RU2244873C2 - Furnace for burning wood wastes in fluidized bed - Google Patents

Abstract

FIELD: heat-power engineering; manufacture of boilers.

SUBSTANCE: proposed furnace has gridless cap-type air distributing grate, fuel feeder, air supply system and flue dust return system, lighting-up unit and heating surfaces; located in upper portion of furnace are pipe lines for tangential delivery of secondary air. Furnace is made in form of cone; walls of furnace are made from refractory material; they are not load-bearing members. Delivery of secondary air to furnace is performed due to rarefaction; heating surfaces are mounted directly on supporting structure and are independent of furnace. Wood lighting-up device is used for lighting-up.

EFFECT: enhanced efficiency; increased heat production of boiler.

3 dwg

Description

The invention relates to the field of power engineering and can be used in boiler building.

Known furnace for burning coal in a low temperature fluidized bed (NTKS) boiler plant called "UKS-2.5" [1]. The base of the furnace is a spherical, wireless cap grill installed between the cylindrical metal walls of the boiler’s water jacket. Air (in full) for combustion and liquefaction of the fuel layer enters through the grate due to the vacuum created in the furnace by smoke exhausters. The cooling surface is a vertical flame tube and a gas-convective part. Fuel is supplied by a screw; ignition is performed by a water-cooled liquid fuel device.

The closest analogue in technical essence to the claimed object is a boiler furnace with a circulating layer [2]. The circulating layer boiler contains a shielded furnace adjacent to the gas duct, in which two traps of circulating particles are connected in series, connected by return channels with a flow regulator to the furnace.

The disadvantages of this boiler are the large volume of the furnace, associated with its increased height necessary for organizing the fuel combustion process in the circulating layer, in this regard, the lining volume is significantly increased, the boiler’s maneuverability is reduced, and large fuel consumption is required, this boiler has a significant energy consumption for its own needs, primarily due to the increased power of the blower fan and smoke exhaust, the presence of two traps of circulating particles greatly increases the dimensions of the boiler.

The objective of the invention is to improve the design of the furnace for burning wood waste in a fluidized bed (KS), the possibility of using different both in design and type of heat carrier heating surfaces, the ability to burn wood of different characteristics in the same boiler without significant loss in efficiency and heat production without additional design measures.

These tasks are solved due to the fact that the furnace consists of a wireless capless air distribution grill. The walls of the furnace in the form of a cone are lined with refractory material. In the upper part of the furnace are pipelines of the tangential supply of secondary air. In this case, the total cross section of the secondary blast piping and the cap grill is chosen so that the ratio of primary secondary air remains 0.4-0.5 / 0.6-0.5, respectively, depending on the vacuum in the furnace, and 0.4 / 0 , 6 - refers to the maximum vacuum. The angle of the walls of the furnace is selected in such a way as to reduce the speed of gases and reduce losses with entrainment.

The angle of inclination and the relative position of the mouths of the secondary blast pipelines create a tangential rotating downward direction of the flow of fuel particles along the heated walls of the furnace, which also reduces losses with entrainment of unburned fuel.

Air is supplied to the furnace and flue gas is removed due to the rarefaction created by a single exhaust fan, which increases the reliability of the boiler as a whole.

The ignition device is a pan in which firewood burns and hot gases flow through the layer into the furnace to heat and ignite the fuel. The use of firewood to ignite the boiler eliminates the need to use additional fuel and organize its storage and supply system.

The walls of the refractory material create an incendiary belt when they are heated to accelerate the drying process, release volatiles and increase the stability of combustion when the moisture content of wood waste changes. The heating surfaces are designed from the aerodynamic drag of the gas path and the need for at least one rotation of the gases in the convective part in order to organize the capture (deposition) of fuel entrainment and return it to afterburning due to ejection.

The furnace is mounted on a support frame - a single support structure, both for the walls of the furnace and for heating surfaces.

Solid particles (soil, dust, etc.) entering the furnace with fuel are either taken out of the furnace with flue gases or, during agglomeration, are removed through a drain hole in the center of the spherical grating using a screw to remove focal residues.

New features in the claimed invention are:

- the use of refractory walls of the furnace in the form of a cone with a certain opening angle in combination with a wireless capless air distribution grill;

- the use of a specially organized secondary blast;

- the use of one draft machine;

- the use of an ignition device using the main fuel of the boiler.

The proposed type and design of a low-temperature fluidized bed furnace is known as a furnace for burning solid fuel [2] and coal [1], but the authors have not identified the use of NTKS furnaces with the above new features for burning wood waste in a fluidized bed from the existing prior art. The proposed design of the secondary air supply is not identified from the existing level of technology. This allows us to conclude that the patentability criterion is “inventive step”.

The proposed design of the furnace is illustrated by drawings, where Fig. 1 shows a side view, Fig. 2 shows a section of Fig. 1 in a horizontal section AA and in Fig. 3 a section B-B of Fig. 2 in a vertical section.

The furnace contains a lattice frame (1) with a support structure under the heating surface (2), a spherical free-flowing cap lattice (3), furnace walls (4), secondary air supply system (5), an ignition device (6), an air box (7) , fuel feeder (8), focal residual removal screw (9) and ablation return system.

The ablation return system is made in the form of a rotary chamber and an ablation hopper (10) located below it with an ejector (11).

The secondary air supply system (5) includes pipelines located in the upper part of the furnace.

The walls of the furnace (4) are made of refractory material inside the supporting structure and are not bearing for heating surfaces.

The heating surfaces (2) are installed directly on the supporting structure and are independent of the furnace.

The proposed furnace works as follows.

Inert (chamotte chips, quartz sand, etc.) is poured into the furnace to a certain height. In the ignition chamber, with minimal draft of the smoke exhaust, firewood is ignited. The secondary blast, air box and ablation return nozzle are closed. When the layer is heated to 200 ° C, a portion of wood waste is fed into the furnace by the fuel feeder (8) from the feed hopper. With their steady burning, the ablation return ejector (11) and the secondary blast (12) are switched on, fuel is supplied, and the amount of primary air is regulated by the air box shutter (13). The hole of the ignition chamber for air inlet does not overlap both during ignition and during operation. When the combustion process stabilizes, the heat output of the boiler is regulated by changing the capacity of the feeder screw (8) and air damper (13).

During combustion, mineral particles agglomerate and settle on the bottom of the grate and are periodically removed by a screw (9).

The combustion products passing through the rotary chamber due to a change in the direction of movement are cleaned of fuel particles that are returned to the furnace for afterburning by the ejector (11).

The vacuum in the furnace and the removal of combustion products is carried out by a smoke exhaust (14). In a multicyclone (15), flue gases are purified from particles of ash and soot.

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

Literature

1. Design documentation of the Brest GSKB, code “UKS-2.5”.

2. Description of the invention to the copyright certificate of the USSR No. 1772523 A1, F 23 C 11/02. 1992 - 8 p.

Claims (1)

A fluidized-bed wood waste combustion chamber, consisting of a wireless capless air distribution grill, a fuel feeder, air supply and ablation return systems, an ignition device and heating surfaces, characterized in that the tangential secondary air supply pipes are located in the upper part of the furnace, the furnace is made in in the form of a cone, the walls of the furnace are made of refractory material and are not load-bearing, the secondary air is supplied to the furnace due to rarefaction, the heating surface They are mounted directly on the supporting structure and are independent of the firebox; a wood-burning ignition device is used for ignition.

Images