ailored to your industry, wastewater composition and treatment needs, Conqinphi offers one-stop customized evaporation solutions—from design, manufacturing to ...
Petrochemical refineries across Southeast Asia are increasingly confronting stringent environmental regulations that mandate zero liquid discharge from process operations. When a major petrochemical complex in Thailand faced a government-imposed deadline to cease all wastewater effluent within 24 months, their engineering team evaluated multiple technology pathways before selecting CONQINPHI to design and implement a comprehensive recovery solution. This case study details how our 26TPH sodium sulfate dual-effect MVR evaporative crystallizer system enabled the facility to not only achieve compliance but also establish a profitable byproduct recovery operation that improved overall plant economics.
The complex, which operates a fluid catalytic cracking unit and associated alkylation processes, generated approximately 600 tons per day of sulfate-rich wastewater containing 14-18% sodium sulfate by weight. Previous treatment through conventional biological systems proved ineffective due to the high salinity, while direct discharge to coastal waters had become environmentally and politically untenable. The facility’s technical committee determined that a large-scale dual-effect MVR evaporative crystallizer represented the only viable path to process all wastewater internally while recovering sufficient value to justify the capital investment.
The incoming wastewater stream presented several characteristics that demanded careful system engineering:
• High sulfate concentration: Sodium sulfate levels fluctuating between 14% and 18% required robust crystallization control to manage supersaturation and prevent uncontrolled nucleation
• Organic contamination: Trace hydrocarbons and sulfonated organics from upstream processing complicated crystal purity achievement and created foaming tendencies during evaporation
• Large scale requirement: The 26 tons per hour design capacity placed this installation among the largest MVR evaporative crystallizer systems deployed in the regional petrochemical sector
• Energy cost sensitivity: Thailand’s industrial electricity pricing structure demanded maximum energy efficiency to ensure operational economics
The facility required a sulfate sodium dual-effect MVR system capable of continuous operation at design capacity while producing anhydrous sodium sulfate meeting GB/T 6009-2014 Grade I specifications (≥99.0% Na₂SO₄, white crystalline appearance). Recovered condensate needed to achieve boiler feedwater quality standards for internal reuse, effectively closing the plant’s water balance.
Our process development team conducted a twelve-week engineering study including laboratory crystallization kinetics analysis and pilot-scale evaporation trials. Based on these findings, we proposed an innovative sulfate sodium dual-effect MVR evaporative crystallizer configuration that optimized the trade-offs between energy efficiency, capital cost, and operational complexity:
• First-effect falling-film evaporator concentrating feed from 16% to 28% solids using mechanically recompressed vapor
• Second-effect forced-circulation crystallizer completing concentration and achieving crystal growth under controlled supersaturation conditions
• Split mechanical vapor recompression with dedicated compressors sized for each effect’s specific vapor volume and compression ratio requirements
• Integrated organic stripping removing volatile contaminants before crystallization to ensure product purity
The installed system represents one of the highest-capacity MVR evaporative crystallizer installations serving the Southeast Asian petrochemical industry. Key design specifications include:
Parameter | First Effect | Second Effect |
Feed capacity | 26,000 kg/h | 15,600 kg/h (concentrated) |
Evaporation capacity | 10,400 kg/h | 7,800 kg/h |
Total system evaporation | 18,200 kg/h | — |
Compressor power | 680 kW (centrifugal) | 420 kW (roots type) |
Product output | — | 4,200 kg/h Na₂SO₄ |
Operating temperature | 85°C | 58°C |
Specific energy consumption | 15.5 kWh/ton evaporation | 18.2 kWh/ton evaporation |
Overall energy efficiency | 2.1 kg evaporation/kWh | — |
Crystal purity | — | ≥99.2% Na₂SO₄ |
The dual-effect MVR evaporative crystallizer configuration leverages the thermodynamic advantages of staged evaporation while maintaining the energy efficiency benefits of mechanical vapor recompression. Vapor from the second-effect crystallizer, after compression to the first effect’s operating pressure, combines with the first effect’s own recompressed vapor to provide the required heat input. This arrangement achieves approximately 35% energy savings compared to a single-effect MVR system of equivalent capacity.
Given the aggressive nature of sulfate solutions at elevated temperature, CONQINPHI specified premium materials throughout the sulfate sodium dual-effect MVR system:
• Heating surfaces: Duplex stainless steel 2205 cladding on carbon steel substrate, providing excellent resistance to sulfate stress corrosion cracking
• Crystallizer body: Titanium Grade 2 construction for the second-effect vessel and internals, ensuring 20-year design life
• Compressor wetted parts: Super duplex 2507 stainless steel impellers and diffusers resistant to chloride and sulfate attack
• Piping and valves: 316L stainless steel with PTFE-lined components for critical control elements
Given the project’s tight regulatory timeline, CONQINPHI employed a modular fabrication strategy that minimized on-site construction duration. The MVR evaporative crystallizer system was manufactured across four major skid assemblies at our production facility:
• Pre-fabricated first-effect module complete with heating elements, vapor separators, and internal piping
• Second-effect crystallizer module including circulation pumps, draft tube crystallizer, and mother liquor return system
• Compressor and drive module housing both vapor compression trains with integrated lubrication and control systems
• Solids handling module incorporating centrifuge, fluid bed dryer, and product conveying equipment
Site installation required just 10 weeks from module arrival to mechanical completion, with commissioning and performance testing completed within an additional 6 weeks. The entire project was delivered 3 weeks ahead of the regulatory compliance deadline.
CONQINPHI provided comprehensive training programs ensuring the client’s operations team could independently manage the sulfate sodium dual-effect MVR evaporative crystallizer system. Training encompassed:
• 40 hours of classroom instruction covering process fundamentals, control system operation, and troubleshooting protocols
• Two weeks of hands-on commissioning participation with CONQINPHI engineers guiding startup, shutdown, and abnormal condition response
• Digital twin simulation allowing operators to practice emergency scenarios without risking actual equipment
After 20 months of commercial operation, the dual-effect MVR evaporative crystallizer system has delivered measurable outcomes across multiple dimensions:
Regulatory Compliance: The facility achieved zero liquid discharge status 3 weeks ahead of the government deadline, avoiding potential production restrictions and penalties estimated at $2.4 million annually. Environmental agency inspectors have since designated the installation as a reference site for other petrochemical facilities facing similar compliance requirements.
Water Balance Closure: The system produces 18,200 tons per day of distilled-quality condensate, fully satisfying the complex’s boiler makeup water demand and cooling tower blowdown replacement requirements. External freshwater purchases have been reduced by 78%, generating annual savings of $890,000.
Byproduct Revenue: Recovered anhydrous sodium sulfate, sold to regional detergent and glass manufacturing customers at $195 per ton, generates $2.7 million in annual revenue. Product quality consistently exceeds Grade I specifications, commanding a 12% price premium over standard industrial grade material.
Energy Performance: Actual specific energy consumption tracks within 4% of design predictions, confirming the accuracy of our thermodynamic modeling. Annual electricity costs of $1.42 million compare favorably against the $4.8 million operating cost projection for an equivalent steam-driven multi-effect alternative.
Operational data demonstrates exceptional system reliability. The MVR evaporative crystallizer has maintained 95.8% on-stream availability, with scheduled maintenance confined to annual compressor inspections and quarterly heat transfer surface cleaning. The dual-effect configuration provides inherent operational flexibility, allowing sustained production at 60% capacity using either effect independently during maintenance activities.
Vibration monitoring and oil analysis on both compressors show no degradation trends, supporting CONQINPHI’s projected 10-year major maintenance interval.
CONQINPHI has established a distinguished track record in large-capacity MVR evaporative crystallizer systems for demanding petrochemical and chemical processing applications. Our engineering competencies include:
• Thermodynamic system optimization: Advanced process simulation using proprietary models validated against extensive operating data from installed systems
• Large-scale compressor engineering: In-house design and manufacturing of centrifugal and positive displacement compressors up to 1,500 kW for evaporation duties
• Crystallization process control: Proprietary supersaturation management algorithms preventing unwanted nucleation and ensuring consistent crystal quality
• Modular execution methodology: Fabrication and quality control procedures enabling rapid, predictable site installation regardless of project location
While this installation serves the China petrochemical market, CONQINPHI’s sulfate sodium dual-effect MVR technology has been successfully deployed across Indonesia, Malaysia, India, the Middle East, and South America. Our international project execution team manages logistics, customs clearance, and local contractor coordination to ensure seamless delivery regardless of destination.
Regional service centers in Bangkok, Jakarta, Dubai, and São Paulo provide responsive spare parts availability and technical support, minimizing potential downtime for critical evaporation equipment.
Petrochemical facilities facing zero-liquid-discharge mandates or seeking to recover value from process wastewater streams require proven large-scale evaporation technology. CONQINPHI’s engineering team offers comprehensive project development services, from initial conceptual design through detailed engineering, fabrication, installation, and commissioning.
Contact our petrochemical specialists today to discuss your specific requirements. Whether you are evaluating sulfate sodium dual-effect MVR systems, exploring alternative salt recovery configurations, or upgrading existing evaporation capacity, CONQINPHI provides the technical depth and execution experience to deliver successful outcomes on the most demanding schedules.
220 meters north of the intersection of Zhanqian Avenue and Lanzhou East Road in Jiaozhou City, Qingdao, Shandong Province, China.
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