Gas separation: processes – Solid sorption – Moving sorbent
Patent
1998-01-12
1999-06-01
Spitzer, Robert
Gas separation: processes
Solid sorption
Moving sorbent
95142, 95143, 95147, 96122, 96125, 96130, 96145, B01D 5304, B01D 5306
Patent
active
059084901
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an organic solvent recovery system for efficiently recovering an organic solvent from a gas containing the organic solvent, the system being capable of reducing the diffusion of the organic solvent to the environment to the extent possible, and an organic solvent recovery method using the same; and the present invention relates to a recovery system for recovery of organic solvents from a gas containing a mixture of organic solvents, and an organic solvent recovery method using the same.
BACKGROUND ART
Organic solvents have been used widely in various industries, and for the prevention of environmental pollution due to gas discharge from plants and factories, regulation of the content of organic solvents in gas discharge has been strengthened more severely in recent years. Thus, the establishment of a gas discharge disposal technique capable of further reducing the content of organic solvents has been desired.
The adsorbing materials conventionally used in organic solvent recovery apparatus to recover solvents from a gas containing organic solvents include particulate active charcoal and active carbon fiber primarily.
So as to recover organic solvents from a gas by organic solvent recovery apparatus using particulate active charcoal as the adsorbing material, the following processes are generally employed: an adsorption process comprising contacting a gas containing organic solvents with the adsorbing material to adsorb the organic solvents onto the material, a subsequent desorption process comprising desorbing the adsorbed organic solvents from the adsorbing material via heat while blowing steam into the adsorbing material, and a further subsequent drying process comprising introducing heated exterior air and the like into the adsorbing material in a state of high moisture and high temperature from the foregoing processing, for the purpose of elevating the adsorption capacity of the adsorbing material for recycle, and cooling and drying the adsorbing material by introducing unheated exterior air into the adsorbing material (Japanese Patent Laid-open No. Sho 51-72968).
Because micropores are present on the outer surface of active carbon fiber while micropores are present as active adsorbing sites inside particulate active charcoal, active carbon fiber has, characteristically, a faster adsorption rate and desorption rate of organic solvents than the respective rates of particulate active charcoal, along with a larger adsorption volume. Therefore, an organic solvent recovery apparatus using active carbon fiber as the adsorbing material requires only a short time for thermal exposure for desorbing organic solvents under steam purging, which is advantageous for efficient recovery of high-quality solvents (Japanese Patent Laid-open No. Sho 61-68122).
Because the cooling and drying of active carbon fiber with such properties in the organic solvent recovery process is generally promoted even by a gas containing organic solvents introduced in the adsorption process, the adsorption process comprising introducing a gas containing organic solvents may be initiated and concurrently carried out at an intermediate stage of the cooling and drying process using drying gas; or the introduction of a gas containing organic solvents at the adsorption stage may be direct without drying using drying gas, to promote the adsorption while advantageously retaining the cooling and drying effect. Therefore, the desorption and adsorption process comprising adsorption, desorption, cooling and drying (this stage sometimes overlaps with the adsorption stage) and adsorption, in this order, can be carried out advantageously within a short period of time.
On completion of desorption in the desorption and adsorption cycle using particulate active charcoal and active carbon fiber as the adsorbing materials, the individual adsorbing materials are in a wet state because of the steam used in the desorption stage. At the adsorption stage to be carried out subsequently, therefore, a gas containin
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Akamatsu Mikio
Hata Taketo
Seki Kenji
Spitzer Robert
Toho Chemical Engineering and Construction Co., Ltd.
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