RU2779675C1 - Method for flare combustion of an air-fuel mixture and apparatus for the implementation of the method - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to power engineering and can be used at thermal power plants, in boiler rooms, etc. to ensure ignition and stabilise the burning of pulverised coal fuel. Method for flare combustion of an air-fuel mixture consists in igniting a highly reactive fuel — oil residue — in a burner apparatus using an ignition-safety apparatus, wherein the muffled part is heated due to the combustion of oil residue; after the muffled part is heated, the air-fuel mixture is supplied into the incandescent muffled part, the air-fuel mixture is ignited from the muffled part due to the process of thermal effect, and a flare is formed. The process of activating the process of combustion of the air-fuel mixture is conducted simultaneously with the process of thermal ignition of the air-fuel mixture due to an electric discharge on the air-fuel mixture.

EFFECT: possibility of igniting pulverised coal fuel with a high content of moisture, ash and a low level of volatile components with minimal specific power costs.

5 cl, 1 dwg

Description

The invention relates to energy and can be used in thermal power plants, boilers, etc. to ensure ignition and stabilization of combustion of pulverized coal fuel.

A known method of burning low-grade coals and a plasma burner for its implementation (patent RU No. 2059926, C 1, MKI F23D1 / 00, F23Q13 / 00, 1992), which consists in generating an electric plasma arc in a plasma torch-igniter with rod electrodes, heating the air mixture in an arc plasma, ignition and stabilization of the combustion of the air mixture. Electric plasma arc generation is carried out in the air mixture supply channel made in the burner. For this purpose, an electric plasma arc is initially generated in the specified channel and the main arc is excited by its plasma flows, while the plasma torch-igniter is moved along the rod elements as they are eroded.

The disadvantage of this method is the high energy consumption of the plasma torch igniter, as well as the small volumetric contact of the arc discharge of the plasma torch and the pulverized coal mixture. Also, the disadvantages of this method include high temperatures (up to 6000 ℃) at which the plasma torch equipment operates, which affects the reliability and durability of the plasma torch parts.

A well-known plasma pulverized coal burner contains an air mixture supply channel, a secondary air supply channel with a swirler installed in it, a plasma torch-igniter with rod electrodes (patent RU No. 2059926, C 1, MKI F23D1 / 00, F23Q13 / 00, 1992). The plasma torch-igniter with electrodes is installed in the air mixture supply channel. Graphite electrodes are placed along the entire length of the air mixture supply channel. The plasma torch-igniter is equipped with double-sided flow nozzles and is installed with the possibility of longitudinal movement between the rod electrodes, while the plasma torch nozzles are oriented to the ends of the electrodes.

The disadvantage of the plasma pulverized coal burner presented in this invention is the low reliability of ignition of pulverized coal fuel of different chemical composition and low reactivity, as well as the high electrical power density of the device and its large size.

A device for plasma ignition of pulverized coal containing a housing, rod electrodes for generating an electric arc, a fuel line and a secondary air pipeline is known (patent RU No. 2410603, C 1, MKI F23 Q 5/00, F23Q13/00, 2009). The body is divided by a transverse partition into resonant and cooling chambers. In the center of the partition, a passage of secondary air is made and rod electrodes are installed with the possibility of longitudinal movement, and their working part is directed inside the resonant chamber, and the electric arc is created by high-frequency alternating current in the resonant chamber with the formation of an acoustic field.

The disadvantage of this device is the limited thermal and electrical power of the initiated flame and, as a result, the impossibility of organizing the combustion of low-reactive fuel, since the design of the known device does not allow for both additional energy supply and localization of the available power.

A device adopted as a prototype for kindling a boiler with a muffled pre-furnace is known (Energy-saving systems for kindling and lighting the flame of the combustion chambers of boilers: monograph by V.A. Dubrovsky, M.V. Zubov. - Krasnoyarsk: Siberian Federal University, 2012, p. .98). The presented device contains a source of dust, an air supply channel, a kindling burner, an ignition signal device, a vapor-acoustic nozzle, a highly reactive fuel supply line. The kindling burner is implemented in the form of a muffled pre-furnace. The kindling of the boiler works as follows. With the help of an ignition-protective device, fuel oil was ignited, which was supplied through a steam-mechanical nozzle. Due to the combustion of a small amount of fuel oil, the inner wall of the muffled pre-furnace (the muffled part) was heated. The control over the heating mode of the muffled furnace was carried out using thermocouples, which recorded the flue gas temperature along the length of the muffled furnace and the temperature of its inner wall. After the muffled pre-furnace was warmed up at low speeds, the dust feeder was switched on, and high-concentration coal dust entered the red-hot muffle pre-furnace for combustion. The oil burner should have been turned off. The secondary air flow was regulated by means of a rotary damper through a remote control column. Passing through the heated muffled pre-furnace, the air-fuel mixture (a mixture of air and fuel) at a low air excess coefficient was subjected to preliminary thermal preparation, and the entire gasified flow of coal dust entered the volume of the boiler furnace, where it was burned out and the volume of the combustion chamber was subsequently heated.

The disadvantage of the described technical solution is the ignition of the air-fuel mixture (with coal dust), which occurs only due to thermal effects from a heated muffled pre-furnace. At the same time, a significant proportion of coal dust does not have time to be activated during the passage through the heated area, enters the furnace in an unignited state and contributes to the formation of zones with increased explosion hazard in the boiler furnace.

The problem solved by the invention is to create a device that allows, with minimal specific energy consumption, to ignite using low-reaction fuel (pulverized coal fuel with high humidity, ash content and low levels of volatile components), as well as to increase the stability of its subsequent combustion. To ensure the optimal quality of ignition and maintenance of flame combustion under various operating modes of boiler equipment.

The achievement of the technical result provided by the invention becomes possible due to the fact that a highly reactive fuel (for example, fuel oil, gas, diesel) or electrical action (for example, induction) heats up the muffled part of the burner device to the self-ignition temperatures of the air-fuel mixture, after which an alternating current is generated on the rod electrodes introduced into the body of the burner, affecting the root zone of the torch, and the supply of highly reactive fuel is stopped. The ignition of the air-fuel mixture using low-reactivity fuel (pulverized coal fuel with high humidity, ash content and low levels of volatile components) is achieved due to the effect of electrical activation of pulverized coal by an electric discharge and thermal activation due to radiation from the muffled part of the burner device. During kindling, when one of the activating agents is exposed to the low-reactivity air-fuel mixture, the activation energy is not enough, the combustion process will be damped. In this case, both the electric discharge and the highly reactive fuel are used as a stabilizer for flame combustion in case of fluctuations in the quality of pulverized coal or at reduced boiler loads. And both jointly and separately. The position of the torch in the burner and the length of the torch outlet into the furnace space is controlled by the supply of highly reactive fuel and/or by the presence of an electric discharge.

To implement the described method, according to the invention, a device for thermoelectric ignition of an air-fuel mixture using a low-reactivity fuel (pulverized coal fuel with high humidity, ash content and a low level of volatile components) is proposed, containing a muffled part, rod electrodes for generating an electric discharge, fuel lines of highly reactive fuel and an air pipeline. According to the invention, the muffled part is heated by burning a highly reactive fuel (for example, fuel oil, gas, diesel) or by electrical action (for example, induction). An electric discharge on rod electrodes introduced into the burner is generated by alternating current. After that, the air-fuel mixture is supplied to the burner. When passing through the burner, the dust-air mixture is affected by thermal and electrical activation. After reaching the self-ignition temperature in the furnace space, the source of the electric discharge is turned off. The operating mode of the burner device becomes autonomous, self-sustaining. When it becomes necessary to maintain the torch, the supply of highly reactive fuel and/or electric discharge is switched on.

From the prior art, no solutions have been identified that have features that coincide with the distinguishing features of the invention. Therefore, it can be argued that the proposed technical solutions meet the condition of inventive step.

The essence of the invention is illustrated by the attached drawings.

Figure 1 shows a longitudinal section of a plasma ignition device for pulverized coal.

The proposed device for thermoelectric ignition of an air-fuel mixture using a low-reactivity fuel (pulverized coal fuel with high humidity, ash content and a low level of volatile components) contains a muffled part (1), an air supply pipeline (2), a low-reactivity fuel supply pipeline (pulverized coal fuel) (3), highly reactive fuel pipeline (4), ignition-protective device (5), rod electrodes (6) for generating an electric discharge (7), connected to a power source (8). The pulverized coal torch (9) has the ability to move inside the burner (10) and the furnace space of the boiler (11).

The proposed method and device for flaring the air-fuel mixture is implemented as follows.

Highly reactive fuel is supplied to the muffled part (1) through the pipeline (4), air through the pipeline (2) and ignited by the ignition-protective device (5), after heating the muffled body (1) to the ignition temperature of pulverized coal, to the rod electrodes (6 ), an electric current is supplied from the power source (8), and an electric discharge (7) is formed at the ends of the electrodes (6), and pulverized coal is supplied to the burner through the pipeline (3). Mixing with air from the pipeline (2), the pulverized coal coming from the pipeline (3) forms an air-fuel mixture. After that, the supply of highly reactive fuel (4) is stopped. The fuel-air mixture ignites under the influence of an electric discharge (7) and thermal radiation of the muffled part (1). As a result, a torch (9) for combustion of the air-fuel mixture is formed. Electric discharge (7) acts on the torch (9) until the torch (9) goes into a self-sustaining, non-extinguishing mode, after which it turns off. In case of deterioration of the quality of the pulverized coal coming from the pipeline (3) or a decrease in the load of the boiler (11), the supply of highly reactive fuel (4) and/or electric discharge (7) can be used to maintain the combustion of the pulverized coal torch (9). In stationary operating modes of the burner device (10), it is possible to control the length of the flame outlet (9) using highly reactive fuel (4) and/or electric discharge (7). This effect is achieved due to the additional supply of energy to the torch (9), which allows more of the pulverized coal fuel (3) entering the burner device (10) to enter into a chemical combustion reaction.

The present invention makes it possible to ignite a pulverized coal-fuel mixture using a low-reactivity fuel (pulverized coal fuel with high humidity, ash content and a low level of volatile components) with minimal specific energy consumption. Provides optimum quality of ignition and maintenance of burning of a torch at various modes of operation of the boiler equipment.

Claims (5)

1. The method of flaring combustion of the air-fuel mixture, which consists in the fact that in the burner with the help of an ignition-protective device, a highly reactive fuel - fuel oil is ignited, while the muffled part is heated due to the combustion of fuel oil, after heating the muffled part, the air-fuel mixture is fed into the red-hot muffled part, due to the process of thermal action from the muffled part, the air-fuel mixture is ignited and a torch is formed, characterized in that, simultaneously with the process of thermal ignition of the air-fuel mixture, the process of activating the combustion process of the air-fuel mixture is carried out due to an electric discharge on the air-fuel mixture. 2. A method for flaring an air-fuel mixture according to claim 1, characterized in that an electric discharge and a highly reactive fuel are used as a fuel-air mixture combustion stabilizer in case of fluctuations in the quality of pulverized coal or at reduced boiler loads. 3. The method of flaring combustion of the air-fuel mixture according to claim 1, characterized in that the position of the torch in the burner device and the length of the torch exit into the furnace space are controlled by supplying highly reactive fuel and/or by the presence of an electric discharge. 4. A device for thermoelectric ignition and maintenance of combustion of an air-fuel mixture, comprising a housing, an ignition-protective device, a muffled part, fuel lines of highly reactive and low-reactive fuel, characterized in that rod electrodes are introduced into the device housing, which produce electrical activation of pulverized coal due to an electric discharge. 5. The device for thermoelectric ignition and maintenance of combustion of the air-fuel mixture according to claim 4, characterized in that the position of the flame in the housing and the length of the flame outlet into the combustion space are controlled by supplying highly reactive fuel and/or by the presence of an electric discharge.

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