RU2782081C1 - Hybrid wall gas-electric boiler - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: invention relates to the field of heat power engineering of autonomous heat supply systems for producing hot water for heating and hot water supply. A wall-mounted boiler is proposed that operates with two sources of thermal energy: the energy of combustion of gaseous fuel at high power and the electric energy of thermal electric heating elements at low power. In the return line of the gas boiler, after the circulation pump, to the main heat exchanger of the gas boiler, a flow-through block of thermal electric heating is installed. To reduce heat losses through the chimney, an air valve is installed in the design of the hybrid wall-mounted boiler.

EFFECT: implementation of the invention makes it possible to create a hybrid wall-mounted gas-electric boiler operating in heating mode with a modulation equal to 50, which makes it possible to achieve the highest energy efficiency of wall-mounted boilers.

4 cl, 1 dwg

Description

The technical field to which the invention belongs

The invention relates to the field of heat power engineering of autonomous heat supply systems for obtaining thermal energy in the form of hot water for heating and hot water supply. The claimed design can be used in industrial and civil construction for heating and hot water supply in autonomous mobile and stationary facilities in the production of thermal energy by burning fuel gas and heating with electrical energy. Including in autonomous heating and hot water supply systems of multi-apartment buildings with different heights.

State of the art

For heat supply of individual houses and apartments, gas double-circuit boilers are often used as a heat generating device, containing a heating circuit and a hot water preparation circuit. The required heat output of the boiler is determined by the size of the heated room, the number of residents, the location of the facility and the total heat loss of the building envelope. In most cases, for a single family, the maximum power of the heat generator does not exceed 40 kilowatts per hour. From the point of view of ecology, greenhouse gas emissions, energy efficiency, gas boilers with a wide range of changes (modulation) of thermal power are currently the most efficient. Convection gas boilers account for 98% of the Russian market for heating equipment, have a power variation range from 40% to 100%, condensing boilers, which make up the remaining 2% of the Russian market, have the ability to regulate thermal output from 20% to 100%. Wall-mounted gas boilers with a capacity of up to 24 kilowatts are widely used as an alternative to centralized heating of apartments in multi-storey buildings. The total number of such autonomous heat supply systems in the Russian Federation is about 3 million.

In autonomous heat supply systems of objects with an area of up to 100 square meters, in most cases, double-circuit wall-mounted gas boilers are used with the possibility of using one heat generator for the heating circuit (primary circuit) and a second heat generator for preparing hot water (second circuit). Gaseous fuel burns in the chamber with the help of a burner and heats the heat exchanger, through which, under the action of the circulation pump, the coolant moves. Next, the heated coolant is sent to the heating circuit with the help of a distribution valve to transfer thermal energy to the heating devices of heated rooms or to the hot water preparation circuit for heating through the second cold water heat exchanger of the water supply system. The problem of operation of gas boilers of autonomous heat supply systems lies in the fact that the calculation of the power of heat generators according to currently existing standards is carried out on the basis of providing heat at an ambient temperature corresponding to the minimum five-day temperature over the past 50 years. Given the warming of the climate in recent years, as well as the fact that the heating period lasts from 5 to 7 months a year, most of the heating period, boiler plants should operate in a mode that is 10 times less than the maximum (calculated) power of the boiler. In particular, for apartments in multi-storey buildings located in the central strip of the Russian Federation, with an area of 45 square meters, the maximum heat loss at an ambient temperature of minus 25 degrees Celsius is no more than 2.5 kilowatts per hour, and the average heat loss during the heating period is 1. 2 kilowatts per hour. 2-3 months in the heating period of the year, heat losses are less than 1 kilowatt per hour, which is 25 times lower than the boiler power. Existing gas boilers cannot operate, as mentioned above, with such small heat loads. The boilers go into the operating mode of constant on-off, the number of which can be up to 20 times per hour. This mode of operation is off-design and leads to premature failure of the boiler. The operation of gas boilers in intermittent mode is accompanied by a sharp decrease in energy efficiency and increased emissions of carbon monoxide and other greenhouse gases. It is necessary to create a design that allows the heat generator to operate in a wide range of generated power, up to 50 times, that is, the boiler power must vary from 2% to 100%. The existing designs of gas burners of any gas boilers do not allow for such a wide range of changes in the power of thermal generation. A double-circuit wall-mounted gas boiler is known, containing a fan, a main heat exchanger, a temperature control sensor, a gas burner, an electric igniter, an electronic control unit, a heated water flow sensor for hot water supply, a gas valve, a heated water temperature sensor for hot water supply, a shut-off solenoid valve for the heating water circuit , shut-off solenoid valve of the secondary heat exchanger, heating water pressure sensor, fan operation sensor, automatic drain valve, safety valve, secondary heat exchanger, water pump, pressure pipe of the heating water circuit, return pipe of the heating water circuit, hot water supply pipe for domestic hot water, pipe cold water supply for heating, make-up pipe, make-up pipe check valve, return pipe check valve, secondary heat exchanger shut-off solenoid valve, make-up pump, make-up water tank, (see patent for utility model RU No. 160237 U1, IPC F24H 1/00 dated March 24, 2015).

The disadvantage of the invention is that this boiler belongs to convection gas boilers with a power control range from 40% to 100%, which does not allow the design to provide the necessary level of compensation for heat losses in the room at the minimum design temperatures and at atmospheric air temperature in the autumn-spring period. Most of the heated period of the year, this boiler operates in on-off mode, which leads to reduced energy efficiency, increased greenhouse gas emissions and additional economic costs.

The closest in technical essence is the patent DESIGN OF THE WATER HEATER (RU No. 2496061 C2, IPC F24H 1/20, published on October 20, 2013, Bull. No. 29).

A water heating system with a gas-fired water heater connected to a cold water inlet pipe and a hot water outlet pipe, characterized in that it additionally contains an electric storage-type water heater built in series into the hot water outlet pipe and equipped with a thermostat. An electric water heater is installed inside a gas water heater. The storage capacity of the electric water heater has a storage capacity of less than 20 liters.

The disadvantages of this design is that it is intended only for the preparation of hot water and does not solve heating issues. The electric water heater built into the boiler is of a volumetric type, and the main purpose of the system is to smooth out the temperature fluctuations of the heated running water at the start of hot water consumption or during periods of a sharp change in the volume of consumption. In this constructive solution, only one point is considered - the preparation of hot water. The issues of energy efficiency in space heating, the amount of greenhouse gas emissions are not considered.

Disclosure of the essence of the invention

The objective of the present invention is to develop a boiler having a modulation range in the full range of changes in the generated thermal energy. It is difficult to solve this issue by using one type of fuel as an energy source. Electric boilers have the widest range of regulation. It is quite simple to implement the possibility of changing the generated power in them, however, electricity is one of the most expensive types of fuel. Currently, most of the electrical energy is generated by gas turbines that burn gas and thermal power plants that burn coal, while emitting large amounts of greenhouse gases. The main part of the energy with this method of generating electricity goes into heat, and only about 35% is converted into electrical energy. The most efficient and environmentally friendly ways to generate thermal energy are to burn gaseous fuels and convert the generated heat into thermal energy in modern convection and, especially, condensing boilers. The efficiency of such systems ranges from 80% to 94% with respect to the gross calorific value of the combusted gas. However, as mentioned above, gas boilers, even condensing ones, are not able to operate at low heat loads, which are less than 10% of the maximum power of the boiler plant. In individual houses of small area, apartments in apartment buildings for more than a quarter of the heating season, and this period is up to two months a year, the required thermal energy for heating is less than one kilowatt per hour. Autonomous low-power boilers used for such premises are simultaneously used for both heating and hot water preparation. The required thermal power for the preparation of hot water significantly exceeds the power for heating even in the coldest period of the year. In the autumn-spring period, the required heating capacity is about 5% of the maximum boiler capacity. Gas boilers of any design cannot support this power level. To implement the task, it is advisable to use hybrid boilers that use the ability to work on two or more sources of thermal energy. A hybrid boiler is offered, operating in the full load power range from 2% to 40% for convection boilers and from 2% to 20% for condensing boilers, operating on electrical heating and, for the above ranges, on gaseous fuels. With regard to the option of a gas boiler with a capacity of 24 kilowatts per hour, a hybrid boiler, when working for heating in the range from 2% to 40% for convection boilers, which corresponds to a load of up to 10 kilowatts per hour, works like an electric boiler, and at a higher load - like a gas boiler . For condensing boilers, this range corresponds to: up to 5 kilowatts per hour as electric, at higher loads - as gas.

The technical result of the task is solved by creating a hybrid design of a wall-mounted boiler operating with two sources of thermal energy: the energy of combustion of gaseous fuel at high power and the electric energy of thermal electric heating elements located in the flow block of thermal electric heating, which is installed in the return line of the gas boiler, after circulation pump, to the main heat exchanger of the gas boiler. The use of this design of a hybrid wall-mounted boiler makes it possible to reduce total greenhouse gas emissions, since when a traditional gas boiler operates at low power, heat is generated in the mode of constant on-off (clocking). This mode of operation is accompanied by a sharp decrease in efficiency - up to 25%, reducing the life of the boiler up to two times.

Brief description of the drawings

The drawing shows a diagram of a hybrid wall-mounted gas-electric boiler, consisting of two circuits.

The design of the boiler consists of:

- main heat exchanger 1;

- combustion chambers of 2 wall-mounted boilers;

- burners 3 for heating the coolant as a result of combustion of gaseous fuel;

- fan 4 to remove combustion products;

- internal supply pipeline 5;

- internal pipeline return line 7;

- circulation pump 6;

- expansion tank 8 to compensate for thermal expansion of the coolant;

- three-way valve 9 for switching hot water and heating modes;

- plate heat exchanger for hot water preparation 10;

- pressure relief valve 11;

- air valve 12;

- valve for filling and feeding circuit 13;

- branch pipes for connecting hot water consumption: outlet 14 and inlet 15;

- supply pipe 16 of the heating circuit;

- return pipe 17 of the heating circuit;

- block of thermal electric heating 18 for heating the coolant;

- coolant flow channel 19, made in the form of a coil;

- thermal electric heating elements 20;

- air valve 21 for smoke removal.

Implementation of the invention.

The wall-mounted gas boiler operates in two modes: preparation of hot water in the hot water supply system (DHW) and heating (heating of the coolant of the heating circuit).

When the hybrid boiler is operating in heating mode (heating the heating medium of the heating circuit), two modes are possible.

If the required thermal power of the boiler to compensate for the heat losses of the room is less than 10 kilowatts per hour for convection boilers with a capacity of 24 kilowatts per hour, then the gas burner 3 does not work. The coolant is heated in the thermal electric heating unit 18. The coolant enters the boiler through the return pipe 17, passes successively the filling and make-up valves of the circuit 13, the air vent valve 12, and the pressure relief valve 11. Compensation for thermal expansion of the coolant is carried out by the expansion tank 8 compensation. The movement of the coolant is carried out by the circulation pump 6. The coolant enters the thermal electric heating unit 18 and moves along the tubular channel of the coolant flow 19, made in the form of a coil. Thermal electric heating elements 20 are also located in the thermal electric heating unit 18. To transfer thermal energy from the thermal electric heating elements 20 to the tubular channel of the coolant flow 19, made in the form of a coil, the space between them in the thermal electric heating unit 18 is filled with a material with high thermal conductivity . Further, the heated coolant through the internal return pipeline 7, the main heat exchanger 1, the internal supply pipeline 5, bypassing the three-way valve 9 for switching the hot water preparation and heating modes, installed in the heating position, enters through the supply pipe 16 of the heating circuit into the heating circuit (on not shown). To exclude heat losses through the chimney (not shown in the figure), an air damper 21 for smoke removal is installed after the fan 4 to remove combustion products.

If the required power of the proposed hybrid boiler exceeds 10 kilowatts per hour, then the thermal electric heating unit 18 of the coolant is turned off, the smoke exhaust air valve 21 opens, the fan 4 turns on to remove combustion products and the gas burner 3 is ignited. The coolant is heated in the main heat exchanger 1 of the chamber combustion of 2 wall-mounted boilers.

The use of two energy sources: electric with a required thermal power of up to 10 kilowatts and the energy of burning combustible gas with a higher value of the required thermal power, allows you to create a hybrid wall-mounted gas-electric boiler operating in heating mode (heating the coolant of the heating circuit) with modulation (change range thermal power) equal to 50, which allows you to achieve the highest energy efficiency of wall-mounted boilers.

In the hot water preparation mode of the hot water supply system (DHW), this boiler operates exclusively on gas, creating maximum heat output. Switching to the hot water preparation mode in the hot water supply system (DHW) is performed by a three-way valve 9, which directs the flow of heated coolant that occurs in the heat exchanger 1 of the combustion chamber 2 of the wall-mounted boiler using burner 3 to the plate heat exchanger for hot water preparation 10. Cold water enters through the inlet pipe 15. Hot water heated in the hot water preparation heat exchanger 10 enters the consumer through the outlet pipe 14. In the mode of operation of the boiler for preparing hot water in the hot water supply system (DHW), the smoke exhaust air valve 21 is constantly open.

The present invention in comparison with the prototype and other known technical solutions has the following advantages:

- the use of two energy sources: electric and gaseous fuel combustion energy allows you to create a hybrid wall-mounted gas-electric boiler operating in heating mode with a modulation of 50, which allows you to achieve the highest energy efficiency of wall-mounted boilers;

- reduced greenhouse gas emissions;

- preservation of the resource of the boiler;

- reduction of heat losses through the chimney.

Since the claimed invention differs from the closest analogue by a number of essential features, it meets the condition of patentability "novelty".

The claimed invention is based on the known laws of the material world, which allows us to assert that the invention meets the condition of "industrial applicability"

Since a hybrid wall-mounted gas-electric boiler is not known from the prior art, it can be concluded that the claimed device complies with the “inventive step” patentability condition.

Claims (4)

1. A wall-mounted gas-electric boiler for heating and hot water preparation, containing a main heat exchanger, a gas burner, a fan, an expansion tank, a circulation pump, a safety valve, an air vent valve, boiler internal pipelines, pipes for connecting heating and hot water circuits, a three-way switching valve modes of preparation of hot water and heating, characterized in that the design of the boiler is hybrid, using two sources of energy: electric to generate thermal energy at a power of from zero to 40 percent of the maximum power of the boiler and the combustion energy of gaseous fuel at a power of 40 to 100 percent of the maximum power boiler, for the implementation of which a block of thermal electric heating is built into the internal pipeline of the return line. 2. Wall-mounted gas-electric boiler for heating and hot water preparation according to claim 1, characterized in that the coolant flow channel in the thermal electric heating unit is made in the form of a coil. 3. Wall-mounted gas-electric boiler for heating and hot water preparation according to claim 1, characterized in that in the thermal electric heating unit, the space between the thermal electric heating elements and the coil is filled with a material with high thermal conductivity. 4. Wall-mounted gas-electric boiler for heating and hot water preparation according to claim 1, characterized in that an air valve is installed, which is closed in the heating mode when generating thermal energy by an electric source and is fully open in the operating mode when generating thermal energy by burning gaseous fuel.

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