A device and method for producing oxalamide

Abstract

The present invention discloses a device and method for producing oxalamide, and relates to the field of chemical production. The method for producing oxalamide provided by the present invention specifically comprises: mixing a methanol solution of liquid ammonia and a methanol solution of dimethyl oxalate to undergo an ammonolysis reaction, flashing, filtering, and drying the first slurry after the reaction to obtain solid oxalamide, refining the liquid phase obtained by solid-liquid separation of the first slurry to obtain byproduct methanol, and washing and absorbing ammonia in the tail gas with dimethyl oxalate and returning to the reaction system. In the process of oxalamide production, the present invention utilizes dimethyl oxalate to react with ammonia in the mixed gas generated during the reaction, and the obtained product continues to undergo subsequent ammonolysis reaction, thereby improving the utilization rate of the reaction materials; at the same time, a condenser is not used to condense ammonia and methanol before separation of alcohol and ammonia, thereby saving condensation equipment and cooling water, reducing production costs, and facilitating industrial production.

Description

Technical Field

[0001] The invention relates to the field of chemical production, and in particular to a device and method for producing oxamide. Background Art

[0002] Oxamide is a high-quality slow-release fertilizer that can slowly release the nitrogen necessary for plant growth in the soil, ensuring a stable supply of nitrogen during the plant growth period, which is beneficial to increasing crop yields.

[0003] With the development of technology, the preparation method of oxalamide has evolved from the early hydrocyanic acid method and ammonium oxalate thermal decomposition method to the oxalate method. The principle of the oxalate method is to use dimethyl oxalate to react with ammonia to prepare oxalamide, which is currently the most promising production method in industry.

[0004] Dimethyl oxalate has a wide range of sources and can be synthesized through a variety of process routes. Ammonia is a common inorganic chemical raw material, and its production technology and supply system are relatively mature and easy to obtain. At the same time, the reaction conditions for preparing oxalamide by reacting dimethyl oxalate with ammonia are mild, and no extreme reaction conditions are required, which is conducive to reducing energy consumption and equipment investment. The preparation of oxalamide by ammonolysis of dimethyl oxalate has been widely studied. For example, patent applications CN111153823A and CN115715962A disclose methods for preparing oxalamide by ammonolysis of dimethyl oxalate. In the preparation process, a condenser is used to condense the generated gaseous methanol and ammonia before use. Since the boiling point of ammonia is about -33.5°C, it is difficult to completely condense and separate the gaseous methanol and ammonia by physical condensation, and the utilization rate of the reaction raw materials is not high enough. At the same time, the cost of using a condenser to condense the gaseous methanol and ammonia is high, and the economic benefits are poor. Summary of the invention

[0005] In view of this, the present invention provides an apparatus and method for producing oxalamide. The present invention introduces a second reaction device into the apparatus for producing oxalamide, in which a methanol solution of dimethyl oxalate is used to react with ammonia in a mixed gas generated by a reaction system to improve the utilization rate of ammonia; at the same time, the production cost is reduced, which is conducive to industrial production.

[0006] The present invention first provides a device for producing oxalamide, comprising:

[0007] a first mixer for mixing methanol and liquid ammonia;

[0008] a second mixer for mixing methanol and dimethyl oxalate;

[0009] A first reaction device having a material inlet connected to the first mixer material outlet and the second mixer material outlet respectively;

[0010] A gas-liquid separation device whose material inlet is connected to the material outlet of the first reaction device;

[0011] A solid-liquid separation device having a material inlet connected to a liquid phase discharge port of the gas-liquid separation device;

[0012] A drying device whose material inlet is connected to the solid phase discharge port of the solid-liquid separation device;

[0013] A second reaction device having a first material inlet that is respectively connected to the gas phase outlet of the gas-liquid separation device and the gas phase outlet of the drying device, a second material inlet of the second reaction device is connected to the material outlet of the second mixer, and a liquid phase outlet of the second reaction device is connected to the material inlet of the second mixer.

[0014] In some specific implementations, the second reaction device is a washing tower; the first material inlet of the second reaction device is located at the bottom of the tower, and the second material inlet is located at the top of the tower.

[0015] In some specific implementations, the first reaction device includes:

[0016] A reactor whose material inlet is respectively connected to the material outlet of the first mixer and the material outlet of the second mixer; and a purifier whose material inlet is respectively connected to the material outlet of the reactor and the material outlet of the first mixer.

[0017] In some specific implementations, the purifier is a plug flow reactor.

[0018] In some specific implementations, the device for producing oxalamide of the present invention also includes: a liquid phase separation device whose material inlet is connected to the liquid phase discharge port of the solid-liquid separation device; the liquid phase discharge port of the liquid phase separation device is connected to the material inlet of the first mixer; and the gas phase discharge port of the liquid phase separation device is connected to the first material inlet of the second reaction device.

[0019] In some specific implementations, the device for producing oxalamide of the present invention further includes: a gas phase purification device whose material inlet is connected to the gas phase outlet of the second reaction device.

[0020] The present invention also provides a method for producing oxamide, comprising:

[0021] a) mixing dimethyl oxalate, liquid ammonia and methanol to undergo an ammonolysis reaction to obtain a first slurry;

[0022] b) performing gas-liquid separation on the first slurry obtained in step a) to obtain a first alcohol-ammonia gas phase mixture and a second slurry;

[0023] c) separating the second slurry obtained in step b) into solid and liquid to obtain a third slurry; drying the third slurry to obtain a second alcohol-ammonia gas phase mixture and oxalamide solid;

[0024] d) mixing the first alcohol-ammonia gas phase mixture obtained in step b) and the second alcohol-ammonia gas phase mixture obtained in step c) with a methanol solution of dimethyl oxalate to obtain a first liquid phase mixture; and further using the first liquid phase mixture in the aminolysis reaction in step a).

[0025] In some specific implementations, the specific method of mixing the first alcohol-ammonia gas phase mixture and the second alcohol-ammonia gas phase mixture with the methanol solution of dimethyl oxalate in step d) is: the liquid phase is from top to bottom, and the gas phase is from bottom to top, and the two are in countercurrent contact and react.

[0026] In some specific implementations, the second slurry in step c) further includes a second liquid phase mixture after solid-liquid separation; the second liquid phase mixture is refined to obtain methanol, a third liquid phase mixture and a third alcohol-ammonia gas phase mixture; the third liquid phase mixture is further used in the ammonolysis reaction in step a), and the third alcohol-ammonia gas phase mixture is mixed with the first alcohol-ammonia gas phase mixture and the second alcohol-ammonia gas phase mixture and reacted with a methanol solution of dimethyl oxalate.

[0027] In some specific implementations, the first alcohol-ammonia gas phase mixture, the second alcohol-ammonia gas phase mixture, the third alcohol-ammonia gas phase mixture and the methanol solution of dimethyl oxalate are mixed and reacted to produce a first gas phase mixture; the first gas phase mixture is purified and then discharged.

[0028] The present invention provides an apparatus and method for producing oxalamide. In the oxalamide production process, a methanol solution of dimethyl oxalate is used to react with ammonia in a mixed gas generated in a reaction system, and the obtained product is further subjected to a subsequent ammonolysis reaction, thereby improving the utilization rate of the reaction materials, and the utilization rate of ammonia can reach 100%. At the same time, no equipment such as a condenser is used, thereby reducing the production cost and facilitating industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the structure of the device for producing oxamide provided by the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the purifier provided by the present invention.

[0031] The markings in the accompanying drawings are as follows: 1 is the first mixer; 2 is the second mixer; 3 is the reactor, 4 is the purifier; 5 is the gas-liquid separation device; 6 is the solid-liquid separation device; 7 is the drying device; 8 is the liquid phase separation device; 9 is the second reaction device; 10 is the gas phase purification device; 4-1 is the material inlet from the reactor 3 of the purifier 4; 4-2 is the material inlet from the first mixer 1 of the purifier 4; 4-3 is the material outlet of the purifier 4. DETAILED DESCRIPTION

[0032] It should be understood that the expression "one or more of..." includes each of the items recited after the expression individually and in various different combinations of two or more of the recited items, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited items should be understood to have the same meaning, unless otherwise understood from the context.

[0033] The use of the terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, for example not excluding other unrecited elements or steps, unless otherwise specifically stated or otherwise understood from the context.

[0034] It should be understood that the order of steps or the order in which certain actions are performed is not important as long as the present invention remains operable. In addition, two or more steps or actions may be performed simultaneously.

[0035] The use of any and all examples or exemplary language, such as "for example" or "including", herein is intended only to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating that any non-claimed element is essential to the practice of the invention.

[0036] In addition, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, quantities, values ​​and percentages used in this disclosure are modified by "about". Here, "about" generally means that the actual value is within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range.

[0037] The present invention provides a device for producing oxamide, comprising:

[0038] a first mixer for mixing methanol and liquid ammonia;

[0039] a second mixer for mixing methanol and dimethyl oxalate;

[0040] A first reaction device having a material inlet connected to the first mixer material outlet and the second mixer material outlet respectively;

[0041] A gas-liquid separation device whose material inlet is connected to the material outlet of the first reaction device;

[0042] A solid-liquid separation device having a material inlet connected to a liquid phase discharge port of the gas-liquid separation device;

[0043] A drying device whose material inlet is connected to the solid phase discharge port of the solid-liquid separation device;

[0044] A second reaction device having a first material inlet that is respectively connected to the gas phase outlet of the gas-liquid separation device and the gas phase outlet of the drying device, a second material inlet of the second reaction device is connected to the material outlet of the second mixer, and a liquid phase outlet of the second reaction device is connected to the material inlet of the second mixer.

[0045] The present invention aims at the problem of insufficient utilization of ammonia in the prior art, introduces a second reaction device into the oxalamide production device, and uses a methanol solution of dimethyl oxalate to absorb ammonia discharged from the reaction system. The oxalamide product obtained by the present invention has high purity, can avoid the phenomenon of seedling burning, and does not produce waste liquid and waste residue, which is an environmentally friendly process for the production of oxalamide.

[0046] See also Figure 1 , Figure 1 The schematic diagram of the device structure for producing oxalamide of the present invention, wherein 1 is a first mixer; 2 is a second mixer; 3 is a reactor in the first reaction device; 4 is a purifier in the first reaction device; 5 is a gas-liquid separation device; 6 is a solid-liquid separation device; 7 is a drying device; 8 is a liquid phase separation device; 9 is a second reaction device; and 10 is a gas phase purification device.

[0047] The device for producing oxalamide provided by the present invention comprises a first mixer 1, which is used to mix methanol and liquid ammonia, and comprises a first material inlet for conveying methanol and a second material inlet for conveying liquid ammonia. After being mixed in the first mixer 1, methanol and liquid ammonia enter the reactor 3 through the first material outlet and enter the purifier 4 through the second material outlet.

[0048] The second mixer 2 is used to mix methanol and dimethyl oxalate, and includes a first material inlet for conveying methanol and a second material inlet for conveying dimethyl oxalate. Methanol and dimethyl oxalate are uniformly mixed in the second mixer 2 and then enter the reactor 3 through the material outlet.

[0049] The preparation of oxalamide by the aminolysis of dimethyl oxalate is a step-by-step reaction. To improve the reaction efficiency and product purity, the present invention preferably uses a two-stage reactor for the aminolysis reaction. Figure 1As shown, the first reaction device of the present invention comprises a reactor 3 and a purifier 4. Dimethyl oxalate and liquid ammonia undergo an ammonolysis reaction in the reactor 3, and the resulting product enters the purifier 4 through the material outlet for further reaction.

[0050] In order to improve the reaction efficiency, the purifier 4 of the present invention is preferably a plug flow reactor. Figure 2 The purifier structure provided by the present invention is shown, including: a shell, staggered partitions, a material inlet 4-1 from the reactor 3, a material inlet 4-2 from the first mixer 1 and a material outlet 4-3. This structure can make the residence time of the reactants in the purifier 4 basically consistent, thereby improving the high purity and uniformity of the reaction products.

[0051] The reaction product out of the purifier 4 enters the gas-liquid separation device 5 through the material outlet 4-3 for gas-liquid separation. The gas phase product after gas-liquid separation enters the second reaction device through the gas phase outlet, and the liquid phase product enters the solid-liquid separation device 6 through the liquid phase outlet.

[0052] The solid-liquid separation device 6 performs solid-liquid separation on the liquid product obtained by the gas-liquid separation device 5. The obtained solid product enters the drying device 7 through the solid phase discharge port for drying to obtain the product oxamide. The product oxamide enters the subsequent packaging process and then is sold. The gas phase product obtained by drying enters the second reaction device 9 through the gas phase discharge port.

[0053] In order to improve the utilization rate of the reaction materials and enhance the quality of the byproduct methanol, the present invention preferably separates the liquid phase mixture produced by the solid-liquid separation device 6. Figure 1 As shown, the device for producing oxalamide of the present invention preferably includes a liquid phase separation device 8. The main components of the liquid phase mixture are methanol and liquid ammonia, which enter the liquid phase separation device 8 through the liquid phase outlet of the solid-liquid separation device 6. The byproduct methanol separated by the liquid phase separation device 8 is output through the liquid phase material outlet, and the mixed solution enters the first mixer 1 through the liquid phase material outlet to continue the subsequent reaction, and the gas phase product enters the second reaction device 9 through the gas phase material outlet.

[0054] In the present invention, the second reaction device 9 mainly collects the gas phase mixture produced by the gas-liquid separation device 5, the drying device 7 and the liquid phase separation device 8 for reaction, and the gas phase mixture is input through the first material inlet. The methanol solution of dimethyl oxalate is introduced from the material outlet of the second mixer 2 and input into the second reaction device 9 through the second material inlet. In the present invention, a gas-liquid reaction occurs in the second reaction device 9, and the tower equipment has the advantages of high mass transfer efficiency, a wide range of applications, energy saving and environmental protection, simple operation and convenient maintenance, and strong adaptability. Therefore, in some specific implementations, the second reaction device 9 of the present invention is preferably a tower equipment, more preferably a washing tower. According to the characteristics of the gas-liquid reaction, in some specific implementations of the present invention, the first material inlet of the second reaction device 9 is located at the bottom of the tower, and the second material inlet is located at the top of the tower.

[0055] The present invention preferably purifies the gas generated during the production process to reduce the impact of chemical production on the environment. Figure 1 As shown, the device described in the present invention preferably includes a gas phase purification device 10 , and the material inlet of the gas phase purification device 10 is connected to the gas phase discharge port of the second reaction device 9 .

[0056] According to the above technical scheme, the device for producing oxalamide described in the present invention includes: a first mixer 1, a second mixer 2, a reactor 3, a purifier 4, a gas-liquid separation device 5, a solid-liquid separation device 6, a drying device 7, a liquid phase separation device 8, a second reaction device 9, a gas phase purification device 10 and necessary components such as pipelines, valves, pumps, etc. commonly used in chemical production processes.

[0057] The present invention also provides a method for producing oxalamide corresponding to the above-mentioned production device, which specifically comprises:

[0058] a) mixing dimethyl oxalate, liquid ammonia and methanol to undergo an ammonolysis reaction to obtain a first slurry;

[0059] b) performing gas-liquid separation on the first slurry obtained in step a) to obtain a first alcohol-ammonia gas phase mixture and a second slurry;

[0060] c) separating the second slurry obtained in step b) into solid and liquid to obtain a third slurry; drying the third slurry to obtain a second alcohol-ammonia gas phase mixture and oxalamide solid;

[0061] d) mixing the first alcohol-ammonia gas phase mixture obtained in step b) and the second alcohol-ammonia gas phase mixture obtained in step c) with a methanol solution of dimethyl oxalate to obtain a first liquid phase mixture; and further using the first liquid phase mixture in the aminolysis reaction in step a).

[0062] The present invention first mixes methanol and liquid ammonia in a first mixer, wherein the mass fraction of liquid ammonia is 1% to 50%, preferably 5% to 50%, and more preferably 10% to 50%. Methanol and dimethyl oxalate are mixed in a second mixer, wherein the mass fraction of dimethyl oxalate is 1% to 60%, preferably 5% to 60%, and more preferably 10% to 60%. In some specific implementations, the conditions for transporting methanol from the methanol raw material tank area to the first mixer are a flow rate of 0.3 to 1.0 t / h, a temperature of 20 to 30°C, and a pressure of 1.5 to 2.5 MPaG; the conditions for transporting methanol from the methanol raw material tank area to the second mixer are a flow rate of 1.5 to 2.5 t / h, a temperature of 20 to 30°C, and a pressure of 1.5 to 2.5 MPaG. In some specific implementations, the conditions for transporting liquid ammonia from the liquid ammonia raw material tank area to the first mixer are a flow rate of 0.3 to 0.6 t / h, a temperature of 20 to 30°C, and a pressure of 2 to 3 MPaG. In some specific implementations, the conditions for dimethyl oxalate in the dimethyl oxalate raw material tank area to be transported to the second mixer are flow rate 1.2~1.6t / h, temperature 100~110°C, and pressure 1.5~2.5MPaG. In order to improve the reaction efficiency, in some specific implementations of the present invention, the operating temperature of the first mixer is 20~40°C, preferably 25~30°C. In some specific implementations, the operating temperature of the second mixer is 40~60°C, preferably 45~60°C, and more preferably 45~55°C. In some specific implementations, the insulation device of the second mixer is a constant temperature water jacket.

[0063] The mixed methanol solution of liquid ammonia and the methanol solution of dimethyl oxalate are introduced into a reactor, reacted at a pressure of 0.05-2.0 MPaG and a temperature of 40-130°C for 0.2-1h, and then introduced into a purifier to continue reacting for 0.2-0.5h to obtain a first slurry, the main component of which is a mixed solution of oxalamide, liquid ammonia and methanol.

[0064] In some specific implementations, the reactor is in a mechanical stirring form. In some specific implementations, the reactor is a heat exchange reactor or an adiabatic reactor. In some specific implementations, the molar ratio of liquid ammonia to dimethyl oxalate in the reactor is 2 to 3:1, preferably 2.05 to 2.5:1, and more preferably 2.05 to 2.2:1.

[0065] In some specific implementations, liquid ammonia, methanol or a methanol solution of liquid ammonia may be added to the purifier to increase the reaction medium and stir the reaction medium. Preferably, the methanol solution of liquid ammonia is used, and more preferably, the methanol solution of liquid ammonia in the first mixer is used. In some specific implementations, the flow rate of the methanol solution of liquid ammonia in the first mixer into the purifier is 0.1-0.3 t / h, preferably 0.1-0.2 t / h, and more preferably 0.1-0.15 t / h.

[0066] After the first slurry is obtained, it is sent to a gas-liquid separation device to obtain a first alcohol-ammonia gas phase mixture whose main components are methanol and ammonia, and a second slurry whose main components are oxalamide, methanol and liquid ammonia. In some specific implementations, the operating temperature of the gas-liquid separation is 60-70°C.

[0067] The obtained second slurry is passed into a solid-liquid separation device for solid-liquid separation to obtain a third slurry and a second liquid phase mixture, wherein the main components of the third slurry are oxalamide, accompanied by a small amount of methanol and liquid ammonia, and the main components of the second liquid phase mixture are methanol and liquid ammonia. In some specific implementations, the solid-liquid separation device is a filter.

[0068] The third slurry is passed into a drying device for drying at a temperature of 60 to 280° C., preferably 100 to 250° C., and a drying time of 0.3 to 4 hours, preferably 0.4 to 2 hours, and more preferably 0.6 to 1 hour. After drying, a solid oxalamide product and a second alcohol-ammonia gas phase mixture whose main components are methanol and ammonia are obtained.

[0069] In some specific implementations, the present invention preferably passes the second liquid phase mixture into a liquid phase separation device for refining to improve the utilization rate of the reaction product. After the second liquid phase mixture is refined, methanol, a third liquid phase mixture and a third alcohol ammonia gas phase mixture are obtained; the third liquid phase mixture is further used for the above-mentioned ammonolysis reaction. In some specific implementations, the refining is preferably performed using a stripping tower. In some specific implementations, the refining parameters are: feed pressure 0.3~0.6MpaG, tower bottom pressure 0.015~0.1MpaG, tower top pressure 0.003~0.006MpaG.

[0070] The present invention passes the first alcohol-ammonia gas phase mixture, the second alcohol-ammonia gas phase mixture, the third alcohol-ammonia gas phase mixture, the sealing gas in the device and the safety valve exhaust gas and other gases produced in the above-mentioned production process into the second reaction device through the first material inlet to wash and collect ammonia in the gas; the methanol solution of dimethyl oxalate in the second mixer is passed into the second reaction device through the second material inlet. In some specific implementations, the specific mode of the reaction of the gas phase and the liquid phase in the second reaction device is: the liquid phase is from top to bottom, the gas phase is from bottom to top, and the two are in countercurrent contact for reaction. In some specific implementations, the operating pressure of the second reaction device is 0.05~0.1 MPaG, and the device temperature is 50~60℃.

[0071] The methanol solution of dimethyl oxalate reacts with the gas generated by the reaction system to obtain a first liquid phase mixture and a first gas phase mixture, wherein the first liquid phase mixture mainly comprises the methanol solution of dimethyl oxalate and a small amount of the reaction product of dimethyl oxalate and ammonia, and returns to the second mixer to continue the subsequent ammonolysis reaction; the first gas phase mixture mainly comprises waste gas and a small amount of methanol, and is discharged after being purified by passing into a gas phase purification device.

[0072] The present invention has no special limitation on the purification method of the first gas phase mixture, and those skilled in the art can select it according to their needs. For example, desalted water can be used to absorb methanol in the first gas phase mixture.

[0073] The present invention provides a device and method for producing oxalamide, which specifically comprises: mixing a methanol solution of liquid ammonia and a methanol solution of dimethyl oxalate to undergo an ammonolysis reaction, flashing, filtering, and drying the first slurry after the reaction to obtain solid oxalamide, refining the liquid phase to obtain byproduct methanol, and returning the ammonia in the tail gas to the reaction system after being absorbed by dimethyl oxalate. In the process of producing oxalamide, the present invention uses a methanol solution of dimethyl oxalate to react ammonia in the mixed gas generated in the reaction system, and the obtained product continues to undergo a subsequent ammonolysis reaction, thereby improving the utilization rate of the reaction materials; at the same time, the process of condensing gaseous methanol and ammonia into liquid is omitted, thereby reducing the production cost and facilitating industrial production.

[0074] The present invention is further described below in conjunction with the following examples. The protection scope of the present invention is not limited by the following examples.

[0075] Example 1

[0076] This embodiment provides a device for producing oxalamide, see Figure 1 The device for producing oxalamide provided in this embodiment specifically includes:

[0077] A first mixer 1 whose material inlet is connected to the material outlet of the methanol raw material tank area and the material outlet of the liquid ammonia raw material tank area respectively;

[0078] A second mixer 2 whose material inlet is respectively connected to the material outlet of the methanol raw material tank area and the material outlet of the dimethyl oxalate raw material tank area;

[0079] A reactor 3 whose material inlet is connected to the material outlet of the first mixer 1 and the material outlet of the second mixer 2 respectively;

[0080] A purifier 4 whose material inlet is connected to the material outlet of the reactor 3 and the material outlet of the first mixer 1 respectively;

[0081] A gas-liquid separation device 5 whose material inlet is connected to the material outlet of the purifier 4, wherein the gas-liquid separation device is a flash evaporator;

[0082] A solid-liquid separation device 6 whose material inlet is connected to the liquid phase discharge port of the gas-liquid separation device 5, wherein the solid-liquid separation device is a filter;

[0083] A drying device 7 connected to the material inlet and the solid phase discharge port of the solid-liquid separation device 6, wherein the drying device is a dryer;

[0084] A liquid phase separation device 8 whose material inlet is connected to the liquid phase discharge port of the solid-liquid separation device 6, wherein the liquid phase separation device is a stripping tower, whose bottom liquid phase discharge port is connected to the methanol raw material tank area, and whose top liquid phase discharge port is connected to the material inlet of the first mixer 1;

[0085] A second reaction device 9 whose first material inlet is respectively connected to the gas phase discharge port of the gas-liquid separation device 5, the gas phase discharge port of the drying device 7 and the gas phase discharge port of the liquid phase separation device 8, wherein the second reaction device is a first washing tower, the second material inlet of the first washing tower is connected to the material outlet of the second mixer 2, and the liquid phase discharge port of the first washing tower is connected to the material inlet of the second mixer 2;

[0086] A gas phase purification device 10 whose material inlet is connected to the gas phase discharge port of the second reaction device 9, wherein the gas phase purification device is a final washing tower.

[0087] Example 2

[0088] 1) Mix liquid ammonia and methanol at a pressure of 1.8 MPaG and a temperature of 28°C to obtain a methanol solution of liquid ammonia, wherein the mass fraction of liquid ammonia is 45%; mix dimethyl oxalate and methanol at a slightly positive pressure and a temperature of 55°C to obtain a methanol solution of dimethyl oxalate, wherein the mass fraction of dimethyl oxalate is 46%;

[0089] 2) subjecting the above-mentioned methanol solution of liquid ammonia and the methanol solution of dimethyl oxalate to an ammonolysis reaction at a pressure of 1.1 MPaG and a temperature of 120° C., wherein the molar ratio of dimethyl oxalate, liquid ammonia and methanol is 1:2.05:5, to obtain a mixed solution of oxalamide, methanol and liquid ammonia;

[0090] 3) flashing the mixed solution obtained in step 2), the obtained gas phase is a mixed gas of ammonia and methanol, and the obtained liquid phase is a mixed slurry containing oxalamide; the mixed slurry containing oxalamide is filtered to obtain a mixed solution of liquid ammonia and methanol and a solid slurry whose main component is oxalamide; the solid slurry is dried at 250° C. for 1 hour to obtain oxalamide solid and generate a mixed gas of ammonia and methanol;

[0091] 4) The mixed solution of liquid ammonia and methanol obtained in step 3) is stripped at 67° C. to obtain liquid methanol, liquid ammonia containing a small amount of methanol, and a mixed gas of a small amount of methanol and ammonia; the liquid methanol is collected, and the liquid ammonia containing a small amount of methanol is re-participated in the ammonolysis reaction in step 2);

[0092] 5) reacting the mixed gas of ammonia and methanol obtained by flash evaporation in step 3), the mixed gas of ammonia and methanol obtained by drying, the mixed gas of ammonia and methanol obtained by stripping in step 4), the sealing gas in the device and the exhaust gas of the safety valve with the methanol solution of dimethyl oxalate in step 1), at a reaction temperature of 55° C. and a pressure of 0.05 MPaG, in a main manner of spraying the methanol solution of dimethyl oxalate from top to bottom, and moving the mixed gas of ammonia and methanol from bottom to top, in countercurrent contact, to obtain a gas containing a small amount of methanol and a reaction mixed solution;

[0093] 6) The gas containing a small amount of methanol obtained in step 5) is discharged into the atmosphere after being adsorbed by desalted water and the obtained reaction mixture is mixed with the methanol solution of dimethyl oxalate in step 1) to continue the aminolysis reaction.

[0094] In this example, the conversion rate of ammonia is 100%, and the yield of oxalamide is 99.9% (based on the amount of ammonia).

[0095] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for producing oxalamide, characterized in that: include: a first mixer for mixing methanol and liquid ammonia; a second mixer for mixing methanol and dimethyl oxalate; A first reaction device having a material inlet connected to the first mixer material outlet and the second mixer material outlet respectively; A gas-liquid separation device whose material inlet is connected to the material outlet of the first reaction device; A solid-liquid separation device having a material inlet connected to a liquid phase discharge port of the gas-liquid separation device; A drying device whose material inlet is connected to the solid phase discharge port of the solid-liquid separation device; A second reaction device having a first material inlet that is respectively connected to the gas phase outlet of the gas-liquid separation device and the gas phase outlet of the drying device, a second material inlet of the second reaction device is connected to the material outlet of the second mixer, and a liquid phase outlet of the second reaction device is connected to the material inlet of the second mixer.

2. The device according to claim 1, characterized in that The second reaction device is a washing tower; The first material inlet of the second reaction device is located at the bottom of the tower, and the second material inlet is located at the top of the tower.

3. The device according to claim 1, characterized in that The first reaction device comprises: A reactor having a material inlet connected to the first mixer material outlet and the second mixer material outlet respectively; A purifier whose material inlet is respectively connected to the material outlet of the reactor and the material outlet of the first mixer.

4. The device according to claim 3, characterized in that The purifier is a plug flow reactor.

5. The device according to claim 1, characterized in that Also includes: A liquid phase separation device having a material inlet connected to a liquid phase discharge port of the solid-liquid separation device; The liquid phase discharge port of the liquid phase separation device is communicated with the material inlet of the first mixer; the gas phase discharge port of the liquid phase separation device is communicated with the first material inlet of the second reaction device.

6. The device according to claim 1, characterized in that Also includes: A gas phase purification device whose material inlet is connected to the gas phase discharge port of the second reaction device.

7. A method for producing oxamide, characterized in that: include: a) mixing dimethyl oxalate, liquid ammonia and methanol to undergo an ammonolysis reaction to obtain a first slurry; b) performing gas-liquid separation on the first slurry obtained in step a) to obtain a first alcohol-ammonia gas phase mixture and a second slurry; c) separating the second slurry obtained in step b) into solid and liquid to obtain a third slurry; drying the third slurry to obtain a second alcohol-ammonia gas phase mixture and oxalamide solid; d) mixing the first alcohol-ammonia gas phase mixture obtained in step b) and the second alcohol-ammonia gas phase mixture obtained in step c) with a methanol solution of dimethyl oxalate to obtain a first liquid phase mixture; and further using the first liquid phase mixture in the aminolysis reaction in step a).

8. The method according to claim 7, characterized in that The specific method of mixing and reacting the first alcohol-ammonia gas phase mixture and the second alcohol-ammonia gas phase mixture with the methanol solution of dimethyl oxalate in step d) is: the liquid phase is from top to bottom, and the gas phase is from bottom to top, and the two are in countercurrent contact to react.

9. The method according to claim 7, characterized in that: The second slurry in step c) further comprises a second liquid phase mixture after solid-liquid separation; The second liquid phase mixture is refined to obtain methanol, a third liquid phase mixture and a third alcohol-ammonia gas phase mixture; the third liquid phase mixture is further used for the aminolysis reaction in step a), and the third alcohol-ammonia gas phase mixture is mixed with the first alcohol-ammonia gas phase mixture and the second alcohol-ammonia gas phase mixture and reacted with a methanol solution of dimethyl oxalate.

10. The method according to claim 9, characterized in that The first alcohol-ammonia gas phase mixture, the second alcohol-ammonia gas phase mixture, the third alcohol-ammonia gas phase mixture and the methanol solution of dimethyl oxalate are mixed and reacted to produce a first gas phase mixture; The first gas phase mixture is purified and then discharged.

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