Clean production method for rice-wheat straw pulp capable of poaching by acetic acid method

Abstract

The invention discloses a paddy grass slurry cleaning producing method through acetic acid method that is produced by boiling grass slurry by acetic acid with catalyst CaCl2 + HCl and NaCl. CaCl2 + HCl used as catalyst could be benefit for protecting fiber, improve slurry yield, physical intension and bleaching ability. Auxiliary agent NaCl could avoid lignin condensation, decrease slurry slag, and improve bleaching ability. The solvent recycling process only needs vaporizing, distilling and drying. Thus, the investment and transferring cost would be sharply decreased. The invention realizes cleaning producing process without discharging of black liquor.

Description

technical field [0001] The invention relates to a clean pulping method for bleachable pulp of rice and wheat straw. Specifically, the present invention relates to a clean production method of cooking rice-wheat-straw raw materials with acetic acid aqueous solution containing acidic calcium chloride and sodium chloride, pickling, water-washing, recycling and drying to realize bleachable pulp of rice-wheat-straw. Background technique [0002] The pulp and paper industry is one of the main industries that seriously pollute the water environment in my country. Although the alkali recovery by combustion method is an effective method to eliminate the pollution of cooking black liquor, it shows great incompatibility to the black liquor of rice and wheat straw. And my country is a country that lacks forest resources and is rich in non-timber raw materials, especially rice and wheat straw raw materials. Therefore, it is impossible not to use non-wood fiber raw materials. Only by impr...

AI Technical Summary

Problems solved by technology

For factories that have built a secondary biochemical treatment system for wastewater in the middle section outside the factory, although the discharged wastewater meets the national discharge standards, the treatment fee is generally 0.8-1 yuan / m3, which is equivalent to an increase of 160-200 yuan per ton of pulp cost

[0010] (3) Large construction investment and long payback period:

[0019] (1) Adopting acetic acid as the first section, and the two-stage cooking of the second section with acetic acid-ethanol mixture complicates the process, correspondingly increases equipment investment, and also increases operational control difficulty;

[0020] (2) The mixture of crude lignin, acetic acid, ethanol, and water adopts an evaporator (equivalent to a still), and the double tower separation operation is very difficult. Although the boiling point of acetic acid is higher than that of water, due to the existence of alcohol and sulfuric acid, acetic acid and ethanol It is easy to generate ethyl acetate whose boiling point is much lower than that of water, and it evaporates from the evaporator, while more water remains, so that the crude lignin in the evaporator is easy to precipitate and even scale, causing the heating tube to be blocked and making the The entire recovery system is inoperable; and the removal of scale is also very difficult;

[0021] (3) It takes a long time to remove the residual ethanol in the pulp by steam stripping, which not only increases the steam consumption, but also reduces the production capacity of the cooking pot

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