Double-membrane-method technology for refining brine and equipment for the same

Abstract

The invention relates to double-membrane-method technology for refining brine and equipment for the same. After pretreatment, brine to be treated enters a filtration procedure to form high-concentration nitrate-containing water and refined brine; pretreatment refers to carrying out a removal procedure of calcium and magnesium ions, a removal procedure of ammonium, a reduction procedure and a pH adjusting procedure to the brine to be treated; the filtration procedure refers to the steps that: the pretreated brine is pumped to gas-stripping tubular type membrane module for ultrafiltration, thereby organic impurities, suspended matters and partial precipitates of the brine are intercepted; pressure raising is carried out to the brine which permeates a tubular type membrane, then the brine directly enters nanofiltration membrane module for nanofiltration; the brine which can not permeate the tubular type membrane returns the removal procedure of calcium and magnesium ions; and in a high pressure state, sulfate ions are intercepted by a nanofiltration membrane to form high-concentration nitrate-containing water, and chloride ions and sodium ions permeate smoothly the nanofiltration membrane to form refined brine. The technology in the invention is simple, low energy consumption, small land-occupation area, low investment and low production cost, a stable operation system, strong impact-resistance load capability and no secondary pollution.

Description

technical field [0001] The invention provides a double-membrane brine refining process and its equipment, in particular to a brine denitrification and other organic matter removal process and the equipment used therein. Background technique [0002] At present, my country's domestic chlor-alkali production technology mainly includes ion-exchange membrane method and diaphragm method. For the soda production process of the diaphragm method, the finished alkali can take away a considerable part of the sulfate radicals. Therefore, in the production process of this process, the accumulation of sulfate radicals is almost non-existent, so there is no need to consider the removal of sulfuric acid in the feed liquid. root. For the ionic membrane alkali production process, on the one hand, the calcium and magnesium ions in the brine will react with the OH- on the anode during the electrolysis process, forming insoluble matter and depositing on the ionic membrane, causing damage to th...

AI Technical Summary

Problems solved by technology

There are problems in this process: (1) adopt barium chloride to remove sulfate radical, barium chloride is expensive, production cost is higher, and poisonous and harmful, difficult to manage, and the barium sulfate precipitation that produces is difficult to handle, often causes the problem of secondary pollution ;(2) HVM TM The tubular membrane is a pertetrafluoroethylene integral tubular membrane manufactured by Singapore Hyflux Company. Although it makes up for the defects of the existing PTEE membrane / PP composite tubular membrane and improves the strength of the membrane, it still adopts the method of terminal filtration. , has the disadvantage of rapid flux decay

Since this process only uses CIM membrane for brine denitrification treatment, there are the following problems: (1) The whole process does not consider the Ca 2+ , Mg 2+ , SS removal, so there are high requirements for brine water quality; (2) The pretreatment process is cumbersome and imperfect, the membrane is easy to clog, and the operating cost is high

Although this process adopts the inorganic membrane cross-flow filter of special structure to realize solid-liquid separation, reduce membrane fouling, and improve membrane flux, but there are still the following problems: (1) using barium chloride to remove sulfate, the added chloride Barium is toxic, difficult to manage, expensive, and high in cost; (2) a large amount of refractory barium sulfate precipitates, resulting in difficulties in post-processing; (3) the presence of barium ions forms secondary pollution, and the risk of membrane fouling increases; (4) There is no ammonium removal device in the system pretreatment, which poses a certain threat to the safe production of chlor-alkali; (5) The ceramic membrane consumes a lot of energy and the investment cost is high

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