Abstract:
The invention relates to an electric peaking combined heat and power (CHP) waste heat recovery device and an operating method thereof. The device comprises an inner power plant portion and a heat exchange station portion, wherein the inner power plant portion comprises a heat exchanger, a waste heat recovery electric heat pump, an energy-storing electric heat pump, high/low temperature water storing tanks, a heating network heater, a valve and a circulating water pump; the heat exchange station portion mainly comprises high/low temperature water storing tanks, an electric heat pump, a heat exchanger, a valve and a circulating water pump; as for the operating method of the device, the device can operate in periods of an electrical load trough, an electrical load flat and an electrical load peak respectively through combination of different valve switches, the high temperature water storing tank is used for balancing the difference between system heat supply amount and heating load, the low temperature water storing tank is used for stabilizing steam exhaust waste heat recovery amount, thereby, the problem that the electricity generation peaking capacity is limited due to mutual coupling of electricity generation and heat supply in traditional operating modes of ‘heat determines electricity’ is solved, a CHP unit can participate in power grid load regulation, the power grid regulating capacity can be improved so as to deal with the condition of constantly increasing of electrical load trough-to-peak difference, and the absorptive capacity of a power grid for wind power generation can be improved so as to reduce phenomena of ‘fan suspending’.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a heat exchanging device and operating method thereof, and in particularly, to an electric peaking combined heat and power (CHP) waste heat recovery device and an operating method thereof by using heat storing technology in combination with combined heat and power (CHP) and waste heat recovery. The present invention belongs to the technical field of energy and power. 
       BACKGROUND 
       [0002]    Northern China belongs to areas that rich in wind energy, and the wind power generation is growing rapidly in these regions; in addition, the installed capacity of wind energy is increasing year by year, and the proportion of the installed capacity of wind energy in the total installed capacity is also increasing year by year. However, the wind power has an anti-load characteristic, i.e., during the electrical load trough in the power grid at night, the wind power output is large, and during the electrical load peak in the power grid at daytime, the wind power output is small. Meanwhile, the difference between electrical load peak and electrical load trough is also expanding year by year, leading the electric peaking to encounter difficulty. 
         [0003]    Currently, the cities and towns in Northern China are still dependent on coal-fired boiler, causing the fact of supplying the heat with high energy consumption and high pollution. Combined heat and power (CHP) is an efficient heating supply mode. However, the heat power plants in China operate in the way of ‘heat determines electricity’. In order to ensure heat supply, regulation ranges of the power output for many heat power plants are greatly limited, and the energy production cannot get lower during the electrical load trough, thereby racing to control the space of wind on-grid energy and making the wind power station have to limit its power output, which lead to phenomena of “fan suspending” in the areas that are rich in wind energy in Northern China. 
         [0004]    Applying heat pump technology to recover exhaust waste heat of the combined heat and power (CHP) unit may further improve the heat supply efficiency of the combined heat and power (CHP), but it still cannot change the operating mode of ‘heat determines electricity’. The combined heat and power (CHP) may operate in the mode of ‘electricity determines heat’ by combining heat storage and the combined heat and power (CHP) unit through the heat storage stabilizing fluctuation of heat output, however, when in combination with the exhaust waste heat recovery technology in power plants, it still cannot ensure the stable recovery for the exhaust waste heat of power plant. 
       SUMMARY 
       [0005]    To solve the above problems, an object of the invention is to provide an electric peaking combined heat and power (CHP) waste heat recovery device and an operating method thereof by using heat storing technology in combination with combined heat and power (CHP) and waste heat recovery, so as to realize electric peaking combined heat and power (CHP) unit on the basis of realization of waste heat recovery. 
         [0006]    In order to realize the above object, the invention adopts the following technical solution: an electric peaking combined heat and power (CHP) waste heat recovery device, characterized in that, the device comprises an inner power plant portion and a heat exchange station portion, 
         [0000]    wherein the inner power plant portion mainly comprises a heat exchanger ( 1 ), a waste heat recovery electric heat pump ( 2 ), an energy-storing electric heat pump ( 3 ), a high temperature water storing tank ( 4 ), a low temperature water storing tank ( 5 ), a heating network heater ( 6 ), valves ( 11 - 19 ) and circulating water pumps ( 20 - 23 ); wherein an inlet of the heat exchanger ( 1 ) is connected to a primary network backwater pipe ( 1 - 1 ), and an outlet of the heat exchanger ( 1 ) is connected to inlets of the valve ( 11 ), the valve ( 12 ) and the circulating water pump ( 20 ) in parallel, respectively; an inlet of the waste heat recovery electric heat pump ( 2 ) is connected to an outlet of the valve ( 12 ), and an outlet of the waste heat recovery electric heat pump ( 2 ) is connected to an inlet of the heating network heater ( 6 ); a top inlet/outlet of the high temperature water storing tank ( 4 ) is connected to an outlet of the valve ( 13 ) and an inlet of the valve ( 14 ) in parallel, respectively, an inlet of the valve ( 13 ) is connected to an outlet of a condenser of the energy-storing electric heat pump ( 3 ) and an outlet of the valve ( 14 ) is connected to the inlet of the heating network heater ( 6 ); a bottom inlet/outlet of the high temperature water storing tank is connected to an outlet of the valve ( 15 ) and an inlet of the circulating water pump ( 21 ) in parallel, respectively, an inlet of the valve ( 15 ) is connected to an outlet of the circulating water pump ( 20 ), and an outlet of the circulating water pump ( 21 ) is connected to an inlet of the condenser of the energy-storing electric heat pump ( 3 ) via the valve ( 16 ); a top inlet/outlet of the low temperature water storing tank ( 5 ) is connected to an outlet of the valve ( 11 ) and an inlet of the valve ( 17 ) in parallel, respectively, and an outlet of the valve ( 17 ) is connected to an inlet of an evaporator of the energy-storing electric heat pump ( 3 ); a bottom inlet/outlet of the low temperature water storing tank ( 5 ) is connected to an outlet of the valve ( 18 ) and an inlet of the circulating water pump ( 22 ) in parallel, respectively, an inlet of the valve ( 18 ) is connected to an outlet of the evaporator of the energy-storing electric heat pump ( 3 ) via the circulating water pump ( 23 ), and an outlet of the circulating water pump ( 22 ) is connected to the inlet of the heat exchanger ( 1 ) in parallel via the valve ( 19 );
 
wherein the heat exchange station portion mainly comprises a high temperature water storing tank ( 7 ), a low temperature water storing tank ( 8 ), an electric heat pump ( 9 ), a heat exchanger ( 10 ), valves ( 24 - 35 ) and a circulating water pump ( 36 - 37 ); wherein a top inlet/outlet of the high temperature water storing tank ( 7 ) is connected to an outlet of a valve ( 24 ) and an inlet of the circulating water pump ( 36 ) in parallel, respectively, an inlet of the valve ( 24 ) is connected to an outlet of the heating network heater ( 6 ) via a primary network water supply pipe ( 1 - 2 ), an outlet of the circulating water pump ( 36 ) connected to the primary network water supply pipe ( 1 - 2 ) in parallel via the valve ( 25 ) is connected to an inlet of the valve ( 26 ), and an outlet of the valve ( 26 ) is connected to an inlet of a primary network of the heat exchanger ( 10 ); a bottom inlet/outlet of the high temperature water storing tank ( 7 ) is connected to an outlet of the valve ( 27 ) and an inlet of the valve ( 28 ) in parallel, respectively, an inlet of the valve ( 27 ) is connected to an outlet of the primary network of the heat exchanger ( 10 ), and an outlet of the valve ( 28 ) is connected to an inlet of an evaporator of the electric heat pump ( 9 ); a top inlet/outlet of the low temperature water storing tank ( 8 ) is also connected to the outlet of the valve ( 27 ) and the inlet of the valve ( 28 ) in parallel, respectively, a bottom inlet/outlet of the low temperature water storing tank ( 8 ) is connected to an outlet of the valve ( 29 ) and an inlet of the valve ( 30 ) in parallel, respectively, and an outlet of the valve ( 30 ) is connected to the primary network backwater pipe ( 1 - 1 ); an outlet of the evaporator of the electric heat pump ( 9 ) is connected to an inlet of the circulating water pump ( 37 ) and the primary network backwater pipe ( 1 - 1 ) in parallel via the valve ( 31 ), respectively, and an outlet of the circulating water pump ( 37 ) is connected to an inlet of the valve ( 29 ); a secondary network backwater pipe ( 1 - 3 ) is connected to inlets of the valve ( 32 ) and the valve ( 33 ) in parallel, respectively, an outlet of the valve ( 32 ) is connected to an inlet of the secondary network of the heat exchanger ( 10 ), both outlets of the valve ( 33 ) and the secondary network of the heat exchanger ( 10 ) are connected to inlets of the valve ( 34 ) and the valve ( 35 ) in parallel, respectively, an outlet of the valve ( 35 ) is connected to a secondary network water supply pipe ( 1 - 4 ), an outlet of the valve ( 34 ) is connected to an inlet of a condenser of the electric heat pump ( 9 ), and an outlet of the condenser of the electric heat pump ( 9 ) is connected to the secondary network water supply pipe ( 1 - 4 ).
 
         [0007]    In a preferred embodiment, the heat exchanger ( 1 ) adopts a condenser or a water-water heat exchanger. 
         [0008]    In a preferred embodiment, the heat exchanger ( 10 ) adopts a plate-type heat exchanger or an absorption-type heat exchanger unit. 
         [0009]    An operating method for the electric peaking combined heat and power (CHP) waste heat recovery device described above, characterized in that, the operating method adjusts operating modes of the device through combination of different valve switches such that the device can operate in periods of an electrical load trough, an electrical load flat and an electrical load peak respectively: 
         [0000]    1) during electrical load trough period: in the inner power plant portion, the valve ( 11 ), the valve ( 14 ), the valve ( 15 ), the valve ( 19 ), the circulating water pump ( 20 ) and the circulating water pump ( 22 ) are closed; the valve ( 12 ), the valve ( 13 ), the valve ( 16 ), the valve ( 17 ), the valve ( 18 ), the circulating water pump ( 21 ) and the circulating water pump ( 23 ) are open; primary network low temperature backwater provided by the primary network backwater pipe ( 1 - 1 ) flows into the heat exchanger ( 1 ) and the waste heat recovery electric heat pump ( 2 ) successively; the heat exchanger ( 1 ) and the waste heat recovery electric heat pump ( 2 ) recover exhaust waste heat of the combined heat and power (CHP) unit to heat the primary network low temperature backwater; the heated heating network water from the waste heat recovery electric heat pump ( 4 ) flows into the heating network heater ( 6 ), wherein the heated heating network water is steam extracted and heated by the combined heat and power (CHP) unit to a heating network design temperature to obtain primary network high temperature supply water flowing into the primary network water supply pipe ( 1 - 2 ) which supplies the primary network high temperature supply water; meanwhile, water stored in the high temperature water storing tank ( 4 ) is drawn from the bottom outlet via the circulating water pump ( 21 ) and flows into the condenser of the energy-storing electric heat pump ( 3 ); and after heat exchanged and heated, the water flows back into the high temperature water storing tank ( 4 ) from the top inlet; water stored in the low temperature water storing tank ( 5 ) is pressed from the top outlet and flows into the evaporator of the energy-storing electric heat pump ( 3 ), and after heat exchanged and cooled, the water is directed into the low temperature water storing tank ( 5 ) from the bottom inlet via the circulating water pump ( 23 ); 
         [0010]    In the heat exchange station portion, the valve ( 25 ), the valve ( 26 ), the valve ( 27 ), the valve ( 30 ), the valve ( 32 ), the valve ( 35 ) and the circulating water pump ( 36 ) are closed; the other valves and the circulating water pump ( 37 ) are open; primary network high temperature supply water provided by the primary network water supply pipe ( 1 - 2 ) flows into the high temperature water storing tank ( 7 ) from the top inlet; the high temperature supply water is stored in the high temperature water storing tank ( 7 ), thus pressing middle temperature water stored in the high temperature water storing tank ( 7 ) from the bottom outlet and is mixed with middle temperature stored water pressed from the top outlet of the low temperature water storing tank ( 8 ); then the mixed water flows into the evaporator of the electric heat pump ( 9 ); after heat exchanged and cooled, the mixed water is divided into two branches, one of which is directed into the low temperature water storing tank ( 8 ) from the bottom inlet via the circulating water pump ( 37 ), and the other of which flows into the primary network backwater pipe ( 1 - 1 ); meanwhile, secondary network low temperature backwater provided by the secondary network water supply pipe ( 1 - 3 ) flows through the condenser of the electric heat pump ( 9 ); and after heat exchanging and heating the secondary network low temperature backwater, secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe ( 1 - 4 ) for supplying to heat users; 
         [0000]    2) during electrical load flat period: in the inner power plant portion, the valve ( 16 ), the valve ( 18 ), the circulating water pump ( 21 ) and the circulating water pump ( 23 ) are closed; the energy-storing electric heat pump ( 3 ) is shut down; and the other parts operates in the same way as that during the electrical load trough period; 
         [0011]    In the heat exchange station portion, the valve ( 24 ), the valve ( 25 ), the valve ( 29 ), the valve ( 30 ), the valve ( 33 ), the valve ( 35 ) and the circulating water pump ( 37 ) are closed; the other valves and the circulating water pump ( 36 ) are open; primary network high temperature supply water provided by the primary network water supply pipe ( 1 - 2 ) flows through a primary network side of the heat exchanger ( 10 ) and the evaporator of the electric heat pump ( 9 ) successively; after heat exchanging and cooling the primary network high temperature supply water, primary network low temperature backwater is obtained, which flows into the primary network backwater pipe ( 1 - 1 ); meanwhile, secondary network low temperature backwater provided by the secondary network backwater pipe ( 1 - 3 ) flows through a secondary network side of the heat exchanger ( 10 ) and the condenser of the electric heat pump ( 9 ) successively; and after heat exchanging and heating the secondary network low temperature backwater, secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe ( 1 - 4 ) for supplying to the heat users; 
         [0000]    3) during electrical load peak period: in the inner power plant portion, the valve ( 12 ), the valve ( 13 ), the valve ( 16 ), the valve ( 17 ), the valve ( 18 ), the circulating water pump ( 21 ) and the circulating water pump ( 23 ) are closed; the valve ( 11 ), the valve ( 14 ), the valve ( 15 ), the valve ( 19 ), the circulating water pump ( 20 ) and the circulating water pump ( 22 ) are open; low temperature water stored in the low temperature water storing tank ( 5 ) is drawn from the bottom outlet and is mixed with the primary network low temperature backwater, and then the low temperature mixed water is sent to heat exchanger ( 1 ); the heat exchanger ( 1 ) recovers the exhaust waste heat of the combined heat and power (CHP) unit to heat the low temperature mixed water; the heated heating network water by the heat exchanger ( 1 ) is divided into two branches, one of which returns back into the low temperature water storing tank ( 5 ) from the top inlet, the other of which is directed into the high temperature water storing tank ( 4 ) from the bottom inlet via the circulating water pump ( 20 ); and high temperature water stored in the high temperature water storing tank ( 4 ) is pressed from the top outlet and then is sent to the heating network heater ( 6 ); wherein the high temperature water is steam extracted and heated by the combined heat and power (CHP) unit to a heating network design temperature to obtain the primary network high temperature supply water flowing into the primary network water supply pipe ( 1 - 2 ) which supplies the primary network high temperature supply water; 
         [0012]    In the heat exchange station portion, the valve ( 24 ), the valve ( 28 ), the valve ( 29 ), the valve ( 31 ), the valve ( 33 ), the valve ( 34 ) and the circulating water pump ( 37 ) are closed; the electric heat pump ( 9 ) is shut down; the other valves and the circulating water pump ( 36 ) are open; high temperature water stored in the high temperature water storing tank ( 7 ) is drawn from the top outlet by the circulating water pump ( 36 ) and is mixed with the primary network high temperature supply water provided by the primary network water supply pipe ( 1 - 2 ); and then the mixed water flows through the primary network side of the heat exchanger ( 10 ); after heat exchanging and cooling the mixed water, middle temperature water is obtained and divided into two branches, one of which flows into the high temperature water storing tank ( 7 ) from the bottom inlet, the other of which flows into the low temperature water storing tank ( 8 ) from the top inlet, thus pressing low temperature water stored in the low temperature water storing tank ( 8 ) from the bottom outlet; the pressed low temperature water flows into the primary network backwater pipe ( 1 - 1 ); meanwhile, the secondary low temperature backwater provided by the secondary network backwater pipe ( 1 - 3 ) flows through the secondary network side of the heat exchanger ( 10 ); and after heat exchanging and heating the secondary low temperature backwater, secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe ( 1 - 4 ) for supplying to the heat users. 
         [0013]    An electric peaking combined heat and power (CHP) waste heat recovery device, characterized in that, the device comprises an inner power plant portion and a heat exchange station portion, 
         [0000]    wherein the inner power plant portion mainly comprises a heat exchanger ( 1 ), a waste heat recovery electric heat pump ( 2 ), an energy-storing electric heat pump ( 3 ), a high temperature water storing tank ( 4 ), a low temperature water storing tank ( 5 ), a heating network heater ( 6 ), valves ( 11 - 19 ) and circulating water pumps ( 20 - 23 ); wherein an inlet of the heat exchanger ( 1 ) is connected to a primary network backwater pipe ( 1 - 1 ), and an outlet of the heat exchanger ( 1 ) is connected to inlets of the valve ( 11 ), the valve ( 12 ) and the circulating water pump ( 20 ) in parallel, respectively; an inlet of the waste heat recovery electric heat pump ( 2 ) is connected to an outlet of the valve ( 12 ), and an outlet of the waste heat recovery electric heat pump ( 2 ) is connected to an inlet of the heating network heater ( 6 ); a top inlet/outlet of the high temperature water storing tank ( 4 ) is connected to an outlet of the valve ( 13 ) and an inlet of the valve ( 14 ) in parallel, respectively, an inlet of the valve ( 13 ) is connected to an outlet of a condenser of the energy-storing electric heat pump ( 3 ) and an outlet of the valve ( 14 ) is connected to the inlet of the heating network heater ( 6 ); a bottom inlet/outlet of the high temperature water storing tank is connected to an outlet of the valve ( 15 ) and an inlet of the circulating water pump ( 21 ) in parallel, respectively, an inlet of the valve ( 15 ) is connected to an outlet of the circulating water pump ( 20 ), and an outlet of the circulating water pump ( 21 ) is connected to an inlet of the condenser of the energy-storing electric heat pump ( 3 ) via the valve ( 16 ); a top inlet/outlet of the low temperature water storing tank ( 5 ) is connected to an outlet of the valve ( 11 ) and an inlet of the valve ( 17 ) in parallel, respectively, and an outlet of the valve ( 17 ) is connected to an inlet of an evaporator of the energy-storing electric heat pump ( 3 ); a bottom inlet/outlet of the low temperature water storing tank ( 5 ) is connected to an outlet of the valve ( 18 ) and an inlet of the circulating water pump ( 22 ) in parallel, respectively, an inlet of the valve ( 18 ) is connected to an outlet of the evaporator of the energy-storing electric heat pump ( 3 ) via the circulating water pump ( 23 ), and an outlet of the circulating water pump ( 22 ) is connected to the inlet of the heat exchanger ( 1 ) in parallel via the valve ( 19 );
 
wherein the heat exchange station portion mainly comprises a low temperature water storing tank ( 8 ), an electric heat pump ( 9 ), a heat exchanger ( 10 ), valves ( 26 - 35 ) and a circulating water pump ( 37 ); wherein an inlet of the valve ( 26 ) is connected to an outlet of the heating network heater ( 6 ) via a primary network water supply pipe ( 1 - 2 ); an outlet of the valve ( 26 ) is connected to an inlet of a primary network of the heat exchanger ( 10 ); a top inlet/outlet of the low temperature water storing tank ( 8 ) is connected to an outlet of the valve ( 27 ) and an inlet of the valve ( 28 ) in parallel, respectively; an inlet of the valve ( 27 ) is connected to an outlet of the primary network of the heat exchanger ( 10 ), and an outlet of the valve ( 28 ) is connected to an inlet of an evaporator of the electric heat pump ( 9 ); a bottom inlet/outlet of the low temperature water storing tank ( 8 ) is connected to an outlet of the valve ( 29 ) and an inlet of the valve ( 30 ) in parallel, respectively, and an outlet of the valve ( 30 ) is connected to the primary network backwater pipe ( 1 - 1 ); an outlet of the evaporator of the electric heat pump ( 9 ) is connected to an inlet of the circulating water pump ( 37 ) and the primary network backwater pipe ( 1 - 1 ) in parallel via the valve ( 31 ), respectively, and an outlet of the circulating water pump ( 37 ) is connected to an inlet of the valve ( 29 ); a secondary network backwater pipe ( 1 - 3 ) is connected to inlets of the valve ( 32 ) and the valve ( 33 ) in parallel, respectively, an outlet of the valve ( 32 ) is connected to an inlet of a secondary network of the heat exchanger ( 10 ), both outlets of the valve ( 33 ) and the secondary network of the heat exchanger ( 10 ) are connected to inlets of the valve ( 34 ) and the valve ( 35 ) in parallel, respectively, an outlet of the valve ( 35 ) is connected to a secondary network water supply pipe ( 1 - 4 ), an outlet of the valve ( 34 ) is connected to an inlet of a condenser of the electric heat pump ( 9 ), and an outlet of the condenser of the electric heat pump ( 9 ) is connected to the secondary network water supply pipe ( 1 - 4 ).
 
         [0014]    In a preferred embodiment, the heat exchanger ( 1 ) adopts a condenser or a water-water heat exchanger. 
         [0015]    In a preferred embodiment, the heat exchanger ( 10 ) adopts a plate-type heat exchanger or an absorption-type heat exchanger unit. 
         [0016]    An operating method for the electric peaking combined heat and power (CHP) waste heat recovery device described above, characterized in that, the operating method adjusts operating modes of the device through combination of different valve switches such that the device can operate in periods of an electrical load trough, an electrical load flat and an electrical load peak respectively: 
         [0000]    1) during electrical load trough period: in the inner power plant portion, the valve ( 11 ), the valve ( 14 ), the valve ( 15 ), the valve ( 19 ), the circulating water pump ( 20 ) and the circulating water pump ( 22 ) are closed; the valve ( 12 ), the valve ( 13 ), the valve ( 16 ), the valve ( 17 ), the valve ( 18 ), the circulating water pump ( 21 ) and the circulating water pump ( 23 ) are open; primary network low temperature backwater provided by the primary network backwater pipe ( 1 - 1 ) flows into the heat exchanger ( 1 ) and the waste heat recovery electric heat pump ( 2 ) successively; the heat exchanger ( 1 ) and the waste heat recovery electric heat pump ( 2 ) recover exhaust waste heat of the combined heat and power (CHP) unit to heat the primary network low temperature backwater; the heated heating network water from the waste heat recovery electric heat pump ( 4 ) flows into the heating network heater ( 6 ), wherein the heated heating network water is steam extracted and heated by the combined heat and power (CHP) unit to a heating network design temperature to obtain primary network high temperature supply water flowing into the primary network water supply pipe ( 1 - 2 ) which supplies the primary network high temperature supply water; meanwhile, water stored in the high temperature water storing tank ( 4 ) is drawn from the bottom outlet via the circulating water pump ( 21 ) and flows into the condenser of the energy-storing electric heat pump ( 3 ); and after heat exchanged and heated, the water flows back into the high temperature water storing tank ( 4 ) from the top inlet; water stored in the low temperature water storing tank ( 5 ) is pressed from the top outlet and flows into the evaporator of the energy-storing electric heat pump ( 3 ), and after heat exchanged and cooled, the water is directed into the low temperature water storing tank ( 5 ) from the bottom inlet via the circulating water pump ( 23 ); 
         [0017]    In the heat exchange station portion, the valve ( 30 ), the valve ( 33 ), the valve ( 35 ) are closed; the other valves and the circulating water pump ( 37 ) are open; primary network high temperature supply water provided by the primary network water supply pipe ( 1 - 2 ) first flows through a primary network side of the heat exchanger ( 10 ); and after heat exchanged and cooled, the primary network high temperature supply water is mixed with middle temperature stored water pressed from the top outlet of the low temperature water storing tank ( 8 ), then the mixed water flows through the evaporator of the electric heat pump ( 9 ); after further heat exchanged and cooled, the mixed water is divided into two branches, one of which is directed into the low temperature water storing tank ( 8 ) from the bottom inlet by the circulating water pump ( 37 ), the other of which flows into the primary network backwater pipe ( 1 - 1 ); meanwhile, secondary network low temperature backwater provided by the secondary network water supply pipe ( 1 - 3 ) first flows through a secondary network side of the heat exchanger ( 10 ); after heat exchanged and heated, the secondary network low temperature backwater flows into the condenser of the electric heat pump ( 9 ); after further heat exchanging and heating the secondary network low temperature backwater, secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe ( 1 - 4 ) for supplying to heat users; 
         [0000]    2) during electrical load flat period: in the inner power plant portion, the valve ( 16 ), the valve ( 18 ), the circulating water pump ( 21 ) and the circulating water pump ( 23 ) are closed; the energy-storing electric heat pump ( 3 ) is shut down, and the other parts operate in the same way as that during the electrical load trough period; 
         [0018]    In the heat exchange station portion, the valve ( 29 ), the valve ( 30 ), the valve ( 33 ), the valve ( 35 ) and the circulating water pump ( 37 ) are closed; the other valves are open; primary network high temperature supply water provided by the primary network water supply pipe ( 1 - 2 ) flows through the primary network side of the heat exchanger ( 10 ) and the evaporator of the electric heat pump ( 9 ) successively, after heat exchanging and cooling the primary network high temperature supply water, the primary network low temperature backwater is obtained, which flows into the primary network backwater pipe ( 1 - 1 ); meanwhile, secondary network low temperature backwater provided by the secondary network backwater pipe ( 1 - 3 ) flows through a secondary network side of the heat exchanger ( 10 ) and the condenser of the electric heat pump ( 9 ) successively; and after heat exchanging and heating the secondary network low temperature backwater, secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe ( 1 - 4 ) for supplying to the heat users; 
         [0000]    3) during electrical load peak period: in the inner power plant portion, the valve ( 12 ), the valve ( 13 ), the valve ( 16 ), the valve ( 17 ), the valve ( 18 ), the circulating water pump ( 21 ) and the circulating water pump ( 23 ) are closed; the valve ( 11 ), the valve ( 14 ), the valve ( 15 ), the valve ( 19 ), the circulating water pump ( 20 ) and the circulating water pump ( 22 ) are open; low temperature water stored in the low temperature water storing tank ( 5 ) is drawn from the bottom outlet and is mixed with the primary network low temperature backwater, and then the low temperature mixed water is sent to heat exchanger ( 1 ); the heat exchanger ( 1 ) recovers the exhaust waste heat of the combined heat and power (CHP) unit to heat the low temperature mixed water; the heated heating network water by the heat exchanger ( 1 ) is divided into two branches, one of which returns back into the low temperature water storing tank ( 5 ) from the top inlet, the other of which is directed into the high temperature water storing tank ( 4 ) from the bottom inlet via the circulating water pump ( 20 ); and high temperature water stored in the high temperature water storing tank ( 4 ) is pressed from the top outlet and then is sent to the heating network heater ( 6 ); wherein the high temperature water is steam extracted and heated by the combined heat and power (CHP) unit to a heating network design temperature to obtain the primary network high temperature supply water flowing into the primary network water supply pipe ( 1 - 2 ) which supplies the primary network high temperature supply water; 
         [0019]    In the heat exchange station portion, the valve ( 28 ), the valve ( 29 ), the valve ( 31 ), the valve ( 33 ), the valve ( 34 ) and the circulating water pump ( 37 ) are closed; the electric heat pump ( 9 ) is shut down; the other valves are open; the primary network high temperature supply water provided by the primary network water supply pipe ( 1 - 2 ) flows through the primary network side of the heat exchanger ( 10 ), and flows into the low temperature water storing tank ( 8 ) after heat exchanged and cooled; the low temperature water stored in the low temperature water storing tank ( 8 ) is pressed from the bottom outlet and is sent to the primary network backwater pipe ( 1 - 1 ); meanwhile, the secondary network low temperature backwater provided by the secondary network backwater pipe ( 1 - 3 ) flows through the secondary network side of the heat exchanger ( 10 ), and after heat exchanging and heating the secondary network low temperature backwater, the secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe ( 1 - 4 ) for supplying to the heat users. 
         [0020]    By applying the above technical solutions, the invention has the following advantages: 1. the waste heat recovery device of the invention comprises an inner power plant portion and a heat exchange station portion, wherein the inner power plant portion comprises a energy-storing and releasing system including an energy-storing electric heat pump, a high temperature water storing tank, a low temperature water storing tank, valves and circulating water pumps. During periods of the electrical load trough, the electrical load flat and the electrical load peak, the device adjusts the power output of the inner power plant portion and the electrical load of the heat exchanger station portion by intermittently operating the electric heat pumps in the inner power plant portion and the heat exchange station portion. The high temperature water storing tank is used for balancing the difference between system heat supply amount and heating load, the low temperature water storing tank is used for stabilizing steam exhaust waste heat recovery amount, thereby, thereby significantly improving the electric peaking capacity, and the problem that the electricity generation peaking capacity is limited due to mutual coupling of electricity generation and heat supply in traditional operating modes of ‘heat determines electricity’ in the CHP is solved, a CHP unit can adjust the grid power generation thereof and participate in power grid load regulation, the power grid regulating capacity can be improved so as to deal with the condition of constantly increasing of electrical load trough-to-peak difference, and the absorptive capacity of a power grid for wind power generation can be improved so as to reduce phenomena of ‘fan suspending’. 2. The waste heat recovering device of the invention may partially or fully recover the exhaust waste heat of the combined heat and power (CHP) unit, significantly improving the heat supply capacity of heat and power plant and the energy utilization efficiency of the system. 3. The invention also realizes “large temperature difference” heat supply of a primary network, which significantly expands the temperature differences between the supply water and backwater, improves the heat supply capacity of the existing pipe network by 50% without changing the primary network traffic; meanwhile, the present invention also realizes long-distance transportation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The invention will be described in details in the following with reference to drawings. However, it should be appreciated that the drawings are provided only for better understanding the invention, not to be interpreted to limit the invention. 
           [0022]      FIG. 1  is an overall structural schematic of a waste recovering device of the invention; 
           [0023]      FIG. 2  is a structural schematic of another heat exchanger of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The invention will be described in the following in details with reference to drawings and embodiments. 
         [0025]    As shown in  FIG. 1 , the device of the invention comprises an inner power plant portion and a heat exchange station portion. 
         [0026]    The inner power plant portion mainly comprises a condenser/water-water heat exchanger  1 , a waste heat recovery electric heat pump  2 , an energy-storing electric heat pump  3 , a high temperature water storing tank  4 , a low temperature water storing tank  5 , a heating network heater  6 , valves  11 - 19  and circulating water pumps  20 - 23 ; wherein the inlet of the condenser/water-water heat exchanger  1  is connected to the primary network backwater pipe  1 - 1 , and the outlet of the condenser/water-water heat exchanger  1  is connected to the inlets of the valve  11 , the valve  12  and the circulating water pump  20  in parallel, respectively. The inlet of the waste heat recovery electric heat pump  2  is connected to the outlet of the valve  12 , and the outlet of the waste heat recovery electric heat pump  2  is connected to the inlet of the heating network heater  6 . The top inlet/outlet of the high temperature water storing tank  4  is connected to the outlet of the valve  13  and the inlet of the valve  14  in parallel, respectively, the inlet of the valve  13  is connected to the outlet of a condenser of the energy-storing electric heat pump  3  and the outlet of the valve  14  is connected to the inlet of the heating network heater  6 . The bottom inlet/outlet of the high temperature water storing tank  4  is connected to the outlet of the valve  15  and the inlet of the circulating water pump  21  in parallel, respectively, the inlet of the valve  15  is connected to the outlet of the circulating water pump  20 , and the outlet of the circulating water pump  21  is connected to inlet of a condenser of the energy-storing electric heat pump  3  via the valve  16 . The top inlet/outlet of the low temperature water storing tank  5  is connected to the outlet of the valve  11  and the inlet of the valve  17  in parallel, respectively, and the outlet of the valve  17  is connected to the inlet of an evaporator of the energy-storing electric heat pump  3 . The bottom inlet/outlet of the low temperature water storing tank  5  is connected to the outlet of the valve  18  and the inlet of the circulating water pump  22  in parallel, respectively, the inlet of the valve  18  is connected to the outlet of the evaporator of the energy-storing electric heat pump  3  via the circulating water pump  23 , and the outlet of the circulating water pump  22  is connected to the inlet of the condenser/water-water heat exchanger  1  in parallel via the valve  19 . 
         [0027]    The heat exchange station portion mainly comprises a high temperature water storing tank  7 , a low temperature water storing tank  8 , an electric heat pump  9 , a plate-type heat exchanger  10 , valves  24 - 35  and circulating water pumps  36 - 37 ; wherein the top inlet/outlet of the high temperature water storing tank  7  is connected to the outlet of the valve  24  and the inlet of the circulating water pump  36  in parallel, respectively, the inlet of the valve  24  is connected to the outlet of the heating network heater  6  via a primary network water supply pipe  1 - 2 , the outlet of the circulating water pump  36  connected to the primary network water supply pipe  1 - 2  in parallel via the valve  25  is connected to the inlet of the valve  26 , the outlet of the valve  26  is connected to the inlet of a primary network of the plate-type heat exchanger  10 . The bottom inlet/outlet of the high temperature water storing tank  7  is connected to the outlet of the valve  27  and the inlet of the valve  28  in parallel, respectively, the inlet of the valve  27  is connected to the outlet of a primary network of the plate-type heat exchanger  10 , and the outlet of the valve  28  is connected to the inlet of the evaporator of the electric heat pump  9 . The top inlet/outlet of the low temperature water storing tank  8  is also connected to the outlet of the valve  27  and the inlet of the valve  28  in parallel, respectively, the bottom inlet/outlet of the low temperature water storing tank  8  is connected to the outlet of the valve  29  and the inlet of the valve  30  in parallel, respectively, the outlet of the valve  30  is connected to the primary network backwater pipe  1 - 1 . The outlet of the evaporator of the electric heat pump  9  is connected to the inlet of the circulating water pump  37  and the primary network backwater pipe  1 - 1  in parallel via the valve  31 , respectively, and the outlet of the circulating water pump  37  is connected to inlet of the valve  29 . The secondary network backwater pipe  1 - 3  is connected to the inlets of the valve  32  and the valve  33 , respectively, the outlet of the valve  32  is connected to the inlet of the secondary network of the plate-type heat exchanger  10 , both the outlet of the valve  33  and the outlet of the secondary network of the plate-type heat exchanger  10  are connected to the inlets of the valve  34  and the valve  35  in parallel, respectively, the outlet of the valve  35  is connected to the secondary network water supply pipe  1 - 4 , the outlet of the valve  34  is connected to the inlet of the condenser of the electric heat pump  9 , and the outlet of the condenser of the electric heat pump  9  is connected to the secondary network water supply pipe  1 - 4 . 
         [0028]    In a preferred embodiment, in the heat exchange station portion, the plate-type heat exchanger  10  may be replaced by absorption-type heat exchanger unit to reduce the water inlet temperature for the evaporator of the electric heat pump  9  such that the power consumption of the electric heat pump  9  is reduced. 
         [0029]    Based on the electric peaking combined heat and power (CHP) waste heat recovery device provided in the above embodiment, the invention also provides a method for electric peaking combined heat and power (CHP) waste heat recovery, the method adjusts operating modes of the device through combination of different valve switches such that the device can operate in periods of an electrical load trough, an electrical load flat and an electrical load peak respectively: 
         [0000]    1. during electrical load trough period: in the inner power plant portion, the valve  11 , the valve  14 , the valve  15 , the valve  19 , the circulating water pump  20  and the circulating water pump  22  are closed; the valve  12 , the valve  13 , the valve  16 , the valve  17 , the valve  18 , the circulating water pump  21  and the circulating water pump  23  are open; primary network low temperature backwater provided by the primary network backwater pipe  1 - 1  flows into the condenser/water-water heat exchanger  1  and the waste heat recovery electric heat pump  2  successively; the condenser/water-water heat exchanger  1  and the waste heat recovery electric heat pump  2  recover exhaust waste heat of the combined heat and power unit to heat the primary network low temperature backwater; the heated heating network water from the waste heat recovery electric heat pump  4  flows into the heating network heater  6 , wherein the heated heating network water is steam extracted and heated by the combined heat and power unit to a heating network design temperature to obtain primary network high temperature supply water flowing into the primary network water supply pipe  1 - 2  which supplies the primary network high temperature supply water; meanwhile, water stored in the high temperature water storing tank  4  is drawn from the bottom outlet via the circulating water pump  21  and flows into the condenser of the energy-storing electric heat pump  3 ; and after heat exchanged and heated, the water flows back into the high temperature water storing tank  4  from the top inlet; water stored in the low temperature water storing tank  5  is pressed from the top outlet and flows into the evaporator of the energy-storing electric heat pump  3 , and after heat exchanged and cooled, the water is directed into the low temperature water storing tank  5  from the bottom inlet via the circulating water pump  23 . 
         [0030]    In the heat exchange station portion, the valve  25 , the valve  26 , the valve  27 , the valve  30 , the valve  32 , the valve  35  and the circulating water pump  36  are closed; the other valves and the circulating water pump  37  are open; primary network high temperature supply water provided by the primary network water supply pipe  1 - 2  flows into the high temperature water storing tank  7  from the top inlet; the high temperature supply water is stored in the high temperature water storing tank  7 , thus pressing middle temperature water stored in the high temperature water storing tank  7  from the bottom outlet and is mixed with middle temperature stored water pressed from the top outlet of the low temperature water storing tank  8 ; then the mixed water flows into the evaporator of the electric heat pump  9 ; after heat exchanged and cooled, the mixed water is divided into two branches, one of which is directed into the low temperature water storing tank  8  from the bottom inlet via the circulating water pump  37 , and the other of which flows into the primary network backwater pipe  1 - 1 ; meanwhile, secondary network low temperature backwater provided by the secondary network water supply pipe  1 - 3  flows through the condenser of the electric heat pump  9 ; and after heat exchanging and heating the secondary network low temperature backwater with middle temperature water stored from the high temperature water storing tank  7  and the low temperature water storing tank  8 , secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe  1 - 4  for supplying to heat users. 
         [0000]    2 during electrical load flat period: in the inner power plant portion, the valve  16 , the valve  18 , the circulating water pump  21  and the circulating water pump  23  are closed; the energy-storing electric heat pump  3  is shut down; and the other parts operates in the same way as that during the electrical load trough period; 
         [0031]    In the heat exchange station portion, the valve  24 , the valve  25 , the valve  29 , the valve  30 , the valve  33 , the valve  35  and the circulating water pump  37  are closed; the other valves and the circulating water pump  36  are open; primary network high temperature supply water provided by the primary network water supply pipe  1 - 2  flows through a primary network side of the heat exchanger  10  and the evaporator of the electric heat pump  9  successively; after heat exchanging and cooling the primary network high temperature supply water, primary network low temperature backwater is obtained, which flows into the primary network backwater pipe  1 - 1 ; secondary network low temperature backwater provided by the secondary network backwater pipe  1 - 3  flows through a secondary network side of the heat exchanger  10  and the condenser of the electric heat pump  9  successively; and after heat exchanging and heating the secondary network low temperature backwater with the primary network high temperature supply water, secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe  1 - 4  for supplying to the heat users, wherein the boot capacity of the electric heat pump  9  is less than that of the electric heat pump  9  during the electrical load trough period. 
         [0000]    3 during electrical load peak period: in the inner power plant portion, the valve  12 , the valve  13 , the valve  16 , the valve  17 , the valve  18 , the circulating water pump  21  and the circulating water pump  23  are closed; the valve  11 , the valve  14 , the valve  15 , the valve  19 , the circulating water pump  20  and the circulating water pump  22  are open; low temperature water stored in the low temperature water storing tank  5  is drawn from the bottom outlet and is mixed with the primary network low temperature backwater, and then the low temperature mixed water is sent to the condenser/water-water heat exchanger  1 ; the condenser/water-water heat exchanger  1  recovers the exhaust waste heat of the combined heat and power unit to heat the low temperature mixed water, wherein the amount of exhaust waste heat recovered by the condenser/water-water heat exchanger  1  is larger than that of the exhaust waste heat recovered by the condenser/water-water heat exchanger  1  during the electrical load trough period; the heated heating network water by the condenser/water-water heat exchanger  1  is divided into two branches, one of which returns back into the low temperature water storing tank  5  from the top inlet, the other of which is directed into the high temperature water storing tank  4  from the bottom inlet via the circulating water pump  20 ; and high temperature water stored in the high temperature water storing tank  4  is pressed from the top outlet and then is sent to the heating network heater  6 ; wherein the high temperature water is steam extracted and heated by the combined heat and power unit to a heating network design temperature to obtain the primary network high temperature supply water flowing into the primary network water supply pipe  1 - 2  which supplies the primary network high temperature supply water; 
         [0032]    In the heat exchange station portion, the valve  24 , the valve  28 , the valve  29 , the valve  31 , the valve  33 , the valve  34  and the circulating water pump  37  are closed; the electric heat pump  9  is shut down; the other valves and the circulating water pump  36  are open; high temperature water stored in the high temperature water storing tank  7  is drawn from the top outlet by the circulating water pump  36  and is mixed with the primary network high temperature supply water provided by the primary network water supply pipe  1 - 2 ; and then the mixed water flows through the primary network side of the heat exchanger  10 ; after heat exchanging and cooling the mixed water, middle temperature water is obtained and divided into two branches, one of which flows into the high temperature water storing tank  7  from the bottom inlet, the other of which flows into the low temperature water storing tank  8  from the top inlet, thus pressing low temperature water stored in the low temperature water storing tank  8  from the bottom outlet; the pressed low temperature water flows into the primary network backwater pipe  1 - 1 ; the secondary low temperature backwater provided by the secondary network backwater pipe  1 - 3  flows through the secondary network side of the heat exchanger  10 ; and after heat exchanging and heating the secondary low temperature backwater, secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe  1 - 4  for supplying to the heat users. 
         [0033]    In a preferred embodiment, as shown in  FIG. 2 , the heat exchange station portion may not contain the high temperature water storing tank  7 , at this operating mode, although during the periods of the electrical load trough, electrical load peak and electrical load peak, the heat exchange station portion provides different amount of heat supply, the thermal inertia of buildings may be used to maintain indoor temperature for human body comfort: 
         [0034]    During the electrical load trough period: in the heat exchange station portion, the valve  30 , the valve  33 , the valve  35  are closed; the other valves and the circulating water pump  37  are open; the heat exchange station portion no longer stores the primary network high temperature supply water; the primary network high temperature supply water directly flows through the plat-type heat exchanger  10  and is mixed with the middle temperature water stored in the low temperature water storing tank  8  that is pressed from the top outlet, and then the mixed water flows into the evaporator of the electric heat pump  9 ; after heat exchanged and cooled, the mixed water is divided into two branches, one of which is directed into the low temperature water storing tank  8  from the bottom inlet by the circulating water pump  37 , the other of which flows into the primary network backwater pipe  1 - 1 . Meanwhile, the secondary network low temperature backwater provided by the secondary network water supply pipe  1 - 3  firstly flows through the secondary network side of the plat-type heat exchanger  10 ; after heat exchanged and heated, the secondary network low temperature backwater flows into the condenser of the electric heat pump  9 ; after further heat exchanging and heating the secondary network low temperature backwater, the secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe  1 - 4  for supplying to the heat users, wherein the electric heat pump  9  operates at full capacity. 
         [0035]    During the electrical load flat period, in the heat exchange station portion, the valve  29 , the valve  30 , the valve  33 , the valve  35  and the circulating water pump  37  are closed and the other valves are open; the low temperature water storing tank  8  no longer participate in heat storing or exothermic process; the primary network high temperature supply water provided by the primary network water supply pipe  1 - 2  flows through the primary network side of the plate-type heat exchanger  10  and the evaporator of the electric heat pump  9  successively; after heat exchanging and cooling the primary network high temperature supply water, the primary network low temperature backwater is obtained, which flows into the primary network backwater pipe  1 - 1 . Meanwhile, the secondary network low temperature backwater provided by the secondary network backwater pipe  1 - 3  flows through the secondary network side of the plate-type heat exchanger  10  and the condenser of the electric heat pump  9  successively; after heat exchanging and heating the primary network high temperature supply water, the secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe  1 - 4  for supplying to the heat users, now the electric heat pump  9  operates at part of capacity. 
         [0036]    During electrical load peak period, in the heat exchange station portion, the valve  28 , the valve  29 , the valve  31 , the valve  33 , the valve  34  and the circulating water pump  37  are closed; the electric heat pump  9  is shut down; and the other valves are open; the primary network high temperature supply water provided by the primary network water supply pipe  1 - 2  flows through the primary network side of the plate-type heat exchanger  10 , and after heat exchanged and cooled, all of which flows into the low temperature water storing tank  8 ; in turn the low temperature water stored in the low temperature water storing tank  8  is pressed from the bottom outlet and is sent to the primary network backwater pipe  1 - 1 . Meanwhile, the secondary network low temperature backwater provided by the secondary network backwater pipe  1 - 3  flows through the secondary network side of the plate-type heat exchanger  10 ; and after heat exchanging and heating the secondary network low temperature backwater, the secondary network high temperature supply water is obtained, which flows into the secondary network water supply pipe  1 - 4  for supplying to the heat users. 
         [0037]    The embodiments described above are only intended to further illustrate the object, technical solution and benefits of the invention in details, not for limiting the invention. Any modification, equivalent replacement and improvement that are made within the spirit and principle of the invention should be included within the scope of the invention.