The recovery of sodium salt from back liquor in the paper industry

                                                                                                                                                                                       - Heating and cooling of black liquor

Application of heat exchanger in paper industry:

1. Coating

2. Heating and Cooling of black liquor

3. Turbid filtrate

4. Cool the sodium hydroxide aqueous solution

5. Cooling of saline-alkali solution for bleaching

6. Heat recovery of cellophane waste liquid

Ect.

The black liquor is a major source of pollution in the paper industry. Using the recovery process of sodium salt (Sodium Hydroxide and Sodium Sulfide), which is the concentration and combustion of back liquor, that can solve this problem effectively, and achieve the purpose of heat and sodium salt recovery. Before the black liquor going to the evaporator, it must be preheated to reduce the temperature difference and improve the efficiency of evaporation. The black liquor is usually preheated by the fixed tube sheet heat exchanger.

Black liquor preheaters generally use tubular preheaters. The tubular black liquor preheater is divided into two types: horizontal and vertical, and there are single-program and multi-program in the two forms. The preheating effect of the horizontal preheater is better, but the main disadvantage is that the structure is not compact, the heat loss is large, the area is large, and the maintenance is inconvenient. Vertical preheaters are generally multi-program. This kind of preheater basically overcomes the shortcomings of the horizontal type, medium and small factories mostly use this form.