Multi-grade low-energy cascade heating method based on comprehensive energy saving of network sources

Abstract

The present invention relates to a multi-grade low-level energy cascade heating method based on comprehensive energy saving of network sources. The heating system includes multiple steam turbine units, multiple heat network condensers, peak heating systems and multiple cooling units. The exhaust steam ports of multiple steam turbine units are connected to the steam inlets of multiple heat network condensers in a one-to-one correspondence. The steam extraction ports of multiple steam turbine units are all connected to the peak heating system, and multiple cooling units are connected to the multiple heat network condensers in a one-to-one correspondence; multiple heat network condensers are connected in series in sequence to form a main heating system, the outlet of the main heating system is connected to the inlet of the peak heating system, and a heat network circulation pump is arranged on the pipeline between the main heating system and the peak heating system. The present invention can control the input levels of the heat network condenser and the peak heating system according to the demand parameters of the heat users, maximize the reasonable matching of the heating steam source parameters and the heat network demand parameters, and reduce the energy consumption cost of heating. In addition, the safety of the heating system is also guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbine heating of thermal power units, and in particular to a multi-grade low-level energy cascade heating method based on network source comprehensive energy saving. Background Art

[0002] With the rapid development of urbanization and the improvement of residents' living standards, the demand for urban heating is growing, and the requirements for heating quality and climate environment are also increasing. However, the proportion of clean heating in northern my country is relatively low, and many areas still use scattered coal in winter, resulting in large primary energy consumption and serious air pollution.

[0003] Cogeneration is a socially recognized clean heating method. If the heating capacity of existing cogeneration units can be fully utilized, industrial waste heat recovery and heating can be done well, energy cascade utilization can be achieved, the shutdown of small coal-fired boilers within the scope of cogeneration heating can be strengthened, and the proportion of cogeneration in urban centralized heating can be increased, it will have huge social benefits in saving coal and reducing emissions. At present, cogeneration accounts for less than 50% of centralized heating in northern cities, which is far from the target requirement of 60% set out in the "Management Measures for Cogeneration" (Development and Reform Energy

[21016] No. 617).

[0004] An important reason restricting the development of clean heating is the lack of overall planning and management in the development of clean heating in cities. The parameter requirements on the heating network side and the heating system design on the heat source side lack coordination, which limits the potential space for waste heat tapping by power plants on the heat source side, resulting in the failure to fully release the cogeneration heating capacity.

[0005] On the conventional heating network side, the design water supply temperature is about 120℃ and the return water temperature is about 70℃. In actual operation, the highest water supply temperature of the heating network is generally about 100-110℃ and the return water temperature is about 50-60℃. The steam extraction parameters of the steam turbine units in power plants are higher than the water supply temperature and the steam source with large-scale steam extraction conditions is the steam exhaust from the intermediate pressure cylinder of the steam turbine. Therefore, power plants generally use the intermediate exhaust steam as the heat source for heating. The extraction pressure is generally 0.25-1.0MPa and the temperature is between 230-380℃. The steam source temperature is generally higher than the demand temperature of the heating network by more than 120-270℃. Such a high temperature difference results in a large waste of useful steam energy.

[0006] On the other hand, the exhaust heat of coal-fired thermal power generation units accounts for more than 50% of the input heat of coal. Conventional system design fails to achieve effective utilization of its heat. Eventually, this part of the exhaust heat is dissipated into the atmosphere in the form of cold source loss. This is a huge waste of energy for low-quality residential heating.

[0007] In order to change the irrational energy consumption of the above-mentioned heating system and tap the potential of low-level energy utilization in the existing power plant stock market, it is necessary to consider the integration of network and source and optimize the design of the heating system of the entire network. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a multi-grade low-grade energy cascade heating method based on network source comprehensive energy saving, which solves the technical problem of low energy grade utilization rate when the steam turbine unit is heating.

[0010] (II) Technical solution

[0011] In order to achieve the above-mentioned object, the multi-grade low-level energy cascade heating system based on network source comprehensive energy saving of the present invention comprises:

[0012] Multiple steam turbine units, multiple heat network condensers, peak heating systems, and multiple cooling units;

[0013] Multiple steam turbine units are operated in sequence with gradually increasing back pressure conditions;

[0014] The exhaust steam outlets of multiple steam turbine units are connected to the steam inlets of multiple heat network condensers in a one-to-one correspondence;

[0015] The steam extraction ports of multiple steam turbine units are connected to the peak heating system;

[0016] Multiple cooling units are connected to multiple heat network condensers in a one-to-one correspondence;

[0017] Multiple heat network condensers are connected in series to form a main heat supply system, the outlet of the main heat supply system is connected to the inlet of the peak heating system; the outlet of the peak heating system is connected to the inlet of the heat user through the heat network water supply pipeline, and the inlet of the main heat supply system is connected to the outlet of the heat user through the heat network return water pipeline, thus forming a heat network;

[0018] A heat network circulation pump is arranged on the pipeline between the outlet of the main heating system and the inlet of the peak heating system.

[0019] Optionally, the multi-grade low-level energy cascade heating system based on network source comprehensive energy saving includes five steam turbine units, the five steam turbine units are respectively a first steam turbine unit, a second steam turbine unit, a third steam turbine unit, a fourth steam turbine unit and a fifth steam turbine unit, and the first steam turbine unit to the fifth steam turbine unit are operated in sequence with gradually increasing back pressure conditions;

[0020] The multi-grade low-level energy cascade heating system based on network source comprehensive energy saving includes five heat network condensers, which are respectively the first heat network condenser, the second heat network condenser, the third heat network condenser, the fourth heat network condenser and the fifth heat network condenser, and the first heat network condenser, the second heat network condenser, the third heat network condenser, the fourth heat network condenser and the fifth heat network condenser are connected in sequence;

[0021] The exhaust steam outlet of the first steam turbine unit is connected to the steam inlet of the first heat network condenser;

[0022] The exhaust steam outlet of the second steam turbine unit is connected to the steam inlet of the second heat network condenser;

[0023] The exhaust steam outlet of the third steam turbine unit is connected to the steam inlet of the condenser of the third heat network;

[0024] The exhaust steam outlet of the fourth steam turbine unit is connected to the steam inlet of the fourth heat network condenser;

[0025] The exhaust steam outlet of the fifth steam turbine unit is connected to the steam inlet of the fifth heat network condenser.

[0026] Optionally, a first condenser bypass pipe is connected in parallel between the cooling water inlet and the cooling water outlet of the first heat network condenser; the cooling water inlet of the first heat network condenser is connected to the outlet of the heat network return water pipe through the first condenser water inlet pipe;

[0027] A second condenser bypass pipe is connected in parallel between the cooling water inlet and cooling water outlet of the second heat network condenser; the cooling water inlet of the second heat network condenser is connected to the outlet of the first condenser outlet pipe through the second condenser water inlet pipe;

[0028] A third condenser bypass pipe is connected in parallel between the cooling water inlet and cooling water outlet of the third heat network condenser; the cooling water inlet of the third heat network condenser is connected to the outlet of the second condenser outlet pipe through the third condenser water inlet pipe;

[0029] A fourth condenser bypass pipeline is connected in parallel between the cooling water inlet and cooling water outlet of the fourth heat network condenser; the cooling water inlet of the fourth heat network condenser is connected to the outlet of the third condenser outlet pipeline through the fourth condenser water inlet pipeline;

[0030] A fifth condenser bypass pipeline is connected in parallel between the cooling water inlet and cooling water outlet of the fifth heat network condenser; the cooling water inlet of the fifth heat network condenser is connected to the outlet of the fourth condenser outlet pipeline through the fifth condenser water inlet pipeline;

[0031] The cooling water outlet of the fifth heat network condenser is connected to the inlet of the peak heating system through the fifth condenser outlet pipeline;

[0032] Valves are provided on the first condenser water inlet pipe (30), the first condenser water outlet pipe (31), the second condenser water inlet pipe (40), the second condenser water outlet pipe (41), the third condenser water inlet pipe (50), the third condenser water outlet pipe (51), the fourth condenser water inlet pipe (60), the fourth condenser water outlet pipe (61), the fifth condenser water inlet pipe (70), and the fifth condenser outlet pipe (71);

[0033] Valves are provided on the first condenser bypass pipe, the second condenser bypass pipe, the third condenser bypass pipe, the fourth condenser bypass pipe and the fifth condenser bypass pipe. The first condenser bypass pipe, the second condenser bypass pipe, the third condenser bypass pipe, the fourth condenser bypass pipe and the fifth condenser bypass pipe are connected in series in sequence to form a main bypass. The inlet of the main bypass is connected to the inlet of the main heating system, and the outlet of the main bypass is connected to the outlet of the main heating system.

[0034] Optionally, the peak heating system comprises a first peak heating system and a second peak heating system connected in series;

[0035] The first peak heating system includes a first small steam turbine and a first small steam turbine exhaust heater, a first heat network heater and a first peak heating bypass pipeline connected in parallel; the first small steam turbine exhaust heater is connected to the exhaust port of the first small steam turbine;

[0036] The second peak heating system includes a second small steam turbine and a second small steam turbine exhaust heater, a second heat network heater and a second peak heating bypass pipeline connected in parallel; the second small steam turbine exhaust heater is connected to the exhaust port of the second small steam turbine;

[0037] The inlet of the first peak heating bypass pipeline is connected to the outlet of the main heating system, the outlet of the first peak heating bypass pipeline is connected to the inlet of the second peak heating bypass pipeline, and the outlet of the second peak heating bypass pipeline is connected to the inlet of the heating network water supply pipeline;

[0038] A first-stage peak heating temperature measuring meter is arranged on the pipeline between the outlet of the first peak heating system (19) and the inlet of the second peak heating system (20);

[0039] The steam extraction ports of the plurality of steam turbine units are all connected to the steam inlets of the first small steam turbine, the first heat network heater, the second small steam turbine and the second heat network heater.

[0040] Optionally, the steam inlet of the first small steam turbine is provided with a first small steam turbine steam inlet control valve;

[0041] The steam inlet of the second small steam turbine is provided with a second small steam turbine steam inlet control valve;

[0042] The first small steam turbine and the second small steam turbine are both connected to the driven equipment.

[0043] Optionally, a return water temperature measuring meter and a return water flow measuring meter are provided on the return water pipeline of the heating network;

[0044] A water supply temperature measuring meter is installed on the water supply pipeline of the heating network;

[0045] An exhaust steam heating temperature measuring meter is arranged on the pipeline between the outlet of the main heating system and the inlet of the peak heating system.

[0046] Optionally, the cooling unit is an air cooling tower, the steam inlet of the air cooling tower is connected to the exhaust steam port of the steam turbine unit, and valves are provided at the steam inlet of the air cooling tower and the steam inlet of the heat network condenser. By controlling the opening and closing of the valves at the steam inlet of the air cooling tower and the steam inlet of the heat network condenser, the input and removal of the air cooling tower can be controlled;

[0047] The cooling unit is a water-cooling tower, the circulating water inlet of the water-cooling tower is connected to the cooling water outlet of the heat network condenser, and the circulating water outlet of the water-cooling tower is connected to the cooling water inlet of the heat network condenser. The circulating water inlet of the water-cooling tower, the circulating water outlet of the water-cooling tower, the cooling water outlet of the heat network condenser and the cooling water outlet of the heat network condenser are all provided with valves. By controlling the opening and closing of the valves at the circulating water inlet of the water-cooling tower, the circulating water outlet of the water-cooling tower, the cooling water outlet of the heat network condenser and the cooling water outlet of the heat network condenser, the water-cooling tower, i.e., the cooling unit, can be controlled to be put into operation and cut off.

[0048] Furthermore, the present invention also provides a multi-grade low-level energy cascade heating method based on network source comprehensive energy saving, which is implemented based on the multi-grade low-level energy cascade heating system based on network source comprehensive energy saving as described above, and the multi-grade low-level energy cascade heating method based on network source comprehensive energy saving includes:

[0049] When the water supply temperature required by the heat user is above the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter is below the exhaust steam set temperature value: the condensers of each level of the heat network are opened, and the bypass pipelines from the first condenser to the fifth condenser are closed; the water in the heat network return water pipeline is heated by the condensers of each level of the heat network in turn, and then heated by the peak heating system to the temperature required by the heat user before being supplied to the heat user;

[0050] When the water supply temperature required by the heat user is above the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter is above the exhaust steam set temperature value; bypass the first-stage heat network condenser, and the heat network circulating water return water enters the subsequent heat network condensers of each level through the first condenser bypass pipe for heating; if the temperature measured by the exhaust steam heating temperature measuring meter is still above the exhaust steam set temperature value, continue to bypass the previous heat network condensers in sequence until the temperature measured by the exhaust steam heating temperature measuring meter is below the exhaust steam set temperature value, and the heat network circulating water return water is heated by the subsequent heat network condensers of each level and then heated by the peak heating system to the temperature required by the heat user before being supplied to the heat user;

[0051] When the water supply temperature required by the heat user is below the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter is lower than the temperature value required by the heat user; the water in the heat network return pipe is heated by the heat network condensers at each level in turn, and then heated by the first peak heating system and the second peak heating system to the temperature required by the heat user before being supplied to the heat user; if the temperature after heating by the first peak heating system is higher than the temperature required by the heat user, the second peak heating system is bypassed;

[0052] When the water supply temperature required by the heat user is below the set exhaust steam temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter exceeds the temperature required by the heat user: first, within the safe load operation range allowed by each steam turbine unit, reduce the power generation load of the first one or more steam turbine units, until the temperature measured by the exhaust steam heating temperature measuring meter drops to the temperature required by the heat user; if after reducing the power generation load, the temperature measured by the exhaust steam heating temperature measuring meter still exceeds the temperature required by the heat user, bypass the first one or more heat network condensers in turn, and the water in the heat network return pipeline is heated to the temperature required by the heat user through the subsequent heat network condensers and peak heating system in turn. Supply heat users.

[0053] Optionally, the driving steam source of the peak heating system is preferentially taken from the extraction ports of the preceding several stages of steam turbine units, and when the pressure of the extraction port of the steam turbine unit is higher than the set pressure value, the first small steam turbine and the first small steam turbine exhaust heater connected in parallel, and / or the second small steam turbine and the second small steam turbine exhaust heater connected in parallel are preferentially turned on; when the steam turbine extraction port pressure is lower than the set pressure value, only the first heating network heater and / or the second heating network heater are turned on.

[0054] Optionally, when a certain steam turbine unit or a heat network condenser fails, the failed heat network condenser or the heat network condenser connected to the failed steam turbine unit is bypassed;

[0055] When the first peak heating system fails, bypassing the first peak heating system;

[0056] When the second peak heating system fails, the second peak heating system is bypassed.

[0057] (III) Beneficial effects

[0058] The present invention aims at large-scale thermal power generating units with a large number of units and a large heating scale. The exhaust steam waste heat of multiple units is recovered step by step, and series heating is adopted in sequence, that is, the original first-level heating system is split into a multi-stage low-energy exhaust steam cascade heating system. This not only effectively reduces the average heating parameters of the heating steam source and reduces the energy consumption cost of heating in the power plant, but also expands the heating capacity of the power plant, and gives full play to the social responsibility of large-scale cogeneration units in assuming large-scale centralized heating and rational utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic diagram of the structure of the multi-grade low-level energy cascade heating system based on network source comprehensive energy saving using an air cooling tower according to the present invention;

[0060] Figure 2 This is a schematic structural diagram of a multi-grade low-level energy cascade heating system based on network source comprehensive energy saving using a water cooling tower according to the present invention.

[0061] [Description of Reference Numerals]

[0062] 1: Heating network water supply pipeline; 2: Heating network return pipeline; 3: First steam turbine unit; 4: Second steam turbine unit; 5: Third steam turbine unit; 6: Fourth steam turbine unit; 7: Fifth steam turbine unit; 8: Heating network circulation pump; 9: Heat user; 10: Cooling unit;

[0063] 11: first heat network condenser; 12: second heat network condenser; 13: third heat network condenser; 14: fourth heat network condenser; 15: fifth heat network condenser;

[0064] 19: first peak heating system; 20: second peak heating system; 21: first small steam turbine; 22: first small steam turbine exhaust heater; 23: first heating network heater; 24: second small steam turbine; 25: second small steam turbine exhaust heater; 26: second heating network heater;

[0065] 30: First heat network condenser water inlet pipeline; 31: First heat network condenser water outlet pipeline; 32: First heat network condenser bypass pipeline; 33: First steam turbine first exhaust steam pipeline; 34: First steam turbine second exhaust steam pipeline; 35: First cooling unit water outlet pipeline; 36: First cooling unit water inlet pipeline;

[0066] 40: Second heat network condenser water inlet pipe; 41: Second heat network condenser water outlet pipe; 42: Second heat network condenser bypass pipe; 43: Second steam turbine first exhaust steam pipe; 44: Second steam turbine second exhaust steam pipe; 45: Second cooling unit water outlet pipe; 46: Second cooling unit water inlet pipe;

[0067] 50: water inlet pipe of the third heat network condenser; 51: water outlet pipe of the third heat network condenser; 52: bypass pipe of the third heat network condenser; 53: first exhaust steam pipe of the third steam turbine; 54: second exhaust steam pipe of the third steam turbine; 55: water outlet pipe of the third cooling unit; 56: water inlet pipe of the third cooling unit;

[0068] 60: the fourth heat network condenser water inlet pipeline; 61: the fourth heat network condenser water outlet pipeline; 62: the fourth heat network condenser bypass pipeline; 63: the fourth steam turbine first exhaust steam pipeline; 64: the fourth steam turbine second exhaust steam pipeline; 65: the fourth cooling unit water outlet pipeline; 66: the fourth cooling unit water inlet pipeline;

[0069] 70: the fifth heat network condenser water inlet pipeline; 71: the fifth heat network condenser water outlet pipeline; 72: the fifth heat network condenser bypass pipeline; 73: the fifth steam turbine first exhaust steam pipeline; 74: the fifth steam turbine second exhaust steam pipeline; 75: the fifth cooling unit water outlet pipeline; 76: the fifth cooling unit water inlet pipeline;

[0070] 81: the first small steam turbine exhaust heating water inlet pipeline; 82: the first peak heating bypass pipeline; 83: the first heating network heating water inlet pipeline; 84: the first small steam turbine exhaust heating water outlet pipeline; 85: the first heating network heating water outlet pipeline; 86: the first small unit steam inlet control valve;

[0071] 91: exhaust steam heating water inlet pipe of the second small steam turbine; 92: second peak heating bypass pipe; 93: second heating network heating water inlet pipe; 94: exhaust steam heating water outlet pipe of the second small steam turbine; 95: second heating network heating water outlet pipe; 96: second small unit steam inlet control valve;

[0072] 101: Return water temperature measuring meter; 102: Supply water temperature measuring meter; 103: Exhaust steam heating temperature measuring meter; 104: First stage peak heating temperature measuring meter; 105: Return water flow measuring meter. DETAILED DESCRIPTION

[0073] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0074] like Figure 1 and Figure 2As shown, in order to solve the above problems, the present invention considers the heating network and the heat source power plant as an integrated whole from the perspective of social heating energy conservation; on the one hand, the heat network side should adopt large temperature difference heating, mixed water heating and other technical measures that can reduce the circulating water return temperature of the heat network, thereby significantly reducing the return water temperature of the heat network; on the other hand, based on the low return water temperature on the external network side, for large-scale thermal power generating units with a large number of units and a large heating scale, the exhaust steam waste heat of multiple units is recovered step by step as the basic heat source of the heat network, and a series heating method is adopted to use the circulating water return water of the heat network as the exhaust steam cooling water of the steam turbine unit, which is heated in turn by the exhaust steam of each group in turn, and the part with insufficient heating is peak heated by high-grade extraction steam.

[0075] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0076] The present invention provides a multi-grade low-level energy cascade heating system based on network source comprehensive energy saving, such as Figure 1 and Figure 2As shown, it includes multiple steam turbine units, multiple heat network condensers, peak heating systems and multiple cooling units, and multiple steam turbine units are operated in turn with gradually increasing back pressure conditions. Among them, the exhaust steam ports of multiple steam turbine units are connected one by one with the steam inlets of multiple heat network condensers, which are used to provide steam for main heating to the heat network condensers. In the heating season, the exhaust steam waste heat of large thermal power generating units is fully utilized to provide heating to users, increase the work and power generation of high-grade extraction steam in the steam turbine, improve the utilization rate of steam, and reduce the useful energy loss of steam. In the non-heating season, the exhaust steam of the steam turbine unit is cooled by the cooling unit. Multiple heat network condensers are connected in series in turn to form a main heating system, and the main heating system is connected in series with the peak heating system. The outlet of the peak heating system can be connected to the inlet of the heat user 9 through the heat network water supply pipeline 1, and the outlet of the heat user 9 can be connected to the inlet of the main heating system through the heat network return water pipeline 2, thereby forming a heat network that provides heat to the heat user 9. A heat network circulation pump 8 is arranged on the pipeline between the outlet of the main heating system and the inlet of the peak heating system, which is used to drive the water on the heat network to circulate. The steam extraction port of the steam turbine unit is connected to the steam inlet of the peak heating system, and the circulating water in the heat network is further heated by the peak heating system to ensure the normal heating of the system. The cooling unit is used to cool the exhaust steam of the steam turbine unit. For the air cooling tower, the cooling unit is connected to the exhaust steam port of the steam turbine unit. For the water cooling tower, the cooling unit is connected to the inlet and outlet water pipes of the heat network condenser. The present invention aims at large-scale thermal power generating units with a large number of units and a large heating scale, recovers the exhaust steam waste heat of multiple units step by step, and adopts series heating in turn, that is, the original first-level heating system is split into a multi-stage low-potential exhaust steam cascade heating system, which effectively reduces the average heating parameters of the heating steam source, reduces the energy consumption cost of the power plant, expands the heating capacity of the power plant, and gives full play to the social responsibility of large-scale cogeneration units in assuming large-scale centralized heating and rational use of resources.

[0077] See also Figure 1 and Figure 2The multi-grade low-level energy cascade heating system based on comprehensive network source energy conservation includes five steam turbine units, which are the first steam turbine unit 3, the second steam turbine unit 4, the third steam turbine unit 5, the fourth steam turbine unit 6 and the fifth steam turbine unit 7. The first steam turbine unit 3 to the fifth steam turbine unit 7 are operated in sequence with gradually increasing back pressure conditions. The multi-grade low-level energy cascade heating system based on comprehensive network source energy conservation includes five heat network condensers, which are the first heat network condenser 11, the second heat network condenser 12, the third heat network condenser 13, the fourth heat network condenser 14 and the fifth heat network condenser 15. The first heat network condenser 11, the second heat network condenser 12, the third heat network condenser 13, the fourth heat network condenser 14 and the fifth heat network condenser 15 are connected in sequence. The exhaust steam port of the first steam turbine unit 3 is connected to the steam inlet of the first heat network condenser 11, the exhaust steam port of the second steam turbine unit 4 is connected to the steam inlet of the second heat network condenser 12, the exhaust steam port of the third steam turbine unit 5 is connected to the steam inlet of the third heat network condenser 13, the exhaust steam port of the fourth steam turbine unit 6 is connected to the steam inlet of the fourth heat network condenser 14, and the exhaust steam port of the fifth steam turbine unit 7 is connected to the steam inlet of the fifth heat network condenser 15. The first steam turbine unit 3 to the fifth steam turbine unit 7 are operated in sequence with the back pressure condition increasing step by step.

[0078] Further, the cooling water inlet of the first heat network condenser 11 is connected to the first condenser water inlet pipe 30, the cooling water outlet of the first heat network condenser 11 is connected to the first condenser water outlet pipe 31, and a first condenser bypass pipe 32 is connected in parallel between the cooling water inlet and cooling water outlet of the first heat network condenser 11. The cooling water inlet of the first heat network condenser 11 is connected to the outlet of the heat user 9 through the first condenser water inlet pipe 30 and the heat network return water pipe 2.

[0079] The cooling water inlet of the second heat network condenser 12 is connected to the second condenser water inlet pipe 40, the cooling water outlet of the second heat network condenser 4 is connected to the second condenser water outlet pipe 41, and a second condenser bypass pipe 42 is connected in parallel between the cooling water inlet and cooling water outlet of the second heat network condenser 12. The cooling water inlet of the second heat network condenser 12 is connected to the cooling water outlet of the first heat network condenser 11 through the second condenser water inlet pipe 40 and the first condenser water outlet pipe 31; the cooling water inlet of the second heat network condenser 12 can be connected to the outlet of the heat user 9 through the first condenser bypass pipe 32 and the heat network return water pipe 2.

[0080] The cooling water inlet of the third heat network condenser 13 is connected to the third condenser water inlet pipe 50, the cooling water outlet of the third heat network condenser 13 is connected to the third condenser water outlet pipe 51, and a third condenser bypass pipe 52 is connected in parallel between the cooling water inlet and cooling water outlet of the third heat network condenser. The third heat network condenser 13 is connected to the second heat network condenser 12 through the third condenser water inlet pipe 50 and the second condenser water outlet pipe 41; the third heat network condenser 13 can be connected to the first heat network condenser 11 through the second condenser bypass pipe 42, and can be connected to the outlet of the heat user 9 through the second condenser bypass pipe 42, the first condenser bypass pipe 32 and the heat network return water pipe 2.

[0081] The cooling water inlet of the fourth heat network condenser 14 is connected to the fourth condenser water inlet pipe 60; the cooling water outlet of the fourth heat network condenser 14 is connected to the fourth condenser water outlet pipe 61; a fourth condenser bypass pipe 62 is connected in parallel between the cooling water inlet and the cooling water outlet of the fourth heat network condenser; the fourth heat network condenser 14 is connected to the third heat network condenser 13 through the fourth condenser water inlet pipe 60 and the third condenser water outlet pipe 51; the fourth heat network condenser 14 can be connected to the second heat network condenser 12 through the third condenser bypass pipe 52, can be connected to the first heat network condenser 11 through the third condenser bypass pipe 52 and the second condenser bypass pipe 42, and can be connected to the outlet of the heat user 9 through the third condenser bypass pipe 52, the second condenser bypass pipe 42, the first condenser bypass pipe 32 and the heat network return water pipe 2.

[0082] The cooling water inlet of the fifth heat network condenser 15 is connected to the fifth condenser water inlet pipeline 70; the cooling water outlet of the fifth heat network condenser 15 is connected to the fifth condenser water outlet pipeline 71; a fifth condenser bypass pipeline 72 is connected in parallel between the cooling water inlet and cooling water outlet of the fifth heat network condenser; the fifth heat network condenser 15 is connected to the fourth heat network condenser 14 through the fifth condenser water inlet pipeline 70 and the fourth condenser water outlet pipeline 61; the fifth heat network condenser 15 can be connected to the fourth condenser bypass pipeline 62 The third heat network condenser 13 can be connected to the second heat network condenser 12 through the fourth condenser bypass pipe 62 and the third condenser bypass pipe 52, can be connected to the first heat network condenser 11 through the fourth condenser bypass pipe 62, the third condenser bypass pipe 52, and the second condenser bypass pipe 42, and can be connected to the outlet of the heat user 9 through the fourth condenser bypass pipe 62, the third condenser bypass pipe 52, the second condenser bypass pipe 42, the first condenser bypass pipe 32 and the heat network return water pipe 2.

[0083] The fifth heat network condenser 15 can be connected to the inlet of the peak heating system through the fifth condenser outlet pipeline 71. The fourth heat network condenser 14 can be connected to the inlet of the peak heating system through the fourth condenser outlet pipeline 61 and the fifth condenser bypass pipeline 72. The third heat network condenser 13 can be connected to the inlet of the peak heating system through the third condenser outlet pipeline 51, the fourth condenser bypass pipeline 62 and the fifth condenser bypass pipeline 72. The second heat network condenser 12 can be connected to the inlet of the peak heating system through the second condenser outlet pipeline 41, the third condenser bypass pipeline 52, the fourth condenser bypass pipeline 62 and the fifth condenser bypass pipeline 72. The first heat network condenser 11 can be connected to the inlet of the peak heating system through the first condenser outlet pipeline 31, the second condenser bypass pipeline 42, the third condenser bypass pipeline 52, the fourth condenser bypass pipeline 62 and the fifth condenser bypass pipeline 72.

[0084] like Figure 1 and Figure 2 As shown, the peak heating system includes a first peak heating system 19 and a second peak heating system 20 connected in series. The first peak heating system 19 includes a first small steam turbine 21 and a first small steam turbine exhaust heater 22, a first heat network heater 23 and a first peak heating bypass pipe 82 connected in parallel, and the first small steam turbine exhaust heater 22 is connected to the exhaust port of the first small steam turbine 21. The second peak heating system 20 includes a second small steam turbine 24 and a second small steam turbine exhaust heater 25, a second heat network heater 26 and a second peak heating bypass pipe 92 connected in parallel, and the second small steam turbine exhaust heater 25 is connected to the exhaust port of the second small steam turbine 24. The inlet of the first peak heating bypass pipe 82 is connected to the outlet of the main heating system, the outlet of the first peak heating bypass pipe 82 is connected to the inlet of the second peak heating bypass pipe 92, and the outlet of the second peak heating bypass pipe 92 is connected to the inlet of the heat network water supply pipeline 1. A first-stage peak heating temperature measuring meter 104 is arranged on the pipeline between the outlet of the first peak heating system (19) and the inlet of the second peak heating system (20). The steam extraction ports of the plurality of steam turbine units are all connected to the steam inlets of the first small steam turbine 21, the first heat network heater 23, the second small steam turbine 24 and the second heat network heater 26. The first small steam turbine 21 and the second small steam turbine 24 are connected to the driven equipment through a coupling. The driven equipment includes a water pump, a fan, an electric motor, etc. The first small steam turbine 21 and the second small steam turbine 24 drive the water pump, the fan or the electric motor to operate by generating electricity. Specifically, the inlet of the first small steam turbine exhaust heater 22 is connected to the first small steam turbine exhaust heating water inlet pipeline 81, and the outlet of the first small steam turbine exhaust heater 22 is connected to the first small steam turbine exhaust heating water outlet pipeline. The inlet of the first heat network heater 23 is connected to the first heat network heating water inlet pipeline 83, and the outlet of the first heat network heater 23 is connected to the first heat network heating water outlet pipeline 85.

[0085] The inlet of the first peak heating system 19 is connected to the fifth heat network condenser 15 through the outlet pipe 71 of the fifth condenser; the outlet of the first peak heating system 19 is connected to the inlet of the second peak heating system 20; the outlet of the first peak heating system 19 can be connected to the inlet of the heat user 9 through the second peak heating bypass 92 and the heat network water supply pipeline 1.

[0086] The inlet of the second peak heating system 20 is connected to the outlet of the first peak heating system 19; the inlet of the second peak heating system 20 can be connected to the outlet of the fifth heating network condenser 15 through the first peak heating bypass 82; the outlet of the second peak heating system 20 can be connected to the inlet of the heat user 9 through the heating network water supply pipeline 1.

[0087] The outlet of the fifth heating network condenser 15 can be connected to the inlet of the heat user 9 through the first peak heating bypass 82, the second peak heating bypass 92 and the heating network water supply pipeline 1. The outlet of the fourth heating network condenser 14 can be connected to the inlet of the heat user 9 through the fifth condenser bypass pipeline 72, the first peak heating bypass 82, the second peak heating bypass 92 and the heating network water supply pipeline 1. The outlet of the third heating network condenser 13 can be connected to the inlet of the heat user 9 through the fourth condenser bypass pipeline 62, the fifth condenser bypass pipeline 72, the first peak heating bypass 82, the second peak heating bypass 92 and the heating network water supply pipeline 1. The outlet of the second heating network condenser 12 can be connected to the inlet of the heat user 9 through the third condenser bypass pipeline 52, the fourth condenser bypass pipeline 62, the fifth condenser bypass pipeline 72, the first peak heating bypass 82, the second peak heating bypass 92 and the heating network water supply pipeline 1. The outlet of the first heat network condenser 11 can be connected to the inlet of the heat user 9 through the second condenser bypass pipeline 42, the third condenser bypass pipeline 52, the fourth condenser bypass pipeline 62, the fifth condenser bypass pipeline 72, the first peak heating bypass 82, the second peak heating bypass 92 and the heat network water supply pipeline 1. The heat network return water pipeline 2 can be connected to the inlet of the first peak heating system 19 through the first condenser bypass pipeline 32, the second condenser bypass pipeline 42, the third condenser bypass pipeline 52, the fourth condenser bypass pipeline 62 and the fifth condenser bypass pipeline 72.

[0088] See also Figure 1 and Figure 2 The steam inlet of the first small steam turbine 21 is provided with a first small steam turbine steam inlet control valve 86, and the pipeline between the first small steam turbine exhaust heater 22 and the exhaust port of the first small steam turbine 21 is provided with a first heat network heating steam inlet control valve. The steam inlet of the second small steam turbine 24 is provided with a second small steam turbine steam inlet control valve 96, and the pipeline between the second small steam turbine exhaust heater 25 and the exhaust port of the second small steam turbine 24 is provided with a second heat network heating steam inlet control valve.

[0089] See also Figure 1 and Figure 2 , a return water temperature measuring meter 101 and a return water flow measuring meter 105 are provided on the return water pipe 2 of the heat network. A water supply temperature measuring meter 102 is provided on the pipe between the peak heating system and the heat user 9. A steam exhaust heating temperature measuring meter 103 is provided on the pipe between the outlet of the main heating system and the inlet of the peak heating system. A first-stage peak heating temperature measuring meter 104 is provided on the pipe between the first peak heating system 19 and the second peak heating system 20. The pipe connections inside the first peak heating system 19 and the second peak heating system 20 are as follows: Figure 1 As shown, the inlet of the first small steam turbine exhaust heater 22 is connected to the first small steam turbine exhaust heating water inlet pipe 81, and the outlet is connected to the first small steam turbine exhaust heating water outlet pipe 84; the inlet of the first heat network heater 23 is connected to the first heat network heating water inlet pipe 83, and the outlet is connected to the first heat network heating water outlet pipe 85; the inlet of the second small steam turbine exhaust heater 25 is connected to the second small steam turbine exhaust heating water inlet pipe 91, and the outlet is connected to the second small steam turbine exhaust heating water outlet pipe 94; the inlet of the second heat network heater 26 is connected to the second heat network heating water inlet pipe 93, and the outlet is connected to the second heat network heating water outlet pipe. Control valves are provided on the first heating network condenser water inlet pipeline 30 to the fifth heating network condenser water inlet pipeline 70, the first heating network condenser water outlet pipeline 31 to the fifth heating network condenser water outlet pipeline 71, the first heating network condenser bypass pipeline 32 to the fifth heating network condenser bypass pipeline 72, the first small steam turbine exhaust steam heating water inlet pipeline 81, the second small steam turbine exhaust steam heating water inlet pipeline 91, the first small steam turbine exhaust steam heating water outlet pipeline 84, the second small steam turbine exhaust steam heating water outlet pipeline 94, the first heating network heating water inlet pipeline 83, the first heating network heating water outlet pipeline 85, the second heating network heating water inlet pipeline 93, the second heating network heating water outlet pipeline 95, the first peak heating bypass pipeline 82, and the second peak heating bypass pipeline 92.

[0090] The cooling unit 10 is an air-cooling tower, the steam inlet of the air-cooling tower is connected to the exhaust steam port of the steam turbine unit, and valves are provided at the steam inlet of the air-cooling tower and the steam inlet of the heat network condenser. By controlling the opening and closing of the valve at the steam inlet of the air-cooling tower and the valve at the steam inlet of the heat network condenser, the input and removal of the air-cooling tower can be controlled; the cooling unit 10 is a water-cooling tower, the circulating water inlet of the water-cooling tower is connected to the cooling water outlet of the heat network condenser, and the circulating water outlet of the water-cooling tower is connected to the cooling water inlet of the heat network condenser. The circulating water inlet of the water-cooling tower, the circulating water outlet of the water-cooling tower, the cooling water outlet of the heat network condenser and the cooling water outlet of the heat network condenser are all provided with valves. By controlling the opening and closing of the valves at the circulating water inlet of the water-cooling tower, the circulating water outlet of the water-cooling tower, the cooling water outlet of the heat network condenser and the cooling water outlet of the heat network condenser, the input and removal of the water-cooling tower, i.e., the cooling unit 10, can be controlled. Specifically, for the air cooling tower, the first steam turbine unit 3 is connected to the air cooling tower through the first steam turbine first exhaust steam pipeline 33, and the first steam turbine unit 3 is connected to the steam inlet of the first heat network condenser 11 through the first steam turbine second exhaust steam pipeline 34; the second steam turbine unit 4 is connected to the air cooling tower through the second steam turbine first exhaust steam pipeline 43, and the second steam turbine unit 4 is connected to the steam inlet of the second heat network condenser 12 through the second steam turbine second exhaust steam pipeline 44; the third steam turbine unit 5 is connected to the air cooling tower through the third steam turbine first exhaust steam pipeline 53, and the third steam turbine unit The steam inlet of the third heat network condenser 13 is connected to the fourth steam turbine unit 6 through the third steam turbine second exhaust steam pipeline 54; the fourth steam turbine unit 6 is connected to the air cooling tower through the fourth steam turbine first exhaust steam pipeline 63, and the fourth steam turbine unit 6 is connected to the steam inlet of the fourth heat network condenser 14 through the fourth steam turbine second exhaust steam pipeline 64; the fifth steam turbine unit 7 is connected to the air cooling tower through the fifth steam turbine first exhaust steam pipeline 73, and the fifth steam turbine unit 7 is connected to the steam inlet of the fifth heat network condenser 15 through the fifth steam turbine second exhaust steam pipeline 74, and each pipeline is provided with a valve. For the water cooling tower, the first heat network condenser 11 is connected to the water cooling tower through the first cooling unit water outlet pipe 35 and the first cooling unit water inlet pipe 36 in a circulation manner, the second heat network condenser 12 is connected to the water cooling tower through the second cooling unit water outlet pipe 45 and the second cooling unit water inlet pipe 46 in a circulation manner, the third heat network condenser 13 is connected to the water cooling tower through the third cooling unit water outlet pipe 55 and the third cooling unit water inlet pipe 56 in a circulation manner, the fourth heat network condenser 14 is connected to the water cooling tower through the fourth cooling unit water outlet pipe 65 and the fourth cooling unit water inlet pipe 66 in a circulation manner, the fifth heat network condenser 15 is connected to the water cooling tower through the fifth cooling unit water outlet pipe 75 and the fifth cooling unit water inlet pipe 76 in a circulation manner, and a valve is provided on each pipe.

[0091] Furthermore, the present invention also provides a multi-grade low-level energy cascade heating method based on network source comprehensive energy saving, which is implemented based on the above multi-grade low-level energy cascade heating system based on network source comprehensive energy saving. The multi-grade low-level energy cascade heating method based on network source comprehensive energy saving complies with the following functional relationship:

[0092]

[0093] In the formula, Respectively represent the opening and closing status of the valves of the inlet and outlet water pipes and bypass pipes of the condensers of the first, second, third, fourth and fifth heat networks; Represents the opening and closing status of the valves of the inlet and outlet pipes and bypass pipes of the first peak heating system and the second peak heating system. When i=0, it means that the valve on this pipe is closed; when i=1, it means that this valve is open.

[0094] T、t g ,t f , t1, t2 represent the exhaust steam set temperature, the heating network water supply demand temperature, the heating network circulating water temperature after turbine exhaust steam heating, the first peak heating temperature, and the second peak heating temperature respectively; P1, P2, P3, P4, P5 represent the power generation load of the first, second, third, fourth, and fifth steam turbine units respectively; p6, p7 represent the power of the first small steam turbine and the second small steam turbine respectively.

[0095] The combination of valves representing each pipeline, i.e., the input and number of stages of the heat network condenser and the peak heating system, depends on the demand temperature of the heat user, the heat network circulating water temperature after the exhaust steam of the steam turbine is heated, the heat network circulating water temperature after the peak heating system is heated, the safe exhaust steam set temperature value, and the power generation load of each steam turbine unit. According to the safe operating back pressure condition of the steam turbine generator unit, under different load conditions, there is a corresponding safe exhaust steam set temperature. During operation, it is necessary to pay close attention to the reading of the exhaust steam heating temperature measuring meter 103.

[0096] When the water supply temperature demand of the heating network is above the exhaust steam setting temperature, and the temperature measured by the exhaust steam heating temperature measuring meter 103 is below the exhaust steam setting temperature: the valves of the water inlet and outlet pipes of the condensers of the heating network at all levels are opened, the valves of the bypass pipes of the condensers of the heating network at all levels and the cooling units of the steam turbine units at all levels are closed, and the circulating water return water of the heating network is heated in turn by the condensers of the heating network at all levels and then sent to the peak heating system, and the circulating water supply temperature of the heating network is heated to the temperature required by the heat user 9 before being supplied to the outside. The exhaust steam setting temperature is preferably 80°C.

[0097] When the water supply temperature required by the heat user (9) is above the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter (103) is above the exhaust steam set temperature value; the first-stage heat network condenser is bypassed, and the heat network circulating water return water enters the subsequent heat network condensers of each stage through the first condenser bypass pipe 32 for heating; if the temperature measured by the exhaust steam heating temperature measuring meter 103 is still above the exhaust steam set temperature, the previous heat network condensers of several stages are bypassed in sequence until the temperature measured by the exhaust steam heating temperature measuring meter 103 is below the exhaust steam set temperature. The heat network circulating water return water is heated by the subsequent heat network condensers of each stage and then heated by the peak heating system to the temperature required by the heat user 9 before being supplied to the heat user 9. The cooling unit of the steam turbine unit corresponding to the opened heat network condenser bypass pipe is turned on. At the same time, the air cooling tower: the valve of the corresponding steam turbine unit's first exhaust steam pipe is closed and the valve of the second exhaust steam pipe is opened; the water cooling tower: the valve of the corresponding steam turbine unit's cooling water inlet and outlet pipe is opened, and the valve of the heat network condenser's inlet and outlet water pipe is closed.

[0098] When the demand for the water supply temperature of the heating network is below the set temperature of the exhaust steam, and the temperature measured by the exhaust steam heating temperature measuring meter 103 is lower than the demand temperature for the water supply of the heating network, the return water of the circulating water of the heating network is heated in sequence by the condensers of each level of the heating network, and then directly heated to the required temperature of the heat user 9 by the first peak heating system 19 and the second peak heating system 20 before being supplied to the outside. When the temperature of the circulating water of the heating network after being heated by the first peak heating system 19 is greater than the demand for the water supply temperature of the heating network, the second peak heating system 20 is bypassed, and the circulating water of the heating network after being heated by the first peak heating system 19 is directly supplied to the heat user 9.

[0099] When the demand for water supply temperature of the heating network is below the set temperature of the exhaust steam, and the temperature measured by the exhaust steam heating temperature measuring meter 103 exceeds the demand temperature for water supply of the heating network: first, within the allowable safe load operation range of each steam turbine unit, reduce the power generation load of the first few stages of steam turbines until the temperature measured by the exhaust steam heating temperature measuring meter 103 drops to the temperature required by the heat user 9; when the total thermal load of the exhaust steam of each steam turbine unit after reducing the power generation load can increase the circulating water temperature of the heating network to the demand temperature for water supply of the heating network, bypass the first peak heating system 19 and the second peak heating system 20, and the return water of the circulating water of the heating network is heated in turn by the condensers of each stage of the heating network and then supplied to the outside. When the total heat load of exhaust steam from each steam turbine unit after reducing the power generation load can raise the temperature of the heat network circulating water but still exceeds the required temperature of the heat network water supply, the first one or several heat network condensers are bypassed first. When the exhaust steam heat of the steam turbine units corresponding to the bypassed heat network condenser is deducted, and the total heat load of exhaust steam from the remaining units can raise the temperature of the heat network circulating water to the heat network water supply temperature, the heat network circulating water return water passes through the bypass pipelines of the first several heat network condensers in turn, directly enters the heat network condensers of the following levels, and then is sent to the peak heating system to heat the heat network circulating water supply temperature to the required temperature of the heat user 9 before supplying it to the outside. The cooling unit of the steam turbine unit with the opened heat network condenser bypass pipeline is turned on.

[0100] Furthermore, the driving steam source of the peak heating system is preferentially taken from the steam extraction ports of the preceding steam turbine units, and when the steam extraction port pressure of the steam turbine unit is higher than the set pressure value, the first small steam turbine 21 and the first small steam turbine exhaust heater 22 connected in parallel, and / or the second small steam turbine 24 and the second small steam turbine exhaust heater 25 connected in parallel are preferentially turned on; when the steam turbine steam extraction port pressure is lower than the set pressure value, only the first heat network heater 23 and / or the second heat network heater 26 are turned on. Specifically, the driving steam source of the peak heating system is preferentially taken from the steam extraction ports of the preceding steam turbine units, and when the steam turbine steam extraction port pressure is relatively high, such as above 0.4MPa, the small steam turbine unit and its exhaust heater system are preferentially turned on, and then the heat network heating system is considered to be turned on. When the steam turbine steam extraction port pressure is relatively low, such as below 0.4MPa, the small steam turbine unit and its exhaust heater system can be turned off, and only the heat network heating system is turned on. When a steam turbine unit or a heat network condenser fails, the failed heat network condenser or the heat network condenser connected to the failed steam turbine unit is bypassed; when the first peak heating system 19 fails, the first peak heating system 19 is bypassed; when the second peak heating system 20 fails, the second peak heating system 20 is bypassed, and the heat network water supply system maintains normal heat exchange requirements.

[0101] The present invention takes into account the network source heating parameters and system design in a comprehensive manner, maximizes the potential of low-level energy utilization space in the existing cogeneration unit stock market, realizes the full recovery and utilization of low-level energy exhaust steam of each level of the unit, effectively reduces the average steam source parameters of heating, reduces the energy consumption cost of heating, and realizes the effective replacement of high-energy-consuming coal-fired boilers. It is of great significance to promote the rational utilization of social resources, promote the healthy development of the cogeneration industry, increase the proportion of clean heating in the north, and solve the serious air pollution during the winter heating period in northern my country.

[0102] It should be noted that the number of steam turbine units, the number of recycled exhaust steam and extraction steam stages, and temperature boundary parameters described in the present invention are only for the purpose of more clearly illustrating the design concept and beneficial effects of the system, and are not limiting.

[0103] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0104] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0105] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0106] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0107] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A multi-grade low-level energy cascade heating method based on network source comprehensive energy saving, characterized by: The multi-grade low-level energy cascade heating method based on network source comprehensive energy saving is implemented based on a multi-grade low-level energy cascade heating system based on network source comprehensive energy saving, and the multi-grade low-level energy cascade heating system based on network source comprehensive energy saving includes: multiple steam turbine units, multiple heat network condensers, peak heating systems and multiple cooling units; Multiple steam turbine units are operated in sequence with gradually increasing back pressure conditions; The exhaust steam outlets of multiple steam turbine units are connected to the steam inlets of multiple heat network condensers in a one-to-one correspondence; The steam extraction ports of multiple steam turbine units are connected to the peak heating system; The plurality of cooling units (10) are connected to the plurality of heat network condensers in a one-to-one correspondence; A plurality of heat network condensers are sequentially connected in series to form a main heat supply system, and the outlet of the main heat supply system is connected to the inlet of the peak heating system; the outlet of the peak heating system is connected to the inlet of the heat user (9) through a heat network water supply pipeline (1), and the inlet of the main heat supply system is connected to the outlet of the heat user (9) through a heat network return water pipeline (2), thereby forming a heat network; A heat network circulation pump (8) is provided on the pipeline between the outlet of the main heating system and the inlet of the peak heating system, and an exhaust steam heating temperature measuring meter (103) is provided on the pipeline between the outlet of the main heating system and the inlet of the peak heating system; The multi-grade low-level energy cascade heating system based on network source comprehensive energy saving comprises five steam turbine units, the five steam turbine units are respectively a first steam turbine unit (3), a second steam turbine unit (4), a third steam turbine unit (5), a fourth steam turbine unit (6) and a fifth steam turbine unit (7), the first steam turbine unit (3) to the fifth steam turbine unit (7) are operated in sequence under step-by-step increasing back pressure conditions; The multi-grade low-level energy cascade heating system based on network source comprehensive energy saving comprises five heat network condensers, the five heat network condensers are respectively a first heat network condenser (11), a second heat network condenser (12), a third heat network condenser (13), a fourth heat network condenser (14) and a fifth heat network condenser (15), the first heat network condenser (11), the second heat network condenser (12), the third heat network condenser (13), the fourth heat network condenser (14) and the fifth heat network condenser (15) are connected in sequence; The exhaust steam outlet of the first steam turbine unit (3) is connected to the steam inlet of the first heat network condenser (11); The exhaust steam outlet of the second steam turbine unit (4) is connected to the steam inlet of the second heat network condenser (12); The exhaust steam outlet of the third steam turbine unit (5) is connected to the steam inlet of the third heat network condenser (13); The exhaust steam outlet of the fourth steam turbine unit (6) is connected to the steam inlet of the fourth heat network condenser (14); The exhaust steam outlet of the fifth steam turbine unit (7) is connected to the steam inlet of the fifth heat network condenser (15); A first condenser bypass pipe (32) is connected in parallel between the cooling water inlet and the cooling water outlet of the first heat network condenser (11); the cooling water inlet of the first heat network condenser (11) is connected to the outlet of the heat network return water pipe (2) through the first condenser water inlet pipe (30); A second condenser bypass pipe (42) is connected in parallel between the cooling water inlet and cooling water outlet of the second heat network condenser (12); the cooling water inlet of the second heat network condenser (12) is connected to the outlet of the first condenser outlet pipe (31) via the second condenser water inlet pipe (40); A third condenser bypass pipe (52) is connected in parallel between the cooling water inlet and cooling water outlet of the third heat network condenser (13); the cooling water inlet of the third heat network condenser (13) is connected to the outlet of the second condenser outlet pipe (41) via the third condenser water inlet pipe (50); A fourth condenser bypass pipe (62) is connected in parallel between the cooling water inlet and cooling water outlet of the fourth heat network condenser (14); the cooling water inlet (14) of the fourth heat network condenser is connected to the outlet of the third condenser outlet pipe (51) via the fourth condenser water inlet pipe (60); A fifth condenser bypass pipe (72) is connected in parallel between the cooling water inlet and cooling water outlet of the fifth heat network condenser (15); the cooling water inlet of the fifth heat network condenser (15) is connected to the outlet of the fourth condenser outlet pipe (61) via the fifth condenser water inlet pipe (70); The cooling water outlet of the fifth heat network condenser (15) is connected to the inlet of the peak heating system through the fifth condenser outlet pipeline (71); Valves are provided on the first condenser water inlet pipe (30), the first condenser water outlet pipe (31), the second condenser water inlet pipe (40), the second condenser water outlet pipe (41), the third condenser water inlet pipe (50), the third condenser water outlet pipe (51), the fourth condenser water inlet pipe (60), the fourth condenser water outlet pipe (61), the fifth condenser water inlet pipe (70), and the fifth condenser outlet pipe (71); The first condenser bypass pipe (32), the second condenser bypass pipe (42), the third condenser bypass pipe (52), the fourth condenser bypass pipe (62) and the fifth condenser bypass pipe (72) are all provided with valves; the first condenser bypass pipe (32), the second condenser bypass pipe (42), the third condenser bypass pipe (52), the fourth condenser bypass pipe (62) and the fifth condenser bypass pipe (72) are sequentially connected in series to form a main bypass; the inlet of the main bypass is connected to the inlet of the main heating system, and the outlet of the main bypass is connected to the outlet of the main heating system; The peak heating system comprises a first peak heating system (19) and a second peak heating system (20) connected in series; The first peak heating system (19) comprises a first small steam turbine (21) and a first small steam turbine exhaust heater (22), a first heat network heater (23) and a first peak heating bypass pipeline (82) connected in parallel; the first small steam turbine exhaust heater (22) is connected to the exhaust port of the first small steam turbine (21); The second peak heating system (20) comprises a second small steam turbine (24) and a second small steam turbine exhaust heater (25), a second heat network heater (26) and a second peak heating bypass pipeline (92) connected in parallel; the second small steam turbine exhaust heater (25) is connected to the exhaust port of the second small steam turbine (24); The inlet of the first peak heating bypass pipe (82) is connected to the outlet of the main heating system, the outlet of the first peak heating bypass pipe (82) is connected to the inlet of the second peak heating bypass pipe (92), and the outlet of the second peak heating bypass pipe (92) is connected to the inlet of the heating network water supply pipeline (1); A first-stage peak heating temperature measuring meter (104) is provided on the pipeline between the outlet of the first peak heating system (19) and the inlet of the second peak heating system (20); The steam extraction ports of the plurality of steam turbine units are all connected to the steam inlets of the first small steam turbine (21), the first heat network heater (23), the second small steam turbine (24) and the second heat network heater (26); A first small steam turbine steam inlet control valve (86) is provided at the steam inlet of the first small steam turbine (21); A second small steam turbine steam inlet control valve (96) is provided at the steam inlet of the second small steam turbine (24); The first small steam turbine (21) and the second small steam turbine (24) are both connected to the driven equipment; The multi-grade low-level energy cascade heating method based on network source comprehensive energy saving includes: When the water supply temperature required by the heat user (9) is above the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter (103) is below the exhaust steam set temperature value: the heat network condensers of each level are opened, and the first condenser bypass pipeline (32) to the fifth condenser bypass pipeline (72) are closed; the water in the heat network return water pipeline (2) is heated by the heat network condensers of each level in sequence, and then heated by the peak heating system to the temperature required by the heat user (9) before being supplied to the heat user (9); When the water supply temperature required by the heat user (9) is above the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter (103) is above the exhaust steam set temperature value; the first-stage heat network condenser is bypassed, and the heat network circulating water return water enters the subsequent heat network condensers of each stage through the first condenser bypass pipe (32) for heating; if the temperature measured by the exhaust steam heating temperature measuring meter (103) is still above the exhaust steam set temperature value, the previous heat network condensers are bypassed in sequence until the temperature measured by the exhaust steam heating temperature measuring meter (103) is below the exhaust steam set temperature value, and the heat network circulating water return water is heated by the subsequent heat network condensers of each stage and then heated by the peak heating system to the temperature required by the heat user (9) before being supplied to the heat user (9); When the water supply temperature required by the heat user (9) is below the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter (103) is lower than the temperature required by the heat user (9); the water in the heat network return water pipeline (2) is heated by each level of the heat network condenser in sequence, and then heated by the first peak heating system (19) and the second peak heating system (20) to the temperature required by the heat user (9) before being supplied to the heat user (9); if the temperature after heating by the first peak heating system (19) is higher than the temperature required by the heat user (9), the second peak heating system (20) is bypassed; When the water supply temperature required by the heat user (9) is below the exhaust steam set temperature value, and the temperature measured by the exhaust steam heating temperature measuring meter (103) exceeds the temperature required by the heat user (9): first, within the safe load operation range allowed by each steam turbine unit, reduce the power generation load of the first one or more steam turbine units until the temperature measured by the exhaust steam heating temperature measuring meter (103) drops to the temperature required by the heat user (9); if after reducing the power generation load, the temperature measured by the exhaust steam heating temperature measuring meter (103) still exceeds the temperature required by the heat user (9), bypass the first one or more heat network condensers in turn, and the water in the heat network return water pipeline (2) is heated to the temperature required by the heat user (9) by the subsequent heat network condensers and the peak heating system in turn, and then supplied to the heat user (9).

2. The multi-grade low-level energy cascade heating method based on network source comprehensive energy saving as claimed in claim 1, characterized in that: A return water temperature measuring meter (101) and a return water flow measuring meter (105) are provided on the heat network return water pipeline (2); A water supply temperature measuring meter (102) is provided on the heating network water supply pipeline (1).

3. The multi-grade low-level energy cascade heating method based on network source comprehensive energy saving as claimed in claim 1, characterized in that: The cooling unit (10) is an air cooling tower, the steam inlet of the air cooling tower is connected to the exhaust steam outlet of the steam turbine unit, and valves are provided at the steam inlet of the air cooling tower and the steam inlet of the heat network condenser. By controlling the opening and closing of the valve at the steam inlet of the air cooling tower and the valve at the steam inlet of the heat network condenser, the air cooling tower can be controlled to be put into operation or shut down; or, The cooling unit (10) is a water cooling tower, the circulating water inlet of the water cooling tower is connected to the cooling water outlet of the heat network condenser, the circulating water outlet of the water cooling tower is connected to the cooling water inlet of the heat network condenser, the circulating water inlet of the water cooling tower, the circulating water outlet of the water cooling tower, the cooling water outlet of the heat network condenser and the cooling water outlet of the heat network condenser are all provided with valves, and by controlling the opening and closing of the valves at the circulating water inlet of the water cooling tower, the circulating water outlet of the water cooling tower, the cooling water outlet of the heat network condenser and the cooling water outlet of the heat network condenser, the water cooling tower, i.e. the cooling unit (10) can be controlled to be put into operation or removed.

4. The multi-grade low-level energy cascade heating method based on network source comprehensive energy saving as claimed in claim 1, characterized in that: The driving steam source of the peak heating system is preferably taken from the steam extraction ports of the preceding steam turbine units, and when the steam extraction port pressure of the steam turbine unit is higher than a set pressure value, the first small steam turbine (21) and the first small steam turbine exhaust heater (22) connected in parallel, and / or the second small steam turbine (24) and the second small steam turbine exhaust heater (25) connected in parallel are preferentially turned on; when the steam extraction port pressure of the steam turbine is lower than the set pressure value, only the first heating network heater (23) and / or the second heating network heater (26) are turned on.

5. The multi-grade low-level energy cascade heating method based on network source comprehensive energy saving as claimed in claim 1, characterized in that: When a certain steam turbine unit or heat network condenser fails, bypass the failed heat network condenser or the heat network condenser connected to the failed steam turbine unit; When the first peak heating system (19) fails, bypassing the first peak heating system (19); When the second peak heating system (20) fails, the second peak heating system (20) is bypassed.

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