Drying pilot plant

A modification of the conventional soy protein isolate process has been investigated on a small pilot-plant scale. It is based on the absorption of water from the aqueous protein after extraction at pH 8.5 using temperature-sensitive polyisopyropylacrylamide gels, followed by spray drying to give a 96% protein isolate (111). 

Still another process, called BI-GAS, was developed by Bituminous Coal Research in a 73 t/d pilot plant in Homer City, Peimsylvania. In this entrained-bed process, pulverized coal slurry was dried and blown into the second stage of the gasifier to contact 1205°C gases at ca 6.9 MPa (1000 psi) for a few seconds residence time. Unreacted char is separated and recycled to the first stage to react with oxygen and steam at ca 1650°C to produce hot gas and molten slag that is tapped. 

Ga.s-Lic(uid Ma.s.s Tran.sfer Gas-liqiiid mass transfer norrnallv is correlated bv means of the mass-transfer coefficient K a ersiis powder le el at arioiis superficial gas elocities. The superficial gas clocitv is the ohirne of gas at the a erage temperature and pressure at the midpoint in the tank di ided bv the area of the essel. In order to obtain the partial-pressure dri ing force, an assumption must be made of the partial pressure in equilibrium wdth the concentration of gas in the liquid, Manv times this must be assumed, but if Fig, 18-26 is obtained in the pilot plant and the same assumption principle is used in e ahiating the mixer in the full-scale tank, the error from the assumption is limited. 

A sulfuric acid drying tower uses 98% acid for drying an incoming air stream. The pilot plant tests show that 15 ft of 1-in. ceramic Intalox packing will do this job. The plant scale rates are ... 

The drying characteristics of the material can be investigated by laboratory and pilot plant tests which are best carried out in consultation with the equipment vendors. 

It is likely asked too much of most laboratory plants, if used as pilot plants for production process development. The best application of laboratory plants is the freeze drying of preparations and products which do not require to be operated within small tolerances, but can be dried under noncritical process data. 

All these plants are of the chamber type (see Fig. 1.88 (c)) with cooled and heated shelves and a condenser which can be separated from the drying chamber by a valve. Refrigeration and vacuum systems should be laid out for temperatures and pressures which can be expected under extreme experimental conditions, even if these extreme data may not be used in the production process. Pilot plants for pharmaceutical or medical products should be laid out differently than those used for food. 

By using manipulators, as shown schematically in Fig. 2.41, certain vials can be closed and left in their position or be removed from the plant by a lock. In a plant without a manipulator it is not possible to close vials after venting the plant for a short time, because during MD the product will collapse or melt and during SD the continuation of the drying will be different, (gas has been absorbed by the solids). Figure 2.42 shows a pilot plant with a manipulator. 

There will be some differences and it is a quantitative question, whether or not they can be tolerated or not. For a final decision, test runs in a pilot plant should be carried out with freshly frozen product and such which has been resting for 5 h before drying. These tests are recommended because the methods mentioned above use different sized samples in different configuration than are used in the production. The amount of product and its geometrical dimension will also influence the structure as well as the number of crystallization nuclei in the product, which can be very different in a normal laboratory and in a clean production area. 

The chosen Tice has been reached in the pilot plant at pc mbar ( 5 % and at 7+ = -10 °C. Note In a freeze drying plant with different dimensions and different number of vials pc will be slightly different to achieve the desired Tjce. Therefore pc must bee modified accordingly. In the pilot plant, a change of pc to 1.1 pc ( 5 % increases Tkc by 0.5 °C. In the pilot plant, pc has been controlled by closing the valve between the condenser and the vacuum pump set. 

The controlled operation pressure during the main drying is pc mbar -0 %, +10 % ). Tsh = -10 °C. With these data Tice has been -29.5 °C (standard deviation 0.38 °C) in the pilot plant. The production department must check the function Tlce = f (pc) for the production plant, and modify pc if necessary to achieve T-Kt = -29.5 °C(standard deviation < 0.4 °C)... 

BHEL pilot plant Lurgi dry ash process Schwarze Pumpe... 

The capital cost of the batch acetylation plant was calculated at 12 million and that of the continuous process plant at 5.5 million. It was assumed that the acetylation facility would be integrated with a traditional fibreboard plant, so that fibre production and drying costs were not included in the analysis. The analysis showed that wood fibre could be acetylated to a WPG of 20 % for a cost of 562 per tonne in a batch process and 384 per tonne in a continuous process. BP subsequently lost interest in the wood acetylation process and sold the pilot plant. 

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