How to remediate powder leakage and ash leakage in circulating fluidized bed boiler

The impact of too much or too little return ash on the boiler of circulating fluidized bed boiler dear, hello. The concept of circulating ash volume can be said to be the material in the external circulation of the circulating fluidized bed, or it can be said to be the amount of return material collected by the cyclone. About 50% of the fuel in the dense phase zone of the circulating fluidized bed is burned, releasing heat, which is used to heat fuel and air, and most of the remaining heat must be taken away by the circulating family as a material to maintain stability.

If the circulating material is insufficient, it will lead to too high bed temperature, that is, sufficient circulating ash is an effective means to control too high bed temperature. Conversely, if the amount of ash circulating is too large, it will lead to insufficient combustion and low bed temperature. The amount of circulating ash also determines the concentration of the material in the furnace, and it can be seen from the heat transfer analysis in the furnace that the heat transfer in the furnace increases with the increase of the material concentration, that is, the influence of the change of material concentration on the heat transfer in the furnace is more significant.

It can also be said that the concentration of materials in the furnace determines the output of the boiler, and the concentration of materials in the furnace is large, and the output of the boiler is also large, and the output of the boiler can be controlled by controlling the balance of the materials in the furnace. During operation, the concentration of materials in the furnace increases, that is, the flow resistance increases, and the pressure and silver difference in the suspension section increases. If the concentration of furnace material is too large, the bed temperature will be reduced, which will affect the output of the boiler, and the concentration of furnace material can be controlled by the method of recirculating ash.

The wear problem of circulating fluidized bed boiler was a worldwide problem a few years ago, but with a large number of experiments and practices of scientific researchers, the current circulating fluidized bed boiler has made great progress in controlling wear, and the existing control means are: 1. Work the structure of the boiler, such as transforming the slope sliding surface of the previous boiler Weiran belt into a desktop type to reduce wear.

2. You can bring the upper part of the boiler to the water wall tube for anti-wear spraying, and if necessary, you can also carry out anti-wear spraying on the water wall around the outlet of the boiler furnace.

3. The patented technology of Xi'an Thermal Power Institute can be used to install a wear-proof wall on the water wall of the boiler furnace to control the wear of the boiler (according to the different coal quality, there may be a high bed temperature, high exhaust gas temperature, and it is not easy to carry load, but if the coal quality at the low calorific value is burned, this situation will generally not occur); The load of the boiler is generally determined according to the specific situation of the boiler, such as the coal quality of the boiler burning, the particle size of the coal burned by the boiler, the resistance of the air distribution plate of the boiler design, the structure of the boiler returner, the return of the boiler, the ratio of wind and coal of the boiler and other factors, which should be solved according to the specific situation of the boiler, not a few simple words.

Dear, hello, I am glad to answer for you that the phenomenon of ash collapse of circulating fluidized bed boiler is 1) The fin piece along the water wall on the refractory layer of the dense celery jujube shouting area is seriously worn, and the material will leak out after wearing, therefore, the installation should avoid the fin dislocation and disdain, and the unsmooth part should be carefully polished. Boiler heating surface anti-wear; 2) The installation quality of the sealing box is poor, resulting in ash leakage, especially the rear sealing box with more openings is more likely to have problems. First of all, the leakage of the sparse plate on the upper part of the sealed box should be avoided, especially the leakage caused by the leakage or virtual welding of the weld on the inner part of the vertical rigid beam on the outside of the inclined bucket (due to the inconvenience of the welding position).

Secondly, it is to avoid the use of the same back cover plate for adjacent sealing boxes, and the sealing box will be cracked due to uneven expansion, and the large sealing boxes shared by different pipe holes should be changed to a plurality of independent small sealing boxes; The third is to pay attention to the large gap between the lower secondary air duct and the castable in front of the rock, and the lower secondary air duct is thin and easy to burn or seriously deformed, resulting in flue gas channeling into the sealed box to hollow out the light thermal insulation castable.

Hello dear, glad to give you an answer! 1.The fins along the water-cooled wall on the refractory layer in the dense phase area are seriously worn, and the material will leak out after wearing, so the fin dislocation should be avoided during installation, and the unsmooth parts should be carefully polished.

Boiler heating surface anti-wear; Grille anti-wear warp and weft structure 2The poor installation quality of the sealed box leads to ash leakage, especially the rear sealed box with more openings is more likely to have problems. First of all, it should be avoided to leak welding of the sparse plate on the upper part of the sealed box, especially the leakage caused by the leakage or virtual welding of the weld on the inner part of the vertical rigid beam on the outside of the inclined bucket (due to the inconvenience of the welding position).

The second is to avoid the use of the same back cover plate for adjacent sealing boxes, and the lead balance of the sealing box will be cracked due to uneven expansion, and the large sealing boxes shared by different pipe holes should be changed to a plurality of independent small sealing boxes; The third is that the gap between the secondary air duct and the castable is large, and the secondary air duct is thin and easy to burn or seriously deformed, resulting in flue gas channeling into the sealed box and hollowing out the lightweight thermal insulation castable.

Summary. Circulating fluidized bed boiler furnace coking accident is a common combustion fault, can be divided into low temperature coking and high temperature coking, low temperature coking is the phenomenon of low bed temperature due to poor fluidization of particles sticking together, high temperature coking occurs when the bed temperature rises sharply more than the ash melting point of coal, oxygen content drops sharply, the flame fluidization is poor and the large area is white, the amount of slag is small or can not be released, the negative pressure continues to increase when the bed temperature is low, the wind pressure in the wind chamber is high and the fluctuation increases, and the primary air volume decreases. Mainly due to the fact that the coaling speed is too fast and too much in the process of ignition and pressurization, or there is no air when coaling, a large number of particles that are not fully burned are gathered together for deflagration, and the oxygen amount does not start to rise when the fire is pressurized, and the fan operation is stopped.

The return material of the returner is abnormal, the coal feeder is cut off, the load increases too quickly, the hood is damaged, the ash falls into the air chamber and the air distribution is uneven, and the bed material is too thick and the slag is not discharged in time.

Hello, we have received your question and are working hard to prepare the answer for you, and will reply to you within five minutes! Wait a moment! ^

Circulating fluidized bed boiler furnace coking accident is a common combustion state failure, can be divided into low temperature coking and high temperature coking, low temperature coking is the phenomenon of particles adhesion together due to poor fluidization when the bed temperature is low, when high temperature coking occurs, the bed temperature is disturbed and the seepage rises sharply to exceed the ash melting point of coal, the oxygen content drops sharply, the flame fluidization is poor and the large area is white, the slag amount is small or can not be released, the negative pressure continues to increase when it is serious, the wind pressure in the air chamber is high and the fluctuation increases, and the primary air volume decreases. It is mainly due to the fact that the coaling speed is too fast and too much in the process of ignition and pressurization or there is no air when coaling, a large number of particles that are not fully burned are gathered together for deflagration, and the oxygen content does not start to rise when the fire is slowed down, and the fan operation is stopped. The return material of the returner is abnormal, the coal feeder is cut off, the load increases too quickly, the hood is damaged, the ash falls into the air chamber and the air distribution is uneven, and the bed material is too thick and the slag is not discharged in time.

When it is found that the bed temperature is abnormal, it is necessary to increase the air volume and slag discharge, reduce the amount of coal to drain the circulating ash, and try to drain the slag in the furnace room. Check the coking situation, open the manhole door to pick out the coke block, the coking is not serious, the coke block can be ignited outside the furnace, and the serious can not be treated when it is cooled and then treated. To prevent the occurrence of coking, it is necessary to control the coal particle size below 10mm, strictly control the amount of coal, when lifting the load, first clear the acacia and prepare the air to add coal, reduce the load first reduce the coal and then reduce the wind to avoid the bed temperature fluctuations, to often check the coal feeding situation and check whether the furnace flame color and the returner is normal, the operator should pay attention to the timely slag discharge and check whether there is any slag block, and close the slag discharge door after the slag is discharged.

When the raw coal ash content of the circulating fluidized bed boiler is too high, it will increase the load of the ash return system, which may lead to the blockage and wear of the ash return system, and even cause dangers such as **. In order to adjust this situation, you can start from the following aspects:

1. Raw coal selection.

Choosing a simple cracked coal with a lower ash content as fuel can reduce the ash content in the circulating fluidized bed boiler system. Coal grades with lower ash content can reduce the load on the ash return system, reducing the risk of wear and clogging.

2. Pretreatment process.

The use of pretreatment processes to treat raw coal, such as coal washing, slime dewatering, etc., can effectively reduce the ash content of raw coal. These pretreatment processes can physically or chemically remove or reduce ash from the coal.

3. Optimize the combustion process.

By optimizing the combustion process of the circulating fluidized bed boiler, the ash content produced during coal combustion can be reduced. Adjusting parameters such as the injection method, gas distribution, and bed temperature of pulverized coal can achieve more complete combustion and reduce ash generation.

4. Optimization of ash return system.

Optimization of the ash return system, including reasonable setting of the layout of the ash returner, good pneumatic conveying system design and operation adjustment, etc., can reduce the load of the ash return system, reduce clogging and wear.

5. Regular cleaning and maintenance.

Regular cleaning of the circulating fluidized bed boiler and ash return system, including removing ash accumulation, cleaning pipes and equipment, etc., can reduce ash accumulation and clogging problems and ensure the stable operation of the system.

To sum up, to adjust the situation that the raw coal ash content of circulating fluidized bed boiler is too high, it is necessary to comprehensively consider the measures such as raw coal selection, pretreatment process, combustion process optimization, ash return system optimization, and regular cleaning and maintenance. At the same time, according to the specific situation and actual operation experience, some targeted adjustments and optimizations may be required. It is recommended that you consult a team of professionals or engineers in the relevant field for more accurate and reliable adjustment advice.