System for removing moisture and acid gas in crude ethylene gas

Abstract

The utility model discloses a system for removing moisture and acid gas in crude ethylene gas. The system comprises a crude ethylene gas feeding pipeline, a first adsorber, a second adsorber and a purified ethylene gas discharging pipeline, the crude ethylene gas feeding pipeline is connected with the first end of the first adsorber, the second end of the first adsorber is connected with the first end of the second adsorber, and the second end of the second adsorber is connected with the purified ethylene gas discharging pipeline; an adsorbent of the first adsorber is a 3A molecular sieve, and an adsorbent of the second adsorber is alkaline alumina balls; in the second adsorber, a stainless steel wire mesh filter is arranged behind the alkaline alumina ball adsorbent. According to the system disclosed by the utility model, a physical adsorption and chemical adsorption combined technology is adopted, so that the water content and the acid gas content in the crude ethylene gas are effectively reduced to below 1ppm respectively, and the treatment process is simpler, more efficient, energy-saving and environment-friendly.

Description

Technical Field

[0001] This utility model belongs to the field of chemical process treatment technology, specifically relating to a system for removing moisture and acidic gases from crude ethylene gas. Background Technology

[0002] Ethylene is a hydrocarbon cracking product and a crucial raw material for petrochemicals, making ethylene plants the leading sector in the petrochemical industry. Ethylene derivatives are diverse and widely used in synthetic materials and organic synthesis, accounting for over 75% of global petrochemical production. They are also widely applied in packaging, agriculture, construction, textiles, electronics, and automobiles. Future growth in oil demand is expected to slow, while demand for chemical products will remain stable, becoming the main driver of oil demand growth. Investment in the ethylene industry will continue to grow steadily, with ethylene feedstocks becoming more diversified and lighter, plants becoming larger, and production technologies becoming more diverse and low-carbon. Regional disparities in ethylene industry development are widening, intensifying competition. Therefore, improving ethylene production processes and reducing energy consumption are crucial to enhancing the competitiveness of ethylene plants.

[0003] Existing technologies for removing moisture and acid gases from crude ethylene gas have the following drawbacks: 1) The method of alkaline washing + water washing generates additional waste alkaline liquid and grease, which are difficult to handle; 2) The method of adsorption + absorption + adsorption cannot remove COS, and the acid gas removal rate is low, only reducing the total acid gas content to ≤3ppm, and frequent replacement of chemical absorbents is required. Utility Model Content

[0004] The purpose of this invention is to provide a system for removing moisture and acidic gases from crude ethylene gas. It employs a combination of physical and chemical adsorption techniques to effectively reduce the water content and acidic gas content in crude ethylene gas to below 1 ppm (mol). The process is simpler, more efficient, energy-saving, and environmentally friendly.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A system for removing moisture and acidic gases from crude ethylene gas includes a crude ethylene gas feed line, a first adsorber, a second adsorber, and a purified ethylene gas discharge line.

[0007] The crude ethylene gas feed line is connected to the first end of the first adsorber, the second end of the first adsorber is connected to the first end of the second adsorber, and the second end of the second adsorber is connected to the purified ethylene gas discharge line.

[0008] The adsorbent in the first adsorbent is 3A molecular sieve, and the adsorbent in the second adsorbent is alkaline alumina balls;

[0009] In the second adsorber, a stainless steel wire mesh filter is installed after the alkaline alumina ball adsorbent.

[0010] According to the system of this utility model, preferably, both the first adsorber and the second adsorber include two sets arranged in parallel, and the two sets can be switched to perform adsorption and regeneration operations. That is, one set is in the adsorption state, and the other set is in the regeneration state, so as to maintain the continuous and stable operation of the industrial production equipment at full load.

[0011] Specifically, the crude ethylene gas feed line can be switched to the first end of two sets of first adsorbers, the second end of the first adsorbers can be switched to the first end of two sets of second adsorbers, and the second ends of the two sets of second adsorbers can be switched to the purified ethylene gas discharge line.

[0012] More preferably, the system further includes a first adsorber regeneration gas inlet pipeline, a first adsorber regeneration gas outlet pipeline, a second adsorber regeneration gas inlet pipeline, and a second adsorber regeneration gas outlet pipeline.

[0013] The first adsorber regeneration gas inlet pipeline can be switched to the second end of two sets of the first adsorbers, and the first adsorber regeneration gas outlet pipeline can be switched to the first end of two sets of the first adsorbers.

[0014] The second adsorber regeneration gas inlet line can be switched to the second end of two sets of the second adsorbers, and the second adsorber regeneration gas outlet line can be switched to the first end of two sets of the second adsorbers.

[0015] As will be understood by those skilled in the art, the switchable connection is achieved by means of a shut-off valve or a three-way valve.

[0016] According to the system of this utility model, preferably, the process parameters of the first adsorber during adsorption include: operating temperature 15~40℃, operating pressure 0.8~4.0MPaG.

[0017] According to the system of this utility model, preferably, the process parameters of the first adsorber during regeneration include: operating temperature 25-240℃, operating pressure 0.05-0.5MPaG; the regeneration gas can be nitrogen or methane and hydrogen. More preferably, the operating temperature is 25-240℃, the operating pressure is 0.3MPaG; regeneration includes cold regeneration and / or hot regeneration.

[0018] According to the system of this utility model, preferably, the process parameters of the second adsorber during adsorption include: operating temperature -20~40℃, and operating pressure 0.5~3.5MPaG.

[0019] According to the system of this utility model, preferably, the process parameters for the second adsorber during regeneration include: operating temperature of 25–270°C and operating pressure of 0.05–0.5 MPaG; the regeneration gas can be nitrogen or a mixture of methane and hydrogen. More preferably, the operating temperature is 25–270°C and the operating pressure is 0.3 MPaG; regeneration includes cold regeneration and / or hot regeneration.

[0020] According to the system of this utility model, preferably, the aspect ratio of the first adsorber is (1-3):1.

[0021] According to the system of this invention, preferably, the pore size of the 3A molecular sieve is 0.3 nm.

[0022] According to the system of this invention, preferably, the aspect ratio of the second adsorber is (4-6):1.

[0023] According to the system of this utility model, preferably, the alkaline alumina balls have a particle size range of 5×8 mesh, and the stainless steel wire mesh filter has a mesh size of 80.

[0024] The system provided by this utility model has the advantages of high removal rate of moisture and acid gas, low residual water content and acid gas content in the purified ethylene gas, no waste alkali liquid and grease produced, and no waste chemical absorbent produced. Attached Figure Description

[0025] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, under the guidance of this invention, can select various possible shapes and proportions to implement this invention according to specific circumstances.

[0026] Figure 1 This is a schematic diagram of a system for removing moisture and acidic gases from crude ethylene gas in a preferred embodiment.

[0027] Explanation of reference numerals in the attached figures:

[0028] S1. Crude ethylene gas containing moisture and acidic gases is fed into the feed.

[0029] S2, Purified ethylene gas output after removing moisture and acidic gases;

[0030] S3, First adsorber desorption regeneration gas feed;

[0031] S4, First adsorber desorbs and regenerates the gas;

[0032] S5, Second Adsorber Desorption Regeneration Gas Feed;

[0033] S6, Second adsorber desorbs and regenerates the gas;

[0034] 11 / 13, First Adsorber;

[0035] 12 / 14, Second Adsorber;

[0036] 101~108 / 201~208, shut-off valve. Detailed Implementation

[0037] To more clearly illustrate this utility model, the preferred embodiments and accompanying drawings will be used for further description. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of this utility model.

[0038] The system for removing moisture and acidic gases from crude ethylene gas provided by this utility model includes: a crude ethylene gas inlet pipeline, a first adsorber, a second adsorber, and a purified ethylene gas outlet pipeline.

[0039] The crude ethylene gas feed line is connected to the first end of the first adsorber, the second end of the first adsorber is connected to the first end of the second adsorber, and the second end of the second adsorber is connected to the purified ethylene gas discharge line; the adsorbent of the first adsorber is 3A molecular sieve, and the adsorbent of the second adsorber is alkaline alumina balls; in the second adsorber, a stainless steel wire mesh filter is installed after the alkaline alumina ball adsorbent.

[0040] Crude ethylene gas containing moisture and acidic gases first enters the first adsorber for physical adsorption, absorbing the moisture. It then enters the second adsorber for chemical adsorption, absorbing the acidic gases, reducing the water and acidic gas content in the crude ethylene gas to below 1 ppm (mol). The acidic gases include CO2, H2S, and COS. Alkaline alumina balls can simultaneously adsorb polar components such as moisture and ethanol, but not non-polar components such as ethylene. Therefore, the crude ethylene gas must first pass through the first adsorber to remove moisture before entering the second adsorber to ensure the adsorption effect of the alkaline alumina balls on CO2. The alkaline substances on the alkaline alumina balls react with CO2 to form complexes. These complexes decompose at high temperatures, so the alkaline alumina balls can be regenerated by heating.

[0041] As understood by those skilled in the art, the 3A molecular sieve and alkaline alumina balls can be purchased commercially directly; the alkaline alumina balls can also be prepared by impregnating alkali metal bicarbonate (K2CO3, NaOH, etc.) solutions with alkali metal oxide content of 1-10 wt%.

[0042] like Figure 1As shown, in a preferred embodiment, the first adsorber 11 / 13 and the second adsorber 12 / 14 are respectively provided in two sets, and the two sets can be switched to perform adsorption and regeneration operations. That is, one set is in the adsorption state and the other set is in the regeneration state, so as to maintain the continuous and stable operation of the industrial production equipment at full load.

[0043] Specifically, the crude ethylene gas feed line can be switched to the first end of two sets of first adsorbers 11 / 13, the second end of the first adsorbers 11 / 13 can be switched to the first end of two sets of second adsorbers 12 / 14, and the second end of the two sets of second adsorbers 12 / 14 can be switched to the purified ethylene gas discharge line.

[0044] The system also includes a first adsorber regeneration gas inlet pipeline, a first adsorber regeneration gas outlet pipeline, a second adsorber regeneration gas inlet pipeline, and a second adsorber regeneration gas outlet pipeline, for regenerating the first adsorber and the second adsorber.

[0045] The first adsorber regeneration gas feed line can be switched to the second end of two sets of first adsorbers 11 / 13, and the first adsorber regeneration gas discharge line can be switched to the first end of two sets of first adsorbers 11 / 13; the regeneration gas feed direction is opposite to the crude ethylene gas feed direction. The second adsorber regeneration gas feed line can be switched to the second end of two sets of second adsorbers 12 / 14, and the second adsorber regeneration gas discharge line can be switched to the first end of two sets of second adsorbers 12 / 14; the regeneration gas feed direction is opposite to the crude ethylene gas feed direction. Each connecting line is equipped with a shut-off valve to enable switchable connections.

[0046] like Figure 1 As shown, shut-off valves 101 / 102 are open, and shut-off valves 201 / 202 are closed, allowing crude ethylene gas feed S1 containing moisture and acidic gas to enter the first adsorber 11. The moisture in the crude ethylene gas is physically adsorbed by the 3A molecular sieve adsorbent. Shut-off valve 105 is closed to prevent the desorption regeneration gas feed S3 (e.g., nitrogen) from entering the first adsorber 11; shut-off valve 106 is closed to prevent the crude ethylene gas feed S1 containing moisture and acidic gas from flowing out.

[0047] When shut-off valve 103 is opened and shut-off valve 203 is closed, the crude ethylene gas, after physical adsorption of moisture, enters the second adsorber 12 and undergoes chemical adsorption of acidic gases from the crude ethylene gas by the chemical adsorbent of alkaline alumina balls. To prevent the alkaline alumina balls from entering subsequent facilities, a stainless steel wire mesh filter is installed after the chemical adsorbent. The chemically adsorbed crude ethylene gas enters the stainless steel wire mesh filter for gas-solid separation, filtering the alkaline alumina balls.

[0048] When shut-off valve 104 is open and shut-off valve 204 is closed, purified ethylene gas S2, after the removal of moisture and acidic gases, is discharged to the outside. When shut-off valve 107 is closed, it prevents the desorption regeneration gas feed S5 (e.g., nitrogen) from entering the second adsorber 12; when shut-off valve 108 is closed, it prevents the crude ethylene gas after the removal of moisture from flowing out.

[0049] When shut-off valve 205 opens, the desorption regeneration gas feed S3 from outside the interface enters the first adsorber 13 and undergoes desorption and regeneration through the 3A molecular sieve adsorbent. When shut-off valve 206 opens, the desorption regeneration gas discharge S4 from the first adsorber is output to the outside.

[0050] When shut-off valve 207 opens, the desorption regeneration gas feed S5 from outside the interface enters the second adsorber 14 and undergoes desorption regeneration through alkaline alumina balls. When shut-off valve 208 opens, the desorption regeneration gas discharge S6 from the second adsorber is output to the outside.

[0051] Switching between adsorption and regeneration operations can be accomplished by reopening and closing the relevant shut-off valves. The first adsorber is configured with two sets of 11 / 13 units in parallel; adjusting the shut-off valves keeps one set in adsorption mode and the other in regeneration mode. Similarly, the second adsorber is configured with two sets of 12 / 14 units in parallel; adjusting the shut-off valves keeps one set in adsorption mode and the other in regeneration mode. This ensures continuous and stable full-load operation of the industrial production unit.

[0052] The process parameters for the first adsorber during adsorption are: operating temperature 15–40℃, operating pressure 0.8–4.0 MPaG; and the process parameters for regeneration are: operating temperature 25–240℃, operating pressure 0.05–0.5 MPaG. The aspect ratio of the first adsorber is 1.5:1; the pore size of the 3A molecular sieve is 0.3 nm. The process parameters for the second adsorber during adsorption are: operating temperature -20–40℃, operating pressure 0.5–3.5 MPaG; and the process parameters for regeneration are: operating temperature 25–270℃, operating pressure 0.05–0.5 MPaG. The aspect ratio of the second adsorber is 5:1, the particle size range of the alkaline alumina adsorbent balls is 5×8 mesh, and the stainless steel wire mesh filter is 80 mesh.

[0053] Application Example 1

[0054] The system for removing moisture and acidic gases from crude ethylene gas using this invention has a production scale of 360,000 tons / year for an ethanol dehydration to ethylene production unit. The composition of the crude ethylene gas entering the system of this invention is shown in Table 1 below.

[0055] Table 1. Composition of crude ethylene gas entering the system of this utility model.

[0056]

[0057] The process parameters for adsorption in this invention are as follows: the operating temperature of the first adsorber is 40℃, the operating pressure is 2.07MPaG, the length-to-diameter ratio of the first adsorber is 1.5:1, and the adsorbent is 3A molecular sieve; the operating temperature of the second adsorber is 40℃, the operating pressure is 2.04MPaG, the length-to-diameter ratio of the second adsorber is 5:1, and the chemical adsorbent is alkaline alumina balls.

[0058] The process parameters for desorption and regeneration are as follows: the operating temperature of the first adsorber is 25-240℃ and the operating pressure is 0.3MPaG; the operating temperature of the second adsorber is 25-270℃ and the operating pressure is 0.3MPaG.

[0059] Therefore, after the crude ethylene gas from the ethanol dehydration to ethylene production device is dehydrated and acidic by passing through the system of this invention, the purified ethylene gas has a water content and an acidic gas content of 1 ppm.

[0060] Comparative Example 1

[0061] The acid gas is removed by alkaline washing followed by water washing, which produces waste alkaline solution and grease, requiring additional treatment.

[0062] Comparative Example 2

[0063] The method of removing acidic gas by adsorption + absorption + adsorption has a low acidic gas removal rate, which can only remove the acidic gas content to ≤2ppm, and the chemical absorbent needs to be replaced frequently.

[0064] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.

Claims

1. A system for removing moisture and acid gases from a crude ethylene gas, comprising: The system comprises a crude ethylene gas feed pipeline, a first adsorber, a second adsorber, and a purified ethylene gas discharge pipeline. The crude ethylene gas feed pipeline is connected to the first end of the first adsorber, the second end of the first adsorber is connected to the first end of the second adsorber, and the second end of the second adsorber is connected to the purified ethylene gas discharge pipeline. The adsorbent of the first adsorber is 3A molecular sieve, and the adsorbent of the second adsorber is basic alumina ball; a stainless steel wire mesh filter is arranged after the basic alumina ball adsorbent in the second adsorber.

2. The system of claim 1, wherein, The first adsorber and the second adsorber each comprise two groups arranged in parallel, and the two groups are switchable for adsorption work and regeneration work.

3. The system of claim 2, wherein, The system further comprises a first adsorber regeneration gas feed pipeline, a first adsorber regeneration gas discharge pipeline, a second adsorber regeneration gas feed pipeline, and a second adsorber regeneration gas discharge pipeline. The first adsorber regeneration gas feed pipeline is switchably connected to the second end of the two groups of first adsorbers, and the first adsorber regeneration gas discharge pipeline is switchably connected to the first end of the two groups of first adsorbers. The second adsorber regeneration gas feed pipeline is switchably connected to the second end of the two groups of second adsorbers, and the second adsorber regeneration gas discharge pipeline is switchably connected to the first end of the two groups of second adsorbers.

4. The system of claim 2, wherein, The process parameters of the first adsorber during adsorption work include an operating temperature of 15-40℃ and an operating pressure of 0.8-4.0 MPaG.

5. The system of claim 2, wherein, The process parameters of the first adsorber during regeneration work include an operating temperature of 25-240℃ and an operating pressure of 0.05-0.5 MPaG.

6. The system of claim 2, wherein, The process parameters of the second adsorber during adsorption work include an operating temperature of -20-40℃ and an operating pressure of 0.5-3.5 MPaG.

7. The system of claim 2, wherein, The process parameters of the second adsorber during regeneration work include an operating temperature of 25-270℃ and an operating pressure of 0.05-0.5 MPaG.

8. The system of claim 1, wherein, The aspect ratio of the first adsorber is (1-3):

1.

9. The system of claim 1, wherein, The particle size range of the basic alumina ball is 5×8 mesh, and the stainless steel wire mesh filter is 80 mesh.

10. The system of claim 1, wherein, The aspect ratio of the second adsorber is (4-6):1.

Images