Triple-effect salt separation

Process principle

1. Three-effect cross-flow evaporation

The first effect uses a combination of falling film + forced circulation to bear 65-70% of the evaporation load; the second and third effects are pure forced circulation and have strong anti-fouling capabilities. The counter-flow/cross-flow operation mode can be switched online according to the salt solubility curve to ensure that the temperature difference between each effect is ≥8°C, the system vacuum gradient is -70→-88→-95kPa, and the evaporation temperature is 80→65→50°C, effectively avoiding the thermal decomposition temperature zone.

2. Split-pass crystallization

Utilizing the target salt solubility intersection point, DCS is used to accurately control the crystal slurry density and supersaturation degree ΔC<3g/L, and sequentially precipitate insoluble salts, medium-soluble salts, and easily soluble salts. A single set of equipment can separate 2-3 types of salts, with a separation coefficient of ≥98%.

3. Intelligent cleaning and anti-scaling

CIP is automatically triggered when the pipe wall temperature difference is >2°C or the vacuum drops by 2kPa. Acid-base + chelating agent + oxidant are alternately cleaned, and the cleaning cycle is extended from 3 days to 10-15 days; online EDTA cycle protection, titanium corrosion rate is <0.01mm/a.

System composition

1. Preheating unit: plate + tube two-stage, using secondary steam and condensed water to heat the incoming water to the boiling point -5°C, with a heat recovery rate >90%.
2. Three-effect evaporation main body: first-effect falling film chamber, second-effect and three-effect forced circulation chamber, material 2205/2507/titanium composite optional, design margin 25%, ensuring no leakage for five years.
3. DTB/OSLO crystallizer: selected according to particle size requirements, built-in guide tube and baffle ring, crystal slurry density 20–35%, d50=0.5–1.2mm adjustable.
4. Centrifugal drying: double-stage piston centrifugal + closed fluidized bed, nitrogen protection, product water content ≤0.3%, oxygen content <3%, explosion-proof ExdⅡBT4.
5. Automatic control system: DCS+SIS dual redundancy, key parameters are voted out of 2 out of 3; MVR/steam mechanical recompression interface is reserved, and the unit steam consumption can be reduced to 0.08t/t water after upgrade.

Performance parameters

1. Processing capacity: 5–30t/h (serialized module)

2. Steam unit consumption: 0.24–0.28t/t water (three effects); after upgrading MVR ≤ 0.08t/t water

3. Power consumption: 18–25kWh/t water (three effects); 22–30kWh/t water after MVR

4. Water production rate: ≥85%, TDS of condensed water ≤150mg/L, reused to circulating water or pure water station

5. Salt purity: NaCl, NH₄Cl, Na₂SO₄, sodium hydroxyl ≥ 99%, meeting the standards of ion membrane, dry-based industrial salt, and electroplating grade

6. Cleaning cycle: ≥10 days; Design life: ≥20 years

Application areas

1. Chemical industry: dye mother liquor, H acid wastewater, T acid wastewater

2. Pharmaceutical: cephalosporin intermediate high-salt residual liquid, vitamin C centrifuge mother liquor

3. Fluorosilicone: fluorocarbon alcohol washing liquid, silicone-containing salt wastewater

4. Coal chemical industry: desulfurization waste liquid (NH₄SCN+(NH₄)₂SO₄+(NH₄)₂S₂O₃)

5. Battery material: ternary precursor sodium sulfate/lithium sulfate mixed salt

Economic benefits
Taking 10t/h and steam unit price of 180 yuan/t as an example, the three-effect system saves 22,000 tons of steam annually, which is equivalent to 4 million yuan in operating expenses; the miscellaneous salt is converted from hazardous waste of 2,000 yuan/t to a product of 800-1,500 yuan/t, and the annual new income is 12-20 million yuan; the investment payback period is 1.5-2.0 years (including government subsidies).

Environmental protection and social value
The carbon reduction per ton of water is 0.25tCO₂, and the miscellaneous salt reduction rate is >90%, completely solving the problem of "mixed salt hazardous waste"; the reuse of condensed water reduces the fresh water consumption in the factory area by 30-50%, helping enterprises to create "waste-free factories" and "green supply chains".

Service and guarantee

1. Process package + design + manufacturing + installation + debugging + operation and maintenance one-stop turnkey

2. 48-hour response, nationwide spare parts warehouse, remote cloud diagnosis

3. Provides an upgrade path: triple effect → triple effect + heat pump → full MVR to protect customer investment

4. Jointly build a salt resource utilization laboratory with universities to continuously optimize crystallization kinetics and separation coefficients

Choose "three-effect miscellaneous salt separation and purification equipment" to make every grain of salt valuable and every drop of water reusable!