JPWO2019235504A1 - Residual monomer remover - Google Patents

Abstract

A residual monomer removing device capable of efficiently removing residual monomers from a vinyl chloride resin-containing slurry while preventing the residual monomers from being discharged out of the process. A tubular tower main body 4, a plurality of perforated plates 34 provided in the vertical direction in the tower main body, a plurality of chambers 16 to 21 formed on the perforated plates as bottom surfaces, and a slurry introduction pipe. 22, 23, a flow-down pipe 36 for sequentially flowing down the slurry from the perforated plate in the upper chamber, a steam introduction pipe 10 provided at the bottom of the tower body, and a gas discharge port 11 at the top of the tower body. Effective for a hot water injection device having a condensing device 6 provided, a slurry discharge port 24 provided on a perforated plate at the bottom, and a hot water injection ring 38 directly under the perforated plate, and including a hot water injection ring. Connect from the pressure gauge 40 for monitoring the injection pressure, the device for adjusting the pressure (pressure control valve 32, or the hot water pump 8 with an inverter control function), and the hot water injection ring 38 of the hot water injection device. A sight glass cleaning nozzle 37 is provided or inserted into the ring.

Description

In the present invention, in the production of a vinyl chloride resin (hereinafter, abbreviated as PVC), a vinyl chloride monomer (hereinafter, abbreviated as VCM) contained in a mixture of PVC and an aqueous medium (hereinafter, abbreviated as PVC slurry). ) And the like, the present invention relates to a residual monomer removing device and a removing method from a vinyl chloride resin-containing slurry capable of efficiently removing residual monomers.

PVC is used in a wide range of fields because it is a resin having excellent chemical and physical properties. Generally, PVC is produced by a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method, or the like, but it is particularly suspended because it has the advantages of easily removing heat of reaction and obtaining a product with few impurities. A polymerization method and an emulsion polymerization method are widely used.

The suspension polymerization method and the emulsion polymerization method are usually carried out by charging VCM together with an aqueous medium, a dispersant or an emulsifier, a polymerization initiator and the like in a polymerizer with a stirrer, and polymerizing under stirring while maintaining a predetermined temperature. It is said. The polymerization reaction is usually not carried out until the VCM is converted to 100% to PVC, and is stopped at a stage where the production efficiency is high, that is, a stage where the polymerization conversion rate is 80 to 95%. After the polymerization reaction is completed, the residual monomer in the polymerizer is separated from the PVC slurry (mainly a mixed dispersion of PVC particles and an aqueous medium) and recovered, but the PVC slurry contains a few percent of the residual monomer. Is normal.

As described above, the PVC slurry containing the residual monomer is mechanically separated from the aqueous medium and dried by hot air drying or various other methods to obtain PVC powder. At this time, the separated aqueous medium, the exhaust by hot air drying, and the obtained PVC powder contain VCM to the extent that it is problematic for environmental hygiene reasons or is clearly recognized as harmful.

Various methods have been proposed to completely remove such manufacturing emissions and VCMs in PVC powders, or to reduce their content to a degree that is harmless to environmental hygiene. For example, Patent Document 1 and Patent Document 2 are examples of methods for removing and recovering residual monomers from a PVC slurry by using a processing tower equipped with a plurality of perforated plate shelves and steam injection ports at the bottom. ..

In these methods, PVC slurries are made of these perforated plates by using perforated plate shelves whose bottom surface is composed of perforated plates and whose dam plates are installed so as to form staggered processing passages on the perforated plates. The PVC slurry is sequentially flowed down along the processing passage on the shelf, during which the PVC slurry is exposed to the water vapor injected from below through the pores of the perforated plate, and the residual monomer contained in the PVC slurry is evaporated and separated. Is what you do.

Generally, such a method of removing and recovering residual monomer is called a demonomerization method, and at present, this demonomerization method occupies the mainstream.
The residual monomer removing device by the demonomerization method has a hot water injection device provided directly below the perforated plate in each chamber and at least toward the lower surface of the perforated plate. While the PVC slurry is sequentially flowing down along the treatment passage on the perforated plate, the slurry moves from the hole of the perforated plate to the lower chamber due to the pressure fluctuation in the room due to the decrease in the temperature in the system or the fluctuation of the steam flow rate. It may descend and clog the holes, and the slurry may scatter and adhere to the wall surface. If it is left as it is, the pores of the perforated plate are closed and the water vapor is blown in unevenly, so that the operation becomes unstable and the removal of residual monomers in the PVC slurry becomes insufficient. In addition, PVC adhering to the wall surface is discolored by heat and causes foreign matter contamination, which adversely affects the quality. The hot water injection by the hot water injection device prevents these problems because the slurry adhering to the holes and the wall surface of the perforated plate can be washed away.

As described above, the hot water injection device of the residual monomer removing device is an important device, and for example, Patent Document 2 has been proposed for the hot water injection device and the method.

Further, in recent years, as in Patent Documents 3 to 5, a tubular tower body, a plurality of perforated plates provided in the vertical direction of the tower body, and a plurality of perforated plates formed on the perforated plates as bottom surfaces. Room, the slurry introduction port provided on the upper side of the uppermost porous plate among the plurality of porous plates, and the porous plate so as to sequentially flow the slurry from the porous plate in the upper chamber to the porous plate in the lower chamber. A flow bottom provided between the plates, a steam inlet provided at the bottom of the tower body, a condensing device provided outside the tower body via a gas transfer pipe in the tower top chamber of the tower body, and the above. Residual monomer having a slurry discharge port provided in the lowermost perforated plate among a plurality of perforated plates, and a hot water injection device provided directly below the perforated plate and at least toward the lower surface of the perforated plate. Removal devices have been proposed.

Among them, it is necessary to maintain the hot water injection pressure in each chamber in order to secure an appropriate hot water injection amount at the time of hot water injection cleaning, and this pressure is applied to the hot water injection nozzle provided at the inlet of each chamber. The opening is adjusted by a manual valve so that the indicated value of the pressure gauge connected to is the predetermined pressure. However, there are cases where a predetermined pressure cannot be secured due to fluctuations in the outlet pressure of the hot water pump.

In addition, in order to visually check the slurry level and bubbling state in each room when the operation of the residual monomer removal device becomes unstable or when the operation becomes unstable, a sight glass is placed on the side of each room. It is installed and you can observe the inside. However, the inside of the sight glass may be difficult to see due to the adhesion of scattered slurry. Therefore, the cleaning nozzle for cleaning the sight glass is connected from the hot water injection ring, but since it is connected from the lower side of the hot water injection ring, the hot water in the hot water injection ring is connected even after the hot water injection cleaning is completed. Since hot water drips from the sight glass cleaning nozzle and hits the sight glass until it comes out, the inside cannot be observed until the hot water in the hot water injection ring comes out.

Furthermore, when the temperature difference between the room temperature and the hot water temperature is large, the room temperature fluctuates and the pressure also fluctuates during cleaning, so that the perforated plate above or below the chamber may leak. is there.

JP-A-54-8693 JP-A-56-22305 JP-A-6-10723 Japanese Patent Application Laid-Open No. 10-338708 JP-A-9-48815

There is a demand for a residual monomer removing device capable of efficiently removing the residual monomer from the vinyl chloride resin-containing slurry while preventing the residual monomer from being discharged out of the process.

The configuration of the residual monomer removing device of the present invention is as follows. A tubular tower main body 4, a plurality of perforated plates 34 provided in the vertical direction in the tower main body, a plurality of chambers 16 to 21 formed on the perforated plates as bottom surfaces, and a slurry introduction pipe. 22, 23, a flow-down pipe 36 for sequentially flowing down the slurry from the perforated plate in the upper chamber, a steam introduction pipe 10 provided at the bottom of the tower body, and a gas discharge port 11 at the top of the tower body. Effective for a hot water injection device having a condensing device 6 provided, a slurry discharge port 24 provided on a perforated plate at the bottom, and a hot water injection ring 38 directly under the perforated plate, and including a hot water injection ring. Connect from the pressure gauge 40 for monitoring the injection pressure, the device for adjusting the pressure (pressure control valve 32, or the hot water pump 8 with an inverter control function), and the hot water injection ring 38 of the hot water injection device. A sight glass cleaning nozzle 37 is provided or inserted into the ring.

In order to solve the above problems, the present invention includes the following items.
[1] A tubular tower body, a plurality of perforated plates provided in the vertical direction of the tower body, and
A plurality of chambers formed on the perforated plate with the bottom surface as the bottom surface, and
A slurry introduction port provided on the upper side of the uppermost perforated plate among the plurality of perforated plates, and
A flow bottom provided between the perforated plates so that the slurry flows down sequentially from the perforated plate in the upper chamber to the perforated plate in the lower chamber, and
The water vapor inlet provided at the bottom of the tower body and
A condensing device provided outside the tower body via a gas transfer pipe in the tower top chamber of the tower body,
A slurry discharge port provided on the lowermost perforated plate among the plurality of perforated plates, and
Immediately below the perforated plate, there is a hot water injection device provided at least toward the lower surface of the perforated plate.
In a residual monomer removing device that removes residual monomers from a polyvinyl chloride-containing slurry containing residual monomers after the completion of polymerization.
The hot water injection device is equipped with a pressure gauge for monitoring the injection pressure and a device for controlling the injection pressure in order to inject an appropriate injection amount of hot water. ..

[2] The residual monomer removing device according to [1], wherein the device for controlling the injection pressure is a device for adjusting the hot water injection pressure by controlling the pressure control valve or the hot water supply pump output with an inverter.

[3] The residual monomer according to [1] or [2], wherein the hot water injection ring provided in the hot water injection device has a cleaning nozzle for cleaning one or more sight glasses installed in each chamber. Removal device.

[4] The residual monomer removing device according to [3], wherein a cleaning nozzle for cleaning the sight glass included in the hot water injection ring is connected from above the hot water injection ring.

[5] The residual monomer removing device according to [3], wherein a cleaning nozzle for cleaning the sight glass included in the hot water injection ring is connected so as to be inserted into the inside of the hot water injection ring.

According to the invention described in [1] or [2], it is an apparatus for removing residual monomers from a polyvinyl chloride-containing slurry containing residual monomers after completion of polymerization, and sets the injection pressure in the hot water injection apparatus to a predetermined pressure. Therefore, the hot water injection pressure can be adjusted by installing a pressure control valve or controlling the output of the hot water pump by inverter control. In addition, using an inverter leads to energy saving.

According to the invention described in [3], the internal condition of each room is observed by installing a washing nozzle for washing the sight glass of each room in the hot water injection ring provided in the hot water injection device. can do.

According to the invention described in [4] or [5], the cleaning nozzle for cleaning the sight glass included in the hot water injection ring is a nozzle inserted from below or connected from above the hot water injection ring. The internal condition of each room can be observed without waiting for the hot water accumulated in the hot water injection ring to escape from the washing nozzle. Further, by storing the hot water in the hot water injection ring, the difference between the indoor temperature and the hot water temperature in the hot water injection ring becomes small, so that the pressure fluctuation in the room is alleviated during the hot water injection cleaning, and the liquid leaks from the perforated plate. It leads to prevention.

It is the schematic of the residual monomer removal apparatus. It is a detailed view of the room of the residual monomer removal treatment tower. It is an enlarged vertical sectional view of a hot water injection ring. It is the whole view of the hot water injection ring seen from the top surface. It is a vertical sectional view of the sight glass washing pipe connected from the upper part of a hot water injection ring. Is a vertical sectional view of a sight glass cleaning pipe inserted and connected from the lower part of the hot water injection ring.

The method for removing the residual monomer from the PVC slurry in the residual monomer removing apparatus of the present invention will be described with reference to FIGS. 1 to 6, but the present invention is not limited thereto.

1. 1. Configuration of Residual Monomer Removal Device This device consists of a tubular tower body 4 and a plurality of perforated plates 34 each having a large number of pores provided in the vertical direction of the tower body 4, and the perforated plates are used as bottom surfaces. The plurality of chambers 16 to 21 formed above, and the slurry introduction port 22 as a slurry introduction portion provided above the perforated plate under the tower top chamber 21 or the perforated plate under the chamber 19 among the plurality of perforated plates. , 23, a flow-down pipe 36 provided between the perforated plates so as to sequentially flow the slurry from the perforated plate in the upper chamber to the perforated plate in the lower chamber, and a steam introduction pipe 10 provided at the bottom of the tower body. A condenser 6 provided at the top of the tower body via a gas transfer port 11, a residual monomer gas transfer pipe 12 provided at the outlet of the condenser, and a perforated plate at the bottom of the plurality of perforated plates. It has a PVC slurry discharge port 24 provided in the above, and a hot water injection ring 38 as a hot water injection means installed directly under each perforated plate so as to face directly under the perforated plate.

1-1. Tower body The inner diameter of the tower body 4 is 200 to 10000 mm, and the height of the tower is 2 to 20 times, more preferably 5 to 15 times the inner diameter. Further, if necessary, the inner diameter of each chamber in the tower may be different. In the residual monomer removal treatment tower 4, the space partitioned between the bottom of the column and the perforated plate, the perforated plate and the perforated plate located immediately above the perforated plate, or the perforated plate and the top of the column is referred to as a chamber. The number of chambers required to treat the residual monomer is determined by the residence time required when removing the residual monomer from the PVC slurry.

1-2. Perforated plate Each of the perforated plates 34 having a large number of pores is provided with several weir plates 35 vertically on the surface thereof, and forms a chamber (space) between the perforated plate 34 and the lower surface of the upper perforated plate. The pores of the perforated plate are opened so that when the PVC slurry flows on the perforated plate, the demonomerization treatment is performed by the water vapor injected from the pores. The size of the pores is such that the PVC slurry does not flow down through the pores, the pores are not blocked, and the water vapor injected from below constantly and uniformly passes through the water vapor pressure and the amount of water vapor introduced. Is set in consideration of.

The pores formed in the perforated plate have a diameter of 5 mm or less, preferably 0.5 to 2 mm, and more preferably 0.7 to 1.5 mm. The aperture ratio (total pore area / perforated plate area) of the perforated plate is 0.001 to 10%, preferably 0.04 to 4%, and more preferably 0.2 to 2%.
When the aperture ratio is in this range, the PVC particles existing in the PVC slurry flowing on the perforated plate shelf are sufficiently agitated, so that the PVC particles settle and the residual monomer is removed from the PVC particles. It is possible to prevent a decrease in efficiency and a decrease in the fluidity of the PVC slurry. Further, when the aperture ratio is within this range, the phenomenon that the PCV slurry flows down from the pores (hereinafter referred to as liquid leakage) does not occur, and liquid leakage can be prevented, so that a large amount is used to prevent liquid leakage. There is no waste of water vapor.
The weir plate 35 is for securing a processing passage through which the PVC slurry can flow on the perforated plate. Weir plates are alternately installed on the upper surface of the perforated plate 34.
The treatment passage formed by the dam plate allows the PVC slurry to flow on the perforated shelf plate for a certain period of time, during which time it undergoes demonomerization treatment with water vapor supplied from below.

1-3. Hot water injection device A hot water injection device is installed in the tower body 4 of the residual monomer removing device of the present invention. A hot water injection ring 38 as a hot water injection device forms a pipe into a predetermined shape (FIG. 4) and is provided directly under the perforated plate 34. Hot water is injected from an injection nozzle at predetermined time intervals to make the pipe porous. Clean the underside of the board and the inner wall of the tower. The number of injection nozzles and the position of the nozzle holes 39 are not particularly limited, but it is preferable that the angles a and b (FIG. 3) of the injection nozzles intersecting the vertical line are set in the range of 10 to 60 degrees.
In order to give the hot water a sufficient ejection speed and thus cleaning power, the difference pressure between the pressure inside the hot water injection ring at the time of ejecting the hot water and the pressure in the room where the hot water is injected shall be 0.02 MPaG or more, preferably 0.05 MPaG or more. Is appropriate. If the differential pressure is within this range, the hot water injection pressure control that can obtain a sufficient cleaning effect without increasing the hot water consumption is such that the hot water pump 8 is converted into an inverter to automatically control the hot water circulation line pressure. This is possible by automatically controlling the pressure control valve 32.

1-4. Cleaning pipe for sight glass It is appropriate that the cleaning pipe 37 for sight glass 33 is connected from the upper part of the hot water injection ring 38 as shown in FIG. 5, or is inserted and connected from the lower part of the hot water injection ring 38 as shown in FIG. .. If the connection is made from the lower side of the hot water injection ring, the hot water remaining in the hot water cleaning ring drips from the sight glass cleaning nozzle and hits the sight glass even after the cleaning is completed, so that the inside cannot be observed from the sight glass. Further, when the temperature difference between the temperature in the room and the temperature of the hot water is large, the temperature in the room fluctuates and the pressure also fluctuates during cleaning, so that the perforated plate above or the perforated plate below may leak. If hot water is stored in the hot water injection ring by connecting the sight glass cleaning pipe from the upper part of the hot water injection ring or by inserting and connecting from the lower part of the hot water injection ring, the temperature difference between the room and the hot water in the ring can be reduced. As it becomes smaller, it helps prevent liquid leakage from the perforated plate.

1-5. Hot water injection ring The plane shape of the pipe of the hot water injection ring 38 as a hot water injection device is usually like the Greek letter Ω type or Φ type or spiral type, star shape or sheep intestine type (turning ninety-nine). A multiple ring type (FIG. 4) having the same center alternately may be used. The hot water injection ring 38 may be installed parallel to the perforated plate 34 and may be housed inside the tower. However, if the hot water injection ring 38 is too close to the inner wall of the tower body, the washed-out PVC particles or the like may block the gap. It is advisable to install the outer diameter at a distance of 20 mm or more from the inner wall to the inside. The outer diameter of the hot water injection ring 38 is preferably 150 to 8000 mm.

2. Method of Removing Residual Monomers from PVC Slurry The PVC slurry obtained by suspension polymerization or emulsion polymerization temporarily stored in the PVC slurry tank 1 is guided to the heat exchanger 3 by the PVC slurry feed pump 2 and is guided to the heat exchanger 3 by the PVC slurry feed pump 2. After being heated to a predetermined temperature inside, it is introduced into the residual monomer removal treatment tower 4 from the PVC slurry introduction pipe 22 or 23.

The flow rate of the PVC slurry introduced into the column is preferably adjusted to 0.1 to 300 ^{m 3} / h (more preferably ^{1 to 100 m 3 / h) per 1 m 2 of the area of the perforated plate 34.} It is desirable that the PVC slurry introduced into the column is preheated to 50 to 100 ° C. by the heat exchanger 3. This preheating improves the efficiency of removing residual monomers.
The difficulty of removing the monomer from the PVC slurry is due to the structure of the PVC particles in the PVC slurry. When the pore volume ratio in the PVC particles is large, the contact between the PVC particles and water vapor is good and demonomerization is easy, and when the pore volume ratio is small, demonomerization is difficult. The residence time of the PVC slurry in the column includes the difficulty of demonomerizing the PVC slurry as described above, the concentration of unreacted monomers contained in the PVC slurry introduced into the column, and the treatment at the PVC slurry discharge port 24. It is determined by the setting value of the residual monomer concentration later.

If the residence time of the PVC slurry in the column is long, the residual monomer can be highly removed from the PVC particles existing in the PVC slurry, but if it is too long, the PVC particles cause coloring due to thermal deterioration. Therefore, contact of the PVC slurry with more water vapor than necessary is not preferable. Therefore, it is necessary to adjust the residence time according to the difficulty of demonomerization of the PVC slurry.

The PVC slurry introduced into the tower body from the slurry introduction pipe 22 or 23 as the slurry introduction portion passes through the processing passage defined by the weir plate 35 on the perforated plate 34, passes through the downflow pipe 36, and the chamber below it. Is introduced onto the perforated plate 34 of. The slurry introduced onto the perforated plate 34 subsequently passes over the processing passage on the perforated plate 34, and further flows through the flow-down pipe 36 onto the perforated plate 34 below it. After passing through the processing passage to the lowermost perforated plate 34 in this way, the PVC slurry is discharged to the outside of the tower from the PVC slurry discharge port 24 provided in the lowermost perforated plate 34.

The perforated plate 34 in the present invention is not particularly limited in the number of weir plates 35 and the width of the treatment passage, but the height of the flowing PVC increases and the perforated plate 34 exceeds the weir plate, so that the staying time is different. It is necessary to properly set the number of weir plates and the width of the treatment passage in order to prevent the quality of the product from being deteriorated due to the mixture of slurries.
In the apparatus of the present invention, the water vapor introduction pipe 10 is connected to the bottom chamber 15, and the water vapor injected from the water vapor introduction port 10 flows through the pores of the perforated plate into the PVC slurry flowing on the perforated shelf plate. Be blown in. The amount of water vapor introduced at this time is 1 to 100 kg / h, preferably 5 to 50 kg / h per ^{1 m 3 of the PVC slurry.} When the amount of water vapor introduced is within this range, residual monomers in the PCV slurry can be efficiently removed without sedimentation of PVC particles in the PVC slurry. Further, when the amount of water vapor introduced is within this range, the generation of splashes of the PVC slurry is suppressed and flooding does not occur. Further, when the amount of water vapor introduced is within this range, the balance between the amount of water vapor introduced and the effect of removing residual monomers in the PVC slurry is good.

Also, adjusting the temperature of the PVC slurry leads to obtaining high quality PVC. Generally, the steam temperature, the amount of steam introduced, and the pressure inside the column are adjusted so that the temperature of the slurry flowing on the perforated plate is 50 to 150 ° C, preferably 70 to 120 ° C, and more preferably 80 to 110 ° C. Is desirable. When the temperature of the PVC slurry is within this range, it is possible to maintain high quality by preventing coloring of PVC particles due to thermal deterioration while maintaining the efficiency of removing residual monomers.

The mixed gas of the monomer gas and the water vapor removed in the residual monomer removing device flows into the condenser 6 through the gas transfer pipe connected to the tower top chamber 21, where most of the water vapor is condensed and the condensed water. Is dropped back into the residual monomer removal treatment tower. At that time, the mixed gas of the monomer gas rising from the top chamber of the tower, the mixed gas of water vapor, and the condensed water flowing down come into countercurrent contact, and the condensed water is heated. Further, energy loss can be prevented by guiding the cooling water 13 introduced into the condenser 6 from the condenser 6 to the hot water tank 7 via the cooling water outlet hot water supply pipe 14 and using it as hot water for washing hot water. The PVC slurry from which the residual monomer has been removed by the residual monomer removal treatment tower 4 is discharged from the PVC slurry discharge port 24 and sent to the pump 9. After that, the PVC slurry is stored in the PVC slurry tank via the heat exchanger 3.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

The hot water injection step using the hot water injection device in the residual monomer removal treatment tower is carried out during the PVC slurry feed and during the washing water feed after the feed is completed.
Further, in the hot water jet cleaning, the hot water jet cleaning is performed in order from the lower chamber 16 to the upper chamber. When the cleaning of the tower top chamber is completed, the cleaning of the chamber 16 is started again. Regarding the chamber 15, when the hot water injection cleaning valve 31 in the bottom chamber is opened during the PVC slurry feed to perform hot water injection cleaning, the temperature inside the chamber 15 is lowered and the pressure is also lowered, so that the liquid from the upper perforated plate is lowered. Do not perform hot water jet cleaning during the PVC slurry feed as it will leak.

[Example 1]
(Hot water ejection pressure control by inverter control of hot water pump output)
1. 1. It is assumed that the hot water pump 8 is started and the inverter output is the minimum value of 100 m ³ / h, which is the circulation amount that can keep the temperature distribution in the hot water tank 7 uniform.
2. One minute before hot water injection, set the hot water circulation line pressure to the hot water circulation line pressure so that the differential pressure between the hot water injection pressure and the room pressure changes from the appropriate value of 0.05 MPaG to 0.08 MPaG, and set the inverter of the hot water pump. Automatically control the output.
3. 3. The inverter output control of the hot water pump 8 is switched to the manual mode, and the output value is fixed at the output value at that time. Then, the hot water injection cleaning valve 30 in the chamber 16 is opened for 8 seconds.
4. ^{After closing the hot water injection cleaning valve 30, the inverter output of the hot water pump 8 is returned to the minimum value of 100 m 3} / h, which is the circulation amount at which the temperature distribution in the hot water tank 7 can be kept uniform, and this state is maintained for 2 to 10 minutes.
5. By the same operation as 2 to 4 above, the hot water injection cleaning valve 29 one step higher is opened and closed to clean the lower side of the chamber 17 and the perforated plate under the chamber 18.
6. The same operations as 2 to 5 above are repeated, and hot water spray cleaning is performed in order from the lower chamber to the upper chamber.

[Example 2]
(Hot water ejection pressure control by controlling the circulation pressure control valve)
1. 1. The hot water pump 8 is started to fully open the circulation pressure control valve 32 opening output.
2. One minute before hot water injection, the hot water circulation line pressure is set to the hot water circulation line pressure so that the differential pressure between the hot water injection pressure and the room pressure becomes an appropriate pressure, and the circulation pressure control valve 32 opening output is automatically controlled. To do.
3. 3. The circulation pressure control valve 32 is switched to the manual mode to fix the opening degree output value. Then, the hot water injection cleaning valve 30 in the chamber 16 is opened for 8 seconds.
4. After closing the hot water injection cleaning valve 30, the circulation pressure control valve 32 opening output is fully opened. Keep this state for 2 to 10 minutes.
5. By the same operation as 2 to 4 above, the hot water injection cleaning valve 29 one step higher is opened and closed to clean the lower side of the chamber 17 and the perforated plate under the chamber 18.
6. The same operations as 2 to 5 above are repeated, and hot water spray cleaning is performed in order from the lower chamber to the upper chamber.

[Example 3]
(Cleaning with a sight glass cleaning pipe connected from the top of the hot water injection ring)
The cleaning of the sight glass 33 in each room is performed at the same time as the hot water jet cleaning of each room is performed. Since the sight glass cleaning pipe is connected from the upper part of the hot water injection ring, hot water will not drip from the sight glass cleaning nozzle forever after the hot water injection cleaning is completed. Further, since the hot water is stored in the hot water injection ring, the temperature difference between the room and the hot water in the ring at the time of cleaning becomes as small as 1 ° C. or less, and liquid leakage of the perforated plate does not occur.

[Example 4]
(Cleaning with a sight glass cleaning pipe inserted from the bottom of the hot water injection ring and connected)
As in the third embodiment, when the hot water jet cleaning is completed, the hot water does not drip from the sight glass cleaning nozzle indefinitely. In addition, liquid leakage from the perforated plate does not occur.

[Comparative Example 1]
In the conventional method, in order to secure an appropriate hot water injection pressure during hot water injection cleaning, a pressure gauge and a manual valve are provided at the hot water injection ring inlet provided at the inlet of each chamber, and the indicated value of the pressure in each chamber is set. The opening degree was adjusted by a manual valve so that the predetermined pressure was changed from 0.05 MPaG to 0.08 MPaG. However, there are cases where a predetermined pressure cannot be secured due to fluctuations in the outlet pressure of the hot water pump. Furthermore, the hot water circulation line requires an automatic valve for shutting off the circulation return line in order to secure the hot water circulation pressure, and when cleaning each room, the hot water injection cleaning automatic valve in each room is opened to shut off the hot water circulation. Although the valve was closed, the timing of opening and closing the valve caused a hammer ring in the pipe, which could cause vibration of the pipe and valve, and eventually hot water leakage from the flange of the pipe or valve.

[Comparative Example 2]
For conventional sight glass cleaning, since the sight glass cleaning pipe is connected to the underside of the hot water injection ring, even after the hot water injection cleaning is completed, the sight glass cleaning nozzle is used until the hot water in the hot water injection ring is completely drained. Hot water drips from the water and hits the sight glass, making it impossible to observe the inside. Further, depending on the room, the temperature difference between the room and the hot water in the ring is as large as 5 ° C. or more, so that liquid leakage of the perforated plate occurs during hot water injection cleaning.

The residual monomer removing device of the present invention can be used in a vinyl chloride resin manufacturing device.

1 ... PVC slurry tank 2 ... PVC slurry feed pump 3 ... Heat exchanger 4 ... Residual monomer removal processing tower 5 ... PVC slurry tank 6 ... Condenser 7 ... Hot water tank 8 ... Hot water pump 9 ... Pump 10 ... Steam introduction pipe 11 ... Gas discharge port 12 ... Residual monomer gas transfer pipe 13 ... Cooling water 14 ... Cooling water outlet Hot water supply pipe 15 ... Tower bottom chamber 16-20 ... Room 21 ... Tower top chamber 22, 23 ... PVC slurry introduction pipe 24 ... PVC slurry discharge Outlets 25 to 30 ... Hot water injection cleaning valve 31 ... Hot water injection cleaning valve 32 in the bottom chamber of the tower ... Hot water circulation pressure control valve 33 ... Sight glass (same number in each room)
34 ... Perforated plate (same number in each room)
35 ... Weir board (same number in each room)
36 ... Flow pipe (same number in each room)
37 ... Sight glass cleaning pipe (same number in each room)
38 ... Hot water injection ring (same number in each room)
39 ... Nozzle hole 40 ... Pressure gauge

Claims (5)

A tubular tower body and a plurality of perforated plates provided in the vertical direction of the tower body,
A plurality of chambers formed on the perforated plate with the bottom surface as the bottom surface, and
A slurry introduction port provided on the upper side of the uppermost perforated plate among the plurality of perforated plates, and
A flow bottom provided between the perforated plates so that the slurry flows down sequentially from the perforated plate in the upper chamber to the perforated plate in the lower chamber, and
The water vapor inlet provided at the bottom of the tower body and
A condensing device provided outside the tower body via a gas transfer pipe in the tower top chamber of the tower body,
A slurry discharge port provided on the lowermost perforated plate among the plurality of perforated plates, and
Immediately below the perforated plate, there is a hot water injection device provided at least toward the lower surface of the perforated plate.
In a residual monomer removing device that removes residual monomers from a polyvinyl chloride-containing slurry containing residual monomers after the completion of polymerization.
The hot water injection device is equipped with a pressure gauge for monitoring the injection pressure and a device for controlling the injection pressure in order to inject an appropriate injection amount of hot water. .. The residual monomer removing device according to claim 1, wherein the device for controlling the injection pressure is a device for adjusting the hot water injection pressure by controlling the pressure control valve or the hot water supply pump output with an inverter. The residual monomer removing device according to claim 1 or 2, wherein the hot water injection ring provided in the hot water injection device has a cleaning nozzle for cleaning sight glasses installed at one or more locations in each chamber. The residual monomer removing device according to claim 3, wherein a cleaning nozzle for cleaning the sight glass included in the hot water injection ring is connected from above the hot water injection ring. The residual monomer removing device according to claim 3, wherein a cleaning nozzle for cleaning the sight glass included in the hot water injection ring is connected so as to be inserted into the inside of the hot water injection ring.

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