RU2704178C1 - Flare combustion device - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: fuel flare combustion device includes an ignition chamber, an alternating current source, at least two rod electrodes connected to the alternating current source, a fuel air mixture supply channel, a secondary air channel, a cooling chamber, wherein between the ignition and cooling chamber there are passages for installation of rod electrodes. At least one constant-voltage source is connected to one of the rod-type electrodes relative to the chamber of the ignition chamber. A flame-forming chamber is installed at the outlet of the ignition chamber, to which the secondary air channel is connected. Rod electrodes are fixed on heat and current conducting racks, the other end of which is fixed on support plates arranged in cooling chamber in isolation relative to current-conducting surfaces of device.

EFFECT: invention allows ignition and combustion of whole volume of pulverized coal fuel supplied to boiler burners at reduced requirements to burnt fuel.

3 cl, 2 dwg

Description

The invention relates to energy and can be used in thermal power plants, boiler houses, etc. to optimize the combustion process and ensure the ignition of boilers and stabilize the combustion of fuel, for example, coal dust, during its flaring without the use of additional highly reactive fuel.

A technical solution is known, disclosed in the patent for invention RU 2377467 C2 (IPC F23D 1/00; published December 27, 2009), which is a device for flaring fuel. This device contains an ignition chamber, the inner surface of which has a cylindrical shape, a channel for supplying fuel mixture to this chamber, a plasma torch equipped with rod electrodes. The plasma torch is mounted on the side surface of the ignition chamber, at its entrance. The device also contains a nozzle of the ignition chamber, in which the plasmatron is installed, and a secondary air channel.

In the design of this device, there is no separation into the ignition chamber and the cooling chamber, secondary air is supplied directly to the ignition chamber. In this regard, the risk of rapid separation of the torch and its extinction during operation of this device increases, which is a significant disadvantage of the known device.

A technical solution is known, disclosed in the patent for invention RU 2059926 C1 (IPC F23D 1/00, F23Q 13/00; published on 05/10/1996), which is a device for flaring fuel. This device contains a channel for supplying fuel mixture, a secondary air channel with a swirl installed in it, a plasma torch igniter with rod electrodes. This device is characterized in that the plasmatron-igniter with rod electrodes is installed in the feed mixture, the electrodes are made of graphite and placed along the entire length of the feed mixture, and the plasmatron-igniter is equipped with double-flow nozzles and installed with the possibility of longitudinal movement between the rod electrodes, the plasma torch nozzles are oriented at the ends of the electrodes.

From the point of view of operation, this device is characterized by low reliability of ignition of pulverized coal fuel, as well as a large specific electric power of the burner and its large size. This, in turn, leads to high specific energy costs during operation of the known device, which is a significant drawback. In addition, due to the rapid wear of the rod electrodes, it becomes necessary to replace them, which complicates the process of servicing the known device for flaring fuel. As a prototype, the well-known technical solution is disclosed in the patent for invention RU 2410603 C1 (IPC F23Q 5/00, F23Q 13/00; published on January 27, 2011), which is a device for flaring fuel. This device comprises a housing, rod electrodes connected to a source of high-frequency alternating current for generating an electric arc, a channel for supplying fuel mixture and a secondary air channel, according to the invention, the housing is divided into an ignition chamber and a cooling chamber, wherein the secondary air passage is installed in the cooling chamber with installed in it with rod electrodes. The indicated features are common with the proposed technical solution.

The disadvantage of this device is the limited thermal power of the initiated flare and the impossibility of organizing the optimal process of burning the entire volume of fuel, since the design of the known device is focused only on the creation of the initiating flare. The supply of secondary air to the ignition chamber also limits the volume of flammable pulverized coal due to the need to increase air volumes and, as a consequence, the values of the flow rate of the mixture are unacceptable, in terms of flame separation. The disadvantages of this device include the low reliability of ignition of low-reactive fuels (lean, ballasted and waterlogged fuels, for example, coal-water fuel). This is primarily due to the subsequent ignition of the main torch from the received torch. When burning fuel with a high degree of slag formation, slagging of the surfaces of the ignition chamber can occur, which requires constant maintenance. This leads to a decrease in the reliability of the ignition system.

The objective of the invention is the creation of a device that allows you to ignite and burn the entire amount of pulverized coal supplied to the burner of the boiler with reduced requirements for combustible fuel (ballasted, lean, waterlogged coals), and to the temperature of the supplied fuel and air to the burner, which allows the boiler to start from a cold state with cold components and with minimal energy consumption without the use of highly reactive fuels. That ensures the reliability of the boilers and the safety of the processes of kindling and fuel combustion. The technical result of the claimed invention is the possibility of flaring fuel, including low reaction, and increasing the efficiency of its combustion.

The efficiency of fuel combustion is understood as the generation of thermal energy with its minimum losses (minimum excess air, that is, close to the stoichiometric value, as well as the minimum chemical and mechanical underburning of the fuel).

The technical result provided by the invention is achieved in that the fuel flaring device comprises an ignition chamber, an alternating current source, at least two rod electrodes connected to an alternating current source, a fuel mixture mixture supply channel, a secondary air channel and a cooling chamber, between the ignition and cooling chamber made passages for the installation of rod electrodes. The inventive device for flaring fuel is characterized in that at least one of the rod electrodes is connected, relative to the shell of the ignition chamber, a constant voltage source, and at the outlet of the ignition chamber there is a torch forming chamber to which a secondary air channel is connected. This device design allows the excitation of a diffuse electric discharge between the electrodes, which produces ionization and ignition of the fuel mixture. In this case, due to chemoionization processes, a highly ionized pre-flame zone of the torch is formed, which is the main condition for ensuring heterogeneous chemical reactions of oxidation of the entire volume of the fuel mixture, which allows efficient burning of low-reaction fuel, i.e., an oxidation reaction that has a high activation energy. The presence of at least one rod electrode, connected to it, relative to the shell of the ignition chamber, with a constant voltage source, allows you to maintain a highly ionized state of the flame zone of the flame and ensure that the necessary conditions for the complete combustion of the fuel mixture during its flaring are fulfilled. In addition, the presence of a secondary air channel connected to the torch forming chamber ensures the formation and burning of the torch in the furnace by supplying secondary air to the torch forming chamber through the secondary air channel. Thus, the creation of the possibility of flaring fuel is achieved, as well as increasing the efficiency of burning low reactive fuel.

The rod electrodes are mounted on heat and conductive racks, the other end of which is mounted on support plates placed in the cooling chamber in isolation relative to the conductive surfaces of the device. This allows, on the one hand, to reliably fix the rod electrodes, and on the other hand, to remove excess heat from the rod electrodes and base plates. This leads to an increase in the life of the rod electrodes, increasing the reliability of the device for efficient combustion of low-reaction fuel.

In addition, the cooling chamber is provided with a channel for supplying sealing air, and secondary air is supplied to the torch forming chamber. This allows you to remove heat from the rod electrodes by supplying sealing air to the cooling chamber, which leads to efficient heat removal from the electrodes of the device, which increases the reliability of the device for efficient burning of low reaction fuel. Also, the supply of secondary air to the chamber of the formation of the torch ensures optimal formation of the torch and, as a result, the efficiency of burning low-reactive fuel using the inventive device for flaring fuel.

In Fig.1 presents a schematic diagram of a device for flaring fuel, in Fig.1. 2 shows a schematic diagram of an ionization unit 2.

The proposed device for flaring fuel contains (Fig. 1) a feed channel for fuel mixture 1, an ionization unit 2, a chamber for forming a torch 3, an alternating current source 4, a constant voltage source 5.

As the fuel mixture can be used any known fuel air mixture. A fuel mixture is a mixture of air or an oxidizing gas, for example, oxygen, and fuel. The fuel used can be in any aggregate state (solid, liquid or gaseous), however, the necessary condition is the size of the particles or drops of fuel, if solid or liquid fuel is used as a component of the fuel mixture, respectively. The particle size for solid fuels should not exceed 60 microns. At the same time, for liquid fuel, the droplet size should not exceed 10 microns. Examples of solid fuels that can be used as a component of air mixtures are coal, peat, wood waste, etc. Examples of liquid fuels that can be used as a component of air mixtures are petroleum products, coal-water fuels, etc.

As an alternating current source 4, an alternating current source of any known design can be used, for example, a commercially available converter of the power source of a plasma generator IRBI943-5.5-0.4 UHL3.1V. As a constant voltage source 5, a constant voltage source of any known design can be used, for example, a commercially available high voltage source, built according to the voltage multiplication scheme, IVNR-5/50. The ionization unit 2 contains an ignition chamber 6, a cooling chamber 7, rod electrodes 8 mounted on current and heat-conducting racks 9, supporting insulators 10 mounted outside the ignition chamber 6, which serve as a support for the plate 11 connected by fasteners 12 to insulators 10 and stand 9. In the cooling chamber 7, which is hermetically sealed, passages are made for the electric cable 13, passage 14 for introducing cooling air and passage 15 for racks 9.

The feed channel of the fuel mixture 1 can be made of any known structural material, for example, steel. The ionization unit 2 can be made of any known conductive structural material, for example, steel. The rod electrodes 8, racks 9 and the support plate 11, in turn, can be made of any known current-conducting and heat-conducting material, for example, copper or bronze. The chamber forming the torch 3 can be made of any known heat-resistant material. As an example, the torch forming chamber 3 can be made of heat-resistant alloy steel, for example, steel grade X20H35. In addition, the torch forming chamber 3 may have an internal high-temperature thermal insulation coating made using any known refractory material, for example, material made from fireclay powder, refractory clay, etc., resistant to temperature in the temperature range, the upper limit which reaches 1500 ° C - 1700 ° C.

The operation of the device flaring plasma fuel is as follows.

In the ignition chamber 6 through the channel 1 for supplying the fuel mixture serves prepared aerosol mixture of fuel. From the AC source 4, AC voltage is applied to the rod electrodes 8 in the frequency range 1-30 kHz, the breakdown of the interelectrode space occurs, as a result of which the electrical circuit is closed. As a result of this, a diffuse electric discharge is excited, which produces ionization and ignition of the fuel mixture. At the same time, due to chemoionization processes, a highly ionized pre-flame zone of the torch is formed, which is the main condition for ensuring heterogeneous chemical reactions of oxidation of the entire volume of the fuel mixture. Ensuring the occurrence of heterogeneous chemical processes is the main condition for burning low-reactive fuels, including coal-water fuels. To ensure a highly ionized state of the flame zone of the flame, at least one rod electrode 8 is supplied with an electrostatic potential from a constant voltage source 5 relative to the conductive surface of the ignition chamber 6. The ignition chamber 6 can be made as part of the channel 1 for supplying fuel mixture. The ignited aerosol mixture enters the torch formation chamber 3, where the main chemical processes take place. Further, the formed torch containing highly activated components of the fuel and oxidizer enters the furnace of the boiler, in which the complete combustion of fuel is carried out. When changing the characteristics of the fuel, its volume, etc. regulate the value of the potential of the pre-flame zone, providing the required parameters of the combustion of the torch. The range of variation of the electric potential is in the range from 0.1 to 5 kV.

To ensure the formation and combustion of the torch in the furnace, secondary air is supplied through the secondary air channel to the chamber of formation of the torch 3. Excess air in the chamber forming the torch 3 is set taking into account the organization of fuel combustion in the furnace.

The heat generated on the rod electrodes 8 is removed through the conductive racks 9 to the support plate 11, which is cooled by the sealing air entering the shell of the ionization unit 2. After that, the heat is discharged into the ignition chamber of the torch 3 through the passages 15 for the conductive racks 9, made in torch ignition chamber 3. Part of the thermal energy from the rod electrodes 8 and racks 9 is removed by the flow of fuel mixture, which ensures the durability of the rod electrodes 8.

At the exit from the chamber for forming the torch 3, a fuel mixture is obtained with a temperature above 700 ° C and a content of combustible substances in the gas phase of up to 50%. Such a mixture burns steadily, which makes it possible to increase the reliability of the torch burning even in a cold furnace, which makes it possible to use this device for the purpose of firing up boilers without the use of highly reactive fuel, providing a high degree of fuel burnout.

The frequency of operation of the AC source 4 is selected from the conditions for ensuring a stable diffuse discharge and technical limitations associated with technical implementation, is in the range of 3 - 50 kHz. To limit the erosion of the rod electrodes 8, the amplitude current should be in the range of 0.1 - 2 A, which ensures the durability of the rod electrodes 8 without replacing them.

The device described in the text of this application may have many specific options for implementation, in this application only the essential features of the invention and the best execution of the invention are disclosed, which does not limit the applicability of the present invention, it is obvious to the person skilled in the art many possible variants of the invention according to the present description.

The application of the invention allows the flare combustion of fuel, including low reaction, and increase the efficiency of its combustion.

Claims (3)

1. The device for flaring fuel containing, the ignition chamber, an alternating current source, at least two rod electrodes connected to an alternating current source, a fuel mixture supply channel, a secondary air channel, a cooling chamber, and passageways for installation are made between the ignition and cooling chamber rod electrodes, characterized in that, at least to one of the rod electrodes, relative to the shell of the ignition chamber, a constant voltage source is connected, at the output of EASURES ignition flame formation chamber is set to a summed channel secondary air. 2. The fuel flaring device according to claim 1, characterized in that the rod electrodes are mounted on heat and conductive racks, the other end of which is fixed on support plates placed in the cooling chamber in isolation relative to the conductive surfaces of the device. 3. The fuel flaring device according to claim 1, characterized in that the cooling chamber is provided with a channel for supplying sealing air, and the secondary air is supplied to the flare chamber.

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