RU2349833C2 - Method of solid fuel burning - Google Patents

Abstract

FIELD: power production; heating.

SUBSTANCE: method of solid fuel burning includes air supply to the fuel burning zone, burning itself and discharge of small fuel fractions and slug through the furnace bar slots. Air is supplied through the channel arranged under furnace bar. The fractions are discharged into the above channel, retained there and, finally, removed. At the same time, the furnace bar slots are cleaned from slug. For this purpose, channel walls are systematically opened. The furnace bar is represented with a balancing element and coupled with tray with slots. Each slot is in the same plane as the corresponding slot of the furnace bar. The furnace bar slots are cleaned with comb teeth. One wall of the channel is formed from the tray and comb teeth inserted into the tray slots, while the other channel wall is formed by the comb. When channel is opened, air supply is terminated. The comb teeth are not equal by height with regard to the tray surface. The channel walls are heat insulated.

EFFECT: intensified burning of fuel, reduced discharge of harmful wastes, simple design of furnace and increased efficiency factor, improved operational conditions.

8 cl, 5 dwg

Description

The invention relates to a power system and can be used for burning solid fuel.

A known method of burning solid fuel by feeding it with a screw through a retort into the burning layer of the combustion chamber, followed by afterburning on slowly rotating drums and removing slag [1].

The disadvantages of this method are:

- incomplete combustion of fuel, due to the fact that large pieces of fuel that have already partially burnt onto the drum and do not have time to completely burn out before falling into the slag collector. If you try to rotate the drum more slowly, these pieces will be filled with slag from the small-sized fuel that has passed through the retort and has already burned. Moreover, since the pieces of fuel falling on the drum are scattered and are removed from the high-temperature combustion zone during its rotation, the burning intensity decreases, which does not allow them to burn completely. If to intensify the burning of pieces on the drum, place the latter closer to the high-temperature zone, then the slag removed subsequently will have a high temperature, which will lead to an increase in heat loss and, ultimately, to a decrease in the efficiency of the furnace;

- a device that implements this method requires significant energy costs for driving screws and drums, which also reduces the overall efficiency of the installation.

The prototype is a method of burning solid fuels, including the supply of fuel to the combustion zone, its ignition and combustion while crushing large pieces, removing small fractions of slag through the grate slit, which is periodically expanded to remove larger fractions from the combustion zone [2].

The disadvantages of this method are:

- incomplete combustion of fuel, due to the fact that its pieces, commensurate with the size of the slit of the grate, fall together with the slag into the dump. If the gap is made very small, the resulting slag will be poorly removed from the combustion zone and prevent the latter;

- crushing pieces of fuel involves additional energy costs, which reduces the efficiency of the installation;

- instability of the combustion process over time (especially when small amounts of fuel are burned) due to a partial or complete cessation of combustion when the remaining portion of the previous portion is filled with fresh fuel.

The objective of the invention is to remedy these disadvantages, namely increasing the completeness of fuel combustion, reducing harmful emissions, simplifying the design of the furnace and increasing its efficiency and improving operating conditions.

The problem is solved in that in the method of burning solid fuel, which includes supplying air to the fuel combustion zone, burning the latter, outputting small fractions of fuel and slag through the grate slit, air is supplied through a channel that is formed under the grate, while fractions are removed into the obtained channel , where they are detained, and then removed and at the same time the slots of the grate are cleaned of slag, for which the channel walls are periodically opened.

The grate is swinging and at the same time with a pallet having slots, each of which lies in the same plane with the corresponding grate slit. The grate slots are cleaned with comb teeth. One channel wall is formed from a pallet and comb teeth inserted into its slots. The other channel wall is formed from a comb. When opening the channel, the air supply to it is stopped. The teeth of the comb are made unequal in height relative to the surface of the pallet. The walls of the channel are thermally insulating.

The invention is reflected in the operations:

- air is supplied through the channel, which is formed under the grate, while fractions are taken out to the obtained channel, where they are delayed, and then the grate slots are removed and simultaneously cleaned of slag, for which the channel walls are periodically opened;

- the grate is swinging and at the same time with a pallet having gaps, each of which lies in the same plane with the corresponding grate gap;

- grate slots are cleaned with comb teeth;

- one channel wall is formed from a tray and comb teeth inserted into its slots, and the other channel wall is formed from a comb;

- when opening the channel, the air supply to it is stopped;

- the teeth of the comb are made unequal in height relative to the surface of the pallet;

- the walls of the channel perform heat insulating.

These operations allow you to achieve the following advantages compared with the prototype.

The implementation of the air supply through the channel, which is formed under the grate, while fractions are taken out to the obtained channel, where they are detained, and then the slots of the grate are removed and simultaneously cleaned of slag, for which the channel walls are periodically opened, which makes it possible to improve the fuel combustion process. If there is an air channel under the grate, it becomes possible to individually control the air supply to the fuel lying on each grate of the furnace. As the fuel burns out, the air supply should be reduced. To control and regulate the process in the furnace, two differential traction meters can be installed. One (furnace draft) will show the resistance of the grate with a layer of fuel, the other (boiler draft) will show the resistance of the flues. With a burnout or too thin layer of fuel, the resistance of the grate slots for air passage and the readings of the furnace draft meter decrease, and the readings of the boiler draft meter, on the contrary, increase due to an increase in the amount of flue gases. This may be a signal to reduce the air supply under the grate, i.e. maintain the coefficient of excess air at the desired value, helping to increase the efficiency of the combustion process.

During the operation of the furnace with conventional grates, part of the unburned fuel is irretrievably lost, both due to failures through the grate slots and due to incomplete combustion of some pieces due to insufficient air supply to them. In the claimed solution, the withdrawal of small fractions of fuel and slag through the slit of the grate into the air channel allows them to be placed near the heated surface of the grate. Receiving radiation from the grate and oxygen from the air passing through the channel, the pieces are burned, and the heat from them and from the slag that has fallen through the slots passes to the air entering the bulk of the fuel, which favorably affects the combustion process. In addition, the products of combustion of the pieces are mixed into this air equivalent to the recirculation of the flue gases into the path of the blast air, which helps to reduce the formation of nitrogen oxides. Moreover, this mixing is free from the disadvantages inherent in recirculation and associated with the presence of a recirculation fan, flues and increase the resistance of the air path. Thus, the capture of small fractions in the air channel makes it possible to more fully use their energy, both chemical and thermal, as well as reduce the formation of nitrogen oxides during fuel combustion on the grate.

The execution of the grate swinging and at the same time with the tray having slots, each of which lies in the same plane with the corresponding grate of the grate, allows you to easily clean it and the tray of slag and fouling, as well as cut the slag from below through the slots of the pallet, which improves operating conditions.

Cleaning the slots of the grate with the teeth of the comb is much faster, so that the furnace does not have time to cool down much, contributing to an increase in the efficiency of the furnace process.

The formation of one channel wall from the pallet and the comb teeth inserted into its slots, and the other from the comb imposes several functional loads on these parts, which reduces the overall dimensions and simplifies the design.

The cessation of air supply to the channel when it is opened prevents the breakthrough of cold air into the furnace, increasing its efficiency.

The implementation of the teeth of the comb unequal in height relative to the surface of the pallet helps to retain small fractions of fuel and slag on the surface of the channel, preventing them from getting carried away by the air flow and accumulate to the end of the channel. This increases the contact surface of these fractions and air, and therefore improves heat transfer to the air supplied to the grate, and at the same time intensifies the combustion of fuel fractions. In addition, the teeth of unequal height form a kind of lattice on which the fuel fractions rise above the surface of the pallet and are washed by air from all sides, as a result of which the contact surface increases even more, which also leads to an increase in the efficiency of the combustion process.

The implementation of the walls of the air channel heat-insulating allows you to better retain heat inside the channel, improving heat transfer to the air and intensifying the combustion of fuel fractions due to an increase in temperature in the channel.

The invention is illustrated by drawings.

Figure 1 shows a device for burning solid fuel.

Figure 2 shows a section aa device for burning solid fuel.

Figure 3 shows the grate of the device.

Figure 4 shows a fragment of the strapping frame, on which the grate is hung.

Figure 5 shows a device for burning solid fuel at the time of cleaning from slag and cinder.

A device for burning solid fuel contains grates 1 with pallets 2 mounted rotatably along with axis 3 in grooves 4 of the strapping frame 5 having cross members 6 made in the form of combs with teeth 7 mating with slots 8 of pallets and 9 grates (FIG. 1, 3, 4). The teeth 7 may be unequal in height relative to the pallet 2 (figure 2). The tray with teeth and comb form an air channel 10, which is combined with the hole 11 (air supply) of the strapping frame. Small fractions 12 of fuel and slag lie on the pallet of the grate, on which the bulk of the fuel 13 burns.

The device operates as follows.

To burn solid fuel 13 on the grate 1, a channel 10 for supplying air is formed under it, one wall of which is formed from the pan 2 and the teeth 7 inserted into its slots, and the other wall from the comb 6 (Fig. 1). In this case, the grate with fuel 13 occupies a horizontal position, and the pallet closes with the comb. After that, fuel is thrown onto the grate and air is supplied through the channel for its combustion.

Small fractions 12 of unburned (unburned) fuel and slag formed in the furnace process are discharged into channel 10 and detained there for afterburning, heating the air, and mixing their combustion products with it.

If it is necessary to clean the slots 9 of the grate and the pallet, the air supply to the channel 10 is stopped and its walls are opened, for which the grate is turned with a drive lever (not shown) counterclockwise. When the grate is rotated at the same time as the axis 3 in the grooves 4 of the strapping frame 5, the comb and the tray open, the slots 8 of which the teeth 7 of comb 6 freely pass through. The burn and slag from the pallet first begin to pour into the formed opening. Then, as soon as the grate is turned away from the comb during turning, the ash and slag from the grate will begin to pour into the ash pan. When the grate reaches the initial (initial) position of the pan in its slot 9 will enter (crash) the teeth 7 of the comb, resulting in the grate will be completely cleaned (figure 5).

After that, the air channel is again formed, returning the grate to a horizontal position, fuel is poured and air is supplied through the hole 11 to the channel to resume burning of fuel on the grate. To prevent heat loss, the channel walls are thermally insulating.

The implementation of the invention will improve the efficiency of combustion devices by reducing the mechanical entrainment of fuel, reduce the amount of harmful emissions and improve operating conditions.

Information sources

1. A.S. USSR No. 1281814, F23В 1/32, 1987 - analogue.

2. A.S. USSR No. 1165849, F23H 9/00, 1980 - prototype.

Claims (8)

1. A method of burning solid fuels, including supplying air to the fuel combustion zone, burning the latter, outputting small fractions of fuel and slag through the slit of the grate, characterized in that the air is supplied through a channel that is formed under the grate, while fractions are removed into the resulting channel , where they are detained, and then removed and at the same time the slots of the grate are cleaned of slag, for which the channel walls are periodically opened. 2. The method according to claim 1, characterized in that the grate is made swinging and at the same time with a pallet having slots, each of which lies in the same plane with the corresponding grate slit. 3. The method according to claim 1, characterized in that the grate slots clean the teeth of the comb. 4. The method according to claim 1, characterized in that one channel wall is formed from a pallet and comb teeth inserted into its slots. 5. The method according to claim 1, characterized in that the other wall of the channel is formed from a comb. 6. The method according to claim 1, characterized in that when opening the channel, the air supply to it is stopped. 7. The method according to claim 1 and any one of claims 3 to 6, characterized in that the teeth of the comb are made unequal in height relative to the surface of the pallet. 8. The method according to any one of claims 1 to 6, characterized in that the channel walls are thermally insulating.

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