Questions&Answers

The combined start-up technology of air duct burner oil gun and bed burner is used for the first time after the modification. In order to ensure safety, the starting parameters under this mode were explored and the adjustment mode of proper amplification of primary air volume was adopted. After fire, according to the outlet smoke temperature of the air duct burner, the temperature at the expansion joint and the inlet temperature of the primary air chamber not exceeding 900℃, 600℃, 250℃ respectively, and adjusting the opening of the manual damper on the ground and the lower layer to optimize the flame morphology, observe the fire situation to ensure good combustion. According to the pressure boost curve, the temperature rise rate should be controlled strictly, and the temperature rise rate should not exceed 100 ℃/h. According to the rising temperature of the bed, when the upper and lower bed temperatures reach 550 ℃ and 300 ℃ respectively, and have an increasing trend, according to the rising temperature of the bed, according to the order of first on the bed and then under the bed, the oil gun is returned completely.

This is the first performance exploration after the transformation of the air duct burner, the outlet temperature of the air duct burner is controlled not more than 250 ℃. After put into operation, it is important to check the expansion condition of each expansion joint of the air duct burner, especially the expansion joint of the primary air chamber. There is no obvious abnormal air leakage in the primary air chamber, and the expansion indication is normal. Through this trial operation, although the fuel consumption does not decrease significantly during the start-up process, the working performance of the air duct burner is basically explored clearly. After that, our company started the exploration process again, and constantly optimized the working area of the duct burner.

When the heat transfer material is fixed, the greater the temperature difference, the greater the heat transfer capacity and the better the effect. Under approximately the same primary air volume and bed pressure, when the bed material is heated to a similar temperature, when the outlet temperature of the controlled air duct burner does not exceed 650 ℃, the heating time is the shortest, the oil consumption is the least, and the heating effect is the best.

The air duct burner was put into operation separately for about 3 h, and then put into the bed oil gun for operation. The fuel consumption needed to reach the coal point was relatively low. Theoretically, the longer the operation time of the air duct burner, the less fuel consumption is required to reach the coal point. But the corresponding start-up time is about long, and the auxiliary engine power consumption, water consumption and so on in the start-up process will be a big expense, obviously, in order to save fuel, it is not advisable to use the method of extending the separate use time of the air duct burner. At last, the optimal mode of air duct burner is obtained by exploring and optimizing the scheme. Four air duct burners run continuously for about 3 h under optimal conditions, and then put into bed oil gun operation. When the temperature of the upper bed and the lower bed reached 550 ℃ and 300 ℃, respectively, and there was an upward trend to gradually return the oil gun.

1.Problems existing in the coal flame detection device

About combustion of inferior coal in the boiler, coal flame detection device signals appear unstable, frequent fluctuation phenomenon, cause the oil system of interlocking input steady combustion, coal mill tripping, RB action, such as unusual, especially in low load operation stage, the coal mill run less quantity, if the coal flame detection signal is not stable, exist MFT misoperation, in turn, lead to the unit not safe hidden trouble, seriously affecting the safe and stable operation of unit. Moreover, the proportion of mixing and burning of inferior coal is limited, the operation cost is increased, and the economic benefit of the unit is affected.

2.Solutions to the problems existing in the coal flame detection device

(1) The installation position of the coal flame detection device is changed from the lower part of the burner to the upper part of the burner to "eliminate" the carrier that can carry coking. The coke will automatically fall off when it reaches a certain weight. And because of the negative pressure effect of the furnace, the burner flame will tend to shift upward, which can increase the covering area of the fire detector of the coal flame detection device, maximize the detection of the burner's stable combustion zone, and obtain the best detection effect.

(2) The fiber components of the coal flame detection device are thickened and changed from the original fiber components with a diameter of 2.5mm to the fiber components with a diameter of 5mm, so as to increase the lighting area and reduce the influence of factors such as unstable and insufficient combustion caused by coal blending and combustion, and changes in the position of the burner's stable combustion area.

(3) According to the inferior coal quality mixed with coal, adjust the tilt Angle of the fire probe of the coal flame detection device, so that it can see the stable combustion zone to the maximum extent and obtain the best detection effect.

3.Implementation effect of coal flame detection device

The transformation effectively solved because of the furnace flame detection device installation control coal coking, burner and combustion instability stable-combustion area change caused by many factors such as the problem of the coal flame detection device detection signal, reduces caused by unstable coal flame detection device detection signal of micro oil system of interlocking input stable-combustion, coal mill tripping, RB action, such as abnormal situation, improve the reliability of the unit MFT main and auxiliary protection and safe operation of the unit level.

First, the main burner was transported to 0 m of the boiler using a flat transport vehicle, and the burner was lifted to the towing chute arranged on the 39.2 m of the boiler by a 300 ton truck crane. Two 5-ton chain reels will be used to transfer the burner to the pot during the towing of the burner

When the upper end of the burner reaches the bottom of the pulley group, use 60.5 mm of the wire rope four as the pulley group hoisting rope, using a 10-ton winch main crane. During hoisting, two 10-ton inverted chains are dragged to the outside of the boiler during the lifting of the burner to prevent the burner from rising too fast until the burner is completely upright. Before the burner is hoisted, another 20-ton hand hoist is equipped to adjust the levelness of the main burner. No force will be put on the chain before the 20-ton burner is hoisted. After the burner is raised, make the hand hoist bear force and adjust the burner level.

During the hoisting process, the rooting beam, pulley block, wire rope and burner must be monitored by someone and equipped with intercom to keep the communication unobstructed. In the process of vertical lifting, due to the narrow space on the upper part of the burner, a hand hoist should be hung at the lifting lug to make the burner move as far as possible between the water cooling wall and the steel structure platform during vertical lifting. During the lifting process, the commanding personnel will direct the main winch to lift, assign special personnel to monitor each dangerous position, and set up the burner smoothly. When the burner is fully upright, it should be suspended at 100mm above the ground and checked everywhere, especially the rooting area. Lifting should be allowed only when there is no problem. The lifting process should be kept slow and smooth.

Remove the 5 ton chain drag after the burner is fully upright. The conductor directs the hoist to drop the hook slowly, and in the process of falling the hook, a monitor is arranged at each floor platform and coal pipeline to monitor the burner during its descent. The Angle and position of the burner can be adjusted at any time during the lifting and descending of the burner by using a rope to prevent the burner from scraping against the surrounding steel beams and pipes.

When the equipment rises to the installation position, 2 10-ton hand hoist and pulley blocks are used to adjust the position of the burner, so that the burner is in place. Using the internal lifting platform of the sprayer, 4 10 tons and 4 5 tons hand hoist, adjust the burner to the required position.

The center line of furnace is drawn out with steel wire, and the intersection point of the two steel wires is the center point of boiler. Draw the imaginary circle on the board and nail the corresponding cutting points to fix the steel wire; The horizontal pipe is used to find the plane elevation of the board (with imaginary tangential circle), so that it is consistent with the central elevation of the nozzle, and the center of the imaginary tangential circle coincides with the central point of the boiler. Hold the plank in place. Based on the vertical end face of each layer of pulverized coal nozzles of each burner, the verticality of the burner was finally rectified by using steel ruler, line drop and hand hoist. A straight line is drawn from the center point of the corresponding nozzle to the imaginary tangent point with steel wire. Adjust the burner so that the center line of the nozzle coincides with the theoretical tangent.

After passing the adjustment and acceptance, the burner is firmly connected with the nearby steel frame. After passing the reexamination of the dimensions, the water-cooled wall is sealed and connected with each rigid beam.

(1) The burner's center is generally slightly in the cross section center of the kiln mouth. If the flame is too close to the surface of the material, part of the unburned fuel will be wrapped in the material layer without sufficient combustion to increase the heat loss, and at the same time, it is easy to grow the coal ring in the kiln. If the flame is too far away from the material surface and deviates from the lining, the flame jet will collide with the kiln skin, scour and burn the kiln skin and lining, which will cause frequent crust, ring and egg laying and other phenomena.

(2) The burner position is too low, the flame is not suitable, and the kiln skin and refractory materials are easy to be burned, and the yellow core material and F-CA0 height are generated due to the rapid burning and incomplete combustion, resulting in the aggravation of reducing atmosphere and the skin blocking of the kiln tail system. The burner position is too far up, the fire burns far away, that is, the burner is far away from the material layer and close to the kiln lining, the flame will wash the kiln skin and kiln lining, reduce the service life of the kiln lining, and it is easy to form long and thick kiln skin, the smoke chamber at the end of the kiln and the final discharge slip are easy to be skinned and blocked, which will cause the kiln high temperature belt to move back and make the material sticky. The influence is intensified when raw material saturation is low and coal ash is large.

(3) The adjustment of internal and external wind: generally increase the internal wind when the flame is short and thick. The flame is thin and long when the external wind is increased. Too large internal wind is easy to cause short and thick divergence, not only the kiln skin is easy to be burned, but also produces thick and yellow core material. When the external wind is too large, the core area of the flame is elongated, which makes the unburned coke particles sink to the back part of the kiln and continue to burn. As a result, the liquid phase of the material appears prematurely, resulting in excessively long floating kiln shell and resulting in ring formation.

(4) The distance from the end of the burner to the kiln is 100-200. The more it reaches into the kiln, the more the high temperature point moves back, and the cooling zone increases, which is equal to shortening the length of the kiln. The tail temperature increases accordingly, and the snowman building phenomenon of grate cooler decreases. The more the flame outside the kiln moves forward, the shorter the cooling belt will be. At this time, the higher the temperature of clinker outside the kiln will be, which is unfavorable to the kiln hood and iron shield.

(5) The calcined belt kiln shell should maintain a certain thickness, generally 200-300 or so long as about 18-20m. The closer the burner position is to the point (0.0), the more uniform the kiln skin.

Type thermal NOx

The generation of thermal NOx is mainly produced during combustion. Nitrogen in the combustion air is generated by oxidation under the high temperature flame. It is mainly generated in the region with a temperature higher than 1800K. Temperature, excess air coefficient and residence time in high temperature zone all affect the formation of thermal NOx. Temperature is the most important factor affecting the thermal type, and 1800K is the key temperature point for the generation of thermal NOx.

Excess air coefficient produces a double - sided effect on thermal NOx, and the actual combustion is more complex. When the excess air coefficient increases, the oxygen concentration increases, promoting the chemical reaction equilibrium movement, so that the production of NOx increases; At the same time, with the increase of excess air coefficient, the amount of gas generated also increases, reducing the combustion temperature, and thus reducing the formation rate. Therefore, the effect of excess air coefficient is more complex, which may be promoting or inhibiting, and should be analyzed according to the actual situation. Generally, the longer the reaction stays in the high temperature zone, the greater the production of NOx.

Type fast NOx

The nitrogen element in the rapidly generated NOx also comes from the air during combustion. The rapid generation is mainly due to the fact that hydrocarbons can decompose a large number of CH, CH∶ and C∶ groups during combustion, which can destroy the molecular bonds of nitrogen and decompose the CH under high temperature conditions. Free radicals react with N∶ N in the air to form HCN, NH, N. The above reaction products can react with O and OH atomic groups in the flame to form NO. Among them, HCN is the most important intermediate product for the rapid formation of NOx, which can rapidly generate NOx in the flame surface. The formation mechanism of rapid NOx is very complex and the intermediate reaction time is short.

Type fast NOx mainly is rapid response generated hydrocarbons in the fuel, the excess air coefficient, the pressure, combustion chamber of a stove or furnace zone N concentration are the main factors influencing the rapid type NOx formation, and temperature on its almost unaffected, at a certain temperature, with the excess air coefficient, NOx generation can appear larger decrease after the first peak.

Fuel type NOx

Fuel type NOx is formed by the nitrogen element contained in the fuel when the fuel is burned. Nitrogen containing organic compounds in fuel are decomposed by heat to form CN, HCN and NH. Such as intermediate products, further oxidation to NOX. The effect of temperature on the generation of fuel NOx is not obvious, mainly because the pyrolysis temperature of fuel containing nitrogen compounds is not high, about 600℃-800℃, fuel NOx can be generated.

Excess air coefficient has a great impact on the generation of fuel NOx, the conversion rate of nitrogen into NOx in the fuel increases with the increase of excess air coefficient; When the excess air coefficient a>1, the fuel NO production basically remains unchanged. When the excess air coefficient A <1, the conversion rate will drop quickly.

Gas was only used as an industrial fuel in the mid-19th century, when much of it was artificial, made by reacting air or steam with coal, coke or charcoal. The combustible components of gas are carbon monoxide and hydrogen. Because of the high content of carbon dioxide and nitrogen, the calorific value of gas is relatively low. Few devices were then called burners. Furnaces and ovens were simply equipped with several sets of air and gas openings, and the two streams of air burned together inside the furnace. The technique was still available in some recycled glass and open steel furnaces a few years ago. The flame is too large and the mixture is too slow to satisfy many combustors and lower calorific values of the gas. The furnace or fuel must be preheated or it will easily die.

Premix burners were the first purpose-designed burners, dating back more than 100 years to Benson and similar laboratory burners, and are the prototypes of today's premix industrial burners. Premixed burners consist of a head and a mixing tube, which in some cases are separate units. The mixer uses pressure to mix gas and air and sends them to the combustion nozzle, where it finds a steady point to ignite the flame and control the shape of the flame.

In the early 1920s several single-nozzle hybrid burners were commercially available. In addition, this burner and premix burner in the design of no improvement. Under the condition of high ignition rate, the flame is not easy to take off, but the fluctuation of mixing ratio is still limited, the speed of air and gas must be carefully controlled to ensure a clean and stable flame. Designers soon realized that installing flame stabilizers, such as whirlpool blades, discs, or protrusions at gas and air outlets to assist the mixing process would help extend the range of ignition and mixing ratio. For extended flames, these stabilizers also generate some safety points from self stabilization, which greatly improves the burner's stability. Over time, more sophisticated stabilizers were designed and the burner's characteristic curve was extended.

Hot boiler automatic control system with schneider PLC as the core, the valve, ignition control cabinet, fire detection, cooling fan control cabinet, process instrumentation, etc have been accused of equipment information layer, control layer and upper layer of three-tier architecture, PC and PLC adopts Ethernet communication, implementation process monitoring of field devices, dynamic data records, parameter setting, and flame detector cooling air system and other management; With self-diagnosis, interlock, operation and system reset, process information archiving, alarm information display, report printing and other functions.

(1) Process instrument: detect high/low pressure in boiler chamber; High/low gas pressure of blast furnace, converter and coke oven; Feed/induced draft fan operation; Drum water level high/low; Steam pressure, overpressure of boiler body, flame detection, air volume of blower, etc.

(2) Cooling fan control cabinet: there are altogether 2 sets of on-site installation to control the fire inspection cooling fan, with functions such as remote/local start and stop and overload protection.

(3) Fire detection cabinet: A total of 2 on-site installation, controlling 1# and 4# Angle 3 combustion layers and 12 gas-jet infrared dynamic flame detector probes, which are used to monitor the combustion situation of each nozzle. The fire detection processor will receive the fire signal processing from the fire detection probe and feed it back to PLC.

(4) Valve control cabinet: a total of 4 sets of on-site installation, control the upper and lower levels of the blast furnace, coke oven, converter 4 sets of valves, with remote/local switching function, and valve switch signal feedback to PLC.

(5) Ignition control cabinet: a total of 2 sets of on-site installation, control the high-energy four-angle furnace ignition device, propeller, etc., with remote/local ignition function, the ignition device is set for timing lighting, the lighting time is 10s, and the igniter and propeller switch signals are fed back to PLC.

(6) Furnace video surveillance: detect and display the real-time situation of furnace flame, which is composed of special high-temperature resistant lens set, color CCD camera, electric propeller, control unit, display equipment, etc.

Biomass energy is mainly used by direct combustion, gasification, liquefaction and anaerobic fermentation. Because of its high volatile content, high carbon activity, low emission pollution and other characteristics, it is particularly suitable for combustion conversion and utilization, and is a kind of high-quality fuel. Compared with the more mature pressed molded biomass fuel, the biomass powder fuel has a great potential in the development and utilization of biomass energy due to its simple production process, low processing energy consumption and high combustion efficiency.

China started relatively late in biomass suspended combustion, and the theoretical and applied research on biomass suspended combustion is still in its infancy. Xiao Bo et al. proposed a biomass powder three-stage combustion model, based on which a special combustion furnace was designed. After the agricultural waste was broken into powder, it was directly sprayed into the combustion experimental furnace developed. The combustion characteristics of the material powder were studied. In view of common crop straw powder, the biomass suspended combustion characteristics experiment was carried out on the new biomass powder burner to study the influence of temperature distribution, fuel feed amount, ratio of primary and secondary air and particle size in the pre-combustion chamber burner on furnace temperature and flue gas emission.

Influence of fuel feed

The feed amount of powder fuel is controlled by the speed of feed screw regulated by frequency converter. The higher the rotating speed of feed screw, the more feed amount. The volatile content of biomass powder fuel is relatively high, and it is pyrolyzed out in the pre-combustion chamber. The combustion in the boiler is similar to that of gas, so the control of feed amount is very important. As the amount of powder fuel volatilization in the precombustion chamber increases, the combustion intensifies, and the temperature of the precombustion chamber rises rapidly, the high temperature in the precombustion chamber accelerates the volatilization and combustion speed of the fuel, so that the fuel is mainly burned in the precombustion chamber rather than in the furnace, thus reducing the thermal efficiency Rate.

The influence of the ratio of primary and secondary air

Secondary air can not only to supplement a wind, also can be adjusted to precombustion chamber air flow and secondary air through the guide vane cyclone into the precombustion chamber, a mixture of air and the powder fuel in precombustion indoor spiral forward, on the burning torch vents form, increase the powder out of fuel in a precombustion chamber volatile analysis, make the combustion more fully. When the ratio of primary and secondary air is large, the secondary air volume is small, the mixing of air and powder fuel in the furnace is not sufficient, and the combustion is not complete, CO Higher in content.

Influence of particle size

Fuel with small particle size can be heated rapidly, releasing volatiles earlier than fuel with large particle size. Reducing the particle size of biomass powder can effectively improve the combustion performance of biomass powder fuel, but the smaller the particle size of biomass powder is not the better. The particle size of biomass powder is too small, which easily leads to complete combustion of fuel before it enters the furnace. Excessive particle size of biomass powder delays the volatilization and combustion of fuel, making the combustion reaction move to the outlet position of furnace, leading to the discharge of volatiles and carbon particles before complete combustion, and increasing the content of volatiles and CO in the flue gas. The swirl design of the precombustion chamber increases the fuel combustion distance, which can appropriately relax the particle size requirements, on the one hand reduce the cost of grinding, on the other hand improve the safety problems in the grinding process.

"Twelfth five-year" period, with the increasingly diversified energy supply, energy conservation and emission reduction work to strengthen and domestic industrial fuel gas burner industry to take advantage of special fuel as the breakthrough point, developed with independent intellectual property rights of burning coke oven gas, coal-bed methane, gas and producer gas, blast furnace gas and chemical waste and other special burner with a combustible component, and has been leading in the domestic market, such as wuxi Witt burner manufacturing co., LTD., Shanghai LingYunRui burner manufacturing co., LTD., jiangxi China navigation instrument co., LTD has developed its own special products, such as The product fuel covers biogas, coke oven gas, producer gas, blast furnace gas, chemical exhaust gas, etc., and the power of a single unit ranges from 35 to 56 000kW.

As the promoting of "coal to gas" project, since 2017, the home-made conventional fuel (natural gas, liquefied petroleum gas) burner of low nitriding technology to get fast and successfully established the scale of domestic market status and application of the burner has entered a new stage of development, is now out of completely generic patterns, the size of the domestic burner manufacturing expanded rapidly. From 2008 to 2018, the number of domestic burner manufacturers reached 192 (including at least 13 boiler manufacturers), with the biggest change in the last three years. In 2018 alone, there were 65 more burner manufacturers than in 2017. At the same time, the number of Chinese foreign burner brands in the domestic market has also changed greatly, reaching 49 foreign burner brands by 2018, an increase of 8 over that of 2017.

At present domestic manufacturer of pulverized coal burner is more, there are mainly MeiKeYuan Beijing, xi 'an jiaotong university siyuan technology Co., Ltd., xi 'an days set energy Environmental protection engineering technology Co., Ltd., tangshan sands combustion heat energy technology Co., Ltd., shanxi blue sky Environmental protection equipment Co., Ltd., Xuzhou Kerong Environmental Resources Co., Ltd., Qingdao universal energy conservation and Environmental protection boiler Co., Ltd., shandong thorpe energy saving technology Co., Ltd., mount tai group Co., Ltd., etc. Their products are not only for their own supporting but also for relevant boiler enterprises supporting.

Because of the characteristics of industrial boilers, pulverized coal industrial boilers mainly use swirl burners. Pulverized coal combustion technology is derived from the research achievements of universities, the swirl combustion technology of pulverized coal boilers in power stations or the advanced combustion technology of Europe. High efficiency combustion and low nitrogen combustion are the development trend of pulverized coal combustion technology at present and in future. At present, axial vane type and tangential vane type cyclone are generally used in pulverized coal industrial boilers, while axial vane type is more widely used. Low nitrogen combustion technology mainly includes air classification, radial thickening and light burning and flue gas recirculation.

(1) The burner is not reliably interlocked with the boiler protection device

The incomplete interlock between burner and boiler safety protection device is not the only case encountered by euroguarantee technicians, which has a great potential safety hazard. Individual technical personnel is not strong sense of responsibility, working graph save trouble, only then good home burner and control cabinet connection, only can ensure the boiler ignition and extinction protection device for reliable, but did not pick up the burner to the boiler all the wiring for all safety interlock protection device, which can cause the boiler monitoring temperature, pressure, water level or water safety interlock protection device failure, not reliable.

(2) The user does not strictly implement the responsibility of the safety subject

In the process of low nitrogen combustion boiler transformation, many kinds of boiler unit did not according to the strict supervision organization guidance documents to carry out the enterprise security responsibility, the low nitrogen transformation of check and acceptance of responsibility was to special equipment inspection inspection agencies, but want to combine boiler inspection institutions of the burner to examine regularly inspection cycle, can't be all low nitrogen to build before the boiler running to confirm all the burner. If the user adopts a burner that has not been verified by type test, or a burner with inconsistent main parts and no record, it may bring risks and hidden dangers to the safe operation of the boiler.

(3) Poor maintenance of the burner in use

The maintenance of low nitrogen burners is higher than that of conventional fuel and gas burners, especially the burner with full premix surface combustion. The air filter should be cleaned once or twice a week, and the gas filter should be cleaned regularly. Must guarantee for the whole surface of the premixed combustion burner into the wind flow, if not timely clean strainer, will cause the mesh was dust jam, greatly increase the burner into the wind resistance, when jams has made inlet wind speed is less than the flame propagation speed, can produce tempering, led to the mixture of air and gas cavity indoor deflagration, serious when in furnace explosion.

Low nitrogen combustion transformation of boiler is a very professional technical work, which also plays an important role in the prevention and control of air pollution. As a technology that has only been applied in the past two or three years, there are still many aspects to be improved. Boiler use, manufacturing, sales and installation units, burner manufacturing, sales, installation and commissioning units, special equipment safety supervision organizations and inspection and testing institutions, etc., should work together to reduce nitrogen oxide emissions of gas boilers, which benefit the country and the people more safely and more effectively into effect.

1. Improve relevant safety specifications and technical standards

Low nitrogen burner in the domestic application came nearly three years, at present in low nitrogen burner installation, modification, commissioning, use and repair of domestic lack of relevant safety standards and technical standard, lead to safety supervision institutions and the examination agencies lack of laws and regulations or technical basis, carry out supervision and inspection work there are many difficulties. Therefore, it is recommended that the boiler, burner safety supervision agencies entrust a specialized organization, safety, environmental protection, energy conservation and domain experts to the research about low nitrogen combustion boiler alteration in Beijing, according to the problems reflected by, and refer to the relevant technical standards of developed countries, developing the low nitrogen burner safety technical specification, the low nitrogen burner installation, modification, commissioning, use and repair specific technical requirements are put forward.

2. Strengthen the implementation of the safety responsibility of the user unit

Boiler use the unit should be clear own security main body responsibility, and the low nitrogen transformation involves various relevant enterprises closely linked together, make the individual, the full implementation of Beijing quality AD hoc letter [2016] no. 22, Beijing quality hair [2017] no. 6, Beijing do hair [2017] no. 16, Beijing quality supervision of quality control of the file such as the no. 39 [2017] of the relevant requirements.

According to above analysis, the use of units of boiler to take the following measures: 1) the superheater coil from the lower left side of the header, the introduction of derivation to the upper left, import, and lowest in the import of superheater header set the discharge pipe, the discharge pipe to set trap and lead to the safe place, import set so as to solve the water problem in the cabinet. 2) The original unsealed positions of the vertical baffle and shutter separator in the pot shall be sealed. In addition, the steam space height of the pot cannot be changed. To alleviate this problem, a group of underwater orifice plates shall be added to the bottom of the vertical baffle horizontally as a first-stage soda separation device. After the above two treatment measures, the normal operation of the boiler has not occurred the superheater tube explosion accident.

The practical principle of low nitrogen combustion is to control NOx based on air fractional combustion technology. The technology works by burning coal, which actually burns at two temperatures: high oxygen and low oxygen. In this way, the co-occurrence of oxygen-rich and high-combustion temperature can be avoided, thus significantly hindering the formation of thermal NOx and fuel NOx to achieve the effect of NOx generation.

First, hypoxia in the main combustion zone of the lower layer presents an increasing trend. Burning area between the furnace exit and the formation of the corresponding burning distance is relatively short, at the same time the upper combustion temperature of burning zone in low temperature condition, the probability of pulverized coal, combustible gas combustion is not improved significantly, the fly ash carbon index in the boiler flue gas emissions and CO content exist the possibility of increasing, eventually increase the mechanical incomplete combustion loss of fly ash carbon content seems to use q4f refer to below), chemical use q3 refer to below is not completely lost like) the probability of ascension, the boiler thermal efficiency is coming down.

Second, the possibility of high temperature corrosion of water cooling wall increases gradually. In the denitrification reduction zone between the lower main combustion zone and the upper burnout zone, the production of reducing combustible gas (CO+H2) is the largest. The reducing gas reacts with S in the fuel to form HS. Under the reducing atmosphere, H5 gas reacts with the water cooling wall at high temperature. H2S reacts directly with metallic iron to form iron sulfide, some of which is further oxidized to iron oxide. This layer of iron sulfide and iron oxide is porous and does not protect the water cooling wall. H2S gas will continuously corrode the water cooling wall through this porous layer. The concentration of H2S has a linear relationship with the corrosion rate of metal.