JPH08259606A - Control of reaction temperature - Google Patents

Abstract

PURPOSE: To provide a method for controlling a polymerization reaction temperature, etc., having good energy efficiency, excellent in controlling property of reaction and capable of providing high productivity by dividing a flow path of heat medium for heating, etc., of a reactor into plural flow paths, feeding a refrigerant thereto and efficiently carrying out cooling of the reactor. CONSTITUTION: In controlling a reaction temperature by passing a heat medium (e.g. water) for cooling into flow paths 2A and 2B of heat medium for heating and/or cooling of a reactor 1, these paths 2A and 2B are divided into plural paths and two or more refrigerants different in temperature are used as the refrigerants and fed to flow paths 2A and 2B of divided cooling media and cooling of the reactor 1 is carried out to practice control of reaction temperature. Furthermore, the cooling system is preferably a Jacket type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a reaction temperature of a reactor which carries out an exothermic reaction, and more particularly to a method for adjusting a reaction temperature capable of effectively utilizing a cooling capacity of a refrigerant. is there. The present invention also relates to an efficient method for controlling the reaction temperature, particularly in the suspension polymerization method for vinyl chloride polymers.

[0002]

2. Description of the Related Art As a cooling system for a reactor that performs an exothermic reaction, 1) jacket type, 2) coil type, 3) reflux condenser type, 4)
It is customary to use one of external circulation coolers or a combination of two or more thereof. Among them, the method of using a cooling device attached to a reactor such as a jacket type or a coil type is simpler than the method of using a so-called heat exchanger and is widely used as a primary cooling method.

Using such a jacket or coil of the reactor (hereinafter collectively referred to as "jacket or the like"), a heat medium for cooling (hereinafter " In order to cool and remove the heat generated at the time of reaction by adjusting the reaction temperature, the cooling capacity at least commensurate with the amount of heat generated is required.

In particular, in a batch reaction involving exotherm, the calorific value fluctuates as the reaction progresses. Therefore, in order to stably control the reaction temperature, it is necessary to provide a sufficient cooling capacity capable of dealing with the exothermic peak. It is necessary to leave it. However, a cooling system that uses water cooled in a cooling water tower (cooling tower) that is widely used in a reactor equipped with a jacket or the like as a refrigerant has a relatively high refrigerant temperature, and due to the season or the temperature of the day, Since the temperature fluctuates, it is necessary to reserve a large margin for the cooling capacity in particular, and therefore it is necessary to operate under conditions that always allow for sudden temperature fluctuations. was there.

As a cooling system in which the fluctuation of the cooling temperature is small, it is general to use a refrigerant forcibly cooled by a refrigerator or the like. However, even with this method, it is necessary to prepare a refrigerating facility having a capacity capable of dealing with the above-mentioned exothermic peak, which requires a device having a capacity much larger than that required for steady operation, which causes increase in facility cost and a refrigerator. Since energy such as electric power is required for the operation of etc., it cannot be said that it is economically economical to perform all cooling by this method.

Further, for example, a batchwise polymerization reaction of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith (hereinafter collectively referred to as "vinyl chloride monomer"). Calorific value (ie load required for cooling)
Are generally greatly different at the beginning, middle and end of the reaction. Therefore, in the method using only the low-temperature refrigerant, it is necessary to greatly change the flow rate according to the progress of the reaction, but if the flow rate is too small, the heat transfer coefficient decreases and the flow rate of the refrigerant exceeds the decrease amount. If the flow rate of the refrigerant is increased in order to cope with this, the cooling efficiency will be lowered, and the temperature inside the reactor will be lowered due to supercooling, which may make the reaction control difficult. In addition, when the load required for cooling is large like a batch reaction, it is necessary to have a large-capacity buffer tank in order to prevent a rapid temperature change of the refrigerant, which increases equipment costs.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently utilizing the cooling capacity of a refrigerant in an exothermic reaction, particularly in a batch reaction involving heat generation in which a cooling load has a large temporal variation. To provide a method for controlling the reaction temperature that is highly efficient, has excellent reaction controllability, and can achieve high productivity. Among them, the reaction temperature of the batch polymerization reaction of the vinyl chloride-based monomer in an aqueous medium can be improved. It is to provide an effective adjustment method.

[0008]

That is, the gist of the present invention is as follows.
In adjusting the reaction temperature by passing the refrigerant through the jacket of the reactor, etc., the flow path was divided into a plurality of parts, and two or more refrigerants having different temperatures were used as the refrigerant, and the refrigerant was divided. A method for adjusting a reaction temperature, characterized in that the reactor is cooled by supplying the refrigerant to a flow path.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the description, the case where two refrigerants are used as the refrigerants having different temperatures is described as an example, and the refrigerant having the higher temperature is referred to as “refrigerant H” and the refrigerant having the lower temperature is referred to as “refrigerant L”. Also, when three or more refrigerants are used, the temperatures may be compared with each other and considered in the same manner.

The refrigerant used in the method of the present invention is not particularly limited, and a commonly used refrigerant can be used. Examples thereof include water, calcium chloride aqueous solution, ethylene glycol (including aqueous solution). ), Methanol, ethanol, freon, kerosene and the like are used, and among them, it is preferable to use water as at least one of the refrigerants because of its excellent handling safety and large heat capacity.

In the method of the present invention, examples of the cooling method for obtaining the refrigerant include a method using a cold water tower, a method using a refrigerator, and a method using heat exchange with a medium having a lower temperature as described above. In particular, the method using a cold water tower is a refrigerant H
The method using a refrigerator is suitable for obtaining the refrigerant L. In the method of the present invention, examples of the flow path of the heat medium for heating and / or cooling the reactor include a jacket type, a coil type, and a temperature control element type. Those suitable for application of the method of the present invention.

As the jacket type, in addition to the commonly used outer jacket type, an inner jacket type, a half pipe jacket and the like are used. As the coil type, a coiled coil, a hairpin coil, a plate coil or the like is used. Further, the temperature control element type means that partition plates are arranged side by side at a right angle on the outer surface of the inner plate, and an outer strip is laid between the ends of the partition plate so as to extend between the inner plate and the outer strip. It is a type in which a flow path wall (temperature control element) having a flow path of a heat medium partitioned by a partition plate is formed, and is fixed inside the reactor, and a similar type.

The following method is used to divide the flow path of the refrigerant such as the jacket into a plurality of parts.
That is, in the jacket type and the temperature control element type, it can be performed by inserting a partition plate that appropriately divides the flow path and providing a refrigerant inlet / outlet nozzle according to each flow path. Can be performed by using a coil having a flow path whose interior is divided similarly to the above, or by using a plurality of coils.

Among them, the temperature control element type reactor is not only excellent in heat transfer efficiency, but also the element can be installed up to the portion corresponding to the bottom end plate of the reactor to enable highly efficient cooling, and the effect of the present invention can be obtained. Can be fully exerted,
It is suitable. The number of divisions of the flow path of the refrigerant depends on the size of the reactor, but is not particularly limited as long as it is plural, and for example, it is common to use about 2 to 20 division flow paths.

In the method of the present invention, the above two (or more)
When cooling a reactor having a plurality of divided flow passages of a refrigerant using the above refrigerant, the amount of heat removal required to keep the reaction temperature within a predetermined range (hereinafter referred to as "required heat removal amount") depends on the refrigerant H. When the heat removal amount is less than (ie, the cooling capacity of the refrigerant H) or less, only the refrigerant H is supplied to all the divided flow paths, or when the flow paths of the refrigerant L and the refrigerant H are divided in advance, The reaction temperature is controlled by adjusting the flow rate of the refrigerant H without flowing the refrigerant L at the minimum flow rate or flowing the refrigerant L at all. When the required amount of heat removal exceeds the amount of heat that can be removed by the refrigerant H, the refrigerant L is supplied to part or all of the divided flow paths,
The reaction temperature is adjusted by the flow rate.

Although the reaction temperature can be adjusted by controlling the flow rate of the refrigerant, when the refrigerant H and the refrigerant L are used together, the maximum flow rate of the refrigerant H is effective in terms of the cooling capacity. Will be economically advantageous. In addition, when the cooling capacity required for carrying out the reaction can be estimated in advance, or when it has a large number of divided channels,
The refrigerant L may be supplied to some of the divided channels from the beginning of the reaction.

An example of a system equipped with a reactor having a divided flow channel, a refrigerator and a cold water tower which can be used in the method of the present invention is shown in FIG. 1, and is provided with only a conventional reactor without a divided flow channel and a cold water tower. An example of such a system is shown in FIG. An example of a specific embodiment in which the method of the present invention is applied to a batch reaction using the system of FIG. 1 will be described below.

When the amount of heat generated is small as in the early stage of the reaction and therefore the required amount of heat removal is not so large, or when the temperature of the refrigerant H obtained in the cold water tower 3 is low as in the winter, the flow paths in the divided flow passages 2A, 2B are reduced. When the refrigerant H is supplied to both and the flow rate is adjusted to cool the reactor, or when the flow paths of the refrigerant L and the refrigerant H are divided, as described above, the refrigerant L must be at the minimum flow rate or not flowed at all. The reaction temperature is controlled by adjusting the flow rate of the refrigerant H.

When the reaction proceeds and the amount of heat generated increases and the required amount of heat removal increases, or when the temperature of the refrigerant H is relatively high and the cooling capacity is low as in the summer, both of the divided flow paths 2A and 2B are used. Even if the flow rate of the refrigerant H supplied to the refrigerant is maximized (using all of the cooling capacity of the refrigerant H), the required heat removal amount may not be achieved. At this time, the reaction temperature is adjusted by the flow rate of the refrigerant L while the refrigerant L is supplied to one of the divided flow paths and the flow rate of the refrigerant H flowing through the other flow paths is maximized.

Further, when the amount of heat generated reaches the peak at the end of the reaction or when the temperature of the refrigerant H becomes high, such as during the daytime in summer, when the cooling capacity is insufficient even when cooled by the above method. Supplies the refrigerant L to all the divided flow paths to cool the reactor. It should be noted that the larger the number of divided channels, the more precise this adjustment can be made, but a pipe for supplying a refrigerant and a control device associated therewith are required for each divided channel, and the equipment and its cost are also large. Because of this, it is usually preferable to divide into about 2 to 20 channels as described above.

As described above, if the reaction temperature is adjusted by selecting the refrigerant to be supplied to the divided flow passages in accordance with the required heat removal amount and the cooling capacity of the refrigerant H, the cooling capacity of the refrigerant H can be made sufficient. By utilizing it, the energy required to obtain the refrigerant L can be minimized. That is, as compared with the case where cooling is performed only with the refrigerant H, almost all of the cooling capacity can be used without allowing for an excessive margin in the cooling capacity.

The method of the present invention is highly effective when applied to an exothermic reaction such as a batchwise polymerization reaction, particularly a polymerization reaction of a vinyl chloride monomer. Bulk polymerization methods, suspension polymerization methods, emulsion polymerization methods, fine suspension polymerization methods, and the like are generally used as polymerization methods for vinyl chloride-based monomers.
Among them, the method of the present invention is preferably used for a method for polymerizing a vinyl chloride monomer in an aqueous medium.

Polymerization of the vinyl chloride-based monomer in an aqueous medium is carried out in the suspension polymerization method in the presence of an oil-soluble polymerization initiator in an aqueous medium containing a dispersant, and in the emulsion polymerization method, an emulsifier and a water-soluble agent. The homogenization treatment is generally performed in the presence of a polymerization initiator, and in the fine suspension polymerization method, in the presence of an emulsifier and an oil-soluble polymerization initiator.

Although the method of the present invention can be effectively applied to any of the above-mentioned methods, particularly in the suspension polymerization method, a large reactor having a volume of 40 m ³ or more is widely used, and a vinyl chloride monomer Although the amount of charge is large and therefore the amount of heat generation is large, the increase in heat transfer area is smaller than the increase in volume, and the cooling capacity tends to be insufficient, so the effect is great.

The vinyl chloride monomer used when the method of the present invention is applied to a polymerization reaction of a vinyl chloride monomer means a vinyl chloride monomer alone and a vinyl chloride monomer-based copolymer. A mixture of polymerizable monomers. As the other monomer copolymerizable with the vinyl chloride monomer, those generally used in the related art can be used and are not particularly limited. Examples of the above-mentioned other monomers include vinyl acetate, vinyl propionate, vinyl stearates and other vinyl esters, methyl vinyl ether, ethyl vinyl ether, octyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether and other alkyl vinyl ethers, ethylene, Α-olefins such as propylene,
Mono-unsaturated acids such as acrylic acid and methacrylic acid, alkyl esters such as methyl esters and ethyl esters of these mono-unsaturated acids, divalent unsaturated acids such as maleic acid, fumaric acid and itaconic acid, and these Examples thereof include one or a mixture of two or more of alkyl esters such as methyl ester and ethyl ester of divalent unsaturated acid, vinylidene compound such as vinylidene chloride and unsaturated nitrile such as acrylonitrile. These other monomers are used in a proportion of usually 30% by weight or less, preferably 20% by weight or less, with respect to the vinyl chloride monomer, but there is no particular limitation.

The dispersant that can be used may be one conventionally used in the suspension polymerization method of vinyl chloride type monomers and is not particularly limited. Examples of the dispersant include partially saponified polyvinyl acetate (so-called polyvinyl alcohol), cellulose derivatives such as hydroxypropylmethyl cellulose, and water-soluble polymers such as gelatin. In addition, anionic surfactants such as sodium lauryl sulfate and nonionic surfactants such as sorbitan fatty acid esters and glycerin fatty acid esters may be used as a dispersion aid. These dispersants or dispersion aids can be used alone or in combination of two or more. Further, the amount of these dispersants used is not particularly limited, its type, stirring strength, polymerization temperature, the type and composition of other monomers to be copolymerized with the vinyl chloride monomer,
Although it varies somewhat depending on the intended particle size of the vinyl chloride polymer, it is generally in the range of 0.001 to 2% by weight, preferably 0.03 to 1% by weight, based on the total amount of the vinyl chloride monomer. Used within.

Examples of emulsifiers used in the emulsion polymerization method and the fine suspension polymerization method include higher alcohol sulfate ester salts (alkali metal salts and ammonium salts), alkylbenzene sulfonates (alkali metal salts and ammonium salts), Examples include higher fatty acid salts (alkali metal salts, ammonium salts), other anionic surfactants, nonionic surfactants, and / or cationic surfactants.
These surfactants may be used alone or in combination of two or more. The amount of the emulsifier used is usually 0.1 to 3% by weight (preferably 0.3 to 1% by weight) based on the vinyl chloride-based monomer, but is not particularly limited.

Further, these emulsifiers can be additionally used for adjusting the foamability during processing, and in this case, they may be added after the completion of the polymerization reaction. The polymerization initiator used in the case where the method of the present invention is applied to the polymerization reaction of a vinyl chloride-based monomer may be a conventionally used one in each polymerization method of a vinyl chloride-based monomer, and particularly, Not limited.

Examples of the polymerization initiator used in the suspension polymerization method include t-butylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-hexylperoxyneodecanoate, Perester compounds such as α-cumyl peroxy neodecanoate, diacyl or dialkyl peroxide compounds such as dilauroyl peroxide, percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, azobis (2,4 -Dimethylvaleronitrile), azo compounds such as azobisisobutyronitrile, and the like. These polymerization initiators can be used alone or in combination of two or more. Although the amount of the polymerization initiator used varies depending on the type of the initiator, the polymerization temperature, the desired reaction time, etc., it is generally in the range of 0.01 to 1% by weight based on the total amount of the vinyl chloride monomer.

The polymerization initiator used in the emulsion polymerization method is a water-soluble peroxide such as persulfate (sodium salt, potassium salt, ammonium salt), hydrogen peroxide, or a water-soluble peroxide thereof. Examples of the water-soluble redox-based initiators include a combination of a water-soluble reducing agent (eg, sodium sulfite, sodium pyrosulfite, sodium bisulfite, ascorbic acid, sodium formaldehyde sulfoxylate, etc.).

The polymerization initiator used in the fine suspension polymerization method is azobisisobutyronitrile or azobis (2,4-
Dimethyl valeronitrile), lauroyl peroxide,
Examples thereof include a monomer-soluble (oil-soluble) initiator such as t-butylperoxypivalate, or a redox-based initiator composed of a combination of these oil-soluble initiators and the above water-soluble reducing agent.

Further, in the polymerization reaction, if necessary, a polymerization degree adjusting agent (chain transfer agent, cross-linking agent), an antioxidant, a pH adjusting agent, a redox type initiator used for the polymerization of vinyl chloride type monomers. Various polymerization aids such as the activator can be appropriately added, and the amount of each component charged and the like can be the general conditions conventionally used for the polymerization of vinyl chloride-based monomers.

As the polymerization degree regulator used for the polymerization of vinyl chloride type monomers, trichlorethylene, carbon tetrachloride, chain transfer agents such as 2-mercaptoethanol and octyl mercaptan, diallyl phthalate and triallyl isocyanurate. Examples thereof include cross-linking agents such as ethylene glycol diacrylate and trimethylolpropane trimethacrylate.

When the method of the present invention is applied to a polymerization reaction of a vinyl chloride monomer, an aqueous medium to the reactor (polymerization tank), a vinyl chloride monomer, a polymerization initiator, and a dispersant for a suspension polymerization method. The emulsifier of the emulsion polymerization method and the fine suspension polymerization method, and the charging ratio and charging method of other various polymerization aids are not particularly limited, and all of these may be charged in a reactor before the start of the polymerization reaction, Alternatively, before starting the polymerization reaction,
The balance may be divided after the start of the polymerization reaction or continuously charged.

The polymerization temperature adopted when the method of the present invention is applied to the polymerization reaction of vinyl chloride-based monomers is determined by the type of polymerization initiator used, the polymerization method, the presence or absence of a polymerization degree modifier, and the target polymerization. Generally, although it depends on the degree,
The range of 0 to 90 ° C, especially 40 to 70 ° C is often used. In the reaction, the polymerization may be carried out at a constant temperature, or the reaction temperature may be changed during the polymerization.
Furthermore, the reactor to which the cooling method of the present invention is applied may be provided with an additional cooling device such as a reflux condenser.

[0036]

EXAMPLES Next, specific embodiments of the method of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. <Example 1> Both the cold water tower 3 and the refrigerator 6 as shown in FIG. 1 are provided, and the refrigerant H and the refrigerant L obtained from the respective equipment are divided into two in the jacket of the reactor 1. 18 t of vinyl chloride monomer, 20 t of deionized water, in a reactor equipped with a stirrer and a jacket having an internal volume of 60 m ³ having a cooling system capable of supplying to the channels 2A, 2B of
Partially saponified polyvinyl acetate as a dispersant and tert-butyl peroxypivalate as an initiator were charged, and the polymerization was carried out at a reaction temperature of 60 ° C. with a target reaction time (set by the amount of the initiator) of 4 hours. did.

The temperature of the refrigerant H was 26.7 ° C., the temperature of the refrigerant L was 5.0 ° C., and the heat generation during the reaction was as shown in FIG. Until the middle stage of the reaction, the reaction could be controlled only by the refrigerant H, but since the amount of heat generation increased from the time 2 hours after the start of the reaction, the refrigerant L cooled by the refrigerator 6 in the lower divided flow passage 2B. Was started and continued until the reaction was completed. After the internal temperature of the reactor reaches a predetermined polymerization reaction temperature, the internal pressure of the reactor decreases from the saturated pressure of vinyl chloride monomer at the reaction temperature by 2 kg / cm ² to start the recovery of unreacted monomer. The time was measured as the reaction time. The reaction time of this reaction was 3 hours and 55 minutes.

Example 2 The same as Example 1 except that the target reaction time was set to 3 hours and 30 minutes, the polymerization initiator was used, and the refrigerant L was supplied to the lower divided flow passage 2B from the beginning of the reaction. The polymerization reaction was carried out. The reaction time was 3 hours and 35 minutes.

Example 3 A polymerization initiator was used with a target reaction time of 4 hours and 15 minutes, and the refrigerant L was supplied to the lower divided flow passage 2B from the time when 3 hours and 15 minutes had elapsed after the start of the reaction. The polymerization reaction was carried out in the same manner as in Example 1. The reaction time was 4 hours and 10 minutes.

<Comparative Example 1> In the same manner as in Example 1 except that the cooling was performed only with the refrigerant H in FIG. 1 (that is, the same state as in FIG. 2), the polymerization was started with the target reaction time of 4 hours. . The reaction controllability was good until the middle stage of the reaction, but the cooling capacity became insufficient at the end stage of the reaction, and the temperature of the reaction system rose even when the refrigerant H was circulated at the maximum flow rate, which was 61 ° C. higher by 1 ° C. than the predetermined reaction temperature. Since it exceeded the limit, the vinyl chloride monomer was collected outside the reactor to stop the reaction.

Comparative Example 2 A polymerization reaction was initiated in the same manner as in Comparative Example 1 except that the target reaction time was 4 hours and 30 minutes and the polymerization initiator was used. Although it was possible to control the reaction only with the refrigerant H during the entire reaction period, the peak flow rate of the refrigerant H reached the maximum flow rate at the end of the reaction, and the cooling capacity was on the verge of becoming insufficient. Reaction time is 4 hours 35
It was a minute. The above results are summarized in Table-1.

<Embodiment 4> In the reactor 1, the jacket has a refrigerant flow passage divided into ten pieces, and a cooling system capable of independently supplying the refrigerant H and the refrigerant L to each of them. A reactor equipped with a stirrer and jacket with a volume of 60 m ³ was used. The target reaction time was set to 4 hours and 15 minutes, and the amount of the initiator was adjusted.
Suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 except that the refrigerant L was supplied to the bottle and the refrigerant H was supplied to the remaining nine divided channels until the end of the reaction. The temperature of the refrigerant H is 2
The temperature of the refrigerant L was 5.4 ° C., the temperature of the refrigerant L was 5.0 ° C., and the heat generation state during the reaction was the same as in FIG. The reaction was completed smoothly, and the reaction time was 4 hours and 20 minutes.

Example 5 A polymerization initiator was used with a target reaction time of 3 hours and 45 minutes, and a refrigerant L was provided in four divided channels from the beginning of the reaction, and a refrigerant H was provided in the remaining six divided channels. A polymerization reaction was carried out in the same manner as in Example 4 except that the supply was performed. The reaction time was 3 hours and 45 minutes.

<Example 6> A polymerization initiator was used with a target reaction time of 3 hours and 30 minutes, and a refrigerant L was provided in five divided channels from the beginning of the reaction, and a refrigerant H was provided in the remaining five divided channels. A polymerization reaction was carried out in the same manner as in Example 4 except that the supply was performed. The reaction time was 3 hours and 30 minutes.

Comparative Example 3 Polymerization was carried out at a target reaction time of 4 hours and 30 minutes in the same manner as in Example 4 except that the refrigerant H was supplied to all the divided channels. At the end of the reaction, the flow rate of the refrigerant H was 96% of the maximum flow rate, but the reaction was smooth and could be carried out stably. The reaction time was 4 hours and 35 minutes.

<Embodiment 7> In a reaction temperature control system having a cold water tower 3 and a refrigerator 6 similar to those shown in FIG. 1, a reactor of a temperature control element type having an internal volume of 60 m ³ as shown in FIG. 4 is used. A reactor was used. This temperature control element type reactor has a refrigerant flow passage divided into twelve lines, and eight of them are supplied with the coolant H and four are supplied with the coolant L.

Using this reactor, vinyl chloride monomer and the like were charged in the same manner as in Example 1, and the polymerization reaction was carried out at a reaction temperature of 60 ° C. with a target reaction time of 3 hours and 30 minutes.
The reaction time was 3 hours and 25 minutes. By using the temperature control element type reactor, in the case of the same reaction time of 3 hours and 30 minutes, the heat transfer efficiency is better than that of a normal external jacket type reactor, so that the proportion of the flow path using the refrigerant L (refrigerant L Even when the supply area) was 33%, the same level of productivity as in the case where the supply area of the external jacket type refrigerant L was 50% (Example 6) could be achieved. The above results are summarized in Table-2.

[0048]

By using the method of the present invention, it is possible to efficiently use the energy of the refrigerant and improve the reaction controllability.
In addition, it has become possible to achieve high productivity. Further, compared to the method of using the refrigerant L over the entire reaction period, the use thereof is limited only when necessary, so that the refrigeration equipment can be small and the energy cost can be reduced.

[0049]

[Table 1] *: L ... Refrigerant L H ... Refrigerant H switching ... Supplying the refrigerant H to start the reaction and switching to the refrigerant L during the reaction. **: Production capacity per hour when the production capacity under the conditions of Comparative Example 2 is 100. Calculated as the value of the ratio of the reciprocal of the reaction time.

[0050]

[Table 2] *: The number of channels that have supplied the refrigerant H or the refrigerant L in the divided channels. **: Production capacity per hour when the production capacity under the conditions of Comparative Example 3 is 100. Calculated as the value of the ratio of the reciprocal of the reaction time. ***: Example 7 uses a temperature control element type reactor.

[Brief description of drawings]

FIG. 1 shows a system for controlling the reaction temperature using two kinds of refrigerants, which is equipped with a reactor having a refrigerant passage divided into two, a refrigerator and a cold water tower that can be used for carrying out the method of the present invention. The flowchart which shows an example.

FIG. 2 is a flow chart showing an example of a conventional system that includes only a reactor having a cooling jacket without a divided flow channel and a cold water tower to control the reaction temperature.

FIG. 3 is a diagram showing an example of a state of generation of reaction heat in a batch polymerization reaction of vinyl chloride.

FIG. 4 is a cross-sectional view showing an example of a temperature control element type reactor having a refrigerant passage divided into two, which can be used for carrying out the method of the present invention.

[Explanation of symbols]

 1 Reactor 2 Reactor jacket 2A, 2B Refrigerant flow path divided into reactor jackets 3 Cold water tower 4 Refrigerant H circulation pump 5 Refrigerant L circulation pump 6 Refrigerator 7 Refrigerant L storage tank 8 Temperature control element 9 Partition 10A, 10B division Refrigerant flow path inlet 11A, 11B Divided refrigerant flow path outlet 12 Pressure equalizing pipe 13 Gap chamber

Claims (10)

[Claims] 1. When controlling a reaction temperature by passing a cooling heat medium (hereinafter referred to as “refrigerant”) through a heat medium flow path for heating and / or cooling a reactor, a plurality of the flow paths are provided. In addition to dividing into two, using two or more refrigerants having different temperatures as refrigerants, the reaction temperature is characterized by cooling the reactor by supplying those refrigerants to the flow path of the divided refrigerant. Adjustment method. 2. As the refrigerant, two refrigerants having different temperatures (hereinafter, the refrigerant having a higher temperature is referred to as "refrigerant H" and the refrigerant having a lower temperature are referred to as "refrigerant L") are used, and a reaction temperature is used. The amount of heat removal required to maintain the heat within the predetermined range
2. When the cooling capacity is less than or equal to the cooling capacity, only the refrigerant H is used, and when it exceeds the cooling capacity of the refrigerant H, the refrigerant L is supplied to a part or all of the flow path of the heat medium. Method. 3. The method for adjusting the reaction temperature according to claim 1, wherein at least one of the refrigerants is water. 4. The method for adjusting the reaction temperature according to claim 1, wherein at least one of the refrigerants is cooled by a refrigerator. 5. The method for adjusting the reaction temperature according to claim 1, wherein the cooling method is a jacket method. 6. The method for adjusting a reaction temperature according to claim 1, wherein the cooling system is a temperature control element type. 7. The method for adjusting the reaction temperature according to claim 1, wherein the number of divided channels is 2 to 20. 8. The reaction carried out in the reactor is a polymerization reaction of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith. The method for controlling the reaction temperature according to item 1. 9. The method for controlling the reaction temperature according to claim 8, wherein the polymerization reaction is carried out in an aqueous medium. 10. The method for controlling the reaction temperature according to claim 8, wherein the polymerization reaction is a batch suspension polymerization reaction.