Tandem system for air cooling unit to adapt to large-temperature-difference heat supply

Abstract

The utility model discloses a series connection system of an air cooling unit suitable for large-temperature-difference heat supply, and belongs to the technical field of energy conservation and consumption reduction of coal-fired units. A heat source of a primary heat supply network heater of the system is communicated with exhaust steam of a low-pressure cylinder, a heat source of a peak heater is communicated with exhaust steam of an intermediate-pressure cylinder, and an absorption heat pump is communicated with a heating station. According to the system, an absorption type heat pump is introduced to a heat supply network water circulation pipeline, low-temperature heat of heat supply network return water is fully utilized through the absorption type heat pump, heat supply network water with heat loss caused by long-distance transmission is heated through the low-temperature heat, heat of dead steam can be fully utilized, and the heat supply network return water temperature is changed from traditional 130 / 70 DEG C to 130 / 30 DEG C; the temperature difference of supply water and return water of the heat supply network is increased, more power plant waste heat is recycled through the first-stage heat supply network heater and the peak heater, a large-temperature-difference long-distance heat plant waste heat conveying central heating mode is formed, and the conveying capacity of the heat supply network is greatly improved.

Description

Technical Field

[0001] This utility model belongs to the field of energy conservation and consumption reduction of coal-fired power units, and specifically relates to a series connection system for air-cooled units to adapt to large temperature difference heating. Background Technology

[0002] In the power system, thermal power units have always played a vital role due to their stable and reliable power generation performance. However, with the continuous acceleration of urbanization, the demand for centralized heating in cities is also increasing. Due to geographical location, resource distribution, or urban planning reasons, some cities lack sufficient heat sources to meet the growing heating demand. Therefore, recovering waste heat from remote power plants and industrial areas and supplying it to cities over long distances has become a practical solution.

[0003] Traditional heat transfer methods have demonstrated economic viability and feasibility when meeting short-distance or small-scale heating needs. However, their limitations become apparent when heat needs to be transported long distances from remote power plants or industrial areas to cities. Specifically, due to the longer distances, traditional methods often require larger circulating water flows to maintain sufficient heating temperatures and meet urban heat demands. This increased flow not only increases pump energy consumption but also necessitates a corresponding increase in the diameter of the circulating water pipes to withstand the greater water pressure and flow rate.

[0004] The increase in the diameter of circulating water pipes directly leads to an increase in investment costs. On the one hand, the material costs, processing costs, and installation costs of large-diameter pipes are relatively high; on the other hand, the construction of large-diameter pipes also requires more manpower, resources, and time, further increasing the difficulty and cost of construction. In addition, large-diameter pipes also present many inconveniences in terms of maintenance and management, increasing the later operating costs and maintenance expenses.

[0005] Therefore, in order to solve the problems of large circulating water flow, increased pipe diameter, and rising investment costs in long-distance heating processes, the industry urgently needs a new heat transmission method. This method needs to be able to maintain sufficient heating temperature while reducing circulating water flow and pipe diameter, lowering investment costs and construction difficulty, and improving the transmission capacity and economy of the heating network. Utility Model Content

[0006] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a series system for air-cooled units to adapt to heating with large temperature differences, so as to solve the problems of large circulating water flow, large pipe diameter and high investment in the long-distance heating process in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A series system for air-cooled units adapted to heating with large temperature differences includes a heating network water circulation pipeline; along the direction of water flow, a primary heating network heater, a peak heater, a heating station, a heating user, and an absorption heat pump are sequentially arranged on the heating network water circulation pipeline;

[0009] The hot end inlet of the primary heating network heater is connected to the low-pressure cylinder exhaust, and the hot end inlet of the peak heater is connected to the medium-pressure cylinder exhaust; the cold source inlet of the absorption heat pump is connected to the outlet of the heat user, the cold source outlet of the absorption heat pump is connected to the cold end inlet of the primary heating network heater, and the heat source outlet of the absorption heat pump is connected to the hot end inlet of the heat station.

[0010] The further improvement of this utility model is as follows:

[0011] Preferably, a booster pump is provided between the cold source outlet of the absorption heat pump and the primary heating network heater.

[0012] Preferably, the low-pressure cylinder is the low-pressure cylinder of Unit 1, and the intermediate-pressure cylinder is the intermediate-pressure cylinder of Unit 2.

[0013] Preferably, the steam input pipeline of the low-pressure cylinder of Unit 1 is connected to the steam output pipeline of the intermediate-pressure cylinder of Unit 1.

[0014] Preferably, both the low-pressure cylinder and the intermediate-pressure cylinder of Unit 1 are modified to have high back pressure.

[0015] Preferably, the steam output pipeline of the intermediate pressure cylinder of Unit 2 is simultaneously connected to the hot end inlet of the peak heater and the steam input pipeline of the low pressure cylinder of Unit 2.

[0016] Preferably, a regulating valve is installed on the steam output pipeline of the intermediate pressure cylinder of Unit 2. The regulating valve is located before the hot end inlet of the peak heater and before the steam input pipeline of the low pressure cylinder of Unit 2.

[0017] Preferably, the steam output pipeline of the intermediate pressure cylinder of the second unit is perforated, and the steam obtained by perforation is connected to the peak heater.

[0018] Preferably, the distance between the peak heater and the heating station is ≥20km.

[0019] Preferably, the inlet water temperature of the primary heating network heater is 30°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This utility model discloses a series system for air-cooled units adapted to heating with large temperature differences. The system introduces an absorption heat pump into the heating network water circulation pipeline. The absorption heat pump can fully utilize the low-temperature heat of the heating network return water. This low-temperature heat is used to heat the heating network water that has lost heat due to long-distance transmission, so that the exhaust steam can be fully utilized. The temperature difference between the heating network supply and return water is changed from the traditional 130 / 70℃ to 130 / 30℃. The temperature difference between the heating network supply and return water is increased, and more waste heat from the power plant can be recovered through the primary heating network heater and the peak heater. This forms a centralized heating mode for long-distance transmission of waste heat from thermal power plants with large temperature differences, which greatly improves the transmission capacity of the heating network.

[0022] Furthermore, this invention reduces the unit's energy consumption. In air-cooled units, due to the higher designed exhaust pressure, there is no need to switch rotors during the heating and pure condensing periods, resulting in lower modification costs. After adopting this system, the turbine's cold source loss can be reduced because, through high back pressure modification, all exhaust steam enters the primary heating network heater to heat the heating network return water, reducing the unit's heat consumption and improving the overall economic efficiency of the turbine.

[0023] Furthermore, by drilling and extracting steam and connecting high back pressure in series, energy can be utilized in stages, ensuring the stability and flexibility of the entire heating system. The supply water temperature is maintained by adjusting the regulating valve on the medium and low pressure cylinder connecting pipe. Secondary heating by the peak heater effectively meets the supply water temperature requirements, and the absorption heat pump further reduces the return water volume and improves the heat exchange effect.

[0024] Furthermore, by installing absorption heat pumps at the heating station, the high-temperature hot water from the primary network is used as the driving heat source. The absorption heat pump significantly reduces the temperature of the primary network return water. This technology increases the temperature difference between the primary network supply and return water while keeping the secondary network operating parameters unchanged, thus greatly improving the heating capacity. Attached Figure Description

[0025] Figure 1 This is a system structure diagram of the present invention;

[0026] 1. Intermediate-pressure cylinder of Unit 1; 2. Intermediate-pressure cylinder of Unit 2; 3. Regulating valve; 4. Low-pressure cylinder of Unit 2; 5. Generator of Unit 2; 6. Low-pressure cylinder of Unit 1; 7. Generator of Unit 1; 8. Heat user; 9. Heat station; 10. Absorption heat pump; 11. Peak heater; 12. Booster pump; 13. Primary heating network heater. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings:

[0028] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0029] As the background technology points out, some cities lack heat sources for centralized heating and need to supply heat to the city from remote power plants and industrial waste heat. However, due to the long distance, if traditional heat transmission methods are used, it will result in a large circulating water flow, which in turn will increase the diameter of the circulating water pipes and significantly increase investment costs.

[0030] To address the aforementioned problems, this utility model discloses a series connection system for air-cooled units to adapt to large temperature difference heating. The system includes a No. 1 unit medium-pressure cylinder 1, a No. 2 unit medium-pressure cylinder 2, a regulating valve 3, a No. 2 unit low-pressure cylinder 4, a No. 2 unit generator 5, a No. 1 unit low-pressure cylinder 6, a No. 1 unit generator 7, a heat user 8, a heat station 9, an absorption heat pump 10, a peak heater 11, a booster pump 12, and a primary heat network heater 13.

[0031] This utility model includes two heating bodies and a circulating water circuit.

[0032] The two heating units are Unit 1 and Unit 2. The steam for the intermediate pressure cylinder 1 of Unit 1 comes from the high pressure cylinder. The steam output pipeline of the intermediate pressure cylinder 1 of Unit 1 is connected to the steam input pipeline of the low pressure cylinder 6 of Unit 1. The power output shafts of the intermediate pressure cylinder 1 and the low pressure cylinder 6 of Unit 1 are connected to the generator 7 of Unit 1.

[0033] The steam for intermediate-pressure cylinder 2 of Unit 2 originates from the high-pressure cylinder. The steam output pipeline of intermediate-pressure cylinder 4 of Unit 2 is connected to the steam input pipeline of low-pressure cylinder 4 of Unit 2. The power output shafts of intermediate-pressure cylinder 1 and low-pressure cylinder 4 of Unit 2 are connected to generator 5 of Unit 2. A regulating valve 3 is installed between the steam output pipeline of intermediate-pressure cylinder 4 and the steam input pipeline of low-pressure cylinder 4 of Unit 2.

[0034] Along the water flow direction, the circulating water circuit includes a primary heating network heater 13, a peak heater 11, a heating station 9, a heating user 8, an absorption heat pump 10, and a booster pump 12 connected in sequence. The outlet of the booster pump 12 is connected to the inlet of the primary heating network heater 13.

[0035] The circulating water is output from the peak heater 11 and then input into the heating station 9 as heating network water supply. The heating station 9 further adds the heating network water supply and then it enters the heating network user 8. After the heating network user 8 uses the heating network water supply, the heating network water supply becomes heating network return water and returns to the absorption heat pump 10.

[0036] The cold end inlet of the primary heating network heater 13 is connected to the outlet of the booster pump 12, the cold end outlet of the primary heating network heater 13 is connected to the cold end inlet of the peak heater 11, and the hot end inlet of the primary heating network heater 13 is connected to the exhaust of the low-pressure cylinder 4 of Unit 1. The heating network heater is a surface heater, using tubes as the heat transfer surface. Extracted steam enters the heating network heater shell and flows outside the tubes; the network feedwater enters the water chamber under the action of the heating network water pump and flows into the heat exchange tubes in the piping system. The water inside the heat exchange tubes absorbs the heat from the condensation of the heating steam flowing counter-currently outside the heat exchange tubes, bringing the network feedwater to the temperature required for heating.

[0037] The cold end inlet of the peak heater 11 is connected to the cold end outlet of the primary heating network heater 13, and the cold end outlet of the peak heater 11 is connected to the inlet of the heating station 9. The hot end inlet of the peak heater 11 is connected to the steam output pipeline of the intermediate-pressure cylinder 2 of Unit 2. The output steam of the intermediate-pressure cylinder 2 of Unit 2 is output to the peak heater 11 and the low-pressure cylinder 4 of Unit 2, respectively. A regulating valve 3 is installed in the steam output pipeline of the intermediate-pressure cylinder 2 of Unit 2 before the hot end inlet pipeline of the peak heater 11 to distribute the steam intake into the low-pressure cylinder and the peak heater. The peak heater is a device that can provide peak heat energy output under specific operating conditions. It uses a resistor as a heating element, converts electrical energy into heat energy through heating wires, and rapidly transfers the heat to the medium that needs to be heated through an efficient heat transfer method.

[0038] Heating station 9, as the connection point between the centralized heating network and the heat users, mainly plays the role of an intermediary for intermediate heat exchange and heat redistribution. In this utility model, it is used to further heat the heating network water that has been cooled down after long-term transportation. Generally, the distance between the outlet of the peak heater 11 and the heating station 9 is greater than or equal to 20km. Specifically, the heat is further heated by the heat output from the absorption heat pump 10. The cold end inlet of the heating station 9 is connected to the cold end outlet of the peak heater 11, and the cold end outlet of the heating station 9 is connected to the heat users.

[0039] An absorption heat pump 10 is a circulating system that utilizes a low-grade heat source to pump heat from a low-temperature heat source to a high-temperature heat source. In this invention, the absorption heat pump 10 absorbs heat from the return water of the heating network output from the heating user 8 and transfers it as a high-temperature heat source to the heating station 9. The cold end inlet of the absorption heat pump 10 is connected to the outlet of the heating user 8, the cold end outlet of the absorption heat pump 10 is connected to the inlet of the absorption heat pump 10, and the hot end outlet of the absorption heat pump 10 is connected to the heat source inlet of the heating station 9.

[0040] Among them, the exhaust steam from the low-pressure cylinder 6 of Unit 1 heats the primary heating network heater 13, and the Unit 1 undergoes a high back pressure modification. During winter heating, the unit maintains a high back pressure, with the exhaust steam pressure maintained at 35-40 kPa, heating the return water of the heating network to about 70°C. Because air-cooled units are designed with higher exhaust steam pressure, rotor replacement is not required when modifying them for high back pressure heating, so the cost is lower.

[0041] As the heat source for the peak heater, a higher pressure medium-pressure cylinder exhaust pressure is selected. Steam can be extracted by drilling through the medium-pressure cylinder exhaust pipe and the steam obtained by drilling is input into the peak heater 11 to reheat the circulating water of the heating network to 130°C.

[0042] In this invention, steam performs work in the intermediate-pressure cylinder 1 of Unit 1, then passes through the connecting pipe of the intermediate-low-pressure cylinder of Unit 1 to the low-pressure cylinder 6 of Unit 1 to perform work and drive the generator 7 of Unit 1 to generate electricity. The exhaust steam after performing work in the low-pressure cylinder 6 of Unit 1 undergoes high back-pressure modification, with the exhaust pressure controlled at 35-40 kPa before entering the primary heating network heater 13 to heat the return water of the heating network, raising the return water temperature to approximately 70°C.

[0043] Steam from the intermediate-pressure cylinder 2 of Unit 2, after performing work, travels through the connecting pipe to the low-pressure cylinder 4 of Unit 2, driving the generator 5 of Unit 2 to perform work. Steam is extracted through perforations in the connecting pipe between the intermediate and low-pressure cylinders. The steam flow into the low-pressure cylinder and the peak heater is distributed via regulating valve 3, with the hot water temperature of the heating network as the control variable to meet the supply temperature requirements. The extracted steam enters the peak heater 11 for secondary heating of the heating network circulating water, raising the supply water temperature to 130℃. Then, it travels through the supply pipeline to the heating station 9. Due to the long-distance pipeline, heat loss is significant. An absorption heat pump 10 is used to maintain a relatively high supply water temperature. After passing through the heating station, the water enters the heat user 8. After utilizing the heat, the return water temperature drops to approximately 55℃. The absorption heat pump 10 then further heats the supply water, releasing more heat. After passing through the absorption heat pump 10, the return water temperature drops to 30℃. The booster pump 12 then pressurizes the water and returns it to the primary heating network heater, completing the entire cycle.

[0044] This invention changes the supply and return water temperature of the heating network from the traditional 130 / 70℃ to 130 / 30℃, increasing the temperature difference between the supply and return water. This allows for the recovery of more waste heat from power plants, forming a centralized heating mode that transports waste heat from thermal power plants over long distances with a large temperature difference, significantly improving the transmission capacity of the heating network. The heat source for the primary heating network heater comes from the exhaust steam of the low-pressure cylinder. The heated circulating water then goes to the peak heater, whose heat source comes from the exhaust steam of the medium-pressure cylinder of another unit. The hot water is then supplied to the heating station, and finally to the users. The hot water that users have used is at a temperature of around 55℃. This portion of the water returns to the heating station and is heated by an absorption heat pump to maintain the supply water temperature while further reducing the return water temperature, thus improving the transmission capacity of the heating network.

[0045] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more. In the description of this utility model, "above" or "below" a second feature may include direct contact between the first and second features, or it may include contact between the first and second features not being in direct contact but through another feature between them.

[0046] In the description of this utility model, the terms "above", "over" and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0047] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0048] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

[0050] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A series connection system for air-cooled units adapted to large temperature difference heating, characterized in that, It includes a heating network water circulation pipeline; along the direction of water flow, the heating network water circulation pipeline is sequentially equipped with a primary heating network heater (13), a peak heater (11), a heating station (9), a heating user (8) and an absorption heat pump (10). The hot end inlet of the primary heating network heater (13) is connected to the low-pressure cylinder exhaust, and the hot end inlet of the peak heater (11) is connected to the medium-pressure cylinder exhaust; the cold source inlet of the absorption heat pump (10) is connected to the outlet of the heat user (8), the cold source outlet of the absorption heat pump (10) is connected to the cold end inlet of the primary heating network heater (13), and the heat source outlet of the absorption heat pump (10) is connected to the hot end inlet of the heat station (9).

2. The series connection system for air-cooled units adapted to large temperature difference heating according to claim 1, characterized in that, A booster pump (12) is provided between the cold source outlet of the absorption heat pump (10) and the primary heat network heater (13).

3. The series connection system for air-cooled units adapted to large temperature difference heating according to claim 1, characterized in that, The low-pressure cylinder is the low-pressure cylinder (6) of Unit 1, and the medium-pressure cylinder is the medium-pressure cylinder (2) of Unit 2.

4. The series connection system for air-cooled units adapted to large temperature difference heating according to claim 3, characterized in that, The steam input pipeline of the low-pressure cylinder (6) of Unit 1 is connected to the steam output pipeline of the medium-pressure cylinder (1) of Unit 1.

5. A series connection system for air-cooled units adapted to large temperature difference heating according to claim 4, characterized in that, The low-pressure cylinder (6) of Unit 1 and the medium-pressure cylinder (1) of Unit 1 have both been modified to have high back pressure.

6. A series connection system for air-cooled units adapted to large temperature difference heating according to claim 3, characterized in that, The steam output pipeline of the intermediate pressure cylinder (2) of Unit 2 is simultaneously connected to the hot end inlet of the peak heater (11) and the steam input pipeline of the low pressure cylinder (4) of Unit 2.

7. A series connection system for air-cooled units adapted to large temperature difference heating according to claim 6, characterized in that, A regulating valve (3) is installed on the steam output pipeline of the intermediate pressure cylinder (2) of the No. 2 unit. The regulating valve (3) is located before the hot end inlet of the peak heater (11) and before the steam input pipeline of the low pressure cylinder (4) of the No. 2 unit.

8. A series connection system for air-cooled units adapted to large temperature difference heating according to claim 6, characterized in that, The steam output pipeline of the intermediate pressure cylinder (2) of the No. 2 unit is perforated, and the steam obtained by perforation is connected to the peak heater (11).

9. A series connection system for air-cooled units adapted to large temperature difference heating according to claim 1, characterized in that, The distance between the peak heater (11) and the heating station (9) is ≥20km.

10. A series connection system for air-cooled units adapted to large temperature difference heating according to claim 1, characterized in that, The inlet water temperature of the primary heating network heater (13) is 30°C.

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