Questions&Answers

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.

Burner control valve plays an important role in the regulation of the burner, fuel flow, pressure, temperature and other parameters can not be regulated without the participation of the control valve, so the need for regular inspection of the burner control valve.

1.Stress relief.

Various stresses due to improper installation or combination. For example, high temperature media produce thermal stress and tight installation. Unbalance of solid force causes stress and so on. The imbalance of stress on the control valve, so that the control valve stem, guide parts deformation, can not be correct and the seat in the middle of the leakage, increase in variation. Therefore, stress relief should be carried out in daily maintenance.

2.Remove rust and dirt.

Check regularly whether there is rust, welding slag, dirt and so on in the connecting pipe of the regulating valve, and remove it in time when found. Because these dirt will cause the valve core and seat wear, affect the normal operation of the valve. Usually, can be installed in front of the regulator filter screen and other filtering devices, and regular cleaning.

3.Check the support of regulating valve.

The support of the regulating valve enables the parts of the regulating valve to be in a position free from the influence of gravity, etc. Improper support will cause the valve stem and seat can not be aligned, so that the difference increased, sealing performance decreased. Therefore, check whether the regulator support is appropriate.

4.Clean up the air source, hydraulic oil and other energy supply dirt.

Air source and hydraulic source are the energy source of regulating valve operation. Impurities contained in the compressed air and hydraulic fluid used in the instrument can clog the throttling holes and pipes, causing faults. Therefore, it is very important to check the air source and hydraulic oil regularly and carry out sewage treatment regularly to the filter unit.

5.Inspection of gear transmission.

The gear transmission of the hand wheel mechanism, electric actuators and hydraulic actuators should be checked regularly and lubricants should be added to prevent the occurrence of biting and jamming. Check that brake and limit devices are in good working order.

6.Stuffing box inspection.

The packing shall be inspected for wear and compression force, and the stuffing box shall be replaced regularly to ensure that the packing can seal while reducing the friction of the hole. Do not add lubricating oil to the grease-free stuffing box.

7.Check the safe operation.

The safe operation of the regulator and related accessories used in explosive dangerous places should be checked, for example, whether the sealing cap is tightened, the operation of the safety grid, the supply of power, etc., to ensure the safe operation of the regulator and related accessories.

8.Transportation and storage.

During transportation and storage, the regulating valve shall be fixed with special support to prevent looseness; The relevant accessories installed on the control valve, such as valve positioner, handwheel mechanism, etc., should be firm, should prevent the feedback rod connected with the control valve and other components from being damaged by external forces; Each connection interface shall be sealed with plastic film to prevent the invasion of external objects; The connecting mouth of the regulating valve can be sealed with matching flange and blind plate, or can be sealed with adhesive paper to prevent invasion of external materials. During transportation, solid wooden boxes should be installed and be protected against wind, sand, rain, dust and other adverse transportation environmental conditions. The environmental conditions for transportation and storage shall meet the requirements of the product specification.

The main structural components of the burner fan are impeller, casing, air inlet, bracket, motor, pulley, coupling, silencer, transmission parts (bearings) and so on. Improper installation and improper maintenance can potentially shorten the service life of the burner fan.

Common faults:

1. Wear of transmission parts

Transmission parts wear is a common problem of fans, including various shaft, roller, reducer, motor, pump and other bearing position, bearing seat, keyway and thread, etc. Traditional repair welding machining method is easy to cause material damage, leading to component deformation or fracture, which has great limitations. Brush plating and spraying remachining methods often need external assistance, not only the repair cycle is long, the cost is high, and because of the repair material or metal material, can not fundamentally solve the cause of wear (metal impact resistance and degradation is poor); Moreover, many parts can only be scrapped and replaced, which greatly increases the production cost and inventory spare parts, making the good resource advantage of enterprises idle and wasted.

2. Vibration fault

The fan and motor are connected by a coupling to transmit motion and torque. Misalignment is the most common fault of the fan, and 60% of the fault of the fan is related to misalignment. The fault of the fan refers to the tilt or deviation degree of the axis line and bearing center line of the rotor of the fan and motor. The misalignment of the fan rotor can be divided into coupling misalignment and bearing misalignment. Of the fan rotor system fault, in the rotation process will produce a series of the dynamic effect of adverse to the equipment operation, cause coupling of deflection and bearing wear, the oil film of steady state and axis deflection, etc., not only make the rotor shaft and bearing position and bearing working condition changed, at the same time reduce the natural frequency of the axis, the rotor bearing and the bearing of the additional force lead to abnormal vibration of the fan and bearing early damage, damage is great. For the fan misalignment fault, you can use the laser alignment instrument to solve, convenient and fast.

Cause analysis,

1. Installation reasons:

Improper installation of machinery, parts dislocation, large pre-load

Poor alignment of shafting

The geometrical parameters of the machine (such as fit clearance, interference and relative position) are improperly adjusted

The dynamic characteristics and installation precision of the machine are changed when the pipeline is under great stress

The rotor is placed improperly for a long time, which changes the dynamic balance precision

Not in accordance with the rules of maintenance, damage the original machine with the nature and precision

2. Improper operation:

Process parameters (such as medium temperature, pressure, flow, load, etc.) deviate from the design value, and the machine runs under abnormal conditions

The operation of the machine under overspeed and overload has changed its working characteristics

The operating point approaches or falls into the critical speed zone

Poor lubrication or cooling

Partial damage or scaling of rotor

Improper operation in the start-stop or lift-speed process, insufficient warm-up, uneven thermal expansion or too long stay in the critical area

3. Equipment degradation:

In the long run, the deflection of the rotor increases or the dynamic balance deteriorates

Partial damage, shedding or cracking of the rotor

Wear, pitting, or corrosion of parts

The bearing surface degrades, resulting in interference deficiency or looseness, which destroys the mating properties and precision

The settlement of the foundation of the machine is uneven, and the shell of the machine is deformed

In heating, electricity, steel, cement, paper making industries fan equipment is used in great quantities, for conveying gas medium contains a lot of hard particles and acid gases, over-current components of the equipment, strong erosion, especially the heart components impeller, at the end of the blade line speed up to 160 meters per second, wear speed is more severe than elsewhere.

According to statistics, the impeller made of ordinary carbon steel or general wear resistant steel 16Mn has a general service life of only half a year, the shortest is only a few dozen days, although the use of various surface anti-wear measures such as surfacing, spraying, spray welding, coating polymer wear resistant materials, it is difficult to significantly improve the service life. In the more commonly used methods, surfacing is used more, the effect is good, can generally use more than a year without the need for large area repair. Its disadvantage is due to the input of a lot of heat, if the control is not good, will lead to impeller deformation, and can not be used repeatedly repair. Thermal spray welding has the same problem, which greatly limits their application.

The use environment should always be kept tidy, the surface of the fan should be kept clean, and there should be no debris in the inlet and outlet. Regularly remove dust and other sundries in the fan and tube.

At the same time, the power supply facilities should be maintained with sufficient capacity and stable voltage. It is strictly prohibited to run out of phase. The power supply line must be a special line instead of a temporary line for a long time.

If the fan is found to have abnormal sound, serious heat of motor, live shell, switch tripping and failure to start during operation, the fan shall stop immediately for inspection. In order to ensure safety, maintenance during fan operation is not allowed. After maintenance, the machine should be tested for about five minutes, and no abnormal phenomena should be confirmed before starting the machine.

According to use environmental conditions do not regularly to supplement or replace the bearing lubrication oil (motor closed bearing need not be replaced during the service life of the lubricating oil), fan in the process of operation in order to guarantee good lubrication, refueling times is not less than 1000 hours/time, seal bearing and motor bearing, oil bearing with ZL - 3 lithium base grease inside and outside the circle of 2/3. Do not run out of oil.

The fan should be stored in a dry environment to prevent the motor from moisture. When the fan is stored in the open air, rain protection measures should be taken. In the process of storage and handling should prevent the fan knock against, so as not to damage the fan.

1. Before commissioning the newly installed furnace body, it shall carefully test whether the gas and pressure meet the requirements of the burner; Check whether the testing instrument on the air supply pipeline is normal and whether the valve of the pipeline is open and closed normally, and whether it is convenient for use and testing in the future.

2. For newly installed pipelines, carefully check the installation reliability and sealing of all pipelines.

3. Users using separate gasification stations should ensure that the air supply quantity and gas supply parameters meet the requirements of safe combustion.

4. Operators should read the operating instructions carefully and master the knowledge and methods of safe operation.

5. Check whether the gas valve is open before starting each time, otherwise the burner will not work (and will not alarm).

6. Start the "Run" button on the control. At this time, the digital display table will show the current temperature of water discharge, return and smoke exhaust of the furnace.

7. After the delay of the boiler controller is about 1 minute, the relay of the burner is controlled to suck in, and the burner fan works for about 45 seconds to prepurge; If the burner fan does not work and does not alarm, check whether the low gas pressure switch is protected; Check whether the outlet temperature of boiler water meets the working requirements of boiler controller temperature parameters, that is, whether the outlet water temperature is lower than the set temperature.

8. After the pre-purge of the burner, the damper is closed for ignition, the yellow light of the burner controller flashes and the ignition transformer discharges. About 2-3 seconds later, the gas solenoid valve is energized and opens.

9. When the combustion controller receives signals that are not favorable to combustion (such as failed ignition, unstable air pressure, circuit problem, etc.), the combustion controller will immediately turn off the gas and issue an alarm signal.

10. If the combustion controller alarms, it must be manually reset by the operator after the fault is solved before it can continue to work.

11. For the operation of the whole equipment, operators should refer to the furnace safety operation rules and production process requirements for operation.

12. When the control temperature needs to be adjusted according to the production process requirements, the operator should refer to the intelligent NUMERICAL control table manual for adjustment.

Burner construction repair technology of basic requirements: improvements in the chamber of a stove or furnace when not all tuyere replacement: a wind, secondary tuyere tuyere with basically three times square plates welded together, also often is the position of the defect, trim will burn out when resection, replace, replacement should strictly pay attention to the size and a tuyere, secondary tuyere, three tuyere mouth direction, shall not change the original design and installation size Numbers and shapes.

1. Remove ash and coking from water-wall pipes in the furnace and heat preservation around the burner, and make preparations before starting:

1) The four walls of the furnace that may cause personal injury and affect the maintenance and installation of ash and coking large blocks should be completely cleaned.

2) Remove all surrounding and external insulation.

3) Purge and clean all the virtual ash in the furnace and around the burner.

2. Working conditions of scaffolding in the burner platform:

1) Before the personnel enter the furnace, the person in charge of the staff or the leader of the sub-field shall measure the temperature inside the furnace. No one can enter the furnace above 40℃.

2) Scaffolds erected shall meet the working requirements of installation, measurement and maintenance of burners; To clear ash and coking in the furnace, dismantle the old burners and safety requirements of the staff during welding. At least one layer of scaffolding can ensure that the furnace center is located at the burner level and can be fixed.

3. Methods for dismantling the old burner:

Inspect the four Angle burners in the furnace. All burners to be replaced must be cleaned and removed from the site in time.

4. The steps of measuring the center point of the furnace and designing a fixed cylinder with imaginary tangential circle:

1) Measure the center of the furnace with a tape measure at the elevation around the burner in the furnace and make corresponding marks.

2) Use wiring method to draw two lines at the center point corresponding to the four corners to intersect at a point in the furnace, which is the center of the imaginary circle.

3) It is better to fix an imaginary tangential circular cylinder with radius R at the intersection and the diameter of the cylinder is about 80cm.

5. The method of drawing the jet line of the four-angle burner respectively:

1) The jet line of the burner is drawn to the center of each nozzle tangential to the imaginary cylinder and tangential to the cylinder.

2) The opposite nozzle is drawn from the center of the two nozzles and passes through the center of the hypothetical tangential cylinder.

6. Steps for installation of spot welding burner:

1) The center axis of the spot-welded burner must coincide with the jet line of the group.

2) The spot welding burner must be at the overall level or in line with the drawing size.

7. On-site operation steps of all burners to verify the Angle, measure the dimensions and weld them fully:

1) The interior of the replaced primary, secondary and tertiary air vents shall be smooth without concave-convex or welding defects.

2) The angles of the first, second and third air vents shall meet the requirements of ICONS.

3) The external secondary air baffle should be flexible and free from stuck death. The stuck baffle should be dealt with or replaced in time.

8. Dynamic field test: check the wind speed and air volume of each burner tuyere, measure and check the Angle of each nozzle, and keep heat.

9. Check and verify the damper plate at each nozzle.

10. Remove the scaffolding in the furnace.

11. Summarize the installation technical report and wait for three-level acceptance.

Direct-flow burners are usually called four-angle nozzles in boiler maintenance, and their outlet airflow is direct current jet. In this kind of direct current burner, coal powder and burning air are injected into the furnace by different nozzle with non-rotating DIRECT current jet flow. According to the flow medium is different, the burner nozzle can be divided into: a, three times of tuyere tuyere, secondary tuyere, wind is used for conveying pulverized coal heating, make the coal through a duct and enters the furnace to the burner, secondary air is high temperature wind with a wind mixing pulverized coal to meet the quantity of air required for the pulverized coal combustion, three times the wind out of the coal pulverizing system with pulverized coal into the furnace exhaust to high speed to adjust the working condition of pulverized coal combustion, considering the needs of the pulverized coal ignition and burn out, different outlets with different flow velocity, this part mainly in the operation of the adjustment.

Direct-flow burners can be arranged in a variety of ways:

1. Single-cut circular type, namely the primary air of the four-angle nozzle, and the geometric axis of the secondary air is tangent to a same-diameter circle in the center of the furnace;

2. The two angles are tangent to each other;

3. Double tangential circle layout, in which the primary and secondary air of the four corners are cut to different tangents, and the first, second and third tuyere of the four corners have different tangents;

4. Directional or six-directional tangential circles, which are used in large stoves;

     5.double furnace circular cutting layout, our power plant furnace with four Angle layout circular burner, its advantage is easy maintenance and maintenance of maintenance and operation regulation.

Common equipment defects of direct-flow burners in operation basically include the following situations:

     1, the nozzle is blocked, especially when the cease-fire nozzle is used to adjust the load, the primary air tuyere that stops operation will form a high temperature area and coking, serious coking, will make the primary air tuyere all blocked, so that the coal air jet can not go out;

2. The tuyere of primary air, secondary air and tertiary air is shape-burned and deformed. After the tuyere that stops operating forms a high temperature zone, although there is no coking, the shape of each tuyere is burned and deformed;

3. The secondary damper plate is stuck. Due to uneven thermal expansion during operation, the adjusted baffle plate is stuck in a certain position and cannot be adjusted or switched;

4. The nozzle falls off. During the operation of the burner, due to poor operation adjustment, the positive pressure of combustion makes the nozzle burn out and falls off, and damages the water-wall pipe, thus causing the boiler operation interruption and other unsafe defects.