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, saturation of the hydrocarbon gas after desulfurization and/or process air fed to the secondary reforming is effected due to the use of the flue gas of a tube furnace at a temperature of 160 to 580C, preferably within 220 to 480C, by means of water recirculation.

EFFECT: reduced consumption of energy due to reduction of the total amount of generated steam, reduced consumption of feed water, and recovered gases dissolved in the process condensate.

4 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 hydrocarbon gases, including the preparation of hydrocarbon gases, saturated hydrocarbon gases water vapor in the saturator with recirculation of water between the saturator and heat exchanger to heat the circulating water by the heat of the converted gas mixture at a temperature of 180-200°C, catalytic conversion of hydrocarbon gases in the shaft reactor at low pressure and temperature 850-930°C, catalytic conversion of carbon monoxide, gas cleaning, compression, synthesis gas and the synthesis of ammonia. In this way in the saturator is provided a hydrocarbon gas saturation water vapor to the relationship vapor/gas of 0.3-0.45. (see Andreev F.A., Kargin SR and other Technology bound nitrogen, Moscow: Chemistry, 1966, S. 34 FF.).

The disadvantage of this method is insufficient securityimage pair and limited use.

Closest to the proposed invention is a method of generating steam in the production of ammonia from sweet hydrocarbon gases, carried out by two-stage catalytic reforming at a pressure up to 4.0 MPa first with steam in a tubular furnace using heat of the exhaust flue gas tube furnace for heating process streams entering the reformer, and then steam-air mixture in the shaft reactor, catalytic conversion of carbon monoxide, heat of the converted gas mixture with receipt and removal of the condensed process condensate, including saturation of the air supplied to the vapor reforming and/or hydrocarbon gas supplied to the steam reforming unit, and generating superheated a pair of feed water to drive machinery and for technological purposes (see Handbook for apothica. M.: Chemistry, 1986, s.112-121, 83-85).

The known method has the disadvantage that characterized the lack of use of the heat of the flue gases in the heat block is ispolzuya equipment, due to an inefficient temperature heat source gas flue gas with high temperature and deficiency heat environments in the unit combustion equipment tubular furnace, which increases the total heat loss from the exhaust flue gases and, as a consequence, the over-expenditure of fuel gas.

The technical result, which is aimed invention is to reduce the consumption of fuel gas with a simultaneous increase in the heat load of node saturation and volume securityimage pair, reducing corrosion and improving the safety of production.

The technical result is achieved in that in the method of generating steam in the production of ammonia from sweet hydrocarbon gases, carried out by two-stage catalytic reforming at a pressure up to 4.0 MPa first with steam in a tubular furnace using heat of the exhaust flue gas tube furnace for heating process streams entering the reformer, and then steam-air mixture in the shaft reactor, catalytic conversion of carbon monoxide, heat of the converted gas mixture with receipt and removal of the condensed process condensate, including saturation of the air supplied to the vapor reforming and/or coal is dorodnova gas, supplied to the steam reforming unit, and generating superheated steam from the feed water to drive machinery and for technological purposes, saturation of air, supplied to a steam-reforming and/or hydrocarbon gas supplied to the steam reforming carried out by using the heat of the flue gas tube furnace at a temperature of 160-850C, preferably 220-480°C.

The technical result is also achieved by the fact that the transfer of heat from the flue gas and the saturation process carried out by circulating water or by manual injection of hot water, and recharge cycle saturation perform the heated process condensate, and for heating the process condensate use warmth converted gas after the carbon monoxide conversion or the heat of the exhaust flue gas tube furnace.

The technical result is also achieved by the fact that the superheated steam used to process the primary and/or secondary reforming, moisturize process condensate supplied to recharge cycle saturation, mass-exchange contact device type.

The technical result is also achieved by the fact that the steam-air mixture and/or gas-vapor mixture after saturation and/or moist steam medium pressure is I in a mixture or separately, before serving on the reformer is heated first step in the heat exchanger by the heat of the hydrocarbon gas after desulfurization, then the heat of the exhaust flue gas furnace in one or more steps.

The drawing shows an example schematic diagram of an apparatus 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 3 and the unit combustion apparatus (BTA) 4, vapor catalytic reforming 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, deep purification of synthesis gas 10, booster compression of the synthesis gas 11, the ammonia synthesis 12, two degrees of saturation of the hydrocarbon gas 13, 14, the heat exchanger 15, the air compressor 16 and two degrees of saturation of the air 17, 18.

The source of hydrocarbon gas in line 19 is fed to the desulfurization and then line 20 through the heat exchanger is fed to saturation. After saturation saturated water vapor gas-vapor mixture in line 21 through the heat exchanger 15 is fed to heat recovery furnace and then through line 22 is fed to the steam reformer and consistently passes all technologist the economic stage of production to the synthesis of ammonia.

Process air for the 2nd stage of the reformer 23 is compressed by the compressor 16 and is fed to the saturation line 24. After saturation saturated water vapor of the vapor mixture in line 25 is fed to heat recovery tube furnace and on line 26 enters the 2nd stage of the reformer.

The saturation process is performed by the heat of the flue gas passed through the circulating water through the lines 27 and 28. Recharge cycles saturation is performed by applying a heated process condensate and/or water supply to the second stage saturation 14, 18 on lines 31, 32.

The missing amount of superheated steam for technological process is served on the steam and steam-air mixture along the lines 29 and 30.

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 reformer at a pressure of 3.6 MPa and system of generating superheated steam of a high pressure of 10 MPa, a temperature of 482°With the number of 288 tons/hour.

Hydrocarbon gas in the number 36000 nm3per hour after hemosorption catalytic desulfurization temperature of 370°cooled in the heat exchanger to a temperature of 178°and served on the saturation, where the mass transfer device when flow irrigation circulating hot water us the return water vapor to vapor/gas 1,25. The amount of water vapor in the hydrocarbon gas is 36200 kg/hour, which saves an equivalent amount of superheated steam medium pressure. The obtained gas-vapor mixture at the top of the saturator is in contact with process condensate supplied to recharge cycle saturation, which allows for the Stripping of gases dissolved in the process condensate.

After saturation, the gas-vapor mixture having a temperature of 212°C, is heated in the heat exchanger to 345°With the counter flow of the hydrocarbon gas and sent to the BTA tubular furnace where it is heated to 520°warm flue gas and is then transferred to steam reforming.

By analogy with the described conduct saturation process air. Thus, the amount of water vapor in the air is 7000 kg/h, and the ratio of steam/air is 0.16. After saturation vapor mixture is heated in BTA tubular furnace to a temperature 480°and served on the 2nd stage of the reformer.

Circulating water to conduct saturation in the amount of 230 m3per hour for saturation of the hydrocarbon gas and 50 m3per hour for saturation of the air is heated by indirect heat exchange with flue gas heat recovery tube furnace to a temperature of 245°C. the flue gas Temperature in the heating zone 220-470°C. After saturation temperature of the circulation in the waters around 170° C.

Thus, the saturation of the total amount of water vapor in the gases is 43200 kg/hour, which saves the consumption of an equivalent amount of superheated steam medium-pressure or 4760 m3per hour of natural gas combusted in the system steam generation ammonia production. In addition, the use of the process condensate in cycles of saturation in accordance with the present invention, provides cost savings 43200 kg/HR expensive feed water and blow-off gases dissolved in the process condensate, allows them to recycle, reduce corrosion in cycles of saturation and improve production safety.

1. The method of generating steam in the production of ammonia from sweet hydrocarbon gases, carried out by two-stage catalytic reforming at a pressure up to 4.0 MPa first with steam in a tubular furnace using heat of the exhaust flue gas tube furnace for heating process streams entering the reformer, and then steam-air mixture in the shaft reactor, catalytic conversion of carbon monoxide, heat of the converted gas mixture with receipt and removal of the condensed process condensate, including saturation of the air supplied to the vapor reforming and/or hydrocarbon g is for, supplied to the steam reforming unit, and generating superheated steam from the feed water to drive machinery and for technological purposes, characterized in that the saturation of the air supplied to the vapor reforming and/or hydrocarbon gas supplied to the steam reformer, carried out by using the heat of the flue gas tube furnace at a temperature of 160-850°C, preferably 220-480°C.

2. The method according to claim 1, characterized in that the transfer of heat from the flue gas and the saturation process carried out by circulating water or by manual injection of hot water, and recharge cycle saturation perform the heated process condensate, and for heating the process condensate use warmth converted gas after the carbon monoxide conversion or the heat of the exhaust flue gas tube furnace.

3. The method according to claim 1, characterized in that the superheated steam used to process the primary and/or secondary reforming, moisturize process condensate supplied to recharge cycle saturation, mass-exchange contact device type.

4. The method according to claim 1, characterized in that the steam-air mixture and/or gas-vapor mixture after saturation and/or moist steam medium pressure in a mixture of silt is separately before serving reformer is heated first step in the heat exchanger by the heat of the hydrocarbon gas after desulfurization, then the heat of the exhaust flue gas furnace in one or more steps.



 

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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, saturation of the hydrocarbon gas after desulfurization and/or process air fed to the secondary reforming is effected due to the use of the flue gas of a tube furnace at a temperature of 160 to 580C, preferably within 220 to 480C, by means of water recirculation.

EFFECT: reduced consumption of energy due to reduction of the total amount of generated steam, reduced consumption of feed water, and recovered gases dissolved in the process condensate.

4 cl, 1 dwg

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