5t/h Ammonia Nitrogen Wastewater MVR Evaporation Crystallization Equipment

I.Equipment Positioning

This is a 5t/h (120t/d) MVR evaporation and crystallization line for ammonia nitrogen wastewater, positioned for a zero-discharge scenario characterized by "high ammonia nitrogen, high salinity, and small water volume": Influent NH₃-N ≤ 2000mg/L (commonly 500–1200mg/L), TDS 3–12%, COD ≤ 5000mg/L; Effluent condensate NH₃-N ≤ 15mg/L, TDS ≤ 200mg/L, reused in workshop wash water or circulating cooling towers; The crystallized product is mainly ammonium chloride, with a purity ≥ 97% and a water content ≤ 5%, which can be directly sold as agricultural fertilizer or used internally.

II.Main Process Package (Single Line Diagram)

This is a three-stage process: "Pretreatment → MVR forced circulation evaporation → Crystallization → Centrifugation → Mother liquor drying." All equipment can be arranged within an 8m × 6m × 13.5m frame, occupying an area of approximately 50m².

1.Pretreatment

Coagulation and Flotation: Add Ca(OH)₂ + PAC/PAM to remove SS, grease, and some silica, achieving an effluent turbidity ≤20 NTU;

Ammonia Stripping (Optional): When NH₃-N > 3000 mg/L, first pass through a pH 11 stripping tower with a gas-liquid ratio of 300:1, achieving a removal rate of 60–70%, reducing the subsequent evaporation load;

Precision Filtration: 50 μm metal mesh + 1 μm bag filter to ensure the evaporator does not clog.

2.MVR Forced Circulation Evaporator

Evaporation Capacity: 5t/h (5t/h inlet water, 4t/h concentrated water, 1t/h outlet concentrated liquid, specific gravity 1.25–1.30);

Evaporation Temperature: 70–75℃ (low temperature to prevent ammonia escape), vacuum degree −65kPa;

Heater: Double-pass, TA2 titanium material, heat exchange area 280m², in-tube flow velocity 2.3m/s, resistant to Cl⁻ pitting corrosion;

Compressor: Roots type, temperature rise 18℃, processing capacity 4200kg/h of secondary steam, shaft power 280kW, frequency conversion 30–55Hz;

Circulation Pump: Magnetic drive, flow rate 1200m³/h, head 18m, power 45kW;

Condensate: After secondary stripping in a deammoniation tower (gas-liquid ratio 200:1), NH₃-N ≤15mg/L, 100% reuse rate.

3.Continuous Crystallizer (DTB type): Effective volume 8 m³, residence time 4 h, slurry density 25% (wt), cooling jacket removes 120 kW of crystallization heat; average particle size 0.8–1.0 mm, wet salt moisture content after centrifugation dehydration 3–5%, output ≈ 550 kg/h (4800 t/year).

4.Mother Liquor Dryer (Vacuum Rake Blade): Processing capacity 0.5 t/h (moisture content 70%→10%), evaporation rate 12 kg/m²·h, drying area 40 m²; heat source: 75℃ condensate waste heat + 0.3 MPa fresh steam supplement, total steam consumption 120 kg/h; dried mixed salt is directly rigidly landfilled after bagging, the system ultimately has no liquid discharge.

III.Energy Consumption and Operating Costs (based on 8000h/a)

1.Electricity Consumption: Compressor 280kW + Pump/Fan 60kW = 340kW, electricity consumption per ton of water 68kWh;

2.Steam: Preheating at start-up 0.6t, continuous steam replenishment 0.12t/h, steam consumption per ton of water 24kg;

3.Reagents: Liquid alkali, PAC, defoamer total 2.8 yuan/ton of water;

4.Comprehensive operating cost ≈ 55 yuan/ton of wastewater (electricity price 0.65 yuan/kWh, steam price 220 yuan/ton).

IV.Key Design Details

1.Ammonia Emission Prevention: The evaporator, condenser, and vacuum pump are all connected to a 0.5% dilute sulfuric acid absorption tower, tower diameter Φ800mm, packing height 4m, NH₃ absorption rate ≥99%, and the by-product 15% ammonium sulfate solution is reused. 

2. Anti-scaling/Foaming: Online addition of 2-3 ppm high-temperature defoamer; Automatic switching to 80℃ hot water for 3 minutes backwash every 8 hours, extending the cleaning cycle to 21 days.

3. Material Selection: Parts in contact with materials: TA2 titanium (heating pipes, separator, circulation pipes); Secondary steam side: 2205 duplex steel; Centrifuge drum: 2507 super duplex steel, lifespan ≥ 10 years.

V.Investment and Delivery

1.Equipment cost: MVR main unit 3.2 million + crystallization centrifuge 900,000 + mother liquor drying 700,000 + pretreatment 600,000 = 5.4 million (including tax);

2.Installation and commissioning: 45 days (modular skid-mounted, on-site piping and wiring only); 

3.Warranty: 5-year warranty for the main unit, 30,000 hours of compressor service without disassembly and inspection, performance guarantee: evaporation capacity ≥ 5t/h, NH₃-N removal rate ≥ 99%, comprehensive energy consumption per ton of water ≤ 70kWh.

VI. Application Performance

1.A Shandong agrochemical company: A 5t/h ammonium chloride wastewater MVR system has been operating for 28 months, achieving NH₃-N 1100mg/L → condensate 8mg/L, with ammonium chloride products meeting the GB/T2946-2018 agricultural grade standard.

2.A fine chemical industrial park in Heilongjiang: The 5t/h MVR system serves as the terminal treatment for high-ammonia nitrogen mother liquor in the park, combined with biochemical and Fenton processes to achieve zero wastewater discharge.

In summary, by 2025, the 5t/h ammonia nitrogen wastewater MVR evaporation crystallization equipment will be a highly standardized, modular, and proven turnkey system, widely applicable to the treatment of high-ammonia nitrogen and high-salinity wastewater and the resource recovery of ammonia salts in industries such as pesticides, pharmaceuticals, rare earths, and battery recycling.