Process for incinerating cotton linter black liquor and recycling alkaline by utilizing heat conduction oil boiler

Abstract

The invention discloses a process for incinerating cotton linter black liquor and recycling alkaline by utilizing a heat conduction oil boiler, which belongs to the technical field of pulping waste water treatment. The process comprises the following steps: (a) cotton linter pumping black liquor with the mass concentration of about 6 percent from an extracting workshop section is heated, evaporated and thickened by a multiple-effect evaporator which takes cyclic heat conduction oil as a heat source till the mass concentration of the black liquor reaches 40-50 percent; (b) the thickened black liquor is sprayed into the heat conduction oil boiler for combustion, the heat energy is recovered by the heat conduction oil in a heating surface, and sodium carbonate generated by the combination of sodium hydroxide and carbon dioxide in the waste water is discharged out of the boiler; (c) the generated sodium carbonate is reduced into alkaline by adopting a hydrated lime causticizing method, and the alkaline resources are recycled for productive cycle and utilization. The process saves the construction funds by one third, saves energy by 30 percent and reduces the operation cost by 25 percent compared with the general alkaline recovery process, has high heat energy utilization ratio and zero CODcr index of discharged waste water and can thoroughly and effectively solve the pollution of cotton linter black liquor.

Description

technical field [0001] The invention relates to a process for treating and recovering alkali from black liquor in the cotton linter pulping industry, in particular to a process of using a heat-conducting oil boiler to incinerate linter black liquor and recover alkali, and belongs to the technical field of pulping wastewater treatment. Background technique [0002] At present, the black liquor treatment process produced by domestic alkaline cotton linter pulping enterprises only adopts physicochemical and biochemical methods to treat wastewater. This method is 3% (equivalent to COD) for treatment concentration. cr The black liquor wastewater below 30000mg / l) can also reach the standard, and the original wastewater concentration from self-made pulp reaches more than 6%. Only relying on these methods can not achieve the discharge of the standard, and the treatment of these high-concentration organic wastewater (concentration 3% Above) the present domestic and even international...

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Problems solved by technology

[0004] Pulping enterprises use black liquor jet steam alkali boilers, which have the following disadvantages: (1) The steam generated by black liquor jet steam boilers cannot be completely recovered, or even not recycled, resulting in a great waste of energy; (2) The heat energy utilization of the whole system (3) The manufacturing cost and operating cost of steam boilers are high, and supporting water treatment equipment and oxygen removal equipment are required; (4) Black liquor jet steam boilers pursue large scale too much and are not suitable for the existing pulping enterprises in my country The national conditions of most medium-sized enterprises are not suitable for the cotton linters industry whose scale is lower than medium-sized

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