Drying and gas or vapor contact with solids – Apparatus – With means to treat gas or vapor
Patent
1983-03-28
1985-06-18
Schwartz, Larry I.
Drying and gas or vapor contact with solids
Apparatus
With means to treat gas or vapor
34 86, 34169, F26B 320
Patent
active
045233888
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a process and equipment for drying damp materials, in particular vegetables.
"Combustion-chamber" dryers are already known; their energy consumption varies between 600 Kcal and 750 Kcal/kg of evaporated water depending on the equipment used. Moreover, such dryers entail a more than trivial consumption of fuel.
The object of the present invention is a so-called "low-temperature" drying process. This process essentially consists in bringing the damp material into contact with the dryer's heater elements, the vapor issuing from the damp material being mechanically recompressed to provide the caloric fluid that feeds the dryer's heater elements.
In a variation of the invention, the temperatures are so selected that the caloric fluid consists of a given quantity of air operating between two temperatures; the air is saturated at the low temperature and unsaturated at the high temperature. The calories required for evaporation are provided within the dryer both by the contact between the solid and the heater surface, and by the contact between the moist air and heater surface.
The moist, hot air leaving the dryer is cooled prior to recompression in the tube-stack of an evaporator of which the cold fluid is condensed water in the heater elements and condensed water in the evaporator itself.
It was found particularly desirable that the evaporator calandria be balanced on a barometric condenser and provide to the intake side of the motor-compressor the vapor which, following recompression, will feed the dryer's heater elements.
Advantageously, the temperature of the damp material at the dryer intake will be between 50.degree. C. and 100.degree. C., and preferably it shall be about 60.degree. C.
In case the dryer lacks an air feed,
the temperature of the vapor feeding the dryer's heater elements will be advantageously between 100.degree. C. and 160.degree. C., and preferably it shall be 105.degree. C.;
the temperature of the vapor issuing from the damp material will be between 80.degree. C. and 110.degree. C., and preferably it shall be 95.degree. C.;
the temperature of the condensates from the heater elements will be between 70.degree. C. and 100.degree. C., and preferably it shall be about 100.degree. C.
In case the dryer is fed at its lower part with saturated air,
the temperature of the vapor feeding the dryer's heater elements will be between 100.degree. C. and 160.degree. C., and preferably it shall be about 110.degree. C.;
the temperature of the vapor/air mixture issuing from the moist vapor will be between 80.degree. C. and 110.degree. C., and preferably it shall be about 75.degree. C.;
the temperature of the condensates from the heater elements will be between 70.degree. C. and 100.degree. C., and preferably it shall be 75.degree. C.;
the temperature of the saturated air injected into the lower dryer part will be between 60.degree. C. and 100.degree. C., and preferably it shall be about 70.degree. C.
The attached drawings and the following examples are non-limiting, and permit a better understanding of the invention:
Sheet I showing FIG. 1 illustrates the basic drying principle of the invention.
Sheet II showing FIG. 2 illustrates a variation of the drying process of the invention.
Sheet III showing FIGS. 3 and 4 illustrates drying equipment for the implementation of the process. At sheet III, FIG. 3 is a sectional view and FIG. 4 is a view taken alone line 4--4 of FIG. 3.
The sheet I schematically shows a dryer (1) provided with heater elements (2) fed with the vapor (3). The damp material (4) is introduced at the upper part of the dryer through a gate (5). A suitable system propels as needed the damp material onto the heater elements. Once the material arrives at the end (6) of an element, it drops by gravity onto the element directly below. The bottom of the dryer comprises a gate (7) for evacuating the dry material. The vapor (8) issuing from the heated damp material is recompressed by a motor-compressor (9), and thereupon it feeds the dryer heater elements (2).
EXAMPLE 1
REFERENCES:
patent: 205662 (1878-07-01), McDowell et al.
patent: 1540769 (1925-06-01), Ericson
patent: 3953927 (1976-05-01), Hoffert
patent: 4068388 (1978-01-01), Knutsen et al.
patent: 4223452 (1980-09-01), Chambers
patent: 4337584 (1982-07-01), Johnson
Beghin-Say S.A.
Breiner A. W.
Schwartz Larry I.
Westphal David W.
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