RU2239127C1 - Device for simultaneous and alternating burning of p\lumpy fuel with other kind of fuel - Google Patents

Abstract

FIELD: device for simultaneous or alternating burning of liquid, gaseous and solid fuels.

SUBSTANCE: proposed device is provided with furnace, fuel supply unit, furnace unit for burning fuel in layer at delivery of primary air; secondary air is fed through cyclone-type primary furnace above fire grate at level of delivery of solid fuel; furnace has combustion chamber and injector for delivery of fuel and primary air. High-reaction fuel is fed to injector. Secondary air is additionally fed through nozzles mounted on furnace walls. Cyclone-type primary furnace is mounted at height equal to 1/3 of height of furnace. Primary furnace is provided with peripheral swirler. Combustion chamber of primary furnace is provided with tangential nozzles for delivery of primary and secondary air. Device is provided with two and more primary furnaces which are mounted opposite each other in such position that jet or vortex flow of secondary air at primary furnace is directed towards jet or vortex flow of secondary air at outlet of opposite primary furnace. Proposed device may work on different kinds of fuel with no interruption in technological process.

EFFECT: enhanced efficiency and ecological safety; reduction of mechanical and chemical incomplete combustion.

9 cl, 2 dwg

Description

The invention relates to the field of boiler technology, in particular to devices for the simultaneous or alternate combustion of liquid, gaseous and solid fuels.

Known furnace devices, the design of which allows you to burn simultaneously or alternately different types of fuel in boiler plants. So, for example, a cyclone pre-furnace is known (RF patent No. 2180074, priority of 06/20/2000), containing an air supply duct, a combustion chamber and an axial nozzle. The pre-furnace provides reliable economical combustion of various types of fuel, but it does not allow to burn lump fuel.

It is also known a device that allows you to burn low-reactive fuel in a pulverized state using special burners that are installed in the lower part of the furnace (Thermal and nuclear power plants: Reference book / Under the general editorship of V.A. Grigoriev, V.M. Zorin. - 2nd ed., revised, t. 3. -M .: Energoatomizdat, 1989, 608 pp.).

However, this device contains several disadvantages:

- requires an additional device for the preparation and grinding of coal to a pulverized state;

- the device requires the main flame to be illuminated with fuel oil or gas using muffle oil burners or dust and gas burners, while the torch is pulled into the low temperature region, since fuel oil or gas burns faster due to higher reactivity, which in turn leads to mechanical burnout;

- the device does not provide an output of nitrogen oxides at the level of 200 mg / m (requirements for environmentally friendly TPPs) without the use of additional means, such as stage (step) burning, reagent injection into the combustion zone, etc.

Also known devices for producing hot water, steam or superheated steam, allowing to burn ground low-reaction solid fuel simultaneously with highly-reactive fuel (AS SU 1185015 A, MKI F 23 C 1/10, 1985 and patent RU 2138729, IPC F 23 C 1/10, 1999), containing the furnace space, horizontal and tempering flues, a pipe system of water heating surfaces and thermal cyclone pre-furnace (s), docked to the furnace space and serving (s) for thermal preparation solid low-reaction fuel, being such an image m derived burners for burning in it (them) a gas suspension.

However, such a device also does not allow lump coal to be burned, it requires preliminary grinding, sorting, and additional drying, which not only complicates the design, but also increases energy consumption, in addition, mechanical underburning of coal is observed with insufficient grinding or when the quality characteristics of the input coal change.

Also known are multi-fuel steam boilers designed on the basis of E-type (KE) bed-type boilers of various capacities, which use wood waste containing fuel as a fuel chamber, secondary air nozzles, pre-furnaces for burning fuel, a hopper for supplying fuel, burners for illumination with gas (fuel oil) (httpzh // www.kotel.ru / catalog / boilermoregas / index.html). Such boilers are used mainly to produce saturated steam used for the technological needs of logging and woodworking enterprises, which in turn limits the possibilities of using these structures. When using coal as a fuel in the aforementioned design, sintering of the upper layer of coal is observed due to open sources of fire in the form of nozzles that are used to illuminate or maintain a given load, and local overheating of heating screen surfaces is observed when using the same nozzles or burners, in addition, highly reactive fuel burned in nozzles takes part of the air supplied to the bed, which impairs the quality of fuel combustion in the bed and increases its entrainment. There is also insufficient twisting of the trajectory of movement of solid particles of fuel in the furnace volume and, as a result, mechanical underburning of coal.

The task of this technical device is the creation of a heat-generating installation that can efficiently operate on different types of fuel simultaneously or alternately with the possibility of switching from one energy source to another without stopping the process while increasing the heat transfer efficiency in the combustion chamber, increasing the efficiency of fuel combustion by reducing chemical and mechanical underburning and improving environmental performance by reducing emissions of nitrogen and carbon oxides in the atmosphere RU.

This problem is solved by a device that contains a furnace for the boiler, a fuel supply device, a furnace device for burning fuel in a layer with a supply of primary air. What is new is that secondary air is supplied through a cyclone pre-furnace docked to the furnace above the grate at the level of solid fuel supply to the furnace and containing a combustion chamber and a nozzle with fuel and primary air. It is better when only highly reactive fuel is brought to the nozzle. Additionally, secondary air can also be supplied through nozzles mounted on the walls of the furnace in “dead” zones - in places where turbulence coming from the furnace is unattainable, thereby increasing the trajectory of twisting of small particles. It is better when the cyclone pre-furnace is installed at a height approximately equal to one third of the height of the furnace. It is better when the nozzle of the pre-furnace contains a peripheral swirl, and the combustion chamber of the pre-furnace is equipped with tangential nozzles for supplying primary and secondary air. The device may contain two or more pre-furnaces, it is better when the pre-furnaces are installed against each other and the twisting of the torch and / or vortex stream of secondary air at the outlet of the pre-furnace is directed towards the twisting of the torch and / or vortex stream of secondary air at the exit from the opposite pre-furnace. This arrangement of the pre-furnaces allows one to concentrate the temperature effect in the central high-temperature part of the furnace and to avoid local overheating of the screen heating surfaces, and the counter-twisting of the secondary air or torch emerging from the pre-furnaces allows increasing the quality of combustion of small fractions of fuel.

The invention is illustrated by schematic drawings. Figure 1 shows the device in section with a fixed grate and one cyclone pre-furnace mounted on the rear wall of the furnace; figure 2. shows a section of a furnace with a fixed grate and two cyclone pre-furnaces mounted against each other.

The invention is illustrated by an example of a specific implementation.

Example 1. A device with a fixed grate and one cyclone pre-furnace

The device comprises a firebox 1, a lighter fuel supply device 2, which is a hopper connected by a feeder to a spreader, as well as a fixed grate 3 with a supply of primary air and located on the back wall of the firebox at the level of solid fuel supply to the firebox at a height of approximately one third from the entire height of the furnace, a cyclone pre-furnace 4 with a secondary air supply. Fuel and primary air are connected to the nozzle 5 installed in the pre-furnace. Lump fuel is fed into the furnace 1 through a fuel supply device 2, where large pieces are burned on a fixed grate 3 in a stream of primary air coming from below. At the same time, small combustible particles of solid fuel with flue gases are removed from the layer or separated from larger ones at the moment of entry into the furnace and, under the influence of a vortex stream of secondary air leaving the cyclone pre-furnace, are twisted in the vortex combustion zone 6, in which the fuel is burned. Secondary and primary air is supplied to the fluidized bed and to the pre-furnace from a high-pressure fan (not shown) under a variable pressure from 800-1000 mm water column. and adjustable by rotary dampers (not shown). When firing up, when switching the boiler to a different type of fuel or maintaining stable boiler operation, a highly reactive fuel is additionally supplied to the nozzle 5 with the simultaneous supply of primary air, the pressure of the secondary air supply to the pre-furnace is reduced to 200-400 mm water column As a result, small combustible particles of fuel twist and burn under the action of a vortex flow arising at the exit from the pre-furnace.

Example 2. A furnace with a fixed grate and two cyclone pre-furnaces mounted against each other

The device comprises a firebox 1, a lump fuel supply device 2, which is a hopper connected by a feeder to a spreader, as well as a fixed grate 3 with a primary air supply and cyclone preheaters 4 located on the side walls of the furnace at the level of solid fuel supply to the furnace, opposite each other friend, with the supply of secondary air to the furnace box. The nozzles 5 installed in the pre-furnaces are supplied with fuel and primary air. Lump fuel is fed into the furnace 1 through a fuel supply device 2, where large pieces are burned on a fixed grate 3 in a stream of primary air coming from below. In this case, small combustible particles of solid fuel with flue gases are removed from the layer or separated from larger ones at the moment of entry into the furnace and, under the action of vortex flows of secondary air coming out of the cyclone pre-furnaces, twist and collide in the vortex combustion zone 6, in which the fuel is burned . When firing up, when switching the boiler to a different type of fuel, or while maintaining stable operation of the boiler, highly reactive fuel is additionally supplied to the nozzles 5 with a simultaneous supply of primary air with a pressure of up to 2000 mm Hg, the pressure of the secondary air supply to the preheater is reduced to 300- 400 mm water column As a result, small combustible particles of fuel, spinning, collide and burn under the influence of vortex flows arising at the exit from the pre-furnaces.

The technical result of the device is to improve the quality of burning solid fuel. Comparative analysis with other technical solutions allowing to burn lump fuel and use simultaneously or alternately different types of fuels showed that such a technical solution allows you to qualitatively change the combustion process and quickly, without design changes, switch from one type of fuel to another or use them together. The volume of the fine fraction, inevitably present in lump fuel, picked up by an upward flow of gases, not having time to burn in the furnace, significantly decreases, the efficiency of the combustion process increases. The volume of wet dust collection products sent to sedimentation tanks is also significantly reduced, which contributes to less environmental pollution. During the combustion process, there is no multiple circulation of abrasive particles of solid fuel, which reduces the abrasive wear of the boiler. Additionally, as a result of the elimination of open fire in the combustion chamber above the fluidized bed, the effect of lowering the sintering ability of the bed is achieved, and the transfer of the boiler to peak mode is faster and less technically difficult.

During the heating period of 2001, cyclone-vortex pre-furnaces were launched with the fluidized bed operating to maintain a given load due to the unsatisfactory quality of solid fuel. Visual observations showed improved mixture formation and more efficient use of the furnace volume.

The layer parameters, temperature and aerodynamic drag remained unchanged. The efficiency of the boiler according to rapid tests increased by q ₂ , t _yx and α by 2-3%, in addition, this boiler has the advantage of quick heating of the layer using the ignition nozzles of cyclone pre-furnaces, as well as a smooth transition to any load with one type of fuel to another, since each burner has its own thermal calculation for the optimal parameters of the boiler.

Thus, we can conclude that the proposed method has not only economic advantages, but also technical advantages achieved by distinguishing features.

Claims (9)

1. A device for the simultaneous or alternate burning of lump with another type of fuel, comprising a furnace, a fuel supply device, a furnace device for burning fuel in a layer with a primary air supply, characterized in that the secondary air is supplied through a cyclone pre-heater docked to the furnace above the grate gratings at the level of supply of solid fuel to the furnace, containing a combustion chamber and a nozzle with a supply of fuel and primary air. 2. The device according to claim 1, characterized in that highly reactive fuel is supplied to the nozzle. 3. The device according to claim 1, characterized in that the secondary air is additionally supplied through nozzles mounted on the walls of the furnace. 4. The device according to claim 1, characterized in that the cyclone pre-furnace is installed at a height approximately equal to one third of the height of the furnace. 5. The device according to claim 1, characterized in that the nozzle pre-furnace contains a peripheral swirl. 6. The device according to claim 1, characterized in that the combustion chamber of the pre-furnace is equipped with tangential nozzles for supplying primary and secondary air. 7. The device according to claim 1, characterized in that it contains two or more pre-furnaces. 8. The device according to claim 6, characterized in that the furnace is installed opposite each other. 9. The device according to claim 7, characterized in that the pre-furnaces are installed so that the swirling of the torch and / or the vortex stream of the secondary air at the outlet of the pre-furnace is directed towards the swirling of the torch and / or the swirling stream of secondary air at the exit of the opposite pre-furnace.

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