Chapter 3 Clinker

Process Diagnosis Handbook

Chapter III: Clinker

Actualization Date: Nov 04 Code DP-03-1

Page 1

Part 1- Clnker. Its design and kiln processes.............................................................................................................3 1.1 Description of the clinker production process................................................................................................................5 Part 2- Combustion, Flame and Heat Balance..........................................................................................................23 2.1 Combustion...............................................................................................................................................................23 2.1.1 2.1.2 2.1.3 2.1.4

Solid Fuels...................................................................................................................................................................................24 Liquids........................................................................................................................................................................................30 Gases..........................................................................................................................................................................................31 Alternates....................................................................................................................................................................................31

3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6 3.1.7

Cyclones towers...........................................................................................................................................................................42 Calciner or fuel burning in the smokes chamber.............................................................................................................................44 Kiln Tube.....................................................................................................................................................................................48 Coolers........................................................................................................................................................................................51 Production Level..........................................................................................................................................................................58 Operational Usage........................................................................................................................................................................59 Electrical Power Consumption.......................................................................................................................................................59

2.2 Flame and burner......................................................................................................................................................32 2.3 Heat Balance.............................................................................................................................................................39 Part 3- Operation and Kiln Control at Regime..........................................................................................................42 3.1 Kiln parts and their functions.....................................................................................................................................42

3.2 Control Variables.......................................................................................................................................................60 3.2.1 3.2.2 3.2.3 3.2.4

What What What What

speed does the kiln must have?...........................................................................................................................................61 draft level does the kiln must have?.....................................................................................................................................65 fuel level is the required one?..............................................................................................................................................67 feeding level does it admit?..................................................................................................................................................68

3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6 3.3.7 3.3.8

Torque or rotation moment (motor amperage)...............................................................................................................................70 NOx............................................................................................................................................................................................71 O2 and pressures..........................................................................................................................................................................71 TV camera, zone temperature, and hot stage temperature.............................................................................................................72 Analytical.....................................................................................................................................................................................72 Exit gas temperature....................................................................................................................................................................73 Kiln view......................................................................................................................................................................................73 Weight/Liter.................................................................................................................................................................................73

3.3 Control Parameters....................................................................................................................................................69

3.4 Control.....................................................................................................................................................................73 Part 4- Kiln control and operation under Special conditions...................................................................................80 4.1 Cooling, heating and kiln start up...............................................................................................................................80

4.1.1 Starting up. Establishment level, and regime recovery....................................................................................................................86 4.1.2 Starting up abacus and kiln recovery.............................................................................................................................................88

4.2 Kiln with a low production..........................................................................................................................................89 4.3 Process protection interlocks......................................................................................................................................95 Part 5- Refractory and Kiln Repairs Protocol ..........................................................................................................96 5.1. Refractory coating....................................................................................................................................................96 5.1.1 5.1.2 5.1.3 5.1.4 5.1.5 5.1.6 5.1.7

Benefits.......................................................................................................................................................................................96 Types..........................................................................................................................................................................................96 Refractory Brick...........................................................................................................................................................................97 Bricks formats............................................................................................................................................................................101 Refractory brick placing systems.................................................................................................................................................102 Refractory life – campaign..........................................................................................................................................................104 Hot spots...................................................................................................................................................................................105

5.2. Refractory Concrete................................................................................................................................................107 5.2.1 Refractory concrete drying..........................................................................................................................................................109

5.3. Refractory Specifications.........................................................................................................................................110 5.3.1 5.3.2 5.3.3 5.3.4

Chemical request – chemical wear...............................................................................................................................................111 Thermal request – thermal wear.................................................................................................................................................114 Mechanical request – mechanical wear........................................................................................................................................116 Kiln tube corrosion.....................................................................................................................................................................119

5.4. Ovalness and kiln aligment......................................................................................................................................122 5.4.1 Kiln aligment..............................................................................................................................................................................123

5.5. Prolonged shut down of an installation (greater than 2 months)................................................................................124 5.6. General repairs protocol..........................................................................................................................................125 5.7 Refractories consumption and campaign durations....................................................................................................131 Part 6- Emissions....................................................................................................................................................133 Appendix A Part I. Potencial composition statement by Bogue.............................................................................143 Appendix B Pare I. Calibration of FRX and DRX equipments.................................................................................154 Appendix A Part II. Combustion.............................................................................................................................160 Appendix B Part II. Heat Balance...........................................................................................................................164 Appendix C Part II. Flame Calculations..................................................................................................................167 Appendix D Part II. System Temperatures Calculation.........................................................................................169 Appendix E Part II. Thermal Conductivity and Insulation.....................................................................................170

Process Diagnosis Handbook

Chapter III: Clinker

Actualization Date: Nov 04 Code DP-03-1

Page 2

Part 1- Clinker. Its design and kiln processes The main objective of this chapter is to expose in a simple and operative way, all those basic concepts to design clinker and to operate kilns in a satisfactory way. Regarding the clinker design, it can not be disconnected from the cement design or the availability or characteristics of the raw materials, but otherwise, as it will be seen ahead, from the raw materials nature a range of possible raw meal / clinker designs will arise, which tested in the cement desing will provide an optimal produced clinker for the cement quality to be commercialized and a total plant cost. The calculation tools which will be described are thought, as in the rest of the chapters, to be simple, of minimum data and easy to obtain, and giving results which allow planning and/or designing. That is why approaches, which can not be seen from a total inoperative point of view, are used, as well as not bibliographical equations empirically obtained which try filling dangerous emptinesses. Kiln Balance Tool

Process Diagnosis Handbook

Chapter III: Clinker

General Repairs Tool

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Process Diagnosis Handbook

Chapter III: Clinker

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1.1 Description of the clinker production process The diagram exposes the main processes involved in clinker production in a dry method kiln.

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Process Diagnosis Handbook

Chapter III: Clinker

Actualization Date: Nov 04 Code DP-03-1

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All the phase formation processes which happen in the kiln are solid-solid reactions (schematized in the previous picture) which will depend on the diffusion speeds. The fastest to diffuse is the calcium, in Ca2+ form, then the aluminum and iron, in form of Al 3+, Fe3+ and, finally, the silica, in SiO 42- form. Without iron or aluminum, the C 2S + CaOL solid-solid reaction which gives C3S is produced over 2000°C. Given the relation between the CaO and SiO 2 molecular weights, it is established that the optimal lime, corresponding to saturation without excess or shortage for the C 3S generation, is: 3 Mw CaO VS 1 Mw SiO2 (Mw = Molar weight) and therefore: Optimal CaO = [3.Mw CaO / 1.Mw SiO2]. SiO2 = 2.8 SiO2 The aluminum presence favors the solids diffusion in this flux, lowering the temperature, which takes place over 1470°C, being the relation for optimal lime: Optimal CaO = 2.8 SiO2 + 1.18 Al2O3 Finally, the iron incorporation lowers the clinkering temperature again to a value around the 1450°C, being the optimal relation between elements: Optimal CaO = 2.8 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3 The 1.18 y 0.65 values are empirical as the phases are not the pure ones which are formulated by Bogue (see Appendix A, p.129)

In this way a relation between the total real lime and the optimal one is established, denominated “saturation degree” which expresses the lime saturation with respect to the rest of elements. LSF (Lime Saturation Factor) = 100 * CaO / CaO optimal. LSF = 100 * CaO / (2.8 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3) As greater the LSF level seeked, more energy will be required for a greater amount of carbonates to be decarbonated, excepting the CaO which comes from other minerals different to carbonates. The inclusion of other elements modifies this Lea&Parker module; so: 

The magnesium presence rises this degree when incorporated (up to 2%) or substituting the calcium in crystal lattices, forming analog compounds to the C3S, C2S, etcetera (M3S, M2S...)



In the other hand, the presence of calcic sulphate in the clinker lowers the lime for the clinkering reactions, so it has to be considered in its stoichiometric relation CaO/SO 3.

In this way, the LSF is corrected to the expression: LSF = 100 * [CaO* + 0.75 MgO* - 0.7 SO3 excess] / [2.8 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3] *Note: Just up to 2% of MgO, since the rest is not incorporated to the clinker phases. If to the total CaO the generated free lime is eliminated, an operative LSF is given, the one the kiln “enjoyed”. The excess SO3 with respect to the alkali.

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This relation between the common elements in all the phases, the CaO, and the rest, can not be characterized by its own, a raw meal or a clinker, being necessary more information relative to the easiness (temperature) to be combined. Then other two modules arise: Silica Module (MS): is the relation between the solids and liquids which favor their diffusion, and therefore will reduce the clinkering temperature.

MS 

C S  C2 S SiO2 Solids  3  Liquids C 3 A  C 4 AF Al 2 O3  Fe2 O3

It is an indirect measurement of the liquid phase porcetange which will be seen ahead. 

Inferior MS to 2.0: generate an excess coating thickness, burning easiness and liquid phase excess.



Superior MS to 3.0: generate a little coating thickness, little liquid phase and high thermal load in order to burn.

Therefore the MS is much related with the kiln temperature at which the clinkering will happen. Alumina Module (MA): is the relation between the two main fluxes, the alumina which melts at high temperatures and the iron which does it at low temperatures MA = Al2O3 / Fe2O3 Therefore the MA is much related with the section of the kiln where this liquid phase will happen specified by the MS. 

Superior MA to 2.3: the liquid phase begins too late (towards the kiln material discharge), the liquid phase will be a viscose one.



Inferior MA to 1.3: the liquid phase begins too soon (towards the kiln material entrance), the liquid phase will be a fluid one.

Summarizing the modules concepts which characterize a raw meal / clinker and the operation in its chemical part (later mineralogy and granulometry will be seen), we get:

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Therefore (without dealing with deatails which will be seen ahead) if the flux (Fundente) usage at low temperatures is abused like the Fe 2O3 and it is compensated with a lowering of Al 2O3 the same L.P. % can be obtained, but gotten at the rear, which will produce premature clinkering with rings formation at the middle of the kiln, and clinker overburning which will rest benefits. As the L.P. expression will show other minority elements are fluxes (Fundentes) at low temperatures, as MgO, K 2O, Na2O and SO3. The formulation of maximum and expected amounts, or phases POTENTIAL, is due to Bogue, who portioned the sotichiometric relation of pure compounds. Knowing how to formulate them and getting to the potential expressions is very important, since the inclusion of new compounds (for example the fluorite) and the compounds which will form, will vary the Bogue formulas and the modules formulation, therefore they will not have an operative validity; this defect is secured raising the new reactions. In the Appendix A part 1, is detailed the development until reaching the Bogue POTENTIAL expressions, as well as an operative formulation for the fluorite inclusion case (F 2Ca), a very high capacity flux(Fundente) which forms a mineralizing pair with the sulfur, speeding up or favoring the C3S formation. Calculations of these potential phases and other behavior data can be calculated in the Raw Meal Design tool. Calculus sheet example

Raw Meal design.XLS

Sheet: Desing and loading plan

Chapter III: Clinker

0.53 Fe2O3 + 5.4 SO3 – 4.59 K2O – 6.93 Na2O – 2.541 Al2O3 C3A = 2.65 Al2O3 – 1.696 Fe2O3 – 10.13 SO3 + 8.61 K2O + 13.06 Na2OC4A3SO3 = 7.62 SO3 – 6.48 K2O – 9.83 Na2OC4AF = 3.04 Fe2O3SULFO-ALUMINOUS CLINKER

Cooking aptitude (BF) (With the new modules)AW = C4AF + C3A + 0.2 C2S + 2 Fe2O3 + 3C2S∙3CaSO4∙CaF2Coatingability coefficient (AW)Clinkering T(°C) = 1300 + 4.51 C3S – 3.74 C3A – 12.64 C4AF – 12 (3C2S∙3CaSO4∙CaF2)

LSF + 10 MS – 3(MgO + K2O + Na2O)Cooking aptitude (BF)AW = C4AF + C3A + 0.2 C2S + 2 Fe2O3Coatingability coefficient (AW)T(°C) = 1300 + 4.51 C3S – 3.74 C3A – 12.64 C4AFRegarding the minimum clinkering temperature

C3S = 4.071 [ CaO – CaO(L)] – 7.6 SiO2 – 4.48 Al2O3 – 2.86 Fe2O3 + Correction by othersC2S = 2.867 SiO2 – 0.754 C3SC2F = 1.7 Fe2O3 – 2.67 Al2O3C4AF = 4.77 Al2O3PORTLAND CLINKER (MA0.64)

2.95 Al2O3 + 2.2 Fe2O3 + MgO* + K2O + Na2O + SO3; For MA>0.64

2.85 SO3 + 3.05 MgO*

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Chapter III: Clinker

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Process Diagnosis Handbook

Chapter III: Clinker

Actualization Date: Nov 04 Code DP-03-1

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Process Diagnosis Handbook

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Code DP-03-1

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It is important to clarify that the evaluation must be done based on the clinker analysis, since this is where other compounds, with no relation with the raw meal, take part, as the fuel ashes. By a natural homogeneity, the marls (tending to the natural raw meal) are more appropiate for the burning than using pure raw materials. This is, for the same material used as a silicic component:

 Better burning High limestone + much clay  Worse burning (because of its little natural initial homogeneity) Limestone marl + little clay

To talk about a clinker analitycal is to talk about its three modules (LSF, MS, and MA) and also about its phases POTENTIAL. The real phases knowledge and their amounts through X Ray Difraction (DRX) allow to connect the kiln with grinding in order to anticipate and calculate grinded cement strength resistances (chapter 4: Cement). Although the range of working values for the modules is based on an industrial strip, the reality is that the clinker design does not begins with its chemical part, but mineralogical, this is (and saving the costs) according to the mineral which constitutes the raw materials for the raw meal, that is how the combination range of modules for getting a quality and operative clinker for the kiln will be. The granulometry will be the last set in order to save the minerals problems, remembering that the kiln processes are physical-chemical, solid-solid, therefore the particule size is especially important, and even determinant. This CHEMICAL-MINERALOGICAL-GRANULOMETRICAL set is summarized in the BURNABILITY or COOKING APTITUDE, which will express how easy or difficult clinkering will result, to a given resultant free lime and a given temperature. Of the two more used methods, one is theorical (F.L.S. method) which corresponds to correlations with empiric data, and other is purely empirical (Polysius method). Both use the free lime concept obtained in a kiln laboratory at a T°C temperature during 30 minutes in order to express its burnability, being the Polysius a several temperatures relation. “Generalized” F.L.S. method (not available in bibliography): CaOF (T°C) = aT * (LSF – LSFT) + bT * (MS – MST) + cT * SiO2 Chemical factor

+45

+ dT * CaCO3 +125 + eT * Aq

mineralogical and granulometrical factor

where: Chemical part: Note: the MA does not influence significantly in the cooking aptitude, as will be seen later. LSF

= raw meal or clinker LSF

LSFT

= LSF reference to temperature T°C: LSFT = 25 + 0.05 T

aT

= temperature adjustment coefficient T°C: aT = 1.71 – 0.001 T

MS

= raw meal or clinker MS

MST

= MS reference to temperature T°c: MST = 0.40 + 0.001 T

bT

= temperature adjustment coefficient T°C: bT = 10.44 – 0.0059 T

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Mineralogical and granulometrical part: a) 20 g. of sample are taken (raw meal) and sieved at 125 m. The retained is evauluated as in its percentage as well as its nature in the following way: Retained % = R

125

125 Seive m

It is analyzed

CaO % in that R 125

by FRX

Obtaining the Calcium Carbonate percentage OVERSIZED, this calcite which has an excessive size will difficult its decomposition; CaCO3 +125 = ( %R125 / 100 ) * [ (100/56) * % CaO

in R125

]

b) 5 g. of sample are taken (raw meal) and sieved at 45 m, evaluating the percentage that is retained (R45.) The retained is tried to dissolve with a chloridric acid dissolution (100 ml water + 20 ml HCl.) It is let boiling for 20 minutes with agitation and then it is filtered. What left as “insoluble residue” (RI) in the filter is dried for 1 hr. at 105 °C and it is weighted to obtain the %RI, and it is analyzed by RX in order to determine the SiO 2 porcentage (it will be the quartz) and the rest (other minerals which are difficult to decompose). So: HCl

%R45

Seive 45 m

%RI Rest (soluble)

% SiO2 Rest = 100 – SiO2

The “oversized” quarts that by its stability and overdimension will difficult its intervention into the reactions: SiO2

+45

=

%R 45  % RI  * % SiO 2 inRI  * 100  100 

Being stables and oversized the rest of the minerals: Aq =

%R 45  % RI  * (100  % SiO 2 inRI ) * 100  100 

And finally the adjustment coefficients are: cT = 5.35 – 0.0033 T dT = 1.87 – 0.0011 T eT = 3.98 – 0.0026 T

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With all these, for example at 1500°C, the burnability will be: CaOF 1500 = 0.21 * (LSF – 100) + 1.59 * (MS – 1.9) + 0.40 * SiO2 +45 + 0.22 CaCO3 +125 + 0.08 Aq If fluorite (F2Ca) is being used, the form calculation can be corrected (empirical not bibliographical): CaOF with F2Ca = (1 – 0.5 * %F2Ca) * CaOF without F2Ca As an example, if a raw meal has: LSF = 95, MS = 2.3 %R45 = 22.6 with RI = 5% (100% SiO2

 Aq = 0)

%R125 = 9.1 with CaO = 46.15 Its theorical burnability is: 1500°C = 1.6

1450°C = 2.8

1400°C = 4.3

1350°C = 6.0

1000°C = 26.1

Polysius Method: Uses as a burnability factor (BF) the following relation between burnabilities (Free lime) tested at different temperatures: BF = 3.73 *

CaO1350  CaO1400  2 * CaO1450  3 * CaO1500 (CaO1350  CaO1500 ) 0.25

Using the previous example, a BF of 53 will be obtained. An approximation of the relation between BF and CaO1500 could be: BF



45 + 14.45 * CaO1500

From the evaluation of the different raw meals it is observed that the importance of the different parameters regarding the burnability is the following: 1) What most affect are the oversized quartz followed by the LSF and the oversized calcite and finally the MS, except this implies quartz movement. 2) The oversized quartz is not reduced significantly with overgrinding, this is, trying to lower this oversized quartz will become uncostable. 3) If the oversized calcite is reduced considerably when overgrinding the raw meal. 4) The Alumina Module (MA) does not affect the burnability, just when there is a low MS has an effect, burning better if the MA is low. Note: the relation alumina/iron (MA) does not affect the burnability in a laboratory kiln (discontinuous operation) but it affects in an industrial one, where the time implies movement (position) along the kiln. 5) The raw meal fine particules just affect a premature nodulation if they are highly contained by clays. The anticipated nodulation would require a greater kiln speed in order to avid ring formations, while the rest of products will require a slower one for their nodulation, having a conflict with the fact that the kiln only has one transmission.

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It is important to clarify that in the laboratory test is observed how from a 5 minutes burning to a 10 minutes one, there is a free lime lowering of 50%, being the tested temperature of 1200 to 1450°C, but from there the change is small, chosing 30 minutes as a secure point for the burnability evaluation. In the bibliography other expression can be found to evaluate the burnability as well as the Ludwig cooking aptitude. CaOF

1500°C

= 0.01 * T

Ludwig

+ 0.7

Where the Ludwig “T” has the following expression: T Ludwig = 55.5 + 11.9 * R96 + 1.56 * (LSF – 90)2 – 0.43 * FL2 With LSF = 100 *

CaO  0.75MgO 2.8SiO 2  1.18 Al 2 O 3  0.65Fe 2 O 3

R96 = raw meal retained at 96 m. LP (Liquid Phase) = 1.56 * ( 3 Al2O3 + 2.25 Fe2O3 + MgO + K2O + Na2O + SO3 ) All the previous for the Ludwing calculation is based on the raw meal analitycal and not on the clinker one. From the practical point of view, it is needed to watch the kiln and to study it stage by stage, but not to the control parameters depth. Z1 – Drying zone: The raw meal humidity degree will affect on the fuel consumption and will be seen when studying the kiln energy balances. Z2 – Clays dehydration zone: The energy (heat) consumed at unbinding the water from the clays, is a small problem as they are easy to decompose and to react. In other words, the SiO 2 parts from the clays are more reactives than the quartz SiO2, as it has already seen at the Quarrys chapter Z3 – Calcination zone: The decarbonation is the most expensive process, thermally talking, of those which happen in the kiln, so all the CaO contributed which does not come from carbonates is an important saving. The decarbonation process can finish before entering the kiln tube in the case of kilns with calciner, keeping in its hot stage very high temperatures (  900°C) which, except in towers with a lot of stages, will derive in a high escape gas temperature and therefore in a thermal inefficiency. In the conventional kilns it happens otherwise, but the decarbonation consumes a lot of kiln meters, leaving less kiln for the rest of the processes, so its production levels are clearly lowered. LOI= 0.786CaO + 1.08 MgO

Z4 – Nodulation zone or liquid phase formation zone or fusion zone: As its name indicates is the zone where the compounds (C3A, C4AF) are formed and when they are fused will form the liquid phase which will favor the CaOF and C2S solids diffusions for their combination in C 3S. In this zone C2S is formed and C3S begins to appear, as nodules which size will depend on the zone length. A bibliographical definition of sintering is, “process which converts melted dust into solids”. The sintering efficiency (Clinkering) is higher when it happens as nodules, so it is very important to nodulize before getting into sintering temperatures. As smaller this zone (small diameter kilns) the nodulation begins

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before so it is easier to find clinker as balls in small kilns, than in those with a bigger diameter, which are very prone to generate clinker dust and also very sensible to MA module changes. Therefore, high flux (Fundentes) levels at low temperatures (Fe 2O3, K2O, Na2O, MgO, SO3) cause early nodulation which can derive in thick coating and large clinker balls formation, and because of this obstruction they can end being enormous, jumping the obstacle and moving forward with danger of damaging the burner. For these reasons, and when these elements levels rise, for example the SO 3 with the pet coke usage must be compensated lowering other element as the Fe 2O3. Thus, the MA relation becomes smaller so the Liquid Phase % must be evaluated at 1338°C and moving the individual element levels according to their relative influences which are contemplated in that expression. For example the relation in clinker of Fe 2O3 with respect to SO3 is 6.1 Fe2O3 vs 1 SO3. The alkali (K2O and Na2O) effects are even more delicated since they are flux (Fundentes) at 800°C, so they can generate selective nodulation at very low temperatures. The inclusion of other fluxes (Fundenetes) as F2Ca must be taken into consideration in the same line, since it seems to work towards the Al2O3 line and, therefore, towards kiln zones closer to the kiln exit. Z5 – Clinkering zone: The formed C3S amount will depend on every factor which affects the extension T C (líquid ) of its solid-solid reaction in a liquid medium (C2S(s) + CaOL(s)    C3S(s)), this is: 1) Relation between the elements (Modules): at higher modules (LSF, MS) higher the C3S potential but worse burnability, so in some cases it is convenient to lower the LSF in order to combine better and rise the C3S.

Kcal/kg

LSF 99 96

99/2.2

96/2.5

MS 2.2 2.5

C3S

2) Residence time: is defined as the necessary permanence time for the obtention of a free lime equal to 2%. This residence time is defined by some authors as: t(min) = 19 * L /(n * D *i) where: L D i n

= = = =

kiln length (m) effective internal kiln diameter, without considering the refractory (m) inclination in % rotation speed of the kiln in rpm

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Other more complete expressions will be seen later. 3) Reaction speed, which depends on: 3.a) Clinkering temperature, being the minimum theorical: Minimum clinkering T = 1300 + 4.51 * C3S – 3.74 * C3A – 12.64 * C4AF In the appendix A it is presented an alternative when F 2Ca is used. It is important not to forget than when the thermal load is very high it results difficult to keep oxidant conditions, being possible to become a reducing condition (Fe 2+) with low strength resistances in cements. 3.b) Liquid phase viscosity. The viscosity increases when the Al 2O3, Na2O, K2O, and MnO are increased and when the F2Ca y Fe2O3, MgO y SO3 is reduced. A viscosity decrement favors the solid diffusion for the C3S formation, but raises the danger of refractory infiltrations. The low surface tension of the liquid phase also favors, being lower as the MgO and the SO3 becomes higher. 3.c) Liquid Phase %. A high L.P. % improves the medium for the C3S formation, so it is improved when raising the Fe2O3, Al2O3, MgO, K2O y SO3. 3.d) The particle size and, therefore, the raw meal granulometry. The size must be the adequate one to the raw materials mineralogy, just as it was seen in cooking aptitude, this is, it will be possible to control by sizes as long as they are not quartz or calcite. The normal values are: Seive ()

% Retained

% Passed Through

297

0.5

99.5

200

0.5 – 5

99.5 – 95

125

5 – 15

95 – 85

90

10 – 20

90 – 80

75

15 – 25

85 – 75

45

25 – 35

75 – 65

Note: being the more recommendable, the finest values of these intervals.

Understanding that one thing is to control by the most operative sieves and other thing is that they are not binded at 45 and 125 m towards the cooking aptitude. In other words, with the complete curve the two sieves which control the raw meal and its relation with 45 y 125 m are determined in order to go from its desired values into equipment control values in other sieves. Therefore the resuides at 45 y 125 m can be controlled, controlling a specific sieve, usually the 75 or 90 m. As an example it is shown common relations of raw meal: P45 = 0.077 * P751.55

P45 = 0.0018 * P902.37

P125 = 12.2 * P750.46

P125 = 3.88 * P900.71

In the other hand, the relation between liquid phase or flux(Fundente) and the raw meal avergae size is very importat in order to characterize the expected at nodulation.

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Raw Meals Behavior 1.- FL1338 = -0.04Φ50 + 28 2.- FL1338 = -0.02Φ50 + 30

% F.F. 28 20

3.- FL1338 = 0.0075Φ50 + 8

A

4.- FL1338 = 0.0435Φ50 -1.75

1338

=

3 B

8

Note: FL

1

2 C

40

A: Effective nodulation (Nodules)

D

B: Incomplete nodulation (Dust)

D

C: Sticky Raw Meal D: Paste or suspension

4 E

200

E: Melted raw meal

500

 50 (m)

6.1  Fe2 O3  MgO  K 2O  Na 2O  SO3 MA  1.38  8.2  Al O - 5.22  Fe O  MgO  K O  Na O  SO MA  1.38  2 3 2 3 2 2 3

Example: Having a raw meal with a Φ50=21 microns which generate a clinker with LP 1338 = 26% will be between the curves 1 and 3, and therefore, in the area A of “Effective nodulation”.

Note: Seive that retains and let pass a half of raw meal. Φ50 = e(50-)/By RRSB approximation b = Rx – a*Ln (x) a = R y - Rx Ln(y) – Ln (x) Seive Y (m) > Seive X (m) Rx = retained in X m

Ry = retained in Y m

If there is not a granulometer, the approximation for the raw meal can be: Φ50 = R75 – 2 = R90 + 2 The raw meal use to have an average diameter of 10 to 25 , in the white raw meals around 10  and in the gray ones 15 to 25 , so, in order to get an effective nodulation, their liquid phase must be around 23 and 28 %. With all these it can be seen that the election of an adequated chemistry for a given mineralogy, is not something limited in selecting the three modules, or electing it trying to get a maximum Bogue potential, since there is a point where the LSF relation, for a given MS, with the calorific kiln consumption becomes exponential, needing to know the economic limit for the C 3S (which use to be a LSF of 95 to 99) and in that search it is important to clarify that movements in MS decimals are equivalent, in burning hardness, to LSF points. This is, as some authors have described the chemical burnability as: AS (Sintering aptitude) = LSF + 10*MS – 3*(MgO + K 2O + Na2O), between 100 and 120 with ideal 108. So in order to keep the same burnability, if a MS decimal is incremented 1 LSF point must have to be decreased.

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In the other hand, it is important not to forget that in all these movements, the coating profiles may vary in thickness and position, being important, the coating and the assurance of the kiln campaing, at the time of selecting the modules. So, a MS above 2.5, besides difficulting the burnability by flux shortage and generating a dusty clinker (which effects will be seen ahead), causes a little coating. This high thermal load which forces a high MS is less important in calciner kilns, since the works between tube and tower are better distributed. Despite the kiln operation with high MS’s becomes more difficult. For the cases on wich there is a flux shortage at the zone and require to operate with higher LSF’s and MS’s, it is recommended to use fluorite, which added in very small amounts, will generate great liquid phase as it will be seen ahead. On the contrary, low MS modules (< 2.0) besides favoring the operations at low thermal load, produce a very granulated clinker, or even with big balls formation, hard to grind and a lot of coating which not only uses free tube section and therefore production capacity, but also the coating weight lowers the refractory life and the kiln gets instable due to continuous coating formation-falling cycles. In bibliography is commonly used as coating coefficient (AW), the following expression: AW = C3A + C4AF + 0.2 C2S + 2 Fe2O3 (*note: C2F in case of MA < 0.64) Being normal AW’s between 20 (less becomes a shortage) and 35 (higher forms excessive coating). Or the Turbain coating index ic: ic = 2.8 (SiO2 – 20) + Fe2O3 If ic < 7 it is difficult to generate coating, being the optimal between 10 and 15. The coating formation aptitude is a relation binded to the MA because it is very influenced to the refractory material adhesion at the Fe2O3 level. Therefore a low MS and a little Fe 2O3 (high MA) produce a greater kiln instability since any MA movement will generate a great change to the material amount which incorporates or leaves the coating. Therefore the MA plays a very important role, being its recommended levels close to 1.63 since at that relation is when all the Fe2O3 and Al2O3 melt at the lowest temperature of 1338°C when constituting the EUTETIC. Above 1.63 all the Fe 2O3 melts at that temperature, but not all the Al 2O3, and under that value the opposite happens. Z6 – Cooling zone: The importance of an effective cooling at the freezing of the reversible reaction of C3S formation has already been seen. Lowering the formed clinker temperature as fast as possible until 1170°C will allow cristallizing the liquid phase and catching C3S phases formed and the C2S and CaO without combine, not letting the reaction to be inverted. If there is a very slow cooling the decomposition will be done and secondary C2S and CaO will be generated, in the C2S case it will not be in a structure with resistances potencial, as in the  (beta) phase, but it will be transforme into  (gamma) which is stable under that temperature and does not have hydraulic properties. According the bibliography, this cooling speed is more critical in the case of actived clinkers with fluorite.

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It is industrially assured, excepting operations cases extremely punctually rarified, as in grates coolers as well as in satellites ones the freezing is effective, being more risky in the satellites ones since the exchange is worse and because the cooling begins before already at the kiln tube. The theory establishes that as faster is the mentioned cooling: 

The crystal sizes are smaller and with a greater tension accumulation, which will make easier the clinker grinding.



The C3S mineral is bigger when its formation reaction gets frozen more effectively.



More MgO is incorporated to the clinker phases, leaving less as free expansive magnesia. It is verified that as a result of a fast cooling, the MgO solidifies in glassy state in very small sizes (< 5) which not generate expansive phenomenons in cement. Otherwise, by slow cooling, will adquire bigger sizes that will affect.



The C3A is less reactive to the setting, decreasing the fast setting or flash tendency.

Also it is true, that at industrial levels there are few justified differences on the cooling type, while in laboratory tests, testing different cooling speeds, the informations (provided by articles) are contradictories even more in terms of C3S amount. As in the flame, regarding its easiness of transmiting heat by radiation, as well as cooling, regarding the heat exchange effectiveness between air and clinker, are very affected the dust level in the clinker, mainly in kiln with satellites coolers, proner to reintroduce in the kiln the clinker dust. That dust does not only interfere in the kiln making it to consume more fuel, but also inestabilize the coating, trying to increase the product losses in open warehouses and in this clinker rehandling. The size or classification by size in the clinker use to be expressed in terms of high dust level, understanding this as the one formed by particules smaller than 1mm, being a habitual classification: % passed through 1 mm

Clinker type

80

Only dust

Very dusty

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Being an optimal clinker, under this premise, the one that pass through 1 mm in the order of 15 to 20%. From the clinker grindability point of view, the bibliography is very contradictory, just agreeing in a general rule: At higher quality, beter grindability. This is, the grindability improves when increasing the C3S % and decreasing the C2S %, when reducing the alite (C3S) and belite (C2S) size and when reducing the liquid phase, some bibliography indicates that the MgO is a grindability facilitator. The clinker density (if porouser better) and the pores distribution (as more distributed better) play an important role, and in this aspect a wrong raw meal homogenization will cause clinkers to be harder to grind. An excess of liquid phase will increase the density and with it the grinding will be harmed, also the overburning and larger and weaker flames which enlarge the belite and CaO (F) crystals forming fewer alites and with a bigger size. According the bibliography the alite particles size is smaller when the lime content in the raw meal is higher and when it is finely grinded. Not confirming in all cases that the cement strength resistances increase when decreasing the alites size, and if happens, is at early ages and not at late ones. Regarding the duration and temperature at the sintering zone, the crystals “usually” become bigger since they have greater residence times and greater temperatures, the term “usually” is used since other authors, the duration (greater residence time) at the preparation zone (800 °C – 1300 °C) generate big crystals, but in the sintering zone (1300 °C – 1450 °C) are generated small ones, therefore a balance is constituted. For all these aspects the microscopy has generated much information: Microscopy and crystals size. Ono Method. Operative parameter Heating speed: by alite size (C3S)

Fast: 15 to 20 m

Slow: 40 to 60 m

Burning time: by belite size (C2S)

Long: 25 to 40 m

Short: 5 to 10 m

Burning temperature: by alite birefringence

High: 0.01 to 0.008

Low: 0.005 to 0.002

Fast: light

Slow: amber

Cooling speed: by belite color.

Definitely, in order to get quality and grindability it is needed to control the following points: 1. Intense and short flames, difficult and unnecessary in big diameter kilns with calciner, therefore it is better to say: “There is no interesting in too large and loose flames”, “There is no interesting in too slow heatings and coolings”. 2. High LSF and MS modules (LSF > 95 y MS > 2.2) and relatively low MA (< 1.6). % grindability ≈ f( C3S %) 3. Small raw meal particule sizes (Φ50 < 25), “Savings on the raw meal mills will reflect on expenses in the kiln and cement mills”

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The microscopy technic gives and excellent investigation work to specific problems, but not, for the control of the calcining procces for which, technics as the DRX give more benefits. Concluding this section, it not easy to determine a priori which is the more convenient clinker to produce in a specific installation in a given geographical point, here is a scheme that might help:

It is important not to forget the importance of the chemical part, mineralogical and granulometical stability chosen finally (LSF < 1, MS < 0.05,MA < 0.05, P75 < 1, constant minerology) To accentuate the importance that the mineralogy has in the cooking aptitude, it is presented the following study done by RDX vs. Cooking Aptitude Test, on which the different hardness are shown based on the presence of different minerals, as: the ordered calcic albite, which as not being considered bibliographically as a hard mineral towards the calcinations process, opens a whole investigation line through the minerals identificaction and quantification.

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So, the new way to talk about (new language) a raw material, will not only be by its chemical composition, but also mineralogically, as the following phrase: silicic component denominated Sandy Mud, of chemical characteristics: SiO2 = 61.76 MS = 2.78 withouht harmful components; and of mineralogical characteristics: Tufa with a %x of ordered calcic albite (from the Feldspar family) which confers a high burning hardness. (Note: being x the semiquantitative percentage that will determine the DRX equipment software) With this information, this silica corrector not only will not allow reaching high MS modules without other corrector, and besides it will contribute to the raw meal a bad cooking aptitude.

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Regarding the mineralizers: are those which, besides being normally fluxes (lowrering the fusion temperature of the liquid phase), are capable of activating or accelerating the formation of the C3S mineral, being one of its mechanisms to lower the liquid phase viscosity favoring the solid-solid reaction, this is, CaO F – C2S (the binds with K, Na favor the penetration attacking the brick at temperatures around 1450°C, causing corrosion at the high transition). Some of these mineralizers are fluorides CaF2 (1350°C, shellphous), MgF 2 (1350°C), SrF2 (1190°C), BaF2 (1285°C), alkalines or alkaline-terreous (see periodic table), P 2O5, Cr2O3, MnO and also seem to be the sulfides (BaSO 4, CaSO4- CaF2) and chlorides (CaCl2, 773°C). That is where the mineralizer “pair” F 2Ca+ CaSO4 rises, which in a 8:1 proportion (in clinker) allows that little amounts of F 2Ca be mixed with CaSO4 and C2S, forming compounds with a high molecular weight and therefore generators of great liquid phase amount. From these, the most used, because of its abundance, is the CaF 2 or fluor-spar, which added to raw meal with a liquid phase deficit, in low proportions (0.2 % – 0.4 %) they generate new phases (3C2S ٠3CaSO4 ٠CaF2, C11A7CaF2) which give a great liquid phase amount, facilitating a higher conversion to C3S, being of great utility for raw meals with a high LSF and MS as well as quartz presence (see appendix A part 1). The CaF2 behavior is not linear, this is, below the 0.2 % does not offer benefits and neither above 0.6 % (Except with high SO3 levels), besides being detrimental above the 0.6 %, it instables the C 11A7F2Ca phase in the clinker and generates low strength resistances and cracks the dough as a “Crocodrile skin”. There are other mineralizers which on the contrary are detrimentals, as the phosphates. The El P 2O5 is a mineralizer which stables the C2S being difficult its transformation to C3S.

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Part 2- Combustion, Flame and Heat Balance. In this section, it is tried to expose briefly the most essential conepts and to give a calculation tool, which will only ask for simple data of easy obtentainment, leaving the appendixes to describe the calculation models.

2.1 Combustion It is the combination of fuel with a combustive agent or oxidant (typically air) in order to generate heat. The main involved reaction is the carbon oxidation to carbon dioxide, always passing through carbon monoxide. C + O2



CO2

94 Kcal/mol (Exothermic)

The reaction might not be completed by different causes as: Oxigen shortage: C + ½ O2



CO

26.4 Kcal/mol (Exothermic)

This reaction is a low exothermic one and may have an explosion risk. An excess oxigen may suffocate the flame and generate CO presence. Contact of the incandescent carbon (activated) with other compounds generated at the combustion or present in the environment: Combustion gases: C + CO2

 2CO

-41 Kcal/mol (Endothermic)

Humidity: C + H2O



CO + H2

-31 Kcal/mol (Endothermic)

Calcium carbonate to be decarbonated: C + CaCO3



CaO + 2CO

-84 Kcal/mol (Endothermic)

These last three reactions, as being endothermic, entail an energetic efficiency lost. The other 2 combustion reactions which follows in importance are the hydrogen ones (H 2 + ½O2  H2O 58 Kcal/mol) and the sulfur ones (S + O2  SO2 71 Kcal/mol), which are exothermics. The fuels used in the cement industry are derived from organic compounds (Coal) and petroleum (Coke, Fuel Oil and Gas) and they are divided by their physical state in Solids, Liquids and Gases where the different alternate fuels will be included. The hydrocarbons amount and therefore the C/H relation is determinant in order to classify the combustion difficulty: Solids C/H >> 8 (more difficult to combust) Liquids C/H ≈ 8 Gases C/H ≈ 3 (less difficult to combust)

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Having each one different flame characteristics: Flame Fuel

Particule Size

Length

Luminosity

Emisivity

Natural Gas

Amströng

Short ≈ 15 m

Little

Low

Fuel Oil

Microns

Medium ≈ 20 m

Much

Medium

Coal/Coke

Microns

Long ≈ 25 m

Very Much

High

In the other hand the air has a main composition of 79 % N 2 and 21 % O2 in volume percentage and 77 % N2 and 23 % O2 in mass percentage.

2.1.1 Solid Fuels a) Coal The coals are composed of an aromatic part (High carbon percentage) and other hidrocarbonic part called “Bitumen”, which binds the aromatic part.

As the coal gets older, it loses its “Bitumen” through the following process described by Mackenzie & Taylor: Wood: CH4 lost in acid and anaerobic medium

Turf Lignite Soft Coal Anthracite

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In order to difference them, 2 types of analyses are done: Ultimate analysis: Determination of the coal chemical compostion analyzing the carbon, hydrogen, nitrogen and sulfur percentage. From this analysis the Low Heat Value can be obtained according reception (LHVSR) through the following formula: PCISR = 7838 (%C/100) + 28899 (%N2/100) + 2218 (%S/100) – 584 (%H2O/100) (Kcal/kg) Example: A coal with the next compositon: % C = 69.0 % N2 = 1.44 % S = 1.29 % H2O = 5.0 % Ashes = 23.27 (ashes: inorganic not combustible components: CaO, SiO 2, Al2O3,P2O5, etc.) Will have an approximate Heat Value LHV = 5824 Kcal/kg. Proximate analysis: Determination of the humidity percentage and once the material gets dry the ashes, volatile and fix coal amounts can be determined. This kind of analysis is complemented with the sulfur percentage (by its effect in the process), the hardness (by Hardgrove method) and the calorific power evaluated in a calorimetric pump Soft Coal or Bituminous Coal Lignite

¾ greasy

½ greasy

Greasy

Anthracite

Coke

Total Humidity

10 - 25

2–6

2-6

2–6

Balls Mills That is why the balls mills complied better with cokes or coals changes. According to the kiln combustion a grinding fineness will be seeked in function to the volatile (which are the first to burn) with the following approximation: % passed through 90 microns = 100 – 0.50 * % volatile % passed through 75 microns = 100 – 0.85 * % volatile

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The combustion process is a physical – chemical process, where the speed on which the heating liberation and volatile ignition happen and the coke or coal combustion depend on the particule size. CO – CO2

Ignition Pyrolisis1 The bitumens Volatile are liberated burn as gases (volatile) Tignition = 300 °C 100 ms

Heating 50 – 100 ms

O2

Coal combustion 1s

The burning time is a direct function of the average particule diameter (d 50), wich oscillates between 20 and 30 (m). Since the obtention of fine fraction is difficult in cokes, it is recommended to use as working sieve, one not superior to 75 microns, being recommendable to observe the particule d 50 as a fineness indicative. The solid fuel grindability depends on, the coal age and the cracking process from which the coke was obtained. In the coal, as getting older, the bituminous part begins to be lost, until reaching the anthracites with low content of volatile and high hardness. In the coke case, these can be produced by batches (Delayed), giving as result a varied result, depending on the cracking time, with HGI hardnesses (Hardgrove Index) between 35 and 70. The fluid coke (or Flexicoke) is produced continuously and it is harder, with a HGI below to 40. The fuel composition is important to define the oxidant amount to be used in order to obtain a complete combustion (stoichiometric O2, stoichiometric air); a) By elemental analysis % MassDB

Kg Minimum air/Kg fuel

Nm3 Minimum/Kg fuel

%C

11.42*%C/100

8.83*%C/100

%H2

34.33*%H2/100

26.55*%H2/100

%S

4.28*%S/100

3.31*%S/100

%O2

- 4.29*%O2/100

-3.31*%O2/100

Amin

Sum

Sum

b) In an approximate way by low heat value in dry base (Expressend in Kcal/kg) Minimum air or stoichiometric (Nm3/kg fuel): Amin = 1.01*PCI/1000 + 0.05 Gases volume of stoichiometric combustion (Nm3/kg fuel): V0R = 0.89*PCI/1000 + 1.65 (With a composition of 18 % of CO2 + SO2) The excess air with respect to the stoichiometric minimum one (Lamda, λ) varies the total amount of available air for the combustion: 1

Pyrolisis: heat breakage

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Total Air Atotal = λ * Amin Total volume of combustion gases VRtotal = λ * V0R With an approximate density of the combustion gases of 1.5 – 0.01*(%O 2) (Kg/Nm3) λ = 1/[1-(79*O2)/(21*N2)] (Requires orsat analysis N2 = 100 – %CO2 – %CO - %O2) λ = 1+0.09*(%O2) (%O2 = Oxigen excess, there where the λ is being evaluated.) In order to expose them in terms of clinker kilograms, the relation between the fuel calorific power and the kiln specific consumption must be multiplied: VR (Nm3/kg clinker) = VR (Nm3/kg fuel) * (CEH/PCI) (Kg clinker/kg fuel) CEH = specific heat consumption (kcal/kg clinker) Finally, and as a necessary heat balance data, the specific heat under constant pressure (Cp) for coal and coke is: Cp = 0.262 + 390x10-6 T(°C); Kcal/kg°C T = coke temperature/coal fed to the burner Also, the dew points for the combustion gases vary, because of the hydrogenated volatile levels, of 50 °C for lignites and 30 °C for anthracites and coke; and for the last ones less temperature will be required at the collector to avoid condensations.

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2.1.2 Líquids The most common is the fuel oil. They are hydrocarbons of very close composition for diesel, light and heavy oil. % C ≈ 86, % H ≈ 12, % S ≈ 2. The densities ρ have important variations which not differ a lot with the temperature: Deisel oil ≈ 0.88 g/cm3 Light oil ≈ 0.9 g/cm3 Heavy oil ≈ 0.95 g/cm3 However the heat value of different types can be related according their density through the following formula: LHV (Kcal/kg) = [12400 – (2100* ρ2)] – 800 Regarding the minimum air, even if it is too close to the 11 Nm3/kg fuel it can be expressed as: Amin (Nm3/kg fuel)

= 10.8*(LHV/9750) = 0.85*(LHV/1000) + 2

V0R (Nm3/kg fuel)

= 1.11*(LHV/1000); with an approximation of 14 % CO2 + SO2

The ignition viscosities and temperatures are very bound: Viscosity (Cst)2

Ignition T °C

Deisel oil

< 10

< 30

Light oil

10 – 60

30 – 50

Medium oil

60 – 150

50 – 60

Heavy oil

> 150

> 60

Being very important the viscosity variation with the temperature towards a good atomization and therefore a good combustion. Then, if a heavy oil at 120 °C has a viscosity (3°E ≈ 23 Cst) in the range of the light oils, which allow to be transported and injected at a working pressure of 35 – 40 Kg/cm 2 will generate, by an adequate atomization, an adequate flame for the kiln. Other characteristic of other fuel kinds is the dew point of their combustion gases very close to 50 °C. The specific heat under a constant pressure Cp is approximately: Cp = (0.403 + 0.008*T)*(1/ ρ0.5), (T = Temperature in °C and ρ = density in g/cm 3 at 15 °C)

2

Cst: centi-stockes

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2.1.3 Gases The most used are the natural gases, which in this case vary highly in composition and properties. Regarding the composition this can be expressed in: %CH4 (Methane) (80 % – 95 %) %C2H6 (Ethane) (2 % - 10 %) %C3H8 (Propane) (0 % – 3 %) %C4H10 (Butane) (0 % - 2 %) Being their heat values, expressed in Kcal/Nm 3 gas, in the order of 7000 – 10,000 Kcal/Nm 3 (Natural Gas 8450 Kcal/Nm3). The minimum air is in a range of 10 – 14 Nm 3/Kg gas, being able to be calculated in function of its low heat value in the following way: Amin = 1.09*LHV/1000 + 0.25

Nm3/kg gas

And its volume of stoichiometric combustion gases V0R = 1.14*LHV/1000 + 0.25 Nm3/kg gas; (With a CO2 percentage in the smoke gases in the order of 10 % and a approximate dew point of 60 °C.) Finally and as a simple rule (not very precise), valid for solids, liquids and gases, the stoichiometric minimum air and combustion gases for each 1000 Kcal is: Amin/1000 Kcal = 1.4 Kg/Kg fuel or 1.1 Nm3/Kg fuel V0R/1000 Kcal = 1.5 Kg/Kg fuel or 1.2 Nm3/Kg fuel Natural gas density at 20°C and 1 atm is 0.694 g/cm 3 2.1.4 Alternative Fuels The alternative fuels judgment entails not only thecnological and economical aspects, but also the enviromentals (Legislation) and socials (Communities), as it will be seen in part 6. a) Liquid Alternative Fuels The main points to consider are: 



Heat Value o

Motor oils ≈ 9600 Kcal/kg

o

Dissolvents ≈ 9000 Kcal/kg

Viscosity: must be below 300 cst, depending on the transport method and nebulization (Atomization) o

Water percentage: Must not surpass 0.0005 Kg water/MW of burner

o

Particles in suspension.

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b) Solid Alternative Fuels Size (mm)

Substitution % Max.

Polyolephines (Polyethylene and polypropylene)

24 + 7*(100 - % usage) + 100 CAMPAIGN DURATION The campaign duration may be expressed in function of the most important factor, the thermal load (CT) due to the main burner. Duration (months) ≈ 770 * CT

-2.64

Remebering other expressions already given: C (g/ton) = 28 x 2 Duration (days) = 5840 / 2

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Part 6- Emissions Although in this section the emissions to the atmosphere subject will be intensely seen, also a global view of the points that must be taken care of when pollution is being considered, remembering that the applicable norm must be fulfilled at each case.

a) Pollution signs in materials: ppm in: As (Arsenic) Be (Beryllium) Cd (Cadmium) Cr (Chrome) Hg (Mercury) Pb (Plumb) Se (Selenium) Te (Tellurium) Tl (Thallium) V (Vanadium) Ni (Nickel)

Raw Meal 10 – 50 0.8 *100 I(34.2°)

I(34.2°)100 I(34.2°)80/20

((80%Clk / 20% Poz)

(100%Clk)

angle C3S (34.2°)

I

Corrected situation (by background noise): I(34.2°)80/20 - I(17°)80/20 = 0.8 * (I(34.2°)100 - I(17°)100 ) I(34.2°)100 I(34.2°)80/20

((80%Clk / 20% Poz)

(100%Clk)

angle Background (17°)

C3S (34.2°)

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And so on for the other angles (phases). The selected peaks must have a enough curvature for the detection (and counting) of the maximum point. Very intense and narrows peaks, are not interesting, facing stability and reliability. In the other hand, the peaks (2 Θ) selected for the phases must be free of interferences by the additions and the gypsum, that is why it is recommended the following angles (for tubes with a copper anode): C3S : 34.2 Y 41.2 C3A : 33.2 C4AF: 33.8 C2S : 30.9 For the free lime (DRX vs. chemical method), the primitive straight line is built with kiln clinkers, taking andvantage of kiln situations of bad burning, for the high point and the objective clinker as the low one. Cx (free lime): 37.3 VERY IMPORTANT NOTE: through time, the equipment will displace the diffractograph, that is why it has to be accompanied with a displacement of the angle that is going to be measured.

41.1

41.2

41.3

41.1

41.2

41.3

41.2

41.3

41.4

“ALSO IT MUST BE TAKEN CARE OF THE PATTERNS RENOVATION” Other commentaries: In case of cements added with limestone, the CaCO 3 quantification by DRX (calibrating previously intensity vs. lost of ignition) allows having LOI of the produced cement without needing the adquisition of other fast evaluation equipment (for example: LECO). Note: CaCO3 at 43.1 / 47.4 / 48.5 / 39.4 angles. For the gypsum case, what refers to quantify the dihydrated, hemhydrated and anhydrite percentage, DRX constitutes a good support for antincipating (before grinding or during) or antincipating for false setting problems. Dihydrated: 11.7 Hemihydrated: 14.7 Anhydrite: 25.8.

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Appendix A Pare II. Combustion Calculations for the stoichiometric air Table 1 FUEL

AIR

CO2

ELEMENT

WEIGHT %

C

86.0

9.818

H2

10.5

3.605

S

3.5

0.1502

TOTAL

100

13.5732

H 2O

SO2

3.154

7.542

10.696

2.765

3.71

0.07

0.1152

0.1852

0.07

10.422

14.59

0.945

3.154

0.945

CARBON COMBUSTION C + O2 Kg C + Kgmol C

CO2

32 Kg O2 Kgmol

44 Kg CO2 Kgmol CO2

Dividing between 12 for reducing in carbon base, we have: 1 +

Total Stoich. gas

TABLE CONSTRUCTION

12

N2

2.667 Kg O2

3.667 Kg CO2

Kg C

Kg C

Multiplying by the percentage in weight of the carbon in the fuel, we find: O.86 Kg C Kgcomb

X 3.667 Kg CO2 = 3.154 Kg CO2 Kg C

Kg comb

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Actualization Date: Nov 04

Chapter III: Clinker

Code DP-03-1

Using air instead of O2: O2 +

N2

AIR

% MASS

0.233

0.767

1

O2 BASE

1

3.29

4.2918

C + 2.66 (4.2918) AIR

3.66CO2 + 2.66(3.2918) N2

C + 11.4168 AIR

3.66 CO2 + 8.77 N2

Substituting: 11.4168 X 0.86 = 9.818 Kg air Kg comb. 8.77X 0.86 = 7.542 Kg N2 Kg comb.

HYDROGEN COMBUSTION H2 + 1/2 O2 2

Kg H2 + Kgmol H2

H2O

16 Kg O2

18 Kg H2O

Kgmol O2

Kgmol H2O

Dividing between 2 to reduce in hydrogen base, we get: 1 +

8 Kg O2 Kg H2

9

Kg H2O Kg H2

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Multiplying by the percentage in weight of hydrogen in the fuel, we find: O.105 Kg H2

X 9.0 Kg H2O = 0.945 Kg H2O

Kgcomb

Kg H2

Kg comb

Using air instead of O2:

O2 +

N2

AIR

% MASS

0.233

0.767

1

O2 BASE

1

3.29

4.2918

H2 + 8 (4.2918) AIR H2 + 34.334 AIR

9 H2O+ 8(3.2918) N2 9 H2O + 26.334 N2

Substituting: 34.334 X 0.105 = 3.605 Kg air Kg comb.

26.334 X 0.105 = 2.765 Kg N2 Kg comb.

SULFUR COMBUSTION S + O2 32

Kg S + Kgmol S

32 Kg O2 Kgmol O2

Dividing between 32 to reduce in sulfur base, we have:

SO2 64 Kg SO2 Kgmol SO2

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1 Kg O2

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Page 169

Kg SO2

Kg S

Kg S

Multiplying by the percentage in weight of sulfur in the fuel, we find: 0.035 Kg S

X 2.0 Kg SO2 = 0.07

Kgcomb

Kg S

Kg SO2 Kg comb

Using air instead of O2: O2 +

N2

AIR

% MASS

0.233

0.767

1

O2 BASE

1

3.29

4.2918

S + 1 (4.2918) AIR S + 4.2918 AIR

2 SO2+ 1(3.2918) N2 2 SO2 + 3.2918 N2

Substituting: 4.2918 X 0.035 = 0.1502 Kg air Kg comb. 3.2918 X 0.035 = 0.1152 Kg N2 Kg comb. EXPLANATION OF THE COLUMNS IN TABLE 2 The total of the 3rd column represents the stoichiometric air amount needed to burn 1 kg of fuel oil. While burning the fuel oil transforms totally into gases (CO 2, H2O, etc.), 1 Kg of fuel oil produces 1 Kg of gases. The Kg of gases are added to the 13.57 Kg of stoichiometric air, finally, the total amount of stoichiometric combustion gases (GT) is: table 1, column Total.

 Kg  GT  13.57  1kg fuel  14.57  Gases   kg Fuels 

Appendix B Part II. Heat Balance The heat balance is based on the heat flows of the the different components that leave and enter the system starting off the base Incomes = Outcomes. Next it is presented a table with the calorific capacities of the main compounds based on the next formula:

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Page 170

Cp = a + b * 10-6 * T + c * 10-9 * T2 (Kcal/kg °C) (T in °C) A

b

C

CO2

0.196

118

-43

H2O

0.443

39

28

N2

0.244

22

0

O2

0.218

30

0

Air

0.237

23

0

Escape Gas (T in °K)

0.306

58

7.96

Raw Meal

0.206

101

-37

Clinker

0.186

54

0

Coal/Coke

0.262

390

0

Note: The temperatures are always in °C unless other is indicated. Heat losses QLosses = QClinker + QCooler + QTower + QKiln + QDuct 3° + QEscape Gas+ QExcess Air + QDust + QReaction + QCO + QResidual Air Clinker Latent Heat (Kcal/hr) QClinker = mClinker*CpClinker*TClinker Radiation and Convection (use T in Kelvin degrees) A = exterior Areas which will be evaluated in m2. Temperatures in Kelvin degrees T = T °C + 273 Radiation (Kcal/hr m2): hRadiation = 0.000000042*(TSuface4 – TAmbient4) Convection (Kcal/hr m2): hConvection = 80.33*(( TSurface + TAmbient)/2)-0.724 *( TSurface - TAmbient)1.33 Cooler (Kcal/hr) QCooler = ACooler * (hRadiation + hConvection) Cyclones Tower (Kcal/hr) QTower = ATower * (hRadiation + hConvection)

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Kiln Shell (Kcal/hr) QKiln = AKiln * (hRadiation + hConvection) Tertiary Air Duct (Kcal/hr) QDuct 3° = ADuct 3° * (hRadiation + hConvection) Latent Heat of: Escape Gas (Kcal/hr) (Including Excess Air) QEscape Gas = mEscape Gas*[CpEscape Gas*(1-(%Excess Air/100)) + CpAir*(%Excess Air/100)]*TEscape Gas mEscape Gas (Kg/hr)= ρEscape Gas * VEscape Gas ρEscape Gas (Kg/ Nm3)= 1.4 – (0.005*%O2) (Tower Exit) VEscape Gas (Nm3/hr)= 1.25 * mClinker / (1 - %Excess Air / 100) mClinker in Kg/hr %Excess Air = %O2 (Tower

Exit)

/ 0.21

Excess Air QExcess Air = mExcess Air*CpAir*TEscape Gas (Kcal/hr) mExcess Air = ρAir * VExcess Air ρAir = 1.29 kg/Nm3 -air normal densityVExcess Air = VEscape Gas * %Excess Air /100 Escape Gas (Kcal/hr) (Without Excess Air) QEscape Gas without excess air = QEscape Gas - QExcess Air Dust Latent Heat not recovered by Cold Stages (Kcal/hr) QDust = mDust*CpDust*TDust MDust = mClinker * (HC/Ck) * (1+ %Dust/100) * (%Dust/100) %Dust= % of raw meal that escapes to the cold stages Where (HC/Ck) is the conversion from raw meal to clinker stoichiometrically. Heat reaction (Kcal/hr) QReaction=(7.646*%CaO+6.48*%MgO+2.22*%Al2O3–5.116*%SiO2–0.59*%Fe2O3–10*%K2O+Na2O *mClinker Residual Air Latent Heat(Kcal/hr) QResidual Air = mResidual Air CpAir*TResidual Air mResidual Air = ρAir * VResidual Air VResidual Air = VTotal Air - VTertiary Air + Secondary VTertiary Air + Secondary = VExcess Air + VStoichiometric Air VExcess Air = VEscape Gas * %Excess Air /100

+11.6*%H2O)

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Page 172

VStoichiometric Air = 1.09 * CEH / 1000 Note: CEH is the specific kiln consumption iterating from 800 Kcal/kg for gray clinker and 1500 Kcal/kg for white clinker. CO presence at the precalciner exit (Kcal/hr) QCO = 32 * %CO * mClinker Heat Incomes Raw Meal Latent Heat (Kcal/hr) QRaw Meal = mRaw Meal*CpRaw Meal*TRaw Meal mRaw Meal = (TPDclinker * 1000 / 24) * 1.56 Note: 1.56 for raw meal of habitual LOI. Fuel Latent Heat (Kcal/hr) QFuel = mFuel*CpFuel*TFuel mFuel = (CEH/PCI dry base) * (TPDclinker * 1000 / 24) , Note: CEH (Kcal/kg) to iterate or a approximated value of the installation, since the contribution of Q Fuel to the balance is too small. Total Air Latent Heat (Kcal/hr) QTotal Air = mTotal Air*CpTotal Air*TTotal Air MTotal Air = ρTotal Air * VTotal Air Return Dust to the Cyclones Tower Latent Heat (Kcal/hr) QReturn Dust = mReturn Dust*CpReturn Dust*TReturn Dust Combustion Heat (Kcal/hr) Qcombustion = QLosses – QRaw Meal – QFuel – QTotal Air – QReturn Dust Calculation of the relation Nm3 a m3 Nm3 = m3 * (273 / (273+T)) * 13.6 * 760 * e-0.0001255 * H /10333 Where, T in Celsius degrees H in meters over the sea level

Process Diagnosis Handbook

Chapter III: Clinker

Actualization Date: Nov 04 Code DP-03-1

Appendix C Part II. Flame Calculations Minimum air (Nm3/Kg fuel) AminSolid = 1.01*PCI/1000 + 0.5 AminLiquid = 0.85*PCI/1000 + 2 AminGas = 0.875*PCI/1000 Stoichiometric Relation λ = 1 + 0.09 * %O2 Kiln Mass Flow of Stoichiometric Air Kg/s Mst = Amin * ρAir * (%Fuel QP / 100) * (CEH / PCI )* (TPHClinker / 3.6) Mass Flow of Primary Air Kg/s Mpa = Mst * (%

Primary Air

/ 100)

Mass Flow of Secondary Air Kg/s Msa = λ * Mst - (%

Primary Air

/ 100) * Mst

Primary Air Speed m/s vpa = f * 236 * %

Primary Air

-0.4

; where f = 1.5 for modern burners and 1 for the rest.

Primary Air Flow m3/s Vpa = Mpa / ρPrimary Air Diameter Relation Burner (Dq) / Kiln(Di)

Vpa Dq/Di  2 *

  v pa

 Di  0.4

Thring – Newby coefficient

 M pa  M sa θ  Dq/Di    M pa 

  ρ pa   ρ   sa

  

0.5

, Maximum value = 0.94

Fuel Mass (Kg/s) Mb = (%

Fuel QP

/ 100) * (CEH / PCI )* (TPHClinker / 3.6)

Burner Push (Newtons -Kgm/s2-) G = (Mpa * vpa) +[23*(Mb + Mc)] Mc ashes mass in Kg/s = (% Ashes /100) * Mb

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Flame length

Actualization Date: Nov 04 Code DP-03-1

  M pa  M b    M st  M b     M b  (Thring - Newby coefficient) L  7.95   0.06   0.5 1     G  ρ Flame    θ  

ρFlame = 0.181 (Kg/m3) Maximum Flame Position = Burner Position + 0.42 * L (Empirical) Note: the maximum temperature position of the flame.

Final Position of the Flame = Burner Position + L Burner Position = Distance from the dump to the burner point. Nota: in satellites kiln the dump is the entrances middle point.

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Appendix D Parte II. System Temperatures Calculation Secondary – Tertiary Air Temperature ΔQ

Clinker

= ΔQ

ΔQ

Clinker

= (TPD/24) * CpCk * (TIncome – TOutcome)

ΔQ

Air

Air

= Msa * Cp * ( T3°+ 2° – TAmbient)

Where; TIncome = Theroical sintering temperature – 50 * Burner position T3°+ 2° = (ΔQ

Clinker

+ Msa * CpAir * TAmbient )/( Msa * Cpsa)

T2° = T3°+ 2° + 100 T3° = T3°+ 2° - 100 Main Flame Temperature PCI (=) Kcal/kg ΔQ

Fuel

= mFuel * Cp Fuel * TFuel

ΔQ

Secondary

ΔQ

Primary Air

Air = (λKiln * Amin - Amin*(% = Amin*(%

TFlame  1.1 

Primary Air

 PCI  ΔQ

Fuel

Primary Air

/ 100)) * ρAir * CpAir * T2°

/ 100) * ρAir * CpAir * TAmbient

 ΔQ Secondary Air  ΔQ Primary Air 

 %   0.393  1.5  0.01  Primary Air   100  

    VoR       

Calciner Flame Temperature TCalciner Flame = (ΔQ

Kiln Gases +

ΔQ Tertiary Air + ΔQFuel) / (mEscape Gas * CpEscape Gas)

Calciner Temperature TCalciner = (ΔQ

Kiln Gases +

ΔQ Tertiary Air - ΔQ

Raw Meal

)/ (mEscape Gas * CpEscape Gas)

Hot Stage Temperature THot Stage = 153 * T0.25 Where: ΔQ

Raw Meal

= mRaw Meal * CpRaw Meal * (TCalciner Flame– TPrevious Stage)

TPrevious Stage = 700 + 2 * %Calciner Fuel ΔQ

Kiln Gases

= VKiln Gases * ρ Kiln Gases * Cp Kiln Gases * Tback end * mclinker

ΔQ Tertiary Air = λCalciner * ρair normal AminCalciner * CEH * %KcalCalciner * Cpair * T3° ΔQ

Fuel

= CEH * mclinker * %KcalCalciner

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Page 176

Appendix E Part II. Thermal Conductivity and Insulation Thermal Conductivity The conductivity can be expressed in different units, and according it is distinguished by the letters W and K: Conductivity W, is expressed in units W/m K: W = Watt K = Kelvin degrees temperature (by nomenclature, the ° is not written) m = meters Conductivity k, kCal h m °C

is expressed in units kCal/h m °C: = kilo Calories = hours = meters = Temperature in Celsius degrees

The approximate relation between both expressions is: 1 W/m K

 0.86 kCal/ h m °C

The conductivity calculation at 1000 °C for a refractory with different oxides proportions is: K

1000 °C

Oxide I MgO Al2O3 SiO2 Cr2O3 CaO Fe2O3 ZrO2 SiC Others

=  (%Xi/100) * Ki Wi

1000

Ki

1000

]

1000

W/m K

kCal/h m °C

3.1 2.3 0.0 1.2 0.4 0.0 0.0 10.4 0.0

2.7 2.0 0.0 1.0 0.3 0.0 0.0 9.0 0.0

The thermal conductivity at any other temperature (expressed in °C) is obtained by:  1000  T C  KT C  K1000C  0.73   1000   Refractivity Ta (°C)

 % xi  Ta     Ta j  100 

Process Diagnosis Handbook

Chapter III: Clinker

Oxide i

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Page 177

Tai °C

The Tai temperature must not be although there is some relation. *Note: If in the composition a due to other elements not taken for that shortage. Cold Resistance (N/mm2)

 % xi  R   Ri  100 

TiO2 SiC ZrO2 Cr2O3 MgO Al2O3 SiO2 CaO Fe2O3 Others*

7000 2000 1750 1750 1750 1700 1200 825 750 1000

Oxide i

confused with the fusion point, 100% of oxides is not comepleted considerated, the 1000 °C value is

Ri N/mm2

For concretes the same equation multiplied by 1.55 to obtain the Density(g/cm3)

 % xi     i  100 

Cr2O3 ZrO2 SiC Al2O3 MgO Fe2O3 SiO2 CaO

190 170 150 80 45 30 2 2

will be used, but the result will be resistance value at 1000°C.

i

Oxide i

g/cm3

Dilatation (%) It is mainly presented in low zero in those of high density. It factor affects the dimensions (L)

 % xi  D1000C     Di 1000C  100 

SiC ZrO2 MgO Al2O3 Cr2O3 CaO Fe2O3 TiO2 SiO2 Oxide i

At other temperatures: D

T°C

=D

1000°C

+ 0.0014 * (T°C –

Cycles Cycles =  Xi * Cycles i ]

4 4 3 3 3 3 3 3 1 Di

density oxides, and it is practically must be considered that this as the (h).

1000°C

%

ZrO2 MgO CaO SiO2 Al2O3 Fe2O3 i Cr2OOxide 3 SiC MgO TiO2 Al2O3 Cr2O3 ZrO2 TiO2 SiC Rest

80 1.6 1.6 1.6 0 0 Cycles 0 0 110 0 80 80 80 80 80 0

1000)

i

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Page 178

Placing of isolators in smokes chamber.

Ta 15 °C

Ts 300 °C

Ta 15 °C

Ts 300 °C

12 mm 200 mm

200 mm

The isolator plate its placed easily (the placing cost does not rise) The heat losses by convection and radiation (Kcal/hr m2) are described with the following formulas:

hconvection

 T  Tair   80.33 *  s  2  

0.724



4 hradiation  4.2 x10 8 * Ts4  Tair

*  Ts  Tair 

1.33



Example for shell temperature of 300 °C:

 300  25  hconvection  80.33 *   2  



0.724

*  300  25

hradiation  4.2 x10 8 *  300  273  15  273 4

4

1.33

 1831.6

  4238.6

q Kcal  1831.6  4238.6  6070.2 A hr  m 2 With shell temperature of 200 °C:

 200  25  hconvection  80.33 *   2  



0.724

*  200  25

hradiation  4.2 x10 8 *  200  273  15  273 4

4

1.33

 1127 .3

  1813.3

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Page 179

q Kcal  1127 .3  1813.3  2940.6 A hr  m 2 Total saved energy:

q Kcal   6070.2  2940.6   3129.6 A hr  m 2 Coke PCI = 8200 Kcal/kg coke, coke savings = 0.38 kg coque/hr m 2 Coke cost = 0.65 $/kg, Savings in $ = 0.25 $/hr m2, So a 100 m2 section where isolation is installed will save each year (7,800 operation hours) $200,000.00 in radiation losses. For a kiln of 2000 TPD of clinker with a heat consumption of 820 Kcal/kg of clinker:

Kcal    2000TPD * 1000 * 820 Kg Kgcoke    * 8200  916 8200 day  Specific consumption =  Kcal/kg of      816.2 2000TPD * 1000

ck The saving will be of 3.8 Kcal/kg of clinker.