Flexible peak shaving system and method driven by waste heat of cogeneration unit

Abstract

The invention relates to the technical field of combined heat and power generation, in particular to a flexible peak shaving system and method driven by waste heat of a combined heat and power generation unit. A low-temperature waste heat power generation circulation unit composed of a waste heat evaporator, a turbine, a first power generator, a working medium condenser and a working medium compressor and a heat pump waste heat heat supply circulation unit composed of a condenser, a compressor and an evaporator are efficiently coupled with a conventional combined heat and power generation steam-water circulation unit and a heat supply network heat supply unit. The heat supply network drainage waste heat is used as a driving heat source, the heat supply network drainage waste heat is fully recycled, thermoelectric decoupling is achieved, the peak regulation and frequency modulation requirements of the combined heat and power generation unit are met, the flexibility of an electric power system is improved, the electric power system can better cope with load fluctuation, and the power supply efficiency of the combined heat and power generation unit is improved. The gradient utilization of energy is realized, and the configuration of power resources is optimized. The problems that in the prior art, the heat supply network drainage waste heat utilization rate is low, and the peak regulation capacity of a thermal power generating unit is poor are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cogeneration, and in particular to a flexible peak-shaving system and method driven by waste heat of a cogeneration unit. Background Art

[0002] The capacity of new energy units has accounted for more than half of the installed capacity of the power system, and the amount of wind power and photovoltaic power connected to the grid has gradually increased. Due to the intermittent and unstable nature of new energy, the power grid needs to withstand scenarios with greater impact and fluctuations. As the amount of new energy connected to the grid increases, the requirements for peak load regulation of thermal power units are becoming more stringent. Peak load regulation of thermal power units is an important part of the power system, which means that thermal power units adjust their output power according to changes in the load demand of the power grid to maintain the stable operation of the power grid. In the power system, the load is constantly changing, and the power supply needs to remain relatively stable. Therefore, when the load fluctuates, it is necessary to compensate by adjusting the output power of the generator to maintain the balance of supply and demand in the power system. As one of the main power generation equipment in the power system, the peak load regulation capability of thermal power units is crucial to the stable operation of the entire system.

[0003] With the gradual implementation of electricity spot trading market policies, the on-grid electricity price of thermal power fluctuates sharply within a dispatching day. In provinces with large photovoltaic installed capacity, the amount of photovoltaic power grid-connected increases sharply at noon, and the on-grid electricity price of thermal power has appeared inverted. The on-grid electricity price of thermal power has also been inverted at night in provinces with large wind turbine installed capacity. For cogeneration units that carry residential heating heat load, due to their operation mode of determining electricity by heat, their peak-shaving and frequency-regulating capabilities are insufficient, resulting in substantial losses in the spot trading market, and the economic performance of the units is poor throughout the year.

[0004] In response to the latest requirements for the steam-water circulation quality of cogeneration units, the heat network drain is not allowed to enter the deaerator directly, and needs to be purified together with the condensate through the condensate polishing device. The heat network drain temperature is relatively high, and there is a large amount of waste heat that can be utilized. Therefore, how to efficiently utilize the waste heat of the heat network drain and improve the peak-shaving heating flexibility of the cogeneration unit is the best way to improve energy utilization and reduce energy supply costs. Summary of the invention

[0005] In view of the problems in the prior art of low utilization rate of waste heat from heat network drainage and poor peak-shaving capability of thermal power units, the present invention provides a flexible peak-shaving system and method driven by waste heat from a cogeneration unit.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a waste heat driven flexible peak load regulation system of a cogeneration unit, comprising at least a cooling tower, a heat network heater, a waste heat evaporator, a turbine, a first generator, a working fluid condenser, a working fluid compressor, an evaporator, a compressor and a condenser; The return water from the heating network enters the heating network heater through the condenser and is heated to supply water to the heating network; Part of the exhaust steam from the medium-pressure cylinder in the conventional cogeneration steam-water circulation unit enters the low-pressure cylinder to perform work, and the other part is heated for the water supply of the heat network through the heat network heater; after the heat network drain water from the heat network heater enters the waste heat evaporator, the turbine is driven to drive the first generator to generate electricity and the working fluid compressor to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged by the turbine enters the working fluid condenser to condense and release heat, and the condensed organic working fluid enters the working fluid compressor to be compressed and increased in pressure, and enters the waste heat evaporator; The circulating water at the outlet of the working medium condenser is combined with the circulating water at the outlet of the condenser and is divided into two paths, one of which enters the evaporator to be cooled, and the other enters the cooling tower for spraying and cooling; the circulating water cooled by the evaporator and the circulating water cooled by the cooling tower are combined and divided into two paths, one of which enters the condenser and the other enters the working medium condenser; the working medium inside the condenser absorbs the waste heat of the circulating water and evaporates in the evaporator, and then enters the condenser after being compressed by the compressor to condense and release heat to heat the heat network return water.

[0007] Optionally, a circulating water pump is provided on the busbar where the circulating water cooled by the evaporator and the circulating water cooled by the cooling tower are combined.

[0008] Optionally, a first circulating water electric regulating valve is provided at the outlet of the working medium condenser.

[0009] Optionally, a heat network circulating water pump is provided at the heat network return water inlet of the condenser.

[0010] Optionally, a second circulating water electric regulating valve is provided between the evaporator and the cooling tower.

[0011] Optionally, an expansion valve is provided between the working medium inlet of the condenser and the working medium outlet of the evaporator.

[0012] Optionally, a steam electric regulating valve is provided between the medium-pressure cylinder and the heating network heater.

[0013] Optionally, the conventional cogeneration steam-water circulation unit comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a deaerator, a high-pressure heater group, a second generator, a condenser and a low-pressure heater group; The high-pressure feed water absorbs the heat of the flue gas in the boiler and evaporates into superheated steam, which enters the high-pressure cylinder to do work. The exhaust steam of the high-pressure cylinder is reheated by the boiler and enters the medium-pressure cylinder to do work. The exhaust steam of the medium-pressure cylinder is divided into two paths, one of which enters the low-pressure cylinder to continue to do work, and the other enters the heat network heater to heat the circulating water of the heat network. The high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder drive the second generator to generate electricity through the shaft to realize external power supply. The exhaust steam of the low-pressure cylinder releases heat and condenses through the condenser, and the waste heat at the cold end is absorbed by the circulating water. The condensed water enters the low-pressure heater group and is heated by extraction steam. The heated condensed water enters the deaerator for deoxygenation, and is heated by the high-pressure heater group before being sent back to the boiler to complete the steam-water cycle.

[0014] Optionally, a feed water pump is provided between the deaerator and the high-pressure heater group; and a condensate water pump is provided between the condenser and the low-pressure heater group.

[0015] The present invention provides a method for peak shaving using the above-mentioned flexible peak shaving system driven by waste heat from a cogeneration unit, comprising: When the cogeneration unit needs a peak load, the exhaust volume of the medium-pressure cylinder entering the heat network heater is reduced, and the water output of the circulating water at the outlet of the working fluid condenser is reduced at the same time, so that the amount of circulating water entering the evaporator is increased, so that the working fluid inside the evaporator absorbs more waste heat of the circulating water to evaporate, and the heat network return water is heated by the condenser for the first stage, and the heated heat network return water is heated by the heat network heater for the second stage to become the heat network supply water; after the water discharge waste heat of the heat network heater enters the waste heat evaporator, the turbine is driven to drive the first generator to generate electricity and the working fluid compressor to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged by the turbine enters the working fluid condenser to condense and release heat, and the condensed organic working fluid enters the working fluid compressor for compression and pressure increase, and enters the waste heat evaporator to realize the water discharge waste heat power generation cycle; When the cogeneration unit needs to peak-shaving, the exhaust steam volume of the medium-pressure cylinder entering the heat network heater is increased according to the peak-shaving demand, and the output of circulating water at the outlet of the working fluid condenser is increased at the same time, so that the amount of circulating water entering the evaporator is reduced, so that the heat source for the heat network heater to heat the heat network return water mainly comes from the extraction steam of the medium-pressure cylinder, and the heat network return water heated by the condenser is supplied to the heat network through the heat network heater. After the hydrophobic waste heat of the heat network heater enters the waste heat evaporator, the turbine is driven to drive the first generator to generate electricity and the working fluid compressor to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged by the turbine enters the working fluid condenser to condense and release heat, and the condensed organic working fluid enters the working fluid compressor for compression and pressure increase, and enters the waste heat evaporator to achieve peak-shaving of the cogeneration unit.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a waste heat-driven flexible peak-shaving system for a cogeneration unit, which comprises at least a cooling tower, a heating network heater, a waste heat evaporator, a turbine, a first generator, a working fluid condenser, a working fluid compressor, an evaporator, a compressor and a condenser. The system efficiently couples a low-temperature waste heat power generation circulation unit composed of a waste heat evaporator, a turbine, a first generator, a working fluid condenser and a working fluid compressor, and a heat pump waste heat heating circulation unit composed of a condenser, a compressor and an evaporator with a conventional cogeneration steam-water circulation unit and a heating network heating unit, so as to realize cascade utilization of waste heat at various levels generated in the steam-water circulation process of the cogeneration unit, use the waste heat of water drainage from the heating network as a driving heat source, fully recover and utilize the waste heat of water drainage from the heating network, and use the waste heat source to simultaneously drive the working fluid compressor and the first generator, so as to avoid energy waste caused by secondary energy conversion of the electric compressor and improve energy utilization efficiency. The heat pump waste heat heating circulation unit recovers the cold end waste heat to improve the heating capacity of the cogeneration unit, realizes thermal-electric decoupling, and improves the operating flexibility of the cogeneration unit. When the unit needs peak load, increasing the amount of circulating water entering the heat pump's low-temperature heat source is equivalent to increasing the waste heat of the heat pump's low-temperature heat source, increasing the heating capacity of the heat pump's waste heat heating circulation unit, and reducing the amount of steam extracted from the cogeneration unit entering the heating network for heating, so that the cogeneration unit has more steam for power generation by the second generator; using the low-temperature waste heat power generation circulation unit to recover the waste heat of water drainage from the heating network to further increase the power generation of the cogeneration unit, and achieve response to the grid dispatching needs in the spot trading market to obtain spot electricity price benefits. When the unit needs to peak-shaving, the heat pump waste heat heating circulation unit is used to recover all the circulating water waste heat. At this time, the heat pump waste heat heating circulation unit, as a primary heat source, has heated the heat network return water to a certain temperature, which can reduce the heating steam extraction in the heat network heater and the main steam volume of the cogeneration unit. The amount of steam used for power generation in the cogeneration unit can be further reduced, thereby achieving peak-shaving and frequency regulation needs, reducing power generation losses when the on-grid electricity price of thermal power in the spot trading market is low, achieving efficient and flexible operation and adjustment methods, and improving the flexibility of the power system, enabling it to better cope with load fluctuations, realizing energy cascade utilization, optimizing the allocation of power resources, improving the thermal efficiency of the entire plant, reducing carbon emissions and other pollutant emissions, and achieving multiple optimizations of high efficiency, flexibility, energy saving and carbon reduction.

[0017] A circulating water pump is arranged on the busbar where the circulating water cooled by the evaporator and the circulating water cooled by the cooling tower are combined. The circulating water pump can smoothly pump the two cooled circulating water to the condenser and the working medium condenser, thereby ensuring the stability and continuity of the water circulation system, improving the cooling efficiency of the entire system, reducing the energy consumption of the system, and improving the flexibility of the system.

[0018] The outlet of the working medium condenser is provided with a first circulating water electric regulating valve. The electric regulating valve can accurately control the condensed water flow at the outlet of the condenser. By adjusting the opening degree of the valve, the condensed water flow can be finely adjusted, thereby controlling the distribution of circulating water entering the condenser and the working medium condenser. When the load of the cogeneration unit changes or the condensed water flow needs to be quickly adjusted, the electric regulating valve can respond quickly and make corresponding adjustments, thereby ensuring the stability and reliability of the entire system. This precise control helps to improve the flexibility of the entire system.

[0019] The heat network return water inlet of the condenser is provided with a heat network circulating water pump. The heat network circulating water pump can accelerate the flow rate of the heat network return water, thereby improving the efficiency of the entire heat network. By providing the heat network circulating water pump, it can be ensured that the heat network return water in the heat network is timely and effectively transported to the condenser for heat exchange, reducing the retention time of the heat network return water and improving the transfer efficiency of heat energy.

[0020] A second circulating water electric regulating valve is provided between the evaporator and the cooling tower. The second circulating water electric regulating valve can accurately control the water circulation flow between the evaporator and the cooling tower, thereby controlling the distribution of circulating water entering the evaporator and the cooling tower, which helps to improve the overall efficiency of the entire system and reduce energy waste.

[0021] An expansion valve is provided between the working medium inlet of the condenser and the working medium outlet of the evaporator. One of the main functions of the expansion valve is throttling and reducing pressure. After the high-temperature and high-pressure refrigerant in the condenser passes through the expansion valve, the pressure is significantly reduced and converted into a low-temperature and low-pressure vapor-liquid mixture. This transformation makes it easier for the working medium to evaporate in the evaporator, thereby absorbing more heat and improving the effect of heat exchange. In addition, the expansion valve can automatically adjust the flow rate of the working medium entering the evaporator according to the temperature signal obtained by the temperature sensing package or the gas box head. This automatic adjustment capability enables the heat pump waste heat heating circulation unit to adapt to the ever-changing refrigeration load requirements and ensure that it can maintain a stable operating state under different working conditions.

[0022] A steam electric regulating valve is arranged between the intermediate pressure cylinder and the heating network heater. The steam electric regulating valve can accurately control the steam flow entering the heating network heater. By adjusting the opening degree of the valve, the steam flow can be finely regulated, thereby realizing efficient coupling of the conventional cogeneration steam-water circulation unit with the heating network and low-temperature waste heat power generation circulation unit, and then flexibly regulating the peak of the cogeneration unit through the hierarchical utilization of multi-level energy.

[0023] The conventional cogeneration steam-water circulation unit includes a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a deaerator, a high-pressure heater group, a second generator, a condenser and a low-pressure heater group; in this cycle, the high-pressure feed water absorbs the heat of the flue gas in the boiler and evaporates into superheated steam, which enters the high-pressure cylinder to do work. The conventional cogeneration steam-water circulation unit passes through the high-pressure cylinder exhaust steam and is reheated, and then enters the medium-pressure cylinder to continue to do work. The medium-pressure cylinder exhaust steam is divided into two paths, one path enters the low-pressure cylinder to do work, and the other path enters the heat network heater to heat the heat network circulating water. This cascade utilization of thermal energy maximizes the utilization of the thermal energy of the fuel; after the low-pressure cylinder exhaust steam is condensed by the condenser, the cold end waste heat is absorbed by the circulating water. This part of the waste heat is effectively recovered and used to heat the heat network circulating water or the low-temperature waste heat power generation circulation unit to generate electricity, further improving the energy utilization efficiency.

[0024] A feed water pump is arranged between the deaerator and the high-pressure heater group; a condensate pump is arranged between the condenser and the low-pressure heater group, which is beneficial to improving the stability and flexibility of the conventional cogeneration steam-water circulation unit and improving the reliability of the cogeneration unit.

[0025] The present invention also provides a method for peak load regulation using the flexible peak load regulation system driven by the waste heat of the above-mentioned cogeneration unit. When the cogeneration unit needs a peak load, the method reduces the exhaust steam volume of the medium pressure cylinder entering the heating network heater, and at the same time reduces the water output of the circulating water at the outlet of the working medium condenser, so that the amount of circulating water entering the evaporator is increased, so that the working medium inside the evaporator absorbs more waste heat of the circulating water for evaporation, and the heat network return water is heated by the compressor and the condenser for the first stage, and the heated heat network return water is heated by the heat network heater for the second stage to become the heat network supply water; the heat network heater is degassing The waste heat of water enters the waste heat evaporator, driving the turbine to drive the first generator to generate electricity and the working fluid compressor to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged from the turbine enters the working fluid condenser to condense and release heat, and the condensed organic working fluid enters the working fluid compressor for compression and pressure increase, and enters the waste heat evaporator to realize the drain waste heat power generation cycle; through the drain waste heat power generation cycle, the drain waste heat power generation cycle is promoted to utilize the drain waste heat of the heat network heater, further improve the power generation of the cogeneration unit, and realize the response to the grid dispatching needs in the spot trading market to obtain spot electricity price benefits. When the cogeneration unit needs to shave its peak, according to the peak-shaving demand, the exhaust steam volume of the medium-pressure cylinder entering the heat network heater is increased, and the water output of the circulating water at the outlet of the working fluid condenser is increased, so that the amount of circulating water entering the evaporator is reduced, so that the heat source for the heat network heater to heat the heat network return water mainly comes from the extraction steam of the medium-pressure cylinder, and the heat network return water heated by the condenser is supplied to the heat network through the heat network heater, so that the hydrophobic waste heat of the heat network heater enters the waste heat evaporator, drives the turbine to drive the first generator to generate electricity and the working fluid compressor to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged by the turbine enters the working fluid condenser to condense and release heat, and the condensed organic working fluid enters the working fluid compressor for compression and pressure increase, and enters the waste heat evaporator, that is, by using the waste heat of the cogeneration unit during peak shaving for heating the heat network return water and generating electricity in the low-temperature waste heat power generation cycle unit, the peak-shaving and frequency-regulating needs are met, and the power generation loss is reduced when the on-grid electricity price of thermal power in the spot trading market is low, so as to achieve an efficient and flexible operation and regulation method. The method is simple and easy to operate, which has promoted the innovation and development of cogeneration technology and provided strong support for the sustainable development of the energy industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a flexible peak-shaving system driven by waste heat of a cogeneration unit of the present invention.

[0027] Figure 2 The present invention is a flow chart of a flexible peak-shaving method driven by waste heat of a cogeneration unit.

[0028] Among them, 1-boiler, 2-high-pressure cylinder, 3-medium-pressure cylinder, 4-low-pressure cylinder, 5-second generator, 6-condenser, 7-condensate pump, 8-low-pressure heater group, 9-deaerator, 10-feed water pump, 11-high-pressure heater group, 12-cooling tower, 13-circulating water pump, 14-steam electric regulating valve, 15-heating network heater, 16-waste heat evaporator, 17-turbine, 18-first generator, 19-working fluid condenser, 20-working fluid compressor, 21-first circulating water electric regulating valve, 22-evaporator, 23-compressor, 24-condenser, 25-expansion valve, 26-second circulating water electric regulating valve, 27-heating network circulating water pump. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0036] The present invention discloses a flexible peak-shaving system driven by waste heat of a cogeneration unit, referring to Figure 1 , including conventional cogeneration steam-water circulation unit, low-temperature waste heat power generation circulation unit, heat pump waste heat heating circulation unit and heat network heating unit; The conventional cogeneration steam-water circulation unit comprises a conventional boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a second generator 5, a condenser 6, a condensate pump 7, a low-pressure heater group 8, a deaerator 9, a feedwater pump 10 and a high-pressure heater group 11; The low-temperature waste heat power generation cycle unit includes a waste heat evaporator 16, a turbine 17, a first generator 18, a working fluid condenser 19, a working fluid compressor 20 and a first circulating water electric valve 21; The heat pump waste heat heating circulation unit includes a condenser 24, a compressor 23, an evaporator 22, an expansion valve 25 and a second circulating water electric regulating valve 26; The heating network heating unit includes a heating network circulating water pump 27 and a heating network heater 15; The high-pressure feed water in the conventional cogeneration steam-water circulation unit absorbs the heat of flue gas in the boiler 1 and evaporates into superheated steam to enter the high-pressure cylinder 2 to do work. The exhaust steam of the high-pressure cylinder 2 is reheated by the boiler 1 and enters the medium-pressure cylinder 3 to do work. The exhaust steam of the medium-pressure cylinder 3 is divided into two paths, one of which enters the low-pressure cylinder 4 to continue to do work, and the other enters the heat network heater 15 to heat the heat network circulating water. Preferably, a steam electric regulating valve 14 is arranged between the heat network heater 15 and the medium-pressure cylinder 3 to adjust the amount of steam extraction entering the heat network heater 15. The high-pressure cylinder 2, the medium-pressure cylinder 3 and the low-pressure cylinder 4 drive the second generator 5 to generate electricity through the shaft to realize external power supply. The exhaust steam of the low-pressure cylinder 4 releases heat and condenses through the condenser 6, and the waste heat at the cold end is absorbed by the circulating water. The condensate enters the low-pressure heater group 8 through the condensate pump 7 and is heated by the extraction steam. The heated condensate enters the deaerator 9 for deoxygenation, and is pumped to the high-pressure heater group 11 by the feed water pump 10 for heating and then sent back to the boiler 1 to complete the steam-water circulation. The return water from the heating network is pumped to the condenser 24 by the heating network circulating water pump 27 for heat exchange, and then enters the heating network heater 15 for heating to supply water to the heating network; After the hot network drain of the hot network heater 15 enters the waste heat evaporator 16, the turbine 17 is driven to drive the first generator 18 to generate electricity and the working fluid compressor 20 to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged by the turbine 17 enters the working fluid condenser 19 to condense and release heat, and the condensed organic working fluid enters the working fluid compressor 20 to be compressed and increased in pressure, and then enters the waste heat evaporator 16, completing the low-temperature waste heat power generation cycle; The circulating water at the outlet of the working medium condenser 19 is combined with the circulating water at the outlet of the condenser 6 through the first circulating water electric valve 21 and then divided into two paths, one of which enters the evaporator 22 to be cooled, and the other enters the cooling tower 12 for spraying and cooling; the circulating water cooled by the evaporator 22 is combined with the circulating water cooled by the cooling tower 12 through the circulating water electric regulating valve 26 and then passes through the circulating water pump 13 and is divided into two paths, one of which enters the condenser 6 and the other enters the working medium condenser 19; the working medium inside the condenser 24 enters the evaporator 22 through the expansion valve 25 to absorb the waste heat of the circulating water and evaporate, and then enters the condenser 24 again after being compressed by the compressor 23 to condense and release heat to heat the heat network return water, completing the heat pump waste heat heating cycle.

[0037] See also Figure 2 The present invention provides a method for peak load regulation using the above-mentioned flexible peak load regulation system driven by waste heat of the cogeneration unit, comprising: S1: When the combined heat and power unit needs a peak load, the exhaust volume of the medium pressure cylinder 3 entering the heat network heater 15 is reduced, and the water output of the circulating water at the outlet of the working medium condenser 19 is reduced, so that the amount of circulating water entering the evaporator 22 is increased, so that the working medium inside the evaporator 22 absorbs more waste heat of the circulating water to evaporate, and the heat network return water is heated by the condenser 24 for the first stage, and the heated heat network return water is heated by the heat network heater 15 for the second stage to become the heat network supply water; after the water discharge waste heat of the heat network heater 15 enters the waste heat evaporator 16, the turbine 17 is driven to drive the first generator 18 to generate electricity and the working medium compressor 20 to compress and increase the pressure of the working medium; the low-temperature and low-pressure organic working medium discharged by the turbine 17 enters the working medium condenser 19 to condense and release heat, and the condensed organic working medium enters the working medium compressor 20 for compression and pressure increase, and enters the waste heat evaporator 16 to realize the water discharge waste heat power generation cycle; S2: When the cogeneration unit needs to shave its peak, according to the peak shaving demand, the exhaust steam volume of the medium pressure cylinder 3 entering the heat network heater 15 is increased, and the water output of the circulating water at the outlet of the working fluid condenser 19 is increased, so that the amount of circulating water entering the evaporator 22 is reduced, so that the heat source for the heat network heater 15 to heat the heat network return water mainly comes from the extraction steam of the medium pressure cylinder 3, and the heat network return water heated by the condenser 24 is supplied to the heat network through the heat network heater 15, and the hydrophobic waste heat of the heat network heater 15 enters the waste heat evaporator 16, and then drives the turbine 17 to drive the first generator 18 to generate electricity and the working fluid compressor 20 to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged by the turbine 17 enters the working fluid condenser 19 to condense and release heat, and the condensed organic working fluid enters the working fluid compressor 20 to be compressed and increased in pressure, and enters the waste heat evaporator 16 to achieve peak shaving of the cogeneration unit.

[0038] In summary, the present invention provides a flexible peak-shaving system and method driven by waste heat of a cogeneration unit, by efficiently coupling a low-temperature waste heat power generation circulation unit consisting of a waste heat evaporator 16, a turbine 17, a first generator 18, a working fluid condenser 19 and a working fluid compressor 20, and a heat pump waste heat heating circulation unit consisting of a condenser 24, a compressor 23 and an evaporator 22 with a conventional cogeneration steam-water circulation unit and a heating network heating unit, so as to realize cascade utilization of waste heat at various levels generated in the steam-water circulation process of the cogeneration unit, use the waste heat of water discharge from the heating network as the driving heat source, fully recycle and utilize the waste heat of water discharge from the heating network, realize thermal and electric decoupling, meet the peak-shaving and frequency regulation needs of the cogeneration unit, reduce power generation losses when the on-grid electricity price of thermal power in the spot trading market is low, realize efficient and flexible operation and regulation methods, improve the flexibility of the power system, enable it to better cope with load fluctuations, realize cascade utilization of energy, and optimize the allocation of power resources.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A flexible peak-shaving system driven by waste heat from a cogeneration unit, characterized in that: The system comprises at least a cooling tower (12), a heating network heater (15), a waste heat evaporator (16), a turbine (17), a first generator (18), a working fluid condenser (19), a working fluid compressor (20), an evaporator (22), a compressor (23) and a condenser (24); The return water from the heating network enters the heating network heater (15) through the condenser (24) and is heated to supply water to the heating network; Part of the exhaust steam of the medium-pressure cylinder (3) in a conventional cogeneration steam-water circulation unit enters the low-pressure cylinder (4) to perform work, and the other part is passed through the heat network heater (15) to heat the heat network water supply; after the heat network water of the heat network heater (15) enters the waste heat evaporator (16), the turbine (17) is driven to drive the first generator (18) to generate electricity and the working fluid compressor (20) to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged from the turbine (17) enters the working fluid condenser (19) to condense and release heat, and the condensed organic working fluid enters the working fluid compressor (20) to be compressed and increased in pressure, and then enters the waste heat evaporator (16); After the circulating water at the outlet of the working medium condenser (19) is combined with the circulating water at the outlet of the condenser (6), it is divided into two paths, one of which enters the evaporator (22) to be cooled, and the other enters the cooling tower (12) for spraying and cooling; after the circulating water cooled by the evaporator (22) and the circulating water cooled by the cooling tower (12) are combined, it is divided into two paths, one of which enters the condenser (6) and the other enters the working medium condenser (19); after the working medium inside the condenser (24) absorbs the waste heat of the circulating water and evaporates in the evaporator (22), it is compressed by the compressor (23) and then enters the condenser (24) to condense and release heat to heat the return water of the heat network.

2. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 1, characterized in that: A circulating water pump (13) is provided on the busbar where the circulating water cooled by the evaporator (22) and the circulating water cooled by the cooling tower (12) are combined.

3. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 1, characterized in that: The outlet of the working medium condenser (19) is provided with a first circulating water electric regulating valve (21).

4. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 1, characterized in that: The heat network return water inlet of the condenser (24) is provided with a heat network circulating water pump (27).

5. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 1, characterized in that: A second circulating water electric regulating valve (26) is provided between the evaporator (22) and the cooling tower (12).

6. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 1, characterized in that: An expansion valve (25) is provided between the working medium inlet of the condenser (24) and the working medium outlet of the evaporator (22).

7. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 1, characterized in that: A steam electric regulating valve (14) is provided between the medium-pressure cylinder (3) and the heating network heater (15).

8. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 1, characterized in that: The conventional cogeneration steam-water circulation unit comprises a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), a deaerator (9), a high-pressure heater group (11), a second generator (5), a condenser (6) and a low-pressure heater group (8); The high-pressure feed water absorbs the heat of flue gas in the boiler (1) and evaporates into superheated steam, which enters the high-pressure cylinder (2) to perform work. The exhaust steam of the high-pressure cylinder (2) is reheated by the boiler (1) and enters the medium-pressure cylinder (3) to perform work. The exhaust steam of the medium-pressure cylinder (3) is divided into two paths, one of which enters the low-pressure cylinder (4) to continue to perform work, and the other enters the heating network heater (15) to heat the heating network circulating water. The high-pressure cylinder (2), the medium-pressure cylinder (3) and the low-pressure cylinder (4) drive the second generator (5) to generate electricity through the shaft to realize external power supply. The exhaust steam of the low-pressure cylinder (4) releases heat and condenses through the condenser (6), and the residual heat at the cold end is absorbed by the circulating water. The condensate enters the low-pressure heater group (8) to be heated by extraction steam. The heated condensate enters the deaerator (9) to be deoxygenated, and is then heated by the high-pressure heater group (11) and sent back to the boiler (1), completing the steam-water cycle.

9. The flexible peak-shaving system driven by waste heat from a combined heat and power unit according to claim 8, characterized in that: A feed water pump (10) is provided between the deaerator (9) and the high-pressure heater group (11); and a condensate pump (7) is provided between the condenser (6) and the low-pressure heater group (8).

10. A method for peak load regulation using a flexible peak load regulation system driven by waste heat from a combined heat and power unit according to any one of claims 1 to 9, characterized in that: include: When the combined heat and power unit needs a peak load, the exhaust volume of the medium pressure cylinder (3) entering the heat network heater (15) is reduced, and the water output of the circulating water at the outlet of the working medium condenser (19) is reduced, so that the amount of circulating water entering the evaporator (22) is increased, so that the working medium inside the evaporator (22) absorbs more waste heat of the circulating water to evaporate, and the heat network return water is first heated by the condenser (24), and the heated heat network return water is then secondarily heated by the heat network heater (15) to become the heat network supply water; the waste heat of the water discharge from the heat network heater (15) enters the waste heat evaporator (16), drives the turbine (17) to drive the first generator (18) to generate electricity and the working medium compressor (20) to compress and increase the pressure of the working medium; the low-temperature and low-pressure organic working medium discharged from the turbine (17) enters the working medium condenser (19) to condense and release heat, and the condensed organic working medium enters the working medium compressor (20) to be compressed and increased in pressure, and enters the waste heat evaporator (16), so as to realize the waste heat power generation cycle; When the combined heat and power generation unit needs to adjust the peak, the exhaust steam volume of the medium pressure cylinder (3) entering the heating network heater (15) is increased according to the peak adjustment demand, and the water output of the circulating water at the outlet of the working medium condenser (19) is increased, so that the amount of circulating water entering the evaporator (22) is reduced, so that the heat source for the heating network heater (15) to heat the heating network return water mainly comes from the extraction steam of the medium pressure cylinder (3), and the heating network return water heated by the condenser (24) is supplied to the heating network through the heating network heater (15). , after the waste heat of the water discharge from the heat network heater (15) enters the waste heat evaporator (16), the turbine (17) is driven to drive the first generator (18) to generate electricity and the working fluid compressor (20) to compress and increase the pressure of the working fluid; the low-temperature and low-pressure organic working fluid discharged from the turbine (17) enters the working fluid condenser (19) to condense and release heat, and the condensed organic working fluid enters the working fluid compressor (20) to be compressed and increased in pressure, and then enters the waste heat evaporator (16), thereby realizing the peak load regulation of the cogeneration unit.

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