Ammonia-alcohol separation device and method for co-production of dimethyl oxalate and oxamide

Abstract

The invention discloses an ammonia-alcohol separation device which comprises a methanol absorption section, a methanol condensation extraction section, an ammonia absorption section and an ammonia absorption raw material preparation section which are sequentially arranged from top to bottom, the methanol absorption section absorbs methanol in gas through desalted water, and methanol extracted from the methanol condensation extraction section is sent to a dimethyl oxalate synthesis device; the ammonia absorption section is used for absorbing ammonia in the gas through a methanol solution of dimethyl oxalate. The device further comprises a dimethyl oxalate rectification device and an oxamide synthesis device. The chemical reaction in the oxamide production process is used for replacing rectification and washing procedures in the prior art, and complete conversion of ammonia, internal circulation of methyl alcohol in the dimethyl oxalate synthesis and oxamide co-production device and effective utilization of low-level heat energy of dimethyl oxalate are achieved. The invention also discloses a method for co-production of dimethyl oxalate and oxamide by using the ammonia-alcohol separation device.

Description

Technical Field

[0001] The invention relates to the field of tail gas treatment, in particular to an ammonia-alcohol separation device. Background Art

[0002] Oxamide is an important organic compound. In the agricultural field, it is an efficient slow-release nitrogen fertilizer that can supply the nitrogen elements needed by crops. In the pharmaceutical field, it is an important raw material for synthesizing peptides and proteins, and it is also an important raw material for synthesizing polyamide polymer materials.

[0003] The most promising production method in the industry is to use dimethyl oxalate and ammonia to prepare oxamide. In the process of preparing oxamide by ammonolysis of dimethyl oxalate, in order to ensure the purity of oxamide, an excess of ammonia is required. Therefore, in the subsequent separation and drying process, the tail gas generally contains nitrogen, methanol and ammonia.

[0004] Plants that use synthesis gas to produce dimethyl oxalate and oxalamide in combination generally use carbon monoxide as the raw material and use the gas phase coupling method to produce dimethyl oxalate. For every 1 mole of dimethyl oxalate produced, 2 moles of methanol are consumed; correspondingly, for every 1 mole of oxalamide produced, 1 mole of dimethyl oxalate is consumed and 2 moles of methanol are produced as a by-product. It can be seen that if synthesis gas is used as the raw material to produce dimethyl oxalate and then ammonolyzed to produce oxalamide, methanol can be regarded as an intermediate circulation product.

[0005] The existing ammonia-alcohol gas separation scheme in the oxalamide production process mostly adopts the method of condensing methanol and ammonia into liquids, and then separating methanol and ammonia by distillation. The separated ammonia is compressed and returned to the front-end dimethyl oxalate ammonolysis process for preparing oxalamide. The separated methanol generally contains trace amounts of ammonia. This part of methanol needs to be further deammonified before returning to the dimethyl oxalate synthesis unit or sold as a methanol product. This technical solution has the disadvantages of large equipment investment and high steam and circulating water consumption.

[0006] Therefore, how to overcome the above technical defects is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide an ammonia-alcohol separation device, which uses a chemical method to achieve the complete conversion of ammonia and the recycling of methanol between a dimethyl oxalate synthesis device and an oxalamide synthesis device. Another object of the present invention is to provide a method for co-producing oxalamide from dimethyl oxalate using the ammonia-alcohol separation device.

[0008] In order to solve the above technical problems, the present invention provides an ammonia-alcohol separation device, comprising a methanol absorption section, a methanol condensation and production section, an ammonia absorption section and an ammonia absorption raw material preparation section which are arranged in sequence from top to bottom, wherein the methanol absorption section absorbs methanol in the gas through desalted water, the methanol produced by the methanol condensation and production section is sent to a dimethyl oxalate synthesis device, and the ammonia absorption section absorbs ammonia in the gas through a methanol solution of dimethyl oxalate. The device also includes a dimethyl oxalate distillation device and an oxalamide synthesis device, wherein the dimethyl oxalate distillation device is used to output dimethyl oxalate at a preset temperature, and the oxalamide synthesis device is used to produce oxalamide, and the methanol and ammonia produced in the production process are sent to corresponding positions.

[0009] Preferably, the methanol absorption section includes a first cylinder, an upper head is provided at the upper end of the first cylinder, a first isolation tower plate is provided at the lower end of the first cylinder, and a desalted water nozzle, a methanol absorption first filler, a circulating water solution nozzle, a methanol absorption second filler and a first riser are arranged in the first cylinder from top to bottom.

[0010] Preferably, the upper cover is provided with a gas exhaust port, a nitrogen inlet and a pressure gauge port, the first cylinder side wall is provided with a desalted water inlet, a circulating water solution inlet, a first overflow port and a circulating water solution outlet in sequence from top to bottom, and the first cylinder side wall is also provided with a first liquid level gauge upper interface, a first liquid level gauge lower interface and a first thermometer interface.

[0011] Preferably, the methanol condensation and production section includes a second cylinder and a heat exchange tube bundle, a baffle and a second riser installed inside the second cylinder, a second isolation tower plate is arranged below the second cylinder, the heat exchange tube bundle is arranged vertically, and a plurality of baffles are arranged alternately horizontally.

[0012] Preferably, the side wall of the second cylinder is provided with a coolant inlet, a coolant outlet, a second overflow port and a methanol production port in sequence from top to bottom, and the side wall of the second cylinder is also provided with a second liquid level gauge upper interface, a second thermometer interface and a second liquid level gauge lower interface in sequence from top to bottom.

[0013] Preferably, the ammonia absorption section includes a third cylinder, in which a first baffle, a sieve plate tray and a second baffle are arranged, the first baffle is arranged at the upper end of the third cylinder, the second baffle is arranged at the middle end of the third cylinder, and a plurality of sieve plate trays are arranged alternately horizontally.

[0014] Preferably, the side wall of the third cylinder is provided with a dimethyl oxalate methanol liquid inlet, a circulating absorption liquid inlet and an exhaust gas inlet in sequence from top to bottom.

[0015] Preferably, the ammonia absorption raw material preparation section includes a fourth cylinder, and a liquid guide plate and a partition are arranged in the fourth cylinder. The liquid guide plate is obliquely arranged at the upper end of the fourth cylinder, and the partition is vertically arranged at the lower end of the fourth cylinder.

[0016] Preferably, the side wall of the fourth cylinder located on the left side of the partition is provided with a dimethyl oxalate inlet and a methanol inlet in sequence from top to bottom, the fourth cylinder located on the left side of the partition is provided with a dimethyl oxalate methanol solution outlet, the fourth cylinder located on the right side of the partition is provided with a circulating absorption liquid outlet, the side wall of the fourth cylinder located on the left side of the partition is provided with a third liquid level gauge upper interface, a third thermometer interface and a third liquid level gauge lower interface in sequence from top to bottom, and the side wall of the fourth cylinder located on the right side of the partition is provided with a fourth liquid level gauge upper interface, a fourth thermometer interface and a fourth liquid level gauge lower interface in sequence from top to bottom.

[0017] The present invention provides a method for co-producing oxalamide from dimethyl oxalate, using the ammonia-alcohol separation device as described in any one of the above, comprising the steps of:

[0018] S1: Directly introduce dimethyl oxalate at 135°C from the dimethyl oxalate heat exchanger of the dimethyl oxalate distillation unit to the dimethyl oxalate inlet in the ammonia absorption raw material preparation section, and mix it with the methanol produced from the methanol production outlet;

[0019] S2: The methanol solution of dimethyl oxalate is pumped out from the outlet of the dimethyl oxalate methanol solution to the inlet of the dimethyl oxalate methanol solution and flows downward, reacts with ammonia in the tail gas generated by the oxalamide synthesis unit to produce oxalamide, and flows into the right area of ​​the partition of the ammonia absorption raw material preparation section, and then is pumped out from the outlet of the circulating absorption liquid, a part of which goes to the oxalamide reactor of the oxalamide synthesis unit, and a part of which goes to the inlet of the circulating absorption liquid to absorb ammonia in the tail gas of the oxalamide synthesis unit;

[0020] S3: Ammonia-free methanol gas and nitrogen enter the methanol condensation and production section from the second riser pipe. Most of the methanol is condensed in the methanol condensation and production section and collected above the second isolation tower plate. A portion of the methanol is pumped from the methanol production outlet to the methanol inlet of the ammonia absorption raw material preparation section to mix with dimethyl oxalate; the other portion is pumped to the dimethyl oxalate synthesis section to produce crude dimethyl oxalate. The crude dimethyl oxalate is refined in the dimethyl oxalate distillation unit and then sent to the oxalamide synthesis unit and the ammonia-alcohol separation unit, thereby realizing the circulation of methanol among the ammonia-alcohol separation unit, the dimethyl oxalate unit and the oxalamide synthesis unit;

[0021] S4: Pumping out the circulating absorption liquid of the oxalamide reactor of the oxalamide synthesis unit to react with excess ammonia to generate oxalamide, and the material discharged from the oxalamide synthesis reactor contains oxalamide, methanol and ammonia;

[0022] S5: The material discharged from the oxalamide reactor of the oxalamide synthesis unit is flashed, filtered and dried to obtain oxalamide powder. The gases containing methanol, ammonia and nitrogen generated in the process are all sent to the ammonia-alcohol separation unit, so that ammonia is completely converted into oxalamide products between the ammonia-alcohol separation unit and the oxalamide synthesis unit. The liquid containing methanol and ammonia generated by the oxalamide synthesis unit is heated to a certain temperature and then enters the lower part of the ammonia absorption section of the ammonia-alcohol separation unit to achieve ammonia-alcohol separation.

[0023] The invention provides an ammonia-alcohol separation device, comprising a methanol absorption section, a methanol condensation and extraction section, an ammonia absorption section and an ammonia absorption raw material preparation section which are sequentially arranged from top to bottom, wherein the methanol absorption section absorbs methanol in gas through desalted water, the methanol extracted by the methanol condensation and extraction section is sent to a dimethyl oxalate synthesis device, the ammonia absorption section absorbs ammonia in gas through a methanol solution of dimethyl oxalate, and further comprises a dimethyl oxalate distillation device and an oxamide synthesis device, wherein the dimethyl oxalate distillation device is used for outputting dimethyl oxalate of a preset temperature, and the oxamide synthesis device is used for producing oxamide, and methanol, ammonia and the like generated in the production process are sent to the ammonia-alcohol separation device.

[0024] The dimethyl oxalate introduced from the dimethyl oxalate production device is used as a raw material to produce oxamide, and all tail gas generated in the oxamide synthesis device is collected and transported to the ammonia-alcohol separation device. In the ammonia-alcohol separation device, dimethyl oxalate and ammonia in the tail gas react to produce oxamide and are pumped into the oxamide synthesis reactor to achieve complete conversion of ammonia; the methanol tail gas that does not contain ammonia is condensed in the ammonia-alcohol separation device provided by the present invention and pumped to the dimethyl oxalate synthesis device as a raw material for dimethyl oxalate synthesis, thereby achieving internal circulation of methanol in the dimethyl oxalate synthesis and oxamide production device; finally, the tail gas containing a small amount of methanol is washed with a circulating aqueous solution and desalted water, and the washed water is sent to the sewage treatment device to supplement the carbon source. The chemical reaction in the oxamide production process replaces the distillation and washing steps in the prior art solution, thereby achieving complete conversion of ammonia, internal circulation of methanol in the dimethyl oxalate synthesis and oxamide production device, and effective utilization of the low-level thermal energy of dimethyl oxalate.

[0025] The present invention also provides a method for co-producing oxalamide from dimethyl oxalate using the above-mentioned ammonia-alcohol separation device. Since the above-mentioned ammonia-alcohol separation device has the above-mentioned technical effects, the above-mentioned method for co-producing oxalamide from dimethyl oxalate should also have the same technical effects, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention provides a schematic structural diagram of a specific embodiment of the ammonia-alcohol separation device. DETAILED DESCRIPTION

[0027] The core of the present invention is to provide an ammonia-alcohol separation device, which uses a chemical method to achieve the complete conversion of ammonia and the recycling of methanol between a dimethyl oxalate synthesis device and an oxalamide synthesis device. Another core of the present invention is to provide a method for co-producing oxalamide from dimethyl oxalate using the above-mentioned ammonia-alcohol separation device.

[0028] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0029] Please refer to Figure 1 , Figure 1 The present invention provides a schematic structural diagram of a specific embodiment of the ammonia-alcohol separation device.

[0030] The specific embodiment of the present invention provides an ammonia-alcohol separation device, comprising a methanol absorption section, a methanol condensation and extraction section, an ammonia absorption section and an ammonia absorption raw material preparation section arranged in sequence from top to bottom, wherein the methanol absorption section absorbs methanol in the gas through desalted water, and the ammonia absorption section absorbs ammonia in the gas through a methanol solution of dimethyl oxalate. It also comprises a dimethyl oxalate distillation device and an oxalamide synthesis device, wherein the dimethyl oxalate distillation device is used to output dimethyl oxalate at a preset temperature, and the oxalamide synthesis device is used to produce oxalamide, and the methanol, ammonia, etc. generated in the production process are sent to the ammonia-alcohol separation device.

[0031] The dimethyl oxalate introduced from the dimethyl oxalate production device is used as a raw material to produce oxamide, and all tail gas generated in the oxamide synthesis device is collected and transported to the ammonia-alcohol separation device. In the ammonia-alcohol separation device, dimethyl oxalate reacts with ammonia in the tail gas to generate oxamide and is pumped into the oxamide synthesis reactor to achieve complete conversion of ammonia; the methanol tail gas that does not contain ammonia is condensed in the ammonia-alcohol separation device provided by the present invention and pumped to the dimethyl oxalate synthesis device as a raw material for dimethyl oxalate synthesis, thereby achieving internal circulation of methanol in the dimethyl oxalate synthesis and oxamide production device; finally, the tail gas containing a small amount of methanol is washed with a circulating aqueous solution and desalted water, and the washed water is sent to the sewage treatment device to supplement the carbon source. The chemical reaction in the oxamide production process replaces the distillation and washing steps in the prior art solution, thereby achieving complete conversion of ammonia, internal circulation of methanol in the dimethyl oxalate synthesis and oxamide production device, and effective utilization of the low-level thermal energy of dimethyl oxalate. It has significant advantages such as high equipment integration, small investment, low energy consumption, and no waste liquid and waste solid generation.

[0032] In the ammonia-alcohol separation device provided in the specific embodiment of the present invention, the methanol absorption section adopts a double-layer packed tower structure, the upper absorption liquid adopts desalted water, and the lower layer adopts a circulating water solution, which can save the amount of desalted water while ensuring the absorption effect. It includes a first cylinder 12, an upper head 11 is arranged at the upper end of the first cylinder 12, a first isolation tower plate 18 is arranged at the lower end of the first cylinder 12, and a desalted water nozzle 13, a first methanol absorption filler 14, a circulating water solution nozzle 15, a second methanol absorption filler 16 and a first riser 17 are arranged in sequence from top to bottom in the first cylinder 12.

[0033] A pipe cap is installed above the first riser pipe 17 to prevent the liquid above from flowing downward from the first riser pipe 17 to below the first isolation tower plate 18 .

[0034] Specifically, the upper head 11 is provided with a gas exhaust port N11, a nitrogen inlet N12 and a pressure gauge port P11, and the side wall of the first cylinder 12 is provided with a desalted water inlet N13, a circulating water solution inlet N14, a first overflow port N15 and a circulating water solution outlet N16 from top to bottom, and the side wall of the first cylinder 12 is also provided with a first liquid level gauge upper interface L11, a first liquid level gauge lower interface L12 and a first thermometer interface T11.

[0035] In the ammonia-alcohol separation device provided in a specific embodiment of the present invention, the methanol condensation and production section includes a second cylinder 23 and a heat exchange tube bundle 21, a baffle 22 and a second riser 24 installed inside the second cylinder 23. A second isolation tower plate 25 is arranged below the second cylinder 23. The heat exchange tube bundle 21 is arranged vertically, and a plurality of baffles 22 are arranged alternately horizontally.

[0036] Specifically, the side wall of the second cylinder 23 is provided with a coolant inlet N21 and a coolant outlet N22, a second overflow port N23 and a methanol production port N24 in sequence from top to bottom, and the side wall of the second cylinder 23 is also provided with a second liquid level gauge upper interface L21, a second thermometer interface T21 and a second liquid level gauge lower interface L22 in sequence from top to bottom.

[0037] In the ammonia-alcohol separation device provided in the specific embodiment of the present invention, the ammonia absorption section adopts a multi-layer plate tower, which can effectively prevent blockage. The upper absorption liquid of the ammonia absorption section adopts a relatively pure dimethyl oxalate methanol solution, and the lower layer adopts a circulating absorption liquid, which can improve the absorption effect of ammonia. The ammonia absorption section includes a third cylinder 32, and the third cylinder 32 is provided with a first anti-collision baffle 31, a sieve plate tray 33 and a second anti-collision baffle 34. The first anti-collision baffle 31 is arranged at the upper end of the third cylinder 32, and the second anti-collision baffle 34 is arranged at the middle end of the third cylinder 32. Multiple sieve plate trays 33 are arranged alternately horizontally.

[0038] Specifically, the side wall of the third cylinder 32 is provided with a dimethyl oxalate methanol liquid inlet N31, a circulating absorption liquid inlet N32 and an exhaust gas inlet N33 in sequence from top to bottom.

[0039] On the basis of the ammonia-alcohol separation device provided in the above-mentioned specific embodiments, the ammonia absorption raw material preparation section includes a fourth cylinder 42, and a liquid guide plate 41 and a partition 43 are arranged in the fourth cylinder 42. The liquid guide plate 41 is obliquely arranged at the upper end of the fourth cylinder 42, and the partition 43 is vertically arranged at the lower end of the fourth cylinder 42.

[0040] Specifically, the side wall of the fourth cylinder 42 located on the left side of the partition 43 is provided with a dimethyl oxalate inlet N41 and a methanol inlet N42 from top to bottom, the fourth cylinder 42 located on the left side of the partition 43 is provided with a dimethyl oxalate methanol solution outlet N43, the fourth cylinder 42 located on the right side of the partition 43 is provided with a circulating absorption liquid outlet N44, the side wall of the fourth cylinder 42 located on the left side of the partition 43 is provided with a third liquid level gauge upper interface L41, a third thermometer interface T41 and a third liquid level gauge lower interface L42 from top to bottom, and the side wall of the fourth cylinder 42 located on the right side of the partition 43 is provided with a fourth liquid level gauge upper interface L43, a fourth thermometer interface T42 and a fourth liquid level gauge lower interface L44 from top to bottom.

[0041] The above interfaces connect corresponding components to achieve smooth flow of fluid and detection of the operating status of the equipment, and the position and layout of each interface can be adjusted according to the situation. Furthermore, the above sections and components to be connected are connected by flanges, and of course, threaded connections or welding can also be used, all of which are within the protection scope of the present invention.

[0042] All tail gas containing nitrogen, methanol and ammonia collected from the oxalamide synthesis unit enters the lower part of the ammonia absorption section from the N33 port and moves from bottom to top under the action of pressure, successively contacting the circulating absorption liquid sprayed from the ammonia absorption section and the methanol solution of dimethyl oxalate on the sieve plate, ammonia reacts with dimethyl oxalate to form oxalamide, and the methanol and nitrogen gases without ammonia continue to rise and are discharged from the second riser pipe into the methanol condensation and production section, and the tail gas exchanges heat with the cooling water from the shell side of the methanol condensation and production section, and most of the methanol is condensed and a part of it is produced and sent to the dimethyl oxalate synthesis unit to participate in the synthesis of dimethyl oxalate, and the other part is used as a solvent to remove ammonia and absorb the left area of ​​the raw material preparation section partition and mix with dimethyl oxalate.

[0043] The tail gas from the methanol condensation and production section enters the methanol absorption section through the first riser pipe. The methanol absorption section is a two-stage packed tower. The lower section uses a circulating aqueous solution containing methanol to wash and absorb the methanol tail gas, and the upper section uses desalted water to further remove the methanol in the tail gas until it meets the emission standards.

[0044] The 135°C dimethyl oxalate from the dimethyl oxalate heat exchanger of the dimethyl oxalate synthesis unit enters the left area of ​​the ammonia absorption raw material preparation section partition, is mixed with part of the methanol produced from the methanol condensation production section, and is pumped to the inlet of the dimethyl oxalate methanol solution. Due to the excess of dimethyl oxalate, the dimethyl oxalate methanol solution after absorbing ammonia still contains a large amount of dimethyl oxalate and methanol, which moves downward under the action of gravity and mixes with the circulating absorption liquid and then enters the right area of ​​the ammonia absorption raw material preparation section partition.

[0045] The main components of the right area of ​​the ammonia absorption raw material preparation section partition are dimethyl oxalate, methanol, and oxalamide. A part of them is used as a circulating absorption liquid to wash the tail gas in the middle of the ammonia absorption section, and the other part is pumped into the oxalamide reactor of the oxalamide synthesis unit for the preparation of oxalamide.

[0046] Part of the circulating water absorption liquid at the bottom of the methanol absorption section is used for washing and absorption of methanol, and part of it is sent to the sewage treatment device as a carbon source supplement for sewage treatment.

[0047] By adjusting the packing height of the methanol absorption tower and the amount of desalted water sprayed, the methanol content in the tail gas can be controlled to meet the prescribed emission standards.

[0048] The specific embodiment of the present invention provides a method for co-producing oxalamide with dimethyl oxalate, using any one of the above-mentioned ammonia alcohol separation devices, comprising the steps of:

[0049] S1: Directly introduce dimethyl oxalate at 135°C from the dimethyl oxalate heat exchanger of the dimethyl oxalate distillation unit to the dimethyl oxalate inlet N41 in the ammonia absorption raw material preparation section, and mix it with the methanol produced from the methanol production outlet N24;

[0050] S2: The methanol solution of dimethyl oxalate is pumped out from the dimethyl oxalate methanol solution outlet N43 to the dimethyl oxalate methanol liquid inlet N31 and flows downward, reacts with ammonia in the tail gas generated by the oxalamide synthesis unit to produce oxalamide, and flows into the right area of ​​the partition 43 of the ammonia absorption raw material preparation section, and then is pumped out from the circulating absorption liquid outlet N44, a part of which goes to the oxalamide synthesis reactor of the oxalamide synthesis unit, and a part of which goes to the circulating absorption liquid inlet N32 to absorb ammonia in the tail gas of the oxalamide synthesis unit;

[0051] S3: Ammonia-free methanol gas and nitrogen enter the methanol condensation and production section from the second riser 24. Most of the methanol is condensed in the methanol condensation and production section and collected above the second isolation plate 25. A portion of the methanol is pumped from the methanol production port N24 to the methanol inlet N42 of the ammonia absorption raw material preparation section to mix with dimethyl oxalate; the other portion is pumped to the dimethyl oxalate synthesis section to produce crude dimethyl oxalate. The crude dimethyl oxalate is refined in the dimethyl oxalate distillation unit and then sent to the oxalamide synthesis unit and the ammonia-alcohol separation unit, thereby realizing the circulation of methanol among the ammonia-alcohol separation unit, the dimethyl oxalate unit and the oxalamide synthesis unit;

[0052] S4: Pumping out the circulating absorption liquid of the oxalamide synthesis reactor of the oxalamide synthesis unit to react with excess ammonia to generate oxalamide, and the material discharged from the oxalamide synthesis reactor contains oxalamide, methanol and ammonia;

[0053] S5: The material discharged from the oxalamide synthesis reactor of the oxalamide synthesis unit is flashed, filtered and dried to obtain oxalamide powder. The gases containing methanol, ammonia and nitrogen produced in the process are all sent to the ammonia-alcohol separation unit, so that ammonia is completely converted into oxalamide products between the ammonia-alcohol separation unit and the oxalamide synthesis unit. The liquid containing methanol and ammonia produced by the oxalamide synthesis unit can be heated to a certain temperature and then enter the lower part of the ammonia absorption section of the ammonia-alcohol separation unit, so as to realize ammonia-alcohol separation in the ammonia-alcohol separation unit.

[0054] The above is a detailed introduction to the ammonia alcohol separation device provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention, and the description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An ammonia alcohol separation device, characterized in that: The method comprises a methanol absorption section, a methanol condensation and production section, an ammonia absorption section and an ammonia absorption raw material preparation section which are arranged in sequence from top to bottom. The methanol absorption section absorbs methanol in the gas by means of desalted water. The methanol produced by the methanol condensation and production section is sent to a dimethyl oxalate synthesis unit. The ammonia absorption section absorbs ammonia in the gas by means of a methanol solution of dimethyl oxalate. The method further comprises a dimethyl oxalate distillation unit and an oxalamide synthesis unit. The dimethyl oxalate distillation unit is used for outputting dimethyl oxalate at a preset temperature. The oxalamide synthesis unit is used for producing oxalamide, and the methanol and ammonia produced in the production process are sent to corresponding positions.

2. The ammonia-alcohol separation device according to claim 1, characterized in that: The methanol absorption section comprises a first cylinder (12), an upper end of the first cylinder (12) is provided with an upper head (11), a lower end of the first cylinder (12) is provided with a first isolation tower plate (18), and the first cylinder (12) is provided with a desalted water nozzle (13), a first methanol absorption filler (14), a circulating water solution nozzle (15), a second methanol absorption filler (16) and a first riser pipe (17) arranged in sequence from top to bottom.

3. The ammonia-alcohol separation device according to claim 2, characterized in that: The upper end cap (11) is provided with a gas exhaust port (N11), a nitrogen inlet (N12) and a pressure gauge port (P11); the side wall of the first cylinder (12) is provided with a desalted water inlet (N13), a circulating water solution inlet (N14), a first overflow port (N15) and a circulating water solution outlet (N16) in order from top to bottom; the side wall of the first cylinder (12) is also provided with a first liquid level gauge upper interface (L11), a first liquid level gauge lower interface (L12) and a first thermometer interface (T11).

4. The ammonia-alcohol separation device according to claim 1, characterized in that: The methanol condensation and extraction section comprises a second cylinder (23) and a heat exchange tube bundle (21), a baffle (22) and a second riser (24) installed inside the second cylinder (23); a second isolation tower plate (25) is arranged below the second cylinder (23); the heat exchange tube bundle (21) is arranged vertically, and a plurality of baffles (22) are arranged alternately horizontally.

5. The ammonia-alcohol separation device according to claim 4, characterized in that: The side wall of the second cylinder (23) is provided with a coolant inlet (N21), a coolant outlet (N22), a second overflow port (N23) and a methanol extraction port (N24) in sequence from top to bottom. The side wall of the second cylinder (23) is also provided with a second liquid level gauge upper interface (L21), a second thermometer interface (T21) and a second liquid level gauge lower interface (L22) in sequence from top to bottom.

6. The ammonia-alcohol separation device according to claim 1, characterized in that: The ammonia absorption section comprises a third cylinder (32), wherein a first impact baffle (31), a sieve plate tray (33) and a second impact baffle (34) are arranged in the third cylinder (32), wherein the first impact baffle (31) is arranged at the upper end of the third cylinder (32), and the second impact baffle (34) is arranged at the middle end of the third cylinder (32), and a plurality of sieve plate trays (33) are arranged alternately horizontally.

7. The ammonia-alcohol separation device according to claim 6, characterized in that: The side wall of the third cylinder (32) is provided with a dimethyl oxalate methanol liquid inlet (N31), a circulating absorption liquid inlet (N32) and an exhaust gas inlet (N33) in sequence from top to bottom.

8. The ammonia-alcohol separation device according to any one of claims 1 to 7, characterized in that: The ammonia absorption raw material preparation section comprises a fourth cylinder (42), wherein a liquid guide plate (41) and a partition plate (43) are arranged inside the fourth cylinder (42), wherein the liquid guide plate (41) is arranged obliquely at the upper end of the interior of the fourth cylinder (42), and the partition plate (43) is arranged vertically at the lower end of the interior of the fourth cylinder (42).

9. The ammonia-alcohol separation device according to claim 8, characterized in that: The side wall of the fourth cylinder (42) located on the left side of the partition (43) is provided with a dimethyl oxalate inlet (N41) and a methanol inlet (N42) in order from top to bottom; the fourth cylinder (42) located on the left side of the partition (43) is provided with a dimethyl oxalate methanol solution outlet (N43); the fourth cylinder (42) located on the right side of the partition (43) is provided with a circulating absorption liquid outlet (N44); the side wall of the fourth cylinder (42) located on the left side of the partition (43) is provided with a third liquid level gauge upper interface (L41), a third thermometer interface (T41) and a third liquid level gauge lower interface (L42) in order from top to bottom; the side wall of the fourth cylinder (42) located on the right side of the partition (43) is provided with a fourth liquid level gauge upper interface (L43), a fourth thermometer interface (T42) and a fourth liquid level gauge lower interface (L44) in order from top to bottom.

10. A method for co-producing oxalamide from dimethyl oxalate, characterized in that: The ammonia-alcohol separation device according to any one of claims 1 to 9 comprises the following steps: S1: Directly introduce 135°C dimethyl oxalate from the dimethyl oxalate heat exchanger of the dimethyl oxalate distillation unit to the dimethyl oxalate inlet (N41) in the ammonia absorption raw material preparation section, and mix it with the methanol produced from the methanol production outlet (N24); S2: The methanol solution of dimethyl oxalate is pumped out from the dimethyl oxalate methanol solution outlet (N43) to the dimethyl oxalate methanol liquid inlet (N31) and flows downward, reacts with ammonia in the tail gas produced by the oxalamide synthesis unit to produce oxalamide, and flows into the right area of ​​the partition (43) of the ammonia absorption raw material preparation section, and then is pumped out from the circulating absorption liquid outlet (N44), a part of which goes to the oxalamide synthesis reactor of the oxalamide synthesis unit, and a part of which goes to the circulating absorption liquid inlet (N32) to absorb ammonia in the tail gas of the oxalamide synthesis unit; S3: Ammonia-free methanol gas and nitrogen enter the methanol condensation and production section from the second riser (24). Most of the methanol is condensed in the methanol condensation and production section and collected above the second isolation plate (25). Part of the methanol is pumped from the methanol production port (N24) to the methanol inlet (N42) of the ammonia absorption raw material preparation section to mix with dimethyl oxalate; the other part is pumped to the dimethyl oxalate synthesis section to produce crude dimethyl oxalate. The crude dimethyl oxalate is refined in the dimethyl oxalate distillation unit and then sent to the oxalamide synthesis unit and the ammonia alcohol separation unit, thereby realizing the circulation of methanol between the ammonia alcohol separation unit, the dimethyl oxalate unit and the oxalamide synthesis unit; S4: Pumping out the circulating absorption liquid of the oxalamide synthesis reactor of the oxalamide synthesis unit to react with excess ammonia to generate oxalamide, and the material discharged from the oxalamide synthesis reactor contains oxalamide, methanol and ammonia; S5: The material discharged from the oxalamide reactor of the oxalamide synthesis unit is flashed, filtered and dried to obtain oxalamide powder. The gases containing methanol, ammonia and nitrogen generated in the process are all sent to the ammonia-alcohol separation unit, so that ammonia is completely converted into oxalamide products between the ammonia-alcohol separation unit and the oxalamide synthesis unit. The liquid containing methanol and ammonia generated by the oxalamide synthesis unit is heated to a certain temperature and then enters the lower part of the ammonia absorption section of the ammonia-alcohol separation unit to achieve ammonia-alcohol separation.

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