An energy-saving ultra-large-scale methanol synthesis method and device for producing different grades of steam

Abstract

The invention discloses an energy-efficient super-large scale methanol-synthesizing method with production of steam of different grades. Virgin gas is compressed and mixed with circulation gas for forming a gas mixture, the gas mixture is heated and simultaneously enters two parallelly arranged first methanol reactors for carrying out methanol synthesis reactions, and incompletely reacted synthetic gas and a methanol steam mixture are formed; the incompletely reacted synthetic gas and the methanol steam mixture are cooled and enter a second methanol reactor for carrying out a methanol synthesis reaction to obtain a final product; the final product is cooled and separated, and parts of the separated gas is used as circulation gas; and liquid crude methanol enters a downstream rectification unit. The invention also discloses an apparatus for realizing the method. A reasonably configured heat exchanger network is used for improving conversion per pass and concentration of methanol at the outlet of the reactor maximally, and reducing recycle ratio and energy consumption, and producing steam of different grades; the low pressure steam can meet low pressure steam demands of the downstream methanol rectification unit.

Description

technical field

[0001] The invention relates to the technical field of preparing methanol from synthesis gas containing hydrogen and carbon oxides, in particular to an energy-saving ultra-large-scale methanol synthesis method and device for producing steam of different grades. Background technique

[0002] It is known to those skilled in the art that by converting (H 2 -CO 2 ) / (CO+CO 2 ) value of about 2.0-2.1 synthesis gas catalytic reaction method and process for producing methanol.

[0003] At present, methanol synthesis production equipment is developing in the direction of large scale, high conversion rate per pass, reasonable energy recovery, small temperature difference between catalyst beds, small pressure drop in synthesis reactor, simple structure, stable, reliable and convenient operation, etc.

[0004] The method and system for producing methanol on a large scale is as described in CN102171171A. After the fresh gas is mixed with the recycle gas, it first enter...

Examples

Embodiment 1

[0089] see figure 1 , the energy-saving ultra-large-scale methanol synthesis plant for producing different grades of steam shown in the figure includes two water-cooled methanol reactors A1 and A2, a methanol reactor C with another structure, and two vapor-liquid separators B , D, one gas-liquid separator H, one compressor K, two gas-gas heat exchangers L, E, one air cooler F, one water-cooled heat exchanger G, one circulating compressor J, one Taiwan decompression flash tank I.

[0090] Water-cooled methanol reactors A1 and A2 are equipped with mixed gas inlets A11 and A21 on the top, gas-liquid mixture outlets A12 and A22 on the upper part, separated water return ports A13 and A23 on the lower part, and unreacted synthesis gas and methanol at the bottom Steam mixture outlets A14 and A24, and heating devices A15 and A25 for start-up are also arranged at the lower part of the water-cooled methanol reactors A1 and A2. A number of reaction tubes are arranged in the water-coole...

Embodiment 2

[0112] see figure 2 , the difference between the energy-saving ultra-large-scale methanol synthesis device for producing different grades of steam in the figure and the embodiment 1 is that the gas-gas heat exchanger L is canceled, the unreacted synthesis gas at the bottom of the water-cooled methanol reactor A1, A2 and Methanol vapor mixture outlets A14, A24 are directly connected with the unreacted synthesis gas and methanol vapor mixture inlet C1 at the top of methanol reactor C of another structural form through the unreacted synthesis gas and methanol vapor mixture delivery pipe 4. The mixed gas outlet E2 of the gas heat exchanger E is directly connected to the mixed gas inlets A11 and A21 at the top of the water-cooled methanol reactors A1 and A2 through the mixed gas delivery pipe 3 .

[0113] The fresh gas enters the compressor K through the fresh gas delivery pipe 1, the pressure rises to 7.9MPag, and then mixes with the circulating gas from the circulating gas deliv...

Embodiment 3

[0121] see image 3 , the difference between the energy-saving ultra-large-scale methanol synthesis plant producing different grades of steam shown in the figure and Example 1 is that the gas-gas heat exchanger L has an inlet L1 for unreacted synthesis gas and methanol steam mixture, and an inlet L1 for unreacted synthesis gas. Gas and methanol vapor mixture outlet L2, recycle gas inlet L3', recycle gas outlet L4', recycle gas delivery pipe 2 is also connected with recycle gas inlet L3' of gas-gas heat exchanger L through a recycle gas delivery pipe 2a, gas The recycle gas outlet L4' of the heat exchanger L is connected to the mixed gas inlets A11 and A21 at the top of the water-cooled methanol reactors A1 and A2 through the mixed gas delivery pipe 3', and the mixed gas outlet E2 of the gas-gas heat exchanger E is transported through the mixed gas The pipe 3" is connected with the mixed gas delivery pipe 3'.

[0122] The fresh gas enters the compressor K through the fresh gas...

technical field

[0001] The invention relates to the technical field of preparing methanol from synthesis gas containing hydrogen and carbon oxides, in particular to an energy-saving ultra-large-scale methanol synthesis method and device for producing steam of different grades. Background technique

[0002] It is known to those skilled in the art that by converting (H 2 -CO 2 ) / (CO+CO 2 ) value of about 2.0-2.1 synthesis gas catalytic reaction method and process for producing methanol.

[0003] At present, methanol synthesis production equipment is developing in the direction of large scale, high conversion rate per pass, reasonable energy recovery, small temperature difference between catalyst beds, small pressure drop in synthesis reactor, simple structure, stable, reliable and convenient operation, etc.

[0004] The method and system for producing methanol on a large scale is as described in CN102171171A. After the fresh gas is mixed with the recycle gas, it first enter...

Examples

Embodiment 1

[0089] see figure 1 , the energy-saving ultra-large-scale methanol synthesis plant for producing different grades of steam shown in the figure includes two water-cooled methanol reactors A1 and A2, a methanol reactor C with another structure, and two vapor-liquid separators B , D, one gas-liquid separator H, one compressor K, two gas-gas heat exchangers L, E, one air cooler F, one water-cooled heat exchanger G, one circulating compressor J, one Taiwan decompression flash tank I.

[0090] Water-cooled methanol reactors A1 and A2 are equipped with mixed gas inlets A11 and A21 on the top, gas-liquid mixture outlets A12 and A22 on the upper part, separated water return ports A13 and A23 on the lower part, and unreacted synthesis gas and methanol at the bottom Steam mixture outlets A14 and A24, and heating devices A15 and A25 for start-up are also arranged at the lower part of the water-cooled methanol reactors A1 and A2. A number of reaction tubes are arranged in the water-coole...

Embodiment 2

[0112] see figure 2 , the difference between the energy-saving ultra-large-scale methanol synthesis device for producing different grades of steam in the figure and the embodiment 1 is that the gas-gas heat exchanger L is canceled, the unreacted synthesis gas at the bottom of the water-cooled methanol reactor A1, A2 and Methanol vapor mixture outlets A14, A24 are directly connected with the unreacted synthesis gas and methanol vapor mixture inlet C1 at the top of methanol reactor C of another structural form through the unreacted synthesis gas and methanol vapor mixture delivery pipe 4. The mixed gas outlet E2 of the gas heat exchanger E is directly connected to the mixed gas inlets A11 and A21 at the top of the water-cooled methanol reactors A1 and A2 through the mixed gas delivery pipe 3 .

[0113] The fresh gas enters the compressor K through the fresh gas delivery pipe 1, the pressure rises to 7.9MPag, and then mixes with the circulating gas from the circulating gas deliv...

Embodiment 3

[0121] see image 3 , the difference between the energy-saving ultra-large-scale methanol synthesis plant producing different grades of steam shown in the figure and Example 1 is that the gas-gas heat exchanger L has an inlet L1 for unreacted synthesis gas and methanol steam mixture, and an inlet L1 for unreacted synthesis gas. Gas and methanol vapor mixture outlet L2, recycle gas inlet L3', recycle gas outlet L4', recycle gas delivery pipe 2 is also connected with recycle gas inlet L3' of gas-gas heat exchanger L through a recycle gas delivery pipe 2a, gas The recycle gas outlet L4' of the heat exchanger L is connected to the mixed gas inlets A11 and A21 at the top of the water-cooled methanol reactors A1 and A2 through the mixed gas delivery pipe 3', and the mixed gas outlet E2 of the gas-gas heat exchanger E is transported through the mixed gas The pipe 3" is connected with the mixed gas delivery pipe 3'.

[0122] The fresh gas enters the compressor K through the fresh gas...

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