In paper-making industry there are mainly two process require steam: pulping and drying. The drying process uses the most steam. It takes about 1.8 tons steam to produce 1 ton of paper (depending on the steam dryness and the type of paper). The steam generated by the boiler enters the drying cylinder of the paper-making machine to dry the wet paper. The steam heat turn into high-temperature condensate after used. The high-temperature condensate can be pumped to hot water tank for boiler water replenishment. The condensate recovery can greatly save the water consumption and save fuel cost.

Thermal Energy Utilization in Paper Industry:

(1)Utilization of high-temperature condensate heat.

(2)The heat of boiler combustion exhaust gas is not effectively utilized.
The exhaust gas temperature of boiler without economizer is about 200℃, the exhaust gas temperature of boilers with economizers is 120~150℃. Due to the large heat loss of exhaust gas, the boiler thermal efficiency is only about 92%, which seriously wastes energy.

Usually for paper mill the condensate recovery rate can be over 80%, and condensate temperature about 80±5℃. For the steam system with high condensate recovery rate and high condensate return temperature, and users who have higher system energy saving requirements, engineers design the Rear Air Preheating condensing steam boiler. the high efficiency air pre-heater plus the integrated economizer and condenser, further reduce the smoke exhaust temperature lowest to 60 degree C., it can greatly save energy and improve boiler thermal efficiency. This boiler  adopts the Surpass traditional two pass (high efficiency and low stress) fully wet back boiler body structure, arc-shaped double-open furnace door for easy maintenance. Equipped with high-efficiency air preheater, low-resistance airfoil economizer and condenser, the sensible heat and latent heat of vaporization in flue gas are recovered to the maximum extent. Boiler thermal efficiency can be up to 103%.