Gas separation: apparatus – Solid sorbent apparatus – Plural solid sorbent beds
Reexamination Certificate
2000-08-03
2002-04-02
Spitzer, Robert H. (Department: 1724)
Gas separation: apparatus
Solid sorbent apparatus
Plural solid sorbent beds
C096S125000, C096S127000, C096S130000, C096S143000, C096S150000
Reexamination Certificate
active
06364943
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a gas treatment system for use in separating and recovering gaseous hydrocarbon (e.g., vapor of toluene, xylene, or the like employed as a solvent) contained in a treatment-object gas such as factory exhaust gas. More particularly (see FIG.
4
), the invention relates to a gas treatment system comprising: a rotary adsorbing-desorbing concentration device
1
including a gas-permeable adsorbing rotor
4
having adsorbent as a main component thereof, the rotor
4
having in a rotational region thereof an adsorbing area x for allowing passage of treatment-object gas A containing gaseous hydrocarbon through a rotor portion corresponding thereto and a desorbing area y for allowing passage of desorbing-concentrating gas B through a rotor portion corresponding thereto, the adsorbing area and the desorbing area being arranged side by side and separated from each other along a rotational direction of the rotor;
an adsorbing-desorbing recovery device
2
for selectively effecting an adsorbing process for causing the desorbing-concentrating gas B′ past the desorbing area y to pass an adsorbent layer
9
and a desorbing process for causing desorbing-recovering gas C to pass the adsorbent layer
9
; and
a condensing recovery device
3
for cooling adsorbing-recovering gas C′ past the adsorbing layer
9
so as to condense the gaseous hydrocarbon contained therein and then separating and recovering this condensed hydrocarbon from the gas.
2. Description of the Related Art
Conventionally, with a gas treatment system of the above-noted type, as shown in
FIG. 4
, the desorbing-concentrating gas B″ which has adsorbed and separated the hydrocarbon from the treatment-object gas A from the rotary adsorbing-desorbing concentration device
1
in the course of passage thereof through the adsorbent layer
9
(the layer
9
shown on the right-hand side in
FIG. 4
) engaged in the adsorbing process at the adsorbing-desorbing recovery device
2
is directly discharged into the atmosphere together with the treated treatment-object gas A′ discharged from the adsorbing area x of the rotary adsorbing-desorbing concentration device
1
(see Japanese published patent gazette No. Sho. 60-10772).
Regarding the adsorbing-recovering gas C″ (the gas which has condensed the desorbed hydrocarbon from the adsorbent layer
9
and separated and eliminated it) which has passed the condensing recovery device
3
subsequent its passage through the adsorbent layer
9
(the other layer
9
shown on the left-hand side in
FIG. 4
) engaged in the desorbing process of the adsorbing-desorbing recovery device
2
, there have been proposed various types of adsorbing-desorbing recovery devices designed to return this gas to the adsorbing adsorbent layer
9
(i.e., the adsorbent layer currently engaged in the adsorbing process) (for instance, Japanese laid-open patent gazette No. Hei. 11-57372; Japanese laid-open patent gazette No. Hei. 9-38445; Japanese laid-open patent gazette No. Hei. 6-226029; Japanese published patent gazette No. Hei. 4-66605; and Japanese published patent gazette No. Sho.
53-22541
).
Further, for this returning of the desorbing-recovering gas C″ past the condensing device back to the adsorbing adsorbent layer
9
, there is also known an adsorbing-desorbing recovery device including a recycling passage for recycling the desorbing-recovering gas C′ past the desorbing adsorbent layer
9
again to the same desorbing adsorbent layer
9
and returning a portion of the desorbing-recovering gas taken off this recycling passage back to the adsorbing adsorbent layer
9
via the condensing recovery device
3
(e.g., see Japanese laid-open patent gazette No. Hei. 9-38445 and Japanese laid-open patent gazette No. Hei. 6-226029).
However, in order to reduce the concentration of the hydrocarbon contained in the adsorbing-concentrating gas B′ (concentrating gas) caused to contain the gaseous hydrocarbon in the course of its passage through the desorbing area y of the rotary adsorbing-desorbing concentration device
1
to a level low enough for the gas to be discharged directly into the atmosphere by means of passage through the adsorbing adsorbent layer
9
of the adsorbing-desorbing recovery device
2
, a significantly high treatment efficiency is required of this adsorbing-desorbing recovery device
2
. Specifically, the adsorbing-desorbing recovery device
2
needs a large amount of adsorbent, which makes it difficult to form this device compact. Moreover, a significantly high temperature (e.g., high temperature which can not be obtained with a typical steam heat source) is needed for the desorbing process to be effected in the adsorbing-desorbing recovery device
2
, which leads to high energy consumption. In addition, such high desorbing temperature disadvantageously promotes degradation of the adsorbent and tends to invite unwanted change in the quality of hydrocarbon, such as a solvent, to be recovered.
Further, as described also hereinbefore, if it is attempted to elevate the cooling temperature needed by the condensing recovery device
3
(to elevate up to substantially the room temperature) by returning the desorbing-recovering gas C″ past this condensing device
3
back to the adsorbing adsorbent layer
9
(in other words, by allowing un-condensed gaseous hydrocarbon to remain at a certain high concentration in the desorbing-recovering gas C″ past the condensing device), there exists a limit in possible elevation of the temperature if the hydrocarbon concentration of the desorbing-concentrating gas B″ past the adsorbing adsorbent layer
9
together with the desorbing-recovering gas C″ past the condensing device is to be maintained low enough for allowing its discharge into the atmosphere. Hence, the condensing recovery device
3
needs sufficiently low temperature for cooling the gas. In this regard too, the energy consumption is increased disadvantageously.
In view of the above-described state of the art, a primary object of the present invention is to achieve compactness of the system and reduction in energy consumption thereof while retaining high recovery efficiency of the gaseous hydrocarbon by means of reasonable improvement enabling more efficient use of the rotary adsorbing-desorbing concentration device of the system.
SUMMARY OF THE INVENTION
For accomplishing the above-noted object, according to the present invention (see
FIG. 1
or FIG.
3
), a gas treatment system comprises:
a rotary adsorbing-desorbing concentration device
1
including a gas-permeable adsorbing rotor
4
having adsorbent as a main component thereof, the rotor
4
having in a rotational region thereof an adsorbing area x for allowing passage of treatment-object gas A containing gaseous hydrocarbon through a rotor portion corresponding thereto and a desorbing area y for allowing passage of desorbing-concentrating gas B through a rotor portion corresponding thereto, the adsorbing area and the desorbing area being arranged side by side and separated from each other along a rotational direction of the rotor;
an adsorbing-desorbing recovery device
2
for selectively effecting an adsorbing process for causing the desorbing-concentrating gas B′ past the desorbing area y to pass an adsorbent layer
9
and a desorbing process for causing desorbing-recovering gas C to pass the adsorbent layer
9
; and
a condensing recovery device
3
for cooling adsorbing-recovering gas C′ past the adsorbent layer
9
so as to condense the gaseous hydrocarbon contained therein and then separating and recovering this condensed hydrocarbon from the gas;
wherein the system further comprises a desorbing-concentrating gas return passage
12
for returning desorbing-concentrating gas B″ past the adsorbent layer
9
after the desorbing layer y to cause this desorbing-concentrating gas B″ together with the treatment-object gas A to pass the adsorbing area x.
That is, according
Spitzer Robert H.
Taikisha Ltd.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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