Report on Low temperature shift converter Catalyst reduction
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The document outlines the procedure for reducing the LTS catalyst used in an ammonia plant, specifically focusing on the Katalco 83-3 catalyst. The reduction process is initiated by heating and introducing hydrogen to convert copper oxide into reactive copper metal while monitoring multiple parameters including temperature and hydrogen flow. The report details the sequential reduction for multiple catalyst beds and the subsequent soaking phase, ultimately culminating in the successful operation of the LTS system.
Report on Low temperature shift converter Catalyst reduction
- 1. REPORT ON LTS REDUCTION Prepared By: Gulfam Khalid Shift Engineer AMMONIA PLANT
- 2. Standard Operating Procedure FOR LTS reduction Introduction Fresh/Newly charged LTS catalyst has to be reduced before taken it into service, by this procedure stable copper oxide component of the new catalyst is converted into reactive copper metal. During reduction and operation its zinc oxide and alumina components remain unchanged and act as support, which stabilize the copper metal crystals that act as reservoir for poisons. Hydrogen is used as reducing agent. The reaction of catalyst with hydrogen is exothermic as given below: CuO + H2 ↔ Cu + H2O ∆H = -81 Kj/mol KATALCO 83-3 catalyst is based on copper oxide supported on a matrix of zinc oxide and alumina. Catalyst type: KATALCO 83-3 (CuO) Form: cylindrical pellets Length: 3.0 mm Diameter: 5.2 mm Charged bulk density: 1.38 kg/L or 86 lb/ft3 Vendor: Johnson Matthy Total volume of catalyst: 39.6 m3 Bulk density: 1380 kg/m3 Total weight: 54648 kg CuO in catalyst: 51 wt% Plant condition before reduction Plant load: 50% Air to secondary reformer: Not started yet Source to H2 rich gas: 103F Steam to carbon ratio: 5
- 3. Reduction circuit: 1. Prepare the reduction circuit of LTS as follows: 2. SFS 1132, SFS 1143, SFS 1144, SFS 1139, SFS 1167, SFS 1168, SFS 1171 and their associated valves should be close. 3. SFS 1165, SFS 1170 and EMV 1165 should be close. 4. Keep close by pass valve of exchanger A-133C1 of line no. 6PF1119. 5. SFS 1133, SFS 1145, and SFS 1172 should be in open position. 6. Open isolation manual valves associated with SFS 1172 and SFS 1145, and block valve of line no. 6PF1121. 7. Establish flow of desulphurised natural gas through LTS slowly at the rate of 15000 Nm3 /hr minimum to maintain space velocity at 300/hr minimum so that gas distribution through the catalyst bed is uniform. Use FI-1140 to measure the N.Gas flow to LTS. 8. Increase the catalyst bed temperature up to 130O C by the by pass valve of the exchanger A-133C1 at the rate of 50O C/hr. keep LTS back pressure at 6.0kg/cm2 g with its manual vent valve on line no.10V1115. 9. Check correct working of hydrogen flow meter F-1168/ F-1169 when catalyst bed temperature reaches 120 ̴130O C. During checking of flow meter do not increase the bed temperature. 10. Install online hydrogen analyzer by connecting it with inlet / outlet sample points S- 1165B & S-1165C of LTS. Before making it online, confirm its accuracy with chemical laboratory results. 11. Increase the top LTS bed temperature up to 180O C. Catalyst reduction When catalyst inlet temperature reached to 180O C, introduce H2 from 103F. 1. Open 103F outlet valve to 104DB fully and open u/s of FI-1169 valve slowly in steps. Keep LTS inlet temperature at 180O C. 2. Establish H2 gas flow at the rate of 30 Nm3/hr initially by opening 1-1/2 ‘’ needle valve. Watch LTS catalyst bed temperature (T-1230 ̴ T-1232, T-1181 ̴ T-1182) for 5 minutes. 3. If catalyst temperatures are not rising by abnormal reaction, increase hydrogen gradually in steps up to 100 m3 /hr. watch LTS bed temperature for 5 minutes after each step. 4. Bed temperature will start increasing when hydrogen starts reacting with CuO catalyst. HPNG BC4 101D 102DA/DB 133C1 LTS /104-DB 103F (H2) VENT
- 4. 5. Keep on increasing hydrogen flow from 1% to 3% in the inlet Natural Gas gradually by watching bed temperatures. Maintain hydrogen flow maximum till the bed temperature stops rising. 6. Monitor LTS inlet and outlet H2 gas content with online analyzer continuously. Verify these results with laboratory analysis after 1 ̴ 2 hrs. So special arrangements for H2 gas analysis is necessary during LTS catalyst reduction. 7. When 1st bed temperature is coming down the reaction will start in 2nd bed and its temperature will rise. Control the temperature by controlling the hydrogen flow into the N.Gas LTS inlet. Similar steps are to be followed for all the beds till the temperature of the last bed starts decreasing after reaching to peak temperature. 8. Confirm hydrogen consumption which is more than 90% if 1st bed temperature comes down to 1st bed inlet temperature (180O C) one by one. 9. If H2 is not consumed more than 90%, increase inlet temperature of LTS 3O C at every step until 90% hydrogen is consumed. However maximum limit of inlet temperature is 215O C. 10. If H2 is consumed more than 90%, keep that temperature and increase hydrogen contents from 3% to 50% volume gradually. Increasing rate of H2 is 1.5 times of existing hydrogen contents. That is 2% × 1.5 = 3%, 3% × 1.5 = 4.5% 11. During catalyst reduction, watch catalyst bed temperature carefully and if any abnormal temperature rise is found cut H2 supply. 12. Under LTS inlet temperature 215O C and inlet hydrogen contents 50%, if each bed temperature is less than LTS inlet temperature (180O C) and H2 consumption is almost zero, LTS reduction has completed. Soaking When reduction of LTS catalyst completed soaking period started, for this gradually increase the hydrogen concentration in the inlet gas up to 15% incrementally and watch very carefully bed temperatures for 5 ̴10 minutes. Bed temperature neither allows increasing abruptly nor exceeding to 230O C. However, for small duration increase is not harmful for the catalyst.
- 5. Actual Operating Procedure LTS catalyst blowing To remove entrapped dust particles from catalyst bed, catalyst is blown with desulphurized natural gas for 3 to 4 hours. It was done to avoid increase in pressure drop along the bed and these dust particles cause foaming problem in the CO2 removal system. Circuit for LTS blowing Heating Desulphurized natural gas is used for heating of LTS catalyst. Established the flow of N.Gas to heat the bed up to 130O C at the rate of 50O C per hour and keep the back pressure 5-6 kg/cm2 g. Ensure that both the hydrogen flow meter and analyzer are operating satisfactorily as the temperature approaches 130O C. Continue heating the catalyst until top of bed is at 180O C. The temperature of the gas should not exceed 210O C during the initial heating if natural gas space velocity is less than recommended more care is necessary as there can be poor gas distribution which can lead to localized overheating. Start recording the bed temperature during warm up to confirm that the gas is well distributed through the bed. Circuit for heating SFS 1132, SFS 1143, SFS 1144, SFS 1167, SFS 1168, SFS 1171 and their associated valves were close. SFS 1165, SFS 1170 and EMV 1165 should be close. Used A-133C1 by pass route for heating of LTS. SFS 1133, SFS 1145, SFS 1177, and SFS 1172 should be open. 102 DA,DB A-133C1 by pass A-104DB Vent
- 6. H2 injection 1st bed reduction When the temperature of top 3rd bed reached 159O C introduced hydrogen through FI 1169 at the rate of 65 Nm3 /hr. To maintain the inlet temperature of N.Gas 180O C at the inlet increase the H2 flow 65 ̴100 Nm3 /hr then 100 ̴160 Nm3 /hr, 16 ̴ 220 Nm3 /hr, 220 ̴ 280 Nm3 /hr within 4.5 hours of reduction started when the hydrogen concentration at online analyzer reached 7.6% first bed reduction completed and exotherm of first bed was at 224O C, at its peak. Actually hydrogen concentrations at online analyzer 7.6% was more than expectations, the reason was that hydrogen analyzer was giving the results of HTS out let combined, later on analyzer position was changed, HTS outlet blinded, and so H2 analyzer concentrations came to normal. 2nd bed reduction Reduction of 2nd bed completed within 10.5 hours of reduction started, H2 concentration at online analyzer was 2.09% and temperature of 2nd bed was 208O C at that time. 150 160 170 180 190 200 210 220 230 0 2 4 6 8 H2 ConcVS 1st bed temperature 1stbedtemperatures H2 concentration 200 205 210 215 220 225 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 H2 concentration 2ndbedtemperatures
- 7. 3rd bed reduction Reduction of 3rd bed completed within 17 hours of reduction started, H2 concentration at online analyzer was 2.40% and temperature of 3rd bed was 206O C at that time. 4th bed reduction Reduction of 4th bed completed within 27.5 hours of reduction started, H2 concentration at online analyzer was 2.40% and temperature of 3rd bed was 215O C at that time. 150 160 170 180 190 200 210 220 230 2.15 2.2 2.25 2.3 2.35 2.4 2.45 2.5 H2 ConcentrationVs 3rd bed temperatures H2 Concentration 3rdbedtemperatures 214 214.5 215 215.5 216 216.5 217 2 2.05 2.1 2.15 2.2 2.25 2.3 2.35 2.4 2.45 2.5 2.55 2.6 2.65 2.7 H2 ConcentrationVs 4th bed temperatures H2 Concentration 4thbedtemperatures
- 8. 5th bed reduction Reduction of 5th bed completed within 29 hours of reduction started, H2 concentration at online analyzer was 2.54% and temperature of 3rd bed was 213O C at that time. Soaking At 34 hours of reduction started temperature 1st ,2nd ,3rd ,4th ,and 5th bed were 191.5,192,192.4,192.2 and 197 respectively then H2 soaking started for this gradually increase the inlet H2 concentration up to 19.08% at that time temperature of inlet gas and all the beds were 219, 219.6, 220.6, 221.5, 223 and 221.8 respectively, since all the beds now were almost same temperature then H2 flow to LTS restricted to zero inlet concentration at LTS inlet and hold for 3.5 hours and after this isolated LTS and hold up it at 30 kg/cm2 g all this activity took 41 hours. At 39 hours of reduction front end load increase started and air to secondary reformer fed at 50% plant load to achieve the desired composition of HTS outlet for taking LTS in service. Circuit for LTS reduction SFS 1132, SFS 1143, SFS 1144, SFS 1167, SFS 1168, SFS 1171 and their associated valves were close. SFS 1165, SFS 1170 and EMV 1165 should be close. Used A-133C1 for LTS reduction. SFS 1133, SFS 1145, SFS 1177, and SFS 1172 should be open. H2 flow for reduction was maintained through FI 1169 and later through both FI 1169 and 1168 196 198 200 202 204 206 208 210 212 214 216 2.1 2.2 2.3 2.4 2.5 2.6 2.7 H2 ConcentrationVs 5th bed temperatures H2 Concentration 5thbedtemperatures
- 9. LTS in service When LTS took in service then temperatures of all the beds shooted abruptly after 12 minutes of taken it into service temperature of 1st bed was 216◦C at its peak, after 15 minutes of service temperature of 2nd bed was 256◦C, after 17 minutes of service temperature of 3rd bed was 287.4◦C, after 23 minutes of service temperature of 4th bed was 300◦C, and after 26 minutes of service temperature of 5th bed was 297◦C. And after that temperatures of all the bed started to come down.