Adjusting system and method for rapid load change of coal-fired power generation unit

Abstract

The invention provides an adjusting system and method for rapid load change of a coal-fired power generation unit, and relates to the technical field of coupling heat storage rapid peak regulation. The adjusting system comprises a heat storage device used for extracting and cooling main steam flowing through a main steam pipeline so as to form a steam-water mixture in the heat storage device; the feed water heating device is used for heating the feed water fed into the coal economizer by utilizing the steam-water mixture in the heat storage device; and the hot air heating device is used for heating hot air sent out from the air outlet of the air pre-heater through main steam, the hot air is heated by the main steam and then becomes first steam to enter the feed water heating device, and the feed water heating device can further heat feed water sent into the economizer through the first steam. According to the adjusting system and method, the heat storage capacity of the coal-fired power generation unit is improved, the heat storage capacity of the heat storage device is improved, and therefore the load adjusting rate of the unit is increased, and the problem that in the prior art, the variable load adjusting rate of the coal-fired power generation unit is insufficient is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coupled heat storage rapid peak regulation, and in particular to a rapid load change regulation system for a coal-fired generator set and a rapid load change regulation method for a coal-fired generator set. Background Art

[0002] Under the new power system situation, the installed capacity and power generation of new energy are increasing day by day. However, the high proportion of new energy grid connection has changed the dynamic characteristics of the power system, making the long-term, medium-term and intraday balance of the power system gradually more difficult, thus requiring coal-fired units to further play the basic guarantee and system regulation functions. The flexible transformation of coal-fired units has played an important role in the consumption of new energy in recent years.

[0003] At present, coal-fired power units mainly control the load of the unit and meet the unit's requirements for load response rate by controlling the amount of fuel entering the boiler and the main steam valve opening on the turbine side during the load increase and decrease stages. This type of regulation is usually accompanied by many problems such as large fluctuations in the main steam parameters of the unit and reduced economy. In addition, the large delay inertia of the boiler system itself also limits the unit's ability to quickly change loads, resulting in the current peak-shaving rate of boilers above 300MW at 50%~100% rated load of about 1.5% rated load / minute, and the peak-shaving rate under the deep peak-shaving state of about 30% load is generally less than 1% rated load / minute. With the increasing proportion of new energy, the load-changing rate of about 1%~1.5% can no longer meet the requirements of rapid peak-shaving.

[0004] Therefore, it is urgent to develop a high-efficiency device to improve the unit's rapid load change capability. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a system and method for regulating rapid load change of a coal-fired power generation unit, so as to solve the problem of insufficient load change rate of regulating a coal-fired power generation unit in the prior art.

[0006] In order to achieve the above object, the present invention provides a regulation system for rapid load change of a coal-fired power generation unit, which is connected to the economizer, deaerator, air preheater and main steam pipeline of the coal-fired power generation unit, and the regulation system comprises: a heat storage device connected to the main steam pipeline, used to extract and cool down the main steam flowing through the main steam pipeline to form a steam-water mixture in the heat storage device; A feed water heating device, used for heating the feed water sent to the economizer by using the steam-water mixture in the heat storage device, the steam-water mixture loses heat after heating the feed water and becomes hydrophobic and finally enters the deaerator; The hot air heating device is connected to the main steam pipeline, the air outlet of the air preheater and the inlet end of the feed water heating device, and is used for utilizing the main steam to heat the hot air sent out from the air outlet of the air preheater. After the main steam heats the hot air, it loses heat and becomes the first steam that enters the feed water heating device, wherein the feed water heating device can also utilize the first steam to heat the feed water sent to the economizer.

[0007] Specifically, the feedwater heating device includes: a first heater and a second heater; The first heater is used to preliminarily heat the feed water sent to the economizer by using a hot working medium, and the hot working medium loses heat and becomes drain water sent to the deaerator; The second heater is connected to the steam outlet of the heat storage device and is used to heat the preliminarily heated feed water using the steam-water mixture. After losing heat, the steam-water mixture becomes steam and enters the first heater.

[0008] Specifically, the regulating system also includes: a spraying device, which is arranged in the heat storage device and connected to the feed water outlet of the first heater, and is used to spray the initially heated feed water into the heat storage device to cool the main steam and thus form a steam-water mixture.

[0009] Specifically, the spray device includes: a spray head, a cooling water pipe and a cooling water valve; One end of the desuperheating water pipe is connected to the spray head, and the other end is connected to the water outlet of the first heater. The desuperheating water pipe is used to transport the preliminarily heated water to the spray head; The spray head is arranged in the heat storage device, and is used to spray the preliminarily heated feed water into the heat storage device; The desuperheating water valve is arranged on the desuperheating water pipe, and is used to control the flow state of the feed water after preliminary heating in the desuperheating water pipe.

[0010] Specifically, the regulating system further includes: a first valve group, a second valve group and a control valve group; The first valve group is arranged between the hot air heating device and the main steam pipeline, the second valve group is arranged between the heat storage device and the main steam pipeline, and the control valve group is arranged between the second heater and the heat storage device.

[0011] Specifically, the first valve group, the second valve group and the control valve group each include a shut-off valve, a regulating valve and a pressure reducing valve.

[0012] Another aspect of the present invention provides a method for regulating rapid load change of a coal-fired power generation set, which is implemented based on any of the above-mentioned regulating systems for rapid load change of a coal-fired power generation set. The method for regulating rapid load change of a coal-fired power generation set comprises: Continuously obtain the current load of coal-fired generating units; If a load reduction instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the first load, main steam flowing through the main steam pipeline of the coal-fired power generation unit is extracted, and the main steam is cooled to form a steam-water mixture for storage; If a load reduction instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the second load, main steam flowing through the main steam pipeline of the coal-fired power generation unit is extracted, and the main steam is used to heat the hot air sent out from the air outlet of the air preheater of the coal-fired power generation unit, and the main steam loses heat and becomes the first steam, and the first steam is also used to heat the feed water sent to the economizer; If a load increase instruction is received from a coal-fired power generation unit, and the current load of the coal-fired power generation unit is the second load, the amount of main steam extracted from the main steam pipeline of the coal-fired power generation unit is gradually reduced, and at the same time, the stored steam-water mixture is used to heat the feed water sent to the economizer of the coal-fired power generation unit, and the steam-water mixture loses heat and becomes water-repellent; If a load increase instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the first load, the steam-water mixture stored in the heat storage device is used to heat the feed water sent to the economizer of the coal-fired power generation unit.

[0013] Specifically, the regulating method further comprises: utilizing the hot working medium to preliminarily heat the feed water sent to the economizer of the coal-fired power generation unit.

[0014] Specifically, the primary heated feed water is used to cool down the main steam to form a steam-water mixture.

[0015] Specifically, the first load is greater than 40% of the rated load of the coal-fired power generation unit, and the second load is less than or equal to 40% of the rated load of the coal-fired power generation unit.

[0016] The present invention provides a rapid load-changing regulation system for a coal-fired generator set, in which a heat storage device is connected to a main steam pipeline of the coal-fired generator set, and the amount of steam flowing through the main steam pipeline is extracted to regulate the amount of steam entering the high-pressure cylinder of the turbine of the coal-fired generator set through the main steam pipeline, thereby regulating the load of the coal-fired generator set. When the load is reduced, the main steam flowing through the main steam pipeline is extracted to the heat storage device, the main steam entering the heat storage device is cooled so that the main steam becomes a steam-water mixture and the steam-water mixture is stored, or when the load is reduced, the main steam flowing through the main steam pipeline is extracted to heat the hot air sent from the air preheater, further increasing the temperature of the hot air finally sent to the boiler of the coal-fired generator set. In this way, when the coal-fired generator set needs to reduce the load, the main steam flowing through the main steam pipeline is extracted, the steam intake of the steam turbine of the coal-fired generator set is reduced, so that the load of the coal-fired generator set is reduced, and the main steam is directly extracted from the main steam pipeline, which increases the load reduction rate of the coal-fired generator set; when the load is increased, the main steam extraction volume of the main steam pipeline for heating the hot air is reduced, and the steam volume of the main steam entering the high-pressure cylinder is increased, or when the load is increased, the steam-water mixture stored in the heat storage device is used to heat the feed water sent to the economizer of the coal-fired generator set again, which increases the heat of the feed water sent to the boiler of the coal-fired generator set and improves the load increase rate of the coal-fired generator set. The system and method for regulating the rapid load change of a coal-fired power generation unit provided by the present invention improve the heat storage capacity of the coal-fired power generation unit itself and the heat storage capacity of the heat storage device, thereby improving the load regulation rate of the unit and solving the problem of insufficient load variation rate of regulating the coal-fired power generation unit in the prior art.

[0017] The main beneficial effects of the present invention are as follows: (1) Using heat storage devices to improve the load increase / decrease rate of the unit: When the coal-fired power generation unit needs to reduce its load, on the one hand, the main steam is extracted from the main steam pipeline and stored in the heat storage device to achieve rapid load reduction of the unit; on the other hand, the main steam extracted from the main steam pipeline is used to heat the hot air discharged from the air preheater and then enters the feed water heater device to heat the feed water sent to the economizer, thereby quickly reducing the steam intake of the steam turbine and achieving rapid load reduction. When the coal-fired power generation unit needs to increase its load, the extraction volume of the main steam for heating the hot air is gradually reduced, and the steam-water mixture stored in the heat storage device is used to heat the feed water. The feed water eventually enters the boiler and becomes steam and enters the high-pressure cylinder and heat recovery system of the steam turbine, thereby quickly improving the load increase rate of the unit.

[0018] (2) Solve the problem of low-load denitrification inlet under-temperature: When the low-load denitrification inlet is under-temperature, part of the main steam is extracted to enter the hot air heating device to heat the hot air. The main steam is cooled down to become the first steam and enters the feed water heating device to heat the feed water. This can significantly increase the feed water temperature and reduce the heat absorption of the economizer, thereby greatly increasing the denitrification inlet flue gas temperature and meeting the low-load denitrification requirements.

[0019] (3) Increasing the low-load feed water temperature and reheat steam temperature to improve the economy of coal-fired power generation units: Under low load, part of the main steam in the main steam pipe is extracted to heat the hot air and feed water. On the one hand, it leads to a decrease in the steam flow through the boiler reheater of the coal-fired power generation unit, an increase in the heat absorption per unit mass of the working fluid in the reheater, and an increase in the reheat steam temperature. On the other hand, the feed water temperature under low load is increased. Both can improve the economy of the coal-fired power generation unit under low load.

[0020] (4) Improving the deep load hydraulic performance of coal-fired power generation units, further lowering the dry-wet state conversion point, and improving the unit's safety performance: Under deep load, the boiler sends high-temperature, high-pressure main steam to the steam turbine. Before entering the steam turbine, part of the main steam is extracted to the hot air heating device to heat the hot air, and then loses heat and further enters the feed water heating device to heat the feed water. The feed water finally enters the boiler. In essence, an internal circulation is formed in the boiler, which greatly improves the deep load hydraulic performance of the unit, further lowers the dry-wet state conversion point, and greatly improves the unit's safety performance.

[0021] (5) Improving the low-load combustion capacity of the boiler: Using a hot air heating device to further increase the temperature of the hot air entering the boiler under low load can significantly enhance the combustion and burnout performance of pulverized coal, and improve the low-load stable combustion capacity and combustion efficiency of the unit.

[0022] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a structural schematic diagram of a regulation system for rapid load change of a coal-fired power generation unit provided by an embodiment of the present invention; Figure 2 It is a dynamic diagram of the variable load condition of the action of the first valve group on the auxiliary pipeline in the regulation system of the rapid variable load of the coal-fired power generation unit provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the variable load characteristics of a conventional coal-fired generating unit; Figure 4 The present invention is a schematic diagram of the load variation characteristics of a regulation system for rapid load variation of a coal-fired power generation unit provided by an embodiment of the present invention.

[0024] Figure 5 It is a collection diagram of the opening and closing states of each control valve group in a rapid load change system of a coal-fired power generation unit provided by an embodiment of the present invention.

[0025] Description of Reference Numerals 1-high-pressure cylinder; 2-main steam pipeline; 3-extraction pipeline; 4-superheater; 5-first valve group; 6-second valve group; 7-heat storage device; 8-spraying device; 9-cooling water pipe; 10-cooling water valve; 11-feedwater pipeline; 12-first heater; 13-second heater; 14-energy release pipeline; 15-control valve group; 16-drain pipeline; 17-hot air heating device; 18-hot air pipeline; 19-air preheater; 20-air cooler; 21-economizer; 22-auxiliary pipeline. DETAILED DESCRIPTION

[0026] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0027] Figure 1 It is a structural schematic diagram of the regulation system for rapid load changes of coal-fired power generation units; Figure 2 It is a dynamic diagram of the variable load condition of the first valve group action on the auxiliary pipeline in the regulation system of the rapid variable load of the coal-fired power generation unit; Figure 3 It is a schematic diagram of the variable load characteristics of a conventional coal-fired generating unit; Figure 4 It is a schematic diagram of the variable load characteristics of the regulation system of the rapid variable load of the coal-fired power generation unit; Figure 5 It is a collection diagram of the opening and closing states of each control valve group in the rapid load change system of a coal-fired generator set.

[0028] like Figure 1-Figure 5 As shown, the present invention provides a rapid load-changing regulation system for a coal-fired power generation unit, which is connected to the economizer 21, the deaerator, the air preheater 19 and the main steam pipeline 2 of the coal-fired power generation unit, and the regulation system includes: a heat storage device 7 connected to the main steam pipeline 2, and used to extract and cool down the main steam flowing through the main steam pipeline 2, so as to form a steam-water mixture in the heat storage device 7; A feed water heating device, used to heat the feed water sent to the economizer 21 by using the steam-water mixture in the heat storage device 7, and the steam-water mixture loses heat after heating the feed water to become hydrophobic water and finally enters the deaerator; The hot air heating device 17 is connected to the main steam pipe 2, the air outlet of the air preheater 19 and the inlet end of the feed water heating device, and is used to use the main steam to heat the hot air sent out from the air outlet of the air preheater 19. After the main steam heats the hot air, it loses heat and becomes the first steam that enters the feed water heating device, wherein the feed water heating device can also use the first steam to heat the feed water sent to the economizer 21.

[0029] The rapid load-changing regulation system for a coal-fired generator set provided by the present invention can adjust the load of the coal-fired generator set by extracting the steam volume of the main steam of the main steam pipe 2 of the coal-fired generator set, wherein one end of the main steam pipe 2 is connected to the superheater 4, and the other end is connected to the high-pressure cylinder 1 of the steam turbine. When the coal-fired power generation unit needs to reduce its load, the main steam flowing through the main steam pipe 2 is extracted, so that the amount of steam entering the high-pressure cylinder 1 of the coal-fired power generation unit is reduced, and the extracted main steam can be directly sent to the hot air heating device 17. The hot air heating device 17 uses the main steam to heat the hot air sent out from the air outlet of the air preheater 19. After the main steam heats the hot air, the temperature is reduced to become the first steam, which is sent to the feed water heating device. The waste heat of the first steam can also be used to heat the feed water sent to the economizer 21; the extracted main steam can also be cooled in the heat storage device 7 to form a steam-water mixture, and the steam-water mixture is stored in the heat storage device 7. The heat storage device 7 is a heat storage tank. Afterwards, when the coal-fired power generation unit needs to increase its load, the steam-water mixture in the heat storage device 7 can be sent to the feed water heating device to heat the feed water sent to the economizer 21, thereby improving the load increase rate of the coal-fired power generation unit and solving the problem of insufficient load change rate of the coal-fired power generation unit in the prior art.

[0030] In one embodiment, Figure 1 As shown, the feedwater heating device comprises: a first heater 12 and a second heater 13; The first heater 12 is used to preliminarily heat the feed water sent to the economizer 21 by using the hot working medium, and the hot working medium loses heat and becomes drain water sent to the deaerator; The second heater 13 is connected to the steam outlet of the heat storage device 7 and is used to heat the preliminarily heated feed water using the steam-water mixture. After losing heat, the steam-water mixture becomes steam and enters the first heater 12 .

[0031] The water supply inlet of the first heater 12 is connected to the water supply pipe 11, the water supply outlet of the first heater 12 is connected to the water supply inlet of the second heater 13 through a first connecting pipe, the drain inlet of the first heater 12 and the drain outlet of the second heater 13 are connected through a drain pipe 16, the steam inlet of the second heater 13 is connected to the steam outlet of the heat storage device 7 through an energy release pipe 14, and the steam inlet of the second heater 13 serves as the inlet end of the water supply heating device; the first heater 12 and the second heater 13 are both high-pressure heaters.

[0032] When the coal-fired power generation unit increases its load, the steam-water mixture flows out from the steam outlet of the heat storage device 7 and enters the second heater 13 through the energy release pipe 14 and the steam inlet of the second heater 13. The feed water flows through the feed water pipe 11 and first enters the first heater 12. The first heater 12 uses a hot working medium to preliminarily heat the feed water. The hot working medium can be the main steam extracted from the main steam channel 2, the steam-water mixture stored in the heat storage device 7, the various stages of extraction steam of the steam turbine of the coal-fired power generation unit, and / or the steam-water mixture that becomes drain after losing heat. The preliminarily heated feed water enters the second heater 13 to exchange heat with the steam-water mixture that enters the second heater 13 at the same time. The steam-water mixture heats the preliminarily heated feed water, so that the feed water temperature increases again. The feed water heated for the second time by the second heater 13 flows out and enters the economizer 21, and the steam-water mixture loses heat and becomes drain and flows out from the drain outlet of the second heater 13 through the drain pipe 16 and the first The drain inlet of the heater 12 enters the first heater 12. After entering the first heater 12, the drain can heat the feed water entering the first heater 12, that is, the residual heat of the drain is used to preliminarily heat the feed water entering the first heater 12. After the drain preliminarily heats the feed water, it enters the deaerator connected to the first heater 12. In order to control the flow state of the steam-water mixture in the energy release pipeline 14, a control valve group 15 is arranged on the energy release pipeline 14. The control valve group 15 includes a shut-off valve, a regulating valve and a pressure reducing valve. When the shut-off valve in the control valve 15 is opened, the steam-water mixture in the heat storage device 7 enters the second heater 13 through the energy release pipeline 14. When the shut-off valve in the control valve group 15 is closed, the steam-water mixture cannot enter the second heater 13. The regulating valve in the control valve group 15 can adjust the flow rate of the steam-water mixture entering the second heater 13. The pressure reducing valve in the control valve group 15 can adjust the pressure of the steam-water mixture entering the second heater 13.

[0033] In order to cool the main steam entering the heat storage device 7, the regulating system also includes: a spraying device 8, which is arranged in the heat storage device 7 and connected to the water supply outlet of the first heater 12, and is used to spray the initially heated water supply into the heat storage device 7 to cool the main steam and thus form a steam-water mixture.

[0034] The spray device 8 includes: a spray head, a cooling water pipe 9 and a cooling water valve 10; One end of the desuperheating water pipe 9 is connected to the spray head, and the other end is connected to the water outlet of the first heater 12. The desuperheating water pipe 9 is used to transport the preliminarily heated water to the spray head; The spray head is arranged in the heat storage device 7, and is used to spray the preliminarily heated feed water into the heat storage device 7; The desuperheating water valve 10 is disposed on the desuperheating water pipe 9 and is used to control the flow state of the feed water after preliminary heating in the desuperheating water pipe 9 .

[0035] The spray head of the spray device 8 is arranged in the heat storage device 7 and at the upper part of the heat storage device 7. One end of the cooling water pipe 9 is connected to multiple spray heads, and the other end is connected to the water supply outlet of the first heater 12. The feed water preliminarily heated in the first heater 12 is transported to the multiple spray heads through the cooling pipe 9. The preliminarily heated feed water is sprayed from the spray head as cooling water to fully contact with the main steam entering the heat storage device 7 to cool the main steam. The sprayed preliminarily heated feed water is mixed with the main steam when cooling the main steam to form a steam-water mixture stored in the heat storage device 7. The regulating system further comprises: a first valve group 5, a second valve group 6 and a control valve group 15; The first valve group 5 is arranged between the hot air heating device 17 and the main steam pipe 2 , the second valve group 6 is arranged between the heat storage device 7 and the main steam pipe 2 , and the control valve group 15 is arranged between the second heater 13 and the heat storage device 7 .

[0036] The first valve group 5 , the second valve group 6 and the control valve group 15 all include a shut-off valve, a regulating valve and a pressure reducing valve.

[0037] In order to extract the main steam flowing through the main steam pipe 2, an extraction pipe 3 is arranged between the steam inlet of the heat storage device 7 and the main steam pipe 2, and the second valve group 6 is arranged on the extraction pipe 3, that is, a shut-off valve, a regulating valve and a pressure reducing valve are arranged on the extraction pipe 3, and the connection state between the heat storage device 7 and the main steam pipe 2 can be controlled by the shut-off valve. When the shut-off valve is opened, the main steam pipe 2 is connected to the heat storage device 7 through the extraction pipe 3, and the main steam enters the heat storage device 7. When the shut-off valve is closed, the main steam cannot enter the heat storage device 7 through the extraction pipe 3. The regulating valve in the second valve group 6 can adjust the flow rate of the main steam entering the heat storage device 7, and the pressure reducing valve in the second valve group 6 can adjust the pressure of the main steam entering the heat storage device 7.

[0038] In order to facilitate the pipeline layout, an auxiliary pipeline 22 is arranged between the steam extraction pipeline 3 and the air inlet of the hot air heating device 17. The air inlet of the hot air heating device 17 is connected to the main steam pipeline 2 through the steam extraction pipeline 3 and the auxiliary pipeline 22. The connection point between the auxiliary pipeline 22 and the steam extraction pipeline 3 is located between the main steam pipeline 2 and the second valve group 6. The first valve group 5 is arranged on the auxiliary pipeline 22, that is, a shut-off valve, a regulating valve and a pressure reducing valve are arranged on the auxiliary pipeline 22. The shut-off valve can control the connection state between the hot air heating device 17 and the main steam pipeline 2. When the shut-off valve is opened, the main steam pipe 2 is connected to the hot air heating device 17 through the steam extraction pipe 3 and the auxiliary pipe 22, and the main steam enters the hot air heating device 17 through the steam extraction pipe 3 and the auxiliary pipe 22. When the shut-off valve is closed, the main steam pipe 2 is disconnected from the hot air heating device 7, and the main steam cannot enter the hot air heating device 17 through the steam extraction pipe 3 and the auxiliary pipe 22. The regulating valve of the first valve group 5 can adjust the flow rate of the main steam entering the hot air heating device 17, and the pressure reducing valve of the first valve group 5 can adjust the pressure of the main steam entering the hot air heating device 17.

[0039] When the coal-fired generator set is reducing its load, and the current coal-fired generator set is at the first load, the coal-fired generator set is running at a rated load greater than 40% of the coal-fired generator set. If a load reduction instruction is received, the cooling water valve 10 and the second valve group 6 are opened, and the first valve group 5 and the control valve group 15 on the energy release pipeline 14 are closed. The main steam flowing through the main steam pipeline 2 enters the heat storage device 7 through the steam extraction pipeline 3. At the same time, the feed water preliminarily heated by the first heater 12 is sprayed into the heat storage device 7 from the sprinkler head through the cooling water pipe 9. The sprayed preliminarily heated feed water cools the main steam, and maintains the temperature in the heat storage device 7 as the main steam. Corresponding to the saturation temperature, the main steam entering the heat storage device 7 continuously condenses into water, and the pressure in the heat storage device 7 forms a pressure difference with the steam extraction pipe 3, which can play a role in steam extraction. Therefore, the main steam flowing through the main steam pipe 2 can enter the heat storage device 7 through the steam extraction pipe 3 without the need for a steam extraction device. The main steam continuously enters the heat storage device 7 until the pressure in the heat storage device 7 is the same as the steam pressure in the boiler of the coal-fired power generation unit, and the steam-water mixture stored in the heat storage device 7 reaches the maximum storage capacity. At this time, the steam-water mixture has been stored in the heat storage device 7, and the cooling water valve 10 and the second valve group 6 are closed.

[0040] When the coal-fired generating set is reducing its load, and the current coal-fired generating set is at the second load, that is, the coal-fired generating set is running at a rated load less than or equal to 40% of the coal-fired generating set, if a load reduction instruction is received, the first valve group 5 is opened, the second valve group 6, the temperature reducing water valve 10 and the control valve group 15 are closed, and the main steam flowing through the main steam pipeline 2 enters the hot air heating device 17 after passing through the extraction pipeline 3 and the auxiliary pipeline 22. The hot air heating device 17 is connected to the air preheater 19 through the hot air pipeline 18, and the air cooler 20 supplies air to the air preheater 19. The air preheater 19 heats the supplied air to become hot air, and the hot air is discharged from the air outlet of the air preheater 19. The hot air enters the hot air heating device 17 through the hot air duct 18, and the hot air exchanges heat with the main steam in the hot air heating device 17. The hot air is heated by the main steam. After the main steam heats the hot air, the temperature is reduced to become the first steam. The first steam is discharged from the air outlet of the hot air heating device 17. A second connecting pipe is arranged between the exhaust port of the hot air heating device 17 and the energy release pipe 14. After the first steam is discharged from the air outlet of the hot air heating device 17, it enters the energy release pipe 14 through the second connecting pipe. The first steam is mixed with the steam-water mixture flowing through the energy release pipe 14 and then enters the second heater 13 together to heat the feed water after the preliminary heating again. When the coal-fired generator set increases its load, and the current coal-fired generator set is at the second load, that is, the coal-fired generator set is running at a load less than or equal to 40% of the rated load of the coal-fired generator set, if a load increase instruction is received, the opening of the regulating valve in the first valve group 5 is controlled to be gradually reduced, so that the steam volume of the main steam extracted from the main steam pipeline 2 is gradually reduced, and the steam volume of the main steam entering the high-pressure cylinder 1 of the steam turbine through the main steam pipeline 2 is gradually increased, so that the output of the steam turbine increases rapidly, and the load of the coal-fired generator set is increased. The opening of the regulating valve in the first valve group 5 is controlled to be gradually reduced, and the control valve group 1 is opened. 5. The steam-water mixture stored in the heat storage device 7 enters the second heater 13. The second heater 13 uses the steam-water mixture to heat the preliminarily heated feed water. As the steam-water mixture in the heat storage device 7 is gradually discharged, the pressure in the heat storage device 7 decreases rapidly, but its heat is not completely released. At this time, the cooling water valve 10 is opened, so that the feed water preliminarily heated by the first heater 12 enters the heat storage device 7 through the cooling water pipe 9. The preliminarily heated feed water is fully mixed with the remaining steam-water mixture in the heat storage device 7 and enters the second heater 13 through the energy release pipe 14, so that the heat in the heat storage device 7 is completely released.

[0041] When the coal-fired generator set increases its load, and the current coal-fired generator set is at the first load, that is, the coal-fired generator set is running at a load greater than 40% of the rated load of the coal-fired generator set, if a load increase instruction is received, the control valve group 15 is opened, and the steam-water mixture in the heat storage device 7 enters the second heater 13 to heat the preliminarily heated feed water. As the steam-water mixture in the heat storage device 7 is gradually discharged, the pressure in the heat storage device 7 decreases rapidly, but its heat is not completely released. At this time, the desuperheating water valve 10 is opened, so that the feed water preliminarily heated by the first heater 12 enters the heat storage device 7 through the desuperheating water pipe 9, and the preliminarily heated feed water is fully mixed with the remaining steam-water mixture in the heat storage device 7 and enters the second heater 13 through the energy release pipe 14, so that the heat in the heat storage device 7 is completely released.

[0042] Air is supplied to the air preheater 19 by the air cooler 20. The air preheater 19 heats the air to become hot air and enters the hot air heating device 17. The hot air is heated again by the main steam, and the reheated hot air is finally sent to the boiler. The hot air heating device 17 is arranged on the hot primary air duct or the hot secondary air duct in the coal-fired power generation unit according to actual needs, and the hot air duct 18 can be a hot primary air duct or a hot secondary air duct. If the coal type entering the coal-fired power generation unit requires the hot primary air temperature of the coal mill to be further increased, the hot air heating device 17 can be arranged on the hot primary air duct to further increase the hot primary air temperature; if the coal type entering the coal-fired power generation unit requires the hot primary air temperature of the coal mill to meet the requirements, the hot air heating device 17 can be arranged on the hot secondary air duct to further increase the hot secondary air temperature.

[0043] In one embodiment, a rapid load change regulation system of a coal-fired power generation unit is applied to a coal-fired power generation unit. The boiler of the coal-fired power generation unit is a subcritical single intermediate reheat controlled cycle drum boiler, model SG-2028 / 17.5-M907, which adopts swing burner temperature control, four-corner arrangement, tangential combustion, positive pressure direct blowing pulverizing system, single furnace, π-type open-air arrangement, solid slag discharge, all-steel frame structure, and balanced ventilation. Table 1 is the main design parameters of the boiler.

[0044] Table 1 Main design parameters of boiler

[0045] Currently, coal-fired power generation units have problems such as poor load change rate, weak low-load stable combustion ability, and insufficient low-load SCR inlet smoke temperature. The rapid load change regulation system of the coal-fired power generation unit described in the present invention is connected to the coal-fired power generation unit to optimize and transform the coal-fired power generation unit, thereby meeting the requirements of wide load efficiency improvement, low-load stable combustion, low-load SCR inlet smoke temperature increase and rapid load change.

[0046] The present invention utilizes the heat storage device 7, the hot air heating device 17 and the second heater 13 to improve the heat storage capacity of the coal-fired power generation set, and meet the requirements of rapid load increase and decrease of the coal-fired power generation set. When the load is increased, the second heater 13 uses the steam-water mixture stored in the heat storage device 7 to heat the feed water temperature, which reduces the heat absorption of the economizer, thereby increasing the SCR (i.e., Selective Catalytic Reduction) inlet flue gas temperature, which can meet the flue gas temperature requirements of the SCR system when the coal-fired power generation set is put into operation at 20% load; the hot air heating device 17 is arranged on the hot secondary air duct, and uses the main steam extracted from the main steam pipeline 2 to heat the hot secondary air entering the hot air heating device 17. After the hot secondary air temperature is increased, the stable combustion ability and burnout performance of the coal-fired power generation set are significantly enhanced.

[0047] The thermal calculations were carried out and the results were as follows: Table 2 shows the 20% load boundary conditions: (1) 20% load boundary condition Table 2 20% load boundary conditions

[0048] (2) Calculation of heat storage device capacity When the coal-fired power generation unit needs to reduce the load quickly when operating at a load of more than 40%, it is necessary to extract part of the main steam in the main steam pipeline 2 and store it in the heat storage device 7. Considering the temperature matching between the heat storage device 7 and the original boiler system, the pressure and temperature in the heat storage device 7 are set to 17MPa and 350℃ (enthalpy value 1666kJ / kg, specific volume 0.001727m 3 / kg).

[0049] The instantaneous gap value between the energy that the boiler of a coal-fired power generation unit can supply and the target energy at a certain moment during the load change process satisfies the following formula: (1) In the formula, Indicates the energy supplied by the heat storage device, GJ / min; It represents the working fluid energy at the target variable load rate, GJ / min; Indicates the working fluid energy under the existing variable load rate, GJ / min; Indicates the load change time, min.

[0050] The total energy difference between the energy that the boiler can supply and the target energy within a certain period of time is the integral of the instantaneous energy difference mentioned above and satisfies the following formula: (2) Based on this, the energy gap is calculated and finally the volume of the hot water tank in this embodiment is determined to be 60m 3 The maximum storage mass of the working fluid in the design heat storage device is 34.7t.

[0051] (3) Steady-state thermal calculation of 20% load extraction steam heating The coal-fired power generation unit draws 72t / h of main steam from the main steam pipe 2 to enter the hot air heating device 17 and the second heater 13 at 20% load. The relevant calculation results are as follows: Table 3 is the thermal calculation table of the hot air heating device, Table 4 is the thermal calculation table of the second heater, and Table 5 is the calculation table of the economizer working condition: Table 3 Thermal calculation table of hot air heating device

[0052] Table 4 Thermal calculation table of the second heater

[0053] Table 5 Economizer operating condition calculation table

[0054] According to Table 3 to Table 5, the secondary air temperature of air preheater 19 increased from 281℃ to 328℃, an increase of 47℃; the boiler feed water temperature increased from 190℃ to 237.81℃, an increase of 47.81℃, and the feed water temperature was greatly improved; the economizer outlet flue gas temperature increased from 285℃ to 309℃, an increase of 24℃, meeting the requirements of 20% THA input into the SCR denitrification system (the inlet flue gas temperature of the SCR denitrification system must be ≥300℃).

[0055] (5) Calculation of load increase characteristics at 20% load When the coal-fired generator set is under 20% load, the valve core opening of the regulating valve of the first valve group 5 gradually decreases, and the steam extraction amount of the steam extraction pipeline 3 decreases. The load change of the coal-fired generator set is as follows: Figure 2 As shown, Figure 2 The load change of the coal-fired power generation unit is obtained by purely relying on the action of the first valve group 5 without increasing the coal and water supply of the coal-fired power generation unit itself. Figure 2 It can be seen that through the adjustment of this regulation system, the variable load capacity of the coal-fired power generation unit can be greatly enhanced.

[0056] like Figure 2 As shown, the first valve group 5 is gradually closed. At this time, the main steam flow entering the high-pressure cylinder 1 of the steam turbine increases, and a total of 3600MJ of heat can be output. After the first valve group 5 is activated, the load of the unit changes within 4 seconds. In this embodiment, the unit load can reach a maximum of 124.3MW within 200 seconds, increasing the average load change rate by 0.25%Pe / min.

[0057] (6) Calculation of variable load rate of heat storage device In this embodiment, the volume of the heat storage device 7 is 60m 3 , the mass of the working fluid under the design working condition is 34.7t, the heat storage device 7 is a heat storage tank, the working fluid pressure and temperature in the heat storage tank are 17MPa, 350℃, and the enthalpy value is 1666kJ / kg. The working fluid stored in the heat storage tank has a heat of 57810MJ. After the second valve group 6 is actuated, the load of the coal-fired power generation unit changes within 10 seconds. In this embodiment, the heat storage device 7 can increase the unit load change rate by 1.4%Pe / min within 200 seconds.

[0058] After using the coal-fired power generation unit and the rapid load change regulation system provided by the present application, the load change rate can be increased by 1.65%Pe / min. By increasing the variation range of the valve core opening of the regulating valve and the pressure reducing valve of the first valve group 5 and the second valve group 6, the load change rate can be further improved.

[0059] It can be seen from this that, combined with the variable load capacity of the coal-fired power generation unit itself, the load increase rate of the coal-fired power generation unit under 20% THA load can be increased to above 2.5% Pe / min. At the same time, it will not cause a significant impact on the safety and stability of the coal-fired power generation unit.

[0060] (7) Impact on hydrodynamic safety In this embodiment, 72t / h of steam is extracted to form a self-circulation in the boiler, which is equivalent to an increase of about 18% in the working fluid flow rate flowing through the boiler water-cooled wall, economizer, and superheater. Although the electrical load output is still 120MW (20%THA), the actual boiler water flow rate is equivalent to a load of 144MW (24%THA). It should be noted that the boiler of the coal-fired power generation unit in this embodiment is a subcritical drum boiler, and its low-load hydrodynamic stability generally does not have safety issues.

[0061] In another embodiment, in another coal-fired power generation unit to which the present invention is applied, the boiler of the other coal-fired power generation unit is a supercritical direct current boiler, and the working fluid flow rate through the boiler water-cooled wall, economizer, and superheater is significantly improved, which can greatly reduce the dry-wet state conversion point of the unit and improve the deep load hydrodynamic safety performance.

[0062] Another aspect of the present invention provides a method for regulating rapid load change of a coal-fired power generation unit, which is implemented based on the rapid load change regulation system of the coal-fired power generation unit described above. The method for regulating rapid load change of a coal-fired power generation unit comprises: Continuously obtain the current load of coal-fired generating units; If a load reduction instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the first load, main steam flowing through the main steam pipeline of the coal-fired power generation unit is extracted, and the main steam is cooled to form a steam-water mixture for storage; If a load reduction instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the second load, main steam flowing through the main steam pipeline of the coal-fired power generation unit is extracted, and the main steam is used to heat the hot air sent out from the air outlet of the air preheater of the coal-fired power generation unit, and the main steam loses heat and becomes the first steam, and the first steam is also used to heat the feed water sent to the economizer; If a load increase instruction is received from a coal-fired power generation unit, and the current load of the coal-fired power generation unit is the second load, the amount of main steam extracted from the main steam pipeline of the coal-fired power generation unit is gradually reduced, and at the same time, the stored steam-water mixture is used to heat the feed water sent to the economizer of the coal-fired power generation unit, and the steam-water mixture loses heat and becomes water-repellent; If a load increase instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the first load, the stored steam-water mixture is used to heat the feed water sent to the economizer of the coal-fired power generation unit.

[0063] The regulating method further comprises: utilizing the hot working medium to preliminarily heat the feed water sent to the economizer of the coal-fired power generation unit.

[0064] The primary heated feed water is used to cool the main steam to form a steam-water mixture.

[0065] The regulating method further comprises: using the preliminarily heated feed water to cool down the main steam to form a steam-water mixture.

[0066] The first load is greater than 40% of the rated load of the coal-fired power generation unit, and the second load is less than or equal to 40% of the rated load of the coal-fired power generation unit.

[0067] The present invention provides a rapid load-changing regulation system for a coal-fired generator set, in which a heat storage device is connected to a main steam pipeline of the coal-fired generator set, and the amount of steam flowing through the main steam pipeline is extracted to regulate the amount of steam entering the high-pressure cylinder of the turbine of the coal-fired generator set through the main steam pipeline, thereby regulating the load of the coal-fired generator set. When the load is reduced, the main steam flowing through the main steam pipeline is extracted to the heat storage device, the main steam entering the heat storage device is cooled so that the main steam becomes a steam-water mixture and the steam-water mixture is stored, or when the load is reduced, the main steam flowing through the main steam pipeline is extracted to heat the hot air sent from the air preheater, further increasing the temperature of the hot air finally sent to the boiler of the coal-fired generator set. In this way, when the coal-fired generator set needs to reduce the load, the main steam flowing through the main steam pipeline is extracted, the steam intake of the steam turbine of the coal-fired generator set is reduced, so that the load of the coal-fired generator set is reduced, and the main steam is directly extracted from the main steam pipeline, which increases the load reduction rate of the coal-fired generator set; when the load is increased, the main steam extraction volume of the main steam pipeline for heating the hot air is reduced, and the steam volume of the main steam entering the high-pressure cylinder is increased, or when the load is increased, the steam-water mixture stored in the heat storage device is used to heat the feed water sent to the economizer of the coal-fired generator set again, which increases the heat of the feed water sent to the boiler of the coal-fired generator set and improves the load increase rate of the coal-fired generator set. The system and method for regulating the rapid load change of a coal-fired power generation unit provided by the present invention improve the heat storage capacity of the coal-fired power generation unit itself and the heat storage capacity of the heat storage device, thereby improving the load regulation rate of the unit and solving the problem of insufficient load regulation rate of the coal-fired power generation unit in the prior art.

[0068] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0069] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0070] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A rapid load-changing regulation system for a coal-fired power generation unit, connected to an economizer (21), a deaerator, an air preheater (19) and a main steam pipeline (2) of the coal-fired power generation unit, characterized in that: The regulating system comprises: A heat storage device (7) connected to the main steam pipeline (2) and used for extracting and cooling the main steam flowing through the main steam pipeline (2) to form a steam-water mixture in the heat storage device (7); A feed water heating device, used to heat the feed water sent to the economizer (21) using the steam-water mixture in the heat storage device (7); after the steam-water mixture heats the feed water, it loses heat and becomes hydrophobic water, which finally enters the deaerator; The hot air heating device (17) is connected to the main steam pipeline (2), the air outlet of the air preheater (19) and the inlet end of the feed water heating device, and is used to use the main steam to heat the hot air sent out from the air outlet of the air preheater (19). After the main steam heats the hot air, it loses heat and becomes the first steam that enters the feed water heating device, wherein the feed water heating device can also use the first steam to heat the feed water sent to the economizer (21).

2. The rapid load-changing regulation system for coal-fired power generation units according to claim 1 is characterized in that: The feedwater heating device comprises: a first heater (12) and a second heater (13); The first heater (12) is used to use a hot working medium to preliminarily heat the feed water fed into the economizer (21), and the hot working medium loses heat and becomes drain water that is fed into the deaerator; The second heater (13) is connected to the steam outlet of the heat storage device (7) and is used to heat the initially heated feed water using the steam-water mixture. After the steam-water mixture loses heat, it becomes steam and enters the first heater (12).

3. The rapid load-changing regulation system for coal-fired power generation units according to claim 2 is characterized in that: The regulating system further comprises: a spraying device (8), which is arranged in the heat storage device (7) and connected to the feed water outlet of the first heater (12), and is used for spraying the preliminarily heated feed water into the heat storage device (7) to cool the main steam and thereby form a steam-water mixture.

4. The rapid load-changing regulation system for coal-fired power generation units according to claim 3 is characterized in that: The spray device (8) comprises: a spray head, a cooling water pipe (9) and a cooling water valve (10); One end of the cooling water pipe (9) is connected to the spray head, and the other end is connected to the water supply outlet of the first heater (12). The cooling water pipe (9) is used to transport the initially heated water to the spray head. The spray head is arranged in the heat storage device (7) and is used to spray the preliminarily heated feed water into the heat storage device (7); The desuperheating water valve (10) is arranged on the desuperheating water pipe (9) and is used to control the flow state of the initially heated feed water in the desuperheating water pipe (9).

5. The rapid load-changing regulation system for coal-fired power generation units according to claim 2, characterized in that: The regulating system further comprises: a first valve group (5), a second valve group (6) and a control valve group (15); The first valve group (5) is arranged between the hot air heating device (17) and the main steam pipeline (2), the second valve group (6) is arranged between the heat storage device (7) and the main steam pipeline (2), and the control valve group (15) is arranged between the second heater (13) and the heat storage device (7).

6. The rapid load-changing regulation system for coal-fired power generation units according to claim 5, characterized in that: The first valve group (5), the second valve group (6) and the control valve group (15) each comprise a shut-off valve, a regulating valve and a pressure reducing valve.

7. A method for regulating rapid load change of a coal-fired power generation unit, implemented based on the rapid load change regulation system of a coal-fired power generation unit according to any one of claims 1 to 6, characterized in that: The method for adjusting the rapid load change of the coal-fired power generation unit comprises: Continuously obtain the current load of coal-fired generating units; If a load reduction instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the first load, main steam flowing through the main steam pipeline of the coal-fired power generation unit is extracted, and the main steam is cooled to form a steam-water mixture for storage; If a load reduction instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the second load, main steam flowing through the main steam pipeline of the coal-fired power generation unit is extracted, and the main steam is used to heat the hot air sent out from the air outlet of the air preheater of the coal-fired power generation unit, and the main steam loses heat and becomes the first steam, and the first steam is also used to heat the feed water sent to the economizer; If a load increase instruction is received from a coal-fired power generation unit, and the current load of the coal-fired power generation unit is the second load, the amount of main steam extracted from the main steam pipeline of the coal-fired power generation unit is gradually reduced, and at the same time, the stored steam-water mixture is used to heat the feed water sent to the economizer of the coal-fired power generation unit, and the steam-water mixture loses heat and becomes water-repellent; If a load increase instruction of the coal-fired power generation unit is received and the current load of the coal-fired power generation unit is the first load, the stored steam-water mixture is used to heat the feed water sent to the economizer of the coal-fired power generation unit.

8. The method for adjusting the rapid load change of a coal-fired power generation unit according to claim 7, characterized in that: The regulating method further comprises: utilizing the hot working medium to preliminarily heat the feed water sent to the economizer of the coal-fired power generation unit.

9. The method for adjusting the rapid load change of a coal-fired power generation unit according to claim 8, characterized in that: The primary heated feed water is used to cool the main steam to form a steam-water mixture.

10. The method for adjusting the rapid load change of a coal-fired power generation unit according to claim 7, characterized in that: The first load is greater than 40% of the rated load of the coal-fired power generation unit, and the second load is less than or equal to 40% of the rated load of the coal-fired power generation unit.

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