Step-by-step separation system and method for extracting salts from coking HPF desulfurizing solution by aqueous phase method

Abstract

The invention relates to a step-by-step separation system and method for extracting salts from coking HPF desulfurizing solution by an aqueous phase method. The step-by-step separation system comprises a primary filtering and decolorizing system, a first-level evaporating concentrating and crystallizing system, a second-level concentrating and crystallizing system, a repulping concentrating and crystallizing system, and a vacuum heating and condensing system, wherein the primary filtering and decolorizing system is communicated with the first-level evaporating concentrating and crystallizing system through a mother liquor tank, and is also communicated with the vacuum heating and condensing system; the first-level evaporating concentrating and crystallizing system is communicated with the second-level concentrating and crystallizing system, and is also communicated with the repulping concentrating and crystallizing system and the vacuum heating and condensing system. The step-by-step separation system adopts a step-by-step concentrating and separating technology of the aqueous phase method to separate and extract thiocyanate and thiosulfate from the desulfurizing solution through high separation and cold crystallization; meanwhile, separated secondary salt is recycled, so that the content of the secondary salt in the desulfurizing solution is decreased, the coking desulfurization is carried on in the positive direction, and the desulfurizing efficiency is improved; in addition, the recycled secondary salt has a high economic value, and the pollution problem due to the coking desulfurizing solution is solved.

Description

technical field [0001] The invention relates to a coking HPF desulfurization liquid aqueous phase method for step-by-step separation and salt extraction system and method. Background technique [0002] In the desulfurization process of the coking plant using ammonia as the alkali source and the catalyst of dinuclear phthalocyanine cobalt sulfonate (PDS) catalyst, when the salt content of the desulfurization liquid reaches 350g / L, the desulfurization efficiency is significantly reduced, and a part of the desulfurization liquid must be discharged. The approximate composition of the desulfurization solution is as follows: (NH 4 ) 2 S 2 o 3 : 30-50 g / L; NH 4 CNS: 120-160 g / L; pH: 8.80. At present, domestic coking desulfurization liquid generally does not have advanced treatment, and is only sprayed on coal piles as water for coal preparation. This method only solves the problem of desulfurization liquid removal, and there is no waste liquid on the surface, but it does not ...

AI Technical Summary

Problems solved by technology

After the sulfide enrichment in the desulfurization liquid, on the one hand, the desulfurization effect is seriously reduced, and on the other hand, it causes serious corrosion to the production system

Because the desulfurization liquid contains thiocyanate ions, it cannot be biochemically treated. If the desulfurization liquid is directly discharged, it will seriously pollute the environment

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