Device for separating synthesis gas and purifying carbon monoxide

Abstract

The utility model discloses a device for separating synthesis gas and purifying carbon monoxide, which comprises a pre-cooling device for pre-cooling unseparated synthesis gas to form a gas-liquid mixed material; the gas-liquid separation device is used for carrying out gas-liquid separation on the gas-liquid mixed material to obtain hydrogen-rich gas and carbon monoxide-rich liquid; the hydrogen-rich gas reheating device is used for heating the hydrogen-rich gas to obtain normal-temperature hydrogen-rich gas; the carbon monoxide reheating device is used for heating the carbon monoxide-rich liquid to obtain normal-temperature carbon monoxide-rich gas; and the carbon monoxide gas pressurizing device is used for compressing the normal-temperature carbon monoxide-rich gas to obtain pressurized carbon monoxide-rich gas. The method for separating and purifying the carbon monoxide from the synthesis gas can cope with the great change of hydrogen and carbon monoxide in the synthesis gas composition caused by the change of raw materials, and can ensure that the quantity and the purity of the sent carbon monoxide product meet the requirements of a downstream device for preparing ethanol from the synthesis gas.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, specifically to a device for separating and purifying carbon monoxide from syngas. Background Technology

[0002] Currently, the most commonly used carbon monoxide purification processes include cryogenic separation, membrane separation, and pressure swing adsorption. Cryogenic separation is used when downstream users require high purity carbon monoxide products, while membrane separation or pressure swing adsorption can be used when downstream users do not require high purity carbon monoxide products.

[0003] Taking the process of producing ethanol from syngas as an example, the purity requirement of the raw material carbon monoxide is usually not high. At the same time, it is also required to contain some hydrogen components. Generally, CO≥94.5v%, H2≤5v% is required. The remaining trace components are trace N2, AR and CH4 in the separation process of raw material syngas. These trace impurities have limited content in the raw material non-shift syngas and usually do not need to be separated. In this case, the carbon monoxide product can also meet the purity requirements of the downstream ethanol process.

[0004] Currently, carbon monoxide purification units built to support the syngas-to-ethanol process are usually membrane separation processes that can meet the carbon monoxide purity requirements of the product. Only when the content of several impurity components such as N2, AR, and CH4 in the feed gas is high, are cryogenic separation or pressure swing adsorption processes considered.

[0005] The syngas produced by the coal gasification unit (dry coal powder fluidized bed gasification technology) mainly consists of H2, CO, CO2, H2S, H2O, N2, AR, CH4, etc. After non-shift gas heat recovery treatment, the water vapor is saturated water vapor at room temperature (with limited content). Then, it is treated by a low-temperature methanol washing unit to remove acidic components such as CO2 and H2S, as well as trace amounts of water. Finally, the purified syngas mainly consists of H2 and CO, as well as trace amounts of N2, AR, and CH4, with the rest being negligible.

[0006] When the type of raw coal used in a coal gasification unit changes, the main components H2 and CO in the final syngas usually show opposite trends of increase and decrease; that is, when H2 increases, CO decreases accordingly. If the change in the type of raw coal causes significant changes in these two components in the syngas, especially a substantial decrease in CO, the original carbon monoxide purification unit will be greatly affected, often resulting in the inability to guarantee the flow rate or purity of the carbon monoxide product.

[0007] Based on the above factors, it is necessary to design a process that can be connected in series or in parallel with existing technologies, minimize investment and energy consumption, and quickly deliver carbon monoxide products that meet purity requirements, ensuring a stable supply of carbon monoxide to downstream carbon monoxide-using devices. Utility Model Content

[0008] This method proposes a device for separating and purifying carbon monoxide from syngas to ensure a stable gas supply to downstream carbon monoxide-consuming plants. This objective can be achieved through the following technical solutions:

[0009] An apparatus for separating and purifying carbon monoxide from syngas, comprising:

[0010] The precooling unit is used to precool the unseparated syngas to form a gas-liquid mixture.

[0011] A gas-liquid separation device is used to separate gas and liquid mixtures to obtain hydrogen-rich gas and carbon monoxide-rich liquid.

[0012] A hydrogen-rich gas reheating device is used to heat the hydrogen-rich gas to obtain room-temperature hydrogen-rich gas.

[0013] A carbon monoxide reheating device is used to heat the carbon monoxide-rich liquid to obtain a room-temperature carbon monoxide-rich gas.

[0014] A carbon monoxide gas pressurization device is used to compress room-temperature carbon monoxide-rich gas to obtain pressurized carbon monoxide-rich gas.

[0015] Optionally, the precooling device, the hydrogen-rich gas reheating device, and the carbon monoxide reheating device employ heat exchangers; the heat exchangers include:

[0016] The first heat exchange channel is used for pre-cooling the unseparated syngas;

[0017] The second heat exchange channel is used to heat the hydrogen-rich gas; the second heat exchange channel is connected to the gas phase outlet of the gas-liquid separator through a hydrogen-rich gas pipeline; the hydrogen-rich gas pipeline is equipped with a first throttle valve for reducing pressure and cooling the hydrogen-rich gas.

[0018] The third heat exchange channel is used to heat the carbon monoxide-rich liquid; the second heat exchange channel is connected to the liquid phase outlet of the gas-liquid separation device through a carbon monoxide-rich liquid pipeline; the carbon monoxide-rich liquid pipeline is equipped with a second throttle valve for reducing pressure and cooling the carbon monoxide-rich liquid.

[0019] Optionally, the heat exchanger further includes a fourth heat exchange channel, which is used to introduce liquid nitrogen to supplement the cooling of the heat exchanger.

[0020] Optionally, it also includes a syngas film separation system; the syngas film separation system includes:

[0021] A membrane separator includes an unseparated syngas inlet, a membrane-separated permeate outlet, and a membrane-separated non-permeate outlet;

[0022] A permeate screw compressor, wherein the inlet of the permeate screw compressor is connected to the permeate outlet of the membrane separation;

[0023] A carbon monoxide compressor, wherein the inlet of the carbon monoxide compressor is connected to the non-permeable gas outlet;

[0024] The pressurized carbon monoxide-rich gas obtained from the carbon monoxide gas pressurization device is sent to the inlet of the membrane separator, and the ambient temperature hydrogen-rich gas obtained from the hydrogen-rich gas reheating device is sent to the inlet of the permeate screw compressor.

[0025] Optionally, a second gas-liquid separation device is provided on the carbon monoxide-rich liquid pipeline at a position between the second throttle valve and the third heat exchange channel. The second gas-liquid separation device is used to separate the secondary hydrogen-rich gas formed in the carbon monoxide-rich liquid.

[0026] Optionally, the inlet of the second gas-liquid separator is connected to the second throttle valve, the gas phase outlet of the second gas-liquid separator is used to output secondary hydrogen-rich gas, and the liquid phase outlet of the second gas-liquid separator is connected to the third heat exchange channel.

[0027] Optionally, the heat exchanger further includes a fifth heat exchange channel, which is used to heat the secondary hydrogen-rich gas to obtain room-temperature secondary hydrogen-rich gas.

[0028] Optionally, the ambient temperature secondary hydrogen-rich gas is fed into the inlet of the carbon monoxide gas pressurization device.

[0029] Optionally, it also includes a syngas film separation system; the syngas film separation system includes:

[0030] A membrane separator includes an unseparated syngas inlet, a membrane-separated permeate outlet, and a membrane-separated non-permeate outlet;

[0031] A permeate screw compressor, wherein the inlet of the permeate screw compressor is connected to the permeate outlet of the membrane separation;

[0032] A carbon monoxide compressor, wherein the inlet of the carbon monoxide compressor is connected to the non-permeable gas outlet;

[0033] The pressurized carbon monoxide-rich gas obtained from the carbon monoxide gas pressurization device is sent to the inlet of the carbon monoxide compressor, and the ambient temperature hydrogen-rich gas obtained from the hydrogen-rich gas reheating device is sent to the outlet of the permeate screw compressor.

[0034] Optionally, the outlet of the permeate screw compressor may also be connected to a permeate reciprocating compressor.

[0035] The technical solution of this utility model has the following advantages:

[0036] This invention provides a method for separating and purifying carbon monoxide from syngas. This method can address significant variations in the hydrogen and carbon monoxide composition of syngas caused by changes in raw materials. Whether operated in series or parallel with an existing membrane separation carbon monoxide extraction unit via a pre-cooling box, or using a two-stage throttling process with a separate pre-cooling box, the quantity and purity of the delivered carbon monoxide product can be guaranteed to meet the requirements of downstream syngas-to-ethanol units. The required additional equipment is limited, the footprint is very compact, and the investment is small, yet it can significantly improve the stability of the carbon monoxide product, ensuring that the downstream unit's capacity is not affected by the purity of the carbon monoxide gas. Attached Figure Description

[0037] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 A simplified flowchart of the membrane separation process for extracting carbon monoxide;

[0039] Figure 2 A simplified flowchart of a process for extracting carbon monoxide by combining membrane separation with a single-stage throttling process;

[0040] Figure 3 A simplified flowchart of a process for extracting carbon monoxide by combining membrane separation with a two-stage throttling process;

[0041] Explanation of reference numerals in the attached figures:

[0042] Figure 1 Chinese figure labels:

[0043] M100 - Membrane separation; C100 - Permeate gas screw compressor; C101 - Permeate gas reciprocating compressor; C102 - Product carbon monoxide compressor.

[0044] 100 - Unseparated syngas; 101 - Membrane separation non-permeate gas; 102 - Product carbon monoxide gas; 103 - Membrane separation permeate gas; 104 - Pressurized permeate gas; 105 - Product permeate gas.

[0045] Figure 2 Chinese figure labels:

[0046] M100 - Membrane separator; C100 - Permeate gas screw compressor; C101 - Permeate gas reciprocating compressor; C102 - Product carbon monoxide compressor; E200 - Heat exchanger; V200 - Separator; C200 - Carbon monoxide-rich compressor.

[0047] 100 - Unseparated syngas; 100a - Unseparated syngas mixed with carbon monoxide-rich gas; 101 - Non-permeate gas from membrane separation; 102 - Product carbon monoxide gas. 103 - Permeate gas from membrane separation; 103a - Mixture of permeate gas from membrane separation and hydrogen-rich gas; 104 - Pressurized permeate gas; 105 - Product permeate gas. 200 - Unseparated syngas; 201 - Gas-liquid mixture; 202 - Hydrogen-rich gas; 203 - Low-temperature hydrogen-rich gas; 204 - Room-temperature hydrogen-rich gas. 205 - Carbon monoxide-rich liquid; 206 - Carbon monoxide-rich material after depressurization; 207 - Room-temperature carbon monoxide-rich gas; 208 - Pressurized carbon monoxide-rich gas. 209 - Liquid nitrogen; 210 - Nitrogen gas.

[0048] Figure 3 Chinese figure labels:

[0049] M100 - Membrane separator; C100 - Permeate gas screw compressor; C101 - Permeate gas reciprocating compressor; C102 - Product carbon monoxide compressor; E300 - Heat exchanger; V300 - Primary separator; V301 - Secondary separator; C300 - Carbon monoxide-rich compressor.

[0050] 100 - Unseparated syngas; 101 - Membrane-separated non-permeate gas; 101a - Membrane-separated permeate gas mixed with carbon monoxide-rich gas; 102 - Product carbon monoxide gas; 103 - Membrane-separated permeate gas; 104 - Pressurized permeate gas; 104a - Membrane-separated permeate gas mixed with hydrogen-rich gas; 105 - Product permeate gas. 300 - Unseparated syngas; 301 - Gas-liquid mixture; 302 - Primary flash hydrogen-rich gas; 303 - Primary cryogenic hydrogen-rich gas; 304 - Primary ambient temperature hydrogen-rich gas; 321 - Secondary hydrogen-rich gas; 322 - Secondary cryogenic hydrogen-rich gas; 323 - Secondary ambient temperature hydrogen-rich gas; 324 - Secondary carbon monoxide-rich liquid; 305 - Primary carbon monoxide-rich liquid; 320 - Primary reduced pressure carbon monoxide-rich liquid; 306 - Reduced pressure carbon monoxide-rich liquid; 307 - Secondary ambient temperature carbon monoxide-rich gas; 307a - Carbon monoxide-rich gas; 308 - Added carbon monoxide-rich gas; 309 - Liquid nitrogen; 310 - Nitrogen. Detailed Implementation

[0051] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0052] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0053] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art described herein. While only preferred methods and materials are described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0054] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0055] A simplified process diagram of a membrane separator used in the production of ethanol from syngas is shown below. Figure 1 As shown, the facility includes a membrane separator M100, a permeate screw compressor C100, a permeate reciprocating compressor C101, a product carbon monoxide compressor C102, and associated piping and valves. The permeate compressor can be configured according to the pressure and the required final compression pressure. It can consist of a single permeate screw compressor, a permeate reciprocating compressor, a permeate centrifugal compressor, or a combination of these compressors; details will not be elaborated here.

[0056] Typically, the existing membrane separator M100 separates the unseparated syngas 100 into two products: membrane separation permeate gas 103 and membrane separation non-permeate gas 101. The membrane separation permeate gas 103 is compressed by the permeate screw compressor C100 to obtain pressurized permeate gas 104, which is then sent to the inlet of the permeate reciprocating compressor C102 for further pressurization and is then sent out as product permeate gas 105. The non-permeate gas is compressed by the product carbon monoxide compressor C102 to become product carbon monoxide gas 102.

[0057] The coal gasification unit used in the above-mentioned membrane separator carbon monoxide extraction unit has good coal quality, resulting in a high carbon monoxide content in the generated non-shift gas. Therefore, the delivered carbon monoxide gas 102 can meet the purity requirements of downstream applications. The various streams under normal operating conditions are shown in Table 1.

[0058] Appendix 1 - Material Inlet and Outlet Table for Membrane Separator Carbon Monoxide Extraction Unit

[0059] Item Units 100 101 102 103 104 105 T ℃ 40 40 40 40 40 40 P Bar A 35 33 53 2.5 18 53 H2 Mol Frac 0.2935 0.0085 0.0085 0.6373 0.6373 0.6373 CO Mol Frac 0.7000 0.9822 0.9822 0.3592 0.3592 0.3592 N2 Mol Frac 0.0050 0.0072 0.0072 0.0026 0.0026 0.0026 AR Mol Frac 0.0012 0.0017 0.0017 0.0006 0.0006 0.0006 C1 Mol Frac 0.0003 0.0004 0.0004 0.0013 0.0013 0.0013 Total Mol Frac 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000

[0060] Note: For actual products, the carbon monoxide requirement is CO ≥ 94.50 v%, which is equivalent to a mole fraction of 0.9450.

[0061] When the quality of the raw coal in the upstream coal gasification unit deteriorates, the carbon monoxide content in the non-conversion syngas it sends out will decrease significantly. Usually, when it is below 5v%, the existing membrane separator carbon monoxide extraction unit can handle it. However, when the variation range is between 5v% and 15v%, the membrane separator carbon monoxide extraction unit cannot guarantee the purity and flow rate of the carbon monoxide in the product. At this time, appropriate technical modifications need to be considered. Otherwise, the reduced purity of the carbon monoxide in the sent product will have a significant impact on the production capacity of the downstream syngas to ethanol production unit.

[0062] Example 1

[0063] This embodiment provides an apparatus for separating and purifying carbon monoxide from syngas, such as... Figure 2 The diagram shows a simplified process for carbon monoxide extraction using a membrane separator combined with a single-stage throttling process. This device adds a heat exchanger (pre-cooling box) and a carbon monoxide-rich compressor to the existing membrane separator unit used for ethanol production from syngas. Specifically, it includes:

[0064] The membrane separator M100 includes an unseparated syngas inlet, a membrane-separated permeate outlet, and a membrane-separated non-permeate outlet.

[0065] A permeate screw compressor C100 is provided, the inlet of which is connected to the permeate outlet of the membrane separation; the outlet of the permeate screw compressor C100 is also connected to a permeate reciprocating compressor C101.

[0066] A carbon monoxide compressor C102, wherein the inlet of the carbon monoxide compressor is connected to the non-permeable gas outlet;

[0067] A precooling device is used to precool the unseparated syngas 200 to form a gas-liquid mixture 201;

[0068] A gas-liquid separation device is used to separate the gas-liquid mixture 201 into hydrogen-rich gas 202 and carbon monoxide-rich liquid 205; in this embodiment, a separation tank V200 is used.

[0069] A hydrogen-rich gas reheating device is used to heat the hydrogen-rich gas 202 to obtain room-temperature hydrogen-rich gas 204.

[0070] A carbon monoxide reheating device is used to heat the carbon monoxide-rich liquid 205 to obtain a room-temperature carbon monoxide-rich gas 207.

[0071] A carbon monoxide gas pressurization device is used to compress room-temperature carbon monoxide-rich gas 207 to obtain pressurized carbon monoxide-rich gas 208. In this embodiment, the carbon monoxide gas pressurization device adopts a carbon monoxide-rich compressor C200.

[0072] The pressurized carbon monoxide-rich gas 208 obtained from the carbon monoxide gas pressurization device is sent to the inlet of the membrane separator, and the ambient temperature hydrogen-rich gas 204 obtained from the hydrogen-rich gas reheating device is sent to the inlet of the permeate screw compressor C100.

[0073] Specifically, in this embodiment, the precooling device, the hydrogen-rich gas reheating device, and the carbon monoxide reheating device are implemented using a heat exchanger E200 (precooling cold box); the heat exchanger E200 includes multiple heat exchange channels, wherein:

[0074] The first heat exchange channel 200A is the pre-cooling device, which is used to pre-cool the unseparated syngas.

[0075] The second heat exchange channel 200B is a hydrogen-rich gas reheating device used to heat the hydrogen-rich gas; the second heat exchange channel is connected to the gas phase outlet of the gas-liquid separator through a hydrogen-rich gas pipeline; the hydrogen-rich gas pipeline is equipped with a first throttle valve JT200 for reducing pressure and cooling the hydrogen-rich gas.

[0076] The third heat exchange channel 200C is a carbon monoxide reheating device used to heat the carbon monoxide-rich liquid. It should be noted that the temperature of the carbon monoxide-rich liquid is still low after heat exchange and needs to be reheated to room temperature in the pipeline. The second heat exchange channel is connected to the liquid phase outlet of the gas-liquid separator through a carbon monoxide-rich liquid pipeline. The carbon monoxide-rich liquid pipeline is equipped with a second throttle valve JT201 for reducing pressure and cooling the carbon monoxide-rich liquid.

[0077] The heat exchanger also includes a fourth heat exchange channel 200D, which is used to introduce liquid nitrogen 209 to supplement the cooling of the heat exchanger. After heat exchange, the liquid nitrogen 209 forms nitrogen gas 210.

[0078] Heat exchanger E200 (pre-cooling cold box) is designed according to the first-stage throttling process. Unseparated synthesis gas 200 is pre-cooled to -150℃ to -180℃ by heat exchanger E200. The resulting gas-liquid mixture 201 is a two-phase gas-liquid mixture. Gas-liquid separation is carried out in separator V200. The gas phase is hydrogen-rich gas 202. After being depressurized by the first throttling valve JT200, it produces low-temperature hydrogen-rich gas 203. After being reheated by the heat exchanger, it becomes room-temperature hydrogen-rich gas 204. Finally, it is sent to the inlet of compressor C100 and pressurized together with the permeate gas from the membrane separator and sent out. Liquid carbon monoxide-rich liquid 205 is discharged from the bottom of the separator V200. After being depressurized by the second throttle valve JT201, it produces depressurized carbon monoxide-rich liquid material 206 (gas-liquid two-phase). After being reheated by the heat exchanger, it becomes room temperature carbon monoxide-rich gas 207, which is sent to the inlet of the newly added carbon monoxide-rich compressor C200. After being pressurized by C200, the pressurized carbon monoxide-rich gas 208 is sent to the inlet of the membrane separator M100 to obtain unseparated syngas and carbon monoxide-rich mixed gas 100a. Then, the existing membrane separator is used to further purify carbon monoxide. With this pre-cooling cold box setting, the equipment in the existing membrane separator carbon monoxide extraction unit can be utilized to the maximum extent, reducing investment and energy consumption.

[0079] During start-up and shutdown, insufficient cooling capacity can be supplied by reheating liquid nitrogen 209 into nitrogen gas 210 via heat exchanger E200. The reheated nitrogen gas 210 can be directly discharged to the atmosphere at a high point or supplied to a nitrogen system network at a similar pressure. The parameters of each material are shown in Table 2. Pressurized carbon monoxide-rich gas 208 increases the CO content in the raw material from 57% to 90%. After mixing with the unseparated syngas at the inlet of membrane separator M100, the CO content in the unseparated syngas can be increased to over 65%, meeting the normal operating requirements of membrane separator M100.

[0080] Table 2. Process Input / Output Material Table for Example 1

[0081]

[0082]

[0083] Example 2

[0084] like Figure 3 As shown, in this embodiment, the heat exchanger (pre-cooling box, which can be a low-temperature plate-fin heat exchanger or a coiled tube heat exchanger) is designed according to a two-stage throttling process. The simplified process diagram of carbon monoxide extraction combined with the membrane separator is shown. This simplified process diagram is an addition of a pre-cooling box and a carbon monoxide-rich compressor to the existing membrane separator carbon monoxide extraction device configured for ethanol production from syngas. The membrane separator part will not be described here, only the pre-cooling box and the carbon monoxide-rich compressor part will be described.

[0085] Specifically, it includes:

[0086] The membrane separator M100 includes an unseparated syngas inlet, a membrane-separated permeate outlet, and a membrane-separated non-permeate outlet.

[0087] A permeate screw compressor C100 is provided, the inlet of which is connected to the permeate outlet of the membrane separation; the outlet of the permeate screw compressor C100 is also connected to a permeate reciprocating compressor C101.

[0088] A carbon monoxide compressor C102, wherein the inlet of the carbon monoxide compressor is connected to the non-permeable gas outlet;

[0089] A precooling device is used to precool the unseparated syngas 300 to form a gas-liquid mixture 301;

[0090] A gas-liquid separation device is used to separate the gas-liquid mixture 301 into hydrogen-rich gas 302 and primary carbon monoxide-rich liquid 305; in this embodiment, a separation tank V300 is used.

[0091] A hydrogen-rich gas reheating device is used to heat the hydrogen-rich gas 202 to obtain room-temperature hydrogen-rich gas 204. The hydrogen-rich gas reheating device is connected to the gas phase outlet of a gas-liquid separator via a hydrogen-rich gas pipeline. A first throttle valve JT200 for reducing the pressure and temperature of the hydrogen-rich gas is provided on the hydrogen-rich gas pipeline. A second throttle valve JT201 for reducing the pressure and temperature of the first-stage carbon monoxide-rich liquid 305 is provided on the pipeline for conveying the first-stage carbon monoxide-rich liquid 305. After passing through the second throttle valve JT201, the first-stage carbon monoxide-rich liquid 305 forms a reduced-pressure carbon monoxide-rich liquid 320 (gas-liquid two-phase).

[0092] The second throttle valve JT201 is connected to a second gas-liquid separation device. In this embodiment, a separation tank V301 is used. The second gas-liquid separation device is used to separate the secondary hydrogen-rich gas 321 formed in the carbon monoxide-rich liquid 320 after depressurization.

[0093] The inlet of the second gas-liquid separator is connected to the second throttle valve. The gas phase outlet of the second gas-liquid separator is used to output secondary hydrogen-rich gas 321, and the liquid phase outlet of the second gas-liquid separator outputs secondary carbon monoxide-rich liquid 324.

[0094] A carbon monoxide reheating device is used to heat the reduced-pressure carbon monoxide-rich liquid 306 formed by the secondary carbon monoxide-rich liquid 324 after being reduced by the fourth throttle valve JT303, to obtain secondary room-temperature carbon monoxide-rich gas 307.

[0095] A carbon monoxide gas pressurization device is used to compress the secondary ambient temperature carbon monoxide-rich gas 307 to obtain pressurized carbon monoxide-rich gas 308. In this embodiment, the carbon monoxide gas pressurization device adopts a carbon monoxide-rich compressor C300.

[0096] The pressurized carbon monoxide-rich gas 308 obtained from the carbon monoxide gas pressurization device is sent to the inlet of the membrane separator, and the primary ambient temperature hydrogen-rich gas 304 obtained from the hydrogen-rich gas reheating device is sent to the inlet of the permeate screw compressor C100.

[0097] Specifically, in this embodiment, the precooling device, the hydrogen-rich gas reheating device, and the carbon monoxide reheating device are implemented using a heat exchanger E300 (precooling cold box, which can be a low-temperature plate-fin heat exchanger or a coiled tube heat exchanger); the heat exchanger E300 includes multiple heat exchange channels, wherein:

[0098] The first heat exchange channel 300A is the pre-cooling device, which is used to pre-cool the unseparated syngas.

[0099] The second heat exchange channel 300B is a hydrogen-rich gas reheating device, used to heat the hydrogen-rich gas.

[0100] The third heat exchange channel 300C is a carbon monoxide reheating device, used to heat the carbon monoxide-rich liquid. It should be noted that the temperature of the carbon monoxide-rich liquid is still low after heat exchange and needs to be reheated to room temperature in the pipeline.

[0101] The heat exchanger also includes a fourth heat exchange channel 300D, which is used to introduce liquid nitrogen 209 to supplement the cooling of the heat exchanger. After heat exchange, the liquid nitrogen 309 forms nitrogen gas 310.

[0102] The heat exchanger also includes a fifth heat exchange channel 300E, which is used to heat the reduced-pressure secondary hydrogen-rich gas 322 formed by the pressure reduction of the secondary hydrogen-rich gas 321 after passing through the third throttle valve, to obtain secondary room-temperature hydrogen-rich gas 323.

[0103] Secondary ambient temperature hydrogen-rich gas 323 can be fed into the inlet of the carbon monoxide gas pressurization device.

[0104] The precooling box is designed with a two-stage throttling process. Unseparated syngas 300 is precooled to -150℃ to -180℃ by heat exchanger E300. The gas-liquid mixture 301 is a two-phase gas-liquid mixture. Gas-liquid separation is carried out in separator V300. The gas phase is hydrogen-rich gas 302. After being depressurized by the first throttling valve JT300, it produces first-stage low-temperature hydrogen-rich gas 303. After being reheated by the heat exchanger, it becomes first-stage room-temperature hydrogen-rich gas 304. Finally, it is sent to the inlet of compressor C101 to form a mixture of membrane separation permeate gas and carbon monoxide-rich gas 304a, which is pressurized and sent out together with the membrane separator permeate gas. At the bottom of separator V300, primary carbon monoxide-rich liquid 305 is discharged in liquid phase. After being depressurized by throttle valve JT301, it produces depressurized carbon monoxide-rich liquid 320 (gas-liquid two-phase). Hydrogen-rich gas 302 is separated by separator V301 into gas-phase secondary hydrogen-rich gas 321 and liquid-phase secondary carbon monoxide-rich liquid 324. Secondary hydrogen-rich gas 321 is depressurized by third throttle valve JT302 to become secondary low-temperature hydrogen-rich gas 322. 322 is reheated by heat exchanger to become secondary room-temperature hydrogen-rich gas 323. The carbon monoxide-rich liquid is throttled by fourth throttle valve JT303 to become gas-liquid two-phase carbon monoxide-rich liquid 306. After being reheated by heat exchanger E300, it becomes secondary room-temperature carbon monoxide-rich gas 307. The two reheated gases, secondary ambient temperature hydrogen-rich gas 323 and secondary ambient temperature carbon monoxide-rich gas 307, can be mixed to form carbon monoxide-rich gas 307a (if the purity meets the downstream requirements) and directly sent to the inlet of carbon monoxide-rich compressor C300. If the downstream purity requirements are not met, then the secondary ambient temperature hydrogen-rich gas 323 will no longer be mixed with the secondary ambient temperature carbon monoxide-rich gas 307, but will be directly sent to the existing gas pipeline network (such as interstage injection or depressurization to the compressor inlet of the pressure swing adsorption tail gas compressor, which will not be described here). The carbon monoxide-rich gas after being pressurized by C300 is sent to the inlet of carbon monoxide compressor C102 and pressurized to the required product pressure downstream using the existing carbon monoxide compressor. This pre-cooling cold box setup allows for series or parallel operation with the membrane separator, or can directly replace the existing membrane separator system. The pre-cooling cold box can directly achieve carbon monoxide emission in the product. This process can shut down the existing membrane separator system and the membrane separator permeate screw compressor, resulting in a significant reduction in power consumption and minimizing investment and energy consumption.

[0105] During start-up and shutdown, insufficient cooling capacity can be provided by reheating liquid nitrogen 309 into nitrogen gas 310 through heat exchanger E300. The reheated nitrogen gas 310 can be directly discharged into the atmosphere at a high point or sent to a nitrogen system pipeline network with equivalent pressure for utilization.

[0106] Appendix 3 - Process Input / Output Material Table for Example 2

[0107]

[0108] Appendix 3 (continued) - Process Input / Output Material Table for Example 2

[0109]

[0110] The change in the type of raw coal has led to a significant reduction in the carbon monoxide content in the purified non-shift syngas sent from the gasification unit (the original design condition for the carbon monoxide value in the purified non-shift syngas was CO=70v%, but the current operating data is CO=57v%). The existing membrane separator for carbon monoxide extraction can no longer simultaneously meet the downstream requirements for the quantity and purity of carbon monoxide products. However, by adding a pre-cooling box, the requirements for the quantity and purity of the gas can be met, and the additional investment and energy consumption required are lower than the sum of the power consumption of adding an extra membrane module and an extra circulating compressor to the membrane separator for carbon monoxide extraction.

[0111] This invention provides a method for separating and purifying carbon monoxide from syngas. This method addresses the significant variations in hydrogen and carbon monoxide composition in syngas caused by changes in raw materials. Whether operating in series or parallel with an existing membrane separator for carbon monoxide extraction via a pre-cooling box, or using a two-stage throttling process with a separate pre-cooling box, the quantity and purity of the delivered carbon monoxide product can be guaranteed to meet the requirements of downstream syngas-to-ethanol plants. The required additional equipment is limited, the footprint is very compact, and the investment is small, yet it significantly improves the stability of the carbon monoxide product, ensuring that the downstream plant's capacity is not affected by the purity of the carbon monoxide gas.

[0112] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. An apparatus for separating and purifying carbon monoxide from syngas, characterized in that, include: The precooling unit is used to precool the unseparated syngas to form a gas-liquid mixture. A gas-liquid separation device is used to separate a gas-liquid mixture to obtain hydrogen-rich gas and carbon monoxide-rich liquid; a hydrogen-rich gas reheating device is used to heat the hydrogen-rich gas to obtain room-temperature hydrogen-rich gas. A carbon monoxide reheating device is used to heat the carbon monoxide-rich liquid to obtain a room-temperature carbon monoxide-rich gas; a carbon monoxide gas pressurizing device is used to compress the room-temperature carbon monoxide-rich gas to obtain a pressurized carbon monoxide-rich gas.

2. The apparatus for separating and purifying carbon monoxide from syngas according to claim 1, characterized in that, The precooling device, the hydrogen-rich gas reheating device, and the carbon monoxide reheating device employ heat exchangers; the heat exchangers include: The first heat exchange channel is used for pre-cooling the unseparated syngas; The second heat exchange channel is used to heat the hydrogen-rich gas; the second heat exchange channel is connected to the gas phase outlet of the gas-liquid separator through a hydrogen-rich gas pipeline; the hydrogen-rich gas pipeline is equipped with a first throttle valve for reducing pressure and cooling the hydrogen-rich gas. The third heat exchange channel is used to heat the carbon monoxide-rich liquid; the second heat exchange channel is connected to the liquid phase outlet of the gas-liquid separation device through a carbon monoxide-rich liquid pipeline; the carbon monoxide-rich liquid pipeline is equipped with a second throttle valve for reducing pressure and cooling the carbon monoxide-rich liquid.

3. The apparatus for separating and purifying carbon monoxide from syngas according to claim 2, characterized in that, The heat exchanger also includes a fourth heat exchange channel, which is used to introduce liquid nitrogen to supplement the cooling of the heat exchanger.

4. The apparatus for separating and purifying carbon monoxide from syngas according to claim 1, characterized in that, It also includes a syngas membrane separation system; the syngas membrane separation system includes: A membrane separator includes an unseparated syngas inlet, a membrane-separated permeate outlet, and a membrane-separated non-permeate outlet; A permeate screw compressor, wherein the inlet of the permeate screw compressor is connected to the permeate outlet of the membrane separation; A carbon monoxide compressor, wherein the inlet of the carbon monoxide compressor is connected to the non-permeable gas outlet; The pressurized carbon monoxide-rich gas obtained from the carbon monoxide gas pressurization device is sent to the inlet of the membrane separator, and the ambient temperature hydrogen-rich gas obtained from the hydrogen-rich gas reheating device is sent to the inlet of the permeate screw compressor.

5. The apparatus for separating and purifying carbon monoxide from syngas according to claim 2, characterized in that, A second gas-liquid separation device is installed on the carbon monoxide-rich liquid pipeline between the second throttle valve and the third heat exchange channel. The second gas-liquid separation device is used to separate the secondary hydrogen-rich gas formed in the carbon monoxide-rich liquid.

6. The apparatus for separating and purifying carbon monoxide from syngas according to claim 5, characterized in that, The inlet of the second gas-liquid separator is connected to the second throttle valve, the gas phase outlet of the second gas-liquid separator is used to output secondary hydrogen-rich gas, and the liquid phase outlet of the second gas-liquid separator is connected to the third heat exchange channel.

7. The apparatus for separating and purifying carbon monoxide from syngas according to claim 2, characterized in that, The heat exchanger also includes a fifth heat exchange channel, which is used to heat the secondary hydrogen-rich gas to obtain room-temperature secondary hydrogen-rich gas.

8. The apparatus for separating and purifying carbon monoxide from syngas according to claim 7, characterized in that, The ambient temperature secondary hydrogen-rich gas is fed into the inlet of the carbon monoxide gas pressurization device.

9. The apparatus for separating and purifying carbon monoxide from syngas according to claim 8, characterized in that, It also includes a syngas membrane separation system; the syngas membrane separation system includes: A membrane separator includes an unseparated syngas inlet, a membrane-separated permeate outlet, and a membrane-separated non-permeate outlet; A permeate screw compressor, wherein the inlet of the permeate screw compressor is connected to the permeate outlet of the membrane separation; A carbon monoxide compressor, wherein the inlet of the carbon monoxide compressor is connected to the non-permeable gas outlet; The pressurized carbon monoxide-rich gas obtained from the carbon monoxide gas pressurization device is sent to the inlet of the carbon monoxide compressor, and the ambient temperature hydrogen-rich gas obtained from the hydrogen-rich gas reheating device is sent to the outlet of the permeate screw compressor.

10. The apparatus for separating and purifying carbon monoxide from syngas according to claim 4 or 9, characterized in that, The outlet of the permeate screw compressor is also connected to a permeate reciprocating compressor.

Images