The way co-production of ammonia and methanol

 

(57) Abstract:

The invention relates to methods of co-production of ammonia and methanol. The way co-production of ammonia and methanol includes desulfurization, two-step conversion of methane, a high-temperature conversion of carbon monoxide, the cleaning gas from the carbon dioxide absorption hot solution of potash, the synthesis of methanol under a pressure of 5 MPa and synthesis of ammonia under a pressure of 30 MPa, while the cleaning gas from the carbon dioxide lead directly after high-temperature conversion of carbon monoxide to a residual content of carbon dioxide of 0.48 to 0.5% vol. with the subsequent synthesis of methanol at a flow scheme for low-temperature copper-containing catalyst (e.g. DN-8-2) under pressure of 5 MPa at a temperature of 200 - 300C and at a ratio of N2: WITH = 22.5 : 1, after separation of the methanol gas komprimiert and sent to the ammonia synthesis on the circulation diagram. The implementation of this method can reduce the total content of inert impurities (argon + methane) in the fresh synthesis gas from 1.5 to 0.75%, that reduces the number of blows. Poison the catalyst in the synthesis of ammonia, oxides of carbon are present in trace amounts. 1 Il.

The invention I produce ammonia and methanol. Most of these schemes operate on a similar principle. There is a project co-production of ammonia and methanol, according to which from the converted gas initially get methanol. Thus due to the recycling of carbon monoxide concentration in the gas is reduced. Next, the residual carbon monoxide are oxidized by oxygen in the air and hydronaut to methane. The gas mixture was purified of carbon dioxide, is fed to the ammonia synthesis (see Chem. Econ. Eng. Rev. 1972, vol. 4, N 11, p. 32 - 34). According to another scheme, a mixture of carbon oxides and hydrogen is passed at a temperature of 160 - 300oC and a pressure of 5 to 15 MPa through the catalyst layers. The catalyst is placed in multiple, consecutive, the reactors. The gas circulation by reducing the concentration of carbon monoxide in the exhaust gases, which then converts it to steam. After cleaning gas from carbon dioxide and methane residual hydrogen is used to produce ammonia (see U.S. Pat. 67675, 1973 [NDP]). Also developed a scheme with a slightly different principle. According to this method, natural gas komprimiert, cleaned of sulfur compounds, is mixed with steam and fed into a tubular furnace for conversion. After that, the converted gas is cooled in the heat exchange is Lennie gases are mixed in the mixer, komprimiert to pressure synthesis and sent to the column, where the catalyst carry out the synthesis of methanol. Nephrolithotripsy in diffusers gas stream is mixed with the heated air and direct in the shaft reactor where the conversion of the residual hydrocarbons. After that, the gas is further scheme for the synthesis of ammonia (ed. St. N 1197997, class C 01 3/38, 1985 [the USSR], ed. St. N 1407898, class C 01 3/38, 1988 [USSR]). As a prototype accept the scheme co-production of ammonia and methanol, in which the synthesis gas to ammonia synthesis goes through the following stages: purification from sulfur compounds, the conversion of excess carbon monoxide, compression, purification from carbon dioxide and methanol synthesis. To ensure deep processing of carbon oxides and get gas enriched with hydrogen, methanol synthesis maintain a high ratio of H2:CO in fresh (5:1) and the circulation (14:1) gas (see Karavaev M. M. and others - Attn. prom., 1965, No. 4, S. 74-91).

A distinctive feature of all these schemes is the presence of circulating synthesis gas for methanol synthesis, which leads to purging and loss of process gas, and subsequent fine purification of gases on artnik impurities in the gas, going for the synthesis of ammonia, and as sledstvie, reducing blowdown and losses of raw materials.

The basis of the proposed scheme takes standard scheme ammonia production capacity of 1360 tons of ammonia per day. But compared to the standard in the proposed scheme, there is no stage low-temperature conversion of carbon monoxide and mahanirvana. Instead, offer after high-temperature conversion of CO to do the cleaning gas from the carbon dioxide absorber hot solution of potash to a residual content of CO2in Gaza 0.48-0.50 vol.%. Then the gas is sent not to the hydrogenation to methane, and the first stage of compression to a pressure of 5 MPa, followed by the synthesis of methanol at a temperature of 200-300oC. Synthesis of methanol is performed in the absence of circulating synthesis gas in a flow diagram. The ratio of H2: CO in the gas in the synthesis of methanol reaches 22.5:1. Synthesis is carried out at low temperature copper-containing catalyst for low pressure, for example DN-8-2. The composition of the catalyst, the molar fraction: CuO: ZnO: Cr2O3:MnO:MgO:Al2O3:BaO=1:0.3:(0.15-0.2):(0.05-0.1):(0.05-0.1): (0.25-0.3): 0.05 (see Kurylev A. Y., Tarasov, L. A. the Effect of promoters on the rate of recovery of low-temperature Katalizator. 13-15. Dept. in VINITI N 2685 - B95 from 5.10.95,, Barkovsky A. I., Kurylev A. Y., L. Tarasov A., Anokhin Century. N. The effect of promoters on the activity of low-temperature catalyst for methanol synthesis. Materials of the scientific - technical conference of NIRTO Novomoskovsk, 7 - 9 December 1994, Part 1, pages 34 - 35. Dept. in VINITI N 2685 - B95 from 5.10.95 year). After methanol synthesis gas is returned to stage the standard scheme of the synthesis of ammonia (daimonia gas until the pressure of the synthesis and the synthesis of the circulation scheme).

The drawing shows a circuit diagram for implementing the proposed method.

Natural gas is compressed in the compressor 1 to a pressure of 2.7 MPa and carry out the desulfurization in the adsorber 2, then the gas is sent to a two-step conversion of methane 3 and 4. After that, the converted gas containing, vol.%: N2- 20.49, Ar - 0.26, H2- 58.33, CO - 12.98, CO2- 7.59, CH4- 0.35, is a high-temperature conversion of carbon monoxide 5 at a temperature of 270oC and a pressure of 2.7 MPa. Further, the gas content, vol.%: N2- 18.64, Ar - 0.23, Hz - 62.08, CO - 2.79, CO2- 15.92, CH4- 0.32, - sent for purification from carbon dioxide 6, after which the gas has the following composition,%: N2- 22.07, Ar - 0.28, H2- 73.48, CO - 3.31, CO22 - 0.48, CH4 lack of H2after synthesis of methanol to stoichiometry in the synthesis of ammonia, and is sent to the syngas compressor. After the first stage of compression 7 gas with a pressure of 5 MPa, containing about.%: N2- 21.91, Ar - 0.28, H2- AT 73.69, CO - 3.27, CO2- 0.48, CH4- 0.38, heated to 200oC in the heat exchanger 8 and is directed in column 9 for the synthesis of methanol under a pressure of 5 MPa at a temperature of 200 - 280oC on the low-temperature copper-containing catalyst with a bulk velocity of 20000 h-1. After cooling to 40oC in the heat exchanger 10 and the separation of methanol 11 gas having a composition, vol.%: N2- 24.82, Ar - 0.31, H2- 74.44, CH4- 0.43, send to the second and subsequent stages 12 compressing the synthesis gas to 30 MPa. After each stage of compression set separators for selecting the condensed during compression of the fluid containing methanol. The gas then goes to the ammonia synthesis 13 on the circulation diagram. After the ammonia synthesis gas is cooled in the refrigerator 14, then in the separator 15 separates the production of ammonia.

Research conducted by flowing the synthesis of methanol at temperatures from 200 to 300oC on the low-temperature copper-containing catalyst DN-8-2.with temperature 220oC, oxides of carbon is completely converted into methanol. Output of crude methanol in the temperature range 240 - 280oC remains practically unchanged and amounts to about 4.5% vol. from the total amount of synthesis gas leaving the column for methanol synthesis. The content of methanol in the raw ranges from 91 to 95%. At a temperature of 300oC output raw a few decreases to about 4. %), and the methanol content can be reduced to 87%. Therefore, the most appropriate to carry out the process at a temperature of 240 - 280oC (catalyst DN-8-2).

In the proposed scheme, the content of inert impurities (argon and methane) gas, going to the ammonia synthesis, decreases in 2 times due to the lack of stage mahanirvana, and poison the catalyst in the synthesis of ammonia, oxides of carbon are present in trace amounts. In addition, with the increase in natural gas consumption by 10% compared to the standard scheme of the synthesis of ammonia is possible to obtain the same amount of ammonia, which according to the standard scheme, and up to 90,000 tons per year of crude methanol from the methanol content up to 95%.

The way co-production of ammonia and methanol, including desulfurization, two-step conversion of methane, a high-temperature conversion oceanium 5 MPa and synthesis of ammonia under a pressure of 30 MPa, characterized in that the cleaning gas from the carbon dioxide lead directly after high-temperature conversion of carbon monoxide to a residual content of carbon dioxide of 0.48 to 0.5% vol. with the subsequent synthesis of methanol at a flow scheme for low-temperature copper-containing catalyst (e.g. DN - 8 - 2) under pressure of 5 MPa at a temperature of 200 - 300oAnd the ratio of N2: WITH = 22,5 : 1, after separation of the methanol gas komprimiert and sent to the ammonia synthesis on the circulation diagram.

 

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