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

干背结构对于制造厂来说，具有制造工艺简便、耗材少等优点。

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

干背式燃气锅炉和湿背式燃气锅炉的优缺点分析

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

但对于使用用户来说，炉胆出口后的高温烟（1000℃以上）直接辐射转烟室的耐火材料，使长期在高温中工作的耐火材料易损坏，往往需要较长时间的停炉才能修复，极为不便。

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.

干背式燃气锅炉和湿背式燃气锅炉的优缺点分析

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

湿背式炉体结构，不存在烧坏的麻烦，同时大大提高了燃气锅炉的燃烧效率和热效率，燃料在炉胆内微正压燃烧，高温烟气沿炉胆向后经回燃室转折180°进入烟道管束，经压迫式前烟箱再转折180°进入第二管束，经过对流换热后排入大气。

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.

湿背式结构的燃气锅炉优点是炉膛后的回燃室是泡在水中的湿背回燃室，不存在烧坏的麻烦，正是由于湿背回燃室泡在水的包围之中，同时也提高了锅炉的辐射传热面积和传热效率，于是后来这种结构的燃气锅炉在上深受欢迎。

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.