The preventive measures which could be observed by the operating personnel during the various stages are as follows:
     --- During the operation, the furnace inside should be of negative pressure, especially the furnace lower parts, the furnace door is not allowed to be open, so that people would not be hurt.
     --- The furnace pressure limitation or the high negative pressure or the positive pressure of furnace would lead to the destroying of the boiler units and auxiliary equipments. Therefore, the furnace pressure must be controlled during the operation, and the following ones are required to be achieved.
     1. Monitor the negative pressure of furnace (the measuring of the balanced points on furnace exit), the negative pressure should be automatically controlled to be within -100～-250Pa.The pressure  change of furnace balanced points is not allowed to be more than ±500Pa (alarming value).
     2. The set pressure change of furnace outlet pressure of MFT is ±2500Pa, and there could be 5 seconds delay.
     3. The remove of the induced draft fan and the blower is set at the moment that the furnace outlet pressure ± 4000Pa, no delay.
     --- After MFT, there is heat storage caused by the large number of cycles within the boiler, so the boiler water level and the boiler steam pressure must be noted.
     --- The adjustment of safety valve
     All the safety valves are already set by the manufacturer, but it still should be checked under the specific working condition before the first start-up of boiler and the pressure-rising. Any one not in line with the criterion should be adjusted again.
     --- The requirements of excessive air
     In order to maintain good combustion conditions, the furnace excessive air coefficient should be under controlling, make sure that there is proper ratio between the air and coal. Under the rated load, the corresponding oxygen content should be controlled to be 5%, and this data should be regarded as the reference, and the best value should be determined through the adjustment at last.
     --- Temperature distribution (towards to the bituminous coal fuel)
     The bed temperature changes can be monitored through the furnace surrounding thermocouples which are arranged on the upper part of air distributors. Select two boiled measuring points and the average value should be regarded as the controlling temperature of the coal change. The normal bed operating range is 880～960℃, the high alarming value of bed temperature is 990℃. Once the temperature is more than 1050℃, MFT would act. The lowest operating bed temperature is 840℃, the bed temperature is not allowed to be lower than this under the condition that there is no combustion-supporting. The low alarming value of bed temperature is 820℃, MFT would act if the bed temperature is lower than 700℃. Unless the under-bed ignition burner is operated, if the bed temperature is reduced to be below 500℃, regardless of the burner is operated or not, the feeder would be cut off automatically.
     --- To monitor the starting and operating conditions, the thermocouple is arranged on some places of the steam side pipeline, and the starting speed should be controlled.
     The above-mentioned thermocouple and the other thermocouples (includes the indication of the controlling room) should be all checked, and they should operate at any time. During the operating of boiler, only if the steam temperature would not exceed the alarming limit in the above table, it can continue to operate. And it alarms, the working personnel should adjust the working conditions to ensure the safety of the equipments.