JP6656940B2 - Multi-effect thin film evaporative concentrator with switching operation - Google Patents

Description

  The present invention relates to a multiple-effect thin-film evaporative concentrator and a method of operating the same, and more particularly to a multi-effect thin-film evaporative concentrator capable of performing a switching operation between the thin-film evaporative concentrators in the same effect stage. About.

  The multi-effect thin-film evaporative concentrator is composed of two or more thin-film evaporative concentrators connected to each other. This is a device that is used as a heat medium in a concentrating can and is similarly repeated in the subsequent stages to gradually concentrate the liquid to be concentrated from the lowest concentration to take out the finally obtained highest concentration concentrated solution as a product. The thin-film evaporating and concentrating can of each effect stage is provided with a stock solution supply port provided at the top of the can, a heat transfer tube or heat transfer plate vertically arranged in the can body, and a stock solution provided at the top of the can. A dispersion mechanism for uniformly dispersing the undiluted solution introduced from the supply port into the heat transfer tube or the heat transfer plate, a gas-liquid separation mechanism provided at the lower part of the evaporating and concentrating can for separating vapor from the concentrated liquid, and a separated concentrated liquid , A liquid sending pipe for sending liquid to the next-stage thin-film evaporative concentrator or outside the system, an air-supply pipe for sending separated steam into a heat transfer tube or a heat transfer plate of the next-stage thin-film evaporative concentrator, It has a vacuum pipe for evacuating the inside of the evaporation concentrator. The boiling point of the stock solution can be lowered by evacuating the inside of the evaporation concentrator, and the stock solution is heated and self-evaporates. And flows down at high speed while being vaporized by indirect heat exchange with the heat medium flowing inside the heat transfer tube or the heat transfer plate, and the residual components are concentrated to form a concentrated liquid. The formed vapor and the concentrated liquid descend along the heat transfer tube or the heat transfer plate, and are separated into the vapor and the concentrated liquid by the gas-liquid separation mechanism below the evaporating and concentrating can.

  When an object to be concentrated in the thin film evaporating and concentrating can is a food or a chemical which solidifies by heat, scale is generated on the inner wall of the can, particularly on a heat transfer tube or a heat transfer plate. When scale is generated in the heat transfer tube or the heat transfer plate, the heat transfer efficiency decreases, and the liquid temperature and the pressure in each can increase. If there is a limit to the liquid temperature that can be used when concentrating objects that are liable to burn, or if supply of the heating medium becomes impossible due to an increase in the pressure inside the can, the operation of the device should be stopped. Need to be cleaned. Usually, in order to remove the scale, cleaning with cold water, hot water, alkali, acid, or the like is performed. If it is not a multiple effect type but a single thin film evaporating concentrator, a low concentration solution is passed through a site where a high concentration solution is originally passed to dissolve scale components or scale growth. By performing the switching operation that has the effect of preventing, the operation time of the apparatus can be prolonged, and the frequency of cleaning can be reduced. However, in the case of the multiple effect type, the switching operation could not be performed in all the cans because the steam in the preceding stage was used as the heat medium in the next stage. For example, raw water (low-concentration liquid) is treated in the first stage to form a concentrated solution at 80 ° C. and steam at 80 ° C. In the second stage, the concentrated solution (high-concentration solution) is treated and concentrated at 60 ° C. Assuming that a liquid and vapor at 60 ° C. are formed, a switching operation is performed, and raw water (low-concentration liquid) is passed through the second stage, and concentrated liquid (high-concentration liquid) is passed through the first stage. However, the temperature of the concentrated solution (highly concentrated solution) which should be treated at 60 ° C. rises to 80 ° C., and depending on the substance to be concentrated, there is a problem that deterioration and scorching occur, and scale is easily generated. is there. Further, when the concentration or viscosity of the liquid to be concentrated in each effect stage is different, by switching the supply of the liquid to be concentrated, the operation is performed under conditions different from the original set temperature and pressure of each effect stage, Operation of the entire concentrator becomes difficult.

JP-B-59-044881

The present invention has been made in view of the problems of the related art, and aims to reduce the production loss and energy loss in a multiple-effect thin-film evaporative concentrator by extending the continuous operation time of the device.

According to the present invention, there is provided a multiple-effect thin-film evaporative concentrator according to the following embodiment.
[1] A multiple-effect thin-film evaporative concentrator that separates a liquid to be concentrated into a vapor and a concentrated liquid by indirect heat exchange with a heat medium and uses the vapor as a heat medium in the next stage,
In each effect stage, two or more concentration separation units including a combination of a thin film descending evaporation concentration unit and a gas-liquid separation unit are arranged in parallel,
A pipe for individually supplying a liquid to be concentrated having a different concentration to each concentration separation section in each effect stage,
A valve for switching the supply of the liquid to be concentrated to each concentration and separation section included in the same utility stage,
And a multi-effect thin film descending evaporative concentrator that enables switching operation within the same effect stage.
[2] In each of the effect stages, a feed pipe for the concentrate that sends the low-order concentrate and the high-order concentrate from each concentration separation section to the same effect stage or another effect stage, and the low-order concentrate and the high-order concentrate The multiple-effect thin-film evaporative concentrator according to [1], further comprising: a valve for switching a destination of the concentrated liquid.
[3] The method according to [1] or [2], wherein two or more thin-film evaporative concentrators each including a combination of a thin-film evaporative concentrator and a gas-liquid separator are arranged in parallel on the same utility stage. Multi-effect thin-film evaporative concentrator.
[4] One thin-film evaporative concentrator having two or more compartments including a combination of a thin-film evaporative concentrator and a gas-liquid separator is arranged in the same utility stage, [1] to [1]. 3] The multiple-effect thin-film evaporative concentrator according to any one of [3].

  The multi-effect thin-film evaporative concentrator according to the present invention has two or more concentrating / separating sections each including a combination of a thin-film evaporating / concentrating section and a gas-liquid separating section in each effect stage. To each concentration separation unit, by providing a pipe for individually supplying a liquid to be concentrated having a different concentration, and a valve for switching the supply of the liquid to be concentrated to each concentration separation unit included in the same utility stage, This is a device that enables switching operation within the same utility stage. Concentration / separation liquids having different concentrations, temperatures, viscosities, etc. are passed through the concentration / separation sections arranged in parallel in two or more of each effect stage, and the supply of the concentration target liquid is switched between the concentration / separation sections of the same effect stage. By passing a low-concentration solution with less than the saturation solubility to the concentration / separation section through which the high-concentration solution was flowing, the scale adhering to the heat transfer tube or heat transfer plate may be dissolved or scaled to the low-concentration solution side. Prevent growth. At this time, it is preferable that the low concentrated liquid has a high temperature because the scale is easily dissolved. On the other hand, even if the highly concentrated liquid is passed through the concentration / separation section through which the lowly concentrated liquid has been flowing, the scale adhesion is not excessively increased in a short period of time because the scale adhesion is originally small. By switching the supply of the liquids to be concentrated having different concentrations among the plurality of concentration / separation sections in the same utility stage, the scale adhesion on the entire apparatus is reduced, and the continuous operation time of the entire apparatus can be prolonged.

  Since the switching of the supply of the liquid to be concentrated in each effect stage is configured to be performed individually for each effect stage, it is necessary to dissolve only the concentration and separation section of the effect stage with severe scale adhesion without stopping the entire apparatus. The switching operation can be performed individually. In addition to switching the supply of the liquid to be concentrated, it is possible to individually perform the cleaning operation in which the cleaning liquid is circulated only in the concentration separation section of the utility stage where the scale adheres heavily and the cleaning waste liquid is discharged. In the conventional apparatus, the concentration operation of the entire effect stage to be washed had to be stopped. For example, if one stage was washed in a four-effect device, the yield of the concentrated product was reduced by 25%. In the apparatus described above, only the operation of the concentration / separation section to be washed may be stopped. For example, in the case of an apparatus in which two concentration / separation sections are arranged in each stage, the yield loss of the concentrated product is reduced to 12.5%. Can be halved.

It is a schematic explanatory drawing of a thin film falling type evaporative concentration can. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic explanatory view of a multi-effect thin-film evaporative concentrator according to the present invention, in which a total of three effect stages each have two separation / concentration units arranged in parallel during normal operation of a liquid to be concentrated. The flow of is shown. 3 shows a flow of a liquid to be concentrated when a switching operation is performed in the multiple effect type thin film evaporative concentration apparatus of FIG. 2. 2 shows a flow of a liquid to be concentrated when a switching operation is performed only in a third effect stage in the multi-effect thin film evaporative concentrator of FIG. In the multi-effect thin film evaporative concentrator of FIG. 2, only the second concentration / separation section of the third effect stage is washed, normal operation is performed in the first effect stage and the second effect stage, and 1 shows the flow of the liquid to be concentrated when the switching operation is performed in the concentration separation section. It is a schematic explanatory drawing of the concentration separation part (thin film falling type evaporative concentration can) of another mode. It is a schematic explanatory drawing of the concentration separation part (thin film falling type evaporative concentration can) of another mode. It is a schematic explanatory drawing of the concentration separation part (thin film falling type evaporative concentration can) of another mode.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic explanatory view of a thin-film evaporating and concentrating can that can be used in the multi-effect thin-film evaporating and concentrating apparatus of the present invention. FIG. 2 shows an example in which the number of effect stages is three. FIG. 1 is a schematic explanatory view of the multiple effect type thin film descending type evaporative concentrator. For the sake of simplicity, the number of effect stages is three, and the number of thin-film evaporating and concentrating units in each effect stage is two. However, the number of effect stages and the number of parts are not limited and may be appropriately selected according to the application.

  At each stage, two or more concentration / separation units including a combination of a thin film descending evaporative concentration unit and a gas-liquid separation unit are installed in parallel. In FIG. 2, for the sake of simplicity, only two concentration / separation sections are shown in parallel in each effect stage.

  The first concentration / separation unit 1A and second concentration / separation unit 1B in the first stage have the same configuration, and are each a combination of a thin film descending evaporative concentration unit 11A (or B) and a gas-liquid separation unit 12A (or B). including. Hereinafter, the concentration / separation unit will be specifically described with reference to FIG. 1 taking the first stage concentration / separation unit 1A as an example. Since the concentration / separation units in the second stage / concentration / separation unit 1B and the other concentration / separation units in the other utility stages have the same configuration, reference numerals and descriptions in the drawings are omitted. In the following description, the same components are assigned the same numbers, the first-stage components are appended with “A”, and the second-stage components are appended with “B”. did. In addition, since the components and reference numerals in the drawing are complicated, the switching valve at the switching portion of each pipe is omitted.

The thin-film evaporative concentrator 11A of the first concentrator / separator 1A is provided with a heat transfer tube or heat transfer tube vertically disposed in the liquid supply port 111A for concentration and the dispersing mechanism 112A provided on the top and the body 114A. A plate 115A (only two are shown for simplicity in the figure; hereinafter, abbreviated as "heat transfer tube"), a heat transfer tube provided on the body 114A or a heat medium pipe 116A for supplying a heat transfer medium to the heat transfer plate 115A; A gas-liquid separator 12A provided at a lower portion for separating a concentrated liquid and a vapor, a first concentrated liquid supply pipe CL1A for extracting a separated concentrated liquid, an air supply pipe VL1A for extracting a separated vapor, a first Has a vacuum pipe (not shown) for evacuating the inside of the concentration separation section 1A. The air supply pipe VL1A is connected to the air supply pipe VL1 that feeds into the heat transfer pipe of the concentration / separation unit 2A at the next stage. The air supply pipe VL1B is also connected to the air supply pipe VL1B that sends steam from the second-stage concentration / separation unit 1B. A liquid supply pipe RL1A for concentration, which is branched from a liquid supply pipe RL for supplying a stock solution from a stock solution source, is connected to the liquid supply port 111A for concentration. A cleaning liquid supply pipe 117A is provided at the top of the thin film evaporating and concentrating unit 11A, and a cleaning drain pipe 118 is provided at the bottom.
A is connected.

  Heat medium from a heat source (not shown) is supplied to the heat transfer tubes 115A and 115B of the first-stage concentration and separation sections 1A and 1B through heat medium pipes 116A and 116B. The steam generated in the first-stage concentration / separation units 1A and 1B passes through the heat transfer tubes of the second-stage concentration / separation units 2A and 2B from the upper part of the gas-liquid separation units 12A and 12B via the first air supply pipe VL1. It is supplied to 215A and 215B and used as a heat carrier. Thereafter, the steam generated in the previous stage is sent to the next heat transfer tube for use as a heat medium in the next stage, and the steam generated in the last stage is sent to a condenser (not shown).

  FIG. 2 shows the flow of liquid and vapor in a multi-effect thin-film evaporative concentrator in which the concentration / separation unit shown in FIG. 1 is installed in each effect stage and two concentration / separation units are arranged in each effect stage in parallel. FIG. For the sake of simplicity, the number of utility stages is three and the number of concentration / separation sections in each utility stage is two. However, the number of utility stages and the number of concentration / separation units are not limited, and may be appropriately selected depending on the application. Further, the configuration of the concentration / separation unit in each stage is as shown in FIG. 1, and in FIG. 2, reference numerals of respective components are omitted to emphasize the flow of liquid and vapor. In the figure, the solid line indicates the flow of the liquid, the large dotted line indicates the flow of the vapor, and the fine dotted line indicates the pipe in which the liquid is not flowing.

  In FIG. 2, the first stage has first and second concentration / separation units 1A and 1B, the second stage has first and second concentration / separation units 2A and 2B, and the third stage has first and second concentration / separation units. Are respectively arranged in parallel. A heat medium from a heat source (not shown) is supplied to heat transfer tubes 115A and 115B of the first-stage thin film evaporating and concentrating units 11A and 11B via heat medium pipes 116A and 116B, respectively.

  The undiluted solution feed pipes RL1, RL2, and RL3 that supply undiluted solution from the undiluted solution feed pipe RL to each effect stage are branched. Each of the concentrate feed pipes RL1, RL2 and RL3 is switchably connected to a concentrate feed liquid feed pipe RL1A and RL1B, RL2A and RL2B, RL3A and RL3B of each effect stage via a switching valve RV11, RV21 and RV31, respectively. Have been. The switching valve RV11 switches supply of the stock solution to the first and second concentration / separation units 1A and 1B. The switching valve RV21 switches supply of the undiluted solution to the first and second concentration / separation units 2A and 2B in the second stage. The switching valve RV31 switches supply of the undiluted solution to the first and second concentration / separation units 3A and 3B in the third stage.

  The concentrated liquid sending pipes CL1A and CL1B for extracting the concentrated liquid from each of the first-stage concentrated separating sections 1A and 1B are connected to the primary concentrated liquid sending pipe CL11 and the higher concentrated liquid sending liquid via the switching valves CV11 and CV12. Each is connected to the pipe CL12. The higher-concentrated liquid sending pipe CL12 is switchably connected to a second-stage concentrated liquid sending pipe RL2A and RL2B via a switching valve RV22.

  The concentrated liquid sending pipes CL2A and CL2B for extracting the concentrated liquid from the respective second concentration separating sections 2A and 2B are connected to the primary concentrated liquid sending pipe CL21 and the higher concentrated liquid sending via switching valves CV21 and CV22. Each is connected to the pipe CL22. The higher-concentrated liquid sending pipe CL22 is switchably connected to a third-stage concentrated liquid sending pipe RL3A and RL3B via a switching valve RV32.

  The concentrated liquid sending pipes CL3A and CL3B for extracting the concentrated liquid from the respective third concentration separating sections 3A and 3B are connected to the primary concentrated liquid sending pipe CL31 and the higher concentrated liquid sending liquid via the switching valves CV31 and CV32. Each is connected to the pipe CL32. The high-order concentrated liquid sending pipe CL32 is a pipe for extracting the concentrated liquid product.

  The primary concentrate liquid feed pipes CL11, CL21, and CL31 of each effect stage are connected to the primary concentrate liquid feed pipe CL that sends the primary concentrate so as to be switchable to the first or second concentration separation section of each effect stage. I have. The downstream end of the primary concentrated liquid feed pipe CL is switchably connected to the raw liquid feed pipes RL1A and RL1B via a switching valve RV12.

  Next, the flow of the liquid to be concentrated and the flow of steam during normal operation will be described with reference to FIG. In the figure, the solid line indicates the flow of the liquid, and the difference in the degree of concentration from the stock solution to the final concentrate is indicated by the difference in the thickness of the solid line.

  The undiluted solution is fed through the undiluted solution sending pipe RL and the undiluted solution sending pipe RL1 to the concentrated liquid supply port 111A of the first thin film evaporative concentration unit 11A of the first stage, and the undiluted solution sending pipe RL and the undiluted solution sending pipe are sent. The first thin film descent of the third stage via the undiluted solution sending pipe RL and the undiluted solution sending pipe RL3 to the concentration target liquid supply port 211A of the second stage first thin film falling type evaporative concentration unit 21A via RL2. The liquid is supplied to the concentration target liquid supply port 311A of the mold evaporation concentration section 31A.

  The undiluted solution supplied to the first thin-film evaporative concentration unit 11A in the first stage contacts the heat transfer tube 115A to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation unit 12A and is separated into gas and liquid. The primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL11 via the first concentrated liquid sending pipe CL1A, merges with the primary concentrated liquid sending pipe CL, and is connected to the first concentrated liquid sending pipe RL1B via the first concentrated liquid sending pipe RL1B. It is sent to the second concentration separation section 1B of the eye.

  The undiluted solution supplied to the second-stage first thin film evaporating and concentrating unit 21A contacts the heat transfer tube 215A to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation section 22A and is separated into gas and liquid. The primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL21 via the first concentrated liquid sending pipe CL2A, merges with the primary concentrated liquid sending pipe CL, and is connected to the first concentrated liquid sending pipe RL1B via the first concentrated liquid sending pipe RL1B. It is sent to the second concentration separation section 1B of the eye.

  The liquid to be concentrated supplied to the first thin-film evaporative concentration unit 31A in the third stage contacts the heat transfer tube 315A to generate steam by indirect heat exchange, and forms a concentrated primary concentrated liquid. It is sent to the lower gas-liquid separation unit 32A to be separated into gas and liquid. The primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL31 via the first concentrated liquid sending pipe CL3A, merges with the primary concentrated liquid sending pipe CL, and is connected to the first concentrated liquid sending pipe RL1B via the first concentrated liquid sending pipe RL1B. It is sent to the second concentration separation section 1B of the eye.

  The primary concentrate supplied to the first-stage second concentration / separation unit 1B comes into contact with the heat transfer tube 115B to generate steam by indirect heat exchange, and forms a concentrated secondary concentrate to form a lower gas concentrate. The liquid is sent to the liquid separation section 12B and gas-liquid separated. The secondary concentrated liquid is sent to the second concentration / separation section 2B of the second stage via the second concentrated liquid sending pipe CL1B and the higher concentrated liquid sending pipe CL12.

  The secondary concentrated liquid supplied to the second-stage second concentrated separation section 2B comes into contact with the heat transfer tube 215B to generate steam by indirect heat exchange, and forms a concentrated tertiary concentrated liquid. The liquid is sent to the liquid separation section 22B and gas-liquid separated. The tertiary concentrated liquid is sent to the second concentration / separation section 3B at the third stage via the second concentrated liquid sending pipe CL2B and the higher concentrated liquid sending pipe CL22.

  The tertiary concentrate supplied to the third concentration / separation unit 3B in the third stage contacts the heat transfer tube 315B to generate steam by indirect heat exchange, and forms a concentrated quaternary (final) concentrate. The gas is sent to the lower gas-liquid separator 32B to be separated into gas and liquid. The fourth concentrated liquid is taken out as a concentrated liquid product via the second concentrated liquid liquid supply pipe CL3B and the higher concentrated liquid liquid supply pipe CL32.

The vapors separated in the first-stage first gas-liquid separation unit 12A and the second gas-liquid separation unit 12B in the first stage are combined in the air supply line VL1 via the air supply lines VL1A and VL1B, and are combined in the second stage. It is sent into the heat transfer tubes 215A and 215B of the concentration separation sections 2A and 2B. The vapors separated by the first gas-liquid separation unit 22A and the second gas-liquid separation unit 22B of the second stage respectively join at the air supply pipe VL2 via the air supply pipes VL2A and VL2B, and are combined at the third stage. It is sent into the heat transfer tubes 315A and 315B of the concentration separation sections 3A and 3B. The vapors separated by the first gas-liquid separation unit 32A and the second gas-liquid separation unit 32B at the third stage are combined at the air supply pipe VL3 via the air supply pipes VL3A and VL3B and sent to the condenser. .

  Next, referring to FIG. 3, the flow of the liquid to be concentrated when the switching operation is performed in each of the first to third effect stages in the multi-effect thin film evaporative concentration device of FIG. 2 will be described. .

  By the switching valves RV11, RV21 and RV31, the supply route of the stock solution from the stock solution sending pipe RL to the evaporation separation unit of each effect stage is switched, and the stock solution is concentrated in the second thin film evaporative concentration unit 11B of the first stage. The target liquid supply port 111B, the concentration target liquid supply port 211B of the second-stage second thin film evaporative concentration unit 21B, and the concentration target liquid supply port 311B of the third second thin film evaporative concentration unit 31B Supplied respectively.

  The undiluted solution supplied to the first-stage second thin-film evaporative concentration unit 11B contacts the heat transfer tube 115B to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation unit 12B and is separated into gas and liquid. The switching valve CV12 of the second concentrated liquid sending pipe CL1B is switched, the primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL11, and joins the primary concentrated liquid sending pipe CL. The switching valve RV12 of the primary concentrated liquid sending pipe CL is switched, and the primary concentrated liquid is sent to the first-stage first concentration / separation unit 1A via the concentrated target liquid sending pipe RL1A.

  The undiluted solution supplied to the second-stage second thin film evaporating and concentrating unit 21B contacts the heat transfer tube 215B to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation section 22B and is separated into gas and liquid. The switching valve CV22 of the second concentrated liquid sending pipe CL2B is switched, and the primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL21, merges with the primary concentrated liquid sending pipe CL, and is subjected to concentration target liquid sending pipe RL1A. To the first concentration / separation unit 1A at the first stage.

  The undiluted solution supplied to the third-stage second thin film evaporative concentration unit 31B contacts the heat transfer tube 315B to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation unit 32B and is separated into gas and liquid. The switching valve CV32 of the second concentrated liquid sending pipe CL3B is switched, the primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL31, merges with the primary concentrated liquid sending pipe CL, and the liquid to be concentrated RL1A is sent. To the first concentration / separation unit 1A at the first stage.

  The primary concentrated liquid supplied to the first-stage first concentrated separation section 1A contacts the heat transfer tube 115A to generate steam by indirect heat exchange, and forms a concentrated secondary concentrated liquid. The liquid is sent to the liquid separation unit 12A and gas-liquid separated. The switching valve CV11 of the first concentrated liquid sending pipe CL1A is switched, the secondary concentrated liquid is sent via the higher concentrated liquid sending pipe CL12, the switching valve RV22 is switched, and the concentrated liquid supply pipe RL2A is switched. To the first concentration / separation unit 2A at the second stage.

The secondary concentrated liquid supplied to the second concentration first separation section 2A contacts the heat transfer tube 215A to generate steam by indirect heat exchange, and forms a concentrated tertiary concentrated liquid. The liquid is sent to the liquid separation section 22A and separated into gas and liquid. The switching valve CV21 of the first concentrated liquid sending pipe CL2A is switched, and the tertiary concentrated liquid is sent via the higher concentrated liquid sending pipe CL22, and the switching valve RV
32 is switched and sent to the first concentration / separation unit 3A at the third stage via the concentration target liquid supply pipe RL3A.

  The tertiary concentrated liquid supplied to the first-stage first concentrated separation section 3A contacts the heat transfer tube 315A to generate steam by indirect heat exchange, and forms a concentrated quaternary (final) concentrated liquid. It is sent to the lower gas-liquid separation unit 32A to be separated into gas and liquid. The switching valve CV31 of the first concentrated liquid sending pipe CL3A is switched, and the fourth (final) concentrated liquid is extracted as a concentrated liquid product via the higher concentrated liquid sending pipe CL32.

The steam flow generated in each effect stage is the same as in normal operation.
Next, with reference to FIG. 4, the flow of the liquid to be concentrated when the switching operation is performed only in the third effect stage in the multiple effect type thin film evaporative concentration device of FIG. 2 will be described.

  The switching valve RV31 switches the supply path of the undiluted solution from the undiluted solution sending pipe RL to the evaporating / separating unit of each effect stage, and the undiluted solution is supplied to the first stage first thin film evaporative concentration unit 11A in the first thin film evaporating / concentrating unit 11A. 111A, the liquid to be concentrated supply port 211A of the first thin film evaporative concentration unit 21A in the second stage, and the liquid to be concentrated supply port 311B of the second thin film evaporative concentration unit 31B in the second stage, respectively. .

  The undiluted solution supplied to the first thin-film evaporative concentration unit 11A in the first stage contacts the heat transfer tube 115A to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation unit 12A and is separated into gas and liquid. The primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL11 via the first concentrated liquid sending pipe CL1A, merges with the primary concentrated liquid sending pipe CL, and is connected to the first concentrated liquid sending pipe RL1B via the first concentrated liquid sending pipe RL1B. It is sent to the second concentration separation section 1B of the eye.

  The undiluted solution supplied to the second-stage first thin film evaporating and concentrating unit 21A contacts the heat transfer tube 215A to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation section 22A and is separated into gas and liquid. The primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL21 via the first concentrated liquid sending pipe CL2A, merges with the primary concentrated liquid sending pipe CL, and is connected to the first concentrated liquid sending pipe RL1B via the first concentrated liquid sending pipe RL1B. It is sent to the second concentration separation section 1B of the eye.

  The undiluted solution supplied to the third-stage second thin film evaporative concentration unit 31B contacts the heat transfer tube 315B to generate steam by indirect heat exchange, and forms a concentrated primary concentrated solution. It is sent to the gas-liquid separation unit 32B and is separated into gas and liquid. The switching valve CV32 of the second concentrated liquid sending pipe CL3B is switched, the primary concentrated liquid is sent to the primary concentrated liquid sending pipe CL31, merges with the primary concentrated liquid sending pipe CL, and the liquid to be concentrated RL1B is sent. To the first concentration / separation unit 1B at the first stage.

  The primary concentrate supplied to the first-stage second concentration / separation unit 1B comes into contact with the heat transfer tube 115B to generate steam by indirect heat exchange, and forms a concentrated secondary concentrate to form a lower gas concentrate. The liquid is sent to the liquid separation section 12B and gas-liquid separated. The secondary concentrated liquid is sent to the second concentration / separation section 2B of the second stage via the second concentrated liquid sending pipe CL1B and the higher concentrated liquid sending pipe CL12.

  The secondary concentrated liquid supplied to the second-stage second concentrated separation section 2B comes into contact with the heat transfer tube 215B to generate steam by indirect heat exchange, and forms a concentrated tertiary concentrated liquid. The liquid is sent to the liquid separation section 22B and gas-liquid separated. The tertiary concentrated liquid is sent through the second concentrated liquid sending pipe CL2B and the higher concentrated liquid sending pipe CL22, the switching valve RV32 is switched, and the third stage liquid is sent through the concentrated target liquid supply pipe RL3A. It is sent to 1 concentration separation section 3A.

The tertiary concentrated liquid supplied to the first-stage first concentrated separation section 3A contacts the heat transfer tube 315A to generate steam by indirect heat exchange, and forms a concentrated quaternary (final) concentrated liquid. It is sent to the lower gas-liquid separation unit 32A to be separated into gas and liquid. The switching valve CV31 of the first concentrated liquid sending pipe CL3A is switched, and the fourth (final) concentrated liquid is extracted as a concentrated liquid product via the higher concentrated liquid sending pipe CL32.

The steam flow generated in each effect stage is the same as in normal operation.
Next, with reference to FIG. 5, the flow of the liquid to be concentrated when only the third-stage second thin-film evaporative concentrator is washed in the multi-effect thin-film evaporative concentrator of FIG. 2 will be described. I do.

  The cleaning liquid is supplied from the cleaning liquid supply pipe 317B to the liquid supply port 311B for concentration in the second thin film descending type evaporative concentration section 31B of the third stage, and after cleaning the inside of the evaporative concentration section 3B, the cleaning drainage pipe 318B at the bottom is provided. The washing drainage is drained from.

  On the other hand, the supply path of the undiluted solution from the undiluted solution sending pipe RL to the evaporative separation unit of each effect stage is switched by the switching valve RV31, and the undiluted solution is the liquid to be concentrated in the first thin-film evaporative concentration unit 11A of the first thin film descending type. The supply port 111A is supplied to the target liquid supply port 211A of the first thin film evaporative concentration unit 21A of the second stage, and the normal operation is performed in the first and second utility stages, and the second stage is operated. Is supplied to the first-stage first concentration / separation section 3A as in the normal operation.

  The tertiary concentrated liquid supplied to the first-stage first concentrated separation section 3A contacts the heat transfer tube 315A to generate steam by indirect heat exchange, and forms a concentrated quaternary (final) concentrated liquid. It is sent to the lower gas-liquid separation unit 32A to be separated into gas and liquid. The switching valve CV31 of the first concentrated liquid sending pipe CL3A is switched, and the fourth (final) concentrated liquid is extracted as a concentrated liquid product via the higher concentrated liquid sending pipe CL32.

The steam flow generated in each effect stage is the same as in normal operation.
In the conventional apparatus, when cleaning, it was necessary to interrupt the operation of the entire apparatus or the entire one-effect stage. However, the multiple-effect thin-film evaporative-concentration apparatus of the present invention employs any one of the one-effect stages. Only one of the evaporating and concentrating units is washed, and the other can be operated by a normal operation or a switching operation without interrupting the concentrated liquid production process. Therefore, it is possible to minimize the decrease in the yield of the concentrated liquid product.

  The switching operation in the multi-effect thin-film evaporative concentrator of the present invention can be performed independently in each evaporative concentrator in each effect stage. Switching of the flow of the liquid to be concentrated by switching can be performed by detecting an increase in pressure and / or temperature due to scale adhesion in the evaporative concentration section of each effect stage. In order to perform a more stable concentrated liquid production operation, an automatic switching operation may be employed in which the operation is automatically switched at predetermined time intervals. Since scale adhesion is likely to occur when a high-concentration liquid is treated at a high temperature, it is preferable to set a predetermined time individually according to the temperature in each evaporative concentration section and the concentration of the concentrated liquid.

  In addition, in the embodiments shown in FIGS. 1 to 5, the concentration separation section is composed of a thin-film evaporative concentration section provided by partitioning the same container, and a gas-liquid separation section provided individually in each thin-film evaporative concentration section. The combination of parts prevents the mixing of low-concentration liquids and high-concentration liquids in the gas-liquid separation section even when the liquid has foaming properties, and also prevents the mixing of cleaning liquid and product liquid during individual cleaning. Further, the apparatus is simplified, the initial cost is reduced, and the apparatus can be installed in a small space.

As described above, the multi-effect thin-film evaporative concentrator of the present invention has been described by taking as an example a three-stage apparatus configuration having two concentrating and removing units arranged in parallel on the same utility stage. It is easily understood by those skilled in the art that the same configuration and the same switching operation can be performed even in the case of having the stages and the case of having three or more concentration removing units arranged in parallel in the same utility stage. Will be.

  Also, if the foaming property of the liquid is low and the possibility of mixing the low-concentration liquid and the high-concentration liquid is low, and if there is no use of the cleaning liquid or the mixing of the cleaning liquid and the product liquid (concentrated liquid) does not pose a problem, As shown in FIG. 6, the concentration / separation unit may be a combination of a thin-film evaporating / concentrating unit provided by partitioning the same vessel and a common gas-liquid separation unit.

  If there is no problem even if the product liquid (concentrated liquid) and the washing liquid are mixed to some extent, as shown in FIG. 7, two or more thin film descending evaporative concentrating units 11 are installed in parallel, A combination in which one common gas-liquid separation unit 12 is provided between 11 may be used. As compared with the embodiments shown in FIGS. 1 to 5, installation is possible in a small space.

  In order to surely prevent the product liquid (concentrated liquid) and the cleaning liquid from being mixed, a thin film descending type evaporating and concentrating unit as shown in FIG. Two or more units may be installed in parallel.

  According to the multi-effect thin-film evaporative concentrator of the present invention, liquids to be concentrated having different concentrations are supplied to a plurality of concentration / separation sections arranged in parallel in the same effect stage, and to the respective concentration / separation sections in the same effect stage. By switching the supply of the liquid to be concentrated, the scale generated in each concentration and separation section can be dissolved or scale growth can be prevented, and the heat transfer efficiency can be recovered or maintained. As a result, the operation period of the entire apparatus can be extended.

1A, 2A, 3A: first concentration / separation units 1B, 2B, 3B: second concentration / separation units 11, 11A, 11B, 21A, 21B, 31A, 31B: thin-film evaporative concentration units 12, 12A, 12B, 22A, 22B, 32A, 32B: Gas-liquid separation units 111, 111A, 211A, 311A, 111B, 211B, 311B: Concentration target liquid supply ports 112, 112A, 212A, 212A, 112B, 212B, 212B: Dispersion mechanisms 115, 115A, 215A. , 315A, 115B, 215B, 315B: heat transfer tubes or plates 116, 116A, 216A, 316A, 116B, 216B, 316B: heat medium pipes 17, 117A, 317B: cleaning liquid supply pipes 18, 118A, 318B: cleaning drainage Pipe CL1: Concentrated liquid feed pipe CL1A, CL2A, CL3A: First concentrated Liquid feed pipes CL1B, CL2B, CL3B: second concentrate feed pipe CL11: primary concentrate feed pipe CL12: higher concentrate feed pipe VL1, VL2, VL3: air feed pipe VL1A between each effect stage , VL1B, VL2A, VL2B, VL3A, VL3B: Air supply pipes RL, RL1, RL2, RL3 from the respective vapor concentration separation sections: Raw liquid supply pipes RL1A, RL1B, RL2A, RL2B, RL3A, RL3B to each effect stage. Liquid supply pipes RV11, RV21, RV31 for the liquids to be concentrated from the respective vapor concentration separation sections RV12, RV22, RV32: Switching valves CV11, CV12, CV21, CV22, CV31, CV32 for the liquids to be concentrated Switching valve

Claims (4)

A multi-effect thin film descending evaporative concentrator that separates the liquid to be concentrated into vapor and a concentrated liquid by indirect heat exchange with a heat medium, and uses the vapor as a heat medium in the next stage,
In each effect stage, two or more concentration separation units including a combination of a thin film descending evaporation concentration unit and a gas-liquid separation unit are arranged in parallel,
A pipe for individually supplying a liquid to be concentrated having a different concentration to each concentration separation section in each effect stage,
A valve for switching the supply of the liquid to be concentrated to each concentration and separation section included in the same utility stage,
And a multi-effect thin film descending evaporative concentrator that enables switching operation within the same effect stage. A concentrated solution sending pipe for extracting a concentrated solution from each concentration / separation section of each effect stage ,
A primary concentrated liquid sending pipe for supplying the extracted concentrated liquid to another concentration separation section of the utility stage where the concentrated liquid is formed,
A high-concentrate liquid supply pipe and a liquid supply pipe for concentration, which supply the extracted concentrated liquid to an effect stage different from the effect stage in which the concentrated liquid is formed,
The extracted concentrate is supplied to another concentration / separation section of the effect stage in which the concentrate is formed, or is withdrawn so as to be supplied to another effect stage other than the effect stage in which the concentrate is formed. has been further comprising a valve for switching each feeding destination of the concentrate, multiple-effect thin-film descending evaporative concentration apparatus according to claim 1. 3. The multi-effect thin film drip according to claim 1, wherein two or more thin film drip evaporators including a combination of a thin film evaporator and a gas-liquid separator are arranged in parallel on the same utility stage. Type evaporation concentrator. 4. The thin-film evaporating and concentrating unit having two or more sections including a combination of a thin-film evaporating and concentrating unit and a gas-liquid separating unit is arranged on the same utility stage. 2. The multiple effect thin film descending type evaporative concentrator according to 1.

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