RU2334166C2 - Method of double-stage fuel burning and device for its implementation - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: method of double-stage fuel burning includes the first stage of solid fuel burning that provides gas generation and the second stage of generated gas burning. By loading fuel through loading hatch, which is equipped with device for sector loading, cone is shaped from supplied fuel, the centre of which is displaced relative to the centre of combustion chamber base, which provides separation of combustion chamber into two burning zones and combination of dense high temperature flame, which is created in the process of fuel layer burning at the cone base, with gases that are created in the process of fuel burning in the whole height of cone, and burning process intensification is carried out by bore piercing of the whole solid fuel burning zone with the help of vertical rods that are lowered from the top part of boiler plant, and forced air supply into cindery part of furnace.

EFFECT: invention allows to create environmentally safe smoke-free method of solid fuel burning with high coefficient of heat generation and heat emission with the help of boiler plant of double-stage type.

2 cl, 1 dwg

Description

The invention relates to the field of heat engineering and can be used in boiler plants.

Currently, for the foreseeable future, the main source of primary energy for boiler plants of industrial enterprises and social facilities is solid fossil fuels. One of the urgent modern tasks is to ensure the cleanliness of the air basin, and therefore, the creation of such methods and devices for burning fuel that would ensure, at high efficiency, the purification of the combustion products of the fuel released into the atmosphere from solid particles of ash, unburned fuel and harmful gaseous products of combustion.

A known method and device for burning solid fuel in a dense layer (Sidelkovsky LN, Yurenev VN "Boiler plants of industrial enterprises" p.11). With this method, fresh fuel is located in the upper part of the layer after loading, burning coke is located under it, and slag is directly above the grate; as it burns out, the fuel passes through all zones. Air is supplied from below through the grill. The slag formed during fuel combustion flows through the grate into the ash removal zone. Dense-bed combustion furnaces can be non-mechanical, semi-mechanical and mechanized. With all the variety of designs, they all contain: a spreader, a fuel combustion chamber with a grate, a device for forced air supply to the combustion zone and a chamber with a coolant.

The disadvantage of this method is the insufficiently high efficiency, incomplete combustion of the fuel and the emission of harmful gaseous and solid residues into the atmosphere.

There is also a known method and device for burning solid fuel in a fluidized bed (Sidelkovsky LN, Yurenev VN "Boiler plants of industrial enterprises", p. 111).

A characteristic distinguishing feature of fluidized bed furnaces is a two-stage scheme for organizing the combustion process. The fluidized bed is used as the first stage of the furnace, where intensive and deep thermal preparation of the fuel is carried out: heating, drying, and the release of high-temperature combustible gases. The second stage of the furnace is the afterburning chamber of the combustible gas emitted by the fluidized bed and the particles of thermally prepared entrainment contained therein. The temperature of the fluidized bed is maintained at a level that excludes melting of the ash, in order to avoid slagging of the layer.

One of the options for a fluidized bed firebox is a single-chamber fluidized bed firebox with a hot water boiler. The second stage of the furnace is located directly above the fluidized bed. Such a furnace in production conditions can work on coke breeze and brown coals. The size of the fuel is 0-20 mm. When working on coke breeze, about a third of the air necessary for complete combustion of fuel is supplied under the grate. The remaining air is supplied to the combustion chamber above the fluidized bed through two rows of tuyeres. The necessary cooling of the fluidized bed of fuel for the implementation of a non-slag mode (t = 1000 ° C) is achieved by water-cooled surfaces located in the fluidized bed included in the boiler circulation system. Water is also injected directly into the fluidized bed so that its temperature can be controlled if necessary. Maintaining the desired ash content of the layer, excluding its extinction and providing small losses from mechanical underburning with a cesspool, is carried out by continuous or periodic “blowing” of the layer through the cesspool device. The height of the layer in the state of boiling is maintained at a level of 600-800 mm. The required air pressure under the grille is 3400-3900 Pa.

The disadvantages of this method and device are the design complexity, the need for constant monitoring and adjustment of the combustion process, the complexity of process control, the need for a constant air supply with a pressure of 3400-3900 Pa, fuel size limitation (no more than 20 mm).

The object of the present invention is to provide an environmentally friendly smokeless method of burning solid fuel (eg coal) of any size and humidity with a high coefficient of heat generation and heat transfer using a two-stage boiler plant. The boiler plant of the proposed type is simple structurally and in manufacture. The technological process of burning fuel according to the proposed method does not require constant complex control, changing the output parameters of the boiler installation is achieved by a simple set of simple operations.

The method of two-stage burning of solid fuel, including the first stage of combustion, which provides gas generation, and the second stage of afterburning of the formed gas, is characterized in that the fuel is burned in the first and second stage in a cylindrical chamber with a height of at least 3 meters, with a loading hatch located at a height of 2 meter and equipped with a device providing sector loading of fuel, while the center of the cone formed by the filled fuel is offset from the center of the base of the combustion chamber, which ensures dividing the combustion chamber into two combustion zones and combining the dense high-temperature flame formed during the combustion of the fuel layer at the base of the cone with the gases generated during the combustion of the fuel along the entire height of the cone, while the combustion process is intensified by forced borehole flashing of the entire combustion zone of the solid fuel using vertical pins lowered from the upper part of the boiler plant and forced air supply to the ash part of the furnace.

The application of this method and device allows: to ensure the operation of the boiler plant for a long period (up to 2 days) without additional load, while the system does not require complex control, in addition, depending on the required load, the specific volume of fuel combustion is easily regulated with systems for adjusting the gasification process and the volume of air supply to the combustion zone. The advantage of this method and device is also that their application allows the purification of the combustion products of the fuel emitted into the atmosphere from solid particles of ash, unburned fuel and harmful gaseous combustion products at a high efficiency of the boiler plant.

The proposed method is carried out using a boiler installation, shown in the drawing and consisting of the following structural elements:

- a combustion chamber 1 with two combustion zones, providing two-stage combustion of fuel;

- fan 2 for forced air supply to the combustion zone of the combustion chamber 1;

- systems for adjusting the combustion process 3, including vertical pins for downhole firmware of the combustion zone;

- fluid carrier 4 with a convective surface in contact with the combustion chamber 1;

- coolant chambers 5;

- heat accumulator 6;

- gate-conveyor system for removing ash 7;

- pump systems 8;

- loading hatch 9;

- device 10, providing sector loading of fuel.

The method using the proposed device is as follows:

The heating system is filled with coolant. The furnace of the boiler is ignited through the slide-conveyor ash removal system 7. The boiler is ignited once and extinguished during operation. The combustion chamber 1 is loaded through the loading hatch 9, equipped with a device 10, providing sector loading of fuel. In this case, the loaded fuel forms a cone, the center of which is offset from the center of the base of the combustion chamber 1, as a result of which two combustion zones are created in the furnace chamber 1 - the fuel combustion zone at the base of the cone, which forms a high-altitude fire column, and the combustion zone of the fuel cone, forming a smoke and gas mixture . The combination of the mixture with the column of fire provides complete combustion of the combustion products of solid fuels. The combustion of fuel in the combustion chamber 1 is ensured and regulated by forced air supply by the fan 2. During the combustion process, a high layer of porous ash fraction is formed, which provides the filtering effect of the generated gases and combustion products. Ash passes air, which makes it possible for the fuel to work for a long time (up to 2 days) without removing ash from the boiler. Additionally, periodic ash flashing of the ash layer is carried out with pins 3. The ash is removed in a cooled mode without stopping the heating system by means of a slide-conveyor ash removal system 7. The heat transfer of the vertical heating boiler is ensured by the heat carrier chamber 4 with a convective surface in contact with the furnace chamber 1, and the chamber coolant 5. When the coolant is heated to a predetermined temperature, the pump system 8 is turned on. The coolant from the heat accumulator 6 is supplied to the chambers 4 and 5 and returns to the battery. From the heat accumulator 6, the coolant is supplied to the consumer via locally independent systems. The heating system can operate in three modes:

1. Intensive mode with the highest possible rise in heat generation.

2. The mode of reduced loads.

3. Standby mode.

The proposed method and device for burning fuel in a boiler plant can be used in heating systems, energy systems and locally for heating buildings of various sizes and purposes. The invention provides an environmentally friendly two-stage combustion of coal fuel of any brand, size and moisture, including sludge.

Claims (2)

1. A method of two-stage combustion of fuel, comprising a first stage of burning solid fuel, which provides gas generation, and a second stage of burning of the formed gas, characterized in that by loading fuel through a loading hatch equipped with a sector loading device, a cone of filled fuel is formed, the center of which is offset relative to the center of the base of the combustion chamber, which ensures the separation of the combustion chamber into two combustion zones and the combination of a dense high-temperature flame formed in the process combustion of the fuel layer at the base of the cone with gases generated during the combustion of the fuel along the entire height of the cone, and the combustion process is intensified by borehole flashing of the entire combustion zone of solid fuel with the help of vertical pins lowered from the top of the boiler plant and forced air supply to the ash part of the furnace. 2. A boiler installation, including a combustion chamber, a loading door, a fan for forced air supply to the combustion zone, a chamber with a coolant, characterized in that the cylindrical combustion chamber has a height of at least 3 m, and the loading door is located at a height of 2 m and is equipped with a device providing sector loading of fuel, in addition, the boiler plant is equipped with pins for downhole firmware of the combustion zone.