TWI758987B - Recovery device and recovery method of low boiling point substances - Google Patents

Abstract

Provided are a low-boiling point substance recovery device and a recovery method, which can recover low-boiling point substances at a high concentration and achieve energy saving.

An ammonia recovery device (1) is provided with: a distillation column (2) for carrying out steam stripping by blowing heating steam; The steam exchanges heat with water to evaporate the water; the compression device (4) compresses and raises the temperature of the steam discharged from the evaporator (3) and discharges it to the distillation column (2) as heating steam; the concentration column (5) ), is to take in the concentrated ammonia-containing vapor in the evaporator (3), cool the vapor and remove moisture to increase the concentration of the ammonia-containing vapor to a high concentration (for example, more than 20wt%); the first absorption tower (6) a second absorption tower (7) to prevent the uncondensed ammonia-containing vapor in the first absorption tower from being discharged to the outside.

Description

Recovery device and recovery method of low boiling point substances

The present invention relates to a recovery apparatus and recovery method for separating and recovering low-boiling substances from waste water containing low-boiling substances such as ammonia.

As a method for separating and removing wastewater containing ammonia, a steam stripping method is known. A general ammonia recovery apparatus using this steam stripping method is equipped with a distillation column for steam stripping, and the ammonia-containing vapor discharged from the top of the distillation column is partially condensed by a condenser, and the condensed water is used as a reflux liquid. Returning to the top of the distillation tower, the remaining concentrated ammonia-containing vapor is supplied to the absorption tower to be absorbed by water and taken out as recovered ammonia water.

However, the steam stripping method used in such an ammonia recovery device is a method of blowing steam directly into the bottom of the distillation column and uses a large amount of steam, so the running cost is high, and the reduction of the treatment cost is sought. On the other hand, in this method, although steam containing ammonia is generated in an amount almost the same as the amount of steam introduced, it is necessary to use this as a reflux liquid to the top of the distillation column and to recover the ammonia liquid. Cooling by a heat exchanger (condenser) installed at the top of the tower consumes energy.

In order to solve the above-mentioned problems, it has been proposed to compress the vapor discharged from the top of the distillation tower with a vapor compressor, and then use a reboiler to compress it. Those that perform heat recovery to reduce the amount of water vapor (see Patent Document 1 below). In addition, it is proposed to supply make-up water to a condenser for partially condensing the ammonia-containing vapor discharged from the top of the distillation column, and to vaporize the make-up water by heat exchange with the ammonia-containing vapor, and guide it to a vapor compressor for compression. , a structure in which the temperature rises to become water vapor and is reused (refer to the following Patent Document 2).

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2002-28637

[Patent Document 2] Japanese Patent Laid-Open No. 2004-114029

In the conventional examples disclosed in the above-mentioned Patent Documents 1 and 2, the heat of the ammonia-containing vapor discharged from the column top of the distillation column is effectively utilized to save energy and reduce operating costs.

However, as described above, in the structure of the conventional example including at least a distillation column, a heat exchanger (reboiler or condenser: these reboilers or condensers correspond to the evaporator of the present invention), and a vapor compressor, When, for example, high-concentration ammonia of 20 wt % or more is to be recovered, the following problems arise. That is, when it is desired to increase the concentration to a high concentration only by the heat exchanger (equivalent to the evaporator in this case), the temperature difference between the inlet and the outlet of the ammonia-containing vapor of the heat exchanger will become larger, and the load of the vapor compressor will become larger. If it is too large, it will be due to the Use and violate the requirements of energy saving. In addition, the above-mentioned problems are not limited to ammonia, but can be widely used in recovery apparatuses containing low-boiling substances.

Therefore, there has been a demand for a low-boiling substance recovery device capable of recovering ammonia at a higher concentration than in the past and achieving energy saving.

The present invention was conceived in view of the above-mentioned problems, and an object thereof is to provide a low-boiling substance recovery device and a recovery method that can recover low-boiling substances at high concentrations and achieve energy saving.

In order to achieve the above object, the present invention is a low-boiling substance recovery device characterized by comprising: a distillation column for contacting a raw liquid containing low-boiling substances with heating water vapor, and separating the low-boiling substances from the raw solution and separating the low-boiling substances from the raw solution. It is gasified and discharged from the top of the tower as a vapor containing low-boiling substances, and the treated water that has removed the low-boiling substances from the raw liquid is stored at the bottom of the tower; the evaporator is the distillation tower that is discharged from the top of the distillation tower. The vapor of the boiling point substance exchanges heat with water, whereby the vapor containing the low boiling point substance is partially condensed, the vapor containing the low boiling point substance is concentrated, and the water is evaporated and discharged as water vapor; the compression device is a The steam discharged from the evaporator is compressed and heated, and the compressed and heated steam is guided to the distillation column, and used as the heating steam used in the distillation column; and the concentration column is a The vapor containing the low boiling point substance after being partially condensed in the evaporator is taken in, and the vapor containing the low boiling point substance is further concentrated by cooling the vapor and removing moisture.

According to the above configuration, an evaporator and a concentration column arranged in the subsequent stage of the evaporator are provided, and the ammonia-containing vapor discharged from the distillation column can be concentrated in two stages of the evaporator and the concentration column to generate a predetermined high concentration (for example, 20wt% or more) of the vapor containing low boiling point substances. According to the above-mentioned structure, it is possible to prevent the load on the compression device from becoming too large compared to the structure in which the concentration is concentrated to a predetermined high concentration (for example, 20 wt % or more) only by the evaporator. As a result, energy saving can be achieved, and a recovery device capable of generating a vapor containing a low boiling point substance at a high concentration (eg, 20 wt % or more) can be obtained.

As the "low boiling point substance", alcohols such as ammonia and methanol, ketones such as acetone, esters such as methyl acetate, and the like can be applied.

As "water", pure water, soft water, ion-exchanged water, etc. can be applied.

One aspect of the present invention is the above-mentioned low-boiling substance recovery device, further comprising a preheater provided in the middle of a discharge line for discharging the treated water stored in the column bottom of the distillation column to the outside, and the above-mentioned The water used in the evaporator is heated by exchanging heat with the treated water in advance.

According to the above structure, the water used in the evaporator is preheated, thereby achieving energy saving in the heat exchange of the evaporator.

Another embodiment of the present invention is the above-mentioned low-boiling substance recovery device, further comprising: a heat exchanger provided in a circulation line for guiding the stored liquid stored at the bottom of the column of the concentration column to the top of the column On the way, the above-mentioned reserved liquid flowing in the circulation pipeline is exchanged with the cooling water to cool the reserved liquid; the temperature sensor detects the temperature of the reserved liquid stored in the bottom of the tower of the above-mentioned concentration tower; and the control valve , is in response to the former The detection result of the temperature sensor is used to adjust the flow rate of the cooling water passing through the heat exchanger.

According to the above configuration, the opening degree of the control valve is controlled according to the detection result of the temperature sensor, thereby adjusting the flow rate of the cooling water passing through the heat exchanger. In this way, the stored liquid (condensed liquid containing low boiling point vapor) stored at the bottom of the concentration tower is cooled to a predetermined temperature and sprayed, whereby a predetermined high concentration (for example, 20 wt% or more) of ammonia-containing vapor can be generated. .

Another embodiment of the present invention is the above-described low-boiling substance recovery device, wherein the compression device is configured by connecting a plurality of vapor compressors in parallel.

Another embodiment of the present invention is the above-mentioned low-boiling substance recovery device, wherein the low-boiling substance is ammonia.

In order to achieve the above object, the present invention is also a method for recovering a low-boiling substance, characterized by comprising: a first step of blowing heating steam into a distillation column, and contacting the raw solution containing the low-boiling substance with the heating steam, And from the aforementioned stoste, the low-boiling substances are separated and gasified to be discharged from the top of the distillation column as the vapor containing the low-boiling substances, and the treated water for removing the low-boiling substances from the stoste is stored at the bottom of the distillation tower; The second step is to partially condense the vapor containing the low boiling point substance by exchanging heat with water and the vapor containing the low boiling point substance discharged from the top of the distillation column to make the vapor containing the low boiling point substance Concentrating, and evaporating the water and discharging it as water vapor; the third step is to compress and heat up the water vapor discharged from the evaporator, and guide the compressed and heated water vapor to the distillation tower, and It is used as heating water vapor used in the distillation column; and in the fourth step, the vapor containing the low-boiling point substance after being partially condensed in the evaporator is taken in, the vapor is cooled and water is removed, and the low-boiling point substance-containing vapor is cooled. The vapor is further concentrated.

According to the above structure, a method for recovering a low-boiling-point substance that can collect a low-boiling-point substance at a high concentration and achieve energy saving is constructed.

According to the present invention, low-boiling substances can be recovered at a high concentration, and energy saving can be achieved.

1: Ammonia recovery unit

2: Distillation tower

3: Evaporator

4: Compression device

5: Concentration tower

6: The first absorption tower

7: The second absorption tower

18, 19: Vapor compressor

FIG. 1 is an overall configuration diagram of an ammonia recovery apparatus according to an embodiment.

FIG. 2 is an enlarged view of the vicinity of the evaporator.

Fig. 3 is an enlarged view of the vicinity of the concentration tower.

Hereinafter, the present invention will be described in detail based on embodiments. Moreover, in the following embodiment, as a low boiling point substance recovery apparatus, the ammonia recovery apparatus which uses ammonia-containing waste water as a raw liquid, separates and removes ammonia from this ammonia-containing waste water, and collects it will be demonstrated. As the low-boiling substance, in addition to ammonia, alcohols such as methanol, ketones such as acetone, esters such as methyl esters.

(Embodiment)

FIG. 1 is an overall configuration diagram of an ammonia recovery apparatus according to an embodiment. The ammonia recovery device (equivalent to the low-boiling substance recovery device of the present invention) 1 is provided with: a distillation column 2 for carrying out steam stripping by blowing heating steam; The discharged ammonia-containing vapor exchanges heat with water to evaporate the water; the compression device 4 compresses and raises the temperature of the water vapor discharged from the evaporator 3 and discharges it to the distillation tower 2 as heating water vapor; the concentration tower 5 is to The ammonia-containing vapor concentrated in the evaporator 3 is taken in to cool the vapor and remove moisture to raise the concentration of the ammonia-containing vapor to a high concentration (for example, 20 wt% or more); the first absorption tower 6 makes the concentration of the vapor from the concentration tower 5 The ammonia-containing vapor absorbs moisture to generate recovered ammonia water of a predetermined concentration; and the second absorption tower 7 prevents the uncondensed ammonia-containing vapor in the first absorption tower from being discharged to the outside. Here, the general features of the ammonia recovery device 1 according to the first embodiment will be described. The evaporator 3 and the concentration column 5 arranged in the subsequent stage of the evaporator 3 are provided, so that the content of the ammonia recovered from the distillation column 2 is discharged. The ammonia vapor can be recovered with a predetermined high concentration (for example, 20 wt% or more) of ammonia water by the two-stage concentration of the evaporator 3 and the concentration tower 5.

Hereinafter, the specific structure of the ammonia recovery apparatus 1 will be described together with the above-mentioned characteristic structure. In the distillation column 2, a multistage one can be used, and it is not limited to this, and a non-multistage one can also be used. That is, as the distillation column 2, a tray column or a packed column can be used. At the top of the distillation column 2, a stock solution (ammonia-containing waste water) is supplied through a stock solution supply pipe L1. In addition, it is also possible to advance the raw liquid Perform pH adjustment.

At the bottom of the distillation column 2, the heating steam from the steam discharger 10 is supplied through the heating steam supply pipe L3. The column bottom of the distillation column 2 is connected to the heat recovery tank 11 through the pipe L4, and the stored liquid (low-concentration ammonia water) in the column bottom is supplied to the heat recovery tank 11 through the pipe L4. The vapor discharger 10 is a vapor compressing means for suctioning and compressing vapor, and is connected to the vapor suction side 10a: a vapor supply pipe L5 for circulating vapor supplied from a high-pressure vapor source (not shown) such as a boiler, and A steam reuse pipe L6 extending from the heat recovery tank 11. With the above structure, the stored liquid in the heat recovery tank 11 is flashed, sucked and compressed by the vapor discharger 10, mixed with the vapor from the vapor supply pipe L5, and blown into the distillation column 2 as heating vapor. bottom of the tower. As described above, the stored liquid in the heat recovery tank 11 is flashed and reused as a part of the heating steam to recover heat.

In addition, a discharge pipe L7 for discharging treated water (eg, low-concentration ammonia water of 30 ppm or less) is connected to the bottom of the heat recovery tank 11, and the discharge pipe L7 is provided with a treated water discharge pump P1 and three heat exchangers device H1, H2, H3. The heat exchanger H1 is a water heater that heats water by exchanging heat between water and treated water. The water heated by the heat exchanger H1 is supplied to the bottom of the evaporator 3 through the water supply pipe L8. The heat exchanger H2 is a raw liquid preheater for preheating the raw liquid by exchanging heat between the raw liquid and the treatment water. The raw liquid preheated by the heat exchanger H2 is supplied to the top of the distillation column 2 through the raw liquid supply pipe L1. The heat exchanger H3 is a cooler that cools the treated water by exchanging heat between the cooling water and the treated water. Process cooled by this heat exchanger H3 The water is discharged to the outside of the system through the discharge pipe L7.

The heat exchangers H1, H2, and H3 are located on the downstream side of the discharge pipe L7 above the treated water discharge pump P1, and are installed in the following order. That is, in the discharge pipe L7, the heat exchanger H1 is provided on the upstream side of the heat exchanger H2. By installing in the above-mentioned order, the amount of heat given to the water by the treated water can be maximized, so that the energy saving of the evaporator 3 for heating the water can be achieved. In addition, the reason for installing the heat exchanger H3 is to cool the treated water, so the heat exchanger H3 is installed on the downstream side of the heat exchangers H1 and H2.

The evaporator 3 is configured as a horizontal tube type evaporator 12 and includes a sprayer 13 and an indirect heater 14 . Moreover, it is not limited to a horizontal pipe type, For example, the evaporation tank of a film flow down (vertical pipe) type, etc. may be used. As shown in FIG. 2 , the indirect heater 14 includes a heat transfer pipe group 15 formed of one or a plurality of horizontal heat transfer pipes, and a pair of left and right manifolds 16A and 16B. Moreover, the bottom part of the evaporation tank 12 becomes the storage part 17 and stores the water supplied through the pipe L8. The storage liquid (water) in the storage part 17 is supplied to the sprayer 13 provided in the upper part of the evaporation tank 12 through the pipe L9 by the circulation pump P2, and is sprayed from the sprayer 13 toward the outer surface of the heat transfer tube group 15. , a structure that flows down to the storage part 17 in the lower part of the evaporation tank 12 and circulates.

The manifold 16B is connected to the vapor supply pipe L10 through the top of the distillation column 2, and the overhead vapor (ammonia-containing vapor) discharged from the top of the distillation tower 2 is guided through the vapor supply pipe L10 to a maximum of The manifold 16B flows through the heat transfer pipe group 15 . Here, the evaporator 3 is a ratio of Since the pressure of the vapor at the top of the tower is still lower, the circulating liquid (water) sprayed by the sprayer 13 evaporates on the surface of the heat transfer pipe group 15 to produce water vapor. The water vapor is supplied to the compression device 4 . Here, the principle of vaporizing water in the evaporator 3 will be described in more detail. In the evaporator 3, the pressure on the outside of the heat transfer pipe where the heated water exists is caused by the overhead steam (inside the heat transfer pipe) that becomes the heating source. lower, so the water will evaporate. In addition, the pressure difference is generated by the compression device 4 (specifically, the vapor compressors 18 and 19). This is because the outer side of the evaporator heat pipe connected to the suction side of the compression device 4 is relatively low, and the pressure of the distillation column 2 connected to the discharge side of the compression device 4 and even the pressure of the top vapor is relatively high. In addition, the pressure in the distillation column 2 is also raised by the steam supplied from the steam discharger 10 , which is a factor for evaporating the water in the evaporator 3 .

In addition, the condensed water (low-concentration ammonia water) which circulates and condenses in the heat transfer pipe group 15 is stored in the manifold 16A, and is returned to the distillation column 2 as a reflux liquid through the pipe L11 by the driving of the condensed water pump P3. top of the tower. The other residual vapor (concentrated ammonia-containing vapor) is discharged to the top of the concentration tower 5 through the pipe L12.

The compression device 4 includes two vapor compressors 18 and 19, and these vapor compressors 18 and 19 are configured by connecting the bottom of the distillation column 2 and the upper part of the evaporation tank 12 in parallel. That is, the inlet side 18a of the vapor compressor 18 is connected to the upper part of the evaporation tank 12 through the pipe L15, and the outlet side 18b of the vapor compressor 18 is connected to the bottom of the distillation column 2 through the pipe L16. The inlet side 19a of the vapor compressor 19 is connected to the upper part of the evaporation can 10 through a branch pipe L17 branching from the pipe L5, and the outlet side 19b of the vapor compressor 19 is It is connected to the bottom of the distillation column 2 through the pipe L18.

Here, as the vapor compressors 18 and 19, a Roots-type vapor compressor having a large maximum differential pressure is used. However, in the present invention, it is not limited to the Roots-type steam compressor, and any of a turbo-type steam compressor, a screw-type steam compressor, a vane-type steam compressor, or other steam compressors may be used. In addition, the compression device 4 is constituted by two steam compressors 18 and 19 in the present embodiment, but may be constituted by one steam compressor or three or more steam compressors.

The concentration tower 5 is constituted by a spray-type scrubber. The retained liquid (condensate) stored in the tower bottom of the concentration tower 5 flows through the spray pipe (corresponding to the circulation line of the present invention) L20, is guided to the top of the tower, and is sprayed toward the top of the tower. In the middle of this spray pipe L20, a circulation pump P4 and a heat exchanger H4 are provided. The stored liquid flowing through the spray pipe L20 is cooled by exchanging heat with the cooling water in the heat exchanger H4. Moreover, as shown in FIG. 3, the control valve V1 is provided in the pipe L21 in which the cooling water flows, and the opening degree is controlled by the temperature sensor T which detects the temperature of the stored liquid stored in the tower bottom of the concentration tower 5. That is, the opening degree of the control valve V1 is controlled according to the detection result of the temperature sensor T, thereby adjusting the flow rate of the cooling water passing through the heat exchanger H4. Thereby, the ammonia-containing vapor of a predetermined high concentration (for example, 20 wt % or more) can be generated by cooling the stored liquid (condensate) to a predetermined temperature and spraying.

In addition, as shown in FIG. 3 , the spray pipe L20 is branched on the way, and the branched branch pipe L22 is connected to the top of the distillation column 2 . A control valve V2 is provided in the middle of the branch pipe L22. And, in the concentration tower 5, as shown in Figure 3 As shown, a liquid level sensor S1 for detecting the liquid level of the stored liquid is provided. The liquid level sensor S includes a level switch S1a for detecting the upper limit set level and a level switch S1b for detecting the lower limit set level. The liquid level sensor S1 controls the opening of the control valve V2 to maintain the liquid level at a predetermined level, and the liquid level exceeding the predetermined liquid level is refluxed to the top of the distillation column 2 .

The first absorption tower 6 is constituted by the same spray scrubber as the concentration tower 5, and a circulation pump P5 and a heat exchanger H5 are provided in the spray pipe L23 which circulates the stored liquid of the first absorption tower 6. In the heat exchanger H5, the stored liquid flowing through the spray pipe L23 is heat-exchanged with the cooling water, and the stored liquid is cooled. The cooled retentate is sprayed to the high concentration (for example, 20 wt% or more) ammonia-containing vapor taken in from the concentration tower 5 through the pipe L24, whereby the ammonia-containing vapor is condensed and recovered to generate recovered ammonia water. . In addition, the spray pipe L23 is branched on the way, and the recovered ammonia water is discharged to the outside of the system through the branched branch pipe L25.

The second absorption tower 7 is composed of the same spray scrubber as the first absorption tower 6, and water is supplied through the pipe L30 at the tower bottom of the second absorption tower 7, and the water stored at the tower bottom is The circulation pump P6 is driven to spray from the top of the tower through the spray pipe L31. Between the first absorption tower 6 and the second absorption tower 7, there is provided a pipe L32 that guides the uncondensed ammonia-containing vapor in the first absorption tower 6 to the top of the second absorption tower 7, and causes the second absorption tower The condensed water in the tower 7 is returned to the pipe L33 of the first absorption tower 6 . In addition, an exhaust pipe L34 for exhausting the vapor from which the ammonia has been removed is provided at the top of the second absorption tower 7 .

1 to 3, L40 is a cooling water supply pipe, and L41 is a cooling water supply pipe. The water supply pipe L40 is branched, and L21 is a pipe branched from the cooling water supply pipe L40. The cooling water supply pipe L40 is provided with a heat exchanger H5, the pipe L41 is provided with a heat exchanger H3, and the pipe L21 is provided with a heat exchanger H5. There is heat exchanger H4.

Next, the processing operation of the ammonia recovery device 1 having the above-described structure will be described. The distillation column 2 is steam stripped by blowing heating steam. That is, in the distillation column 2, the raw liquid is brought into contact with heating water vapor, and ammonia is separated from the raw liquid and gasified, and is discharged from the top of the tower as ammonia-containing vapor, and low-concentration ammonia (for example, 30 ppm of ammonia) has been removed from the raw liquid. hereinafter) is stored in the bottom of the tower as treated water.

The ammonia-containing vapor discharged from the top of the distillation tower 2 is guided to the manifold 16B through the vapor supply pipe L10, and circulates in the heat transfer pipe group 15, whereby the circulating liquid ( Water) evaporates on the surface of the heat transfer pipe group 15 to generate water vapor. This water vapor is supplied to the vapor compressors 18 and 19 . On the other hand, the condensed water (low-concentration ammonia water) flowing through the heat transfer pipe group 15 and condensed is stored in the manifold 16A, and is returned to the top of the distillation column 2 through the pipe L11 as a reflux liquid, and the remaining The vapor (ammonia-containing vapor after concentration) is supplied to the concentration tower 5 through the pipe L12.

In the steam compressors 18 and 19, the supplied water vapor is compressed and raised in temperature, and fed into the bottom of the distillation column 2 as heating water vapor. Thereby, the heating steam supplied from the heating steam supply pipe L3 can be reduced, and energy saving can be achieved.

On the other hand, in the concentration tower 5, the opening degree of the control valve V1 is controlled according to the detection result of the temperature sensor T, thereby adjusting the passage through the heat exchanger. The flow rate of cooling water for H4. Thereby, the retentate (condensate) cooled to a predetermined temperature is sprayed from the top of the concentration tower 5 to partially condense the ammonia-containing vapor, thereby generating a predetermined high concentration (for example, 20 wt% or more) of the ammonia-containing vapor. . In addition, all the condensate is returned to the top of the distillation column 2 as a reflux liquid. As described above, the concentration tower 5 is configured to take in the ammonia-containing vapor partially condensed by the evaporator 3, remove moisture to further condense the ammonia-containing vapor, and thereby concentrate the vapor-containing ammonia to a predetermined level only by the evaporator 3. In contrast to a structure having a high concentration (for example, 20 wt % or more), the load on the vapor compressors 18 and 19 can be prevented from becoming too large. As a result, energy saving can be achieved, and a high concentration (for example, 20 wt % or more) of ammonia-containing vapor can be generated.

Next, in the first absorption tower 6, the stored liquid at the bottom of the tower is sprayed from the top of the tower through the spray pipe L23, whereby the ammonia-containing vapor guided from the concentration tower 5 through the pipe L24 is condensed to generate a vapor containing ammonia. Ammonia recovery water with high concentration of ammonia (recycled ammonia water). In the second absorption tower 7, the uncondensed ammonia gas remaining in a small amount in the first absorption tower 6 is guided through the pipe L32, and the water supplied from the outside of the system is sprayed from the top of the tower through the spray pipe L31. , thereby absorbing uncondensed ammonia. The ammonia-absorbed water is the condensate returned to the first absorption tower 6 . As a result, the uncondensed ammonia gas is prevented from being discharged to the outside. In addition, the gas from which ammonia has been removed is exhausted from the exhaust pipe L34.

(something else)

(1) In the above-described embodiment, the structure in which "water" is supplied to the evaporator 3 or the second absorption tower 7 is described, but the "water" can be specifically applied to pure water, soft water, ion-exchanged water, or the like.

(2) For reference, in the case of a structure in which the vapor of the distillation column is directly compressed to be used as a heat source of the distillation column (for example, Patent Document 1, etc.), the vapor of the distillation column is directly compressed, and there is a possibility that there are substances contained in the distillation column. Doubt of causing corrosion, or the possibility of corrosion or leakage of the seal. On the other hand, in the case of the structure in which the water is evaporated by the evaporator and used directly in the distillation tower as in the present invention, since the vapor (steam) directly used in the distillation tower does not contain substances, it is possible to prevent substances from being contained. the occurrence of corrosion or leakage.

[Industrial Availability]

The present invention is applicable to a recovery apparatus and recovery method for separating and recovering low-boiling substances from waste water containing low-boiling substances such as ammonia.

1: Ammonia recovery unit

2: Distillation tower

3: Evaporator

4: Compression device

5: Concentration tower

6: The first absorption tower

7: The second absorption tower

10: Vapor Ejector

11: Heat recovery tank

12: Evaporation tank

13: Sprayer

17: Reservoir

18, 19: Vapor compressor

Claims (6)

A low-boiling substance recovery device, characterized in that it has: The distillation column is to contact the stock solution containing low-boiling substances with heating steam, and separate and gasify the low-boiling substances from the above-mentioned stock solution and discharge them from the top of the tower as the steam containing low-boiling substances, and remove the excess from the stock solution. Treated water with low boiling point substances is stored at the bottom of the tower; The evaporator is to perform heat exchange between the vapor containing the low-boiling substance discharged from the top of the distillation column and water, thereby partially condensing the vapor containing the low-boiling substance and condensing the vapor containing the low-boiling substance , and the aforementioned water is evaporated and discharged as water vapor; The compression device compresses and warms the water vapor discharged from the evaporator, and guides the compressed and warmed water vapor to the distillation column, and utilizes it as the heating water vapor used in the distillation column; and The preheater is provided in the middle of the discharge line for discharging the treated water stored at the bottom of the distillation column to the outside, and heats the water used in the evaporator by exchanging heat with the treated water in advance. The low-boiling substance recovery apparatus according to claim 1, further comprising a concentration tower that takes in the vapor containing the low-boiling point substance partially condensed in the evaporator, cools the vapor, and removes moisture to remove the low-boiling point substance. The vapors of the boiling substances are further concentrated. The low-boiling substance recovery device according to claim 1 or 2, wherein the compression device is configured by connecting a plurality of vapor compressors in parallel. The apparatus for recovering a low-boiling substance according to any one of claims 1 to 3, wherein the low-boiling substance is ammonia. A method for recovering low boiling point substances, characterized in that it has: In the first process, heating steam is blown into the distillation column, the raw liquid containing low-boiling substances is brought into contact with the heating steam, and the low-boiling substances are separated and gasified from the raw liquid, and the low-boiling substances are obtained as steam containing low-boiling substances. The top of the distillation column is discharged, and the treated water from which the low boiling point substances are removed from the stock solution is stored at the bottom of the distillation column; The second step is to partially condense the vapor containing the low-boiling point substance by partially condensing the vapor containing the low-boiling point substance and making the vapor containing the low-boiling point substance discharged from the top of the distillation column to exchange heat with water. The vapor of the substance is concentrated and the aforementioned water is evaporated and discharged as water vapor; and The third step is to compress and heat up the steam discharged from the evaporator in a compression device, and guide the compressed and heated steam to the distillation column, and use it as the heating steam used in the distillation column. to take advantage of, The water used in the evaporator is previously heat-exchanged with the treated water by a preheater provided in the middle of the discharge line for discharging the treated water stored at the bottom of the distillation column to the outside. to heat. The method for recovering low boiling point substances as described in claim 5, further comprising: The fourth process is after the condensation tower is partially condensed in the aforementioned evaporator The vapor containing the low boiling point substance is taken in, and the vapor containing the low boiling point substance is further concentrated by cooling the vapor and removing moisture.

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