Questions&Answers

The burner is an important part of asphalt mixer, its normal operation directly determines whether the aggregate temperature can meet the requirements of production. Because there are many factors that cause burners to fail, when they fail, the fault can be quickly removed according to its fault characteristics, so that the asphalt mixer to resume production as soon as possible.

The common faults of asphalt mixer burners can be analyzed from four parts, namely oil part, gas part, wind part and circuit part. Different faults have different characteristics. According to the composition and working principle of burners, the faults are judged and analyzed.

(1) Gas and circuit problems

Whether the gas can be ignited, in addition to the normal work of the gas circuit itself, the normal work of the circuit, is also a necessary condition for the ignition. When the burner started to ignite, the gas was not ignited, which caused the HONEYWELL combustion controller to automatically cut off the operation program and the blower to stop running. Gas is not ignited, which is a common fault in the ignition process of the burner.

The first is the gas path. When the pressure in the gas cylinder is lower than 0.3bar and the pressure is too low to ignite under the normal combustion air, then a gas cylinder with appropriate pressure should be replaced. The second is that the solenoid valve of the gas is not opened, and the ignition electrode cannot ignite the gas at all. So should check the solenoid valve itself and the cause of the line.

There are three kinds of circuit problems. The first one is that the ignition electrode is not successful. The reason is that the ignition electrode is damaged or the ignition electrode has too much carbon, which causes a short circuit during the ignition. In this case, it is necessary to clean up the accumulation of carbon, or replace the damaged electrode. The second is the fault of the ignition transformer line. The reason is that the ignition transformer is damaged, or the 220V control line provided to the ignition transformer is faulty, and the normal input voltage cannot be provided. The solution is to find the electrical components and wiring for the control circuit, or to replace the ignition transformer. The third reason is that the flame detector does not detect the flame, the reason is that there is too much dust, blocking the flame detector, or the flame detector is damaged. The solution is to dust or replace the flame detectors frequently.

(2) The wind route

When the burner is ready, the blower doesn't start properly. There are two reasons for this. First, there is a problem with the motor protection switch of the blower, and the thermal relay cuts off the line, resulting in no voltage input to the blower. In this case, the motor protection switch should be checked, restarted or replaced. In another case, the servo motor is not in the low flame position and the blower cannot be started. At this time should check the air - oil ratio of the CAM mechanism, or reset the lowest position. After the burner is lit, sometimes the flame goes out unexpectedly, one of the reasons is excessive or insufficient combustion air, then should adjust the fan node door.

Since the swirl burner ignites the coal powder by absorbing the surrounding hot flue gas and has little relationship with the surrounding burners, the swirl burner can be tested on a single burner and individually optimized and adjusted. During the operation of the cyclone burner, the central return flow, the range of the air flow and the diffusion Angle of the air flow are mainly regulated.

Volute swirl burners are generally regulated by adjusting the tongue baffle at the inlet of the burner. The length and width of the central backflow area of the rotary jet increase with the increase of cyclone intensity. The range of the rotary jet decreases with the increase of cyclone intensity. The diffusion Angle of the rotating jet increases with the increase of cyclone intensity. Therefore, in operation adjustment, the diffusion Angle, range and reflux zone should be considered comprehensively. According to the corresponding type of coal, the cyclone strength can be properly adjusted. When the load is low or the ash content of coal quality difference is large, the axial baffle can be properly turned off to obtain a larger cyclone strength and improve the fire condition of the burner. When the load is high or the coal quality reaches the design standard, the large axial baffle can be properly opened to avoid coking.

The double volute burner itself has some disadvantages: (1) the airflow rotation intensity attenuation is very fast, the later mixing of coal powder and air is poor; Large secondary wind resistance; (3) Poor adaptability of coal; At the outlet section of the burner, the distribution of coal powder in the primary air flow is not uniform; (5) Grinding through casing in the first wind and powder leakage cause the jet flow of the burner outlet to be destroyed, and the axial baffle of the secondary air to fall off or get stuck, resulting in the difficulty in adjusting the secondary air; Part of the secondary air outlet of the burner is deformed due to the fall off of the upper and lower edge castable, its vertical diameter is larger than the horizontal diameter, the shape of the nozzle is changed from circular to elliptic, the exit cross-sectional area is increased, the secondary air cyclone intensity is weakened, making the shape of the flame change, causing combustion instability.

Therefore, it is necessary for the burner to maintain an appropriate first, second, and third air outlet speed to establish a normal aerodynamic field and stable combustion in the furnace. In order to improve the fire condition of the burner reasonably, it is more important than the coordination of the primary and secondary winds. In the past, due to the static pressure monitoring of primary air pressure, the primary air baffle was in full open position most of the time to prevent pipe blocking. After the DCS system modification of the unit is completed, due to the installation of an online monitoring device for wind powder, the operator's monitoring of the primary air duct is completed by changing the original wind pressure to wind speed, wind powder concentration and wind powder temperature. In this way, the wind speed of primary air duct can be adjusted quantitatively. If the wind speed of primary air duct is too high, the fire will be delayed; if the wind speed is too low, the burner will be easily burned and pulverized coal will be deposited in the primary air duct.

In addition to adjusting the primary wind, the secondary wind must also be adjusted. Since there is a big difference in the measured secondary air velocity, the secondary air volume can only be changed by changing the secondary damper opening. When the load is low or the coal quality is poor, turn down the secondary damper, on the one hand, it can improve the cyclone strength, on the other hand, it can ensure that the oxygen meets the requirements; When the load is high or the coal quality is good, open the secondary air damper, which is consistent with improving the combustion, reducing the fly ash fuel, and ensuring the main steam parameters. In addition, in the field practice, the influence on combustion should be considered due to the large change of coal quality, the destruction of jet flow at the outlet of the burner due to the grinding and leaking of powder through casing in the primary air, and the falling off or jamming of axial baffle in the secondary air.

1. Definition and principle of low nitrogen burners

Low nitrogen burner refers to the burner in the design of low nitrogen combustion technology, so that the air and fuel in a certain way of classification, mixed combustion, fuel combustion process NOx emissions are low. Using a low NOx burner can reduce NOx emissions during combustion. There are many factors affecting NOx generation, the main factors are combustion temperature, fuel concentration, oxygen concentration, shorten the residence time of flue gas in the high temperature zone. The essence of low NOx combustion technology is to reduce the maximum combustion temperature and control the concentration of fuel or oxygen in the combustion zone to destroy the optimal conditions for NOx generation to reduce the production of NO. For gas-fired boilers, it is important to control the temperature and time of the combustion process to reduce nox production.

2. Flue gas recycling technology

Is to extract part of the lower temperature of the flue gas and combustion air mixed, through the burner into the furnace, so as to reduce the combustion temperature and oxygen concentration, effectively reduce NOx production of a combustion technology. Flue gas recirculation control method of a flue gas recycling recycling of smoke gas through import frequency conversion fan control panel to adjust, PLC by signal control damper, by recycling the smoke gas and combustion load setting optimal combustion curve, automatic control, according to automatically adjust the flue gas under different working conditions, management operation of scrap, to meet the boiler NOx concentration control under different load in a reasonable range. Flue gas recirculation rate of gas-fired boilers is generally controlled at 10-20%.

3. Operation and maintenance requirements

Due to the replacement of the burner and the addition of recirculation fan, flue duct and flue gas/air mixer, higher requirements are put forward for the environment of the boiler room. It is necessary to regularly check the gas leakage detection probe and carry out the leakage alarm linkage test to ensure that the monitoring of the probe is accurate and the ventilation system linkage is reliable. In the process of operation, it is necessary to strengthen the inspection of equipment, flue, air duct and adjusting baffle, so as to avoid the phenomenon that the baffle switch is not flexible and the action is not accurate; Regularly replace or change the filter element and other components; Regularly check the drainage situation at the inlet, flue and air duct drainage points of the blower to avoid vibration or corrosion of the smoke duct; Regularly check and maintain boiler flue gas emission monitoring system to ensure the accuracy and reliability of test data. The operation analysis of boiler outlet pressure, water supply temperature, smoke temperature at furnace outlet, oxygen content, smoke exhaust temperature and main operation parameters of the transition is carried out. The abnormal situation is reported and measures are taken to ensure the safe operation of the boiler. After stopping the boiler, the anti-wear, anti-corrosion and water accumulation of the heating surface, burner, smoke duct and other parts should be inspected.

4. Risk control

When the boiler is running under low load, the nox emission concentration cannot reach below 30mg/Nm3; Incorrect setting time of FGR will result in shutout, which is extremely difficult for on-site staff to operate, and it is not easy to find the optimal ratio of recirculating smoke and air volume, resulting in difficulties in debugging. At the same time the flue gas and the cold air contact mix to produce more condensed water. The boiler flue gas flow increases, the flue gas flow field changes greatly, and the possibility of boiler flue vibration exists. For the transformation of the boiler, whether using low nitrogen burners or flue gas recirculation technology or combination technology, is to reduce the furnace combustion temperature, resulting in the reduction of radiation heat transfer, flue gas flow in the tail increased, convection heat transfer increased, the overall efficiency of the boiler has the possibility of reducing.

Mechanism of nitrogen oxide production

Nitrogen oxide (NOx) is a compound composed of nitrogen and oxygen elements, the most important of which are NO and NO2. Nitrogen oxides also occur in small amounts in nature, but most of them come from transportation and energy production. In the combustion process, nitrogen oxides can be divided into three categories according to their causes:

1.Thermal NOx: NOx is formed by the oxidation of nitrogen in the air at high temperature during combustion.

2.Rapid NOx: NOx is produced by the reaction between nitrogen in the air and hydrocarbon ions in the fuel during combustion.

3.Fuel NOx: NOx is produced by the thermal decomposition of nitrogen oxides in fuel during combustion.

Common management plan

Low nitrogen emission targets are achieved through technical schemes such as boiler replacement, combustion equipment modification or terminal treatment. There are mainly the following several common governance schemes:

1.Boiler replacement is a technical means to replace the boiler body. The key is to control the initial emission concentration of NOx from boiler flue gas to meet the requirements of low nitrogen emission.

2.The modification of combustion equipment is a pollution prevention technology in the combustion process, which is to meet the requirements of low nitrogen emission by changing low-nitrogen burners or implementing flue gas recycling transformation and other measures. At present, flue gas recycling is the most mature and most widely used. Among them, flue gas internal circulation (FIR) is introduced into the combustion area by means of jet flow in the furnace chamber, and flue gas external circulation (FGR) is introduced into the combustive air or gas, and the flue gas external circulation (FGR) is most widely used.

3.NOx terminal treatment is a post-combustion pollution treatment technology, which refers to the supplementary measures taken when the emission requirements cannot be met only by relying on low nitrogen transformation. Its technical methods mainly include: selective non-catalytic reduction denitration (SNCR), selective catalytic reduction denitration (SCR), snCR-SCR combined denitration, etc..

Introduction of qualification standards for low-nitrogen transformation

1. Environmental testing standards

The reformed gas boiler should meet the requirements of safety performance, low nitrogen emission and energy efficiency under the condition of full combustion. The boiler can operate safely and stably under the condition of full combustion. The NOx emission concentration is stable below 50mg/m3, and other pollutants meet the requirements of GB13223 and GB13271. In addition to environmental protection indicators, the CO emission concentration should be lower than 95mg/m3. Newly built or completely replaced boilers are encouraged to stabilize NOx emission concentration below 30mg/m3.

2. Energy efficiency testing standards

The thermal efficiency of the boiler after low-nitrogen transformation conforms to the regulations of DB33/800 "Boiler Operation Energy Efficiency Limit and Monitoring Technical Requirements", and the energy test method is as follows: Industrial boilers are executed according to GB/T 10180-2017 "Industrial Boilers Thermal Performance Test Rules", and power station boilers are executed according to GB/T 10184-2015 "Power Station Boilers Performance Test Rules".

Low nitrogen modification inspection and detection

The inspection and testing of low nitrogen reformation should meet the requirements of laws, standards and relevant regulations. The following points should be paid attention to in the transformation process:

1. The modification or replacement of boiler burners shall follow the relevant construction notification procedures in accordance with the provisions on major boiler repair

2. If the burner of the gas boiler is selected by the boiler user, the user shall check whether the burner conforms to the configuration and technical requirements of the boiler manufacturing enterprise, and the boiler manufacturer shall provide the confirmation certificate.

3. Burners shall meet the requirements of safety technical specifications and standards such as Boiler Safety Technical Supervision Regulations, and oil and gas burners shall pass type tests.

4. Any modification, repair and replacement of the burner shall not reduce the safety performance and energy efficiency of the boiler and shall meet the requirements of environmental protection.

5. Energy efficiency and environmental testing should be conducted by a qualified institution. Energy efficiency and environmental protection data will affect each other, and should be tested at the same time to ensure that the debugging parameters are consistent with the normal state of use

6. After the low-nitrogen transformation is completed, the boiler user shall apply for the external inspection of the boiler.

To reduce nox emissions, gas burners adopting diffusion combustion generally adopt such low nitrogen technologies as fractional combustion, flue gas recirculation, positive and negative oxygen combustion. In order to realize the low nitrogen combustion technology above, structure design should be adopted to improve the flow velocity of gas jet and air jet, so as to strengthen the mixture of gas and air. Meanwhile, cyclone design should be adopted to increase the turbulence level of flame and improve the stability of flame.

1. on the effect of the steady flame

Flame stabilization is achieved by two methods. One of them is called hydromechanics method. By reducing the axial flow velocity of fuel and combustion air in the burner, the mixture will not leave the burning area too quickly, which will lead to defiring. The second method, called chemical kinetics, is to form a persistent ignition source at the root of the flame that can ignite the gas at the temperature, such as the flame reflux zone, so that the flame can continue to burn. These two methods are often used in combination.

2. Influence on air flow stability

Low nitrogen burners have strict requirements on the air-fuel ratio, especially the design scheme using positive and negative oxygen combustion technology. The air-fuel ratio in different combustion zones with different concentrations directly affects the production of nitrogen oxides.

3. Influence on fast mixing

Turbulent free efflux can continuously suck in surrounding gases, making them mix quickly. To evaluate the mixing efficiency of turbulent free jet, the ratio of the total mass flow rate of the jet after a certain point on the jet path to the mass flow rate of the jet outlet can be used to represent, that is, the ratio of the mass flow rate of the jet outlet.

4. Influence on the production of nitrogen oxides

Diffused low nitrogen burners are generally combined with flue gas recirculation technology, in which part of the flue gas is redirected back to the burner through the external circulation pipeline for dilution of combustible mixture and inhibition of nitrogen oxide formation. With the increase of the relative opening of the flue gas external circulation valve, more and more backflow flue gas is introduced and less nitrogen oxide is produced.

First, the harm of nitrogen oxide

NOx is one of the main sources of air pollution. With the increasing use of gas-fired hot water boilers in recent years, NOx emissions are increasing, our country is facing serious NOx pollution. These NOx harms are mainly in the following aspects:

1.NOx produces aerosol particles through photochemical reaction (London fog), which is toxic to people and harmful to health.

2.NOx is one of the gases that cause the greenhouse effect.

3.After NOx is discharged into the atmosphere, HNO2 and HNO3 are formed when water meets them, forming acid rain.

4.NOx causes O3 decomposition and ozone layer is greatly damaged.

5.NOx and hydrocarbons form photochemical smog.

As nox emissions come from a wide range of sources, only by implementing energy conservation policies and emission control at the same time, on the one hand, implementing clean energy policies and on the other hand, strengthening nox emission control in key areas such as power plants, industry and transportation, can the national NOX emission level be effectively reduced. In this context, the country is becoming more and more strict in NOx emission control. Heating period gas boiler NOx emissions accounted for about 20% of the total NOx emissions, so control of gas boiler NOx emissions is very important. At present, the state has higher requirements on the emission of gas boilers, and the NOx emission standard will be increased. In Tianjin, the upper limit of NOx emission has been reduced from 80 mg /m3 to 30 mg /m3, and all gas-fired boilers that do not meet emission requirements will be transformed.

Second, replace the low nitrogen burner

The boiler furnace structure is unchanged, remove the original burner of the boiler and replace it with a new low nitrogen burner. The new low nitrogen burners adopt fractional combustion, which can reduce NOx emission. According to the need to adjust the burner and boiler butt installation plate, replace the gas pipeline valve group, etc. Remove the original burner control cabinet and related connection cables, install the new burner control cabinet and rearrange the cables. Maintain the original boiler control system and safety chain. The new low nitrogen burners adopt full electronic proportional control to achieve more accurate atmosphere ratio and more efficient combustion, reducing NOx emission and saving fuel cost.

Third, add FGR system

To further reduce NOx emissions from flue gas, the FGR system (flue gas recirculation system) was added on the basis of replacing the burner. Principle of flue gas recirculation system: mix 15% ~ 20% of boiler exhaust smoke with outdoor air and send it into the furnace. Because the flue gas heat absorption and dilution of oxygen, so that the combustion rate and the temperature in the furnace to reduce, resulting in the reduction of thermal NOx, can be reduced by up to 30% ~ 70%. The FGR pipe is arranged in an appropriate position at the smoke outlet of the boiler. The diameter of the pipe is 350 mm and the heat preservation treatment is carried out. A mixing box is installed at the suction entrance of the blower to fully mix the flue gas with outdoor fresh air and send it to the boiler after mixing.

Furnace coking is a common combustion anomaly in coal-fired boilers. Due to the heat-absorbing effect of water cooling wall, the flue gas temperature decreases gradually outward along the furnace center. When coal ash particles meet the heating surface, they suddenly freeze and stick to the heating surface, forming coking. The coking of boiler has a great influence on the safe and economic operation of boiler, and the most common one is water wall coking. The coking problem of water wall of boiler can be solved by modification of low nitrogen burner.

In view of China's current energy policy and the status quo of the coal market, in order to reduce the cost of power generation, most of the coal purchased by power generation enterprises are of low quality and inferior quality. Moreover, the coal quality varies in a wide range, and the actual burning coal is far from the designed coal, which makes the coking accidents happen frequently in the furnace.

When the boiler is coking in a large area, if the combustion condition changes, the coke block will fall off from the heating surface. Large area of coke will cause combustion instability, furnace pressure fluctuation, and even furnace fire extinguishing. In addition, under the action of high-temperature flue gas, a series of complex chemical reactions will occur between the coke slag adhering to the water-cooled wall and the pipe wall, forming high-temperature corrosion and increasing the occurrence of pipe explosion accidents of water-cooled wall.

Analysis of the influencing factors of coking

1.1Smoke atmosphere

The flue gas atmosphere, namely the oxidizing and reducing atmosphere in the furnace, is another important factor affecting the coking in the furnace. If the flue gas oxygen content in the furnace outlet is low when the boiler is in operation, the reducing atmosphere in the furnace is strong, the ash melting point will be reduced, and the water wall of the boiler is more prone to coking. This is mainly related to the form of iron in fly ash. Therefore, in reducing atmosphere, the furnace is easier to coking, when the content of iron in fly ash increases, the influence of flue gas atmosphere on ash melting point is more obvious.

1.2 Aerodynamic field in furnace

The water wall coking is easily caused by the unsatisfactory aerodynamic field, the deviation of burner jet Angle from the design value, the deviation of furnace flame center, flame sticking to the wall and the larger diameter of tangential circle. If the tangential diameter of the furnace chamber is larger than a certain value, the coking degree of the water-cooling wall will be intensified with the increase of tangential diameter, which is caused by the large number of semi-molten and molten particles will directly wash the water-cooling wall and adhere to the water-cooling wall. In addition, if the air distribution is not reasonable, coal powder and air gas cannot be well mixed in the furnace, resulting in incomplete combustion of coal powder in the furnace and water cooling wall coking [8-9].

1.3 Temperature field

The temperature field is one of the most important factors affecting the coking in the furnace. The research and analysis show that the degree of coking in the furnace increases exponentially with the increase of temperature in the furnace. When the temperature in the furnace is at a low level, the probability of coal particles softening or melting is very small, and coking is not easy to occur. If the temperature level in the furnace is high, but the temperature near the water cooling wall is relatively low, the coal ash particles have been well cooled before hitting the water cooling wall, and the probability of sticking to the water cooling wall will also decrease due to the decrease of their own temperature.

Analysis of the influence of the modification of low nitrogen burners on coking characteristics

2.1 Aerodynamic field in furnace

After the transformation of the low-nitrogen burner, no organized air leakage in the main combustion area was controlled. The primary air burner was replaced with a horizontal concentration-light separation pulverized coal burner on the opposite mound body, so that the primary air flow carrying coal powder was divided into two streams of air flow into the furnace chamber at a concentration-light ratio of 8:2. Thus, a layer of air film is formed between the primary air and the water cooling wall, forming a typical combustion form of "wind cladding powder", improving the oxidizing atmosphere in the water cooling wall area, so as to realize the purpose of restraining coking in the furnace.

2.2temperature field

The modification of low-nitrogen burner adjusted the air distribution mode and adopted the low-nitrogen combustion technology of air classification. The excess coefficient of air in the main burning area was kept at about 0.85, forming the under-oxygen combustion, making the temperature of the main burning area lower than before the modification, thus reducing the proportion of molten or softened coal ash. "Wind bag powder" form of combustion can be in a form a layer of air film between wind and water wall, making it nearly wall inside certain limits of temperature gradient is relatively flat, causing half melting, molten particles collide with the wall before fully cooling solidification, reduce its own temperature, adherence to the possibility of water-cooled wall decreases. It can be seen that the influence of low-nitrogen burner modification on the temperature field in the furnace is beneficial to prevent the water wall coking of the boiler.

The gas regulator is an important component installed between the boiler air source and the burner. Its function is to adjust the higher pressure and unstable air source to the smaller and relatively stable air source, and to provide the burner with appropriate energy.

Performance of gas regulator

1. The internal spring of the regulator can balance the fluctuation of inlet pressure and keep the stability of outlet pressure;

2. There are pressure measuring point interfaces on both sides of the inlet and outlet of the voltage regulator;

3. Accuracy of set point: the error is ±5% of the set value of outlet pressure

Regulation of voltage regulator

1. Remove the sealing screw of the outlet side pressure measurement interface of the voltage regulator;

2. Connect the pressure detection equipment to the pressure measurement interface;

3. Turn off the cap of the voltage regulator counterclockwise;

4. Outlet pressure is achieved by adjusting the setting screw. Turn the setting screw clockwise, the outlet side pressure will increase; The opposite is true. Pressure detection equipment can display outlet side pressure;

5. When adjusting the voltage regulator, the outlet pressure must be adjusted from small to large slowly, not too hard;

6. Record the outlet pressure setting value of the regulator;

7. Reinstall the top cover of the voltage regulator;

8. Remove the pressure detection equipment and restore the sealing screw.

Replace the regulating spring

1. Remove the top cover of the voltage regulator;

2. Unscrew the setting screw counterclockwise;

3. Take out the old or inappropriate spring and replace it with a new or suitable spring;

4. Reinstall the setting screw and set the outlet pressure according to the voltage regulator adjustment method.

The burner pressure regulating valve is an important component installed between the boiler air source and the burner. Its function is to adjust the higher pressure and unstable air source to the smaller and relatively stable air source, and to provide the burner with appropriate energy. Therefore, it is necessary to maintain the burner pressure regulating valve.

1.Replace the diaphragm of pneumatic actuator. The diaphragm of pneumatic thin film actuator is stretched during operation, so it is easy to suffer fatigue damage. The rubber diaphragm of the same specification shall be used for replacement, and the diaphragm shall be evenly stressed when fixed to prevent leakage and damage of the diaphragm.

2.Grinding. The spool and valve seat will cause leakage after running for a certain time, and the piston between the cylinder block will also cause internal leakage, at this time should be ground. Can be hand grinding, mechanical grinding, coating treatment and sleeve, grinding emery particle size should be appropriate, grinding force should be uniform and appropriate. After grinding, it shall be polished to meet the required smoothness and accuracy requirements, to meet the valve core and seat in the middle requirements, etc., and shall be tested for tightness after the final assembly.

3.the stuffing box replacement. Stuffing box of the same type shall be used for replacement. It shall be carefully checked out and properly removed to prevent damage to the valve stem. The new stuffing box shall be installed in accordance with the instructions, the notches shall be misaligned to prevent stem threads from scraping the packing, the packing shall be compressed evenly and properly to prevent stress and increase friction.

4.Replacement of transmission parts. Control valve and accessories in the transmission parts if part of the wear can be replaced, repair parts. After replacement and repair should ensure that the transmission flexibility, transmission clearance as small as possible.

5.Cleaning of pneumatic amplifier. When the throttle hole of pneumatic amplifier is blocked by dirt in the compressed air, the throttle hole should be cleaned. Suitable steel wire can be used for dredging and cleaning. The diaphragm of the amplifier shall be under uniform force during reloading to prevent blockage or leakage. The gain of the amplifier can be adjusted by adjusting the pressing force of the steel ball to prevent resonance.

Fuel oil is also called heavy oil, residue oil, for black brown viscous combustible liquid, viscosity moderate, good fuel performance, high calorific value. Used for boiler fuel, good atomization, complete fuel, less carbon and ash, less corrosion. Higher flash point, safer storage and use.

Fuel oil is a kind of refined oil produced from crude oil, which is widely used in Marine boiler fuel, heating furnace fuel, metallurgical furnace and other industrial furnace fuel. Fuel oil is mainly made of petroleum cracking residuum oil and straight running residuum oil, characterized by high viscosity, non-hydrocarbon compounds, gelatinous, asphaltene. The main technical indexes of fuel oil are viscosity, sulfur content, flash point, water, ash, and mechanical impurities.

1.Viscosity: Viscosity is the most important performance index of fuel oil and the main basis for grading fuel oil. It is a measure of fluidity resistance, and its size indicates the fluidity, pumpability and atomization of fuel oil. At present, the domestic more commonly used is 40℃ kinematic viscosity (distillate fuel oil) and 100℃ kinematic viscosity (residual fuel oil). In the past, the standard of fuel oil industry in China used Engler viscosity (80℃, 100℃) as the quality control index, and the grade was divided by 80℃ kinematic viscosity. Kinematic viscosity of oil is the ratio of dynamic viscosity to density of oil. The unit of kinematic viscosity is Stokes, or Stokes for short. The dynamic viscosity is 1 Stokes when the fluid has a dynamic viscosity of 1 berth and a density of 1g/cm3. CST is short for Centistockes, meaning one hundredth of a Stokes.

2.Sulfur content. Excessive sulfur content in fuel oil can cause corrosion of metal equipment and environmental pollution. According to the sulfur content, fuel oil can be divided into high sulfur, medium sulfur and low sulfur fuel oil.

3.Flash point. Is concerned with the use of safety indicators, too low flash point will bring fire hazards.

4.Moisture. The presence of water will affect the freezing point of fuel oil, which will rise gradually with the increase of water content. In addition, water will also affect the combustion performance of fuel oil machinery, may cause the furnace fire, stop the furnace and other accidents.

5.Ash content. Ash content is the remaining part that cannot be burned after combustion, especially when FCC circulating oil and slurry are added to fuel oil, silica and aluminum catalyst powder will accelerate the wear of pump and valve. In addition, ash will also cover the boiler heating surface, so that the heat transfer becomes bad.

6.Mechanical impurities. Mechanical impurities can clog the filter screen, causing wear on the pump and blockage of the nozzle, affecting the normal combustion.

For most of the burner on the market, more use of the automatic control system, components, once the equipment failure, not the first time in a timely manner, to repair and eliminate temperature will result in system failure, the impact to the crude oil processing, such as the quality of the products, especially in the cold winter could lead to serious consequences on the production system, so should be developed for automatic burner system failure manual emergency disposal measures.

1.When the automatic control system fails, close the globe valve in the flow of the automatic control system, cut off the air source of the automatic control, open the manual globe valve, and manually control the flame size and temperature.

2.When can't ignition point, two of the control system shall be globe valve closed, and then take a burning stick and ribbons for firing, dip in after take a small amount of flammable fuel ignites, will lead a burning stick from observation hole deep in the burner, the guarantee lead out a burning stick a spray hole front-end, the manual control valve slightly open (1/3 to 2/3 opening), lit the fire, take off a burning stick, then slowly open the automatic control system of cut-off valve, manual ignition end.

3.In the control system with frequent power loss, the loss of power will lead to the fire extinguishing of the heating furnace. In order to prevent the fire extinguishing of the heating furnace caused by frequent accidental power loss, the manual stop valve can be left with a little opening after the automatic control to ensure that a little gas can pass through. In addition, due to the fuel gas water content with the seasons change, the adjustment of production parameters will be needed for combustion heating furnace gas change occurs, the burner for the first time after installation and debugging, post staff can according to the change of running status of heat furnace with timely adjust the volume, cause the waste of fuel or burner overworked, the increase of energy consumption, increasing, operation cost and equipment failure rate, the operation of the heating furnace thermal efficiency drops, these are to disposal scheme to deal with them.