KR20060090404A - Waste heat recovery system for steam power plant - Google Patents

Abstract

The present invention is a steam power plant comprising a boiler, a turbine, a condenser, and a feed water pump, the cooling water is installed in the condenser and sprayed with the cooling water which is expanded in the turbine directly mixed with the steam introduced into the condenser sprayer; A first pipe connected to the cooling water sprayer; A cooling water tank supplying cooling water to the cooling water sprayer through the first pipe; A second pipe discharging the condensed water cooled inside the condenser; A hot water tank storing condensed water discharged through the second pipe; A third pipe for discharging the condensed water stored in the hot water tank; An external heat exchanger connected to the third pipe to recover heat stored in the condensed water; A fourth pipe for recovering the condensed water recovered from the heat exchanger to the cooling water tank; And a fifth pipe branched from the third pipe and connected to the boiler. 2. The waste heat recovery apparatus of the steam power plant according to claim 1, wherein the fifth pipe is connected to the boiler.

Cooling water sprayer, hot water tank, cooling water tank, external heat exchanger, internal heat exchanger, 1st pipe, 2nd pipe, 3rd pipe, 4th pipe, 5th pipe

Description

Waste heat recovery system for steam power plant

FIG. 1 is a system diagram of a cogeneration apparatus, FIG. 1 (a) is a system diagram of an ideal cogeneration apparatus, and FIG. 1 (b) is a system diagram of a more practical cogeneration apparatus.

2 is a system diagram and T-s diagram of a steam power plant equipped with a conventional feed water heater.

3 is a schematic diagram of a specific embodiment of the present invention.

4 is a schematic diagram of another specific embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: multiplexer

110: cooling water spray

120: circulating water pump

130: internal heat exchanger

200: hot water tank

300: cooling water tank

400: external heat exchanger

10: first piping 20: second piping

30: 3rd piping 40: 4th piping

50: fifth piping

Technical Field

The present invention is a waste heat recovery device having a hot water tank and a coolant tank connected to the condenser and installed in the condenser to increase the thermal efficiency of the steam power plant including a boiler, a turbine, a condenser, and a feed water pump. It is about.

Prior art

The steam power plant, which includes a boiler, a turbine, a condenser and a feed water pump, converts the liquid compressed in the feed water pump into a superheated steam by heating it in a boiler, and the superheated steam generates electricity by rotating the turbine while expanding in the turbine. Flows into the condenser. The steam introduced into the condenser is condensed while releasing the heat that it had through heat exchange with a cooling medium such as river water or air.

The cooling medium such as the river water used in the condensation process is usually heat exchanged with the steam inside the condenser and then released to the outside with a large portion of the thermal energy of the steam cannot be utilized. In order to solve these problems, a method of using waste heat as a valuable energy form is being sought, and a representative method is a cogeneration device illustrated in FIG. 1.

1 (a) is a schematic diagram of an ideal cogeneration system, in which a condenser disappears from a steam power plant and is replaced by a process heater to recycle waste heat discharged through the condenser into energy useful for a process, but is actually operated. It is not a model, but the ideal of the cogeneration device is presented as one of the models.

1 (b) shows a schematic diagram of a cogeneration device having a variable load as a more practical cogeneration device.

In the case of the cogeneration system that recycles a part of the thermal energy that has been discarded in the form of waste heat as energy useful for the process, it is necessary to increase the work generated in the turbine along with the recycling of the useful energy from the process heater. Above all, it is an important challenge.

In other words, there is a need to increase the work generated in the turbine and at the same time have appropriate means to recycle the thermal energy that is wasted as waste heat into useful energy.

On the other hand, Figure 2 shows a schematic diagram and T-s diagram of a steam power plant equipped with a conventional feedwater heater (FWH). The feed water heater is a device that primarily heats the feedwater circulated to the boiler by using steam extracted from the turbine, and increases the overall thermal efficiency by reducing the thermal energy supplied from the boiler.

The use of feedwater heaters not only improves thermal efficiency, but also helps to control the large volumetric flow rate of the steam due to the large specific volume at low pressures in the last stage of the turbine. In addition, there is a problem that can not use the waste heat emitted from the condenser.

In order to solve this problem, the applicant increases work generated in the turbine, recycles waste heat emitted from the condenser into useful energy, and prevents consumption of energy for a separate extraction, thereby dramatically improving thermal efficiency. The company has developed a waste heat recovery system for steam power plant.

The object of the present invention created to solve the above problems is as follows.

First, it is an object of the present invention to provide a means to increase the work occurring in the turbine by providing a more effective condensation method.

Second, another object of the present invention is to provide a means for recycling the cooling water used as the cooling means in the condenser without discharging to the outside.

Third, another object of the present invention is to provide a means for improving thermal efficiency even if steam is not extracted from a turbine, thereby preventing the consumption of energy required for extraction and simplifying the overall structure to pursue economic efficiency.

Fourth, it is another object of the present invention to provide an eco-friendly steam power plant that can prevent ecosystem destruction due to excessive cooling water discharge.

The present invention created to achieve the above object is configured as follows.

The present invention is a steam power plant comprising a boiler, a turbine, a condenser, and a feed water pump, the cooling water is installed in the condenser and sprayed with the cooling water which is expanded in the turbine directly mixed with the steam introduced into the condenser sprayer; A first pipe connected to the cooling water sprayer; A cooling water tank supplying cooling water to the cooling water sprayer through the first pipe; A second pipe discharging the condensed water cooled inside the condenser; A hot water tank storing condensed water discharged through the second pipe; A third pipe for discharging the condensed water stored in the hot water tank; An external heat exchanger connected to the third pipe to recover heat stored in the condensed water; A fourth pipe for recovering the condensed water recovered from the heat exchanger to the cooling water tank; And a fifth pipe branched from the third pipe and connected to the boiler.

Hereinafter, with reference to the accompanying drawings will be described in detail a specific embodiment of the present invention.

A specific embodiment of the present invention is shown in Figures 3 and 4, which, unlike Figure 3, is further provided with an internal heat exchanger (130).

3 and 4, after the superheated steam superheated at a high temperature and high pressure in a boiler expands in a turbine and converts a portion of thermal energy into kinetic energy to generate power, the expanded steam whose energy level is lowered is a condenser ( Condensed into 100).

Conventionally, the steam introduced into the condenser and the cooling water for cooling the steam are not directly contacted and mixed. That is, the cooling water was exchanged with the steam while passing around or inside the condenser through a separate pipe, and the coolant whose temperature was increased through the heat exchange was discharged to the outside, and the new condenser was introduced from the outside into the condenser.

In the case of the present invention, the interior of the condenser 100 is provided with a cooling water sprayer 110 that directly mixes with the expanded steam to condense the steam.

The cooling water transferred from the cooling water tank 300 through the first pipe 10 is directly sprayed on the steam introduced into the condenser 100 through the cooling water sprayer 110 to condense the steam.

In this case, the temperature of the cooling water transferred from the cooling water tank 300 and sprayed is about 30 ° C. to about 40 ° C., and the temperature of steam condensed by the cooling water is about 300 ° C. to about 400 ° C.

The steam, which is lowered in energy level while being mixed with the cooling water, is condensed and stored in the condenser 100 together with the cooling water.

In this case, the temperature of the liquid mixture of cooling water and condensate will be about 85 to 95 degreeC.

The mixed liquid of the cooling water and the condensate stored in the condenser 100 is transferred to the hot water tank 200 through the second pipe by the circulation water pump 120.

A portion of the mixed liquid of the cooling water and the condensate transferred to the hot water tank 200 is transferred to the external heat exchanger 400 through the third pipe 30.

Although not shown in the accompanying drawings, the third pipe 30 or the fourth pipe 40 may be additionally equipped with a separate pump to make the transfer of the mixed liquid more smoothly.

In the external heat exchanger 400, a large portion of the thermal energy of the mixed liquid is recycled into useful energy such as a heat source for heating.

After the heat exchange is performed in the external heat exchanger 400, the temperature of the mixed liquid is lowered to 30 ° C to 40 ° C.

The mixed liquid whose temperature is lowered is circulated back to the cooling water tank 300 through the fourth pipe 40 and reused as the cooling water.

In addition, the fifth pipe 50 branched from the third pipe 30 is connected to the boiler.

The fifth pipe 50 is provided with a water supply pump as shown in Figures 3 and 4 to transfer the remaining part of the mixed liquid of the cooling water and condensate transferred to the hot water tank 200 to the boiler.

The mixed liquid transferred to the boiler is converted into superheated steam to drive a turbine, and the circulation process of condensing by entering the condenser 100 is repeated.

As already known, in order to improve turbine efficiency, it is necessary to convert more heat energy of superheated steam into kinetic energy.

In order to convert more into kinetic energy, it is necessary to lower the temperature and pressure in the condenser 100 corresponding to the outlet of the turbine, and in general, a pressure below atmospheric pressure acts on the condenser 100.

In order to further improve the efficiency of the turbine, it is necessary to lower the pressure inside the condenser 100 even more, and the lower the pressure, the lower the temperature at which steam is condensed.

Therefore, when the pressure inside the condenser 100 approaches a vacuum state, even if the temperature at which the condensation of steam is lowered becomes more effective, in order to condense the vapor in the condenser 100 more effectively, it is necessary to process the cooling of the steam more effectively. .

As such, as shown in FIG. 4, an additional internal heat exchanger 130 may be additionally installed on the upper portion of the cooling water sprayer 110.

The internal heat exchanger 130 primarily cools the steam introduced into the condenser 100 using a mixture of the cooling water and the condensate discharged from the condenser 100 through the second pipe 20.

As described above, the steam introduced into the condenser 100 may be primarily cooled by using the internal heat exchanger 130, and then secondly cooled by the cooling water sprayer 110 to effectively condense the steam. At this time, the temperature of the cooling water and condensate mixture discharged from the condenser 100 is 50 ℃ to 60 ℃.

The mixed solution is heat-exchanged with the steam introduced into the condenser 100 in the internal heat exchanger 130 to obtain thermal energy that the steam has, the temperature is raised to 85 ℃ to 95 ℃ is transferred to the hot water tank 200.

The rest of the operation of the other embodiment of the present invention shown in FIG. 4 is the same as that shown in FIG.

The technical effects of the present invention according to the above technical configuration are as follows.

First, it can increase the work occurring in the turbine by providing a more effective condensation method.

In other words, the present invention can be used to more effectively condense the steam introduced into the condenser 100 after expanding in the turbine by using the coolant atomizer 110 and the internal heat exchanger 130 spraying the coolant directly to the steam, the condenser The pressure applied to the inside (100) can be lowered, which can significantly improve turbine efficiency.

Second, the cooling water used as the cooling means in the condenser can be recycled without being discharged to the outside.

In other words, the present invention is characterized in that the coolant used in the condenser 100 is not discharged to the outside but recycled to the useful energy in the external heat exchanger 400 and then circulated back to the coolant tank 300 for reuse. However, normal system operation is possible even if the supply of river or sea water that can be used as cooling water is not desired.

Third, even if steam is not extracted from the turbine, the thermal efficiency can be improved, thereby preventing the consumption of energy required for the extraction and simplifying the overall structure, it is possible to pursue economics.

In other words, by using the external heat exchanger 400 to recycle the heat energy contained in the mixture of cooling water and condensate as useful energy, such as using a heat source for heating, not only improves the overall thermal efficiency of the steam power plant, but also the condenser ( In addition, the turbine efficiency has been improved by improving the structure of 100), and it is possible to simplify the overall system structure because no additional extraction process is included, and it is also possible to prevent energy consumption required during the extraction process.

Fourth, it is another object of the present invention to provide an eco-friendly steam power plant that can prevent ecosystem destruction due to excessive cooling water discharge.

In other words, the present invention is characterized in that the cooling water can be used repeatedly, it is possible to minimize the risk of ecosystem destruction due to excessive discharge of the cooling water.

Claims (3)

In a steam power plant comprising a boiler, a turbine, a condenser, and a feed water pump, A cooling water sprayer installed in the condenser and spraying the cooling water which is expanded in the turbine and directly mixed with steam introduced into the condenser; A first pipe connected to the cooling water sprayer; A cooling water tank supplying cooling water to the cooling water sprayer through the first pipe; A second pipe discharging the condensed water cooled inside the condenser; A hot water tank storing condensed water discharged through the second pipe; A third pipe for discharging the condensed water stored in the hot water tank; An external heat exchanger connected to the third pipe to recover heat stored in the condensed water; A fourth pipe for recovering the condensed water recovered from the heat exchanger to the cooling water tank; And, A fifth pipe branched from the third pipe and connected to the boiler; Waste heat recovery apparatus of the steam power plant, characterized in that comprises a. In claim 1, A circulating water pump installed in the second pipe to discharge condensed water in the condenser; Waste heat recovery apparatus of the steam power plant, characterized in that it further comprises. The method of claim 1 or 2, An internal heat exchanger installed at an upper portion of the condenser and expanding in the turbine to exchange heat with steam introduced into the condenser; and wherein the second pipe is connected to the hot water tank through the internal heat exchanger. Waste heat recovery apparatus of the steam power plant.

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