JP4389833B2 - Cooling water treatment method and treatment equipment - Google Patents

Description

The present invention relates to a treatment method and treatment equipment for cooling water that is circulated in a cooling system such as metal smelting, iron making, and power generation equipment. More specifically, in the cooling system in which the cooling water is circulated and used, when the cooling water is extracted and replenished with new cooling water, the cooling water in the circulation system holds the extracted cooling water. The present invention relates to a cooling water treatment method and treatment equipment that reduces the burden of waste liquid treatment by reducing evaporation by using heat, and at the same time effectively uses cooling water.

A large amount of cooling water is used in cooling systems such as metal smelting, iron making, and power generation facilities. For example, in metal smelting, high-temperature molten slag discharged from a melting furnace or the like is granulated and recycled (Patent Document 1). Since a large amount of water is used in the water granulation treatment, the cooling water is circulated and reused in the cooling process in order to effectively use water resources and reduce processing costs. In such a cooling system in which cooling water is circulated, in order to suppress contamination and deterioration of the circulating cooling water, a part of the cooling water is extracted and replenished with new cooling water.

For example, in the process of granulating molten slag, contaminants dissolve when the cooling water comes into contact with the molten slag, and the contaminants gradually accumulate every time the cooling water is circulated. The water is extracted out of the system and replenished with new water. Specifically, as shown in FIG. 2, for example, when circulating cooling water of 1500 t / Hr to the water granulation step and continuously granulating about 59 t / Hr of molten slag, circulation use per hour About 3t / Hr of water adheres to the granulated slag every time and is carried out of the system. Further, about 10t / Hr of water is taken out of the system and about 13t / Hr of water is replenished. There is a lot of water.

Moreover, in the conventional water granulation process, the calorie | heat amount of molten slag is discharged | emitted out of the system as it is, and energy is lost wastefully. Specifically, for example, the cooling water that has come into contact with the molten slag has an increased water temperature. Therefore, in order to circulate and use this water as cooling water, it is necessary to lower the water temperature. It is cooling. Although the seawater used for this cooling has risen in water temperature due to heat exchange, it has been discharged into the sea as it is and heat energy has been lost wastefully.

The same is true for metal smelting, iron making, power generation facilities, etc., and when cooling water is circulated, a large amount of cooling water is conventionally discharged outside the system, and water resources and heat energy are lost wastefully. Yes.
JP 2000-34528 A

The present invention solves the above-mentioned problem in the conventional cooling system that circulates and uses cooling water, and reduces the amount of waste liquid by performing the evaporation process by effectively using the amount of heat that the cooling water has. Provided is a cooling water treatment method and treatment equipment that reduces the burden and reduces the amount of makeup water by returning evaporated water to the circulation system.

According to this invention, the processing method of the cooling water which has the following structures, and its processing equipment are provided.
[1] In the cooling system where the water temperature is used circulated to cool the cooling water rises, leading to a vacuum evaporation unit by extracting part of the water temperature up cooling water from the circulation, whereas, water temperature rise is not withdrawn from circulation Led to the heat exchange part of the vacuum evaporation part, utilizing the heat of the cooling water introduced into this heat exchanger, the cooling water of the vacuum evaporation part is vacuum evaporated, the evaporation residue is discharged out of the system, A method for treating cooling water, wherein the steam is cooled and condensed, returned to the circulation system, and reused.
[2] In the above [1], the cooling water is a cooling water for granulating molten slag, a cooling water for a furnace water cooling jacket, a cooling water in a steelmaking rolling process, or a cooling water circulating in a cooling system of a power generation facility A cooling water treatment method to be described.
[3] The molten slag during the granulated processing, a method of recycling a contact with the molten slag cooling water temperature rises as cooling water again to cool water砕用, the water temperature up cooling water one The cooling water whose temperature has risen not to be extracted from the circulation system is led to the heat exchange section of the vacuum evaporation section, and the heat of the cooling water is used to extract the vacuum evaporation section from the circulation system. The cooling water is evaporated in a vacuum and the evaporation residue is discharged out of the system, while the steam is cooled and condensed with natural water such as seawater and returned to the circulation system. The cooling water treatment method according to the above [1], wherein the cooling water is cooled and reused by natural water such as seawater.
[4] The cooling water according to any one of [1] to [3] above, wherein nitrogen gas is introduced into the cooling water extracted from the circulation system and the dissolved gas is driven out of the cooling water, and then the cooling water is vacuum evaporated. Processing method.
[5] The cooling water according to any one of [1] to [4] above, wherein the heat retained in the cooling water in the circulation system that has exchanged heat in the vacuum evaporator is used as a heating source for the waste liquid in another system. Processing method.
[6] Treatment equipment for slag water crushed water, a circulation system for circulating cooling water, a pulverized part for bringing cooling water into contact with molten slag and crushing it, and a cooling water having an increased water temperature in contact with molten slag A vacuum evaporation part that extracts a part of the water from the circulation system and evaporates, a heat exchange part that introduces cooling water whose water temperature has not been extracted from the circulation system and uses it as a heating source for the vacuum evaporation part , It has a condensing part that cools with natural water, a pipe that returns the condensed water to the circulation system, a pipe that discharges evaporation residue outside the system, and a cooling part that cools the cooling water in the circulation system with natural water such as seawater. A slag crushed water treatment facility.
[7] The slag crushed water treatment facility according to the above [6], wherein a gas introduction part that introduces nitrogen gas into the cooling water and drives out the dissolved gas is provided in the cooling water introduction part of the vacuum evaporation part.

In the treatment method of the present invention, when the cooling water is circulated and used, a part of the cooling water extracted from the circulation system is guided to the vacuum evaporation section, and the cooling water not extracted from the circulation system is supplied to the heat exchange section of the vacuum evaporation section. Introducing and evaporating in vacuum using the heat held by the cooling water and discharging the evaporation residue to the outside of the system greatly reduces the amount of discharge and remarkably reduces the burden of waste liquid treatment. Further, since the vapor evaporated in vacuum is cooled and condensed and returned to the circulation system for reuse, the amount of water required for replenishment is greatly reduced. Furthermore, since the heat is held in the cooling water and evaporated in vacuum, the heat energy can be effectively used.

For example, in a treatment system for molten slag granulated water, the treatment method of the present invention extracts a part of the cooling water used for molten slag granulation from the circulation system, evaporates it in vacuum, and discharges the evaporation residue outside the system. As a result, the amount of waste liquid is significantly reduced. In addition, since contaminants mixed into the cooling water from the molten slag remain as residues during vacuum evaporation, the steam can be cooled and condensed and returned to the circulation system, and a large amount of new water must be replenished. Absent. Therefore, effective use of water resources can be achieved. Furthermore, in the treatment method of the present invention, the amount of natural water used for cooling the cooling water and the evaporating water does not increase, and the condensed water is recovered by evaporation, so that highly pure water can be obtained.

In addition, since the treatment method of the present invention performs vacuum evaporation by the amount of heat held in the cooling water whose water temperature has increased due to contact with the molten slag, the thermal energy of the cooling system can be used effectively and the energy cost can be reduced. can do.

The treatment method of the present invention is a cooling process for circulating water cooling jackets of various furnaces such as a melting furnace and a smelting furnace, in addition to the cooling water for granulating molten slag in metal smelting as described above, and a rolling process for iron making. The present invention can be widely applied to cooling water that is circulated and used in the cooling system of this type, or cooling water that circulates in the cooling system of power generation equipment.

Processing method according to the present invention is a cooling system where the water temperature is used circulated to cool the cooling water rises, leading to a vacuum evaporation unit by extracting part of the water temperature up cooling water from the circulation, whereas, from the circulatory system The cooling water whose temperature has not been withdrawn is led to the heat exchange section of the vacuum evaporation section, and the cooling water in the vacuum evaporation section is vacuum evaporated using the heat of the cooling water introduced into the heat exchanger, and the evaporation residue is systemized. It is a cooling water treatment method characterized in that it is discharged outside, the steam is cooled and condensed, returned to the circulation system, and reused.

Hereinafter, the cooling water treatment method of the present invention will be described by taking, as an example, cooling water for granulating molten slag in metal smelting. An outline of the processing method or processing equipment of the present invention is shown in FIG. As shown in the figure, the treatment system of the present invention has a circulation system 40 for circulating and using cooling water, and a granulating unit 10 that crushes molten slag in contact with cooling water, and cooling water for the circulation system. The cooling system 50 is provided in the circulation system 40 to cool the water with natural water such as seawater. For convenience of explanation, seawater and river water are referred to as natural water. Use of natural water is advantageous in reducing the treatment cost.

Processing method system of the present invention, further a water temperature elevated vacuum evaporation section 20 for a part of the coolant evaporated withdrawn from circulation, heat heat source temperature up cooling water does not withdrawn from circulation's Heat exchanging part 21 of the vacuum evaporation part, vacuum pump 24 of the vacuum evaporation part, condensing part 30 for cooling the vacuum evaporated steam with natural water such as sea water, heat exchanging part 31 between steam and sea water provided in the condensing part, steam A conduit 32 for returning condensed water cooled and condensed to the circulation system and a conduit 22 for discharging the evaporation residue outside the system are provided in the circulation system 40. Further, a cooling water supply pipe 60 is connected to the circulation system 40. Preferably, a gas introduction part 23 for introducing a nitrogen gas into the cooling water to drive out the dissolved gas is provided in the cooling water introduction part of the vacuum evaporation part 20.

In the granulated portion 10, the method and means / equipment for bringing the cooling water into contact with the molten slag may be normal. When the molten slag is rapidly cooled by the cooling water, the molten slag is cracked into fine particles by causing thermal distortion. This granulated slag is reused as a resource such as cement.

The cooling water that has come into contact with the molten slag in the granulated portion 10 has a water temperature, for example, rising to about 55 ° C. In the treatment system of the present invention, the cooling water extracted from the circulation system is vacuum-evaporated using the heat held by the cooling water whose temperature has risen. In the illustrated example, the vacuum evaporation unit 20 is provided in the pipeline of the circulation system 40 that has passed through the water granulating unit 10.

A gas introduction part 23 is provided in the cooling water introduction part of the vacuum evaporation part 20. The cooling water that has contacted the molten slag may contain dissolved gas due to gas components mixed from the slag. If the amount of dissolved gas is large, it is difficult to maintain a degree of vacuum for evaporating the cooling water at 100 ° C. or lower. In such a case, the gas introduction part 23 is provided in the cooling water introduction part of the vacuum evaporation part 20. It is preferable to evaporate in vacuum after introducing nitrogen gas or the like into the cooling water extracted from the circulation system to drive out the dissolved gas.

The vacuum evaporation unit 20 is provided with a heat exchange unit 21. As shown in FIG. 1, cooling water having an increased water temperature that is not extracted from the circulation system is introduced into the heat exchange unit 21. The heat exchanging portion 21 may be formed by, for example, a large number of pipes (not shown) penetrating the vacuum evaporation portion 20, and the pipe forms a part of the circulation system 40. While the cooling water that has risen flows through the pipe, the vacuum evaporation unit 20 is heated by the amount of heat held by the cooling water, and the cooling water extracted from the circulation system and guided to the vacuum evaporation unit 20 evaporates.

For example, the cooling water that has passed through the water granulating unit 10 leads the cooling water that has risen to about 55 ° C. due to contact with the molten slag (cooling water that is not extracted from the circulation system 40) to the heat exchanging unit 21, and the vacuum evaporation unit 20 Heat. The vacuum evaporation unit 20 is maintained at an appropriate vacuum by the vacuum pump 24 and can be evaporated at a temperature of about 55 ° C. by introducing the cooling water extracted from the circulation system 40 under vacuum. The vacuum evaporation part 20 can be formed by a vacuum sealed container. The vacuum pump 24 is preferably provided at the last part of the condensing unit 30 so that a large amount of water vapor does not enter. The vacuum evaporator 20 and the condenser 30 are connected by a pipe 25 having a diameter sufficient to keep the vacuum evaporator 20 in a vacuum by suction of the vacuum pump 24. Further, the vacuum evaporator 20 may be provided with a heater for auxiliary heating. The cooling water that has passed through the heat exchanging portion 21 has its water temperature lowered to about 50 ° C. by heat exchange, and this is led to the cooling portion 50 for further cooling.

On the other hand, by evaporating the cooling water extracted from the circulation system in the vacuum evaporation unit 20 and discharging the evaporation residue to the outside of the system, the amount of waste liquid is greatly reduced, and the burden of waste liquid treatment is remarkably reduced. Specifically, for example, even when cooling water of about 10 t / Hr is extracted from the circulation system, the amount of waste liquid can be reduced to about 1 t / Hr by vacuum evaporation, and the cooling water can be converted into cooling water by contact with molten slag. Since most of the contaminated contaminants remain without being evaporated, the evaporation amount of about 9 t / Hr can be returned to the circulation system. Therefore, the amount of cooling water to be supplied to the circulation system may be much smaller than that of the conventional method. In addition, contaminants are concentrated in the distillation residue, and this evaporation residue is discharged to a waste liquid treatment facility outside the system.

The evaporated water (vapor) evaporated in vacuum is guided to the condensing unit 30. The condensing unit 30 is provided with a heat exchanging unit 31 that cools the steam with natural water such as seawater or river water, and the steam is cooled to become condensed water. The heat exchanging unit 31 may have, for example, a structure in which a large number of pipes are provided in a water tank containing seawater and the like, and the pipes are cooled and condensed by seawater while steam flows. Seawater introduced into the aquarium is discharged outside after heat exchange.

The condensed water evaporated by the vacuum evaporation unit 20 and cooled through the condensation unit 30 is returned to the circulation system 40 through the pipe line 32. On the other hand, the water temperature of the circulating cooling water that has passed through the heat exchanging unit 21 of the vacuum evaporation unit 20 is, for example, about 50 ° C., so that it is guided to the cooling unit 50 and is about 42 ° C. by natural water such as seawater. Cooling. The structure of the cooling unit 50 can be formed in the same manner as the condensing unit 30.

Note that the cooling water in the circulation system that has passed through the heat exchange unit 21 of the vacuum evaporation unit 20 has a water temperature of about 50 ° C., for example, as described above. It can be used as a heating source for concentrating the waste liquid of another system by vacuum evaporation.

The cooling water whose water temperature has been lowered via the cooling unit 50 is returned to the granulating unit 10 through the circulation system 40 and used again as cooling water for granulating the molten slag. In addition, while cooling water is returned to the water granulating unit 10, new water is supplied through the pipe line 60. Specifically, the total amount of water that has adhered to the granulated slag in the granulating unit 10 and carried out of the system and the amount of water that has been extracted out of the system as a distillation residue in the vacuum evaporation unit 20 is replenished. As described above, in the treatment system of the present invention, the amount of waste liquid is greatly reduced by vacuum evaporation, so that the amount of cooling water to be replenished to the circulation system may be much smaller than that of the conventional method.

The treatment method of the present invention is a cooling process for circulating water cooling jackets of various furnaces such as a melting furnace and a smelting furnace, in addition to the cooling water for granulating molten slag in metal smelting as described above, and a rolling process for iron making. The present invention can be widely applied to cooling water that is circulated and used in the cooling system of this type, or cooling water that circulates in the cooling system of power generation equipment.

〔Example〕
A specific application example of the processing system of the present invention shown in FIG. 1 will be shown.
When 1500t / Hr of cooling water is circulated in the water granulation process and about 59t / Hr of molten slag of about 1230 ° C, about 3t / Hr of water adheres to the granulated slag and is carried out of the system. The About 10 t / Hr of water is extracted from the cooling water (water temperature of about 55 ° C.) whose water temperature has been raised by this water granulation, and sent to the vacuum evaporation section. The remaining amount of cooling water flows through the circulation system through the heat exchange section of the vacuum evaporation section. With this high temperature cooling water, the vacuum evaporation section is heated to about 55 ° C. under a vacuum of about 35 mmHg, about 9 t / Hr of cooling water is converted into vapor and led to the condensation section, and about 1 t / Hr of cooling water. Remains without evaporating and is extracted to a wastewater treatment facility outside the system. Seawater at about 20 ° C. is introduced into the condensing part, and the steam introduced into the condensing part is cooled by this seawater to become condensed water, and merges with the cooling water in the circulation system. On the other hand, cooling water (about 50 ° C.) that has passed through the heat exchange section of the vacuum evaporation section is introduced into the cooling section and cooled to about 42 ° C. This cooling water is newly replenished with 13 t / Hr of water through the pipe line 60 and then supplied to the water granulating unit 10 to repeat the above water granulating step.

The conceptual diagram which shows the processing system of this invention Conceptual diagram showing a conventional processing system

Explanation of symbols

10-water granulation unit, 20-vacuum evaporation unit, 21-heat exchange unit, 22-pipeline, 23-gas introduction unit, 24-vacuum pump, 25-pipeline, 30-condensing unit, 31-heat exchange unit, 32-Pipe line, 40-Circulation system, 50-Cooling part, 60-Supply line.

Claims (7)

In the cooling system where the water temperature is used circulated to cool the cooling water rises, leading to a vacuum evaporation unit by extracting part of the water temperature up cooling water from the circulation, whereas the water temperature up cooling water does not withdrawn from circulation Is led to the heat exchange part of the vacuum evaporation part, the cooling water introduced into the heat exchanger is used to evaporate the cooling water of the vacuum evaporation part , the evaporation residue is discharged out of the system, and the steam is cooled. A method for treating cooling water, wherein the cooling water is condensed and returned to the circulation system for reuse. The cooling water according to claim 1, wherein the cooling water is a cooling water for granulating molten slag, a cooling water for a water cooling jacket of a furnace, a cooling water in a steelmaking rolling process, or a cooling water circulating in a cooling system of a power generation facility. Processing method. Circulating molten slag during the granulated processing, a method of recycling a contact with the molten slag cooling water temperature rises as cooling water again to cool water砕用, a portion of the water temperature up cooling water Extracted from the system and led to the vacuum evaporation section, while the cooling water whose water temperature has not been extracted from the circulation system is guided to the heat exchange section of the vacuum evaporation section, and the cooling water of the vacuum evaporation section is utilized by using the heat of the cooling water. The evaporation residue is discharged out of the system, while the steam is cooled and condensed with natural water such as seawater and returned to the circulation system. The cooling water treatment method according to claim 1, wherein the cooling water is reused after cooling with natural water. The method for treating cooling water according to any one of claims 1 to 3, wherein nitrogen gas is introduced into the cooling water extracted from the circulation system to expel dissolved gas from the cooling water and then the cooling water is evaporated in vacuum. The processing method of the cooling water according to any one of claims 1 to 4, wherein the heat held by the cooling water in the circulation system that has exchanged heat in the vacuum evaporation section is used as a heating source for the waste liquid of another system. A slag crushed water treatment facility that circulates and circulates cooling water, a crushed part that makes molten water come into contact with molten slag, and a part of the chilled water that comes into contact with molten slag and rises in water temperature A vacuum evaporation part that extracts and evaporates water from the circulation system, a heat exchange part that introduces cooling water whose water temperature has not been extracted from the circulation system and that serves as a heating source for the vacuum evaporation part , A cooling unit for cooling, a conduit for returning the condensed water to the circulation system, a conduit for discharging the evaporation residue outside the system, and a cooling unit for cooling the cooling water of the circulation system with natural water such as seawater. Slag granulated water treatment facility. The processing equipment for slag crushed water according to claim 6, wherein a gas introduction part for introducing nitrogen gas into the cooling water and driving out the dissolved gas is provided in the cooling water introduction part of the vacuum evaporation part.

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