Kiln Installed Capacity

Installed Capacity of the Cement Kiln The clinker production installed capacity is defined by the geometry of the cement kiln (the kiln’s tube diameter) and its thermodynamic t hermodynamic conditions (kiln heat load). As requested by the UNFCCC, CEMEX Costa Rica has determined the installed capacity of the cement kiln at the time of validation in manner consistent with standard industry practice. For this purpose the calculation was performed based on the worldwide standard for cement 1 industry practice defined in “CEMENT-DATA. BOOK” by BOOK” by Dipl.-Ing.Walter H Duda  . “CEMENT-DATA. BOOK”  has been taken as the cement sector standard because it is considered an essential resource for the cement engineer and plant library. This book has been used worldwide for the design of new cement plants, development of energy efficiency project at the cement industry, research and development of new cementitiuos materials and other additional applications in the cement manufacturing industry. Page 414 of “CEMENT-DATA. BOOK”  shows a standard strategy to estimate a rotary kiln capacity. For practical purposes of rotatory kiln sizing, statistical data for each kiln system are used to derive capacity figures which are applied as indicating factors. The next formula considers thermodynamic conditions in the rotatory kiln to estimate its capacity:

TPH  = 2.826 ⋅

v V g

⋅

D

2

Where: TPH =Kiln capacity, (metric tons/hour) v = Gas Velocity in the gas discharge end (m/sec) 3 Vg = Specific gas volume (m  /kg clinker) D = Kiln diameter on bricks (m) Variable “v” is “v”  is defined by the heat load from the kiln’s tube operation and is directly related to the amount of fuel consumed and the gas flow from the products of combustion. The kiln heat load is calculated based on the following formula:

F i * NHV i  Gcal  n = ∑ 2  h − m  i 1    Dint2    π   *  * 1 × 10 6  4    

Ki ln  Heat  Load 

=

Where: Fi = Fuel rate (kg/h) NHVi = Fuel Net heat value (kcal/kg) Dint = Kiln Effective Diameter, inside refractory lining ( m). Variable “Vg” is determined based on stoichiometric calculations assuming a 3% of excess oxygen.

1

Cement data book, Dipl.-Ing Walter H. Duda, Vol.1, International Process Engineering in Cement Industry, 3rd Edition, Bauverlag GmbH

Considering the formula described on the “CEMENT-DATA. BOOK” , and taking into account the actual kiln diameter as well as the kiln heat load, it can be determined that the installed 2 capacity of the kiln in Colorado Plant at the t ime of validation is of 4,155 TPD . As it can be noticed, this value is higher than the installed capacity that was originally computed and presented in the PDD using CEMEX own formula included on an internally developed technical protocol. Then, it can be said that CEMEX calculations were conservative compared to the results obtained from applying the standard cement industry practice However it is important to clarify that CEMEX developed this technical protocol named “CEMEX Diagnostic Process Manual” based on the cement industry standards and best practices and adapting them according to their own kiln characteristics and behavior and their specific operational conditions. The following kiln capacity formula was the one used to obtain the value reported in the PDD. It is included on the mentioned technical manual and was defined as the standard to be used by the Technical Department in CEMEX. It was deducted through the development of a mathematical model constructed from an exhaustive database of CEMEX kilns operational data. By using this formula CEMEX is able to determine the installed clinker production capacity for the kilns of any installation within the group worldwide and can also predict accurately the expected behavior of new systems:

Tpd  = production level ≅

10.28 ⋅  Di

3.84

0.06 ⋅ (% ppal ) 0.72

(for white multiply by 0.65)

where :  Di

=

Ferrule internal diameter

%ppal = percentage of  calories in the main burner

As shown in the formula, the variables defining the clinker production capacity are the ferrule internal diameter (kiln’s diameter) and the percentage of calories in the main burner (similar to the formula included on “CEMENT-DATA. BOOK”  which is based on the kiln’s diameter and heat load). These variables are considered because it has been observed that they can give the best explanation of the installed capacity through two components: the maximum capacity of the equipment (explained by the kiln’s internal diameter) and the operation optimization (explained by the % of calories consumed in the main burner). Both parameters (Di and %ppal) are fixed for each system, thus, installed clinker production capacity is also fixed for each system

Tpd  = production level ≅

10.28 ⋅ Di

3.84

0.06 ⋅ (% ppal ) 0.72

10.28 ⋅ 4.267 ≅

3.84

0.06 ⋅ (33) 0.72

=

3,632 TPD

According to the available equipment and the operational conditions existing by the time of validation of the project activity, the Colorado cement plant has a kiln with an internal diameter of 4.267 m and the percentage of calories used in the main burner is 33% resulting in an installed clinker production capacity of 3,632 t onnes/day. As it was already mentioned, this value is more conservative than the one computed with the standard formula proposed in the CEMENT-DATA BOOK.

2

Two spreadsheets including the detailed calculations and assumptions will be provided to the DOE, so as the technical sheets of the kiln’s diameter.