High-temperature corrosion of water-cooled wall of boiler for industrial boiler in chemical
What are the causes of high temperature corrosion of water wall of industrial boilers in chemical plants? according to the analysis of raw coal sulfides, according to the relevant statistical data, the occurrence of inorganic sulfur in coal is mainly inorganic sulfur, accounting for 60% of the total sulfur content, accounting for 60% of the total sulfur content. The remaining 30% �� 40% is organic sulfur. Most of the inorganic sulfur occurs in the form of pyrite, and sulfate accounts for only a small part of the inorganic sulfur content. the results of sulfur speciation in raw coal are shown in Table 2. Because pyrite has a serious influence on boiler slagging and corrosion, it has been paid attention to in the process of practice, but the corrosion effect of sulfate on water wall is often ignored. Therefore, in the specific It is necessary to determine the form of sulfur in combustion raw coal in the process of practice.
2. Coal quality analysis the coal used in the industrial boiler of the chemical plant is 50% anthracite and 50% bituminous coal. According to the coal quality test data of the relevant research institutions, it can be seen that the volatile matter of raw coal used in the industrial boiler of the chemical plant is crystal water. The content of non-flammable or flame retardant components such as CO2 is higher, the content of combustible substances such as CH4,H2 is low, the release temperature of volatile matter is higher, the release is slower, the combustion time of coal is long, and the ash content produced by combustion is high. It is easy to cause reductive components on the water wall. 3, the size of the inner tangential circle of the boiler is analyzed, and the industrial boiler in the chemical plant is considered for use in the early stage of design. Mixed power coal to achieve the purpose of enhanced combustion, so the boiler tangential design is large, large tangential circle will cause high temperature corrosion of pulverized gas and other substances formed after coal combustion. The experimental results also show that when the tangential diameter of the boiler is in the range of 8 �� 8.3 m, the deflection of the primary air flow after leaving the nozzle under the action of upper and lower secondary air mixing and floating air flow is obviously larger than that of other tangential circles.
4. The use of bituminous coal and anthracite mixed power coal is considered in the analysis of boiler design by air flow and two-channel burner. therefore, higher secondary wind speed and lower primary wind speed are used, the sizes of which are 43.5 m / s, 22.5 m / s, respectively. The great difference of secondary wind speed results in the obvious difference of jet rigidity. Due to the influence of the upstream air flow at the adjacent angle and the difference of replenishment conditions on both sides, when the primary and secondary air flow is ejected from the burner, the air flow will shift to the water wall of the back-to-flame. At this time, the primary air flow with lower jet velocity is more obviously deviated than the secondary air flow, which makes the primary and secondary air flow more obvious. The separation phenomenon between them is obvious. Through the analysis of long belt and other related tests, it can be seen that the downstream part of the primary air flow is obviously moving against the boiler wall, so this part of the air flow deviates from the direction of the secondary air flow, and the pulverized coal and other combustibles burn under the condition of insufficient oxygen supply. Produces a certain amount of reductive gas composition. At the same time, due to the design of two-channel burners, the separation and migration of primary and secondary air flow is aggravated. To a certain extent, when the reflux in the boiler is strong, the better the reflux effect of flue gas is, the more obvious the combustion effect of fuel is. However, when the reflux is strong, it will also lead to the attenuation of the primary air flow. Dual channel design causes combustion The outlet area of the burner is much larger than the outlet area of the conventional single channel, but also the outlet speed of the primary air stream is greatly reduced. in general, that difference of the two-channel design and one and the secondary air flow speed is analyzed, so that the stiffness of the primary air flow is reduced obviously, and the wind-flow deviation phenomenon is serious, The high-temperature corrosion of the water-cooled wall is easy to occur.
The raw coal pulverizing system of the raw coal is designed according to the raw coal type of combustion and the coal, and when the coal quality with poor quality is adopted, the load of the pulverizing system is increased, the separation effect is reduced, and the particle size of the pulverized coal is increased, The thickness of the pulverized coal has an obvious influence on the high-temperature corrosion of the boiler, and when the coal powder When the particles increase, the flare length of combustion in the boiler is easy to occur, reducing the combustion effect of pulverized coal, and the coarse particle pulverized coal that is not fully burned is bonded near the water wall of the boiler, so that the high temperature corrosion phenomenon is aggravated.
