JP6611391B1 - Methacrylic acid production equipment - Google Patents

Abstract

An apparatus for producing methacrylic acid having excellent continuous operability is provided. An apparatus 100 for producing methacrylic acid includes a first reactor 10 for obtaining methacrolein, a second reactor 20 for obtaining methacrylic acid, a methacrolein recovery means 70, an outlet 10j of the first reactor 10, and A line LA connecting the inlet 20i of the second reactor 20, a line LB connecting the line LA and the oxygen supply source, a line connecting the outlet 20j of the second reactor 20 and the liquid inlet 70i of the methacrolein recovery means 70. LC and a line LD connecting the gas outlet 70gj of the methacrolein recovery means 70 and the line LA, the line LD has a heating means 23a, and the heating means 23a is a connecting portion from the gas outlet 70gj to the line LA. When the length of the line up to Xo is 100, the gas outlets 70gj to 30 are arranged at least in part. [Selection] Figure 1

Description

  The present invention relates to an apparatus for producing methacrylic acid.

  Patent Document 1 describes a method for producing methacrylic acid.

International Publication No. 2008/145417

  The manufacturing apparatus used for manufacturing methacrylic acid is required to be able to operate continuously over a long period of time. Then, an object of this invention is to provide the manufacturing apparatus of methacrylic acid which is excellent in continuous operativity.

  The apparatus for producing methacrylic acid of the present invention has an inlet and an outlet, a first reactor for obtaining methacrolein from isobutylene and / or tert-butyl alcohol (hereinafter referred to as “TBA”) and oxygen, and an inlet And a second reactor for reacting methacrolein and oxygen to obtain methacrylic acid, a methacrolein recovery means having a liquid inlet, a liquid outlet and a gas outlet, an outlet of the first reactor, and a second reaction A line LA connecting the inlet of the reactor, a line LB connecting the line LA and the oxygen supply source, a line LC connecting the outlet of the second reactor and the liquid inlet of the methacrolein recovery means, and the gas of the methacrolein recovery means A line LD connecting the outlet and the line LA, the line LD has a heating means, the heating means from the gas outlet to the connection portion Xo to the line LA When the length of the line is 100, it is arranged at least at a part of the position from the gas outlet to 30.

  Such an apparatus for producing methacrylic acid is excellent in continuous operation.

  The heating means may be disposed in at least a part of the position from the gas outlet to 20 or may be disposed in at least a part of the position from the gas outlet to 10. As a result, continuous operation is further improved.

  The length of the line from the gas outlet to the inlet of the heating means may be 3 m or less. As a result, continuous operation is further improved.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing apparatus of methacrylic acid which is excellent in continuous operativity can be provided.

It is a figure which shows an example of the manufacturing apparatus of methacrylic acid of this embodiment.

  As used herein, isobutylene refers to 2-methylpropene.

  First, a methacrylic acid production apparatus 100 according to this embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a methacrylic acid production apparatus according to the present embodiment.

  The production apparatus 100 mainly includes a first reactor 10, a second reactor 20, a liquefaction means 60, a methacrolein recovery means 70, and lines LA, LB, LC, and LD. The line LA includes a gas mixer 50b. Line LB includes a compressor 55. The line LD includes a heating unit 23a.

  A gas supply source (S0) containing isobutylene and / or TBA and oxygen is connected to the inlet 10i of the first reactor 10 via a line L10.

  The first reactor 10 is a reactor for obtaining methacrolein from isobutylene and / or TBA and oxygen. The first reactor 10 is preferably a reactor in which a container is filled with a catalyst. The first reactor 10 can be a fixed bed reactor filled with a catalyst in a vessel. There is no restriction on the direction of flow, and it may be upflow or downflow. An example of a catalyst used in a reaction for synthesizing methacrolein from isobutylene and / or TBA and oxygen is a metal oxide containing molybdenum and bismuth.

  When obtaining methacrolein from isobutylene and oxygen, isobutylene and oxygen react to produce methacrolein. It is also possible to use TBA instead of isobutylene. When obtaining methacrolein from TBA and oxygen, it is considered that isobutylene is produced by the dehydration reaction of TBA, and the produced isobutylene and oxygen react to produce methacrolein. The reason why TBA can be used in place of isobutylene is considered to be that the oxidation reaction of isobutylene becomes rate limiting in the first reactor 10. Isobutylene and TBA can be used in combination.

  The outlet 10j of the first reactor 10 and the inlet 20i of the second reactor 20 are connected by a line LA.

The inlet 50b _m of gas mixer 50b of the line LA, line LB is connected. The line LB is a line that connects the line LA and the oxygen supply source (S1).

  The second reactor 20 is a reactor for obtaining methacrylic acid by reacting methacrolein and oxygen. The second reactor 20 is preferably a reactor filled with a catalyst in a container. The second reactor 20 can be a fixed bed reactor filled with a catalyst in a vessel. There is no limitation on the direction of flow, and it may be upflow or downflow. An example of the catalyst used in the reaction for synthesizing methacrylic acid from methacrolein and oxygen is a heteropolyacid compound containing phosphorus and molybdenum.

  The outlet 20j of the second reactor 20 and the liquid inlet 70i of the methacrolein recovery means 70 are connected by a line LC via the liquefaction means 60. The liquefaction means 60 has one inlet and three outlets. A line LC is connected to the inlet and one outlet of the liquefying means 60, and a line L35 and a line L31 are connected to the other two outlets, respectively.

  The liquefying means 60 is a means for liquefying methacrylic acid and unreacted methacrolein in the outlet gas flow (F30) of the second reactor 20. The liquefying means 60 may have a function of separating methacrolein. Examples of the liquefying means 60 include a distillation tower, an extraction tower, an absorption tower, and combinations thereof. The number of inlets and outlets of the liquefying means 60 can be changed according to the form of the liquefying means 60. For example, the line L35 and the line L31 may or may not exist. Further, other lines (not shown) may be connected to the liquefying means 60.

  The methacrolein collecting means 70 is a means for collecting methacrolein. The methacrolein recovery means 70 has a liquid inlet 70i, a liquid outlet 70j, and a gas outlet 70gj. Examples of the methacrolein recovery means 70 include a stripping tower, a distillation tower, and a combination thereof. In the stripping tower, methacrolein is separated by bringing a liquid containing methacrolein into contact with the stripping gas and entraining the stripping gas with methacrolein.

  When the methacrolein recovery means 70 is a diffusion tower, the methacrolein recovery means 70 has a gas inlet 70gi as shown in FIG. 1 in addition to the liquid inlet 70i, the liquid outlet 70j, and the gas outlet 70gj. When the methacrolein recovery means 70 is a distillation column, the gas inlet 70gi is not always necessary.

  The gas outlet 70gj is preferably provided at the top of the methacrolein recovery means 70 from the viewpoint of easily reducing the length of the line from the gas outlet 70gj to the inlet 23i of the heating means described later. The liquid outlet 70j is provided at the bottom of the methacrolein recovery means 70, for example.

  A line L40 is connected to the liquid outlet 70j of the methacrolein recovery means 70. The line L40 merges with the line L31.

  The gas outlet 70gj of the methacrolein recovery means 70 and the line LA are connected by a line LD.

  The heating means 23a is provided in a part of the line from the gas outlet 70gj to Xm. Here, when the length of the line from the gas outlet 70gj to the connection portion Xo with the line LA is 100, the length of the line from the gas outlet 70gj to Xm is 30 or less. That is, the heating means 23a is disposed at least at a part of the positions from the gas outlets 70gj to 30 when the length of the line from the gas outlet 70gj to the connection part Xo with the line LA is 100. Here, the length of the line refers to the length of the central axis of the line. The heating means 23a is a part of the line.

  From the viewpoint of further improving the continuous stability, the heating means 23a has at least one of the positions from the gas outlets 70gj to 20 when the length of the line from the gas outlet 70gj to the connection portion Xo with the line LA is 100. It is preferable that it is arrange | positioned at the part, and it is more preferable that it arrange | positions at least one part of the position from the gas outlets 70gj to 10.

  Examples of the heating means 23a include a heat exchanger, a jacket pipe, and a pipe wound with a sheet heater.

  The length of the line from the gas outlet 70gj to the inlet 23i of the heating means 23a is preferably 3 m or less from the viewpoint of further improving the continuous operability. The heating means 23a may be provided directly at the gas outlet 70gj. From the viewpoint of continuous stability and simplification of the apparatus, the gas outlet 70gj may be provided at the top of the methacrolein recovery means 70, and the heating means 23a may be provided directly at the gas outlet 70gj.

Then, the manufacturing method of methacrylic acid concerning this embodiment is explained.

(supply source)
A stream (F10) containing isobutylene and / or TBA and oxygen as a gas source (S0) containing isobutylene and / or TBA and oxygen is prepared.

  Stream (F10) may contain components other than isobutylene, TBA and oxygen. Components other than isobutylene, TBA and oxygen include, for example, C5 olefins such as isoprene, isobutane, 1-butene, 2-butene (cis, trans), propane, propylene, n-butane, methyl-tert-butyl ether, methanol , Dimethyl ether, butadiene, propadiene, diisobutylene, nitrogen, carbon monoxide, carbon dioxide, water and argon.

  The concentration of isobutylene and / or TBA in the stream (F10) is, for example, 1% by mass or more, 2% by mass or more, or 4% by mass or more in terms of the total concentration of isobutylene and TBA. The total concentration of isobutylene and TBA in the stream (F10) is, for example, 21% by mass or less, 19% by mass or less, or 17% by mass or less. The total concentration of isobutylene and TBA in the stream (F10) is preferably 1 to 21% by mass, more preferably 2 to 19% by mass, and even more preferably 4 to 17% by mass.

  The oxygen concentration in the flow (F10) is, for example, 7% by mass or more, 8% by mass or more, or 10% by mass or more. The oxygen concentration in the flow (F10) is, for example, 24% by mass or less, 23% by mass or less, or 21% by mass or less. The oxygen concentration in the stream (F10) is preferably 7 to 24% by mass, more preferably 8 to 23% by mass, and still more preferably 10 to 21% by mass.

  Moreover, the flow (F22) containing oxygen as an oxygen supply source (S1) is prepared.

  The concentration of oxygen in the flow (F22) is, for example, 15% by mass or more. The concentration of oxygen in the stream (F22) is preferably 16% by mass or more, more preferably 17% by mass or more, and further preferably 20% by mass or more. The upper limit of the concentration of oxygen in the flow (F22) can be set to 35% by mass, for example. The concentration of oxygen in the flow (F22) may be, for example, 30% by mass or less, or 25% by mass or less. The oxygen concentration in the stream (F22) is preferably 16 to 35% by mass, more preferably 17 to 30% by mass, and still more preferably 18 to 25% by mass.

(Reaction process)
A stream (F10) is fed to the first reactor 10 where the isobutylene and oxygen in the stream (F10) are reacted. A stream (F11) containing methacrolein obtained by the reaction of isobutylene and oxygen is discharged from the line LA.

  The reaction temperature of the first reactor 10 can be 300 to 400 ° C. The reaction pressure of the first reactor 10 can be 0.004 to 0.6 MPaG (gauge pressure).

  The stream (F11) discharged from the first reactor 10 is mixed with a later-described recycle stream (F23) containing methacrolein and a diffused gas via a line LD, and a stream containing oxygen via a line LB ( F22) is mixed. Thereby, the obtained flow (F21) is supplied to the second reactor 20 via the line LA.

  In the second reactor 20, methacrolein and oxygen are reacted to obtain methacrylic acid, and a stream (F30) containing methacrylic acid is discharged via a line LC.

  The stream (F30) contains unreacted methacrolein. The stream (F30) may contain components other than methacrylic acid and methacrolein. Such components include acrylic acid, acrolein, nitrogen, argon, water, carbon monoxide, carbon dioxide, acetaldehyde, propionaldehyde, terephthalic acid, maleic acid, fumaric acid, diacetyl, isophthalic acid, isobutyric acid, methylfurfural, Examples include acetic acid and propionic acid.

  The reaction temperature of the second reactor 20 can be 200 to 350 ° C. The reaction pressure in the second reactor 20 is, for example, 0.01 to 0.3 MPaG.

(Liquefaction process)
The stream (F30) leaving the second reactor 20 is supplied to the liquefaction means 60 via the line LC. In the liquefaction means 60, methacrylic acid and methacrolein in the stream (F30) are liquefied, for example, a stream (F31) containing methacrylic acid and heavy components from the line L31, carbon monoxide, carbon dioxide, A stream containing nitrogen, argon, other light components and oxygen (F35) and a stream containing methacrolein (F34) are extracted from the line LC, respectively.

(Metachlorein recovery process)
The stream containing methacrolein (F34) is supplied to the methacrolein recovery means 70 via the line LC.

  When the methacrolein recovery means 70 is a diffusion tower, a flow containing a diffusion gas is supplied to the gas inlet 70gi, a flow (F40) containing methacrylic acid and heavy components is supplied from the liquid outlet 70j, and methacrolein is supplied from the gas outlet 70gj. And the stream (F23) containing the emitted gas is discharged respectively. The emitted gas may be a gas that can diffuse methacrolein when it comes into contact with a liquid containing methacrolein. The emitted gas may contain at least one gas component selected from the group consisting of nitrogen, argon, oxygen and carbon dioxide.

  When the methacrolein recovery means 70 is a distillation column, for example, a flow (F40) containing methacrylic acid and heavy components from the liquid outlet 70j and a stream (F23) containing methacrolein from the gas outlet 70gj are obtained by distillation operation. Each can be discharged.

  The temperature of the flow (F23) at the gas outlet 70gj of the methacrolein recovery means 70 may be, for example, 50 to 90 ° C, 55 to 85 ° C, or 60 to 80 ° C. .

  The concentration of methacrolein in the stream (F23) is preferably 0.1% by mass or more, more preferably 3% by mass or more, and further preferably 7% by mass or more. The concentration of methacrolein in (F23) is preferably 32% by mass or less, more preferably 23% by mass or less, and still more preferably 16% by mass or less. The concentration of methacrolein in the flow (F23) may be 0.1 to 32% by mass, 3 to 23% by mass, or 7 to 16% by mass. The stream (F23) may contain, for example, nitrogen, argon, oxygen, water and carbon dioxide as components other than methacrolein.

  The flow (F40) joins the flow (F31).

  The flow (F23) is heated by the heating means 23a. The temperature of the heated stream (F23) may be, for example, 150 ° C. or higher, 170 ° C. or higher, or 190 ° C. or higher. The temperature of the heated stream (F23) may be, for example, 285 ° C. or lower, 250 ° C. or lower, or 220 ° C. or lower. 150-285 degreeC may be sufficient as the temperature of the stream (F23) after a heating, for example, 170-250 degreeC may be sufficient, and 190-220 degreeC may be sufficient.

  The flow (F23) heated by the heating means 23a is joined to the flow (F11) as a recycle flow.

  The methacrylic acid production apparatus 100 has an inlet 10i and an outlet 10j, a first reactor 10 for obtaining methacrolein from isobutylene and / or TBA and oxygen, an inlet 20i and an outlet 20j, methacrolein and oxygen Of the second reactor 20 to obtain methacrylic acid, a methacrolein recovery means 70 having a liquid inlet 70i, a liquid outlet 70j and a gas outlet 70gj, an outlet 10j of the first reactor 10, and a second reactor 20 A line LA connecting the inlet 20i, a line LB connecting the line LA and the oxygen supply source (S1), a line LC connecting the outlet 20j of the second reactor 20 and the liquid inlet 70i of the methacrolein recovery means 70, A gas outlet 70gj of the methacrolein recovery means 70 and a line LD connecting the line LA, the line LD being a heating means A heating means the length of the line from the gas outlet 70gj to connecting portion Xo is taken as 100, it is disposed on at least part of the position of the gas outlet 70gj to 30. Thereby, it is excellent in continuous drivability. In such an apparatus, the inventors presume the reason why it is excellent in continuous operability as follows.

  When the methacrolein recovered from the gas outlet of the methacrolein recovery means 70 is recycled to the second reactor, if it is recycled at the same temperature, methacrolein may be liquefied and polymerized, or heavy components may be precipitated. Conceivable. If the continuous operation is continued as it is, the amount of methacrolein recycled from the methacrolein recovery means 70 to the second reactor decreases, and as a result, the productivity of methacrylic acid may decrease. Further, since the amount of methacrolein recycled affects the component composition at the inlet of the second reactor, it is considered that the reaction in the second reactor is also affected. As a result, continuous operation may become difficult. On the other hand, the methacrylic acid production apparatus 100 is provided with the heating means 23a at the position of the line LD, so that methacrolein can easily reduce liquefaction and precipitation of heavy components, and keep the second reactor in a steady state. It is considered easy. Therefore, even if it is operated over a long period of time, it is easy to operate stably and excellent in continuous operation.

  Moreover, since the apparatus of this embodiment is excellent in continuous operability, it is considered possible to reduce raw materials and energy during long-term operation.

  The present invention is not limited to the above-described embodiment, and various modifications can be made.

  For example, each of the first reactor 10 and the second reactor 20 may be a plurality of unit reactors connected in series or in parallel. Further, separation / purification means such as a distillation column and an extraction column may be added to each line.

  The line L40 does not necessarily have to join the line L31. That is, the flow (F40) and the flow (F31) may be separately sent to the next step.

  The gas mixer 50b can be omitted. In this case, the line LB can be directly connected to the piping of the line LA.

  In the methacrylic acid production apparatus 100, the heating means 23a is arranged at a part of the positions from the gas outlets 70gj to 30 when the length of the line from the gas outlet 70gj to the connection part Xo with the line LA is 100. However, the heating means may be disposed at all of the positions from the gas outlets 70gj to 30.

  The line LD may further include other heating means at a place other than the positions from the gas outlets 70gj to 30.

  DESCRIPTION OF SYMBOLS 10 ... 1st reactor, 20 ... 2nd reactor, 50b ... Gas mixer, 60 ... Liquefaction means, 70 ... Methacrolein collection | recovery means, 23a ... Heating means, 100 ... Production apparatus of methacrylic acid.

Claims (6)

A first reactor having an inlet and an outlet and obtaining methacrolein from isobutylene and / or tert-butyl alcohol and oxygen;
A second reactor having an inlet and an outlet and reacting methacrolein and oxygen to obtain methacrylic acid;
Methacrolein recovery means having a liquid inlet, a liquid outlet and a gas outlet;
A line LA connecting the outlet of the first reactor and the inlet of the second reactor;
A line LB connecting the line LA and the oxygen supply source;
A line LC connecting the outlet of the second reactor and the liquid inlet of the methacrolein recovery means;
A line LD connecting the gas outlet of the methacrolein recovery means and the line LA;
The line LD has a heating means,
The heating means is disposed in at least a part of the position from the gas outlet to 30 when the length of the line from the gas outlet to the connection portion Xo with the line LA is 100.
It said heating means, Ri means der for heating a flow comprising methacrolein over 0.99 ° C.,
The methacrolein recovery means, Ru desorption column der apparatus for producing methacrylic acid.   The apparatus for producing methacrylic acid according to claim 1, wherein the heating means is a means for heating a stream containing methacrolein to 150 ° C or higher and 250 ° C or lower.   The apparatus for producing methacrylic acid according to claim 1 or 2, wherein the heating means is disposed at least at a part of the position from the gas outlet to 20.   The apparatus for producing methacrylic acid according to any one of claims 1 to 3, wherein the heating means is disposed at least at a part of the position from the gas outlet to 10.   The apparatus for producing methacrylic acid according to any one of claims 1 to 3, wherein the heating means is disposed at least at a part of positions 10 to 30 from the gas outlet.   The apparatus for producing methacrylic acid according to any one of claims 1 to 5, wherein a length of a line from the gas outlet to the inlet of the heating unit is 3 m or less.

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