Evaporative crystallization method and system

An evaporation crystallization and evaporation tank technology, which is applied in the field of solid-liquid separation, can solve the problems of lax valve closure, pipeline and equipment blockage, device shutdown, etc., achieve low energy consumption and operating costs, improve yield and quality, and ensure The effect of stable operation

Pending Publication Date: 2021-12-17
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing technology usually adopts manual salt discharge method. On the one hand, the operation is based on personal experience, which consumes a lot of manpower, and the salt discharge is not thorough enough, which may easily cause blockage of pipelines and equipment, and in serious cases will cause the shutdown of the device; on the other hand, the salt discharge Residual salt solid particles in the pipeline cause the valve to be closed tightly, and the concentrated feed liquid will continuously enter the separation device, affecting the normal operation of the solid separation device

Method used

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  • Evaporative crystallization method and system
  • Evaporative crystallization method and system
  • Evaporative crystallization method and system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0068] use as figure 1 In the system shown, NaCl industrial wastewater (feed rate 580t / h, TDS 25000mg / L, COD 230mg / L) is evaporated and crystallized (the operating temperature of the evaporation tank is 130°C, and the operating pressure is 0.115MPaG). specifically:

[0069] The evaporation crystallization system includes an evaporation crystallization unit, a slurry discharge and flushing unit, and a solid-liquid separation unit; the evaporation crystallization unit includes an evaporation tank 1 and a material circulation pipeline 104 provided with a material circulation pump 2 (axial flow pump) and a heating chamber 3; The solid-liquid separation unit comprises a solid-liquid separation device and a mother liquor circulation line 115, such as figure 1 The shown solid-liquid separation device comprises 1# solid-liquid separation device 6 (thickener), 2# solid-liquid separation device 7 (centrifuge), mother liquor tank 8, mother liquor circulation line 115 is provided with mo...

Embodiment 2

[0079] Adopt the method for embodiment 1 to carry out Na 2 SO 4 Evaporation and crystallization of industrial wastewater, the difference is that the system in this example is figure 2 Shown, 1# solid-liquid separation device 6 is a suspension separator; Na 2 SO 4 The feed rate of industrial wastewater is 300t / h, the TDS is 55000mg / L, and its COD is 500mg / L; the operating temperature of the evaporation tank is 145°C, and the operating pressure is 0.2MPaG; the critical solid-liquid ratio is 25%, which is taken as the upper layer 0.22 times the ratio of the saturated density of concentrated slurry to the density of water.

[0080] Separated Na 2 SO 4 The water content of industrial nitrate crystals is 7.3%, the yield rate is 98%, and the stable operation time of the system exceeds 1000h. Na in the secondary steam condensate at the top of evaporation tank 1 + , SO 4 2- All are less than 100ppmw, COD2 SO 4 Crystalline nitrate, the operating cost is 864 yuan / tNa 2 SO 4 ...

Embodiment 3

[0082] Adopt the method for embodiment 2 to carry out Na 2 SO 4 Evaporation and crystallization of industrial wastewater, the difference is that the system in this example is image 3 As shown, the saline clear water 111 at the top of the 1# solid-liquid separation device 6 is sent into the material circulation pipeline 104; Na 2 SO 4 The feed rate of industrial wastewater is 350t / h, the TDS is 60000mg / L, and the COD is 750mg / L; the critical solid-liquid ratio is 23%, which is taken as 0.205 times the ratio of the saturated density of the concentrated slurry in the upper layer to the density of water.

[0083] Separated Na 2 SO 4 The water content of industrial nitrate crystals is 5.5%, the yield rate is 97.5%, and the stable operation time of the system exceeds 1050h. Na in the secondary steam condensate at the top of evaporation tank 1 + , SO 4 2- All less than 110ppmw, COD2 SO 4 Crystalline nitrate, the operating cost is 840 yuan / tNa 2 SO 4 Crystalline nitrate. ...

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Abstract

The invention relates to an evaporative crystallization method and system. The operation of discharging lower-layer concentrated slurry from an evaporation tank through a slurry discharging pipeline in the method comprises first front flushing, back flushing, slurry discharging and second front flushing which are sequentially carried out. The solid-liquid ratio of the upper-layer concentrated slurry is monitored online in real time, so that automatic removal of salt slurry in the evaporation tank and automatic cleaning of pipelines are realized, stable operation of the evaporative crystallization process is ensured, the yield and quality of crystallized salt are improved, and meanwhile, the method has the advantages of high applicability, stable device operation and low energy consumption and operation cost.

Description

technical field [0001] The present disclosure relates to the field of solid-liquid separation, in particular, to a method and system for evaporative crystallization. Background technique [0002] In the inorganic salt chemical industry and water treatment industry, the evaporation crystallization process is usually used to precipitate the salt ions in the brine in the form of crystalline salt solids, thereby achieving solid-liquid separation. There are thermal method and cold method for crystallization treatment containing brine: cold crystallization mainly uses cooling medium to lower the temperature of brine until salt crystals are precipitated; thermal crystallization mainly uses multi-effect evaporation, falling film evaporation, steam mechanical recompression technology (MVR, mechanical vapor recompression) and other methods. [0003] For the brine concentration process, as the water in the evaporating tank continues to evaporate, the salt concentration increases. Afte...

Claims

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Application Information

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IPC IPC(8): B01D1/00B01D1/30B01D9/02C02F1/04
CPCB01D1/0094B01D1/305B01D9/0031C02F1/04C02F1/043C02F2301/046C02F2303/14C02F2209/01C02F2209/03C02F2209/10
Inventor 张旭张海珠蔡维婷杨照盛在行
Owner CHINA PETROLEUM & CHEM CORP
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