Wide-load heat supply system of coal-fired power generating unit

Abstract

The utility model provides a wide-load heat supply system of a coal-fired power generation unit, and belongs to the field of heat supply of coal-fired power A wide-load heat supply system of a coal-fired power generation unit comprises a main steam heat supply pipeline, a heat reheat supply pipeline and a heat supply mother pipe. The output end of the main steam heat supply pipeline is connected with the input end of the heat supply main pipe, and the main steam heat supply pipeline is used for conveying main steam to the heat supply main pipe when the coal-fired power generation unit is in a low-load operation state. The input end of the heat reheat supply pipeline is connected with a reheater of the coal-fired power generation unit, the output end of the heat reheat supply pipeline is connected with the input end of the heat supply mother pipe, and the heat reheat supply pipeline is used for conveying reheat steam to the heat supply mother pipe when the coal-fired power generation unit is in a high-load operation state or a conventional-load operation state; the output end of the heat supply mother pipe is used for supplying heat to heat consumers through main steam in the low-load operation state of the coal-fired power generation unit and supplying heat to the heat consumers through reheat steam in the normal-load operation state and the high-load operation state.

Description

Technical Field

[0001] The utility model relates to the field of coal-fired unit heating, in particular to a wide-load heating system for a coal-fired generator unit. Background Art

[0002] At present, the "three reforms and linkage" of coal-fired power units is being steadily promoted as an important measure to promote energy structure transformation and environmental protection. However, it faces the following technical difficulties in its specific implementation:

[0003] Under normal load, thermal power units generally use cold and hot reheating for heating. The use of cold reheating is limited by the over-temperature problem of the reheater wall temperature, and its heating amount generally cannot exceed 5% of the unit's reheat steam flow rate. However, the use of hot reheating requires cooling and pressure reduction, resulting in the problem of suboptimal heating economy. Under low load, reheat steam often cannot meet the heating parameter requirements. Utility Model Content

[0004] In order to solve one of the above technical defects, the utility model provides a wide-load heating system for coal-fired generator sets, wherein the wide-load heating system for coal-fired generator sets is provided with a heating main pipe, and the steam in the heating main pipe is used to supply heat to heat users, and when the coal-fired generator set is in a low-load operation state, the main steam of the coal-fired generator set is extracted, and the main steam is provided to heat users through the heating main pipe for heating. When the coal-fired generator set is in a normal load operation state and a high load operation state, the reheated steam of the coal-fired generator set is extracted, and the reheated steam is provided to heat users through the heating main pipe for heating, thereby realizing full-load heating of the coal-fired generator set and improving the flexibility of heating of the coal-fired generator set.

[0005] The first aspect of the utility model provides a wide load heating system for a coal-fired power generation unit, comprising: a main steam heating pipeline, a hot reheating pipeline and a heating main pipe;

[0006] The input end of the main steam heating pipeline is connected to the high-temperature superheater and the low-temperature superheater through a first three-way valve, and the output end of the main steam heating pipeline is connected to the input end of the heating main pipe, so as to transport the main steam from the high-temperature superheater or the low-temperature superheater to the heating main pipe when the coal-fired power generation unit is in a low-load operation state;

[0007] The input end of the hot reheating pipeline is connected to the reheater of the coal-fired power generation unit, and the output end of the hot reheating pipeline is connected to the input end of the heating main pipe, so as to transport the reheated steam from the reheater to the heating main pipe when the coal-fired power generation unit is in a high-load operation state or a normal-load operation state;

[0008] The output end of the heat supply main pipe is used to supply heat to heat users through main steam in the low-load operation state of a coal-fired power generation unit, and to supply heat to heat users through reheated steam in the normal-load operation state and the high-load operation state.

[0009] In the embodiment of the present invention, the system further includes a hot air heater, which has a first input end, a first output end, a second input end, and a second output end. The hot air heater inputs hot air through the second input end;

[0010] The heat supply main pipe has a heat exchange input end and a heat exchange output end. The heat supply main pipe conveys main steam or reheated steam to the first input end of the hot air heater through the heat exchange output end;

[0011] The main steam or reheated steam exchanges heat with the hot air in the hot air heater to obtain the cooled main steam or the cooled reheated steam, and to obtain the heated hot air;

[0012] The cooled main steam or the cooled reheated steam returns to the heat supply main pipe through the heat exchange input end;

[0013] The heated hot air flows to the boiler furnace of the coal-fired power generation unit through the second output end of the hot air heater.

[0014] In the embodiment of the present invention, the system further includes a first high-pressure heater, which has a first input end, a second input end, a first output end, and a second output end; the second input end of the first high-pressure heater is used to input feed water;

[0015] The heat supply main pipe also has a first output end and a second output end. The second output end is connected to the first input end of the first high-pressure heater;

[0016] The cooled main steam from the heat supply main pipe is divided into two paths. One path of the cooled main steam supplies heat to heat users through the first output end of the heat supply main pipe; the other path of the cooled main steam flows to the first high-pressure heater through the second output end of the heat supply main pipe;

[0017] The other path of the cooled main steam flowing to the first high-pressure heater is used to heat the feed water. The heat supply main pipe also has a first output end and a second output end. The second output end is connected to the first input end of the first high-pressure heater.

[0018] In the embodiment of the present invention, the system further includes a second high-pressure heater, which has a first input end, a second input end, a first output end, and a second output end. The second output end of the second high-pressure heater is connected to the second input end of the first high-pressure heater;

[0019] The first input end of the second high-pressure heater receives extraction steam from the steam turbine. The second input end of the second high-pressure heater is used to input feed water. The second high-pressure heater uses the extraction steam of the steam turbine to heat the feed water to obtain the once-heated feed water. The second high-pressure heater conveys the once-heated feed water to the first high-pressure heater through the second output end;

[0020] The shown first high-pressure heater uses the other path of the cooled main steam to heat the once-heated feed water.

[0021] In the embodiment of the present invention, a desuperheating water pipeline is further provided on the heat supply main pipe. The desuperheating water pipeline is used to spray desuperheating water on the heat supply main pipe to cool the main steam or reheated steam entering the hot air heater.

[0022] In the embodiment of the present invention, a cold reheat heat supply pipeline is further included. The cold reheat heat supply pipeline is used to provide cold reheat steam to heat users to achieve heat supply to heat users.

[0023] In the embodiment of the present invention, the cold reheat heat supply pipeline is connected to the inlet end of the reheater;

[0024] The cold reheat heat supply pipeline is used to provide cold reheat steam to the reheater. The reheater is used to heat the cold reheat steam into reheated steam and then output it to the hot reheat heat supply pipeline.

[0025] In the embodiment of the present invention, the system further includes a second three-way valve. The second three-way valve is arranged on the reheated steam pipeline of the coal-fired power generation unit. The first end of the second three-way valve is connected to the reheater. The second end of the second three-way valve is connected to the hot reheat heat supply pipeline. The third end of the second three-way valve is connected to the intermediate pressure cylinder of the coal-fired power generation unit.

[0026] In the embodiment of the present invention, the system further includes a first valve group and a second valve group;

[0027] The first valve group is arranged on the main steam heat supply pipeline and is used to adjust the flow rate of the main steam flowing to the main steam on the heat supply main pipe;

[0028] The second valve group is arranged on the hot reheat heat supply pipeline and is used to adjust the flow rate of the reheated steam flowing to the heat supply main pipe in the hot reheat heat supply pipeline.

[0029] In the embodiment of the present invention, a third valve group is further included. The third valve group is arranged in the desuperheating water pipeline and is used to adjust the flow rate of the desuperheating water.

[0030] The wide-load heating system of the coal-fired power generation unit supplies heat to heat users through a heating main pipe. The steam in the heating main pipe is used for heating. When the coal-fired power generation unit is operating at a low load, the main steam of the coal-fired power generation unit is extracted and supplied to heat users through the heating main pipe for heating. When the coal-fired power generation unit is operating at a normal load and a high load, the reheated steam of the coal-fired power generation unit is extracted and supplied to heat users through the heating main pipe for heating, realizing full-load heating of the coal-fired unit and improving the flexibility of heat supply of the coal-fired unit.

[0031] Other features and advantages of the technical solution of the present utility model will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0032] The drawings described herein are used to provide a further understanding of the present utility model and constitute a part of the present utility model. The schematic embodiments of the present utility model and their descriptions are used to explain the present utility model and do not constitute an improper limitation of the present utility model. In the drawings:

[0033] Figure 1 is a schematic structural diagram of the wide-load heating system of the coal-fired power generation unit provided by the embodiment of the present utility model.

[0034] Description of the Reference Numerals in the Drawings

[0035] 1 - Main steam heating pipeline, 2 - Hot reheat heating pipeline, 3 - Heating main pipe, 4 - Hot air heater, 5 - High-pressure heater, 6 - Desuperheating water pipeline, 7 - Air preheater, 8 - Cold reheat heating pipeline, 9 - First valve group, 10 - Second valve group, 11 - Third valve group, 12 - Fourth valve group, 13 - Fifth valve group, 14 - Sixth valve group, 15 - Main steam pipeline, 16 - Reheated steam pipeline, 17 - Fan, 18 - Hot air duct, 19 - Economizer, 20 - Feed water pipeline, 21 - Reheater, 22 - High-temperature superheater, 23 - Low-temperature superheater, 24 - First three-way valve, 25 - Second three-way valve, 26 - Heat exchange output end, 27 - Heat exchange input end. Detailed Description of the Preferred Embodiments

[0036] In order to make the technical solutions and advantages in the embodiments of the present utility model clearer and more understandable, the following further describes the exemplary embodiments of the present utility model in detail with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other.

[0037] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model.

[0038] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0039] In the present utility model, unless otherwise clearly specified and defined, terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection or communication with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0040] In the process of implementing the present utility model, the inventor found that currently, the "three-in-one linkage" of coal-fired power units, as an important measure to promote the transformation of the energy structure and environmental protection, is being steadily promoted. However, it faces the following technical problems in specific implementation:

[0041] Under normal load, thermal power units generally use cold and hot reheat for heating. Using cold reheat for heating is limited by the problem of overheating of the wall temperature of the reheater 21, and its heating capacity generally cannot exceed 5% of the reheater steam flow of the unit. While using hot reheat for heating, there is a problem that desuperheating and pressure reduction are required, resulting in sub-optimal heating economy; under low load, the reheated steam often fails to meet the heating parameter requirements.

[0042] In view of the above problems, the utility model provides a wide load heating system for a coal-fired power generation unit in an embodiment, comprising: a main steam heating pipeline 1, a hot reheating pipeline 2 and a heating main pipe 3. The input end of the main steam heating pipeline 1 is connected to a high temperature superheater 22 and a low temperature superheater 23 through a first three-way valve 24, and the output end of the main steam heating pipeline 1 is connected to the input end of the heating main pipe 3, so as to transport the main steam from the high temperature superheater 22 or the low temperature superheater 23 to the heating main pipe 3 when the coal-fired power generation unit is in a low load operation state;

[0043] The input end of the hot reheating pipeline 2 is connected to the reheater 21 of the coal-fired power generation unit, and the output end of the hot reheating pipeline 2 is connected to the input end of the heating main pipe 3, so as to transport the reheated steam from the reheater 21 to the heating main pipe 3 when the coal-fired power generation unit is in a high-load operation state or a normal-load operation state;

[0044] The output end of the heating mother pipe 3 is used to supply heat to heat users through main steam when the coal-fired generator set is in low-load operation state, and to supply heat to heat users through reheat steam when the coal-fired generator set is in normal load operation state and high load operation state. When the coal-fired generator set is in normal load operation state and high load operation state, the reheat steam of the coal-fired generator set is extracted, and the reheat steam is provided to the heat users through the heating mother pipe 3 for heating, so as to realize full-load heating of the coal-fired generator set and improve the flexibility of heating of the coal-fired generator set.

[0045] Figure 1 Schematic diagram of the structure of the wide load heating system of the coal-fired generator set provided by the embodiment of the utility model. Figure 1 As shown, a wide-load heating system for a coal-fired power generation unit provided in this embodiment includes: a main steam heating pipeline 1, a hot reheating pipeline 2 and a heating main pipe 3;

[0046] The input end of the main steam heating pipeline 1 is connected to the high-temperature superheater 22 and the low-temperature superheater 23 through the first three-way valve 24, and the output end of the main steam heating pipeline 1 is connected to the input end of the heating main pipe 3, so as to transport the main steam from the high-temperature superheater 22 or the low-temperature superheater 23 to the heating main pipe 3 when the coal-fired power generation unit is in a low-load operation state;

[0047] The input end of the hot reheating pipeline 2 is connected to the reheater 21 of the coal-fired power generation unit, and the output end of the hot reheating pipeline 2 is connected to the input end of the heating main pipe 3, so as to transport the reheated steam from the reheater 21 to the heating main pipe 3 when the coal-fired power generation unit is in a high-load operation state or a normal-load operation state;

[0048] The output end of the heat supply main pipe 3 is used to supply heat to heat users through main steam in the low-load operation state of the coal-fired power generation unit, and to supply heat to heat users through reheat steam in the normal-load operation state and the high-load operation state.

[0049] Specifically, under the action of the first three-way valve 24, the input end of the main steam heating pipe 1 can flexibly select the source of the required main steam. It can select the main steam from the high-temperature superheater 22 or the main steam from the low-temperature superheater 23.

[0050] Furthermore, when the coal-fired power generation unit is in the low-load operation state, according to the heat supply parameters required by heat users, the first three-way valve 24 can be used to select the main steam from the high-temperature superheater 22 or the low-temperature superheater 23, improving the flexibility of heat supply of the coal-fired power generation unit.

[0051] The wide-load heat supply system of the coal-fired power generation unit supplies heat to heat users through the steam in the heat supply main pipe 3. When the coal-fired power generation unit is in the low-load operation state, the main steam of the coal-fired power generation unit is extracted and supplied to heat users through the heat supply main pipe 3 to supply heat. When the coal-fired power generation unit is in the normal-load operation state and the high-load operation state, the reheat steam of the coal-fired power generation unit is extracted and supplied to heat users through the heat supply main pipe 3 to supply heat, realizing full-load heat supply of the coal-fired unit and improving the flexibility of heat supply of the coal-fired unit.

[0052] In this embodiment, the system further includes a hot air heater 4. The hot air heater 4 has a first input end, a first output end, a second input end, and a second output end. The hot air heater 4 inputs hot air through the second input end;

[0053] The heat supply main pipe 3 has a heat exchange input end and a heat exchange output end. The heat supply main pipe 3 transports main steam or reheat steam to the first input end of the hot air heater 4 through the heat exchange output end 26;

[0054] The main steam or reheat steam exchanges heat with the hot air in the hot air heater 4 to obtain the cooled main steam or the cooled reheat steam, and to obtain the heated hot air;

[0055] The cooled main steam or the cooled reheat steam returns to the heat supply main pipe 3 through the heat exchange input end 27;

[0056] The heated hot air flows to the boiler furnace of the coal-fired power generation unit through the second output end of the hot air heater 4.

[0057] The hot air heater 4 is used to recover the flow rate of the main steam or the reheated steam. Specifically, the hot air heater 4 is disposed on the outlet hot air duct 18 of the air preheater 7 and is used to receive the main steam or the reheated steam from the heat supply main pipe 3. The hot air from the second input end of the hot air heater 4 is heated by the heat of the main steam or the reheated steam in the heat supply main pipe 3, and the hot air is heated by the heat of the main steam or the reheated steam in the heat supply main pipe 3 to obtain the heated hot air with further increased heat.

[0058] The heated hot air is used to increase the inlet air temperature of the coal mill. Specifically: The hot air comes from the outlet of the boiler air preheater 7, is sent into the air preheater 7 by the fan 17 for heating, and then goes to the hot air heater 4 for further heating, and finally is sent to the boiler. If the hot primary air temperature of the coal mill needs to be further increased for the coal type fed into the coal-fired generating unit, the hot air heater 4 can be arranged on the hot primary air duct to further increase the hot primary air temperature; if the hot primary air temperature of the coal mill meets the requirements for the coal type fed into the coal-fired generating unit, the hot air heater 4 can be arranged on the hot secondary air duct to further increase the hot secondary air temperature.

[0059] The heat of the reheated steam and the main steam is recovered by the hot air heater 4 to further match the heat supply demand of the heat user. The recovered heat enters the boiler, which can reduce the throttling loss of the coal-fired generating unit for heat supply and significantly improve the heat supply economy. Moreover, by using the hot air heater 4 to further increase the inlet primary / secondary air temperature, the combustion and burnout performance of the pulverized coal can be significantly enhanced, and the low-load stable combustion capacity and combustion efficiency of the coal-fired generating unit can be improved.

[0060] In this embodiment, the cooled main steam is used to supply heat to the heat user. In the case of low load of the coal-fired generating unit, part of the main steam is extracted for heat supply, resulting in a reduction in the steam flow rate flowing through the subsequent heating surfaces, an increase in the heat absorption per unit mass of the working medium, and an increase in the temperature of the main steam and the reheated steam of the boiler, which can improve the economy of the coal-fired unit in the low-load operation state.

[0061] In the prior art, when using the reheated steam to supply heat to the heat user, only the reheated steam is subjected to desuperheating and pressure reduction operations before supplying heat to the heat user, reducing the energy grade of the reheated steam and causing energy loss of the reheated steam, thereby increasing the pulverized coal consumption.

[0062] In this embodiment, when the coal-fired power generation unit is in the normal load operation state or the high load operation state, the reheated steam passes through the hot air heater 4 to heat the hot air by using its heat. After the reheated steam heats the hot air, its temperature decreases. There is no need to reduce the temperature and pressure of the reheated steam as required in the prior art and then use it for heating the heat users, thus ensuring the energy grade of the reheated steam. Then, the cooled reheated steam is used to heat the heat users, so that the heat of the reheated steam is fully utilized, achieving the best heating economy, reducing the pulverized coal consumption, and achieving the energy-saving effect.

[0063] Similarly, in this embodiment, when the coal-fired power generation unit is in the low load operation state, the reheated steam passes through the hot air heater 4 to heat the hot air by using its heat. After the main steam heats the hot air, its temperature decreases. There is no need to reduce the temperature and pressure of the main steam as required in the prior art and then use it for heating the heat users, thus ensuring the energy grade of the main steam. Then, the cooled main steam is used to heat the heat users, so that the heat of the reheated steam is fully utilized, achieving the best heating economy, reducing the pulverized coal consumption, and achieving the energy-saving effect.

[0064] In this embodiment, the system further includes a first high-pressure heater 5, and the first high-pressure heater 5 has a first input end, a second input end, a first output end, and a second output end; the second input end of the first high-pressure heater 5 is used for inputting feed water.

[0065] The heat supply main pipe 3 further has a first output end and a second output end, and the second output end is connected to the first input end of the first high-pressure heater 5.

[0066] The cooled main steam in the heat supply main pipe 3 is divided into two paths. One path of the cooled main steam supplies heat to the heat users through the first output end of the heat supply main pipe 3; the other path of the cooled main steam flows to the first high-pressure heater 5 through the second output end of the heat supply main pipe 3.

[0067] The other path of the cooled main steam flowing to the first high-pressure heater 5 is used to heat the feed water.

[0068] In this embodiment, the first high-pressure heater 5 uses the original high-pressure heater 5 of the coal-fired power generation unit, such as the No. 1 high-pressure heater 5. The cooled main steam entering the No. 1 high-pressure heater 5 replaces the extraction steam of the original steam turbine of the coal-fired power generation unit to heat the feed water in the high-pressure heater 5.

[0069] After the feed water is heated by the cooled main steam in the first high-pressure heater 5, it enters the economizer 19 along the feed water pipeline 20. Since the temperature of the feed water entering the economizer 19 increases significantly, the heat absorption of the economizer 19 decreases, so the SCR denitration inlet flue gas temperature can be increased.

[0070] The flue gas temperature at the SCR denitrification inlet is increased by main steam, which is different from the prior art that the flue gas temperature at the SCR denitrification inlet is increased by a bypass flue. This avoids the problem that the amount of flue gas involved in heat exchange is reduced due to the newly added bypass flue using the furnace flue gas to increase the flue gas temperature at the SCR denitrification inlet, thereby affecting the work of the steam turbine.

[0071] In this embodiment, a cooling water module is further provided on the heating main pipe 3 , and the cooling water module is used to spray water to cool the main steam or reheated steam entering the hot air heater 4 .

[0072] Furthermore, the desuperheating water module includes a desuperheating water pipeline 6, which is used to spray desuperheating water on the heating main pipe 3 to desuperheat the main steam or reheated steam entering the hot air heater 4. The desuperheating water module is arranged on the heating main pipe 3 before the hot air heater 4, and controls the steam temperature and heating parameters entering the hot air heater 4 by spraying water to reduce the temperature. The desuperheating water can come from the boiler superheating desuperheating water.

[0073] In this embodiment, a cold reheating pipeline 8 is also included, and the cold reheating pipeline 8 is used to provide cold reheating steam to heat users to achieve heating for the heat users.

[0074] In this embodiment, the cold reheating pipe 8 is connected to the inlet end of the reheater 21;

[0075] The cold reheating pipeline 8 is used to provide cold resteam to the reheater 21 , and the reheater 21 is used to heat the cold resteam into reheated steam and then output it to the hot reheating pipeline 2 .

[0076] In this embodiment, the system also includes a second three-way valve 25, which is arranged on the reheat steam pipe 16 of the coal-fired generator set, the first end of the second three-way valve 25 is connected to the reheater 21, the second end of the second three-way valve 25 is connected to the hot reheating pipe 2, and the third end of the second three-way valve 25 is connected to the medium-pressure cylinder of the coal-fired generator set.

[0077] After the reheater 21 heats the cold reheat steam, it selects to deliver the reheat steam to the hot reheating pipeline 2 or the medium-pressure cylinder through the second three-way valve 25.

[0078] In this embodiment, the system further includes a first valve group 9, a second valve group 10, a third valve group 11, a fourth valve group 12, a fifth valve group 13 and a sixth valve group 14;

[0079] The first valve group 9 is arranged on the main steam heating pipeline 1 and is used to adjust the flow of the main steam to the heating main pipe 3 .

[0080] The second valve group 10 is arranged on the hot reheat supply pipeline 2 and is used to adjust the flow rate of the reheated steam going to the heat supply main pipe 3.

[0081] The third valve group 11 is arranged on the desuperheating water pipeline 6 and is used to adjust the flow rate of the boiler superheated desuperheating water for spraying desuperheating into the heat supply main pipe 3.

[0082] The fourth valve group 12 is arranged on the cold reheat supply pipeline 8 and is used to adjust the flow rate of the cold reheat steam in the cold reheat supply pipeline 8.

[0083] The fifth valve group 13 is arranged on the pipeline for supplying heat to heat users and is used to adjust the flow rates of the cooled reheated steam and the cooled main steam.

[0084] The sixth valve group 14 is arranged on the pipeline at the second output end of the heat supply main pipe 3 and is used to adjust the flow rate of another path of the cooled main steam flowing to the first high-pressure heater 5.

[0085] The first valve group 9, the second valve group 10, the third valve group 11, the fourth valve group 12, the fifth valve group 13, and the sixth valve group 14 can select any number of shut-off valves, regulating valves, pressure-reducing valves, etc. according to their respective functional positions.

[0086] This embodiment also provides the flow directions of the main steam and the reheated steam as follows:

[0087] The main steam is taken from the main steam pipe 15 of the coal-fired generating unit. By drawing out a stream of main steam from the main steam pipe 15, after the flow rate is adjusted by the first valve group 9 arranged on the main steam heat supply pipeline 1, it goes to the heat supply main pipe 3, and then enters the hot air heater 4 to heat the hot air. After the main steam heats the hot air and cools down, one path is used for heat supply after being adjusted by the fifth valve group 13, and the other path enters the first high-pressure heater 5 to greatly increase the feed water temperature.

[0088] The reheated steam is taken from the reheated steam pipe 16 of the coal-fired generating unit. By drawing out a stream of reheated steam from the reheated steam pipe 16, after being adjusted by the second valve group 10 arranged on the hot reheat supply pipeline 2, it goes to the heat supply main pipe 3 to the hot air heater 4 to heat the hot air. After the steam heats the hot air and cools down, it is used for heat supply after being adjusted by the fifth valve group 13.

[0089] This embodiment also provides a method for realizing a wide-load heat supply system of a coal-fired generating unit, including:

[0090] When the coal-fired generating unit is in a low-load operation state, draw out the main steam of the coal-fired generating unit to supply heat to heat users;

[0091] When the coal-fired generating unit is in a normal-load operation state or a high-load state, draw out the reheated steam of the coal-fired generating unit to supply heat to heat users.

[0092] In this embodiment, when the coal-fired power generation unit is in a low-load operation state, extracting the main steam of the coal-fired power generation unit to supply heat to heat users includes:

[0093] When the coal-fired power generation unit is in a low-load operation state, extracting the main steam of the coal-fired power generation unit, and performing a primary heat exchange between the main steam and the hot air input to the boiler furnace of the coal-fired power generation unit to obtain the heated hot air and the cooled main steam;

[0094] The cooled main steam is divided into two paths. One path of the cooled main steam is used to supply heat to heat users, and the other path of the cooled main steam performs a secondary heat exchange with the feed water of the economizer 19 input to the coal-fired power generation unit to obtain the heated feed water.

[0095] In this embodiment, when the coal-fired power generation unit is in a normal-load operation state or a high-load state, extracting the reheated steam of the coal-fired power generation unit to supply heat to heat users includes:

[0096] When the coal-fired power generation unit is in a high-load operation state or a normal-load state, extracting the reheated steam of the coal-fired power generation unit, and performing a primary heat exchange between the reheated steam and the hot air input to the boiler furnace of the coal-fired power generation unit to obtain the heated hot air and the cooled reheated steam;

[0097] The cooled reheated steam is used to supply heat to heat users.

[0098] In this embodiment, the method further includes:

[0099] When the coal-fired power generation unit is in a high-load operation state or a normal-load operation state, and at the same time the heat supply flow rate of the coal-fired power generation unit is greater than a first preset value, extracting the reheated steam and the cold reheat steam of the coal-fired power generation unit to supply heat to heat users.

[0100] Specifically, the method for flexibly improving the efficiency of the coal-fired power generation unit under wide load is as follows:

[0101] When the coal-fired power generation unit is in a high-load operation state or a normal-load operation state, it is determined by judging whether the proportion of the heat supply flow rate of the coal-fired power generation unit is less than 5% of the reheated steam flow rate of the coal-fired power generation unit and whether the parameters of the cold reheat steam of the coal-fired power generation unit meet the heat supply parameter requirements.

[0102] (1) When the proportion of the heat supply flow rate of the coal-fired power generation unit is less than 5% of the reheated steam flow rate of the coal-fired power generation unit and the parameters of the cold reheat steam of the coal-fired power generation unit meet the heat supply parameter requirements, the coal-fired power generation unit supplies heat to heat users through the cold reheat steam. At this time, the fourth valve group 12 is opened, and the first valve group 9, the second valve group 10, the third valve group 11, the fifth valve group 13, and the sixth valve group 14 are closed. The heat supply flow rate and parameters are adjusted through the fourth valve group 12 to meet the requirements of heat users.

[0103] (2) When the proportion of the heating flow rate of the coal-fired power generation unit is greater than 5% of the reheating flow rate of the coal-fired power generation unit, in order to avoid overheating of the boiler reheater 21 of the coal-fired power generation unit, it is necessary to adopt the combined supply method of cold reheat and hot reheat to supply heat to the heat users. At this time, open the fourth valve group 12, the second valve group 10, the third valve group 11, and the fifth valve group 13, close the first valve group 9 and the sixth valve group 14, and adjust the opening of each valve group to adjust the heating flow rate and parameters to meet the requirements of the heat users.

[0104] When the coal-fired power generation unit is in a low-load operation state, it is judged whether the denitration inlet flue gas temperature of the coal-fired power generation unit meets the requirements for putting into the denitration system.

[0105] (1) When the denitration inlet flue gas temperature of the coal-fired power generation unit meets the unit load requirements for putting into the denitration system, the coal-fired power generation unit supplies heat to the heat users through the main steam. At this time, open all the first valve group 9, the second valve group 10, the third valve group 11, the fourth valve group 12, and the fifth valve group 13, close the sixth valve group 14, and adjust the opening of each valve group to adjust the heating flow rate and parameters to meet the requirements of the heat users.

[0106] (2) When the denitration inlet flue gas temperature of the coal-fired power generation unit does not meet the unit load requirements for putting into the denitration system, the coal-fired power generation unit supplies heat to the heat users through the main steam and uses the main steam to heat the feed water temperature to increase the denitration inlet flue gas temperature. At this time, open all the valve groups, adjust the opening of each valve group to adjust the heating flow rate and parameters to meet the requirements of the heat users; adjust the opening of the sixth valve group 14 to meet the flue gas temperature requirements for putting into the denitration system under low load of the unit.

[0107] The utility model has the following beneficial effects:

[0108] (1) Solve the problem of insufficient temperature at the denitration inlet under the low-load operation state of the coal-fired power generation unit: When the temperature at the denitration inlet is insufficient, extract part of the main steam into the first high-pressure heater 5, which can significantly increase the feed water temperature to improve economy, reduce the heat absorption of the economizer 19, and thus greatly increase the denitration inlet flue gas temperature to meet the requirements for putting into denitration under low load.

[0109] (2) Improve the main steam and reheated steam temperatures of the coal-fired power generation unit under the low-load operation state: Extracting part of the main steam for heat supply under the low-load state results in a reduction in the steam flow rate flowing through the subsequent heating surfaces, an increase in the heat absorption per unit mass of the working fluid, and an increase in the main steam and reheated steam temperatures of the boiler, which can improve the economy of the unit under low load.

[0110] Increasing the reheated steam temperature also helps to improve the steam dryness at the last stage blade of the low-pressure cylinder of the steam turbine, reduce the risk of water erosion of the last stage blade, and improve the safety of long-term low-load operation of the steam turbine.

[0111] (3)Meet the full-load heating demand and heating economy of coal-fired power generation units: By adopting the wide-load heating system for coal-fired power generation units described in the present utility model, it can meet the needs of heat users under any working conditions. And the present utility model recovers the heat of the hot re-steam and the main steam through the hot air heater 4 to further match the heating demand of heat users. The recovered heat enters the boiler, which can reduce the throttling loss of the unit for heating and significantly improve the heating economy.

[0112] (4)Improve the low-load combustion capacity of the boiler: By using the hot air heater 4 to further increase the temperature of the primary / secondary air entering the furnace, it 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.

[0113] Embodiment 2

[0114] This embodiment is basically the same as Embodiment 1, the difference is that in this embodiment, the system further includes a second high-pressure heater 5, and the second high-pressure heater 5 is the original No. 1 high-pressure heater 5 in the coal-fired power generation unit. The second high-pressure heater 5 has a first input end, a second input end, a first output end and a second output end, and the second output end of the second high-pressure heater 5 is connected to the second input end of the first high-pressure heater 5;

[0115] The first input end of the second high-pressure heater 5 receives the extraction steam from the steam turbine, the second input end of the second high-pressure heater 5 is used for inputting feed water, and the second high-pressure heater 5 uses the extraction steam of the steam turbine to heat the feed water to obtain the once-heated feed water; the second high-pressure heater 5 conveys the once-heated feed water to the first high-pressure heater 5 through the second output end.

[0116] In this embodiment, the system further includes a first high-pressure heater 5, and the first high-pressure heater 5 has a first input end, a second input end, a first output end and a second output end; the second input end of the first high-pressure heater 5 is used for inputting the once-heated feed water;

[0117] The heating main pipe 3 further has a first output end and a second output end, and the second output end is connected to the first input end of the first high-pressure heater 5;

[0118] The main steam whose temperature is reduced in the heating main pipe 3 is divided into two paths. One path of the main steam whose temperature is reduced supplies heat to heat users through the first output end of the heating main pipe 3; the other path of the main steam whose temperature is reduced flows to the first high-pressure heater 5 through the second output end of the heating main pipe 3;

[0119] The other path of the main steam whose temperature is reduced and flows to the first high-pressure heater 5 is used to heat the once-heated feed water. More specifically, the first high-pressure heater 5 is a newly added high-pressure heater 5 in the present utility model, which is the No. 0 high-pressure heater 5.

[0120] The first high-pressure heater 5 and the second high-pressure heater 5 are connected in series. The first high-temperature heater uses the extraction steam of the steam turbine to heat the feed water from the feed water pump to obtain the feed water after being heated once. The feed water after being heated once is input into the first high-pressure heater 5, and the first high-pressure heater 5 uses another path of the main steam whose temperature is reduced to heat the feed water after being heated once to obtain the feed water after being heated twice.

[0121] Embodiment 3

[0122] The present utility model also provides a specific example as follows:

[0123] A certain power plant has two 2×320MW-class units. The boiler model is DG1025 / 17.4-Ⅱ14, and its type is subcritical parameters, natural circulation, double-arch furnace, intermediate once-through reheat, double flue gas ducts at the tail, balanced draft, outdoor layout, all-steel frame, all-suspended structure, and solid slag discharge. The main design parameters of the boiler are as shown in Table 1 below.

[0124] Table 1 Main design parameters of the boiler

[0125]

[0126]

[0127] The local power grid requires that this unit achieve a 30% THA load (i.e., 96MW). At present, this unit does not have the ability to deeply adjust to a 96MW load, and it is planned to carry out the "three-in-one linkage" transformation. The following problems are faced:

[0128] 1. Each unit of this power plant needs to supply heat externally at 100t / h, and the heat supply parameters are 1.3MPa / 250℃. The main heat supply method is combined cold and hot reheat supply.

[0129] 2. At a 96MW load, the SCR inlet flue gas temperature is about 285℃, which is difficult to meet the SCR minimum continuous input temperature requirement of 300℃.

[0130] 3. At low loads, the air temperature of the unit is relatively low, and the pulverized coal combustion ability is weak.

[0131] 4. At low loads, the main and reheat steam temperatures are subcooled.

[0132] The transformation is carried out by using the wide-load heat supply system described in the present utility model to meet the requirements of wide-load efficiency improvement, stable combustion at low loads, increasing the SCR inlet flue gas temperature at low loads, and heat supply at full loads.

[0133] The overall idea of the solution is as follows: At low load, steam is extracted from the main steam header, and after desuperheating and pressure reduction (pressure reduction may be required only according to the actual situation), it first enters the hot secondary air heater to heat the hot secondary air. Then, one part of the main steam enters the No. 1 first high-pressure heater 5, significantly increasing the water temperature at the inlet of the economizer 19. Since the feed water temperature at the inlet of the economizer 19 increases, the economizer 19 absorbs less heat, so the flue gas temperature at the outlet of the economizer 19 increases, thus realizing the low-load SCR system input; the other part of the steam is desuperheated and pressure-reduced for heating supply to meet the low-load heating demand.

[0134] At medium and high loads of the unit, the hot reheat extraction steam can be used to increase the temperature of the hot secondary air, improve the combustion efficiency at medium and high loads, and reduce the throttling loss of the hot reheat steam.

[0135] Retrofit effect

[0136] At low load, the high-temperature and high-pressure main steam is used to replace the low-temperature and low-pressure extraction steam of the first stage, making the No. 1 high-pressure heater equivalent to the No. 0 high-pressure heater at this time. Therefore, the feed water temperature can be significantly increased, and the SCR inlet flue gas temperature can be increased to above 300°C. At the same time, the temperature of the hot secondary air can also be significantly increased, realizing stable combustion at low load and improving the low-load combustion efficiency.

[0137] System design calculation at 30% THA load

[0138] System design boundary conditions

[0139] Deep peak shaving to 30% THA (96 MW), and the design parameters on the working medium side refer to the heat balance diagram at 30% THA (96 MW) load, as shown in Table 2 below

[0140] Table 2 System design parameters at 30% THA load

[0141] Serial Number Utility Model Data Remarks 1 Main Steam Pressure (MPa) 7.85 Heat Balance Diagram 2 Main Steam Temperature (°C) 516 Heat Balance Diagram 3 Main Steam Flow (t / h) 294.21 Heat Balance Diagram 4 Reheat Steam Pressure (MPa) 1.097 Heat Balance Diagram 5 Reheat Steam Temperature (°C) 510 Calculated Based on Operating Data 6 Cold Reheat Inlet Pressure 1.193 7 Cold Reheat Inlet Temperature (°C) 275 Calculated Based on Operating Data 8 Feed Water Flow (t / h) 294.21 9 Feed Water Pressure (MPa) 8.55 10 Outlet Temperature of No. 2 High Pressure Heater (°C) 185.4 Heat Balance Diagram 11 Outlet Temperature of No. 1 High Pressure Heater (°C) 210.4 Heat Balance Diagram 12 Extraction Pressure of No. 2 Extraction Steam (MPa) 1.193 Heat Balance Diagram 13 Extraction Pressure of No. 1 Extraction Steam (MPa) 1.956 Heat Balance Diagram 14 Temperature of No. 1 Extraction Steam (°C) 345.4 Heat Balance Diagram 15 Drain Temperature of No. 1 Extraction Steam (°C) 191 Heat Balance Diagram 16 SCR Inlet Temperature (°C) 280 Calculated Based on Operating Data

[0142] Other design parameters are selected as follows:

[0143] (1) At 30% THA load, the SCR inlet flue gas temperature is calculated according to 285°C.

[0144] (2) At 30% THA load, the feed water temperature is calculated according to 210.4°C.

[0145] (3) At 30% THA load, according to the DCS screen, the main steam pressure is 7.85 MPa, the main steam temperature is 516°C, and the reheat steam temperature is 510°C.

[0146] System analysis and thermal calculation are as follows:

[0147] 1. Thermal calculation of main steam desuperheating and pressure reduction

[0148] Under the 30% THA condition, the extracted main steam passes through the bypass valve for desuperheating and pressure reduction, and then enters the hot secondary air heater. The thermodynamic calculation of the main steam desuperheating and pressure reduction is shown in Table 3 below.

[0149] Table 3 Main Steam Thermodynamic Calculation Table

[0150] Serial Number Name Unit Value Remarks 1 Main Steam Flow on Turbine Side t / h 294.21 Entering the Steam Turbine 2 Main Steam Flow on Boiler Side t / h 342.21 3 Main Steam Pressure MPa 7.85 Sliding Pressure Operation 4 Main Steam Temperature ℃ 516 5 Feed Water Pressure MPa 8.55 6 Extracted Main Steam Flow t / h 48 7 Main Steam Flow after Pressure Reduction t / h 48 8 Main Steam Pressure after Desuperheating and Pressure Reduction MPa 6.538 9 Main Steam Temperature after Desuperheating and Pressure Reduction ℃ 505.594

[0151] 2. Thermodynamic Calculation of Hot Air Heater 4

[0152] Under the 30% THA condition, the extracted steam after desuperheating and pressure reduction from the bypass valve enters the hot secondary air heater. The hot air heater 4 uses an integral spiral finned tube heat exchanger, and the material is selected as 12Cr1MoVG.

[0153] The thermodynamic calculation of the hot air heater 4 is shown in Table 4 below.

[0154] Table 4 Thermodynamic Calculation Table of Hot Air Heater 4

[0155] Serial Number Name Unit Value Remarks 1 Inlet Steam Flow of Hot Air Heater t / h 48 2 Inlet Steam Pressure of Hot Air Heater MPa.a 6.538 3 Inlet Steam Temperature of Hot Air Heater ℃ 505.594 4 Steam Side Differential Pressure MPa.a 0.3 5 Outlet Steam Pressure of Hot Air Heater MPa.a 6.238 6 Outlet Steam Temperature of Hot Air Heater ℃ 330 7 Heat Transfer Quantity of Hot Air Heater MW 6 8 Inlet Temperature of Hot Secondary Air ℃ 280 9 Outlet Temperature of Hot Secondary Air ℃ 330 Higher than THA Condition Temperature 10 Temperature Rise of Hot Secondary Air ℃ 50 Total Temperature Rise 50 + 20 = 75°C 11 Flow Rate of Hot Secondary Air t / h 400 12 Air Side Pressure Loss Pa <100 THA Load Less than 300 Pa 13 Steam Side Resistance MPa <0.3 14 Number of Hot Air Heaters Unit 2

[0156] The layout scheme of the hot air heater 4 is shown in Table 5 below.

[0157] Table 5 Layout Scheme of Hot Air Heater 4

[0158] Name Unit Data Heat Transfer Method / Countercurrent Heat Transfer Arrangement Method / In-line Arrangement Outer Diameter of Heat Exchanger Tube mm 32 Wall Thickness of Heat Exchanger Tube mm 3 Material of Heat Exchanger Tube - 12Cr1MoVG Finned Height mm 14 Finned Thickness mm 1.5 Finned Pitch mm 13 Finned Material - 12Cr1MoV Transverse Pitch mm 100 Transverse Rows Row 24 Longitudinal Pitch mm 80 Longitudinal Rows Row 16 Parallel Number of Tubes Tube 2

[0159] The air side resistance of the hot air heater 4 is less than 100 Pa at 30% THA load, and does not exceed 300 Pa under THA condition. The steam side resistance is less than 0.3 MPa.

[0160] 3. Variable Condition Thermodynamic Calculation of No. 1 High-Pressure Heater

[0161] Under the 30% THA condition, the steam coming out of the hot secondary air heater replaces the original extraction steam of the first stage and enters the No. 1 high-pressure heater. The thermodynamic calculation of the No. 1 high-pressure heater is shown in Table 6 below.

[0162] Table 6 Variable Condition Thermodynamic Calculation Table of No. 1 High-Pressure Heater

[0163]

[0164]

[0165] As can be seen from the above table, after reducing the pressure and temperature of the main steam to the same pressure and temperature as the steam at the inlet of the No. 1 high-pressure heater under THA condition and through variable condition calculation, the heat transfer quantity of the No. 1 high-pressure heater after transformation is lower than that under the original THA condition at 30% THA condition. The heat transfer area margin of the No. 1 high-pressure heater under low load can be utilized, and at this time, the upper and lower terminal differences of the No. 1 high-pressure heater increase compared with the original parameters.

[0166] After the transformation, the feed water temperature is increased from the original 210.4°C to 250.14°C, with an increase of 39.74°C. At this time, the No. 1 high-pressure heater is equivalent to the No. 0 high-pressure heater, improving the regenerative effect of the steam turbine and greatly enhancing the economy.

[0167] After the transformation, the steam inlet volume of the No. 1 high-pressure heater is 48 t / h, which is 33.893 t / h higher than the 14.107 t / h before the transformation. The steam flow rate entering the reheater 21 decreases, and the steam temperature of the reheater 21 increases under low load.

[0168] 4. Thermal calculation of the economizer 19 under off-design conditions

[0169] The thermal calculation of the economizer 19 under off-design conditions and the SCR inlet flue gas temperature under 30% THA condition is shown in Table 7 below.

[0170] Table 7 Thermal calculation table of the economizer 19 under off-design conditions and the SCR inlet flue gas temperature

[0171]

[0172]

[0173] As can be seen from Table 7 above, under the 30% THA condition after the transformation, the SCR inlet flue gas temperature is increased from 285°C to 305°C, an increase of 20°C.

[0174] Under the 30% THA condition after the transformation, the outlet feed water temperature (the inlet temperature of the water wall) of the economizer 19 is increased from 230.5°C to 259.4°C, and the outlet water temperature subcooling degree is 47.27°C, which can ensure the normal operation of the SCR under low load and the safe operation of the boiler.

[0175] 5. Reheat steam temperature rise calculation

[0176] The boiler-turbine coupling scheme uses the main steam to replace the extraction steam 1, which will lead to a reduction in the reheated steam volume of the boiler and an increase in the reheated steam temperature.

[0177] The calculation of the change in the reheated steam temperature is shown in Table 8 below.

[0178] Table 8 Reheat steam temperature rise calculation table under 30% THA load

[0179] Serial Number Name Unit Before Modification 30% THA After Modification 30% THA Remarks 1 Main Steam Flow of Boiler t / h 294.21 342.21 2 Extracted Main Steam Flow t / h 0 48 3 Reheat Steam Flow t / h 250.137 238.337 4 Cold Reheat Steam Pressure MPa 1.193 1.193 5 Cold Reheat Steam Temperature ℃ 275 275 6 Hot Reheat Steam Pressure MPa 1.097 1.097 7 Hot Reheat Steam Temperature ℃ 510 520 8 Heat Absorbed by Reheater MW 35.08 34.86 9 Increase Reheat Steam Temperature ℃ - 10

[0180] Extract 48 t / h of the main steam and use it all to replace the extraction steam 1. After the transformation, the reheated steam temperature is increased by 10°C, and the reheated steam temperature reaches 520°C.

[0181] 6. Economic analysis calculation

[0182] The main changes in the economy under the 30% THA condition include the following parts:

[0183] (1) Due to a significant increase in the temperature of the hot secondary air, the combustion efficiency of the boiler is improved, the carbon content in fly ash and large slag is reduced, and the boiler efficiency is increased.

[0184] (2) The SCR inlet flue gas temperature is 20 °C, the exhaust gas temperature rises by 6 °C, and the boiler efficiency decreases.

[0185] (3) Extracting the main steam flow rate to replace the No. 1 extraction steam increases the feed water temperature and the reheat steam temperature, improves the unit cycle efficiency, and reduces the heat consumption rate of the steam turbine.

[0186] (4) Extracting the main steam flow rate to replace the No. 1 extraction steam reduces the work capacity of the unit and increases the heat consumption rate of the steam turbine.

[0187] Based on the above impact analysis, through calculation, the power supply coal consumption rate of the unit under 30% THA load after transformation is reduced by 0.6 g / kWh.

[0188] THA Load System Design Calculation

[0189] Under full load, cold and hot reheat combined supply mode is adopted for external heating. Among them, the hot reheat extraction steam is heated after being desuperheated and pressure-reduced for heating. The utility model uses this part of the hot reheat steam to heat the hot secondary air at the outlet of the air preheater 7 and then uses it for heating, making full use of the existing energy and improving the utilization rate of high-quality steam energy.

[0190] The transformation benefits of the utility model under THA load are as shown in Table 9 below.

[0191] Table 9 Transformation Benefits under THA Load

[0192] Number Utility Model Unit Before Modification After Modification 1 Heat Reheat Pressure for Heat Supply MPa 3.4 3.4 2 Heat Reheat Temperature for Heat Supply ℃ 541 541 3 Heat Reheat Flow for Heat Supply t / h 70 83 4 Heat Supply Pressure MPa 1.6 1.6 5 Heat Supply Temperature ℃ 280 280 6 Heat Supply Flow t / h 83 83 7 Heat Recovered by Boiler MW / 12.8 8 Unit Power Generation Efficiency ％ / 45 9 Equivalent Coal Saving Quantity g / kWh / 5.58

[0193] As can be seen from Table 9, installing the hot primary air system reduces the throttling loss of the unit's hot reheat, and the converted savings in power supply coal consumption is 5.58 g / kWh.

[0194] After the transformation using the scheme described in the utility model, when the unit load is 96 MW (30% THA), the SCR inlet flue gas temperature can reach above 300 °C, meeting the minimum SCR inlet flue gas temperature requirement, maintaining a high denitration efficiency of the SCR reactor, reducing ammonia escape, and having great environmental benefits.

[0195] After the utility model is put into operation at low load, the power supply coal consumption rate of the unit decreases by 0.6 g / kWh. When put into operation at high load, using the hot reheat steam to heat the hot secondary air for heating, the power supply coal consumption is reduced by 5.58 g / kWh.

[0196] After the implementation of the utility model, the full-load heating demand can be met.

[0197] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0198] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

[0199] The optional embodiments of the present invention have been 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 embodiments. Within the technical concept scope of the embodiments of the present invention, various simple variations can be made to the technical solutions of the embodiments of the present invention, and these simple variations all fall within the protection scope of the embodiments of the present invention. Additionally, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any appropriate manner, as long as this combination does not violate the idea of the embodiments of the present invention, and it should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A wide load heating system for coal-fired generator sets, characterized in that: include: Main steam heating pipeline, hot reheating pipeline and heating main pipe; The input end of the main steam heating pipeline is connected to the high-temperature superheater and the low-temperature superheater through a first three-way valve, and the output end of the main steam heating pipeline is connected to the input end of the heating main pipe, so as to transport the main steam from the high-temperature superheater or the low-temperature superheater to the heating main pipe when the coal-fired power generation unit is in a low-load operation state; The input end of the hot reheating pipeline is connected to the reheater of the coal-fired power generation unit, and the output end of the hot reheating pipeline is connected to the input end of the heating main pipe, so as to transport the reheated steam from the reheater to the heating main pipe when the coal-fired power generation unit is in a high-load operation state or a normal-load operation state; The output end of the heating main pipe is used to supply heat to heat users through main steam when the coal-fired generator set is in low-load operation state, and to supply heat to heat users through reheat steam when the coal-fired generator set is in normal load operation state and high load operation state.

2. The wide load heating system for coal-fired power generation units according to claim 1, characterized in that: It also includes a hot air heater, the hot air heater having a first input end, a first output end, a second input end and a second output end, and the hot air heater inputs hot air through the second input end; The heat supply mother pipe has a heat exchange input end and a heat exchange output end, and the heat supply mother pipe transports main steam or reheat steam to the first input end of the hot air heater through the heat exchange output end; The main steam or reheated steam exchanges heat with the hot air in the hot air heater to obtain cooled main steam or cooled reheated steam, and heated hot air; The cooled main steam or the cooled reheated steam returns to the heating main pipe through the heat exchange input end; The heated hot air flows to the boiler furnace of the coal-fired power generation unit through the second output end of the hot air heater.

3. The wide load heating system for coal-fired power generation units according to claim 2, characterized in that: It also includes a first high-pressure heater, the first high-pressure heater having a first input end, a second input end, a first output end and a second output end; the second input end of the first high-pressure heater is used to input feed water; The heating mother pipe also has a first output end and a second output end, and the second output end is connected to the first input end of the first high-pressure heater; The cooled main steam from the heating main pipe is divided into two paths, one path of the cooled main steam supplies heat to the heat user through the first output end of the heating main pipe; the other path of the cooled main steam flows to the first high-pressure heater through the second output end of the heating main pipe; Another path of the cooled main steam flowing into the first high-pressure heater is used to heat the feed water.

4. The wide load heating system for coal-fired power generation units according to claim 3 is characterized in that: Also includes a second high-voltage heater, the second high-voltage heater having a first input end, a second input end, a first output end and a second output end, the second output end of the second high-voltage heater being connected to the second input end of the first high-voltage heater; The first input end of the second high-pressure heater receives extraction steam from the steam turbine, the second input end of the second high-pressure heater is used to input feed water, the second high-pressure heater uses the extraction steam from the steam turbine to heat the feed water to obtain the once heated feed water; the second high-pressure heater transmits the once heated feed water to the first high-pressure heater through the second output end; The first high-pressure heater uses the other path of cooled main steam to heat the once heated feed water.

5. The wide load heating system for coal-fired power generation units according to claim 2, characterized in that: The heating main pipe is also provided with a cooling water pipeline, which is used to spray cooling water on the heating main pipe to cool the main steam or reheated steam entering the hot air heater.

6. The wide load heating system for coal-fired power generation units according to claim 1, characterized in that: It also includes a cold reheating pipeline, which is used to provide cold reheating steam to heat users to achieve heating for the heat users.

7. The wide load heating system for coal-fired power generation units according to claim 6, characterized in that: The cold reheating pipeline is connected to the inlet end of the reheater; The cold reheating pipeline is used to provide cold resteam to the reheater, and the reheater is used to heat the cold resteam into reheated steam and then output it to the hot reheating pipeline.

8. The wide load heating system for coal-fired power generation units according to claim 7, characterized in that: It also includes a second three-way valve, which is arranged on the reheat steam pipe of the coal-fired generator set, the first end of the second three-way valve is connected to the reheater, the second end of the second three-way valve is connected to the hot reheating pipe, and the third end of the second three-way valve is connected to the medium-pressure cylinder of the coal-fired generator set.

9. The wide load heating system for coal-fired power generation units according to claim 1, characterized in that: Also includes a first valve group and a second valve group; The first valve group is arranged on the main steam heating pipeline, and is used to adjust the flow rate of the main steam flowing from the main steam heating pipeline to the heating main pipe; The second valve group is arranged on the hot reheating pipeline, and is used to adjust the flow rate of the reheated steam flowing from the hot reheating pipeline to the heating mother pipe.

10. The wide load heating system for coal-fired power generation units according to claim 5, characterized in that: It also includes a third valve group, which is arranged in the cooling water pipeline and is used to adjust the flow rate of the cooling water.

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