RU2231714C2 - Furnace for burning solid fuel in fluidized bed - Google Patents

Abstract

FIELD: heat-power engineering; manufacture of boilers.

SUBSTANCE: proposed furnace includes narrow movable fire grate which has side seal and is inclined towards level. Fire gate is provided with sectionalized blast duct arranged inside it. Cooling surface is located on both sides along and above upper portion of fire grate. Fire grate may perform reverse stroke from back to front portion of furnace. Inclination ensures location of upper point of fire grate at front portion and lower point at back portion of furnace. Tractive effort is transmitted from sprockets of drive shaft to drive fire bars of fire grate moving in guide slides. Side seals of fire grate are made from separate plates mounted in between fire grate and jaw of frame. Cooling surface of fire grate is made in form of panel consisting of row of tubes tightly located one above another; axis of each upper tube is shifted relative to axis of lower tube in direction of side walls of furnace.

EFFECT: enhanced efficiency of burning solid fuel; increased heat production.

2 dwg

Description

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

Known fire chamber of a high-temperature fluidized bed (VTKS) under the name "Ignifluid" [1]. The hearth of the furnace is a narrow, movable forward chain lattice inclined to the horizon by 10-15 °. The web is moved along the guide rollers. Air for combustion and liquefaction of 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 sealing of the grate at the front and side walls is achieved by natural slag filling. A cooling surface is installed on the sides of the grill, one square tube on each side of the grill, cooled by water. Caught ablation returns to the furnace from the back wall of the furnace into the superlayer space.

The closest analogue is the TNU-0.31 / 5.6 furnace [2], installed under the DKVR and KE boilers. The hearth of the furnace is a movable, narrow, chain forward-lattice inclined 10 ° to the horizon. Along the edges of the web are steel drive chains with rollers engaged with sprockets. On the sides of the web labyrinth seals are installed. Air for combustion and liquefaction of the fuel layer is fed through the grill from the air box, divided into six blow zones. The return of ablation is carried out on both sides of the boiler in the region of the active zone above the layer, to natural slopes on the sides of the furnace. Along the grate, cooling surfaces are installed on both sides of two pipes with a diameter of 108 mm placed vertically. Water for cooling enters them from the water supply.

This analogue has several disadvantages:

- the use of a chain drive of the grill reduces the reliability of the grill, complicates the design of the side seals and reduces their effectiveness;

- the use of support rollers to move the canvas grate structure complicates the design, reduces the reliability of the lattice;

- the design of the cooling surfaces and their small area determine the decrease in the reliability of the boiler due to slagging;

- the forward-flow grill causes difficulties with the distribution of fuel along the length of the grill. The supply of fuel of different particle size distributions to one area of the grill with a highly accelerated blast increases the percentage of fines removal and reduces the efficiency of coal burning, determines the presence of a heat-stressed zone at the front of the boiler, from the service side, which creates unfavorable conditions for the fuel supply system to work, and complicates visual control and process control burning, reduces the comfort of the staff;

- the inability to organize the return of ablation by a short, straight section of the ash pipe directly to the active zone of the fluidized bed, the implementation of the return of ablation to the superlayer space and to natural side slopes reduces the burnout efficiency due to the possibility of its secondary ablation, excludes part of it from the process of controlling the temperature level in the layer.

The objective of the invention is to increase the efficiency of burning solid fuel, increase heat production, reliability, simplify the design of the combustion device.

These tasks are solved due to the fact that

the furnace consists of a narrow, movable grate with side seals, located inside the grate of a sectioned blast box and located on both sides along the upper branch of the grate of the cooling surface of the grate.

The grate has a reverse stroke in relation to the casting of fuel, i.e., the upper branch of the web moves to the front of the furnace, where the fuel supply system is installed. In this case, the inclination to the horizon is made in such a way that the upper point of the web is located at the front of the furnace, and the lower one is at the back wall of the furnace. Using a flyback grill increases combustion efficiency due to a more even distribution of fuel along the length of the grill; the coarse fraction flies further, the fine fraction, depending on size, falls earlier. The initial preparation of fuel for combustion occurs due to its passage through the entire active zone of the combustion chamber. Ease of operation is improved (the driver monitors fuel supply, combustion and slag from one service point). The entrainment of the fine fraction is reduced; this fraction enters the blast zones with a relatively low gas velocity, sufficient for liquefaction, but insufficient for entrainment, which increases the efficiency of fuel burnup. The return of hot ablation is carried out in a short way from the ablation return system to the active combustion zone by a direct section of the ash pipe. The feed return of ablation in the active zone of the fluidized bed allows you to further control the temperature in the layer, while ensuring effective burnout of unburned fuel particles. The most active heat-stressed combustion zone is located at the opposite end of the furnace from the fuel injection site, which creates favorable conditions for the operation of the fuel supply system, reduces the possibility of burning metal heat and coal ignition on it, which increases reliability and reduces the likelihood of fuel ignition in the fuel tank.

The movable grate is drawn from TLZM grates of two types, while the two drive sprockets used in the drive system of the grate are directly engaged with the drive grates, the traction is transmitted directly from the drive shaft sprockets to the drive grates of the grating web, which pull the driven ones grate. The lattice without the use of traction chains improves reliability and simplifies the design.

The movement of the grate blade web is carried out along the reference runners. Support runners are made of metal strip and are located under the upper and lower branches of the lattice for its entire length. The use of support skids simplifies the design and increases reliability.

The side seals of the grill are recruited from separate plates mounted on the edges of the grate web on the cheeks of the frame, and are attached to the latter using bolted connections with the possibility of adjusting the gap between the seals and the extreme grates of the grate. This increases the efficiency of the seal, reduces air leakage and reduces the spillage of the layer material into the blast zones due to the absence of channels for the traction chains, which increases the efficiency of combustion, increases reliability and simplifies the design.

The grate cooling panel is made of a series of pipes placed closely one above the other, and the axis of each overlying pipe is offset relative to the axis of the lower adjacent pipe in the direction of the side walls of the furnace. Each pipe has a U-shaped layout in plan, i.e. pipes of the cooling panel run along one side of the grate, unfold at the back wall of the furnace and go in the opposite direction along the opposite side of the grate. The more developed heating surface of the cooling panel provides active control of the temperature level of the fluidized bed, prevents melting of ash, slagging of the grate, which ensures an increase in the efficiency of fuel combustion and an increase in heat output. Also, the above-mentioned panel configuration eliminates the contact of hot particles with the walls of the furnace within the layer, which prevents the slag bridges from being thrown over the grate. This provides a higher reliability of the furnace.

New features in the claimed invention are the following:

- the use of a return grid;

- the moving grate is made in such a way that the drive sprockets are in direct engagement with the leading grate;

- moving the canvas grate is carried out on the supporting guide runners;

- the side seals of the grill are made of separate plates installed between the grate and the cheek of the frame;

- the cooling panel of the grate is made of a number of pipes placed one above the other, closely, and the axis of each overlying pipe is offset relative to the axis of the lower adjacent pipe in the direction of the side walls of the furnace.

The proposed type and design of a backstop lattice are known as mechanical layered furnaces for burning solid fuel [3], but the authors have not found the use of reverse furnaces with the above new features for burning solid fuel in a fluidized bed from the existing prior art. The proposed type and design of the lattice cooling panel is not identified from the existing level of technology. This allows us to conclude that the patentability criterion is “inventive step”.

The proposed furnace is illustrated by drawings, where in Fig.1 shows a side view; figure 2 shows a section of figure 1 in a vertical section aa.

The furnace contains a grate frame 1 with a narrow, movable, inclined grate grate 2 installed on it, a drive shaft 3 with an asterisk 4, a driven shaft 5 and a tension device 6. A partitioned primary air duct with air flow control valves 8 and a removal system is allocated inside the grate frame failures 9 with gates 10. On the cheeks of frame 1, lateral gasket plates 11 are installed at the edges of the grate web 11. Under both branches of the grate there are upper 12 and lower 13 supporting runners. A cooling panel 14 is installed along the grate.

The proposed furnace works as follows.

Fuel is supplied to the furnace using the fuel supply system and burned in the space above the grate 2 in a fluidized bed, bounded below by a grate grate 2 and a cooling panel 14 on the sides. A cooling panel 14 installed along the grate sheet 2 with developed heating surfaces, included in the water circuit of the boiler, provides active control of the temperature level of the fluidized bed, prevents melting of ash and slagging of the grate. Also, the aforementioned panel configuration eliminates the contact of hot particles with unshielded walls of the furnace, which prevents the slag bridges from being thrown over the grate. The movement of the lattice web occurs along the upper 12 and lower 13 supporting runners to the front wall of the furnace, with the two gears 4 of the shaft 3 being directly engaged with the leading grid-irons that pull the driven grid-irons. The tension of the grate web is carried out by moving the driven shaft 5 with the help of the tensioning device 6. On the side cheeks of the frame 1 side seals 11 are installed, which prevent the fines from spilling fuel and slag into the blast box. The gap between the extreme grates of the grate and the side seals 11 is adjusted using the adjusting bolts. Combustion and liquefaction air is supplied through a grill 2 from a sectioned duct of primary air with blast zones. The air supply is regulated by gates 8 depending on the load for each blast zone separately. Due to the small width of the grate, air is supplied at a speed that ensures fluidization of the bed. Tilting the grate to the rear wall of the boiler prevents the fluidized bed from flowing into the slag discharge zone. The hole is removed from the blast zones by air by opening the gates 11 on the system for removing the hole 10.

In the process of burning, the slag particles of fuel and entrainment are agglomerated, fall on the grate 2 and are carried out to the front of the boiler, in the zone of discharge of slag.

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

Sources of information

1. Baskakov A.P. etc. Boilers and fluidized-bed furnaces. M .: Energo-atomizdat, 1995, p. 260.

2. Baskakov A.P. etc. Boilers and fluidized-bed furnaces. M .: Energo-atomizdat, 1995, p. 263.

3. Somov. V.V. Boiler installations. S.Pb .: VISI, 1995, p. 180.

Claims (1)

A fluidized-bed solid fuel combustion chamber, consisting of a narrow, movable grate with side seals, inclined to the horizontal, located inside a sectional blast box grate and located on both sides along and above the upper branch of the grating web of the cooling surface, characterized in that the grill has a reverse stroke and moves from the back to the front of the furnace, with the top point of the web located at the front and the bottom at the back of the furnace, traction is transmitted to directly from the drive shaft sprockets to the leading grates of the grate sheet, the grate sheet is moved along the support guide rails, the side seals of the grate are made of separate plates installed between the grate sheet and the frame cheeks, the cooling surface of the grate is made in the form of a panel of a number of pipes placed close to each other, and the axis of each pipe is offset relative to the axis of the lower pipe adjacent to it in the direction of the side walls of the furnace.

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