Measures to improve the production capacity of Kay membrane filters

      The knowledge of belt filter press talk about measures on how to improve the production capacity of Kay membrane filter

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The primary brine adopts the Kay membrane filtration process of the pre-processor, with a design capacity of 80,000 t/a caustic soda production equipment, of which ionic membrane caustic soda is 60,000 t/a and diaphragm caustic soda is 20,000 t/a. The process adopts the process of floating up the crude salt water with pressurized dissolved gas and salt mud and then filtering by Kay membrane. There are 3 sets of Kay membrane filters, each membrane filtering area is 100 m2; The clarification bucket settled for clarification. The construction of the ion-exchange membrane electrolysis device started in January 2004, and it was successfully started up in June 2004 to deliver qualified brine to the diaphragm electrolysis device.
Since the start-up, the device has been running relatively stable, the Kay membrane filtration pressure drop is controlled at 0.030.05 MPa, the filtration time is greater than 1 500s, and the conventional chemical method analyzes the SS< 1 mg/L and the mass concentration of calcium and magnesium in the brine <1 mg/ L, until it cannot be detected.

1 Kay membrane filtration process of primary brine
The brine is added to NaC10 and then enters the brine storage tank, and the ion-exchange membrane electrolysis returns to the dechlorinated dilute brine. Adds BaC12 to the clarification tank to remove SO: then enters the chemical brine storage tank, and the diaphragm electrolysis evaporation returns the water to the brine storage tank (when the return water When 5S042-high is included, BaC12 must be added in addition to S《一) The temperature of the brine is controlled to 5055℃ by the heat exchanger for salt, and the crude brine is added with alkali or acid (when the evaporated backwater contains high alkali) to adjust the pH value to 9-10o M and OH after the reaction in the crude brine pool , In the pressurized dissolved gas tank, the dissolved gas enters the human venturi mixer and is mixed with the flocculant FeC13, the Mg(OH)2 particles agglomerate and become larger and enter the pretreatment device, and the dissolved gas is released. Mg(OH)2 is in the form of floating mud Float to the upper part, drain to the salt mud pool, and add Na2CO3 into the reaction tank from the pre-processor brine, cCa2′ reacts with COA to form CaC03, and then Na2S03 is added to adjust the oxidation-reduction potential to remove free chlorine, and enter the intermediate tank. The CaC03 and SS are removed by pumping to the Kay membrane filter to produce crude brine, and the refined brine is sent to diaphragm electrolysis and ion-exchange membrane electrolysis secondary brine.
The process is characterized by simple process and convenient operation; high degree of automation; low labor intensity; PLC control is adopted for the filter, and the device runs reliably; the quality of the brine is stable, and the control points of the SS 2 brine production process in the filtered brine
Through 1.5 years of operation, in the production process of mixed brine, the plant combined its own production characteristics and summarized measures to improve the production capacity of Kay membrane filters and meet production requirements.

2.1 Refined Jing is added to f
2.1.1 Control of excess alkali
Maintaining a certain amount of over-alkaline is necessary to reduce the content of calcium and magnesium ions in refined brine and improve current efficiency. Based on production experience for a long time, the factory has controlled the excess NaOH in refined brine by 0.10.3 g/L and Na2C03 by 0.30.5 g/L. In order to keep the over-alkaline amount of refined brine up to the standard, the excess NaOH at the outlet of the crude brine baffle tank is 0.2-0.4 g, and the mass concentration of Mg2 in the brine at the outlet of the preprocessor is 1 mg/L. Due to the large amount of brine mixed in the production, the halogen mixing rate is 85% when the diaphragm electrolysis is driven alone, and the halogen mixing rate is about 60% when the diaphragm and ion-exchange membrane electrolysis are driven at the same time. The calcium and magnesium ion content of the brine in the factory is required. It is higher than the original salt. The mass concentrations of cCa2 and Mg 2 are 1.4g/L and 0.2g/L respectively. According to the normal operation, only the post-reaction tank is used to remove calcium. If the amount of CaCO3 generated is too large, it will bring more to the Kay membrane filter. It is a big burden, so according to the actual situation, it is necessary to pre-remove a part of cCa2 in the preprocessor. Under normal circumstances, the cCa2 mass concentration of the brine baffle is 300800mg/L, and the cCa2 mass concentration of the pretreatment outlet brine is controlled at 200-600m g/L. If the cCa2 content is too low, it is not conducive to the formation of CaC03 on the surface of the Kay membrane. Bridge the filter aid layer, causing small particles of Mg(OH)2 flocculent sediment to directly enter the surface of the membrane, blocking the membrane pores, and increasing the pressure difference and shortening the filtration cycle. When the cCa2:M E2 10×1 in the brine from the pre-processor is discharged, the filtering effect is better.

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