WIS Series - NewGate Technologies

1 Screw CompressorsCompressed air treatmentWIS SeriesExclusive Supplier of GrassAir CompressorsFew 5-75 HP oil-free air compressors can match the GRASSAIRWIS Series Water-Injected Screw Compressor in three criticalareas: Efficiency, Simplicity and WIS uses treated water as a coolant instead of oil. This resultsin a near Isothermal Compression, the most efficient way tocompress any gas. Energy savings in the range of 10-40% areachievable, compared to other compressors. The WIS is the simplest of all oil free compressors available in themarket today.

2 The combination of a simple rotary screw design withwater injection results in far fewer parts than other compressors inits class. Water injection makes possible the use of a single-stagedesign with one set of rotors, and a water cooler replaces theconventional oil cooler+ air after-coolerand moisture separatorcombination. There are no elaborate timing gears, no expensive oiland air/oil separator elementto replace, no gasketsand zeropossibility of are also no inter-coolers, no valvesand piston ringsto replace, and noenvironmentally damaging oily condensateto worry about.

3 Finally, the WIS is the most reliable of all oil-free compressors in its class. Water injection means lowoperating temperatures, resulting in extended component life. Low operating speeds also means lesswear and tear, resulting in minimal the best in each of these areas puts the GrassAir s WIS Series Water Injected RotaryScrew Compressor truly in a class by Rotary Screw designCompact, quieter (as low as 65 dBA), simple and vibration-freeNo foundation, no valves, no piston ringsSimple to install and maintain Water Injection Isothermal Compression/ Greater Efficiency10 to 40% greater energy savings than other compressors Water InjectionOnly one coolerrequiredNo oil coolers, Inter-coolers, after-coolers or moisture separatorsLess maintenance Single-stage operation50% fewer moving partsLower maintenance costs and Increased reliability Belt DriveNo cumbersome timing gears.

4 Very simple and inexpensive to repair and maintain Ceramic RotorsNo rusting or corrosionLower maintenance costs and Increased reliability Corrosion resistant Aluminum-Eliminates corrosion and alloy air end housingImproved reliability Oil free designNo oil filters or separators to change, no expensive oil to buyAbsolutely no danger of oil contaminationLower maintenance costs and increased reliability WIS Seriesoil-free rotary screw compressorsIn a Class by ItselfEfficiency, Simplicity and ReliabilityAtmospheric air is drawn into the air-end (12)through the air intake filter (1) and the inlet valve (2).

5 Simultaneously, cool water returning from the heatexchanger (8) is also injected into the air end. In theair-end, the air/water mixture is compressed up tothe discharge pressure and is let into the waterseparator vessel (13).The air and water are separated in the waterseparator. The saturated compressed air is thendischarged through a minimum pressure valve (4)directly into the plant air system. If the air pressurein the water separator is at any time less than 50 Psig, the minimum pressure valve will not the water separator vessel, most of the water isseparated from the air and drops to the bottom of theseparator.

6 Differential pressure allows the water toflow from the separator to the heat exchanger, whereit is cooled to within 15 F of the ambient airtemperature (air-cooled unit) or cooling water (water-cooled unit).The water removes almost all of the heat ofcompression. It also has high capacity to hold heat. Asa result, the air/water mixture in the separator isonly about 25 F above the air intake (ambient)temperature. As such, no after-cooler is required forthe air. The discharge air is always saturated withwater vapor.

7 Depending on the RH and temperatureof the intake air, water vapor will either condense intothe cooling water or will evaporate into the air streamduring the process of compression, thus adding to orsubtracting from the cooling water in the the level of water, controlled by two capacitancesensors, in the separator is too high, the high levelcap. sensor (S3) will open the bleed valve (Y4) anddischarge the water to the drain. On the other hand,if the level of water in the separator is too low, theLow level cap.

8 Sensor (S4) will open the water supplyvalve (Y5) and supply make-up water into the suctionside of the air-end. Both water bleed valves have atime delay of 5 heat exchanger (8) will be a fin & tube type for aircooled units and shell & tube type for water-cooledunits. In a water-cooled unit, instead of city water, aclosed-loop glycol-cooling system can be Heat-Exch 1 Reverse Osmosis FiltrationCompressorY51212Y418413S3S411Y 11678101. Air Intake2, Inlet valve4. Minimum pressure valve7. Water filter8. Water cooler10. Ball Valve11.

9 Non return valve12. Air-end13. Water separator vessel16. Waterfilter Strainer17. Valve18. Pressure GaugeS3. Capacitance Sensor-High levelS4. Capacitance Sensor-Low levelY1. Water injection valveY4. Drain valveY5. Supplemental water make-up valveHowThe WIS WorksIsothermal Compression meansLowest Compression EnergyAt top is the theoretical PV diagram forIsothermal and Adiabatic compression area ADEF represents the work requiredwhen operating on the Isothermal basis (PV =Constant); and ABEF, the work required on theAdiabatic basis (PVk= Constant).

10 Clearly, ittakes more work to compress and deliver a gaswhen the compression is adiabatic than when itis Isothermal, the difference being representedby the shaded area. For 100 Psig aircompression, this difference is about 27%.Water Injection results in Isothermal CompressionIn Isothermal compression, all the heat equivalent of compressor work is carried away as thegas is being compressed. By using water as a coolant, the GRASSAIR WIS unit accomplishesnear-isothermal compression. As seen below, this results in an energy savings from 10% upto 40% when compared to other compressors in its class.