Many boilers used for heating or seasonal loads or for standby service may have extended periods of non-use. Many technicists may come across the shutdown in the use of coal fired steam boiler. The shutdown can be divided into three types: pressure fire shutdown,normal shut down,and emergency shutdown.In this text,we will mainly discuss the pressure fire shutdown.
We can appropriately thicken the coal seam,stop the rotation of boiler grate,stop the running of drum induced draft fan,turn down the damper of ventilation door and gas pass under the grate moderately,maintaining the combustion through natural ventilation.
The steam pressure should be allowed to drop naturally without opening vents or other intentional means of taking steam from the unit to hasten the lowering of steam pressure. A cooling rate exceeding 100Â°F per hour to 150Â°F per hour by excessive opening of vents should be avoided to limit the drum distortion and resulting strains on tube joints. Vents can be fully opened when the steam pressure drops to 15 to 20 psig. Close the stop valve on the steam line and open the drain (if provided). When the steam pressure has dropped to approximately 20 psig, open the drum vent valve to prevent a vacuum from forming within the boiler. The boiler is drained only after the water temperature drops below 200Â°F.
Turn off the main gas pass,and open other related cooling channels.
It is hoped that this article will provide a better understanding of the proper operation of coal fired steam boiler shutdown.In case you need to know more,please do not hesitate to contact us!