Waste heat utilization system of combined cycle gas turbine power plant waste heat boiler

Abstract

The utility model provides a combined cycle gas turbine power plant waste heat boiler waste heat utilization system which comprises a waste heat boiler low-pressure economizer, a water-water heat exchanger and a lithium bromide unit. The water-water heat exchanger is further connected with a water supply branch of the lithium bromide unit and a water return branch of the lithium bromide unit. By arranging the water-water heat exchanger, hot water at the outlet of the low-pressure economizer of the waste heat boiler is led to the water-water heat exchanger, and hot water for the lithium bromide unit is heated to the target temperature in the water-water heat exchanger.

Description

Technical Field

[0001] The utility model belongs to the technical field of waste heat utilization, and in particular relates to a waste heat utilization system of a waste heat boiler of a combined cycle gas turbine power plant. Background Art

[0002] The statements in this section merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] For 9F-class gas turbine power plants, the exhaust temperature of the waste heat boiler is about 90°C. Reducing the exhaust temperature of the waste heat boiler and recovering the waste heat from the boiler exhaust can improve the efficiency of the combined cycle unit and generate greater economic benefits.

[0004] The existing technology extracts hot water from the outlet of the waste heat boiler low-pressure economizer to the hot water type lithium bromide unit as the driving heat source of the hot water type lithium bromide unit, and the hot water type lithium bromide unit can be used for summer cooling.

[0005] The existing technology directly extracts hot water from the outlet of the waste heat boiler low-pressure economizer to supply it to the hot water type lithium bromide unit, which has the following disadvantages:

[0006] The ideal hot water temperature for hot water type lithium bromide units is 90-145℃. The outlet hot water temperature of the waste heat boiler low-pressure economizer is between 140-150℃ according to the load of the unit. The hot water temperature is low when the unit load is low, and the hot water temperature gradually increases as the unit load increases. If the hot water temperature supplied to the lithium bromide unit is between 145-150℃, the lithium bromide unit will work at this temperature for a long time, and there is a risk of crystallization, which will cause the lithium bromide unit to fail to work normally. Summary of the invention

[0007] In order to solve the above problems, the utility model proposes a waste heat utilization system for a waste heat boiler of a combined cycle gas turbine power plant. The utility model arranges a water-to-water heat exchanger to lead the hot water at the outlet of a low-pressure economizer of the waste heat boiler to the water-to-water heat exchanger, and heats the hot water for the lithium bromide unit to a target temperature in the water-to-water heat exchanger.

[0008] According to some embodiments, the utility model adopts the following technical solutions:

[0009] A waste heat utilization system for a waste heat boiler in a combined cycle gas turbine power plant comprises a low-pressure economizer for the waste heat boiler, a water-to-water heat exchanger and a lithium bromide unit, wherein the outlet of the low-pressure economizer for the waste heat boiler is connected to the water-to-water heat exchanger through a pipeline, and the water-to-water heat exchanger is also connected to a water supply branch of the lithium bromide unit and a return branch of the lithium bromide unit.

[0010] In the above scheme, the hot water at the outlet of the low-pressure economizer of the waste heat boiler is introduced to the water-to-water heat exchanger, and the hot water for the lithium bromide unit is heated in the water-to-water heat exchanger.

[0011] As an optional implementation, the outlet hot water of the waste heat boiler low-pressure economizer is supplied to the low-pressure steam drum via an electric stop valve and a check valve.

[0012] As a further implementation, a first branch line is further provided in front of the check valve, and the first branch line is connected to the inlet pipe of the low-pressure economizer of the waste heat boiler through a stop valve, a flow meter, a regulating valve, and a check valve in sequence.

[0013] As a further implementation, a second branch is provided in front of the check valve, and the second branch is connected to the inlet pipe of the waste heat boiler low-pressure economizer through the stop valve, flow meter, regulating valve, water-to-water heat exchanger and check valve in sequence.

[0014] As a further implementation manner, the first branch circuit and the second branch circuit are connected in parallel.

[0015] As a further embodiment, a recirculation pump is connected in series between the first branch line and the check valve, and the recirculation pump includes three branches, each of which includes an electric stop valve, a Y-type filter, a low-pressure economizer recirculation pump, a check valve and a stop valve connected in series.

[0016] As a further implementation, the recirculation pump is connected in series between the second branch line and the check valve.

[0017] As an optional implementation, the inlet pipe of the waste heat boiler low-pressure economizer is connected to a condensate water pipeline.

[0018] As a further implementation, a stop valve is provided at the inlet pipe of the waste heat boiler low-pressure economizer.

[0019] As a further implementation, the stop valve is an electric stop valve.

[0020] Compared with the prior art, the beneficial effects of the utility model are:

[0021] The system provided by the utility model can provide hot water with stable temperature to the hot water type lithium bromide unit, solving the drawback of the prior art that the hot water supply temperature varies with the load of the unit, and solving the problem that the lithium bromide unit crystallization cannot work normally when the hot water temperature is over-temperature.

[0022] The utility model arranges a water-to-water heat exchanger at the outlet of a recirculation pump of a low-pressure economizer, and supplies hot water to the inlet of the low-pressure economizer after being pressurized by the recirculation pump. There is no need to arrange an additional pressure pump, and the system is simple.

[0023] The utility model has wide applicability and can be used for refrigeration and heating; the waste heat of exhaust gas from the waste heat boiler is recovered for external refrigeration or heating, which can reduce the exhaust gas temperature of the waste heat boiler and improve the efficiency of the combined cycle unit.

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0026] Figure 1 It is a structural diagram of the utility model.

[0027] Among them, 1. Water supply branch of lithium bromide unit, 2. Return branch of lithium bromide unit, 3. Water-to-water heat exchanger, 4. Low-pressure economizer, 5. Low-pressure steam drum, 6. Check valve, 7. Electric stop valve, 8. Y-type filter, 9. Low-pressure economizer recirculation pump, 10. Control valve, 11. Stop valve, 12. Flow meter.

[0028] A. Smoke direction. DETAILED DESCRIPTION

[0029] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the utility model. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] In the absence of conflict, the embodiments in this application and the features in the embodiments may be combined with each other.

[0033] Embodiment 1

[0034] like Figure 1 As shown, a waste heat utilization system of a waste heat boiler in a combined cycle gas turbine power plant includes a waste heat boiler low-pressure economizer 4, a water-to-water heat exchanger 3 and a lithium bromide unit, wherein the outlet of the waste heat boiler low-pressure economizer 4 is connected to the water-to-water heat exchanger 3 through a pipeline, and the water-to-water heat exchanger 3 is also connected to a water supply branch 1 of the lithium bromide unit and a return water branch 2 of the lithium bromide unit.

[0035] In this embodiment, the hot water at the outlet of the low-pressure economizer 4 of the waste heat boiler is supplied to the low-pressure drum 5 through the electric stop valve 7 and the check valve 6 .

[0036] In this embodiment, a first branch line and a second branch line are further provided before the check valve 6. The first branch line is connected to the inlet pipe of the waste heat boiler low-pressure economizer 4 through the stop valve 11, the flow meter 12, the regulating valve 10, and the check valve 6 in sequence;

[0037] The second branch line is connected to the inlet pipeline of the waste heat boiler low-pressure economizer 4 through the stop valve 11, the flow meter 12, the regulating valve 10, the water-to-water heat exchanger 3, and the check valve 6 in sequence.

[0038] In this embodiment, a recirculation pump is connected in series between the first branch branch, the second branch branch and the check valve 6, and the recirculation pump includes three branches, each of which includes an electric stop valve 7, a Y-type filter 8, a low-pressure economizer recirculation pump 9, a check valve 6 and a stop valve 11 connected in series.

[0039] In this embodiment, the inlet pipe of the waste heat boiler low-pressure economizer 4 is connected to a condensate water pipeline, and an electric stop valve 7 is provided at the inlet pipe.

[0040] The working process of this embodiment includes:

[0041] The condensate water is supplied to the low-pressure economizer 4 of the waste heat boiler through the check valve 6 and the electric stop valve 7, and the condensate is heated to 140-150℃ in the low-pressure economizer 4. The hot water at the outlet of the low-pressure economizer 4 is supplied to the low-pressure drum 5 through the electric stop valve 7 and the check valve 6. A path of hot water is drawn out before the check valve 6, and after being pressurized by the low-pressure economizer recirculation pump 9, it is divided into two paths: one path is connected to the inlet pipeline of the low-pressure economizer 4 through the electric stop valve 7, the flow meter 12, the electric regulating valve 10, and the check valve 6; the other path is connected to the inlet pipeline of the low-pressure economizer 4 through the electric stop valve 7, the flow meter 12, the electric regulating valve 10, the water-to-water heat exchanger 3, and the check valve 6.

[0042] like Figure 1 As shown, the three branches of the low-pressure economizer recirculation pump are two-for-one and standby, and each branch includes an electric stop valve 7, a Y-type filter 8, a low-pressure economizer recirculation pump 9, a check valve 6 and a stop valve.

[0043] The water-to-water heat exchanger 3 is connected to the lithium bromide hot water supply and return pipelines at the same time.

[0044] Most of the hot water at the outlet of the low-pressure economizer is supplied to the low-pressure drum 5, and a small part is drawn out and pressurized by the recirculation pump to be mixed with the condensate. The function of the low-pressure economizer recirculation pump is to pressurize a part of the hot water (140-150℃) at the outlet of the low-pressure economizer and lead it to the inlet of the low-pressure economizer. The hot water is mixed with the condensate and supplied to the low-pressure economizer. The temperature of the condensate is relatively low, about 20-30℃. If the low-temperature condensate directly enters the low-pressure economizer, it will cause low-temperature corrosion of the low-pressure economizer.

[0045] This technology sets the water-to-water heat exchanger at the outlet of the low-pressure economizer recirculation pump, and does not require an additional booster pump, so the system is simple (if the water-to-water heat exchanger is not set at the outlet of the low-pressure economizer recirculation pump, and a separate hot water line is introduced from the low-pressure economizer outlet to the water-to-water heat exchanger, since the pressure of the low-pressure economizer inlet water is higher than the outlet water pressure, a separate booster pump is required to pressurize the water before it can be returned to the low-pressure economizer inlet).

[0046] In the water-to-water heat exchanger, the 68°C hot water used by the lithium bromide unit is heated to the target temperature (between 90-145°C) with the 140-150°C hot water at the outlet of the low-pressure economizer. The hot water meeting the target temperature is supplied to the hot water type lithium bromide unit for refrigeration.

[0047] This embodiment can provide hot water with stable temperature to the hot water type lithium bromide unit, solving the problem of the hot water supply temperature varying with the load of the unit in the prior art, and solving the problem that the lithium bromide unit crystallization cannot work normally when the hot water temperature exceeds 145°C.

[0048] This technology is not only suitable for heating hot water for lithium bromide units, but also for heating hot water for heating networks: in summer, hot water for lithium bromide is used for cooling, and in winter, hot water for heating networks is used for residential heating. If the hot water from the heating network is used for industrial heating, it can operate all year round.

[0049] When cooling and heating are not required, close the electric stop valve upstream of the water-to-water heat exchanger and let the hot water flow through another branch of the recirculation pump outlet.

[0050] The above description is only the preferred embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the utility model without creative labor shall be included in the protection scope of the utility model.

Claims

1. A waste heat utilization system for a waste heat boiler in a combined cycle gas turbine power plant, characterized in that: It includes a waste heat boiler low-pressure economizer, a water-to-water heat exchanger and a lithium bromide unit, wherein the outlet of the waste heat boiler low-pressure economizer is connected to the water-to-water heat exchanger through a pipeline, and the water-to-water heat exchanger is also connected to a water supply branch of the lithium bromide unit and a return branch of the lithium bromide unit.

2. A waste heat utilization system for waste heat boilers in combined cycle gas turbine power plants as claimed in claim 1, characterized in that: The outlet hot water of the waste heat boiler low-pressure economizer is supplied to the low-pressure drum through an electric stop valve and a check valve.

3. The waste heat utilization system of the waste heat boiler of a combined cycle gas turbine power plant as claimed in claim 2, characterized in that: A first branch line is also arranged in front of the check valve, and the first branch line is connected to the inlet pipeline of the low-pressure economizer of the waste heat boiler through a stop valve, a flow meter, a regulating valve and a check valve in sequence.

4. A waste heat utilization system for waste heat boiler of a combined cycle gas turbine power plant as claimed in claim 3, characterized in that: A second branch is also provided in front of the check valve, and the second branch is connected to the inlet pipe of the low-pressure economizer of the waste heat boiler through the stop valve, flow meter, regulating valve, water-to-water heat exchanger and check valve in sequence.

5. A waste heat utilization system for waste heat boilers in combined cycle gas turbine power plants as claimed in claim 4, characterized in that: The first branch circuit and the second branch circuit are connected in parallel.

6. The waste heat utilization system of a waste heat boiler of a combined cycle gas turbine power plant as claimed in claim 3, characterized in that: A recirculation pump is connected in series between the first branch line and the check valve. The recirculation pump includes three branches, each of which includes an electric stop valve, a Y-type filter, a low-pressure economizer recirculation pump, a check valve and a stop valve connected in series.

7. The waste heat utilization system of a waste heat boiler of a combined cycle gas turbine power plant as claimed in claim 4, characterized in that: A recirculation pump is connected in series between the second branch line and the check valve.

8. The waste heat utilization system of a waste heat boiler of a combined cycle gas turbine power plant as claimed in claim 1, characterized in that: The inlet pipe of the waste heat boiler low-pressure economizer is connected with a condensate water pipeline.

9. A waste heat utilization system for waste heat boilers in combined cycle gas turbine power plants as claimed in claim 8, characterized in that: A stop valve is provided at the inlet pipe of the waste heat boiler low-pressure economizer.

10. A waste heat utilization system for waste heat boilers in combined cycle gas turbine power plants as claimed in claim 9, characterized in that: The stop valve is an electric stop valve.

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