Coal is one of the main fuels used by boilers, especially the coal-fired boiler. In order to reduce the production costs, we need to know whether the coal-fired boiler saves coal in operation.
The fuel of coal-fired boiler will release some harmful substances after combustion that are harmful to human body, but also pollute the environment. Therefore, the desulfurization treatment is required for coal-fired boiler, including desulfurization before combustion, desulfurization during combustion and desulfurization after combustion. The specific operating methods are different.
When regulating and controlling the coal-fired steam boiler, it will involve the banking-up operation which has a set of operating steps and points for attention. Strictly adhering to the operating steps will be helpful for the more efficient operation of coal-fired steam boiler and can extend its service life at the same time.
In the adjustment of boiler operation, on the basis of ensuring safe operation, economic operation must also be achieved to improve boiler efficiency. In general boiler units, the efficiency can basically reach more than 92%, and the total loss is less than 8%. The loss is: exhaust heat loss, generally 5-6%, followed by mechanical incomplete combustion heat loss is less than 1-1.5 %, heat loss and ash slag physical heat loss are about 1%. (Physical heat loss for high ash coal ash residue will be greater).
From the point of view of quantification of indicators, the key to improving boiler efficiency is to reduce smoke loss and heat loss due to incomplete combustion of machinery. Pay attention to the flue gas temperature changes. Excessive flue gas temperature will affect the efficiency of the boiler. Too low temperature may cause low-temperature corrosion of the air preheater. Therefore, it is necessary to strengthen the adjustment according to the load changes during operation. When t
For same energy output when energy input is lesser efficiency increase. When maximum heat energy is generated from coal or losses in heat transfer are reduced efficiency increase. Coal in boulder size is burnt combustion may not be complete. There will be more unburnt coal. As per coal chemistry and as per boiler flue gas velocity as designed best coal size for full combustion is designed. Maximum crushed coal is also not the best. Then there will be more coal dust. According to general design in various technologies pulverized coal give best combustion for fbc boilers. For cfbc boilers generally crushed coal size is 6 mm.
When you achieve best combustion mean this is main contributor for increase in efficiency. Boiler design, heat transfer, flue gas velocity, heat losses, are other factors for efficiency.
1.Primary air is used for transportation of fine coal particle from coal mill to boiler floor at different elevations as per requirement.
2.Primary air is used for preheating of moisturised coal in to the coal mill so that minimum energy is required for combustion of the same.
3.As we all know that only 23% oxygen is available in the air by weight. For combustion of huge quantity of coal inside the boiler very high quantity of oxygen is required. This oxygen requirement will be completed by secondary air which is supplied by FORCED DRAFT fans through ducts.
This secondary air is coming via air preheater hence its outlet temperature increases this will help in combustion and low heat input is required for combustion of coal.
Few parameters critical to health of the Boiler are
(4)Heat rate of the Boiler. This is a composite index of many performance indicators. Most of them will appear below.
(5)Unburnt fuel in flue gas and at boiler bottom .
(6)Flue gas furnace exit temperature.
(7)Boiler tube metal temperatures.
(8)Oxygen in flue gas.
(9)Imbalances in flue gas temperature over a cross section.
(10)Spray water consumption in Super heater and Reheater.
(11)Heat radiation from insulation.
The above all affects the performance of the boiler.
The proximate analysis of coal is to dry, heat and burn coal samples as required to get the percentage of moisture, volatiles, fixed carbon and ash in the coal and learn about the characteristics of coal combustion.
