An apparatus for producing methyl methacrylate from coal

Abstract

This utility model relates to a coal-based apparatus for producing methyl methacrylate; it includes a raw coal bunker and an oxygen pipeline, which are respectively connected to the inlet of a gasification unit. The outlet of the gasification unit is connected to both a non-shifted gas scrubbing unit and a shifted gas scrubbing unit. The outlet of the non-shifted gas scrubbing unit is connected to a methanol synthesis unit, which is connected to a methanol-to-olefins unit, which is connected to a propionaldehyde synthesis unit, which is connected to a methacrolein synthesis unit, and finally, the methacrolein synthesis unit is connected to a methyl methacrylate synthesis unit. This apparatus achieves the goal of conforming to my country's energy structure and reducing dependence on foreign oil, while also extending the coal chemical industry chain to increase product added value and enhance the competitiveness of coal chemical enterprises.

Description

Technical Field

[0001] This utility model belongs to the field of coal chemical industry extension technology, specifically a device for producing methyl methacrylate from coal. Background Technology

[0002] Methyl methacrylate (MMA) is mainly used in the synthesis of polymethyl methacrylate (PMMA, plexiglass). In recent years, with the rapid development of my country's photovoltaic industry and the expanding application of PMMA materials in photovoltaic panels, the demand for MMA has been continuously increasing. However, the current production of MMA is mostly concentrated in petrochemical enterprises, heavily reliant on petroleum resources. Due to my country's energy structure of being rich in coal, poor in oil, and lacking in gas, the dependence on imported MMA is relatively high. Therefore, there is an urgent need to develop a process for producing MMA from coal. Utility Model Content

[0003] To overcome the above deficiencies, this utility model provides a coal-based apparatus for producing methyl methacrylate, thereby solving the technical problems existing in the prior art.

[0004] The technical solution adopted by this utility model to solve its technical problem is:

[0005] A coal-based apparatus for producing methyl methacrylate, the apparatus comprising a raw coal bunker and an oxygen pipeline, the raw coal bunker and the oxygen pipeline being connected to the inlet of a gasification unit, and the outlet of the gasification unit being connected to an unconverted gas scrubbing unit and a converted gas scrubbing unit, respectively.

[0006] The outlet of the unshifted gas scrubbing unit is connected to the methanol synthesis unit via the second and third three-way valves. The methanol synthesis unit is connected to the methanol-to-olefins unit via the third and fourth-way valves. The outlet of the methanol-to-olefins unit is connected to the propionaldehyde synthesis unit via the fourth and fifth three-way valves. The outlet of the propionaldehyde synthesis unit is connected to the methacrolein synthesis unit via the sixth three-way valve. The outlet of the methacrolein synthesis unit is connected to the methyl methacrylate synthesis unit via the fourth and fourth-way valves. The outlet of the shifted gas scrubbing unit is connected to the third end of the second and fourth-way valves via the second and third-way valves. The third ends of the second and fourth-way valves are connected to the thirteenth three-way valve, and the third end of the thirteenth three-way valve is connected to the fifth three-way valve via the seventh three-way valve. The third end of the third and fourth-way valves is connected to the sixth three-way valve via the formaldehyde synthesis unit. The oxygen pipeline is connected to the third end of the fourth and fourth-way valves, and the fourth end of the third and fourth-way valves is connected to the fourth end of the fourth and fourth-way valves.

[0007] The beneficial effects of this utility model are as follows: This utility model uses coal as raw material and is based on traditional methanol synthesis. It realizes the production of methyl methacrylate through gasification, purification and synthesis processes. It not only achieves the goal of conforming to my country's energy structure and reducing dependence on foreign oil, but also extends the coal chemical industry chain to improve the added value of products and the competitiveness of coal chemical enterprises.

[0008] Preferably, the third end of the fourth three-way valve is connected to the acrylic acid synthesis unit through the eighth three-way valve and the eleventh three-way valve, the outlet of the acrylic acid synthesis unit is connected to the butyl acrylate synthesis unit through the twelfth three-way valve, and the oxygen pipeline is also connected to the third end of the eleventh three-way valve.

[0009] Preferably, the third end of the seventh three-way valve is connected to the butyraldehyde synthesis unit through the ninth three-way valve, and the butyraldehyde synthesis unit is connected to the third end of the twelfth three-way valve through the thirteenth three-way valve and the butanol synthesis unit; the third end of the eighth three-way valve is connected to the third end of the ninth three-way valve; and the fourth end of the second four-way valve is connected to the third end of the thirteenth three-way valve through the PSA hydrogen extraction unit.

[0010] Preferably, the oxygen pipeline is connected to the main oxygen pipeline outlet of the air separation unit via a first four-way valve, and the inlet of the air separation unit is connected to the atmosphere.

[0011] Preferably, the outlet of the gasification unit is connected to both the unconverted gas scrubbing unit and the converted gas scrubbing unit via a first tee.

[0012] Preferably, a heat recovery unit is provided between the first three-way valve and the unconverted gas washing unit.

[0013] Preferably, a conversion and heat recovery unit is provided between the first three-way valve and the conversion gas washing unit.

[0014] A coal-based apparatus for producing methyl methacrylate (MMA) according to the above scheme prepares MMA for the synthesis of plexiglass using coal as a raw material, aiming to align with my country's energy structure. Furthermore, based on the traditional methanol synthesis process, this invention, through gasification, purification, and synthesis steps, not only produces MMA but also co-produces butyl acrylate. Butyl acrylate is mainly used in the production of polymer monomers for fibers, rubber, and plastics; in the organic industry, it is used to manufacture adhesives, emulsifiers, and as an intermediate in organic synthesis; and in the paper industry, it is used to manufacture paper strengthening agents. The above process setup allows for flexible adjustment of the final product output according to market conditions, reducing dependence on imported oil and extending the coal chemical industry chain to increase product added value and enhance the competitiveness of coal chemical enterprises. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of this utility model.

[0017] In the diagram: 1. Raw coal bunker; 2. Air separation unit; 3. Gasification unit; 4. Heat recovery unit; 5. Shift conversion and heat recovery unit; 6. Unshifted gas scrubbing unit; 7. Shifted gas scrubbing unit; 8. Methanol synthesis unit; 9. Methanol to olefins unit; 10. Formaldehyde synthesis unit; 11. Propanal synthesis unit; 12. Methacrolein synthesis unit; 13. Methyl methacrylate synthesis unit; 14. PSA hydrogen extraction unit; 15. Butyraldehyde synthesis unit; 16. Butanol synthesis unit; 17. Acrylic acid synthesis unit; 18. Butyl acrylate synthesis unit; 19. First tee; 20. Second tee; 21. Third tee; 22. Fourth tee; 23. Fifth tee; 24. Sixth tee; 25. Seventh tee; 26. Eighth tee; 27. Ninth tee; 28. Thirteenth tee; 29. ​​Eleventh tee; 30. Twelfth tee; 31. Thirteenth tee; 32. First four-way connector; 33. Second four-way connector; 34. Third four-way connector; 35. Fourth four-way connector. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0019] The following is in conjunction with the appendix Figure 1This application provides a further detailed description of an apparatus for producing methyl methacrylate from coal. The apparatus includes a raw coal bunker 1 and an oxygen pipeline. The raw coal bunker 1 and the oxygen pipeline are connected to the inlet of a gasification unit 3. The outlet of the gasification unit 3 is connected to a non-shifted gas scrubbing unit 6 and a shifted gas scrubbing unit 7. The outlet of the non-shifted gas scrubbing unit 6 is connected to a methanol synthesis unit 8 via a second three-way valve 20 and a third three-way valve 21. The methanol synthesis unit 8 is connected to a methanol-to-olefins unit 9 via a third four-way valve 34. The outlet of the methanol-to-olefins unit 9 is connected to a propionaldehyde synthesis unit 11 via a fourth three-way valve 22 and a fifth three-way valve 23. The outlet of the propionaldehyde synthesis unit 11 is connected to a sixth three-way valve 23. The three-way valve 24 is connected to the methacrolein synthesis unit 12, and the outlet of the methacrolein synthesis unit 12 is connected to the methyl methacrylate synthesis unit 13 through the fourth four-way valve 35; the outlet of the shift gas scrubbing unit 7 is connected to the third end of the third three-way valve 21 through the second four-way valve 33, and the third ends of the second four-way valve 33 and the second three-way valve 20 are respectively connected to the thirteenth three-way valve 31, and the third end of the thirteenth three-way valve 31 is connected to the fifth three-way valve 23 through the seventh three-way valve 25; the third end of the third four-way valve 34 is connected to the sixth three-way valve 24 through the formaldehyde synthesis unit 10; the oxygen pipeline is connected to the third end of the fourth four-way valve 35, and the fourth end of the third four-way valve 34 is connected to the fourth end of the fourth four-way valve 35. This invention uses coal and oxygen as raw materials to prepare methyl methacrylate, which is traditionally prepared using petroleum as a raw material. The oxygen can be purchased externally or obtained by separating air using an air separation device. Furthermore, this invention relies on the traditional methanol synthesis process, which can effectively reduce the cost of investment and modification, and lay the foundation for setting subsequent process parameters. The gasification unit mentioned in this invention includes, but is not limited to, coal-water slurry gasification and pulverized coal gasification, with a gasification temperature of 800-1500℃. The unshifted gas scrubbing unit 6 includes, but is not limited to, a methanol scrubbing tower, a CO2 stripping tower, and a methanol thermal regeneration tower; the shifted gas scrubbing unit 7 includes, but is not limited to, a methanol scrubbing tower, a CO2 stripping tower, and a methanol thermal regeneration tower; the methanol synthesis unit 8 includes, but is not limited to, a methanol synthesis tower, a methanol water cooler, and a circulating gas compressor; the methanol-to-olefins unit 9 includes, but is not limited to, a reactor, a water scrubbing tower, a quench tower, and a wastewater stripping tower; the formaldehyde synthesis unit 10 includes, but is not limited to, an oxidation furnace, an absorption tower, a catalytic oxidation reactor, and a blower; the propionaldehyde synthesis unit 11 includes, but is not limited to, a hydroformylation reactor, a propionaldehyde absorption tower, an ethylene stripping tower, a propionaldehyde stabilization tower, and a propionaldehyde distillation tower; the methacrolein synthesis unit 12 includes, but is not limited to, an aldol condensation reactor, a propionaldehyde recovery tower, a methacrolein de-heavy tower, and a methacrolein recovery tower; the methyl methacrylate synthesis unit 13 includes, but is not limited to, an aldehyde oxidation reactor, an MMA extraction tower, an MMA deacidification tower, and an MMA de-heavy tower. The above equipment can be purchased directly from the market and is not the focus of this utility model's protection; therefore, it will not be described in detail further.The technical solution of this utility model is in line with my country's energy structure. While ensuring the development of the polymethyl methacrylate (plexiglass) industry, it reduces the dependence on oil, extends the industrial chain of the coal chemical industry, and increases the added value of coal chemical products.

[0020] Furthermore, the third end of the fourth three-way valve 22 is connected to the acrylic acid synthesis unit 17 via the eighth three-way valve 26 and the eleventh three-way valve 29. The outlet of the acrylic acid synthesis unit 17, the twelfth three-way valve 30, is connected to the butyl acrylate synthesis unit 18. The oxygen pipeline is also connected to the third end of the eleventh three-way valve 29. This invention can not only produce methyl methacrylate but also co-produce butyl acrylate. The production of butyl acrylate in this invention also relies on the traditional methanol synthesis process. By co-producing methyl methacrylate and butyl acrylate, the final product output can be flexibly adjusted according to market conditions, thereby improving the competitiveness and risk resistance of coal chemical enterprises. The acrylic acid synthesis unit 17 in this invention includes, but is not limited to, an oxidation reactor, an absorption tower, a light component removal tower, and an acrylic acid refining tower. The butyl acrylate synthesis unit 18 includes, but is not limited to, an esterification reactor, a butyl acrylate refining tower, and an alcohol recovery tower. The above equipment can be purchased directly on the market and is not the focus of this invention, so it will not be described in detail.

[0021] Furthermore, the third end of the seventh three-way valve 25 is connected to the butyraldehyde synthesis unit 15 via the ninth three-way valve 27, and the butyraldehyde synthesis unit 15 is connected to the third end of the twelfth three-way valve 30 via the thirteenth three-way valve 28 and the butanol synthesis unit 16; the third end of the eighth three-way valve 26 is connected to the third end of the ninth three-way valve 27; and the fourth end of the second four-way valve 33 is connected to the third end of the thirteenth three-way valve 28 via the PSA hydrogen extraction unit 14. The butyraldehyde synthesis unit 15 described in this invention includes, but is not limited to, a carbonyl synthesis reactor, a falling film evaporator separator, a stripping tower, and a stabilization tower; the butanol synthesis unit 16 is not limited to, but is not limited to, a hydrogenation reactor and a product purification tower; the PSA hydrogen extraction unit 14 includes, but is not limited to, an adsorption tower, a desorption gas buffer tank, and a forward-release gas buffer tank. The above equipment can be purchased directly from the market and is not the focus of this invention's protection; therefore, it will not be described in detail further.

[0022] Furthermore, the oxygen pipeline is connected to the main oxygen pipeline outlet of the air separation unit 2 via the first four-way connector 32, and the inlet of the air separation unit 2 is connected to the atmosphere. The air separation unit 2 includes a preliminary purification system, ensuring the air is dust-free and oil-free; the oxygen purity after separation by the air separation unit 2 is greater than 99.6%.

[0023] Furthermore, the outlet of the gasification unit 3 is connected to the unconverted gas scrubbing unit 6 and the converted gas scrubbing unit 7 respectively via the first tee 19.

[0024] Furthermore, a heat recovery unit 4 is provided between the first three-way valve 19 and the unconverted gas washing unit 6. The heat recovery unit 4 described in this utility model includes, but is not limited to, waste boilers, gas-liquid separators, ammonia washing towers, etc. The above-mentioned equipment can be purchased directly on the market and is not the focus of protection of this utility model, so it will not be described in detail.

[0025] Furthermore, a conversion and heat recovery unit 5 is provided between the first three-way valve 19 and the gas conversion and washing unit 7. The conversion and heat recovery unit 5 described in this utility model includes, but is not limited to, a conversion furnace, a waste boiler, a gas-liquid separator, an ammonia washing tower, etc. The above-mentioned equipment can be purchased directly on the market and is not the focus of protection of this utility model, so it will not be described in detail.

[0026] The specific working process of this utility model is as follows: Air is separated into oxygen and nitrogen in air separation unit 2. Coal from raw coal bunker 1 and high-pressure pure oxygen separated from air separation unit 2 enter gasification unit 3 together, and after incomplete combustion, raw material gas containing components such as CO, CO2, H2, and H2O is obtained. Part of the raw material gas enters heat recovery unit 4 and unconverted gas scrubbing unit 6, and another part of the raw material gas enters conversion and heat recovery unit 5 and gas exchange scrubbing unit 7 to obtain high-purity H2. Part of the purified gas from the outlet of unconverted gas scrubbing unit 6 and part of the purified gas from conversion gas scrubbing unit 7 are controlled by corresponding valves to obtain mixed gases with H2 / (CO+CO2)=2 and H2:CO=1, respectively. Part of the purified gas from the outlet of conversion gas scrubbing unit 7 is sent to PSA hydrogen extraction unit 14, where pure hydrogen is separated. H2 / (CO+CO2)=2 is the raw material gas for methanol synthesis unit 8, and the synthesized methanol is used as the raw material for methanol-to-olefins unit 9, formaldehyde synthesis unit 10, and methyl methacrylate synthesis unit 13, respectively. The main products of methanol-to-olefins unit 9 are ethylene and propylene. Ethylene reacts with syngas (H2:CO = 1) in propionaldehyde synthesis unit 11 to obtain propionaldehyde. Propionaldehyde reacts with formaldehyde in methacrolein synthesis unit 12 to obtain methacrolein. Methacrolein, methanol, and oxygen react in methyl methacrylate synthesis unit 13 to obtain methyl methacrylate. Propylene serves as a raw material for the synthesis of butanol and acrylic acid. A portion of the propylene from methanol-to-olefins unit 9 reacts with syngas (H2:CO = 1) in butanol synthesis unit 15 to obtain butanol. Butanol reacts with high-purity hydrogen in butanol synthesis unit 16 to obtain butanol. Another portion of propylene reacts with oxygen in acrylic acid synthesis unit 17 to obtain acrylic acid. Acrylic acid and butanol react in butyl acrylate synthesis unit 18 to produce butyl acrylate. Specifically, the method for the combined production of methyl methacrylate and butyl acrylate using this invention includes the following steps:

[0027] Step 1: Air is separated into nitrogen and oxygen in air separation unit 2. The oxygen can be sent to gasification unit 3, methyl methacrylate synthesis unit 13 and acrylic acid synthesis unit 17 through oxygen pipelines as raw materials. The air separation unit includes a preliminary purification system, requiring that the air be dust-free and oil-free. The oxygen purity after separation in air separation unit 2 is greater than 99.6%. Step 2: The raw coal from coal bunker 1 and the aforementioned oxygen undergo incomplete combustion in gasification unit 3 to obtain raw material gas. The preferred gasification temperature in gasification unit 3 is 800-1500℃. Step 3: Part of the raw material gas passes through heat recovery unit 4 to recover heat, and then enters unconverted gas scrubbing unit 6 to remove H2S and CO2, obtaining purified gas. Step 4: Part of the raw material gas passes through conversion and heat recovery unit 5 and conversion gas scrubbing unit 7 to obtain converted purified gas with an H2 purity of 97-99.5%. Step 5: The purified gas from the outlet of unconverted gas scrubbing unit 6 and the converted purified gas from the outlet of conversion gas scrubbing unit 7 are controlled by valves to obtain synthesis gases with H2 / (CO+CO2) = 2 and H2:CO = 1, respectively. Step 6: The aforementioned synthesis gas with H2 / (CO+CO2) = 2 enters methanol synthesis unit 8 to synthesize methanol. The reaction temperature in methanol synthesis unit 8 is 200-400℃, and the pressure is 4-6 MPaG. Step 7: A portion of the methanol obtained in Step 6 reacts in methanol-to-olefins unit 9 to produce ethylene and propylene at a reaction temperature of 350-650℃ and a reaction pressure of 0.1-0.35 MPaG. Step 8: Another portion of the methanol obtained in Step 6 reacts in formaldehyde synthesis unit 10 to produce formaldehyde at a reaction temperature of 180-300℃ and a reaction pressure of 50-80 kPaG. Step 9: The synthesis gas from the aforementioned ethylene and H2:CO=1 reacts in propionaldehyde synthesis unit 11 to produce propionaldehyde at a reaction temperature of 80-200℃ and a reaction pressure of 0.5-2 MPaG. Step 10: Propanal and formaldehyde react in methacrolein synthesis unit 12 to produce methacrolein at a reaction temperature of 40-100℃ and a reaction pressure of 0.1-0.25 MPaG. Step 11: Methacrolein, methanol, and oxygen react in methyl methacrylate synthesis unit 13 to obtain methyl methacrylate (MMA) at a reaction temperature of 100-350℃ and a reaction pressure of 0.2-0.8 MPaG. Step 12: The propylene and the aforementioned H2:CO=1 synthesis gas undergo a carbonylation reaction in butyraldehyde synthesis unit 15 to obtain butyraldehyde at a reaction temperature of 60-130℃ and a reaction pressure of 1.5-3 MPaG.Step Thirteen: The purified gas from the outlet of the shift gas scrubbing unit 7 has a hydrogen purity >97%. After passing through the PSA hydrogen extraction unit 14, hydrogen with a purity ≥99% is obtained. The PSA hydrogen extraction unit 14 includes an adsorption tower with a temperature of 20-40℃ and a pressure of 2-6 MPaG. Step Fourteen: Butyraldehyde and hydrogen with a purity ≥99% react in the butanol synthesis unit 16 to obtain butanol. The reaction temperature is 60-150℃, and the reaction pressure is 2-3 MPaG. Step Fifteen: Propylene and oxygen react in the acrylic acid synthesis unit 17 to obtain acrylic acid. The reaction temperature is 300-400℃, and the reaction pressure is 0.05-0.2 MPaG. Step Sixteen: Acrylic acid and butanol react in the butyl acrylate synthesis unit 18 to obtain butyl acrylate. The catalyst is an inorganic strong acid, p-toluenesulfonic acid, a solid acid, or a cation exchange resin. The reaction temperature is 70-190℃, and the reaction vacuum is controlled at -0.08 to -0.05 MPa. This invention aligns well with my country's energy structure, which is characterized by abundant coal, scarce oil, and limited gas resources. It is particularly suitable for coal chemical enterprises to simultaneously produce methyl methacrylate and butyl acrylate, creating opportunities for them to enter the high-end materials field. Specifically, this invention uses coal and air as raw materials. Building upon traditional methanol synthesis, it further utilizes methanol-to-olefins and formaldehyde synthesis processes, combined with high-purity hydrogen obtained from a PSA hydrogen extraction unit, to simultaneously produce methyl methacrylate and butyl acrylate. This process boasts advantages such as a rational and simple overall design, tight coupling and integration, short process flow, and high product added value.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A plant for the coal-based production of methyl methacrylate, comprising a raw coal bin (1) and an oxygen pipeline, characterized in that: The raw coal bunker (1) and the oxygen pipeline are connected to the inlet of the gasification unit (3) respectively, and the outlet of the gasification unit (3) is connected to the unconverted gas washing unit (6) and the converted gas washing unit (7) respectively. The outlet of the unconverted gas washing unit (6) is connected to the methanol synthesis unit (8) through the second three-way valve (20) and the third three-way valve (21). The methanol synthesis unit (8) is connected to the methanol-to-olefins unit (9) through the third four-way valve (34). The outlet of the methanol-to-olefins unit (9) is connected to the propionaldehyde synthesis unit (11) through the fourth three-way valve (22) and the fifth three-way valve (23). The outlet of the propionaldehyde synthesis unit (11) is connected to the methacrolein synthesis unit (12) through the sixth three-way valve (24). The outlet of the methacrolein synthesis unit (12) is connected to the methyl methacrylate synthesis unit (13) through the fourth four-way valve (35). The outlet of the air-changing washing unit (7) is connected to the third end of the third three-way (21) through the second four-way (33), the third end of the second four-way (33) and the third end of the second three-way (20) are respectively connected to the thirteenth three-way (31), and the third end of the thirteenth three-way (31) is connected to the fifth three-way (23) through the seventh three-way (25). The third end of the third four-way connector (34) is connected to the sixth three-way connector (24) through the formaldehyde synthesis unit (10); The oxygen pipe is connected to the third end of the fourth four-way connector (35), and the fourth end of the third four-way connector (34) is connected to the fourth end of the fourth four-way connector (35).

2. A plant for the coal based production of methyl methacrylate according to claim 1, characterized in that: The third end of the fourth tee (22) is connected to the acrylic acid synthesis unit (17) via the eighth tee (26) and the eleventh tee (29). The outlet of the acrylic acid synthesis unit (17) is connected to the butyl acrylate synthesis unit (18) via the twelfth tee (30). The oxygen pipeline is also connected to the third end of the eleventh tee (29).

3. A coal based plant for producing methyl methacrylate as claimed in claim 2 wherein: The third end of the seventh three-way connector (25) is connected to the butyraldehyde synthesis unit (15) through the ninth three-way connector (27), and the butyraldehyde synthesis unit (15) is connected to the third end of the twelfth three-way connector (30) through the thirteenth three-way connector (28) and the butanol synthesis unit (16). The third end of the eighth tee (26) is connected to the third end of the ninth tee (27); The fourth end of the second four-way (33) is connected to the third end of the thirteenth way (28) through the PSA hydrogen extraction unit (14).

4. A plant for the coal based production of methyl methacrylate according to claim 2, characterized in that: The oxygen pipeline is connected to the main oxygen pipeline outlet of the air separation unit (2) via the first four-way valve (32), and the inlet of the air separation unit (2) is connected to the atmosphere.

5. A plant for the coal based production of methyl methacrylate according to claim 1, characterized in that: The outlet of the gasification unit (3) is connected to the unchanging gas scrubbing unit (6) and the changing gas scrubbing unit (7) respectively through the first tee (19).

6. The apparatus for producing methyl methacrylate from coal according to claim 5, characterized in that: A heat recovery unit (4) is provided between the first three-way valve (19) and the unconverted gas washing unit (6).

7. The apparatus for producing methyl methacrylate from coal according to claim 5, characterized in that: A conversion and heat recovery unit (5) is provided between the first three-way valve (19) and the gas conversion and washing unit (7).

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