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Q&A on the basic operation of boilers I. Methods for flushing boiler water level gauges and pressure gauges. Method for flushing the water level gauge: 1. Open the drain valve to flush out steam, water, and the glass tube. 2. Turn off the water tap. Flush the steam pipeline separately. 3. Open the water cock and close the steam cock to flush the water pipeline. 4. Open the steam valve and close the drain valve to restore the water level to normal. The method for flushing a pressure gauge is to turn the three-way valve of the pressure gauge to the position that leads to the atmosphere. Release the water stored in the elbow. Then turn the faucet to the position where water is stored. Rotate again to the position before flushing to return to normal. II. Methods for identifying and dealing with false water levels. Phenomenon 1: The water level in the gauge fluctuates violently, to the point where it becomes impossible to see the water level clearly. 2. Water hammer occurs in the steam pipeline. Steam and water are leaking at the flange connection. Treatment methods: 1. Reduce combustion, lower the boiler’s evaporation rate, and close the main air valve to decrease the load. 2. Fully open the surface blowdown valve of the upper drum, and partially open the periodic blowdown valve at the lower part of the boiler. At the same time, increase water supply to maintain the water level at normal levels in order to reduce the salt content in the boiler water. 3. Open the drain valves on the pipelines and steam distributors. 4. Increase the frequency of analyses of the boiler water to provide timely guidance for water replacement. III. Briefly describe the corresponding measures taken when the output of the boiler changes. When the boiler’s output increases: 1. Increase the draft, adjust the supply air, and speed up the rotation of the grate. Also, control the water level properly. (High load, low water level) When the boiler’s output decreases: 1. Reduce the air supply, adjust the exhaust air, and lower the speed of the grate. Control the water level well. (Low load, high water level) Generally, there is no need to adjust the coal seam thickness. IV. Emergency measures for overpressure. When the boiler is overpressured, methods such as blowdown and water addition are generally employed. At the same time, reduce the blast air and decrease the exhaust air. Reduce the grate speed. Reduce combustion. (Note the occurrence of water shortage and water overflow.) V. Methods for dealing with water shortage, water overflow, and deviation of the fire bed. Water shortage: 1. The water level is below the safe level or the water level is not visible; the glass panel (tube) of the water gauge turns white. . 2. The low and high water level alarms emit low water level alarm signals. 3. The water supply volume is less than the steam flow rate. The opposite phenomenon occurs if water shortage is caused by a broken furnace tube. 4. In severe cases, a burnt smell can be detected. Treatment method 1. Check the water level indicated by the gauge. Open the drain valve on the water level gauge; the flow of water indicates a situation of excessive water, while the flow of steam indicates a situation of insufficient water. 2. When the water level is below the lowest water level line but above the lower edge of the water gauge, it indicates a slight water shortage. Reduce the fuel and air supply to weaken combustion, and add water to the boiler slowly. At the same time, quickly identify the cause. 3. If the water level cannot be seen on the gauge, it indicates a severe water shortage. An emergency shutdown of the furnace should be carried out. Be sure not to add water to the boiler. Full water phenomenon: 1. The water level is above the maximum level mark, or the water level is not visible; the glass panel (tube) of the water gauge appears dark in color. 2. The high and low water level alarms emit high water level alarm signals. 3. The water supply flow rate is abnormally higher than the steam flow rate. 4. Water hammer sounds are heard in the steam pipeline, and water drips and vapor escapes from the connection flanges. Treatment methods: 1. Flush the water level gauge to check if there is water present, and determine whether it is at full level or severely full. 2. In the case of mild overfilling, partially or completely close the supply valve to reduce or stop the water supply. If necessary, open the drain valve to release a small amount of boiler water. Lower the water level to the normal level, and be vigilant for signs of water shortage. Severe water overflow: Shut off the water supply valve immediately. Stop the water supply and open the drain valve to increase the water discharge. Close the air damper to reduce coal feeding and air supply. Activate the drain valves on the main steam pipe, steam header, and steam cylinders. Bed deviation: It is caused by operational issues: 1. Improper air adjustment, with the dampers in the pre-combustion zone set too wide. The air intake pressure at the grates on both sides is different. There is a phenomenon of spontaneous ignition. 2. The coal particles are unevenly distributed: the coal lumps are concentrated on one or both sides, while the coal particles are in the center. 3. The operators fail to make timely adjustments to the problems that arise in the fire bed. Solution: 1. Add an appropriate amount of water to the coal in advance. It is generally around 10%. 2. Lengthen the fire bed to concentrate wind force and enhance combustion. 3. Card fire position. The simplest way. If it is found that the burning is incomplete or uneven, push it away promptly. Slag should be removed promptly. VI. Briefly describe the steps for normal shutdown and emergency shutdown. Normal shutdown: 1. Close the baffle at the bottom of the coal hopper so that all remaining coal enters the coal gate. When lowering the coal gate, ensure there is a gap of about 50 mm between it and the grate. Avoid burning out the coal gate valve. 2. Reduce the grate speed, as well as ventilation and exhaust airflow. Move the coal about 500 mm behind the gate plate, and stop the grate. Avoid directly grilling the front arch. The furnace chamber maintains a certain negative pressure to cool the grate. 3. Once there is no open flame on the grate, turn off the blower and then the exhaust fan; open the furnace door to allow natural ventilation. 4. After the coal is burned out, rotate the grate again to remove all the ash. 5. Continue to run the grate idly until it cools down. 6. If water needs to be drained, the water temperature must be below 70°C. Avoid the generation of thermal stress. Emergency shutdown of the furnace: 1. Stop feeding coal immediately. Turn off the blower. Reduce induced draft. Remove the remaining coal from the front of the furnace grate. 2. Set the grate speed to maximum so that all the coal on the grate falls into the coal hopper and is extinguished with water. But water must not be poured into the furnace. 3. Open the air chamber dampers fully and shut down the exhaust fan to allow natural ventilation of the boiler. Continue to idle the grate until it cools down. 4. Shutdown due to water shortage: A. It is strictly prohibited to supply water to the boiler. B. Exhausting work involving the opening of safety valves and drain valves is prohibited. Prevent accidents from worsening due to changes in temperature and pressure. C. If there is no water shortage, a pressure-reduction measure of alternating sewage discharge and water supply can be adopted. 5. Shut down the furnace with full water level: A. Stop the feed water supply, reduce the flue dampers, and weaken combustion. B. Open the drain valve to release water and lower the water level appropriately. C. Activate the steam traps on the main steam pipe and steam cylinders to prevent large amounts of water from entering the steam along with it, as well as to avoid water hammer in the pipes.