1) Set up the air preheater. One of the most effective measures to improve the thermal efficiency of thermal oil heater is to use an air preheater for heat recovery. 2) Use waste heat boiler for heat recovery. The waste heat boiler uses the waste heat in the flue gas exhausted from the thermal oil heater to heat water or generate steam.
The exhaust gas heat loss of coal-fired boiler is caused by the flue gas removed by final stage heat exchanger. The flue gas will take away a part of heat, mainly including the heat taken away by dry flue gas and the sensible heat with water vapor in the flue gas. What’s more, if the combustible gas in the coal-fired boiler is not completely burned, there will be heat loss as well. Therefore, this kind of heat loss mainly depends on the content of incomplete combustion products in the exhaust smoke.
Boiler produces heat via fuel combustion, so the burner is one of the important parts of boiler. And the air supply system is also an important component of burner. Whether the burner works well largely depends on its air supply system.
From the perspective of atomization mode, there are three kinds of burner used by boiler that are rotating cup atomization burner, pressure atomization burner and medium atomization burner.
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
Influencing factors of slagging on heating surface of boiler
(1) Ash characteristics of pulverized coal
Generally, the softening temperature ST of ash is used as the main indicator of slag formation. Coal with low ash melting point (ST<1200℃) is easy to slag. In addition, the slagging index also includes: silicon ratio, alkali-acid ratio, slagging index, limit viscosity and so on.
（2）Aerodynamic characteristics in the furnace
Improper air flow organization leads to flame center deviation, and the pulverized coal air flow flame adheres to the wall, causing local slagging of the water-cooled wall;
Improper air flow organization, forming flue gas retention vortex area and forming a reducing atmosphere (with CO), reducing the ash melting point and increasing the possibility of slagging.
Excess air coefficient: When the excess air in the furnace is too small, a reducing atmosphere may be generated, and the tendency of slagging will increase accordingly.
（3）Influence of boiler heat lo
The condensing boiler burns carbon-based fuel with oxygen in order to produce steam and carbon dioxide. The gases that escape this process (through a chimney) as exhaust are called flue gases. The major advantage is that they offer up to a 90% improvement in terms of efficiency when compared to standard gas boilers. Overall, condensing boilers are considered much more efficient in contrast to non-condensing gas boilers, a major consideration for any business running on a budget.
