Control system for hydraulic turbine power generation system with redundant flow energy recovery

Abstract

The present application relates to a control system for a hydraulic turbine power generation system for redundant flow energy recovery, wherein the hydraulic turbine power generation system comprises a deaerator (E1), a boiler feed pump (E2), a hydraulic turbine generator set (E4, E5), a recirculation valve (V3), and a first pipeline (T1), a second pipeline (T2), a third pipeline (T3), a fourth pipeline (T4), and a fifth pipeline (T5) connecting these devices, and a control system comprising: a distributed computer controller DCS and a pressure transmitter (PT3), which sends a control signal to a user end based on an input signal and a preset algorithm. The distributed computer controller DCS receives a pressure signal from the pressure transmitter (PT3), and divides the operation of the hydraulic turbine power generation system into three operation modes, namely, the first operation mode, the second operation mode, and the third operation mode are switched by opening / closing a valve in the system, and the third pipeline (T3) is only connected in the third operation mode to enable the hydraulic turbine generator set to operate and generate electricity.

Description

Technical Field

[0001] The present application relates to energy recovery and utilization in the production process of a power plant, and in particular, to a hydraulic turbine power generation system and a control system thereof for energy recovery of redundant flow working medium downstream of a boiler feed pump in a power plant. Background Art

[0002] The main engine of a thermal power plant or cogeneration plant includes boilers, steam turbines and generators. It uses coal, oil or gas as the power source and the working medium circulation, mainly water, as the driving force to make the steam turbine generator set generate electricity, contributing about 60% of the electricity to the national grid. Cogeneration plants can use waste heat to provide steam for industrial users such as petrochemical plants, and also provide heating for residents.

[0003] The boiler feed pump provides the working medium to the boiler or the working medium circulates outside the unit. The boiler feed pump has its inherent head-flow characteristic (curve). When designing and selecting, it should match the pressure-flow required for the boiler operation, that is, the head-flow of the boiler feed pump is slightly larger than the pressure-flow required for the boiler operation. However, in actual operation, the power supply of the steam turbine generator set of the power plant is controlled by the grid dispatch. As the power supply decreases, the amount of working medium required by the boiler decreases. The difference between the flow provided by the boiler feed pump and the flow required by the boiler can be called redundant flow. In order to ensure the safe operation of the boiler feed pump, the redundant flow traditionally needs to be released by configuring the boiler feed pump recirculation system, that is, the system returns part of the high-temperature and high-pressure water at the outlet of the boiler feed pump to the deaerator after reducing the pressure through the recirculation valve, ensuring that the actual operating flow of the boiler feed pump at any time is not lower than the minimum flow condition requirement, and consuming part of the energy to ensure the safe and stable operation of the boiler feed pump during startup, shutdown and rapid adjustment.

[0004] In accordance with the national strategy of achieving carbon peak and carbon neutrality goals, the country gives priority to the development of non-fossil energy, such as photovoltaic power generation, wind power, hydropower, and nuclear power, which has enabled traditional thermal power units to gradually develop towards large capacity, high parameters and participation in deep peak regulation. More and more units have undergone flexibility modifications, making the recirculation valve open more and more frequently and for longer periods of time. Especially at night when electricity consumption is low, the units are in low-load conditions and need to open the recirculation valve for a long time, so more and more energy is consumed.

[0005] Therefore, the problem of how to recover the redundant flow of the boiler water supply system needs to be solved urgently. Summary of the invention

[0006] The technical problem to be solved by the present application is to achieve energy conservation and emission reduction by recycling the redundant flow at the outlet of the boiler feed pump when the generator set of a thermal power plant or a cogeneration power plant is running at low load.

[0007] To solve the above technical problems, according to one aspect of the present application, a hydraulic turbine power generation system for redundant flow energy recovery is provided, comprising: a boiler feed pump, comprising an inlet and an outlet, through which a liquid working medium is provided to a power plant boiler at a predetermined head and flow rate; a turbine, comprising an inlet, an outlet, an impeller and a rotating shaft, wherein the inlet of the turbine is connected to the outlet fluid of the boiler feed pump in a fluid-communicating manner; a generator, wherein the rotating shaft of the generator is connected to the rotating shaft of the turbine through a coupling; a deaerator, comprising a plurality of working medium inlets, a working medium outlet and at least one exhaust port, wherein at least one of the plurality of working medium inlets is connected to the outlet fluid of the turbine, and the working medium outlet of the deaerator is connected to the inlet fluid of the boiler feed pump in a fluid-communicating manner. The turbine receives the working medium of the predetermined redundant flow rate from the boiler feed pump, absorbs the pressure energy of the working medium, drives the rotating shaft of the turbine and drives the rotating shaft of the generator to rotate to generate electricity. The turbine generates electricity using only the predetermined redundant flow rate of the boiler feed pump.

[0008] According to an embodiment of the present application, the hydraulic turbine power generation system for redundant flow energy recovery may also include a main high-pressure pipeline leading from the outlet of the boiler feed water pump to the boiler, and a check valve, a gate valve, and a flow measuring device arranged in sequence on the main high-pressure pipeline.

[0009] According to an embodiment of the present application, the hydraulic turbine power generation system for redundant flow energy recovery may further include a boiler economizer, and the main pipeline may lead to the boiler through the boiler economizer.

[0010] According to an embodiment of the present application, the working medium outlet of the deaerator is fluidly connected to the inlet fluid of the boiler feed pump and may include a first pipeline and a pressure sensor, a gate valve, and a flow measurement device sequentially arranged on the first pipeline.

[0011] According to an embodiment of the present application, the inlet of the turbine is fluidly connected to the outlet of the boiler feed pump and may include a third pipeline and a pressure regulating valve and a gate valve disposed on the third pipeline.

[0012] According to an embodiment of the present application, at least one of the plurality of working medium inlets connected to the outlet fluid of the turbine may include a fifth pipeline and an isolation valve and a check valve disposed on the fifth pipeline.

[0013] According to an embodiment of the present application, a hydraulic turbine power generation system for redundant flow energy recovery may also include a second pipeline fluidically connecting the outlet of a boiler feed water pump and one of the multiple working medium inlets of a deaerator, as well as a pre-recirculation isolation valve, a recirculation valve, a post-recirculation isolation valve, and a check valve arranged on the second pipeline.

[0014] According to an embodiment of the present application, the boiler feed water pump may be a multi-stage centrifugal impeller series combined feed water pump.

[0015] According to an embodiment of the present application, the electricity generated by the generator may be integrated into the factory power grid through a transformer.

[0016] According to an embodiment of the present application, the power plant boiler can provide steam power for the peak-shaving steam turbine generator set.

[0017] According to an embodiment of the present application, the working medium may be treated water and necessary chemicals dissolved in the water.

[0018] According to an embodiment of the present application, a hydraulic turbine power generation system for redundant flow energy recovery has a first operating mode, a second operating mode and a third operating mode under different operating conditions, and the first to third operating modes are switched by opening / closing valves in the system.

[0019] According to an embodiment of the present application, in the first operating mode, the boiler feed pump only delivers working medium to the boiler of the power plant; in the second operating mode, the pressure regulating valve on the third pipeline is closed, and the recirculation valve on the second pipeline is opened, so that the boiler feed pump can deliver working medium to the boiler of the power plant and at the same time, it can divert part of the flow through the recirculation valve on the second pipeline to maintain the safe and stable operation of the boiler feed pump; in the third operating mode, the pressure regulating valve on the third pipeline is opened, and the recirculation valve on the second pipeline is closed, so that the boiler feed pump can deliver working medium to the boiler of the power plant and at the same time, it can provide redundant flow of working medium to the turbine through the third pipeline and drive the generator to generate electricity to recover the pressure energy of the working medium.

[0020] According to another aspect of the present application, a control system for a hydraulic turbine power generation system for redundant flow energy recovery is provided. The hydraulic turbine power generation system for redundant flow energy recovery includes a deaerator for collecting various working media and deoxidizing and degassing them, a boiler feed pump for providing working media to the boiler of a power plant, a hydraulic turbine generator set utilizing the redundant flow of the boiler feed pump, a recirculation valve for overpressure protection, and a first pipeline connecting the outlet of the deaerator to the inlet of the boiler feed pump, a second pipeline connecting the outlet of the boiler feed pump to the inlet of the deaerator via the recirculation valve, a third pipeline connecting the outlet of the boiler feed pump via the inlet of the hydraulic turbine of the hydraulic turbine generator set, a fourth pipeline connecting the outlet of the boiler feed pump to the boiler of the power plant, and a fifth pipeline connecting the outlet of the hydraulic turbine of the hydraulic turbine generator set to the inlet of the deaerator. The control system includes: a distributed computer controller DCS, which sends control signals to a user end based on input signals and preset algorithms and communicates with a main control room of the power plant; and a pressure transmitter, which outputs a pressure signal of the outlet of the boiler feed pump to the distributed computer controller DCS. The distributed computer controller DCS receives the pressure signal of the outlet of the boiler feed water pump outputted by the pressure transmitter, and the distributed computer controller DCS divides the received pressure signal of the outlet of the boiler feed water pump into three operation modes, namely, the first operation mode, the second operation mode and the third operation mode, and the first to third operation modes are switched by opening / closing the valve in the system. The distributed computer controller DCS conducts the third pipeline only in the third operation mode, and enables the hydraulic turbine generator set to operate and generate electricity.

[0021] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include a first pressure transmitter disposed at the outlet of the deaerator, a second pressure transmitter disposed at the inlet of the boiler feed pump, a third pressure transmitter disposed at the outlet of the boiler feed pump, a fourth pressure transmitter disposed at the inlet of the hydraulic turbine, a fifth pressure transmitter disposed at the outlet of the hydraulic turbine, and a sixth pressure transmitter disposed at the inlet of the power plant boiler. The distributed computer controller DCS receives the pressure signals from the above pressure transmitters, and in combination with the pressure signals from the pressure transmitters, comprehensively judges the operation status of the hydraulic turbine power generation system for redundant flow energy recovery according to a predetermined algorithm, and determines its next operation step.

[0022] According to an embodiment of the present application, the first operating mode may be an operating mode when the load of the steam turbine generator set of a power plant is above 70% of the design load, the second operating mode may be an operating mode when the load of the steam turbine generator set of a power plant is between 60% and 70% of the design load, and the third operating mode may be an operating mode when the load of the steam turbine generator set of a power plant fluctuates around 40% to 50% of the design load, and the third operating mode may also include deep peak regulation to a lower operating mode that may occur based on the scheduling of the power grid.

[0023] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include a pressure regulating valve and a gate valve arranged on the third pipeline. In the first operating mode, the gate valve V7 and the recirculation valve V3 are closed; in the second operating mode, the recirculation valve V3 is opened and the gate valve V7 is closed; and in the third operating mode, the pressure regulating valve V6 and the gate valve V7 are opened, and the recirculation valve V3 is closed.

[0024] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may further include a flow measurement device SG1 arranged at the inlet of the boiler feed water pump and a flow measurement device SG2 arranged at the inlet of the power plant boiler E3.

[0025] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include differential pressure transmitters DPT1 and DPT2 respectively arranged at both ends of the flow measuring devices SG1 and SG2. The differential pressure signals generated by the differential pressure transmitters DPT1 and DPT2 are sent to the distributed computer controller DCS and flow distribution calculations are performed.

[0026] According to an embodiment of the present application, in the third operation mode, the redundant flow of the third pipeline is equal to the difference between the flows measured by the flow measuring device SG1 and the flow measuring device SG2.

[0027] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include speed measuring probes SE1, SE2, and SE3 for monitoring the speed of the hydraulic turbine. When the speed of the hydraulic turbine E4 is lower than the rated speed of the generator E5, the distributed computer controller DCS controls the pressure regulating valve V6 and the gate valve V7 to increase the opening. When the speed of the hydraulic turbine E4 is higher than the rated speed of the generator E5, the distributed computer controller DCS controls the pressure regulating valve V6 and the gate valve V7 to reduce the opening. When the speed of the hydraulic turbine E4 is higher than the rated speed of the generator E5 and controlling the pressure regulating valve V6 and the gate valve V7 to reduce the opening is ineffective, the pressure regulating valve V6 and the gate valve V7 are closed, and the recirculation valve V3 is opened.

[0028] According to an embodiment of the present application, the distributed computer controller DCS may be a subsystem of the main control room of the power plant. In any case, the distributed computer controller DCS operates under the main control room of the power plant.

[0029] Compared with the prior art, the embodiments of the present application can at least achieve the following beneficial effects:

[0030] The hydraulic turbine power generation system for redundant flow energy recovery according to the embodiment of the present application includes a set of turbine generator sets connected between the outlet of the boiler feed water pump and the inlet of the deaerator, the turbine receives the working medium of the predetermined redundant flow from the boiler feed water pump, absorbs the pressure energy of the working medium to drive the rotating shaft of the turbine and drive the rotating shaft of the generator to rotate to generate electricity, and the turbine only uses the predetermined redundant flow of the boiler feed water pump to generate electricity. The energy of the redundant flow that can be recovered by the hydraulic turbine power generation system for redundant flow energy recovery according to the embodiment of the present application is huge. Taking a 1000MW generator set as an example, the maximum recoverable energy per hour is 2300kW, and the annual power generation is about 6.9 million kWH, so it has a good energy-saving effect. If this part of the energy is not recovered, the redundant flow will be decompressed through the recirculation valve and then flow back to the deaerator, which increases the burden on the recirculation valve and accelerates wear. The recirculation valve will vaporize the working medium during the decompression process and increase the workload of the deaerator, and the heat emission generated during the decompression process is also a pollution to the ambient air. In addition, since the turbine absorbs the redundant flow, the deterioration of the boiler feed pump operating condition can be reduced when the steam turbine generator set is running at low load, that is, the flow of the boiler feed pump can be appropriately increased while the outlet pressure remains within a reasonable range to keep the boiler feed pump running under a better condition. The extra energy consumed by the boiler feed pump can be fully recovered and compensated in the hydraulic turbine generator set. The electricity generated by the hydraulic turbine generator set can be directly incorporated into the power grid of the power plant after being transformed by a transformer, reducing the power consumption of the power plant to the national grid. At the same time, the electricity generated by the hydraulic turbine generator set can also be used as a backup power source for the power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present application, rather than limiting the present application.

[0032] Figure 1 It is a block diagram of a hydraulic turbine power generation system for redundant flow energy recovery according to an embodiment of the present application.

[0033] Figure 2 It is a block diagram of a hydraulic turbine power generation control system for redundant flow energy recovery according to an embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme of the embodiment of the present application will be clearly and completely described in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, not all of the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of this application.

[0035] Unless otherwise defined, the technical or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which this application belongs. The words "first", "second" and similar words used in this patent application specification and claims do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "an" do not indicate a quantity limitation, but indicate the existence of at least one.

[0036] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0037] Figure 1 It is a block diagram of a hydraulic turbine power generation system for redundant flow energy recovery according to an embodiment of the present application.

[0038] like Figure 1 As shown, according to one aspect of the present application, a hydraulic turbine power generation system for redundant flow energy recovery is provided, comprising a boiler feed water pump E2, a hydraulic turbine generator set and a deaerator E1.

[0039] The boiler feed pump E2 includes an inlet and an outlet. The boiler feed pump E2 provides liquid working medium to the power plant boiler through its outlet at a predetermined head and flow rate.

[0040] The power plant mentioned here refers to the traditional thermal power plant or cogeneration plant, which uses coal, oil (heavy oil), gas (coal gas, biogas, carbon-containing mixed gas), and domestic garbage as fuel, heats the working medium through the boiler and drives the steam turbine to drive the generator to generate electricity. The working medium here refers to treated water or a mixture of water and treatment agents, so the working medium can also be called water in this article.

[0041] According to an embodiment of the present application, the boiler feed water pump E2 may be a multi-stage centrifugal impeller series combined feed water pump.

[0042] According to an embodiment of the present application, the power plant boiler E3 can provide steam power for the peak-shaving steam turbine generator set. For a peak-shaving power plant, as known to those skilled in the art, the power generation of the power plant's generator set needs to be allocated through scheduling according to the power consumption of the power grid. In particular, during peak and trough power consumption (commonly known as deep peak regulation), the amount of water supply required by the boiler E3 varies with the change in power generation, but the follow-up operation change of the boiler feed pump E2 will have a certain lag. Based on a comprehensive consideration of the characteristics of the boiler E3 and the boiler feed pump D2, under certain operating conditions, a certain amount of redundant flow will inevitably be generated between the boiler feed pump D2 and the boiler E3.

[0043] The hydraulic turbine generator set includes a turbine E4, a generator E5, and a coupling for connecting the turbine E4 and the generator E5.

[0044] The turbine E4, also referred to herein as a hydraulic turbine, includes an inlet, an outlet, an impeller, and a rotating shaft (not shown in detail), and the inlet of the turbine E4 is connected to the outlet fluid of the boiler feed pump E2 in a fluid-communicating manner. According to an embodiment of the present application, the inlet of the turbine is connected to the outlet fluid of the boiler feed pump E2 in a fluid-communicating manner and may include a third pipeline T3 and a pressure regulating valve V6 and a gate valve V7 arranged on the third pipeline T3. The pressure regulating valve V6 may be an electric pressure regulating valve, which opens and closes at a predetermined pressure according to the command of the control system. For example, when the outlet pressure of the boiler feed pump E2 rises to a first predetermined pressure, the gate valve V7 opens, and the third pipeline T3 from the outlet of the boiler feed pump E2 to the inlet of the turbine E4 is connected, so as to provide the working medium to the turbine E4, and ensure that the turbine E4 operates at the rated speed of the generator E5 by adjusting the opening of the pressure regulating valve V6. When the outlet pressure of the boiler feed pump E2 continues to rise to the second predetermined pressure, the gate valve V7 is closed, cutting off the third pipeline T3 from the outlet of the boiler feed pump E2 to the inlet of the turbine E4, thereby stopping the supply of working medium to the turbine E4.

[0045] According to an embodiment of the present application, the turbine E4 may include a plurality of impellers coaxially assembled in series, the plurality of impellers respectively absorb the pressure energy of the working medium flowing therethrough, and convert the pressure energy into mechanical energy of their own rotation, thereby driving the main shaft of the turbine E4 to rotate at a high speed, for example, the rotation speed may be 3600rpm, 3000rpm, 1500rpm, and other rotation speeds desired by those skilled in the art. The details of the turbine E4 will be described in detail later.

[0046] The rotating shaft of the generator E5 is connected to the rotating shaft of the turbine E4 through a coupling. The connection between the rotating shaft of the generator E5 and the rotating shaft of the turbine E4 can be a rigid connection or a coupling connection. The rotation speed of the generator E5 and the turbine E4 can be a synchronous speed, for example, 3000 rpm. However, the embodiment of the present invention is not limited to this, but the rotation speed of the generator E5 and the turbine E4 can be 1500 rpm or 3600 rpm, or any suitable rotation speed, and those skilled in the art can determine it according to the corresponding relationship between the rotation speed and the number of magnetic pole pairs according to actual needs. The details of the generator E5 will be described in detail later.

[0047] The deaerator E1 includes a plurality of working medium inlets, a working medium outlet and at least one exhaust port (not shown in detail). Figure 1 As shown, at least one of the multiple working medium inlets is fluidly connected to the outlet fluid of the turbine E4, and the working medium outlet of the deaerator E1 is fluidly connected to the inlet fluid of the boiler feed water pump E2. According to an embodiment of the present application, at least one of the multiple working medium inlets is fluidly connected to the outlet fluid of the turbine and may include a fifth pipeline T5 and an isolation valve V8 and a check valve V9 arranged on the fifth pipeline T5. According to an embodiment of the present application, the working medium outlet of the deaerator E1 is fluidly connected to the inlet fluid of the boiler feed water pump E2 and may include a first pipeline T1 and a pressure sensor PT, a gate valve V1, and a flow measurement device SG1 arranged in sequence on the first pipeline T1.

[0048] According to the actual needs of the power grid, under the predetermined operating conditions of the steam turbine generator set of the power plant, the turbine receives the working medium of the predetermined redundant flow from the boiler feed pump E2, absorbs the pressure energy of the working medium to drive the rotating shaft of the turbine and drive the rotating shaft of the generator to rotate to generate electricity. The turbine generates electricity only by using the predetermined redundant flow of the boiler feed pump E2.

[0049] According to an embodiment of the present application, the hydraulic turbine power generation system for redundant flow energy recovery may also include a main high-pressure pipeline T4 leading from the outlet of the boiler feed pump E2 to the boiler, and a check valve V10, a gate valve V11, and a flow measurement device SG2 arranged in sequence on the main high-pressure pipeline T4. The main high-pressure pipeline T4 is the main trunk connecting the boiler feed pump E2 to the boiler of the generator set. The hydraulic turbine power generation system for redundant flow energy recovery according to an embodiment of the present application must comply with and serve the needs of power generation and operation of the steam turbine generator set of the power plant.

[0050] According to an embodiment of the present application, the hydraulic turbine power generation system for redundant flow energy recovery may further include a boiler economizer E3, and the main pipeline T4 may lead to the boiler through the boiler economizer E3. The boiler economizer E3 is used at the front end of the boiler to recover and utilize the waste heat in the flue, and also preheats the water supply at the front end of the boiler.

[0051] According to an embodiment of the present application, the hydraulic turbine power generation system for redundant flow energy recovery may also include a second pipeline T2 that fluidically connects the outlet of the boiler feed pump E2 and one of the multiple working medium inlets of the deaerator E1, and a pre-recirculation isolation valve V2, a recirculation valve V3, a post-recirculation isolation valve V4, and a check valve V5 arranged on the second pipeline T2. As mentioned above, when the boiler feed pump E2 is in the startup, shutdown, and rapid adjustment operating conditions, under the control of the control system, the recirculation valve V3 is opened. In addition, when the opening of the pressure reducing valve V6 is adjusted and still cannot make the turbine E4 operate at the rated speed of the generator E5, the recirculation valve V3 also needs to be opened, and the redundant flow will be reduced through the recirculation valve V3 and then flow back to the deaerator. During this period, the recirculation valve V3 bears a huge pressure difference, such as a pressure difference of about 17 MPa, and consumes a huge pressure energy. Of course, this is also an important guarantee to ensure the normal operation of the boiler feed pump and the boiler without causing accidental shutdown.

[0052] According to an embodiment of the present application, the electricity generated by the hydraulic turbine generator set can be incorporated into the power grid for the factory through a transformer. However, the embodiment of the present application is not limited thereto, but the electricity generated by the hydraulic turbine generator set can also be incorporated into the power grid (national power grid) through a transmission and transformation circuit. When the electricity generated by the hydraulic turbine generator set is incorporated into the power grid for the factory, the power demand of the power plant on the power grid can be greatly reduced. In addition, it can also be used as a backup power source for the power supply of the power plant. In this case, the dependence of the backup power supply for the factory power on the diesel generator set can be reduced.

[0053] According to an embodiment of the present application, a hydraulic turbine power generation system for redundant flow energy recovery has a first operating mode, a second operating mode and a third operating mode under different operating conditions, and the first to third operating modes are switched by opening / closing valves in the system.

[0054] According to an embodiment of the present application, in the first operating mode, the boiler feed pump E2 only delivers working medium to the power plant boiler E3; in the second operating mode, the pressure regulating valve V7 on the third pipeline is closed, and the recirculation valve V3 on the second pipeline T2 is opened. The boiler feed pump E2 can deliver working medium to the power plant boiler E3, and at the same time, it can divert part of the flow through the recirculation valve V3 on the second pipeline T3 to maintain safe and stable operation of the boiler feed pump; in the third operating mode, the pressure regulating valve V7 on the third pipeline T3 is opened, and the recirculation valve V3 on the second pipeline T2 is closed. The boiler feed pump E2 can deliver working medium to the power plant boiler E3, and at the same time, it can provide redundant flow of working medium to the turbine E4 through the third pipeline T3 and drive the generator E5 to generate electricity to recover the pressure energy of the working medium.

[0055] Below, the significance and beneficial effects of the hydraulic turbine power generation system for redundant flow energy recovery according to the embodiments of the present application are described with reference to examples.

[0056] Table 1 Summary of actual operation of steam turbine generator units in a 1000MW power plant

[0057]

[0058]

[0059] Table 2 Operation rules of the water supply pump recirculation valve opening

[0060]

[0061]

[0062] Table 3 Comparison of economic benefits of energy recovery effect

[0063]

[0064]

[0065] Conclusion: Taking the average value of the design parameters listed in Table 3 above for budgeting, one unit can achieve an annual electricity saving of about 1.8 million yuan.

[0066] Figure 2 It is a block diagram of a hydraulic turbine power generation control system for redundant flow energy recovery according to an embodiment of the present application.

[0067] like Figure 2As shown, according to another aspect of the present application, a control system for a hydraulic turbine power generation system for redundant flow energy recovery is provided, wherein the hydraulic turbine power generation system for redundant flow energy recovery comprises a deaerator E1 for collecting various working media and deoxidizing and degassing them, a boiler feed pump E2 for providing working media to a power plant boiler E3, hydraulic turbine generator sets E4 and E5 utilizing the redundant flow of the boiler feed pump E2, a recirculation valve V3 for overpressure protection, and a first pipeline T1 connecting the outlet of the deaerator E1 to the inlet of the boiler feed pump E2, and a second pipeline T1 connecting the outlet of the boiler feed pump E2 to the inlet of the deaerator E1 via the recirculation valve V3. The pipeline T2, the third pipeline T3 connecting the outlet of the boiler feed water pump E2 to the inlet of the hydraulic turbine of the hydraulic turbine generator set E4 and E5, the fourth pipeline T4 connecting the outlet of the boiler feed water pump E2 to the boiler E3 of the power plant, and the fifth pipeline T5 connecting the outlet of the hydraulic turbine of the hydraulic turbine generator set E4 and E5 to the inlet of the deaerator E1, the control system includes: a distributed computer controller DCS, which sends a control signal to the user end based on the input signal and the preset algorithm, and communicates with the main control room of the power plant; and a pressure transmitter PT3, which outputs the pressure signal of the outlet of the boiler feed water pump to the distributed computer controller DCS. The distributed computer controller DCS receives the pressure signal of the outlet of the boiler feed water pump output from the pressure transmitter PT3, and the distributed computer controller DCS divides the received pressure signal of the outlet of the boiler feed water pump into three operation modes, namely the first operation mode, the second operation mode and the third operation mode, and the first to third operation modes are switched by opening / closing the valve in the system. The distributed computer controller DCS conducts the third pipeline only in the third operation mode and enables the hydraulic turbine generator set to operate and generate electricity.

[0068] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include a first pressure transmitter PT1 disposed at the outlet of the deaerator E1, a second pressure transmitter PT2 disposed at the inlet of the boiler feed pump E2, a fourth pressure transmitter PT4 disposed at the inlet of the hydraulic turbine, a fifth pressure transmitter PT5 disposed at the outlet of the hydraulic turbine, and a sixth pressure transmitter PT6 disposed at the inlet of the power plant boiler. The distributed computer controller DCS receives the pressure signals from the above-mentioned pressure transmitters PT1, PT2, PT4, PT5, PT6, and in combination with the pressure signal from the pressure transmitter PT3, comprehensively judges the operation status of the hydraulic turbine power generation system for redundant flow energy recovery according to a predetermined algorithm, and determines its next operation step.

[0069] According to an embodiment of the present application, the first operating mode may be an operating mode in which the outlet pressure of the boiler feed pump is adjusted when the load of the steam turbine generator set of a power plant is above 70% of the design load, the second operating mode may be an operating mode in which the outlet pressure of the boiler feed pump is adjusted when the load of the steam turbine generator set of a power plant is between 60% and 70% of the design load, the third operating mode may be an operating mode in which the load of the steam turbine generator set of a power plant fluctuates around 40% to 50% of the design load, and the third operating mode may also include a lower operating mode of deep peak regulation that may occur based on the dispatch of the power grid.

[0070] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include a pressure regulating valve V6 and a gate valve V7 arranged on the third pipeline T3. In the first operating mode, the gate valve V7 and the recirculation valve V3 are closed; in the second operating mode, the recirculation valve V3 is opened and the gate valve V7 is closed; and in the third operating mode, the pressure regulating valve V6 and the gate valve V7 are opened, and the recirculation valve V3 is closed.

[0071] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include a flow measurement device SG1 arranged at the inlet of the boiler feed water pump E2 and a flow measurement device SG2 arranged at the inlet of the power plant boiler E3.

[0072] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include differential pressure transmitters DPT1 and DPT2 respectively arranged at both ends of the flow measuring devices SG1 and SG2. The differential pressure signals generated by the differential pressure transmitters DPT1 and DPT2 are sent to the distributed computer controller DCS and flow distribution calculations are performed.

[0073] According to an embodiment of the present application, in the third operation mode, the redundant flow of the third pipeline is equal to the difference between the flows measured by the flow measuring device SG1 and the flow measuring device SG2.

[0074] According to an embodiment of the present application, the control system of the hydraulic turbine power generation system for redundant flow energy recovery may also include speed measuring probes SE1, SE2, and SE3 for monitoring the speed of the hydraulic turbine. When the speed of the hydraulic turbine E4 is lower than the rated speed of the generator E5, the distributed computer controller DCS controls the pressure regulating valve V6 to increase the opening. When the speed of the hydraulic turbine E4 is higher than the rated speed of the generator E5, the distributed computer controller DCS controls the pressure regulating valve V6 to reduce the opening. When the speed of the hydraulic turbine E4 is higher than or lower than the rated speed of the generator E5 and controlling the opening of the pressure regulating valve V6 is ineffective, the gate valve V7 is closed and the recirculation valve V3 is opened.

[0075] According to an embodiment of the present application, the distributed computer controller DCS may be a subsystem of the main control room of the power plant. In any case, the distributed computer controller DCS operates under the main control room of the power plant.

[0076] Below, taking a 1000MW steam turbine generator set equipped with a 100% capacity boiler feed pump as an example, the design parameters and control requirements of the control system for a hydraulic turbine power generation system with redundant flow energy recovery are described.

[0077] The steam turbine generator set operates within the load range of 400MW to 1000MW, with an annual average load rate of 60%. During peak periods when electricity demand is strong, the load rate remains above 80%, and during trough periods, it basically maintains a load rate of 40%. The turbine generator set is designed with reference to the highest efficiency at a boiler load rate of 40%, and the annual operation time is expected to be 3000h.

[0078] A flow measuring device SG1 is provided on the feed water pump inlet side, and a flow measuring device SG2 is provided on the boiler inlet side. The recirculation flow (pipeline T2) and the turbine generator flow (pipeline T3) are the differences between SG1 and SG2.

[0079] The deaerator outlet, feed water pump inlet and outlet, turbine inlet and outlet, and boiler inlet are respectively equipped with pressure detection devices PT1~PT6.

[0080] The recirculation valve V3 has a fast opening function, the gate valve V7 has a fast closing function, and the isolation valves V2, V4 and V8 are normally open.

[0081] The size of the grid load determines the flow rate and pressure of the medium required by boiler E3. The above requirements are met by adjusting the opening of valve V11 and the speed of feed water pump E2.

[0082] When the unit is about to start, shut down or quickly reduce the load, the recirculation valve V3 is fully opened and the gate valve V7 is fully closed. After the unit is running smoothly and the feed water pump flow, i.e., the SG1 value, is greater than the minimum flow value of the feed water pump by a certain range, the recirculation valve V3 is slowly closed.

[0083] When the unit load is about 400MW to 500MW, the turbine generator set is put into operation, the gate valve V7 and the pressure regulating valve V6 are opened, and the recirculation valve V3 is closed. The redundant high-pressure medium enters the turbine wheel through the turbine inlet, drives the turbine to work, and the low-pressure medium returns to the deaerator E1 through the turbine outlet. The turbine drives the generator to work through the coupling. The turbine shaft head is equipped with a speed measuring device and equipped with 3 redundant speed measuring probes. The signal is connected to the power plant automatic control system DCS. When the turbine speed is higher than the generator working speed, the pressure regulating valve V6 and the gate valve V7 opening are first reduced. If it still cannot meet the requirements, the recirculation valve V3 is opened appropriately; when the turbine speed is higher than the safe speed of the generator in special circumstances, the valve V7 is quickly closed and the valve V3 is quickly opened; when the turbine speed is lower than the generator working speed, the gate valve V7 and the pressure regulating valve V6 are opened to full open and the recirculation valve V3 is adjusted to full close to ensure that the turbine speed is within the working range of the generator.

[0084] When the load is 600MW and above, the turbine generator set is cut out, and the gate valve V7 and recirculation V3 are closed.

[0085] Compared with the prior art, the embodiments of the present application can at least achieve the following beneficial effects:

[0086] The hydraulic turbine power generation system for redundant flow energy recovery according to the embodiment of the present application includes a set of turbine generator sets connected between the outlet of the boiler feed water pump and the inlet of the deaerator, the turbine receives the working medium of the predetermined redundant flow from the boiler feed water pump, absorbs the pressure energy of the working medium to drive the rotating shaft of the turbine and drive the rotating shaft of the generator to rotate to generate electricity, and the turbine only uses the predetermined redundant flow of the boiler feed water pump to generate electricity. The energy of the redundant flow that can be recovered by the hydraulic turbine power generation system for redundant flow energy recovery according to the embodiment of the present application is huge. Taking a 1000MW generator set as an example, the maximum recoverable energy per hour is 2300kW, and the annual power generation is about 6.9 million kWH, so it has a good energy-saving effect. If this part of the energy is not recovered, the redundant flow will be decompressed through the recirculation valve and then flow back to the deaerator, which increases the burden on the recirculation valve and accelerates wear. The recirculation valve will vaporize the working medium during the decompression process and increase the workload of the deaerator, and the heat emission generated during the decompression process is also a pollution to the ambient air. In addition, since the turbine absorbs the redundant flow, the deterioration of the boiler feed pump operating condition can be reduced when the steam turbine generator set is running at low load, that is, the flow of the boiler feed pump can be appropriately increased while the outlet pressure remains within a reasonable range to keep the boiler feed pump running under a better condition. The extra energy consumed by the boiler feed pump can be fully recovered and compensated in the hydraulic turbine generator set. The electricity generated by the hydraulic turbine generator set can be directly incorporated into the power grid of the power plant after being transformed by a transformer, reducing the power consumption of the power plant to the national grid. At the same time, the electricity generated by the hydraulic turbine generator set can also be used as a backup power source for the power plant.

[0087] The above description is merely an exemplary embodiment of the present application and is not intended to limit the protection scope of the present application. The protection scope of the present application is determined by the appended claims.

Claims

1. A control system for a hydraulic turbine power generation system for redundant flow energy recovery, the hydraulic turbine power generation system for redundant flow energy recovery comprising a deaerator (E1) for collecting various working media and deoxidizing and degassing them, a boiler feed pump (E2) for providing working media to a power plant boiler (E3), a hydraulic turbine generator set (E4, E5) utilizing the redundant flow of the boiler feed pump (E2), a recirculation valve (V3) for overpressure protection, and a first pipeline (T1) connecting the outlet of the deaerator (E1) to the inlet of the boiler feed pump (E2), and a first pipeline (T2) connecting the boiler A second pipeline (T2) connecting the outlet of the feedwater pump (E2) via the recirculation valve (V3) to the inlet of the deaerator (E1), a third pipeline (T3) connecting the outlet of the boiler feedwater pump (E2) via the inlet of the hydraulic turbine of the hydraulic turbine generator set (E4, E5), a fourth pipeline (T4) connecting the outlet of the boiler feedwater pump (E2) to the power plant boiler (E3), and a fifth pipeline (T5) connecting the outlet of the hydraulic turbine of the hydraulic turbine generator set (E4, E5) to the inlet of the deaerator (E1), the control system includes: Distributed computer controller DCS, which sends control signals to the user end based on input signals and preset algorithms, and communicates with the main control room of the power plant; A pressure transmitter (PT3) outputs a pressure signal of the outlet of the boiler feed pump (E2) to the distributed computer controller DCS; as well as The pressure regulating valve (V6) and the gate valve (V7) are arranged on the third pipeline (T3). wherein the distributed computer controller DCS receives a pressure signal from the outlet of the boiler feed pump (E2) output by the pressure transmitter (PT3), and the distributed computer controller DCS divides the operation of the hydraulic turbine power generation system for redundant flow energy recovery into three operation modes, namely, a first operation mode, a second operation mode and a third operation mode, based on the received pressure signal from the outlet of the boiler feed pump (E2), and the first to third operation modes are switched by opening / closing valves in the system; Wherein, the distributed computer controller DCS conducts the third pipeline (T3) only in the third operation mode and enables the hydraulic turbine generator sets (E4, E5) to operate and generate electricity; Wherein, the first operation mode is an operation mode when the load of the steam turbine generator set of the power plant is above 70% of the design load, the second operation mode is an operation mode when the load of the steam turbine generator set of the power plant is between 60% and 70% of the design load, and the third operation mode is an operation mode when the load of the steam turbine generator set of the power plant is between 40% and 50% of the design load according to the dispatch of the power grid, and the third operation mode includes an operation mode in which deep peak regulation occurs to a lower level according to the dispatch of the power grid; Wherein, in the first operation mode, the gate valve (V7) and the recirculation valve (V3) are closed; Wherein, in the second operation mode, the recirculation valve (V3) is opened; and the gate valve (V7) is closed; and In the third operating mode, the pressure regulating valve (V6) and the gate valve (V7) are opened, and the recirculation valve (V3) is closed.

2. The control system of the hydraulic turbine power generation system for redundant flow energy recovery according to claim 1, further comprising a first pressure transmitter (PT1) arranged at the outlet of the deaerator (E1), a second pressure transmitter (PT2) arranged at the inlet of the boiler feed pump (E2), a fourth pressure transmitter (PT4) arranged at the inlet of the hydraulic turbine, a fifth pressure transmitter (PT5) arranged at the outlet of the hydraulic turbine, and a sixth pressure transmitter (PT6) arranged at the inlet of the power plant boiler, in, The distributed computer controller DCS receives pressure signals respectively from the first pressure transmitter (PT1) at the outlet of the deaerator (E1), the second pressure transmitter (PT2) at the inlet of the boiler feed pump (E2), the fourth pressure transmitter (PT4) at the inlet of the hydraulic turbine, the fifth pressure transmitter (PT5) at the outlet of the hydraulic turbine, and the sixth pressure transmitter (PT6) at the inlet of the power plant boiler, and in combination with the pressure signal from the pressure transmitter (PT3) at the outlet of the boiler feed pump (E2), comprehensively judges the operating status of the hydraulic turbine power generation system for redundant flow energy recovery according to a predetermined algorithm, and determines its next operating step.

3. The control system of the hydraulic turbine power generation system for redundant flow energy recovery as described in claim 1, further comprising a flow measurement device (SG1) arranged at the inlet of the boiler feed water pump (E2) and a flow measurement device (SG2) arranged at the inlet of the power plant boiler (E3).

4. The control system of the hydraulic turbine power generation system for redundant flow energy recovery as described in claim 3 further includes differential pressure transmitters (DPT1, DPT2) respectively arranged at both ends of the flow measuring device (SG1, SG2), and the differential pressure signal generated by the differential pressure transmitter (DPT1, DPT2) is sent to the distributed computer controller DCS and the flow distribution calculation is performed.

5. The control system for a hydraulic turbine power generation system with redundant flow energy recovery according to claim 3, wherein: In the third operation mode, the redundant flow of the third pipeline is equal to the difference between the flow rates measured by the flow measuring device (SG1) at the inlet of the boiler feed pump (E2) and the flow measuring device (SG2) at the inlet of the power plant boiler (E3).

6. The control system of the hydraulic turbine power generation system for redundant flow energy recovery according to claim 1, further comprising a speed measuring probe (SE1, SE2, SE3) for monitoring the speed of the hydraulic turbine, in, When the speed of the hydraulic turbine (E4) is lower than the rated speed of the generator (E5), the distributed computer controller DCS controls the pressure regulating valve (V6) to increase its opening degree. When the speed of the hydraulic turbine (E4) is higher than the rated speed of the generator (E5), the distributed computer controller DCS controls the pressure regulating valve (V6) to reduce its opening, and When the rotation speed of the hydraulic turbine (E4) is higher or lower than the rated rotation speed of the generator (E5) and controlling the opening of the pressure regulating valve (V6) is ineffective, the gate valve (V7) is closed and the recirculation valve (V3) is opened.

7. The control system for a hydraulic turbine power generation system with redundant flow energy recovery according to claim 1, wherein: The distributed computer controller DCS is a subsystem of the main control room of the power plant. In any case, the distributed computer controller DCS runs under the main control room of the power plant.

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