Method for steam generation at production of ammonia

FIELD: heat power and chemical industries, applicable in production of ammonia.

SUBSTANCE: in the method for steam generation at production of ammonia from hydrocarbon gases the mean-pressure steam used for the process of steam reforming and/or for the compressor drives is subjected to humidification by injection of the process condensate or feed water, and the obtained humidified steam is overheated by the heat of the flue gas in a unit of the heat-using equipment of the reforming tube furnace.

EFFECT: reduced consumption of energy due to reduction of the amount of generated steam and reduced of the amount of generated steam and reduced consumption of feed water; provided additional cleaning of the process condensate and recovering of gases dissolved in it in the process of steam humidification in the mass transfer device.

2 cl, 1 dwg

 

The invention relates to the field of industrial heat and power engineering and chemical industry and can be used in the production of ammonia.

There is a method of generating steam in a combined thermal unit (see EN 2028465 C1, class F 01 K 13/00, 09.02.1995), which includes a combustion chamber and fuel preparation, combustion node blocks the recycling of flue gas, refrigeration, blocks processing of oxides of nitrogen, sulfur and carbon, purge and distillation columns, gas turbine, the compressor and the collection of acidic condensate.

The disadvantage of this method is of limited use.

There is a method of generating steam in the production of ammonia from natural gas, including: the desulfurization of hydrocarbon gases, catalytic steam reforming in a tubular furnace at a pressure of 2.9 to 3.8 MPa, the compression ratio of the air-driven motor, a steam catalytic conversion in the shaft reactor, two-stage catalytic conversion of carbon monoxide, the use of heat converted gas mixture with receipt and removal of the condensed process condensate cleaning gas from carbon dioxide, booster compression produced synthesis gas with electric drive, the synthesis of ammonia in the circulation circuit with circulating on what netteler and system for generating superheated water vapor pressure of 3.8 to 4.2 MPa in waste heat boilers through the use of warmth technological processes, heat the flue gases of the reformer furnace in the unit combustion apparatus (BTA) tubular furnace with the waste flue gas at a temperature of not lower than 220°; part of the resulting water vapor is used for the process of steam reforming and other production needs, the other part of the pair is given on the side. (See The project's ammonia production capacity of 600 tons/day, second of all, the object 19418-for Rivne REASON, the Company p/I-7531, , Severodonetsk, 1968, S. 138 - schema steam and condensate).

The known method has the following major drawbacks:

- receive pairs is not a high energy potential to drive the main compressor machines;

a significant part of the received pair is displayed on the side;

all major drives compressors and pumps electric, which significantly increases the consumption of electrical energy.

Closest to the proposed invention is a method of generating steam in the production of ammonia from hydrocarbon gases by desulfurization of hydrocarbon gases, obtain a gas mixture, carrying out catalytic reforming gas mixture in a tubular furnace at a pressure of 2.9 to 3.8 MPa, compressed air, steam-air catalytic conversion in the shaft reactor, two-stage catalic the risk of carbon monoxide conversion, use of heat converted gas mixture with receipt and removal of the condensed process condensate, gas purification from carbon dioxide booster compression of the produced synthesis gas, the synthesis of ammonia in the circulation circuit with circulation pump, water-ammonia refrigeration installation and system generation of superheated vapour high pressure of 9.7 to 10.6 MPa) in waste heat boilers by using the heat of the technological processes of heat of flue gases of the reformer furnace in the unit combustion apparatus (BTA) tubular furnace, in the auxiliary boiler, ensure the maintenance of the balance of steam, and starting the boiler, generating superheated steam medium pressure (3,8-4,2 MPa) and providing start-up and transient operation modes, using the generated water vapor high pressure first stage turbine syngas compressor, working with backpressure and outstanding superheated steam medium pressure (3,8-4,2 MPa), and then use part of this pair in the second condensation stage turbine syngas compressor and drive turbines other compressors, exhausters and pumps, as in condensing turbines, and turbines operating with a pressure of 0.4-0.8 MPa, and another part of the steam medium pressure for technological processprotocol reforming. (see Technical project ammonia production AM-70 capacity of 1360 tons/day for Kirovo-Chepetsk chemical works, project No. 25040, GIAP, Moscow, 1974, s, 117, 118).

The known method has the disadvantage that limits the amount of steam total thermal load of the system steam generation, as well as poor utilization of flue gas heat recovery tube furnace, which reduces energy efficiency and increase the overall energy consumption.

The technical result, which is aimed invention is to optimize the production and distribution of steam and reducing power consumption.

The technical result is achieved in that in the method of generating steam in the production of ammonia from hydrocarbon gases by desulfurization of hydrocarbon gases, obtain a gas mixture, carrying out catalytic reforming gas mixture in a tubular furnace at a pressure of 2.9 to 3.8 MPa, compressed air, steam-air catalytic conversion in the shaft reactor, two-stage catalytic conversion of carbon monoxide, heat of the converted gas mixture with receipt and removal of the condensed process condensate, gas purification from carbon dioxide booster compression obtained xing the ez-gas, synthesis of ammonia in the circulation circuit with circulation pump, water-ammonia refrigeration installation and system generation of superheated vapour high pressure of 9.7 to 10.6 MPa) in waste heat boilers by using the heat of the technological processes of heat of flue gases of the reformer furnace in the unit combustion equipment tubular furnace, in the auxiliary boiler, ensure the maintenance of the balance of steam, and starting the boiler, generating superheated steam medium pressure (3,8-4,2 MPa) and providing start-up and transient operation modes, using the generated water vapor high pressure first stage turbine syngas compressor, working with backpressure and outstanding superheated steam medium pressure (3,8-4,2 MPa), and then use part of this pair in the second condensation stage turbine syngas compressor and drive turbines other compressors, exhausters and pumps, as in condensing turbines, and turbines operating with a pressure of 0.4-0.8 MPa, and another part of the steam medium pressure for the process of steam reforming, steam medium-pressure or steam-gas mixture used for the process, before applying for catalytic reforming is subjected to moisture by contact with the process to which the completion or feed water and overheat the heat of the flue gas in the combustion unit of the apparatus, the tube furnace reformer.

The technical result is also achieved by the fact that the contacting steam or steam-gas mixture with process condensate is carried out in the mass transfer device, providing an additional cleaning process condensate disposal of gases and reducing the corrosiveness of process condensate.

The drawing shows a schematic diagram of a device for implementing the method.

The device for implementing the method includes: the desulfurization of hydrocarbon gases 1, catalytic steam reforming of 2 with the auxiliary boiler and system of generating superheated steam 3, block combustion apparatus (BTA) tubular furnace 4, a steam catalytic conversion of 5 with heat recovery boilers 6, two-stage catalytic conversion of carbon monoxide 7, the use of heat converted gas mixture 8, the cleaning gas from the carbon dioxide 9, booster compression of the synthesis gas 10, the ammonia synthesis 11 circulating blower 12, starting the boiler 13, two-stage steam turbine booster compressor syngas: the first stage 14 working with backpressure and outstanding superheated steam medium pressure (3,8-4,2 MPa), the second condensation stage 15 running on superheated steam medium pressure, the node contact (wetting) of superheated steam medium having the program and vapor-gas mixture with process condensate 16, steam turbine other compressors, exhausters, pumps, condensing 17, 18 and working pressure of 0.4-0.8 MPa 19, 20, consumers of low-pressure steam (0,4-0,8 MPa) 21.

The source of hydrocarbon gas in line 22 is fed to the desulfurization and moves sequentially through all stages of production to ammonia synthesis. Received high-pressure superheated steam line 23 passes first stage of the turbine 14 working with backpressure and outstanding superheated steam medium pressure. After the turbine 14 superheated steam medium pressure is distributed: line 26 in the condensation stage turbine syngas compressor 15 through the manifold 24 to the drive steam turbines other compressors, exhausters and pumps 17, 18, 19 and 20, line 25 superheated steam medium pressure used for the process is supplied to the node contact 16, where the mass transfer device he moistened process condensate supplied through the line 32 from the host using the heat of the reformed gas 8. Another possible implementation of the method can be a supply of water from the installation preparation of feed water in line 33 instead of the process condensate, or in addition to it.

By contact with superheated steam generation is provided an additional quantity of steam to the cleaning process condensate from the gases, their utilization and reduce corrosion. Further humidified vapor line 30 is mixed with sweet petroleum gas supply line 27, 28, and the resulting gas-vapor mixture is fed to overheating in BTA tubular furnace 4 and line 31 to catalytic reforming 2.

Another possible variant of the method presented in figure 1, is that the original hydrocarbon gas after desulfurization, the whole or at least part of it, along the line 29 is mixed with superheated steam medium pressure. The obtained gas-vapor mixture enters the node contact 16, where the mass transfer device moistened process condensate supplied through the line 32, and/or feed water line 33 with the generation of additional quantities of steam cleaning process condensate and recycling gases. The humidified gas-vapor mixture in line 30 is supplied to overheating in BTA tubular furnace 4 and further along the line 31 to catalytic reforming.

Low pressure steam from the turbines 19, 20, working with pressure, is collected in the reservoir 27, which is served to consumers 9, 21.

Example.

In accordance with the invention presents a method of ammonia production with a capacity of 1,360 tons/day of natural gas from the steam reformer at a pressure of 3.6 MPa and system of generating superheated steam in the high pressure 10 MPa, temperature 482°With the number of 319 tons/hour. After the first stage of the turbine compressor syngas part of the superheated steam medium pressure 90 t/h at a pressure of 4 MPa and a temperature of 380°contact with process condensate. Due to the evaporation process condensate quantity of wet steam after humidification is increased to 12 t/h, and the total number of generated vapor is increased from 319 to 335 tons/hour. Natural gas after mixing or saturation vapor in contact with process condensate, resulting in the amount of steam it increases to 4 t/h. Next, the resulting gas-vapor mixture dispense the necessary amount of steam for the process of steam reforming and sent to BTA tubular furnace to overheat the heat of the flue gas, resulting in the temperature of the flue gas will be reduced from 220°175°s, which provides savings of 7.2 Gcal/h of heat or 900 m3per hour of natural gas. In addition, part of the feed water going to the evaporation process is replaced by condensate in the amount of 16 t/h, which further reduces the cost of production.

1. The method of generating steam in the production of ammonia from hydrocarbon gases by desulfurization of hydrocarbon gases, obtain a gas mixture, carrying out catalytic is forming vapor-gas mixture in a tubular furnace at a pressure of 2.9 to 3.8 MPa, compressed air, steam-air catalytic conversion in the shaft reactor, two-stage catalytic conversion of carbon monoxide, heat of the converted gas mixture with receipt and removal of the condensed process condensate, gas purification from carbon dioxide booster compression of the produced synthesis gas, the synthesis of ammonia in the circulation circuit with circulation pump, water-ammonia refrigeration installation and system generation of superheated vapour high pressure of 9.7 to 10.6 MPa) in waste heat boilers by using the heat of the technological processes of heat of flue gases of the reformer furnace in the unit combustion equipment tubular furnace, in the auxiliary boiler, ensure the maintenance of the balance of steam, and starting the boiler, generating superheated steam medium pressure (3,8-4,2 MPa) and providing start-up and transient operation modes, using the generated water vapor high pressure first stage turbine syngas compressor, working with backpressure and outstanding superheated steam medium pressure (3,8-4,2 MPa), and then use part of this pair in the second condensation stage turbine syngas compressor and drive turbines other compressors, exhausters and pumps, as in the condensation is Urbino, and in turbines operating with a pressure of 0.4-0.8 MPa, and another part of the steam medium pressure for the process of steam reforming, characterized in that the steam medium pressure and/or vapor-gas mixture used for the process, before applying for catalytic reforming is subjected to moisture by contact with process condensate or feed water and overheat the heat of the flue gas in the combustion unit of the apparatus, the tube furnace reformer.

2. The method according to claim 1, characterized in that the moisture vapor or vapor-gas mixture, the process condensate is carried out in the mass transfer device, providing an additional cleaning process condensate disposal of gases and reducing the corrosiveness of process condensate.



 

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