DE202015103407U1 - Combined heat and power system - Google Patents

Abstract

Combined heat and power system for generating electrical and thermal energy by burning solid biomass in a heat generator (1), the system comprising an ORC circuit (4) with a working fluid, a turbine (7) and with the turbine (3). 7) mechanically connected power generator (8) for generating the electrical energy and a condenser (10) for generating the thermal energy and a working fluid pump (12), characterized in that - the system comprises a Zwischenwärmekreislauf (2) with thermal oil as the intermediate heat transfer medium wherein the intermediate heat circuit (2) a first, arranged in the heat generator heat exchanger, and a second, designed as an evaporator (6) of the ORC circuit (4) and a third (5) in the ORC circuit (4) in the flow direction of the working fluid before the evaporator (6) arranged heat exchanger and a thermal oil pump (3) comprises; - the working fluid of the ORC circuit (4) is a fluoroketone; - The working fluid pump (12) is a piston diaphragm pump with a membrane of ethylene-propylene-diene rubber; - The turbine (7) is a radial turbine, on the turbine shaft, the power generator (8) is arranged; and - the heat generator (1), the intermediate heat circuit (2) and the ORC circuit (4) are formed as a unit.

Description

The invention relates to a combined heat and power (CHP) system that provides electrical power and thermal energy at a heating-standard level based on the thermal utilization of solid biomass.

For years, little attention has been paid to the use of secondary forms of energy that can be extracted from primary energy sources. Today, therefore, there is a particular need to make the most of primary energy sources in order to extract the largest possible amount of energy in every possible form from the latter with the aim of saving primary energy and reducing pollutant emissions.

To achieve this goal, for example, so-called combined heat and power plants have been set up, which generate electrical and thermal energy from a single source and in a single process.

From the prior art are for these combined heat and power plant process concepts for the use of stored in biomass chemical energy by combustion and a subsequent cycle, for example steam power or ORC process in which the heat energy proportionate to mechanical energy and finally into electrical energy is converted, known.

During combustion, the chemical energy of the biomass is first converted into thermal energy. The combustion is followed by steam generation or only heat transfer to a carrier medium such as water or air. When converted to thermal energy, high efficiencies of up to 90% can generally be achieved.

There are a number of technical possibilities of generating electrical energy, z. B. obtained by a combustion process, thermal energy. A well-known, highly efficient method is, for example, the conversion of thermal energy into mechanical energy and further into electrical energy using the generator principle.

While steam power plants with steam turbines dominate the use of solid fossil fuels in large-scale plants, different processes compete for the smaller plants required for biomass use. This is mainly due to the fact that the steam power processes are associated with steam turbines in smaller sizes with poor efficiencies.

In particular, in the case that the available temperature gradient between heat source and sink is too low for the operation of a steam driven turbine, the Organic Rankine Cycle (ORC) process is used instead of the steam power process.

The ORC process is a process of steam turbine operation that uses organic liquids with a low evaporation temperature as the working medium instead of water vapor.

The main problem with high power centralized cogeneration plants is their relatively high installation costs, since these systems require both connection to an electrical distribution network and a distribution network of thermal energy. Such combined heat and power plants therefore require high initial investment.

For the use of a small cogeneration system, d. H. With an electrical power of 10 kW maximum and a maximum thermal output of 65 kW, the approaches pursued so far are associated with excessively high investment costs. A major disadvantage of turbomachines with a small volume flow are also the relatively low efficiencies, d. H. for turbomachines with low power losses in classical run and Leitradsystemen are too large. What is needed, therefore, are novel systems which have sufficiently high efficiency as well as a low cost construction and a simple, ie. H. cost-effective with little technical effort, operation permit.

The DE 10 2010 047 520 A1 describes a device for energy recovery of the heat energy contained in the exhaust gases of a motor vehicle. The system described here comprises a first circuit through which flows a medium which absorbs the heat from the exhaust gases of the vehicle engine and a second ORC circuit through which flows an organic medium which is suitable for exchanging the heat with the medium. that flows in the first cycle. The ORC cycle includes a turbine driven by the organic medium vaporized to produce power. The energy recovery device also includes an electric motor which receives mechanical power from the turbine and is either adapted to supply electrical energy to an accumulator connected thereto or to provide mechanical energy to the motor shaft of the vehicle.

However, this energy recovery device is not optimized for pure power generation and is not suitable for feeding electrical energy into a power grid.

The object of the invention is to provide a combined heat and power (CHP) system for a stationary, decentralized generation of electrical and thermal energy in the electric power range of less than 10 kWel and in the thermal power range of up to 65 kWth is characterized by a compact design and high efficiency, the system should be inexpensive to install and operate. In addition, should be used for the operation of the system regenerative energy sources, such as wood or halmgutartige biomasses.

The solution of this task is carried out according to protection claim 1; expedient embodiments of the invention can be found in the subclaims.

According to the invention, a stationary, compact CHP system is provided, whose power level is a maximum of 10 kWel and 65 kWth, wherein the thermal energy provided is at a heating standard level.

The CHP system includes a boiler, an intermediate heat cycle and an ORC cycle.

In the boiler, which is designed as a solid fuel boiler, heat energy is generated by combustion of preferably solid, renewable biomass, such as wood, which in a, arranged in or on the boiler, heat exchanger to a thermal oil, which acts as an intermediate heat transfer medium of the intermediate heat cycle transmitted becomes.

The boiler and the heat exchanger are preferably designed such that during operation of the CHP system, the thermal oil after heating has a temperature of about 200 ° C.

The intermediate heat cycle has a fluid energy machine, for. B. in the form of a thermal oil pump, which causes a continuous flow of thermal oil in the intermediate heat cycle during operation of the CHP system, the aforementioned heat exchanger for the transmission of heat energy generated in the boiler to the intermediate heat cycle and other heat exchangers for the transmission of heat energy from the intermediate heat cycle to the ORC cycle of the CHP system.

The heated thermal oil transfers the (heat) energy to the ORC circuit, preferably by means of a respective heat exchanger designed as an evaporator and a preheater, wherein the evaporator is arranged in the intermediate heat cycle in the flow direction in front of the preheater, so that the remaining in the thermal oil after passing through the evaporator remaining thermal energy in the preheater for heating the working fluid of the ORC circuit is available.

In the ORC cycle, the organic working fluid heated in the preheater is evaporated in the evaporator while absorbing heat energy. A portion of the energy absorbed by the vaporized working fluid is withdrawn as mechanical energy at a, in the ORC circuit in the flow direction of the working fluid behind the evaporator arranged turbomachine, preferably a turbine, the circuit.

This turbomachine is coupled in a fixed unit with a power generator, with which from the generated by means of the turbomachine mechanical energy electrical energy in a power range up to 10 kW can be generated.

This electrical energy can be fed into it using a phasing panel connected in parallel to a public or private power grid.

The working fluid flowing out of the turbomachine is further passed through a heat exchanger (ie, an internal heat exchanger) designed as a recuperator, which, during operation of the system, transfers part of the thermal energy of the working fluid back to the working fluid of the ORC cycle already at this position of the circuit that flows into the preheater.

In a downstream of the recuperator arranged in the flow direction heat exchanger, hereinafter referred to as the condenser, the still gaseous working fluid is condensed with release of heat energy. The condensation takes place z. B. at a pressure of about 2.6 bar and a temperature of about 80 ° C. The main part of the energy in the form of thermal energy is withdrawn from the ORC cycle.

The condenser may be connected to a heating circuit for heating buildings and preferably operates at temperatures in the range of 65 ° C to 80 ° C, i. H. at a heating standard.

The ORC circuit further includes a working fluid collector disposed downstream of the condenser. The collector is designed so that the entire circulating in the ORC cycle working fluid (in liquid form) is receivable.

Via a working fluid pump of the ORC circuit, the working fluid flowing out of the collector is forced back to the evaporator via the recuperator and the preheater. As a working fluid pump, a piston diaphragm pump with EPDM (ethylene-propylene-diene rubber) membrane is preferably used.

The working fluid of the ORC cycle is preferably a fluoroketone having a boiling point well below 100 ° C.

The CHP system according to the invention is designed such that all essential components, ie. H. Boiler, intermediate heat circuit and ORC circuit with turbine and power generator to form a single unit. Thus, the CHP system is completely in a single, relatively small housing, z. B. a 40-foot ISO container, housed.

A major advantage of the CHP system is its small dimensions in terms of both electrical and thermal power generation as well as in terms of its dimensions, the system is efficiently operated despite these small dimensions due to the use of a fluoroketone as working fluid in the ORC cycle.

Thus, the CHP system can be used inexpensively, decentralized.

A second advantage of fluoroketone is its negligible impact on global warming, if it is, for. B. by an accident, enters the atmosphere.

Another advantage of fluoroketone is its non-combustibility. Therefore, the fluid is particularly suitable for use in close proximity to solid fuel firing.

According to one embodiment, the turbine is a radial turbine, wherein the power generator is arranged directly on the turbine shaft.

The invention will be described in more detail with reference to the accompanying figure, which shows a block diagram of the CHP system according to the invention.

In the special biomass boiler 1 solid biomass is converted by combustion technology. In the heat exchanger 1.1 The boiler body is thereby thermal oil, which in the intermediate heat cycle 2 by means of the thermal oil pump 3 is heated, heated to a temperature of about 200 ° C. In the intermediate heat cycle 2 are also the preheater 5 and the evaporator 6 arranged the thermal energy on the ORC cycle 4 transfer. In the evaporator 6 the working fluid fluoroketone of the ORC circuit vaporizes 4 at a temperature of about 160 ° C and a pressure of about 15.9 bar and drives the turbine 7 - here in the form of a radial turbine - on. This is in solid unity with the generator 8th coupled, by means of which electrical energy in the power range up to 10 kW can be generated.

The working fluid continues through the recuperator 9 which transfers a portion of the thermal energy of the fluoroketone to the fluorocarbon stream to the evaporator 6 transfers. In the condenser 10 the fluoroketone is condensed at a pressure of about 2.6 bar and about 80 ° C. The condenser is connected to a heating circuit for heating buildings (not shown). In the collector 11 the fluoroketone is stored. The working fluid pump 12 , here a piston diaphragm pump with EPDM membrane, presses the fluoro ketone through the ORC circuit 4 ,

LIST OF REFERENCE NUMBERS

1

Heat generator / boiler

1.1

Heat exchanger

2

Between heat cycle

3

Thermal oil pump

4

ORC cycle

5

Heat exchanger / preheater

6

Heat exchanger / evaporator

7

turbine

8th

power generator

9

Heat exchanger / recuperator

10

condenser

11

Working fluid storage

12

Working fluid pump

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010047520 A1 [0012]

Claims (6)

Cogeneration system for generating electrical and thermal energy by burning solid biomass in a heat generator ( 1 ), the system has an ORC circuit ( 4 ) with a working fluid, a turbine ( 7 ) and one with the turbine ( 7 ) mechanically connected power generator ( 8th ) for generating the electrical energy and a condenser ( 10 ) for generating the thermal energy and a working fluid pump ( 12 ), characterized in that - the system has an intermediate heat cycle ( 2 ) with thermal oil as the intermediate heat transfer medium, wherein the intermediate heat cycle ( 2 ) a first, arranged in the heat generator heat exchanger, and a second, as an evaporator ( 6 ) of the ORC cycle ( 4 ) trained and a third ( 5 ), in the ORC cycle ( 4 ) in the flow direction of the working fluid in front of the evaporator ( 6 ) arranged heat exchanger and a thermal oil pump ( 3 ); The working fluid of the ORC cycle ( 4 ) is a fluoroketone; - the working fluid pump ( 12 ) is a piston diaphragm pump having an ethylene-propylene-diene rubber membrane; - the turbine ( 7 ) is a radial turbine, on whose turbine shaft the power generator ( 8th ) is arranged; and - the heat generator ( 1 ), the intermediate heat cycle ( 2 ) and the ORC circuit ( 4 ) are formed as a unit. Cogeneration system according to claim 1, characterized in that it comprises a parallel to a public or private power grid connected switch panel comprising phase adjustment devices and a control device which is designed such that the phase adjustment devices are controlled by him. Cogeneration system according to claim 1 or 2, characterized in that the ORC circuit ( 4 ) one between condenser ( 10 ) and working fluid pump ( 12 ) arranged memory ( 11 ) for the working fluid. Cogeneration system according to one of claims 1 to 3, characterized in that the ORC circuit ( 4 ) one between working fluid pump ( 12 ) and the third heat exchanger ( 5 ) and between turbine ( 7 ) and liquefier ( 10 ) arranged recuperator ( 9 ) having. Combined heat and power system according to one of the preceding claims, characterized in that the heat exchanger ( 1.1 ) comprises one or more tubes passing through the heat generator ( 1 ) are guided. Cogeneration system according to one of the preceding claims, characterized in that in the heat generator ( 1 ) renewable, solid biomass for use of energy stored therein can be used.

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