What are the key points to consider when constructing and commissioning new hydrogen production facilities?

This post was last edited by jbcyf on 2013-6-22 08:27. 4.1.2 Startup steps 4.1.2.1 Nitrogen purging and airtightness testing of the equipment. Airtightness requirements: 1. Ensure that the process is properly set up during airtightness testing, so that there is no overpressure or pressure leakage. 2. Conduct thorough checks for airtightness; ensure airtightness in all flanges, valve bodies, drain pipes, welds, and control valves, paying special attention to flanges that have been disassembled and areas that have been reworked. 3. Record the identified leak points and mark them with chalk; after the maintenance personnel have addressed them, continue to test for airtightness until it is satisfactory. 4. The medium- and low-activity methanation catalysts are in a reduced state; it is strictly prohibited to introduce oxygen-containing gases into the reactor. I. Desulfurization system (airtight pressure: 2.5 MPa) Airtight flow path: High-pressure nitrogen → V-101 → E-106 → F-103 → R-104/AB → R-109 → R-105/AB → upstream of the valve before FCV-1203 ； →E-301 (tube side) → Before the downstream valve of PCV-1102: Introduce nitrogen to seal the natural gas line up to before the blind flange of PCV-1110 ； Lead the nitrogen-sealed feed oil line to upstream of the valve in PCV-101 and in front of the boundary blind flange ； Lead the nitrogen-sealed hydrogen return line to in front of the blind flange in the northern boundary area ； Introduce nitrogen to the outlet of the hermetically sealed hydrogen compressor → line V-101 to behind the hydrogen compressor outlet valve. II. Converter: After the interior of the waste boiler has been worked on and the manholes have been sealed, the check valve FCV-1203 is adjusted, and a blind plate is used to purge the converter tubes and the waste boiler with nitrogen from the desulfurization system; the gas is discharged at the \"8\"-shaped blind plate located at the waste boiler’s outlet. Once the oxygen level is reduced to less than 0.5%, under positive pressure, the \"8\"-shaped blind plate at the waste boiler’s outlet is adjusted again, and the converter tubes and the waste boiler are pressurized to 2.5 Mpa to ensure airtightness. Medium-low pressure conversion, methanation, and decarburization systems: Airtightness pressure: 1.6 Mpa. Airtightness procedures: Close the valves downstream of FCV-1309, FCV-1310, LCV-1307, as well as the bypass manual valves, and isolate T-411 ； Close the V-404, 407, 410 hydraulic downstream valves and the bypass manual valves to isolate T-431 ； Pay attention to the pressure changes in the T-411 and T-431 systems to prevent internal leakage and pressure crossover in the manual valves. T-408 is filled with low-pressure nitrogen, which is then discharged through drains such as V-403 and V-410. After the decarburization system has been purged to an O2 level of <0.5%, the medium/low pressure converters and the methanation reactor are connected to the process. Nitrogen is introduced into the conversion system following the specified procedure to achieve pressurization and airtightness. R-301→E-302→E-303/AB→R-304→E-401→E-402→V-403→E-405→E-406→V-407→T-408→E-409→V-410→E-306/AB (pipe)→E-302→R-305→E-306/AB (shell)→E-307→V-308→ahead of the downstream valve of PCV-1304. Introduce nitrogen and seal hydrogen to the two-hydrogenation line, in front of the blind flange in the northern boundary area ； Introduce nitrogen and seal hydrogen to a hydrogenation line in front of the blind flange in the southern boundary area ； Introduce nitrogen and seal hydrogen to the South Sulfur line, in front of the blind flange in the southern boundary area ； Lead the nitrogen-sealed company hydrogen line to the blind flange in the southern boundary area ； III. PSA System: Airtightness pressure: 1.6 Mpa. Airtightness procedure: After the construction of E-302 is completed, connect the outlet of the medium-pressure transformer to the blind flange of E-301; then introduce nitrogen through this connection to purge and displace the PSA heat exchange system. Venting is carried out at the “8”-shaped blind flange at the PSA inlet. Once the oxygen level is reduced to less than 0.5%, under positive pressure conditions, the “8”-shaped blind flanges at the PSA inlet and outlet are connected again, and the pressure is raised to 1.6 Mpa to achieve airtightness. R-301→E-301→E-302/ABC (tube side)→V-301→E-303→V-302→E-304→V-303→E-305→V-304→each PSA adsorption tower→hydrogen compressor inlet. IV. Boiler system: Airtightness pressure: 2.5 Mpa. Airtightness procedure: Close the low-pressure nitrogen isolation valve; no low-pressure nitrogen is required at other locations. Under these conditions, open the manual valve that allows high-pressure nitrogen to flow into the low-pressure nitrogen in the desulfurization tank, thereby filling the V-210 system to an airtight pressure of 2.5 Mpa. V-210→ P-211→R-208 water protection section→V-210→ahead of the downstream valve of PCV-1210. →P-215 outlet → before the downstream valve of FCV-1315 → E-302/B (shell side) → E-405 (shell side) → E-303/AB (tube side). V. Fuel gas system: Airtight pressure: 0.4 Mpa. E-205 is filled with low-pressure nitrogen; venting is carried out from the high point of the fuel gas stream in R-208, and PCV-1201 and FCV-1105 are used for drainage to remove oxygen levels to below 0.5%, after which the system is pressurized to achieve airtightness. 4.1.2.2 Device cold nitrogen circulation 1. Requirements: ⑴ Establish the flow path; pressurize the entire system with nitrogen to 1.2 MPa, ensure proper purging such that O2 level is <0.5%. ⑵During circulation, FCV-1103, PCV-1107, the FCV-1107 bypass line, and the F-1103 main line must be opened, with the circulation rate to be maintained above 12,000 m3/h. ⑶Pay close attention to the current and outlet temperature of the hydrogen compressor to prevent overheating and overcurrent. ⑷After the circulation is established, it is necessary to regularly open the drain valves at various low points to prevent freezing. ⑸When vanadiumizing the decarburization system statically, attention should be paid to maintaining a heating rate of 10~15°C/h. ⑹Starting from the activation of the press, each position begins to take records and fill out all the forms. 2. Cold nitrogen circulation process: Hydrogen compressor → V-101 → E-106 → F-103 → R-104/AB → R-109 → R-105/AB → R-208 → E-209 → R-301 → E-302 → E-303/AB → R-304 → E-401 → E-402 → V-403 → E-405 → E-406 → V-407 → T-408 → E-409 → V-410 → E-306/AB (pipe) → E-302 → R-305 → E-306/AB (shell) → E-307 → V-308 → V-308 to C-701 crossover → Hydrogen compressor. →R-301→E-301→E-302/ABC→V-301→E-303→V-302→E-304→V-303→E-305→V-304→PSA heat exchanger to C-701 crossover line→hydrogen compressor. 3. Static vanadiumization for decarbonization: (1) Shut off the vent at the top of tower T-411, start P-430, and send the solution from V-427 to the bottom of T-411 via an activated carbon filter. (2) The liquid delivery volume is 42 m3 (i.e., the V-427 liquid level drops by 1.5 meters). (3) Start up FCV-1308 to heat the solution at the bottom of T-411 at a rate of 10~15°C/h. The temperature is based on TI-1320. (4) The static vanadization time is 12–30 hours. 4.1.2.3 Device thermal nitrogen circulation Process conditions: circulation rate > 10,000 m3/h, PIC1304: 1.0–1.2 Mpa; each reactor bed is heated according to the heating curve. Water washing of the boiler system and establishment of water circulation: 1. Introduce demineralized water into V-214; after the water at the bottom is drained, a normal liquid level is established. Then P-215 is started to feed water into V-210. Intermittent drainage is carried out, and once the water has been drained, a normal liquid level is achieved in V-210. P-211 is then started to establish water circulation. Intermittent and continuous drainage are used to maintain the liquid level in V-210 at 40–50%. The boiler system is washed, and any leaks in the water system are checked. 2. Add chemicals to the water in V-217, start P-216 and P-217, and check whether the chemical addition process is unobstructed. 3. Dynamic vanadiumization during decarburization: (1) After static vanadiumization is completed, open the manual valve from T-411 to E-421; after the P-419 filling pump is started, activate P-419 to send liquid to T-408, then start P-430 to replenish liquid into T-411, ensuring that the liquid level in T-411 remains at 40–50%. (2) Once the liquid level in T-408 reaches 50%, LCV-1307 is activated to maintain normal liquid levels in LCV-1306 and LCV-1307, allowing P-419 to operate in a dynamic cycle. (3) Fully open the TIC1317 bypass line, close the manual valves at the inlet and outlet of the process gas to E-402, open the manual drain valve at the bottom of E-402, and activate FCV-1308 to heat the solution at the bottom of T-411. Raise the temperature at a rate of 10~15°C/h until it reaches around 105°C; the temperature should be monitored using TI-1320. (4) Once the liquid level LI1305 in tower T-411 reaches 50–60%, start P-418 to supply liquid to T-408, thereby establishing a circulation system with two towers, three liquid levels, and two pumps. (5) The circulation rate of the lean liquid is controlled at around 50 t/h, while that of the semi-lean liquid is controlled at around 150 t/h. The temperature of the lean liquid entering T-408 is around 70°C; the pressure in T-408 is controlled at 1.2 Mpa, and the pressure in T-411 is between 15 and 20 kpa. (6) When there is a liquid level in LCV-1304, P-416 can be started; deionized water must flow through E-412 and 420 to prevent uneven heating. (7) During dynamic vanadation, the solution is analyzed routinely once per hour to maintain the total potassium level at around 25%. (8) Dynamic vanadization time: 24–72 hours. 4. F-103 ignition and heating: After the fuel gas system has been properly purged, the fuel gas is introduced into the unit; fire-suppression steam is used to purge the furnace chamber. Sampling and analysis show that the explosive gases in the F-103 furnace chamber are within acceptable limits, after which F-103 is ignited and the temperature is increased at a rate of 30°C/h. 5. R-208 Ignition and heating: (1) After the cold nitrogen cycle is established, check that XV-1201, 1202, 1203, and all the ignition nozzles are in the closed state; also check the dampers in the hot air ducts and ensure that the air valves for each burner operate properly. After normal operation, start C-206 and 207 to control the negative pressure in furnace R-208 at 50–80 Pa. (2) After the sampled gas from the R-208 furnace chamber is found to be suitable for use, the R-208 furnace is ignited in accordance with the ignition sequence and temperature rise curve of the converter; the temperature is raised at a rate of 30°C/h until it reaches 120°C, after which the temperature is maintained at that level for 8 hours. (3) Use convection zone nozzles to control the inlet temperature of the converter, and use tunnel nozzles to control the outlet temperature of the converter. 4.1.2.4 Steam for conversion and medium-shift reaction, heating of low-shift and methanation crude hydrogen, reduction of conversion catalyst – Temperature requirements: (1) Steam supply conditions: Inlet temperature for conversion ≥ 320°C, temperature in the medium-shift bed ≥ 150°C. (2) The normal flow is discharged through the low-temperature transformer before steam is introduced. (3) After introducing steam, stop using steam for heating via FIC1308; the low-temperature transformed gas is routed through the E-402 process. When activating E-402, the steam condensate must be drained first, after which the low-temperature transformed gas is introduced, and finally TIC1317 is closed. (4) For conversion, first open the drain on the pipe rack to drain any remaining water before steam generation, then slowly open its main valve. After draining the water again through FIC1204’s drain, conversion can be initiated. (5) After the boiler starts generating steam, the drum can have its pressure gradually increased to 2.0 Mpa in accordance with the heating curve. Once the pressure exceeds 1.0 Mpa, PCV-1210 is activated to feed the steam into the LS pipeline network; the manual valve for releasing steam through the pipe bank must not be opened. (6) Pay attention to the dehydration of the catalyst at the medium-temperature inlet during the heating process with hot nitrogen. 1. Temperature increase for low-shift and methanation reactors: When the inlet temperature of the conversion unit is ≥320°C and the temperature in the medium-shift bed is ≥150°C, that is, before steam is supplied to the conversion unit, the low-shift reactor is taken out of the main process flow; the \"crude hydrogen gas\", namely the gas flowing through tube side of vessel E-302, is used to heat the low-shift reactor and the methanation reactor. A. First close the feed line valve, then close the inlet and outlet valves; open the inlet and outlet valves for the crude hydrogen going to the low-pressure converter, and reduce the flow rate by closing the large inlet valve for methanation. B. Reuse the general \"crude hydrogen\" heating process; try to heat the low-temperature shift reactor first, and for the methanation reactor, it is sufficient to allow gas to flow through it. 2. Steam supply for conversion: (1) Once the inlet temperature of the conversion unit is ≥320°C and the temperature of the medium-temperature shift bed is ≥150°C, start by feeding the steam produced internally into the conversion unit, then add Z35 steam, gradually increasing the flow rate to 20–25 t/h. (2) Once the steam for conversion is operating normally, open the company’s hydrogen or hydrodual reduction hydrogen return valve to supply reducing hydrogen, and maintain the hydrogen concentration in the recycle gas at over 65%. (3) After converting to steam, the condensate water from each separator in the PSA heat exchange process is routed to the T-431 process. (4) Introduce hydrogen back; after hydrogen blending, when the H2% in the recycle gas is >90, the PSA performs pressure increase for displacement. 3. Reduction of the conversion catalyst: Conditions for reducing the conversion catalyst: inlet temperature of 490–500°C, outlet temperature of the catalyst bed at 790–800°C; hydrogen concentration in the recycle gas above 65%, with a H2O/H2 ratio of 3–7.5:1. Reduction time: 8 hours; recycle volume > 10,000 m3/h; steam supply: 25 t/h. Once the low-temperature outlet temperature reaches 180°C, the “crude hydrogen” heating process can be removed to improve the main process. During the modification, the inlet valve of 305 must be opened fully before closing the tube-side valve of E-302 leading to R-304; the R-304 and R-305 valves should then be operated in parallel to start up the reduction line, after which the inlet and outlet valves of R-304 should be opened and its branch line valve closed. 4.1.2.5 Desulfurization by oil injection – production of qualified industrial hydrogen 1. Requirements for oil injection: (1) The feed oil should be used to flush the feed and return lines for 6 hours in advance, and it is necessary to ensure that all valves related to the feed oil are fully closed before starting the oil injection process. (2) Gradually raise the F-103 outlet temperature to 380°C before oil injection. (3) Before oil injection, route the recycle gas through the PSA heat exchange process to the HIC1303 vent, control the flow rate at FIC1301 to keep it low, and close the valve at the inlet of the PSA heat exchange dehydrogenation compressor. (4) Before oil injection, reduce the circulation rate; use the PIC1107 control valve for regulation, close the valves of the main line F-103 and all its branch lines, and control the hydrogen return flow at 4000 Nm3/h. (Reduce the opening of the balance valve.) (5) After the circulation gas volume decreases, connect T-408 to the main flow path. (6) During oil injection, it is essential to coordinate well between the indoor and outdoor areas. Do not start the oil injection too aggressively; increase the feed flow rate only after the temperature drops by three degrees as a result of the conversion process. (7) Pay attention to whether the flow rate indicators for the crude oil and steam are accurate; if there are any issues, contact the instrumentation team promptly for handling. 2. Introducing T-408 into the main process: When connecting it to the absorption tower, first gradually open its inlet valve; once pressure is balanced, close one of the two bypass valves. Once the pressure gauge at the bottom of the tower shows a slight increase, open the outlet valve of the absorption tower, and then close the two auxiliary line valves. Pay attention to the V-410 liquid level; in the event of a liquid carryover incident, immediately shut down the tower and transfer the solution urgently to the regeneration tower. Desulfurization with oil injection: 3. Oil injection operation: Hydrogen return rate of 4,000–5,000 m3/h, steam supply of 25 t/h; outlet temperature of F-103 at 380°C, inlet temperature at 490–500°C; bed temperature in R-305 above 280°C. The low-temperature shift reactor, absorption tower, and methanation unit are all operating in normal mode. Oil feeding is carried out in several stages; during this process, FCV-1104 and FCV-1106 are gradually activated. The amount of oil fed is increased according to the requirements, and the feed rate can be increased appropriately only after the temperature drops by three degrees. The pressure is controlled at 1.3 Mpa by the PCV-1304 control system. Notify the laboratory to analyze the industrial hydrogen once oil injection is operating normally. Once the industrial hydrogen meets the requirements, it can be sent to the first and second hydrogenation units. The hydrogen return is changed from C-701 to two-stage high-pressure hydrogen return; C-701 is operated at idle speed. The manual valves from C-701 to V-101 and E-301 are closed, and the manual valve for the line from V-308 to C-701 is also closed. Once oil injection is normal, activate T-431. Adjust the various process parameters to meet the process specifications. Contact the lab to add samples for various analyses. 4.1.2.6 PSA startup and hydrogen delivery from the hydrogen compressor: ⑴ Once the composition analysis of the intermediate-pressure gas is satisfactory, the PSA can be used to increase the pressure of this gas. ⑵On the DCS operation screen, click the start button for the hydraulic system to bring it into operation. ⑶When raising the PSA pressure, do so slowly – increase the pressure in the adsorption tower by about 0.1 Mpa per minute – to prevent fluctuations in the pressure of the desulfurization and conversion systems caused by high gas consumption by the PSA system. ⑷When driving the PSA, adjust the pressure of the PIC1327 system in a timely manner to maintain stable system pressure. ⑸When the pressure in the adsorption tower rises to 1.3 Mpa, the PSA unit starts up and operates in high-speed self-circulation mode; the desorbed gas is sent to the flare via PIC1406, while hydrogen from unqualified products is also sent to the flare. After the PSA desorbed gas is operating normally, divert the PSA desorbed gas to R-208. ⑹After the PSA has been operating for a period of time and the purity of the product hydrogen reaches 99.9%, PIC1403 is slowly opened, the valve that directs the product hydrogen to the flare is closed, and the product hydrogen is fed into the hydrogen compressor. ⑺The hydrogen compressor is loaded and the pressure is increased in cycles; once the outlet pressure reaches 2.0 Mpa, the compressor is opened to connect to the pipeline network, and the hydrogen is sent to the pipeline system. (8) Adjust the high-pressure hydrogen load according to scheduling requirements, and carry out the adjustment operations.

Purging and airtightness testing must be carried out strictly, and the instruments need to be reliable.