Boiler Blowdown

Boiler Blowdown is a very important knowledge in the process of boiler use. The correct blowdown method and blowdown process can make the boiler run more stable, improve the steam quality, and steam stability, and can also make the boiler life longer.

‍Why Do Boiler Blowdown‍

1. Boiler feed water always contains a certain amount of salt. After the feed water is dosing, the fouling substances in the feed water will turn into slag. In addition, the boiler water will also produce some corrosion products when corroding metals.

2. During the operation of the boiler, only a small part of these soluble and insoluble impurities is taken away by the steam, and most of them remain in the boiler water. As the boiler water evaporates, the concentration of the water in the boiler gradually increases.

3. Excessive concentration of impurities in the boiler water not only affects the steam quality, but also causes scaling and corrosion of the heating surface, affecting the safe operation of the boiler.

‍Purpose of Boiler Blowdown‍

1. Ensure the quality of water in the boiler.

2. Keep the boiler operating safely.

3. 3. Extend the service life of the boiler.

‍How to Perform Boiler Blowdown‍

1. Before Discharging the Sewage:

Ensure that the sewage is discharged under the premise of high-water level and low load.

2. Blowdown Valve Open Method.

First open the blowdown valve at the front of the furnace, and then slowly open the blowdown valve at the back of the furnace. Remember to open slowly in this step. The purpose is to heat the sewage pipe (especially in winter), and to prevent accidents (such as leakage of connecting gaskets) when it is suddenly opened. 

3. When Heating the Blowdown Pipe:

slowly open the blowdown valve after the furnace until it is fully open, then close the valve, open the blowdown valve after the furnace again, and then close it, repeat this operation two to three times (usually three times), and open the valve time control In 2~3 seconds. Finally, close the blowdown valve in front of the furnace.

4. Perform the Above Operations on the Same Blowdown. 

5. After the Overall Primary Blowdown Work is Completed,：

The boiler liquid level should drop by 20~750px. 

‍Precautions for Boiler Blowdown‍

1. Ensure that the boiler performs blowdown operations under high water level and low load conditions;  

2. Ensure that before the boiler blowdown operation, only a single boiler is blown off, and it is strictly forbidden to blow off two or three sets at the same time;  

3. The valve must be opened slowly when the sewage is discharged, and it is strictly prohibited to open or close quickly;  

4. When opening the blowdown valve, pay attention to the sequence of opening the valve. It is strictly forbidden to control the blowdown process by using the blowdown valve in front of the furnace.

5. During the blowdown operation, blow off the boiler, both sides and the back side at the same time, and do not operate only one side;  

6. In case of special circumstances during the operation that cannot be handled, it should be reported in time or an emergency shutdown operation should be carried out.

‍Boiler Blowdown Requirements‍

1. Frequent discharge: In other words, there are more sewage discharges, especially when the bottom sewage is used to remove the slag, the short-time and multiple sewage discharges are much better than the long-term, one-time sewage discharge.

2. Less discharge: As long as frequent discharge is achieved, less discharge will inevitably be achieved, that is, the amount of sewage discharged every time is small. This can ensure that the steam supply is not affected, and the quality of the boiler water can always be controlled within the standard range. Will produce larger fluctuations, which is very beneficial to boiler maintenance.

3. Balanced discharge: It means that the time interval for each discharge is roughly the same, so that the quality of the pot water is always kept in a balanced state.

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Boiler blowdown method‍

1. Continuous blowdown

2. Regular sewage discharge