What is the hardness of condensate water from gas boiler flue gas?

As a clean fuel, natural gas has much lower sulfur content and nitrogen content than coal, and there is no ash in the fuel, and the flue gas produced after combustion is almost smoke-free. Therefore, a nationwide upsurge of coal to gas has been set off.

However, there are some problems in the process of gas boiler operation, among which the hardness, harm and treatment of gas boiler flue gas condensate are prominent.

When the boiler flue gas temperature is lower than the dew point temperature or the heating surface wall temperature is lower than the flue gas dew point temperature, the water vapor in the flue gas will condense or condense on the heating surface wall. Condensed water is inversely proportional to exhaust temperature, inlet water temperature and excess air coefficient, and is closely related to the structure of heat exchange surface. If the economizer adopts finned tube structure, the condensed water will be greatly reduced.

Hardness and harm of condensed water from boiler flue gas

Because CO2, NOx, SOx and other gases in the flue gas are dissolved in the condensate water, the condensate water has high acidity, and the hardness of the condensate water in the gas boiler flue gas is very low. The acid concentration of condensed water in different parts is different. From the beginning of flue gas condensation on the heating surface to the tail condenser, the acid concentration of condensed water gradually decreases, which makes the pH value of condensed water accumulated in the furnace lower than that of the condenser. At the same time, because of the corrosion of the heating surface, the iron ion content and conductivity of condensed water in the furnace are increased.

Because of the low hardness of gas boiler flue gas condensate, the main harm of condensate is the corrosion of heating surface. In addition, the insulation effect of boiler insulation materials will be reduced under the erosion of condensed water for a long time, and even fall off in severe cases, which will increase the heat loss of the boiler and reduce the thermal efficiency of the boiler. At the same time, after the sealing material is deformed and aged, the sealing effect becomes worse, resulting in smoke leakage and certain energy loss. In addition, the leakage of harmful components in flue gas will also threaten the life safety of boiler operators.

ZOZEN attaches great importance to the hardness of gas-fired boiler flue gas condensate, and puts forward effective measures from design, manufacture, operation and maintenance to reduce the corrosion of condensate to the boiler body and recycle the condensate and its heat, thus effectively improving the safe and economic operation level of the boiler.

Aiming at the problem of condensed water, ZOZEN Boiler has developed a condensed water recovery device and a sealing device which are in line with the gas boiler. By adding a condenser and an economizer at the tail of the boiler, the exhaust temperature can be reduced to 60℃, and the sensible heat and latent heat of the condensed water can be fully utilized, which not only solves the hydrophobic problem of the gas boiler, but also improves the comprehensive thermal efficiency of ZOZEN gas boiler system to over 98%.