Drying and gas or vapor contact with solids – Process – Gas or vapor pressure is subatmospheric
Patent
1992-11-18
1995-07-11
Gromada, Denise L.
Drying and gas or vapor contact with solids
Process
Gas or vapor pressure is subatmospheric
34514, 34 86, D06F 5802
Patent
active
054309565
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process and a device to dry a drying room.
2. Prior Art
The German Patent DE 36 44 077 A1 and EP0043 361 A1 reveal a process and a device to dry wet laundry. Such systems are however technically seen as very complicated and the drying process as very time consuming. This is so because the high inlet volume flow is difficult to handle and because the non condensable gases in the inlet volume flow, such as air or the like, are difficult to extract. Additionally the energy consumption is very high.
Another known drying process uses a rotary sliding vane type compressor or a liquid seal pump to pump condensable gases as well as non condensable gases. However, it is importent that the temperature of the liquid ring is considerably lower than the temperature of the inlet gas otherwise the liquid of the liquid ring of the pump will evaporate due to the fact that the boiling pressure is reached. At this point practically no compression takes place. If the temperature of the liquid ring or the water jet considerably below the temperature of the condensing fluid, good results are achieved.
With a gas ballast device in a rotary sliding vane type compressor the working fluid can attain higher pressure ratios. The disadvantage is a lower efficiency and the following condensation is more difficult due to the lack of non condensable gases.
Another generally known method to evacuate a room filled with condensable and non condensable gases is the use of a gas jet pump for the first stage of compression to avoid cavitation. The disadvantage is the necessity of a gas source and the mixture of condensable and non condensable fluids.
A general problem is the very high inlet volume flow of the gas mixture at the beginning of compression. It is possible to use a roots pump or a rotary sliding vane type compressor. However, this is an expensive investment as a large space for a big pump is needed.
Further, it is generally known from the publication, H. D. Baehr, "Thermodynamik", Springer Verlag 4th edition, 1978, pages 289-292, and especially FIG. 6.48, to approximate a compression process to the Carnot cycle by intermediate cooling.
Therefore it is an object of the present invention to have a process and a device to dry a drying room by means of a few small elements with the need of little energy.
SUMMARY OF THE INVENTION
This object is attained according to the present invention by a special process e.g. by first raising the pressure of the gas mixture to be evacuated by means of a turbo pump to such an extent that in the next step the fluid or fluid mixture respectively can be compressed and the rising liquid can be carried away with a pump with an eccentric liquid ring or a liquid jet pump.
By this method the inner section of the dryer has a lower pressure and the boiling point of one or more fluids in the container are lowered. If there is wet laundry in the container the boiling point of the water is lowered till the water evaporates. Hence, the laundry can be dried at a lower pressure and at a temperature slightly above room temperature. An additional advantage is the carefull treatment since only a low temperature and little mechanical load is necessary. The laundry is left loosly mixed in the container. On top of that it is sterilised since most life can not withstand such a low pressure. Finally energy consumption, in the range of 40%, is much lower relative to the above mentioned processes.
Here the evaporating fluid is a mixture of air and water and in the container of the drier is air and wet laundry. By evacuating the container, water in the form of steam and air as a gas mixture is removed from the container.
The air is evacuated with a liquid seal pump and the steam will be condensated to avoid a high inlet volume flow. To have a sufficient pressure of water/steam above the boiling point of the water, a turbo pump is used to build the water in the liquid seal pump. This arrangement will raise the pressure of the mixture of
REFERENCES:
patent: 1309357 (1919-07-01), Falk et al.
patent: 2627669 (1953-02-01), Candor
patent: 3762065 (1973-10-01), Wahlgren
patent: 4347671 (1982-09-01), Dias et al.
Periodical "Siemens-Zeitschrift", vol. 33, 1959, No. 4, pp. 281 & 282.
Gromada Denise L.
SEMTEC Muller OHG
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