A range of Multi-Stage Flash Evaporators has been specifically designed for applications which require large amounts of fresh water with low energy consumption. We have developed and improved this already well-proven method of desalination to produce the most advanced systems available today, offering the highest possible standards in design and manufacture, with particular emphasis on the selection of the best quality materials. Our flash evaporators are available ranging from 50m3/day capacity with 2 stages, through 500m3/day with 6 stages, up to 1500m3/day with 16 to 24 stages.

Features of Caird & Rayner Clark MSF Evaporators

• Low Energy Consumption - High efficiency for utilisation of limited waste heat.
• Low Operating Costs - Electrical power only for pump motors.
• Purpose Built - Designs individually adapted to specified output and heat source requirements.
• Reliability - High quality materials of construction for long-term reliability and availability.
• Low Installation Costs - Factory assembled unit on single baseframe for simple low cost installation.
• Ease Of Operation - Simple start-up and operation to full rated output in less than one hour.
• Fresh Water Quality - High quality fresh water production, suitable for all domestic and technical uses.
• Low Maintenance Costs - Low evaporating temperatures and low brine concentration for extended scale-free operation.
• Automatic Control - Comprehensive automatic control and safety systems for unattended operation.
• Stable Operation - Automatic brine recirculation control system to maintain constant sea water temperature for stable, unattended operation. Operating Principle When water flows into a vacuum chamber at a temperature higher than the saturation temperature of the chamber, instantaneous evaporation of some of the water takes place. This phenomenon is called flash evaporation, and is the principle utilised for the production of fresh water from seawater. In the flash evaporator, seawater is circulated through the vapour condenser tubes of the final stage where it is heated by the transfer of latent heat from the condensing vapour. The seawater passes through the vapour condensers of each stage in series, increasing in temperature. The seawater then enters the tubes of the heat input section, where a further temperature increase takes place to provide the temperature differential needed to promote flash evaporation. In the heat input sections any available source of steam or hot water can be utilised, and it is in this area that the plant is customised to meet the operators specific requirements. The seawater after the heat input section, is regulated to a maximum temperature of 90°C so that scale formation of the heat transfer surfaces is minimised. As all stages of the MSF plant operate under vacuum, even the low grade heat available in a diesel engine fresh water cooling system can be utilised, and in this case the maximum temperature is normally in the range of 75°C to 80°C, but may be’ as low as 65°C. The hot seawater enters the first stage chamber, where flash evaporation takes place as described. The remaining seawater, which has reduced in temperature due to the transfer of latent heat to the vapour, then flows through the remaining stages in turn, each of which operates at a lower pressure and corresponding saturation temperature than the previous stage, thus permitting flash evaporation in each stage. The remaining concentrated seawater, or brine is extracted from the last stage and pumped to waste. The vapour produced in each stage rises to the coldest part of the stage, the vapour condenser tubes, passing through a demister to separate any remaining seawater droplets. The vapour is condensed on the outside surface of the tubes and the distillate is collected in trays. The total distillate produced is extracted from the last stage and pumped to storage. Both the brine and distillate flows utilise the pressure differential between the stages and the flows cascade internally through specially designed channels, reducing the number of external pipe connections and controls. The flash evaporator is supplied as a package unit on a single baseframe, and the scope of supply includes a steam boost feed heater, air ejector system, seawater, distillate and condensate pumpsets, instrumentation and automatic control systems, control panel, chemical injection set, piping and valves. Testing All our MSF Evaporators are subjected to full hydrostatic tests during manufacture, to ensure the integrity of shell, tubes, waterboxes and pipework. On request, or if required by the specification, we can conduct equipment function tests and fully simulated evaporator performance tests in our modem and fully equipped factory test facility. These tests can be witnessed by the client and representatives of the appropriate Classification Society, e.g. LRS, DNV, ABS, RINA, etc. Total service We provide a complete in-house engineering service, from preliminary design studies, followed by comprehensive specifications and quotations, technical and commercial consultation, through to fully detailed design, manufacture and testing. After-sales service includes technical assistance for supervision of installation, start-up and commissioning, and operator training. This is backed up by our engineering staff and world-wide agency network, for the provision of spare and services. Applications The Caird & Rayner Clark range of desalination and water treatment systems are extensive, with specific designs available for:
• Cruise ships
• Naval vessels
• Tankers
• Offshore platforms
• Land-based sites

info.ewt@glv.com