JPH11350921A - Exhaust heat recovery boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust heat recovery boiler that eliminates change in temperature of supply water from the pump while reducing power of the auxiliary and water extraction rate. SOLUTION: A branched water supply pipe is provided at a low temperature water supply pipe, and water is supplied directly to a low pressure system via the low temperature water supply pipe. A high pressure water supply pump 39 is arranged at the branched pipe from an outlet water supply and water extracted at an intermediate stage of the high pressure water supply pump 39 are supplied to a high pressure system and to a medium pressure water extraction system, respectively. Accordingly, low temperature water supply for an exhaust heat recovery boiler is supplied to a low pressure system economizer 8 directly at a pressure required in the low pressure system, while only pressure in high and medium pressure system water supplies that are branched from a water supply passage for supplying the low temperature water are increased by the high pressure water supply pump 39. Therefore, pressure in the low pressure system is not increased with no effect. Further, since only the medium pressure system water supply is extracted from an intermediate stage of the high pressure water supply pump 39, water extraction rate is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery boiler, and more particularly to an exhaust heat recovery boiler in which the power of a water supply system is reduced while an increase in the heat transfer area of a economizer is reduced.

[0002]

2. Description of the Related Art A conventional exhaust heat recovery boiler is, for example, a triple-pressure exhaust heat recovery boiler comprising a high-pressure, medium-pressure and low-pressure steam generation system as shown in FIG. This is a boiler with heat exchangers such as superheaters, evaporators, and economizers arranged basically from the high temperature side of the inlet where the exhaust gas is introduced in the boiler housing to the low temperature side of the outlet. In addition, a configuration is provided in which the water or steam system introduced into the heat exchanger and the exhaust gas flowing through the housing have a counterflow, so that the maximum heat recovery can be performed with a minimum heat transfer area. The original heat recovery steam generator was single-pressure, but due to the recent demand for improved thermal efficiency, a double-pressure heat recovery steam generator consisting of high-pressure and low-pressure steam generation systems, as well as high-, medium-, and low-pressure steam generation A triple-pressure exhaust heat recovery boiler consisting of a system has been proposed and actually employed. Hereinafter, a boiler shown in FIG. 8, which is a configuration example of a typical system of a triple pressure boiler, will be described.

[0003] The water from the condenser 46 is boosted by a condenser pump 47 to a pressure required for the low-pressure steam system, and is supplied to the low-temperature water supply pipe 1.
Is supplied to the low-pressure economizer 8 via the low-pressure water supply pipe 2a. The supply water whose temperature has been raised by heat exchange with the exhaust gas 29 flowing through the housing 28 in the low pressure economizer 8 is supplied to the low pressure water supply pipe 2b.
After a part is supplied to the low-pressure drum 9, it is vaporized in a process of passing from the low-pressure downcomer 10 to the low-pressure evaporator 11. Partially vaporized feedwater is returned from the low-pressure evaporator 11 to the low-pressure drum 9 to perform steam separation, and the steam is sent from the low-pressure main steam pipe 12 to a steam turbine (not shown).

[0004] Further, the other water supplied by the low-pressure water supply pipe 2b is boosted from the medium- and high-pressure water supply pipe 42 to a pressure required for the high- and medium-pressure steam system, and is supplied to the medium-pressure drum 14 and the high-pressure drum 20, respectively. Supplied. Medium pressure drum 14 and high pressure drum 2
The feed water supplied to the evaporator 16 is vaporized in the evaporator 16 and the evaporator 22, respectively.
Through a steam turbine (not shown).

[0005] That is, the feed water pressurized by the high-pressure feed pump 39 provided in the middle-high pressure feed pipe 42 is sent to the high-pressure primary economizer 6 via the high-pressure feed pipe 4a, where it is heated. After the heat exchange with the exhaust gas 29 in the high pressure secondary economizer 19 via the high pressure water supply pipe 4b, the heat is introduced into the high pressure drum 20 via the high pressure water supply pipe 4c. The high-pressure water in the high-pressure drum 20 becomes high-pressure steam in the process of passing from the high-pressure downcomer 21 to the high-pressure evaporator 22, is returned from the high-pressure evaporator 22 to the high-pressure drum 20, and is subjected to gas-water separation. It is further heated by the superheater 23 and the high-pressure secondary superheater 25 and sent to a high-pressure steam turbine (not shown). In the steam flow path between the high-pressure primary superheater 23 and the high-pressure secondary superheater 25, a desuperheater 24 for controlling the superheated steam temperature is provided.

[0006] The water supplied by the medium-pressure water supply pump 40 provided in the medium- and high-pressure water supply pipe 42 is supplied to the medium-pressure water supply pipe 3.
The medium is sent to the intermediate-pressure primary economizer 7 via a, is heated here, and is introduced into the intermediate-pressure drum 14 via the intermediate-pressure water supply pipe 3b. The medium-pressure water in the medium-pressure drum 14 is supplied to the medium-pressure downcomer 15
Into medium-pressure steam in the process of passing through the medium-pressure evaporator 16,
The steam is returned from the medium-pressure evaporator 16 to the medium-pressure drum 14, where the steam is separated. The medium-pressure steam is superheated by the medium-pressure superheater 17 and sent from the medium-pressure main steam pipe 18 to a medium-pressure steam turbine (not shown). Can be

Water supplied from the middle stage of the high-pressure water supply pump 39 is returned to the low-temperature water supply pipe 1 from the water supply recirculation pipe 27, and the temperature of the low-temperature water is raised to about 60 ° C. Prevents corrosion. Further, part of the water supplied from the high-pressure water pump 39 to the high-pressure primary economizer 6 is supplied to the high-pressure water minimum flow pipe 5, and part of the water supplied from the medium-pressure water pump 40 to the intermediate-pressure primary economizer 7 is medium. The water is sent from the pressure supply minimum flow pipe 41 to the condenser 46, and the minimum flow amount of the high pressure water supply pump 39 and the medium pressure water supply pump 40 is secured.

In the above-mentioned heat recovery steam generator, high-temperature water branched from the outlet of the low-pressure economizer 8 is supplied to a medium- and high-pressure water supply pipe 42 which is an inlet pipe of the high-pressure water supply pump 39 and the medium-pressure water supply pump 40. Therefore, a boiler or the like that repeatedly starts and stops every day is exposed to a sudden temperature change of about 6 ° C./second at the time of starting, and there is a problem in durability of the pumps 39 and 40.

FIG. 9 shows an exhaust heat recovery boiler described in Japanese Patent Application Laid-Open No. 7-225003, which eliminates sudden changes in temperature of medium- and high-pressure feed pumps, reduces the number of pumps, and facilitates boiler arrangement. For this purpose, a water supply pump 45 is provided in the low-temperature water supply pipe 1 and a low / medium pressure system is drawn from an intermediate stage of the water supply pump 45.

That is, the water discharged from the water supply pump 45 is supplied to the high-pressure drum 20 via the high-pressure primary economizer 6, the high-pressure water supply pipe 4 b and the high-pressure secondary economizer 19.
5 is supplied to the low-pressure drum 9 via the medium-pressure water supply pipe 3a and the medium-pressure primary economizer 7, and further from the medium-pressure water supply pipe 3b branched from the outlet of the medium-pressure primary economizer 7. It is configured to be supplied to the medium pressure drum 14 via the pressure secondary economizer 13 and the medium pressure water supply pipe 3c. For this reason, the temperature change of the feedwater flowing into the feedwater pump 45 is suppressed, the pump 45 is not subjected to an excessive thermal shock, the deterioration of the feedwater pump 45 can be prevented, and one large-sized feedwater pump 45 is provided. If
It is possible to reduce the power consumption in the office and the number of installations of auxiliary equipment.

In the configuration shown in FIG. 9, a feed water recirculation pipe 27 is provided at the outlet of the intermediate-pressure primary economizer 7, and
By recirculating a part of the feedwater from 7 to the inlet side of the feedwater pump 45, low-temperature corrosion of the medium-pressure primary economizer 7 and the high-pressure primary economizer 6 can also be prevented.

[0012]

In the above prior art, the low pressure water supply system is provided with a high pressure pump 39 and a medium pressure pump 4 as shown in FIG.
0 to increase to high or medium pressure, or FIG.
As shown in FIG. 9, the auxiliary power is increased to increase the pressure to medium pressure or high pressure by the large water supply pump 45, and in the example of FIG. 9, water is drawn from the medium / low pressure system of the water supply pump 45. As the ratio increases, the boiler starts and stops every day, and the combined cycle in which the load changes drastically (combined with a gas turbine and a waste heat recovery boiler using its exhaust gas and a steam turbine), the durability of the feedwater pump system Could be adversely affected.

An object of the present invention is to provide an exhaust heat recovery boiler in which the power of auxiliary equipment is reduced and the pump water supply temperature is not changed while reducing the water extraction ratio.

[0014]

The above object of the present invention is attained by the following constitution. That is, a heat transfer tube group provided in an exhaust gas flow path composed of two or more pressure systems, a water supply path for supplying water to the economizer in the heat transfer tube group of each pressure system, and a water supply from the economizer of each pressure system In the exhaust heat recovery boiler provided with each of the steam-water separation drums, a branch water supply path branched from a water supply path to the low-pressure system, a high-pressure water supply pump provided in the branch water supply path, and a discharge from the high-pressure water supply pump An exhaust heat recovery boiler is provided with a water supply path for supplying water to a high-pressure side pressure system and a water supply path for supplying high-pressure water supply pump intermediate stage extraction to an intermediate pressure system.

Referring to the drawings, one example of the present invention will be described. As shown in FIG. 1, a low-temperature water supply pipe 1 is provided with a branch water supply pipe.
The low-pressure system is supplied with water from the low-temperature water supply pipe 1 as it is, a high-pressure water supply pump 39 is disposed in the branched pipe, the outlet water supply of the high-pressure water supply pump 39 is used for the high-pressure system, and the intermediate-stage water extraction of the high-pressure water supply pump 39 is applied to the medium pressure. It is supplied to the water extraction system.

In this manner, the low-temperature feedwater supplied to the exhaust heat recovery boiler is supplied to the low-pressure system economizer at the pressure required for the low-pressure system as it is, and the high- and medium-pressure water branched from the water supply path for supplying the low-temperature feedwater. Since only the system water is boosted by the high-pressure water pump, the low-pressure system is not unnecessarily boosted, and
Since only the medium-pressure water is extracted from the middle stage of the high-pressure water pump, the extraction ratio can be reduced.

According to the present invention, there are three types of economizers, for example, high pressure, medium pressure and low pressure. In FIG. 1, a low-pressure economizer 8 and a medium-pressure 1
The secondary economizer 7 and the high-pressure primary economizer 6 are arranged. In this case, the temperature distribution of exhaust gas and water is as shown in FIG.
Since the temperature difference between the low pressure economizer 8 and the medium pressure primary economizer 7 is smaller than the temperature difference between the medium pressure primary economizer 7 and the high pressure primary economizer 6, the low pressure economizer 8 and the medium In the pressure primary economizer 7, the heat of the exhaust gas cannot be used effectively. The horizontal axis in FIG. 2 represents a necessary heat transfer area in each pressure system.

Therefore, the actual arrangement is such that three types of economizers of high pressure, medium pressure and low pressure are arranged in parallel in the gas flow direction, as shown in the top view of the exhaust heat recovery boiler in FIG. Thereby, an increase in the heat transfer area of the heat transfer tube of each economizer can be prevented.

However, in this case, the ratio of the number of heat transfer tubes in the direction perpendicular to the gas flow is as follows: high-pressure economizer: medium-pressure economizer: low-pressure economizer = 100: 5-1
0: 5-10 and the heat transfer area of the heat transfer tubes of the medium-pressure and low-pressure economizers is extremely small. There are factors that increase costs.
As shown in the top view of the exhaust heat recovery boiler in FIG. 6 or 7, the problem is that the heat transfer tubes of each economizer are transferred in the exhaust gas flow direction of the exhaust gas passage according to the heat transfer area of each pressure system. The problem is solved by arranging them in series for the number of heat tubes.

In the above description, the three pressure systems of high pressure, medium pressure and low pressure have been described. However, the present invention is not limited to this.
It can be applied to the waste heat recovery boiler of the above water supply or steam pressure system.

At this time, when the exhaust heat recovery boiler of the present invention is applied to two pressure systems, a high pressure system and a low pressure system, it is not necessary to extract water at an intermediate stage of the high pressure pump.

Further, according to the present invention, when reheating high-pressure steam after performing a part of the work in the high-pressure turbine, the high-pressure steam is returned to the medium-pressure system, superheated as reheated steam, and supplied to the steam turbine again. It is good also as composition.

Further, in the present invention, a part of the high-temperature feedwater heat recovered by the economizer of a predetermined pressure system (the intermediate-pressure secondary economizer 13 in FIG. 1) is partially replaced with a high-pressure feed pump (in FIG. 1, a high-pressure feed pump). By providing a water supply recirculation path (the water supply recirculation pipe 27 in FIG. 1) for returning to the water supply water supply path 1 to the low pressure system upstream of the branch water supply path where the water supply pump 39) is provided, the thermal shock of the high pressure water supply pump and Low temperature corrosion of each economizer can be prevented.

A part of the water supplied from the high pressure water supply pipe 4a downstream of the high pressure water supply pump 39 to the high pressure primary economizer 6 is sent to the high pressure water supply pump minimum flow pipe 5, and the minimum flow of the high pressure water supply pump 39 is minimized. Secure quantity. Further, the arrangement structure of the economizer as shown in FIG. 4, FIG. 6 or FIG. 7 can also be applied to the exhaust heat recovery boiler having the configuration shown in FIG.

[0025]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a case where an exhaust heat recovery boiler according to an embodiment of the present invention is applied to a combined cycle.
Exhaust gas at about 600 ° C. obtained from a gas turbine (not shown) is recovered by an exhaust heat recovery boiler, and is discharged as a low temperature exhaust gas 29 at about 100 ° C. from a chimney (not shown) into the atmosphere.

On the other hand, the low-pressure main steam generated in the exhaust heat recovery boiler is a low-pressure main steam pipe 12, and the medium-pressure main steam is a medium-pressure main steam pipe 18.
The high-pressure main steam is sent from the high-pressure main steam pipe 26 to steam turbines (not shown) of the respective pressure systems, and after working, releases heat that cannot be used in the condenser 46 to return to water,
The pressure is raised by the condensate pump 47 to be low-temperature water supply, and the low-temperature water supply pipe 1 supplies water to the exhaust heat recovery boiler.

The low-temperature water supplied from the low-temperature water supply pipe 1 passes through the low-pressure water supply pipe 2a and is heated by the low-pressure economizer 8 to a temperature about 10 ° C. lower than the saturation temperature at the pressure in the low-pressure drum 9; And the feedwater is vaporized while circulating between the downcomer 10, the evaporator 11 and the drum 9, and only the low-pressure steam obtained by the steam separation in the low-pressure drum 9 is not shown by the low-pressure main steam pipe 12. Supplied to the turbine.

The water supplied to the high-pressure water supply pipe 4a branched from the low-temperature water supply pipe 1 is boosted by a high-pressure water supply pump 39 to a pressure required for the high-pressure system, about 130 kg / cm ^2. And then the high pressure water pipe 4
b, it is sent to the high-pressure secondary economizer 19, further heated and supplied to the high-pressure drum 20 via the high-pressure water supply pipe 4c. The high-pressure drum 20 vaporizes while circulating between the high-pressure downcomer 21, the high-pressure evaporator 22, and the high-pressure drum 20, and the high-pressure steam separated by the high-pressure drum 20 passes through the high-pressure primary superheater 23 and the high-pressure secondary superheater 25. It is superheated to about 540 ° C. by passing through sequentially and sent from the high-pressure main steam pipe 26 to a high-pressure steam turbine (not shown). In the steam flow path between the high-pressure primary superheater 23 and the high-pressure secondary superheater 25, a desuperheater 24 for controlling the superheated steam temperature is provided.

The water extraction pressure from the intermediate stage of the high-pressure water supply pump 39 is about 35 kg / cm ² , water is extracted from the wake of the first stage blade of the high-pressure water supply pump 39, and the medium-pressure primary node is passed through the medium-pressure water supply pipe 3a. It is supplied to the charcoal 7 and then the medium pressure water supply pipe 3b,
It is supplied to the medium pressure drum 14 via the medium pressure secondary economizer 13. The feed water is vaporized while circulating from the medium pressure drum 14 to the medium pressure downcomer 15, the medium pressure evaporator 16, and the medium pressure drum 14. The intermediate-pressure steam separated by the intermediate-pressure drum 14 is superheated by the intermediate-pressure superheater 17 and then sent from the intermediate-pressure main steam pipe 18 to an intermediate-pressure steam turbine (not shown).

Further, in the configuration shown in FIG. 1, a part of the outlet water supply of the intermediate-pressure secondary economizer 13 is recirculated from the recirculation pipe 27 to the low-temperature water supply pipe 1 upstream of the inlet of the high-pressure water supply pump 39. The thermal shock of the high-pressure water supply pump 39 can be reduced, and low-temperature corrosion of the economizers 6 to 8 can be prevented. When reheating high pressure steam after doing some work in a high pressure turbine,
The high-pressure steam may be returned to the medium-pressure system, superheated as reheated steam, and supplied to the steam turbine again.

As described above, the low-pressure system uses the water supply of the pressure system pressurized by the condensate pump 47, and the water drawn from the middle stage of the high-pressure pump 39 is used only as the medium-pressure water supply.
The power of the water supply pump 39 and the water extraction ratio (to the suction flow rate) of the high-pressure water supply pump 39 are as shown in the following table.

[Table 1] ================================== The Present Invention Prior Art ---- -------------------------------------------------------- (FIG. 1) (FIG. 8) (FIG. 9) ------------------------------------------------------------------------ −−−−−−−−−−− Pump shaft power (kw) 1170 1190 1210 Extraction ratio (normal) (%) 25 16 32 Extraction ratio (during special operation) (%) 35 to 45 16 to 25 42 to 52 ==================================

Here, the special operation is at the time of starting or at the time of load change. According to the present invention, the shaft power of the high-pressure pump 39 can be reduced as compared with the prior art, and the water extraction ratio from the middle stage of the high-pressure pump 39 is within a range in which there is no problem in terms of the pump function. A great effect can be obtained.

Next, an economical arrangement of the economizer when the economizer is divided into a high pressure, a medium pressure and a low pressure system will be described. For example, in the exhaust heat recovery boiler shown in FIG. 1, which is an embodiment of the present invention, the intermediate-pressure primary economizer 7 is on the downstream side of the exhaust gas flow from the low-pressure economizer 8, and the high-pressure primary economizer 6 is intermediate-pressure. After the heat exchange of the low-pressure economizer 8 disposed upstream of the medium-pressure primary economizer 7, since it is arranged on the downstream side of the exhaust gas flow from the primary economizer 7 and the low-pressure economizer 8, respectively. Heat exchange with the temperature-reduced exhaust gas 29 is performed in the intermediate-pressure primary economizer 7, and between the intermediate-pressure primary economizer 7 and the low-pressure economizer 8 arranged upstream of the high-pressure primary economizer 6. The heat exchange with the exhaust gas 29 whose temperature has decreased after the heat exchange is performed in the high-pressure primary economizer 6. Therefore, as shown in FIG. 2, the temperature difference between the feedwater temperature and the exhaust gas temperature at the outlet side of the medium-pressure primary economizer 7 is smaller than the temperature difference between the feedwater temperature and the exhaust gas temperature at the outlet side of the low-pressure economizer 8. The temperature difference between the feed water temperature on the outlet side of the high pressure primary economizer 6 and the exhaust gas temperature is smaller than the temperature difference between the feed water temperature on the outlet side of the medium pressure primary economizer 7 and the exhaust gas temperature. Therefore, it is necessary to increase the heat transfer area of the intermediate-pressure primary economizer 7 and the high-pressure primary economizer 6.

As shown in FIG. 4, the casing 28 of the exhaust heat recovery boiler is opened and viewed from above, and FIG. 5 is a view viewed from the side of the exhaust heat recovery boiler. The medium-pressure and low-pressure economizers are arranged, and the heat exchanger tube section 34 of the high-pressure primary economizer 6 (FIG. 1) and the heat exchanger tube section 37 of the intermediate-pressure primary economizer 7 (FIG. 1) are arranged. The high-pressure feed pipe 4a, the medium-pressure feed pipe 3a, and the low-pressure feed pipe 2a are connected to the feeder 32 and the feeder 30 of the heat transfer pipe portion 36 of the low-pressure economizer 8 (FIG. 1), respectively. The high-pressure economizer header 34 is connected by a high-pressure economizer connection pipe 35, the medium-pressure economizer header 32 is connected by a medium-pressure economizer connection pipe 33, and the low-pressure economizer header 3 is connected.
Numeral 0 is connected by a low-pressure economizer connecting pipe 31.

The feed water heat-exchanged in each economizer is sent out from the high-pressure feed pipe 4b, the medium-pressure feed pipe 3b and the low-pressure feed pipe 2b to the next flow path. In this case, the temperature distribution of the exhaust gas and the feedwater is as shown in FIG. 2, and the ratio of the number of heat transfer tubes in the direction orthogonal to the gas flow is high: medium pressure: low pressure = 100: 5 to 10 in order to effectively use the temperature difference. : Low-pressure economizer 6, medium-pressure primary economizer 7 and low-pressure economizer 8 so as to be 5 to 10
Install each heat transfer tube.

The heat transfer tube 36 of each of the economizers 6 to 8 shown in FIG.
Although there is a factor that increases the cost due to the manufacture of No. 38 and the provision of the exhaust gas bypass structure between the heat transfer tube groups, as shown in FIG. 6 or FIG. 7 (all viewed from the top of the boiler), By arranging and mixing the heat transfer tubes of the charcoal in series in a direction orthogonal to the gas flow for the number of heat transfer tubes corresponding to the heat transfer area of each pressure system, the above-mentioned problems such as the production cost can be solved.

FIG. 6 shows the relationship between the temperature of the feed water heated by the economizers 6 to 8 and the amount of heat exchange when the split high-, medium- and low-pressure feed water is divided into three parts as shown in FIG. 3
First, as for the medium-pressure primary economizer 7 and the low-pressure economizer 8, the temperature difference between the feedwater temperature on the feedwater outlet side and the exhaust gas temperature, which greatly affects the heat transfer area of the heat transfer tube, is shown in FIG. 2, exactly or almost the same as their temperature differences.

Next, as for the high-pressure primary economizer 6, the temperature difference at the feed water outlet side can be shifted to the higher temperature side of the exhaust gas as compared with the conventional one shown in FIG. The temperature difference between the feed water temperature and the exhaust gas temperature is much smaller than the decrease in the case of FIG. 2, so that the rate of increase in the heat transfer area of the high-pressure primary economizer 8 is also shown in FIG. It becomes smaller than the case.

The difference between the actual exhaust gas and the outlet feed water temperature of the high-pressure primary economizer 8 in a certain waste heat recovery boiler plant is shown in Table 2 below. [Table 2] ================================= Prior Art (FIG. 8) FIG. 3) −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Temperature difference between exhaust gas and high pressure outlet 15 ° 8.3 ° 12. 8 degrees ==================================

As shown in FIG. 7, instead of dividing the economizers 6 to 8 into three as shown in FIG. 6, the greater the number of divisions, the more the effect is obtained. Since the number of heat transfer tube groups of the low-pressure economizer increases, it is not economical, and usually the most economical is to divide into two to four.

As another embodiment of the present invention, in the configuration of the exhaust heat recovery boiler shown in FIG. 9, a high-pressure primary economizer 6 and an intermediate-pressure primary economizer 7 are shown in FIGS. 4, 6 and 7. Such a split arrangement structure may be adopted. Further, the high-pressure primary economizer 6 and the intermediate-pressure primary economizer 7 shown in FIG. 8 may have a split arrangement structure as shown in FIGS. 4, 6, and 7.

[0043]

According to the present invention, it is possible to reduce the power of auxiliary equipment and to use a single water supply pump and arrange it in a constant water supply temperature range without a large increase in the water extraction ratio. It is also effective for maintenance.

Further, the divisional arrangement of the economizer has the effect that the heat transfer area and the number of tube groups can be set economically.

[Brief description of the drawings]

FIG. 1 is a system diagram of an exhaust heat recovery boiler according to an embodiment of the present invention.

FIG. 2 is a temperature distribution diagram of feedwater of the exhaust heat recovery boiler according to the embodiment of the present invention.

FIG. 3 is a temperature distribution diagram of feedwater of an exhaust heat recovery boiler according to an embodiment of the present invention.

FIG. 4 is a top view showing an arrangement example of economizers of the exhaust heat recovery boiler according to the embodiment of the present invention.

FIG. 5 is a side view showing an arrangement example of a economizer of the exhaust heat recovery boiler according to the embodiment of the present invention.

FIG. 6 is a top view showing an example of the arrangement of the economizer of the exhaust heat recovery boiler according to the embodiment of the present invention.

FIG. 7 is a top view showing an example of the arrangement of the economizer of the exhaust heat recovery boiler according to the embodiment of the present invention.

FIG. 8 is a system diagram of a conventional heat recovery steam generator.

FIG. 9 is a system diagram of a conventional heat recovery steam generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Low-temperature water supply pipe 2a, 2b Low-pressure water supply pipe 3a, 3b Medium-pressure water supply pipe 4a, 4b High-pressure water supply pipe 5 Minimum flow pipe 6 High-pressure primary energy-saving device 7 Medium-pressure primary energy-saving device 8 Low-pressure energy-saving device 9 Low-pressure drum 10 Precipitation Pipe 11 Evaporator 12 Low-pressure main steam pipe 13 Medium-pressure secondary economizer 14 Medium-pressure drum 15 Medium-pressure downcomer 16 Medium-pressure evaporator 17 Medium-pressure superheater 18 Medium-pressure main steam pipe 18 Medium-pressure main steam pipe 19 High-pressure pipe Next-stage coal saver 20 High-pressure drum 21 High-pressure downcomer 22 High-pressure evaporator 23 High-pressure primary superheater 24 Desuperheater 25 High-pressure secondary superheater 26 High-pressure main steam pipe 27 Recirculation pipe 30, 32, 34 Heading 31, 33, 3
5 Connecting pipes 36, 37, 38 Heat transfer pipe section 39 High pressure water supply pump 46 Condenser 47 Condensate pump

Claims (6)

[Claims] 1. A heat transfer tube group provided in an exhaust gas flow path comprising two or more pressure systems, a water supply path for supplying water to a economizer in the heat transfer tube group of each pressure system, and a water saving passage of each pressure system. An exhaust heat recovery boiler provided with a steam-water separation drum supplied from a water heater, a branch water supply path branched from a water supply path to a low-pressure system, a high-pressure water supply pump provided in the branch water supply path, and a high-pressure water supply pump. A wastewater heat recovery boiler provided with a water supply path for supplying water discharged from a high pressure side to a high pressure side pressure system and a water supply path for supplying high pressure water pump intermediate stage extraction water to an intermediate pressure system. 2. The exhaust heat recovery according to claim 1, wherein a reheater for reheating the high-pressure steam after working using the steam obtained in the high-pressure system is provided in the exhaust gas passage. boiler. 3. The heat transfer tubes of the economizer of each pressure system having the number of heat transfer tubes corresponding to the heat transfer area of each pressure system are arranged in parallel or in series in a direction orthogonal to the exhaust gas flow direction in the exhaust gas passage. The exhaust heat recovery boiler according to claim 1, wherein the exhaust heat recovery boiler is disposed. 4. A high-pressure system economizer in which heat transfer tubes having substantially the same heat transfer area as a low-pressure system and a medium-pressure system economizer are arranged in parallel in a direction orthogonal to the exhaust gas flow direction in the exhaust gas flow path. 4. The heat transfer tube whose heat transfer area is substantially the same as the total heat transfer area of the medium / low pressure system economizer is arranged in series with the middle / low pressure system economizer. Waste heat recovery boiler. 5. A feedwater recirculation route for returning a part of high-temperature feedwater heat recovered by a economizer of a predetermined pressure system to a feedwater route to a low-pressure system on an upstream side of a branch feedwater route provided with a high-pressure feedwater pump. An exhaust heat recovery boiler according to any one of claims 1 to 4, further comprising: 6. A heat transfer tube group provided in an exhaust gas flow path composed of two or more pressure systems, a water supply path for supplying water to a economizer in the heat transfer tube group of each pressure system, and a water saving passage of each pressure system. In an exhaust heat recovery boiler equipped with steam-water separation drums supplied from a steam generator, the economizer is divided into one or more high-pressure economizers and one or more low-pressure economizers. A water supply path for supplying a portion of the feed water heated in step 1 to one or more high-pressure system economizers; a high-pressure water pump provided in a water supply path to the high-pressure economizer; And a water supply path for supplying water to the low-pressure system economizer, and heat transfer tubes of economizers of each pressure system with different cross-sectional areas are arranged in parallel or in series in the direction orthogonal to the exhaust gas flow direction in the exhaust gas flow path. An exhaust heat recovery boiler characterized by being arranged.