Methods for Controlling Temperature in Saturated Pressure Vessels

 
In saturated pressure vessels, temperature changes in response to variations in working pressure. This temperature fluctuation is primarily influenced by two key factors: the exothermic reactions on the flue gas side of the heating surface and the endothermic reactions on the pressure vessel side. Variations in the temperature, quantity, and flow rate of the flue gas passing through the heating surface can cause the temperature of the pressure vessel to rise or fall. Effective temperature control is crucial for the safe and stable operation of pressure vessels. Here are several common methods to lower steam temperature when it becomes excessively high:
 
Utilizing Desuperheaters
 
If the system is equipped with a desuperheater, increasing the water flow through the desuperheater can reduce the temperature. Desuperheaters work by injecting water into the steam, which absorbs some of the heat and lowers the steam temperature. This method is simple to operate and easy to adjust, making it a common temperature control technique.
 
Steam Injection Cooling
 
Injecting steam into the outlet of the pressure vessel can effectively reduce the temperature. This method involves introducing lower temperature steam directly into the high-temperature area, providing a cooling effect. Steam injection cooling can quickly adjust the temperature and is suitable for emergency cooling situations.
 
Soot Blowing
 
Performing soot blowing on the heating surface before the superheater is an effective method to lower the temperature. For example, soot blowing the reheater can increase the heat absorption of the heating surface inside the furnace, reduce the excess air coefficient at the furnace outlet, and thus lower the heat transfer temperature of the heating surface. Regularly cleaning the heating surface of accumulated soot helps maintain heat exchange efficiency and reduces operating temperatures.
 
Reducing Excess Air Volume
 
Reducing the excess air volume within permissible limits can effectively lower the temperature. Excessive excess air increases the furnace temperature and adds to the pressure vessel's load. By optimizing the air supply and controlling the excess air volume, the thermal load on the pressure vessel can be lessened, thereby reducing the temperature.
 
Increasing Feedwater Temperature
 
When the load remains constant, increasing the feedwater temperature can weaken combustion, preventing an increase in discharge. Weakened combustion results in decreased flue gas quantity and flow rate, reducing the heat absorption by the heating surface and thus lowering the pressure vessel temperature. Properly adjusting the feedwater temperature can improve thermal efficiency and effectively control the temperature.
 
Adjusting Combustion Management
 
Appropriately reducing the air flow from the induced draft fan and blower can lower the furnace flame, reducing the amount of flue gas reaching the heating surface and decreasing the excess air coefficient. Ultimately, this lowers the temperature. Optimizing combustion management by controlling flame position and combustion intensity can effectively reduce heat transfer to the heating surface, enhancing temperature control.
 
By employing these methods, the temperature of saturated pressure vessels can be effectively controlled, ensuring the safe and stable operation of the equipment. Proper utilization of these temperature control techniques not only extends the lifespan of the equipment but also improves operational efficiency and reduces energy consumption. As technology continues to advance, these methods will be further refined, providing more reliable solutions for temperature regulation in pressure vessels.