Process and system for synthesizing high-purity industrial feed gas carbon monoxide by recycling carbon dioxide

Abstract

The invention discloses a process and a system for synthesizing high-purity industrial feed gas carbon monoxide by recycling carbon dioxide. The process mainly comprises the following steps: mixing captured CO2 and air-separated O2 to obtain a gasifying agent G1; the obtained gasifying agent G1 enters from a gasifying agent gas inlet system through the lower part of the gasification furnace, and is in countercurrent contact with a mixture entering from the upper part of the gasification furnace to generate a thermal chemical reaction; the core reaction temperature is 1600-2000 DEG C, and the pressure reaches 3.5 MPa or above; the gasifying agent G1 is converted into crude raw material gas G2, and semi-coke slag W1 is generated; and carrying out deoxidation, low-temperature methanol cleaning and cryogenic separation on the obtained crude raw material gas G2 to obtain high-purity CO gas G3. According to the method, the defects in the prior art are effectively overcome, CO2 captured from waste gas discharged by enterprises is utilized for resource value-added utilization, the purity of the finally generated CO is up to 99.5% or above, a great contribution is made to CO2 emission reduction work, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial waste gas treatment and resource recovery, and more specifically, relates to a process and system for synthesizing high-purity industrial raw gas carbon monoxide from resource-recovered carbon dioxide by thermochemical reaction. Background Art

[0002] In recent years, due to the significant increase in CO2 emissions, the global greenhouse effect caused by its accumulation in the atmosphere has attracted human attention. Therefore, recovering CO2 from exhaust gases with high CO2 concentrations and converting it into useful chemicals or fuels (i.e., CO2 resource utilization) not only solves environmental problems, but also meets the new demand for energy and chemicals. At present, common CO2 resource utilization methods include: synthesizing methane through catalytic reactions of CO2 and H2O, catalytic pyrolysis of CO2 to form useful chemicals or fuels, converting CO2 into biomass under simulated photosynthesis, and catalytic synthesis of industrial raw gas from CO2.

[0003] The catalytic synthesis of industrial raw gas (CO, CH4, etc.) by CO2 has attracted continuous attention from domestic and foreign researchers and the industry due to its relatively mature technical route, high energy utilization rate, and easy large-scale promotion. Among them, CO is an important chemical raw material that can be used as a reducing agent in chemical reactions (such as metal smelting) and is also an important raw material for chemical synthesis (such as CO can be used to synthesize formaldehyde, methyl tert-butyl ether, polyester, etc.).

[0004] Currently, common methods for catalytic synthesis of CO from CO2 include catalytic method, electrochemical method and thermochemical method.

[0005] The catalytic method reduces CO2 to CO under mild conditions by adding precious metal catalysts such as silver, gold, and palladium. For example, invention disclosure CN201711105381.X relates to a highly selective CO2 reduction photocatalyst, preparation method, and application. The catalyst is prepared by depositing Ag or Pd on the surface of ultra-thin mesoporous ZnO nanosheets by in-situ photodeposition, and the yield of methane and CO is as high as more than 90%. However, the catalyst required for the catalytic method is expensive, and the high-purity CO generated is prone to catalyst poisoning, which significantly increases the operating cost.

[0006] The electrocatalytic method is to introduce CO2 and a certain current into the electrolyte to reduce CO2 to CO. This process can be carried out at room temperature, and the CO production can be controlled by adjusting the conditions of the current and the electrolyte. For example, invention disclosure CN202010915539.5 relates to a CO2 catalytic reduction device and method, which realizes the reduction reaction of CO2 on the opposite side of the discharge electrode by constructing a friction nanogenerator and a microplasma component. However, the current electrocatalytic method still has a low catalytic efficiency and high energy consumption, and is not suitable for treating large-scale industrial flue gas CO2.

[0007] The thermochemical method is to mix the raw material (CO2) and a certain amount of solid carbon or charcoal together, and heat them to high temperature conditions to react to produce CO and CO2. On the one hand, this process requires high temperature and a large amount of solid carbon or charcoal; on the other hand, too much CO2 will lower the reaction temperature, thereby affecting the reaction efficiency. The common method at present is to add water vapor to the feed or use lignite with a high moisture content for reaction. For example, the invention disclosure CN201010524327.0 involves a method for preparing synthesis gas by replacing water vapor with CO2 as a pressurized fixed bed gasification agent, using lignite with a high moisture content of more than 20wt% to gasify in a gasifier, and the washed raw coal gas is subjected to CO conversion, and the conversion gas is cooled and purified. However, the current thermochemical method still has problems such as low CO content in the conversion gas (<35%), low CO2 conversion rate, and secondary pollution. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing CO2 resource utilization process for preparing high-purity industrial raw gas, such as substandard effect, low product purity, secondary pollution and high investment cost, and to provide a process and system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resource utilization, which is economical and efficient, has high-purity CO as the product and does not generate secondary pollution.

[0009] The above-mentioned object of the present invention is achieved by the following technical scheme: A process for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources, comprising the following steps:

[0010] S1. Mixing the captured CO2 and the O2 from the air separation to obtain the gasification agent G1;

[0011] S2. The gasifying agent G1 obtained in step S1 enters the gasifier from the gasifying agent intake system through the lower part, and contacts with the mixed material entering from the upper part in countercurrent to produce a thermochemical reaction; the core reaction temperature is 1600-2000°C, and the pressure reaches above 3.5MPa; the gasifying agent G1 is converted into a crude raw material gas G2, and a blue coke slag W1 is generated;

[0012] S3. The crude raw material gas G2 obtained in step S2 is subjected to deoxygenation, low-temperature methanol washing, and deep-cold separation to obtain high-purity CO gas G3.

[0013] Furthermore, the CO2 / O2 ratio in the gasifying agent G1 is 0.9-1.2.

[0014] Furthermore, the CO content in the raw material gas G2 generated in step S2 is greater than 90%. In the prior art, the CO content in the raw material gas is only 30%-50%, which greatly increases the energy consumption of subsequent impurity removal (O2, CO2, H2, H2S).

[0015] Furthermore, the CO content in the high-purity CO gas G3 generated in step S3 is >99.5%.

[0016] Furthermore, a system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources includes:

[0017] The gasifier air intake system is used to mix CO2 and O2 to obtain gasifier G1, and spray it into the gasifier; the feeding device is used to mix lignite and limestone in proportion to form a mixture, and feed it into the gasifier; the gasifier is used to convert the gasifier G1 into a crude raw material gas G2; the coal lock gas recovery system is arranged in the feeding lock of the feeding device, and is used to prevent coal lock leakage and recovery; the slag discharge system is used to convert lignite slag W1 into harmless vitreous slag; the cooling water system is used to control the temperature of the gasifier and the slag discharge system; the coal lock gas recovery system is used to remove dust from the crude raw material gas G2 and recover waste heat; the deoxidation device is used to remove organic sulfur and residual O2 from the crude raw material gas G2; the low-temperature methanol cleaning device is used to remove acidic gases from the crude raw material gas G2; the deep cold separation device is used to separate H2 from the crude raw material gas G2 and obtain high-purity CO gas G3.

[0018] Furthermore, the ratio of lignite to limestone in the mixture is 1:0.052.

[0019] Furthermore, the cooling water system includes a quenching water flow and a multi-purpose water flow. The water inlet temperature of the quenching water flow is 30-40°C, and the water temperature after passing through the quenching chamber is 40-60°C; the multi-purpose water flow is closed to cool the jacket of the gasifier.

[0020] Furthermore, the dust removal and heat recovery system adopts one or more of a cyclone separator, a metal filter, an electrostatic precipitator, a wet dust removal, and a dry dust removal.

[0021] Furthermore, the deoxygenation device includes a hydroconversion reactor and a catalytic reactor. The hydroconversion reactor removes organic sulfur from the raw material gas G2 at a pressure of 2.2-3.2 MPa and 180-250° C., and converts residual O2 under the action of a deoxygenator.

[0022] Furthermore, the deoxidizer is any one of aluminum-based platinum sulfide or iron-based deoxidizer.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention utilizes the CO2 captured from the flue gas emitted by enterprises to generate high-purity CO and apply it to industrial production, making a great contribution to CO2 emission reduction and effectively preventing the greenhouse effect. At the same time, it saves energy, has low cost and high purity, and has broad application prospects.

[0025] (2) The core process of the present invention does not require the use of expensive catalysts. The raw materials used are mainly blue carbon, and the thermochemical autocatalytic effect is achieved under high temperature (1600-2000°C) and high pressure (>3.5MPa), which greatly increases the CO content in the raw gas (>90%) with low cost. The purity of the final generated CO is as high as 99.5% or more, which is of high purity and can be directly used in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : It is a schematic diagram of the system structure required for the process of the present invention;

[0027] In the figure: 1-gasification agent air intake system; 2-feeding device; 3-gasification furnace; 4-coal lock gas recovery system; 5-slag discharge system; 6-cooling water system; 7-dust removal and heat recovery system; 8-deoxygenation device; 9-low-temperature methanol cleaning device; 10-deep cooling separation device. DETAILED DESCRIPTION

[0028] The present invention is further explained below in conjunction with the examples and drawings. The following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] like Figure 1 As shown, a process for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources includes the following steps:

[0030] S1. CO2 captured from the flue gas emitted by the enterprise and O2 separated from the air are mixed to obtain the gasification agent G1;

[0031] S2. The gasifying agent G1 obtained in step S1 enters the gasifier through the gasifying agent air intake system through the lower part, and contacts with the mixed material entering from the upper part in countercurrent to produce a thermochemical reaction; the core reaction temperature is 1600-2000°C, and the pressure reaches above 3.5MPa; the gasifying agent G1 is converted into a crude raw material gas G2, and blue coke slag W1 is generated; the conversion rate of carbon dioxide in the whole gasification process reaches more than 90%.

[0032] Among them, the CO2 / O2 ratio in the gasifying agent G1 is an important control parameter, which directly affects the core reaction temperature of the slag zone in S2. The CO2 / O2 ratio is determined according to the melting point of blue coke, the activity of blue coke, and the melting characteristics of ash and slag, and is adjusted according to the slag discharge state during the thermal reaction. Preferably, the CO2 / O2 ratio in the gasifying agent G1 is 0.9-1.2.

[0033] Preferably, the CO content in the raw material gas G2 generated in step S2 is >90%.

[0034] S3. The crude raw material gas G2 obtained in step S2 is subjected to deoxygenation, low-temperature methanol washing, and deep-cold separation to obtain high-purity CO gas G3.

[0035] Preferably, the CO content in the high-purity CO gas G3 generated in step S3 is >99.5%.

[0036] Example:

[0037] Step S2, generating the gasifying agent G1 for producing 1000 cubic meters of effective gas (CO) in the raw material gas G2, CO2 and O2 are 248 Nm 3 、269Nm 3 , 558 kg of blue coke is required. After the reaction, the CO content in the generated raw material gas G2 is 94.51%.

[0038] A system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources includes the following devices: a gasifying agent air intake system 1, a feeding device 2, a gasifier 3, a coal lock gas recovery system 4, a slag discharge system 5, a cooling water system 6, a dust removal and heat recovery system 7, a deoxidation device 8, a low-temperature methanol cleaning device 9, and a deep cold separation device 10.

[0039] The gasifying agent air intake system 1 is used to mix CO2 and O2 to obtain the gasifying agent G1. The gasifying agent air intake system 1 includes a CO2 buffer tank, an O2 buffer tank, and a mixed fire-retardant tank. The mixed gasifying agent G1 is sprayed into the gasifying furnace 3 from the bottom of the gasifier through a nozzle for gasification.

[0040] The feeding device 2 is used to mix the blue charcoal and limestone in proportion to form a mixture and then feed it into the gasifier 3. The feeding device 2 includes a feeding lock, and the coal lock gas recovery system 4 is arranged inside the feeding lock to prevent the coal lock from leaking and the recovery system. The feeding method of the feeding lock is intermittent automatic feeding. Preferably, the ratio of blue charcoal to limestone is 1:0.052, the feeding frequency is 3-6 times / hour, and the particle size is 6-12mm.

[0041] The gasifier 3 is used to convert the gasifier G1 into a crude raw material gas G2. The gasifier 3 includes a drying layer, a retorting layer, a reducing layer, an oxidation layer, and a slag layer from the upper part to the lower part of the furnace body. The gasifier G1 is introduced into the slag zone from the lower part of the gasifier, reacts upward in sequence, and forms a crude raw material gas G2 before entering the subsequent CO dust removal and heat recovery system 7. The mixed material enters the drying layer from the upper part of the gasifier 3, contacts the gasifier G1 in countercurrent, and reacts downward in sequence;

[0042] Among them, the slag layer is the area with the strongest reaction in the gasifier 3. The pressure and resistance of the drying layer, retorting layer, reduction layer, oxidation layer, and slag layer need to be controlled at 40-48Kpa. Preferably, in order to achieve liquid slag discharge, improve gasification intensity, and reduce consumption, the reaction temperature of the slag layer is 1600-2000℃, and the CO2 / O2 ratio is 0.9-1.2; the oxidation layer is the main area where the oxidation reaction occurs. Preferably, the reaction temperature of the oxidation layer is 1100-1600℃; the reduction layer is the main gasification area where CO is produced. Preferably, the reaction temperature of the reduction layer is 900-1600℃; the retorting layer is the area of ​​pyrolysis reaction and gas conversion. Preferably, the reaction temperature of the retorting layer is 700-900℃; the drying layer is the area where the feed blue charcoal is dried using the waste heat of CO to reduce residual water vapor. Preferably, the reaction temperature of the drying layer is 400-700℃.

[0043] The slag discharge system 5 is used to convert the lignite slag W1 into harmless vitreous slag, and the slag discharge system 5 includes a slag support combustion chamber, a quenching chamber and a slag collecting tank; wherein, the slag support combustion chamber is used to maintain the slag discharge port of the gasification furnace in a high temperature state to ensure that the lignite slag W1 has good fluidity; the quenching chamber is used to convert the slag into harmless vitreous slag; and the slag collecting tank is used to collect the shaped vitreous slag.

[0044] The cooling water system 6 is used to control the temperature of the gasifier 3 and the slag discharge system 5. The cooling water system 6 includes a quenching water process and a multi-purpose water process; wherein, the quenching water process is used to ensure that the quenching chamber is at a low temperature to prevent water vapor from ascending and affecting the CO content in the raw material gas G2; the multi-purpose water process is closed to cool the jacket of the gasifier 3, that is, the gasifier 3 is a double-layer pressure vessel, the outer interlayer is a thick-walled pressure shell, and the inner interlayer is relatively thin. Boiler water is injected between the two interlayers to keep it at about the boiling point temperature under the operating pressure to cool the inner wall of the gasifier and protect the inner wall of the gasifier. Preferably, the water inlet temperature of the quenching water process is 30-40°C, the water temperature after passing through the quenching chamber is 40-60°C, and the water replenishment amount is controlled at 1%.

[0045] The dust removal and heat recovery system 7 is used to remove dust from the raw material gas G2 and recover the remaining heat. The dust removal and heat recovery system 7 can be one or more of a cyclone separator, a metal filter, an electrostatic precipitator, a wet dust removal, and a dry dust removal. Preferably, the dust concentration in the raw material gas G2 is reduced to 5 mg / Nm 3 The heat recovery rate of crude raw gas G2 is 120-300 kJ / m 3 .

[0046] Preferably, the dust removal and heat recovery system 7 includes a scrubber cooler and a tar separator. The high-temperature (200-700°C) raw material gas G2 quickly enters the scrubber cooler after leaving the upper part of the gasifier 3. The raw gas is washed by circulating gas water in the gasification process to cool and wash the raw gas. A strong mass transfer and heat transfer reaction occurs, and the gas is cooled to about 180°C. The raw material gas G2 is saturated with water in the scrubber cooler, and most of the phenol, fatty acid, ammonia and part of the hydrogen sulfide are dissolved in the liquid. The entrained dust is also washed out, and the high-boiling point components in the tar are present in the condensate of the raw material gas. The multiphase fluid from the scrubber cooler enters the sump of the waste heat boiler, and the gas is cooled in the waste heat boiler to generate low-pressure steam. The water and hydrocarbons in the raw material gas are further condensed, and the condensate and dust deposited in the sump of the waste heat boiler enter the gas-water separation unit. After the droplets of the raw material gas are separated by the centrifugal liquid separator, the gas enters the tar separator.

[0047] The tar separator is used to further separate dust and tar from the above-mentioned gas. The raw gas enters the center of the tar separator and flows radially to the first sedimentation zone. In this zone, dust and most of the heavy tar are deposited at the conical bottom of the separator. The conical bottom of the separator is equipped with a scraper to prevent solids from depositing on the inner wall of the separator. A steam heating coil is welded on the outer wall of the conical bottom of the separator to keep the tar low in viscosity. The tar temperature is maintained between 65-120°C to avoid pipeline blockage or tar cracking. The raw gas water from the first sedimentation zone flows through the annular groove around the separator and enters the second sedimentation zone. The first sedimentation zone and the second sedimentation zone are separated by a conical plate. In the second sedimentation zone, the gas water returns radially to the central zone of the separator, enters the fixed overflow device around the central pipe of the separator, and flows to the oil separator under the action of gravity. The tar separated in the second sedimentation zone is discharged to the bottom of the separator through pipes equidistant around the conical plate, and the separated gas enters the next process.

[0048] The deoxygenation device 8 is used to remove organic sulfur and residual O2 in the raw material gas G2. The deoxygenation device 8 includes a hydroconversion reactor and a catalytic reactor. Preferably, the hydroconversion reactor removes organic sulfur in the raw material gas G2 at a pressure of 2.2-3.2 MPa and a temperature of 180-250° C., and converts the residual O2 under the action of a deoxidizer.

[0049] More preferably, the deoxidizer can be any one of aluminum-based platinum sulfide or iron-based deoxidizer. The iron-based deoxidizer includes 50%-60% reduced iron powder, 0.5%-2% activated carbon, 8%-12% electrolyte, and 11-18% highly absorbent resin.

[0050] Preferably, the O2 concentration at the outlet of the deoxygenation device 8 is as low as below 1 ppm, and the carbonyl sulfide concentration is as low as below 10 ppm.

[0051] The low-temperature methanol cleaning device 9 is used to remove acidic gases. The low-temperature methanol cleaning device 9 uses a physical absorption method to remove acidic gases with cold methanol as a solvent, mainly separating CO2 and H2S in the raw coal gas, and the purified gas is mainly CO and H2. Preferably, the sulfur-rich methanol segmented coil heating and decompression technology is adopted to increase the sulfur content in the sulfur-rich methanol, reduce the flow of the concentrated stream from the hot zone, and reduce the system cooling consumption.

[0052] The cryogenic separation device 10 is connected to the low-temperature methanol cleaning device 9 and is used to separate CO and H2 to obtain high-purity CO gas G3.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources, characterized in that: The steps include: S1. Mixing the captured CO2 and the O2 from the air separation to obtain the gasification agent G1; S2. The gasifying agent G1 obtained in step S1 enters the gasifier from the gasifying agent intake system through the lower part, and contacts with the mixed material entering from the upper part in countercurrent to produce a thermochemical reaction; the core reaction temperature is 1600-2000°C, and the pressure reaches above 3.5MPa; the gasifying agent G1 is converted into a crude raw material gas G2, and a blue coke slag W1 is generated; S3. The crude raw material gas G2 obtained in step S2 is subjected to deoxygenation, low-temperature methanol washing, and deep-cold separation to obtain high-purity CO gas G3.

2. A process for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 1, characterized in that: The CO2 / O2 ratio in the gasifying agent G1 is 0.9-1.

2.

3. The process for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 1 is characterized in that: In step S2, the CO content in the generated raw material gas G2 is >90%.

4. The process for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 1, characterized in that: In step S3, the CO content in the generated high-purity CO gas G3 is >99.5%.

5. A system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources, characterized in that: include: The gasifying agent intake system is used to mix CO2 and O2 to obtain the gasifying agent G1, and spray it into the gasifier; The feeding device is used to mix the blue coal and limestone in proportion to form a mixed material, and feed the mixed material into the gasifier; The gasifier is used to convert the gasifying agent G1 into a raw material gas G2; The coal lock gas recovery system is arranged in the feeding lock of the feeding device and is used to prevent gas leakage and recovery in the coal lock; The slag discharge system is used to convert the blue coke slag W1 into harmless vitreous slag; The cooling water system is used to control the temperature of the gasifier and the slag discharge system; The coal lock gas recovery system is used to remove dust from the raw material gas G2 and recover waste heat; The deoxidation device is used to remove organic sulfur and residual O2 from the raw material gas G2; The low-temperature methanol cleaning device is used to remove acidic gases from the crude raw material gas G2; The cryogenic separation device is used to separate H2 from the crude raw material gas G2 and obtain high-purity CO gas G3.

6. The system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 5 is characterized in that: The ratio of blue coke to limestone in the mixture is 1:0.

052.

7. The system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 5 is characterized in that: The cooling water system includes a quenching water flow and a multi-purpose water flow. The water inlet temperature of the quenching water flow is 30-40°C, and the water temperature after passing through the quenching chamber is 40-60°C; the multi-purpose water flow is closed to cool the jacket of the gasifier.

8. The system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 5 is characterized in that: The dust removal and heat recovery system adopts one or more of a cyclone separator, a metal filter, an electrostatic precipitator, a wet dust removal, and a dry dust removal.

9. The system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 5, characterized in that: The deoxygenation device includes a hydroconversion reactor and a catalytic reactor. The hydroconversion reactor removes organic sulfur from the raw material gas G2 at a pressure of 2.2-3.2 MPa and 180-250° C., and converts the residual O2 under the action of a deoxidizer.

10. The system for synthesizing high-purity industrial raw gas carbon monoxide from carbon dioxide resources according to claim 9, characterized in that: The deoxidizer is any one of aluminum-based platinum sulfide or iron-based deoxidizer.

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