One is the dry furnace back, the other is the wet furnace back.

幹背結構對於製造廠來說，具有製造工藝簡便、耗材少等優點。

Dry back structure has the advantages of simple manufacturing process and less consumables for manufacturers.

幹背式燃氣鍋爐和濕背式燃氣鍋爐的優缺點分析

Analysis on advantages and disadvantages of dry back gas fired boiler and wet back gas fired boiler

但對於使用用戶來說，爐膽出口後的高溫煙（1000℃以上）直接輻射轉煙室的耐火材料，使長期在高溫中工作的耐火材料易損壞，往往需要較長時間的停爐才能修複，極為不便。

However, for users, the high-temperature smoke (above 1000 ℃) directly radiates the refractory in the flue gas chamber after the furnace outlet, which makes the refractory materials working in high temperature for a long time easy to be damaged, and it is very inconvenient to repair the refractory after a long time of furnace shutdown.

幹背式燃氣鍋爐和濕背式燃氣鍋爐的優缺點分析

Analysis on advantages and disadvantages of dry back gas fired boiler and wet back gas fired boiler

濕背式爐體結構，不存在燒壞的麻煩，同時大大提高了燃氣鍋爐的燃燒效率和熱效率，燃料在爐膽內微正壓燃燒，高溫煙氣沿爐膽向後經回燃室轉折180°進入煙道管束，經壓迫式前煙箱再轉折180°進入第二管束，經過對流換熱後排入大氣。

The structure of wet back type furnace body has no burning out trouble, and greatly improves the combustion efficiency and thermal efficiency of the gas-fired boiler. The fuel is slightly positive pressure combustion in the furnace, and the high-temperature flue gas turns 180 ° along the furnace back through the reburning chamber to enter the first flue tube bundle, and then turns 180 ° through the compression type front smoke box to enter the second tube bundle, which is discharged into the atmosphere after convection heat exchange.

濕背式結構的燃氣鍋爐優點是爐膛後的回燃室是泡在水中的濕背回燃室，不存在燒壞的麻煩，正是由於濕背回燃室泡在水的包圍之中，同時也提高了鍋爐的輻射傳熱麵積和傳熱效率，於是後來這種結構的燃氣鍋爐在上深受歡迎。

The advantage of gas-fired boiler with wet back structure is that the reburning chamber behind the furnace is immersed in water, so there is no problem of burning out. It is precisely because the chamber is surrounded by water, and it also improves the radiation heat transfer area and heat transfer efficiency of the boiler. Therefore, the gas-fired boiler with this structure is very popular in the world.