Device and method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas

Abstract

The invention belongs to the technical field of chemical process tail gas treatment, and particularly relates to a hydrogen-containing tail gas and carbon dioxide tail gas utilization device. In order to improve the utilization efficiency of hydrogen-containing tail gas and carbon dioxide tail gas and reduce the problems of environmental pollution and the like, the hydrogen-containing tail gas, the carbon dioxide tail gas and coke oven gas are introduced into an adsorption tower, and adsorbed raw material gas enters a pre-hydrogenation reactor through a supercharger, a first separator and a feeding and discharging heat exchanger; after hydrogenation reaction, the gas passes through a first-stage hydrogenation reactor, a medium-temperature desulfurization reactor, a second-stage hydrogenation reactor, a fine desulfurization reactor and a feeding and discharging heat exchanger, after heat exchange, the gas is condensed by a water cooler and separated by a second separator, the gas enters a carbon dioxide removal tower for further purification, the purified gas enters a cryogenic separation device, and liquid methane is separated out; the tail gas utilization value is improved, economic benefits are increased, and carbon dioxide emission is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical process tail gas treatment, and particularly relates to a device for utilizing hydrogen-containing tail gas and carbon dioxide tail gas. Background Art

[0002] Currently, in the syngas-to-ethylene glycol co-producing LNG device, the main components of the tail gas generated in the ethylene glycol synthesis process are hydrogen and part of nitrogen. Among them, the hydrogen concentration is 95% - 98%, and the remaining components are mainly inert gases such as nitrogen and argon. The tail gas generated in the carbon dioxide removal process is mainly carbon dioxide, etc., and the carbon dioxide concentration is 95% - 99%. Currently, the main utilization methods of these two gas streams are as follows: The ethylene glycol synthesis tail gas is sent to the incinerator for combustion, or after being purified by a pressure swing adsorption hydrogen purification device, it is returned to the synthesis system for utilization. The utilization method of the carbon dioxide tail gas is to be sent to the chimney and directly discharged into the atmospheric environment.

[0003] The utilization methods of these two gases mainly have the following problems: 1) The process method of sending the ethylene glycol synthesis tail gas to the incinerator for combustion will cause environmental pollution and an increase in carbon dioxide emissions. Especially in the later stage of catalyst use, when the side reactions of the synthesis device increase and the discharged purge gas volume increases, part of the gas is directly discharged to the flare system, causing serious pollution. 2) The hydrogen concentration in the ethylene glycol synthesis tail gas is high, and sending it to the incinerator for combustion will result in low energy utilization efficiency and is not conducive to energy conservation. 3) The process method of returning the ethylene glycol synthesis tail gas to the synthesis device after being purified by pressure swing adsorption has the problem that impurities such as alcohols and esters in the synthesis tail gas are easily re-introduced into the system, causing catalyst coking and a decrease in the production efficiency of the synthesis device. 4) Directly discharging the carbon dioxide tail gas into the atmospheric environment causes problems such as air pollution and an increase in carbon emissions. Summary of the Invention

[0004] In view of the above problems, the present invention provides a device for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to the process parameters and process flow characteristics of the two gases.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a device for utilizing hydrogen-containing tail gas and carbon dioxide tail gas, including an adsorption tower. The inlet of the adsorption tower is used to introduce the hydrogen-containing tail gas sent by an ethylene glycol synthesis device, the carbon dioxide tail gas sent by a decarbonization process, and coke oven gas. The outlet of the adsorption tower is connected to the inlet of a booster through a pipeline. The outlet of the booster is connected to the inlet of a first separator through a pipeline. The outlet of the first separator is connected to the cold medium inlet of a feed and discharge heat exchanger through a pipeline. The cold medium outlet of the feed and discharge heat exchanger is connected to the inlet of a pre-hydrogenation reactor through a pipeline. The outlet of the pre-hydrogenation reactor is connected to the inlet of a primary hydrogenation reactor through a pipeline. The outlet of the primary hydrogenation reactor is connected to the inlet of a medium-temperature desulfurization reactor through a pipeline. The outlet of the medium-temperature desulfurization reactor is connected to the inlet of a secondary hydrogenation reactor through a pipeline. The outlet of the secondary hydrogenation reactor is connected to the inlet of a fine desulfurization reactor through a pipeline. The outlet of the fine desulfurization reactor is connected to the hot medium inlet of the feed and discharge heat exchanger through a pipeline. The hot medium outlet of the feed and discharge heat exchanger is connected to the hot medium inlet of a water cooler through a pipeline. The hot medium outlet of the water cooler is connected to the inlet of a second separator through a pipeline. The outlet of the second separator is connected to the first inlet of a carbon dioxide removal tower through a pipeline, and the first outlet of the carbon dioxide removal tower is connected to the inlet of a cryogenic separation device for separating out liquid methane. The second inlet of the carbon dioxide removal tower is used to introduce lean MDEA solution, and the second outlet of the carbon dioxide removal tower is used to output rich MDEA solution.

[0007] Furthermore, it also includes a first waste heat recovery device, a second waste heat recovery device, and a third waste heat recovery device. The outlet of the pre-hydrogenation reactor is connected to the hot medium inlet of the first waste heat recovery device through a pipeline, and the hot medium outlet of the first waste heat recovery device is connected to the inlet of the primary hydrogenation reactor through a pipeline. The outlet of the medium-temperature desulfurization reactor is connected to the hot medium inlet of the second waste heat recovery device through a pipeline, and the hot medium outlet of the second waste heat recovery device is connected to the inlet of the secondary hydrogenation reactor through a pipeline. The hot medium outlet of the feed and discharge heat exchanger is connected to the hot medium inlet of the third waste heat recovery device through a pipeline, and the hot medium outlet of the third waste heat recovery device is connected to the hot medium inlet of the water cooler through a pipeline.

[0008] The present invention also provides a method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas, including the following steps:

[0009] Step 1, the hydrogen-containing tail gas sent by the ethylene glycol synthesis device, the carbon dioxide tail gas sent by the decarbonization process, and the coke oven gas are introduced into the adsorption tower. In the adsorption tower, the impurities in the raw gas are removed by the adsorption action of the adsorbent to obtain purified raw gas.

[0010] Step 2: The purified feed gas is sent to a booster compressor to increase the pressure. After the pressure is increased, the feed gas enters the first separator. After separating the moisture in the first separator, it enters the inlet-outlet heat exchanger to increase the temperature.

[0011] Step 3: The feed gas after increasing the temperature enters the pre-hydrogenation reactor, where the feed gas reacts with hydrogen.

[0012] Step 4: The gas after passing through the pre-hydrogenation reactor enters the first waste heat recovery unit. After recovering the reaction heat, it enters the first-stage hydrogenation reactor.

[0013] Step 5: The gas after passing through the first-stage hydrogenation reactor enters the medium-temperature desulfurization reactor. After the sulfide is removed from the feed gas, it enters the second waste heat recovery unit. After recovering the reaction heat, it is sent to the second-stage hydrogenation reactor.

[0014] Step 6: The gas after passing through the second-stage hydrogenation reactor enters the fine desulfurization reactor. After further desulfurization, the gas enters the inlet-outlet heat exchanger. After heat exchange, it is sent to the third waste heat recovery unit. After recovering the reaction heat, it enters the water cooler. After condensation, it is sent to the second separator. After separating the moisture, the gas is sent to the carbon dioxide removal tower. After further purification, the gas is sent to the cryogenic separation unit to separate out liquid methane as the product.

[0015] Furthermore, the process parameters of the hydrogen-containing tail gas in Step 1 are: flow rate 300 - 3000 Nm 3 / h, pressure 2.8 MPa, temperature 35°C - 40°C, hydrogen content 95% - 98%; the process parameters of the carbon dioxide tail gas are: flow rate 100 - 1000 Nm 3 / h, pressure 0.6 MPa, carbon dioxide content 95% - 99%.

[0016] Furthermore, in Step 2, the purified feed gas is sent to a booster compressor to increase the pressure to 3.0 - 3.4 MPa and enters the inlet-outlet heat exchanger to increase the temperature to 220 - 275°C.

[0017] Furthermore, in Step 3, the reaction temperature in the pre-hydrogenation reactor is 290 - 300°C, and the pre-hydrogenation reactor is filled with a catalyst with a nickel content of 3% - 9%.

[0018] Furthermore, in Step 4, the first waste heat recovery unit reduces the temperature to 220 - 260°C. According to the process parameters of the supplemented synthesis tail gas and carbon dioxide tail gas, the reaction temperature in the first-stage hydrogenation reactor is 340 - 380°C. Adjust the first-stage hydrogenation reactor to be filled with a catalyst with a nickel content of 3% - 9% to improve the activity and selectivity of the hydrogenation catalyst.

[0019] Further, in the step 5, the second waste heat recovery device reduces the temperature to 220 - 260°C, the reaction temperature in the secondary hydrogenation reactor is 340 - 390°C, and the hydrogenation catalyst with a nickel content of 3% - 9% is loaded in the secondary hydrogenation reactor.

[0020] Further, in the step 6, the feed - and - discharge heat exchanger reduces the temperature to 230 - 260°C, the third waste heat recovery device reduces the temperature to 160°C, and the water cooler condenses the temperature to 20 - 40°C.

[0021] Furthermore, in order to improve the conversion rates of hydrogen and carbon dioxide in the tail gas and reduce the chemical reaction equilibrium constant, the by - product steam pressure of the first waste heat recovery device, the second waste heat recovery device and the third waste heat recovery device in the present invention is 0.5 - 3.8 MPa. By adjusting the temperature of the raw material gas entering the hydrogenation reactor under different production modes, the economic efficiency of the device is improved.

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

[0023] (1) It reduces the carbon emissions of the high - concentration carbon dioxide tail gas and creates relatively high environmental protection benefits.

[0024] (2) It improves the energy utilization efficiency of the hydrogen - containing tail gas, and this utilization method is more energy - saving. Compared with the traditional combustion utilization method, the resource utilization efficiency is increased by more than 20%. Compared with the pressure swing adsorption purification utilization method, the resource utilization efficiency is increased by more than 10%.

[0025] (3) It reduces the fixed - asset investment. It can be achieved by using the equipment design margin in the original process without additional investment, thus improving the economic efficiency of the device.

[0026] (4) It improves the safety of the device and avoids safety risks such as incomplete combustion, hydrogen escape, burner flash - back and blow - out during the combustion of high - concentration and high - pressure hydrogen - containing tail gas in the incinerator.

[0027] (5) It does not require the construction of a hydrogen - containing tail gas incinerator, reduces a fixed pollution source, avoids pollutant emissions and protects the atmospheric environment.

[0028] (6) It improves the selectivity and conversion rate of the organic sulfur hydrogenation catalyst. With the increase of the active components in the catalyst, the carbon dioxide conversion rate is increased by more than 15%, and the carbon dioxide concentration in the purified gas after the hydrogenation reaction is reduced to less than 1%.

[0029] (7) While recovering hydrogen, it also recovers carbon dioxide gas, increases the molecular weight of the mixed gas, avoids the problem that the centrifugal compressor is prone to surge due to the decrease of the working medium molecular weight and the increase of the pressure ratio, and improves the operation efficiency of the centrifugal compressor. Description of the Drawings

[0030] Figure 1 It is a structural schematic diagram of a device for utilizing hydrogen-containing tail gas and carbon dioxide tail gas. Specific implementation manners

[0031] In order to further elaborate on the technical solution of the present invention, the present invention will be further described below through embodiments.

[0032] Embodiment 1

[0033] As Figure 1 shown, a device for utilizing hydrogen-containing tail gas and carbon dioxide tail gas in this embodiment includes an adsorption tower 1. The inlet of the adsorption tower 1 is used to introduce hydrogen-containing tail gas sent from an ethylene glycol synthesis device, carbon dioxide tail gas sent from a decarbonization process, and coke oven gas. The outlet of the adsorption tower 1 is connected to the inlet of a booster 2 through a pipeline. The outlet of the booster 2 is connected to the inlet of a first separator 3 through a pipeline. The outlet of the first separator 3 is connected to the cold medium inlet of a feed and product heat exchanger 4 through a pipeline. The cold medium outlet of the feed and product heat exchanger 4 is connected to the inlet of a pre-hydrogenation reactor 5 through a pipeline. The outlet of the pre-hydrogenation reactor 5 is connected to the inlet of a primary hydrogenation reactor 7 through a pipeline. The outlet of the primary hydrogenation reactor 7 is connected to the inlet of a medium-temperature desulfurization reactor 8 through a pipeline. The outlet of the medium-temperature desulfurization reactor 8 is connected to the inlet of a secondary hydrogenation reactor 10 through a pipeline. The outlet of the secondary hydrogenation reactor 10 is connected to the inlet of a fine desulfurization reactor 11 through a pipeline. The outlet of the fine desulfurization reactor 11 is connected to the hot medium inlet of the feed and product heat exchanger 4 through a pipeline. The hot medium outlet of the feed and product heat exchanger 4 is connected to the hot medium inlet of a water cooler 12 through a pipeline. The hot medium outlet of the water cooler 12 is connected to the inlet of a second separator 14 through a pipeline. The outlet of the second separator 14 is connected to the first inlet of a carbon dioxide removal tower 15 through a pipeline. The first outlet of the carbon dioxide removal tower 15 is connected to the inlet of a cryogenic separation device for separating out liquid methane. The second inlet of the carbon dioxide removal tower 15 is used to introduce lean MDEA solution. The second outlet of the carbon dioxide removal tower 15 is used to output rich MDEA solution.

[0034] As a further improvement, the device of this embodiment further includes a first waste heat recovery device 6, a second waste heat recovery device 9, and a third waste heat recovery device 13; the outlet of the pre-hydrogenation reactor 5 is connected to the hot medium inlet of the first waste heat recovery device 6 through a pipeline, and the hot medium outlet of the first waste heat recovery device 6 is connected to the inlet of the primary hydrogenation reactor 7 through a pipeline; the outlet of the medium-temperature desulfurization reactor 8 is connected to the hot medium inlet of the second waste heat recovery device 9 through a pipeline, and the hot medium outlet of the second waste heat recovery device 9 is connected to the inlet of the secondary hydrogenation reactor 10 through a pipeline; the hot medium outlet of the inlet and outlet heat exchanger 4 is connected to the hot medium inlet of the third waste heat recovery device 13 through a pipeline, and the hot medium outlet of the third waste heat recovery device 13 is connected to the hot medium inlet of the water cooler 12 through a pipeline.

[0035] Embodiment 2

[0036] A method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas in this embodiment, based on the device described in Embodiment 1, includes the following steps:

[0037] Step 1, the hydrogen-containing tail gas sent by the ethylene glycol synthesis device, the carbon dioxide tail gas sent by the decarbonization process, and the coke oven gas are introduced into the adsorption tower 1. In the adsorption tower 1, the adsorption effect of the adsorbent is used to remove impurities in the raw material gas, and organic substances such as alcohols and esters in the tail gas are adsorbed by the adsorbent to obtain purified raw material gas;

[0038] Among them, the process parameters of the hydrogen-containing tail gas are: flow rate 300 - 3000 Nm 3 / h, pressure 2.8 MPa, temperature 35°C - 40°C, hydrogen content 95% - 98%; the process parameters of the carbon dioxide tail gas are: flow rate 100 - 1000 Nm 3 / h, pressure 0.6 MPa, carbon dioxide content 95% - 99%, and the rest are impurities such as moisture;

[0039] Step 2, the purified raw material gas is sent to the booster 2 to be boosted to 3.2 MPa. The raw material gas after boosting enters the first separator 4. After separating moisture in the first separator 4, it enters the inlet and outlet heat exchanger 4 to be heated to 250°C;

[0040] Step 3, the raw material gas after heating enters the pre-hydrogenation reactor 5. In the pre-hydrogenation reactor 5, oxygen, unsaturated olefins, etc. in the raw material gas react with hydrogen to generate water, unsaturated alkanes, etc. The reaction temperature in the pre-hydrogenation reactor 5 is 295°C, and the pre-hydrogenation reactor 5 is internally filled with a catalyst with a nickel content of 6%;

[0041] Step 4: The gas after passing through the pre-hydrogenation reactor 5 enters the first waste heat recovery unit 6, where the temperature is reduced to 240°C. After recovering the reaction heat, it enters the primary hydrogenation reactor 7. The reaction temperature inside the primary hydrogenation reactor 7 is 360°C, and the catalyst filled inside the primary hydrogenation reactor 7 has a nickel content of 6%.

[0042] Step 5: The gas after passing through the primary hydrogenation reactor 7 enters the medium-temperature desulfurization reactor 8. The raw material gas after removing sulfides enters the second waste heat recovery unit 9, where the temperature is reduced to 240°C. After recovering the reaction heat, it is sent to the secondary hydrogenation reactor 10. The reaction temperature inside the secondary hydrogenation reactor 10 is 360°C, and the hydrogenation catalyst filled inside the secondary hydrogenation reactor 10 has a nickel content of 6%. Carbon dioxide in the gas further reacts with hydrogen to form methane.

[0043] Step 6: The gas after passing through the secondary hydrogenation reactor 10 enters the fine desulfurization reactor 11. The gas after further desulfurization enters the feed and product heat exchanger 3. After heat exchange, the temperature is reduced to 250°C, and then it is sent to the third waste heat recovery unit 13, where the temperature is reduced to 160°C. After recovering the reaction heat, it enters the water cooler 12, where the temperature is condensed to 30°C. After condensation, it is sent to the second separator 14. The gas after separating water is sent to the carbon dioxide removal tower 15. The gas after further purification is sent to the cryogenic separation unit to separate out liquid methane as the product. The carbon dioxide removal tower 15 also inputs lean MDEA solution and outputs rich MDEA solution.

[0044] In this embodiment, the by-product steam pressures of the first waste heat recovery unit 6, the second waste heat recovery unit 9, and the third waste heat recovery unit 13 are 2.5 MPa.

[0045] Embodiment 3

[0046] A method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas in this embodiment, based on the device described in Embodiment 1, includes the following steps:

[0047] Step 1: The hydrogen-containing tail gas sent by the ethylene glycol synthesis unit, the carbon dioxide tail gas sent by the decarbonization process, and the coke oven gas are introduced into the adsorption tower 1. Inside the adsorption tower 1, the impurities in the raw material gas are removed by the adsorption action of the adsorbent, and organic substances such as alcohols and esters in the tail gas are adsorbed by the adsorbent to obtain purified raw material gas.

[0048] Among them, the process parameters of the hydrogen-containing tail gas are: flow rate 300 - 3000 Nm 3 / h, pressure 2.8 MPa, temperature 35°C - 40°C, hydrogen content 95% - 98%; the process parameters of the carbon dioxide tail gas are: flow rate 100 - 1000 Nm 3 / h, with a pressure of 0.6 MPa, a carbon dioxide content of 95% - 99%, and the rest being moisture and other impurities;

[0049] Step 2, The purified feed gas is sent to a booster 2 to be pressurized to 3.0 MPa. The pressurized feed gas enters the first separator 4. After separating moisture in the first separator 4, it enters the inlet and outlet heat exchanger 4 and is heated to 220 °C;

[0050] Step 3, The heated feed gas enters the pre-hydrogenation reactor 5. In the pre-hydrogenation reactor 5, oxygen, unsaturated olefins, etc. in the feed gas react with hydrogen to generate water, unsaturated alkanes, etc. The reaction temperature in the pre-hydrogenation reactor 5 is 290 °C, and the pre-hydrogenation reactor 5 is filled with a catalyst with a nickel content of 3%;

[0051] Step 4, The gas after passing through the pre-hydrogenation reactor 5 enters the first waste heat recovery unit 6 to reduce the temperature to 220 °C. After recovering the reaction heat, it enters the first-stage hydrogenation reactor 7. The reaction temperature in the first-stage hydrogenation reactor 7 is 340 °C, and the first-stage hydrogenation reactor 7 is filled with a catalyst with a nickel content of 3%;

[0052] Step 5, The gas after passing through the first-stage hydrogenation reactor 7 enters the medium-temperature desulfurization reactor 8. The feed gas after removing sulfides enters the second waste heat recovery unit 9 to reduce the temperature to 220 °C. After recovering the reaction heat, it is sent to the second-stage hydrogenation reactor 10. The reaction temperature inside the second-stage hydrogenation reactor 10 is 340 °C. The second-stage hydrogenation reactor 10 is filled with a hydrogenation catalyst with a nickel content of 3%. Carbon dioxide in the gas further reacts with hydrogen to generate methane;

[0053] Step 6, The gas after passing through the second-stage hydrogenation reactor 10 enters the fine desulfurization reactor 11. The gas after further desulfurization enters the inlet and outlet heat exchanger 3. After heat exchange, the temperature is reduced to 230 °C and then sent to the third waste heat recovery unit 13 to reduce the temperature to 160 °C. After recovering the reaction heat, it enters the water cooler 12 to condense the temperature to 20 °C. After condensation, it is sent to the second separator 14. The gas after separating moisture is sent to the carbon dioxide removal tower 15. The gas after further purification is sent to a cryogenic separation unit to separate out liquid methane as a product. The carbon dioxide removal tower 15 also inputs lean MDEA solution and outputs rich MDEA solution.

[0054] The by-product steam pressure of the first waste heat recovery unit 6, the second waste heat recovery unit 9, and the third waste heat recovery unit 13 in this embodiment is 0.5 MPa.

[0055] Example 4

[0056] A method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas in this embodiment, based on the device described in Example 1, includes the following steps:

[0057] Step 1: The hydrogen-containing tail gas sent from the ethylene glycol synthesis unit, the carbon dioxide tail gas sent from the decarbonization process, and the coke oven gas are introduced into the adsorption tower 1. In the adsorption tower 1, the adsorbent is used to remove impurities in the raw material gas by adsorption. Organic substances such as alcohols and esters in the tail gas are adsorbed by the adsorbent, and the purified raw material gas is obtained.

[0058] Among them, the process parameters of the hydrogen-containing tail gas are: flow rate 300 - 3000 Nm 3 / h, pressure 2.8 MPa, temperature 35°C - 40°C, hydrogen content 95% - 98%; the process parameters of the carbon dioxide tail gas are: flow rate 100 - 1000 Nm 3 / h, pressure 0.6 MPa, carbon dioxide content 95% - 99%, and the rest are impurities such as moisture.

[0059] Step 2: The purified raw material gas is sent to the booster 2 to be boosted to 3.4 MPa. The raw material gas after boosting enters the first separator 4. After separating the moisture in the first separator 4, it enters the inlet and outlet heat exchanger 4 to be heated to 275°C.

[0060] Step 3: The raw material gas after heating enters the pre-hydrogenation reactor 5. In the pre-hydrogenation reactor 5, oxygen, unsaturated olefins, etc. in the raw material gas react with hydrogen to generate water, unsaturated alkanes, etc. The reaction temperature in the pre-hydrogenation reactor 5 is 300°C, and the pre-hydrogenation reactor 5 is filled with a catalyst with a nickel content of 9%.

[0061] Step 4: The gas after passing through the pre-hydrogenation reactor 5 enters the first waste heat recovery unit 6 to reduce the temperature to 260°C. After recovering the reaction heat, it enters the first-stage hydrogenation reactor 7. The reaction temperature in the first-stage hydrogenation reactor 7 is 380°C, and the first-stage hydrogenation reactor 7 is filled with a catalyst with a nickel content of 9%.

[0062] Step 5: The gas after passing through the first-stage hydrogenation reactor 7 enters the medium-temperature desulfurization reactor 8. The raw material gas after removing sulfides enters the second waste heat recovery unit 9 to reduce the temperature to 260°C. After recovering the reaction heat, it is sent to the second-stage hydrogenation reactor 10. The reaction temperature inside the second-stage hydrogenation reactor 10 is 390°C, and the second-stage hydrogenation reactor 10 is filled with a hydrogenation catalyst with a nickel content of 9%. Carbon dioxide in the gas further reacts with hydrogen to generate methane.

[0063] Step 6: The gas exiting the secondary hydrogenation reactor 10 enters the fine desulfurization reactor 11. After further desulfurization, the gas enters the feed and product heat exchanger 3. After heat exchange, the temperature is reduced to 260°C and then sent to the third waste heat recovery unit 13, where the temperature is reduced to 160°C. After recovering the reaction heat, it enters the water cooler 12, where the temperature is condensed to 40°C. After condensation, it is sent to the second separator 14. The gas after separating the moisture is sent to the carbon dioxide removal tower 15. After further purification, the gas is sent to the cryogenic separation unit to separate out liquid methane as the product. The carbon dioxide removal tower 15 also inputs lean MDEA solution and outputs rich MDEA solution.

[0064] In this embodiment, the by-product steam pressure of the first waste heat recovery unit 6, the second waste heat recovery unit 9, and the third waste heat recovery unit 13 is 3.8 MPa.

[0065] After being processed through the above processes, the hydrogen-containing tail gas and the carbon dioxide tail gas are converted into valuable LNG products, solving the safety and environmental protection problems. At the same time, the resource utilization efficiency is improved, the economic benefits of the enterprise are increased, and the carbon dioxide emissions are reduced.

[0066] The foregoing has shown and described the main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

[0067] In addition, it should be understood that although this specification is described in accordance with the embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A device for utilizing hydrogen-containing tail gas and carbon dioxide tail gas, characterized in that: The invention comprises an adsorption tower (1), wherein the inlet of the adsorption tower (1) is used to introduce hydrogen-containing tail gas sent from an ethylene glycol synthesis unit, carbon dioxide tail gas sent from a decarbonization process, and coke oven gas, the outlet of the adsorption tower (1) is connected to the inlet of a supercharger (2) through a pipeline, the outlet of the supercharger (2) is connected to the inlet of a first separator (3) through a pipeline, the outlet of the first separator (3) is connected to the cold medium inlet of an inlet and outlet heat exchanger (4) through a pipeline, the cold medium outlet of the inlet and outlet heat exchanger (4) is connected to the inlet of a pre-hydrogenation reactor (5) through a pipeline, the outlet of the pre-hydrogenation reactor (5) is connected to the inlet of a primary hydrogenation reactor (7) through a pipeline, the outlet of the primary hydrogenation reactor (7) is connected to the inlet of a medium-temperature desulfurization reactor (8) through a pipeline, and the outlet of the medium-temperature desulfurization reactor (8) is connected to the inlet of a secondary hydrogenation reactor (10) through a pipeline. The outlet of the secondary hydrogenation reactor (10) is connected to the inlet of the fine desulfurization reactor (11) through a pipeline, the outlet of the fine desulfurization reactor (11) is connected to the heat medium inlet of the inlet and outlet heat exchanger (4) through a pipeline, the heat medium outlet of the inlet and outlet heat exchanger (4) is connected to the heat medium inlet of the water cooler (12) through a pipeline, the heat medium outlet of the water cooler (12) is connected to the inlet of the second separator (14) through a pipeline, the outlet of the second separator (14) is connected to the first inlet of the carbon dioxide removal tower (15) through a pipeline, the first outlet of the carbon dioxide removal tower (15) is connected to the inlet of the deep cold separation device through a pipeline for separating liquid methane, the second inlet of the carbon dioxide removal tower (15) is used to introduce a lean MDEA solution, and the second outlet of the carbon dioxide removal tower (15) is used to output a rich MDEA solution.

2. The hydrogen-containing tail gas and carbon dioxide tail gas utilization device according to claim 1, characterized in that: It also includes a first waste heat recovery device (6), a second waste heat recovery device (9) and a third waste heat recovery device (13); the outlet of the pre-hydrogenation reactor (5) is connected to the heat medium inlet of the first waste heat recovery device (6) through a pipeline, and the heat medium outlet of the first waste heat recovery device (6) is connected to the inlet of the primary hydrogenation reactor (7) through a pipeline; the outlet of the medium-temperature desulfurization reactor (8) is connected to the heat medium inlet of the second waste heat recovery device (9) through a pipeline, and the heat medium outlet of the second waste heat recovery device (9) is connected to the inlet of the secondary hydrogenation reactor (10) through a pipeline; the heat medium outlet of the inlet and outlet heat exchanger (4) is connected to the heat medium inlet of the third waste heat recovery device (13) through a pipeline, and the heat medium outlet of the third waste heat recovery device (13) is connected to the heat medium inlet of the water cooler (12) through a pipeline.

3. A method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas, characterized in that: The following steps are involved: Step 1, the hydrogen-containing tail gas sent from the ethylene glycol synthesis unit, the carbon dioxide tail gas sent from the decarbonization process and the coke oven gas are introduced into an adsorption tower (1), and in the adsorption tower (1), the impurities in the raw gas are removed by the adsorption effect of the adsorbent to obtain a purified raw gas; Step 2, the purified raw gas is sent to the booster (2) for pressure increase, and the pressurized raw gas enters the first separator (4), after the water is separated in the first separator (4), it enters the inlet and outlet heat exchanger (4) for temperature increase; Step 3, the heated raw gas enters a pre-hydrogenation reactor (5), and the raw gas reacts with hydrogen in the pre-hydrogenation reactor (5); Step 4, the gas after passing through the pre-hydrogenation reactor (5) enters the first waste heat recovery device (6), and after recovering the reaction heat, enters the primary hydrogenation reactor (7); Step 5, the gas after passing through the primary hydrogenation reactor (7) enters the medium-temperature desulfurization reactor (8), and the raw gas after the sulfide is removed enters the second waste heat recovery device (9), and after recovering the reaction heat, it is sent to the secondary hydrogenation reactor (10); Step 6, the gas after the secondary hydrogenation reactor (10) enters the fine desulfurization reactor (11), and the gas after further desulfurization enters the inlet and outlet heat exchanger (3), and after heat exchange, it is sent to the third waste heat recovery device (13), after recovering the reaction heat, it enters the water cooler (12), and after condensation, it is sent to the second separator (14), and the gas after water separation is sent to the carbon dioxide removal tower (15), and the gas after further purification is sent to the deep cold separation device to separate the liquid methane as a product.

4. A method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to claim 3, characterized in that: The process parameters of the hydrogen-containing tail gas in step 1 are: flow rate 300~3000Nm 3 / h, pressure 2.8MPa, temperature 35℃~40℃, hydrogen content 95%~98%; process parameters of carbon dioxide tail gas: flow rate 100~1000Nm 3 / h, pressure 0.6MPa, carbon dioxide content 95%~99%.

5. The method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to claim 3, characterized in that: The purified raw gas in step 2 is sent to the booster (2) to be pressurized to 3.0-3.4 MPa, and then enters the inlet and outlet heat exchanger (4) to be heated to 220-275°C.

6. The method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to claim 3, characterized in that: The reaction temperature in the pre-hydrogenation reactor (5) in step 3 is 290-300° C., and the pre-hydrogenation reactor (5) is filled with a catalyst having a nickel content of 3%-9%.

7. The method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to claim 3, characterized in that: In step 4, the first waste heat recovery device (6) reduces the temperature to 220-260° C., the reaction temperature in the primary hydrogenation reactor (7) is 340-380° C., and the primary hydrogenation reactor (7) is filled with a catalyst having a nickel content of 3%-9%.

8. The method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to claim 3, characterized in that: In step 5, the second waste heat recovery device (9) reduces the temperature to 220-260° C., the reaction temperature in the secondary hydrogenation reactor (10) is 340-390° C., and the secondary hydrogenation reactor (10) is filled with a hydrogenation catalyst having a nickel content of 3%-9%.

9. The method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to claim 3, characterized in that: In step 6, the inlet and outlet heat exchanger (3) reduces the temperature to 230-260°C, the third waste heat recovery device (13) reduces the temperature to 160°C, and the water cooler (12) condenses the temperature to 20-40°C.

10. A method for utilizing hydrogen-containing tail gas and carbon dioxide tail gas according to any one of claims 3 to 9, characterized in that: The byproduct steam pressure of the first waste heat recovery device (6), the second waste heat recovery device (9) and the third waste heat recovery device (13) is 0.5 to 3.8 MPa.

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