JP2009162418A - Open circulation type combined cooling facilities and operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide open circulation type combined cooling facilities and their operating method capable of reducing the amount of makeup water and the amount of blow water, reducing the usage of medical agents added to the circulated water, and easily controlling the addition of medical agents in a case when the plurality of open circulation type cooling facilities are installed in one area. <P>SOLUTION: In this open circulation type combined cooling facilities, the plurality of open circulation type cooling facilities are installed in one area, levels of concentration in supplying the same makeup water to each of the cooling facilities are different from each other by cooling facilities, and the blow water of the first cooling facility 10 of higher level of concentration is supplied as the makeup water of the second cooling facility 20 of lower level of concentration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an open circulation type combined cooling facility in which a plurality of open circulation type cooling facilities are installed in one area, and an operation method thereof.

  In general industrial cooling facilities, an open circulation type cooling facility is widely used in which cooling water circulating through a manufacturing apparatus or a cooling apparatus in a manufacturing process is brought into contact with outside air by a cooling tower and cooled by removing heat of vaporization. For example, in the petrochemical industry, a plurality of large cooling towers are installed to cool a large volume of circulating water with a circulating water volume of several thousand to 20,000 tons / hour.

  In the open circulation cooling facility, the circulating water is concentrated by partial evaporation of the water in the cooling tower, and the solid content concentration of salts and the like contained in the circulating water increases. For this reason, a part of circulating water is discharged as forced blow water, and an increase in the solid content concentration of the circulating water is suppressed. Further, fresh water (industrial water or the like) is injected as make-up water to make up for the loss of circulating water due to partial evaporation of water in the cooling tower.

  The value of (Ca hardness of circulating water) / (Ca hardness of makeup water) is referred to as the degree of concentration, and the open circulation type cooling facility has an amount of makeup water and a forced blow water amount so that the degree of concentration is within a predetermined range. (Here, Ca hardness is a value obtained by converting the weight of calcium ions contained in water into the corresponding weight of calcium carbonate. The same shall apply hereinafter). As described above, the open circulation cooling facility is controlled based on the enrichment for the following reason.

  That is, when the enrichment becomes high in the open circulation cooling facility, the concentration of calcium ions and bicarbonate ions contained in the circulating water increases, the pH of the circulating water rises, and calcium carbonate tends to precipitate. The calcium carbonate thus deposited forms a scale on the metal surface, which suppresses metal corrosion as a protective film on the metal surface. For this reason, it is necessary for the anticorrosion that the degree of enrichment exceeds a certain level. However, an excessive increase in the concentration causes adhesion of calcium carbonate scales and scales containing calcium carbonate to heat transfer surfaces such as heat exchangers, and causes problems such as heat transfer inhibition.

  On the other hand, when the degree of concentration is too low, the concentration of calcium carbonate and silica, which are anticorrosive components, is low, and the corrosion prevention of the piping becomes insufficient. Further, when the operation is performed at a low degree of concentration, the amount of makeup water and the amount of forced blow water increase, and the cost of water treatment and water treatment for forced blow water increases. In addition to forced blow water, blow water includes scattered loss water lost due to scattering from the cold water tower, and plant blow water lost due to water leakage in the piping of the circulating water system. Since the water treatment agent is added according to the forced blow water, when the concentration is low, the amount of the water treatment agent used increases, and the cost required for the water treatment agent also increases. For this reason, it is necessary to set the degree of enrichment to a value above a certain level.

  Regardless of the concentration level of the open circulation cooling facility, phosphates are used to prevent corrosion of metals such as carbon steel, copper, and copper alloys used in circulation cooling facility piping and heat exchangers. Corrosion inhibitors such as polymer phosphates, phosphonates, zinc salts and molybdates, and scale inhibitors such as polymer phosphates, phosphonates and carboxylic polymer compounds are added to the circulating water. . These corrosion inhibitors and scale inhibitors are discharged by circulating water blow, and after being subjected to wastewater treatment, are discharged into rivers, lakes, and sea areas. The corrosion inhibitor and scale inhibitor discharged by blowing are proportional to the total amount of forced blow water, splash loss water, and plant blow water. The smaller the total amount of blow water, the smaller the loss. Zinc salts and molybdates, which are active ingredients of corrosion inhibitors used in open circulation cooling facilities, are heavy metal salts, and wastewater containing them may adversely affect aquatic organisms. In addition, although phosphorus-containing wastewater, which is an active ingredient for corrosion inhibitors and scale inhibitors, has low toxicity, it causes eutrophication problems in closed water areas such as lakes and inland seas. The smaller the discharge amount, the better.

Therefore, various methods for obtaining a sufficient effect while reducing the amount of the corrosion inhibitor and the scale inhibitor used have been proposed. For example, an anticorrosion / scale prevention method (see Patent Document 1) or a conductivity meter that removes the hardness component of makeup water and operates under conditions of high alkalinity of 500 (mg-CaCO 3 / L) or higher and pH of 9 or higher. And a cooling water management device (see Patent Document 2) that manages the degree of concentration with a float switch.
JP 9-94598 A Japanese Patent Laid-Open No. 11-248394

  However, the difference in evaporation capacity in open circulation cooling facilities and the degree of leakage of circulating water differ from facility to facility, so even if makeup water with the same solid content concentration is supplied to each cooling facility, Different values for each cooling facility. For this reason, when there are multiple open circulation cooling facilities in an area, the forced blow water is controlled to be discharged under individual management according to the characteristics and concentration of each open circulation cooling facility. For this reason, the total amount of forced blow water is increased, and the treatment cost of forced blow water is high. In addition, since the pH, calcium hardness and total hardness of the circulating water differ depending on the characteristics and concentration of each open circulation cooling facility, the types of chemicals such as anticorrosives, scale inhibitors and slime control agents used are different. It will be different for each cooling facility. In addition, even if the same anticorrosive, the same scale inhibitor, the same slime control agent, etc. are used, it is possible to control the addition of the chemical so that the addition amount according to the characteristics of the open circulation type cooling facility. Management becomes complicated and workability is poor.

  The present invention has been made in view of the above-described conventional problems. When a plurality of open circulation type cooling facilities are installed in one area, the amount of makeup water and the amount of forced blow water are reduced and added to circulating water. It is an object of the present invention to provide an open circulation type combined cooling facility that can reduce the amount of medicine used and that can easily control the addition of medicine and manage the medicine, and an operation method thereof.

  In the open circulation type combined cooling facility of the present invention, a plurality of open circulation type cooling facilities are installed, and the concentration when supplying makeup water of the same water quality is different for each cooling facility. The forced blow water of the first cooling facility having a lower degree is supplied as makeup water for the second cooling facility having a lower concentration.

  In the open circulation type combined cooling facility of the present invention, the forced blow water of the first cooling facility having a higher concentration is reused as makeup water for the second cooling facility having a lower concentration. The amount of forced blow water sent to the treatment device is reduced, and the treatment cost of forced blow water is reduced. Further, the amount of makeup water supplied from the outside such as industrial water is reduced by the amount of reuse of forced blow water.

  Further, in the open circulation type combined cooling facility of the present invention, a plurality of open circulation type cooling facilities are installed, and the degree of enrichment when supplying makeup water of the same water quality to each cooling facility is different for each cooling facility. Is different. However, since the forced blow water of the first cooling facility having a higher concentration is introduced as makeup water for the second cooling facility having a lower concentration, it is supplied to the second cooling facility. Unlike the makeup water supplied to the first cooling facility, the supplementary water contains calcium carbonate having an anticorrosive effect, a scale inhibitor and anticorrosive agent that suppresses scale components, and, in some cases, a slime control agent. For this reason, the difference in the water quality of the circulating water in each cooling facility is reduced, the water quality and concentration of both cooling facilities are close to each other, and the optimum addition amount of anticorrosive agent, scale inhibitor, and in some cases, slime control agent, etc. Will be close. For this reason, even if it does not manage so that it may become the optimal addition amount different for every cooling facility, if it adds with the same management value, it will be in the state close | similar to the optimal conditions.

  Furthermore, chemicals added to the circulating water system such as corrosion inhibitors and scale control agents added to the circulating water in the first cooling facility become recycled water in the second cooling facility along with forced blow water and are reused. As a result, the cost of these chemicals is reduced, the chemicals used are unified, the treatment costs for blow water drainage are reduced, and the management burden is reduced.

  The open circulation type combined cooling facility of the present invention is operated as follows. That is, in the operation method of the open circulation type combined cooling facility of the present invention, a plurality of open circulation type cooling facilities are installed, and the concentration when supplying makeup water of the same water quality is different for each cooling facility. The forced blow water of the first cooling facility having a higher concentration is used as makeup water for the second cooling facility having a lower concentration.

  Water treatment chemicals such as a scale control agent are added to the circulating water system of the open circulation type combined cooling facility in proportion to the total amount of splash loss water, plant blow water and forced blow water. When a plurality of open circulation type cooling facilities are operated independently, forced blow water is generated from each open circulation type cooling facility, and each must be treated as waste water. On the other hand, according to the operating method of the open circulation type combined cooling facility of the present invention, the forced blow water of the first cooling facility in the state where the water treatment agent has already been added is reduced to the second concentration with a lower concentration. Since it is used as makeup water for a cooling facility, sufficient anticorrosive effect and scale preventive effect can be obtained even if there are few water treatment agents. In addition, the amount of makeup water can be reduced.

In the present invention, the effect of the present invention can be obtained if the concentration of circulating water in the first cooling facility is higher than the concentration in the second cooling facility. In particular, if the operation method of the present invention is performed in an open-circulation combined cooling facility in which the concentration of circulating water in the first cooling facility is one or more larger than the concentration in the second cooling facility, it is possible to reduce makeup water. This is preferable because the effects of reducing forced blow water, saving water treatment chemicals, and managing circulating water quality are obtained. Further, if the concentration of circulating water in the first cooling facility is one or more larger than the concentration of the second cooling facility and the concentration of circulating water in the first cooling facility is 5 or more and less than 7, This is more preferable because the forced blow water is greatly reduced, and the effects of further reduction of water treatment chemicals and the management of circulating water quality are obtained.
In addition, the low concentration of circulating water in the second cooling facility is operating in a state where a small amount of forced blow water or forced blow is not performed due to a large loss due to plant blow water or splash loss water, etc. In this case, the operation method of the present invention is applied to use the forced blow water having a high concentration of the circulating water of the first cooling facility as the makeup water of the second cooling facility, so that the first cooling facility is used. Therefore, it is possible to effectively reuse the added water treatment chemical added to the first cooling facility in the second cooling facility, and to circulate two or more different cooling facilities. By approximating the water quality of the water, it is preferable that the quality of the circulating water is simplified and can be collectively managed.

  The present invention can be applied to an open circulation type cooling facility that is used by taking industrial water, tap water, well water, etc. from rivers, lake water, ground water, rain water and the like. As such an open circulation type cooling facility, for example, an oil refining industry, a petrochemical industry, a paper pulp manufacturing industry, a textile industry, a paint industry, a synthetic rubber latex industry and various other manufacturing industries, a power plant, an air conditioning system, etc. Cooling facility.

  Various characteristics of the open circulation cooling facility are not particularly limited, but generally, the amount of retained water is about 500 tons to about 5,000 tons, and the amount of circulating water is about 300 tons / hour to about 20,000 tons / , ΔT is about 2 ° C. to about 12 ° C., the makeup water amount is about 60 tons / hour to about 100 tons / hour, the blow water amount is about 10 tons / hour to about 50 tons / hour, and the concentration is about 2 to about 7 It is. The amount of scattered water is an amount specific to an open circulation type cooling facility, but is usually about 0.1 wt% to 0.2 wt% of the circulating water amount. The amount of plant blow water is a value specific to an open circulation cooling facility and varies depending on each open circulation cooling facility. The plant blow water amount is calculated by the difference between the water amount at the start of circulation sent out from the cooling tower and the water amount at the time of recovery when returning to the cooling tower. The amount of forced blow water is adjusted according to the quality and concentration of the target circulating water. In addition, natural water from industrial rivers and lakes, tap water, and the like are used as makeup water for the open circulation cooling facility.

Hereinafter, Example 1 and Comparative Example 1 that further embody the present invention will be described in detail with reference to the drawings.
Example 1
As shown in FIG. 1, the open circulation type combined cooling facility according to the first embodiment includes two cooling facilities of an open circulation type first cooling facility 10 and an open circulation type second cooling facility 20. The first cooling facility 10 has a retained water amount of 2400 t and a circulating water amount of 7000 t. When the first cooling facility 10 is operated independently, the enrichment is 6 times. On the other hand, the second cooling facility 20 has a retained water amount of 2300 t and a circulating water amount of 10000 t. When operated alone, the scattering loss, plant blow (that is, leakage in the circulating water plant), convenience of facility capacity, and operating conditions Although the forced blow was sometimes temporarily performed due to the circumstances of the above, it was usually operated with the forced blow water amount being zero. Therefore, the enrichment in the second cooling facility 20 can only be increased up to about 4.1 times.

  In the first cooling facility 10, an induced draft counterflow contact type cooling tower 11 and a heat exchanger 12 are connected by a pipe 13, and circulating water is passed through the pipe 13 by a circulation pump 14 installed in the middle of the pipe 13. Circulation is possible. The corrosion inhibitor is added so as to maintain a constant concentration (for example, 10 mg / L as a corrosion inhibitor) with respect to the circulating water system. Therefore, the amount of the corrosion inhibitor having a concentration of 10 mg / L with respect to the total blow water is added to the makeup water. Similarly, in the case of the slime control agent, it is added so as to maintain a constant concentration (for example, added so as to be 2 mg / L as the slime control agent) with respect to the circulating water system. The corrosion inhibitor and the slime control agent are added to the pits of the cooling tower 11 by the injection device 16 and the injection device 17, respectively. In addition, industrial water is used as make-up water and is supplied to the pits of the cooling tower 11 through the supply pipe 15. A valve 18 is provided in the pipe 13 between the cooling tower 11 and the circulation pump 14, and forced blow water is supplied to the pit of the cooling tower 21 of the second cooling facility 20 via the blower pump 30 and the forced blow water supply pipe 31. To be introduced.

  The second cooling facility 20 is connected to a cooling tower 21 and a heat exchanger 22 of an induced draft countercurrent contact type by a pipe 23, and circulating water is circulated in the pipe 23 by a circulation pump 24 installed in the middle of the pipe 23. Can be circulated. The makeup water is supplied to the pit of the cooling tower 21 through the supply pipe 25. As a corrosion inhibitor, an acrylic acid-acrylamide sulfonic acid copolymer is added so as to maintain a certain concentration (for example, 10 mg / L as a corrosion inhibitor) with respect to the circulating water system. Therefore, the amount of the corrosion inhibitor having a concentration of 10 mg / L with respect to the total blow water is added to the makeup water. Similarly, sodium hypochlorite (2 to 12% by weight aqueous solution) as a slime control agent is maintained at a constant concentration (for example, 2 mg / L as a slime control agent) with respect to the circulating water system. Added. They are added to the pits of the cooling tower 21 by the injection device 26 and the injection device 27, respectively. The forced blow water discharged from the second cooling facility 20 is sent to a wastewater treatment facility (not shown) through the valve 28 and the forced blow water supply pipe 29.

  In the open circulation type combined cooling facility configured as described above, the circulating water in the pipe 13 of the first cooling facility 10 is heat-exchanged by the heat exchanger 12, and the temperature rises. And it is sent to the cooling tower 11 by the drive of the circulation pump 14, and is cooled. At this time, part of the circulating water is carried away by evaporation, so that the solid content concentration increases. A part of the circulating water whose concentration has been increased in this way is reused as supplementary water as forced blow water by driving the blower pump 30 through the forced blow water supply pipe 31 to the pipe 23 of the second cooling facility 20. . Also in the second cooling facility 20, the concentration of circulating water similar to that in the first cooling facility 10 occurs, and a part of the water whose concentration is increased is driven through the forced blow water supply pipe 29 by driving the valve 28. Sent to a wastewater treatment facility.

(Comparative Example 1)
In Comparative Example 1, the same open circulation type combined cooling facility as in Example 1 was used. However, the valve 18 closed the supply of water to the second cooling facility 20, and the blower pump 30 was also stopped. Then, each of the first cooling facility 10 and the second cooling facility 20 is operated independently, the forced blow water is drawn from the first cooling facility 10 by the blower pump 19, and the forced blow water is also discharged from the second cooling facility 20 by the valve 28. I pulled it out. When the first cooling facility 10 and the second cooling facility 20 are each operated independently, the circulating water quality is different, so the first cooling facility 10 uses an acrylic acid-acrylamide sulfonic acid copolymer as a corrosion inhibitor, and slime control. Sodium hypochlorite is used as the agent. On the other hand, in the 2nd cooling facility 20, acrylic acid-phosphonic acid copolymer was used as a corrosion inhibitor, and sodium hypochlorite was used as a slime control agent.

(Evaluation results)
In Table 1, the forced circulation water of the first cooling facility is used as makeup water for the second cooling facility, and the open circulation type combined cooling facility of Example 1 and the comparative example 1 in which each cooling facility is driven independently. The test results are shown.

  As can be seen from Table 1, the makeup water was 232 t / hr in Comparative Example 1 whereas it was 223 t / hr in Example 1, which was a 9 t / hr saving (about 4% savings). Further, drainage by forced blow water was 0 t / hr in Example 1. Regarding the water quality, the quality of the circulating water in the second cooling facility in Example 1 was almost the same as that of the first cooling facility in Comparative Example 1.

  The above results are explained as follows. That is, in the open circulation type combined cooling facility of the first embodiment, the blow water of the first cooling facility 10 is reused as makeup water for the second cooling facility 20, and therefore the amount of blow water sent to the waste water treatment apparatus is small. This reduces the cost of treating blow water. Further, the amount of makeup water supplied from the outside such as industrial water is reduced by the amount of reuse of blow water.

  In addition, water supplied to the first cooling facility 10 is only industrial water, whereas water supplied to the circulating water of the second cooling facility 20 is industrial water and blow water from the first cooling facility 10. Therefore, water having a higher solid content concentration is supplied. However, since the concentration in the single operation of the first cooling facility 10 is higher than the concentration in the single operation of the second cooling facility 20, the difference in the concentration is the solid content of the replenished water. It is alleviated by the difference in concentration. For this reason, the optimum addition amount of anticorrosive and scale inhibitor is close, and even if it is not controlled so that the optimum addition amount differs for each cooling facility, it is optimal if it is added with the same control value. It becomes a state close to the conditions, and management becomes easy. For example, as shown in Table 1, in Example 1, the water quality values (for example, calcium hardness) of the first cooling facility and the second cooling facility are close to each other. It can be seen that the quality of the circulating water in the cooling facility can be managed in the same way. As a result, it can be seen that the two cooling facilities can be managed with common water treatment chemicals and indicators.

  Furthermore, additives added to the circulating water system such as corrosion inhibitors and slime control agents added to the circulating water of the first cooling facility become recycled water of the second cooling facility together with the blow water and are reused. Therefore, the cost of these chemicals is reduced, the chemicals used are unified, the cost for treating the blow water drainage is reduced, and the management burden is reduced. For example, with respect to the addition amount of the corrosion inhibitor and the slime control agent, in Example 1, since the blow water of the first cooling facility 10 is reused as make-up water of the second cooling facility 20, comparison is made from the results in Table 1. It turns out that it becomes a chemical | medical agent saving of "9/38 = about 24" (%) with respect to Example 1. FIG.

  The present invention is not limited to the description of the embodiments of the invention. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

The open circulation type combined cooling facility and the operation method of the present invention can be used for an open circulation type combined cooling facility in which a plurality of open circulation type cooling facilities are installed in one area.
While reducing the amount of replenishing water and the amount of blown water, the amount of the chemical added to the circulating water can be reduced, and the control of the chemical addition is facilitated.

It is a schematic diagram of the open circulation type complex cooling facility of Example 1.

Explanation of symbols

  10, 20 ... cooling facility (10 ... second cooling facility, 20 ... first cooling facility)

Claims (3)

  A plurality of open-circulation cooling facilities are installed, and the concentration when supplying makeup water of the same water quality is different for each cooling facility, and forced blow of the first cooling facility with a higher concentration is achieved. An open circulation combined cooling facility characterized in that water is supplied as makeup water for a second cooling facility having a lower concentration.   A plurality of open-circulation cooling facilities are installed, and the concentration when supplying makeup water of the same water quality is different for each cooling facility, and forced blow of the first cooling facility with a higher concentration is achieved. A method of operating an open circulation type combined cooling facility, wherein water is used as makeup water for a second cooling facility having a lower concentration.   The operating method of the open circulation type combined cooling facility, wherein the difference between the concentration of circulating water in the first cooling facility and the concentration of the second cooling facility is 1 or more.

Images