Regular sewage discharge mainly refers to the elimination of the bottom of the boiler slag, dirt and corrosion products, reduce furnace tube scaling, prevent blockage, reduce the salt content of pot water, strengthen the heat transfer effect.Some people will think that the longer the sewage time, the more impurities will be discharged from the bottom of the pot, the better the effect of sewage, but in fact it is not.
Blowdown time is too long, a large amount of heat is wasted, affecting the heating steam pressure;The second is adverse to the boiler water circulation, serious water wall tube blasting will occur.
Therefore, regular sewage discharge must be carried out in accordance with the principle of "frequently row, less row, even row", and set special person to operate.It is generally stipulated that every eight hours at least one blowdown, each blowdown time shall not be greater than 30s, and overtime is strictly prohibited.
Low exhaust temperature indicates that the waste heat of boiler exhaust smoke is well utilized, but if the exhaust temperature is too low, some abnormal phenomena may occur.It mainly includes:
(1) The cold air enters the measuring point of the exhaust temperature, which makes the measured value low;
(2) excess air coefficient of flue is too high;
Boiler operation load is too low;
(4) bad combustion, furnace temperature is too low;
⑤ Leakage of tail superheater, reheater, economizer, air preheater, etc.
When the exhaust temperature is lowered, it will cause serious consequences such as low temperature sulfuric acid corrosion, ulceration and perforation on the tube wall of the heating surface at the tail.Therefore, large and medium-sized oil stoves and part of the tail of coal stoves should be equipped with steam heaters to improve the temperature of smoke exhaust.The normal exhaust temperature should conform to the design value of the boiler.