CN215595669U

CN215595669U - Combined heat and power system

Info

Publication number: CN215595669U
Application number: CN202121600789.6U
Authority: CN
Inventors: 王建勋
Original assignee: Guoneng Longyuan Lantian Energy Saving Technology Co ltd
Current assignee: Guoneng Longyuan Lantian Energy Saving Technology Co ltd
Priority date: 2021-07-14
Filing date: 2021-07-14
Publication date: 2022-01-21
Anticipated expiration: 2031-07-14

Abstract

The utility model belongs to the technical field of combined heat and power, and particularly relates to a combined heat and power system. In the system, a heat supply network condenser is communicated with condensed water of an organic working medium evaporator, and the organic working medium evaporator is communicated with an organic working medium of an organic working medium preheater. The organic working medium evaporator is communicated with an organic working medium of the organic working medium screw expander, the organic working medium screw expander is communicated with an organic working medium of the organic working medium condenser, the organic working medium condenser is communicated with an organic working medium of the organic working medium preheater, a heat supply network circulating water inlet of the organic working medium preheater and a heat supply network circulating water outlet of the heat supply network condenser are respectively communicated with heat users, and the organic working medium preheater is communicated with heat supply network condenser heat supply network circulating water. The system can realize heat exchange between the liquid organic working medium and circulating return water of the heat supply network, heat exchange between the heated liquid organic working medium and condensed water of the unit, work of the gaseous organic working medium and condensation to form organic Rankine cycle, reduce the temperature of the circulating water of the heat supply network and meet the high back pressure operation condition of the unit.

Description

Combined heat and power system

Technical Field

The utility model belongs to the technical field of combined heat and power, and particularly relates to a combined heat and power system.

Background

In recent years, with the rapid development of urban economic construction, the living standard of people is continuously improved, the requirement of heating heat load of cities in winter is rapidly increased, and with the continuous increase of the demand of heat users, the annual central heating demand of the cities is greater than the actual heating capacity, so that the demand of the heat supply capacity of units is urgently needed to be improved. How to deeply excavate the heat supply potential of the existing coal-fired unit and reduce the heat supply cost so as to meet the requirements of heat users becomes the problem which needs to be solved urgently at present.

In the most conventional heating technologies in China at present, the medium-exhaust perforating steam extraction heating technology is the most common, and the technology utilizes the medium-pressure cylinder to extract steam to heat the circulating water of the heating network in the heating network heater, so that the heating demand of a heat user is met. However, in the heat supply technology, on one hand, the steam extraction parameters of the intermediate pressure cylinder are high, the steam quality is high, the heat energy consumption is high, the steam extraction parameters are not matched with the demand parameters of heat users, the steam which is originally used for generating electricity is used for heating and supplying heat, the energy waste loss is caused, the energy-saving effect is poor, the minimum flow of the low pressure cylinder is limited, the steam extraction flow of the intermediate pressure cylinder is limited, the heat supply capacity of the intermediate pressure cylinder cannot be fully exerted, and the heat supply load of a unit is limited. On the other hand, after the steam entering the low-pressure cylinder of the steam turbine does work, the steam is discharged through the low-pressure cylinder and enters the condenser or the air cooling island to be condensed into condensed water, and the heat of the condensed water is dissipated to the atmosphere through the cooling tower or the air cooling island, so that the cold source loss is generated, the energy waste is great, and the heat efficiency of the power plant is improved to a limited extent. Therefore, the heat supply by using the steam with lower grade is an important research direction, more and more projects are provided for supplying heat by using the waste steam waste heat of the unit at present, the technology for supplying heat by using the waste steam waste heat of the unit is mainly a high-back-pressure heat supply technology, the technology can realize energy conservation and emission reduction, is a heat supply technology for deeply recovering the waste steam exhaust heat of the steam turbine, utilizes the vaporization latent heat of the steam exhaust of the steam turbine, can effectively reduce the inherent cold source loss caused by the heat release of the steam exhaust of the low-pressure cylinder of the steam turbine in a condenser or an air cooling island, and is an important energy conservation and emission reduction technology. According to the technology, the large condenser is transformed into the heat supply network condenser of the combined heat and power system (the air cooling unit is additionally provided with the heat supply network condenser), the exhaust pressure of the low-pressure cylinder of the steam turbine is increased, so that the exhaust temperature of the low-pressure cylinder of the steam turbine is increased, the heat supply network circulating water is introduced into the heat supply network condenser (the air cooling unit is introduced into the additionally provided heat supply network condenser) and is heated by the exhaust of the low-pressure cylinder, the outlet temperature of the heat supply network circulating water is increased, and the heat supply requirement of a heat user is met. Adopt this technique will get into the intermediate pressure cylinder exhaust steam waste heat recovery of condenser or air cooling island originally, reduce the loss of inherent cold source to zero, with this partial energy make full use of, both can improve the heating capacity, can promote the energy utilization efficiency of unit again. However, the objective condition of the heat supply technology is that the heat supply network with sufficient heat supply area and low temperature circulates the latent heat of vaporization of the water discharged by the low pressure cylinder, and the unit can safely and stably operate after being transformed, so that the unit is not suitable for being adopted by the unit with overhigh return water temperature, the popularization of the high back pressure heat supply technology is limited due to overhigh return water temperature, and the heat supply technology becomes a key technical difficulty and bottleneck of the popularization of the technology. Furthermore, during the severe cold period of heat supply, the steam extracted by the intermediate pressure cylinder is generally adopted as a peak steam source to secondarily heat the circulating water of the heat supply network in the heat supply network heater, so that the requirement of a user is met, and the steam heated as the peak is condensed into hydrophobic steam and then returns to a hot well of the condenser (the air cooling unit returns to the steam exhaust device). The steam extraction parameter of the intermediate pressure cylinder is far higher than the water supply temperature and is not matched with a hot user, so that the loss of high-grade energy is caused, the energy is wasted, and the steam extraction parameter of the intermediate pressure cylinder is higher in temperature after being condensed into condensed water, so that the requirement of a fine processing device cannot be met.

SUMMERY OF THE UTILITY MODEL

Technical problem to be solved

In order to solve the above problems of the prior art, the present invention provides a cogeneration system capable of reducing the temperature of the circulating return water of a heat supply network.

(II) technical scheme

In order to achieve the purpose, the utility model adopts the main technical scheme that:

the utility model provides a combined heat and power system, which comprises a unit capable of operating at high back pressure, an organic working medium evaporator, an organic working medium preheater, an organic working medium screw expander and an organic working medium condenser, wherein the organic working medium evaporator is connected with the organic working medium preheater; the unit capable of operating at high back pressure comprises a low-pressure cylinder and a heat supply network condenser, wherein a steam inlet of the heat supply network condenser is communicated with a steam outlet of the low-pressure cylinder; a condensed water outlet of the heat supply network condenser is communicated with a condensed water inlet of the organic working medium evaporator, and an organic working medium inlet of the organic working medium evaporator is selectively communicated with an organic working medium outlet of the organic working medium preheater; an organic working medium outlet of the organic working medium evaporator is selectively communicated with an organic working medium inlet of the organic working medium screw expander; an organic working medium outlet of the organic working medium screw expander is communicated with an organic working medium inlet of the organic working medium condenser, and an organic working medium outlet of the organic working medium condenser is communicated with an organic working medium inlet of the organic working medium preheater; a heat supply network circulating water return inlet of the organic working medium preheater is used for being communicated with a heat user, and a heat supply network circulating water return outlet of the organic working medium preheater is communicated with a heat supply network circulating water inlet of the heat supply network condenser; and a heat supply network circulating water outlet of the heat supply network condenser is communicated with a heat user.

According to the utility model, the device also comprises a steam power device and a spike heater; the unit capable of operating at high back pressure further comprises an intermediate pressure cylinder, wherein a steam exhaust outlet of the intermediate pressure cylinder is communicated with a steam inlet of the low pressure cylinder and a steam inlet of the steam work doing equipment in an adjustable flow manner, and a steam outlet of the steam work doing equipment is communicated with a steam inlet of the peak heater; a heat supply network circulating water outlet of the heat supply network condenser is communicated with a heat supply network circulating water inlet of the peak heater, and the heat supply network circulating water outlet of the peak heater is communicated with a heat user; the organic working medium evaporator comprises an organic working medium low-temperature evaporator and an organic working medium high-temperature evaporator, and optionally comprises an organic working medium-temperature evaporator; a condensed water outlet of the peak heater is communicated with a condensed water inlet of the organic working medium high-temperature evaporator, and the condensed water outlet of the organic working medium high-temperature evaporator is selectively communicated with a condensed water inlet of the organic working medium low-temperature evaporator; when the organic working medium temperature evaporator is included: the condensation water outlet of the heat supply network condenser is communicated with the condensation water inlet of the organic working medium temperature evaporator, the condensation water outlet of the organic working medium temperature evaporator is selectively communicated with the condensation water inlet of the organic working medium low temperature evaporator, the organic working medium outlet of the organic working medium low temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium temperature evaporator, the organic working medium inlet of the organic working medium high temperature evaporator is selectively communicated with the organic working medium outlet of the organic working medium temperature evaporator, and the organic working medium outlet of the organic working medium low temperature evaporator, the organic working medium temperature evaporator and the organic working medium outlet of the organic working medium high temperature evaporator are selectively communicated with the organic working medium inlet of the organic working medium screw expander; when the medium-temperature evaporator of the organic working medium is not included: the organic working medium outlet of the organic working medium low-temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium high-temperature evaporator, and the organic working medium outlet of the organic working medium low-temperature evaporator and the organic working medium outlet of the organic working medium high-temperature evaporator are selectively communicated with the organic working medium inlet of the organic working medium screw expander.

According to the utility model, the unit capable of operating at high back pressure comprises a first unit and a second unit; when the first unit and the second unit run at the same time with high back pressure, the back pressure of the low-pressure cylinder of the first unit can be higher than that of the low-pressure cylinder of the second unit; the first unit comprises a first unit low-pressure cylinder and a first unit heat supply network condenser, a steam inlet of the first unit heat supply network condenser is selectively communicated with a steam outlet of the first unit low-pressure cylinder, the second unit comprises a second unit low-pressure cylinder and a second unit heat supply network condenser, and a steam inlet of the second unit heat supply network condenser is communicated with a steam outlet of the second unit low-pressure cylinder; the combined heat and power system comprises a first organic working medium low-temperature evaporator and a second organic working medium low-temperature evaporator, a condensed water outlet of a second unit heat supply network condenser is communicated with a condensed water inlet of the second organic working medium low-temperature evaporator, and organic working medium inlets of the first organic working medium low-temperature evaporator and the second organic working medium low-temperature evaporator are selectively communicated with an organic working medium outlet of the organic working medium preheater; the combined heat and power system also optionally comprises an organic working medium temperature evaporator; under the condition that the organic working medium temperature evaporator is not included, a condensed water outlet of the first unit heat supply network condenser is communicated with a condensed water inlet of the first organic working medium low temperature evaporator, and organic working medium outlets of the first organic working medium low temperature evaporator and the second organic working medium low temperature evaporator are selectively communicated with an organic working medium inlet of the organic working medium screw expander; under the condition of comprising an organic working medium low-temperature evaporator, a condensed water outlet of a first unit heat supply network condenser is communicated with a condensed water inlet of the organic working medium low-temperature evaporator, a condensed water outlet of the organic working medium low-temperature evaporator is selectively communicated with a condensed water inlet of a first organic working medium low-temperature evaporator, organic working medium outlets of the first organic working medium low-temperature evaporator and a second organic working medium low-temperature evaporator are selectively communicated with an organic working medium inlet of the organic working medium low-temperature evaporator, an organic working medium outlet of the first organic working medium low-temperature evaporator, an organic working medium outlet of the second organic working medium low-temperature evaporator, an organic working medium outlet of the organic working medium low-temperature evaporator and an organic working medium inlet of the organic working medium screw expander are selectively communicated; a heat supply network circulating water return inlet of the organic working medium preheater is used for being communicated with a heat user, and a heat supply network circulating water return outlet of the organic working medium preheater is communicated with a heat supply network circulating water inlet of a second unit heat supply network condenser; and a heat supply network circulating water outlet of the second unit heat supply network condenser is communicated with a heat supply network circulating water inlet of the first unit heat supply network condenser, and a heat supply network circulating water outlet of the first unit heat supply network condenser is communicated with a heat user.

According to the utility model, the device also comprises steam work equipment, a peak heater, an organic working medium high-temperature evaporator and an organic working medium-temperature evaporator; the first unit also comprises a first unit intermediate pressure cylinder, the steam outlet of the first unit intermediate pressure cylinder is communicated with the steam inlet of the first unit low pressure cylinder and the steam inlet of the steam work doing equipment in an adjustable flow manner, and the steam outlet of the steam work doing equipment is communicated with the steam inlet of the spike heater; a condensed water outlet of the peak heater is communicated with a condensed water inlet of the organic working medium high-temperature evaporator, a condensed water outlet of the organic working medium high-temperature evaporator is selectively communicated with a condensed water inlet of the first organic working medium low-temperature evaporator, an organic working medium inlet of the organic working medium high-temperature evaporator is selectively communicated with an organic working medium outlet of the organic working medium-temperature evaporator, and an organic working medium outlet of the organic working medium high-temperature evaporator is selectively communicated with an organic working medium inlet of the organic working medium screw expander; and a heat supply network circulating water outlet of the first unit heat supply network condenser is communicated with a heat supply network circulating water inlet of the peak heater, and the heat supply network circulating water outlet of the peak heater is communicated with a heat user.

According to the utility model, the device also comprises steam work equipment, a peak heater and an organic working medium high-temperature evaporator, but does not comprise an organic working medium-temperature evaporator; the first unit also comprises a first unit intermediate pressure cylinder, the steam outlet of the first unit intermediate pressure cylinder is communicated with the steam inlet of the first unit low pressure cylinder and the steam inlet of the steam work doing equipment in an adjustable flow manner, and the steam outlet of the steam work doing equipment is communicated with the steam inlet of the spike heater; the condensed water outlet of the peak heater is communicated with the condensed water inlet of the organic working medium high-temperature evaporator, the organic working medium inlet of the organic working medium high-temperature evaporator is selectively communicated with the organic working medium outlets of the first organic working medium low-temperature evaporator and the second organic working medium low-temperature evaporator, and the organic working medium outlet of the organic working medium high-temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium screw expander; and a heat supply network circulating water outlet of the first unit heat supply network condenser is communicated with a heat supply network circulating water inlet of the peak heater, and the heat supply network circulating water outlet of the peak heater is communicated with a heat user.

According to the utility model, the device also comprises steam work equipment and a peak heater, and does not comprise an organic working medium temperature evaporator; the first unit also comprises a first unit intermediate pressure cylinder, the steam outlet of the first unit intermediate pressure cylinder is communicated with the steam inlet of the first unit low pressure cylinder and the steam inlet of the steam work doing equipment in an adjustable flow manner, and the steam outlet of the steam work doing equipment is communicated with the steam inlet of the spike heater; a condensed water outlet of the peak heater is selectively communicated with a condensed water inlet of the first organic working medium low-temperature evaporator; and a heat supply network circulating water outlet of the first unit heat supply network condenser is communicated with a heat supply network circulating water inlet of the peak heater, and the heat supply network circulating water outlet of the peak heater is communicated with a heat user.

According to the utility model, the unit capable of operating at high back pressure further comprises a hot well and a fine processing device, wherein a condensed water outlet of the organic working medium low-temperature evaporator is communicated with an inlet of the hot well, and an outlet of the hot well is communicated with an inlet of the fine processing device.

According to the utility model, the device also comprises an organic working medium side cooling water heat dissipation tower; a cooling water inlet of the organic working medium condenser is communicated with an outlet of the organic working medium side cooling water heat dissipation tower; the cooling water outlet of the organic working medium condenser is communicated with the inlet of the organic working medium side cooling water heat dissipation tower.

According to the utility model, the device also comprises a steam exhaust heat exchanger and a steam side cooling water heat dissipation tower; the steam inlet of the steam exhaust heat exchanger is communicated with the steam outlet of the steam work doing equipment in an adjustable flow manner, the cooling water inlet of the steam exhaust heat exchanger is communicated with the outlet of the steam side cooling water heat dissipation tower, and the cooling water outlet of the steam exhaust heat exchanger is communicated with the inlet of the steam side cooling water heat dissipation tower.

According to the utility model, the steam power plant comprises a steam screw expander/steam back press, a steam-side reduction gear and a steam-side generator; the steam side generator is connected with the steam screw expander/steam back press through a steam side speed reducer.

(III) advantageous effects

The utility model has the beneficial effects that:

the combined heat and power system provided by the utility model can realize heat exchange between the liquid organic working medium and the circulating return water of the heat supply network, heat exchange between the heated liquid organic working medium and the condensed water of the unit, and work done by the gaseous organic working medium and condensation to form organic Rankine cycle, so that the temperature of the circulating water of the heat supply network (namely the circulating return water of the heat supply network) is reduced, sufficient cooling capacity is provided to take away the latent heat of vaporization of the exhaust steam of the low-pressure cylinder of the high-back-pressure unit, the waste heat of the exhaust steam of the low-pressure cylinder is utilized, the high-back-pressure operation condition of the unit is met, and the harsh requirements of the traditional high-back-pressure heat supply technology on the heat supply area and the circulating return water temperature of the heat supply network are overcome.

Drawings

FIG. 1 is a schematic structural diagram of a combined heat and power system according to a first embodiment of the present invention; FIG. 2 is a schematic diagram of the combined heat and power system of FIG. 1 during the initial and final heating phases; FIG. 3 is a schematic diagram of the combined heat and power system of FIG. 1 in a first heating mode during a normal heating phase; FIG. 4 is a schematic diagram of the combined heat and power system of FIG. 1 in a second heating mode during a normal heating phase; FIG. 5 is a schematic structural diagram of a combined heat and power system according to a second embodiment of the present invention; FIG. 6 is a schematic diagram of the combined heat and power system of FIG. 5 during the initial and final heating phases; FIG. 7 is a schematic diagram of the combined heat and power system of FIG. 5 being turned on in a first heating mode during a normal heating phase; FIG. 8 is a schematic diagram of the combined heat and power system of FIG. 5 being turned on in a second heating mode during a normal heating phase; FIG. 9 is a schematic structural diagram of a third embodiment of the cogeneration system of the utility model; FIG. 10 is a schematic diagram of the combined heat and power system of FIG. 9 during the initial and final heating phases; FIG. 11 is a schematic diagram of the combined heat and power system of FIG. 9 being turned on in a first heating mode during a normal heating phase; FIG. 12 is a schematic diagram of the combined heat and power system of FIG. 9 in a second heating mode during a normal heating phase; fig. 13 is a schematic view of the cogeneration system of the utility model having only one unit.

1: a first set of intermediate pressure cylinders; 2: a first set of low pressure cylinders; 3: a second unit low pressure cylinder; 4: an organic working medium screw expander; 5: a steam screw expander; 6: an organic working medium side reduction gear; 7: an organic working medium side generator; 8: a second unit heat supply network condenser; 9: a first unit heat supply network condenser; 10: a spike heater; 11: a hot user; 12: a heat supply network water circulating pump; 13: an organic working medium preheater; 14: an organic working medium condenser; 15: a steam exhaust heat exchanger; 16: a first organic working medium low-temperature evaporator; 17: a second organic working medium low-temperature evaporator; 18: an organic working medium temperature evaporator; 19: an organic working medium high-temperature evaporator; 20: an organic working medium circulating pump; 21: cooling water radiating tower on organic working medium side; 22: an organic working medium side cooling water circulating pump; 23: a second unit hot well; 24: a first cluster of hot wells; 25: a first unit condensate pump; 26: a condensate pump of the second unit; 27: a first unit fine processing device; 28: a second unit fine processing device; 29: a first valve; 30: a third valve; 31: a fifth valve; 32: a fourth valve; 33: a tenth valve; 34: an eleventh valve; 35: a seventh valve; 36: a seventeenth valve; 37: a ninth valve; 38: a fifteenth valve; 39: a tenth valve; 40: an eighteenth valve; 41: a tenth valve; 42: a sixteenth valve; 43: a fourteenth valve; 44: a sixth valve; 45: a second valve; 46: a steam side cooling water heat dissipation tower; 47: a steam side cooling water circulation pump; 48: a steam-side reduction gear; 49: a steam-side generator; 50: an eighth valve; 51: a nineteenth valve.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

Example one

Referring to fig. 1, the present embodiment provides a cogeneration control system. The combined heat and power control system comprises a first unit, a second unit, a first organic working medium low-temperature evaporator 16, a second organic working medium low-temperature evaporator 17, an organic working medium intermediate-temperature evaporator 18, an organic working medium high-temperature evaporator 19, an organic working medium preheater 13, an organic working medium screw expander 4, an organic working medium condenser 14, an organic working medium side generator 7, an organic working medium side speed reducer 6, an organic working medium side cooling water heat dissipation tower 21, steam work equipment, a peak heater 10, a steam exhaust heat exchanger 15 and a steam side cooling water heat dissipation tower 46.

Wherein, first unit and second unit all can high back pressure operation. Namely, the water temperature at the outlet of the second unit heat supply network condenser is lower than that of the first unit heat supply network condenser.

The first unit comprises a first unit high-pressure cylinder (not shown), a first unit medium-pressure cylinder 1, a first unit low-pressure cylinder 2, a first unit heat supply network condenser 9, a first unit hot well 24, a first unit condensate pump 25 and a first unit fine processing device 27.

The steam outlet of the first unit high-pressure cylinder is connected with the steam inlet of the first unit intermediate-pressure cylinder 1, and the steam outlet of the first unit intermediate-pressure cylinder 1 is communicated with the steam inlet of the first unit low-pressure cylinder 2 in an adjustable flow manner through a pipeline with a first valve 29. The steam outlet of the first unit low-pressure cylinder 2 is selectively communicated with the steam inlet of the first unit heat supply network condenser 9 through a pipeline with a nineteenth valve 51. And a condensed water outlet of the first unit heat supply network condenser 9 is communicated with a condensed water inlet of the organic working medium temperature evaporator 18 through a pipeline. The condensed water outlet of the organic working medium intermediate temperature evaporator 18 is selectively communicated with the condensed water inlet of the first organic working medium low temperature evaporator 16 through a pipeline with a second valve 45. The condensed water outlet of the first organic working medium low-temperature evaporator 16 is communicated with the inlet of the first unit hot well 24 through a pipeline, and the outlet of the first unit hot well 24 is communicated with the inlet of the first unit fine processing device 27 through a pipeline where the first unit condensed water pump 25 is located.

The steam work equipment includes a steam screw expander 5 or a steam back press, etc. which can use steam to work, and in this embodiment, the steam screw expander 5 is taken as an example. The steam work plant further includes a steam-side reduction gear 48 and a steam-side generator 49.

The steam outlet of the first group of cylinders 1 is also in flow-adjustable communication with the steam inlet of the steam screw expander 5 (i.e. the steam inlet of the steam power plant) via a line with a third valve 30. Thus, the exhaust steam of the first unit intermediate pressure cylinder 1 can selectively enter the first unit low pressure cylinder 2 and/or the steam screw expander 5. The steam-side generator 49 is connected to the steam screw expander 5 via a steam-side reduction gear 48.

The steam outlet of the steam screw expander 5 (i.e. the steam outlet of the steam power plant) is in flow-adjustable communication with the steam inlet of the exhaust heat exchanger 15 via a line with a fourth valve 32. The cooling water inlet of the exhaust heat exchanger 15 is communicated with the outlet of the steam side cooling water heat dissipation tower 46 through a pipeline, the cooling water outlet of the exhaust heat exchanger 15 is communicated with the inlet of the steam side cooling water heat dissipation tower 46 through a pipeline, and one of the two pipelines is provided with a steam side cooling water circulating pump 47 (in the embodiment, the steam side cooling water circulating pump 47 is arranged on the pipeline communicated with the cooling water outlet of the exhaust heat exchanger 15 and the inlet of the steam side cooling water heat dissipation tower 46), so that the circulation of the cooling water on the steam side is formed. The condensed water outlet of the exhaust steam heat exchanger 15 is communicated with the inlet of the first unit heat well 24 through a pipeline.

The steam outlet of the steam screw expander 5 (i.e. the steam outlet of the steam power plant) is also in flow-adjustable communication with the steam inlet of the spike heater 10 via a line with a fifth valve 31. The condensed water outlet of the peak heater 10 is communicated with the condensed water inlet of the organic working medium high-temperature evaporator 19 through a pipeline. The condensed water outlet of the organic working medium high-temperature evaporator 19 is selectively communicated with the condensed water inlet of the first organic working medium low-temperature evaporator 16 through a pipeline with a sixth valve 44.

The second unit comprises a second unit high-pressure cylinder (not shown), a second unit medium-pressure cylinder (not shown), a second unit low-pressure cylinder 3, a second unit heat supply network condenser 8, a second unit hot well 23, a second unit condensate pump 26 and a second unit fine processing device 28. The back pressure of the first unit low pressure cylinder 2 can be operated higher than the back pressure of the second unit low pressure cylinder 3.

The steam outlet of the second unit high-pressure cylinder is connected with the steam inlet of the second unit intermediate-pressure cylinder, and the steam outlet of the second unit intermediate-pressure cylinder is communicated with the steam inlet of the second unit low-pressure cylinder 3 through a pipeline. And a steam outlet of the second unit low-pressure cylinder 3 is communicated with a steam inlet of a second unit heat supply network condenser 8 through a pipeline. And a condensed water outlet of the second unit heat supply network condenser 8 is communicated with a condensed water inlet of the second organic working medium low-temperature evaporator 17 through a pipeline, and a condensed water outlet of the second organic working medium low-temperature evaporator 17 is communicated with an inlet of the second unit heat well 23 through a pipeline. The outlet of the second unit hot well 23 is communicated with the inlet of a second unit fine treatment device 28 through a pipeline where a second unit condensate pump 26 is located.

The organic working medium inlet of the first organic working medium low-temperature evaporator 16 and the organic working medium inlet of the second organic working medium low-temperature evaporator 17 are both selectively communicated with the organic working medium outlet of the organic working medium preheater 13 through a pipeline with a seventh valve 35, and meanwhile, an eighth valve 50 for independently controlling whether the first organic working medium low-temperature evaporator 16 is used or not is arranged between the first organic working medium low-temperature evaporator 16 and the seventh valve 35. When the seventh valve 35 and the eighth valve 50 are opened simultaneously, the organic working medium outlet of the organic working medium preheater 13 is communicated with the organic working medium inlet of the first organic working medium low-temperature evaporator 16 and the organic working medium inlet of the second organic working medium low-temperature evaporator 17 simultaneously; when the seventh valve 35 is opened and the eighth valve 50 is closed, the organic working medium outlet of the organic working medium preheater 13 is disconnected from the organic working medium inlet of the first organic working medium low-temperature evaporator 16 and is communicated with the organic working medium inlet of the second organic working medium low-temperature evaporator 17. The organic working medium outlet of the first organic working medium low-temperature evaporator 16 and the organic working medium outlet of the second organic working medium low-temperature evaporator 17 are selectively communicated with the organic working medium inlet of the organic working medium intermediate-temperature evaporator 18 through a pipeline with a ninth valve 37 and a tenth valve 39.

In addition, the organic working medium outlet of the first organic working medium low-temperature evaporator 16 and the organic working medium outlet of the second organic working medium low-temperature evaporator 17 are also selectively communicated with the organic working medium inlet of the organic working medium screw expander 4 through a pipeline with an eleventh valve 34. In this embodiment, the line is connected to the organic working medium inlet of the organic working medium screw expander 4 via the tenth valve 33 in the line on the upstream side of the organic working medium screw expander 4. When the eleventh valve 34 is opened and the ninth valve 37 is closed, the gaseous organic working medium discharged from the first organic working medium low-temperature evaporator 16 and the second organic working medium low-temperature evaporator 17 directly enters the organic working medium screw expander 4 without passing through the organic working medium-temperature evaporator 18 and the organic working medium high-temperature evaporator 19.

The organic working medium outlet of the organic working medium intermediate temperature evaporator 18 is selectively communicated with the organic working medium inlet of the organic working medium high temperature evaporator 19 through a pipeline with a thirteenth valve 41 and a fourteenth valve 43. Meanwhile, an organic working medium outlet of the organic working medium intermediate temperature evaporator 18 is communicated with an organic working medium inlet of the organic working medium screw expander 4 through a pipeline with a fifteenth valve 38, and an organic working medium outlet of the organic working medium high temperature evaporator 19 is communicated with an organic working medium inlet of the organic working medium screw expander 4 through a pipeline with a sixteenth valve 42. In this embodiment, the above-mentioned pipeline is connected to the organic working medium inlet of the organic working medium screw expander 4 through the tenth valve 33 on the pipeline on the upstream side of the organic working medium screw expander 4. Therefore, when the fifteenth valve 38 is disconnected and the thirteenth valve 41, the fourteenth valve 43 and the sixteenth valve 42 are connected, the organic working medium high-temperature evaporator 19 is connected to the system for working; when the fifteenth valve 38 is turned on and the thirteenth valve 41, the fourteenth valve 43 and the sixteenth valve 42 are turned off, the organic working medium high-temperature evaporator 19 is not connected to the system and does not work.

In this embodiment, one end of the pipeline where the fifteenth valve 38 is located is connected to one end of the pipeline where the sixteenth valve 42 is located and one end of the pipeline where the eleventh valve 34 is located, so that the on-off of the twelfth valve 33 also determines whether the organic working medium high-temperature evaporator, the organic working medium low-temperature evaporator and the organic working medium-temperature evaporator can be communicated with the organic working medium screw expander 4. The organic working medium screw expander 4 is connected with the organic working medium side generator 7 through the organic working medium side speed reducer 6, and the connection of the organic working medium screw expander, the organic working medium side generator and the organic working medium side speed reducer is completed through a shaft.

Furthermore, a line with a seventeenth valve 36 is connected upstream of the seventh valve 35 and downstream of the ninth valve 37, and when the seventeenth valve 36 is open, the first organic working medium low-temperature evaporator 16 and the second organic working medium low-temperature evaporator 17 are not connected to the system. There is also a line with an eighteenth valve 40 upstream of the tenth valve 39 and downstream of the tenth valve 41, and when the eighteenth valve 40 is open, the organic medium-temperature evaporator 18 is not connected to the system. Generally, the seventeenth valve 36 and the eighteenth valve 40 are not conductive, but in a specific situation (such as an accident of the system, etc.), the corresponding devices can be disconnected from the system by the conduction of the seventeenth valve 36 and the eighteenth valve 40.

An organic working medium outlet of the organic working medium screw expander 4 is communicated with an organic working medium inlet of the organic working medium condenser 14 through a pipeline. The organic working medium outlet of the organic working medium condenser 14 is communicated with the organic working medium inlet of the organic working medium preheater 13 through a pipeline with an organic working medium circulating pump 20. The cooling water inlet of the organic working medium condenser 14 is communicated with the outlet of the organic working medium side cooling water heat dissipation tower 21 through a pipeline, the cooling water outlet of the organic working medium condenser 14 is communicated with the inlet of the organic working medium side cooling water heat dissipation tower 21 through management, and one of the two pipelines is provided with an organic working medium side cooling water circulating pump 22 (in the embodiment, the organic working medium side cooling water circulating pump 22 is arranged on the pipeline between the cooling water inlet of the organic working medium condenser 14 and the outlet of the organic working medium side cooling water heat dissipation tower 21), so that the cooling water on the organic working medium side can be recycled.

The heat supply network circulating water return inlet of the organic working medium preheater 13 is communicated with one end of the heat supply loop, and the other end of the heat supply loop is connected with the heat user 11. And a heat supply network circulating water outlet of the organic working medium preheater 13 is communicated with a heat supply network circulating water inlet of the second unit heat supply network condenser 8 through a pipeline with a heat supply network water circulating pump 12. Of course, the position of the heat supply network water circulation pump 12 may be changed, and may be provided downstream of the second unit heat supply network condenser 8 or downstream of the spike heater 10, for example.

The heat supply network circulating water outlet of the second unit heat supply network condenser 8 is communicated with the heat supply network circulating water inlet of the first unit heat supply network condenser 9 through a pipeline, the heat supply network circulating water outlet of the first unit heat supply network condenser 9 is communicated with the heat supply network circulating water inlet of the peak heater 10 through a pipeline, the heat supply network circulating water outlet of the peak heater 10 is communicated with one end of a heat supply pipeline, and the other end of the heat supply pipeline is communicated with a heat user 11. Therefore, the heat supply network circulating water outlet of the first unit heat supply network condenser 9 is communicated with the heat supply pipeline. Of course, the present invention is not limited to this, and a bypass may be provided beside the spike heater 10, and when the spike heater 10 is not used for heating, the heat supply network circulating water outlet of the first unit heat supply network condenser 9 is guided to communicate with the heat consumer 11 through the bypass and the heat supply pipeline.

First, the first unit and the second unit both operate at high back pressure, and the back pressure of the low pressure cylinder of the first unit is higher than that of the low pressure cylinder of the second unit.

The low pressure cylinder adopts the original low pressure cylinder rotor, the exhaust steam of the intermediate pressure cylinder directly enters the low pressure cylinder to do work, and the exhaust steam parameter of the low pressure cylinder is restored to the normal level, namely, the steam turbine is restored to the pure condensing mode operation (non-high back pressure mode operation).

The low pressure jar rotor is changed for the high back pressure low pressure jar rotor of new design, realizes the high back pressure operation, according to the different scheduling requirements of power generation load and heat supply load, adjusts the steam flow who gets into steam screw expander, takes different heat supply modes, satisfies the heat consumer to the demand of heating to improve the economic nature of unit.

The heat supply demand of the combined heat and power system in the conventional heat supply stage is higher than that in the initial and final heat supply stages. The regular heating phase further comprises a first heating mode and a second heating mode. The beginning and end heating phases are applied to a period of very small heating demand, generally used in 11 months and 3 months, the first heating mode is used in 12 months, and the second heating mode is used in 1 month to 2 months. The specific use time of the initial and final heating stages and the two heating modes is determined according to the actual air temperature and may be slightly different every year.

The beginning and end heat supply stages are characterized in that only the second unit is put into the working mode of high back pressure operation, the first unit still operates in the pure condensation mode, and the steam work doing equipment, the peak heater 10, the steam exhaust heat exchanger 15, the organic working medium temperature evaporator 18, the steam side cooling water heat dissipation tower 46 and the organic working medium high temperature evaporator 19 do not work. Specifically, the method comprises the following steps:

referring to fig. 2, the seventh valve 35, the eleventh valve 34, the twelfth valve 33, and the first valve 29 are opened, and the remaining valves are closed.

And the heat supply network circulating backwater and the liquid organic working medium from the heat user 11 enter the organic working medium preheater 13, and the heat supply network circulating backwater exchanges heat with the liquid organic working medium to form cooled heat supply network circulating backwater and heated liquid organic working medium.

The cooled heat supply network circulating backwater passes through the second unit heat supply network condenser 8, and the exhaust steam of the low-pressure cylinder of the second unit enters the second unit heat supply network condenser 8. Therefore, the cooled circulating water of the heat supply network exchanges heat with the exhausted steam of the low-pressure cylinder of the second unit, and the heated circulating water of the heat supply network enters a heat supply pipeline through the condenser 9 (only passing without heating) of the heat supply network of the first unit and the peak heater 10 (only passing without heating) and is conveyed to a heat user 11 for supplying heat. And then the circulating return water of the heat supply network flows out of the heat user 11, enters a heat supply loop, returns to the organic working medium preheater 13 and exchanges heat with the liquid organic working medium again. Thus, the heat supply network circulating water forms a circulation.

The exhaust steam of the medium pressure cylinder of the first unit enters the low pressure cylinder 2 of the first unit through a pipeline with a first valve 29, and the exhaust steam of the low pressure cylinder of the first unit enters a condenser (not shown in the figure).

And the exhaust steam of the low-pressure cylinder of the second unit is condensed into condensed water of the second unit, and the condensed water is discharged from a heat supply network condenser 8 of the second unit to a second organic working medium low-temperature evaporator 17.

The heated liquid organic working medium enters the second organic working medium low-temperature evaporator 17 through a pipeline with a seventh valve 35 to exchange heat with the condensed water of the second unit, the heated liquid organic working medium is heated to form a gaseous organic working medium of the second unit, and meanwhile, the condensed water of the second unit is cooled. In conclusion, the heated liquid organic working medium absorbs the heat of the condensed water of the second unit to form the gaseous organic working medium.

The gaseous organic working medium of the second unit enters the organic working medium screw expander 4 through a pipeline with an eleventh valve 34 and a twelfth valve 33 to do work, and the gaseous organic working medium drives the generator 7 to generate electricity through the organic working medium side speed reducing device 6. The exhaust steam and cooling water of the organic working medium screw expander 4 enter the organic working medium condenser 14, the exhaust steam of the organic working medium screw expander 4 exchanges heat with the cooling water to form liquid organic working medium for exchanging heat with the circulating return water of the heat supply network, the liquid organic working medium enters the organic working medium preheater 13 through a pipeline with an organic working medium circulating pump 20, and the heated cooling water enters the organic working medium side cooling water heat dissipation tower 21 for heat dissipation and then is recycled. Therefore, the gaseous organic working medium of the second unit is directly used for doing work and generating electricity.

Thus, an organic working medium Rankine cycle is formed.

In addition, the second unit condensed water and the cooled second unit condensed water formed by the heat exchange of the heated liquid organic working medium are treated by a second unit fine treatment device 28, and the water quality is purified.

The first heat supply mode is characterized in that, referring to fig. 3, the first unit and the second unit are both put into the working mode of high back pressure operation, and the steam exhausted from the pressure cylinder in the first unit is completely fed into the low pressure cylinder 2 of the first unit through the pipeline with the first valve 29, so that the steam work equipment, the peak heater 10, the steam exhaust heat exchanger 15, the steam side cooling water heat dissipation tower 46 and the organic working medium high temperature evaporator 19 do not work. Specifically, the method comprises the following steps:

the first valve 29, the second valve 45, the seventh valve 35, the eighth valve 50, the ninth valve 37, the tenth valve 39, the tenth valve 33, the fifteenth valve 38, and the nineteenth valve 51 are opened, and the remaining valves are closed.

The cooled heat supply network circulating backwater sequentially passes through a second unit heat supply network condenser 8 and a first unit heat supply network condenser 9, the exhaust steam of the low-pressure cylinder of the second unit enters the second unit heat supply network condenser 8, and the exhaust steam of the low-pressure cylinder of the first unit enters the first unit heat supply network condenser 9. Therefore, the cooled circulating backwater of the heat supply network exchanges heat with the steam exhausted from the low-pressure cylinder of the second unit and the steam exhausted from the low-pressure cylinder of the first unit in sequence, and the circulating water of the heat supply network heated by two stages enters a heat supply pipeline through the peak heater 10 (only passing without heating effect) and is conveyed to a heat user 11 for supplying heat. And then the circulating return water of the heat supply network flows out of the heat user 11, enters a heat supply loop, returns to the organic working medium preheater 13 and exchanges heat with the liquid organic working medium again. Thus, the heat supply network circulating water forms a circulation.

The exhaust steam of the low-pressure cylinder of the second unit is condensed into condensed water of the second unit, the condensed water is discharged from a heat supply network condenser 8 of the second unit to a second organic working medium low-temperature evaporator 17, the exhaust steam of the low-pressure cylinder of the first unit is condensed into condensed water of the first unit, the condensed water is discharged from a heat supply network condenser 9 of the first unit to an organic working medium temperature evaporator 18, and then the condensed water enters a first organic working medium low-temperature evaporator 16 from the organic working medium temperature evaporator 18 through a pipeline with a second valve 45.

The heated liquid organic working medium is divided into two parts. And a part of the heated liquid organic working medium enters the second organic working medium low-temperature evaporator 17 through a pipeline with a seventh valve 35 to exchange heat with the condensed water of the second unit, the heated liquid organic working medium is heated to form a gaseous organic working medium of the second unit, and meanwhile, the condensed water of the second unit is cooled. The other part of the heated liquid organic working medium enters the first organic working medium low-temperature evaporator 16 through a pipeline with a seventh valve 35 and an eighth valve 50 to exchange heat with the cooled first unit condensed water, the heated liquid organic working medium is heated to form the first unit gaseous organic working medium, and meanwhile, the cooled first unit condensed water is cooled again. Wherein, the sources of the cooled condensed water of the first unit are as follows: the first unit gaseous organic working medium and the second unit gaseous organic working medium enter the organic working medium intermediate temperature evaporator 18 through a pipeline with a ninth valve 37 and a tenth valve 39, heat exchange is carried out between the organic working medium intermediate temperature evaporator 18 and first unit condensed water from the first unit heat supply network condenser 9, the first unit condensed water is cooled to form 'cooled first unit condensed water', and the 'cooled first unit condensed water' is sent to the first organic working medium low temperature evaporator 16 through a pipeline with a second valve 45. The gaseous organic working medium of the first unit and the gaseous organic working medium of the second unit are heated to form a heated gaseous organic working medium. In conclusion, the heated liquid organic working medium absorbs the heat of the condensed water of the second unit and the condensed water of the first unit to form the gaseous organic working medium, wherein the heat is effectively utilized and the temperature of the gaseous organic working medium is increased by the graded heating of the organic working medium intermediate-temperature evaporator and the first organic working medium low-temperature evaporator. The first unit gaseous working medium and the second unit gaseous working medium are named only by distinguishing according to flow paths, and are completely the same and are changed from the same liquid working medium.

The heated gaseous organic working medium enters the organic working medium screw expander 4 through a pipeline with a fifteenth valve 38 and a twelfth valve 33 to do work, and the organic working medium side generator 7 is dragged by the organic working medium side speed reducer 6 to generate electricity. The exhaust steam and cooling water of the organic working medium screw expander 4 enter the organic working medium condenser 14, the exhaust steam of the organic working medium screw expander 4 exchanges heat with the cooling water to form liquid organic working medium for exchanging heat with the circulating return water of the heat supply network, and the liquid organic working medium enters the organic working medium preheater 13 through a pipeline with an organic working medium circulating pump 20. The heated cooling water enters the cooling water heat dissipation tower 21 at the organic working medium side for heat dissipation and then is recycled. Therefore, the gaseous organic working medium of the first unit and the heated gaseous organic working medium formed after the gaseous organic working medium of the second unit exchanges heat with the condensed water of the first unit are directly used for doing work and generating power.

Thus, an organic working medium Rankine cycle is formed.

In addition, the second-stage cooling first unit condensed water formed by heat exchange between the cooled first unit condensed water and the heated liquid organic working medium is processed by the first unit fine processing device 27 to purify the water quality. Meanwhile, the second unit condensed water is subjected to heat exchange with the heated liquid organic working medium to form cooled second unit condensed water, and the cooled second unit condensed water is treated by a second unit fine treatment device 28 to purify water.

The second heat supply mode is characterized in that, referring to fig. 4, part of the steam discharged by the pressure cylinder in the first unit enters the low pressure cylinder 2 of the first unit through the pipeline with the first valve 29, and the other part enters the steam work equipment through the pipeline with the third valve 30 to do work and generate power, so that the steam work equipment, the peak heater 10, the steam discharge heat exchanger 15, the steam side cooling water heat dissipation tower 46 and the organic working medium high-temperature evaporator 19 are in work. Specifically, the method comprises the following steps:

the first valve 29, the second valve 45, the third valve 30, the fourth valve 32, the fifth valve 31, the sixth valve 44, the seventh valve 35, the eighth valve 50, the ninth valve 37, the tenth valve 39, the tenth valve 33, the thirteenth valve 41, the fourteenth valve 43, the sixteenth valve 42, and the nineteenth valve 51 are opened, and the remaining valves are closed.

The cooled heat supply network circulating backwater sequentially passes through a second unit heat supply network condenser 8, a first unit heat supply network condenser 9 and a peak heater 10, the exhaust steam of a second unit low-pressure cylinder enters the second unit heat supply network condenser 8, the exhaust steam of a first unit low-pressure cylinder enters the first unit heat supply network condenser 9, a steam screw expander 5 receives the exhaust steam of the first unit medium-pressure cylinder to do work, a steam side speed reducer 48 and a steam side generator 49 are dragged to generate electricity, a part of the steam (namely the exhaust steam of a steam work equipment) exhausted by the steam screw expander 5 enters the peak heater 10 through a pipeline with a fifth valve 31, and a part of the steam enters an exhaust steam heat exchanger 15 through a pipeline with a fourth valve 32. Therefore, the cooled circulating backwater of the heat supply network exchanges heat with the steam exhausted by the second unit low-pressure cylinder, the steam exhausted by the first unit low-pressure cylinder and the steam exhausted by the steam screw expander in sequence, and enters a heat supply pipeline after being heated in a three-stage mode and is conveyed to a heat user 11 for heat supply. And then the circulating return water of the heat supply network flows out of the heat user 11, enters a heat supply loop, returns to the organic working medium preheater 13 and exchanges heat with the liquid organic working medium again. Thus, the heat supply network circulating water forms a circulation.

The exhaust steam of the low-pressure cylinders of the second unit is condensed into condensed water of the second unit, and the condensed water is discharged from the heat supply network condenser 8 of the second unit to the low-temperature evaporator 17 of the second organic working medium, and the exhaust steam of the low-pressure cylinders of the first unit is condensed into condensed water of the first unit, and the condensed water is discharged from the heat supply network condenser 9 of the first unit to the medium-temperature evaporator 18 of the organic working medium. Condensed water after the exhaust steam of the steam screw expander 5 is condensed in the peak heater 10 is discharged from the peak heater 10 to the organic working medium high-temperature evaporator 19.

The heated liquid organic working medium is divided into two parts. And a part of the heated liquid organic working medium enters the second organic working medium low-temperature evaporator 17 through a pipeline with a seventh valve 35 to exchange heat with the condensed water of the second unit, the heated liquid organic working medium is heated to form a gaseous organic working medium of the second unit, and meanwhile, the condensed water of the second unit is cooled. The other part of the heated liquid organic working medium enters the first organic working medium low-temperature evaporator 16 through a pipeline with an eighth valve 50 and a seventh valve 35 to exchange heat with the cooled first unit condensed water, the heated liquid organic working medium is heated to form the first unit gaseous organic working medium, and meanwhile, the cooled first unit condensed water is cooled again. Wherein, the sources of the cooled condensed water of the first unit are as follows: the first unit gaseous organic working medium and the second unit gaseous organic working medium enter the organic working medium intermediate temperature evaporator 18 through a pipeline with a ninth valve 37 and a tenth valve 39, heat exchange is carried out between the organic working medium intermediate temperature evaporator 18 and the first unit condensed water, the first unit condensed water is cooled to form 'cooled first unit condensed water', and the 'cooled first unit condensed water' is sent to the first organic working medium low temperature evaporator 16 through a pipeline with a second valve 45. The gaseous organic working medium of the first unit and the gaseous organic working medium of the second unit are heated in the organic working medium intermediate temperature evaporator 18 to form the heated gaseous organic working medium. In conclusion, the heated liquid organic working medium absorbs the heat of the condensed water of the second unit and the condensed water of the first unit to form the gaseous organic working medium, wherein the heat is effectively utilized and the temperature of the gaseous organic working medium is increased by the graded heating of the organic working medium intermediate-temperature evaporator and the first organic working medium low-temperature evaporator.

The heated gaseous organic working medium enters the organic working medium high-temperature evaporator 19 through a pipeline with a thirteenth valve 41 and a fourteenth valve 43, condensed water obtained after exhaust steam condensation of the steam screw expander 5 exchanges heat with the heated gaseous organic working medium to form a secondary heated gaseous organic working medium and cooled condensed water, the secondary heated gaseous organic working medium enters the organic working medium screw expander 4 through a pipeline with a sixteenth valve 42 and a twelfth valve 33 to do work, and the organic working medium side generator 7 is dragged to generate electricity through the organic working medium side speed reducer 6. The exhaust steam and cooling water of the organic working medium screw expander 4 enter the organic working medium condenser 14, the exhaust steam of the organic working medium screw expander 4 exchanges heat with the cooling water to form liquid organic working medium for exchanging heat with the circulating return water of the heat supply network, and the liquid organic working medium is sent to the organic working medium preheater 13 through a pipeline with an organic working medium circulating pump 20. The heated cooling water enters the cooling water heat dissipation tower 21 at the organic working medium side for heat dissipation and then is recycled. Thus, an organic working medium Rankine cycle is formed.

In addition, the cooled condensate formed simultaneously with the second-stage heated gaseous organic working medium enters the first organic working medium low-temperature evaporator 16 through a pipeline with a sixth valve 44, is also used for exchanging heat with the heated liquid organic working medium therein, and participates in forming "cooled first unit condensate".

In addition, steam and cooling water discharged by the steam screw expander 5 enter the steam-discharging heat exchanger 15 for heat exchange to form condensed water, the condensed water enters the first unit hot well 24, and the heated cooling water enters the steam-side cooling water heat-radiating tower 46 for heat radiation and then is recycled. Of course, in other embodiments of the utility model, the fourth valve 32 may be closed to allow all of the steam exiting the steam screw expander 5 to enter the spike heater 10. That is, part or all of the steam discharged from the steam screw expander 5 may be used for heat exchange with the heat supply network circulating water.

In summary, the cogeneration system provided by the embodiment has the following advantages:

1. synthesize the heating mode that above-mentioned heating is not the severe cold period and the severe cold period is different, the high back pressure heat supply under the condition that the heat supply area is limited and heat supply network circulation return water temperature is higher can be born the demand of reforming transform to this embodiment cogeneration system, can carry out high back pressure heat supply with the power plant that originally is not applicable to high back pressure heat supply and reforms transform, has widened the accommodation that high back pressure heat supply was reformed transform, has reduced the cold source loss, has improved unit economic nature. The design that the organic Rankine cycle is formed by the heat exchange between the liquid organic working medium and the circulating backwater of the heat supply network, the heat exchange between the heated liquid organic working medium and the unit condensed water, the work of the gaseous organic working medium in the screw expander, the power generation of the screw expander driving the generator and the heat exchange between the gaseous organic working medium and the cooling water after the work of the gaseous organic working medium can be realized is particularly realized, the higher temperature of the circulating water of the heat supply network is utilized, the circulating backwater temperature of the heat supply network is really reduced, the high back pressure operation of the first unit and the second unit is met, and the prerequisite condition for realizing the high back pressure heat supply reconstruction of the unit is improved. Meanwhile, enough cooling capacity is provided for taking away latent heat of vaporization of the low-pressure cylinder exhaust steam of the high-back-pressure unit, and the waste heat of the low-pressure cylinder exhaust steam is utilized, so that the high-back-pressure operation condition of the unit is met, the harsh requirements of the traditional high-back-pressure heat supply technology on the heat supply area and the circulating return water temperature of a heat supply network are overcome, the application range of the high-back-pressure heat supply technology is widened, and the adaptability of the high-back-pressure heat supply technology is improved.

2. In the severe cold period of heat supply, when the exhaust steam of the low-pressure cylinder cannot meet the requirements of heat users, the exhaust steam of the steam screw expander is used as the steam for peak heating by additionally arranging the steam work doing equipment, and the exhaust steam parameters of the steam screw expander are matched with the heat supply temperature, so that the requirements of the heat users are met. Originally, because the energy of throttling loss has converted the kinetic energy of steam screw expander, is draged the generator by steam screw expander and has generated electricity, and kinetic energy has converted the electric energy into, has avoided the loss of high-grade energy, has accomplished the cascade utilization of the energy, and the cold source loss reduces to zero, has increased the generating power, has improved the economic nature of unit.

3. The high back pressure primary heating of the second unit heat supply network condenser, the high back pressure secondary heating of the first unit heat supply network condenser and the steam exhaust peak heating of the steam screw expander are combined, the reasonable grading utilization of energy is improved, and the difficulty that the high back pressure heat supply technology is difficult to adopt due to overhigh circulating return water temperature of the heat supply network is solved.

4. The design of the organic working medium screw expander system is characterized in that gaseous organic working media discharged by the organic working medium screw expander are condensed into low-temperature liquid organic working media by cooling water in the organic working medium condenser, and the low-temperature liquid organic working media enter the organic working medium preheater to reduce the circulating return water temperature of a heat supply network, so that the requirement of high back pressure operation of a second unit is met.

5. The first organic working medium low-temperature evaporator and the second organic working medium low-temperature evaporator are mainly used for reducing the temperature of condensed water, so that the operating conditions of the unit fine processing device are met. The organic working medium intermediate-temperature evaporator and the organic working medium high-temperature evaporator are mainly used for further heating the organic working medium from the organic working medium low-temperature evaporator, so that the temperature of condensed water from the first unit and the temperature of condensed water of the peak heater are preliminarily reduced. The organic working medium low-temperature evaporator, the organic working medium-temperature evaporator and the organic working medium high-temperature evaporator are designed, so that parameters of gaseous organic working medium entering the organic working medium screw expander can be improved, the heat efficiency of the organic working medium screw expander is improved, the temperature of condensate entering the first unit hot well and the second unit hot well can be reduced, the requirement of a fine processing device on the temperature of the condensate is met, and the two purposes are achieved.

One case is provided as follows:

before the thermal power generating unit of a 2X 350MW grade of a power plant is transformed by adopting the technology, the circulating backwater temperature of a heat supply network is 65 ℃, and the high back pressure heat supply technology cannot be transformed due to the high backwater temperature, so that the circulating backwater of the heat supply network is directly heated by adopting middle-exhaust steam extraction for external heat supply, the heat supply load is designed to be 618MW, and the heat supply index is 43W/m²The conversion is that the heat supply area is 1437 km²。

Before transformation, under the rated working condition: in the initial and final heating stages, the power plant power generation load is 598.57MW, the total power plant heat supply load is 372.11MW, the steam extraction heat supply load is 372.11MW, the dead steam heat supply load is 0MW, the power plant power generation heat consumption rate is 6705.31kJ/kWh, and the power plant power generation coal consumption rate is 251.59 g/kWh.

Before transformation, under the rated working condition: in the non-initial stage of heating, the power plant generates 533.52MW of power load, the total heat supply load of the unit is 618MW, wherein the steam extraction heat supply load is 618MW, the dead steam heat supply load is 0MW, the power plant generates 5863.65kJ/kWh of heat consumption rate, and the power plant generates 220.01g/kWh of coal consumption rate.

After the technology is transformed, a 30MW steam screw expander power generation system and a 30MW organic working medium screw expander power generation system are matched, when the return water temperature of a heat supply network is 65 ℃, under the rated working condition:

in the non-severe cold heating period, only the low-pressure cylinder steam exhaust (high back pressure) of the second unit and the first unit is needed for external heating, and part of steam exhaust of the medium-pressure cylinder of the first unit is used for power generation of the steam screw expander. Because the temperature of the circulating backwater of the heat supply network is higher, the circulating backwater of the heat supply network is firstly cooled to 45 ℃ through the working medium organic preheater, the generating load of a unit of the power plant is 593.96MW, the total heating load of the power plant is 618MW, wherein the steam extraction heating load is 0MW, the exhaust steam heating load is 618MW, the heat load utilized by a heat user is 372MW, the generating heat consumption rate of the power plant is 5299.56 kWh/kWh, and the generating coal consumption rate of the power plant is 198.84 g/kWh. Under the working condition, the power generation load of the steam screw expander is 25.7MW, the power generation load of the organic working medium screw expander is 17.56MW, and the total power generation load of the power plant is 637.22 MW.

In the severe cold period of heat supply, the heat is supplied to the outside through the steam exhaust of the second unit, the low-pressure cylinder of the first unit (high back pressure) and the steam exhaust of the steam screw expander, so that the requirements of heat users are met. The temperature of the circulating backwater of the heat supply network is high, so that the circulating backwater of the heat supply network is firstly cooled to 45 ℃ through the working medium organic preheater, the generating load of a unit of the power plant is 593.96MW, the total heating load of the power plant is 841MW, the extracting heating load is 223MW, the exhaust heating load is 618MW, the heat load utilized by a heat user is 618MW, the generating heat consumption rate of the power plant is 3943.04 kWh, and the generating coal consumption rate of the power plant is 147.95 g/kWh. Under the working condition, the power generation load of the steam screw expander is 25.7MW, the power generation load of the organic working medium screw expander is 26.76MW, and the total power generation load of the power plant is 646.42 MW.

It can be known from the above cases that after the improvement, when the return water temperature is 65 ℃, in the non-severe cold period of heat supply, the requirement of a heat user can be met only by externally supplying heat through the low-pressure cylinder steam exhaust (high back pressure) of the second unit and the first unit, under the condition that the heat supply area is not changed, the total power generation load of the power plant is increased by 38.65MW, and the power generation coal consumption rate of the power plant is reduced by 52.74 g/kWh.

Synthesize above-mentioned case and know, through this utility model technical transformation back, when the return water temperature is 65 ℃, in the severe cold period of heat supply, through second unit and first unit low pressure cylinder steam extraction (high back pressure) and the steam screw expander steam extraction external heat supply to satisfy hot user's requirement, under the unchangeable condition of heat supply area, total power generation load has increased 112.9MW, and the power generation coal consumption rate of power plant has reduced 72.06g kWh.

By combining the cases, the coal consumption rate of power generation of the power plant is greatly reduced no matter in the non-severe cold period or the severe cold period of heat supply, the total power generation load of the power plant is increased more, the energy-saving and economic effects are obvious, and the technical prospect is wide.

Example two

In the first embodiment, the organic working medium temperature evaporator and the first organic working medium low temperature evaporator are used for carrying out graded heat exchange, which is beneficial to heat recovery. However, the present invention is not limited to this, referring to fig. 5, in this embodiment, the organic medium temperature evaporator 18 is not included, that is, compared to the first embodiment, the organic medium temperature evaporator 18 is removed, the pipeline where the fifteenth valve 38 is located is removed, the pipeline where the thirteenth valve 41 is located is removed, the pipeline where the tenth valve 39 is located is removed, the seventeenth valve 36 and the fourteenth valve 43 are directly connected by the pipeline without the eighteenth valve 40, and the condensed water outlet of the first unit heat supply network condenser 9 is directly connected to the second valve 45 by the pipeline.

Therefore, in this embodiment, the condensed water outlet of the first unit heat supply network condenser 9 is communicated with the condensed water inlet of the first organic working medium low-temperature evaporator 16, and the organic working medium outlets of the first organic working medium low-temperature evaporator 16 and the second organic working medium low-temperature evaporator 17 are selectively communicated with the organic working medium inlet of the organic working medium screw expander 4. The organic working medium inlet of the organic working medium high-temperature evaporator 19 is selectively communicated with the organic working medium outlets of the first organic working medium low-temperature evaporator 16 and the second organic working medium low-temperature evaporator 17. The organic working medium outlet of the organic working medium high-temperature evaporator 19 is selectively communicated with the organic working medium inlet of the organic working medium screw expander 4.

The beginning and end heat supply stages are characterized in that only the second unit is put into the working mode of high back pressure operation, the first unit still operates in pure condensation mode, and the steam work doing equipment, the peak heater 10, the steam exhaust heat exchanger 15, the steam side cooling water heat dissipation tower 46 and the organic working medium high-temperature evaporator 19 do not work. Referring to fig. 6, the detailed description of the method at this stage is consistent with the detailed description corresponding to fig. 2, and is not repeated.

The first heat supply mode is characterized in that, referring to fig. 7, the first unit and the second unit are both put into the working mode of high back pressure operation, and the steam exhausted from the pressure cylinder in the first unit is completely fed into the low pressure cylinder 2 of the first unit through the pipeline with the first valve 29, so that the steam work equipment, the peak heater 10, the steam exhaust heat exchanger 15, the steam side cooling water heat dissipation tower 46 and the organic working medium high temperature evaporator 19 do not work. Specifically, the method comprises the following steps:

the first valve 29, the second valve 45, the seventh valve 35, the eighth valve 50, the eleventh valve 34, the twelfth valve 33, and the nineteenth valve 51 are opened, and the remaining valves are closed.

The cooled heat supply network circulating backwater sequentially passes through a second unit heat supply network condenser 8 and a first unit heat supply network condenser 9, the exhaust steam of the low-pressure cylinder of the second unit enters the second unit heat supply network condenser 8, and the exhaust steam of the low-pressure cylinder of the first unit enters the first unit heat supply network condenser 9. Therefore, the cooled circulating backwater of the heat supply network exchanges heat with the steam exhausted by the low-pressure cylinder of the second unit and the steam exhausted by the low-pressure cylinder of the first unit in sequence, and enters a heat supply pipeline through the peak heater 10 (only through without heating) after being heated by two stages, and is conveyed to a heat user 11 for heat supply. And then the circulating return water of the heat supply network flows out of the heat user 11, enters a heat supply loop, returns to the organic working medium preheater 13 and exchanges heat with the liquid organic working medium again. Thus, the heat supply network circulating water forms a circulation.

The exhaust steam of the low-pressure cylinder of the second unit is condensed into condensed water of the second unit, the condensed water is discharged from a heat supply network condenser 8 of the second unit to a second organic working medium low-temperature evaporator 17, the exhaust steam of the low-pressure cylinder of the first unit is condensed into condensed water of the first unit, the condensed water is discharged from a heat supply network condenser 9 of the first unit, and the condensed water is sent to a first organic working medium low-temperature evaporator 16 through a pipeline with a second valve 45.

The heated liquid organic working medium is divided into two parts. And a part of the heated liquid organic working medium enters the second organic working medium low-temperature evaporator 17 through a pipeline with a seventh valve 35 to exchange heat with the condensed water of the second unit, the heated liquid organic working medium is heated to form a gaseous organic working medium of the second unit, and meanwhile, the condensed water of the second unit is cooled. The other part of the heated liquid organic working medium enters the first organic working medium low-temperature evaporator 16 through a pipeline with a seventh valve 35 and an eighth valve 50 to exchange heat with the condensed water of the first unit, the heated liquid organic working medium is heated to form the gaseous organic working medium of the first unit, and meanwhile, the condensed water of the first unit is cooled. In summary, the heated liquid organic working medium absorbs the heat of the condensed water of the second unit and the condensed water of the first unit to form a gaseous organic working medium. The first unit gaseous working medium and the second unit gaseous working medium are named only by distinguishing according to flow paths, and are completely the same and are changed from the same liquid working medium.

The gaseous organic working medium of the first unit and the gaseous organic working medium of the second unit are mixed through a pipeline with an eleventh valve 34 and a twelfth valve 33, enter the organic working medium screw expander 4 to do work, and drag the organic working medium side generator 7 to generate electricity through the organic working medium side speed reducer 6. The exhaust steam and cooling water of the organic working medium screw expander 4 enter the organic working medium condenser 14, the exhaust steam of the organic working medium screw expander 4 exchanges heat with the cooling water to form liquid organic working medium for exchanging heat with the circulating return water of the heat supply network, and the liquid organic working medium is sent to the organic working medium preheater 13 through a pipeline with an organic working medium circulating pump 20. The heated cooling water enters the cooling water heat dissipation tower 21 at the organic working medium side for heat dissipation and then is recycled. Therefore, the heated gaseous organic working medium formed after the heat exchange between the gaseous organic working medium of the first unit and the gaseous organic working medium of the second unit and the condensed water of the first unit and the condensed water of the second unit is directly used for doing work and generating electricity.

Thus, an organic working medium Rankine cycle is formed.

In addition, the first unit condensed water and the cooled first unit condensed water formed by the heat exchange of the heated liquid organic working medium are treated by the first unit fine treatment device 27 to purify the water quality. Meanwhile, the second unit condensed water is subjected to heat exchange with the heated liquid organic working medium to form cooled second unit condensed water, and the cooled second unit condensed water is treated by a second unit fine treatment device 28 to purify water.

The second heat supply mode is characterized in that, referring to fig. 8, part of the steam discharged by the pressure cylinder in the first unit enters the low pressure cylinder 2 of the first unit through the pipeline with the first valve 29, and the other part enters the steam work equipment through the pipeline with the third valve 30 to do work and generate power, so that the steam work equipment, the peak heater 10, the steam discharge heat exchanger 15, the steam side cooling water heat dissipation tower 46 and the organic working medium high-temperature evaporator 19 are in work. Specifically, the method comprises the following steps:

the first valve 29, the second valve 45, the third valve 30, the fourth valve 32, the fifth valve 31, the sixth valve 44, the seventh valve 35, the eighth valve 50, the ninth valve 37, the tenth valve 33, the fourteenth valve 43, the sixteenth valve 42, and the nineteenth valve 51 are opened, and the remaining valves are closed.

The cooled heat supply network circulating backwater sequentially passes through a second unit heat supply network condenser 8, a first unit heat supply network condenser 9 and a peak heater 10, the exhaust steam of a second unit low-pressure cylinder enters the second unit heat supply network condenser 8, the exhaust steam of the first unit low-pressure cylinder enters the first unit heat supply network condenser 9, a steam screw expander 5 receives the exhaust steam of the first unit medium-pressure cylinder to do work, a steam side speed reducer 48 and a steam side generator 49 are dragged to generate electricity, one part of the steam (namely the exhaust steam of a steam work equipment) exhausted by the steam screw expander 5 enters the peak heater 10 through a pipeline with a fifth valve 31, and the other part of the steam enters an exhaust steam heat exchanger 15 through a pipeline with a fourth valve 32. Therefore, the cooled circulating backwater of the heat supply network exchanges heat with the steam exhausted by the second unit low-pressure cylinder, the steam exhausted by the first unit low-pressure cylinder and the steam exhausted by the steam screw expander in sequence, and enters a heat supply pipeline after being heated in a three-stage mode and is conveyed to a heat user 11 for heat supply. And then the circulating return water of the heat supply network flows out of the heat user 11, enters a heat supply loop, returns to the organic working medium preheater 13 and exchanges heat with the liquid organic working medium again. Thus, the heat supply network circulating water forms a circulation.

The exhaust steam of the low-pressure cylinder of the second unit is condensed into condensed water of the second unit, the condensed water is discharged from a heat supply network condenser 8 of the second unit to a second organic working medium low-temperature evaporator 17, the exhaust steam of the low-pressure cylinder of the first unit is condensed into condensed water of the first unit, the condensed water is discharged from a heat supply network condenser 9 of the first unit, and the condensed water is sent to a first organic working medium low-temperature evaporator 16 through a pipeline with a second valve 45. Condensed water after the exhaust steam of the steam screw expander 5 is condensed in the peak heater 10 is discharged from the peak heater 10 to the organic working medium high-temperature evaporator 19.

The heated liquid organic working medium is divided into two parts. And a part of the heated liquid organic working medium enters the second organic working medium low-temperature evaporator 17 through a pipeline with a seventh valve 35 to exchange heat with the condensed water of the second unit, the heated liquid organic working medium is heated to form a gaseous organic working medium of the second unit, and meanwhile, the condensed water of the second unit is cooled. The other part of the heated liquid organic working medium enters the first organic working medium low-temperature evaporator 16 through a pipeline with an eighth valve 50 and a seventh valve 35 to exchange heat with the condensed water of the first unit, the heated liquid organic working medium is heated to form the gaseous organic working medium of the first unit, and meanwhile, the condensed water of the first unit is cooled. In summary, the heated liquid organic working medium absorbs the heat of the condensed water of the second unit and the condensed water of the first unit to form a gaseous organic working medium.

The gaseous organic working medium of the first unit and the gaseous organic working medium of the second unit are mixed through a pipeline with a ninth valve 37 and a fourteenth valve 43 and enter the organic working medium high-temperature evaporator 19, condensed water obtained after exhaust steam of the steam screw expander 5 is condensed in the peak heater 10 exchanges heat with the gaseous organic working medium in the organic working medium high-temperature evaporator 19 to form heated gaseous organic working medium and cooled condensed water, the heated gaseous organic working medium enters the organic working medium screw expander 4 through a pipeline with a sixteenth valve 42 and a tenth valve 33 to apply work, and the organic working medium side generator 7 is driven by the organic working medium side speed reducer 6 to generate electricity. The exhaust steam and the cooling water of the organic working medium screw expander 4 enter the organic working medium condenser 14, the exhaust steam of the organic working medium screw expander 4 exchanges heat with the cooling water to form a liquid organic working medium for exchanging heat with the circulating return water of the heat supply network, and the heated cooling water enters the cooling water heat dissipation tower 21 at the organic working medium side for heat dissipation and then is recycled. Thus, an organic working medium Rankine cycle is formed.

In addition, the cooled condensate formed simultaneously with the heated gaseous organic working medium enters the first organic working medium low-temperature evaporator 16 via a line with a sixth valve 44 and is also used for heat exchange with the heated liquid organic working medium therein, and the condensate discharged from the first organic working medium low-temperature evaporator 16 is collectively referred to as "cooled first unit condensate".

In addition, the cooled first unit condensed water is treated by the first unit fine treatment device 27 to purify the water quality. Meanwhile, the second unit condensed water is subjected to heat exchange with the heated liquid organic working medium to form cooled second unit condensed water, and the cooled second unit condensed water is treated by a second unit fine treatment device 28 to purify water.

Compared with the first embodiment, the first embodiment has the advantages of removing the effect of multi-stage heat exchange of the organic working medium-temperature evaporator 18.

EXAMPLE III

Referring to fig. 9, in the present embodiment, the organic medium temperature evaporator 18 and the organic medium high temperature evaporator 19 are not included, that is, compared with the first embodiment, the organic medium temperature evaporator 18 and the organic medium high temperature evaporator 19 are removed, the pipeline where the fifteenth valve 38 is located is removed, the pipeline where the ninth valve 37 is located is removed, the pipeline where the thirteenth valve 41 is removed, the pipeline where the tenth valve 39 is located is removed, the pipelines where the seventeenth valve 36, the eighteenth valve 40 and the fourteenth valve 43 are located are removed, and the pipeline where the sixteenth valve 42 is located is removed, the condensed water outlet of the first unit heat grid condenser 9 is directly communicated with the second valve 45 through the pipeline, and the condensed water outlet of the spike heater 10 is directly communicated with the sixth valve 44 through the pipeline.

Therefore, in this embodiment, the condensed water outlet of the first unit heat supply network condenser 9 is communicated with the condensed water inlet of the first organic working medium low-temperature evaporator 16, and the organic working medium outlets of the first organic working medium low-temperature evaporator 16 and the second organic working medium low-temperature evaporator 17 are selectively communicated with the organic working medium inlet of the organic working medium screw expander 4. The condensed water outlet of the peak heater 10 is selectively communicated with the condensed water inlet of the first organic working medium low-temperature evaporator 16.

The beginning and end heating phases are characterized in that only the second unit is put into the working mode of high back pressure operation, the first unit still operates in pure condensation mode, and the steam work doing equipment, the peak heater 10, the steam exhaust heat exchanger 15 and the steam side cooling water heat dissipation tower 46 do not work. Referring to fig. 10, the detailed description of the method at this stage is identical to that of fig. 2, and is not repeated.

The first heating mode is characterized in that, referring to fig. 11, the first unit and the second unit are both put into operation with high back pressure, and the exhaust steam of the pressure cylinder in the first unit is all fed into the low pressure cylinder 2 of the first unit through the pipeline with the first valve 29, so that the steam work equipment, the peak heater 10, the exhaust steam heat exchanger 15 and the steam side cooling water heat dissipation tower 46 do not participate in operation. Specifically, the first valve 29, the second valve 45, the seventh valve 35, the eighth valve 50, the eleventh valve 34, the twelfth valve 33, and the nineteenth valve 51 are opened, and the remaining valves are closed. Referring to fig. 11, the detailed description of the method of this mode is identical to that of fig. 7, and is not repeated.

The second heating mode is characterized in that, referring to fig. 12, part of the steam discharged from the pressure cylinder in the first unit enters the low pressure cylinder 2 of the first unit through the pipeline with the first valve 29, and the other part enters the steam power device through the pipeline with the third valve 30 to do work and generate power, so that the steam power device, the peak heater 10, the steam discharge heat exchanger 15 and the steam side cooling water heat dissipation tower 46 take part in the work. Specifically, the method comprises the following steps:

the first valve 29, the second valve 45, the third valve 30, the fourth valve 32, the fifth valve 31, the sixth valve 44, the seventh valve 35, the eighth valve 50, the tenth valve 33, the eleventh valve 34, and the nineteenth valve 51 are opened.

The exhaust steam of the low-pressure cylinder of the second unit is condensed into condensed water of the second unit, the condensed water is discharged from a heat supply network condenser 8 of the second unit to a second organic working medium low-temperature evaporator 17, the exhaust steam of the low-pressure cylinder of the first unit is condensed into condensed water of the first unit, the condensed water is discharged from a heat supply network condenser 9 of the first unit, and the condensed water is sent to a first organic working medium low-temperature evaporator 16 through a pipeline with a second valve 45. The condensed water condensed in the peak heater 10 by the exhaust steam of the steam screw expander 5 is discharged from the peak heater 10 and sent to the first organic working medium low-temperature evaporator 16 through a pipeline with a sixth valve 44.

The heated liquid organic working medium is divided into two parts. And a part of the heated liquid organic working medium enters the second organic working medium low-temperature evaporator 17 through a pipeline with a seventh valve 35 to exchange heat with the condensed water of the second unit, the heated liquid organic working medium is heated to form a gaseous organic working medium of the second unit, and meanwhile, the condensed water of the second unit is cooled. The other part of the heated liquid organic working medium enters the first organic working medium low-temperature evaporator 16 through a pipeline with a seventh valve 35 and an eighth valve 50 to exchange heat with the mixed condensed water of the first unit and the condensed water of the exhaust steam of the steam screw expander, the heated liquid organic working medium is heated to form the gaseous organic working medium of the first unit, and meanwhile, the condensed water of the first unit and the condensed exhaust steam of the steam screw expander is cooled. In conclusion, the heated liquid organic working medium absorbs the heat of the condensed water of the second unit and the condensed water of the first unit, and the condensed water after the exhaust steam of the steam screw expander is condensed in the peak heater, so as to form the gaseous organic working medium.

The first group of gaseous organic working media and the second group of gaseous organic working media are mixed and enter the organic working media screw expander 4 to do work, and the mixture is dragged by the organic working media side speed reducer to generate electricity. The exhaust steam and the cooling water of the organic working medium screw expander 4 enter the organic working medium condenser 14, the exhaust steam of the organic working medium screw expander 4 exchanges heat with the cooling water to form a liquid organic working medium for exchanging heat with the circulating return water of the heat supply network, and the heated cooling water enters the cooling water heat dissipation tower 21 at the organic working medium side for heat dissipation and then is recycled. Thus, an organic working medium Rankine cycle is formed.

Compared with the first embodiment, the first embodiment has the advantages of removing the effect of multi-stage heat exchange of the organic working medium intermediate-temperature evaporator 18 and the organic working medium high-temperature evaporator 19. In the utility model, the serial numbers of the valves are only used for distinguishing the valves at different positions, and do not represent the position relation before and after the valves and the importance degree of the valves, and any valve in the valves can be reserved and removed according to the requirement in each embodiment of the utility model.

It can be seen from the above 3 embodiments that one of the key points of the present invention is to have at least one unit capable of operating at high back pressure, and it can be understood that, if only one unit capable of operating at high back pressure is adopted, the first unit and the associated devices in the first to third embodiments can be retained, referring to fig. 13, the present invention further includes an organic working medium evaporator, an organic working medium preheater, an organic working medium screw expander, and an organic working medium condenser. The unit capable of operating at high back pressure comprises a low-pressure cylinder and a heat supply network condenser, wherein a steam inlet of the heat supply network condenser is communicated with a steam outlet of the low-pressure cylinder; a condensed water outlet of the heat supply network condenser is communicated with a condensed water inlet of the organic working medium evaporator, and an organic working medium inlet of the organic working medium evaporator is selectively communicated with an organic working medium outlet of the organic working medium preheater; an organic working medium outlet of the organic working medium evaporator is selectively communicated with an organic working medium inlet of the organic working medium screw expander; an organic working medium outlet of the organic working medium screw expander is communicated with an organic working medium inlet of the organic working medium condenser, and an organic working medium outlet of the organic working medium condenser is communicated with an organic working medium inlet of the organic working medium preheater; a heat supply network circulating water return inlet of the organic working medium preheater is used for being communicated with a heat user, and a heat supply network circulating water return outlet of the organic working medium preheater is communicated with a heat supply network circulating water inlet of the heat supply network condenser; and a heat supply network circulating water outlet of the heat supply network condenser is communicated with a heat user. Preferably, the high-pressure steam generating set further comprises a steam power device and a peak heater, the high-back-pressure running set further comprises an intermediate pressure cylinder, a steam exhaust outlet of the intermediate pressure cylinder is communicated with a steam inlet of the low pressure cylinder and a steam inlet of the steam power device in an adjustable flow manner, and a steam outlet of the steam power device is communicated with a steam inlet of the peak heater; a heat supply network circulating water outlet of the heat supply network condenser is communicated with a heat supply network circulating water inlet of the peak heater, and the heat supply network circulating water outlet of the peak heater is communicated with a heat user; the organic working medium evaporator comprises an organic working medium low-temperature evaporator and an organic working medium high-temperature evaporator, and optionally comprises an organic working medium-temperature evaporator; the condensed water outlet of the peak heater is communicated with the condensed water inlet of the organic working medium high-temperature evaporator, and the condensed water outlet of the organic working medium high-temperature evaporator is selectively communicated with the condensed water inlet of the organic working medium low-temperature evaporator. The specific connection relationships have been described in the first to third embodiments, and thus are not described in detail.

When the organic working medium temperature evaporator is included: referring to fig. 13, a condensed water outlet of the heat supply network condenser is communicated with a condensed water inlet of the organic working medium intermediate temperature evaporator, the condensed water outlet of the organic working medium intermediate temperature evaporator is selectively communicated with the condensed water inlet of the organic working medium low temperature evaporator, an organic working medium outlet of the organic working medium low temperature evaporator is selectively communicated with an organic working medium inlet of the organic working medium intermediate temperature evaporator, the organic working medium inlet of the organic working medium high temperature evaporator is selectively communicated with an organic working medium outlet of the organic working medium intermediate temperature evaporator, and the organic working medium outlet of the organic working medium low temperature evaporator, the organic working medium intermediate temperature evaporator and the organic working medium outlet of the organic working medium high temperature evaporator are selectively communicated with an organic working medium inlet of the organic working medium screw expander.

When the medium-temperature evaporator of the organic working medium is not included: referring to the first unit and the equipment associated with the first unit in fig. 5, the organic working medium outlet of the organic working medium low-temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium high-temperature evaporator, and the organic working medium outlet of the organic working medium low-temperature evaporator and the organic working medium outlet of the organic working medium high-temperature evaporator are selectively communicated with the organic working medium inlet of the organic working medium screw expander.

In the above 3 embodiments, on the basis of having one unit capable of operating at high back pressure, two units capable of operating at high back pressure are introduced to change more heat supply modes.

While the utility model has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the utility model. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims

1. A combined heat and power system is characterized by comprising a unit capable of operating at high back pressure, an organic working medium evaporator, an organic working medium preheater, an organic working medium screw expander and an organic working medium condenser;

the unit capable of operating at high back pressure comprises a low pressure cylinder and a heat supply network condenser, wherein a steam inlet of the heat supply network condenser is communicated with a steam outlet of the low pressure cylinder; a condensed water outlet of the heat supply network condenser is communicated with a condensed water inlet of the organic working medium evaporator, and an organic working medium inlet of the organic working medium evaporator is selectively communicated with an organic working medium outlet of the organic working medium preheater;

an organic working medium outlet of the organic working medium evaporator is selectively communicated with an organic working medium inlet of the organic working medium screw expander;

an organic working medium outlet of the organic working medium screw expander is communicated with an organic working medium inlet of the organic working medium condenser, and an organic working medium outlet of the organic working medium condenser is communicated with an organic working medium inlet of the organic working medium preheater;

the heat supply network circulating water return inlet of the organic working medium preheater is used for being communicated with a heat user, and the heat supply network circulating water return outlet of the organic working medium preheater is communicated with the heat supply network circulating water inlet of the heat supply network condenser;

and a heat supply network circulating water outlet of the heat supply network condenser is communicated with a heat user.

2. The cogeneration system of claim 1, further comprising a steam power plant, a spike heater;

the unit capable of operating at high back pressure further comprises an intermediate pressure cylinder, wherein the steam exhaust outlet of the intermediate pressure cylinder is communicated with the steam inlet of the low pressure cylinder and the steam inlet of the steam work doing equipment in an adjustable flow manner, and the steam outlet of the steam work doing equipment is communicated with the steam inlet of the spike heater;

a heat supply network circulating water outlet of the heat supply network condenser is communicated with a heat supply network circulating water inlet of the peak heater, and the heat supply network circulating water outlet of the peak heater is communicated with a heat user;

the organic working medium evaporator comprises an organic working medium low-temperature evaporator and an organic working medium high-temperature evaporator, and optionally comprises an organic working medium-temperature evaporator;

the condensed water outlet of the peak heater is communicated with the condensed water inlet of the organic working medium high-temperature evaporator, and the condensed water outlet of the organic working medium high-temperature evaporator is selectively communicated with the condensed water inlet of the organic working medium low-temperature evaporator;

when the organic working medium temperature evaporator is included:

the condensation water outlet of the heat supply network condenser is communicated with the condensation water inlet of the organic working medium temperature evaporator, the condensation water outlet of the organic working medium temperature evaporator is selectively communicated with the condensation water inlet of the organic working medium low temperature evaporator, the organic working medium outlet of the organic working medium low temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium temperature evaporator, the organic working medium inlet of the organic working medium high temperature evaporator is selectively communicated with the organic working medium outlet of the organic working medium temperature evaporator, and the organic working medium outlet of the organic working medium low temperature evaporator, the organic working medium temperature evaporator and the organic working medium outlet of the organic working medium high temperature evaporator are selectively communicated with the organic working medium inlet of the organic working medium screw expander;

when the organic working medium temperature evaporator is not included:

the organic working medium outlet of the organic working medium low-temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium high-temperature evaporator, and the organic working medium outlet of the organic working medium low-temperature evaporator and the organic working medium outlet of the organic working medium high-temperature evaporator are selectively communicated with the organic working medium inlet of the organic working medium screw expander.

3. The cogeneration system of claim 1, wherein said set capable of high back pressure operation comprises a first set and a second set;

when the first unit and the second unit run at the same high back pressure, the back pressure of the low-pressure cylinder of the first unit can be higher than that of the low-pressure cylinder of the second unit;

the first unit comprises a first unit low-pressure cylinder and a first unit heat supply network condenser, a steam inlet of the first unit heat supply network condenser is selectively communicated with a steam outlet of the first unit low-pressure cylinder, the second unit comprises a second unit low-pressure cylinder and a second unit heat supply network condenser, and a steam inlet of the second unit heat supply network condenser is communicated with a steam outlet of the second unit low-pressure cylinder;

the combined heat and power system comprises a first organic working medium low-temperature evaporator and a second organic working medium low-temperature evaporator, a condensed water outlet of a heat supply network condenser of the second unit is communicated with a condensed water inlet of the second organic working medium low-temperature evaporator, and organic working medium inlets of the first organic working medium low-temperature evaporator and the second organic working medium low-temperature evaporator are selectively communicated with an organic working medium outlet of the organic working medium preheater;

the combined heat and power system also optionally comprises an organic working medium temperature evaporator;

under the condition that the organic working medium temperature evaporator is not included, a condensed water outlet of the first unit heat supply network condenser is communicated with a condensed water inlet of the first organic working medium low temperature evaporator, and organic working medium outlets of the first organic working medium low temperature evaporator and the second organic working medium low temperature evaporator are selectively communicated with an organic working medium inlet of the organic working medium screw expander;

under the condition of comprising an organic working medium intermediate temperature evaporator, a condensed water outlet of the first unit heat supply network condenser is communicated with a condensed water inlet of the organic working medium intermediate temperature evaporator, a condensed water outlet of the organic working medium intermediate temperature evaporator is selectively communicated with a condensed water inlet of the first organic working medium low temperature evaporator, organic working medium outlets of the first organic working medium low temperature evaporator and the second organic working medium low temperature evaporator are selectively communicated with an organic working medium inlet of the organic working medium intermediate temperature evaporator, an organic working medium outlet of the first organic working medium low temperature evaporator, an organic working medium outlet of the second organic working medium low temperature evaporator, an organic working medium outlet of the organic working medium intermediate temperature evaporator and an organic working medium inlet of the organic working medium screw expander are selectively communicated;

the heat supply network circulating water return inlet of the organic working medium preheater is used for being communicated with a heat user, and the heat supply network circulating water return outlet of the organic working medium preheater is communicated with the heat supply network circulating water inlet of the second unit heat supply network condenser;

and a heat supply network circulating water outlet of the second unit heat supply network condenser is communicated with a heat supply network circulating water inlet of the first unit heat supply network condenser, and a heat supply network circulating water outlet of the first unit heat supply network condenser is communicated with a heat user.

4. The cogeneration system of claim 3, further comprising a steam work device, a spike heater, an organic working medium high-temperature evaporator and the organic working medium intermediate-temperature evaporator;

the first unit further comprises a first unit intermediate pressure cylinder, a steam exhaust outlet of the first unit intermediate pressure cylinder is communicated with a steam inlet of the first unit low pressure cylinder and a steam inlet of the steam work-doing equipment in an adjustable flow manner, and a steam outlet of the steam work-doing equipment is communicated with a steam inlet of the spike heater;

the condensed water outlet of the peak heater is communicated with the condensed water inlet of the organic working medium high-temperature evaporator, the condensed water outlet of the organic working medium high-temperature evaporator is selectively communicated with the condensed water inlet of the first organic working medium low-temperature evaporator, the organic working medium inlet of the organic working medium high-temperature evaporator is selectively communicated with the organic working medium outlet of the organic working medium-temperature evaporator, and the organic working medium outlet of the organic working medium high-temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium screw expander;

and a heat supply network circulating water outlet of the first unit heat supply network condenser is communicated with a heat supply network circulating water inlet of the peak heater, and the heat supply network circulating water outlet of the peak heater is communicated with a heat user.

5. The cogeneration system of claim 3, further comprising a steam work device, a spike heater, an organic working medium high-temperature evaporator, excluding the organic working medium-temperature evaporator;

the condensed water outlet of the peak heater is communicated with the condensed water inlet of the organic working medium high-temperature evaporator, the organic working medium inlet of the organic working medium high-temperature evaporator is selectively communicated with the organic working medium outlets of the first organic working medium low-temperature evaporator and the second organic working medium low-temperature evaporator, and the organic working medium outlet of the organic working medium high-temperature evaporator is selectively communicated with the organic working medium inlet of the organic working medium screw expander;

6. The cogeneration system of claim 3, further comprising a steam power plant, a spike heater, excluding said organic working medium intermediate temperature evaporator; the first unit further comprises a first unit intermediate pressure cylinder, a steam exhaust outlet of the first unit intermediate pressure cylinder is communicated with a steam inlet of the first unit low pressure cylinder and a steam inlet of the steam work-doing equipment in an adjustable flow manner, and a steam outlet of the steam work-doing equipment is communicated with a steam inlet of the spike heater;

a condensed water outlet of the peak heater is selectively communicated with a condensed water inlet of the first organic working medium low-temperature evaporator;

7. The cogeneration system according to any one of claims 2 to 6,

the unit capable of operating at high back pressure further comprises a hot well and a fine processing device, wherein a condensed water outlet of the organic working medium low-temperature evaporator is communicated with an inlet of the hot well, and an outlet of the hot well is communicated with an inlet of the fine processing device.

8. The cogeneration system according to any one of claims 1 to 6, further comprising an organic working medium side cooling water heat dissipation tower;

a cooling water inlet of the organic working medium condenser is communicated with an outlet of the organic working medium side cooling water heat dissipation tower;

and a cooling water outlet of the organic working medium condenser is communicated with an inlet of the organic working medium side cooling water heat dissipation tower.

9. The cogeneration system according to any one of claims 2 and 4 to 6, further comprising a steam discharge heat exchanger and a steam side cooling water heat rejection column;

the steam inlet of the steam exhaust heat exchanger is communicated with the steam outlet of the steam work doing equipment in an adjustable flow mode, the cooling water inlet of the steam exhaust heat exchanger is communicated with the outlet of the steam side cooling water heat dissipation tower, and the cooling water outlet of the steam exhaust heat exchanger is communicated with the inlet of the steam side cooling water heat dissipation tower.

10. The cogeneration system of any one of claims 2, 4-6,

the steam work equipment comprises a steam screw expander/steam back press, a steam side speed reducer and a steam side generator;

the steam side generator is connected with the steam screw expander/steam back press through a steam side speed reducer.