JP4666347B2 - Evaporating apparatus and evaporating method for effervescent solution - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an evaporation apparatus and an evaporation method suitable for evaporating a solvent while suppressing foaming used in operations involving boiling such as concentration of an effervescent solution.

In the operation involving boiling such as evaporative concentration of effervescent solution, solvent recovery, and distillation, when evaporating the solvent while suppressing foaming, the one described in Patent Document 1 developed by the present applicants is suitable. In this evaporator, the evaporator includes a steam outlet at the top of the can, a concentrate outlet at the bottom of the can, and a pipe end that is attached to the top of the can and protrudes from the upper gas phase portion inside the can. the foamable solution to be processed, between the heater and the tube was supplied as superheated liquid from the supply pipe to the pipe end that is connected to inject a gas-liquid mixed-phase from the tube end. In other words, in terms of the evaporation method, the foamable solution heated by the heater is evaporated in the supply pipe up to the tube end to form a gas- liquid mixed phase, and the gas-liquid mixing in the vicinity of the tube end The flow form of the phase is set to intermittent flow or annular flow, and most of the residual heat quantity in the droplets ejected from the tube end is transferred to the liquid phase part at the bottom of the can. It is released as latent heat of vaporization to complete boiling. This technique prevents foaming due to subsurface boiling and / or steam entrainment that occurs when the droplet reaches the liquid level in the evaporator, and prevents foaming of the foamable solution itself in the evaporator. In order to suppress foaming by controlling the flow form of the gas-liquid mixed phase in advance, it does not require a conventional centrifugal force or a device for creating a high vacuum, and is a mechanically movable part for breaking bubbles. Or an operation that impairs the heat efficiency of blowing gas or steam is unnecessary.

Japanese Patent Publication No. 7-5201

By the way, with the technique of the said patent document 1, although foaming can be suppressed efficiently, without complicating an apparatus, the following becomes a problem.
A) As an effervescent solution, for example, an emulsion (hereinafter referred to as an emulsion) used for coating, paper coating, fiber processing, or plastic or rubber production may be treated. In the case of evaporating and concentrating such an emulsion, the emulsion sprayed from the pipe end becomes mist and adheres to the inner surface of the vapor phase portion of the evaporator. The adhering emulsion dries without flowing down due to evaporation of moisture, and adheres to the inner surface of the can. The fixed matter is difficult to dissolve, remains as it is, becomes coarse particles, and stays on the inner surface of the can. For this reason, in actual operation, the fixed matter on the inner surface of the can must be periodically cleaned and removed, which causes a reduction in operating rate. In particular, when the evaporator is large, the cleaning efficiency is poor or a large amount of cleaning wastewater is discharged, and the subsequent processing is also expensive.
B) In addition, if the above-mentioned sticking material is peeled off and mixed in the concentrated liquid in the can, there is a problem of clogging in the piping system attached to the evaporator, so it must be filtered and removed. Liquid) quality may be adversely affected. Note that the evaporator is usually made of SS (iron) or SUS (stainless steel). 57-61004), Teflon (registered trademark) coating or glass lining, or a method of applying an anti-adhesive material (JP-A-11-35625, JP-A-4-81404, etc.) has been proposed. However, in these methods, once an emulsion film is formed on the inner surface of the can, an effect cannot be expected.

  The object of the present invention is to prevent sticking of the inner surface of the vapor phase portion of the evaporator that occurs in the process of evaporating and concentrating the foamable solution as described above, increasing the recovery efficiency of the concentrated solution, and improving the quality and reducing the cleaning process as much as possible. There is in doing so.

In order to achieve the above object, according to the present invention of claim 1, the evaporator is attached to the steam outlet provided at the top of the can, the concentrate outlet provided at the bottom of the can, and the top of the can. A pipe end protruding to the upper gas phase portion in the can and a circulation that allows the concentrated liquid in the lower can of the evaporator to be taken out from the outlet for the concentrated liquid and heated to be supplied to the pipe end In an evaporation apparatus comprising a system pipe, supplying a foamable solution to be treated as superheated liquid from the pipe to the pipe end, and jetting it as a gas-liquid mixed phase from the lower end of the pipe end,
The steam can comprises a large cylindrical main body and a small cylindrical neck with the upper portion of the main body squeezed, and is provided outside the can of the evaporation can, and the can surface corresponding to the gas phase portion in the can from the neck It is characterized by having a cooling means that cools the portion with a refrigerant and cools the adhering liquid adhering to the inner surface of the can to suppress evaporation and flow down into the concentrated liquid in the can .
As the above cooling means, as specified in claim 2, the cooling means has a gap between the neck and the can surface portion corresponding to the gas phase portion in the can and the outer wall covering the can surface portion. corresponding jacketed flow refrigerant coil type allowing the refrigerant to flow through the pipe that is wound around the can surface portion from the neck, from the neck by discharging from nozzles provided in the upper portion of the neck and the gas phase portion in the can to It is preferable that it is either of the shower type which distributes a refrigerant | coolant to the whole can surface part. In the shower type, when the refrigerant is a liquid, a tub or the like is provided on the outer periphery of the can to collect the refrigerant discharged from the nozzle at substantially the same height as the liquid level in the can.

The inventions of claims 3 and 4 are regarded as an evaporation method for evaporating and concentrating the foamable solution to be processed using the above-described evaporation apparatus. That is, the invention according to claim 3 is that the cooling means cools the can surface portion corresponding to the gas phase portion in the can, and the raw material corresponding to the volume reduced by evaporation and concentration of the foamable solution. the foamable solution before evaporation is added or supplemented to foamable solution in the process of the inner circulation system of pipes, it is characterized by keeping the liquid level in the can in the solution set range. The invention of claim 4 has liquid level detection means for detecting the liquid level in the evaporator in claim 3, and based on the detection value obtained by the liquid level detection means, the liquid of the solution in the can It is characterized by keeping the surface within a set range.
The above evaporation method uses the inventive device according to claim 1 or 2, for example, the outer surface of the can corresponding to the gas phase portion in the evaporator by the cooling means in synchronization with the temperature rise of the evaporator surface portion. The part is cooled, but the method of Patent Document 1 is substantially the same except for this point. That is, in this method, for example, control is performed so that the flow form of the gas-liquid mixed phase flow in the vicinity of the pipe end becomes an intermittent flow or an annular flow, and piping from the overheating of the foamable solution to the pipe end By evaporating in the evaporator, shearing force due to the gas-liquid speed difference is applied to the liquid surface as a gas-liquid mixed phase flow to suppress foaming in the piping, and the remaining evaporation can be performed easily. A droplet is generated by the jetting force of the vapor from the end of the tube to increase the surface area, and the evaporation is completed until the droplet reaches the bottom side liquid level of the evaporator. In such an operation, the foamable solution (concentrated liquid) in the can is kept constant by supplementing the stock solution (new foamable solution) by the amount of evaporation flowing out from the can.

In the first aspect of the invention, in the process of concentrating the foamable solution, the surface attached to the inner surface of the can is cooled by cooling the can surface portion corresponding to the gas phase portion inside the can by the cooling means. The liquid is cooled to suppress evaporation, so that the phenomenon that the adhering liquid naturally flows into the concentrated liquid in the can is reliably maintained, thereby making it possible to prevent sticking due to evaporation and drying. Moreover, bumping on the surface of the concentrated liquid in the can can be suppressed and foaming can be suppressed. As a result, in the apparatus of the present invention, for example, even if the foamable solution to be processed is an emulsion, the apparatus operation rate is improved by suppressing the sticking to the inner surface of the can, and the quality deterioration factor is eliminated to provide reliability. it can.
The invention of claim 2 can be easily installed in an existing evaporator if the cooling means is a jacket type, a coil type, or a shower type, and the attached droplets can be cooled efficiently.
The inventions of claims 3 and 4 are characterized in that the height of the foamable solution in the evaporator during the concentration process is kept constant, that is, the heat energy such as heating the solution by keeping the gas phase volume constant. Loss can be minimized. Further, by cooling the can surface corresponding to the gas phase portion in the can, the solution surface portion is also somewhat cooled, and there is an effect of reducing foaming by reducing bumping on the solution surface.

  The best mode of the present invention will be described with reference to the embodiments shown in the drawings. 1 shows a first form, FIG. 2 shows a second form, and FIG. 3 shows a third form. In the following description, the basic structure of the apparatus will be described according to the first embodiment, and after referring to the changes between the second and third embodiments, the usefulness of the present invention will be clarified with examples. In each form example, the same numerals are given to the same or similar member, and duplicate explanation is omitted as much as possible.

(First Embodiment) FIG. 1 schematically shows the entire structure of an evaporator. The evaporator includes a vertical evaporator 1, an extraction cylinder 2 that forms an upper outlet of the evaporator 1, and a plurality of pipe ends 3 that are arranged in a suspended state in the evaporator 1. The pipe 5 communicates between the common pipe 4 connected to the upper end of each pipe end 3 via a flexible hose and the like, and the outlet 1a provided at the bottom of the evaporator 1 and the common pipe 4. In addition, a pump 6 provided in the middle of the pipe 5, a heater 7, a circulation system 8 having an introduction portion for the stock solution a, and the like, a cooling means 9 for cooling the can surface portion corresponding to the gas phase portion in the can with a refrigerant, and the like It has.

  Here, the evaporator 1 is made of SS, SUS, or the like, and includes a large cylindrical main body 10 and a small cylindrical neck 11 with the upper portion of the main body 10 being narrowed, and the take-out cylinder 2 is connected to the neck 11. Yes. The take-out cylinder 2 serves as an take-out port for taking out the steam from the main body 1. Usually, although not shown, the take-out cylinder 2 is connected to a demister through a pipe. And the vapor | steam in the evaporator 1 is introduce | transduced into the demister, and is derived | led-out to a condenser as vapor | steam which removed mist with this demister, and is processed as a condensate. On the other hand, the take-out port 1a leads to the concentrated liquid in the can by deriving it by switching the on-off valves 8a and 8b attached to the pipe 5 so that it can be recovered for use as a product, or the concentrated liquid ( The foamable solution under treatment) can be sprayed again from the pipe end 3 as superheated liquid via the circulation system 8.

Each tube end 3 is on the mirror surface 12 of the main body 10 and is held vertically on a concentric circle centered on the neck 11 via a double tube 13 or the like, and the foamable solution to be treated is shared with the circulation system 8. When supplied as a superheated liquid through the tube 4, to inject a gas-liquid mixed-phase from the pipe lower end which projects into the gas phase portion of the upper within the can. The number of tube ends 3 is arbitrarily determined in consideration of the processing capability of the apparatus. The circulation system 8 is connected to a pipe section between the pump 6 and the heater 7 in the pipe 5 and introduces a foamable solution (stock solution a) from the stock solution supply section, or a foamable solution in the evaporator 1 ( The effervescent solution in the middle of concentration is taken out from the outlet 1a via the pump 6, heated to a predetermined temperature by the heater 7, and can be supplied from the common pipe 4 to each end pipe 3 as a superheated liquid.

  Further, in the above evaporation apparatus, the total amount of the foamable solution in the evaporator 1 is calculated by back-calculating from the amount of evaporation flowing out from the take-out tube 2, or the liquid level detection (not shown) attached to the evaporator 1 is detected. By grasping by means, the measurement is managed sequentially. When the apparatus is in operation, the stock solution a is added to or supplemented to the foaming solution being processed in accordance with the volume reduced by evaporation and concentration of the foaming solution, and the liquid level of the solution in the can is kept within the set range. Be controlled.

  The cooling means 9 has a jacket configuration in which an outer wall member 15 made of SS, SUS, or heat insulation is attached to the outer surface portion of the can corresponding to the gas phase portion in the can with the gap 16 being maintained. The outer wall member 15 covers from the liquid level of the solution in the can of the main body 10 to the neck 11, the lower periphery is fixed to the main body 10 side in a watertight state, and the upper periphery is watertight to the flange side of the neck 11. It is fixed to. The outer wall member 15 is provided with an inlet 15a for introducing the refrigerant into the gap 16 at the lower peripheral portion and an outlet 15b for discharging the refrigerant out of the gap 16 at the upper peripheral portion. The refrigerant is not limited to gas but may be liquid. This refrigerant is supplied from the dedicated device to the inlet 15a at a predetermined pressure or flow rate. In addition, a baffle plate, a fin, or the like for controlling the rising speed or the outflow speed of the refrigerant may be attached to the gap 16. Further, structurally, the refrigerant inlet and outlet may be set in reverse.

(Second Embodiment) FIG. 2 shows a configuration example in which the cooling means is changed. The cooling means 9 has a pipe configuration in which a pipe 17 is wound around the outer surface portion of the can corresponding to the gas phase portion in the can. The pipe 17 is not limited to the circular shape as shown in FIG. 2, but may be a so-called coil jacket type in which the pipe is halved. The pipe 17 is wound around the liquid level height of the solution in the can of the main body 10 to the neck 11 at a predetermined pitch, and discharges the refrigerant introduced from the lower end inlet 17a from the upper end outlet 17b. Also in this case, the refrigerant is a gas or a liquid, and is supplied from the dedicated device to the inlet 17a at a predetermined pressure or flow rate. Structurally, it is possible to reversely set the inlet and the outlet as in FIG.

(Third Embodiment) FIG. 3 shows another configuration example in which the cooling means is further changed. The cooling means 9 has a shower configuration in which the refrigerant is discharged from the nozzle 18 provided in the upper portion of the can and spread over the entire outer surface of the can corresponding to the gas phase portion in the can. That is, for example, the nozzle 18 is wound around the outer periphery of the neck 11 in a ring shape, and the refrigerant introduced from the inlet 18 is discharged downward from a plurality of holes provided in the ring-shaped tube portion. Further, in this example, a collar 19 is provided around the body 10 at a location corresponding to the liquid level of the solution in the can. The eaves 19 are open upward and receive liquid, which is a refrigerant discharged from the nozzle 18 in a shower shape, and can be collected from the outlet 19a.

  Next, an operation example for evaporating and concentrating the emulsion using the above-described evaporation apparatus will be described. First, the stock solution a is stored in the evaporator 1 at a predetermined temperature by a predetermined amount using the circulation system 8. Thereafter, the emulsion is heated to a predetermined temperature by the circulation system 8 with the heater 7 and the inside of the evaporator 1 is adjusted to a predetermined internal pressure. And if the superheated liquid of the circulation system 8 enters each pipe end 3 and is injected from a lower end as a gas-liquid two-phase flow, it will be isolate | separated into liquid suitability and a vapor | steam in the gaseous-phase part of can upper part. The separated droplets are released as latent heat of vaporization until reaching the liquid level in the evaporator 1 while increasing the surface area, and reach the liquid level as saturated droplets. The separated steam is introduced from the take-out tube 2 to a demister (not shown). In addition, the droplets ejected from each tube end 3 have an appropriate droplet diameter, and bubbles on the liquid surface generated by disturbances such as pressure fluctuations that are likely to occur at the start of the apparatus are extinguished by the impact force caused by the collision of the droplets. Foam. As an operating condition for suppressing foaming during normal operation, control is performed so that the flow form of the gas-liquid mixed phase in the vicinity of the pipe end 3 and the common pipe 4 becomes an intermittent flow or an annular flow. However, in practice, even if some foaming occurs, operation is possible if the foam breaking speed and the foaming speed due to the collision of the droplets are balanced and the foam layer does not exceed a certain height. These are the same as those of Patent Document 1. As described above, the emulsion in the can is taken out from the can by the circulation system 8 and reheated again, and the same concentration operation is repeated. As the evaporation and concentration progresses, the liquid level in the can (measured by a liquid level detection means not shown) falls in accordance with the evaporation amount, so the stock solution a (emulsion) is added by the amount corresponding to the evaporation amount. It is replenished and evaporative concentration is performed while keeping the liquid level in the can almost constant. The concentrated solution concentrated to the set concentration is discharged from the discharge pipe 5a in the lower part of the can to the recovery unit.

  In the above evaporative concentration operation, by cooling the can outer surface portion corresponding to the gas phase portion in the can of the evaporator 1 by the cooling means 9, the adhering liquid (droplet) adhering to the inner surface of the can is cooled. Suppresses evaporation. This is in order to reliably maintain the phenomenon that the adhered droplets naturally flow down into the concentrated liquid in the can, thereby preventing sticking caused by evaporation and drying. Further, as compared with the three cooling means 9 as the cooling structure, the jacket type in FIG. 1 is the best as the cooling efficiency (thermal efficiency). However, in the jacket type, when the number of the tube ends 3 increases, the outer wall member 15 covering the upper side of the can must be provided with a notch for each tube end 3 or the bracket 13, and thus the evaporator can with a small number of tube ends 3. Suitable for The coil type of FIG. 2 has a smaller heat transfer area and lower cooling efficiency than the jacket type, but is superior in that it does not suffer from installation restrictions or become complicated even if the tube ends 3 are increased. The nozzle type shown in FIG. 4 is suitable for reducing the equipment cost, and it is simple and simple, so that it is excellent in maintainability.

  The following examples are examples in which the concentration treatment was performed using the same apparatus as described above. In other words, the evaporators used in Examples 1 and 2 and the comparative example differ depending on the presence or absence of the cooling means 9, otherwise the evaporator can have a capacity of 35 L and an inner diameter of 300 mm, and the pipe end and the circulation system have the same settings. is there. This is an example of concentrating synthetic rubber latex (solid content of about 45%) as an effervescent solution. The cooling means 9 of the first and second embodiments is an example of the coil type shown in FIG.

(Example 1) In this concentration operation, 11 kg of synthetic rubber latex (solid content: about 45%) was charged into an evaporator, and heated at a pressure of 20 torr and a heater temperature of 50 ° C. (hot water). The evaporative concentration proceeded while flowing cold water of 2 ° C. through the pipe. In this operation, the mist-like latex flew to the gas phase and adhered to the inner surface of the can, but immediately dropped into the concentrated liquid in the can and the processing operation could proceed without solidifying. In addition, foaming on the surface of the concentrated liquid in the can was confirmed to be about several centimeters high at the start of operation. As the concentration progressed, the liquid level in the can decreased, and latex (solid content of about 45%) was added as a stock solution by a reduced amount in conjunction with the measured value of the liquid level detection means provided in the can. And it was able to drive | operate without a problem until it became latex of 60% of solid content which is a setting density | concentration.

(Example 2) In this concentration operation, 12.5 kg of synthetic rubber latex (solid content: about 45%) was charged into an evaporator, heated at an internal pressure of 25 torr, and a heater temperature of 60 ° C. (warm water). The evaporative concentration proceeded while flowing cold water of 2 ° C. through the wound pipe. In this operation, the latex that adhered to the surface of the gas phase part immediately flowed down as in Example 1 and did not solidify. Moreover, almost no foam was observed, and operation was possible without any problems until the latex had a solid content of 60%, which was the set concentration.

(Comparative Example) In this concentration operation, 13.2 kg of synthetic rubber latex (solid content: about 45%) was charged into an evaporation can, maintained at a constant vacuum of 25 torr in the can, and latex at a heater temperature of 60 ° C. (hot water). Was heated and sprayed from the end of the tube, and an evaporative concentration operation was performed. After the start of operation, the latex sprayed from the end of the tube flew into the gas phase part by mist, adhered white on the inner surface of the gas phase part, and solidified as a film (polymer film). When the solidified film was mixed in the latex solution, it might be a deteriorated latex, and it was judged that a sufficient evaporation and concentration process was impossible. This also has the effect that the latex used lacks thermal stability and tends to be altered by heat.

  As described above, the present invention only needs to satisfy the requirements of claim 1, and details can be variously modified and developed with reference to the above-described embodiments and examples.

It is a block diagram which shows typically the principal part of the evaporation apparatus which concerns on a 1st form. It is a block diagram which shows typically the principal part of the evaporation apparatus which concerns on a 2nd form. It is a block diagram which shows typically the principal part of the evaporation apparatus which concerns on a 3rd form.

1 ... Evaporator (1a is the outlet, 10 is the main body, 11 is the neck)
2 ... Take-out tube (outlet)
3 ... pipe end 4 ... common pipe 5 ... pipe 6 ... pump 7 ... heater (heater)
8 ... Circulation system 9 ... Cooling means

Claims (4)

The evaporator is provided with a steam outlet provided at the top of the can, a concentrate outlet provided at the bottom of the can, and a pipe end attached to the top of the can and projecting into the upper gas phase. And a recirculating system pipe that allows the concentrated liquid in the lower side of the evaporator to be taken out from the outlet for the concentrated liquid and heated to be supplied to the pipe end, and is a foamable solution to be processed Is supplied as superheated liquid from the pipe to the pipe end, and is ejected as a gas-liquid mixed phase from the lower end of the pipe end.
The steam can is composed of a large cylindrical body and a small cylindrical neck with the upper part of the main body squeezed,
The can is provided outside the can of the evaporating can, and the can surface portion corresponding to the gas phase portion in the can is cooled from the neck by the refrigerant to cool the adhering liquid adhering to the inner surface of the can, thereby suppressing evaporation. An evaporating apparatus for evaporating solution, characterized by having cooling means for allowing flow down into the concentrated liquid inside . Said cooling means, a jacket type allowing the refrigerant to flow through the gap between the outer wall covering the can surface portion corresponding with the gas phase and the can surface portion of said can from said neck, around the said can surface portion from the neck Either a coil type that allows a refrigerant to flow through the pipe, or a shower type that discharges from the nozzle provided at the top of the neck and distributes the refrigerant from the neck to the entire surface of the can corresponding to the gas phase portion in the can. The apparatus for evaporating a foamable solution according to claim 1. An evaporation method for evaporating and concentrating a foamable solution to be treated using the evaporation apparatus according to claim 1 or
The cooling means cools the can surface portion corresponding to the gas phase portion in the can, and the foaming solution before evaporation and concentration is a raw material corresponding to the volume reduced by concentration by evaporating the foamable solution. Is added to or supplemented to the foaming solution being treated in the piping of the circulation system, and the liquid level of the solution in the can is kept within a set range. The liquid level detection means for detecting the liquid level in the evaporator can be maintained, and the liquid level of the solution in the can is maintained within a set range based on the detection value obtained by the liquid level detection means. Item 4. A method for evaporating a foamable solution according to Item 3.

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