RU2230989C2 - Furnace for after-burning of flue gases - Google Patents

Abstract

FIELD: after-burning furnaces for burning domestic and industrial wastes.

SUBSTANCE: proposed cyclone-type after-burning furnace includes cylindrical housing, taper bottom with ash collector, cover with pipe for exhaust of combustion products and unit for delivery of flue gases into furnace which is mounted tangentially relative to cylindrical housing. Flue gas delivery unit is made in form of ejector with plasmatron mounted along its axis for ejecting flue gases by plasma jet of air-oxidizer.

EFFECT: simplified construction; intensification of after-burning process.

2 dwg

Description

The invention relates to flue gas afterburning furnaces and may find application for solving environmental problems in the combustion of domestic and industrial waste.

When waste is burnt, flue gases are formed which contain products of incomplete combustion and thermal decomposition.

In this regard, the organization of the process of afterburning of combustible gases contained in flue gases is of great importance.

The known chamber for the afterburning of exhaust (flue) gases (SU 473880 A, F 23 G 7/00, 06/14/1975) has a complex structure: the presence of gas manifolds for supplying combustible components; numerous nozzles directed radially into the afterburner; the presence of an additional fan for supplying combustion air; low efficiency of thermal decomposition of combustible substances due to low speeds and insufficient mixing of flue gases with air in the furnace.

Closest to the proposed invention in terms of features is a flue gas afterburner (US 3817712, F 23 G 7/06, 06/18/1971). It consists of a cylindrical cyclone-type afterburning chamber, a pipe for introducing flue gases and a burner for supplying fuel combustion products installed tangentially to the furnace body, a pipe for the exit of combustion products and a pipe for removing ash.

The disadvantages of this furnace are the presence of two tangential nozzles - flue gas inlet (outlet) and fuel combustion products (from the burner) and the insufficient efficiency of burning combustible components in flue gases. One of the conditions for intense combustion of gaseous substances is good mixing of combustible components with an oxidizing agent, oxygen in the air. The known design of the furnace for afterburning flue gases does not allow for high mixing. Flue gases entering the cylindrical housing tangentially meet with the combustion products of fuel coming from the nozzle, which are introduced into the cylindrical housing also tangentially and in the same direction. These two streams of gases move in a spiral, twisted in one direction. As the gases move in one direction, the velocities of the gases are leveled and thereby their mixing is impaired. At the same time, the velocity of gas flows is not large, therefore, the Reynolds number is not large, and therefore the mixing of gases is ineffective.

The present invention solves the problem of simplifying the design, the intensification of the process of afterburning of combustible components in flue gases.

To solve the stated problem in a cyclone-type furnace for burning off flue gases, containing a cylindrical body, a conical bottom with a device for collecting ash, a cover with a pipe for discharging combustion products and a device for introducing flue gases into the furnace tangentially to the cylindrical body, a device for introducing flue gases of gases is made in the form of an ejector-type mixer, along the axis of which a plasmatron is installed, ejecting flue gases with a plasma jet of air-oxidizer.

The tangential arrangement of the device for introducing flue gases to the cylindrical body of the furnace is necessary for the separation of solid non-combustible substances from flue gases. The location of the plasma torch along the axis of the mixer is necessary for using a plasma jet of air as an ejection gas.

The plasma jet of the air-oxidizer absorbs flue gases, and in the ejector there is a thermal treatment (destruction and oxidation) of the components that make up the flue gases. Due to high speeds, intense mixing of gases occurs.

The plasma torch plays the role of the working nozzle of the ejector, from which the working (ejecting) stream of a high-temperature (5000-6000 ° C) plasma jet of oxidizing air comes out. The plasma torch performs two functions: 1 - the source of thermal energy, 2 - the working nozzle of the ejector.

The flue gas afterburner is presented in figure 1 - General view and figure 2 - section aa. It consists of a cylindrical body 1, a conical bottom 2, a cover 3, a pipe for the exit of gases 4, a plasma torch 5, an ejector type mixer 6.

The furnace operates as follows: flue gases enter the ejector type mixer 6 through the nozzle 7. Air enters the plasma torch 5 through the nozzle 13, where it is heated in an electric arc to a plasma state, and the plasma stream of the air-oxidizer through the nozzle 10 enters the ejector-type mixer 6. In the confuser 12 of the mixer 6, the flue gases are pre-mixed with a plasma jet of air-oxidizing agent and carried away by it, enter the cylindrical part 11 of the mixer 6.

Due to the high speeds of the gases, they are intensively mixed and the temperatures equalized. The temperature of the gas mixture is controlled by changing the current load of the plasma torch. With a certain, predetermined temperature, the gas mixture enters the cylindrical body of the furnace 1, where the spiral flow of gases, separated from the non-combustible solid particles that are collected in the nozzle 9, enters the pipe 4. The combustion products are removed from the furnace through the nozzle 8. Destruction and afterburning flue gas begins in the mixer 6, and ends afterburning in the furnace itself.

Thus, the application of the proposed design of a flue gas afterburner provides high mixing of flue gases and a plasma jet of air-oxidizer, which leads to an intensification of the afterburning process, and also eliminates the need to supply additional air to the burner to obtain combustion products with a high temperature, as part of the air spent on burning fuel. The use of this furnace design allows the kinetic energy of the plasma jet of air-oxidizer to be used in an ejector-type mixer for suction of flue gases, and the design of the furnace itself is also simplified.

Additional positive properties of the proposed design of the furnace flue gas afterburning include:

1. The high temperature (5000-6000 ° C) of a plasma jet of air-oxidizing agent makes it possible to decompose and burn highly toxic compounds, for example, chlorine-containing hydrocarbons, etc. (The temperature of the combustion products of natural gas with air is 1875 ° C, of kerosene - 1930 ° C, of gasoline - 1970 ° C.) [A.M. Kitaev, Ya.A. Chinas. Welder reference book. M .: Engineering, 1985, p. 173].

2. All flue gas particles are forced to pass through the high-temperature zone of the plume of a plasma jet of air-oxidizer, at which the temperature is 5000-6000 ° C.

Claims (1)

A cyclone-type furnace for flue gas afterburning, comprising a cylindrical body, a conical bottom with a device for collecting ash, a cover with a pipe for discharging combustion products and a device for introducing flue gases into the furnace tangentially to the cylindrical body, characterized in that the device for introducing flue gases made in the form of an ejector-type mixer, along the axis of which a plasmatron is installed, ejecting flue gases with a plasma jet of air-oxidizer.

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