Process description of Purifier process.pptx

Purifier

1. INTRODUCTION TO AMMONIA PLANT COLD BOX Presented By: ABDUL JABBAR GTE TSD 10/25/2010 1 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

2. CONTENTS Application of Cold box Brief description of Ammonia Plant Cold Box Process Flow Schematic Construction of cold box Operational issues relating to Cold box Fouling of Exchangers Bad Mode Operation Gas Mal-Distribution in Exchangers High ∆P across the Expander Important Practices at Kemira 10/25/2010 2 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

3. COLD BOX What is a Cold Box? Cold Box is a group of multi-fluid exchanger cores assembled in a single structure and Purifier column for separation of gases. Net refrigeration is provided by Expander and Joule Thomson Valve. 10/25/2010 3 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

4. Purpose of Cold Box Cold Box provides Cryogenic Purification. Word Cryogenic means Generation of cold. Temperature below -150  C is considered to be cryogenic temperature. Principle of cryogenic purification is liquefaction i.e. separation of gases by decreasing the temperature. Cryogenic Purification is achieved in Cold box. 10/25/2010 4 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

5. FFCL COLD BOX 10/25/2010 5 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

6. FFCL Cold Box (KBR Purifier): Function of FFCL cold box is to purify Feed Gas (FG) by separating argon (brought in with the air), excess nitrogen and methane (contained in the synthesis gas) by cooling and distillation. Basically cold box fixes ratio of H 2 /N 2 at synthesis machine suction by condensing excess nitrogen and almost all inert. Extent to which inerts are removed Methane Removal Efficiency 99.9% Argon Removal Efficiency 60% Carbon Dioxide 50% 10/25/2010 6 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

7. 1. Process Flow Schematic H 2 =64.173 N 2 = 32.433 CH 4 = 2.88 Ar = 0.508 T= 4 ˚ C P = 27.3Kg/cm 2 H 2 = 74.17 N 2 = 24.95 CH 4 = 0.001 Ar = 0.244 T= 3 ˚ C P = 23.6Kg/cm 2 Feed Gas Syn Gas Waste Gas 10/25/2010 7 H 2 = 4.26 N 2 = 74.59 CH 4 = 19.14 Ar = 1.99

8. Construction of Cold Box Main Components of FFCL Cold Box Plate and Fine Exchanger (Compact Heat Exchanger) Joule Thomason (JT) Valve Purifier Rectifier Column Purifier Expander Insulation Perlite 10/25/2010 8 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

9. Plate and Fine Exchanger (Compact Heat Exchanger) Plate-fin heat exchangers are a matrix of flat plates and corrugated fins in a sandwich construction. Primary Heat Transfer Surface Provide Sealing b/w Plates Secondary Heat Transfer Surface 10/25/2010 9 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

10. Corrugated fins and Plates in a sandwich construction. 10/25/2010 10 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

11. Core of Plate-Fin Heat Exchanger Flow Through Single Element Syn Gas Feed Gas Waste Gas Complete Core of Plate- Fin Heat Exchanger: These elements are built into a complete core and then vacuum brazed to form an integral unit Core of plate-fin heat exchanger Many Elements Combine to form a complete Core 10/25/2010 11 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

12. Cores Assembled in Parallel 10/25/2010 12 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

13. Exchanger Arrangement in Series and Parallel Cores of E-125A1 Cores of E-125A2 Cores of E-126 Cores of E-126 = 8 Cores of E-125 = 16 10/25/2010 13 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

14. Operational issues of COLD BOX 10/25/2010 14 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

15. (A). Fouling in Cold box Fouling: Accumulation of unwanted material on heat transfer surfaces of exchangers is called fouling. Fouling results in retardation of heat transfer across the surfaces. Generally three kinds of fouling persists in cold box exchangers: Rime of H 2 O, CO 2 and NH 3 Non-uniform solids fouling Fouling by oil 10/25/2010 15 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

16. 1. Rime of H 2 O, CO 2 and NH 3 Rime of H 2 O, CO 2 and NH 3 solid water carbon dioxide and ammonia can continuously accumulate in the feed gas passages (FG) of the upper part of exchangers (i.e. E-125A1 and E-125B1). Minimizing Rime Fouling: Rime fouling can be suppressed and minimized by correct regeneration and operation of driers. Removal of Such Kind of Fouling: Such kind of fouling can be removed by De-riming. 10/25/2010 16 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

17. 2. Non-uniform solids fouling Non-Uniform solid fouling Desiccant and filter material from the drier Sand and debris from other sources can cause partial plugging and mal-distribution of flow from the cores. Minimizing Non-Uniform solid fouling : Non-uniform fouling can be minimized by monitoring Filter Delta P Drier Delta P Alternatively replacement of filters preferably after each 2 months. (Reference Kemira Study Report) Removal of Such Kind of Fouling: Such kind of fouling can be removed by Rupture Disc Blowing and back blowing. 10/25/2010 17 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

18. 3. Oil Fouling Fouling by Oil: Slight slip of oil along feed gas passage to E-126 always persists and results in oil film fouling after a period of six months to year in E-126 exchanger. Major sources of oil slippage are: Lube oil may enter the process side during normal operation During uncontrolled shut down and major upsets Removal of Such Kind of Fouling : De-riming Cold Box exchangers up to 80˚C Solvent Wash By Methylene Chloride By Naphtha 10/25/2010 18 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

19. Identification of COLD BOX fouling Two methods proved to be very effective for identification of fouling in Cold box are: Temperature Pattern across the exchangers (This method was recently used to locate fouling across the exchanger during plant shut down on 13 th August). Pressure Pattern across various section of cold box 10/25/2010 19 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

20. (B). Bad mode Operation of COLD BOX When waste Gas exit T of E-126 becomes much cooler Waste Gas instead of cooling FG in E-126 , itself being Cooled by FG from Expander. So Expander has to do more Refrigeration E-125 A2/B2 apparently seems to be performing over-efficient Liquid carried to the cores of E-126 10/25/2010 20 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

21. Bad mode Operation of COLD BOX Reasons for cold box Bad Mode operation “ Conditions which accelerates cold box shift to bad mode. Fouled exchangers are greater chances to stuck in Bad Mode. Cold Box going to Bad Mode during start-up. “ But it is very difficult to come with a set of procedure that always will force the operation back to good mode if plant deteriorates into bad mode.” Decrease waste gas P as far as Possible. Venting Waste gas between E-126 and E-125. ( sometimes prove to be helpful to force operation back to good mode specially during start-up) 10/25/2010 21 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

22. Modification at Kemira to avoid Bad Mode WG Flow reversal of E-127 (Partial condenser) to avoid liquid carry to E-126 WG Passages 10/25/2010 22

23. Bad mode of COLD BOX WG Flow through E-127 before May, 1979 Syn Gas in Tube Side Syn Gas tube side out waste Gas in Shell Side waste Gas out Shell Side 10/25/2010 23 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

24. Bad mode of COLD BOX WG Flow reversal of E-127 Partial condenser Waste Gas Flow in E-127 Impingement Plate Longitudinal Baffles 10/25/2010 24 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

25. (C) Mal-distribution in cold box exchangers Situation at Dispersed Flow: Waste Gas in E-126 10/25/2010 25

26. Mal-distribution in cold box exchangers Situation at Segregated Flow: Waste Gas in E-126 Difference between Mal-Distribution and Bad mode ? 10/25/2010 26 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

27. (D) High ∆P across Expander 1-C-103 Following Parameters contributes to high ∆P across the Expander: Mal-distribution in WG Passage of Exchangers Bad Mode Operation of Cold Box Fouling In Cold Box Exchangers Leakages in Cold Box Level loss in Purifier rectifier column 10/25/2010 27 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

28. Important Practices at Kemira Liquid Nitrogen Injection system Frequent back blowing and Rupture Disc blowing of Feed Gas passages of E-125 (upper exchangers) Deriming of cold box Solvent wash under supervision of Linde Experts Kemira Research Technical Services Department (RTS) Simulation study on Cold Box Performance Addressing issues relating to cold box in collaboration with Process, Operation and Linde Experts) New cold box study (Oil Free expander) 10/25/2010 28 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED

29. THANKS 10/25/2010 29 PROCESS ENGINEERING - FATIMA FERTILIZER COMPANY LIMITED