Multiple Effect Distillation
Components and Specifications
Feedwater Preheater The multi-effect still's feedwater is preheated in the condenser to 180°F - 190°F (82° - 88°C), and then further heated in the feedwater preheater. The preheaters are 316L stainless steel, double-tube sheet shell and tube heat exchangers.
Evaporators 316L stainless steel evaporator shells are polished to a 25 Ra finish and then electropolished. The tube bundle is a U-tube design with 316L stainless steel tube sheets, 316L stainless steel tube supports, and titanium tubes. (Optional 316L SS Tubes)
Separators Separators are constructed of 316L stainless steel, polished to a 25 Ra finish and then electropolished. The patented vapor separator consists of a four-stage steam separation process to insure endotoxin removal during high and low flow conditions.
Pressure Vessel Evaporators, separators, shells, and heat exchanger tubes are manufactured to ASME Section VIII, Division I specifications and rated at 150 psig (10.3 bar) and 400°F (204°C). International code registrations are available.
Insulation Evaporators, separators, and preheaters are precoated with Thermolux Teflon® and insulated with high-density, chloride-free fiberglass. Lagging is polished stainless steel to 10 Ra.
Condensers Condenses the still's final effect steam and vents non-condensible gases to the atmosphere. The 316L stainless steel shell and tube, double tube sheet heat exchangers are electropolished.
Skid and Frame Welded structural steel and tubing are coated with phenolic finish. Optional stainless steel.
Piping 316L stainless steel, orbital-welded construction. 25 Ra finished and electropolished. Gaskets are Teflon® encapsulated EPDM on hot water and steam and EPDM on cold water.
Power Three-phase and single-phase service. 50 or 60 cycle.
Electronic Control The still is equipped with a comprehensive PLC control package with operator/machine interface and alarms for pressure, levels, temperature, and conductivity. Steam generators are equipped with PLC control package with operator/machine interface and alarms for feedwater pressure and evaporator levels.
Instrumentation Local and operator/machine interface for pressure, temperature, levels, and conductivity.
Feedwater Pump System 316 stainless steel centrifugal pump; pump motor is a totally enclosed, fan-cooled design (TEFC). Note: Feedwater pump is not required when the feedwater pressure exceeds 35 psig (2.4 bar) over the heating steam pressure.
Documentation Validation Operation, Instruction and Maintenance Manual, drawings, component literature, FAT documentation, Software Audit and ASME certifications, and material certificates are provided to support validation requirements.
New Design Features for Optimal Performance and Reliability
- PID level controllers for optimal feed water level control in the evaporator columns.
- Condenser is double tube sheet and tube heat exchangers to condense and cool the pure steam as WFI.
- Feedwater preheaters are double tube sheet, shell and tube heat exchangers for long term reliability.
- New evaporator gasket design for optimal seal.
- Extended 5 year warranty on the titanium U-tube bundle. The U-tube design addresses the issue of thermal cycling by allowing the tubes to expand and contract freely.
- Shell-Side Evaporation Design
- Ensures heat transfer surface will shed potential scale formation
- Submerged-tube rising-film design eliminates dry tube “hot spots”