Efficient thermodynamic system of coal-fired power generating unit and control method

Abstract

The invention relates to an efficient thermodynamic system of a coal-fired power generation unit and a control method. The coal power unit comprises a boiler, a thermodynamic cycle system, a back pressure machine and a feed water heater. The steam output end of the boiler is connected with the steam input end of the back pressure machine and the steam input end of the thermodynamic cycle system. The steam output end of the back pressure machine is connected with the steam input end of the feed water heater, and the feed water output end of the thermodynamic cycle system is connected with the feed water input end of the feed water heater; steam output by the back pressure machine is used for heating feed water input to the feed water heater by the thermodynamic cycle system; and the feed water output end of the feed water heater is connected with the feed water end of the boiler. The coal consumption of the coal power unit can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal power units, in particular to a high-efficiency thermal system and control method of a coal-fired power unit. BACKGROUND

[0002] With the continuous increase of new energy installed capacity and the development of new generation coal power, coal power units are increasingly widely used, and the flexibility of the units needs to be continuously improved. Generally, a coal power unit can generate steam by burning coal to drive a steam turbine to drive a generator to generate electricity.

[0003] In the current coal power unit system, in order to reduce the coal consumption of the unit, the flue gas waste heat is usually used to heat the boiler feed water. However, since the flue gas temperature is not high, the position of heating the feed water is generally before the high-pressure heater, i.e. the final feed water cannot be heated, so that the temperature of the boiler feed water side does not change, and the effect of significantly reducing the coal consumption of the unit cannot be achieved. SUMMARY

[0004] Therefore, it is necessary to provide a high-efficiency thermal system and control method of a coal-fired power unit capable of reducing the coal consumption of the unit in view of the above technical problems.

[0005] In a first aspect, the present application provides a coal power unit, comprising: a boiler, a thermal cycle system, a back pressure turbine and a feed water heater;

[0006] The steam output end of the boiler is connected with the steam input end of the back pressure turbine and the steam input end of the thermal cycle system respectively;

[0007] The steam output end of the back pressure turbine is connected with the steam input end of the feed water heater, and the feed water output end of the thermal cycle system is connected with the feed water input end of the feed water heater; the steam output by the back pressure turbine is used to heat the feed water input to the feed water heater by the thermal cycle system;

[0008] The feed water output end of the feed water heater is connected with the feed water end of the boiler.

[0009] In one of the embodiments, the thermal cycle system comprises a high-pressure cylinder and a high-pressure regenerative component, the steam input end of the thermal cycle system comprises the steam input end of the high-pressure cylinder and the steam input end of the high-pressure regenerative component, and the feed water output end of the thermal cycle system comprises the feed water output end of the high-pressure regenerative component;

[0010] The steam input end of the high-pressure cylinder is connected with the steam output end of the boiler;

[0011] The steam input end of the high-pressure regenerative component is connected with the steam output end of the high-pressure cylinder, and the feed water output end of the high-pressure regenerative component is connected with the feed water input end of the feed water heater.

[0012] In one of the embodiments, the coal power unit further comprises a connecting assembly; the connecting assembly is arranged between the back pressure turbine and the high pressure cylinder, and is configured to control a connection state between the back pressure turbine and the high pressure cylinder.

[0013] In one of the embodiments, a first valve is arranged between the boiler and the back pressure turbine, and is configured to control an on-off state of a steam passage between the boiler and the back pressure turbine.

[0014] In one of the embodiments, a second valve is arranged between the back pressure turbine and the feed water heater, and is configured to control an on-off state of a steam passage between the back pressure turbine and the feed water heater.

[0015] In one of the embodiments, the coal power unit further comprises a condensing device; a steam input end of the condensing device is connected with a steam output end of the back pressure turbine, and is configured to condense steam discharged by the back pressure turbine.

[0016] In one of the embodiments, a third valve is arranged between the back pressure turbine and the condensing device, and is configured to control an on-off state of a steam passage between the back pressure turbine and the condensing device.

[0017] In a second aspect, the present application further provides a coal power unit control method, which is applied to the coal power unit, and comprises the following steps:

[0018] In response to a power generation instruction for the coal power unit, a target load of the coal power unit and a feed water heating demand of the coal power unit are obtained;

[0019] In a case where the target load is lower than a rated load, the boiler is controlled to deliver first steam matching the feed water heating demand to the back pressure turbine;

[0020] A target steam admission amount for the thermal cycle system is determined, and the boiler is controlled to deliver second steam to the thermal cycle system according to the target steam admission amount;

[0021] A feed water heating result is obtained; the feed water heating result is a result obtained by the feed water heater heating feed water entering the boiler based on the first steam delivered by the back pressure turbine and the second steam delivered by the thermal cycle system.

[0022] In one of the embodiments, a first valve is arranged between the boiler and the back pressure turbine, and a second valve is arranged between the back pressure turbine and the feed water heater; the boiler is controlled to deliver first steam matching the feed water heating demand to the back pressure turbine, which comprises the following steps:

[0023] The first valve and the second valve are controlled to be in an open state, so that the boiler delivers first steam matching the feed water heating demand to the back pressure turbine, and the back pressure turbine delivers the first steam to the feed water heater.

[0024] In one embodiment, the coal-fired power unit further includes a condensing device and a connecting assembly, a third valve is provided between the back pressure compressor and the condensing device, the thermal circulation system includes a high-pressure cylinder, and the coal-fired power unit control method further includes:

[0025] Obtain the operating status of the back pressure unit when the target load is not lower than the rated load;

[0026] When the back pressure machine is in a stopped state, the first valve, the second valve, and the third valve are all closed, and the back pressure machine is disconnected from the high pressure cylinder through the connecting assembly.

[0027] When the back pressure unit is in standby mode, determine the minimum steam inlet flow rate of the back pressure unit;

[0028] The first and third valves are controlled to be in the open state, while the second valve is in the closed state, so that the boiler delivers a third steam that matches the minimum steam intake to the back pressure unit, and the third steam is delivered to the condensing device through the back pressure unit.

[0029] The aforementioned coal-fired power unit and its control method, by installing a back-pressure turbine between the boiler's steam outlet and the inlet of the thermal cycle system, and adding a feedwater heater between the back-pressure turbine and the boiler feedwater side, allow the coal-fired power unit to operate at a load below its rated load (i.e., under medium-to-low load conditions). This means that, based on feedwater heating needs, a portion of the boiler steam matching these needs can be extracted and fed into the back-pressure turbine to perform work. Furthermore, the back-pressure turbine can then deliver this portion of boiler steam to the feedwater heater, which further heats the boiler feedwater. This allows the feedwater to be heated to a higher temperature than the conventional system feedwater under these load conditions, thereby improving the thermal cycle efficiency of the coal-fired power unit, reducing coal consumption, and achieving economical operation of the coal-fired power unit across wide load ranges.

[0030] The first steam supplied by the boiler to the back pressure turbine is located before the throttling valve, therefore the first steam does not undergo throttling and there is no throttling loss. This reduces the overall throttling loss of the unit, resulting in economic benefits. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a coal-fired power unit in one embodiment;

[0033] Figure 2 a structural diagram of a coal-fired power unit in an embodiment;

[0034] Figure 3 a structural diagram of an optimized coal-fired power unit in an embodiment;

[0035] Figure 4 a flowchart of a control method of a coal-fired power unit in an embodiment;

[0036] Figure 5 a flowchart of a control method of a coal-fired power unit in another embodiment;

[0037] Figure 6 a structural diagram of a control device of a coal-fired power unit in an embodiment;

[0038] Figure 7 an internal structural diagram of a computer device in an embodiment. DETAILED DESCRIPTION

[0039] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0040] The power generation of a coal-fired power unit is a complex energy conversion process involving the mutual conversion of multiple energy forms. The unit mainly consists of a boiler, a steam turbine, a generator, and auxiliary systems. In the boiler, coal is fed into the combustion chamber for combustion, releasing a large amount of heat energy. The feed water in the boiler is heated and evaporated by the heating surface, forming high-temperature and high-pressure steam. The steam enters the steam turbine and expands on the blades, pushing the blades to rotate and thus converting heat energy into mechanical energy. The mechanical energy output by the steam turbine is converted into electrical energy by the generator and output to the outside through the power transmission line.

[0041] The steam cylinder of the steam turbine can be divided into a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder according to different inlet steam parameters. Figure 1 A structural diagram of a coal-fired power unit is shown. The coal-fired power unit 10 includes a boiler 101, a high-pressure cylinder 102, a medium-pressure cylinder 103, a low-pressure cylinder 104, a condenser 105, a low-pressure heater 106, a deaerator 107, a third high-pressure heater 108, a second high-pressure heater 109, and a first high-pressure heater 110. The third high-pressure heater, the second high-pressure heater, and the first high-pressure heater are connected in sequence through a feed water passage, and the steam extraction temperatures of the third high-pressure heater, the second high-pressure heater, and the first high-pressure heater increase in sequence.

[0042] Specifically, the main steam discharged from boiler 101 enters high-pressure cylinder 102. The exhaust steam from high-pressure cylinder 102 enters the reheater of boiler 101 for reheating, forming reheated steam. Simultaneously, the second high-pressure heater 109 and the first high-pressure heater 110 extract exhaust steam from high-pressure cylinder 102 at different temperatures for reheating. The reheated steam discharged from boiler 101 enters intermediate-pressure cylinder 103. The intermediate-pressure exhaust steam from intermediate-pressure cylinder 103 enters low-pressure cylinder 104, while the third high-pressure heater 108 extracts a portion of the exhaust steam from intermediate-pressure cylinder 103 for reheating. The exhaust steam that performs work in low-pressure cylinder 104 enters condenser 105 and condenses into water. The condensate then sequentially enters low-pressure heater 106, deaerator 107, third high-pressure heater 108, second high-pressure heater 109, and first high-pressure heater 110, finally returning to boiler 101, thus realizing the boiler's thermal cycle. The power generated by generator 20 comes from the combined work of high-pressure cylinder 102, medium-pressure cylinder 103 and low-pressure cylinder 104. The condensers in this scheme can all be replaced by air-cooled islands.

[0043] In current coal-fired power unit systems, to reduce coal consumption, waste heat from flue gas is typically used to heat boiler feedwater. Based on Figure 1 As illustrated, the structure shows that the feedwater temperature from the first high-pressure heater is relatively high, while the flue gas temperature is relatively low. Therefore, the feedwater is typically heated before the high-pressure heater, meaning the final feedwater cannot be heated. This results in no change in the boiler feedwater temperature, failing to significantly reduce the unit's coal consumption. Furthermore, when the unit is operating at medium to low loads, throttling losses increase, and heating with waste heat from the flue gas cannot reduce these losses. Therefore, how to increase the boiler feedwater temperature while simultaneously reducing throttling losses under medium to low load conditions, thereby achieving economic efficiency in wide-load operation of coal-fired power units, is a key focus for current coal-fired power unit development.

[0044] Based on this, this plan selects to add one back-pressure turbine and one feedwater heater. A back-pressure turbine is a steam turbine with an exhaust pressure higher than atmospheric pressure, significantly higher than that of a condensing steam turbine. A feedwater heater is a steam-water heat exchange device that uses extracted steam to heat boiler feedwater; by further heating the boiler feedwater, it can improve the overall thermal cycle efficiency of the coal-fired power unit.

[0045] In some embodiments, Figure 2 A structural block diagram of a coal-fired power unit is shown, wherein the coal-fired power unit 10 includes: a boiler 101, a thermal cycle system 201, a back pressure machine 202, and a feedwater heater 203.

[0046] The steam output end of the boiler 101 is connected with the steam input end of the back pressure turbine 202 and the steam input end of the thermal cycle system 201 respectively, and the steam input of the back pressure turbine 202 meets the water supply heating demand of the coal-fired unit. The steam output end of the back pressure turbine 202 is connected with the steam input end of the water supply heater 203, and the water supply output end of the thermal cycle system 201 is connected with the water supply input end of the water supply heater 203. The water supply output end of the water supply heater 203 is connected with the water supply end of the boiler 101.

[0047] In some embodiments, Figure 3 The structural schematic diagram of the optimized coal-fired unit is shown. The thermal cycle system 201 can include a high-pressure cylinder 102, a medium-pressure cylinder 103, a low-pressure cylinder 104, a condenser 105, a low-pressure heater 106, a deaerator 107, and a high-pressure regenerative assembly (a third high-pressure heater 108, a second high-pressure heater 109, and a first high-pressure heater 110).

[0048] Specifically, the back pressure turbine is arranged before the high-pressure cylinder of the steam turbine and is connected in parallel with the high-pressure cylinder of the steam turbine. The main steam of the boiler is divided into two parts before throttling, one part flows into the back pressure turbine, and the other part flows into the high-pressure cylinder after throttling. In this way, the main steam flowing into the back pressure turbine does not need to be throttled, and the throttling loss of a part of the main steam can be reduced. The water supply heater is arranged between the high-pressure regenerative assembly and the water supply side of the boiler and is connected with the first high-pressure heater, for further heating the water supply delivered by the first high-pressure heater through the exhaust steam of the back pressure turbine. In this way, the water supply can be further heated. Thus, the coal consumption of the unit can be reduced, and the economic efficiency of the wide load operation of the coal-fired unit can be realized.

[0049] In the above embodiments, by adding a back pressure turbine and a water supply heater, in the medium and low load conditions of the unit, a part of the main steam of the boiler meeting the water supply heating demand can be extracted into the back pressure turbine to do work, and the amount of steam entering the thermal cycle system is reduced. Further, the back pressure turbine can discharge steam into the water supply heater to further heat the water supply based on the water supply heater, so as to increase the water supply temperature, and thus the coal consumption of the unit can be reduced. Further, the steam input of the high-pressure cylinder in the medium and low load conditions can be reduced, and excessive throttling can be avoided, so as to reduce the throttling loss of the unit and realize the economic efficiency of the wide load operation of the coal-fired unit.

[0050] It should be understood that the flow of the main steam entering the back pressure turbine is equal to the flow of the exhaust steam of the back pressure turbine, and the exhaust steam of the back pressure turbine will enter the newly added water supply heater to heat the water supply. That is, the flow of the exhaust steam of the back pressure turbine required for heating the water supply determines the flow of the main steam entering the back pressure turbine. Therefore, the flow of the main steam entering the back pressure turbine can be dynamically adjusted based on the water supply heating demand of the coal-fired unit, so as to achieve the purpose of heating the water supply on demand.

[0051] In some embodiments, the steam input end of the thermal cycle system 201 can include the steam input end of the high-pressure cylinder 102 and the steam input end of the high-pressure regenerative assembly, specifically the steam input end of the first high-pressure heater 110 and the steam input end of the second high-pressure heater 109. Similarly, the feedwater output end of the thermal cycle system 201 can include the feedwater output end of the high-pressure regenerative assembly, specifically the feedwater output end of the first high-pressure heater 110 and the feedwater output end of the second high-pressure heater 109.

[0052] The steam input end of the high-pressure cylinder 102 is connected to the steam output end of the boiler 101 to receive the main steam delivered by the boiler. The steam output end of the high-pressure cylinder 102 is connected to the steam input end of the first high-pressure heater 110 and the steam input end of the second high-pressure heater 109 to discharge steam to the first high-pressure heater 110 and the second high-pressure heater 109, respectively. The feedwater output end of the first high-pressure heater 110 is connected to the feedwater input end of the feedwater heater 203 to deliver heated feedwater to the feedwater heater 203 through the feedwater passage.

[0053] Specifically, after the low-pressure heater heats the condensate water, the heated feedwater is delivered to the third high-pressure heater after being treated by the deaerator. The third high-pressure heater further heats the feedwater by extracting steam from the intermediate-pressure cylinder, and the re-heated feedwater is delivered to the second high-pressure heater through the feedwater passage. The second high-pressure heater also re-heats the feedwater by extracting steam from the high-pressure cylinder, and the re-heated feedwater is delivered to the first high-pressure heater through the feedwater passage. After the first high-pressure heater heats the feedwater by extracting steam, the re-heated feedwater is delivered to the newly added feedwater heater through the feedwater passage. The feedwater heater further heats the feedwater by extracting steam from the back-pressure turbine, and delivers the heated feedwater to the boiler.

[0054] In the above embodiments, by adding a feedwater heater between the high-pressure regenerative assembly and the boiler, the feedwater is further heated, which not only ensures the accurate increase of the feedwater temperature, but also improves the overall cycle thermal efficiency of the unit.

[0055] In some embodiments, the coal-fired unit 10 can further include a connecting assembly 205 arranged between the back-pressure turbine 202 and the high-pressure cylinder 102, for controlling the connection state of the back-pressure turbine and the high-pressure cylinder.

[0056] In some embodiments, the connecting assembly is a clutch. It can be understood that, in this embodiment, the back-pressure turbine and the high-pressure cylinder are coaxially arranged through the clutch, that is, the back-pressure turbine and the high-pressure cylinder share the same shaft or mechanical transmission system. The clutch can dynamically connect or separate the back-pressure turbine and the high-pressure cylinder to realize flexible input / output of the back-pressure turbine.

[0057] In some embodiments, in the case of long-term non-use of the back pressure turbine, the back pressure turbine can be considered to be in a shutdown state, and the connection between the back pressure turbine and the high pressure cylinder can be disconnected through the connection assembly, at which time the back pressure turbine is completely stopped and the high pressure cylinder is independently operated.

[0058] In some embodiments, in the case of short-term or temporary non-use of the back pressure turbine, the back pressure turbine can be considered to be in a standby state, and whether to disconnect the connection between the back pressure turbine and the high pressure cylinder can be determined according to the actual situation.

[0059] In some embodiments, in the case of short-term or temporary non-use of the back pressure turbine, the back pressure turbine can be considered to be in a standby state, and whether to disconnect the connection between the back pressure turbine and the high pressure cylinder can be determined according to the actual situation.

[0060] In some embodiments, in order to cooperate with the steam bypass (such as exhaust to the condenser), prevent the pressure from accumulating inside the back pressure turbine, and save energy, the connection between the back pressure turbine and the high pressure cylinder can be disconnected.

[0061] In some embodiments, for systems with high response speed requirements, the connection between the back pressure turbine and the high pressure cylinder can also be maintained.

[0062] In the above embodiments, on the one hand, the connection assembly is arranged between the back pressure turbine and the high pressure cylinder to realize coaxial arrangement of the back pressure turbine and the high pressure cylinder, without the need for an additional generator, which can save unit space and simplify the transmission. On the other hand, the connection assembly can flexibly switch the connection state between the back pressure turbine and the high pressure cylinder, which can dynamically start and stop the back pressure turbine without affecting the operation of the main unit.

[0063] In some embodiments, the coal-fired unit 10 can further include a first valve 206 between the boiler 101 and the back pressure turbine 202, and a second valve 207 between the back pressure turbine 202 and the feedwater heater 203.

[0064] The first valve 206 is used to control the on-off of the steam passage between the boiler and the back pressure turbine, and to control the steam flow into the back pressure turbine. The second valve 207 is used to control the on-off of the steam passage between the back pressure turbine and the feedwater heater.

[0065] Specifically, in the case of low load working condition of the coal-fired unit, the feedwater temperature is low, and the back pressure turbine needs to be started. At this time, the first valve and the second valve are fully opened, and the main steam can flow from the boiler to the back pressure turbine, and from the back pressure turbine to the feedwater heater. Further, the steam flow into the back pressure turbine can be controlled by adjusting the opening degree of the first valve. It can be understood that since the ultimate goal is to improve the feedwater temperature, only the main steam flow that can meet the feedwater temperature improvement needs to be extracted into the back pressure turbine.

[0066] In some embodiments, when the back pressure machine is in the shutdown state, the first valve and the second valve can be in the closed state. When the back pressure machine is in the hot standby state, the first valve is opened, the steam flow into the back pressure machine is controlled to be minimum, and the second valve is closed, the exhaust steam of the back pressure machine does not enter the newly added heater.

[0067] In the above embodiments, by setting the valves between the boiler and the back pressure machine, and between the back pressure machine and the feedwater heater, the on-off of the steam conveying pipe is accurately controlled, and the accuracy of the steam conveying control is improved.

[0068] In some embodiments, the coal-fired generating unit 10 can further include a condensing device 204 connected with the back pressure machine, which can be a condenser. The steam input end of the condensing device 204 is connected with the steam output end of the back pressure machine 202, for condensing the steam discharged by the back pressure machine 202. The condensing device 204 can also be a condenser 105 of the coal-fired generating unit. The condenser 105 is connected with the low-pressure heater. After the condenser 105 condenses the steam discharged by the back pressure machine 202 and the low-pressure cylinder 104 into water, the condensed water is conveyed to the low-pressure heater through a feedwater pipe for heating, and then after being treated by a deaerator, the condensed water is conveyed to the third high-pressure heater, the second high-pressure heater, the first high-pressure heater, and the feedwater heater for heating, and then to the boiler feedwater side. A third valve 208 is arranged between the back pressure machine 202 and the condensing device 204, for controlling the on-off of the steam conveying passage between the back pressure machine 202 and the condensing device 204.

[0069] Specifically, in the case that the back pressure machine is in the hot standby state, although its main function is temporarily disabled, it still needs to maintain a certain steam flow and temperature control to prevent equipment damage and ensure rapid response capability. Based on this, in order to avoid the accumulation of steam in the back pressure machine, which may cause a sudden rise in pressure and possibly lead to equipment damage, the present embodiment adds a condensing device, i.e., a condenser, connected with the back pressure machine. By opening the third valve, the exhaust steam of the back pressure machine is guided into the condenser, maintaining the low pressure at the outlet of the back pressure machine, thereby preventing overpressure of the back pressure machine.

[0070] In some embodiments, when the back pressure machine is in the shutdown state, the third valve is closed.

[0071] In some embodiments, the condensing device 204 can condense the steam discharged by the back pressure machine into water, and the condensed water can be returned to the low-pressure regenerative component, and after being treated by a deaerator, the condensed water is conveyed to the third high-pressure heater, the second high-pressure heater, the first high-pressure heater, and the feedwater heater for heating, and then to the boiler feedwater side.

[0072] In the above embodiments, by arranging the condensing device connected with the back pressure machine, the accumulation of steam in the back pressure machine can be avoided, thereby avoiding equipment damage and ensuring the safety and stability of the back pressure machine.

[0073] In some embodiments, the coal power unit 10 further comprises a fourth valve between the boiler 101 and the thermal cycle system 201, specifically a fourth valve 209 between the boiler 101 and the high-pressure cylinder 102, for controlling the steam admission amount of the thermal cycle system, or in other words, the steam admission amount of the high-pressure cylinder.

[0074] In some embodiments, the fourth valve 209 is a throttle valve, which can control the flow of fluid by adjusting the passage cross-sectional area, achieving precise control of the fluid flow.

[0075] Specifically, the boiler main steam is split before entering the throttle valve, and based on the feedwater heating demand of the coal power unit, the part of the main steam that meets the feedwater heating demand is made to work in the back pressure turbine, and the generated power is used for the on-grid power of the unit.

[0076] In combination with the above, it can be seen that the present scheme adds a back pressure turbine, which can transport part of the main steam to the back pressure turbine when the unit is in a medium and low load condition, reducing the throttling loss of part of the main steam, thereby reducing the coal consumption of the unit. The present scheme also adds a feedwater heater, and the heating steam of the feedwater heater comes from the exhaust steam of the back pressure turbine. On the one hand, it can dynamically increase the feedwater temperature based on the feedwater heating demand, achieving the purpose of on-demand heating of the feedwater, and on the other hand, it can further reduce the coal consumption and has energy-saving benefits. In addition, it can improve the steam utilization rate.

[0077] Furthermore, the present scheme sets a connecting assembly between the back pressure turbine and the high-pressure cylinder to realize coaxial arrangement of the back pressure turbine and the high-pressure cylinder, without the need for an additional generator, which can save unit space and simplify transmission. On the other hand, the connecting assembly can flexibly switch the connection state between the back pressure turbine and the high-pressure cylinder, which can dynamically put or remove the back pressure turbine without affecting the operation of the main unit.

[0078] Furthermore, the present scheme sets a condenser connected with the back pressure turbine, which can avoid accumulation of steam inside the back pressure turbine, thereby avoiding equipment damage and ensuring the safety and operation stability of the back pressure turbine.

[0079] In combination with the above, in some embodiments, as shown in Figure 4 A coal power unit control method is provided, and the method is applied to a controller of the coal power unit as an example for illustration, including the following steps:

[0080] Step S402, in response to a power generation instruction for the coal power unit, obtaining a target load of the coal power unit and a feedwater heating demand of the coal power unit.

[0081] The power generation instruction can be a control instruction for power generation operation of the coal-fired unit. The target load can be real-time load data of the coal-fired unit. The feedwater heating demand can be demand information for feedwater heating of the coal-fired unit, such as a target feedwater temperature, that is, the feedwater temperature needs to be raised to the target temperature. In addition to this, the feedwater heating demand can also include pressure demand, water quality demand, etc. The specific demand can be determined according to actual conditions, and the present embodiment does not limit this.

[0082] Specifically, the controller can obtain the operating condition information of the coal-fired unit from the management server of the thermal system of the coal-fired unit in response to the power generation instruction for the coal-fired unit. The operating condition information can include the real-time load of the coal-fired unit, in addition to which the operating condition information can also include the operating condition of the coal-fired unit, the electrical parameter of the coal-fired unit, etc. The feedwater heating demand can be pre-set or set in real time according to actual power generation conditions.

[0083] Step S404, in the case where the target load is lower than the rated load, the boiler is controlled to deliver first steam matching the feedwater heating demand to the back pressure turbine.

[0084] The rated load is the full load of the coal-fired unit, and the coal-fired unit is in a rated operating condition when the full load. The coal-fired unit can continuously output maximum power when operating in the rated operating condition. The target load being lower than the rated load means that the coal-fired unit is in a medium-low load operating condition, which can include a medium load operating condition or a low load operating condition. It should be understood that in the medium-low load operating condition, the feedwater temperature is low, and the back pressure turbine needs to be started and part of the main steam needs to be delivered to the back pressure turbine. The first steam is the main steam delivered to the back pressure turbine, and the back pressure turbine delivers the first steam to the feedwater heater to further heat the feedwater.

[0085] In some embodiments, the controller can control the first valve provided between the boiler and the back pressure turbine and the second valve provided between the back pressure turbine and the feedwater heater to be in an open state, so that the boiler delivers the first steam to the back pressure turbine, and the back pressure turbine delivers the first steam to the feedwater heater.

[0086] In some embodiments, the controller can monitor the change of the feedwater temperature in real time, and dynamically adjust the first valve to be larger or smaller, so as to control the steam admission amount of the back pressure turbine.

[0087] Step S406, determining a target steam admission amount for the thermal cycle system, and controlling the boiler to deliver second steam to the thermal cycle system according to the target steam admission amount.

[0088] The target steam intake refers to the steam intake of the thermal cycle system, or the steam intake of the high-pressure cylinder. The second steam refers to the main steam delivered to the thermal cycle system, or the main steam delivered by the boiler to the high-pressure cylinder. In an example, the sum of the steam intakes of the back-pressure turbine and the high-pressure cylinder can be equal to the total flow of the main steam.

[0089] Specifically, the controller can further determine the steam intake of the high-pressure cylinder, so as to control the boiler to deliver steam to the high-pressure cylinder according to the steam intake. The high-pressure cylinder can deliver the second steam to the feedwater heater through the high-pressure regenerative component for further heating of the feedwater.

[0090] Step S408: obtaining a feedwater heating result. The feedwater heating result is obtained by the feedwater heater based on the first steam delivered by the back-pressure turbine and the second steam delivered by the thermal cycle system, and heating the feedwater entering the boiler.

[0091] Specifically, the feedwater heater can heat the feedwater entering the boiler based on the first steam discharged by the back-pressure turbine and the second steam discharged by the high-pressure cylinder. In this process, the controller can monitor the feedwater heating in real time and obtain the feedwater heating result, such as the feedwater temperature, the feedwater heating time, etc. The controller can also adjust the feedwater heating demand based on the feedwater heating result, so as to dynamically control the steam intake of the back-pressure turbine.

[0092] In the above embodiment, when the coal-fired unit is in a medium-low load condition, a part of the boiler steam matched with the feedwater heating demand can be extracted into the back-pressure turbine to do work based on the feedwater heating demand. Further, the back-pressure turbine can deliver the part of the boiler steam to the feedwater heater, and the feedwater heater can heat the boiler feedwater based on the part of the steam. In this way, the increase of the feedwater temperature can be ensured, and the feedwater temperature can also meet the feedwater heating demand. Thus, the coal consumption of the unit can be reduced, and further, the throttling loss of the coal-fired unit under the medium-low load condition can be reduced, and the economic efficiency of the wide load operation of the coal-fired unit can be realized.

[0093] In some embodiments, as shown in Figure 5 The coal-fired unit further includes a condensing device and a connecting component, the thermal cycle system includes a high-pressure cylinder, a third valve is further arranged between the back-pressure turbine and the condensing device, and the coal-fired unit control method further includes:

[0094] Step S502: obtaining an operation state of the back-pressure turbine when the target load is not lower than the rated load.

[0095] The running state can refer to a running state of the back pressure machine, including a stop state and a standby state. It should be understood that the target load being not lower than the rated load means that the coal power unit is in a rated working condition or a high load working condition, at which time the feed water temperature is high, and the back pressure machine does not need to be started. There are two cases when the back pressure machine is not started, one is that the back pressure machine is completely stopped, and the other is that the back pressure machine is in a standby state and can be quickly put into operation at any time.

[0096] In step S504, when the back pressure machine is in the stop state, the first valve, the second valve and the third valve are controlled to be in the closed state, and the connection assembly is controlled to disconnect the back pressure machine from the high-pressure cylinder.

[0097] Specifically, when the back pressure machine is in the stop state, the first valve, the second valve and the third valve are controlled to be fully closed, and the connection assembly is used to disconnect the back pressure machine from the high-pressure cylinder, so that the back pressure machine is completely isolated from the thermal cycle system.

[0098] In step S506, when the back pressure machine is in the standby state, the minimum steam admission amount of the back pressure machine is determined.

[0099] The minimum steam admission amount refers to the minimum steam flow lower limit that must be maintained by the back pressure turbine in the standby state. The minimum steam admission amount can maintain the operating temperature of the back pressure machine and ensure its rapid operation capability.

[0100] In step S508, the first valve and the third valve are controlled to be in the open state, and the second valve is controlled to be in the closed state, so that the boiler delivers the third steam matching the minimum steam admission amount to the back pressure machine, and the back pressure machine delivers the third steam to the condenser.

[0101] Specifically, when the back pressure machine is in the standby state, the controller controls the first valve and the third valve to be fully open, and the second valve to be closed. In this way, the boiler can deliver the third steam matching the minimum steam admission amount to the back pressure machine, and the back pressure machine further discharges the third steam into the condenser for condensation.

[0102] In some embodiments, the controller can adjust the opening degree of the first valve to match the minimum steam admission amount of the back pressure machine, so that the boiler delivers the third steam matching the minimum steam admission amount to the back pressure machine.

[0103] In the above embodiments, different opening and closing controls of the valves are performed for the stop state and the standby state of the back pressure machine respectively, so as to realize precise control of the back pressure machine. In addition, the connection assembly and the condenser are introduced to disconnect the back pressure machine from the high-pressure cylinder when the back pressure machine is stopped, so that the back pressure machine is completely isolated from the thermal cycle system, and the exhaust steam of the back pressure machine is condensed when the back pressure machine is in the standby state, which can prevent the back pressure machine from overpressure and ensure the safety of the equipment of the back pressure machine.

[0104] It should be understood that although the steps in the flowcharts involved in the embodiments described above are shown in sequence according to the arrows, the steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, the execution of the steps is not strictly limited in sequence, and the steps can be executed in other orders. Moreover, at least some of the steps in the flowcharts involved in the embodiments described above can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution of the steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least part of other steps or stages.

[0105] Based on the same inventive concept, the embodiments of the present application also provide a coal-fired power unit control device for implementing the coal-fired power unit control method described above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme described in the above method, so the specific limitations in one or more coal-fired power unit control device embodiments provided below can refer to the limitations of the coal-fired power unit control method described above, which will not be repeated here.

[0106] In one exemplary embodiment, as shown in Figure 6 A coal-fired power unit control device is provided, comprising:

[0107] The information acquisition module 602 is configured to acquire the target load of the coal-fired power unit and the feedwater heating demand of the coal-fired power unit in response to the power generation instruction for the coal-fired power unit.

[0108] The first steam delivery control module 604 is configured to control the boiler to deliver the first steam matching the feedwater heating demand to the back pressure turbine when the target load is lower than the rated load.

[0109] The second steam delivery control module 606 is configured to determine the target steam admission amount for the thermal cycle system and control the boiler to deliver the second steam to the thermal cycle system according to the target steam admission amount.

[0110] The result acquisition module 608 is configured to acquire the feedwater heating result, which is the result obtained by the feedwater heater heating the feedwater entering the boiler based on the first steam delivered by the back pressure turbine and the second steam delivered by the thermal cycle system.

[0111] In one embodiment, a first valve is arranged between the boiler and the back pressure turbine, and a second valve is arranged between the back pressure turbine and the feedwater heater.

[0112] The first steam control module 604 is further configured to control the first valve and the second valve to be in an open state, so that the boiler supplies the back pressure machine with first steam matching the water heating demand, and the back pressure machine supplies the water heater with the first steam.

[0113] In one of the embodiments, the coal-fired unit further comprises a condenser and a connecting assembly, a third valve is arranged between the back pressure machine and the condenser, and the thermal cycle system comprises a high-pressure cylinder; the coal-fired unit control device further comprises:

[0114] The operation state acquisition module is configured to acquire the operation state of the back pressure machine when the target load is not lower than the rated load;

[0115] The first control module is configured to control the first valve, the second valve and the third valve to be in a closed state when the back pressure machine is in a shutdown state, and control the back pressure machine to be disconnected from the high-pressure cylinder through the connecting assembly;

[0116] The steam intake amount determination module is configured to determine the minimum steam intake amount of the back pressure machine when the back pressure machine is in a standby state;

[0117] The second control module is configured to control the first valve and the third valve to be in an open state, and the second valve to be in a closed state, so that the boiler supplies the back pressure machine with third steam matching the minimum steam intake amount, and the back pressure machine supplies the condenser with the third steam.

[0118] The above-mentioned modules in the coal-fired unit control device can be realized by software, hardware or a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in hardware form, or stored in the memory in the computer device in software form, so as to be called and executed by the processor to perform the operations corresponding to the above-mentioned modules.

[0119] In one exemplary embodiment, a computer device is provided, which can be a server, and the internal structure diagram thereof can be as shown in Figure 7The computer device shown in the figure includes a processor, a memory, an input / output interface (I / O for short), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store coal-fired generating unit control data. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals through network connection. The computer program is executed by the processor to implement a coal-fired generating unit control method.

[0120] Those skilled in the art can understand that, Figure 7 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. A specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0121] In one exemplary embodiment, a computer device is provided, including a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the following steps:

[0122] In response to a power generation instruction for the coal-fired generating unit, obtaining a target load of the coal-fired generating unit and a feedwater heating demand of the coal-fired generating unit;

[0123] In the case where the target load is lower than the rated load, controlling the boiler to deliver first steam matching the feedwater heating demand to the back pressure turbine;

[0124] Determining a target steam admission amount for the thermal cycle system, and controlling the boiler to deliver second steam to the thermal cycle system according to the target steam admission amount;

[0125] Obtaining a feedwater heating result, which is a result obtained by the feedwater heater heating the feedwater entering the boiler based on the first steam delivered by the back pressure turbine and the second steam delivered by the thermal cycle system.

[0126] In one embodiment, the processor executing the computer program further implements the following steps: controlling the first valve and the second valve to be in an open state, so that the boiler delivers first steam matching the feedwater heating demand to the back pressure turbine, and the first steam is delivered to the feedwater heater through the back pressure turbine.

[0127] In one embodiment, the computer program, when executed by the processor, further implements the following steps:

[0128] In the case where the target load is not lower than the rated load, obtaining the running state of the back pressure machine;

[0129] In the case where the back pressure machine is in the shutdown state, controlling the first valve, the second valve and the third valve to be in the closed state, and controlling the back pressure machine to be disconnected from the high-pressure cylinder through the connecting assembly;

[0130] In the case where the back pressure machine is in the standby state, determining the minimum steam admission amount of the back pressure machine;

[0131] Controlling the first valve and the third valve to be in the open state, and the second valve to be in the closed state, so that the boiler delivers the third steam matching the minimum steam admission amount to the back pressure machine, and the back pressure machine delivers the third steam to the condenser.

[0132] In one embodiment, a computer readable storage medium is provided, and the computer readable storage medium stores a computer program, and the computer program, when executed by the processor, implements the following steps:

[0133] In response to the power generation instruction for the coal-fired power unit, obtaining the target load of the coal-fired power unit and the feedwater heating demand of the coal-fired power unit;

[0134] In the case where the target load is lower than the rated load, controlling the boiler to deliver the first steam matching the feedwater heating demand to the back pressure machine;

[0135] Determining the target steam admission amount for the thermal cycle system, and controlling the boiler to deliver the second steam to the thermal cycle system according to the target steam admission amount;

[0136] Obtaining the feedwater heating result, which is a result obtained by the feedwater heater based on the first steam delivered by the back pressure machine and the second steam delivered by the thermal cycle system, and heating the feedwater entering the boiler.

[0137] In one embodiment, the computer program, when executed by the processor, further implements the following steps: controlling the first valve and the second valve to be in the open state, so that the boiler delivers the first steam matching the feedwater heating demand to the back pressure machine, and the back pressure machine delivers the first steam to the feedwater heater.

[0138] In one embodiment, the computer program, when executed by the processor, further implements the following steps:

[0139] In the case where the target load is not lower than the rated load, obtaining the running state of the back pressure machine;

[0140] When the back pressure machine is in a shutdown state, the first valve, the second valve, and the third valve are controlled to be in a closed state, and the back pressure machine is controlled to be disconnected from the high pressure cylinder through the connecting assembly;

[0141] When the back pressure machine is in a standby state, a minimum steam admission amount of the back pressure machine is determined;

[0142] The first valve and the third valve are controlled to be in an open state, and the second valve is controlled to be in a closed state, so that the boiler delivers third steam matching the minimum steam admission amount to the back pressure machine, and the back pressure machine delivers the third steam to the condenser.

[0143] In one embodiment, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the following steps:

[0144] In response to a power generation instruction for the coal-fired power unit, a target load of the coal-fired power unit and a feedwater heating demand of the coal-fired power unit are obtained;

[0145] When the target load is lower than the rated load, the boiler is controlled to deliver first steam matching the feedwater heating demand to the back pressure machine;

[0146] A target steam admission amount for the thermal cycle system is determined, and the boiler is controlled to deliver second steam to the thermal cycle system according to the target steam admission amount;

[0147] A feedwater heating result is obtained; the feedwater heating result is a result obtained by the feedwater heater heating the feedwater entering the boiler based on the first steam delivered by the back pressure machine and the second steam delivered by the thermal cycle system. In one embodiment, the computer program, when executed by the processor, further implements the following steps: the first valve and the second valve are controlled to be in an open state, so that the boiler delivers first steam matching the feedwater heating demand to the back pressure machine, and the back pressure machine delivers the first steam to the feedwater heater.

[0148] In one embodiment, the computer program, when executed by the processor, further implements the following steps:

[0149] When the target load is not lower than the rated load, an operating state of the back pressure machine is obtained;

[0150] When the back pressure machine is in a shutdown state, the first valve, the second valve, and the third valve are controlled to be in a closed state, and the back pressure machine is controlled to be disconnected from the high pressure cylinder through the connecting assembly;

[0151] When the back pressure machine is in a standby state, a minimum steam admission amount of the back pressure machine is determined;

[0152] The first valve and the third valve are controlled to be in an open state, and the second valve is controlled to be in a closed state, so that the boiler delivers the third steam matching the minimum steam admission to the back pressure machine, and the third steam is delivered to the condenser by the back pressure machine.

[0153] It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or authorized by all parties, and the collection, use and processing of related data need to comply with relevant regulations.

[0154] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiment methods. Any reference to memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. The non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. The volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration but not limitation, the RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., without being limited thereto.

[0155] The technical features of the above embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0156] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific manner, but should not be construed as limiting the scope of the patent of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A coal-fired power unit, characterized in that, The coal-fired power unit includes: a boiler, a thermal circulation system, a back pressure turbine, and a feedwater heater; The steam output end of the boiler is connected to the steam input end of the back pressure machine and the steam input end of the thermal cycle system, respectively. The steam output end of the back pressure unit is connected to the steam input end of the feedwater heater, and the feedwater output end of the thermal circulation system is connected to the feedwater input end of the feedwater heater; the steam output from the back pressure unit is used to heat the feedwater input to the feedwater heater from the thermal circulation system. The water supply output end of the water heater is connected to the water supply end of the boiler.

2. The coal-fired power unit according to claim 1, characterized in that, The thermal circulation system includes a high-pressure cylinder and a high-pressure regeneration component. The steam input end of the thermal circulation system includes the steam input end of the high-pressure cylinder and the steam input end of the high-pressure regeneration component. The water supply output end of the thermal circulation system includes the water supply output end of the high-pressure regeneration component. The steam input end of the high-pressure cylinder is connected to the steam output end of the boiler; The steam input end of the high-pressure regenerative component is connected to the steam output end of the high-pressure cylinder, and the water supply output end of the high-pressure regenerative component is connected to the water supply input end of the water supply heater.

3. The coal-fired power unit according to claim 2, characterized in that, The coal-fired power unit also includes a connection assembly; The connecting component is disposed between the back pressure machine and the high-pressure cylinder, and is used to control the connection status between the back pressure machine and the high-pressure cylinder.

4. The coal-fired power unit according to claim 1, characterized in that, A first valve is provided between the boiler and the back pressure machine to control the opening and closing of the steam transmission channel between the boiler and the back pressure machine.

5. The coal-fired power unit according to claim 1, characterized in that, A second valve is provided between the back pressure unit and the feedwater heater to control the opening and closing of the steam transmission channel between the back pressure unit and the feedwater heater.

6. The coal-fired power unit according to claim 1, characterized in that, The coal-fired power unit also includes condensing devices; The steam input end of the condenser is connected to the steam output end of the back pressure machine, and is used to condense the steam discharged from the back pressure machine.

7. The coal-fired power unit according to claim 6, characterized in that, A third valve is provided between the back pressure unit and the condensing device to control the opening and closing of the steam transmission channel between the back pressure unit and the condensing device.

8. A control method for a coal-fired power unit, characterized in that, Applied to any one of claims 1 to 7, the method comprises: In response to a power generation command for the coal-fired power unit, the target load of the coal-fired power unit and the feedwater heating requirements of the coal-fired power unit are obtained; When the target load is lower than the rated load, the boiler is controlled to supply the back pressure unit with first steam that matches the feedwater heating demand; Determine the target steam intake for the thermal cycle system, and control the boiler to supply second steam to the thermal cycle system according to the target steam intake; Obtain the feedwater heating result; the feedwater heating result is the result obtained by the feedwater heater heating the feedwater entering the boiler based on the first steam delivered by the back pressure machine and the second steam delivered by the thermal cycle system.

9. The method according to claim 8, characterized in that, A first valve is provided between the boiler and the back pressure machine, and a second valve is provided between the back pressure machine and the feedwater heater; The control of the boiler to supply first steam to the back pressure unit in accordance with the feedwater heating demand includes: The first valve and the second valve are both controlled to be in the open state, so that the boiler delivers first steam to the back pressure machine that matches the feedwater heating demand, and the first steam is delivered to the feedwater heater through the back pressure machine.

10. The method according to claim 9, characterized in that, The coal-fired power unit further includes a condensing device and a connecting assembly; a third valve is provided between the back pressure compressor and the condensing device; the thermal circulation system includes a high-pressure cylinder; the method further includes: Under the condition that the target load is not lower than the rated load, the operating status of the back pressure machine is obtained; When the back pressure machine is in a stopped state, the first valve, the second valve, and the third valve are all closed, and the back pressure machine is disconnected from the high-pressure cylinder through the connection assembly; When the back pressure unit is in standby mode, determine the minimum steam intake of the back pressure unit; The first valve and the third valve are controlled to be in the open state, and the second valve is in the closed state, so that the boiler delivers a third steam that matches the minimum steam intake to the back pressure unit, and the third steam is delivered to the condensing device through the back pressure unit.

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