H4-KH26A olerPG P x KthPG P x Kth Auxiliary cooling is r Helical speed reducer H4

Flender/Flender Gear Units/Helical speed reducer H4

ion required. The columns are generally of 1 to 4 ft (0.3 to 1.2 ) diameter and 6 to 2 ft (1.8 to 6.1 ) tall. Theextractor is equipped with line refractometers to check solubles concentration with provi- sion for intercolumn heating. feed water temperature of 1 C1C and pressure ranging from 1.7 to 1.4 bar are used. Particle size of powder should be neither too nenor too coarse. Approximate size specications are 2% to be retained on British sieve mesh size 8 and 5% to pass through 2 mesh. After leaving the extractor, the coffee extract is claried while hot. This is achieved by passing through strainers, but more commonly by centrifuging. The claried extract is then weighed and kept in storage tanks. 4.2.7 Drying of Coffee Extract The drying of coffee extract is achieved by one of two methods, spray drying or freeze drying. The extract is concentrated to 3%4% solids content by employing lm/plate/ centritherm. Generally, the extract of the fresh powder that has most of the aroma is kept separate and the extracts from the comparatively spent grounds are concentrated and addedback to the aroma-rich extract. 4.2.7.1 Spray Drying In the spray drying process, the atomized coffee extract ( /H1% solubles) is subjected to ash evaporation by using air at relatively higher temperature (2 C2C). Spray drying involves three steps: dispersion of the extract as ne spray, exposure of theatomized particles to current of hot air, and separation of air from the dried product. The atomization can be effected by either of two methods: owing of extract through arotating disk or passing through pressure nozzle. Two types of spray dryers are available,cocurrent and countercurrent, depending on the air and the feed ow. However, cocurrent dryers are by far more popular. Similarly, spray dryers of the vertical type are more com- mon than the horizontal type. The atomized particles on exposure to air at high temperaturelose water almost instantaneously. The exposure of hot air is short, re