RU2768438C2 - Method of generating heat and electric power and a thermal electric generator - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention is intended for autonomous cogeneration of thermal and electric power due to energy contained in fuel and external air. Electric power is generated by a steam thermal power plant with its subsequent transfer to a consumer. Waste heat of power plant and heat of external air is transferred to cooler of heat pump and used for heat generation. For operation of the heat pump, the obtained electric power is used, and heat from the heater of the heat pump is transferred to the consumer. Also disclosed is a version of the proposed method, in which electric power is generated by a generator connected to an internal combustion engine, with subsequent transfer thereof to a consumer. Waste gases of internal combustion engine are supplied to heat-generating circulation circuit, in which in the process of natural or forced convection they are mixed with external air, heat of exhaust gases and heat leaving the internal combustion engine and generator is transferred to the heat pump cooler, and after cooling, the gas mixture is released from the circuit through the exhaust valve, wherein the heat pump is connected to the electric generator.

EFFECT: invention implementation enables to reduce fuel consumption and independence from ambient temperature.

4 cl, 5 dwg

Description

Technical field

The invention relates to the field of energy and is intended for autonomous cogeneration of thermal and electrical energy, and specifically for cogeneration using low-power electrical installations: Mini-, Micro CHP or Micro CHP.

State of the art

From the prior art methods of cogeneration of thermal and electrical energy by carrying out known processes of converting the energy of fuel and air into electricity and heat with the help of Mini-, MicroCHP or MicroCHP. (Wikipedia. Micro combined heat and power production - Micro combined heat and power. - Microturbine).

The general essential features of the described methods are:

- the use of chemical energy of fuel and atmospheric oxygen to generate electricity.

- transfer of waste heat with the help of a heat exchanger to the liquid heat carrier of the consumer's heat supply system

The following features coincide with the essential features of the invention:

- the use of chemical energy of fuel and atmospheric oxygen to generate electricity.

- transfer of waste heat with the help of a heat exchanger to the liquid heat carrier of the consumer's heat supply system.

Similar features, with the essential features of the invention, have the methods described in the following literature ["Construction Review" //Journal of Quality//, St. Petersburg, No. 5(32), May-June 1999, pp. 16-17; - Klaus Mollenhauer, Helmut Tshoke. Handbook of Diesel Engines. - Springer-Verlag, Berlin Heidelberg, 2010].

The technical problem to be resolved is that the known methods using the energy contained in the fuel with the help of Mini-, Micro CHP or Micro CHP, and cogeneration plants implementing such methods, are not economical. The generated electrical energy is only %: 20-35 of the fuel energy. Waste heat makes up the rest, and although a significant proportion of waste heat is used in Mini and Micro CHPs, energy losses are still at least 10%.

This gives rise to another problem - an environmental one: - emissions of exhaust hot gases (gas temperature in MiniCHP is up to 150°C, and in MiniCHP - up to 350°C). Combustion products dissipate in the atmosphere, contribute to the formation of smog containing harmful substances, including carcinogens.

The reason preventing the solution of this technical problem is that in order to utilize thermal energy, it is necessary to transfer it to another device or heat carrier of some system, for example, a building heat supply system. For this, heat exchangers are used. But according to the laws of heat transfer, the temperature of the utilized exhaust gases, or other heat carrier, must be significantly higher than the temperature of the heat carrier of the heat supply system.

Known methods of heat generation, or rather methods of transferring thermal energy from a low-temperature source to a higher temperature body using heat pumps (HP). But at the same time, it is necessary to spend the high-potential energy borrowed from outside [see. Brief polytechnical dictionary. State publishing house of technical and theoretical literature. M. 1956, p. 619. Art. "Reverse Carnot Cycle"].

The essential features of the known methods are:

- heat generation with the help of HP;

- the cost of high-potential energy HP operation.

Both of these features coincide with the essential features of the invention.

Air-to-air reversible heat pumps (HP) are known, for example, Mitsubishi Electric, model FDUM71VNXVF, having a four-way valve for reversing purposes, which allows the refrigerator and the HP heater to change roles, and thereby switch the room heating mode to the cooling mode, and vice versa .

A device is known, an air conditioner-heater designed to cool the air in rooms in the warm season and heat these rooms in the cold season [see. Description of the invention to the patent RU 2307290 C2 F24D 15/04 (2006.01), publ. 09/27/2007 Bull. No. 27]. The essential features of the device according to patent RU 2307290 C2 are:

- a heat exchanger-heater located inside the heated room;

- external heat exchanger-refrigerator;

- refrigerant-working fluid;

- compressor with electric drive;

- four-way valve and branch pipes connecting the units into a single unit;

- thermosiphons, in the form of vertical gravitational pipes, the evaporative parts of which are immersed in the ground, and the condenser parts protrude above the surface and are equipped with air heat exchangers;

- a thermally insulated casing, which contains heat pipe heat exchangers and an external heat exchanger-refrigerator;

- opening hatches of the casing;

- hatch drives with a control system, with outdoor air temperature sensors.

The following features coincide with the essential features of the claimed device:

- the heat exchanger which is in the room - a heater;

- external heat exchanger-refrigerator.

A technical problem that hinders the widespread use of methods and devices with HP is the decrease in the efficiency of methods and devices with a decrease in the temperature of a low-temperature source, for example, the most accessible - outside air.

The reason for the decrease in efficiency is the decrease in the efficiency of the heat transfer process with a decrease in the temperature of the low-temperature source. For example, air-to-air HPs operate with an energy conversion factor (COP) of up to 9 only at positive outdoor temperatures. At negative temperatures, COP decreases by more than three times.

Another technical problem is the supply of the installation with electrical energy, if it is intended to be used as part of an autonomous or mobile object. The reason is that the introduction of devices that generate electricity from solar energy or wind energy into the installation makes cogeneration dependent on the presence of the sun or wind, the use of heat engines with an electric generator worsens efficiency, and the use of low-temperature energy sources with a sufficient supply of heat, such as soil , groundwater requires complex and expensive earthworks, and is impossible for mobile objects.

Disclosure of the essence of the invention

The purpose of the present invention is to obtain a method for cogeneration of heat and electricity, which makes it possible to increase the efficiency of the use of thermal energy and create a device using this method, suitable for autonomous use in off-season and winter conditions in a wide range of objects:

- in individual housing construction;

- in other remote facilities, and where the use of central heat and power supply is not economically feasible or technically impossible;

- in transport, for example, in passenger rail transport;

- in mobile and rapidly erected objects of the Ministry of Emergency Situations;

- as an emergency or backup source of heat and electricity for socially significant and especially important facilities, etc.

This goal is achieved by the fact that in the method of generating heat and electric energy due to the energy contained in the fuel and air, the following is obtained:

- electrical energy;

- waste heat (including waste heat from hot units, heat from gases leaving the boiler unit, exhaust gas heat, etc.)

Further, in contrast to the above known methods, the waste heat is transferred by known methods to the HP refrigerator, where heat is transferred to the HP working fluid, and then the process of increasing the temperature of the HP working fluid and peleding heat to the heater transferring heat to the consumer is carried out.

To carry out the working process, HP uses the received electricity.

Transfer of all waste heat, i.e. The energy of fuel and air entering the Micro TPP, excluding the energy converted into electricity, is provided to the HP working fluid by a very low temperature of the HP cooler. For example, the popular refrigerant R410a boils at minus 48.5 C.

If, alternatively, an internal combustion engine (ICE) is used as a machine-engine in a Micro TPP, then the main carrier of waste heat will be hot exhaust gases, which greatly simplifies the implementation of the proposed method and the device that implements the method.

This method is carried out as follows:

- outdoor air and fuel are supplied to Micro TPP (CHP), where electrical energy and exhaust hot gases are obtained in a known way, mainly consisting of a mixture of fuel combustion products and excess air, including air used in the cooling system, with a temperature of 150 C up to 350 C;

- exhaust hot gases are fed into the heat-generating circulation circuit, mixed during circulation with the gases circulating in the circuit, to equalize the temperature of the mixture, passed through the heat pump cooler to cool the mixture and transfer heat to the working fluid of the heat pump, blow the cooled mixture over the units of Micro TPP, removing waste heat from aggregates and thereby increasing the temperature of the mixture, and again sent to the circulation circuit. The circulation is carried out due to the kinetic energy of the exhaust hot gases or in another known way (for example, using a fan, or convection in the Earth's gravitational field, due to the difference in temperature and density of the gas mixture).

- the excess of the cooled mixture is released to the outside through the exhaust valve.

- the heat of the mixture circulating through the HP refrigerator is transferred to the HP working fluid, and then the process of increasing the temperature of the HP working fluid and transferring heat to the heater, which transfers heat to the consumer, is carried out.

- for carrying out the working process HP use the received electricity.

A device for generating heat and electricity from the energy contained in the fuel, which implements the proposed method,

- heat and power generator (TEG) includes:

- Micro TPP, mainly incorporating internal combustion engines;

- Heat pump.

And also according to the invention has in its composition:

- a sealed housing forming a heat-generating circulation circuit;

- exhaust valve.

- Micro thermal power plant built into the housing so that the hot parts are cooled by the mixture of gases circulating in the housing;

- Exhaust system of Micro TPP, designed so that the kinetic energy of the outgoing exhaust gases maintains the circulation of the mixture of gases in the circuit and the mixing of the mixture.

The invention provides the following results:

• Full use of the energy contained in the fuel. This effect is due to the fact that the waste heat is introduced into the heat generating circuit, cooled there to the temperature of the mixture circulating in the circuit, and thereby gives up its heat to the mixture of gases and vapors circulating in the circuit. Since the circulating mixture of gases and vapors is continuously cooled in the HP cooler, the temperature of the mixture can reach the ambient temperature and even fall below. All thermal energy that has entered the circuit is pumped by the HP to the consumer, including the energy of water vapor condensation, the heat of condensate cooling, the heat of turning condensate into ice if the temperature of the mixture is below zero degrees. As a rule, this happens, since the heat output of the HP is greater than the waste heat generated by the mini thermal power plant, and the energy consumption of the HP is less than the generated electricity.

• Transfer of heat from the outside air to the consumer if the temperature of the circulating mixture is lower than the outside air temperature.

• Reduced fuel consumption, even compared to the heating option with the most modern gas boiler, due to the full use of the energy contained in the fuel and the additional energy of the outside air.

• Possibility of application on autonomous and mobile objects due to the use of Micro TES and outside air (including as a low-temperature energy source), which, therefore, ensures independence from extraneous energy sources.

Reducing the harm from products coming from the heat and power generator into the environment due to the low temperature of the gas component of the mixture leaving the TEG outside. It also facilitates the subsequent neutralization of harmful substances.

• Possibility of equipping the plant with used, mass-produced units and parts as the basis for high reliability of the plant.

• efficient and economical operation at low ambient temperatures, down to minus 60°С. The tightness of the heat generator housing makes it independent of the outside temperature, allows you to maintain the temperature of the mixture inside the housing in a wide range, and the use of electric heaters - and any ratio of thermal and electrical energy.

Brief description of the drawings

On FIG. 1 shows a block diagram of the method of cogeneration with a steam mini thermal power plant, where: 1 steam boiler, 2 - steam turbine, 3 - electric generator, 4 - consumer of electricity, 5 - heat pump refrigerator, 6 - heat pump, 7 - HP working fluid, 8 - condensate pump, 9 - outside air blower, 10 - cooling system of the unit units, 11 - heat pump heater, 12 - heat consumer,.

On FIG. 2 shows a block diagram of the method of cogeneration using a micro thermal power plant with an internal combustion engine, where: 1 - internal combustion engine, 2 - generator, 3 - consumer of electricity, 4 - exhaust gases, 5 - combustion products, 6 - excess air, 7 - heat generating circulation circuit, 8 - gas mixture heated by the units, 9 - HP cooler, 10 - HP, 11 - HP working medium, 12 - HP heater, 13 - heated gas mixture, 14 - cold gas mixture, 15 - exhaust valve.

On FIG. 3 shows a heat and power generator equipped with a microgas turbine unit - MicroGTU (microturbine) where: 1 - MicroGTU 2 - heat generating circuit, 3 - housing, 4 - consumer, 5 - heat pump, 6 - heat pump cooler, 7 - exhaust valve, 8 - working fluid HP, 9 - heat pump heater.

On FIG. Figure 4 shows a graph of the dependence of the COP coefficient on the outdoor air temperature according to the test data of the VT model FDUM71VNXVF from Mitsubishi Electric. Test conditions - indoor temperature 20 C.

In FIG. 5 shows the characteristics of the heat and power generator calculated using the data shown in FIG. 4. Symbols:

G _t is the energy contained in the fuel (analogue of fuel consumption);

Q - thermal energy received by the consumer;

E _in - thermal energy received by the consumer from the outside air;

E _g - energy generated by the electric generator;

E - electricity received by the consumer;

E _Z is the total electrical and thermal energy of the heat and power generator.

Implementation of the invention

On FIG. 1 shows an example of the implementation of the cogeneration method using a mini thermal power plant with a steam turbine and a steam boiler. In the steam boiler 1, high-pressure and temperature steam is produced by burning fuel, which is sent to the steam turbine 2, which converts the steam energy into mechanical energy, which is converted in the electric generator 3 into electricity, which is sent to the consumer 4. The gases leaving the furnace of the steam boiler 1 are sent to the refrigerator 5 of the heat pump 6, where they are cooled, transferring heat to the working fluid 7 of the heat pump 6, and then taken out. The crumpled steam after the turbine 2 is also sent to the refrigerator 5, where it is cooled and condensed, transferring heat to the working fluid 7. The condensate from the refrigerator 5 is sent to the condensate pump 8, which pumps the condensate into the steam boiler 1.

Outside air is supplied by blower 9 through the cooling system of units 10 to the turbine 2 and electric generator 3, and the heated air is sent to the refrigerator 5, where it is cooled, transferring heat to the working fluid 7 of the heat pump, and then taken out.

In the heat pump 6, the process of increasing the temperature of the working fluid 7 and transferring heat to the heater 11 of the heat pump is carried out to transfer heat to the consumer 12.

On FIG. 2 shows a block diagram of an exemplary implementation of the method of cogeneration due to the energy contained in the fuel and outdoor air, using a micro thermal power plant with an internal combustion engine.

The engine 1 is supplied with fuel and outside air, and, depending on the type of engine, the excess air ratio is from 1.2 to more than 5, taking into account the air taken into the internal combustion engine cooling system. In the generator 2, connected to the internal combustion engine, electricity is generated with its subsequent transfer to the consumer 3.

The heat of exhaust gases 4, consisting mainly of combustion products 5 and excess air 6, is fed into a heat generating circulation circuit 7, in which, in the process of natural or forced convection, the heat of exhaust gases 4 and waste heat from the internal combustion engine 1 and generator 2 8 is transferred to the refrigerator 9 of the heat pump 10, in which heat is transferred by means of the working fluid 11, to the heater 12 of the heat pump and further to the consumer, while the heat pump 10 is connected to the generator 2.

The hot mixture of gases 13, passing through the refrigerator 9, is cooled, and the cooled mixture 14 is sent to the generator 2, to the internal combustion engine 1 for their cooling, and is released from the circuit 7 through the exhaust valve 15.

On FIG. 3 shows a heat and power generator with a micro gas turbine unit (MicroGTU). The operation of the TEG is carried out as follows. MicroGTU 1 receives air and gaseous fuel. As a result, electricity and exhaust hot gases are obtained, consisting of products of combustion of fuel and excess air. The exhaust gases enter the heat generating circuit 2 formed by the housing 3. Electricity is supplied to the consumer 4 and to the heat pump 5. The exhaust system of the MicroGTU is designed so that the kinetic energy of the exhaust gases maintains the circulation of the gas mixture 6 in the circuit 2, equalizing the temperature and mixing the mixture.

The gas mixture, circulating, passes through the cooler 6 of the heat pump, where it cools, then blows over the MicroGTU units, removing the waste heat, and heats up again, mixing with the exhaust gases. Excess mixture is discharged to the outside through the exhaust valve 7.

From the refrigerator 6 of the heat pump, the heat with the working fluid 8 is transferred to the heater 9 and supplied to the consumer.

In some cases, for example, at a positive outside temperature, it is possible to supply additional air to circuit 2 with a blower, but the presence of a blower is not necessary for the operation of a heat and power generator.

The supply of outside air succeeds, as can be seen from the characteristics shown in Fig. 5, keep the temperature in the enclosure close to the outdoor temperature, if the power consumption does not exceed:

25% at an air temperature of 12°C;

20% at an air temperature of 0°С;

14% at air temperature minus 12°С;

10% at air temperature minus 18°С.

In these ranges, under these conditions, gases and condensate exit from the exhaust valve 7 with a temperature equal to the ambient temperature, and, therefore, the TEG fully uses the energy contained in the fuel - the higher calorific value. The above proves the achievement of the result of the full use of the energy contained in the fuel.

From the consideration of the flow of characteristics G _t /Q, it can be seen that in the same range of electricity extraction, fuel consumption decreases: with zero electricity extraction, fuel consumption decreases by 29% at a temperature of minus 18 C, by 42% at a temperature of minus 12 C, by 60% at temperature zero C, by 70% at a temperature of 12 C. The above proves the achievement of the result of reducing fuel consumption even in comparison with the heating option using the most modern gas boiler.

From the flow of characteristics it is also clear that with a real proportion of the heat required and the electricity required for domestic needs, the harmfulness of products coming from the heat and power generator into the environment is reduced due to the low temperature of the gas component of the exhaust and complete condensation of vapors.

From the above TEG scheme one can see the possibility of equipping the plant with used, mass-produced units and parts as the basis for high reliability of the plant.

, чем если бы отопление осуществлялось газовым котлом. Возможность генерации электроэнергии при этом сохраняется в пределах мощности электрогенератора. Вышеназванное доказывает достижимость независимости от наружной температуры.At very low ambient temperatures, it is possible to completely separate the internal cavity of the TEG case from the environment, while the TEG will operate with a slightly increased fuel consumption, but not

than if the heating was provided by a gas boiler. At the same time, the possibility of generating electricity remains within the power of the electric generator. The above proves the achievability of independence from the outside temperature.

Claims (4)

1. A method for generating thermal and electrical energy from the energy contained in the fuel and outside air, characterized in that electric power is generated by a steam thermal power plant with its subsequent transfer to the consumer, the waste heat of the power plant and the heat of the outside air are transferred to the heat pump refrigerator and used for heat generation, and for the operation of the heat pump, the received electricity is used, and the heat from the heater of the heat pump is transferred to the consumer. 2. A method for generating thermal and electrical energy from the energy contained in the fuel and outside air, characterized in that electricity is generated by a generator connected to an internal combustion engine, followed by its transfer to the consumer, the exhaust gases of the internal combustion engine are fed into a heat generating circulation circuit , in which, in the process of natural or forced convection, they are mixed with outside air, the heat of the exhaust gases and the waste heat from the internal combustion engine and the generator are transferred to the heat pump refrigerator and, after cooling, the mixture of gases is released from the circuit through the exhaust valve, while the heat pump is connected to electric generator. 3. A thermal power generator, including an internal combustion engine, arranged in a single unit with an electric generator, a heat pump, consisting of an indoor unit located indoors, including a heat pump heater, an external unit, including a heat pump refrigerator, and lines connecting them, characterized in that the engine internal combustion unit, the electric generator and the external heat pump unit are mounted in a single housing, forming a heat-generating circulation circuit for transferring exhaust gas heat and waste heat from the internal combustion engine to the heat pump cooler, while the housing is equipped with an exhaust valve. 4. Heat and power generator according to claim 3, equipped with an external air blower with an electric drive.

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