Back pressure gas turbine waste heat boiler low pressure feed water system

Abstract

The present application relates to a kind of back pressure gas turbine waste heat boiler low-pressure feedwater system, belong to boiler equipment technical field.The present application includes low-pressure steam drum, low-pressure economizer, vacuum deaerator, vacuum deaerator inlet is connected with desalted water source by deaeration inlet pipeline, vacuum deaerator outlet is connected with the inlet of low-pressure economizer by deaeration outlet pipeline, economizer outlet pipeline is connected with low-pressure steam drum by deaeration head, deaeration outlet pipeline is provided with booster pump, booster pump inlet is communicated with vacuum deaerator outlet while outlet is communicated with the inlet of low-pressure economizer, booster pump outlet is also connected with deaeration inlet pipeline by the regulating valve bypass provided with regulating valve.The present application uses regulating valve bypass to send back surplus flow to vacuum deaerator by low-pressure feedwater, and this part of surplus flow circulates between booster pump and vacuum deaerator, thereby solve the technical problem that low-pressure feedwater system produces pressure when low load waste heat boiler.

Description

Technical Field

[0001] This invention relates to a low-pressure feedwater system for a back-pressure gas turbine waste heat boiler, belonging to the technical field of boiler equipment. Background Technology

[0002] Steam and hot water from the back-pressure gas turbine waste heat boiler are typically not recycled after being fed to users outside the plant area. In this case, the waste heat boiler needs to be replenished with demineralized water. Because the oxygen content of the demineralized water is as high as 7-8 mg / L, failing to meet specifications, and also causing significant oxygen corrosion damage to the boiler's low-pressure feedwater system, a vacuum deoxygenation device is required in the low-pressure feedwater system to perform preliminary deoxygenation of the demineralized water. The existing low-pressure feedwater system is shown in the attached diagram. Figure 1 As shown, the demineralized water mixes with hot water drawn from the low-pressure economizer 2 in the deoxygenation inlet pipe 4, and then enters the vacuum deoxygenation device 3 for deoxygenation. The deoxygenated demineralized water is then sent to the low-pressure economizer 2 by the booster pump 13 for heating, and then enters the low-pressure steam drum 1 through the economizer outlet pipe 6 and the deoxygenation head 7. In the above low-pressure feedwater system, the booster pump 13 is conventionally a constant-speed pump. When the waste heat boiler section or under low load is running, the opening of the economizer outlet regulating valve 8 decreases, while the feedwater flow rate delivered by the booster pump 13 remains unchanged, which leads to pressure buildup in the low-pressure feedwater system. When the low-pressure feedwater system experiences back pressure, the design pressure of the heating system 11 is relatively low compared to the waste heat boiler side, which inevitably poses a safety hazard to the operation of the heating system 11. At the same time, the vent valve at the outlet of the low-pressure economizer 2 also needs to be adjusted to a higher setting value, which will have an adverse effect on the low-pressure feedwater system. If the demineralized water heating regulating valve 17 is fully opened and the excess flow is sent back to the vacuum deaerator 3 through the second heating pipeline 12, the water temperature inside the vacuum deaerator 3 will rise, affecting the deaeration effect. Summary of the Invention

[0003] This invention primarily addresses the technical problem of pressure buildup in the low-pressure feedwater system of a waste heat boiler during low-load operation, and provides a back-pressure gas turbine waste heat boiler low-pressure feedwater system that prevents pressure buildup during low-load operation.

[0004] The present application is mainly solved by the following technical scheme: the low-pressure steam drum, the low-pressure economizer, the vacuum deaerating device, the deaerating inlet pipeline of the vacuum deaerating device is connected with the desalted water source, the deaerating outlet pipeline of the vacuum deaerating device is connected with the inlet of the low-pressure economizer, the outlet of the low-pressure economizer is provided with the economizer outlet pipeline, the outlet of the economizer outlet pipeline is connected with the low-pressure steam drum through the deaerating head, the low-pressure economizer is provided with the hot water outlet, the hot water outlet is connected with the heat supply system through the first heat supply pipeline and connected with the deaerating inlet pipeline through the second heat supply pipeline, the heat supply system is connected with the inlet of the low-pressure economizer through the heat network circulating pump, the deaerating outlet pipeline is provided with the booster pump, the inlet of the booster pump is communicated with the outlet of the vacuum deaerating device and the outlet is communicated with the inlet of the low-pressure economizer, and the booster pump is characterized by that the outlet of the booster pump is connected with the deaerating inlet pipeline through the bypass provided with the regulating valve, the flow of the bypass is controlled by the regulating valve according to the flow and pressure of the economizer outlet pipeline, and the low-pressure feed water entering the bypass forms a circulation between the vacuum deaerating device and the booster pump.

[0005] Preferably, the regulating valve is controlled by the DCS control system, and the regulating valve is opened when the flow of the economizer outlet pipeline is reduced to cause the low-pressure feed water pressure to be greater than the set working pressure.

[0006] Preferably, the opening degree of the regulating valve is interlocked controlled by the DCS control system according to the opening degree of the economizer outlet regulating valve.

[0007] Preferably, the booster pump is provided with two groups connected in parallel.

[0008] The present application has the following advantages:

[0009] In the present application, the bypass is provided at the outlet of the booster pump. When the waste heat boiler is in low load operation, the flow of the economizer outlet pipeline is reduced to cause the low-pressure feed water pressure to be increased to generate pressure retention, and the regulating valve can be opened to send the excess flow of the low-pressure feed water back to the vacuum deaerating device through the bypass, and the excess flow circulates between the booster pump and the vacuum deaerating device, so that the low-pressure feed water system is prevented from generating pressure retention, and the operation safety of the heat supply system is ensured.

[0010] In the present application, the circulating water returned to the vacuum deaerating device through the bypass is not heated and increased in temperature by the low-pressure economizer, and the technical problem that the excess flow is sent back to the vacuum deaerating device through the second heat supply pipeline to cause the water temperature in the vacuum deaerating device to be increased and the deaerating effect to be affected in the prior art is avoided.

[0011] Further, the regulating valve is automatically controlled by the DCS control system, and the degree of automation is high.

[0012] Further, the opening and closing of the regulating valve is interlocked controlled by the DCS control system according to the opening degree of the economizer outlet regulating valve, and the flow of the regulating valve bypass can timely respond to the flow change of the economizer outlet pipeline, so as to keep the stability of the low-pressure feedwater system working pressure, and make the system run safely and reliably.

[0013] Further, the booster pump has two groups, one of which is in normal operation and the other is standby, when the running booster pump needs to be repaired and replaced, the standby booster pump is put into operation, so as to not affect the normal operation of the low-pressure feedwater system.

[0014] Therefore, the present application solves the technical problem of pressure build-up of the low-pressure feedwater system at low load of the waste heat boiler in the prior art, and has the advantages of simple system, stable operation, and strong applicability to unit load. BRIEF DESCRIPTION OF DRAWINGS

[0015] FIG. 1 is a schematic diagram of the prior art; Figure 1 is a schematic diagram of the prior art;

[0016] FIG. 2 is a schematic diagram of a preferred embodiment of the present application. Figure 2

[0017] BRIEF DESCRIPTION OF DRAWINGS Specifically, the present application comprises a low-pressure steam drum 1, a low-pressure economizer 2, and a vacuum deaerator 3.

[0018] The technical solutions of the present application will be further specifically described below by examples in combination with the drawings.

[0019] Example 1: As shown in FIG. 1, the present application comprises a low-pressure steam drum 1, a low-pressure economizer 2, and a vacuum deaerator 3. Figure 2 The inlet of the vacuum deaerator 3 is connected with a deaerated water source through a deaerated inlet pipeline 4, and the outlet of the vacuum deaerator 3 is connected with the inlet of the low-pressure economizer 2 through a deaerated outlet pipeline 5.

[0020] The outlet of the low-pressure economizer 2 is provided with an economizer outlet pipeline 6, and the outlet of the economizer outlet pipeline 6 is connected with the low-pressure steam drum 1 through a deaerated head 7.

[0021]

[0022] ​​The low-pressure economizer 2 is provided with a hot water outlet 9, the hot water outlet 9 is connected with a heat supply system 11 through a first heat supply pipeline 10, the outlet of the heat supply system 11 is connected with the inlet of the low-pressure economizer 2 through a heat network circulating pump 18;

[0023] The hot water outlet 9 is also connected with the deaerating inlet pipeline 4 through a second heat supply pipeline 12, a desalted water heating regulating valve 17 is arranged on the second heat supply pipeline 12;

[0024] A booster pump 13 is arranged on the deaerating outlet pipeline 5, the inlet of the booster pump 13 is communicated with the outlet of the regulating valve bypass 15, and the outlet is communicated with the inlet of the low-pressure economizer 2, the outlet of the booster pump 13 is also connected with the deaerating inlet pipeline 4 through the regulating valve bypass 15 provided with the regulating valve 14, the feed water from the outlet of the booster pump 13 into the regulating valve bypass 15 returns to the vacuum deaerating device 3 and forms a circulation between the vacuum deaerating device 3 and the booster pump 13;

[0025] The flow of the regulating valve bypass 15 is controlled by the regulating valve 14 according to the flow and pressure of the economizer outlet pipeline 6;

[0026] The regulating valve 14 is connected with the economizer outlet regulating valve 8 and the DCS control system 16, the opening and closing of the regulating valve 14 is controlled by the DCS control system 16 according to the opening degree of the economizer outlet regulating valve 8, the opening degree parameter of the economizer outlet regulating valve 8 is converted into a standard signal and input into a logic controller, and a control signal is generated through logic operation to control the opening and closing of the regulating valve 14;

[0027] The booster pump 13 is arranged in two groups in parallel, one is used and the other is standby.

[0028] When the waste heat boiler is partially or lowly loaded, the DCS control system 16 monitors the flow and pressure of the economizer outlet pipeline 6, collects the opening degree parameter of the economizer outlet regulating valve 8, converts the parameter into a standard signal and inputs into a logic controller, generates a control signal through logic operation and controls the regulating valve 14 to open through an actuator, after the regulating valve 14 is opened, the excess low-pressure feed water from the outlet of the booster pump 13 returns to the vacuum deaerating device 3 through the regulating valve bypass 15 and circulates between the vacuum deaerating device 3 and the booster pump 13, and the low-pressure feed water system can stably operate at a normal working pressure.

[0029] Of course, the above-mentioned drawings and embodiments are only used for explaining and illustrating the present application, and cannot be used as improper limitation of the present application. Any technical solution obtained by equivalent adjustment and change according to the present application by those skilled in the art falls into the protection scope of the present application.

Claims

1. A waste heat boiler low-pressure feedwater system, comprising a low-pressure steam drum (1), a low-pressure economizer (2), a vacuum deaerator (3), the vacuum deaerator (3) inlet being connected with a deaerated water source through a deaerated water inlet pipeline (4), the vacuum deaerator (3) outlet being connected with the low-pressure economizer (2) inlet through a deaerated water outlet pipeline (5), the low-pressure economizer (2) outlet being provided with an economizer outlet pipeline (6), the economizer outlet pipeline (6) outlet being connected with the low-pressure steam drum (1) through a deaerated water head (7), the low-pressure economizer (2) being provided with a hot water outlet (9), the hot water outlet (9) being connected with a heat supply system (11) through a first heat supply pipeline (10) and being connected with the deaerated water inlet pipeline (4) through a second heat supply pipeline (12), the heat supply system (11) being connected with the low-pressure economizer (2) inlet through a heat network circulating pump (18), the deaerated water outlet pipeline (5) being provided with a booster pump (13), the booster pump (13) inlet being communicated with the vacuum deaerator (3) outlet and the booster pump (13) outlet being communicated with the low-pressure economizer (2) inlet, characterized in that, The booster pump (13) outlet is also connected with the deaerating inlet pipeline (4) through a regulating valve bypass (15) provided with a regulating valve (14), the flow of the regulating valve bypass (15) is controlled by the regulating valve (14) according to the flow and pressure of the economizer outlet pipeline (6), the low-pressure feed water entering the regulating valve bypass (15) forms a circulation between the vacuum deaerating device (3) and the booster pump (13), the regulating valve (14) is controlled by a DCS control system (16), the regulating valve (14) is opened when the low-pressure feed water pressure is greater than the set working pressure due to the flow reduction of the economizer outlet pipeline (6), the opening of the regulating valve (14) is interlocked controlled by the DCS control system (16) according to the opening of the economizer outlet regulating valve (8), and the economizer outlet regulating valve (8) is arranged in the economizer outlet pipeline (6).

2. A low-pressure feedwater system for a waste heat boiler according to claim 1, characterized in that The booster pump (13) is arranged in two groups in parallel connection.

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