500t/d Rubber Additives M-Water Quadruple Effect Evaporator

I. Introduction to the Four-Effect Evaporator

This four-effect evaporator is a continuous evaporation system designed by our company specifically for this rubber additive manufacturer. It is suitable for the high-COD, high-color, and high-salt wastewater generated during the production of accelerator M (2-mercaptobenzothiazole). The system adopts a "four-effect co-current + forced circulation + staged crystallization" process, with an evaporation capacity of 500t/d (21t/h), a steam consumption of ≤0.22t/t water, and can achieve >95% condensate reuse and high-value utilization of impurities, helping customers achieve "zero emissions" and "dual carbon" goals.

II. Technical Background of the Four-Effect Evaporator

Typical wastewater quality of rubber additive M: Na₂SO₄ 120-160g/L, M residue 8000mg/L, COD 30000-50000mg/L, color 10000 times, temperature 90℃. Traditional single-effect or triple-effect evaporators have high steam consumption (0.35-0.4 t/t water), are prone to coking and foaming, and have high operating costs. This equipment, based on a four-effect heat transfer stage and forced circulation flow, incorporates a module for enriching and incinerating M residues and refining sodium sulfate, effectively solving the two major pain points of energy consumption and resource utilization.

III. Process and System Composition

1. Four-Effect Co-current Forced Circulation: Live steam enters only the first-effect heating chamber. The heat transfer temperature difference between each effect is ≥7℃, the vacuum gradient is -70→-82→-90→-95kPa, and the evaporation temperature is 80→68→56→45℃, effectively inhibiting the high-temperature polymerization of M residues.

2. Fractional Crystallization: Utilizing the solubility difference between Na₂SO₄ and M residue, the triple-effect effluent first enters the DTB crystallizer (low-temperature side) to precipitate anhydrous Na₂SO₄. After centrifugation, the dry basis purity is ≥99%, and the whiteness is ≥85. The M-rich mother liquor is returned to the second-effect evaporator for concentration to 65% (solids), pumped into the enrichment tank, and periodically sent to the plant's RTO for incineration. The system has no external discharge of impurities.

3. Anti-coking and Defoaming: The heat exchanger uses duplex steel + TAi composite tubes, designed with a forced flow rate of 3.5 m/s. The evaporation chamber is equipped with a double-layer inclined plate + wire mesh demister, with online defoamer injection, resulting in a foam layer <150 mm. The cleaning cycle has been extended from 2 days to 12 days.

4. Deep Condensate Treatment: The condensate from the fourth-effect evaporator undergoes activated carbon decolorization + ozone catalytic oxidation, achieving COD ≤120 mg/L and color ≤20 times. It is then reused as makeup water for circulating cooling water, saving 180,000 tons of fresh water annually.

IV. Core Equipment Parameters

1. Total Evaporation: 21t/h (500t/d)

2. Steam Consumption per Unit: 0.22t/t water (fourth effect); MVR interface reserved, ≤0.08t/t water after upgrade

3. Heat Transfer Area: First effect 320m², Second effect 280m², Third effect 240m², Fourth effect 200m², Total 1040m², Design margin 20%

4. Compressor Reserved: Speed-increasing box-type centrifugal compressor, temperature rise 20℃, motor power 1800W kW, can be cut and matched later to achieve full MVR

5. Crystallizer: Two Φ2800DTB units, one in Oslo, material 2507 + rubber lining, crystal slurry density 25-35%

6. Centrifugal Drying: Two-stage piston pusher centrifuge + paddle drying line, product moisture content ≤0.3%, packaging capacity 3t/h

V. Performance and Advantages

1. Low Energy Consumption :Four-effect + split-range + heat pump recycling, steam cost is reduced by 28% compared to three-effect; after the full MVR upgrade, steam consumption is almost "zero".

2. Resource Utilization: Na₂SO₄ reaches the recovery standard, and the external sales price increases from 300 yuan/t to 650 yuan/t; M residue is enriched and incinerated, with a calorific value recovery of 3.2GJ/t.

3. Stable Operation: Forced circulation + online cleaning, annual operating time ≥8000h, equipment availability >98%. 

4. Space Saving: Modular steel structure frame, single-story layout, occupying only 480m², 30% less space than traditional four-effect compressors.

5. Intelligent Control: DCS+SIS dual redundancy, key parameters with two-out-of-three voting; remote monitoring control software, fault SMS push notifications.

VI. Economic and Environmental Benefits

Based on steam price of 180 yuan/t and electricity price of 0.65 yuan/kWh, the four-effect compressor saves approximately 11 million yuan annually in steam costs; resource utilization of miscellaneous salts generates an additional 9 million yuan annually. Carbon reduction per ton of water is 0.32tCO₂, resulting in a total annual emission reduction of 48,000 tons.

VII. Service and Upgrade Path

1.One-stop turnkey solution for process packages, design, manufacturing, installation, commissioning, and operation and maintenance.

2.48-hour response time, spare parts warehouses nationwide, and a remote cloud diagnostic center online in real time.

Subsequently, an MVR compressor can be connected via the live steam inlet bypass, allowing for a 72-hour downtime cutover, reducing steam consumption to 0.08t/t of water in one step.