Compared with traditional coal-fired boilers, natural gas fired boilers emit little sulfur dioxide and nitrogen oxides, reducing the pressure on the environment, but a large amount of water vapor generated after combustion is discharged into the environment with high-temperature flue gas, which still causes a serious waste of energy.
The condensing boiler is used to recover the sensible heat and latent heat in the high-temperature flue gas, which can make full use of energy and reduce the operation cost.
1、 Use condenser displacer
Condensing heat exchanger is a waste heat recovery device added at the tail of natural gas boiler. When the flue gas passes through the heat transfer surface in the channel, the temperature drops below the dew point temperature, so that the water vapor in the flue gas condenses and releases the latent heat to the recovered working medium, which can recover and utilize a large amount of energy in the flue gas, so as to achieve the effect of energy conservation and environmental protection.
2、 Flue gas analysis
Most of natural gas is hydrocarbon, and the content of water vapor in flue gas of gas-fired boiler is high. 1.55kg water vapor can be produced per 1m3 of natural gas after combustion, and the latent heat of vaporization is about 3700kj / Nm3, accounting for more than 10% of the low calorific value of natural gas. In traditional boilers, the flue gas temperature is generally 160 ~ 250 ℃, and the water vapor in the flue gas is still superheated. It is impossible to condense into liquid water and release the latent heat of vaporization.
Therefore, the theoretical thermal efficiency of traditional natural gas boilers can only reach about 95%. As long as the flue gas temperature is reduced below the flue gas dew point temperature by using the condensing heat exchanger, the sensible heat in the flue gas and the condensation latent heat of water vapor can be recovered. Calculated based on the low calorific value, the thermal efficiency of natural gas boilers can reach or exceed 109%.