TWI732870B - Recovery device and recovery method for low boiling point substances - Google Patents

Abstract

Provided is a low-boiling point material recovery device and recovery method, which can recover low-boiling point materials at a high concentration, and seeks to save energy.

The ammonia recovery device (1) is equipped with: a distillation tower (2), which is blown with heated water vapor for vapor stripping; an evaporator (3), is used to make the ammonia discharged from the top of the distillation tower (2) The steam and water exchange heat 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 as heating water vapor to the distillation tower (2); the concentration tower (5) ) Is to take in the ammonia-containing vapor concentrated 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, 20wt% or more); the first absorption tower (6) , The ammonia-containing vapor from the concentration tower (5) absorbs moisture to generate a predetermined concentration of recovered ammonia; and the second absorption tower (7) prevents the uncondensed ammonia-containing vapor in the first absorption tower from being discharged to the outside.

Description

Recovery device and recovery method for low boiling point substances

The present invention relates to a recovery device and a 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 device using this vapor stripping method is equipped with a distillation tower for vapor stripping. The ammonia-containing vapor discharged from the top of the distillation tower is partially condensed by a condenser, and the condensed water is used as reflux liquid Back to the top of the distillation tower, the remaining concentrated ammonia vapor is fed to the absorption tower to be absorbed by water and taken out as recycled ammonia.

However, the steam stripping method used in this ammonia recovery device is a method of blowing steam directly into the bottom of the distillation column. A large amount of steam is used, so the operating cost is high, and the reduction of the processing cost is pursued. On the other hand, in this method, almost the same amount of water vapor containing ammonia as the injected water vapor is generated, but in order to use this as the reflux liquid to the top of the distillation column and to recover the ammonia liquid, it is necessary to use Cooling is performed by a heat exchanger (condenser) installed at the top of the tower, which consumes energy.

In order to solve the above-mentioned problems, proposals have been made to compress the vapor discharged from the top of the distillation column by a vapor compressor and recover the heat by a reboiler to reduce the amount of water vapor (see Patent Document 1 below). And the proposal is: for the condenser that partially condenses the ammonia-containing vapor discharged from the top of the distillation column, supply make-up water, make the make-up water and the ammonia-containing vapor heat exchange and evaporate, and guide it to the vapor compressor for compression , The structure is heated to become water vapor to be reused (refer to Patent Document 2 below).

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2002-28637 A

[Patent Document 2] JP 2004-114029 A

The conventional examples disclosed in the above-mentioned Patent Documents 1 and 2 effectively utilize the heat of the ammonia-containing vapor discharged from the top of the distillation column 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 are equivalent to the evaporator in this case), and a vapor compressor, When it is desired to recover high-concentration ammonia of, for example, 20 wt% or more, the following problems arise. That is, when it is desired to only rely on the heat exchanger (equivalent to the evaporator in this case) to increase the concentration to a high concentration, the temperature difference between the inlet and outlet of the ammonia-containing vapor of the heat exchanger will become larger, and the load of the vapor compressor will become If it is too large, it will violate the energy saving requirement due to the use of the vapor compressor. In addition, the above-mentioned problem is not limited to ammonia, and can be expanded to be common to recovery devices containing low-boiling substances.

Therefore, there is a demand for a low-boiling substance recovery device capable of recovering a higher concentration of ammonia than before, and achieving energy saving.

The present invention is contemplated in view of the above-mentioned problems, and its purpose is to provide a low-boiling-point substance recovery device and recovery method, which can recover low-boiling-point substances at a high concentration and achieve energy saving.

In order to achieve the above-mentioned object, the present invention is a low-boiling substance recovery device, which is characterized by including a distillation column for contacting a raw liquid containing a low-boiling substance with heating water vapor to separate the low-boiling substance from the raw liquid and It is gasified and discharged from the top of the tower as a vapor containing low-boiling substances, and the treated water from which low-boiling substances has been removed from the raw liquid is stored at the bottom of the tower; the evaporator is the low-boiling substance discharged from the top of the aforementioned distillation tower. The vapor of the boiling point substance exchanges heat with water, thereby partially condensing the vapor containing the low boiling point substance to condense the vapor containing the low boiling point substance, and evaporating the water to be discharged as water vapor; the compression device is The steam discharged from the evaporator is compressed and heated, and the compressed and heated steam is guided to the distillation tower to be used as heating water vapor used in the distillation tower; and the concentration tower is The vapor containing the low-boiling substance after being partially condensed in the evaporator is taken in, and the vapor is cooled and moisture is removed to further concentrate the vapor containing the low-boiling substance.

According to the above structure, an evaporator and a concentration tower arranged after the evaporator are installed, so that the ammonia-containing vapor discharged from the distillation tower can be concentrated in two stages of the evaporator and the concentration tower to produce a predetermined high concentration (for example, 20wt% or more) of steam containing low-boiling substances. By the above-mentioned structure, compared with the structure which only relies on the evaporator to concentrate to a predetermined high concentration (for example, 20wt% or more), the load of the compression device can be prevented from becoming too large. As a result, it is possible to obtain a recovery device that can achieve energy saving and can generate high-concentration (for example, 20 wt% or more) low-boiling-point substance-containing vapor.

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

As "water", it can be applied to pure water, soft water, ion exchange water, etc.

According to an embodiment of the present invention, the above-mentioned low-boiling substance recovery device is provided with a preheater, which is provided in the middle of a discharge line for discharging the treated water stored in the bottom of the distillation column to the outside, and evaporates the The water used in the vessel is heated by heat exchange with the aforementioned treated water in advance.

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

Another embodiment of the present invention is the above-mentioned low-boiling substance recovery device, which is provided with: a heat exchanger, which is provided in a circulation line that guides the retentate stored at the bottom of the concentration tower to the top of the tower On the way, the above-mentioned retentate flowing in the circulation pipeline and the cooling water are heat-exchanged to cool the retentate; the temperature sensor detects that the above-mentioned concentration tower The temperature of the liquid stored at the bottom of the tower; and the control valve, which adjusts the flow rate of the cooling water passing through the heat exchanger in response to the detection result of the temperature sensor.

According to the above structure, 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. With this, the retentate (condensate containing low-boiling substance vapor) stored in the bottom of the concentration tower is cooled to a predetermined temperature and sprayed, thereby generating a predetermined high concentration (for example, 20wt% or more) of ammonia-containing vapor .

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

In order to achieve the above-mentioned object, the present invention is also a method for recovering low-boiling substances. It is characterized by having: the first step is to blow heating water vapor into the distillation column to bring the raw liquid containing the low-boiling substances into contact with the heating water vapor. The low-boiling substance is separated and gasified from the aforementioned raw liquid to be discharged from the top of the distillation tower as a vapor containing low-boiling substances, and the treated water from which the low-boiling substance is removed from the raw liquid is stored at the bottom of the distillation tower; The second step is to exchange heat between the vapor containing the low-boiling substance and water discharged from the top of the distillation tower, thereby partially condensing the vapor containing the low-boiling substance to make the vapor containing the low-boiling substance Concentrate and evaporate the aforementioned water to be discharged as water vapor; the third process is to compress and increase the water vapor discharged from the aforementioned evaporator Temperature, and guide the compressed and heated water vapor to the aforementioned distillation tower, and use it as the heating water vapor used in the distillation tower; and the fourth step is to partially condense the vapor contained in the aforementioned evaporator with low content The vapor of the boiling point substance is taken in, the vapor is cooled and the moisture is removed to further concentrate the vapor containing the low boiling point substance.

According to the above-mentioned structure, a method for recovering low-boiling-point substances in a high concentration and achieving energy saving is constructed.

According to the present invention, low boiling point substances can be recovered in 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 device related to the embodiment.

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

Figure 3 is an enlarged view of the vicinity of the enrichment tower.

Hereinafter, the present invention will be described in detail based on embodiments. In addition, in the following embodiment, as a low boiling point substance recovery device, an ammonia recovery device that uses ammonia-containing waste water as a raw liquid and separates, removes and recovers ammonia from the ammonia-containing waste water will be described as an example. As the low boiling point substance, in addition to ammonia, it is also applicable to alcohols such as methanol, ketones such as acetone, and esters such as methyl acetate.

(Implementation form)

Fig. 1 is an overall configuration diagram of an ammonia recovery device related to the embodiment. The ammonia recovery device (corresponding to the low-boiling substance recovery device of the present invention) 1 is equipped with: a distillation tower 2, which is blown with heated water vapor for vapor stripping; and an evaporator 3, is installed from the top of the distillation tower 2 The discharged ammonia 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 as heating water vapor to the distillation tower 2; the concentration tower 5 The ammonia-containing vapor concentrated in the evaporator 3 is taken in to cool the vapor and remove moisture to increase the concentration of the ammonia-containing vapor to a high concentration (for example, 20 wt% or more); 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, when describing the outline characteristics of the ammonia recovery device 1 of the first embodiment, it is configured to install an evaporator 3 and a concentration tower 5 arranged after the evaporator 3 to discharge the content from the distillation tower 2 Ammonia vapor can be recovered with a predetermined high concentration (for example, 20 wt% or more) ammonia water by the two-stage concentration of the evaporator 3 and the concentration tower 5.

Hereinafter, the specific structure of the ammonia recovery device 1 will be described in conjunction with the above-mentioned characteristic structure. The distillation column 2 may use a multi-stage one, and it is not limited to this, and a non-multi-stage one may also be used. That is, in the distillation column 2, a plate column or a packed column can be used. At the top of the distillation column 2, the raw liquid (ammonia-containing waste water) is supplied through the raw liquid supply pipe L1. In addition, the pH of the stock solution may be adjusted in advance.

At the bottom of the distillation column 2, the heating steam from the steam ejector 10 is supplied through the heating steam supply pipe L3. The bottom of the distillation column 2 is connected to the heat recovery tank 11 through a pipe L4, and the retentate (low-concentration ammonia water) at the bottom of the tower is supplied to the heat recovery tank 11 through the pipe L2. The vapor ejector 10 is a vapor compression means for suction and compression of vapor. On the vapor suction side 10a, there is connected: a vapor supply pipe L5 and a vapor supply pipe L5 for circulating vapor supplied from a high-pressure vapor source (not shown) such as a boiler The 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 and sucked and compressed by the vapor ejector 10, mixed with the vapor from the vapor supply pipe L5, and blown into the distillation column 2 as heating vapor The 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, and heat is recovered.

In addition, to the bottom of the heat recovery tank 11, a discharge pipe L7 for discharging treated water (for example, low-concentration ammonia water of 30 ppm or less) is connected, and the discharge pipe L7 is provided with a treated water discharge pump P1, and three heat exchanges器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 that heats the raw liquid by exchanging heat with the treated 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. The treated water cooled by the heat exchanger H3 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 treated water discharge pump P1 above the discharge pipe L7, and are installed in the following order. That is, in the discharge pipe L7, the heat exchanger H1 is installed on the upstream side of the heat exchanger H2. By installing in the above order, the amount of heat imparted by the treated water to the water can be maximized, so that energy saving of the evaporator 3 that heats 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. In addition, it is not limited to the horizontal tube type, and an evaporation can, for example, a thin film flow down (vertical tube) type or the like may be used. As shown in FIG. 2, the indirect heater 14 includes a heat transfer tube group 15 composed of one or a plurality of horizontal heat transfer tubes, and a pair of left and right multi-manifolds 16A, 16B. In addition, the bottom of the evaporation tank 12 serves as a storage portion 17 to store the water supplied through the pipe L8. The storage liquid (water) of the storage section 17 is supplied to the sprayer 13 provided in the upper part of the evaporation tank 12 by the circulating pump P2 through the pipe L9, and sprayed from the sprayer 13 toward the outer surface of the heat transfer tube group 15 , The structure that flows down to the storage part 17 in the lower part of the evaporation tank 12 to circulate.

The multi-manifold 16B is connected to the vapor supply pipe L10 through the top of the distillation tower 2, and the top vapor (ammonia-containing vapor) discharged from the top of the distillation tower 2 is guided through the vapor supply pipe L10. The manifold 16B circulates in the heat transfer tube group 15. Here, the evaporator 3 has a pressure lower than the pressure of the overhead vapor. Therefore, the circulating fluid (water) sprayed by the sprayer 13 evaporates as a thin film on the surface of the heat transfer tube group 15 to generate water vapor. This steam is supplied to the compression device 4. Here, the principle of vaporizing water in the evaporator 3 will be explained in more detail. In the evaporator 3, the overhead vapor (inside the heat transfer pipe) used as the heating source causes the heated water to exist outside the heat transfer pipe. Is lower, so the water will evaporate. In addition, this pressure difference is generated by the compression device 4 (specifically, the vapor compressors 18 and 19). This is because the outside of the heat pipe of the evaporator connected to the suction side of the compression device 4 is lower, and the pressure of even the top vapor in the distillation column 2 connected to the discharge side of the compression device 4 is higher. In addition, the steam supplied from the steam ejector 10 also increases the pressure in the distillation column 2 and becomes a factor for evaporating the water in the evaporator 3.

In addition, the condensed water (low-concentration ammonia water) circulating in the heat transfer tube group 15 is stored in the multi-manifold 16A, driven by the condensate pump P3, passes through the pipe L11, and returns to the distillation column 2 as a reflux liquid. The top of the tower. The other remaining vapor (concentrated ammonia-containing vapor) is discharged to the top of the concentration tower 5 through the pipe L12.

The compression device 4 is provided with two vapor compressors 18 and 19, and the vapor compressors 18 and 19 are configured by connecting the bottom of the distillation column 2 and the upper part of the evaporation tank 10 side by side. That is, the inlet side 18a of the vapor compressor 18 is connected to the upper part of the evaporation tank 12 through a pipe L15, and the outlet side 18b of the vapor compressor 18 is connected to the bottom of the distillation column 2 through a pipe L15. 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 branched from the pipe L5, and the outlet side 19b of the vapor compressor 19 is connected to the bottom of the distillation column 2 through a pipe L18.

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

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

In addition, the spray pipe L20 is branched on the way as shown in FIG. 2, and the branch pipe L22 of the branch is connected to the top of the distillation column 2. A control valve V2 is provided on the way of the sub-manifold L22. In addition, as shown in FIG. 2, the concentration tower 5 is provided with a liquid level sensor S1 for detecting the liquid level of the stored liquid. The liquid level sensor S has a level switch S1a for detecting the upper limit setting level and a level switch S1b for detecting the lower limit setting level. With the liquid level sensor S1, the opening degree of the control valve V2 is controlled to maintain the retentate at a predetermined liquid level, and the retentate exceeding the predetermined liquid level is refluxed to the top of the distillation tower 2.

The first absorption tower 6 is composed of the same spray scrubber as the concentration tower 5, and the spray pipe L23 that circulates the retentate of the first absorption tower 6 is provided with a circulation pump P5 and a heat exchanger H5. In the heat exchanger H5, the storage liquid flowing in the spray tube L23 is heat-exchanged with the cooling water, and the storage liquid is cooled. The cooled retentate is sprayed through the tube L24 to the high-concentration (for example, 20wt% or more) ammonia-containing vapor taken in from the concentration tower 5, thereby condensing and recovering the ammonia-containing vapor to produce recycled ammonia . 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 branch pipe L25 that has been branched.

The second absorption tower 7 is composed of the same spray scrubber as the first absorption tower 6. At the bottom of the second absorption tower 7, water is supplied through the pipe L30, and the water stored at the bottom of the tower 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, so that the second absorption tower The condensed water in the tower 7 returns to the pipe L33 of the first absorption tower 6. In addition, at the top of the second absorption tower 7, an exhaust pipe L34 for exhausting the ammonia-removed vapor is provided.

In addition, in Figures 1 to 3, L40 is a cooling water supply pipe, L41 is a pipe branched from the cooling water supply pipe L40, and L21 is a pipe branched from the cooling water supply pipe L40. The cooling water supply pipe L40 is provided with heat In the exchanger H5, a heat exchanger H2 is provided on the pipe L41, and a heat exchanger H4 is provided on the pipe L21.

Next, the processing operation of the ammonia recovery device 1 configured as described above will be described. In the distillation tower 2, heated water vapor is blown in to perform vapor stripping. That is, in the distillation tower 2, the raw liquid is brought into contact with heating water vapor, and ammonia is separated from the raw liquid and gasified, and discharged from the top of the tower as ammonia-containing vapor. The low-concentration ammonia water (for example, 30 ppm) is removed from the raw liquid. The following) is stored at 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 multi-manifold 16B through the vapor supply pipe L10, and circulates in the heat transfer pipe group 15, thereby causing the circulating liquid sprayed by the sprayer 13 ( Water) evaporates as a thin film on the surface of the heat transfer tube group 15 to generate water vapor. This steam is supplied to the steam compressors 18 and 19. On the other hand, the condensed water (low-concentration ammonia water) circulating in the heat transfer tube group 15 is stored in the multi-manifold 16A, and returns to the top of the distillation column 2 as a reflux liquid through the pipe L11, and the remaining remaining The vapor (concentrated ammonia-containing vapor) is supplied to the concentration tower 5 through the pipe L12.

In the vapor compressors 18 and 19, the supplied water vapor is compressed and increased in temperature, and is fed to the bottom of the distillation column 2 as heating water vapor. Thereby, the heating water vapor 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 in accordance with the detection result of the temperature sensor T, thereby adjusting the flow rate of the cooling water passing through the heat exchanger H4. In this way, 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, 20wt% or more) of ammonia-containing vapor . In addition, all the condensate is returned to the top of the distillation column 2 as reflux liquid. As described above, the concentration tower 5 is configured to take in the ammonia-containing vapor partially condensed by the evaporator 3, and remove the water to further condense the ammonia-containing vapor. This is different from the evaporator 3 alone to concentrate the ammonia-containing vapor. In contrast, the structure with a high concentration (for example, 20 wt% or more) can prevent the load of the vapor compressors 18 and 19 from becoming excessive. As a result, energy saving can be achieved, and high-concentration (for example, 20 wt% or more) ammonia-containing vapor can be generated.

Next, the first absorption tower 6 is configured such that the stored liquid at the bottom of the tower is sprayed from the top of the tower through the spray tube L23, thereby condensing the ammonia-containing vapor guided from the concentration tower 5 through the tube L24 to produce Ammonia recovery water with high concentration of ammonia (recovered ammonia water). The second absorption tower 7 is configured such that a small amount of uncondensed ammonia gas remaining in the first absorption tower 6 is guided through the pipe L32, and water supplied from outside the system is sprayed from the top of the tower through the spray pipe L31 , Thereby absorbing uncondensed ammonia gas. The water that has absorbed ammonia 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 the ammonia has been removed is exhausted from the exhaust pipe L34.

(something else)

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

(2) For reference, in the case of a structure in which the vapor of the distillation column is directly compressed and used as the heat source of the distillation column (for example, Patent Document 1, etc.), the vapor of the distillation column is directly compressed, which may contain substances. There is a concern about corrosion, or the possibility of corrosion or leakage of the sealing part. In contrast, as in the present invention, when the evaporator evaporates water and directly uses it in the structure of the distillation tower, since the vapor (water vapor) directly used in the distillation tower does not contain substances, it is possible to prevent the content of substances. The occurrence of corrosion or leakage.

[Industrial availability]

The present invention is applicable to a recovery device 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‧‧‧Steam ejector

11‧‧‧Heat recovery tank

12‧‧‧Evaporation tank

13‧‧‧Atomizer

17‧‧‧Reservation Department

18.19‧‧‧Vapor compressor

Claims (4)

A low-boiling substance recovery device, which is characterized by comprising: a distillation column that contacts a raw liquid containing a low-boiling substance with heating water vapor, and separates and gasifies the low-boiling substance from the raw liquid as a low-boiling substance-containing The steam is discharged from the top of the tower, and the treated water with low boiling point substances removed from the raw liquid is stored at the bottom of the tower; the evaporator is to exchange heat between the steam containing low boiling point substances discharged from the top of the distillation tower and the water. By this, the vapor containing the low boiling point substance is partially condensed to condense the vapor containing the low boiling point substance, and the water is evaporated and discharged as water vapor; the compression device is the water discharged from the evaporator The vapor is compressed and heated, and the compressed and heated water vapor is guided to the aforementioned distillation tower to be used as heating water vapor used in the distillation tower; and the concentration tower is partially condensed in the aforementioned evaporator The vapor containing the low-boiling substance is taken in, the vapor is cooled and the moisture is removed to further condense the vapor containing the low-boiling substance; the heat exchanger is set up to guide the retentate stored in the bottom of the aforementioned concentration tower to On the way of the circulation pipeline at the top of the tower, the above-mentioned retentate flowing in the circulation pipeline is heat exchanged with cooling water to cool the retentate; the temperature sensor detects the retentate stored at the bottom of the aforementioned concentration tower The temperature; and the control valve are based on the detection result of the aforementioned temperature sensor to adjust the flow of cooling water passing through the aforementioned heat exchanger. The low boiling point substance recovery device described in claim 1, wherein the compression device is configured by connecting a plurality of vapor compressors in parallel. The device for recovering a low boiling point substance as described in claim 1 or 2, wherein the low boiling point substance is ammonia. A method for recovering low-boiling substances, which is characterized in that: the first step is to blow heating water vapor into the distillation tower, contact the raw liquid containing low-boiling substances with the heating water vapor, and remove the low-boiling substances from the raw liquid. It is separated and gasified to be discharged from the top of the distillation tower as vapor containing low-boiling substances, and the treated water from which the low-boiling substances are removed from the raw liquid is stored at the bottom of the distillation tower; the second step is to distill from the aforementioned distillation The vapor containing the low-boiling substance discharged from the top of the tower exchanges heat with water in the evaporator, whereby the vapor containing the low-boiling substance is partially condensed to condense the vapor containing the low-boiling substance, and the water Evaporate and discharge as water vapor; the third step is to compress the water vapor discharged from the evaporator in the compression device to increase the temperature, and guide the compressed and heated water vapor to the distillation tower as a The heating water vapor used in the distillation tower is used; and the fourth step is to take in the vapor containing low boiling point substances after being partially condensed in the aforementioned evaporator in the concentration tower, cool the vapor and remove moisture to control the low boiling point The vapor of the substance is further concentrated, A heat exchanger is installed in the middle of the circulation line that guides the retentate stored in the bottom of the concentration tower to the top of the tower to exchange heat between the retentate flowing in the recirculation line and the cooling water. , And cool the retentate; use a temperature sensor to detect the temperature of the retentate stored at the bottom of the concentration tower; and according to the detection result of the temperature sensor, adjust the control valve to pass through the heat exchanger The flow of cooling water.

Images