JPH09131582A - Separating and concentrating method of volatile material in underwater and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove a volatile component with reduced energy consumption by transferring a part of a liquid in a separating and concentrating process to the preceding stage at the time of introducing a volatile material-containing water to an evaporation process, partially condensing a gas containing steam and the volatile material under a reduced pressure and condensing an uncondensed part. SOLUTION: A raw water 1 containing the volatile material such as ammonia is introduced into the evaporation process 3 through a heat exchanger 2, to be evaporated under a reduced pressure and condensed and distilled under a reduced pressure in the separating and concentrating process 4. Next, the water is passed through a pressure reducing device 5 and condensed in a condensing process 6. The volatile component is condensed in the condensate 7 and is discharged as a concentrated water 8. The quantity of a inflow steam exceeds the quantity of an outflow steam in the separating and concentrating process 4 to increase the quantity of the liquid and then the excess water is introduced into the evaporation process 3 as a return water 9. The evaporation process outflow water 10 is passed through the heat exchanger 2 to give heat to the raw water 1 and is discharged or reutilized after treating a non-volatile component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to separation and concentration of volatile substances in water, and more particularly, to volatilization of waste water containing volatile substances such as organic solvents, alcohols, organic chlorine compounds, ammonia and hydrogen chloride. The present invention relates to a method for separating and concentrating a substance and its equipment.

[0002]

2. Description of the Related Art Direct distillation by heating, steam distillation, and vacuum distillation are known as methods for fractionally distilling low-boiling volatile components from a mixture of a plurality of volatile components. When removing low-concentration volatile components from water, for example, chlorine-based organic compounds in water,
A method in which ammonia or the like is countercurrently contacted with air or water vapor to be diffused and recovered is applied as one of water purification methods (JP-A-7-31966).

When the volatile component in water is released, the volatile component always evaporates together with water vapor. However, when the vapor pressure of the volatile component is significantly lower than the vapor pressure of water, the volatile component is condensed by condensing the released gas. Even if recovered, the concentration of volatile components in the condensed water does not increase, so its use and treatment are not easy.
In order to increase the concentration of volatile components in the condensed water, repeated distillation (dissipation) is required, which requires a lot of energy and operation. A rectification column is used for separating and concentrating a mixture of relatively high-concentration volatile components.For example, in the method for separating and concentrating volatile components in which a stock solution is injected into the middle part of a multistage rectification column, the concentration ratio of the concentrated liquid is In order to raise the temperature, the vapor in the concentrating section is condensed and recirculated, but since the number of times of recirculation is repeated, a large amount of energy for heating is consumed.

On the other hand, a method using a multi-effect can is generally used as a method for evaporating water containing a non-volatile component and concentrating the non-volatile content. In this method, the liquid of the previous stage is transferred to the next stage, and the liquid of the next stage is heated by the steam generated in the previous stage, and the energy efficiency improves as the number of cans increases. However, in this method, the vapor is condensed when it is used for heating and is discharged to the outside of the system.Therefore, even if the volatile component moves to the condensed water due to evaporation, it is naturally possible to increase the concentration. There is a limit. Further, in such a device configuration, even if the evaporative gas in the final evaporating tube is condensed in the condenser, the volatile component in the condensed water evaporates under reduced pressure because the vacuum pump (pressure reducing device) follows. Therefore, it is impossible to obtain a concentrated solution of volatile components. A multi-stage flash evaporation method has been put into practical use as a method for efficiently obtaining condensed water, but this method also cannot concentrate volatile components in condensed water.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, the present invention provides water purified with a relatively low concentration of volatile component-containing water by efficiently removing volatile components and efficiently purifying the water. It is an object of the present invention to provide a method for separating and concentrating volatile substances in water, which is capable of concentrating components and facilitating their use and treatment, and equipment therefor.

[0006]

In order to solve the above-mentioned problems, in the present invention, volatile substance-containing water is introduced into an evaporation step to separate water vapor generated under reduced pressure and a gas containing volatile substances. After partially condensing under reduced pressure in the concentration step, in the method for separating and concentrating volatile substances in which the uncondensed portion is condensed in the next condensation step, part of the liquid in the separation and concentration step was transferred to the previous step. It is a thing. In the method for separating and concentrating, it is preferable that the separating and concentrating step is provided in multiple stages, and the inner solution of the step is transferred to the preceding separating and concentrating step.
The heat source in the first step is preferably supplied from the second step using a heat pump.

Further, in the present invention, in a facility for separating and concentrating volatile substances in volatile substance-containing water, an evaporator for evaporating the volatile substance-containing water and a separator for partially condensing the vaporized gas from the evaporator. A concentrating device, a condensing device for condensing uncondensed gas from the separating and concentrating device, and a decompression device are provided, and a gas passage for sequentially connecting these devices and a liquid inside the latter device are transferred to the former device. And a transfer means. In the separation-concentration facility, the separation-concentration device and the condensing device are preferably provided with an opening of a gas passage for the inflowing gas below the liquid surface of the device.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, the concentration of volatile components in vapor is increased by condensing the volatile components evaporated in the evaporation process in the next separation and concentration process and re-evaporating. In the separation / concentration step, the latent heat of vaporization of the outflow vapor is directly and effectively utilized for the condensation of the inflow vapor.
It is also possible to indirectly use the heat of condensation as a heat source for evaporation. In the present invention, it is preferable to interpose a decompression device between the evaporation step and the condensation step, which allows the volatile components to be easily concentrated. As in the prior art, in the method involving the condensation process between the evaporation process and the decompression device, since the condensed water in the condensation process exists under reduced pressure, the volatile components concentrated in the condensed water are re-evaporated to reduce the concentrated concentration. Difficult to raise.

Next, an example of the present invention will be described in detail with reference to the drawings. 1 and 2 show an overall configuration diagram of the flow of the present invention, and FIGS. 3 and 4 show partially enlarged views of the separation and concentration step (apparatus). In FIG. 1, raw water 1 containing, for example, ammonia as a volatile substance is heated through a heat exchanger 2 and introduced into an evaporation step 3, and is evaporated under reduced pressure under reduced pressure. Is introduced into the separation / concentration step 4 having a lower temperature, is condensed and distilled under reduced pressure, and is condensed in the condensation step 6 whose temperature is lower than that of the separation / concentration step 4 via the decompression device 5. Volatile components are concentrated in the condensed water 7, and the condensed water 8
Be shipped as. In the separation / concentration step 4, the amount of inflow vapor becomes larger than the amount of outflow vapor and the amount of liquid increases, so that the amount is introduced to the evaporation step 3 as return water 9. The evaporative process runoff water 10 supplies heat to the raw water 1 via the heat exchanger 2, and then the non-volatile components are treated and discharged or reused. The evaporation step 3 and the separation / concentration step 4 are decompressed to atmospheric pressure or less by the decompression device 5.

Heat is supplied to the evaporation step 3 and the separation / concentration step 4 by the heat pumps 11 and 12 from the next step in order to prevent the temperature from lowering due to the latent heat of evaporation. That is, the evaporation process 3 is performed from the separation concentration process 4 to the heat pump 11
Although heat is supplied by the heat, the temperature of the separation / concentration step 4 is reduced by that much, so that the inflowing steam can be smoothly condensed. On the other hand, in the separation / concentration step 4 as well, in order to prevent a temperature decrease due to evaporation, the heat of condensation of the condensation step 6 is transferred to the heat pump 1.
2 moves to separation and concentration step 4. The temperature of the condensation step 6 can thereby be maintained at the temperature required for the condensation of the incoming vapor. The heating in each of the steps 3, 4, and 6 can of course be performed by using a known technique such as steam as another heat source, and a known technique such as cooling water can also be used for cooling, so that an inexpensive and effective heat source or cooling source exists. If so, no heat pump is needed. However, when such a heat source or a cooling source does not exist, it is economically advantageous to use a heat pump capable of simultaneously performing cooling and heating in the system.

In the condensation step 7, a pressure adjusting device 13 for adjusting the internal pressure to the atmospheric pressure is provided, and when the internal pressure becomes lower than a predetermined value, a gas such as air is supplied and when the internal pressure is increased. The internal gas is released via the gas treatment process 14, and the pressure of the condensation process 6 is adjusted. The decompression device 5 may be arranged after the condensing step 6 as shown in FIG. Although not shown, two (plural) pressure reducing devices may be provided in total, one between the separation and concentration step 4 and the condensation step 6 and one after the condensation step 6. In the evaporation step 3, a known evaporator or distillation apparatus such as a single-stage evaporator or a multi-stage distillation column can be used. Separation and concentration step 4
Uses the apparatus shown in FIGS. 3 and 4 for simultaneously performing evaporation and condensation.

In FIG. 3, the inflow steam 17 passes through the perforations of the perforated tube 20 provided below the water surface of the separation / concentration step internal water 19 and contacts the internal water 19 to be condensed. The internal water 19 evaporates under reduced pressure and moves to the condensation step 7 as the outflow steam 18. The heat pump 1
A heating side heat exchanger 21 and a cooling side heat exchanger 22 of the heat pump 11 are provided. After the inflow steam 17 is condensed in the separation and concentration step 4, the condensed water flows out again as the steam 18. FIG. 4 shows a tower type apparatus configuration in the separation and concentration step 4. In FIG. 4, the water 19 in the separation / concentration step is passed through the heat exchanger 23 from the top of the column to the packed bed 24 of the packing material for gas-liquid contact.
Sprayed on. The inflow steam 17 passes through the inside of the tower to be condensed, and again flows out as the steam 18. Ammonia exists in water in a state of equilibrium between a gas body (free ammonia) and ions, but ammonia emitted from water is a gas body. Therefore, in order to increase the existing amount of the gas body, raising the temperature or increasing the pH by adding an alkaline agent is an effective means for increasing the emission efficiency.

[0013]

EXAMPLES Next, examples using the flow and apparatus of FIGS. 1 and 3 will be described. Example 1 Ammonia nitrogen concentration of 1000 m as volatile component-containing water
Ammonia water of g / liter was used to separate and concentrate ammonia under the following apparatus and conditions. As a result, it was possible to reduce the ammoniacal nitrogen of the ammonia water to 340 mg / liter and obtain a concentrated solution of 5.3% ammoniacal nitrogen (53000 mg / liter).

Volume of equipment, Evaporator capacity: 0.70 m ³ , Separation and concentration can capacity: 0.15 m ³ , Operating conditions, Volatile water content: 10 m ³ / day, Concentrated water quantity: 0.0125 m ³ / day, Evaporation cans evaporate water content: 0.5 m ³ / day, separation and concentration can evaporate water content: 0.125 m ³ / day, separation and concentration can outflow water: 0.375 M ³ / day,

Evaporator water temperature: 67 ° C., Separation / concentration evaporator water temperature: 48 ° C., Condenser water temperature: 20 ° C., Heat pump 11 power consumption: 83 kWh / day, Heat pump 12 power consumption: 22 kWh / day, (heat pump water temperature Was detected and controlled on and off) Pressure reducing device: vacuum pump,

[0016]

According to the present invention, the following effects can be obtained. (A) Volatile components in a liquid can be separated and concentrated with a simple device configuration. (B) It is possible to remove harmful volatile components from water,
Moreover, since it can be concentrated to a high concentration, it becomes easy to dispose of it, such as incineration. (C) Since useful volatile components in water can be separated and concentrated, they can be easily reused. (D) Since the concentrated volatile component can be stored in a liquid state, a large-capacity tank like gas is not required for storage, and storage is easy. Therefore, there are few time restrictions on operations such as treatment, disposal, and effective use of concentrated volatile components. (E) Since there is no non-condensable gas in the vapor component other than the trace gas dissolved in the raw water and accompanying it, for example, nitrogen gas, exhaust gas treatment is almost unnecessary.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an example of a flow of the present invention.

FIG. 2 is an overall configuration diagram showing another example of the flow of the present invention.

FIG. 3 is a partially enlarged view of the separation and concentration device used in the present invention.

FIG. 4 is a partially enlarged view of another separation and concentration device used in the present invention.

[Explanation of symbols]

1: Raw water, 2: Heat exchanger, 3: Evaporation step, 4: Separation and concentration step, 5: Decompression device, 6: Condensation step, 7: Condensate, 8:
Concentrated water, 9: Return water, 10: Evaporation process runoff water, 11, 1
2: Heat pump, 13: Pressure adjusting device, 14: Gas treatment process, 17: Inflow steam, 18: Outflow steam, 19: In-process water, 20: Perforated pipe, 21: Heating side heat exchanger, 22: Cooling side heat Exchanger, 23: heat exchanger, 24: packed bed,

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C02F 1/58 C02F 1/58 A H

Claims (5)

[Claims] 1. Introducing water containing volatile substances into the evaporation step,
The gas containing water vapor and volatile substances generated under reduced pressure is partially condensed under reduced pressure in the separation and concentration step, and then the uncondensed component is condensed in the next condensation step. A method for separating and concentrating volatile substances in water, characterized in that a part of the liquid in the concentration step is transferred to the previous step. 2. The method for separating and concentrating volatile substances in water according to claim 1, wherein the separating and concentrating step is provided in multiple stages, and the inner liquid of the latter step is transferred to the former separating and concentrating step. 3. The method for separating and concentrating volatile substances in water according to claim 1 or 2, wherein in the separating and concentrating method, the heat source of the former step is supplied from the latter step by using a heat pump. 4. A facility for separating and concentrating volatile substances in volatile substance-containing water, comprising: an evaporation device for evaporating the volatile substance-containing water; and a separation-concentration device for partially condensing evaporative gas from the evaporation device. A condensing device for condensing the uncondensed gas from the separation concentrating device and a decompression device are provided, a gas passage for sequentially connecting these devices, and a transfer means for transferring the liquid in the latter device to the former device. A facility for separating and concentrating volatile substances in water, which is characterized by having. 5. The separation / concentration device and the condensing device according to claim 4, wherein an opening of a gas passage for the inflowing gas is provided below the liquid surface of the device. Concentration equipment.