How to calculate boiler water consumption? What precautions should be taken when replenishing water and draining sewage from boilers?

In recent years, with the rapid economic development, the demand for boilers has also increased. During the daily operation of the boiler, it mainly consumes fuel, electricity and water. Among them, boiler water consumption is not only related to cost accounting, but also affects the calculation of boiler water replenishment. At the same time, the water replenishment and sewage discharge of the boiler play an important role in the use of the boiler. Therefore, this article will talk with you about some issues about boiler water consumption, water replenishment, and sewage discharge.


Boiler displacement calculation method

The calculation formula of boiler water consumption is: water consumption = boiler evaporation + steam and water loss

Among them, the calculation method of steam and water loss is: steam and water loss = boiler blowdown loss + pipeline steam and water loss

Boiler blowdown is 1~5% (related to water supply quality), and pipeline steam and water loss is generally 3%

If the condensed water cannot be recovered after the boiler steam is used, water consumption per 1t of steam = 1+1X5% (5% for blowdown loss) + 1X3% (3% for pipeline loss) = 1.08t of water

Boiler water replenishment:

In steam boilers, generally speaking, there are two main ways to replenish water, namely manual water replenishment and automatic water replenishment. For manual water replenishment, the operator is required to make accurate judgments based on the water level. Automatic water replenishment is carried out by automatic control of high and low water levels. In addition, when it comes to replenishing water, there are hot and cold water.

Boiler wastewater:

Steam boilers and hot water boilers have different blowdowns. Steam boilers have continuous blowdown and intermittent blowdown, while hot water boilers mainly have intermittent blowdown. The size of the boiler and the amount of blowdown are stipulated in the boiler specifications; the water consumption between 3 and 10% also depends on the Depending on the purpose of the boiler, for example, heating boilers mainly consider the loss of pipes. The range from new pipes to old pipes can be 5% to 55%. Irregular flushing and blowdown during boiler soft water preparation depends on what process is mainly adopted. Backflush water can be between 5% and 5%. Choose between ~15%. Of course, some use reverse osmosis, and the amount of sewage discharge will be very small.


The drainage of the boiler itself includes fixed drainage and continuous drainage:

Continuous discharge: As the name suggests, it means continuous discharge through the normally open valve, mainly discharging water on the surface of the upper drum (steam drum). Because the salt content of this part of water is very high, it has a great impact on the steam quality. The emission accounts for about 1% of the evaporation. It is usually connected to the continuous expansion vessel to recover its heat.

Scheduled discharge: means regular discharge of sewage. It mainly discharges rust, impurities, etc. in the header (header box). The color is mostly reddish brown. The discharge volume is about 50% of the fixed discharge. It is connected to the fixed discharge expansion vessel to reduce pressure and temperature.

Post time: Nov-20-2023