JP5794622B2 - Drain collection system - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a drain recovery system in which steam generated in a boiler is reduced to a water supply tank after the temperature is lowered by using it in a steam-using device, and more specifically, heat stored in the drain is wasted. The present invention relates to a drain recovery system that can increase the drain recovery effect.

  As described in Japanese Patent Application Laid-Open No. 7-119918, the steam using apparatus uses the heat of the steam generated in the boiler and recovers steam (drain) whose temperature is lowered by heat exchange in the water supply tank. A drain recovery device for reusing the recovered drain as boiler water is widely used. When drain recovery is performed, the temperature of the boiler water rises because the temperature of the drain is higher than room temperature. If the boiler water temperature rises, the amount of heat required for steam generation decreases, so the amount of fuel used in the boiler can be reduced. Moreover, the usage-amount of boiler water can be reduced by the amount which reuses boiler water.

  However, when the drain recovery amount increases, a large amount of high-temperature drain enters the water supply tank, so that the temperature in the water supply tank rises, causing a water hammer phenomenon in the water supply tank or causing the water pump to cavitate. There was a problem that there was. Therefore, if it is a marine boiler, the drain is recovered after cooling with seawater, or it is recovered after cooling the drain by exchanging heat between the water supplied from the water tank to the boiler and the drain. Things have been done. In the Example column of Japanese Patent Laid-Open No. 7-119918, there is a specific description of an example in which drain is cooled by boiler feed water. Here, the drain is lowered to about 100 ° C. by cooling the drain at about 180 ° C. with boiler feed water at about 95 ° C., and the drain lowered to 100 ° C. is recirculated to the water supply tank. When an air release tank is used as the water supply tank, no pressure is applied in the water supply tank, and flash steam is generated when a drain higher than 100 ° C. enters the water supply tank. If the temperature of the drain returning to the water supply tank is set lower than 100 ° C., the drain that has entered the water supply tank is not flashed and a large amount of steam is not released from the water supply tank.

  However, in the above example, the drain is cooled by boiler feed water that has already risen to about 95 ° C., and the temperature of the boiler feed water goes up and down, so the drain temperature may not be lowered sufficiently. When drain cooling is insufficient and the drain temperature returning to the water supply tank exceeds 100 ° C., it boils in the water tank and releases a large amount of flash vapor into the atmosphere. A large amount of energy and water was to be thrown away.

Japanese Patent Laid-Open No. 7-119918

  The problem to be solved by the present invention is to reduce the loss of thermal energy and water and increase the amount of recovered heat and water in a boiler apparatus that is collecting drainage, thereby increasing overall fuel consumption and water usage. The amount is to reduce.

  A boiler that supplies steam to the steam using device, a steam using device that uses the heat of steam generated in the boiler, a water supply tank that stores the boiler water supplied to the boiler, and after using the heat in the steam using device Steam is recirculated to the water supply tank and reused as boiler water. In the drain recovery system, the drain recovery heat exchanger recovers the heat of the drain in the middle of the drain piping that circulates the drain from the steam using device to the water supply tank. The heat recovered by the drain recovery heat exchanger is supplied to a heat using device such as a vaporizer.

  By utilizing the heat of the drain for purposes other than the heating of boiler feed water, the heat can be effectively utilized without waste and the loss of water can be reduced.

Flow diagram of a drain recovery system implementing the present invention

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow diagram of a drain recovery system embodying the present invention. The boiler 1 generates steam by heating the boiler feed water supplied from the feed water tank 2 through the feed water pipe 4. The water supply tank 2 supplies makeup water (soft water). However, when drain is being collected, the amount of makeup water supplied is reduced because the water collected as drain is supplied to the boiler. In the water supply tank 2, soft water is replenished for the amount that is not sufficient for the drain recovery, and the supply of soft water decreases if the drain recovery amount is large. Boiler feed water sent from the feed water tank 2 to the boiler 1 is supplied in a state where the recovered drain and the replenished soft water are mixed.

  The steam generated in the boiler 1 is sent to the steam using apparatus 3 through the steam pipe 5 connecting the steam using apparatus 3 and the boiler 1, and the steam using apparatus 3 uses the heat of the steam. The temperature of the steam supplied to the steam using device 3 is lowered by the heat used by the steam using device 3. The steam after the heat is taken away by the steam using device 3 is returned to the water supply tank 2 through the drain pipe 6.

  The drain pipe 6 connects the steam using device 3 and the water supply tank 2, and a drain recovery heat exchanger 7 for cooling the drain is provided in the middle of the drain pipe 6. Although the temperature of the steam is reduced by taking heat away from the steam using device 3, the steam still has a lot of heat. Therefore, the drain recovery heat exchanger 7 is installed in the drain pipe 6 and returned to the water supply tank 2. Heat is recovered from the previous drain. The water supply tank 2 is a tank that is open to the atmosphere, and the drain pipe 6 has its tip at the water supply tank 2 side immersed in the underwater portion of the water supply tank 2, so that the heat of the drain Soak up with water. The equipment cost is low if it is a release tank, but flash steam is generated when drainage of 100 ° C. or higher is recovered. In this case, since a large amount of steam is released into the atmosphere, the energy and water held by the collected drain are discarded. Therefore, the heat of the drain is recovered in advance by the drain recovery heat exchanger 7. If heat recovery is performed until the temperature of the drain becomes lower than 100 ° C. in the drain recovery heat exchanger 7, flash steam will not be generated when the drain is returned to the feed water tank 2, and heat and water The amount of discharge from the water supply tank 2 can be reduced.

  The drain recovery heat exchanger 7 is connected to a vaporizer circulation pipe 11 that circulates hot water with the vaporizer 8, and supplies heat recovered from the drain to the vaporizer 8. The drain recovery heat exchanger 7 exchanges heat between the drain and the circulating water, and the heated hot water is sent to the vaporizer hot water tank 9 from the vaporizer hot water tank 9 to the vaporizer 8. Since the vaporizer 8 loses heat of vaporization when the fuel gas is vaporized, the temperature of the hot water sent to the vaporizer 8 is lowered by the vaporizer 8 and is sent to the drain recovery heat exchanger 7 again. In the drain recovery heat exchanger 7, the heat of the drain moves to the circulating water from the vaporizer 8, and raises the temperature of the circulating water. The steam supply amount to the vaporizer hot water tank 9 can be reduced by raising the temperature of the vaporizer hot water tank 9 using the heat of the drain.

  The heat of the drain can be used to heat boiler feed water, thereby reducing the amount of fuel used in the boiler. If only the efficiency of the boiler is considered, the efficiency is higher when all the heat of the drain is used for heating the boiler feed water. However, in that case, another heat needs to be supplied to the vaporizer 8, and a part of the steam generated in the boiler is supplied to the vaporizer 8. Then, even if the efficiency of the boiler alone is increased, the amount of steam used is increased, resulting in an increase in fuel consumption.

  In this embodiment, since the heat of the drain is supplied to the vaporizer 8, the amount of boiler feed water heated by the drain is less than when all the heat of the drain is used for boiler feed water. However, if the vaporizer hot water tank 9 is heated by the heat of the drain, the amount of steam supplied to the vaporizer hot water tank 9 can be reduced. Naturally, if the amount of steam required is reduced, the amount of fuel consumed by the boiler is also reduced. Since the heat of the drain was used only for heating the boiler feed water, the drain heat exceeding 100 ° C. returned to the feed water tank 2 without being able to use up the drain heat, generating flash steam to generate heat from the feed water tank 2. Compared to the case where water is to be thrown away, the total amount of heat recovered will increase, and fuel consumption can be reduced.

  The use of the heat recovered by the drain recovery heat exchanger 7 is not limited to the vaporizer 8, but may be different as long as it uses the heat of the drain. However, an apparatus installed in the boiler room and its surroundings is advantageous because it can supply heat without loss and can utilize heat more effectively. In this respect, the vaporizer 8 that vaporizes LNG and uses it as the fuel gas of the boiler is optimal because it is installed in the boiler room and its vicinity and requires heat.

  The present invention is not limited to the above-described embodiments, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 boiler
2 Water supply tank
3 Steam Use Equipment 4 Water Supply Pipe 5 Steam Pipe 6 Drain Pipe 7 Drain Recovery Heat Exchanger 8 Vaporizer 9 Vaporizer Hot Water Tank 10 Drain Heat Exchange Bypass Valve 11 Vaporizer Circulation Pipe

Claims (1)

A boiler that supplies steam to the steam using device, a steam using device that uses the heat of steam generated in the boiler, a water supply tank that stores the boiler water supplied to the boiler, and after using the heat in the steam using device Steam is recirculated to the water supply tank and reused as boiler water. In the drain recovery system, the drain recovery heat exchanger recovers the heat of the drain in the middle of the drain piping that circulates the drain from the steam using device to the water supply tank. The drain recovery heat exchanger is connected to a vaporizer circulation pipe that circulates hot water with the vaporizer, and the heat recovered from the drain is supplied to the vaporizer. Between the recovery heat exchanger and the vaporizer, a vaporizer warm water tank and a vaporizer circulation pipe vaporizer A drain heat exchange bypass path connecting between the drain recovery heat exchanger and between the drain recovery heat exchanger and the hot water tank for vaporizer and a drain heat exchange bypass valve provided in the middle are installed, and a drain of 100 ° C. or higher is installed. drain recovery system according to this and the characteristics that are to be lower than 100 ° C. by supplying to the heat using equipment such as a vaporizer by recovering heat drain recovery heat exchanger.

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