Device and method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide

Abstract

The invention discloses a device and method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide, and the method comprises the following steps: flue gas from a thermal power plant is desulfurized and dedusted through an alkaline washing tower, and then is introduced into an absorption tower through an induced draft fan, carbon dioxide is absorbed by an organic alcohol amine solution, a rich solution is introduced into a desorption tower through a lean-rich solution heat exchanger and an amine solution heater, and the desorption tower is used for desorption; the regenerated gas in the desorption tower is subjected to condensate drainage and molecular sieve adsorption from the tower top to obtain industrial-grade gaseous carbon dioxide. Part of impurities are emptied through two-stage compression condensation and a gas-liquid separator, and food-grade liquid carbon dioxide is obtained. Food-grade liquid carbon dioxide is used as a raw material and is rectified by a heavy component removal high-pressure tower and a light component removal low-pressure tower to obtain the electronic-grade liquid carbon dioxide. According to the invention, the processes of carbon capture, compression condensation and low-temperature rectification are combined, the production efficiency is improved, the whole process optimization is realized, the system operation is stable, the energy is saved, the consumption is reduced, the product gas purity is high, and the recovery rate is high.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas capture and carbon dioxide purification, and specifically relates to a device and method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide. Background Art

[0002] Carbon capture, recovery and utilization technology can not only slow down climate deterioration, but also use the captured carbon dioxide as a product for daily life. It has a wide range of uses: in addition to being used as industrial chemicals and protective gases, liquid carbon dioxide can be used as a refrigerant, food-grade carbon dioxide can be used as carbonated beverage dry ice, etc., and higher purity (electronic grade) carbon dioxide is mainly used in the electronics industry, reactor gas cooling, critical extraction in medicine, supercritical cleaning, semiconductor manufacturing and other fields. At present, the domestic production of industrial-grade and food-grade carbon dioxide is mainly faced with problems such as low efficiency, complex process and high energy consumption. It is necessary to continuously upgrade and innovate technology to improve production efficiency and reduce energy consumption. The production scale of electronic-grade carbon dioxide is small, the production cost is high, and it mainly relies on imports, which inhibits the development of related industries. Therefore, it is necessary to design a large-scale industrial-grade, food-grade and electronic-grade carbon dioxide co-production process and device to solve the above problems. Summary of the invention

[0003] The object of the present invention is to provide a device and method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide, so as to solve the problems of low efficiency, complex process and high energy consumption in the production of industrial-grade and food-grade carbon dioxide and small production scale, high production cost and high energy consumption of electronic-grade carbon dioxide.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A device for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide, characterized in that it comprises an alkali washing tower, a condenser after alkali washing, an absorption tower, an organic alcohol amine solution spray unit, an amine liquid heater, a desorption tower, a cooler, a molecular sieve adsorber, a gaseous industrial-grade carbon dioxide storage tank, a compression condensation unit, a liquid food-grade carbon dioxide storage tank, a de-heavy high-pressure tower, a de-heavy condenser after alkali washing, a de-light low-pressure tower and a liquid electronic-grade carbon dioxide storage tank, wherein the front end of the alkali washing tower is connected to the flue of a thermal power plant, the top of the alkali washing tower is connected to the condenser after alkali washing, and the condenser after alkali washing is used to remove gas The sulfur element in the body, after alkali washing, the condenser is connected to the front end of the absorption tower, the organic alcohol amine solution spray unit is connected to the top of the absorption tower, which is used to spray the organic alcohol amine solution into the absorption tower, and the organic alcohol amine solution absorbs the carbon dioxide in the absorption tower to form a rich liquid, the bottom of the absorption tower is connected to the amine liquid heater, the amine liquid heater is used to heat the rich liquid, the amine liquid heater is connected to the desorption tower, the rich liquid is desorbed into lean liquid and carbon dioxide gas in the desorption tower, the bottom of the desorption tower is connected to the absorption tower, the lean liquid is passed into the absorption tower, the top of the desorption tower is connected to the cooler, the cooler is used to Gas cooling, preliminarily removing moisture from the carbon dioxide gas, the cooler is connected to a molecular sieve adsorber, the molecular sieve adsorber is used to further remove moisture and impurities from the carbon dioxide gas to obtain industrial-grade gaseous carbon dioxide, the molecular sieve adsorber is connected to a gaseous industrial-grade carbon dioxide storage tank; the molecular sieve adsorber is also connected to a compression and condensation unit, the compression and condensation unit is used to compress and condense the industrial-grade gaseous carbon dioxide and empty some impurities to obtain food-grade liquid carbon dioxide, the compression and condensation unit is connected to a liquid food-grade carbon dioxide storage tank, the liquid food-grade carbon dioxide storage tank, the compression and condensation unit is also connected to the front end of a de-heavy high-pressure tower, the de-heavy high-pressure tower is used to de-heavy the food-grade liquid carbon dioxide, the heavy component is extracted from the bottom of the de-heavy high-pressure tower, the top is connected to the de-heavy high-pressure tower and the post-heavy condenser, the post-heavy condenser is used to condense the de-heavy food-grade liquid carbon dioxide, the post-heavy condenser is connected to the light-removal low-pressure tower, the light-removal low-pressure tower is used to de-lighten the food-grade liquid carbon dioxide after de-heavy, the light component is extracted from the top of the light-removal low-pressure tower, and the electronic-grade liquid carbon dioxide is obtained at the bottom of the light-removal low-pressure tower.

[0006] To optimize the above technical solutions, the specific measures taken also include:

[0007] The above-mentioned alkali washing tower is equipped with an alkali liquid spraying unit, which includes an alkali liquid tank and an alkali liquid pump. The alkali liquid tank contains alkali liquid, and the alkali liquid pump is used to pump the alkali liquid in the alkali liquid tank to the top of the alkali washing tower.

[0008] The above-mentioned organic alcohol amine solution spraying unit comprises an ammonia liquid tank and an ammonia liquid pump. The ammonia liquid tank contains the organic alcohol amine solution. The ammonia liquid pump is used to pump the organic alcohol amine solution in the ammonia liquid tank to the top of the absorption tower.

[0009] The bottom of the above-mentioned absorption tower is connected to the amine liquid heater through a rich liquid pipeline, and a rich liquid delivery pump and a lean-rich liquid heat exchanger are installed on the rich liquid pipeline. The bottom of the desorption tower is connected to the top of the absorption tower through a lean liquid pipeline, and a lean liquid delivery pump, a lean-rich liquid heat exchanger and a lean liquid cooler are installed on the lean liquid pipeline. The rich liquid pipeline and the lean liquid pipeline exchange heat at the lean-rich liquid heat exchanger.

[0010] The above-mentioned compression and condensing unit is a two-stage compression and condensing structure, including a primary compressor, a primary condenser, a primary gas-liquid separator, a secondary compressor, a secondary condenser and a secondary gas-liquid separator. The front end of the primary compressor is connected to the molecular sieve adsorber, and the rear end of the primary compressor is connected to the primary condenser. The primary condenser is connected to the primary gas-liquid separator. The primary compressor is used to compress industrial-grade gaseous carbon dioxide. The primary condenser is used to condense the compressed industrial-grade gaseous carbon dioxide. The primary gas-liquid separator is used to separate the gas and liquid of the condensed industrial-grade gaseous carbon dioxide. The primary gas-liquid separator is connected to the secondary compressor, the secondary compressor is connected to the secondary condenser, and the secondary condenser is connected to the secondary gas-liquid separator. The secondary compressor, the secondary condenser and the secondary gas-liquid separator are respectively used to compress, condense and gas-liquid separate the industrial-grade gaseous carbon dioxide after the primary separation. The industrial-grade gaseous carbon dioxide after the secondary gas-liquid separation is food-grade liquid carbon dioxide.

[0011] A method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide, using the above-mentioned co-producing industrial-grade, food-grade and electronic-grade carbon dioxide device, specifically comprising the following steps:

[0012] Step 1: The flue gas of the thermal power plant continuously enters the alkali washing tower, and the flue gas is extracted from the top of the alkali washing tower. After the alkali washing, the sulfur element is removed by the condenser, and then the flue gas is passed into the absorption tower through the induced draft fan;

[0013] Step 2: Spraying an organic alcohol amine solution on the top of the absorption tower to absorb carbon dioxide to form a rich liquid. The rich liquid is extracted from the bottom of the absorption tower and passed through a lean-rich liquid heat exchanger and an amine liquid heater before entering a desorption tower. The lean liquid produced by the desorption tower is extracted from the bottom of the desorption tower and passed through a lean-rich liquid heat exchanger and a lean liquid cooler before entering the absorption tower for recycling. The carbon dioxide is desorbed and extracted from the top of the desorption tower;

[0014] Step 3: After the carbon dioxide is extracted from the top of the desorption tower, it is cooled in a cooler to discharge excess water, and then further dehydrated and impurized by a molecular sieve adsorber to obtain industrial-grade gaseous carbon dioxide, which enters a compression condensation unit;

[0015] Step 4: The compression and condensation unit performs primary and secondary compression and condensation on the industrial-grade gaseous carbon dioxide and exhausts some impurities to obtain food-grade liquid carbon dioxide. Part of the food-grade liquid carbon dioxide is introduced into a dry ice machine, and the rest is introduced into a de-weighting high-pressure tower through a first distillation pump;

[0016] Step 5: Liquid food-grade carbon dioxide is extracted from the bottom of the de-heavy high-pressure tower to obtain heavy components, and the rest is condensed in the post-heavy condenser from the top of the de-heavy high-pressure tower, and then passed into the light-removal low-pressure tower through the second distillation pump;

[0017] Step 6: The liquid food-grade carbon dioxide after de-heavy treatment is passed through the top of the light-removal low-pressure tower to extract the light component, and electronic-grade liquid carbon dioxide is obtained at the bottom of the tower.

[0018] The purity of carbon dioxide in flue gas from thermal power plants is 10% to 90%, and the flue gas temperature is 20 to 80°C.

[0019] The top of the alkaline washing tower is sprayed with sodium hydroxide solution to desulfurize and remove dust from the flue gas.

[0020] The operating pressure of the absorption tower is 1.5-3.5MPa, and when the rich liquid flows through the lean and rich liquid heat exchanger, the temperature difference of the heat exchanger is 5-20°C; the heating temperature of the amine liquid heater is 95-135°C; the operating pressure of the desorption tower is 0.1-0.2MPa, and the tower bottom temperature is 90-120°C; the cooling temperature of the cooler is 15-28°C. In step 4, the pressure after the first-stage compression is 0.4-1.0MPa, and the first-stage cooling temperature is -45--65°C; the pressure after the second-stage compression is 1.6-2.5MPa, and the second-stage cooling temperature is -15--35°C. The operating pressure of the de-heavy high-pressure tower is 1.5-4.0MPa, and the operating temperature is -10--25°C. The cooling temperature of the condenser after de-heavy is -20--35°C, and the operating pressure of the light-removal low-pressure tower is 1.0-3.0MPa, and the operating temperature is -20--35°C.

[0021] The purity of industrial-grade gaseous carbon dioxide is 99%, the purity of food-grade liquid carbon dioxide is 99.9%, and the purity of electronic-grade liquid carbon dioxide is 99.9999%.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The process designed by the present invention integrates three parts: carbon capture, pressurized condensation, and double-tower cryogenic distillation, realizing the optimization of the entire process from raw gas capture to product purification in thermal power plants. The product has high purity, the process technology is simple and mature, and the overall production efficiency and product quality are improved.

[0024] 2. The industrial-grade carbon dioxide produced by the present invention adopts a chemical absorption method, which can be applied to a variety of industrial emission sources, and the purity can be effectively improved, which is conducive to the utilization of subsequent products, such as the production of food-grade carbon dioxide, the preparation of chemical raw materials, etc.

[0025] 3. Using the above industrial-grade carbon dioxide as raw material, the impurities and water therein are adsorbed and separated by molecular sieves, and then through two-stage pressurized condensation, the pressure and temperature can be precisely controlled to achieve the discharge of some impurities, and liquid food-grade carbon dioxide can be obtained. The process equipment has a reasonable structure, energy saving and consumption reduction, easy operation, and stable operation.

[0026] 4. The above-mentioned liquid food-grade carbon dioxide is used as raw material and further purified through double-tower distillation to obtain liquid electronic-grade carbon dioxide with a purity of up to 6N level. In the double-tower distillation process, the cold source required in the carbon dioxide liquefaction step can be utilized, thereby optimizing the inherent process of the carbon dioxide distillation and purification configuration refrigeration device, achieving full utilization of resources, energy saving and consumption reduction, and significantly reducing the operating cost of producing electronic-grade carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] The accompanying drawings are marked as follows: alkali washing tower 11, absorption tower 12, desorption tower 13, de-heavy high-pressure tower 14, de-light low-pressure tower 15, alkali washing post-condenser 21, lean-rich liquid heat exchanger 22, lean liquid cooler 23, cooler 24, primary condenser 25, secondary condenser 26, de-heavy condenser 27, delivery pump 31, rich liquid delivery pump 32, lean liquid delivery pump 33, first distillation pump 34, second distillation pump 35, amine liquid heater 41, molecular sieve adsorber 51, primary compressor 61, secondary compressor 62, gaseous industrial-grade carbon dioxide storage tank 71, primary gas-liquid separator 72, secondary gas-liquid separator 73, liquid food-grade carbon dioxide storage tank 74, liquid electronic-grade carbon dioxide storage tank 75. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0030] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0031] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0032] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0033] Example 1: Production of industrial-grade carbon dioxide

[0034] The flue gas of the thermal power plant continuously enters the alkali washing tower 11, and the alkali washing tower is sprayed with sodium hydroxide solution. The flue gas is extracted from the top of the tower and passes through the condenser 21 after alkali washing to remove sulfur elements, and then passes into the absorption tower 12 through the induced draft fan. The operating pressure of the absorption tower is 1.5-3.5MPa. The organic alcohol amine solution is sprayed on the top of the tower to absorb carbon dioxide to form rich liquid. The rich liquid is extracted from the bottom of the tower and heated to 95-135°C by the lean-rich liquid heat exchanger 22 and the amine liquid heater 41, and then passed into the desorption tower 13. The operating pressure of the desorption tower is 0.1-0.2MPa. The lean liquid is extracted from the bottom of the desorption tower and cooled to 15-45°C by the lean-rich liquid heat exchanger 22 and the lean liquid cooler 23, and then passed into the absorption tower for recycling. After being desorbed, the carbon dioxide is extracted from the top of the tower, cooled to 15-28°C by the cooler 24 to discharge excess water, and then further dehydrated and impurized by the molecular sieve adsorber 51 to obtain industrial-grade gaseous carbon dioxide with a purity of 99%. After compression and cooling, industrial-grade liquid carbon dioxide with a purity of 99% is obtained.

[0035] In this embodiment, the purity of the carbon dioxide raw material in the flue gas of the thermal power plant is 10-90%, and the flue gas temperature is 20-80°C;

[0036] In this embodiment, the rich liquid flows out from the bottom of the absorption tower, and the temperature of the rich liquid is 60-100°C.

[0037] In this embodiment, the temperature difference of the lean-rich liquid heat exchanger 22 is 5-20°C.

[0038] In this embodiment, the temperature at the bottom of the desorption tower is 80-135°C.

[0039] Example 2: Industrial-grade and food-grade co-production

[0040] The flue gas of the thermal power plant continuously enters the alkali washing tower 11, and the alkali washing tower is sprayed with sodium hydroxide solution. The flue gas is extracted from the top of the tower and passes through the condenser 21 after alkali washing to remove sulfur elements, and then passes into the absorption tower 12 through the induced draft fan. The operating pressure of the absorption tower is 1.5-3.5MPa. The organic alcohol amine solution is sprayed on the top of the tower to absorb carbon dioxide to form rich liquid. The rich liquid is extracted from the bottom of the tower and heated to 95-135°C by the lean-rich liquid heat exchanger 22 and the amine liquid heater 41, and then passed into the desorption tower 13. The operating pressure of the desorption tower is 0.1-0.2MPa. The lean liquid is extracted from the bottom of the desorption tower and cooled to 15-45°C by the lean-rich liquid heat exchanger 22 and the lean liquid cooler 23, and then passed into the absorption tower for recycling. After desorption, the carbon dioxide is extracted from the top of the tower, cooled to 15-28°C by the cooler 24, and then the excess water is discharged. Then, it is further dehydrated and impurized by the molecular sieve adsorber 51, and an industrial-grade gaseous carbon dioxide with a purity of 99% is obtained, which enters the compression and condensation unit. After two-stage compression and condensation: the pressure after the first stage of compression is 0.4-1.0MPa, and the first stage of cooling temperature is -45--65°C; the pressure after the second stage of compression is 1.6-2.5MPa, and the second stage of cooling temperature is -15--35°C. After some impurities are discharged through the gas-liquid separator, food-grade liquid carbon dioxide with a purity of 99.9% can be obtained.

[0041] In this embodiment, the purity of the carbon dioxide raw material in the flue gas of the thermal power plant is 10-90%, and the flue gas temperature is 20-80°C;

[0042] In this embodiment, the rich liquid flows out from the bottom of the absorption tower, and the temperature of the rich liquid is 60-100°C.

[0043] In this embodiment, the temperature difference of the lean-rich liquid heat exchanger 22 is 5-20°C.

[0044] In this embodiment, the temperature at the bottom of the desorption tower is 80-135°C.

[0045] Example 3: Industrial, food and electronic grade trigeneration

[0046] The flue gas of the thermal power plant continuously enters the alkali washing tower 11, and the alkali washing tower is sprayed with sodium hydroxide solution. The flue gas is extracted from the top of the tower and passes through the condenser 21 after alkali washing to remove sulfur elements, and then passes into the absorption tower 12 through the induced draft fan. The operating pressure of the absorption tower is 1.5-3.5MPa. The organic alcohol amine solution is sprayed on the top of the tower to absorb carbon dioxide to form rich liquid. The rich liquid is extracted from the bottom of the tower and heated to 95-135°C by the lean-rich liquid heat exchanger 22 and the amine liquid heater 41, and then passed into the desorption tower 13. The operating pressure of the desorption tower is 0.1-0.2MPa. The lean liquid is extracted from the bottom of the desorption tower and cooled to 15-45°C by the lean-rich liquid heat exchanger 22 and the lean liquid cooler 23, and then passed into the absorption tower for recycling. After the carbon dioxide is desorbed, it is extracted from the top of the tower, cooled to 15-28°C by the cooler 24, and then the excess water is discharged. Then, it is further dehydrated and impurized by the molecular sieve adsorber 51, and an industrial-grade gaseous carbon dioxide with a purity of 99% is obtained, which enters the compression and condensation unit. After two-stage compression and condensation: the pressure after the first stage of compression is 0.4-1.0MPa, and the first stage cooling temperature is -45--65°C; the pressure after the second stage of compression is 1.6-2.5MPa, and the second stage cooling temperature is -15--35°C. Then, part of the impurities are emptied through the gas-liquid separator, and food-grade liquid carbon dioxide with a purity of 99.9% can be obtained. Part of it is passed into the dry ice machine, and the rest is passed into the double-tower low-temperature distillation unit through the pump 34. The operating pressure of the de-heavy high-pressure tower 14 is 1.5-4.0MPa, and the operating temperature is -10--25°C. The heavy components are extracted from the bottom of the tower, and the top of the tower is condensed to -20--35°C by the condenser 27 after de-heavy, and then passed into the light-removal low-pressure tower. The operating pressure of the light-removal low-pressure tower 15 is 1.0 to 3.0 MPa, and the operating temperature is -20 to -35°C. The light components are extracted from the top of the tower, and electronic grade liquid carbon dioxide with a purity of 99.9999% is obtained at the bottom of the tower.

[0047] In this embodiment, the purity of the carbon dioxide raw material in the flue gas of the thermal power plant is 10-90%, and the flue gas temperature is 20-80°C;

[0048] In this embodiment, the rich liquid flows out from the bottom of the absorption tower, and the temperature of the rich liquid is 60-100°C.

[0049] In this embodiment, the temperature difference of the lean-rich liquid heat exchanger 22 is 5-20°C.

[0050] In this embodiment, the temperature at the bottom of the desorption tower is 80-135°C.

[0051] Example 4: Industrial-grade and electronic-grade co-production

[0052] The flue gas of the thermal power plant continuously enters the alkali washing tower 11, and the alkali washing tower is sprayed with sodium hydroxide solution. The flue gas is extracted from the top of the tower and passes through the condenser 21 after alkali washing to remove sulfur elements, and then passes into the absorption tower 12 through the induced draft fan. The operating pressure of the absorption tower is 1.5-3.5MPa. The organic alcohol amine solution is sprayed on the top of the tower to absorb carbon dioxide to form rich liquid. The rich liquid is extracted from the bottom of the tower and heated to 95-135°C by the lean-rich liquid heat exchanger 22 and the amine liquid heater 41, and then passed into the desorption tower 13. The operating pressure of the desorption tower is 0.1-0.2MPa. The lean liquid is extracted from the bottom of the desorption tower and cooled to 15-45°C by the lean-rich liquid heat exchanger 22 and the lean liquid cooler 23, and then passed into the absorption tower for recycling. After desorption, the carbon dioxide is extracted from the top of the tower, cooled to 15-28°C by the cooler 24, and the excess water is discharged. After further dehydration and impurity removal by the molecular sieve adsorber 51, industrial-grade gaseous carbon dioxide is obtained. After partial compression and cooling, industrial-grade liquid carbon dioxide with a purity of 99% is obtained as an intermediate product, and the remaining part enters the compression and condensation unit. After two-stage compression and condensation: the pressure after the first stage of compression is 0.4-1.0MPa, and the first stage cooling temperature is -45--65°C; the pressure after the second stage of compression is 1.6-2.5MPa, and the second stage cooling temperature is -15--35°C. At this time, the carbon dioxide is liquid and is passed into the double-tower low-temperature distillation unit through the pump 34. The operating pressure of the de-heavy high-pressure tower 14 is 1.5-4.0MPa, and the operating temperature is -10--25°C. The heavy component is extracted from the bottom of the tower, and the top of the tower is condensed to -20--35°C by the condenser 27 after de-heavy removal, and then passed into the light-removal low-pressure tower. The operating pressure of the light-removal low-pressure tower 15 is 1.0 to 3.0 MPa, and the operating temperature is -20 to -35°C. The light components are extracted from the top of the tower, and electronic grade liquid carbon dioxide with a purity of 99.9999% is obtained at the bottom of the tower.

[0053] In this embodiment, the purity of the carbon dioxide raw material in the flue gas of the thermal power plant is 10-90%, and the flue gas temperature is 20-80°C;

[0054] In this embodiment, the rich liquid flows out from the bottom of the absorption tower, and the temperature of the rich liquid is 60-100°C.

[0055] In this embodiment, the temperature difference of the lean-rich liquid heat exchanger 22 is 5-20°C.

[0056] In this embodiment, the temperature at the bottom of the desorption tower is 80-135°C.

[0057] The above are preferred embodiments of the present application, but those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0058] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A device for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide, characterized by: The invention comprises an alkali washing tower (11), an alkali washing post-condenser (21), an absorption tower (12), an organic alcohol amine solution spray unit, an amine liquid heater (41), a desorption tower (13), a cooler (24), a molecular sieve adsorber (51), a gaseous industrial-grade carbon dioxide storage tank (71), a compression condensation unit, a liquid food-grade carbon dioxide storage tank (74), a de-heavy high-pressure tower (14), a de-heavy post-condenser (27), a de-light low-pressure tower (15) and a liquid electronic-grade carbon dioxide storage tank (75), wherein the front end of the alkali washing tower (11) is connected to the flue of a thermal power plant, the top of the alkali washing tower (11) is connected to the alkali washing post-condenser (21), and the alkali washing post-condenser (21) is used to remove sulfur elements in the gas. The condenser (21) is connected to the front end of the absorption tower (12) after alkali washing. The organic alcohol amine solution spraying unit is connected to the top of the absorption tower (12) for spraying the organic alcohol amine solution into the absorption tower (12). The organic alcohol amine solution absorbs the carbon dioxide in the absorption tower (12) to form a rich liquid. The bottom of the absorption tower (12) is connected to an amine liquid heater (41). The amine liquid heater (41) is used to heat the rich liquid. The amine liquid heater (41) is connected to a desorption tower (13). The rich liquid is desorbed into a lean liquid and carbon dioxide gas in the desorption tower (13). The bottom of the desorption tower (13) is connected to the absorption tower (12). The lean liquid is introduced into the absorption tower (12). The top of the desorption tower (13) is connected to a cooler (24). ), the cooler (24) is used to cool the carbon dioxide gas and preliminarily remove moisture from the carbon dioxide gas. The cooler (24) is connected to a molecular sieve adsorber (51), and the molecular sieve adsorber (51) is used to further remove moisture and impurities from the carbon dioxide gas to obtain industrial-grade gaseous carbon dioxide. The molecular sieve adsorber (51) is connected to a gaseous industrial-grade carbon dioxide storage tank (71); the molecular sieve adsorber (51) is also connected to a compression and condensation unit, and the compression and condensation unit is used to compress and condense the industrial-grade gaseous carbon dioxide and exhaust some impurities to obtain food-grade liquid carbon dioxide. The compression and condensation unit is connected to a liquid food-grade carbon dioxide storage tank (74). The food-grade carbon dioxide storage tank (74) and the compression and condensing unit are also connected to the front end of the de-heavy high-pressure tower (14). The de-heavy high-pressure tower (14) is used to de-heavy the food-grade liquid carbon dioxide. The heavy component is extracted from the bottom of the de-heavy high-pressure tower (14). The top of the de-heavy high-pressure tower (14) is connected to a de-heavy post-condenser (27). The de-heavy post-condenser (27) is used to condense the de-heavy food-grade liquid carbon dioxide. The de-heavy post-condenser (27) is connected to a light degassing low-pressure tower (15). The light degassing low-pressure tower (15) is used to de-lighten the food-grade liquid carbon dioxide. The light component is extracted from the top of the light degassing low-pressure tower (15). Electronic-grade liquid carbon dioxide is obtained at the bottom of the light degassing low-pressure tower (15).

2. The device for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 1, characterized in that: The alkali washing tower (11) is equipped with an alkali solution spraying unit, and the alkali solution spraying unit comprises an alkali solution tank and an alkali solution pump. The alkali solution tank contains alkali solution, and the alkali solution pump is used to pump the alkali solution in the alkali solution tank to the top of the alkali washing tower (11).

3. The device for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 2, characterized in that: The organic alcohol amine solution spraying unit comprises an ammonia liquid tank and an ammonia liquid pump. The ammonia liquid tank contains the organic alcohol amine solution. The ammonia liquid pump is used to pump the organic alcohol amine solution in the ammonia liquid tank to the top of the absorption tower (12).

4. The device for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 3 is characterized by: The bottom of the absorption tower (12) is connected to the amine liquid heater (41) via a rich liquid pipeline, and a rich liquid delivery pump (32) and a lean-rich liquid heat exchanger (22) are installed on the rich liquid pipeline. The bottom of the desorption tower (13) is connected to the top of the absorption tower (12) via a lean liquid pipeline, and a lean liquid delivery pump (33), a lean-rich liquid heat exchanger (22) and a lean liquid cooler (23) are installed on the lean liquid pipeline. The rich liquid pipeline and the lean liquid pipeline exchange heat at the lean-rich liquid heat exchanger (22).

5. The device for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 4, characterized in that: The compression condensation unit is a two-stage compression condensation structure, comprising a primary compressor (61), a primary condenser (25), a primary gas-liquid separator (72), a secondary compressor (62), a secondary condenser (26) and a secondary gas-liquid separator (73), wherein the front end of the primary compressor (61) is connected to the molecular sieve adsorber (51), the rear end of the primary compressor (61) is connected to the primary condenser (25), the primary condenser (25) is connected to the primary gas-liquid separator (72), the primary compressor (61) is used to compress industrial-grade gaseous carbon dioxide, and the primary condenser (25) is used to compress the compressed industrial-grade gaseous carbon dioxide. The first-level gaseous carbon dioxide is condensed, and the first-level gas-liquid separator (72) is used to separate the condensed industrial-grade gaseous carbon dioxide into gas and liquid. The first-level gas-liquid separator (72) is connected to the second-level compressor (62), the second-level compressor (62) is connected to the second-level condenser (26), the second-level condenser (26) is connected to the second-level gas-liquid separator (73), the second-level compressor (62), the second-level condenser (26) and the second-level gas-liquid separator (73) are respectively used to compress, condense and separate the gas and liquid of the industrial-grade gaseous carbon dioxide after the first-level separation, and the industrial-grade gaseous carbon dioxide after the second-level gas-liquid separation is food-grade liquid carbon dioxide.

6. A method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide, using the co-producing industrial-grade, food-grade and electronic-grade carbon dioxide device as claimed in claim 4, specifically comprising the following steps: Step 1: Flue gas from a thermal power plant continuously enters an alkali washing tower (11), the flue gas is extracted from the top of the alkali washing tower (11), the sulfur element is removed by a condenser (21) after alkali washing, and then the flue gas is passed into an absorption tower (12) through an induced draft fan; Step 2: spraying an organic alcohol amine solution on the top of the absorption tower (12) to absorb carbon dioxide to form a rich liquid; the rich liquid is extracted from the bottom of the absorption tower (12), passes through a lean-rich liquid heat exchanger (22) and an amine liquid heater (41), and then is introduced into a desorption tower (13); the lean liquid produced by the desorption tower (13) is extracted from the bottom of the desorption tower (13), passes through a lean-rich liquid heat exchanger (22) and a lean liquid cooler (23), and then is introduced into the absorption tower (12) for recycling; and the carbon dioxide is desorbed and extracted from the top of the desorption tower (13); Step 3: After the carbon dioxide is extracted from the top of the desorption tower (13), it is cooled in a cooler (24) to discharge excess water, and then further dehydrated and impurized by a molecular sieve adsorber (51) to obtain industrial-grade gaseous carbon dioxide, which enters a compression condensation unit; Step 4: The compression and condensation unit performs primary and secondary compression and condensation on the industrial-grade gaseous carbon dioxide and exhausts some impurities to obtain food-grade liquid carbon dioxide. Part of the food-grade liquid carbon dioxide is passed into a dry ice machine, and the rest is passed into a deweighting high-pressure tower (14) via a first distillation pump (34); Step 5: Liquid food-grade carbon dioxide is extracted from the bottom of the de-heavy high-pressure tower (14) to remove the heavy component, and the remaining part enters the de-heavy post-condenser (27) from the top of the de-heavy high-pressure tower (14) for condensation, and then passes through the second distillation pump (35) into the de-light low-pressure tower (15); Step 6: The liquid food-grade carbon dioxide after degassing is passed through a light-removing low-pressure tower (15) to extract the light components from the top of the tower, and obtain electronic-grade liquid carbon dioxide at the bottom of the tower.

7. The method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 6, characterized in that: The purity of carbon dioxide in the flue gas of the thermal power plant is 10% to 90%, and the flue gas temperature is 20 to 80°C.

8. The method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 6, characterized in that: The top of the alkali washing tower (11) is sprayed with sodium hydroxide solution to desulfurize and remove dust from the flue gas.

9. The method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 6, characterized in that: The operating pressure of the absorption tower (12) is 1.5-3.5 MPa. When the rich liquid flows through the lean-rich liquid heat exchanger (22), the temperature difference of the heat exchanger is 5-20°C. The heating temperature of the amine liquid heater (41) is 95-135°C. The operating pressure of the desorption tower (13) is 0.1-0.2 MPa, and the tower bottom temperature is 90-120°C. The cooling temperature of the cooler (24) is 15-28°C. In step 4, the pressure after the first-stage compression is 0.4-1.0 MPa. The primary cooling temperature is -45 to -65°C; the pressure after the secondary compression is 1.6 to 2.5 MPa, the secondary cooling temperature is -15 to -35°C, the operating pressure of the de-heavy high-pressure tower (14) is 1.5 to 4.0 MPa, and the operating temperature is -10 to -25°C. The cooling temperature of the condenser (27) after de-heavy removal is -20 to -35°C, and the operating pressure of the de-light low-pressure tower (15) is 1.0 to 3.0 MPa, and the operating temperature is -20 to -35°C.

10. The method for co-producing industrial-grade, food-grade and electronic-grade carbon dioxide according to claim 6, characterized in that: The purity of industrial-grade gaseous carbon dioxide is 99%, the purity of food-grade liquid carbon dioxide is 99.9%, and the purity of electronic-grade liquid carbon dioxide is 99.9999%.

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