WO1999013276A1

WO1999013276A1 - Coupled power-heat device for supplying energy

Info

Publication number: WO1999013276A1
Application number: PCT/DE1998/002756
Authority: WO
Inventors: Jörg HARTAN; Ingo Gatzke; Ralph Bahke
Original assignee: Vng - Verbundnetz Gas Aktiengesellschaft
Priority date: 1997-09-09
Filing date: 1998-09-09
Publication date: 1999-03-18
Also published as: AU1022299A; EP1012513A1; DE19740398A1; DE19740398C2

Abstract

The invention relates to a coupled power-heat device for heating, cooling and supplying buildings and installations with electric energy comprising an internal combustion engine (1), a generator (2) and a heat accumulator (4) to which a cooling accumulator (6) is assigned. Both accumulators (4, 6) are connected to one another via a heat pump (3), whereby the cooling accumulator (6) serves as a heat source for said heat pump (3). System modules which generate the heat energy having a relatively high thermal level are attached to the heat accumulator (4) and the modules which deliver the heat energy having a relatively low thermal level to the cooling accumulator (6).

Description

Combined heat and power facility for energy supply

The invention relates to a combined heat and power facility of small to medium power for the energy supply of private and / or public buildings and facilities using primary energy from liquid or gaseous fuels, preferably natural gas.

Numerous plants and facilities for supplying energy to buildings with thermal and electrical energy and for treating hot domestic water are already known from the prior art. The systems provided for heating, including hot water preparation, air conditioning and power generation in buildings are mostly installed and operated separately from one another. This inevitably means that both the investment and the operating costs, especially for the primary energies to be used, are high. From DE 42 03 491 AI an electronically controlled energy supply unit is known, which is used to generate heat and electrical energy. The energy supply unit comprises a generator for generating electricity, which is driven by an internal combustion engine. The thermal energy is obtained from the exhaust gases of the engine and from the cooling water of the internal combustion engine by means of a heat exchanger and made available in a boiler. With the help of a heat pump, which is driven by the internal combustion engine, residual heat is recovered from the engine exhaust gases and used to heat the boiler. If necessary, the boiler can also be heated by the electrical energy generated. The energy supply unit according to DE 42 03 491 AI has no equipment for air conditioning the building and for the recovery of heat from the exhaust air. Renewable energies are not used.

A similar heating and power generation system for converting primary energy and ambient heat into electrical energy and useful heat is proposed by DE-OS 40 06 742 AI. The centerpiece of the system is a boiler operated with a burner and a Stirling engine which can be heated with the same burner and which drives a generator and a heat pump. The generator is preferably a linear generator which can be electrically connected to the drive motor of a heat pump, to the public power grid or to other consumers via a corresponding control. With the help of the heat pump, thermal energy is also recovered from the ambient heat and made available for heating purposes. This solution does not provide for a subsystem for the air conditioning of buildings and facilities and for the recovery of thermal energy from the air conditioning systems. A combined system for the generation of electrical energy using the waste heat from the domestic power generation for a room heating is known from DE 44 34 831 AI. The electrical energy is generated with a gas engine generator arrangement, a heat exchanger operating as a heat source being connected to the gas engine generator arrangement via a waste heat recovery pipeline. A heat transfer medium is heated in the source-side heat exchanger and the steam thus formed is fed to the heat exchangers for space heating. The liquefied steam then flows back into the source-side heat exchanger of the gas engine-generator arrangement after its heat energy has been released. According to a preferred embodiment of this system, an absorption cooling device is also provided, which is integrated in a circulating pipeline. The circulating pipeline is filled with a heating medium subjected to gas-liquid phase changes. Heat exchangers, which are used to cool building floors, are connected to this circulation pipe. The disadvantage of this device is that the system does not provide any means of using renewable energies.

From DE 41 02 636 AI it is also known to buffer the electrical energy generated in a combined heat and power system using a generator in a battery. In addition to greater independence from public energy supply networks, this measure is intended to reduce the operating times of the system and to better adapt the internal supply of electrical energy to the respective requirements. The proposed system, which is used to supply hot domestic water and heating energy at the same time, works exclusively with electrical energy as the primary energy input and has no further equipment for the use of renewable energy. gien and for heat storage. It is particularly disadvantageous that larger amounts of heat, which occur during peak load periods, must not be used and released to protect the system.

A proposal for integrating solar collectors into a heating system that is operated with fossil primary energies is known from DE 26 91 774. The proposed heating system is also equipped with a liquid heat storage and with heat pumps in order to achieve the highest possible efficient use of the heat generated by solar and primary energy. The thermal energy generated by the solar collectors is used in this system as far as possible only for heating purposes. This system does not provide for further use of solar energy, for example in seasons when the sun is not so strong, and the use of further renewable energies.

The invention has for its object to develop an electronically controllable device of the type mentioned for heating, cooling and energy supply of buildings and facilities with the inclusion of renewable energies, which can be realized with relatively low cost and investment and the necessary primary energy share for the heat - and energy supply further reduced.

According to the invention the object is achieved by the features specified in claim 1. Advantageous developments of the invention result from claims 2 to 10. With the coupling of known basic modules according to the invention and their specially coordinated interaction, a completely new quality in the utilization of the primary energy used is achieved, the system according to the invention being able to be used simultaneously for heating, for producing hot process water and for air conditioning (cooling) of buildings. The invention is therefore not an addition or extension to known combined heat and power systems, but rather a new, completely independent and environmentally friendly solution that is extremely economical. In its entirety, it combines the complex functionalities of heating, power generation, hot water generation and cooling with efficient use of regenerative environmental energy.

The system according to the invention, which is used in winter operation to generate heat and electrical energy from fossil fuels, such as gas or oil, is used in summer operation to air-condition buildings and facilities and to prepare hot domestic water with simultaneous electricity generation. There are therefore no additional costs for the air conditioning in summer operation, whereby only corresponding dimensions of the heating surfaces that serve as cooling surfaces during summer operation need to be taken into account.

The system according to the invention can be used efficiently anywhere and thus the primary energy consumption can be reduced where conventional gas, oil or solid fuel heating systems are currently still installed. The centerpiece of the combined heat and power device according to the invention is a hot storage tank in conjunction with an additional cold storage device, which according to the invention has an internal combustion engine which drives a power generator, and a heat pump, which is optionally designed as a compression or absorption heat pump, and solar devices for Utilization of regenerative energies and the waste heat generated when primary energy is used.

By using the two storage units, the number of operating hours of the internal combustion engine can be designed with appropriate dimensioning of the overall system in such a way that, with proper maintenance, the longest possible service life is easily achieved with standard machines. The use of special and therefore expensive internal combustion engines, which must be designed for continuous operation, is therefore not necessary. The integration of the heat pump system even makes it possible to use an inexpensive air-cooled fuel machine for this application, since the cylinder and housing waste heat can be usefully coupled into the storage system. The system according to the invention, which is equipped with a temperature and dew point-based control, ensures the highest possible utilization of regenerative energies through the use of an efficient, electronic control. The runtime of the combined heat and power facilities and the consumption of primary energy can be reduced to a minimum as a result of energy storage. The heat generated in the internal combustion engine, which is used in conjunction with a generator to generate electrical energy and is used to drive the heat pump, is fed to the hot or cold storage at a different thermal level via the cooling system of the internal combustion engine. With the help of heat exchangers, part of the residual heat is extracted from the exhaust gases, the cooling water and the engine oil of the internal combustion engine at a relatively high thermal level and coupled in for further charging of the heat accumulator.

With the help of a condensing condenser, further residual heat, including the heat of condensation, is extracted from the already cooled exhaust gases due to the condensing effect and fed to the cold store at a relatively low thermal level.

According to an essential feature of the invention, the internal combustion engine-generator unit is thermally encapsulated in a soundproof and heat-insulated housing. The waste heat generated in the housing is injected into the cold store by an air-water heat exchanger at a thermally low level and can therefore also be used. These energies serve as a source for the heat pump.

The invention thus ensures almost complete use of the waste heat from the system, which corresponds to the combined heat and power (CHP) principle, including the use of the condensing effect.

Via the cold storage, to which a recooler for heat recovery from the ventilation system of a building, a heat exchanger for the utilization of the waste water heat and during the winter operation also the solar collectors are connected on the primary side are used with the heat pump, which connects the hot storage tank with the cold storage tank, thermal energy from the environment, which has a relatively low level, and with a higher thermal level in the hot storage tank for the preparation of hot water for heating and for hot domestic water fed. Depending on the system, the use of the heat pump increases the effectiveness of the combined heat and power device according to the invention to the extent that more usable heat and electrical energy is provided than the primary energy used.

This effect results from the coupling of the environmental energy from the solar system in cooperation with the heat pump.

The invention will be explained in more detail below using an exemplary embodiment. The accompanying drawing shows a schematic representation of the combined heat and power heating, cooling and energy supply device.

As can be seen from the drawing, the primary energy used for heating, air conditioning (cooling), for generating electrical energy and for hot domestic water, in the present exemplary embodiment preferably natural gas, is supplied in a manner known per se to an internal combustion engine 1, for example a gas engine or a turbine that drives a generator 2 for generating electrical energy. Internal combustion engine 1 and generator 2 are housed in a sound and heat insulated housing 36, which with a supply for supply and exhaust air 37; 38 is equipped for cooling purposes. To the generator 2, which drives the heat pump 3, the house network 34 for the electrical power supply and the public e-network are connected via the e-network connection 32. The connection to the public E-network is made with the interposition of meter units 15 for the supply and for the recovery / supply of electrical energy.

The generator 2 is preferably designed as an asynchronous machine which is rigidly connected to the internal combustion engine 1. This variant offers the advantage that the generator is used as a drive to start the internal combustion engine 1 and, at the same time, complex network synchronizations can be dispensed with. A so-called soft start circuit may be necessary for generators with high output. The use of synchronous or direct current generators is of course possible and, among other things. then makes sense if an island operating mode of the electrical energy supply system is desired.

After the starting process, the internal combustion engine 1 runs up at the nominal speed of the motor in accordance with the mains frequency present. When the internal combustion engine is loaded by increasing the primary energy supply, the generator 2 is over-synchronized and current is fed into the connected network. The load on the internal combustion engine can be regulated by measuring the power in such a way that the generator works with its specified nominal power. This condition forms the nominal operating point for the generation of electrical energy and waste heat.

If 34 electrical energy is consumed during the generator operation in the house network connected in parallel, the energy is supplied directly by the generator 2 and does not have to be charged from the public e-network. By using the hot storage 4, the running time of the device for generating electrical energy can be controlled so that it always works when the electrical energy consumption in the building or in the public network is given.

In principle, it is also possible to use a fuel cell instead of the internal combustion engine generator unit, without the downstream system parts and operating principles thereby changing significantly.

Because of the intermittent mode of operation of the system according to the invention, it makes sense and is economical to temporarily store the generated electrical energy. According to the present exemplary embodiment, the alternating current generated by the generator 2 is rectified in a photovoltaic system 16 and delivered to a battery system integrated in the system 16, in which the electrical energy is stored. The electrical energy stored in this way for self-consumption is fed into the house network 34 by the inverter as AC voltage via the E-grid connection 33 and the switching device 40. In addition, the photovoltaic system 16 is connected to the public electric network.

The solar panels included in the photovoltaic system 16 supplement the use with regenerative energy in a known manner.

In addition to the use of a hot storage device 4 known per se, an additional cold storage device 6 is part of the combined heat and power device according to the invention. This cold storage 6 serves on the one hand as a heat supplier for the evaporator of the heat pump 3 in the heating mode during winter operation and as a cooling supplier in the cooling mode when air conditioning the buildings in summer mode.

During winter operation, the solar collectors 13, the condensing condenser 42 and the cooling system 10 of the internal combustion engine 1 and generator 2 are connected to the cold store 6, which is connected to the hot store 4 via the heat pump 3, on the primary side by means of the lines 5.

A heat exchanger for utilizing the waste heat from the exhaust air recooling 27 of the building is also connected to the cold store 6. All of the aforementioned modules deliver heat energy with a relatively lower thermal level to the cold store 6, which forms the heat energy source for the heat pump 3.

In addition, there is a heat exchanger in the cold store 6 with a waste water waste heat recovery 20, which naturally has a waste water connection 19 and an overflow 31 for the sewer system, and via the valve 11 for the selectable changeover to summer and winter operation with the underfloor heating 28 and the heating / Heatsinks 29 connected to the building. The cold store 6 is also advantageously equipped with a connection 7 for an additional cooling circuit.

To the hot storage 4, which is preferably designed as a stratified storage, the exhaust system of the internal combustion engine 1 and the solar collectors 13 are connected on the primary side for charging it with thermal energy through the connecting lines 8. Through the connecting lines 45, the oil cooler of the internal combustion engine 1 with connecting lines gen 8 connected and thus directly coupled to the hot storage 4. The condenser of the heat pump 3 serves as a further heat source for the hot store 4. An alternative heat generation device in the form of a conventional gas burner 39 (redundancy) supplements the system according to the invention.

On the secondary side, the flow 21 of the heating installations, which at the same time for cooling or. Serve air conditioning, and the lines for the hot water connection 25 connected.

The flow 21 of the heating installations is connected on the secondary side to the cold storage 6 for the air conditioning of the rooms, to which the recooling 27 for heat recovery from the exhaust air of the building is connected in winter operation. The changeover to summer and winter operation is carried out with the help of the changeover valves 11; 12 and the valves 41, 42 and 43 are realized, all of which are controlled with the aid of the electronic control unit 9.

For the event of a malfunction on the internal combustion engine 1, a gas burner 39 is provided as an alternative heat generating device in the exhaust line of the internal combustion engine 1, which has an exhaust gas flow switch 35 for summer and winter operation, which in connection with exhaust gas heat exchanger 24 for charging the hot storage tank 4 directly via the connecting lines 8 is connected to this.

The outside temperature-controlled regulation of the heating flow 21 takes place in a special way via the mixer 18 connected to the hot storage 4 on the secondary side operated with several connection points. These are the hot water connection on the input side from the upper area of the hot storage 4, the hot water connection from the central area of the hot storage 4 and the return 14 of the heating system and on the output side the flow 21 of the heating system. The electronic control unit 9 is used to automatically switch between the input lines for regulating the flow temperature. Thus, at flow temperatures up to the average temperature of the hot storage 4, the heating / cooling flow 21 is operated in the middle storage area in connection with the cooler return 14. If the setpoint of the outside temperature-controlled control is above the temperature in the storage medium area, the admixture from the return 14 is interrupted. The admixture then takes place from the upper area of the hot storage 4 with hot water. This special arrangement of the input streams for the mixer 18 minimizes the consumption of hot water and thus greatly reduces the system start-ups for recharging the hot storage tank 4. This effect directly benefits the life of the internal combustion engine 1.

The return 14 of the heating installation is fed to the hot storage 4 at the lowest point and in this way supports the thermal stratification in the storage 4 a preheater 26 is arranged for heating the incoming fresh air of the ventilation system. Heat exchangers are provided within the hot storage tank 4, by means of which the hot service water in the lower part of the hot storage tank 4, which, as described above, is preferably designed as a stratified storage tank, is preheated. This on the one hand supports the desired cooling of the hot storage 4 in this storage area and at the same time minimizes the heat removal in the upper, hot storage area. A downstream simple thermal mixer 30 is used to set the desired end temperature of the treated hot water.

A major advantage of the combined heat and power device according to the invention is that the proposed system can be used effectively for heating purposes and for air conditioning / cooling of the buildings and facilities in the cold seasons without additional equipment or changes in the system. In summer operation, the medium (water) located in the cold store 6 is cooled down to approximately 0 ° C. using the heat pump 3. This cold water is via switch valves 11; 12 for the cooling operation in summer and for heating operation in winter, fed to the mixer 18 and mixed to a temperature just above the dew point of the air in the rooms to be cooled and via the cooling / heating surfaces 29 and, if appropriate, the underfloor heating systems 28 to the corresponding rooms Cooling supplied. The existing heating system thus cools the rooms without requiring additional system-related expenses. Existing ventilation and air conditioning systems are integrated into this cycle accordingly. Another advantage is that when an absorption machine is used as the heat pump 3, the heat energy transported in the summer by the solar collectors 13 into the hot store 4 can be used for cooling. The energy source of the absorption refrigerator is then the charged hot storage device 4.

The solar collectors 13 integrated in the device according to the invention fulfill two tasks. Due to the direct connection of the solar collectors 13 to the hot storage tank 4, the solar energy in summer operation is used directly for the treatment of hot service water and, if necessary, for the treatment of warm water for heating purposes. This arrangement corresponds to the well-known classic application of solar systems in a temperature range above 50 ° C.

Especially in the colder season, however, the solar energy is generally no longer sufficient to heat the heat transfer medium of the solar collectors 13 to the desired temperature level of over 50 ° C. In conventional systems, the collectors are therefore only used to a limited extent in the winter period.

In the device according to the invention, with the help of the heat pump 3 in conjunction with the cold store 6, collector flow temperatures of the solar collectors 13 of substantially less than 50 ° C. can be used efficiently all year round by the relatively low temperature level of the solar collectors 13 during the colder season and the even colder heat transfer medium in the cold store 6 is supplied via a heat exchanger. As a result, heat is transported from the environment into the cold store 6 at a relatively low temperature level. The heat pump 3 uses this heat energy raised to a usable thermal level of about 50 ° C and fed to the hot storage 4, as already described. As a result, it is largely possible to dispense with other environmental heat suppliers for the operation of the heat pump 3, as is the case, for example, with conventional heat pump systems for utilizing thermal energy from geothermal, water or air heat with a correspondingly high level of equipment and thus financial outlay. The device according to the invention differs fundamentally from known plants and systems and at the same time minimizes the plant-side effort by consistently using the solar collectors 13 in both summer and winter. The changeover to summer and winter operation is in turn carried out with the aid of the changeover valves 22; 23 made.

REFERENCE NUMBERS

1 internal combustion engine

2 generator

3 heat pumps

4 hot water tanks

5 line

6 cold stores

7 Connection for additional cooling circuit

8 connecting cable

9 electronic control unit

10 coolers

11 changeover valve

12 changeover valve

13 solar collector

14 return

15 counter unit

16 photovoltaic system

17 -

18 mixers

19 sewage pipe

20 wastewater intermediate storage

21 Heating / cooling flow

22 changeover valve 23 changeover valve

24 exhaust gas heat exchanger

25 Process water connection

26 Supply air preheating

27 Exhaust air recooling

28 underfloor heating

29 heating / cooling surfaces

30 Domestic hot water thermostat

31 waste water overflow

32 E mains connection E-mains connection house connection flue gas flow switchover housing supply air exhaust air gas burner switchover valve condensing condenser valve valve connecting cable

Claims

claims

Combined heat and power facility for heating, cooling and supplying energy to buildings and facilities using fossil primary energy and using solar energy consisting of an internal combustion engine and a generator driven by it, which is used to operate a heat pump and with the house network of the building and is connected to the public supply network for feeding in electrical energy and a heat exchanger arranged in the exhaust gas duct of the internal combustion engine, which is connected on the primary side to a heat accumulator together with a solar collector, to which the building equipment to be supplied with thermal energy and hot water is connected on the secondary side, characterized in that that the hot store (4) is assigned a cold store (6) and both stores (4; 6) are thermally coupled to one another via a heat pump (3), system modules which generate thermal energy at a relatively high thermal level, to the hot storage tank (4) and system modules that supply thermal energy with a lower thermal level, to the cold storage tank (6), which serves as a heat source for the heat pump (3).

2. Device according to claim 1, characterized in that the exhaust system of the internal combustion engine (1), the cooling system (10) of the internal combustion engine (1) and generator (2) and in summer the Sollar collectors (13), on the primary side to the hot storage tank (4) and system modules (20; 27; 42) for the recovery and recovery of thermal energy from the building exhaust air, the waste water and during winter operation from the target collectors (13) and the cooling system (10) of the internal combustion engine (1) and the generator (2) on the primary side the cold storage (6) are connected.

3. Device according to claim 1 and 2, characterized in that the hot storage (4) and the cold storage (6) are stratified storage.

4. Device according to claim 1 and 2, characterized in that in the exhaust pipe of the internal combustion engine (1) as an alternative heat generating device, a gas burner (39), which is directly coupled to the hot storage tank (4) on the primary side, and an exhaust gas flow switch (35) for summer - and winter operation are provided.

5. Device according to claim 1 and 2, characterized in that the waste water line (19) of the building is connected to a waste water intermediate store (20) and the store (20) is connected to a heat exchanger in the cold store (6).

6. Device according to claim 1 and 2, characterized in that a supply air preheater (26) for conditioning the supply air of the ventilation system of the building in the return (14) of the heating / cooling installations (29; 28) is coupled.

7. Device according to claim 1 and 2, characterized in that an exhaust air recooling (27) is integrated in the ventilation system of the building and is thermally coupled to the cold store (6).

8. Device according to claim 1, 2 and 7, characterized in that in the heating / cooling flow (21) a mixer (18) turned on and the mixer (18) on the input side of the hot storage tank (4), each with a connection in the upper and middle area of the hot storage tank (4), the return (14) of the heating / cooling installations (28; 29) and the exhaust air recooling (27) of the building are connected.

9. Device according to one of claims 1 to 8, characterized in that the conversion to summer or winter operation by switching valves (11; 12; 22; 23) provided in the line connections of the respective system modules to the hot or cold storage (4; 6) are and the exhaust gas flow switch (35) and the valves (11; 12; 22; 23) and the switchover

(35) can be controlled via the electronic control unit (9).

10. Device according to one of claims 1 to 8, characterized in that the changeover to the heating or cooling mode is carried out by the changeover valves (11; 12;) and valves (41; 43; 44), which are via the mixer (18) are switched on in the heating and cooling flow (21), the valves (41; 43) and the changeover valve (12) with the hot storage tank (4), the valve (44) with the return flow (14) and the exhaust air recooling (27) and the changeover valve

(11) are connected to the cold store (6) and the exhaust air recooling (27).

11. Device according to one of claims 1 to 10, characterized in that the internal combustion engine (1) and the generator (2) are replaced by a fuel cell with an electronic inverter.