RU41837U1 - COMBINED BOILER FOR COAL BURNING IN A HIGH-TEMPERATURE BOILING LAYER - Google Patents

Abstract

The invention relates to the field of power engineering. A boiler unit consists of a mechanical furnace device in the form of a narrow, movable, grate inclined to the horizon, cast-iron sectional and steel welded heating surfaces, a fuel feeder, an ablation return chamber with an ejector, and secondary blast nozzles. Fuel is supplied by a plate feeder to the booster plate and further into the furnace. The pipe system is made in the form of a front, ceiling, and two rotary screens blocking the combustion chamber and providing a sharp turn of the flue gases and separation of particles to the ablation into the ablation return chamber, which are returned to the afterburner by means of an air ejector. A two-stage air supply is applied. Primary air goes under the grill, and the secondary air goes into the superlayer space. In the combustion chamber along the grate, an additional heating surface (cooling panel) is installed included in the boiler circulation circuit. The cooling panel is made of a number of pipes. flush with each other and has a U-shaped layout in plan.

Description

The invention relates to the field of heat power

Known boiler with a furnace for burning solid fuel in a fluidized bed design "Ignifluid" GC. The firebox consists of a narrow, movable grate. tilted to the horizon by 10-15 °. Air for liquefying the fuel layer is supplied through a grate from an air box, divided into sections, in each of which a predetermined pressure is maintained. The grate seals at the front and side walls of the combustion chamber are comprehended by natural slag filling, which borders the fluidized bed and protects the furnaces from overheating. A system of pipes cooled by water prevents slagging of the layer, holds backfill on each side of the grate and directs the flow of slag [2].

Known boiler unit Bratsk [3]. It is equipped with a mechanical firebox with a screwing bar. Above the firebox are steel heating surfaces in the form of flat screens and cast-iron sections of the convective beam, which gases pass in two moves. The air required for combustion is supplied through the blast channels under the grill.

This analogue has several disadvantages:

- the cyclical supply and combustion of fuel and the mixing of combustion zones, which leads to an increase in mechanical and chemical underburning, does not allow the use of

low-grade coal grades with high ash content, humidity, a large number of fine fractions;

- all air is supplied under the grate, which increases the entrainment of solid particles of fuel and slag from the furnace;

- to move using chains and rod devices, which reduces the reliability of its work;

- low reliability of steel flat bags. The objective of the invention is to improve the reliability of the design of the device, the possibility of burning low-grade coals, increasing efficiency, increasing heat production and environmental performance of the boiler.

These tasks are solved due to the fact that:

1. To burn fuel, a mechanical furnace device is used in the form of a narrow, movable grate grate inclined to the horizon, which implements the technology of burning fuel in a high-temperature fluidized bed. According to this technology, the fuel layer is blown by an intense stream of air supplied from below through the grate. In this case, the fuel particles begin to mix intensively. Due to the active mixing of coal particles, intensive washing with air, quick removal of the crust of ash from the outer surface of the pieces of fuel, it is possible to burn the combustible mass by 98-99%. This allows this boiler to work with high efficiency on low-grade coals with high ash content, humidity, low heat of combustion, a large number of small fractions.

2. In the convective beam, a rotary chamber is made, providing a sharp turn of the flue gases. This makes it possible to precipitate particles of slag and unburned fuel carried out from the furnace.

3. The air ejector transports the ablation to the furnace. This increases the efficiency of fuel burnout, transfers part of the ablation to slag and reduces emissions of particulate matter with flue gases.

4. A two-stage air supply is applied. Air is directed under the grill and into the superlayer space. The air supplied to the superlayer space forms a screen (air surface) preventing the entrainment of particles of dispersed material, which increases the efficiency of fuel combustion and reduces the loss of heat with entrainment. A decrease in the amount of O ₂ in the active combustion zone reduces NO _x emissions.

5. Fuel is supplied by a plate feeder to the accelerating plate, from where it enters the furnace under the influence of gravity. The exclusion of the screwing strap simplifies the design, increases reliability.

6. In the combustion chamber along the grate, an additional heating surface is installed, a cooling panel included in the boiler circulation circuit. The cooling panel is made of three pipes placed close to each other. Each pipe has a U-shaped layout in plan. An additional heating surface provides active control of the temperature level of the fluidized bed, prevents slagging of the grate, which ensures an increase in the efficiency of fuel combustion and an increase in heat output.

The proposed design of the boiler unit is not identified from the existing level of development of technology. This allows us to conclude that the criterion of "novelty."

The proposed design of the boiler is illustrated by drawings, where figure 1 shows a side view, and figure 2 is a front view.

The boiler includes a firebox and heating surfaces. The heating surfaces consist of a cooling panel (5), gas-tight front, ceiling, two rotary and rear steel welded screens (3), two packages of cast-iron sections (2).

The main technological element of the firebox is a narrow horizontal grate (1) inclined to the horizon. The device also includes a frame with an air box (11) located inside it, divided into blow zones (8), a grill drive, and also lateral and transverse (interzone) seals.

The device operates as follows: the fuel is fed by a plate feeder from the hopper to the accelerating plate, acquires a certain speed and enters the active combustion zones in the initial part of the grate, where it warms up and burns in suspension over the web. The resulting slag, sticking together into large agglomerates, is lowered onto the grate and removed from the boiler.

The small unburned and partially burnt particles carried out from the layer fall into the expanded part of the furnace, lose their speed and, for the most part, come back from the zone of active combustion.

Part of the air necessary for the combustion of fuel is supplied to the blast zones (8). The rest of the air enters the sharp blast system.

Flue gases exiting directly from the fluidized bed contain gaseous products of incomplete combustion and unburned solid particles of fuel. The sharp blast jets supplied from the secondary air manifolds (4) towards each other, colliding, spread over the grate, burn the gases and prevent the particles from being removed from the active combustion zone.

In order to reduce heat loss with mechanical underburning and to reduce solid emissions, an ablation recovery system is used. For this, the boiler is equipped with a special rotary chamber (9) and an ablation deposition chamber (10) located below it. Due to a sharp turn and a decrease in the speed of the flue gases, a significant amount of coarse ablation particles is separated before the flue gases enter the cast iron sections. The entrainment deposited in the chamber is directed by the ablation return ejector (6) to the active combustion zone, where the unburned entrainment carbon is burned, and most of the fly ash is transferred to slag.

The above allows us to conclude that the criterion of "industrial use".

1. A.P. Baskakov and others. Boilers and furnaces with a fluidized bed. M .: Energoatomizdat, 1995, p. 260.

2. AP Baskakov and others. Boilers and furnaces with a fluidized bed. M .: Energoatomizdat, 1995, p. 263.

3. V.V.Somov. Boiler installations. S. - St. Petersburg: VISI, 1995, pp. 182-184,280-282.

Claims (1)

Coal fired boiler unit, consisting of a mechanical furnace device, heating surfaces, fuel feeder, characterized in that the furnace device is made in the form of a narrow, movable, inclined grate grate for burning fuel in a high-temperature fluidized bed, the heating surfaces are combined of cast-iron sectional panels and steel pipes, the pipe system is made in the form of gas-tight front, ceiling and rear screens enclosing the furnace volume, and two rotary screens, ne that simulate a combustion chamber for turning gases in a vertical plane, an ablation return hopper with an ejector is installed behind the combustion chamber, fuel is supplied gravitationally using a mechanical feeder, air is supplied under the grate through the primary air blast zones and into the superlayer space through secondary blast nozzles, a cooling panel is installed in the combustion chamber along the grating web in the form of a pipe heating surface included in the boiler circulation circuit.