RU2496885C1 - Heat treatment furnace - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: proposed furnace comprises screw mechanism to transfer articles to be heated. Said mechanism comprises cylindrical housing to accommodate said screw. Jet flare heater divided into continuous and fire section is arranged aligned with said screw mechanism. Sealed continuous section abuts on article loading zone and comprises isolated cylindrical casing and perforate flame tube aligned therewith. Said fire section abuts on article discharge zone. Sire section casing end incorporates gas flow feed system arranged parallel with screw mechanism housing walls and air flow feed system arranged perpendicular to said walls. Note here that continuous and fire sections are communicated via channel for feeding combustion products from fire section to continuous section.

EFFECT: higher efficiency, increased temperature drop at higher combustion product jet velocities, higher available fuel factor, reduced carbon oxide emissions.

Description

The invention relates to heat engineering and can be used in various industries, for example, metallurgy, mechanical engineering, the building materials industry when heating small mechanical engineering products for hardening, normalization, tempering and cementation.

Known furnace for heat treatment of products (JP 2007192471, publ. 11.09.2001), which contains a screw device for moving heated products inside a rotary horizontal furnace.

The disadvantages of this device include low heat flux density to the heated material and, associated with this, low fuel utilization.

A prototype of the proposed invention is a furnace for heat treatment of products (RU 2251579, publ. 05/10/2005), which provides for air-flare heating of products using a gas-air mixture, while the flares are perpendicular to the surface of the products.

The disadvantages of this device include: a significant decrease in the density of the heat flux at the outlet of the working chamber due to dilution of the combustion products coming from the combustion zone with air jets that attack the heated surface and reduce the temperature head; as well as significant heat losses with flue gases due to dilution with excess air and the possibility of unreacted carbon monoxide in cold jets during transient “freezing” conditions.

In the proposed invention, a technical result is achieved, which consists in increasing energy efficiency by significantly reducing the supply of excess air to the method zone, increasing the temperature head at high speeds of the jets of combustion products flowing onto the heated surface of the furnace method zone, and significantly increasing the fuel utilization rate due to the increased heat transfer in the methodical zone at low air excess factors, as well as a significant reduction in oxide emissions carbon, the dying in the buffer zone methodology section. In addition, it is possible to intensively heat products in the firing section by ensuring uniform heating of the products to a plastic state when they are mixed with a screw mechanism in the methodical section.

The specified technical result is achieved as follows.

The furnace for heat treatment of products contains a screw mechanism for transporting heated products, including a cylindrical body with a screw located in it. Coaxial to the screw mechanism, a jet-torch heating device is installed, divided by the methodical and fire sections.

The sealed methodical section adjoins the product loading zone and contains an insulated cylindrical body and a perforated heat pipe mounted coaxially to it.

The fire section is adjacent to the zone of unloading products. At the end of the cylindrical body of the fire section, a gas flow supply system is installed parallel to the walls of the screw mechanism housing and an air flow supply system perpendicular to the walls of the screw mechanism housing.

The cases of the methodical and fire sections are connected by a channel for supplying combustion products from the fire section to the methodical section.

The invention is illustrated by the drawing, which schematically shows the design of the furnace for heat treatment of products according to the proposed invention.

The drawing shows a screw mechanism, including a cylindrical body 1 and a screw 2, a methodical section 3, a product loading zone 4, a fire section 5, a product unloading zone 6, a gas flow supply system 7, an air flow supply system 8, a small torch system 9, a channel 10 supply of combustion products, the housing 11 of section 3, a perforated flame tube 12, streams 13 of hot combustion products.

The operation of the furnace for heating products is as follows.

Through zone 4, heated products are loaded into the screw mechanism and, with the help of screw 2, are transported along the housing 1.

In the firing section 5, the gas flow supplied from the annular collector of system 7 and moving parallel to the surface of the housing of the screw mechanism, when interacting with the air jets, the air flow supplied by system 8 perpendicular to the surface of the housing 1, form a system of 9 small flares with the effect of surface combustion on the housing 1 The used heating system has a high coefficient of heat transfer to the heated surface. At the same time, the heat of the spent combustion products is effectively used in the methodological section, significantly increasing the fuel utilization rate. The use of a screw mechanism makes it possible to efficiently use the furnace for both heating and heat treatment, including chemical-thermal treatment, for example, when a solid carburetor, uniformly mixed with a screw mechanism, is fed along with the products. Exhaust flue gases from the firing section 5 through the channel 10 enter the space formed in the methodical section 3 by an insulated cylindrical body 11 and a perforated flame tube 12.

Through the openings of the pipe 12, hot flue gases are sent at high speed to the surface of the screw mechanism. Thus, a significant increase in heat transfer from flue gases to the heated surface of the screw mechanism and an increase in fuel utilization due to the efficient use of flue gases in the methodical section with an excess air coefficient of about one are achieved.

A screw furnace with a methodical section is a highly efficient thermal unit and allows for non-oxidative heating and chemical-thermal treatment of products using various media. The use of jet-flare heating with the effect of surface combustion in the fire section and subsequent jet heating with combustion products in the methodical section can significantly increase the fuel utilization rate, reducing heat emissions. Multi-stage combustion of fuel by multi-jet air supply in the firing section significantly reduces the concentration of nitrogen oxides in flue gases, and the combustion of carbon monoxide in the buffer zone of the method section leads to its almost zero concentration in the combustion products, which leads to a significant reduction in harmful emissions.

Claims (1)

A furnace for heat treatment of products, containing a screw mechanism for transporting heated small products, including a cylindrical body with a screw located in it, and a jet-torch heating device installed coaxially to the screw mechanism, divided into a sealed methodical section adjacent to the product loading zone and containing an insulated cylindrical body with a perforated flame tube installed coaxially to it, and a firing section adjacent to the product discharge zone, while At the end of the fire section housing, a gas flow supply system is installed parallel to the walls of the screw mechanism housing and an air flow supply system perpendicular to the walls of the screw mechanism housing, the methodical and fire sections being communicated by a channel for supplying combustion products from the fire section to the methodical section.