Questions&Answers

Methanol burner is a device that integrates all parts of methanol supply, atomization, air supply, ignition, flame detection and operation regulation control into one body, and is installed on the same cabinet to realize fully automatic control of the combustion process.

Working Principle

Adopting the classical principle of pilot combustion, combined with the principles of air, automatic control and combustion science, so that the methanol fuel really gets full combustion; overcoming the application for the fuel with more impurity content such as crude methanol and waste methanol after secondary filtration, preventing the occurrence of blockage and pump body damage phenomenon, and getting rid of the high-pressure pump body pressure atomization.

The advantages

1.High thermal efficiency: alcohol-based fuel burner, internal and external double-layer tangential cyclone system, reasonable structure, full combustion, high thermal efficiency.

2.High safety: boiler start-up first light small fire, when the small fire normal stable combustion, automatic control system before opening the main gas valve, the fuel can enter the boiler normal combustion, will not produce deflagration phenomenon.

3.Methanol fuel atomization is good, low energy consumption, low noise.

4.Stable flame, high combustion efficiency, low pollution to the environment.

5.Reliable installation, fully automatic control.

Flameless combustion characteristics

1.High temperature and low oxygen is the basic condition to achieve flameless combustion, the oxidizer is preheated to a certain high temperature before the reaction or the furnace chamber is fully preheated so that the temperature anywhere in the furnace during combustion is greater than the auto-ignition point of the fuel.

2.To make the fuel and oxidizer sufficiently diluted by means of high speed jet coiling and suction, or by means of special structure of the burner to produce reflux, as well as by filling with dilute gas, etc., so that the concentration of oxygen in the combustion reaction zone is kept at 2%-15% as far as possible.

3.In the flameless combustion mode, the combustion is "soft", there is no combustion noise, and the combustion space is diffused to a larger area, resulting in uniform temperature distribution and lower pollutant emissions in the whole space.

Three ways to achieve flameless combustion

1.Charge of nitrogen gas

2.High-speed jet

3.Special combustion chamber structure

Structure

The gas burner includes a firing bowl, a combustion nozzle, a gas inlet pipe, a gas inlet nozzle and an air inlet mechanism, the combustion nozzle is installed in the firing bowl, the gas inlet nozzle is installed at the outlet of the gas inlet pipe, the air inlet mechanism consists of a volute and a throat pipe, one end of the throat pipe is connected to the firing bowl, the other end is connected to the volute, the gas inlet pipe passes through the volute and the gas inlet nozzle is located in the throat pipe. 

The characteristics

The gas burner not only concentrates heat, but also burns fully, which greatly improves the combustion efficiency and helps to save gas, and also has the effect of fast and time-saving, and at the same time greatly reduces the content of nitrogen and sulfide in the combustion products and reduces pollution.

The gas burner has long service life, good sealing performance and high temperature resistance and anti-deformation ability, adopts the structure of separating the burner body and external pilot tube, and can be configured with different parameters of the pilot tube according to the nature of gas, so as to optimize the performance of the burner to the greatest extent.

Gas fuel is a gaseous fuel at room temperature, which has very outstanding advantages compared with various solid fuels and liquid fuels: less pollution, high heat generation, easy operation, etc. It is an ideal quality boiler fuel. There are two kinds of gas fuels: natural gas fuels and artificial gas fuels.

Natural gas fuel

There are two kinds of natural gas fuel: gas field gas and oil field associated gas. Gas field gas is a kind of combustible gas from pure gas field, and oil field associated gas is a combustible gas produced in the process of oil extraction. Both of these natural gaseous fuels are mainly composed of methane, but also contain small amounts of alkanes, olefins, carbon dioxide, hydrogen sulfide and nitrogen, etc. Both have a high calorific value. Because natural gas is an important chemical raw material, only a few boilers near the production area can use natural gas as fuel.

Artificial gas fuels

There are various types of artificial gas fuels, including blast furnace gas, coke oven gas, generator coal gas and liquefied petroleum gas. Except for liquefied petroleum gas, all of them have low calorific value and are low calorific value gas. Although blast furnace gas and coke oven gas have lower calorific value, they are mainly used as chemical raw materials and fuel for various heating furnaces, and only a small amount is used as boiler fuel in situ. The occurrence of furnace gas and liquefied petroleum gas, generally not used as boiler fuel.

1.Definition.

When a substance burns, smoke is produced and heat is given off along with visible or invisible light radiation. Flame detectors, also known as light-sensitive fire detectors, which are used to respond to the light characteristics of fire. That is, the light intensity of diffuse flame combustion and the flicker frequency of the flame of a fire detector.

2.Classification.

According to the light characteristics of the flame, there are three types of flame detectors used: one is the UV detector sensitive to the shorter wavelength of ultraviolet light radiation in the flame; another is the infrared detector sensitive to the longer wavelength of infrared light radiation in the flame; the third is the UV/IR hybrid detector that detects both the shorter wavelength of ultraviolet light and the longer wavelength of infrared light in the flame.

Specifically according to the detection band can be divided into: single ultraviolet, single infrared, double infrared, triple infrared, infrared / ultraviolet, additional video and other flame detectors.

According to the explosion-proof type can be divided into: explosion-proof type, intrinsically safe type.

3.The working principle

Flame detection signal comes from UV detector and smoke detector. In the above burner flame detector, the use of radiation light energy principle of the burner flame detector is the most widely used, but also the more effective method of burner flame detector. The principle of radiation light energy intensity detection is to use the probe to receive radiation from the flame, according to its intensity to determine the presence or absence of the flame.

Flame radiation is a discrete spectrum of gas radiation and accompanied by a continuous spectrum of solid radiation, its wavelength in the range of 0.1-10μm or more. The UV flame detection technology, which successfully enables the system to avoid the complex background caused by the most powerful natural light source, the sun, makes the burden of information processing in the system much less. Coupled with the fact that it is a photonic detection means, and thus has a high signal-to-noise ratio and the ability to detect very weak signals, in addition to its extremely fast response time. Compared with infrared detectors, UV detectors are more reliable and have high sensitivity, high output, high response speed and simple application lines. Therefore, UV burner flame detector is increasingly widely used in combustion monitoring, fire self-alarm, discharge detection, UV detection, and UV photoelectric control and other fields.

Solid fuels are a large category of fuels, solid combustible substances that produce heat or power, mostly containing carbon or hydrocarbons. The natural ones are wood, peat, lignite, bituminous coal, anthracite, oil shale, etc. The processed ones are charcoal, coke, briquettes, briquettes, etc. There are also some special varieties, such as solid alcohol and solid rocket fuel. Compared with liquid or gaseous fuels, solid fuels in general are harder to control in combustion, less efficient and have more ash.

Solid fuels include the following types.

1.Bituminous coal: known as long bituminous coal, gray-black or black, the surface is lusterless or has an oily luster.

2.Anthracite coal: called white coal or wood coal, black, sometimes gray, hard and brittle, with a lustrous cross-section.

3.Poor coal: between bituminous coal and anthracite, volatile to 10%-20%, easier to catch fire

4.Coal gangue: it is the coal seam with combustible quality of the sandwich stone, ash is high, reaching more than 50%, the heat is low, not suitable for fire.

5.Oil mother shale: it is a kind of ore containing oil, ash is very high, reaching 50%-70%, volatilization is also very high, reaching 80%-90%, it is easy to catch fire.

6.Firewood: It has less ash and high volatile content than coal, and burns quickly, but has low heat generation.

Principle

When the combustible gas (city gas, natural gas, LPG) is controlled by the microcomputer control system according to the program into the combustion head of the burner, the primary air is mixed with the combustible gas, ignition and combustion, and the secondary air assists combustion to achieve full combustion. The combustion condition is detected and controlled by the flame automatic tracking system. When there is a failure in combustion (lack of oxygen in the combustion chamber, underpressure of combustible gas, cut-off of combustible gas, insufficient gas quantity, etc.), the control system issues a command and the solenoid valve of the gas supply system is quickly closed to cut off the gas power supply, and the gas burner is automatically shut down after blowing to indicate the failure.

Features

(1) high thermal efficiency: can adapt to pressure fluctuations, self-regulating primary air distribution (that is, large gas pressure, inhaling more primary air; small gas pressure, inhaling less primary air), full combustion, high thermal efficiency.

(2) High safety: The burner is equipped with small fire. When the boiler starts, the small fire is lit first, and when the small fire burns normally and steadily, the automatic control system opens the main gas valve before the fuel enters the boiler for normal combustion, which will not produce the phenomenon of deflagration.

(3) High adaptability of fuel: This burner can be applied to natural gas, LPG, gas, LPG mixture and other types of gas by only replacing a small number of parts.

1.Power system

On the commonly used burner, there should be only electric motor related to power.

2.Fuel supply system

On the burner, this is one of the more complicated systems, in fact, the mechanical products involved in this system are much more complicated than the electrical products on the control system. Including fuel pumps, nozzles, fuel heaters, oil cups, fuel lines, fuel solenoid valves gas valves (including gas solenoid valves), gas regulators, gas filters, etc.

3.The combustion system

The most technical content of the burner industry a system. In fact, no matter how cutting-edge the technology of the electrical products in charge of the control, or how sophisticated the manufacture of the oil pump is, the level of these technologies and means have nothing to do with the burner manufacturer's own ability, but the design of the combustion system is something they must do on their own. Therefore, the level of the combustion system is what determines the ability of a burner. This part of the product includes the combustion cylinder, forced air blower impeller, flame plate, oil gun, gas core tube, and built-in or external diffusion head. This is the part of the product that constitutes the air-fuel premixing device.

1.Controller

The core part of the burner control, including the process management controller called proportional regulator, the gas leak detector responsible for detecting valve leaks, etc., are responsible for collecting and triggering the signal of each action, which is equivalent to the brain of the burner.

2.Servo mechanism

All electric servo motors and mechanical drive hydraulic cylinders are classified as control system, the reason is that the former and the program controller constitute a closed-loop control system, the latter's power source from the oil pump, the instructions for the execution of the action is actually triggered by the controller, and control the opening and closing of the dampers.

3.Flame monitor

This name is the name of the industry, the more popularly known as the name of its actual function, and eventually confused with the controller category, simply through the flame signal control open and close the controller - can monitor the flame is actually only photoresistors and phototubes, as well as the detection of flame ion ion probe, if the power can be turned on and off by itself should obviously be called more appropriate controller.

4.Pressure and temperature switch

Broadly speaking, it should be called pressure or temperature sensors. Among the pressure switches in the gas switch: gas switch, mostly used for gas burner gas control, wind pressure switch for the control of air (such as no forced air supply and wind pressure, the whole power cut off). The temperature switch is mostly used for the control of heating temperature of high viscosity fuel, such as heavy oil or residual oil.

Gas (liquefied gas, natural gas, city gas, coke oven gas, converter gas, mixed gas, furnace gas, blast furnace gas, etc.) burners have the advantages of easy ignition, complete combustion, stable flame, good spreading, no tempering, no de-flaming, large adjustment range, low noise, long life, safety and reliability due to reasonable structural design. 

1.Definition

According to its working principle, a burner can be defined as a device that converts substances into heat energy by means of a chemical reaction called combustion - that is, air and fuel are mixed in the right proportion through a premixing device to make them burn fully. The burner is a kind of thermal energy device that feeds fuel and air into the furnace chamber according to the required concentration, speed, turbulence and mixing method, and enables the fuel to fire and burn stably in the furnace chamber.

2.classification

Gas burner is divided into natural gas burner, city gas burner, etc.

According to the combustion control mode of the burner is divided into: single-stage fire burner, double-stage fire burner, proportional regulation burner.

Divided by fuel atomization: mechanical atomization burner, medium atomization burner.

Divided by structure: integral burner as well as split burner.

China's natural gas and coal gas (raw materials for coal) resources are abundant and clean energy, so there are good socio-economic benefits. However, in the design of gas burner development, gas characteristics - flammable, explosive and toxic, the primary issue of safety control. The following is an introduction to the gas burner safety control requirements: according to the combustion characteristics of gas in the furnace, the content of its safety control requirements are mainly pre-blowing, automatic ignition, combustion state monitoring, protection against non-ignition, protection against flame failure, protection against flame failure, protection against high and low gas pressure limits, protection against insufficient air pressure, power failure protection, measures to prevent gas leakage accidents, etc.

1.Pre-blowing air

Burner in the ignition before, there must be a period of pre-blowing air, the furnace and flue gas in the residual blowing or dilution. Because the work of the burner furnace inevitably have residual gas, if not pre-blowing air and ignition, there is a risk of explosion. The residual gas must be blown clean or diluted to ensure that the gas concentration is not within the explosion limit.

2.Automatic ignition

Gas burners should use electric spark ignition, to facilitate the realization of automatic control. Available high-voltage ignition transformer to generate an arc ignition, the output energy required: voltage ≥ 3.5K V, current ≥ 15mA.

3.Combustion state monitoring

Combustion state must be monitored dynamically, once the flame detector detects the flame out signal, must be a very short time feedback to the burner, the burner then into the protection state, while cutting off the gas supply.

4.The protection of non-ignition

When the burner is ignited, gas is introduced and the gas catches fire and burns. Ignition action is required to occur before the gas into the first formation of the ignition temperature field, to facilitate the ignition and combustion. If the fire does not ignite, the flame detector does not sense the flame signal, the burner enters the protection state. The time from ignition to enter the protection state should be appropriate, neither too short nor too long, generally required in 2-3 seconds into the gas, the burner to the flame detector to detect the flame signal to judge, not on fire then enter the protection state, on fire to maintain combustion.

5.Flame out protection

Burner in the process of combustion, if the accidental flame out, the burner into the protection state. As the furnace chamber is hot. Gas is prone to deflagration, so it must enter the protection state in a very short time, cut off the gas supply.

6.Gas pressure high and low limit protection

 Stable combustion of gas burners have a certain range, only allow gas pressure fluctuations within a certain range. The purpose of limiting the gas high and low pressure is to ensure flame stability: no flame off, no flame out and no flame back, while limiting the output thermal power of the burner to ensure the safe and economic operation of the equipment. When the gas pressure exceeds this range, the burner should be locked to work.

7.Insufficient air pressure protection

 The gas burner is designed with high thermal intensity and its combustion method is forced by the blower. If the fan fails to cause air interruption or air shortage, immediately cut off the gas, otherwise, the chamber will be burst combustion or backfire to the fan. Therefore, while improving the quality of the fan, the gas control must be interlocked with the air pressure, when the air pressure is insufficient, the gas supply should be cut off immediately.

8.Power failure protection

Burner in the process of working suddenly power failure, must immediately cut off the natural gas supply to protect the safety of equipment. Gas control solenoid valve must be normally closed type, once the power failure, automatically shut off the gas supply.

9.Measures to prevent gas leakage accidents

Gas leakage includes two aspects, one refers to the gas leakage to the environment through the pipeline, and the other refers to the gas leakage to the furnace through the end of the solenoid valve spool. Environmental leakage may cause poisoning and explosion at the work site, which must be paid great attention to. Leakage inside the furnace may cause an explosion inside the furnace. Prevention of gas leakage measures are peripheral control, generally not included in the burner body control.

Tracing the history of the development of solenoid valves, so far, domestic and foreign solenoid valves from the principle is divided into three categories, namely: direct-acting, step-by-step direct-acting, pilot type .

First, direct-acting solenoid valve 

Principle: When energized, the solenoid coil generates electromagnetic force to lift the closing member from the valve seat, the valve opens; when disconnected, the electromagnetic force disappears and the spring force presses the closing member on the valve seat, the valve closes. 

Features: in the vacuum, negative pressure, zero pressure can work properly, but the general diameter does not exceed 25mm. 

Second, step-by-step direct-acting solenoid valve 

Principle: It is a combination of direct-acting and piloting principle, when the inlet and outlet pressure difference ≤ 0.05Mpa, when energized, the electromagnetic force directly to the pilot small valve and the main valve closure parts in turn upward lift, the valve open. When the inlet and outlet pressure difference > 0.05Mpa, when the power is applied, the electromagnetic force opens the pilot valve first, the pressure in the lower chamber of the main valve rises and the pressure in the upper chamber falls, thus using the pressure difference to push the main valve upward; when the power is off, the pilot valve and the main valve use the spring force or medium pressure to push the closing member and move downward to close the valve. 

Features: in zero differential pressure or vacuum, high pressure can also work reliably, but the power is larger, requiring vertical installation. 

Third, the pilot operated solenoid valve 

Principle: When energized, the electromagnetic force opens the pilot hole, the pressure in the upper chamber drops rapidly, forming a low pressure differential around the closing member, pushing the closing member to move upward and open the valve; when disconnected, the spring force closes the pilot hole, the inlet pressure through the bypass hole quickly into the upper chamber to form a low pressure differential around the closing member, pushing the closing member to move downward and close the valve. 

Features: the upper limit of the fluid pressure range is high, but must meet the fluid pressure differential conditions.

Fourth, the solenoid valve open and closed state

Commonly used solenoid valve is mostly diaphragm valve, its working principle is: the valve body is divided into two chambers, the middle for the diaphragm, under the same conditions of water pressure, due to the diaphragm up and down the force area is different and the pressure difference, to cut off the flow of water.

Burner solenoid valve open state: when the remote controller to give an electrical signal or manually rotate the solenoid head, drainage channel open, the upper diaphragm chamber water discharge, indoor pressure decreases, the pressure acting on the upper diaphragm becomes smaller, under the action of upstream pressure to push the diaphragm upward movement, open the pipeline channel.

Solenoid valve closed state: manually close or disconnect the solenoid head electrical signal, so that the drainage channel is closed, the upper diaphragm chamber slowly filled with water, wait until the diaphragm up and down the same pressure, due to the diaphragm on the upper side of the force area is larger, so that the diaphragm downward movement, close the pipeline channel.