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.

而采用冷凝式鍋爐將高溫煙氣中的顯熱和潛熱予以回收，可以達到充分利用能源降低運行成本的效果。

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.

一、使用冷凝置換器

1、 Use condenser displacer

冷凝式換熱器就是增設在天然氣鍋爐尾部的餘熱回收裝置，當煙氣在通道內通過傳熱麵，溫度降露點溫度以下，從而使排煙中的水蒸氣凝結釋放潛熱傳遞給回收工質，可以將排煙中大量的能量加以回收利用，從而達到的效果。

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.

二、煙氣分析

2、 Flue gas analysis

天然氣成分絕大部分為烴，燃氣鍋爐排煙中水蒸氣的含量較高。每1m3天然氣燃燒後可以產生1.55kg水蒸氣，汽化潛熱大約為3700kJ/Nm3，占天然氣的低位發熱量的10%以上。傳統鍋爐中，排煙溫度一般在160～250℃，煙氣中的水蒸氣仍處於過熱狀態，不可能凝結成液態的水而放出汽化潛熱。

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.

因此傳統的天然氣鍋爐理論熱效率一般隻能達到95%左右，利用冷凝式換熱器隻要把煙氣溫度降到煙氣露點溫度以下，就可回收煙氣中的顯熱和水蒸氣的凝結潛熱，按低位發熱量為基準計算，天然氣鍋爐熱效率可達到和超過109%。

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%.