RU2645107C1 - Autonomous gas fuel micro-tpp using a free piston stirling engine - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to the field of heat and power engineering and is intended to meet the heat and power requirements in industrial and residential premises in the absence of mains power supply. Summary of invention is that the device includes an electrogenerating device (18) module, which includes the Stirling engine (1), the main gas burner (2) to supply thermal energy to the engine head (1), a synchronous linear generator with permanent magnets (3), integrated into the motor housing (1), tuning resonance capacitance (11) at the linear generator (3) output and the engine (1) cooling system (10); converting power electronics (19) module, which includes an inverter (5), a rectifier (7), an electrical energy accumulator (4) and the common AC bus (6) to which the power generating device module (18) tuning capacitance (11) is connected; heat generating device module (20) comprising a heat generator (12), an additional gas burner (13) and an emergency cooler (14); module of adjustable ballast load (9) connected to the common AC bus (6) of the converting power electronics (19) module; automatic control system (17), which signals provide control over the above modules (18), (19), (20), (9) configured to monitor the current and voltage of the linear generator (3), Stirling engine (1) thermal head temperature and control over the activation of the linear generator (3) in a function of the Stirling engine (1) thermal head temperature regime.

EFFECT: technical result is an increase in the installation reliability and efficiency by improving the system dynamic stability under transient conditions that arise when electric or thermal loads surges, and also increasing the efficiency.

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Description

FIELD OF TECHNOLOGY

The invention relates to the field of thermal power and is intended to meet the needs for heat and electricity in industrial and residential premises in the absence of power from the network.

BACKGROUND

There are many applications for installations for the simultaneous production of heat and electricity of low power, capable of operating autonomously in remote areas for a long time. Currently, preference is given to using the Stirling free-piston engine as the main device in such installations. It has several advantages. First of all, it is a sealed unit that does not require maintenance and works synchronously, providing stable power output with low noise and vibration. Also, the Stirling engine has a long service life without maintenance, since it does not require oil lubrication, there is no crank mechanism and gearbox.

The prior art stand-alone multifunctional power plants (RU 2162532 C1, publ. 01/27/2001, RU 2450148 C2, publ. 06/10/2010, EP 3124878 A1, publ. 02/01/2017, CN 105443267 A, publ. 30.03.2016), including a Stirling engine with an electric generator, a fuel supply line, an engine cooling system connected through an heat exchanger to an external heat supply system. At the same time, these installations have significant design complexity and require increased energy consumption for their own needs.

Also known is an autonomous energy generating system (RU 2448260 C1, publ. 04/20/2012), which includes a boiler with lines for supplying fuel (gas) and oxidizer (air), a coolant circuit, an electric energy generator, the Stirling engine is used as its drive. The system is configured to convert the energy of the steam of the working fluid on the drive through the generator into electrical energy, which is supplied both to the network of direct current consumers, to the storage unit and through the inverter to the network of alternating current consumers. The generated electricity goes to consumers, and the excess goes to the accumulator block and to the terminals of the inverter, which converts direct current to alternating voltage of 220 V. This system has a complex structure that requires the use of several drives for auxiliary systems, and it does not have dynamic stability during transients .

The closest analogue in technical essence is a combined device for providing electric and thermal energy using a Stirling free piston engine and an additional heat exchanger with the supply of gaseous products of combustion from the main engine burner and additional burner (US 7459799 B2, publ. 02.12.2008). Said system comprises a Stirling engine, which includes a burner for supplying thermal energy to the engine head to actuate a reciprocating element and generating electricity by means of an alternating current generator, and a start-up system including a monitoring means for controlling the start-up of the unit, igniter for ignition of the burner, a pulse generator for supplying an electrical impulse to the generator to start the element making a reciprocating Tel'nykh motion when the control means determines that the engine head reaches the threshold temperature, and a local limited power source (battery) for supplying electric power control means, ignitor and pulse generator during the start-up operation. To supply an electric pulse to the generator for starting the engine, in a known solution, it is necessary to use a pulse generator, which provides a packet of pulses with a frequency of 50 Hz with a packet duration of up to 1 s to be sent to the stator winding of the generator.

Moreover, the known device has a low efficiency of using the thermal potential of the combusted fuel and insufficient system flexibility in the redistribution of thermal and electric energy.

SUMMARY OF THE INVENTION

The objective of the invention is to create a micro-CHP that generates thermal and electric energy in the absence of an external AC network. When using this installation, an improvement in the dynamic stability of the system during transient conditions arising from surges in electric or thermal loads should be achieved, as well as an increase in the efficiency of the device compared to existing analogues.

The technical result of the invention is to increase the reliability and efficiency of the installation.

The technical result is achieved due to the fact that an autonomous gas-fired micro-CHP using a free-piston Stirling engine, which provides thermal and electric energy, includes a module of an electric generating device (18), which includes a Stirling engine (1), the main gas burner ( 2) for supplying thermal energy to the engine head (1), a synchronous linear generator with permanent magnets (3) integrated into the motor housing (1), tuning resonant capacitance (11) at the output of the linear nerator (3) and cooling system (10) of the engine (1); a converter power electronics module (19), which includes an inverter (5), a rectifier (7), an electric energy storage device (4) and a common AC bus (6), to which a tuning capacitance (11) of the module of the power generating device (18) is connected ), a module of a heat generating device (20), which includes a heat generator (12), an additional gas burner (13) and an emergency cooler (14); an adjustable ballast load module (9) connected to a common alternating current bus (6) of the converter power electronics module (19); automatic control system (17), whose signals provide control of the above modules (18), (19), (20), (9), configured to control the current and voltage of the linear generator (3), the temperature of the thermal head of the Stirling engine (1) and controlling the inclusion of the linear generator (3) as a function of the temperature regime of the thermal head of the Stirling engine (1).

In addition, the storage of electrical energy (4) is a rechargeable battery.

In addition, the battery is connected to the input of the inverter (5) and the output of the rectifier (7), and the output of the inverter (5), the input of the rectifier (7) are connected to a common AC bus (6).

In addition, the useful electric load (8) is connected to a common alternating current bus (6) of the converter power electronics module (19).

Ensuring the autonomous operation of the system in the absence of an external AC network is achieved by turning on an inverter with a sinusoidal output voltage running continuously from the battery (drive) energy and providing start-up by the signal from the ACS controller and synchronization of the linear generator integrated into the Stirling engine .

Improving the efficiency of the device compared to analogues is due to the fact that the electrical load of the alternating current is connected directly to the alternating current bus without any converters. Power converters of the power electronics unit (inverter and rectifier) do not participate energetically in the load power supply. Their work provides only the integrity of the system, the launch and synchronization of the generator.

Depending on the direction of the generated energy in this system, the converter power electronics module performs the functions of both an inverter and a charger, which allows to expand functional stability.

Using an inverter allows you to cover rare peak overloads on a common AC bus, which improves the dynamic stability of the system during transients.

The use of ballast load allows to ensure the constancy of power consumption at the output of the generator module of the power generating device. In order to maintain the power balance, especially in transient conditions, the ballast load is regulated by the ballast load control module.

The use of an emergency cooler in a closed cooling system, which provides cooling of the engine and generator, allows for the adaptability of the operation of micro-thermal power plants when the heat load is released.

LIST OF DESIGNATIONS

RT1 - thermal power of the main gas burner

RT2 - thermal power of an additional gas burner

Loose 1 - thermal power carried away by the exhaust gases of the main burner

P exhaust 2 - thermal power carried away by the exhaust gases of the entire installation

РСО - thermal power of the cooling system

Rao - thermal capacity of the emergency cooler

RTN - heat load power

Rmeh - mechanical power developed by an engine

Rel - electric power of the generator

Ри - electric power consumed from the inverter

Rv - electric power consumed by the rectifier in the drive (AB)

Rzu - the electric power of the charger

Slave - the electrical power consumed by the battery

Ren - Electric Payload Power

RB - electric power of the ballast load

1 Thermodynamic converter (Stirling engine)

2 The main gas burner of the Stirling engine (thermal energy of gas combustion)

3 Electromechanical converter (linear generator)

4 Electric energy storage device (battery)

5 Voltage converter (inverter)

6 AC power adder (common bus)

7 Current transducer (rectifier)

8 Electrical load

9 Adjustable ballast load module (MRBN)

10 Engine / generator cooling system

11 Tuning Resonance Capacitance

12 Heat generator

13 Additional gas burner heat generator

14 Emergency Cooler (AO)

15 Chimney

16 Thermal load (VT)

17 Automatic control system (ACS)

18 Module power generation device (MEGU)

19 Converter power electronics module (MPSE)

20 Heat-generating device module (MTGU)

DETAILED DESCRIPTION OF THE INVENTION

The essence of the claimed invention is illustrated by the drawing, where in Fig. 1 a structural diagram of a micro-CHP is presented, which is an autonomous installation for the simultaneous production of electricity and heat.

Micro-CHPPs in general include a module of a power generating device (18), a module of a heat generating device (20), a converting power electronics module (19), an adjustable ballast load module (9), and an automatic control system (17) whose signals provide control of the above modules ( 18), (19), (20), (9).

The module of the power generating device (18) includes a Stirling free-piston engine (1), a main gas circular burner (2) for supplying thermal energy to the engine head, a synchronous linear generator with permanent magnets (3), integrated into the engine housing to provide electricity, tuning resonant capacity (11) at the output of the generator (3) and the engine cooling system (10).

The primary energy source of the proposed autonomous micro-CHP is thermal energy RT1, which is created by burning external supply fuel to the installation, and implemented on a circular gas burner (2), which is part of the Stirling engine (1). The fuel for this burner is combustible gas, which mixes with air (oxidizing agent).

In general, a system for supplying thermal energy to the engine head (1) includes a circular burner-type gas burner with injection of a combustible mixture (2) and (not shown in FIG. 1) a mixer (Venturi tube) for preparing a gas-air mixture; boost fan for supplying combustion air and regulating the amount of air-gas mixture; a valve assembly consisting of two shut-off gas valves and a membrane gas flow regulator with pneumatic feedback from a Venturi mixer to control the gas flow; safety controller that controls the ignition process and provides flame control using an ionization flame sensor; spark gap of the gas mixture ignition system and a pulse high-voltage transformer.

The flow of the mixture is supplied to the main burner (2) by a fan, which drives the Stirling engine in a manner well known in the art to generate power from a linear alternator (3).

To operate micro-CHPs seek to use mainly the supply of domestic gas, which is the most common source of fuel. However, other combustible gases may also be used, such as, for example, liquefied petroleum gas, liquefied natural gas or biogas, or liquid fuel.

Actually, the Stirling engine (1) is a thermodynamic converter of thermal energy into mechanical energy. Reciprocating motion.

The synchronous linear generator (3), integrated into the motor casing (1), is an electromechanical converter and provides electric power of alternating current Rel. The synchronous linear generator (3) generates an alternating voltage of 230 V with a frequency of 50 Hz due to the reciprocating motion of the inductor with permanent magnets relative to the fixed stator winding.

The tuning resonant capacitance (11) at the output of the generator (3) is tuned to a frequency of 50 Hz, which provides correction of the power factor of the generation module, compensating for the voltage drop across the inductance of the stator winding of the linear generator (3).

The tuning tank (11) is connected to a common AC bus (6). Since the electric load (8) is connected directly to the output of the generator (3) through the tuning capacitance (11), bypassing the converter devices of the inverter (5) and the rectifier (7), this connection allows to increase the efficiency of the device.

The module of the heat generating device (20) includes an additional gas burner (13), a heat generator (12) connected to the emergency cooler (14) and configured to be connected to a heat load (16).

Heat is removed from the engine (1) of the module of the power generating device (18) by a cooling system (10), which is essentially a heat exchanger through which water is pumped (not shown) by a pipeline (not shown) to a heat generator (12) ) module heat generating device (20). The cooling system (10), in general, consists of pipelines of the local cooling system and shutoff valves. The inlet and outlet pipes of the cooling system (10) are equipped with temperature control sensors (thermistors), and a coolant flow sensor is also installed on the inlet pipe. The temperature of the inlet water is not lower than + 6 ° C, and the temperature at the outlet of the cooling system is not higher than + 75 ° C.

The converter power electronics module (19) includes an inverter (5), a rectifier (7), an electric energy storage device (4), and a common AC bus (6), to which the output of the module of the power generating device (18) is connected. The electric energy storage device (4) is a rechargeable battery, which acts as an electric energy storage device and is connected to the inverter input (5) and the rectifier output (7). The inverter output (5), the rectifier input (7) are connected, in turn, to a common AC bus (6).

The battery can deliver the accumulated electrical energy to the DC slave through a voltage / voltage converter DC / AC inverter (5) to a common AC bus (6).

The adjustable ballast load module (9) and the useful electric load (8) are connected to a common alternating current bus (6) of the converter power electronics module (19).

The automatic control system (17) contains an engine controller (1), controllers for the main (2) and additional (13) gas burners, control boards for the modules of the electricity generating device (18), heat generating device (20), converter power electronics (19) and adjustable ballast load (9), providing the necessary algorithm for the entire system. Moreover, the motor controller (1) is configured to control the current, frequency and voltage of the linear generator (3), the temperature of the thermal head of the Stirling engine (1), control the inclusion of the linear generator (3) as a function of the temperature regime of the thermal head of the Stirling engine (1).

The following signals are received from the engine controller (1) from sensors integrated into the Stirling engine housing (1): measured effective values of current, voltage and frequency at the generator output (3); current (controlled) and limit temperature of the thermal head of the Stirling engine (1) (thermocouple signals); engine body temperature (1) (thermistor).

In addition, additional signals from external sensors are received in the engine controller (1): ambient temperature (thermistor); temperature at the inlet and outlet of the cooling system (10) (thermistors); exchange rate (flow rate) of the cooler; tachometer signal of the air supply fan.

The engine controller (1) generates the following signals and performs the functions:

- turning on the gas burner controller;

- fan control (fan motor power);

- a starting pulse for starting the Stirling engine (1) when a certain temperature of the thermal head of the Stirling engine (1) is reached;

- controls the current temperature of the thermal head of the Stirling engine (1);

- determines the current output electric power from the linear generator (3) of the module of the power generating device (18);

- generates a signal about the output of the micro-CHP system to the nominal mode.

In addition, the automatic control system (17) monitors the consumption of thermal energy by the heat load (16), during the discharge of which the emergency cooler (14) is included in the operation, and regulates the operating mode of the ballast load (9) when the electric load is reset (8).

The common bus is conventionally represented by a power adder (6), one input of which receives the electric power of the generator (3) Rel, the second input receives the electric power of the inverter (5) Ри, the third input of the adder Рв is connected to the current type converter - rectifier (7), which performs the function of a charger, recharging the drive - a rechargeable battery (4) with a power of Rzu, and the fourth input of the adder Rn is connected to the payload Reng (8) and the ballast block RB (9), so that the total electric load dressing will be Pn = Ran Rb +.

The overall balance of electrical power on a common AC bus can be written as follows: Rel + Ri-Rn-Rv = 0.

If Рн≥Рел, then the inverter (5) gives additional power Ри to the common bus, consuming the energy of the drive Slave, and the load is powered by the energy of the generator (3) and inverter (5).

If Rn≤Rel, then the rectifier (7) provides recharge of the battery (4) with part of the power of the generator Rel (3). In this case, the inverter (5) performs only the function of a reference voltage source for a common AC bus (6).

The purpose of the ballast load is to ensure the constancy of power consumption at the output of the generator (3) of the module of the power generating device (18). The higher the payload current (8), the lower the ballast load current (9). The power Rel generated by the generator (3) is distributed between the useful (8) pH and ballast loads (9) RB and should remain constant in both steady-state and transient processes (when the payload is dropped or dumped).

,

,

 where Rel is the power at the output of the generator (3); Ren - payload power; RB is the power of the ballast load; Rsn - power of own needs (power of the pump, fan, secondary power source, etc.).

The work of an autonomous micro-CHP is as follows.

After receiving a signal about the completion of diagnostics of the state of micro-CHP modules, the automatic control system (17) allows the power supply from the battery (4) to the gas burner controller (2), which is part of the automated control system (17), which includes a boost fan for combustion air supply, and after a while the gas valve of the system for supplying thermal energy with a power of PT1 of the module of the power generating device (18) is turned on.

At the same time, a pulse ignition signal of the gas mixture is supplied to the ignition unit from the gas burner controller (2). Upon successful ignition, a flame signal appears and the temperature of the thermal head of the engine begins to increase (1). When the heat head reaches the start resolution temperature (+ 170 ... 210 ° C) by the signal from the engine controller (1), which is part of the automated control system (17), the stator winding of the linear generator (3) is connected through the tuning resonant capacitance (11) to a common AC bus (6), which causes a reciprocating motion of the inductor of the linear generator (3). The time required to reach the required thermal regime is up to 2 minutes, depending on the ambient temperature.

As the temperature of the thermal head of the engine (1) increases, the electric power at the output of the linear generator (3) increases, and after 8 minutes, when the temperature of the thermal head reaches 550 ° C, the system reaches a rated power of 1 kW.

The cooling of the engine (1) and linear generator (3) is carried out from a closed cooling system equipped with an emergency cooler (14) of a free-convection type.

Heat is removed from the engine (1) of the module of the power generating device (18) by the cooling system (10), through which water is pumped through the pipeline into the heat generator (12) of the heat generating device module (20). The water passing through the cooling system (10) is then additionally heated in the heat generator (12) by the gaseous products of combustion. from the main burner of the engine (2), which heats the thermal head of the Stirling engine (1). The thermal energy Ptn is provided by a heat generator (12).

Without some need for waste heat, the Stirling engine (1) cannot work, since the water temperature at the inlet of the engine cooling system (10) should be lower than at the outlet. The engine controller (1) receives signals from temperature control sensors installed on the inlet and outlet pipes of the cooling system (10).

To discharge the generated heat, the heat capacity of the radiators of the local heating system that are part of a closed cooling system can be used. But in those cases when the radiators are turned off, and hot water is not required, the water temperature will gradually rise. In this case, the autonomy of the micro-CHP will be ensured by the use of an emergency cooler (14) to discharge heat. In the case when the water temperature at the outlet of the cooling system (10) is lower than at the inlet, a signal is sent from the control board of the module of the heat-generating device (20) to turn on the emergency cooler (14).

Thus, an autonomous micro-thermal power plant generates the supplied electric power Rel and thermal power Ptn, which can be used, for example, to provide household needs for electricity and hot water or to power a central heating system or both.

In order to provide additional heating and to create some degree of independence for heating water in the module of the heat generating device (20), when the Stirling engine (1) does not work at full electric power, an additional burner (13) is provided for heating water in the heat generator (12), operating similarly to the main gas burner (2). The controller of the additional gas burner (13) is supplied with a control signal by an automatic control system (17), which includes a boost fan for supplying air, which is mixed with the gas supplied to the burner (13). After some time, the gas valve of the system for supplying thermal energy with a power of PT2 of the module of the heat-generating device (20) is turned on.

Gaseous products of combustion with a thermal power Rvyhl. 1 from the main burner (2) of the engine (1) and additional burner (13) of a heat generator (12) with a thermal power of PT2, which transferred their heat to the heat generator (12), then are discharged into the atmosphere through a chimney (15) with a thermal power of Rhym. 2.

Coordination of the modules of the heat generating device (20) and the power generating device (18) is as follows.

When the demand for heat and electricity is large, an additional gas burner (13) of the module of the heat generating device (20) is turned on. In this case, the engine (1) of the module of the power generating device (18) will operate at the maximum temperature of the heat head provided by the main gas burner (2). Electric energy in this case will be spent on power supply to the load (8) and battery charge (4).

On the other hand, the demand for heat can be low, while the demand for electricity is high. In this case, the additional gas burner (13) either turns off or does not turn on at all.

In cases where there is a need for heat and a small need for electric energy, the Stirling engine (1) must work to generate sufficient power (approximately 200 W) for the micro-TPPs own needs (power supply to servicing devices, control circuits, pumps and fans) . Power will be generated by the main gas burner (2) of the engine (1) when it is set to the minimum output.

The proposed stand-alone power supply device can operate in the following modes:

1. The consumption of electric energy in the load (8) only from the linear generator (3), when the inverter (5) acts as a reference voltage source for a common AC bus (6).

2. The consumption of electric energy in the load (8) from the linear generator (3) and inverter (5) at the same time with an abrupt increase in load. In this case, the inverter (5) gives additional power to the common bus (6), consuming the energy of the battery (4).

3. The consumption of electric energy in the load (8) from the generator (3) and the battery charge (4) as part of the generator power (3).

4. The consumption of electric energy from the generator (3) in the payload (8) and the ballast load (9) during the jump-like discharge of the payload.

5. Consumption of thermal energy by a thermal load, during the discharge of which an emergency cooler is included in the operation (14).

Thus, the created micro-CHP with the possibility of generating heat and electricity according to the present invention is completely autonomous and has improved dynamic stability of the system during transient conditions arising from surges in electrical or thermal loads.

The above description illustrates and in no way limits the present invention. Although the present invention has been described with reference to an exemplary embodiment, it should be understood that the explanations used herein are illustrative and not restrictive. Changes may be made within the scope of the appended claims. Although the present invention is described herein with reference to specific means, materials and embodiments, the present invention is not limited to the details disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods, and applications that are within the scope of the appended claims.

Claims (9)

1. Autonomous gas-fired micro-CHP using the Stirling free-piston engine, which provides thermal and electrical energy, including: - a module of an electric generating device (18), which includes a Stirling engine (1), a main gas burner (2) for supplying thermal energy to the engine head (1), a synchronous linear generator with permanent magnets (3) integrated into the engine body ( 1) tuning resonance capacitance (11) at the output of the linear generator (3) and cooling system (10) of the engine (1); - a converter power electronics module (19), which includes an inverter (5), a rectifier (7), an electric energy storage device (4) and a common alternating current bus (6), to which a tuning capacitance (11) of the module of the power generating device is connected ( eighteen); - a module of a heat generating device (20), which includes a heat generator (12), an additional gas burner (13) and an emergency cooler (14); - an adjustable ballast load module (9) connected to a common alternating current bus (6) of the converter power electronics module (19); - an automatic control system (17), whose signals provide control of the above modules (18), (19), (20), (9), configured to control the current and voltage of the linear generator (3), the temperature of the thermal head of the Stirling engine (1 ) and controlling the inclusion of the linear generator (3) as a function of the temperature regime of the thermal head of the Stirling engine (1). 2. An autonomous micro-CHP according to claim 1, characterized in that the electric energy storage device (4) is a storage battery. 3. The stand-alone micro-CHP according to claim 2, characterized in that the battery is connected to the input of the inverter (5) and the output of the rectifier (7), and the output of the inverter (5) and the input of the rectifier (7) are connected to a common AC bus ( 6). 4. Autonomous micro-CHP according to claim 1, characterized in that the useful electric load (8) is connected to a common alternating current bus (6) of the converter power electronics module (19).

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