Problems after 50% capacity expansion and transformation of Ningxia Petrochemical's secondary fertilizer ammonia synthesis unit

You can refer to the transformation information of Yuntianhua and Lutianhua and communicate with each other. We also need to renovate here. I don’t know what modifications you have made. Do you have relevant information? Please give me one, thank you!

Many of the questions raised by the poster are related to equipment bottlenecks, which are difficult to solve. I wonder if there is any big difference between the transformation method of Yuntianhua, which has been successfully transformed in China, and the transformation plan of your factory?

There is a lot of information, but I can send you a rough summary.

1. Current situation of the device When the ammonia synthesis device was re-designed in 1997, a series of energy-saving technical transformations were carried out on the device to improve the technical level of the device. It was completed and put into operation in September 1999. After nearly 6 years of technical transformation and production operation, the ammonia synthesis device can reach a production capacity of 1000 t/d in the short term. 1.1 Main technical transformation contents completed since it was put into production: ——The boiler feed water pump 104-JA has a new speed increaser to increase the pump speed and increase the pump capacity. ——The decarburization reflux pump 108-J was modified to adapt to the characteristics of the modified MDEA decarburization process, which has less solvent volatile components. ——Modification of the 103-D inlet mixer of the second-stage reformer, with an inner diameter of Ф457, a wall thickness of 10mm, and a height of 890mm. ； ——Added CO2 water cooler 110-C2 with a heat exchange area of ​​712.8m2 ； ——Added CO2 ammonia cooler 110-C3 with a heat exchange area of ​​195m2 ； ——Surface condenser 135-JC was modified to change the heat exchange tube material from aluminum alloy to copper tube material to enhance heat transfer. ； ——The decarburization lean liquid pump 107-JB is changed from motor drive to steam turbine drive ； It is currently being converted to a hydraulic turbine. The turbine is in place and the pipelines have been completed. It will be put into use after 50% capacity expansion and transformation. ——The desulfurization system was transformed by canceling the two activated carbon desulfurization tanks at the 102-J entrance and adding two parallel zinc oxide desulfurization tanks at the 108-D outlet. ； ——A new dryer (Q=40Nm3/min, V=0.839m3) and oil remover (Q=40Nm3/min, V=0.612m3) are added to the air compressor station. ； In August 2003, a new instrument air system (Q=100Nm3/min) made in Belgium was added. Now a single unit can meet the production needs of the second fertilizer and deliver part of the instrument air to the first fertilizer. ——The air compressor capacity is insufficient, mainly because the atmospheric pressure in Yinchuan is lower than the original design pressure (about 0.0049MPa lower) ； In October 2004, the air compressor was renovated through maintenance. After the remodeling, the new replacement equipment was: Low-pressure cylinder, high-pressure cylinder, speed increaser, and three inter-section heat exchangers. The cooling water of the three inter-section heat exchangers is changed from primary water to circulating water. 1.2 The main problem - the gas volume in the synthesis section of the syngas compressor does not match the gas volume in the circulation section. The reason is that when the design was restored, the ammonia synthesis tower was changed to Casale internals, which increased the net ammonia value of the loop and decreased the circulation volume. ； ——The main reason for the surplus of low-pressure steam is that the water/carbon ratio in the conversion process is high, and the MDEA regeneration heat load is lower than that of the original sulfolane. Therefore, the steam used by the steam reboiler decreases. 2. Renovation Principle: The synthetic ammonia production unit shall be renovated according to the production capacity of 1500 t/d. 3. Introduction to technological transformation 3.1 Main transformation of transformation: 3.1.1 Pre-conversion The newly added equipment in the pre-conversion unit is as follows:: The adiabatic pre-reformer is filled with Topsoe's AR-301 reforming catalyst flame heating furnace. The convection section includes preheating coils and waste heat recovery to preheat the raw gas to the first-stage reformer to 650°C. Preheat the temperature of the mixed raw gas to the new pre-reformer to 480°C. Preheat the temperature of the natural gas to the new desulfurization unit to 350°C. Three sets of waste heat recovery coils are used to generate high-pressure steam of 10.7MPa g and 515°C. 3.2 Add a heating furnace. The main purpose of adding the radiant section of the heating furnace is to heat the pre-reformed gas to 650°C. In the convection section, the natural gas is preheated to 350°C, and the mixed raw gas is preheated to 480°C. In order to improve the thermal efficiency of the entire heating furnace, the high-pressure steam must be superheated and the combustion air must be preheated. The burner of the heating furnace adopts forced ventilation type, with 10%-20% excess air, and has low NOX emission. Install a blower with an inlet filter and an induced draft fan, both driven by electric motors, with the fans regulated by an inlet damper. 3.3 One-stage furnace transformation The existing reforming furnace (101-B) has 8 rows of furnace tubes, each row has 42 tubes, the outer diameter is 108mm, the inner diameter is 85mm, the material is HK-40, and the catalyst loading amount is 19.5m3. After calculation, its maximum production capacity can reach 1360t/d ； When the production capacity reaches 1500 t/d, the average heat transfer intensity of the furnace tube will exceed 0.36GJ/h.m2, so 101-B will become the bottleneck of conversion and production increase transformation. 3.3.1 Replacement of the 101-B radiant section furnace tube upper gas collecting pipe, furnace tube, lower gas collecting pipe and riser pipe will be replaced. The inner diameter of the riser will be expanded from 92mm to 105mm. When the inlet temperature of a section of the furnace increases to 650°C, the material grade of the inlet pipeline of the section of the furnace must be improved. The inlet pipeline and upper gas collecting pipe will be made of stainless steel (ASTM A 312 TP 321 H). In this renovation, all existing furnace tubes will be replaced with the latest microalloy materials.: 25/35 Cr Ni Nb Ti, the inner diameter of the furnace tube is slightly increased to 87mm, and the mechanical design temperature of the furnace tube can reach 950°C. The reformer tubes are filled with Topsoe's R67-7H reforming catalyst. : The size of the upper 50% of the catalyst is 20 ´ 13 mm, and the size of the lower 50% of the catalyst is 20 ´ 18 mm. The purpose of selecting relatively larger particle catalysts is to control the resistance drop of the furnace tube. . Using the above catalyst in combination with the new furnace tube, the resistance of the furnace tube was reduced to 215kPa. 3.2.2 Appropriately optimize existing process operating parameters. Reducing the water-to-carbon ratio of the first-stage conversion from the original design value of 3.5 to 3.2 can reduce the process steam by 9.4t/h. In addition to slightly reducing the heat load of the first-stage furnace, combined with the low-energy decarbonization process, it can alleviate the current problem of excess low-pressure steam, reduce the amount of venting, and reduce energy consumption. 3.3 Replacement of 103-D two-stage furnace air mixer The two-stage reforming furnace is filled with 20.9 m3 Topsoe Company's RKS-2-7H catalyst. In order to avoid sintering on the top catalyst, a 300mm RKS-2P catalyst is also loaded on the RKS-2-7H catalyst. In order to avoid uneven gas mixing in the top combustion chamber, an air mixer with a new nozzle from Topsoe was installed. 3.4 Transformation and transformation The existing high-variation furnace and low-variation furnace have axial structures. After the production is increased to 1500t/d, the system resistance will reach about 0.25MPa, which is very unfavorable. Therefore, the existing high-variance furnace and low-variance furnace are changed to axial-radial structures. In addition, in order to reduce the CO content in the shift gas to less than 0.27% (dry), to reduce the loss of methanation H2 and reduce the consumption of raw natural gas. 3.5 Decarbonization transformation The company’s existing decarbonization process is BASF’s activated MDEA, one-stage absorption and one-stage regeneration process. BASF's activated MDEA process has the advantages of large solution absorption capacity, high CO2 recovery rate, lower energy consumption than the hot potash process, and equipment pipelines can be made of ordinary carbon steel. The output of the current device has been increased by 50%. This renovation plan is mainly to tap the potential. Various measures such as increasing the solvent concentration, increasing the activator content, and lowering the absorption temperature are adopted to greatly increase the absorption capacity of the solution and relatively reduce the solution circulation volume. The solution circulation pump, absorption tower and some heat exchangers can use the existing equipment to tap the potential to meet the production increase requirements, reduce the amount of renovation projects, and reduce investment. After system accounting, the decarbonization section mainly adopts the following transformation measures:: ——CO2 absorption tower 101E: Use existing equipment to transform the original plate tower into a high-efficiency structured packed tower ； ——Gas stripping regeneration tower 102E: After calculation, the current tower circulation capacity (tower diameter) is insufficient. Therefore, a new ф4000 high-efficiency structured packing tower was added. 3.6 Methanation transformation After accounting for the methanation process equipment, except for the methanation water cooler (115-C), which has insufficient capacity and needs to be updated, the other equipment can meet the transformation needs. 3.7 Ammonia synthesis transformation will change the existing ammonia separation process before the tower to the ammonia separation process after the tower, and add a synthetic molecular sieve drying device. A synthetic molecular sieve drying device is added to match the ammonia separation process after the tower. A molecular sieve system is added at the inlet of the 103-J high-pressure cylinder of the synthesis gas compressor (downstream of 105-F), which can remove moisture in the synthetic fresh gas to 4ppm and CO2 to 2ppm, which improves gas quality and helps protect the synthesis catalyst. Since the shaft seal was changed to a dry gas seal, the oil separator mentioned in the scientific research report was cancelled. ； The anti-surge return cooler is cancelled, and the backflow from 124-C is still used. ； The site layout of the molecular sieves and systems is now being determined. When the second fertilizer unit was re-designed, the internal parts of the ammonia synthesis tower (105-D) had been changed to Swiss Casale Company's three-bed axis radial and one-layer inter-cooling heat exchange internal parts. At that time, the maximum production capacity of the internal parts modification was considered to be 1200t/d. The production increase target of this technical transformation is 50%, which requires the ammonia synthesis tower production capacity to reach 1,500t/d. After preliminary calculations, Casale believes that the ammonia synthesis tower internals can meet the production increase requirements, but it needs to be finally confirmed by the patentee. 3.8 The ammonia refrigeration system is transformed into hot ammonia to meet the needs of the urea unit for hot ammonia. Due to the increase in ammonia production, a hot ammonia pump must be added to meet the transformation needs. 3.9 Large Compressor Unit Renovation 3.9.1 Air Compressor Unit (101-J/JT) Renovation The compressor was completed during maintenance in October 2004. In this capacity expansion and transformation, only the turbine will be transformed. Simply update the partitions that have not been updated. 3.9.2 Increased production of raw gas compressor unit (102-J/JT) Since the pressure of the natural gas pipeline network entering the boundary area is high, when the ammonia synthesis unit increases production, the compressor can meet the requirements without modification. 3.9.3 Syngas compressor unit (103-J/JT) During the transformation, the internal parts of the compressor were modified, the shaft end seal was changed to a dry gas seal, the original sealing oil system was removed, and the turbines were all replaced with new turbines with high and medium pressure integrated upper exhaust due to reasons such as efficiency, life, and maintenance difficulties. They were equipped with a separate surface cooler. This surface cooler also serves as the condenser for turbines such as 107-JBT/JCT and 101-BJ, and the remaining condensation is borne by the original 103-JC. However, the on-site layout of the new surface cooler and condensate pump must be determined as soon as possible. 3.9.4 Ammonia compressor unit (105-J/JT) modification l The performance of the compressor was reviewed by DELAVAL Company of the United States, and it was confirmed that the compressor does not need to be modified, and the safety and reliability of the unit after increasing the speed meet the requirements. Consider whether to cancel the steam extraction in 2001b and improve some compressor internal parts ； Change the shaft end mechanical seal to a dry gas seal and cancel the original shaft sealing oil system ； At the same time, since the newly added 110-C3 ammonia cooler needs to cool CO2 to below 25°C, this part will be taken into account in the load of 105-J. l The steam turbine needs to be modified, and the modification plan is:: ——Keep the turbine shell, nozzle and foundation unchanged ； ——Transform the original steam turbine rotor into a high-efficiency and energy-saving rotor. Through the above modifications, the production increase requirements of the device can be met. At the same time, in order to ensure the vacuum degree at the outlet of the steam turbine, the condenser needs to be modified to increase the condensation capacity, condensation area and ejector capacity. 3.10 According to the feasibility study report, the transformation of condensate is considered as follows 3.10.1 When restoring the design, a set of medium-pressure steam stripping condensate treatment device was added. However, due to the low pressure of the medium-pressure steam pipe network, there is a certain pressure difference through the stripping tower, which causes instability to the filling system. The factory Now it has been changed to low-pressure steam stripping according to the operating conditions, and the bulk packing of the stripping tower has been changed to structured packing to strengthen mass transfer. After treatment, the content of condensed NH3 and other impurities has reached less than 0.5ppm. However, the low-pressure steam after stripping is directly vented, causing a waste of energy and environmental pollution. 3.10.2 As far as the process condensate treatment process is concerned, the current low-pressure steam stripping process will be changed to a medium-pressure steam stripping process. Replace the stripper and add a heat exchanger. Based on the production capacity of 1500t/d ammonia, there are about 72t/h low variable condensate, and the processed process condensate is sent to the desalted water device. 4. Problems after the implementation of the transformation project 4.1 After the production increase, the resistance of the process system will reach about 2.0MPa. The operating pressure of the upstream equipment should be appropriately increased to maintain the 103-J inlet pressure at about 2.5MPa (A). The corresponding pressure of the natural gas entering the device needs to be increased to 4.2MPa (G). The increase in system resistance is undoubtedly very detrimental to reducing the energy consumption of the entire device. As can be seen from the table, the biggest change in system resistance after the production increase transformation is in the first furnace section. Therefore, how to reduce the resistance in this part is very meaningful. 4.2 Ammonia-carbon balance after transformation The process of using natural gas as raw material to produce ammonia by steam reforming and processing it into urea has the problem of ammonia-carbon imbalance. After the implementation of this project, the processing of 2610t/d urea will require about 41530Nm3/h of CO2 (converted to 100% CO2, the same below). After the synthetic ammonia production is expanded to 1500t/d, the by-product CO2 will be about 38200Nm3/h, and 3300Nm3/h of CO2 will need to be supplemented. There are two carbon supplement options to choose from: * A fertilizer carbon supplement plan: After the first chemical fertilizer is completely changed to natural gas partial oxidation, the low-temperature methanol wash needs to be modified and the CO2 recovery amount needs to be increased. According to calculations, approximately 10460Nm3/h CO2 can be used for secondary fertilizers ； Second fertilizer carbon supplement plan: The MEA method is used to recover CO2 in the flue gas. This solution requires an additional investment of approximately 14 million yuan. 5. After the implementation of the transformation project, the energy consumption of the ammonia synthesis unit is shown in the following table (tons of ammonia consumption) Table 4-1 Serial number project unit After transformation Unit energy consumption before transformation kJ Same type of equipment 1 Natural gas Nm398510263455610222 Electricity kWh1471118405.963 Circulating cooling water m335842725123424 Demineralized water t4. 05.28142352.565 Steam condensate t-2.2-4.5614235--6 Process condensate t-1.15-1.3214235--7 Ammonia energy consumption GJ35.1137.36 (△=-2.25) 36.28 Gcal(8.39)(8.92)(△=-0.53)(8.71) At present, after the technical transformation of domestic ammonia synthesis equipment using natural gas as raw material introduced in the 1970s, the comprehensive energy consumption per ton of ammonia synthesis is generally around 37GJ. After the implementation of this project, the energy consumption per ton of ammonia of the ammonia synthesis device is 35GJ, which is at the advanced level of similar devices in China. However, judging from the indicator of natural gas consumption per ton of ammonia, it is still on the high side.

Gas distribution station process flow description: Natural gas from Changning Company enters the gas distribution station with a pressure of 2.5-3.0MPa. After being measured by FQ-1600, it is transported outwards in six routes. The first route is measured by FQ-1601, decompressed to 1.7MPa by PCV-1601 and sent to the second synthesis workshop as raw gas. The second route is measured by FQ-1602 and passed through PCV-1602. The pressure is reduced to 1.4MPa and sent to the second synthetic workshop as fuel gas. The third route is metered by FQ-1603, and the pressure is reduced to 0.5MPa by PCV-1603 and sent to the water truck workshop as fuel gas. The fourth route is metered by FQ-1604 and sent to the synthetic first workshop as raw material gas. The fifth route is measured by the FQ compound fertilizer meter. The compound fertilizer decompression station is decompressed and sent to the compound fertilizer as fuel gas. The sixth route is sent to the FQ The gas is measured by civilian meters, and is decompressed by the civil pressure reduction station before being sent to civilians for use as fuel gas. 1.1.4.2 Raw gas desulfurization process description The raw natural gas from the off-site gas distribution station is measured by FQ-1601 and pressurized by the raw gas compressor (102-J). The low-temperature section of the convection section of the first furnace is heated to about 220°C, mixed with hydrogen from section 103-J, and then enters the heating furnace (103-B) for further heating to 350°C. The temperature of the low-temperature section of the convection section of the first furnace can be adjusted by bypass TV-04106, and then enters the Co-Mo After final desulfurization in the hydrogenation reactor (110-D) and zinc oxide desulfurization tank (108-DA/DB), the total sulfur in the natural gas is ≤10PPb. 1.1.4.3 Description of raw gas pre-conversion and first-stage conversion process: After the desulfurized raw gas is mixed with medium-pressure steam, it is heated to 444°C by the mixed raw gas coil in the convection section, and then enters the heating furnace (103-B) to be heated to 480°C, and then enters the pre-reforming furnace (109-D) for pre-conversion. After pre-conversion, the residual methane in the gas is about 75%. After coming out of the pre-reformer (109-D), the temperature drops by 47°C. It enters the heating furnace (103-B) at 433°C and is heated to 650°C. The outside of the tube is provided with reaction heat by 36 burners at the bottom. It enters the 336 catalyst reaction tubes of the first-stage furnace (101-B) for steam reforming. The outside of the tube is provided by the 144 burners at the top. After the first-stage transformation, the residual methane in the gas is about 10%. 1.1.4.4 The second-stage reforming process of the first-stage reforming gas shows that the first-stage reforming gas enters the second-stage furnace (103-D), and process air is sent into the second-stage furnace at the same time. The process air comes from the air compressor (101-J) and adds a small amount of medium-pressure steam and is preheated by the convection section air preheating coil. H2 in the reforming gas The heat generated by combustion with oxygen in the air is supplied to the methane in the conversion gas for further conversion in the catalyst bed of the second-stage furnace. The residual methane content of the process gas coming out of the second-stage furnace is about 0.3%. The heat is recovered by the two first waste heat boilers connected in parallel, and then the waste heat is further recovered by the second waste heat boiler and sent for conversion. 1.1.4.5 The high-low temperature conversion process of the reformed gas shows that the reformed gas from the second waste heat boiler contains about 12-14% CO, enters the high-conversion furnace (104-DA), and converts part of the CO into CO2 under the action of the high-conversion catalyst. After high-temperature conversion, the CO The content is reduced to about 3%, and then part of the heat energy is recovered through the third waste heat boiler (103-C), and then enters the low-change furnace (104-DB) through the heat exchanger (104-C, 148-C). Under the action of the low-change catalyst, the remaining CO is converted into CO2. The CO content in the process gas leaving the low-change furnace is about 0.3%. 1.1.4.6 Boiler feed water, boiler water and high, medium and low pressure steam system process flow description When the ammonia synthesis device is started, about 50t/h of medium pressure steam of 3.8MPa and 327℃ will be introduced from outside. The desalted water used in the auxiliary boiler and waste heat boiler is introduced from the water truck workshop, and is preheated to about 100°C using a parallel low-variability outlet gas heater (106-C) and a methanation outlet gas heater (134-C). It is divided into two routes, one is sent to the 4# high pot, and the other is adjusted by LCV-23 and enters the deoxidation section of the deaerator (101-U). In the deoxygenation section, low-pressure steam is used to remove dissolved oxygen from the water, and then dimethyl oxime is added to the water storage section to remove residual dissolved oxygen. The final dissolved oxygen content is less than 7PPb. Add ammonia to the deoxygenated water to adjust the pH to 8.5-9.2, and pass it through the boiler feed water pump 104-J/JA/JB The parallel-connected syngas heater (123-C/C1), shift gas heater (148-C), methane gas heater (114-C) and the boiler feed water preheating coil in the low-temperature section of the convection section of the furnace is heated to about 295°C and enters the steam drum (101-F), and the other route passes through 103-B-6 The coil is heated to about 290°C and enters the steam drum (122-F). At the same time, phosphate solution is added to the steam drum. The water at the bottom of the steam drum is partially vaporized by heating in 103-B-5 and then enters the 122-F steam drum. At the same time, add phosphate solution to the 101-F drum. The water at the bottom of the drum is vaporized by 101-CA/CB, 102-C, 103-C/C1, and the auxiliary boiler heating part, and then enters the drum. The saturated steam separated by drum 101-F is superheated in the convection section of the first furnace and sent to 103-JAT. Extract 3.8MPa, 327℃ medium-pressure steam for use by various medium-pressure steam users. When 103-JAT is out of service, the high-pressure steam is decompressed and all enters the medium-pressure steam pipe network. Part of the medium-pressure steam is used for process, part is used for the condensing turbine, and the rest is used for the back-pressure turbine, and low-pressure steam is generated for use by the 111-C, 101-U, and 135-JC steam extractors, and the rest is used for heat tracing. The saturated steam separated by steam drum 122-F is decompressed to 3.8MPa through the outlet regulating valve PCV-04124, enters the convection section of the heating furnace to be overheated, and then passes through TCV-04131 to add or subtract warm water to control the temperature at 327°C and send it to the medium-pressure steam pipe network 1.1.4.7 The process of aMDEA solution decarburization shows that the process gas temperature in the low-variation process is 260°C, the pressure is 2.83 MPa, and the flow rate is 187187.4NM3/h (moisture gas). The process condensate from 106-J is added and then cooled to 130°C by 105-CA/CB. After cooling at 106-C, it enters 102-F for gas-liquid separation. Part of the separated process condensate goes to 106-J as quench water, another part goes to 103-F through LCV-5 at 55°C and 2.55MPa, and the other part is combined with the condensate from 121-F/F1 and goes to the process condensate recovery system (E66401). The 102-F process gas 55℃, 2.62Mpa, 222283NM3/h (dry gas) enters the lower part of the CO2 absorption tower 101-E. In the absorption tower, it flows counter-currently through the packing layer and contacts the lean liquid 40℃, 801.336t/h added to the top of the tower to remove the carbon dioxide contained in the process gas, and then passes through the top washing section to produce CO2. In the absorption tower, the purified gas leaving the absorption tower is on the pipeline, further washed in the ejector with the process condensate sent through 106-J, and enters the purification separator (121-F/F1) for gas-liquid separation, and the liquid is combined with the condensate separated by 102-F. Demethanation process of gas (CO 0.245%V CO2 0.03%V) with a temperature of 44°C and a pressure of 2.61MPa. The rich liquid coming out of the bottom of the CO2 absorption tower is 77℃ 882.28t/h and enters the top flash section of the CO2 stripping tower 102-E through LCV-4A/4B to release part of the CO2. The 76.3°C semi-lean liquid coming out of the bottom of the 102-E flash section passes through the semi-lean liquid pump 123-JA/JB and is heated by 109-CB1/CB2 (shell side) and 109-CA1/CA2 (shell side) to 102.1°C and enters the 102-E stripping section. In the CO2 stripping section, a large amount of water vapor is evaporated by the heat provided by the switching gas boiler 105-CA/CB and the steam boiler 111-C, and the CO2 in the solution is gradually stripped from bottom to top. The gas at the top of 102-E passes through the CO2 stripping tower condenser 110-C1 and C2, and then is separated by the CO2 stripping tower reflux tank 103-F. The separated CO2 gas is CO2 99.681%, H2 0.268%, total sulfur is less than 1.5PPM, 35℃, 0.12MPa, and then sent to the urea device through 150-C. The condensate separated from the bottom is first boosted by the reflux pump 108-J, and part of it goes to the top of the CO2 absorption tower to wash the solution entrained in the purified gas. The washed condensate returns to the top of the CO2 stripping tower and enters the system, and the other part goes to the injector on the purified gas pipeline to be used as wash water. The hot lean liquid 112.8℃ 801.64t/h coming out of the bottom of the CO2 stripping tower is first cooled by the solution heat exchanger 109-CA1/CA2 (tube side), then enters the lean liquid pump to be pressurized by 107-J, then cooled by the solution heat exchanger 109-CB1/CB2 (tube side), and further cooled to about 40℃ by the lean liquid cooler 108-C before entering the CO2 absorption tower. 1.1.4.8 Methanation process description: The feed gas from decarbonization (44°C, 2.76Mpa) is first preheated to 117.49°C by the synthesis gas-decarbonization gas heat exchanger (136-C), and then heated to 316°C by the high-variable gas-decarbonization gas heat exchanger (104-C) and enters the methanation furnace 106-D. The furnace is equipped with 18m3, J-105 type nickel catalyst. The gas enters 106-D from the top. The carbon oxides (CO: 0.56%V, CO2 0.09%V) in the gas react with H2 under the action of nickel catalyst to generate CH4 and H2O. ； The outlet gas temperature of the methanation furnace (106-D) is 363°C. It is sequentially cooled to 90°C by the boiler feed water preheater, the methane gas desalted water preheater (134-C), and then cooled to 90°C by the water cooler (115-C). Finally, the temperature is reduced to 10°C by the ammonia cooler 115-CR. The CO and CO2 content in the methanated gas drops below 10PPM and enters 104-F for gas-liquid separation. 1.1.4.9 Ammonia synthesis process description: The fresh process gas from methanation (40℃, 2.6Mpa, 117700Nm3/h, H2/N2=3:1) enters the low-pressure section of the synthesis gas compressor 103-J, and is compressed to 169.23℃, 6.65Mpa. After exiting the low-pressure section, it first passes through 136-C The methanation feed gas is cooled to 93.3°C, then cooled to 38°C by the water cooler (116-C), and finally cooled to 7°C by the ammonia cooler (129-C). It is then mixed with the recovered hydrogen and enters the intermediate separation tank (105-F) for gas-liquid separation. The hydrogen-nitrogen gas coming out of 105-F enters the high-pressure cylinder of the synthesis compressor. Recycled gas from the synthesis loop (H2: 53.4% ​​(v), N2: 17.8% (v), 44℃, 10.25Mpa, 19913.97Kmal/h) is mixed with the hydrogen and nitrogen compressed by the high-pressure section and enters the compressor cycle section. Syngas (H2) from the circulation section: 57.4% (v), N2: 19.1% (v), 60℃, 11.25Mpa, 24703.4mal/h) enters the water cooler of the synthesis system at 124-C and is cooled to 38℃. After cooling at 124-C, the gas is divided into two streams.: One stream is cooled to -9 by primary and secondary ammonia coolers (117-C and 118-C)℃ ； The other stream enters the parallel exchanger (120-C) to exchange heat with the cold air after ammonia separation, and then the two streams merge into the three-stage ammonia cooler (119-C) to be cooled to -23.3°C and then enter the ammonia separator (106-F) to separate the liquid ammonia. The liquid ammonia is 99.44% (wt), -23.3°C, 11.06Mpa, 37067.48Kg/h Send to frozen intermediate flash tank (107-F). 106-F The gas after ammonia separation enters the parallel heat exchanger (120-C) to recover cold energy, is reheated to 23.2°C and then enters the synthesis gas exchanger (121-C) to be heated to 141°C and then enters the ammonia synthesis tower (105-D). The synthesis tower is equipped with 72.1m3 iron catalyst. Under the action of catalyst, the reaction produces ammonia. Out of the synthesis tower gas H2: (53.4% ​​(v), N2: 17.8% (v), 301.5℃, 10.25Mpa, 20301.64Kmal/h), the boiler feed water preheater (123-C) recovers heat and then drops to 166℃ and then enters the synthesis tower and inlet and outlet heat exchanger (121-C). The preheated syngas entering the tower is lowered to 44℃, and the syngas at 121-C flows out into the synthesis gas compressor (103-J) cycle section, and the above cycle is repeated. The purge gas is extracted (44°C, 10.25Mpa, 387.7Kmol/h) before entering 103-J. It is cooled by the purge gas ammonia cooler (125-C) and condensed ammonia is separated by the purge gas separator (108-F) and sent to the hydrogen recovery device. The liquid ammonia separated from 108-F is sent to the intermediate flash tank of the refrigeration unit (107-F). 1.1.4.10 Freezing process description: The synthesized liquid ammonia enters the intermediate flash tank (107-F) and the non-condensable gas flashed out is used as fuel gas. The pressure is controlled by PICA-8 to 1.68Mpa and sent to a furnace for combustion. A part of the liquid ammonia (37.8t/h, –23°C) is decompressed and sent to the third-level flash tank (112-F). A part is controlled and adjusted by MIC-24 and enters the second-level flash tank (111-F) for further flash evaporation. Then it enters the system as liquid ammonia for freezing. The operating pressures of the frozen first-, second- and third-stage flash tanks are 0.4Mpa, 0.16MPa and 0.0028Mpa respectively. The three flash tanks correspond to the first, second and third-stage ammonia coolers in the synthesis system respectively. They operate on the principle of thermosiphon for freeze-evaporation cycle. Liquid ammonia flows from each flash tank into the corresponding ammonia cooler. After absorbing heat, the liquid ammonia evaporates to form a gas-liquid mixture and returns to each flash tank for gas-liquid separation. The gas ammonia flows into each section of the ammonia compressor (105-J) respectively, and the liquid ammonia flows into each ammonia cooler respectively to complete a cycle. The liquid ammonia from the liquid ammonia receiving tank (109-F) is gradually decompressed and then replenished to each flash tank. The liquid ammonia coming out of the primary flash tank (110-F) is sent to the first ammonia cooler (117-C), and the other part is used as the cold source of the ammonia cooler (126-C) at the outlet of the syngas compressor (103-J) and the flash tank (109-F). The gas ammonia evaporated from 129-C and 126-C enters the secondary flash tanks 111-F and 110-F. The other part of the liquid ammonia is sent to 111-F. The liquid ammonia coming from 111-F is sent to the second ammonia cooler (118-C) and the purge gas ammonia cooler 125-C as the cold source, and the rest is sent to the third-stage flash tank 112-F. In addition to being sent to 119-C, the liquid ammonia at 112-F can also be sent to the liquid ammonia storage tank for storage by the cold ammonia product pump (109-J) as a cold ammonia product through 109-JA/JB. The gas ammonia from the third-stage flash tank (112-F) is 0.0028Mpa, -33℃, 24160Nm3/h and enters the 105-J stage of compression. The outlet of the first stage merges with the gaseous ammonia from 111-F (0.16Mpa, -12℃, 19040Nm3/h) and enters the second stage of compression. ； The gas ammonia at the outlet of the second stage is first cooled by the compressor intercooler (128-C) and then merges with the gas ammonia from 110-F at 0.4Mpa, 4.4℃, 23607Nm3/h to enter the third stage of compression. ； The ammonia gas at the outlet of the third section is 1.55Mpa and 124°C and is cooled to 45°C by the ammonia cooler 127-CA/B/C. The liquid ammonia enters the receiving tank 109-F. The non-condensable gas goes to 126-C. The condensed liquid ammonia flows back to 109-F. The non-condensable gas is used as fuel gas and sent to the first stage furnace for combustion with PIC-7 controlling the pressure at 1.2Mpa. Part of the liquid ammonia in 109-F is decompressed by LCV-15 and sent to the first-level flash tank (110-F). The other part is sent as hot ammonia product to the urea unit (2.5Mpa, 40℃, 37856Kg/h) through hot ammonia pump 1-3p-1/2. 1.1.4.11 Hydrogen recovery process description: The purge gas (10.5Mpa, -22.7℃, Nm3/h) from ammonia synthesis (108-F) is preheated to -19.4℃ by the boiler feed water through the preheater (E-101) and then enters the lower part of the ammonia absorption tower (K-101), along the tray (12 block) contacts the boiler feed water coming down from the top of the tower from bottom to top, the ammonia in it is absorbed, and the gas leaving the tower contains about 100PPm ammonia. The ammonia water (30% (WT)) discharged from the bottom of the ammonia absorption tower is decompressed to 0.21Mpa by LV-1108 and enters the ammonia water exhaust tank V-103, and the analyzed gases such as H2 and N2 are vented. AV-1113 controls the BFW flow rate and controls the ammonia water at 10.9Mpa, 121.1℃, and 1244.9Kg/h to be sent to the urea hydrolysis unit. The boiler feed water from the high-pressure boiler feed water pump (104-J) is first cooled to 32.2°C by the water cooler (E-102), and then further cooled by the bleed gas preheater (E-101) before being sent to the top of the ammonia absorption tower for absorbing ammonia. The process gas (5°C, 3Mpa) at the top of K-101 is used to remove residual ammonia and moisture through the molecular sieve adsorber (V101A/101B). The two molecular sieves have fixed operating times and sequences to ensure that one is working while the other can be activated and regenerated. In addition to the raw material gas used during startup, the regeneration gas source uses fuel gas from the cold box during the production process. The fuel gas is 21°C. It is first heated to 301.7°C at 143-C and then enters the molecular sieve bed. The regenerated exhaust gas (221.1°C) from the molecular sieve adsorber is cooled to 43.3°C by the water cooler (E-103) and enters the separation tank (V-102). The separated gas is mixed with the remaining fuel gas and passes through the fuel gas pressure control valve PV-1313. Send out of the boundary area, and the discharged ammonia is sent to the ammonia exhaust tank (V-103). The raw gas (20°C, 7.58Mpa) leaving the molecular sieve adsorber enters the cold box and is pre-cooled by liquid ammonia from the cold ammonia pump (109-J) (-33.3°C, 0.37Mpa) in the heat exchanger (E-201B) to the third-stage flash tank (112-F) frozen in the form of gas ammonia. The precooled feed gas is cooled to -185°C in counter-current flow with the hydrogen and fuel gas in the return product in the heat exchanger (E-201A), and is partially condensed. The gas-liquid mixture produced by partial condensation is separated in the raw gas separator (V-201). The hydrogen content of the gas phase product is 90%, and the rest is N2, Ar, CH4 and other liquid phases as fuel gas products. The main components are CH4, Ar, and N2. The main part of the product hydrogen is reheated to 12.7°C by the main heat exchanger (E-201A) and leaves the cold box. After being regulated by the pressure control valve PV-1317, it is sent to the high-pressure cylinder inlet separation tank (105-F) of the syngas compressor (103-J). A small part of the product hydrogen is injected into the liquid of the outlet liquid level regulating valve LCV-1309 through the air injection valve FV-1311. Injecting a certain amount of hydrogen is to ensure sufficient material flow throttling to increase the Joule-Thomson effect. The whole process consists of two stages. In the first stage, LCV-1309 controls the pressure from 7.2Mpa to 2.9Mpa. ； In the second stage, the PCV-1321 control pressure dropped to 0.49Mpa. The liquid (approximately -187°C) leaving the separator (V-201) is all vaporized in the heat exchanger (E-201A), provides cold energy to the raw material stream and is reheated to 21°C and leaves the cold box as fuel gas, part of which is used as a regeneration gas source for the molecular sieve adsorber. 1.1.4.12 Process condensate stripping process description: A part of the process condensate from the shift separator (102-F) is pressurized to 4.12MPa by the process condensate pump (J66401), heated to 212.4°C by the liquid-to-liquid heat exchanger (C66401), and then sent to the medium pressure stripping tower (E66401) for stripping. To remove impurities such as CO2, CH3OH and NH3 in the condensate. The condensate leaving the stripping tower at 247°C is cooled to about 45°C by the liquid-to-liquid heat exchanger (C66401, C66401A) and water cooler (C66402) and sent to the desalted water station for treatment and then used as boiler feed water. Stripping steam is medium-pressure steam from the medium-pressure steam pipe network. The steam (3.88Mpa, 247℃) after leaving the stripping tower is added to the raw gas of the first-stage reformer as part of the process steam.

Hello! I have been paying attention to you for a while and would like to help you solve the problem, but your classification is not very good, and my time does not allow it. There is no one who is willing, has the time and has the ability to answer your question. ； Let me answer your question first. If it works, let’s discuss it further.: 1. Low inlet temperature of 101-B, insufficient combustion air, high synthesis circuit pressure, large purge gas volume, etc. are a problem because the conversion rate cannot meet the requirements, but the solution is not the same. As long as the methane content at the outlet of 103-D reaches the standard, it will be fine. Improving the capacity of the induced draft fan and increasing the temperature of combustion air and fuel gas are the least investment and best ways ； 2.104-D2 Cl poisoning, you didn’t explain where the Cl comes from. I think it’s because the judgment is inaccurate. There is no Cl root in the front. ； Maybe it’s because of the mismatch that Gao Bian didn’t meet the requirements? 3. The decarburization fluctuates greatly and the circulation volume cannot be reached. It is considered that the pressure of the foaming and regeneration towers is unstable. Careful analysis can solve the problem. ； 4.106-D is in its late stages, it shouldn’t be! Don't state a conclusion unless you've already judged it to be correct. The methanation catalyst has been used for 6 years without any problem. The high temperature is caused by the high CO2 at the low-temperature variable outlet and the high CO2 at the decarbonization outlet. It is normal. If it is not high, it is not normal. Solve these two problems and there will be no problem. ； 5. The problem that the refrigerant level is not well balanced is because the pressure during start and stop is unstable. A certain pressure corresponds to a certain condensation temperature. It is a phase balance problem. It is normal. It will be fine if you have experience. ； 6. Bubble steam production, boiler feed water pump, deaerator O2, and 123-C are problems of the boiler system, but steam production is a common problem between the conversion heat load and 123-C and 103-C. ； 123-C internal leakage is a big problem. It not only affects steam production, but also corrodes the steam turbine, high-pressure steam system, and steam condensate system. The cost is too high. Solve it as soon as possible, otherwise you will leave a lot of sequelae in the future. ； The high oxygen content of the deaerator will cause corrosion in the boiler water system, so resolve it as soon as possible. It’s okay not to open it, otherwise the price will be too high: Equipment safety and personal safety caused by major accidents. Let’s talk more: If you make a good argument, it can be solved with the least investment. I have considered a solution, but due to the incomplete time and on-site situation, let’s not talk about it for now. You are capable of solving the problem. The problem is that there is no good use of people who understand technology. Nowadays, leaders just do what they think of. Leaders understand but they don’t have time and energy. Design institutes are not destined to share the same fate as themselves. They only make money and don’t consider everything comprehensively, right? !

I heard that 103JT/J and 105J/JT did not meet the design standards after modification. Can you tell us about them?

It's better now, but after this minor repair, a new problem appeared in 103-J, that is, the speed cannot be increased. In the past, 103-J was a problem with the turbine rotor, and it could only rotate for about a month, which was a lot of trouble for us. 8#lth

The technological transformation part of Yutianhua's natural gas steam reforming is to add a first-stage heat exchange reformer, add a second-stage furnace, build a new carbon dioxide recovery unit, increase raw materials, and increase the conversion rate, thus doubling production capacity. The modification was relatively successful, with the capacity of 60,000 tons reaching 160,000 tons. It seems that the core of your transformation is to improve the reaction conditions of the first stage of the furnace, increase its reaction capacity by increasing the pipe diameter and raising the preheating temperature, and other equipment and devices are designed around this core. However, many indicators deviate greatly from the design values ​​and deserve careful analysis. I suggest that the poster send me two installation process drawings and equipment introductions before and after the transformation, so that I can analyze them carefully and learn together. * progress. mail: JIANGUO1116@YAHOO.COM.CN ,TEL: 13669140668 address: Shaanxi Province Yulin Natural Gas Chemical Co., Ltd.

Can you upload some flow charts or photos? :o

1. The outlet temperature of the newly added heating furnace cannot reach the design value of 650°C, resulting in a low temperature of the process gas at the entrance of the furnace and an increase in the load of the furnace. "After coming out of the pre-reformer (109-D), the temperature dropped by 47°C. It is OK. The pre-reformer is working properly. 2. The heat load of the first-stage furnace is too large, the oxygen content is insufficient, the flue gas temperature is overheated, and the system methane content is higher than the design index. the heat exchangers are not working properly. Maybe it is HEs design problem.

Our mixed gas preheating box furnace is 410 degrees, the heat exchange furnace is 460 degrees, and the outlet is between 700-710 degrees. The load of a single pipe is 60 cubic meters, and the methane content at the outlet is between 6% and 7%. ； Ningxia Erhua, where Huang Xinhui works, has a high mixed gas preheating temperature and a pre-conversion reactor with a single tube load of more than 110 cubic meters. The production intensity is indeed very high and is worth learning from.

Please ask the host: Is the transformation axis-radial?

This post was last posted by * aoye613 edited on 2009-6-3 22:47 The transformation of Ningxia Erhua is mainly reflected in the front half of the preheating part. The rear system mainly produces steam, and the heat utilization of the system is not reasonable enough. If the waste heat of the rear system can be used to heat the front system, a large part of the fuel gas can be saved. If the steam is insufficient, the boiler can be relied on. The heat of the rear system is very abundant. The waste heat of the rear system can be used to increase conversion capacity and reduce fuel gas consumption, which can be used as the starting point for the next technical transformation.

Lowering the outlet temperature of the flue gas to 120 degrees and using the recovered heat for the air preheater or raw material preheater can solve the problem of low furnace temperature and reduce many subsequent problems (such as high methane). The newly built devices in recent years all use plate air preheaters. The outlet flue gas temperature is 120-150 degrees, and the preheated air temperature is 450-550 degrees. It is of great benefit to increase the furnace temperature and save fuel. http://bbs.hcbbs.com/viewthread.php?tid=344019&highlight=%B0%E5%CA%BD%BF%D5%C6%F8%D4%A4%C8%C8%C6%F7

Which manufacturers are using plate air preheaters? Please provide a brief introduction.

It also needs to be combined with the current application situation. I don’t know which domestic household used it earliest, which manufacturer, application situation, advantages and disadvantages.

The earliest one in China is used by Shanghai Gaoqiao Petrochemical. It has been nearly 30 years old and is one of the only heat exchangers still in normal use at Gaoqiao Petrochemical. Dutch equipment in the petrochemical industry is a consistent guarantee of high technology and high quality.

I would like to ask the original poster, which design institute did you use to design the capacity expansion technology of your installation? As far as I know, domestic factories such as Lutianhua, Yuntianhua, and Daqing all ask KBR to make the process package, and domestic engineering companies to do the basic design. If the technology is not in place, the transformation will go a long way. The transformation of Lutianhua, Yuntianhua and Daqing was relatively successful. We can communicate with them and learn from their experiences and lessons. At the same time, I would also like to visit your factory for study. * , I wonder if there is any chance?

We were made by Wuhuan. You are right. The choice of transformation craft package is indeed very important. Welcome!