Design of A Deaerator Presentation One

 

DESIGN OF A DEAERATOR FOR BOILER FEED WATER TREATMENT BY ADUSEI GEORGE G EORGE SENCHIRE SUPERVISOR SUPER VISOR : DR. MOSES MOSES Y. MENSAH

27TH APRIL,2019 ©

 

PRESENTATION OUTLINE

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Problem Statement

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Introduction and Objectives

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Process Selection and Description

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Summary of Chemical Engineering Calculations

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Summary of Mechanical Design Calculations Conclusion

 

PROB PROBLEM LEM ST STA ATEME TEMENT NT

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To design a deaerator to strip dissolved oxyg oxygen en from a condensate return stream and a makeup water flowing at a rate of 225,000 kg/hr at 125 kPa and 120⁰C to produce water at 120.9 kPa and105⁰C.

 

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OBJECTIVES

Main Objective •

To remove dissolved oxygen from fr om a stream of water that flows at a rate of 225,000 kg/hr to be fed to the  boiler..  boiler

Specific Objectives •

To select the appropriate column type for the stripping process.

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To select the appropriate tray contractors

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To calculate the appropriate column diameter, height and number of trays.

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To perform both chemical and mechanical engineering calculations.

 

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INTRODUCTION

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Why Deaeration?

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Operating principles:

1.The temperature solubility relationship of gases in water. 2.Henry’s Law

 

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PROCESS OCESS SELECTION AND DESCRIPTION PR

Column Type •

Trays (Plates) Column

Contacting Device •

Sieve Trays

 

7 SUMMARY OF CHEMICAL ENGINEERING CALCULATIONS

Log{

X1 1− 1 + 1 } X2 S S , S = G (Sinnot, 2005) L log log (S) (S)

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  N   =

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  N  = Theoretical number of stages

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X1 = mole fraction of oxygen in the feed water 

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X2 = mole fraction of oxygen in the deaerated water 

 

8 TABLE 1: SUM MA R Y OF OF C H E MI CA L E NG I NE E R I NG C AL CUL ATI ONS PARAMETER

VALUE

Liquid flow rate, kg/hr

225,000

Vapour Flow rate, kg/hr

PARAM ETER

VALUE

2,163

Temperature, ⁰C

120

Liquid Vapour flow factor

2.4

Pressure, kPa

125

Flooding Velocity, m/s

3

Maximum Volumetric liquid flow, m3 /s

0.06

Number of Trays

14

Vapour Volumetric flow rate, m3 /s

1.14

Column Diameter, m

0.8

Residence time, s

6 Column Height, m

7.4

Fractional Entrainment

0.009

Enthalpy of Feed steam, kJ/hr

5.8 x 106

Tray Spacing, m

0.5

Enthalpy of Feed water, kJ/hr

54.6 x 106

Enthalpy of Deaerated Water, kJ/hr

113.3 x 106

Pressure Drop,

1.8 kPa

 

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CALCULATIONS TIONS SUMMARY OF MECHANICAL DESIGN CALCULA TABLE 2: SUM MA R Y OF OF M E CH A NI CA L E NG I NE E R I NG C A L CUL CU L ATI ONS PARAMETERS

VALUE

PARAMETERS Total direct stress,

kN/m2

VALUE

6707.3

Design Pressure, kPa

140

Design Temperature, ⁰C

130

Bending stress, kN

4730

Wall thickness, mm

14

Skirt height, m

2

Weight of Shell, kN

25

Skirt thickness, mm

17

Weight of Plate, kN

8.1

Bolt spacing, m

0.17

Weight of Insulation with fittings, kN

3.6

Number of bolts

16

Total weight of column, kN

36.7

Actual width of base ring, mm

141

1251.8

Actual bearing pressure on foundation, kN/m2

497.2

Total wind Loading,

N/m2

Total longitudinal stress, kN/m2

2000

Total Circumferential stress, kN/m2

4000

Material of construction of shell

Stainless steel 304

707.3

Insulation material

Mineral wool

Total dead weight stress,

kN/m2

 

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CONCLUSION

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Plate column was chosen and used for the t he design of the deaerator with sieve plates (trays) ( trays) selected as the type of contractors for the column. col umn.

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Chemical engineering design parameters deemed appropriate were calculated.

Mechanical engineering parameters were successfully calculated.

 

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REFERENCES

Robertt E. Treybal. (198 Rober (1981) 1) Mass  Mass Transfer Oper Operations ations.. 3rd ed.,p:679. McGraw-Hill, Inc., New York. Underwood ,A.J.V.,(1935) Trans.Inst.Chem.Engrs. 1st ed. p:25 (vol.1)

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Christie J. Geankoplis (1993) Transport Processes and Unit Operations, 3rd ed., p: 679. Eaglewood Cliffs, New Jersey

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R. K. Sinnot Sinnott, t, Coulso Coulson n & Richards Richardson’s, on’s, (2004 (2004)) Chemical Engineering Design. Design. 3rd e ed.,p: d.,p: 550-580, 830850 (vol. 6), Butterworth-Heinemann.

 

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THANK THA NK Y YOU OU