Ammonia Synthesis Converter

N2 + 3 H2 2NH3 EFFECTS OF-- A.PRESSURE B.TEMPERATURE C.CATALYST D.INERTS E.GAS COMPOSITION F.CIRCULATION RATE

H500= -26kcal

Temkin &Pyzhew = k2 { kp pN2(pH23 / pNH32)a - (pNH32 / pH23)1-a}w = rate of reactionkp=equilibrium constant for ammonia reaction.K2=k2(0)exp-{ Ek2/R( 1/T - 1/T0)}a has value between 0 & +1.

Addition of first H2molecule to the adsorbed nitrogenTemkin ,Morozov & Shapatina(1963)W = k*pN21-a{1- pNH32 / KppN2pH23 }{L/pH2 +1/kp. pNH32/ pN2pH23}{1+ l/pH2}1-a

Since the reaction is accompanied by decrease in volume ,so the equilibrium conc Of ammonia will be favored by high pressure.Designed for maximum pressure of 155ksc.

Since the reaction is exothermic(about 750 kcal/kg of ammonia), equilibrium conc. is favored by low temp.However , reaction velocity is very much enhanced at high temp. operation. Reaction temp. in the catalyst bed is 360 to 520 0C.

TYPEKM1KM1RVOLUME68.4WEIGHT59720COMPOSITION194940m3kgFe3O4,oxides of Ca,Al and K26.9

Magnetite has a spinel structure, consisting of cubic packing oxygen ions ,in the interstices of which Fe2+ and Fe3+ ions are distributed. During reduction all the oxygen is removed, but no shrinkage occurs. Catalyst is activated by reducing the iron oxide surface layer to free iron.This reduction is normally carried out with circulating syn gas.Cat. is stable in air below 1000C . Above 100 C it will react with air and spontaneously heat up.

Main component has remained iron since the catalyst was first introduced in1914 by BASF in Germany.(osmium & uranium have been tried).Reaction does not take in absence of catalyst because of high stability of the N2 molecule.The catalyst function by forming a nitrogen compound on the catalyst surface which is hydrogenated to ammonia.Iron chemisorbs nitrogen rapidly, and it is this adsorption which is generally considered to be the step which controls the rate of overall synthesis process.

In the manufacture of catalyst ,some of the alumina and magnesia promoters dissolve in the magnetite as they have similar ionic dimensions.During reduction, the dissolved Al2O3 & MgO comes out of solution and separates in the pores between the iron crystallites , hindering their further growth during the reduction and in subsequent use.Thus Al2O3 assist in both the formation and preservation of small iron crystals of high surface area.

PotashIt increases the intrinsic activity of the iron surface ,but also tends to decrease the iron surface area.Calcium oxide it enhances the action of Al2O3 in stabilizing the iron surface area and preventing sintering.It also make the catalyst more resistant to poisoning by sulphur and chlorine.

H2N2NH3CH4Arinletoutlet

Sheet1

SYNTHESIS LOOP MATERIAL BALANCE

STREAM1234567891011

PHASEGASGASGASGASGASGASGASGASGASGASLIQUIDGASLIQUID

%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr%Kmol/hr

H264.061816103.2664.061816103.2664.061816103.2664.061816103.2664.061816103.2651.526411303.4751.526411303.4751.526411303.4751.526411303.4753.26111298.040.74945.4355.009111293.560.70419.91

N223.64785944.3623.64785944.3623.64785944.3623.64785944.3623.64785944.3619.80394344.4319.80394344.4319.80394344.4319.80394344.4320.46664341.50.40322.9221.13574339.230.36925.19

NH33.3805849.753.3805849.753.3805849.753.3805849.753.3805849.7518.464049.6118.464049.6118.464049.6118.464049.6115.72713336.1398.4639713.4812.97112663.0198.56111386.6

CH46.88451730.556.88451730.556.88451730.556.88451730.556.88451730.557.88871730.557.88871730.557.88871730.557.88871730.558.14651728.080.34132.478.407117260.32344.55

Ar2.0255509.162.0255509.162.0255509.162.0255509.162.0255509.162.321509.162.321509.162.321509.162.321509.162.3988508.860.04210.312.4771508.570.04230.6

TOTAL25137.0825137.0825137.0825137.0825137.0821937.2221937.2221937.2221937.2221212.61724.6120530.371406.85

TEMP(Deg C)-11.5313.3534.1245.98213.8424.232425982.838.0838.083131

PRESSURE(BarA)136.8136.2135.73146.12144.75142.41141.7141140.3139.6139.6138.9138.9

STREAM121314151617181920

PHASEGASLIQUIDGASLIQUIDGASLIQUIDGASLIQUIDLIQUIDGASGASGASGAS


H257.828911289.210.590314.2659.612711289.20.475614.2759.612710704.830.4814.2762.7116101.570.4912.980.3611.359.61584.3873.435395.4686.76453.3272.414942.14

N222.21764337.290.29567.1422.90384337.420.2334722.90384112.90.23723.155943.730.236.120.175.522.9224.5224.91829.9411.7961.625.911768.34

NH38.52211663.6798.78022385.945.70671080.7198.97512968.95.70671024.7698.982968.95.411390.2799.042603.3899.243143.925.7155.94000000

CH48.82861723.510.29177.059.09481722.340.27388.219.09481663.180.278.216.741731.510.25.320.26.299.0989.161.3595.440.693.671.3591.84

Ar2.6029508.140.04221.022.6821507.920.04141.242.6821481.630.041.241.98509.290.0380.030.942.682126.290.3427.220.763.970.3423.25

TOTAL19521.822415.4118937.592999.6217987.32999.6225676.372635.83167.95980.297348.06522.566825.57

TEMP(Deg C)16162.92.92.92.92.252.25-11.532.93113.3513.35

PRESSURE(BarA)138.2138.2137.5137.5137.5137.5137.5137.5136.8137.5141.2136.2136.2

SYNTHESIS LOOP HEAT BALANCE

TEMPin(Deg C)TEMPout(Deg C)PRESin(BarA)PRESout(BarA)Duty(Gcal/hr)

E-501424.2324142.41141.218.557

E-502324259141.714111.795

E-50325982.8141140.331.459

E-50482.838.05140.3139.610.769

E-5053116138.9138.26.8945

E-5062.25-11.53137.5136.85.7425

E-50738.0531139.6138.93.9061

E-508162.9138.2137.55.0359

Sheet2

Sheet3

Sheet1


STREAM1234567891011



H264.061816103.2664.061816103.2664.061816103.2664.061816103.2664.061816103.2651.526411303.4751.526411303.4751.526411303.4751.526411303.4753.26111298.040.74945.4355.009111293.560.70419.91

N223.64785944.3623.64785944.3623.64785944.3623.64785944.3623.64785944.3619.80394344.4319.80394344.4319.80394344.4319.80394344.4320.46664341.50.40322.9221.13574339.230.36925.19

NH33.3805849.753.3805849.753.3805849.753.3805849.753.3805849.7518.464049.6118.464049.6118.464049.6118.464049.6115.72713336.1398.4639713.4812.97112663.0198.56111386.6

CH46.88451730.556.88451730.556.88451730.556.88451730.556.88451730.557.88871730.557.88871730.557.88871730.557.88871730.558.14651728.080.34132.478.407117260.32344.55

Ar2.0255509.162.0255509.162.0255509.162.0255509.162.0255509.162.321509.162.321509.162.321509.162.321509.162.3988508.860.04210.312.4771508.570.04230.6

TOTAL25137.0825137.0825137.0825137.0825137.0821937.2221937.2221937.2221937.2221212.61724.6120530.371406.85

TEMP(Deg C)-11.5313.3534.1245.98213.8424.232425982.838.0838.083131

PRESSURE(BarA)136.8136.2135.73146.12144.75142.41141.7141140.3139.6139.6138.9138.9

STREAM121314151617181920



H257.828911289.210.590314.2659.612711289.20.475614.2759.612710704.830.4814.2762.7116101.570.4912.980.3611.359.61584.3873.435395.4686.76453.3272.414942.14

N222.21764337.290.29567.1422.90384337.420.2334722.90384112.90.23723.155943.730.236.120.175.522.9224.5224.91829.9411.7961.625.911768.34

NH38.52211663.6798.78022385.945.70671080.7198.97512968.95.70671024.7698.982968.95.411390.2799.042603.3899.243143.925.7155.94000000

CH48.82861723.510.29177.059.09481722.340.27388.219.09481663.180.278.216.741731.510.25.320.26.299.0989.161.3595.440.693.671.3591.84

Ar2.6029508.140.04221.022.6821507.920.04141.242.6821481.630.041.241.98509.290.0380.030.942.682126.290.3427.220.763.970.3423.25

TOTAL19521.822415.4118937.592999.6217987.32999.6225676.372635.83167.95980.297348.06522.566825.57

TEMP(Deg C)16162.92.92.92.92.252.25-11.532.93113.3513.35

PRESSURE(BarA)138.2138.2137.5137.5137.5137.5137.5137.5136.8137.5141.2136.2136.2



E-501424.2324142.41141.218.557

E-502324259141.714111.795

E-50325982.8141140.331.459

E-50482.838.05140.3139.610.769

E-5053116138.9138.26.8945

E-5062.25-11.53137.5136.85.7425

E-50738.0531139.6138.93.9061

E-508162.9138.2137.55.0359

Sheet2

Sheet3

Sheet1


STREAM1234567891011



H264.061816103.2664.061816103.2664.061816103.2664.061816103.2664.061816103.2651.526411303.4751.526411303.4751.526411303.4751.526411303.4753.26111298.040.74945.4355.009111293.560.70419.91

N223.64785944.3623.64785944.3623.64785944.3623.64785944.3623.64785944.3619.80394344.4319.80394344.4319.80394344.4319.80394344.4320.46664341.50.40322.9221.13574339.230.36925.19

NH33.3805849.753.3805849.753.3805849.753.3805849.753.3805849.7518.464049.6118.464049.6118.464049.6118.464049.6115.72713336.1398.4639713.4812.97112663.0198.56111386.6

CH46.88451730.556.88451730.556.88451730.556.88451730.556.88451730.557.88871730.557.88871730.557.88871730.557.88871730.558.14651728.080.34132.478.407117260.32344.55

Ar2.0255509.162.0255509.162.0255509.162.0255509.162.0255509.162.321509.162.321509.162.321509.162.321509.162.3988508.860.04210.312.4771508.570.04230.6

TOTAL25137.0825137.0825137.0825137.0825137.0821937.2221937.2221937.2221937.2221212.61724.6120530.371406.85

TEMP(Deg C)-11.5313.3534.1245.98213.8424.232425982.838.0838.083131

PRESSURE(BarA)136.8136.2135.73146.12144.75142.41141.7141140.3139.6139.6138.9138.9

STREAM121314151617181920



H257.828911289.210.590314.2659.612711289.20.475614.2759.612710704.830.4814.2762.7116101.570.4912.980.3611.359.61584.3873.435395.4686.76453.3272.414942.14

N222.21764337.290.29567.1422.90384337.420.2334722.90384112.90.23723.155943.730.236.120.175.522.9224.5224.91829.9411.7961.625.911768.34

NH38.52211663.6798.78022385.945.70671080.7198.97512968.95.70671024.7698.982968.95.411390.2799.042603.3899.243143.925.7155.94000000

CH48.82861723.510.29177.059.09481722.340.27388.219.09481663.180.278.216.741731.510.25.320.26.299.0989.161.3595.440.693.671.3591.84

Ar2.6029508.140.04221.022.6821507.920.04141.242.6821481.630.041.241.98509.290.0380.030.942.682126.290.3427.220.763.970.3423.25

TOTAL19521.822415.4118937.592999.6217987.32999.6225676.372635.83167.95980.297348.06522.566825.57

TEMP(Deg C)16162.92.92.92.92.252.25-11.532.93113.3513.35

PRESSURE(BarA)138.2138.2137.5137.5137.5137.5137.5137.5136.8137.5141.2136.2136.2



E-501424.2324142.41141.218.557

E-502324259141.714111.795

E-50325982.8141140.331.459

E-50482.838.05140.3139.610.769

E-5053116138.9138.26.8945

E-5062.25-11.53137.5136.85.7425

E-50738.0531139.6138.93.9061

E-508162.9138.2137.55.0359

Sheet2

Sheet3

Pressure shell type S-200 I.D. 2700mmH2 partial pressure 102kscshell thickness 117 mm

Relative necessary catalyst volumeRelative pressure drop per unit bed height1.5-33-66-108-1201

1st bed

2nd bed

Diameter

2334/1050

2400/650

Total height

7925

16390

Effective height

7015

15250

Total volume

26.9m3

68.4m3

Effective volume

23.8m3

63.7m3

type1-1 disc and doughnutno.of tube667dimensions of tubes 3/4 BWG 18effective length6780mmbaffle distance565mmshell length5765mmshell I.d.825mmdisc dimension569mmdoughnut dimension 823/573mmmaterial of tubesinconel600

OXYGEN COMPOUNDSSULPHURCHLORINE

PPM O EQV. = 2*ppm O2 + ppm H2O + ppm CO +2*ppm CO2SOURCE---poor performance of methanator-poor performance of secondary ammonia separator The rate of sintering increases in presence of oxygen compound particularly H2O . Chlorine--loss of K due to formation of KCL

Effect is mainly irreversibleprimarily inner layer of the catalyst is affected.SOURCE make up gas lubricating oil leaking from syn gas compressor

N H3 %TEMP. 3 bed2 bed

reduced operating pressure.reduced circulation flow rate & pressure drop.reduced refrigeration load.increased heat recovery from the synthesis loop.

Mechanical characteristics

Multi layer shell.3layers inner layer A387 Gr 11 30m thick.(A.S.)Outer layer A533 Gr B 32mmX2 layers.(C.S.)Total thickness 94 mm.Design Pressure 152.1 KSC

Mechanical characteristics

Vendor L & T.Other Features being same as of Now.

Ammonia Synthesis Converter

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