JPH05163217A - Process and apparatus for producing oxamide - Google Patents

Abstract

PURPOSE:To enable high-efficient continuous production of oxamide by preventing the blockade at the ammonia feeder caused by formation and adhesion of insoluble oxamide to the site to which ammonia is fed and by improving the contact efficiency between ammonia gas and a solution of dialkyl oxalate in an alcohol. CONSTITUTION:In the reactor 30, a rotary drum 31 having a plurality of projecting nozzles 32 in the direction crossing with the rotation axis 31a is rotated around the axis 31a. Thus, as the mixture is stirred, ammonia gas is jetted through the nozzles 32 into the mixture in fine bubbles whereby oxamide is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing oxamide (slow-acting fertilizer), and more specifically, a lower solvent such as methanol, ethanol, butanol or the like in an aliphatic lower alcohol such as dimethyl oxalate, diethyl oxalate, Generation and adhesion of the insoluble crystalline oxamide, which is a product when ammonia gas is brought into contact with a mixed solution in which a dialkyl oxalate ester solution such as dibutyl oxalate is obtained as a product, to an ammonia gas supply section The present invention relates to a method and an apparatus for producing oxamide, which can prevent the blockage of the portion due to the above, and further improve the contact efficiency between the ammonia gas and the mixed liquid to continuously and efficiently produce oxamide.

[0002]

2. Description of the Related Art Oxamide has hitherto been used as a reaction solvent in a reaction vessel such as methanol (CH ₃ OH), ethanol,
Dialkyl oxalate such as dimethyl oxalate, diethyl oxalate, dibutyl oxalate (hereinafter
Ammonia gas (NH ₃ ) is contacted with a solution prepared by dissolving a solution (sometimes referred to as dialkyl oxalate) to generate an alcohol such as methanol and an oxamide through the formation of an alkyl oxamate such as methyl oxamate. And oxamide is recovered as a product. An example of this reaction formula is represented by the following formula.

[0003]

[Formula 1]

The manufacturing method is carried out by the method shown in FIG. 3 or FIG. In the manufacturing apparatus shown in FIG. 3, 1 is a reaction vessel in which methanol (hereinafter, also referred to as MeOH) is stored, 2 is an ammonia gas supply nozzle arranged at the bottom of the vessel 1, and 3 is a tip. A stirrer 5 having a stirring blade 4 is a dimethyl oxalate supply pipe attached to the upper side wall of the container 1, and a plurality (two in this example) of such reaction containers 1 are arranged and provided. .. In such a device, dimethyl oxalate (hereinafter also referred to as DMO) is supplied from a supply pipe 5 while stirring excess methanol in one container 1 with a stirrer 3, and a large number of nozzles 2 are supplied into the liquid. Ammonia gas is bubbled and dispersed and supplied. Then, in the reaction container 1, the reaction as shown in the above reaction formula is performed to generate oxamide (hereinafter sometimes referred to as OX) and methanol. In such a reaction, the ammonia gas is supplied to the liquid which is being stirred, so that the liquid and the ammonia gas are efficiently contacted with each other. The produced oxamide and methanol are taken out from the bottom discharge pipe 6 of the reaction vessel 1 and sent to a drying process not shown, where methanol is separated and oxamide is taken out as a product.

In this manufacturing method, however, insoluble crystals of a product such as oxamide are generated in the holes of the ammonia gas supply nozzle 2 during the dissolution reaction and block the holes. Therefore,
When blockage occurs, the reaction in the container 1 is stopped, and the other container 1 is switched to the same reaction. During this time, the insoluble crystals formed in the nozzle 2 of the closed container 1 spontaneously dissolve in the liquid and the nozzle hole is opened. Then, when the nozzle 2 of the other container 1 that is currently operating is similarly closed, the operation is switched to this one side operation. By alternately performing the switching operation in this way, the oxamide can be continuously produced.

On the other hand, in view of the need for maintenance due to the occurrence of a clogging trouble of the ammonia gas dispersion device of the nozzle 2 in the manufacturing method shown in FIG. 3, a method using a multistage gas-liquid free interface reaction as shown in FIG. 4 is also performed. It is being appreciated. In FIG. 4, a plurality of reaction vessels 10, 11, 12 are connected in multiple stages, and each vessel has a stirrer 1 having a blade 13 at its tip.
4. An ammonia gas supply pipe 15 is provided facing the free interface of the liquid in the container, and a dimethyl oxalate supply pipe 16 is attached to the first-stage container 10. First stage containers 10 and 2
The connecting pipes 17 and 18 are connected to the second-stage container 11 and between the second-stage container 11 and the third-stage container 12, respectively. The oxamide and methanol produced from the lower discharge pipe 19 of the container 12 are taken out, and oxamide is produced through the same steps as the method of FIG. As described above, in the method of FIG. 4, the free interface necessary for the multi-step reaction system is secured to carry out the reaction.

[0007]

By the way, in the method as described above, in the method shown in FIG. 3, although the gas-liquid contact efficiency is good, maintenance is required for the clogging trouble in the dispersion nozzle 2, and Even if the reaction is performed in the other reaction vessel 1 and the crystals formed in the other reaction vessel 1 in the idle state are dissolved, the supply of the ammonia gas becomes unstable without completely separating from the nozzle 2. Become. Further, since a plurality of reaction vessels 1 are required, there is a problem that the entire apparatus becomes large. On the other hand, in the method shown in FIG. 4, it is necessary to connect a large number of reaction vessels to carry out a multi-stage gas-liquid free interface reaction in order to secure a free interface required for the reaction, and therefore, there is a problem that the apparatus also becomes large. is there.

The present invention eliminates the drawbacks of the conventional method and apparatus for producing oxamide, prevents the insoluble crystalline oxamide from clogging at the ammonia gas supply section due to its formation and adhesion, and also prevents the formation of ammonia. The contact efficiency between the gas and the mixed solution is improved, and oxamide is continuously added, and
It is an object of the present invention to provide an oxamide production method and apparatus that can be produced efficiently.

[0009]

In order to achieve the above object, the present invention comprises: (1) ammonia in a mixed solution prepared by dissolving a dialkyl oxalate ester solution in an aliphatic lower alcohol as a reaction solvent in a reaction vessel. In a method for producing oxamide by supplying gas to produce oxamide, a rotary cylinder having a plurality of nozzles provided so as to project in a direction intersecting a rotation axis in a liquid mixture in the reaction vessel is rotated. The oxamide is produced by jetting and supplying the ammonia gas as fine bubbles into the mixed liquid from the nozzle while stirring the mixed liquid by rotating around the axis. Also,

(2) In an apparatus for producing oxamide, ammonia gas is supplied to a mixed solution in which a dialkyl oxalate solution is dissolved in an aliphatic lower alcohol as a reaction solvent in a reaction vessel to produce oxamide. A rotary cylinder having a large number of nozzles for ejecting ammonia gas, which is provided in the reaction vessel so as to project in a direction intersecting the rotation axis, is immersed in the mixed liquid and rotated around the rotation axis. The configuration is provided as possible.

[0011]

With the above-mentioned structure, since the rotary drum having the protruding nozzle is rotated in the alcohol liquid such as methanol, the alcohol liquid is agitated and the alcohol is dialkyl oxalate such as dimethyl oxalate. The liquid is completely dissolved, and the ammonia gas in the mixed liquid is dispersed and supplied as fine bubbles due to the bubbles generated by forced shearing by the action of the projection nozzle, thereby providing a dialkyl oxalate liquid. The gas-liquid contact reaction with ammonia gas is carried out very efficiently and the reaction is carried out very efficiently, and the projection nozzle is always washed with the liquid due to the rotating action of the rotary cylinder in the mixed liquid. Crystals such as oxamide, which is a reaction product, are washed away. Also,
Since the bubbles ejected from the projection nozzle are centrifugally dispersed, the backflow reaction of the reaction product into the bubbles does not occur. Therefore, the reaction product does not adhere or precipitate in the nozzle or in the nozzle hole, and the production of oxamide does not require maintenance such as work of removing the reaction product crystals, and the efficiency is continuously improved. Often done.

Therefore, a protrusion nozzle is provided in a rotary drum rotatably provided in the liquid in a direction perpendicular to the rotation axis of the drum, and the gas is dispersed as fine bubbles in the liquid from the nozzle. Performing oxidation and dedusting by contacting with a liquid is known, for example, in Japanese Patent Publication No. 52-22953 and Japanese Patent Publication No. 60-32797, but as in the present invention, this gas-liquid contact principle is By applying the ammonia gas as a method of supplying the ammonia gas into the mixed liquid of the alcohol as the reaction solvent and the dialkyl oxalate liquid in the oxide manufacturing method and apparatus, as described above, the stirrer 3, 14 can be used as in the prior art. It is possible to effectively carry out the stirring action of the liquid without the need to separately install a stirring device such as etc., and the adhesion and precipitation of crystals such as oxamide, which is a reaction product, occurs. It is excellent effect that it is not being achieved.

[0013]

The present invention will now be described in detail with reference to the embodiments shown in the drawings. FIG. 1 is a schematic cross-sectional view and a flow sheet showing an example of a dissolution reaction type oxamide reactor to which the present invention is applied, FIG. 2 shows an example of a rotary drum of the reactor, and FIG. 2A is a partially enlarged sectional view of the drum, and FIG. 2B is a sectional view taken along the arrow B in FIG. 2A. In FIG. 1, reference numeral 30 is a reaction vessel for carrying out a dissolution reaction, and excess methanol (MeOH) is stored in the reaction vessel at the beginning of the operation. A rotary drum 31 as a rotary cylinder is provided in the liquid of the excess methanol at the bottom of the inside of the reaction container 30, and the rotary drum 31 is rotated around its rotation axis 31a by a motor M at a predetermined rotation speed. To be done.
By using a variable speed motor as the motor M, a desired rotation speed can be applied to the rotary drum 31.
A large number of projecting nozzles 32 are attached to the outer peripheral cylindrical surface of the rotating drum 31 so as to intersect with the rotation axis 31a thereof and orthogonally intersect in this embodiment. The rotary drum 31 and the projection nozzle 32 are internally communicated with each other, and the ammonia gas supplied into the rotary drum 31 is supplied from the projection nozzle 32 into the liquid as bubbles.

A coil 33 for cooling is provided in the liquid above the rotary drum 31. A mist eliminator 34 is provided at the top of the reaction vessel 30, and an exhaust gas outlet 30b is provided at its outlet. Exhaust gas exhaust port 30
A circulating gas pipe 35 having a circulation blower 36 interposed therein is connected to b, and one of them is connected to the inside of the rotary drum 31 so as to communicate therewith. An ammonia gas supply pipe 38 is connected to the circulating gas pipe 35. A slurry withdrawing port 30a is provided at the lowermost portion of the reaction container 30, and the lower container 4 having a small capacity is connected to the slurry withdrawing port 30a.
0 is attached to the reaction container 30. A liquid circulation pipe 42 having a pump 41 interposed is connected between the bottom portion of the reaction container 30 near the side wall and the lower container 40, and the liquid in the reaction container 30 is circulated and supplied from the lower portion of the lower container 40. By forming an ascending liquid flow in the lower container 40, a slurry composed of oxamide and intermediate products methyl oxamate and methanol, which flow down from the reaction container 30 and are taken into the lower container 40, flows into the ascending flow. It is configured to ride up and down and repeat the vertical reciprocating motion between the bottom of the reaction container 30 and the bottom of the lower container 40.

At the bottom of the lower container 40, a throttle valve 44 is installed, and a discharge pipe 43 for taking out the produced slurry of oxamide and methanol is attached. The lower end of the discharge pipe 43 is a tumbling dry granulator. It is connected to 50. The tumbling dry granulator 50 has a plurality of stirring blades 5 which have a center of rotation inside the rotary drum 51 at a position eccentric to the center of rotation of the drum 51 in a sectional view of the drum and rotate in the opposite direction to the drum 51.
3 is attached, and a heating jacket 54 is provided around the drum 51. Steam ST is supplied to the heating jacket 54 to indirectly heat the slurry in the drum 51, while the slurry is granulated and dried by the action of the drum 51 and the stirring blade 53. The tumbling dry granulator 50 is connected with an exhaust pipe 55 for exhaust gas, which is evaporated methanol vapor, and is discharged downstream from the tumbling dry granulator 50 in sequence with the exhaust gas. A collector 56 such as a bag filter for collecting fine oxamide powder and a suction blower 77a are attached. The lower part of the collector 56 and the slurry supply side of the tumbling dry granulator 50 are the collector 56
The oxamide fine powder captured in (1) is connected by a transport pipe 58 for returning to the tumbling drying granulator 50. A discharge pipe 57 is provided on the anti-slurry supply side of the tumbling dry granulator 50 to take out the dry granulated oxamide as a product.

The methanol vapor from which the fine powder of oxamide has been removed by the collector 56 is piped 77 by a suction blower 77a.
Is sent to the methanol recovery / supply unit 70. The methanol recovery / supply unit 70 includes a condenser 71 for cooling and liquefying the methanol vapor sent from the pipe 77, and a pipe for sending a part of the methanol liquefied by the condenser 71 to the methanol recovery unit 80. 72, a pipe 73 for interposing a pump 73 to take out the remaining methanol liquefied in the condenser 71, an adsorption dehydrator 79 branched from this pipe 74, and dimethyl oxalate (DMO) at a downstream point thereof. It is composed of a methanol supply pipe 76 connected to the supply pipe 37 and connected to the reaction container 30 at its end, and a pipe 75 for supplying a part of the methanol liquid to the methanol recovery unit 80. Further, from the discharge side pipe 74 of the pump 73, a pipe line 78 for supplying a seal liquid for liquid leakage sealing to the rotary sliding parts of the pumps 41 and 73, the shaft penetrating part of the rotary drum 31 of the reaction container 30, and the like. , Conduit 4 for supplying clean methanol to the bottom of the lower container 40
5 is provided in a branched manner.

The operation of the oxamide reactor thus constructed will be described. Dimethyl oxalate (temperature of about 60 ° C.) is supplied from the pipe 37 into the methanol supply pipe 76, and the dimethyl oxalate is dissolved in the methanol sent from the methanol recovery / supply unit 70 in the reaction vessel 30. It is supplied, and further, is supplied to the reaction container 30 and is dissolved in excess methanol as a reaction solvent stored therein prior to the start of operation. Then, the ammonia gas becomes fine bubbles from the protrusion nozzle 32 of the rotating drum 31 which is immersed in the excess methanol in the reaction container 30 and is rotating, and is dispersed in the methanol solvent to efficiently perform gas-liquid contact. The liquid is stirred by the rotation of the rotary drum 31 and the dimethyl oxalate is completely dissolved in the excess methanol solvent, so that the dimethyl oxalate reacts efficiently with the ammonia gas.

Here, the projection nozzle 3 provided around the rotary drum 31 so as to project in the direction orthogonal to the rotation axis 31a.
By rotating 2 around the rotation axis 31a,
The principle of generating bubbles by forced shear will be described with reference to FIG. 2B. When the rotating drum 31 is rotated in the liquid, the liquid contacting the cylindrical surface of the rotating drum 31 is almost in contact with the cylindrical surface. Although they rotate at the same peripheral velocity, the velocity rapidly decreases as they move away from the surface of the cylinder. Therefore, at the tip of the projection nozzle 32, which is the gas outlet, there is a large velocity difference ΔV between the opening of the tip and the liquid. Has occurred. As a result, first, the static pressure is reduced in the vicinity of the opening, and when the pressure becomes equal to or lower than the liquid pressure, the gas in the projection nozzle 32 is sucked out and self-injects into the liquid. Then, the gas flowing out from the tip end opening of the projection nozzle 32 is forcibly subjected to the shearing action due to the difference in speed with the liquid and dispersed,
Almost regardless of the size of the opening, uniform fine bubbles are formed. Further, since the direct dispersion action by the forced shearing action is strong even when a large amount of gas exceeding the self-injection ability is forcedly aerated, it is several tens of times larger than the system in which a large number of small holes are simply formed on the cylindrical surface. Has gas dispersion ability.

By the reaction of dimethyl oxalate and ammonia gas, oxamide and methanol are produced through the production of methyl oxamate. In addition, in the present embodiment, the inside of the reaction vessel 30 is pressurized and the pressure is set to about 4 to 5 kg / cm ^2, so that the above-mentioned reaction is performed quickly. The reaction solvent in the reaction container 30 is kept at a predetermined temperature by the coil 33. Ammonia gas is supplied into the rotary drum 31 by supplying a reaction equivalent amount from the supply pipe 38 to the circulating gas pipe 35. Then, in the reaction container 30, gas such as nitrogen gas, carbon dioxide gas, and ammonia gas rises with mist by the suction action of the blower 36 of the circulating gas pipe 35, passes through the mist removing device 34, and the mist is removed. The remaining gas passes through the circulating gas pipe 35 and is supplied with new ammonia gas from the supply pipe 38 as described above, and is returned to the rotary drum 31.

During the production of such oxamide, however, as will be described below, insoluble crystals of oxamide and the like are continuously produced without being generated or attached to the projection nozzle 32 of the rotary drum 31. Gas can be supplied. That is, during operation, as shown in FIG. 2A, the projection nozzle 32 is constantly washed with the liquid in the external liquid by the rotating action of the rotary drum 31, so that crystals of reaction products such as oxamide are generated. Have been washed away,
Further, since the bubbles ejected from the projection nozzle 32 are centrifugally ejected, the backflow reaction of the reaction products into the bubbles does not occur. Therefore, the reaction product does not adhere or deposit inside the protrusion nozzle 32 or in the nozzle hole. As described above, in this example, the production of oxamide can be continuously performed for a long period of time even in a single-stage reactor without maintenance.

Then, the insoluble oxamide and methanol produced in the reaction vessel 30 flow down into the lower vessel 40 through the lower opening 30a. At this time, since the liquid is circulated from the bottom of the reaction container 30 to the bottom of the lower container 40 by the pump 41 and is circulated in the lower container 40, the liquid is flowed upward from the bottom of the container, so that the oxamide crystal grains Among them, those having a large particle size remain at that position, and those having a small particle size (for example, a particle size of less than 0.1 mm) are put on the ascending flow and returned to the upper reaction vessel 30, and then descended. To do. As such rising and falling are repeated, crystal formation in methanol is promoted and gradually grows as crystal grains having a large grain size (for example, grain size 0.1 mm).

In this case, clean methanol is supplied from the pipe 45 to the lowest part of the lower container 40, and the reaction container 30
Impurities such as unreacted products are washed with this clean methanol from the slurry consisting of oxamide crystal grains flowing down from and the methanol. Thus, in the lower container 40, a slurry containing oxamide and methanol in a ratio of, for example, 1: 2 is obtained. That is, in the lower container 40, the oxamide is slurried to a predetermined concentration. As described above, in this embodiment, the slurry of insoluble oxamide and methanol produced in the reaction container 30 is taken out from the bottom of the reaction container 30 to the lower container 40 at the lower portion, and the reaction container 30 is also removed.
The liquid inside is extracted from the container and is supplied to the bottom of the lower container 40 to circulate the liquid between the reaction container 30 and the lower container 40, thereby adjusting and increasing the concentration of oxamide in the slurry. be able to. Then, this slurry flows into the slurry discharge pipe 43 from the bottom of the lower container 40 and is taken out at a desired flow rate by the throttle valve 44,
It is sent to the tumbling drying granulator 50 which is the next drying / granulating step.

The slurry of oxamide crystal grains charged into the tumbling dry granulator 50 is indirectly heated by the steam ST supplied into the jacket 54 around the rotary drum 51,
It is dried by the action of the rotary drum 51 and the stirring blades 53 to vaporize the methanol, and at the same time, is tumbled and granulated to adjust the particle size of the particles and then taken out from the discharge pipe 57 as a product. Evaporated methanol vapor from the tumbling dry granulator 50 is taken out from the exhaust gas discharge pipe 55 by the suction blower 77a, and fine oxamide powder entrained in it is captured by the collector 56 and rolled from the pipe 58. Dry granulator 50
It is returned to and used again for granulation. If the particle size of oxamide is too small, it will be blown away by the wind during fertilization.
It is necessary to keep the desired size.

The methanol vapor from which the oxamide fine particles have been removed by the collector 56 is sent from the pipe 77 to the methanol recovery / supply unit 70, is introduced into the condenser 71 thereof, and is liquefied as clean methanol. The methanol is sent to the methanol recovery unit 80 to be recovered, the other is sent to the pipe 74 by the pump 73, and a part thereof is recovered through the pipe 75 to the methanol recovery unit 80, and the rest is supplied to the pipe 76.

The methanol supplied to the pipe 76 is supplied to the adsorption dehydrator 79 to remove the water content thereof and discharged, and thereafter, the dimethyl oxalate supplied from the pipe 37 is supplied and the dimethyl oxalate is converted to methanol. Is dissolved. As a result, dimethyl oxalate is supplied into the reaction vessel 30 from the pipe 76 in a state of being dissolved in methanol, and the dissolution reaction is efficiently performed as described above. As described above, in the present embodiment, the methanol is discarded by condensing a part of the methanol vapor vaporized in the tumbling dry granulator 50 and reusing it as the raw material dimethyl oxalate dissolving methanol. It can be reused effectively without being used, and the manufacturing cost can be reduced.

After leaving the pump 73, part of the clean methanol is sent from the pipe 45 to the bottom of the lower container 40 to remove impurities such as unreacted intermediate products in the slurry, that is, the slurry. Used for cleaning etc. Further, a part of the methanol is supplied from the pipe 78 to the rotary sliding parts of the pumps 41 and 73, the shaft penetrating part of the rotary drum 31 of the reaction container 30 and the like as a sealing liquid for sealing liquid leakage. In the above examples, the case where the aliphatic lower alcohol was methanol as the reaction solvent was shown, but the alcohol may be ethanol, butanol, isopropanol, or the like. And, although the case where the oxalic acid dialkyl ester solution is a dimethyl oxalate solution is shown, it may be diethyl oxalate, dibutyl oxalate or the like.

[0027]

As is apparent from the above description, according to the present invention, a dialkyl oxalate such as dimethyl oxalate as a raw material is completely dissolved in an alcohol solvent such as methanol to prepare ammonia in the mixture. Since the gas can be dispersed and supplied in the form of fine bubbles, the gas-liquid contact can be carried out efficiently and the reaction can be carried out efficiently, and at the same time, the ammonia gas supply part can be blocked by the growth and adhesion of insoluble oxamide crystal grains. It can be effectively prevented. Therefore, it is not necessary to install a large number of reaction vessels such as multiple reaction vessels or multiple reaction vessels, and the production apparatus can be downsized, and the production apparatus can be continuously operated to continuously and efficiently produce oxamide. You can

The slurry of the insoluble oxamide and the alcohol such as methanol produced in the reaction vessel as described above is taken out from the bottom of the reaction vessel to another vessel below, and the liquid inside is taken out from the reaction vessel. If the liquid is circulated between the reaction container and the lower container by supplying it to the bottom of the lower container, the concentration of oxamide in the slurry can be adjusted and increased to efficiently produce the oxamide. it can.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view and a flow sheet showing an embodiment of a dissolution reaction type oxamide reactor of the present invention.

FIG. 2 (a) is a partially enlarged sectional view showing an embodiment of a rotary drum of a dissolution reaction type oxamide reactor of the present invention,
(B) is a sectional view taken along the arrow B of (a).

FIG. 3 is a diagram showing a conventional method for producing oxamide.

FIG. 4 is a diagram showing another conventional method for producing oxamide.

[Explanation of symbols]

 30 Reaction Container 31 Rotating Drum 32 Protrusion Nozzle 40 Lower Container 41 Circulation Pump 42 Circulation Pipe 50 Rolling Dry Granulator 70 Methanol Recovery / Supply Section

Claims (2)

[Claims] 1. A method for producing an oxamide, wherein ammonia gas is supplied to a mixed solution prepared by dissolving a dialkyl oxalate ester solution in an aliphatic lower alcohol as a reaction solvent in a reaction vessel to produce an oxamide. In the mixed liquid in the reaction vessel, a rotary cylinder having a large number of nozzles provided so as to project in a direction intersecting with the rotation axis is rotated around the rotation axis to agitate the mixed solution while the ammonia gas is discharged from the nozzles. The method for producing oxamide is characterized in that oxamide is produced by jetting and supplying the mixture as fine bubbles into the mixed solution. 2. An oxamide production apparatus in which ammonia gas is supplied to a mixed solution prepared by dissolving an oxalic acid dialkyl ester solution in an aliphatic lower alcohol as a reaction solvent in a reaction vessel to produce an oxamide. A rotary cylinder having a large number of nozzles for ejecting ammonia gas, which are provided so as to project in a direction intersecting with the rotation axis in the reaction vessel, is immersed in the mixed liquid so as to be rotatable about the rotation axis. A method for producing an oxamide, which is characterized.