Liquefaction recovery system for dimethyl ether in mixed gas

Abstract

The utility model provides a system for liquefying and recovering dimethyl ether in mixed gas. The system comprises a washing tower group, a first-stage temperature swing adsorption tower group and a second-stage temperature swing adsorption tower group, the raw material gas pipeline is connected with the washing tower group, the washing tower group is provided with a dimethyl ether liquid circulating pipeline and a regeneration gas pipeline header pipe, and the dimethyl ether liquid circulating pipeline is provided with a dimethyl ether liquid circulating pump and a dimethyl ether liquid cooler; the first-stage temperature swing adsorption tower group is connected with the washing tower group and the regenerated gas pipeline header pipe through pipelines and valves; the second-stage temperature swing adsorption tower group is connected with an outlet of the first-stage temperature swing adsorption tower group and a regeneration gas pipeline main pipe through pipelines and valves, and the second-stage temperature swing adsorption tower group is provided with a product gas pipeline; the first-stage temperature swing adsorption tower group and the second-stage temperature swing adsorption tower group are connected with an inlet of the washing tower group through a desorption gas pipeline and a valve, and a desorption gas cooler is arranged on the desorption gas pipeline. The system can achieve efficient recovery of dimethyl ether.

Description

TECHNICAL FIELD

[0001] The utility model mainly relates to the dimethyl ether recovery related technical field, concretely is a kind of dimethyl ether liquefaction recovery system in mixed gas. BACKGROUND

[0002] In the technical process of producing ethanol and dimethyl ether from coal synthetic gas, 3%-9% of dimethyl ether is contained in the tail gas of dimethyl ether production. It is necessary to recover dimethyl ether in the tail gas by reasonable means to ensure environmental protection requirements and increase benefits.

[0003] The previous process is to recover 85%-90% of effective hydrogen and carbon monoxide in the process by temperature swing adsorption, and the remaining gas is burned in a flare. This not only wastes the produced dimethyl ether product, but also increases carbon emissions from flare combustion. At the same time, 10%-15% of effective hydrogen and carbon monoxide are lost in this process, which is not only uneconomical but also not environmentally friendly. Therefore, it is necessary to design a system that can ensure environmental protection requirements and achieve high-efficiency recovery of dimethyl ether to solve the shortcomings of the prior art. CONTENT OF THE UTILITY MODEL

[0004] To solve the shortcomings of the current technology, the utility model combines the prior art and is based on practical application to provide a dimethyl ether liquefaction recovery system in mixed gas, which can achieve high-efficiency recovery of dimethyl ether.

[0005] The technical solution of the utility model is as follows:

[0006] A dimethyl ether liquefaction recovery system in mixed gas includes a washing tower group, a first-stage temperature swing adsorption tower group and a second-stage temperature swing adsorption tower group.

[0007] The raw material gas pipeline is connected to the washing tower group, which is configured with a dimethyl ether liquid circulation pipeline and a regenerated gas pipeline main pipe. A dimethyl ether liquid circulation pump and a dimethyl ether liquid cooler are arranged on the dimethyl ether liquid circulation pipeline.

[0008] The first-stage temperature swing adsorption tower group is connected to the outlet of the washing tower group and the regenerated gas pipeline main pipe through a pipeline and a valve.

[0009] The second-stage temperature swing adsorption tower group is connected to the outlet of the first-stage temperature swing adsorption tower group and the regenerated gas pipeline main pipe through a pipeline and a valve, and is configured with a product gas pipeline.

[0010] The first-stage temperature swing adsorption tower group and the second-stage temperature swing adsorption tower group are both connected to the inlet of the washing tower group through a desorption gas pipeline and a valve, and a desorption gas cooler is arranged on the desorption gas pipeline.

[0011] The utility model discloses a washing tower group makes dimethyl ether gas liquefaction absorption into dimethyl ether liquid, simultaneously, the temperature of circulating dimethyl ether liquid in this process, will gradually increase because of the liquefaction of dimethyl ether gas, adopts the mode of circulating pump after adding a cooler to reduce the temperature of dimethyl ether liquid, completes dimethyl ether liquid circulation washing, guarantees the effect of dimethyl ether liquid washing absorption. The gas after dimethyl ether liquid absorption enters the first stage temperature swing adsorption tower group composed of two towers or multiple towers, and the adsorbent in the regenerated adsorption tower bed layer absorbs the gas dimethyl ether, and the dimethyl ether in the gas is absorbed by the adsorbent, and the dimethyl ether partial pressure in the adsorbent gradually reaches the liquefaction partial pressure, and the gas-liquid mixture of dimethyl ether is formed in the adsorbent. The gas with the dimethyl ether content in the design index from the first stage temperature swing adsorption tower group goes to the second stage temperature swing adsorption tower group composed of two towers or multiple towers and carries out further adsorption operation, and finally obtains the product gas with the total content of dimethyl ether, methyl acetate and methanol below the design standard. The adsorption saturated adsorption tower carries out the isobaric back flushing operation with the heating raw material gas, and the high concentration dimethyl ether gas-liquid mixture in the adsorbent is blown out from the adsorption tower from top to bottom, and after cooling by the cooler, goes to the washing tower and is washed by the normal temperature dimethyl ether liquid and then is liquefied, so as to achieve the purpose of recovering dimethyl ether, and the adsorbent is regenerated, and after the adsorption tower is regenerated, the temperature is lowered and cooled to enter the next cycle. The raw material gas is used as the adsorption bed layer regeneration gas source, avoids the use of other gas regeneration, causes the product gas pollution factor, and the regeneration gas returns to the washing tower and has no external discharge loss.

[0012] Further, the washing tower group includes washing tower A and washing tower B, the regeneration gas pipeline main pipe is arranged between washing tower A and washing tower B, the raw material gas pressure reducing regulating valve is arranged on the pipeline connected with washing tower A and washing tower B, the regeneration gas flow regulating valve is arranged on the regeneration gas pipeline, and the desorption gas pipeline is connected to washing tower B.

[0013] Further, the dimethyl ether liquid circulation pipelines of washing tower A and washing tower B are connected with the liquid product dimethyl ether pipeline through pipelines and dimethyl ether liquid level regulating valves.

[0014] Two-stage washing towers are adopted, the first stage washing tower can wash the dimethyl ether content in the raw material gas to below 1.5%, after the treatment, the degree of polluting the adsorption bed layer when using the raw material gas as the regeneration gas is reduced. After the secondary washing, the dimethyl ether in the raw material gas is reduced to below 1%, and the amount of the adsorbent in the later process is reduced.

[0015] The raw material gas pressure reducing regulating valve and the regeneration gas flow regulating valve are used to divide the raw material gas into two groups of gas with pressure difference, 15-25% of the high-pressure part is used as the regeneration gas, and the remaining part is used to remove and recover dimethyl ether after pressure reduction, after the pressure difference is formed through the raw material gas pressure reducing regulating valve, the regeneration gas can work normally and be recovered, the system pressure drop is less than 0.2Mpa, and the requirement of the later process on the pressure can be completely guaranteed.

[0016] Further, the first-stage temperature swing adsorption tower group comprises an adsorption tower A and an adsorption tower B, the adsorption tower A and the adsorption tower B are arranged in parallel, and the adsorption tower A and the adsorption tower B are connected with the second-stage temperature swing adsorption tower group through an intermediate gas pipeline.

[0017] Further, the adsorption tower A and the adsorption tower B are connected with each other through pipelines and valves, and are connected with an intermediate gas cooling pipeline, the intermediate gas cooling pipeline is provided with an intermediate gas cooler, and the intermediate gas cooling pipeline is connected with the intermediate gas pipeline.

[0018] The two-stage adsorption tower is alternately operated, and the intermediate gas of the other adsorption tower can be used for cooling and temperature reduction when the adsorption tower is cooled.

[0019] Further, the second-stage temperature swing adsorption tower group comprises an adsorption tower C, an adsorption tower D and an adsorption tower E, the adsorption tower C and the adsorption tower D are arranged in parallel, the inlets of the adsorption tower C and the adsorption tower D are connected with the intermediate gas pipeline, and the outlets are connected with a product gas pipeline.

[0020] Further, the adsorption tower C, the adsorption tower D and the adsorption tower E are connected with each other through pipelines and valves.

[0021] Further, the regeneration gas pipeline main pipe has three branch pipes, a first branch pipe is connected to the adsorption tower A and the adsorption tower B, a second branch pipe is connected to the adsorption tower C, the adsorption tower D and the adsorption tower E, and a third branch pipe is connected to the adsorption tower E.

[0022] Further, the first branch pipe and the second branch pipe of the regeneration gas pipeline main pipe are provided with regeneration gas heaters.

[0023] After the regeneration gas heating of the adsorption tower C or the adsorption tower D is completed, the regeneration gas that is not heated through the adsorption tower E can be used to cool and replace the adsorption tower that needs to be cooled, so that the dimethyl ether with high concentration brought by the regeneration gas main pipeline can be replaced.

[0024] Further, the valves on the pipelines are remote control valves, so that the system can be automatically controlled.

[0025] The beneficial effects of the utility model are as follows:

[0026] 1. The system efficiently recovers and liquefies dimethyl ether in tail gas, no effective gas is lost in the whole process, the total content of dimethyl ether, methyl acetate and methanol in product gas is ensured to be below the design index, and the system has obvious economic benefits and environmental protection value.

[0027] 2, The whole operation process of the system has no exhaust gas outlet, realizes full recovery, reduces the gas loss of the traditional process decompression venting, the power system only has a dimethyl ether circulating pump, the recovered dimethyl ether liquid pressure is the system pressure, the power consumption load is low, and the recovery cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0028] BRIEF DESCRIPTION OF DRAWINGS Figure 1 It is a system structure schematic diagram of the utility model.

[0029] The reference signs shown in the figure are:

[0030] 1-raw material gas pipeline; 2-washing tower A; 3-raw material gas pipeline after washing; 4-regeneration gas flow regulating valve; 5-raw material gas decompression regulating valve; 6-dimethyl ether liquid level regulating valve A; 7-dimethyl ether liquid circulating pump; 8-liquid product dimethyl ether pipeline; 9-dimethyl ether liquid cooler; 10-dimethyl ether liquid level regulating valve B; 11-washing tower B; 12-dimethyl ether liquid circulating pipeline; 13-regeneration gas pipeline main pipe; 14-adsorption tower A; 15-adsorption tower B; 16-regeneration gas heater; 17-first sequence valve; 18-second sequence valve; 19-third sequence valve; 20-fourth sequence valve; 21-fifth sequence valve; 22-regeneration gas cooling pipeline; 23-regeneration gas heating pipeline; 24-regeneration gas pipeline; 25-regeneration gas regeneration pipeline; 26-regeneration gas inlet sequence valve; 27-intermediate gas cooling pipeline; 28-adsorption tower E regeneration sequence valve; 29-product gas pipeline; 30-desorption gas pipeline; 31-desorption gas cooler; 32-backflow pipeline; 33-cooling sequence valve; 34-adsorption tower C; 35-adsorption tower D; 36-adsorption tower E; 37-intermediate gas pipeline; 38-adsorption tower E regeneration gas outlet sequence valve; 39-adsorption tower E cooling sequence valve A; 40-adsorption tower C and adsorption tower D cooling sequence valve; 41-adsorption tower E cooling sequence valve B; 42-intermediate gas cooler. DETAILED DESCRIPTION

[0031] The utility model is further described in combination with the drawings and specific embodiments. It should be understood that these embodiments are only used for illustrating the utility model and are not used for limiting the scope of the utility model. In addition, it should be understood that after reading the content taught by the utility model, those skilled in the art can make various changes or modifications to the utility model, and these equivalent forms also fall within the scope defined by the present application.

[0032] Embodiment 1

[0033] The embodiment provides a mixed gas dimethyl ether liquefaction recovery system, and a system principle diagram is as shown in Figure 1 .

[0034] The recovery system of the embodiment mainly consists of a washing tower group, a first-stage temperature swing adsorption tower group, a second-stage temperature swing adsorption tower group, pipelines and corresponding valves and the like.

[0035] As shown in Figure 1 , the washing tower group mainly comprises a washing tower A2 and a washing tower B11. The raw material gas pipeline 1 is connected to the washing tower A2. The washing tower A2 is provided with a dimethyl ether liquid circulation pipeline 12. A dimethyl ether liquid circulation pump 7 and a dimethyl ether liquid cooler are arranged on the dimethyl ether liquid circulation pipeline 12. The dimethyl ether liquid circulation pipeline 12 is connected to a liquid product dimethyl ether pipeline 8 through a dimethyl ether liquid level regulating valve A6.

[0036] The top outlet of the washing tower A2 is connected to a washed raw material gas pipeline 3. The washed raw material gas pipeline 3 has two branches. One branch is connected to a regeneration gas pipeline main pipe 13 through a regeneration gas flow regulating valve 4. The other branch is connected to the washing tower B11 through a raw material gas pressure reducing valve 5. The washing tower B11 is provided with a dimethyl ether liquid circulation pipeline 12. A dimethyl ether liquid circulation pump 7 and a dimethyl ether liquid cooler 9 are arranged on the dimethyl ether liquid circulation pipeline 12. The dimethyl ether liquid circulation pipeline 12 is connected to the liquid product dimethyl ether pipeline 8 through a dimethyl ether liquid level regulating valve B10.

[0037] The first-stage temperature swing adsorption tower group mainly comprises an adsorption tower A14 and an adsorption tower B15. The adsorption tower A14 and the adsorption tower B15 are arranged in parallel. The upper pipelines of the adsorption tower A14 and the adsorption tower B15 are provided with a first program control valve 17 and a second program control valve 18 (the program control valve referred to in the present application is a remote control valve). The first program control valve 17 is connected to an intermediate gas pipeline 37. The second program control valve 18 is connected to a first branch pipeline of the regeneration gas pipeline main pipe 13.

[0038] The lower pipelines of the adsorption tower A14 and the adsorption tower B15 are provided with a third program control valve 19, a fourth program control valve 20 and a fifth program control valve 21. The third program control valve 19 is connected to the outlet of the washing tower B11. The third program control valve 19 is connected to the washing tower B11. The fourth program control valve 20 is connected to a desorption gas pipeline 30. The fifth program control valve 21 is connected to an intermediate gas cooling pipeline 27. The intermediate gas cooling pipeline 27 is connected to the intermediate gas pipeline 37. An intermediate gas cooler 42 is arranged on the intermediate gas cooling pipeline 27. A desorption gas cooler 31 is arranged on the desorption gas pipeline 30.

[0039] The second-stage temperature swing adsorption tower group mainly comprises the adsorption tower C34, the adsorption tower D35 and the adsorption tower E36. The adsorption tower C34 and the adsorption tower E35 are connected in parallel, and the upper pipes are provided with the first program control valve 17 and the second program control valve 18. The first program control valve 17 is connected to the product gas pipe 29, and the second program control valve 18 is connected to the upper pipe of the adsorption tower E36. The lower pipes of the adsorption tower C34 and the adsorption tower D35 are provided with the third program control valve 19, the fourth program control valve 20 and the fifth program control valve 21. The third program control valve 19 is connected to the intermediate gas pipe 37, the fourth program control valve 20 is connected to the desorption gas pipe 30, the fifth program control valve 21 is connected to the bottom of the adsorption tower E36, and the adsorption tower E36 is connected to the product gas pipe 29 through the program control valve A39 for cooling of the adsorption tower E. The upper part of the adsorption tower E36 is connected to the product gas pipe 29 through the program control valve B41 for cooling of the adsorption tower E.

[0040] The upper part of the adsorption tower E36 is connected to the second branch of the regeneration gas main pipe 13, i.e., the regeneration gas pipe 24. The pipe has two branches, i.e., the regeneration gas cooling pipe 22 and the regeneration gas heating pipe 23. One valve is arranged at each pipe. The regeneration gas cooling pipe 22 and the regeneration gas heating pipe 23 are connected in parallel and are provided with the program control valve 28 for regeneration of the adsorption tower E between them. The third branch, i.e., the regeneration gas regeneration pipe 25, is connected to the lower part of the adsorption tower E36 and is connected to the reflux pipe 32 through the program control valve 38 for outlet of the regeneration gas of the adsorption tower E. The reflux pipe 32 is connected to the desorption gas pipe 30.

[0041] The regeneration gas main pipe 13 has three branches. The first branch pipe is provided with the program control valve 26 for inlet of the regeneration gas and the regeneration gas heater 16 and is connected to the first-stage temperature swing adsorption tower group. The second branch pipe is provided with the regeneration gas heater 16 and is connected to the second-stage temperature swing adsorption tower group. The third branch pipe is provided with the program control valve 26 for inlet of the regeneration gas and is not provided with the regeneration gas heater 16. The third branch pipe is connected to the adsorption tower E36.

[0042] Example 2

[0043] The present embodiment provides a recycling method and a recycling process of the above-mentioned recycling system.

[0044] In the system implementation process, first, the pressure of 2.2-5.2Mpa, containing gaseous dimethyl ether 3%-9% of raw gas through the raw gas pipeline 1 into the washing tower A2, using liquid dimethyl ether washing absorption, wire mesh absorber absorption dimethyl ether droplets, the raw gas dimethyl ether content from 3%-9% to 1.5% or less, then using the regeneration gas flow regulating valve 4 gas, wherein the regeneration gas accounts for 15-25% of the raw gas, the remaining gas through the raw gas pressure regulating valve 5 after decompression to washing tower B11, washing tower B11 washing tower B11, the dimethyl ether content in the raw gas to 1% or less, then sent to the adsorption tower A14 or adsorption tower B15. Adsorption tower A14 or adsorption tower B15 upper outlet dimethyl ether content reaches the design index of 0.3%, switch to another adsorption tower adsorption, the intermediate gas from the intermediate gas pipeline 37 into the second stage of the adsorption tower group.

[0045] In the above washing process, the temperature of the circulating dimethyl ether liquid will gradually increase due to the liquefaction of dimethyl ether gas, and the temperature of the dimethyl ether liquid is reduced to 40 degrees or less by using a dimethyl ether liquid circulating pump 7 and a dimethyl ether liquid cooler 9 to ensure the effect of dimethyl ether liquid washing absorption. The temperature of the dimethyl ether liquid at the bottom of the washing tower A2 and the washing tower B11 should be controlled at 40℃ or less after the dimethyl ether liquid cooler 9, so that the dimethyl ether content in the outlet gas at the top of the washing tower A2 and the washing tower B11 is easily controlled below the design index. After two-stage washing, the dimethyl ether in the raw gas is reduced to 1% or less, reducing the amount of adsorbent in the later stage.

[0046] To ensure the effect of regeneration of the adsorption tower A14 and the adsorption tower B15, the temperature of the regeneration gas after heating by the regeneration gas heater 16 is in the range of 140℃-160℃, which effectively ensures that the dimethyl ether content in the intermediate gas is below the design index of 0.3%. The raw gas is divided into two gases with pressure difference by using the raw gas pressure regulating valve 5 and the regeneration gas flow regulating valve 4, wherein 15-25% of the high pressure part is used as regeneration gas, and the remaining gas is decompressed to remove and recover dimethyl ether in the main process. After the pressure difference is formed by the raw gas pressure regulating valve 5, it is ensured that the regeneration gas can work normally and be recovered, and the system pressure drop is less than 0.2Mpa, which fully meets the requirements of the later stage on pressure. The dimethyl ether content in the raw gas is washed to 1.5% or less by the first-stage washing tower, which reduces the degree of pollution of the adsorption bed when using raw gas as regeneration gas.

[0047] When the adsorption tower A14 or the adsorption tower B15 is saturated and the outlet dimethyl ether content reaches 0.3%, the tower is switched to run, and the adsorption tower enters the regeneration process, and the generated intermediate gas is sent to the second-stage adsorption tower group.

[0048] The regeneration gas is heated to 140-160 degrees by the regeneration gas inlet program control valve 26 and the regeneration gas heater 16, and then is sent to the top of the adsorption tower A 14 or the adsorption tower B 15 through the second program control valve 18. Under the action of the high-temperature gas, the dimethyl ether adsorbed in the adsorbent is gradually desorbed in the form of gas-liquid mixture, enters the desorption gas cooler 31 through the fourth program control valve 20, and finally enters the bottom of the washing tower B 11, thus completing the liquefaction process of dimethyl ether.

[0049] The adsorbent in the adsorption tower is selected from one or more of activated carbon, 5A molecular sieve and silica gel. When the dimethyl ether concentration in the adsorbent reaches the liquefaction concentration, a dimethyl ether gas-liquid mixture is formed in the adsorbent bed, and the dimethyl ether content in the raw gas is reduced to below 0.3% by the first-stage adsorption tower group composed of the adsorption tower A 14 and the adsorption tower B 15, and then enters the second-stage adsorption tower group composed of the adsorption tower C 34, the adsorption tower D 35 and the adsorption tower E 36, so that the total content of dimethyl ether, methyl acetate and methanol in the final product gas can be controlled to be below 100 ppm. The dimethyl ether gas-liquid mixture in the adsorbent is desorbed by isobaric backwashing operation using the raw gas heated to 140-160 degrees, and then is cooled by the cooler, washed by dimethyl ether liquid in the washing tower, liquefied, and recovered, so that the adsorbent is regenerated. The raw gas is used as the adsorption bed regeneration gas source, avoiding the use of other gases for regeneration, which causes product gas pollution. At the same time, the regeneration gas returns to the washing tower B 11 without external loss.

[0050] After the adsorption tower A 14 or the adsorption tower B 15 is desorbed by the high-temperature regeneration gas, the intermediate gas of the other adsorption tower is used for cooling. For example, after the adsorption tower A 14 is desorbed by the regeneration gas, the intermediate gas of the adsorption tower B 15 enters the adsorption tower A 14 through the first program control valve 17, enters the intermediate gas cooling pipeline 27 through the fifth program control valve 21, and then enters the adsorption tower C 34 and the adsorption tower D 35 through the intermediate gas pipeline 37. After the adsorption tower is cooled, the adsorption stage is entered, and the adsorption tower B 15 enters the heating regeneration stage. The two adsorption towers are alternately adsorbed.

[0051] The intermediate gas containing 0.3% dimethyl ether enters the adsorption tower C 34, and the product gas after adsorption of dimethyl ether is directly sent to the product gas pipeline 29. When the total content of dimethyl ether, methyl acetate and methanol at the upper outlet of the adsorption tower C 34 reaches the design value of 100 ppm, the adsorption tower D 35 is switched to run, and the adsorption tower C 34 enters the regeneration process. The adsorption tower C 34 and the adsorption tower D 35 are alternately adsorbed.

[0052] The regeneration gas is heated to 140-160 degrees by the regeneration gas pipeline and the regeneration gas heater 16, and then enters the adsorption tower C34 or the adsorption tower D35, and the regenerated adsorption tower. Under the action of the high-temperature gas, the dimethyl ether adsorbed in the adsorbent is gradually desorbed in the form of a gas-liquid mixture, enters the desorption gas cooler 31 through the fourth program-controlled valve 20, and finally enters the bottom of the washing tower B11, thus completing the whole process of dimethyl ether liquefaction.

[0053] After the regeneration gas is heated to regenerate the adsorbent, the regeneration gas in the third branch of the regeneration gas pipeline main pipe 13 is used first, and then the regeneration gas enters the adsorption tower C34 or the adsorption tower E35 that needs to be cooled through the regeneration gas inlet program-controlled valve 26, the regeneration gas regeneration pipeline 25, the adsorption tower E36 and the cooling program-controlled valve 33. The time for cooling and replacing the adsorption tower C34 or the adsorption tower D35 is not less than 5 minutes, and the replaced gas returns to the bottom of the washing tower B11 through the fourth program-controlled valve 20. Then, the product gas of another adsorption tower is used to cool the adsorption tower C34 or the adsorption tower D35 that needs to be cooled, and the product gas of the other adsorption tower enters the adsorption tower through the first program-controlled valve 17, the adsorption tower that needs to be cooled, the fifth program-controlled valve 21 and the final product gas pipeline 29, so as to further cool the adsorption tower. After the cooling is completed, the adsorption stage is entered, and the other adsorption tower enters the heating and regeneration stage.

[0054] After the adsorption tower E36 runs for five cycles (after replacing the adsorption tower C34 or the adsorption tower D35 five times), the regeneration gas is used to regenerate the adsorption tower E36 through the regeneration gas pipeline 24, the regeneration gas heater 16 and the adsorption tower E regeneration program-controlled valve 28. The desorption gas of the adsorption tower E36 returns to the washing tower B11 through the reflux pipeline 32 to recover dimethyl ether. After the heating and regeneration of the adsorption tower E36 are completed, the product gas of the adsorption tower C34 or the adsorption tower D35 is used to cool the adsorption tower E through the adsorption tower E cooling program-controlled valve A39, the adsorption tower E36 and the adsorption tower E cooling program-controlled valve B41, and then enters the product gas pipeline 29 to perform cooling.

[0055] After the regeneration gas heating of the adsorption tower C34 or the adsorption tower D35 is completed, the regeneration gas is used to cool and replace the adsorption tower that needs to be cooled through the regeneration gas regeneration pipeline 25, the regeneration gas inlet program-controlled valve 26, the adsorption tower E36 and the cooling program-controlled valve 33. The time for cooling and replacing the adsorption tower is not less than 5 minutes, so that the dimethyl ether with a high concentration brought by the regeneration gas main pipeline 13 can be replaced. After the replacement is completed, the product gas is used for cooling, so that the total content of dimethyl ether, methyl acetate and methanol in the product gas can be effectively ensured to be less than 100 ppm.

[0056] Example 3

[0057] The embodiment provides a specific implementation of the dimethyl ether recovery system and the recovery method. Table 1 is the raw material gas condition in the implementation.

[0058] Table 1 Raw material gas condition

[0059]

[0060] The process implementation points in this embodiment are as follows:

[0061] The key points of this process implementation are: 1. liquid dimethyl ether washing; 2. adsorbent absorption; and 3. regeneration liquefaction.

[0062] The main purpose of washing is to directly absorb part of the dimethyl ether in the raw material gas with the upper liquefied and downward flowing liquid dimethyl ether, so as to reduce the amount of special adsorbent needed to reduce dimethyl ether entering the adsorbent.

[0063] The main purpose of adsorbent absorption is that the adsorbent absorbs dimethyl ether, and after the dimethyl ether concentration in the adsorbent reaches the liquefaction concentration, a dimethyl ether gas-liquid mixture is formed in the adsorbent.

[0064] The main purpose of regeneration liquefaction is to completely desorb the dimethyl ether gas-liquid mixture in the adsorbent by heating, absorb it with dimethyl ether liquid to obtain product liquid dimethyl ether, and regenerate the adsorbent for the next cycle.

[0065] Table 2 is the implementation effect.

[0066] Table 2 Implementation Effect

[0067]

[0068] After statistics, the recovered dimethyl ether is (254 Nm3 / h-0.2034 Nm3 / h)=253.7966 Nm3 / h, accounting for 521.6 Kg / h, and the annual recovery of dimethyl ether is 417.28 tons, with a value of 13.77 million yuan (at 3300 yuan / ton).

[0069] Example 4

[0070] This embodiment provides a specific implementation of the dimethyl ether recovery system and method. Table 3 below shows the raw gas conditions during implementation.

[0071] Table 3 Raw Gas Conditions

[0072]

[0073]

[0074] The process implementation points in this embodiment are as follows:

[0075] The key points of this process implementation are: 1. liquid dimethyl ether washing; 2. adsorbent absorption; and 3. regeneration liquefaction.

[0076] The main purpose of washing is to absorb part of the dimethyl ether in the raw gas directly with the upper liquefied and downward flowing dimethyl ether, so as to reduce the amount of dimethyl ether reducing special adsorbent.

[0077] The main purpose of adsorbent absorption is that the adsorbent absorbs dimethyl ether, and after the dimethyl ether concentration in the adsorbent reaches the liquefied concentration, the dimethyl ether gas-liquid mixture is formed in the adsorbent.

[0078] The main purpose of regenerating liquefaction is to completely desorb the dimethyl ether gas-liquid mixture in the adsorbent by heating, absorb the dimethyl ether liquid to obtain the product dimethyl ether liquid, and regenerate the adsorbent for the next cycle.

[0079] The following Table 4 is the implementation effect.

[0080] Table 4 Implementation effect

[0081]

[0082] According to the statistics, the recovered dimethyl ether is 1123.82 Kg / h, the annual recovery of dimethyl ether is 8990.56 tons, and the value is 2966.88 million yuan.

Claims

1. A mixed gas dimethyl ether liquefaction recovery system characterized by, Comprise: washing tower group, first stage temperature swing adsorption tower group, second stage temperature swing adsorption tower group; Raw material gas pipeline connects washing tower group, washing tower group is equipped with dimethyl ether liquid circulation pipeline, regeneration gas pipeline main pipe, dimethyl ether liquid circulation pump and dimethyl ether liquid cooler are arranged on dimethyl ether liquid circulation pipeline; First stage temperature swing adsorption tower group is connected with washing tower group and regeneration gas pipeline main pipe through pipeline and valve; Second stage temperature swing adsorption tower group is connected with first stage temperature swing adsorption tower group outlet and regeneration gas pipeline main pipe through pipeline and valve, and second stage temperature swing adsorption tower group is equipped with product gas pipeline; First stage temperature swing adsorption tower group and second stage temperature swing adsorption tower group are connected with washing tower group inlet through desorption gas pipeline and valve, and desorption gas cooler is arranged on desorption gas pipeline.

2. The mixed gas dimethyl ether liquefaction recovery system according to claim 1, characterized by, The washing tower group comprises washing tower A and washing tower B, the regeneration gas pipeline main pipe is arranged between washing tower A and washing tower B, raw material gas pressure reducing regulating valve is arranged on the pipeline connecting washing tower A and washing tower B, regeneration gas flow regulating valve is arranged on the regeneration gas pipeline, and the desorption gas pipeline is connected to washing tower B.

3. The mixed gas dimethyl ether liquefaction recovery system according to claim 2, characterized by, The dimethyl ether liquid circulation pipeline of washing tower A and washing tower B is connected with liquid product dimethyl ether pipeline through pipeline and dimethyl ether liquid level regulating valve.

4. The mixed gas dimethyl ether liquefaction recovery system according to claim 1, characterized by, The first stage temperature swing adsorption tower group comprises adsorption tower A and adsorption tower B, adsorption tower A and adsorption tower B are arranged in parallel, and adsorption tower A and adsorption tower B are connected with second stage temperature swing adsorption tower group through intermediate gas pipeline.

5. The mixed gas dimethyl ether liquefaction recovery system according to claim 4, characterized by, Adsorption tower A and adsorption tower B are connected with each other through pipeline and valve, and are connected with intermediate gas cooling pipeline, intermediate gas cooler is arranged on intermediate gas cooling pipeline, and intermediate gas cooling pipeline is connected with intermediate gas pipeline.

6. The mixed gas dimethyl ether liquefaction recovery system according to claim 4, characterized by, The second stage temperature swing adsorption tower group comprises adsorption tower C, adsorption tower D and adsorption tower E, adsorption tower C and adsorption tower D are arranged in parallel, the inlet of adsorption tower C and adsorption tower D is connected with intermediate gas pipeline, and the outlet is connected with product gas pipeline.

7. The mixed gas dimethyl ether liquefaction recovery system according to claim 6, characterized by, Adsorption tower C, adsorption tower D and adsorption tower E are connected with each other through pipeline and valve.

8. The mixed gas dimethyl ether liquefaction recovery system according to claim 7, characterized by, The regeneration gas pipeline main pipe has three branch pipes, the first branch pipe is connected to adsorption tower A and adsorption tower B, the second branch pipe is connected to adsorption tower C, adsorption tower D and adsorption tower E, and the third branch pipe is connected to adsorption tower E.

9. The mixed gas dimethyl ether liquefaction recovery system according to claim 8, characterized by, Regeneration gas heater is arranged on the first branch pipe and the second branch pipe of regeneration gas pipeline main pipe.

10. The mixed gas dimethyl ether liquefaction recovery system according to any one of claims 1 to 9, characterized by, The valve on the pipeline is a remote control valve.

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