RU2338141C1 - Installation for recovery of waste furnace gas heat - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention is related to installation of waste furnace gas heat. Installation contains heating furnace with working chamber, in which fuel burners are installed, as well as heat-insulated channel with heat-exchanging tubes, along internal surface of which combustion products are removed from furnace working chamber, at that part of internal surface of heat-insulated channel is formed by engine cylinder with external heat supply, with which heat-exchanging tubes are connected. Being installed on internal surface of heat-insulated channel, cylinder and heat-exchanging tubes remove heat from high-temperature waste furnace gas to working body of engine with external supply of heat, in which heat is transformed into mechanical energy with high efficiency factor. Ribbing of engine cylinder surface intensifies the process of heat removal from waste furnace gas and promotes increase of power and efficiency factor of engine.

EFFECT: provision of more efficient usage of fuel combustion heat in heating and thermal furnaces of forge production.

2 cl, 2 dwg

Description

The invention relates to thermal equipment, in particular to installations for the utilization of heat of exhaust gases from heating and thermal furnaces in forging and stamping.

Known devices for using the heat of the exhaust furnace gases in a heat exchanger (recuperator) installed in the exhaust duct to heat the air entering the fuel burners of the heating furnaces [G. Nemzer Thermotechnology of forging and pressing production. - L .: Mechanical Engineering, 1988, p.208-210]. The efficiency of using the heat of the exhaust gases in the recuperators does not exceed 20-30%, is limited by the limiting temperature of air heating for fuel burners and cannot be used when starting and stopping flame furnaces.

As a prototype, a device has been adopted for cooling and utilizing the heat of the exhaust gases from the furnace [RF Patent No. 2082929, IPC F27D 17/00, publ. 05/27/2003, Bull. No. 15], comprising a heating furnace, a channel that removes combustion products from a heat exchanger in which a liquid metal coolant (liquid sodium) circulates, a steam-water circuit with a steam turbine installation and a steam generator heated by a liquid metal coolant. The liquid metal coolant allows heat to be removed at high temperature, to obtain steam with high thermodynamic parameters in the steam generator, and to ensure the operation of the steam turbine unit with high efficiency However, this cooling and heat recovery device has a complex structure and low efficiency in small flame heating and thermal furnaces located at significant distances from each other in the forging and stamping industry. The periodic mode of operation of heating thermal furnaces also leads to additional energy costs when starting and stopping a known device and further reducing its efficiency

The technical result of the invention is to increase the efficiency of heat recovery installations of exhaust furnace gases operating with heating and thermal furnaces of forging and stamping production under conditions of periodic shutdown of furnaces for technological reasons.

To achieve a technical result in the proposed installation of heat recovery of exhaust gas of a furnace containing a heating furnace with a working chamber with fuel burners, a heat-insulated channel with heat-exchange pipes of the heater through which combustion products are removed from the furnace, in the initial part of the inner surface of the heat-insulated channel there is a cylinder with an engine piston with an external heat supply, which is connected to heat exchange pipes to ensure the movement of the working fluid in them. In this case, the surface of the engine cylinder located in the heat-insulated channel is made with fins.

Figure 1 presents the installation diagram of the heat recovery of flue gases.

FIG. 2 is a sectional view showing a heat-insulating channel of a heating furnace with an engine cylinder with external heat input, heater heat exchange tubes, and fins.

The heat recovery unit for the exhaust furnace gases consists of a heating furnace 1 with a heat-insulated working chamber 2, in which fuel burners 3 are installed. In the working chamber 2, heated workpieces 5 are placed on the loading table 4. In the roof 6 of the heating furnace 1, a heat-insulated channel 7 is made, along the inner surface 8 which exhaust furnace gases in the form of combustion products are removed from the working chamber 2 of the furnace. In the initial part of the heat-insulated channel 7 adjacent to the working chamber 2, on the inner surface 8 there is a cylinder 9 and heater heat exchange tubes 10 communicating the cylinder 9 and the engine regenerator 11 with an external heat supply. The cylinder 9 contains a piston 12, due to the movement of which the working fluid (gas) moves in the heat exchange tubes 10. To intensify the heating of the working fluid (gas), the surface of the cylinder 9 located in the heat-insulated channel 7 is made with ribbing 13 (see figure 2) .

Behind the heat exchange tubes 10 of the heater of the engine 11, a recuperator 14 is installed in the heat-insulated channel 7 to heat the air entering the fuel burners 3.

Installation of heat recovery of exhaust flue gases is as follows. The fuel is mixed with air in the burner 3 and burns in the working chamber 2, heating the steel billet 5 before forging and hot forging to 1150-1250 ° C. Exhaust furnace gases in the form of combustion products with a temperature of 1100-1200 ° C under the action of natural or artificial traction are removed from the working chamber 2 into a thermally insulated channel 7. Passing along the inner surface 8 of an insulated channel 7, the exhaust furnace gases (combustion products) heat the heat exchange pipes 10 and fins 13 of the cylinder 9 of the engine 11 and maintain a high temperature (900-1000 ° C) of the working fluid (gas) in the heat exchange tubes 10 and in the cylinder 9 of the engine. At this level of heating of the working fluid by means of a thermodynamic cycle with periodic expansion and compression of the working fluid in the cylinder 9, the engine 11 is provided with an external heat supply with effective efficiency conversion of heat into mechanical energy 30-40%, which is several times higher than efficiency steam turbine units of similar capacity. The heat removed from the working fluid in the engine cooler 11 can also be used in space heating systems and hot water supply. Engines with an external heat input from 1 to 100 kW can be used in waste heat recovery plants, while several motors 11 can be sequentially installed in the heat-insulated channel 7 to more fully recover the heat from the exhaust gases. Starting and stopping engines 11 with an external supply of heat is carried out without significant expenditures of external energy and is simply mechanized. At the output of the engine 11, the converted thermal energy can be obtained in the form of mechanical energy to drive an electric generator, pump, refrigeration unit or compressor, as well as in the form of compressed gas under high pressure.

The use of an engine 11 with an external supply of heat can be combined with the use of recuperators 14 for heating the air entering the fuel burners 3, or other heat recovery devices of the exhaust furnace gases.

Heating and thermal furnaces in engineering production are located in accordance with the location of the forging and stamping equipment at a considerable distance from each other. Compact, efficient and self-contained engines with external heat input, capable of operating in an automated mode, can provide not only a high level of heat recovery of the flue gases, but also the distribution of the received mechanical energy in the form of compressed gas, electricity or liquid under pressure from production.

The application of this technical solution is expected in heating and thermal furnaces of the forging and stamping and thermal industries of the engineering plant. The use of engines with an external supply of heat operating from flame furnaces to drive heat pumps and compressors will fully satisfy the production need for space heating, hot water supply, cold supply and compressed air and reduce the consumption of electric energy from external sources.

Claims (2)

1. Installation of heat recovery of exhaust furnace gases, comprising a heating furnace with a working chamber with fuel burners, a heat-insulated channel with heat exchange pipes, through which combustion products are removed from the working chamber of the furnace, characterized in that a cylinder with a piston is located in the initial part of the inner surface of the heat-insulated channel an engine with an external supply of heat, which is connected to heat exchange pipes to ensure the movement of the working fluid in them. 2. Installation according to claim 1, characterized in that the surface of the cylinder of the engine located in the heat-insulated channel is made with fins.

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