Method for the production of ammonia

 

(57) Abstract:

Sobranie relates to the production of ammonia from gaseous and liquid hydrocarbons and can be used in the chemical and petrochemical industries. Method for the production of ammonia includes a two-stage catalytic conversion of hydrocarbons under pressure with steam and air compressed by a compressor driven by a gas turbine, the conversion of carbon monoxide with obtaining nitric mixture, purification from carbon oxides, the selection of the purified gas mixture of hydrogen, a mixture of the latter with a gas stream enriched in nitrogen to the stoichiometric ratio of hydrogen to nitrogen is 3 : 1, flow derived nitric mixture for the synthesis of ammonia, in order to reduce energy consumption before the release of hydrogen gas mixture is divided into flows in a volume ratio(0,42 - 0,63) : (0,58 - 0,37), however, the selection of hydrogen lead from the second stream and separate the hydrogen is mixed with the first stream with obtaining nitric mixture of stoichiometric composition, and the remaining after the separation of the hydrogen fraction is served on a turbine with a pressure equal to 95 - 98% of the partial pressure of the mixture. The cost of the low-potential is(0,67 - 0,425) Gcal/t NH3. 1 Il., table 4.

The invention relates to the production of ammonia from gaseous and liquid hydrocarbons and can be used in the chemical and petrochemical industries.

The aim of the invention is the reduction of energy consumption.

To achieve this goal in the method of producing ammonia, comprising a two-stage catalytic conversion of hydrocarbons under pressure with steam and air compressed by a compressor driven by a gas turbine, the conversion of carbon monoxide with obtaining a mixture of nitric, cleaned from oxides of carbon, separation of the purified gas mixture of hydrogen, a mixture of the latter with a gas stream enriched in nitrogen, up to the stoichiometric ratio of hydrogen to nitrogen is 3:1, flow derived nitric mixture for the synthesis of ammonia, according to the present invention, before the release of hydrogen gas mixture is divided into flows in a volume ratio(0,42-0,63):(0,58-0,37), however, the selection of hydrogen lead from the second stream and separate the hydrogen is mixed with the first stream with obtaining nitric mixture of stoichiometric composition, and the remaining after the separation of the hydrogen fraction is served on Turbin to reduce energy consumption.

This is due to the following:

1. Replacing the separation process converted and purge gases to the process of separation of the hydrogen gas in the presence of intermetallic compounds or by passing them through a diffusion membrane, while maintaining the pressure of the liberated hydrogen and waste fractions.

2. Separation of nitric mixture after stage mahanirvana into two streams, one of which komprimiert to pressure synthesis, and from the second emit hydrogen, mix it before komprimirovannom with the first stream and the waste fraction under pressure is directed to the combustion gazoturbogeneratorov unit.

3. The bonding emitted from the converted and the purge gas intermetallic compounds of hydrogen until the pressure synthesis.

In the drawing given technological scheme of the proposed method of production of ammonia and hydrogen. It includes mixer hydrocarbons with water vapor 1, the heat exchanger 2, the Converter tubular primary reformer 3, mine deconverter secondary reformer 4, the apparatus teplooborudovanie 5, CO conversion stage 6, stage washing from CO27, the stage of mahanirvana 8, the intermetallic compression ammonia synthesis 12, hedebrant 13, the circulation compressor 14, a separator 15, the separator of hydrogen from the purge gas ammonia synthesis 16, the process air compressor 17, the air compressor to the combustion 18, the combustion chamber gazoturbogeneratorov unit 19, the gas turbine 20, the unit teplooborudovanie for gas turbine 21.

Compressed hydrocarbon raw materials in the mixer 1 is mixed with steam and after heating in the heat exchanger 2 by the heat converted gas after the secondary reformer is served in a tubular Converter 3, where in the reaction tubes at the Nickel catalyst through indirect heat exchange with the converted gas stream after the air shaft reforming is the process of steam reforming at 621-749aboutTo the residual methane 25-44% about. The converted gas after the Converter 3 is fed in mine deconverter 4. This also serves heated to 700-900aboutWith process air. In mine deconverter 4 the process air dikonversi hydrocarbons at 1100aboutRatio (H2+CO)/N21,37-2,0. The converted gas is sent to the Converter tube 3, which gives off heat to cover the endothermic effect of the steam reforming process.

aboutWith converted gas sequentially passes through the stages of conversion of carbon monoxide 6, shaded from carbon dioxide 7 and stage mahanirvana residues co and CO28. All of these stages is rational utilization of secondary heat resources in the process of exothermic reactions to produce process energy and steam. Cleaned from oxide and dioxide nitric mixture with a ratio of N2/N2= 1,33-1,91 divided into two streams in relation to(0,42-0,63):(0,68-0,37). The first stream is sent to the Department of synthesis and of the second flow produce hydrogen in the hydrogen separator 9 under the pressure of one of the known methods and mix it with the first stream in the mixer 10, with the formation of nitric mixture with a ratio of N2/N2=2,9-3,0 and remaining after the separation of the hydrogen-enriched nitrogen fraction under pressure is directed to the combustion in the chamber of the gas turbine 19.

Nitric mixture komprimiert in the compressor 11 to the pressure of the synthesis, mixed with the circulating gas and sent to the ammonia synthesis column of 12.

The mixture is proektnym turn holocoenic 13, is divided into two streams. One of the threads is sent to the circulating gas compressor 14, and the second purge gases ammonia synthesis) - separator of hydrogen from the purge gas ammonia synthesis 16.

Purge gases after separation of the hydrogen gas containing methane, hydrogen, argon and nitrogen, under pressure mixed with a second stream enriched in nitrogen fractions after hydrogen separator 9 and is directed to the combustion in the combustion chamber 19 of the gas turbine unit 20. This also serves compressed in the compressor 18 for combustion air. Gas turbine unit is used to drive the compressor fuel air 18 and the process air compressor 17, after which the process air is heated to 700-900aboutWith the unit teplooborudovanie 21 and is directed to the process of mine dikonversi the Converter 4.

P R I m e R 1. Hydrocarbons in the number 54405,6 m3/h with the composition, vol.%: CO2- 0,03; N2- 4,2; N2- 6,98; Ar - 0,03; CH4- 82,2; C2H6- 4,47; C3H8- 1,36; C4H10- 0,49; C5H12- 0,24 komprimiert to 4.3 MPa, is mixed with steam in the mixer 1, is heated in heat exchanger 2 to 450aboutWith and served in a tubular reactor 3, where the reactions the e secondary shaft reforming is the process of steam reforming at 721aboutWith up to a content of residual methane in the mixture 28,08%. In mine Converter 4 receives the converted gas after the primary reformer and 107870 m3/h of air, heated to 800aboutC. Process air reforming of hydrocarbons occurs at 1010aboutWith the pressure of 3.69 MPa and the ratio (H2+CO)/N2=1,84.377606 m3/h converted gas having a composition, vol.% : CO2- 4,53; CO - 9,41; N2- 33,60; N2- 23,31; Ar - 0,28; CH4- 0.24, N2On - 28,63, out of the annulus of the tubular reactor at 580aboutWith the heating source progresterone mixture in the heat exchanger 2.

Next, the converted gas is sequentially sent to the stage of conversion of carbon monoxide, flashing of carbon dioxide and stage mahanirvana from the remnants of co and CO2.< / BR>
After the stage of mahanirvana drained nitric mixture of the following composition, about. %: H2- 62,95; N2- 35,59; Ar - 0,42; CH4- 1,04 when the pressure 2,99 MPa, a temperature of 40aboutWith divided into two streams. The first thread in the amount of 125483 m3/h to send kompremirovannyj, and from the second stream, which is 92401 m3/h, allocate 49441 m3/h of hydrogen, mix it with the first stream, naprawcze after the separation of the hydrogen-enriched nitrogen fraction, under pressure, equal 2,8 (95%) - 2,87 (98%) MPa, is directed to the combustion in the combustion chamber of the gas turbine unit.

P R I m e R s 1-5 are shown in table. The table shows that in the proposed method in contrast to the known costs of low-grade heat to the hydrogen gas is reduced by dividing the flow of nitric mixture after stage mahanirvana against(0,42-0,63)/(0,58-0,37).

The total energy savings in the proposed method, including the energy consumption for kompremirovannyj, heated process air and energy on the production of hydrogen, as compared with the method of the prototype is 0,473-0,688 Gcal/NH3.

Limits to reduce power consumption caused by the temperature of the reformed gas at the outlet of the annulus of the tubular Converter. Temperature below 540aboutWith causes irrational change of the constructive and technological parameters (increase in the length of the reaction tubes and the height of the apparatus, increasing the resistance of the pressure drop, which will lead to an increase in the intensity), and at a temperature of 800aboutWith a two-step conversion of methane is practically replaced by a single-stage shaft conversion.

WAY Prom with water vapor and air, compressed by a compressor driven by a gas turbine, the conversion of carbon monoxide with obtaining nitric mixture, purification from carbon oxides, the selection of the purified gas mixture of hydrogen, a mixture of the latter with a gas stream enriched in nitrogen to the stoichiometric ratio of hydrogen to nitrogen is 3 :1, flow derived nitric mixture for the synthesis of ammonia, characterized in that, to reduce energy consumption, before the release of hydrogen gas mixture is divided into flows in a volume ratio(0,42 - 0,63) : (0,58 - 0,37), however, the selection of hydrogen lead from the second stream and separate the hydrogen is mixed with the first stream with obtaining nitric mixture of stoichiometric composition, and the remaining after the separation of the hydrogen fraction is served on a turbine with a pressure equal to 95 - 98% of the partial pressure of the mixture.

 

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