[Weekly Topic] June 4-11, 2011

When insulating for heat retention, do not work on rainy, snowy, or overcast days to prevent water from accumulating on the outer surfaces of pipes and equipment

Questions for the Purification Position Exam 1: What are the three methods for replenishing methanol in the methanol washing system? Answer: 1) Replenish the pure methanol in T-FB204 into DA202/DA402/FB201 via T-GA204； 2) Top up methanol in FA205 to DA202 via GA205 ； 3) Top up FB201 methanol to DA202/DA402 via GA206. 2. What should be done if the filter for regenerated nitrogen at the outlet of the 500# molecular sieve becomes clogged? Answer: 1) Confirm that the cooling of the regenerated nitrogen is complete, then close the inlet and outlet valves of the filter ； 2) Open the release valve to relieve pressure and hand over for cleaning ； 3) After cleaning, reinstall it, close the discharge valve, and open the inlet and outlet valves. 3. How can GB201 be made compliant? Answer: 1) Close the inlet and outlet valves of GB201 ； 2) Open the flare valve to relieve pressure ； 3) Open the low-pressure nitrogen valve to perform nitrogen purging of the system ； 4) Open the inlet drain and the drain behind PC205A, discharge the contents completely, then take a sample for analysis; if the O2 concentration is less than 0.5%, the replacement is considered successful. 4. How to prepare the GA402 pump as a backup? Answer: 1) Confirm that the pump is powered on ； 2) Close the outlet valve completely, open the inlet valve completely ； 3) Open the minimum flow valve ； 4) Open the flow-limiting orifice valve for cooling ； 5) Verify that the oil level in the oil cup is normal ； 6) Confirm that the cooling water is functioning properly ； 7) Confirm that the purging nitrogen is normal, at about 1 M3/H ； 8) Regular turning of the turbine. 5) Describe the entire process of shutting down the methanol washing unit. Answer: 1) Stop GB201; the vapor is vented through PC205B ； 2) Acidic gases from Tower DA203 are vented through PC203B1 ； 3) Reabsorbed exhaust gases are vented through PC252B ； 4) Stop supplying CO2 in connection with urea shutdown; stop GB401 ； 5) Reduce the load on the gasifier; reduce the circulating methanol in proportion ； 6) Confirm shutdown of Unit 500, and open the pipelines for operation ； 7) Turn on the high-pressure switch FC301, stop the conversion process, turn off HC203 and HC401, and perform nitrogen displacement ； 8) For the methanol system’s pressure retention cycle, if it is difficult to maintain the pressure, open the high-pressure nitrogen filling valve to ensure that the pressure of PIC202/PIC404 remains above 4.0 MPa ； 9) Shut off valves for each ammonia cooler ； 10) Stop the methanol circulation when the total sulfur analyzed by S227 is less than 2 ppm ； a. Store methanol in DA203 as much as possible ； b. Try to keep the liquid levels in the other towers as low as possible ； c. When shutting down the pumps, GA201 should be stopped first, followed by GA202, to prevent the EA206 pipeline at room temperature from freezing and cracking ； d. Closely monitor the liquid levels in various high-pressure and low-pressure areas; shut down the EMV207/LV406 as well as the FC402, FC204, and LV411 isolation valves ； e. Close the high-pressure nitrogen valve and open the vent valve. 6. How is the nitrogen washing unit cooled while driving? Answer: 1) Pressure setting: PIC55207 at 1000 KPa, PIC55214 at 50 KPa, PIC55212 at 500 KPa. 2) Introduce high-pressure nitrogen to bypass FC053A, thereby equalizing the pressure in front of valves FIC55203/FC55204. After voltage equalization, fully open FC053A and close the bypass valve. Slowly operate FC55203/FC55204 to pressurize the T-501 tower to 1000 KPa. 3) Throttling refrigeration: Nitrogen is throttled to 1000 KPa via FIC55203/FC55204, and then the gas enters the nitrogen washing tower. Open TDCV55208, and nitrogen enters the synthesis gas pipeline. At the site, after opening TC55201, the two vent valves were opened to cool the raw material gas pipeline. Open the bypass around the P501 inlet and outlet, and open LIC55201; nitrogen enters the carbon monoxide pipeline. Open LIC55203 and throttle to 250 KPa via LIC55203; nitrogen then enters the methane-rich pipeline. Adjust the opening degree of various valves to control the nitrogen flow rate and cooling rate

1. Installation of the insulation layer on horizontal pipe sections: The soft insulation material should be tied together using galvanized iron wire of gauge 14–16; the spacing between these ties must not exceed 200 mm. There should be no fewer than two ties per piece of insulation material, and the tying should be even in terms of tension and consistency in thickness. The unit weight of the compressed insulation material must meet the design requirements. The seam width of the insulation layer shall not exceed 5 mm. The insulation material should be in close contact with the pipe wall; longitudinal seams should be located at the upper part of the pipe, at an angle of about 45° from the vertical centerline of the pipe. At flanges and valves, insulation work should be carried out after the connecting bolts have been tightened cold; moreover, a gap of the length of the bolts plus 25 mm should be left on one side of the flange. 2 For the installation of the insulation layer on vertical pipe sections, it should start from the supports; the insulation material is laid from bottom to top, and then tied together circumferentially using 14–16# galvanized iron wire. For pipes with a diameter of DN>100mm that do not have fixing elements, 8# galvanized iron wire should be used to form twisted braid loops on the pipe wall, and these twisted braid cords are then used to secure the insulation layer with the galvanized iron wire. 3 Installation of insulation layers at elbows, tees, and reducers: When installing insulation material at elbow locations, if no pre-formed products are available, the pipe casing or sheets should be processed into a shape similar to that of shrimps in order to facilitate assembly. For the installation of the insulation layer at the tee joints, for lower tees, the insulation layer of the vertical pipe should be installed first, followed by that of the horizontal pipe; for upper tees, the insulation layer of the horizontal pipe should be installed first, followed by that of the vertical pipe. This helps to prevent water from seeping into the pipe walls to the greatest extent possible. When installing the insulation layer for reducer pipes, the pipe casing or sheets should be processed into trapezoidal or fan-shaped sections for assembly. Tie it with two strands of galvanized iron wire as well. 4 Installation of valve and flange insulation layers: The installation of the insulation layers for valves and flanges must be carried out after the valves and flanges have been tightened. Since it is a part that requires frequent maintenance, it must be designed with a detachable structure. The installation of the insulation layer and the protective layer is carried out simultaneously. 5 In all areas that are connected by screws and require cold tightening, the insulation layer and protective layer should be applied separately after the cold tightening is completed. 6 Use standardized shell materials, which are installed on horizontal pipes; they must be covered both above and below and connected in a staggered manner. 7 During the insulation installation process, it is crucial to prevent the insulation material from getting wet, especially in outdoor applications. The horizontal joints of the shell materials should be oriented toward the sides. When installed in vertical pipes, construction should proceed from bottom to top. The gaps between all prefabricated pipe shells or plates should be filled with mortar made from materials with similar heat conduction properties, or with soft materials having the same or lower heat conduction coefficient, ensuring that the gaps are completely filled and compacted. Avoid using spiral binding. During construction, insulation and protective layers should be applied simultaneously, along with emergency measures to prevent rain.

During the insulation installation, it is crucial to prevent the insulation material from getting wet; especially in outdoor applications, the horizontal joints of the pipe insulation materials should be oriented toward the sides. When installed in vertical pipes, construction should proceed from bottom to top. The gaps between all prefabricated pipe shells or plates should be filled with mortar made from materials with similar heat conduction properties, or with soft materials having the same or lower heat conduction coefficient, ensuring that the gaps are completely filled and compacted. Avoid using spiral binding. During construction, insulation and protective layers should be applied simultaneously, along with emergency measures to prevent rain.

During the insulation installation, it is crucial to prevent the insulation material from getting wet, especially in outdoor insulation applications. When installed in vertical pipes, construction should proceed from bottom to top. The gaps between all prefabricated pipe shells or plates should be filled with mortar made from materials with similar heat conduction properties, or with soft materials having the same or lower heat conduction coefficient, ensuring that the gaps are completely filled and compacted. Avoid using spiral binding. During construction, insulation and protective layers should be applied simultaneously, along with rainproof emergency measures.

Insulation should be carried out on sunny days, and preferably when the pipes and equipment are dry. Vertical pipes should not have any gaps, and it is best to seal any gaps in valves with mortar