Boiler water quality management involves boiler raw water, boiler feed water and boiler make-up water, etc., each of which has its own specific definition and testing index.In this paper, we will discuss in detail the definitions of these three types of water quality, their testing indicators and their importance.
Raw boiler water, also known as raw water, is natural water without any treatment, mainly from rivers, wells or city tap water.Raw water contains a variety of impurities and minerals, such as suspended particulate matter, calcium and magnesium ions, chloride ions, and dissolved oxygen.These impurities and minerals can have a serious impact on the safe operation and efficiency of the boiler if they enter the boiler directly.
Detection Indicator:
Turbidity: reflecting the content of suspended solids in water, is an important indicator for evaluating the cleanliness of water quality.
Hardness: Indicates the amount of calcium and magnesium ions in the water, and is the main factor in the production of scale.
pH: Indicates the acidity or alkalinity of the water, which has a significant effect on the rate of corrosion of boiler metals.
Dissolved Oxygen: Indicates the amount of oxygen dissolved in the water, which contributes to the oxidative corrosion of boiler metals.
Chloride ion content: excessive levels can have a corrosive effect on boiler metals.
The content of other metal ions: such as copper, iron, etc., too high can also adversely affect the boiler metal.
Boiler feedwater is water that enters the boiler directly and is used by the boiler for evaporation or heating.Feedwater is usually a mixture of make-up water and production return water, and needs to meet stringent water quality requirements.Before entering the boiler, the feed water usually needs to undergo a series of treatments, such as softening, de-oxygenation, etc., in order to remove hardness ions, dissolved oxygen and other harmful substances in the water, and to ensure that the water quality meets the boiler's operational requirements.
Detection Indicator:
Hardness: After softening treatment, the hardness of boiler feed water should be significantly reduced to avoid scale formation in the boiler.
Dissolved Oxygen: Through deoxygenation treatment, the dissolved oxygen in the boiler feed water should be controlled at a very low level to prevent oxidative corrosion of the boiler metal.
pH: The pH of the boiler feed water should be adjusted to a suitable range (between 7 and 9) to slow down the rate of metal corrosion and maintain stable water quality.
Conductivity: reflecting the ionic content of water, need to be controlled within a certain range to ensure the thermal efficiency of the boiler and avoid scaling.
Other specific indicators: such as phosphate content (to prevent scaling and corrosion), chloride content (strictly controlled to prevent corrosion), etc., vary depending on the type of boiler and operating conditions.
Boiler make-up water is water that is added to the boiler to replenish losses due to evaporation, discharge, etc. during boiler operation.The water quality requirements for recharge water are similar to those for feed water, but with more emphasis on its replenishment capacity and stability.For different types of boilers, the indicators and frequency of testing of make-up water vary.
Detection Indicator:
Hardness: Normally needs to be kept low to avoid scale formation in the boiler.
pH: Maintain proper acidity and alkalinity to minimize corrosion.
Turbidity: Ensure the cleanliness of the water and reduce the impact of impurities on the boiler.
Dissolved Oxygen: Controlled at very low levels to prevent corrosion of boiler metals.
Iron content: The presence of iron ions increases the risk of corrosion inside the boiler and needs to be kept within safe limits.
The quality of boiler raw water, feed water and make-up water directly affects the heat transfer efficiency, corrosion rate and steam quality of the boiler.Through regular testing and monitoring of water quality, water quality problems can be detected and solved in time, reducing corrosion and scaling inside the boiler, improving energy utilization efficiency, reducing operating costs and reducing environmental pollution.
