JP4186459B2 - Tower equipment for easily polymerizable compounds - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to tower equipment such as an easily polymerizable compound distillation tower, evaporation tower or high boiling point decomposition reaction tower, and more particularly to a tower equipment having a reboiler.
[0002]
[Prior art]
In a production facility for easily polymerizable compounds such as (meth) acrylic acid and (meth) acrylic acid ester, a distillation column of high molecular weight (meth) acrylic acid or a crude (meth) acrylic acid ester or a high-boiling product is decomposed ( Tower equipment such as a decomposition reaction tower for recovering (meth) acrylic acid or the like is used.
[0003]
In such tower equipment, a part of the tower bottom liquid may be introduced into the reboiler and heated and then returned to the tower bottom.
[0004]
Conventionally, the introduction tubular member for introducing the column bottom liquid into the reboiler is provided so as to be continuous with the bottom surface of the lower end of the column.
[0005]
[Problems to be solved by the invention]
According to such a connection structure of the tower bottom liquid introduction tubular member to the conventional reboiler, a polymer, a polymerization inhibitor or the like contained in the tower bottom liquid easily enters the introduction tubular member. And this polymer and a polymerization inhibitor may accumulate on a reboiler and may cause clogging. This polymerization inhibitor is added in the production process of the easily polymerizable compound. Polymers include those brought in from upstream facilities and those generated in the tower facilities.
[0006]
As a countermeasure against the above blockage, when a forced circulation pump is provided in the introduction tubular member, a strainer may be provided in the introduction tubular member to separate a polymer or a polymerization inhibitor by filtration. However, when the opening of the strainer is increased, the separation by filtration becomes insufficient, and the reboiler blocking prevention effect becomes insufficient. Conversely, if the strainer opening is reduced, the strainer clogs frequently, and the operation of the tower equipment tends to become unstable. In addition, in a natural circulation type reboiler, such a strainer cannot be installed, and measures for preventing inflow of a polymer or a polymerization inhibitor into the reboiler are not adopted.
[0007]
The present invention solves the above-mentioned conventional problems and can suppress the inflow of a polymer or a polymerization inhibitor into the reboiler with a simple mechanism, thereby enabling the tower equipment to be stably and continuously operated over a long period of time. For the purpose.
[0008]
[Means for Solving the Problems]
[0009]
The tower equipment for an easily polymerizable compound of the present invention (Claim 1 ) is a tower equipment for treating the easily polymerizable compound, and the tower body and the bottom liquid of the tower body are provided with a tubular member for introduction. In the tower equipment for an easily polymerizable compound having a reboiler introduced through the pot, the tower main body has a pot portion protruding downward at the lower end portion, and an extraction tube projecting downward from the lower end of the pot portion. An extraction pipe connected to the lower end of the extraction tubular member, the introduction tubular member is connected to the side surface of the pot portion, and the vicinity of the upstream end of the introduction tubular member is It is characterized by a horizontal or upward slope toward the downstream side .
[0010]
The tower equipment for an easily polymerizable compound of the present invention (Claim 2 ) is a tower equipment for treating the easily polymerizable compound, and the tower main body and the tower bottom liquid of the tower body are provided with a tubular member for introduction. In the tower equipment for an easily polymerizable compound having a reboiler introduced through the pipe, a tubular member for extracting the bottom liquid of the tower extends downward from the lower end of the tower main body , and is pulled out to the lower end of the tubular member for extraction. Outlet piping is connected , the introduction tubular member is connected to the side surface of the extraction tubular member, and the vicinity of the upstream end of the introduction tubular member is horizontal or ascending toward the downstream side . It is characterized by this.
[0011]
In the present invention (claims 1 and 2 ), the tubular member for introducing the bottom liquid into the reboiler extends sideways. Since the polymer and polymerization inhibitor contained in the column bottom liquid tend to flow down vertically, it is difficult to enter the tubular member for introduction. For this reason, according to this invention, the quantity of the polymer which flows into a reboiler via a tubular member for introduction, or a polymerization inhibitor decreases, and blockage with a reboiler is prevented.
[0012]
In the present invention, in the vicinity of the upstream end of the introduction tubular member, that is, in the vicinity where the introduction tubular member is connected to the tower main body, its pot portion or the extraction tubular member, the introduction tubular member has a horizontal or upward gradient toward the downstream side. It is preferable that In this way, the amount of the polymer or polymerization inhibitor flowing into the introduction tubular member is further reduced, and the reboiler is more reliably prevented from being blocked.
[0013]
Examples of the easily polymerizable compound that is an object of the present invention include at least one of acrylic acid, methacrylic acid, and esters thereof.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments will be described with reference to the drawings. 1, 2 and 3 are longitudinal sectional views of the vicinity of the lower part of the tower for the easily polymerizable compound according to the embodiment, and FIGS. 4 and 5 are systems of a distillation apparatus and a decomposition reaction apparatus employing this tower equipment. FIG.
[0015]
In the tower facilities of FIGS. 1, 2 and 3, the tower bottom liquid of the tower body 1 is introduced into the reboiler 5 through the introduction nozzle 3 and the pipe 4 as the introduction tubular member and heated, and then the pipe 6 And returned to the tower body 1 through the nozzle 7. The nozzle 7 protrudes from the tower body 1. Flange 3a, 7a is provided in the front-end | tip of the protrusion direction of nozzle 3, 7, and flange 4a, 6a provided in piping 4, 6 is connected with flange 3a, 7a, respectively.
[0016]
In FIGS. 1 and 3, an extraction nozzle 2 as a tubular member for extraction from the lower end of the tower bottom mirror portion of the tower main body 1 is provided to project vertically downward. In FIG. 2, the extraction nozzle 2 protrudes vertically downward from the lower end of the pot portion 10. A flange 11 a of the extraction pipe 11 is connected to a flange 2 a provided at the lower end of the extraction nozzle 2.
[0017]
In the tower facility of FIG. 1, the introduction nozzle 3 protrudes laterally from the lower side surface of the tower body 1. In the tower facility of FIG. 2, the tower main body 1 includes a pot portion 10 that bulges downward at the lower end portion, and the introduction nozzle 3 projects from the side surface of the pot portion 10. In the tower facility of FIG. 3, the introduction nozzle 3 is projected from the side surface of the extraction nozzle 2.
[0018]
In any of the tower facilities, “near the upstream end of the tubular member for extraction” is composed of the introduction nozzle 3. The introduction nozzle 3 is provided so as to have an upward gradient toward the horizontal or downstream side. That is, the introduction nozzle 3 has an angle (elevation angle) θ with respect to a horizontal line with respect to the downstream side (direction toward the reboiler 5) of 0 ° or more, preferably 0 to 85 °.
[0019]
The length of the introduction nozzle 3 is preferably 0.05 times or more, for example, 0.08 to 3 times the tube diameter of the introduction nozzle 3 (inner diameter or less, similarly). Nozzles with this ratio of less than 0.05 are difficult to construct, and if it exceeds 3, the protrusions from the tower body become large, which is also unfavorable for construction.
[0020]
In the embodiment of FIG. 3, the ratio a / b between the tube diameter a of the extraction nozzle 2 and the tube diameter b of the introduction nozzle 3 is preferably 0.5 or more, particularly 0.5-2. When a / b is smaller than 0.5, the solid content in the column bottom liquid is slightly taken into the introduction nozzle 3.
[0021]
In any embodiment, since the introduction nozzle 3 is provided in a horizontal or upward gradient, a polymer or a polymerization inhibitor contained in the column bottom liquid in the column main body 1, the pot unit 10 or the extraction nozzle 2. Are difficult to enter into the introduction nozzle 3, and therefore, they are prevented from accumulating in the reboiler 5 and causing clogging.
[0022]
FIG. 4 shows an acrylic acid distillation apparatus employing the tower equipment of FIG. 1, and the tower body 1 is used as a distillation tower.
[0023]
Crude acrylic acid is introduced into the distillation column 1 and distilled, and a part of the column bottom liquid is circulated in the order of the extraction nozzle 2, the introduction nozzle 3, the piping 4, the reboiler 5, the piping 6, and the nozzle 7. Further, the tower bottom liquid is taken out as a residue through the extraction nozzle 2, the pipe 11, the pump 12, and the pipe 13.
[0024]
The distillate from the top of the column is introduced into the reflux tank 21 through the pipe 19 and the condenser 20 for condensation. A part of the acrylic acid in the reflux tank 21 is returned to the top of the tower via the pump 22 and the pipe 23. The remaining acrylic acid is taken out as purified acrylic acid through a pipe 24 branched from the pipe 23. The gas in the reflux tank 21 is cooled again by the vent gas condenser 25, the condensed acrylic acid returns to the reflux tank 21, and the gas component is taken out as a vent gas through the vacuum facility 26.
[0025]
4 employs the tower equipment of FIG. 3, it is obvious that the tower equipment of FIG. 1 or FIG. 2 may be adopted. In this case, the position of the introduction nozzle 3 is as shown in FIG. The other configuration is as shown in FIG. In any case, the tower bottom temperature is preferably 60 to 120 ° C., particularly preferably 70 to 100 ° C., and the pressure is preferably 1 to 50 kPa, particularly 2 to 20 kPa.
[0026]
FIG. 5 shows the tower body 1 as a decomposition reaction tower for high-boiling substances produced in the acrylic acid or acrylate ester production process. The high-boiling substances are introduced into the reaction tower 1 and subjected to a decomposition reaction. A part of the column bottom liquid is returned to the reaction column 1 through the extraction nozzle 2, the introduction nozzle 3, the piping 4, the pump 40, the reboiler 5, the piping 6 and the nozzle 7. The tower bottom liquid is also taken out through the extraction nozzle 2, the pipe 11, the pump 12 and the pipe 13.
[0027]
The gaseous decomposition product is introduced into the liquid tank 31 from the top of the tower via the pipe 29 and the tower top gas cooling heat exchanger 30. The liquid in the liquid tank 31 is taken out as a recovered liquid via the pump 32 and the pipe 33. A part of the column bottom liquid is returned to the heat exchanger 30 through a pipe 34 branched from the pipe 33. The gas in the liquid tank 31 is cooled by the vent gas cooling heat exchanger 35, the condensate is returned to the liquid tank, and the uncondensed gas is taken out via the pipe 36.
[0028]
Although FIG. 5 employs the tower equipment of FIG. 3, the tower equipment of FIGS. In this case, the position of the introduction nozzle 3 is as shown in FIGS. 1 and 2, and the other configuration is as shown in FIG. In any case, the decomposition reaction temperature is preferably 110 to 250 ° C., particularly preferably 120 to 230 ° C., and the decomposition reaction time is 0.5 to 50 hours (when the decomposition temperature is low, 10 to 50 hours, when high) Is preferably 0.5 to 10 hours), and the pressure may be reduced or normal pressure.
[0029]
As shown in the figure, in the present invention, a pump may be provided in the middle of the introduction tubular member, upstream of the reboiler.
[0030]
Hereinafter, incidental items of the present invention will be described.
[0031]
<Easily polymerizable compound>
Typical examples of the easily polymerizable compound that is an object to be handled by the tower equipment of the present invention are (meth) acrylic acid and (meth) acrylic acid esters. Acrylic esters include methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, tertiary butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, acrylic And methoxyethyl acid. Examples of the methacrylic acid esters include the same compounds as these.
[0032]
<Process for producing acrylic acid or acrylic esters>
Examples of the process for producing acrylic acid include the following (1) to (3).
(1) Oxidation step for contact gas phase oxidation of propylene and / or acrolein, collection step for contacting acrylic acid-containing gas from the oxidation step with water to collect acrylic acid as an aqueous acrylic acid solution, from this aqueous acrylic acid solution Extraction step of extracting acrylic acid using a suitable extraction solvent, followed by separation of acrylic acid and solvent, purification by providing a purification step, and further adding Michael Acrylic acid adduct and polymerization inhibitor used in each step The high boiling liquid containing is supplied to the decomposition reaction tower as a raw material to recover valuables, and the valuables are supplied to any step after the collection step. (2) Catalytic gas phase oxidation of propylene and / or acrolein Oxidation process for producing acrylic acid, a collection process for collecting acrylic acid as an acrylic acid aqueous solution by bringing acrylic acid-containing gas into contact with water, and this acrylic acid aqueous solution In an azeotropic separation tower, distillation is performed in the presence of an azeotropic solvent to remove crude acrylic acid from the bottom, followed by an acetic acid separation process for removing acetic acid, and further purification for removing high-boiling impurities. A high-boiling liquid containing a Michael adduct after purification and a polymerization inhibitor used in these production steps is supplied to the cracking reaction tower as a raw material to recover the valuable material. Supplying to any of the steps after the collection step (3) Oxidation step of producing acrylic acid by contact gas phase oxidation of propylene and / or acrolein, acrylic acid containing acrylic acid by contacting acrylic acid-containing gas with organic solvent A collection / separation process in which water is collected as an acid organic solvent solution and water, acetic acid, and the like are simultaneously removed, a separation process in which acrylic acid is extracted from the acrylic acid organic solvent solution, and further used in these production processes. A high-boiling liquid containing a polymerization inhibitor, an organic solvent, and Michael Acrylate adduct is supplied as raw materials to the decomposition reaction tower to recover valuable materials, and the valuable materials are supplied to any step after the collection step. Consisting of a step, a step of partially purifying the organic solvent.
The step of producing an acrylate ester is, for example, an esterification reaction step in which acrylic acid and alcohol are reacted with an organic acid or a cationic ion exchange resin as a catalyst, in order to concentrate the crude acrylate solution obtained by the reaction. It consists of a purification process that performs extraction, evaporation, and distillation as a unit operation. Each unit operation is appropriately selected depending on the raw material ratio of acrylic acid and alcohol in the esterification reaction, the catalyst species used in the esterification reaction, or the physical properties of the raw materials, reaction by-products, and acrylic esters. After each unit operation, a product is obtained in the acrylic ester purification tower. The liquid at the bottom of the purification tower contains Michael adducts mainly composed of acrylic acid esters, β-acryloxypropionic acid esters, β-alkoxypropionic acid esters, β-hydroxypropionic acid esters, and in the production process. The high-boiling liquid containing the used polymerization inhibitor is supplied to the decomposition reaction tower, or valuables are recovered by returning to the process.
[0034]
Depending on the alcohol species, acrylic acid obtained from any of the various production processes other than the bottom of the purification column of acrylic ester products, acrylic acid dimer (hereinafter referred to as dimer), acrylic acid trimer (hereinafter referred to as trimer), There is also a high boiling liquid containing β-alkoxypropionic acids and β-alkoxypropionic acid esters as the main components and a polymerization inhibitor used in the production process, and it is supplied to the decomposition reaction tower as a high boiling liquid containing Michael adducts. In some cases, valuable materials are recovered and the valuable materials are supplied to the reaction process or the purification process.
[0035]
The above-mentioned Michael adduct of acrylic acid or acrylate ester is, for example, a Michael adduct when producing acrylic acid, an acrylic acid dimer (hereinafter referred to as dimer), an acrylic acid trimer (hereinafter referred to as trimer), Acrylic acid tetramer (hereinafter referred to as tetramer) and the like, and as an Michael adduct when producing an acrylic ester, acrylic to the above-mentioned acrylic ester such as an alkyl ester or cycloalkyl ester having 2 to 8 carbon atoms Michael adduct of acid, specifically β-acryloxypropionate ester, Michael adduct of alcohol, specifically β-alkoxypropionate ester, dimer, trimer, tetramer, trimer ester, tetramer ester , Β-hydroxypropionic acid, β-hydroxypropionic acid ester Etc. The.
[0036]
Further, in the production of acrylic acid or acrylic acid esters which are easily polymerizable compounds, as described above, a polymerization inhibitor is used to suppress the generation of a polymer during production.
[0037]
Specific examples of the polymerization inhibitor include copper acrylate, copper dithiocarbamate, phenol compounds, and phenothiazine compounds. Examples of copper dithiocarbamate include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dipropyldithiocarbamate, copper dibutyldithiocarbamate, copper diethylenedithiocarbamate, copper ethylenedithiocarbamate, copper tetramethylenedithiocarbamate, copper pentamethylenedithiocarbamate, Examples thereof include cyclic alkylene dithiocarbamate copper such as copper hexamethylenedithiocarbamate, and cyclic oxydialkylene dithiocarbamate copper such as copper oxydiethylenedithiocarbamate. Examples of the phenol compound include hydroquinone, methoquinone, pyrogallol, catechol, resorcin, phenol, or cresol. Examples of the phenothiazine compound include phenothiazine, bis- (α-methylbenzyl) phenothiazine, 3,7-dioctylphenothiazine, bis- (α-dimethylbenzyl) phenothiazine and the like.
[0038]
Substances other than those mentioned above may be included depending on the process, but obviously the type does not affect the present invention.
[0039]
<Distillation tower>
The distillation column of the present invention is generally used in a chemical plant.
[0040]
A tray or packing is installed in the column of the distillation column. Specifically, examples of the tray include a bubble bell tray with a downcomer, a perforated plate tray, a valve tray, a super flack tray, and a max flux tray, and a dual tray without a downcomer.
[0041]
As the packing, regular packing, Sulzer Pack manufactured by Sulzer Brothers Co., Ltd., Sumitomo Sulzer Packing manufactured by Sumitomo Heavy Industries, Ltd., Merapack manufactured by Sumitomo Heavy Industries, Ltd., Glitch Co., Ltd. Gem Pack, Monz Pack by Monz Co., Good Roll Packing by Tokyo Special Wire Mesh Co., Ltd., NGK Honeycomb Pack, Nagaoka Co. Impulse Packing, Mitsubishi Chemical Engineering Co., Ltd. MC pack etc. The irregular packing includes an interlock saddle manufactured by Norton Co., Ltd., a terrarette manufactured by Nippon Steel Chemical Industries, Ltd., a pole ring manufactured by BASF Co., Ltd., and a cascade mini ring manufactured by Mass Transfer Co., Ltd. There are flexi rings made by JGC Corporation.
[0042]
In the present invention, it is not limited to these types, and one or more types of trays and fillers can be used in combination as generally used.
[0043]
<Reboiler>
In the present invention, the tower bottom liquid heating heat exchanger attached to each tower is a reboiler. Generally, it is roughly classified into a case where it is installed inside the tower and a case where it is installed outside the tower, but the present invention is intended for those installed outside the tower.
[0044]
The type of reboiler is not particularly limited. Specific examples include a vertical fixed tube plate type, a horizontal fixed tube plate type, a U-tube type, a double tube type, a spiral type, a square block type, a plate type, and a thin film evaporator type.
[0045]
<Evaporation tower>
The evaporation tower of the present invention is one generally used in chemical plants. That is, it comprises an evaporator and a reboiler, and if necessary, is constituted by a cooling heat exchanger for condensing evaporated gas, a tank for storing condensate, a pump for sending condensate, and the like. There is no limitation in the present invention.
[0046]
<Material>
The materials of the various nozzles, the tower body, the reboiler, and the piping of each tower are selected depending on the easily polymerizable compound to be handled and the temperature conditions, but are not limited in the present invention. For example, in the production of typical (meth) acrylic acid and (meth) acrylic acid esters as easily polymerizable substances, stainless steels are often used, but are not limited thereto. For example, SUS304, SUS304L, SUS316, SUS316L, SUS317, SUS317L, SUS327, or hastelloys are used, and may be selected corresponding to each liquid physical property from the viewpoint of corrosion resistance.
[0047]
【Example】
Example 1
The decomposition reaction of the high boiling liquid was carried out using the decomposition reaction apparatus of FIG. The elevation angle θ of the introduction nozzle 3 was set to 45 °. The tube diameters a and b of the nozzles 2 and 3 are both 155.2 mm (6B size) and a / b = 1. The pipe 41 has a pipe diameter of 106.3 mm (4B size). The cracking reactor has a tower diameter of 1000 mm, a tower length of 2800 mm, and the material is Hastelloy C. The composition of the high boiling liquid is butyl acrylate 21% by weight, β-butoxypropionate butyl 65% by weight, acryloxypropionate butyl 4% by weight, β-hydroxypropionate butyl 2% by weight, hydroquinone 3% by weight, methoxyquinone 2 It was fed at 580 kg / h at 3% by weight and other 3% by weight.
[0048]
A 1% by weight aqueous solution of sulfuric acid was supplied as a decomposition reaction catalyst in a 10% weight ratio to the feed solution, and the decomposition reaction was carried out at a reaction pressure of 100 kPa, a decomposition temperature of 190 ° C. and a residence time of 1 hour. As a result, 8.7% by weight of butyl acrylate, 62.5% by weight of butyl β-butoxypropionate, 2% by weight of butyl acryloxypropionate, 0.3% by weight of butyl β-hydroxypropionate, hydroquinone 8 from the bottom of the tower 0.7 wt%, methoxyquinone 5.8 wt%, butanol 0.8 wt%, sulfuric acid 2.9 wt%, and other 9 wt%, 200.1 kg / h was obtained as a reaction residue, and was removed from the bottom of the column. It was issued.
[0049]
The reboiler is a vertical fixed tube plate heat exchanger. The amount of liquid supplied to the reboiler was measured with a flow meter installed at the outlet of the pump 40, and the initial value was 32,000 kg / h. The bottom liquid was circulated on the tube side of the reboiler.
[0050]
After three months of continuous operation, the operation was stopped and the reboiler was checked. As a result of the inspection, there was no accumulation, the reboiler supply liquid amount during operation was stable, and there was no blockage during operation.
[0051]
Example 2
The same operation as in Example 1 was performed except that the elevation angle θ of the introduction nozzle 3 was set to 0 ° (horizontal).
[0052]
After three months of continuous operation, the operation was stopped and the reboiler was checked. As a result of the inspection, there was no accumulation, and there was no blockage during operation.
[0053]
Comparative Example 1
The same operation as in Example 2 was performed except that the introduction nozzle 3 protruded vertically downward from the lowermost part of the tower body 1.
[0054]
After two months of operation, the reboiler feed volume began to decrease gradually. Suddenly, the operation of the cracking reaction tower was stopped and the inside was inspected, and as a result, the reboiler pipe was clogged.
[0055]
Example 3
Using the same apparatus as in Example 1, the high boiling liquid was decomposed.
[0056]
The composition of the high boiling liquid was 580 kg with 45.3% by weight of acrylic acid, 10% by weight of maleic acid, 42.4% by weight of acrylic acid dimer (acryloxypropionic acid), 1.3% by weight of hydroquinone and 1% by weight of phenothiazine. / H. As a result of carrying out the decomposition reaction at a reaction pressure of 72 kPa, a decomposition temperature of 190 ° C. and a residence time of 1 hour, acrylic acid 8% by weight, maleic acid 14% by weight, acrylic acid dimer (acryloxypropionic acid) 67.2% by weight from the tower bottom. 5.8% by weight of hydroquinone, 4.4% by weight of phenothiazine, 0.6% by weight of oligomer and polymer, 130.5 kg / h were obtained as reaction residues.
[0057]
After three months of continuous operation, the operation was stopped and the reboiler was checked. As a result of the inspection, there was no accumulation, the reboiler supply liquid amount during operation was stable, and there was no blockage during operation.
[0058]
Comparative Example 2
The same operation as in Example 3 was performed except that the introduction nozzle 3 protruded vertically downward from the lowermost part of the tower body 1.
[0059]
After one month of operation, the reboiler feed volume began to gradually decrease. Suddenly, the operation of the cracking reaction tower was stopped and the inside was inspected, and as a result, the reboiler pipe was clogged.
[0060]
Example 4
In the distillation apparatus shown in FIG. 4, crude acrylic acid was distilled using a stainless steel (SUS316) distillation tower having an inner diameter of 1100 mm, a length of 20000 mm, and 21 perforated plates (dual trays) installed therein. The extraction nozzle 2 and the introduction nozzle 3 have a tube diameter of 155.2 mm (6B size), and the elevation angle θ of the introduction nozzle 3 is 0 ° (horizontal). A pump was provided in the middle of the pipe 4. The pipe 4 has the same diameter as the introduction nozzle 3. As a crude acrylic monomer, a mixture containing 98.5% by weight of acrylic acid, 0.3% by weight of maleic acid, and 0.3% by weight of acrylic acid dimer was supplied at 90 ° C. at 1300 kg / h.
[0061]
Further, a solution obtained by dissolving 8% by weight of methoquinone and 1% by weight of phenothiazine in acrylic acid from a polymerization inhibitor-containing liquid tank is supplied at 34 kg / h and 31 kg / h, respectively, with a tower top pressure of 2.8 kPa and a tower bottom pressure of 7. By carrying out the operation at 9 kPa, a tower top temperature of 53 ° C., and a tower bottom temperature of 75 ° C., high purity acrylic acid having a purity of 99.8% by weight or more was obtained from the tower top.
[0062]
The reboiler was a vertical fixed tube plate heat exchanger, and the amount of liquid supplied to the reboiler was measured by a flow meter installed at the pump outlet of the pipe 4, and the initial value was 68,000 kg / h. The bottom liquid was circulated on the tube side of the reboiler.
[0063]
After 6 months of continuous operation, the operation was stopped and the reboiler was checked. As a result of the inspection, there was no accumulation, the reboiler supply liquid amount during operation was stable, and there was no blockage during operation.
[0064]
Comparative Example 3
The same operation as in Example 4 was performed except that the introduction nozzle 3 protruded vertically downward from the lowermost part of the tower body 1.
[0065]
After 4 months of operation, the amount of reboiler feed began to decrease gradually. As a result of stopping the operation of the cracking reaction tower and inspecting the inside, it was confirmed that the reboiler tube was blocked.
[0066]
【The invention's effect】
As described above, according to the present invention, the polymer and polymerization inhibitor in the column bottom liquid are suppressed from flowing into the reboiler, and the reboiler is prevented from being blocked. Therefore, it becomes possible to operate the tower equipment continuously and stably over a long period of time.
[Brief description of the drawings]
FIG. 1 is a vertical cross-sectional view of a lower part of tower equipment according to an embodiment.
FIG. 2 is a longitudinal sectional view of a lower part of tower equipment according to another embodiment.
FIG. 3 is a vertical cross-sectional view of a lower part of tower equipment according to still another embodiment.
FIG. 4 is a system diagram of a distillation apparatus employing tower equipment according to an embodiment.
FIG. 5 is a system diagram of a high boiling point decomposition reaction apparatus employing tower equipment according to an embodiment.
[Explanation of symbols]
1 tower body 2 extraction nozzle 3 introduction nozzle 5 reboiler 21 reflux tank 31 liquid tank

Claims (4)

A tower facility for treating easily polymerizable compounds,
In a tower facility for an easily polymerizable compound having a tower main body and a reboiler into which the tower bottom liquid of the tower main body is introduced through a tubular member for introduction,
The tower body includes a pot portion protruding downward at a lower end portion, an extraction tubular member protruding downward from the lower end of the pot portion, and an extraction pipe connected to the lower end of the extraction tubular member With
The introduction tubular member is connected to a side surface of the pot portion ;
A tower facility for an easily polymerizable compound, characterized in that the vicinity of the upstream end of the introduction tubular member is horizontal or ascending toward the downstream side . A tower facility for treating easily polymerizable compounds,
In a tower facility for an easily polymerizable compound having a tower main body and a reboiler into which the tower bottom liquid of the tower main body is introduced through a tubular member for introduction,
A tubular member for extracting tower bottom liquid extends downward from the lower end of the tower body , and an extraction pipe is connected to the lower end of the extracting tubular member ,
The introduction tubular member is connected to a side surface of the extraction tubular member ;
A tower facility for an easily polymerizable compound, characterized in that the vicinity of the upstream end of the introduction tubular member is horizontal or ascending toward the downstream side . 3. The tower equipment for easily polymerizable compounds according to claim 2 , wherein a ratio a / b between the tube diameter a of the tubular member for extraction and the tube diameter b of the tubular member for introduction is 0.5 or more. . The tower equipment according to any one of claims 1 to 3 , wherein the easily polymerizable compound is at least one of acrylic acid and / or methacrylic acid or an ester thereof.

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