The steam boiler has the characteristics of high work pressure, high media temperature, and complex operating conditions. The types of accidents show a variety of forms. During the operation of the boiler, the phenomenon of pressure in the boiler exceeds the highest permitting work pressure and endangered the safe operation, which is called an ultra -pressure accident. This maximum permit pressure can be the design pressure of the boiler or the defect of the boiler after testing, and the agreed work pressure depends on the intensity. In short, the risk of over pressure boilers is relatively large, one of the direct reasons for the boiler explosion accident
1. The phenomenon of boiler overpressure
(1) The steam pressure rises sharply, exceeding the allowable working pressure, pressure gauge pointer “red line person safety valve action after the pressure is still rising.
(2) Send out overpressure alarm signal, overpressure interlock protection device action to stop the boiler air supply, coal supply and air intake.
(3) The steam temperature increases while the steam flow decreases.
2. Reasons for boiler overpressure
(1) with steam units suddenly stop using steam, so that the steam pressure rises sharply.
(2) The furnace staff does not monitor the pressure gauge, and the combustion is not weakened correspondingly when the load is reduced.
(3) the safety valve fails; The spool is adhered to the valve seat and cannot be opened; The inlet of the safety valve is connected with a blind plate; The exhaust capacity of the safety valve is insufficient.
(4) The pressure gauge tube is blocked and frozen; Pressure gauge failure beyond the calibration period; The pressure gauge is damaged and the pointer indicates incorrect pressure, which does not reflect the real pressure of the boiler.
(5) overpressure alarm failure, overpressure interlock protection device failure.
(6) After the test of the boiler step-down use, if the safety valve caliber does not change accordingly (boiler step-down use, safety valve caliber should be increased), so that the exhaust capacity of the safety valve is insufficient, the steam pressure can not be controlled and overpressure.
3. Treatment of boiler overpressure
(1) Quickly weaken combustion, manually open the safety valve or release valve.
(2) Increase the water supply, at the same time in the lower drum to strengthen blowdown (at this time should pay attention to maintain the normal water level of the boiler), in order to reduce the temperature of the pot water, so as to reduce the pressure of the boiler drum.
(3) If the safety valve fails or all the pressure gauges are damaged, the furnace should be stopped in an emergency manner. After the safety valve and pressure gauges are repaired, the pressure should be increased to run.
(4) When the boiler overpressure occurs and endangers the safe operation, the pressure reduction measures should be taken, but the speed of pressure reduction is strictly prohibited.
(5) After the serious overpressure of the boiler is eliminated, the furnace should be stopped for internal and external inspection of the boiler, the deformation and leakage caused by overpressure should be eliminated, and the safety accessories of the cell should be tested.