JP2010046571A - Method and device for concentrating aqueous solution by evaporation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for concentrating an aqueous solution by evaporation which performs the efficient concentration of the aqueous solution by evaporation at a low cost. <P>SOLUTION: The device 1 for concentrating an aqueous solution by evaporation comprises a first evaporator 30 which evaporates the aqueous solution by heat, a second evaporator 50 which produces heat transfer vapor by heating a heat transfer fluid, using the vapor of the aqueous solution produced by the first evaporator 30 as a heating source, an ejector 20 which compresses the heat transfer vapor produced by the second evaporator 50 through sucking the heat transfer vapor with the help of a driving vapor, and a compressor 26 which further compresses the heat transfer vapor compressed by the ejector 20. In addition, the device 1 utilizes the heat transfer vapor heated up by the compressor 26 as a heating source of the first evaporator 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an evaporation concentration method and an evaporation concentration apparatus for an aqueous solution.

  As an apparatus for evaporating and concentrating an aqueous solution, for example, the configuration of Patent Document 1 is known. As shown in FIG. 3, the evaporation concentrator includes an evaporator 201 having a plurality of heat transfer tubes 202, and an aqueous solution stored in the evaporator 201 is pumped up by a pump 203, and each heat transfer tube is supplied from a spreader 204. By spraying on the outer surface of 202, the aqueous solution is heated and evaporated.

  The evaporator 201 is connected to a blower compressor 206 through a suction duct 205, and the steam generated in the evaporator 201 is compressed by the blower compressor 206 and then transmitted to a plurality of transmissions through the steam duct 207. By passing through the inside of the heat tube 202, it is used as a heating source for evaporating the aqueous solution.

  Further, an ejector 209 is connected to the steam duct 207 via a branch pipe 208, and the steam compressed by the blower compressor 206 is transferred from the driving steam supply pipe 211 to the ejector 209 with the steam switching valve 210 closed. By introducing the driving steam, it is sucked into the ejector 209 and further compressed.

According to the evaporative concentration apparatus of Patent Document 1, when the aqueous solution has a low concentration, the steam switching valve 210 is opened and the blower compressor 206 is operated so that the steam generated in the evaporator 201 is blower compressor. One-stage compression is performed by 206. When the aqueous solution is gradually evaporated and concentrated to a medium concentration, the steam switching valve 210 is closed and the drive steam is supplied to the ejector 209 so that the steam generated in the evaporator 201 is blown by the blower compressor 206. After being compressed, it is compressed by the ejector 209 and compressed in two stages. Thus, even if the boiling point rises due to the concentration of the aqueous solution increasing, the surface temperature of the heat transfer tube 202 necessary for evaporation of the aqueous solution can be secured.
Japanese Patent Laid-Open No. 10-57702

  However, the conventional evaporative concentrator is configured so that when the steam is compressed in two stages, before being compressed by the ejector 209, it is first compressed by the blower compressor 206. Steam having a large specific volume is introduced at a low temperature. For this reason, the blower compressor 206 requires a large amount of equipment because the volume flow rate to be processed is large. On the other hand, since the ejector 209 sucks the steam after being compressed by the blower compressor 206, the consumption of expensive driving steam must be increased, and there is still room for cost reduction in this respect.

  Accordingly, an object of the present invention is to provide a method and an apparatus for evaporating and concentrating an aqueous solution capable of efficiently evaporating and concentrating the aqueous solution at low cost.

  The object of the present invention is a method of evaporating and concentrating an aqueous solution, wherein the vapor of the aqueous solution generated by heating in the evaporator is sucked into the ejector by driving steam and compressed, and then further compressed by a compression device. Then, the temperature is raised, and this is achieved by a method of evaporating and concentrating an aqueous solution used as a heating source of the evaporator.

  Alternatively, the object of the present invention is a method of evaporating and concentrating an aqueous solution, wherein the heat medium liquid is generated in the second evaporator using the vapor of the aqueous solution generated by heating in the first evaporator as a heating source. The heating medium vapor generated by heating is sucked into the ejector by driving steam and compressed, and then further compressed by the compression device and heated to evaporate the aqueous solution used as the heating source of the first evaporator. This is achieved by a concentration method.

  Further, the object of the present invention is to provide an evaporator for heating and evaporating the aqueous solution, an ejector for sucking and compressing the vapor of the aqueous solution generated by the evaporator by driving steam, and further compressing the vapor compressed by the ejector. And an aqueous solution evaporating and concentrating device that uses steam heated by the compressing device as a heating source of the evaporator.

  Alternatively, the object of the present invention is to provide a first evaporator for heating and evaporating the aqueous solution, and heating the heat transfer liquid by using the vapor of the aqueous solution generated by the first evaporator as a heating source. A second evaporator for generating the heat, an ejector for sucking and compressing the heat medium steam generated by the second evaporator by driving steam, and a compressor for further compressing the heat medium steam compressed by the ejector And an aqueous solution evaporating and concentrating device that uses the heat medium vapor heated by the compression device as a heating source of the first evaporator.

  According to the method for evaporating and concentrating an aqueous solution and the apparatus for evaporating and concentrating the present invention, it is possible to efficiently perform the evaporation and concentration of the aqueous solution at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an evaporative concentration apparatus according to an embodiment of the present invention. As shown in FIG. 1, the evaporative concentration apparatus 1 includes an ejector 20, a first evaporator 30, a second evaporator 50, and a condensing device 80.

  The ejector 20 is a vapor compression means for sucking and compressing the vapor. The vapor suction side 21 includes a drive vapor supply line 23 through which drive vapor such as water vapor supplied from a vapor supply source (not shown) flows, and a first A steam reuse line 54 extending from the two evaporators 50 is connected. Further, the discharge side 22 of the ejector 20 is connected to a heating steam supply line 24 that guides the steam compressed by the ejector 20 to the first evaporator 30. A compression device 26 is interposed.

  The compression device 26 is a device that mechanically compresses the gas passing through the heating steam supply pipe 24, and can be exemplified by a blower, a compressor, and the like, and an electric type that is easy to control is preferably used. Can do. The compression device 26 may be either a single stage or a multistage so as to obtain a desired compression ratio. In the present embodiment, a two-stage blower (heat pump) is used.

  The first evaporator 30 evaporates and concentrates the aqueous solution. The first evaporator 30 includes a sealed evaporator 31, an aqueous solution spraying device 32, an indirect heater 33, an aqueous solution vapor transfer line 34, and a heating medium liquid transfer line 35. The bottom of the evaporator 31 constitutes a reservoir that stores the aqueous solution supplied via the aqueous solution supply pipe 10. Examples of the aqueous solution include an alcohol aqueous solution, sulfuric acid waste water, hydrochloric acid waste water, and ammonia waste water.

  The aqueous solution spraying device 32 is a supply device that supplies the aqueous solution stored at the bottom of the evaporator 31 toward the outer surfaces of the plurality of heat transfer tubes 39, and is an aqueous solution that is disposed on the top of the evaporator 31 and sprays the aqueous solution. A spray nozzle 36 and a circulation pipe 37 that connects the aqueous solution spray nozzle 36 and the bottom of the evaporator 31 are provided. In the middle of the circulation pipe 37, a circulation pump 37 a that guides the aqueous solution stored at the bottom of the evaporator 31 to the aqueous solution spray nozzle 36 is provided. The circulation line 37 is connected to a concentrate discharge line 38 for discharging the concentrated solution of the aqueous solution accumulated at the bottom of the evaporator 31 after evaporation and concentration.

  The indirect heater 33 includes a plurality of heat transfer tubes 39 provided inside the evaporator 31, and a first header 40 and a second header 41 respectively connected to both ends of the plurality of heat transfer tubes 39. . Connected to the first header 40 is a heating steam supply pipe 24 that guides the heat transfer steam compressed by the ejector 20 to the heat transfer pipe 39. A heat medium liquid transfer pipe 35 is connected to the second header 41, and the heat medium accumulated in the second header 41 by the operation of the heat medium liquid pump 35 a interposed in the heat medium liquid transfer pipe 35. The liquid is guided to an evaporator 51 of the second evaporator 50 described later. A part of the heat medium liquid passing through the heat medium liquid transfer pipe 35 can be discharged to the outside from the middle of the heat medium liquid transfer pipe 35.

  The aqueous solution vapor transfer pipe 34 is a pipe that discharges the vapor of the aqueous solution generated in the first evaporator 30 and leads it to an indirect heater 53 of the second evaporator 50 described later. And the 1st header 60 which comprises the indirect heater 53 is connected.

  The second evaporator 50 heats the heat transfer fluid using the vapor of the aqueous solution discharged from the first evaporator 30 as a heating source. Examples of the heat transfer liquid include water, but are not limited thereto. The second evaporator 50 includes a sealed evaporator 51, a heat medium liquid spraying device 52, an indirect heater 53, a steam reuse pipe 54, and a recovery pipe 55. The basic configurations of the evaporator 51, the heat medium liquid spraying device 52, and the indirect heater 53 are the same as the basic configurations of the evaporator 31, the aqueous solution spraying device 32, and the indirect heater 33 that constitute the first evaporator 30. The heat medium liquid spraying device 52 includes a heat medium liquid spray nozzle 56 and a circulation pipe 57 in which a circulation pump 57a is interposed. A heat medium liquid discharge pipe 58 branches from the circulation pipe 57.

  The steam reuse pipe line 54 supplies at least a part of the heat medium steam discharged from the second evaporator 50 to the first evaporator 30 as a heating source for generating steam of the aqueous solution in the first evaporator 30. The upper part of the evaporator 51 and the suction side 21 of the ejector 20 are connected. A condensing steam line 70 that guides the heat medium steam generated in the second evaporator 50 to a condensing device 80 described later is connected to the steam reuse line 54.

  In the recovery pipe 55, the vapor of the aqueous solution passing through the heat transfer pipe 59 is condensed through the heat transfer pipe 59, and the condensate accumulated in the second header 61 of the indirect heater 53 is discharged to the outside by the operation of the recovery pump 55a. It is a pipeline that discharges and collects.

  The condensing device 80 is a device that generates a condensate by cooling and condensing the heat medium vapor guided from the second evaporator 50, and is branched from the vapor reuse pipe line 54 of the second evaporator 50. A condensing steam pipe 70 extending, a cooling water supply pipe 81 through which cooling water is guided, and a condensed water supply pipe 82 for returning the generated condensed water to the evaporator 51 of the second evaporator 50 are connected. As the cooling water guided to the condensing device 80 through the cooling water supply pipe 81, industrial water cooled by a cooling tower (not shown), cold water (chiller water) cooled by a refrigeration device, or the like can be used.

  Next, the operation of the evaporative concentration apparatus 1 having the above configuration will be described. First, the aqueous solution is supplied from the aqueous solution supply pipe 10 to the evaporator 31 of the first evaporator 30. The aqueous solution stored at the bottom of the evaporator 31 is supplied to the aqueous solution spray nozzle 36 through the circulation pipe 37 by the operation of the circulation pump 37 a and sprayed on the outer surface of each heat transfer tube 39.

  Inside each heat transfer tube 39, a high-temperature heat medium vapor such as water vapor supplied from the compression device 26 passes, and a part of the aqueous solution evaporates due to heat exchange inside and outside the heat transfer tube 39. The vapor of the aqueous solution thus generated is supplied from the upper part of the evaporator 31 to the first header 60 of the second evaporator 50 via the vapor transfer pipe 34.

  The aqueous solution that has not evaporated on the outer surface of the heat transfer tube 39 flows down along the outer surface of each heat transfer tube 39 and is stored at the bottom of the evaporator 31, and is again sprayed from the aqueous solution spray nozzle 36 through the circulation line 37. The The aqueous solution concentrated in the evaporator 31 can be partially discharged from the middle of the circulation pipe 37 to the concentrate discharge pipe 38 and discharged to the outside.

  On the other hand, the heat medium vapor that has passed through the inside of the heat transfer tube 39 and exchanged heat with the aqueous solution is cooled to become a heat medium liquid and stored in the second header 41. A part of the heat medium liquid is discharged to the outside by the operation of the heat medium liquid pump 35 a, and the remaining part is supplied to the evaporator 51 of the second evaporator 50 via the heat medium liquid transfer pipe 35.

  In the second evaporator 50, the heat transfer fluid stored in the evaporator 51 is sprayed from the heat transfer fluid spray nozzle 56 to the outer surface of each heat transfer tube 59 by the operation of the circulation pump 57a. The aqueous solution vapor supplied from the first evaporator 30 passes through the inside of the heat transfer tube 59, and a part of the heat transfer liquid evaporates due to heat exchange inside and outside the heat transfer tube 59. The generated heat medium steam is sucked and compressed by the ejector 20 by supplying the drive steam from the drive steam supply line 23 to the ejector 20, and is supplied to the compression device 26 together with the drive steam. Then, after mechanical compression is performed in the compression device 26, it is supplied to the first header 40 of the first evaporator 30 and used as a heating source for evaporating the aqueous solution in the first evaporator 30.

  Excess heat medium vapor is supplied to the condensing device 80 via the condensing steam line 70 and condensed by heat exchange with the cooling water passing through the cooling water supply line 81. The generated condensate is returned again to the evaporator 51 of the second evaporator 50 via the condensed water supply line 82.

  The heat transfer fluid that has not evaporated on the outer surface of the heat transfer tube 59 flows down along the outer surface of the heat transfer tube 59 and is stored at the bottom of the evaporator 51, and again passes through the circulation line 57 to be the heat transfer fluid spray nozzle 56. Scattered from. A part of the heat medium liquid passing through the circulation pipe 57 can be discharged to the outside through the heat medium liquid discharge pipe 58. Thus, heat exchange between the heat transfer fluid and the aqueous solution vapor is performed in a state where a constant amount of the heat transfer fluid is always stored in the evaporator 51 of the second evaporator 50.

  The vapor of the aqueous solution that has passed through the inside of the heat transfer tube 59 and exchanged heat with the heat transfer fluid is cooled to become a condensate, and stored in the second header 61. This condensate is recovered as recovered acid or the like through the recovery line 55 by the operation of the recovery pump 55a.

  Thus, according to the evaporation concentrating device 1 according to the present embodiment, the heat medium vapor generated by the second evaporator 50 is first compressed by the ejector 20, and then further compressed by the compression device 26, One evaporator 30 is used as a heating source for evaporating the aqueous solution. Therefore, relatively low-temperature heat transfer steam can be efficiently sucked into the ejector 20 by a small flow rate of driving steam, and the compression device 26 compresses the steam heated by the ejector 20 so that the volume flow rate is low. Reduction can be achieved, and the size of the compression device 26 can be reduced as compared with the prior art. As a result, the evaporation and concentration of the aqueous solution in the first evaporator 30 can be efficiently performed at low cost. In particular, when continuously evaporating and concentrating an aqueous solution, the blower compressor and the ejector must be used together in the configuration disclosed in Patent Document 1, and the above-described effect becomes more remarkable. Therefore, the evaporative concentration apparatus of the present invention is particularly suitable when a large amount of aqueous solution is continuously processed.

  As mentioned above, although one Embodiment of this invention was explained in full detail, the specific aspect of this invention is not limited to the said embodiment. For example, in the present embodiment, the first evaporator 30 and the second evaporator 50 are provided, and the aqueous solution and the heat transfer liquid are completely separated from each other by evaporating the aqueous solution and the heat transfer liquid to form a heating source. The vapor of the aqueous solution is configured not to be supplied to the ejector 20 or the compression device 26, but the vapor of the aqueous solution generated in the evaporator 110 is converted into the evaporator 110 itself as in the evaporation and concentration device 100 shown in FIG. It can also be configured to be used as a heating source.

  In FIG. 2, the evaporator 110 includes a sealed evaporator 111, an aqueous solution spraying device 112, an indirect heater 113, a steam reuse pipe 114 and a recovery pipe 115. The basic configurations of the evaporator 111, the aqueous solution spraying device 112, and the indirect heater 113 are the same as the basic configurations of the evaporator 31, the aqueous solution spraying device 32, and the indirect heater 33 that constitute the first evaporator 30 of FIG. The aqueous solution spraying device 112 includes an aqueous solution spraying nozzle 116 and a circulation pipe 117 in which a circulation pump 117a is interposed. An aqueous solution discharge pipe 118 is branched from the circulation pipe 117, and the aqueous solution concentrated by the evaporator 111 can be discharged.

  The steam reuse pipe line 114 connects the upper part of the evaporator 111 and the suction side 21 of the ejector 20, and a part of the aqueous solution vapor generated in the evaporator 111 is in the middle of the steam reuse pipe line 114. Is connected to the condensing steam line 70. Since the configurations of the ejector 20, the compression device 26, and the condensing device 80 are the same as those in FIG. 1, the same numbers as those in FIG.

  The aqueous solution supplied from the aqueous solution supply pipe 101 to the evaporator 111 is sprayed by the aqueous solution spraying device 112 and is evaporated on the outer surface of the heat transfer tube 119 by high-temperature steam passing through the heat transfer tube 119 of the indirect heater 113. . The steam of the generated aqueous solution is sucked into the ejector 20 by supplying driving steam to the ejector 20, further mechanically compressed by the compression device 26, and then passed through the first header 120 of the evaporator 110 to the heat transfer tube 119. Supplied.

  The steam that has passed through the inside of the heat transfer tube 119 is cooled by heat exchange inside and outside the heat transfer tube 119, becomes a condensate, and is stored in the second header 121. This condensate is supplied to the condensing device 80 via the recovery line 115 and discharged together with the aqueous solution vapor supplied from the condensing steam line 70 from the condensate discharge line 83.

  Also in the evaporative concentration apparatus 110 of the present embodiment, similarly to the evaporative concentration apparatus 1 shown in FIG. 1, the consumption amount of driving steam supplied to the ejector 20 and the driving power of the compression apparatus 26 can be suppressed. Evaporation concentration processing can be performed efficiently.

  The present invention will be described in more detail based on examples and comparative examples of the present invention. However, a specific aspect of the present invention is not limited to the above embodiment.

  As in the evaporation concentrator shown in FIG. 1, the heat medium vapor discharged from the second evaporator 50 is first introduced into the ejector 20 and compressed, and then compressed by the two-stage blower (heat pump) of the compressor 26. The temperature difference obtained in the case was measured. This is shown in Table 1 as Example 1. In Table 1, “EJ steam consumption” indicates the flow rate (weight flow rate) of the driving steam in the ejector 20, and “HP 1-axis power” and “HP 2-axis power” indicate the power consumption of the two blowers of the compressor 26. Show. In Example 1, the heat medium vapor before being introduced into the ejector 20 is 42.0 ° C., whereas the vapor temperature after being discharged from the compressor 26 is raised to 63.3 ° C., and 21.3 ° C. The temperature difference is obtained.

  On the other hand, when the temperature difference obtained when the heat medium vapor was first compressed by the two-stage blower and then compressed by the ejector was measured, as shown in Table 1 as Comparative Example 1, it was the same as Example 1. A temperature difference of only 20 ° C. was obtained with respect to the EJ steam consumption.

  Therefore, when the rotational speed of the two-stage blower was increased under the conditions of Comparative Example 1 so that the same temperature difference as Example 1 was obtained, as shown in Table 1 as Comparative Example 2, the EJ steam consumption amount, In addition, the total of the HP1 shaft power and the HP2 shaft power was increased as compared with that of Example 1, and the difference in effect from Example 1 was clear.

It is a schematic block diagram of the evaporative concentration apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram of the evaporative concentration apparatus which concerns on other embodiment of this invention. It is a schematic block diagram of the conventional evaporative concentration apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Evaporation concentration apparatus 20 Ejector 26 Compression apparatus 30 1st evaporator 50 2nd evaporator 110 Evaporator

Claims (4)

A method for evaporating and concentrating an aqueous solution,
The vapor of the aqueous solution generated by heating in the evaporator is sucked into the ejector by the driving vapor and compressed, and then further compressed by the compression device to increase the temperature, and the aqueous solution used as the heating source of the evaporator Evaporative concentration method. A method for evaporating and concentrating an aqueous solution,
Using the vapor of the aqueous solution generated by heating in the first evaporator as a heating source, the heat medium vapor generated by heating the heat medium liquid in the second evaporator is sucked into the ejector by the driving steam. The method of evaporating and concentrating the aqueous solution used as a heating source of the first evaporator after further compression by a compression device and raising the temperature. An evaporator that heats and evaporates the aqueous solution;
An ejector that sucks and compresses the vapor of the aqueous solution generated by the evaporator with driving steam;
A compressor for further compressing the steam compressed by the ejector,
An apparatus for evaporating and concentrating an aqueous solution, using steam heated by the compression apparatus as a heating source of the evaporator. A first evaporator that heats and evaporates the aqueous solution;
A second evaporator that generates heat medium vapor by heating the heat medium liquid using the vapor of the aqueous solution generated in the first evaporator as a heating source;
An ejector that sucks and compresses the heat medium steam generated by the second evaporator by driving steam;
A compression device that further compresses the heat medium vapor compressed by the ejector,
An aqueous solution evaporating and concentrating device that uses the heat medium vapor heated by the compression device as a heating source of the first evaporator.

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