Performance of VOC Abatement by Thermal Swing Honeycomb Rotor

May 11, 2007 - honeycomb rotor of adsorbent was applied to the VOC abatement system operating with thermal swing adsorption. Dependence of the removal...
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Performance of VOC Abatement by Thermal Swing Honeycomb Rotor Adsorbers Hisashi Yamauchi,† Akio Kodama,*,‡ Tsutomu Hirose,§ Hiroshi Okano,| and Ken-ichiro Yamada| Art, Science and Technology Center, Kyushu UniVersity, Kasuga-shi, Fukuoka 816-8580 Japan, DiVision of InnoVatiVe Technology and Science, Graduate School of Natural Science and Technology, Kanazawa UniVersity, Kakuma-machi, Kanazawa, 920-1192 Japan, AdVanced Adsorption Technology, 4-19-7, Miwadai, Higashi-ku, Fukuoka, 811-0212 Japan, and Research and DeVelopment, Seibu Giken Co., Ltd., 3108-3, Aoyagi, Koga, Fukuoka, 811-3134 Japan

Fine powder of hydrophobic high silica zeolite was solidified with silica sol in the void of a 0.2 mm thick ceramic fiber sheet fabricated into a honeycomb structure, typically with 3.2 mm pitch × 1.7 mm height. The honeycomb rotor of adsorbent was applied to the VOC abatement system operating with thermal swing adsorption. Dependence of the removal efficiency of VOC on various variables was investigated for a test honeycomb rotor of 300 mm in diameter. The following operating guide was recommended to reach high performance where more than 95% of VOC in the feed gas is removed: superficial velocity of feed air ) 2-4 m/s, flow rate ratio of process to regeneration zone ) 5-15, relative humidity < 80%, and regeneration air temperature ) 180 °C with rotation speed optimized. The optimal rotation speed of the honeycomb rotor was investigated closely, and the result was interpreted in terms of the heat capacity ratio between the honeycomb rotor and the regeneration air stream. Introduction Volatile organic compounds (VOC) emitted in a large volume from chemical plants, semiconductor industries, printing and coating processes, and so on have been recognized as one of the precursors for suspended particulate matter and photochemical oxidants. The governmental regulations for VOC emission are getting more and more severe in many countries in a worldwide movement toward environmental protection. For example, in Japan, the air pollution control law revised in 2004 has been enforced in April 2006 and the aim is to reduce the annual emission in 2010 by 30% relative to the total emission of 1.5 million tons in 2000 by a combination of governmental regulations and voluntary efforts of emission sites. High-efficiency units for VOC abatement are required to meet the above target of air pollution control. VOC of low concentration are destructed finally by direct or catalytic combustion, corona destruction, or ozone decomposition unless recovery by cooling or compression is economical in the case of high concentration (>1%). VOC-laden air is strongly recommended to be pretreated to concentrate VOC and reduce the load of the final destruction units. Preconcentrators are usually based on adsorption on various porous solids, although absorption and membrane processes are not impossible. Remarkable progress in adsorptive VOC treatments in the recent one or two decades may be the introduction of thermal swing honeycomb rotor adsorbers into the market. This type of VOC concentrators was characterized by a monolith or honeycomb structure of adsorbent instead of the conventional particles or pellets and by a rapid response to temperature swing. They were developed by Seibu Giken and Nichias in Japan, Munters Zeol in Sweden, and Lurgi in Germany. Activated carbon was employed as the adsorbent at first but was replaced soon by * To whom correspondence should be addressed. Tel.: +81-76-2646472, Fax: +81-76-264-6496. E-mail: [email protected]. † Kyushu University. ‡ Kanazawa University. § Advanced Adsorption Technology. | Seibu Giken Co., Ltd.

high silica zeolite to avoid possible ignition during thermal regeneration by hot air. Seibu Giken Co., Ltd., Fukuoka, Japan, which the present authors are concerned in, had commercialized a honeycomb rotor dehumidifier in 1984 as an extension of their corrugation technology developed in cumulative heat exchangers some years before they put the VOC concentrators into market in 1988. The dehumidifier was applied later to the adsorptive desiccant cooling system, and the heat/mass transfer properties of the dehumidifier itself and the cooling system have been analyzed by Kodama et al.,1-3 Okano et al.,4 and Jin et al.5 Recently, Matsukuma et al.6,7 analyzed a potential application of the honeycomb rotor adsorber to CO2 recovery other than dehumidification. As for the thermal swing VOC concentrator, thermal effects for a cyclic adsorption process have been discussed by Ko et al.,8 Gales et al.,9 Sullivan et al.,10 Nastaj et al.,11 and Matsukuma et al.12,13 However, they discussed particle packed beds8-11 instead of honeycomb type, a combined temperature-pressure swing11 or numerical simulation, but not experimental works.8-13 No papers based on experimental data seem available except for a conference paper by Kuma et al.14 and a short paper by Mitsuma et al.15 within the authors’ scope. Keller16 timely outlined the honeycomb rotor adsorber in his review of adsorption technology, but only a few engineering data are published yet, as he said. The purpose of this investigation is to describe the details of honeycomb rotor adsorbers developed by Seibu Giken Co. Ltd. and discuss the performance of VOC abatement to derive some general principles for design and operation of honeycomb rotor VOC concentrators. Honeycomb Rotor Adsorbent and VOC Abatement System Figure 1 shows the total system of a VOC abatement system. VOC-laden air is concentrated by a factor of about 10 in a honeycomb rotor concentrator according to the flow sheet given in arrowed bold lines before it is combusted directly in an incinerator to destruct it finally. The degree of enrichment is usually sufficiently high for combustion of VOC. The direct

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Figure 1. Integrated system of VOC abatement with a thermal swing honeycomb rotor incorporated.

Figure 2. Cross-sectional view of honeycomb structure.

combustion sometimes is replaced by catalytic combustion or others when VOC concentration in the feed air is too low to concentrate it to the sufficient concentration. Combustion heat released is utilized through heat exchange to regenerate the honeycomb adsorbent by desorbing the adsorbed VOC at an elevated temperature. Thus a self-sufficient system can be constructed without any external heat source in a fortunate case. A housing holding a slowly rotating honeycomb adsorbent rotor is subdivided usually into three sectors as shown in Figure 1. The first is a process zone where VOC vapor was removed from the feed air by adsorption onto the adsorbent surface during passing through narrow channels of the honeycomb structure as shown in Figure 2. The second is a regeneration zone where the adsorbent rotor is regenerated by hot air streamed countercurrently to the process zone. The last is a cooling zone, which is located between the process and regeneration zones and serves to purge the crude product from the bulk of fine product and to cool the rotor to keep a high adsorption capacity in the subsequent process zone. The rotor was kept airtight to avoid air leakage across each zone by a set of radial and circumferential seals, of which the details are discussed by Mitsuma et al.17 In typical commercial applications, the ratio of crosssectional area of process:regeneration:cooling zone is set to 10: 1:1 and the regeneration temperature is 180 °C. The key technology of the honeycomb rotor adsorber is the preparation of a high-efficiency adsorbent in a matrix of corrugated sheet; the detailed procedure can be found in patents by Kuma et al.18-20 A plane strip and a corrugated strip of 0.2

mm thick ceramic fiber paper with high voidage were first stacked with heat-resistant adhesive to manufacture a single layer of honeycomb with a typical channel pitch of 3.2 mm width × l.7 mm height and wall thickness of 0.2 mm. Then the singlelayer honeycomb was rolled up with the same adhesive into the shape of a honeycomb rotor as shown in Figure 2 up to a desired diameter while the tension applied to the layer was controlled carefully. The largest commercial size is about 4 m in diameter, and a large-diameter unit was manufactured by fixing several precut honeycomb segments in a frame instead of the above single stage rolling-up. The rotor was once calcined at about 500 °C to manufacture a heat-resistant ceramic rotor by removing unnecessary organic matter involved as a binder in the ceramic paper. The ceramic rotor was then impregnated with dilute silica sol in which fine powder of high silica zeolite was suspended. The composite adsorbent of zeolite was solidified in the void of the ceramic fiber sheet of the rotor matrix after drying. The adsorbent honeycomb rotor was completed by heating it, cutting it in 450 mm width, and finishing the end surface flush. High silica zeolite, i.e., zeolite with a high Si/Al ratio, as used here bears a hydrophobic surface to accelerate the adsorbability for organic compounds and was utilized in the present study instead of conventional activated carbon. Performance Test Figure 3 is a schematic diagram of the experimental apparatus for the performance test. A small test rotor of 0.3 m diameter of honeycomb adsorbent of high silica zeolite was manufactured by the same procedure as the commercial unit mentioned above. The fractional zone area β of each zone was set as βp:βr:βc ) 10:1:1 unless otherwise mentioned. The honeycomb rotor was installed between 2 m calming sections of heat-resistant tubes of 135 mm i.d. (process zone) or 70 mm i.d. (regeneration zone) to stabilize the flow through the rotor. Humidity in the feed air was controlled to the desired value in a 20 m3 air-conditioned chamber, while the VOC component was mixed with the air stream by spontaneous evaporation from a shallow liquid pool. VOC components tested were acetone, isopropyl alcohol (IPA), methyl ethyl ketone (MEK), and toluene as single components or a mixture of them. The feed concentration of VOC ranged over Cp0 ) 50-700 ppm. The feed air was supplied to the test rotor by suction through a process fan, and the regeneration air was driven by another fan via the cooling zone. Air leaving the cooling zone was totally returned to the regeneration zone after heating it to a preset temperature by a 3 kW electric heater.

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Figure 3. Schematic diagram of the experimental apparatus for performance test.

Flow rates through the process and cooling (or regeneration) zones were measured by orifice flow meters and adjusted individually to desired values by frequency inverters. VOCenriched air exhausted from the regeneration fan was sent to an incinerator for combustion. Byproducts were not detected in the enriched air stream by our gas chromatographic analysis, and the deterioration of solvent did not seem to take place. The feed and product VOC concentrations Cp0 and Cp1, respectively, were measured by a gas chromatograph in the feed air stream and the clean air product stream as shown in Figure 3, and the performance of VOC treatment was evaluated in terms of a removal efficiency E defined as fractional decrease in VOC concentration relative to the feed concentration.

E ) (Cp0 - Cp1)/Cp0

(1)

The recovery ratio R of enriched VOC leaving the regeneration zone divided by the total feed VOC entering the process and the cooling zones is simply calculated as

R ) (EF + 1)/(F + 1) ) E + (1 - E)/(F + 1) > E (2) when the ratio of volumetric flow rate of the process to the regeneration zone is defined as F ()βpUp/βrUr). The recovery ratio R is greater than E numerically but is very close to E in actual cases since E ) 1 and F . 1. Temperature T and humidity φ were monitored, respectively, by thermocouples and dew point meters at the positions shown in Figure 3. A typical example of a performance test is shown in Figure 4 in a plot of the removal efficiency E against rotation speed of the honeycomb rotor N. The figure shows high removal efficiency E over 95%, which is sufficiently high in industrial applications. The honeycomb rotor adsorbent has been improved in chemicals used, reaction process, ceramic material of matrix, adhesive, assembling process, etc. since it was put into the market in 1988. The efficiency in the improved rotor is higher than that in the conventional one for which the efficiency was cited in previous reports.14,15 The removal efficiency reported in the present article was newly obtained for the improved rotor. It is notable that the removal efficiency E has a peak value with the variation in rotation speed N. Operation at the optimum rotation speed Nopt is recommended to give the highest performance, but the details will be discussed later. It should be noted that the reported efficiency E hereafter is that at this optimal rotation speed Nopt when in the following sections we

Figure 4. Dependence of the removal efficiency E on rotation speed N and the effect of superficial velocities in the process Up and regeneration zones Ur on the optimal rotation speed Nopt.

discuss in more detail the dependence of removal efficiency upon various operating conditions. Effects of Various Operating Conditions The removal efficiency E at the optimum rotation speed is influenced by various operating conditions such as feed concentration of VOC Cp0, superficial velocity of the feed air Up, fractional zone area β or flow rate ratio F ()βpUp/βrUr) in the process to the regeneration zone, relative humidity of feed air φ, temperature of regeneration air Tr1, and so on. Effect of Feed VOC Concentration Cp0. Removal efficiency E at various values of feed VOC concentration Cp0 is shown in Figures 5 and 6 for a mixed feed of methyl ethyl ketone (MEK), isopropyl alcohol (IPA), and toluene. Values of E decrease with increasing concentration, although a still high value over 90% is kept at the highest concentration. The adsorption isotherm of organic vapors on high silica zeolite is usually highly nonlinear and so-called favorable. The adsorption coefficient, i.e., adsorbed amount divided by concentration, decreases rapidly with increasing concentration, and the adsorbent tends to reach the breakthrough point very soon. Another reason may be the adsorption heat which is liberated during adsorption and results in a lower amount adsorbed at higher temperature. The removal efficiency E is plotted in Figures 5 and 6, respectively, with parameters of superficial velocity in the process zone Up and the flow rate ratio F. As seen there, the removal efficiency E is improved with decreasing values of Up or F and the operation

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Figure 7. Effect of the flow rate ratio in the process to regeneration zone F on the removal efficiency E. Figure 5. Effect of feed VOC concentration Cp0 on the removal efficiency E at two different velocities in the process zone.

Figure 8. Effects of relative humidity φ on the removal efficiency E for VOC and accompanying water vapor. Figure 6. Effect of feed VOC concentration Cp0 on the removal efficiency E for various flow rate ratios in the process to regeneration zone F.

at lower feed velocity Up or lower ratio of flow rate ratio F is recommended for high concentration feed Cp0 although the resultant process capacity or VOC enrichment is forced to be decreased. The removal efficiency E decreases with increasing velocity in the process zone Up as shown in Figure 5, but the practical application to the feed velocity of 4 m/s is acceptable, depending on the feed concentration Cp0. Probably the effect of the air velocity appears through the number of mass transfer units (NTU), kaL/Up. However, the mass transfer term ka remains unknown, unfortunately, and further discussion on it seems impossible at the present stage. Effect of Flow Rate Ratio F. The flow rate ratio F ()βpUp/ βrUr) can be varied by changing the fractional zone area β at constant velocity of regeneration air Ur or by changing the regeneration air velocity Ur at constant β. The effect of the flow rate ratio F is shown in Figures 6 and 7 for a constant value of βp:βr:βc ) 10:1:1. In either figure, the removal efficiency E decreases with the increasing ratio of the flow rate F. The ratio F is required to be kept at as high a value as possible since it is a possible maximum ratio of enrichment of VOC, Cr0/Cp0. On the other hand, an operator has to compromise with a value of F low enough to meet a required high removal efficiency E. Thus the selection of a suitable value of flow rate ratio F is an important work for an engineer.

Effect of Accompanying Humidity O. Since VOC in the feed air is mixed with the atmospheric air, the feed contains water vapor, the concentration of which usually is much higher than that of VOC. The removal efficiency of VOC was expected to be influenced by the humidity because of decrease of the adsorbed amount in the competitive adsorption with water vapor and the probable increase of temperature due to the adsorption heat of water vapor. VOC removal was carried out under various values of relative humidity φ, and the result of removal efficiency E is shown in Figure 8 together with the removal efficiency of water vapor, similarly defined as eq 1. No substantial decrease in the VOC removal efficiency is shown to appear up to the relative humidity of 80%, and this fact corresponds to the result that the removal efficiency of water vapor was as low as 10%. Such a wide operating range of humidity can be kept owing to the hydrophobic nature of the surface of high silica zeolite used. Activated carbon has been known as a good adsorbent for VOC, but the recommended range of humidity φ was restricted to below 60% in a similar honeycomb rotor with activated carbon powder substituted for high silica zeolite. Effect of Regeneration Air Temperature Tr1. Thermal swing adsorption operates on a principle of difference of the amount adsorbed between two different temperatures in the process and regeneration zones. Thus the regeneration air temperature Tr1 supplied to the regeneration zone is an important operating parameter. Figure 9 shows the effect of regeneration

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Figure 9. Effect of regeneration air temperature Tr1 on the removal efficiency E.

temperature Tr1 on the removal efficiency E. The removal efficiency E increases with increasing temperature of regeneration Tr1 and reaches the highest value at the temperature of Tr1 ) 180 °C. The temperature of 180 °C is an easily accessible temperature by on-site combustion of concentrated VOC or the external waste heat from off-site. The overall system of VOC abatement can be simplified greatly by combustion for both destruction and heat recovery while steam regeneration of activated carbon has been employed conventionally. Recommended Operation. To summarize the above discussion, the following range of operating parameters is recommended to obtain a satisfactory removal efficiency E higher than 95% for the present honeycomb rotor adsorber: superficial velocity Up ) Ur ) 2-4 m/s, flow rate ratio F ) 5-15, relative humidity φ < 80%, and regeneration temperature Tr1 ) 180 °C. It should be noted that the rotation speed N must be set at the optimal value, which will be discussed in detail in the following section. The removal efficiency can be kept higher than 90% until 3-6 years after installation, but it gradually decreases during a long-term operation due to accumulation of trace heavy components of high boiling point on the adsorbent. The removal efficiency can be recovered to some extent by washing the rotor with water spray and subsequent drying without dismantling the rotor. More efficient reactivation by hot air of 300 °C is possible when a heat-resistant rotor as well as a heat-resistant seal is employed. Optimal Rotation Speed The contacting mode of the honeycomb rotor adsorber is a kind of cross-flow moving bed, and the supplying rate of the adsorbent is controlled by the rotation speed of the honeycomb rotor N. The removal efficiency E depends on the rotation speed, i.e., the supplying rate of the adsorbent as seen previously in Figure 4. Thermal swing adsorption is a typical operation concerned with the simultaneous heat/mass transfer, and discussion has to be made from both points of view. As for mass transfer, the higher rotation speed is preferred since more adsorbent is supplied and the adsorbent leaves the process zone sufficiently before the so-called breakthrough point of adsorption. For heat transfer, on the other hand, the lower rotation speed is preferred since the adsorbent enters the process zone after it is cooled sufficiently in the preceding cooling zone. The adsorbent temperature is not different between the process and regeneration zones at a limit of infinitely high speed, and the honeycomb rotor is just a heat exchanger but does not function

Figure 10. Correlation of the optimal rotation speed Nopt in terms of the apparent space velocity (βrUr/L) in the case of bulk density Fb ) 263 kg/m3.

as an adsorber. The optimal rotation speed Nopt exits to give the highest value of the removal efficiency E because of the above conflicting effects of the rotor speed N. Figure 4 shows the effect of superficial velocities in the process zone Up and the regeneration zone Ur on the optimal rotation speed Nopt. The velocity in the process zone Up does not influence the optimal rotation speed Nopt, although the removal efficiency E itself is higher for lower velocity Up naturally. The regeneration air velocity Ur is a rather important factor and the optimal rotation speed Nopt is proportional to it, as shown in the figure. This fact implies that heat supplied by the regeneration air has to be matched with the one to heat the adsorbent entering the regeneration zone. In other words, the optimal rotation speed Nopt is controlled by a balance of heat capacity supplied to the regeneration zone between flowing regeneration air and rotating adsorbent. The former is characterized by FgcpSβrUr while the latter is characterized by FbccSLNopt, in which Fg and Fb are air and bulk densities, cp and cc are air and adsorbent heat capacities, and S is the total cross-sectional area of the rotor. The ratio defined as a heat capacity ratio Λopt

Λopt ) (Fbcc/Fgcp)LNopt/βrUr

(3)

is proposed to correlate the optimal rotation speed Nopt. The optimal rotation speed Nopt obtained under various operation parameters is plotted against the value of βrUr/L in Figure 10 to check the validity of eq 3. The term Fbcc/Fgcp is identical since the same rotor with the bulk density Fb ) 263 kg/m3 was used through the experiment. The term βrUr/L expresses an apparent space velocity of the regeneration air based on the total cross-sectional area S of the rotor but not the real area of the regeneration zone. Thus, βrUr/L ) 1 s-1 means that the volume of the regeneration air supplied each second is equal to the volume of the rotor. The figure shows a good consistency between two different values of fractional zone area of βp:βr:βc ) 10:1:1 and 13:2:1. Since the rotation speed N is the space velocity of adsorbent, in other words, a straight correlation line in Figure 10 indicates that the space velocity of the honeycomb rotor should be set as low as 1/400 of that of regeneration air under the optimal condition. The bulk density of the rotor Fb can be changed by the material of the matrix sheet, its thickness, honeycomb pitch, etc. The effect of the bulk density Fb is shown in Figure 11, in which the optimal rotation speed Nopt is plotted against the reciprocal of bulk density (1/Fb) in the right-hand side of eq 3.

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variables, more than 95% of VOC in the feed gas was removed while VOC were concentrated about 10 times in the exhaust gas stream. The optimal rotation speed of the honeycomb rotor was investigated closely and interpreted in terms of the heat capacity ratio between the honeycomb rotor and the regeneration air stream as given by eq 4. Nomenclature

Figure 11. Effect of bulk density of the honeycomb rotor Fb on the optimal rotation speed Nopt.

Results are correlated by a straight line, and this fact recommends that the lighter rotor should be rotated faster in inverse proportion to the bulk density. The above discussion supports that the capacity ratio Λopt takes a constant value at the optimal rotation speed. With substitution of substantially constant numerical values of Fg ) 1.2 kg/m3, cp ) 1.0 kJ/kg‚K, and cc ) 1.0 kJ/kg‚K, the final correlation of the optimal rotation speed Nopt can be obtained as follows:

Λopt ()(Fbcc/Fgcp)LNopt/βrUr) ) 0.55

Cp0, Cp1 ) VOC concentration at the feed inlet and the product outlet, respectively (ppm) cc, cp ) heat capacity of the rotor and air, respectively (J/kg‚ K) E ) removal efficiency defined by eq 1 F ) volumetric flow rate ratio of the process zone to the regeneration zone ()βpUp/βrUr), with flow rate converted to feed temperature Tp0 ka ) volumetric mass transfer coefficient (1/s) L ) width of the honeycomb rotor (m) N ) rotation speed of the honeycomb rotor (1/s) Nopt ) optimal rotation speed to give the highest removal efficiency E (1/s) R ) recovery ratio of enriched VOC leaving the regeneration zone, given by eq 2 S ) total cross-sectional area of the adsorbent rotor (m2) Tp0, Tr1 ) temperature of the feed and regeneration air, respectively (°C) Up, Ur ) superficial air velocity in the process and regeneration zones, respectively, converted to feed temperature Tp0 (m/s) Greek Symbols

(4)

Kuma et al.14 and Mitsuma et al.,15 respectively, have discussed preliminarily the optimal rotation speed of VOC honeycomb rotors in their short paper and conference paper. Their results are consistent with the present one when their results were evaluated in terms of eq 4. Kodama et al.1 has discussed the optimal rotation speed in the case of honeycomb rotor dehumidifiers similarly operating with thermal swing. Their result was correlated with the heat capacity ratio Λopt, of which the numerical value is equal to 0.38 for low humidity and decreases to 0.23 with increasing humidity instead of 0.55 in eq 4 for VOC removal. A higher value for VOC removal is consistent with that for dehumidification quantitatively since the VOC concentration was much lower than the water vapor concentration. In the dehumidification, no cooling zone was installed, the fractional area of regeneration zone βr was as large as 0.215, the concentration and amount adsorbed were much higher than those for the VOC case, the heat effect of adsorption was substantial, and so on. These differences should be taken into account for a more quantitative discussion on the numerical difference in the heat capacity ratio Λopt. However, the heat capacity ratio defined by eq 3 is an important parameter in discussing the optimal rotation speed of the thermal swing honeycomb rotor adsorber in various industrial applications. Conclusions The honeycomb rotor adsorber was manufactured by solidifying hydrophobic high silica zeolite with silica sol. A performance test for VOC removal was carried out by operating it in thermal swing adsorption. The removal efficiency of VOC depended on various variables such as the rotation speed, gas flow rate and flow rate ratio, accompanying humidity, regeneration temperature, and so on. With a suitable combination of

βc, βp, βr ) fractional cross-sectional area of the cooling, process, and regeneration zones, respectively φ ) relative humidity of the feed air (%) Λopt ) optimal heat capacity ratio defined by eq 3 Fb, Fg ) bulk density of the honeycomb rotor and air density in the feed stream, respectively (kg/m3) Literature Cited (1) Kodama, A.; Goto, M.; Hirose, T.; Kuma, T. Experimental Study of the Optimal Operation for a Honeycomb Adsorber Operated with Thermal Swing. J. Chem. Eng. Jpn. 1993, 26, 530. (2) Kodama, A.; Goto, M.; Hirose, T.; Kuma, T. Performance Evaluation for a Thermal Swing Honeycomb Rotor Adsorber Using a Humidity Chart. J. Chem. Eng. Jpn. 1995, 28, 19. (3) Kodama, A.; Andou, K.; Ohkura, M.; Goto, M.; Hirose, T. Process Configurations and Their Performance of an Adsorptive Desiccant Cooling Cycle for Use in a Damp Climate. J. Chem. Eng. Jpn. 2003, 36, 819. (4) Okano, H.; Jin, W-L.; Hirose, T. Field Test of Adsorptive Desiccant Air-Conditioning System Utilizing Waste Heat from Micro-Gas-Turbine Dynamos. Kagaku Kogaku Ronbunshu 2002, 28, 726. (5) Jin, W-L.; Kodama, A.; Goto, M.; Hirose, T. An Adsorptive Desiccant Cooling Using Honeycomb Rotor Dehumidifier. J. Chem. Eng. Jpn. 1998, 31, 706. (6) Matsukuma, Y.; Matsushita, Y.; Kakigami, H.; Inoue, G.; Minemoto, M.; Yasutake, A.; Oka, N. Study on CO2 Recovery System from Flue Gas by Honeycomb Type Adsorption 1 (Results of Test and Simulation). Kagaku Kogaku Ronbunshu 2006, 32, 138. (7) Matsukuma, Y.; Sadagta, K.; Kakigami, H.; Inoue, G.; Minemoto, M.; Yasutake, A.; Oka, N. Study on CO2 Recovery System from Flue Gas by Honeycomb Type Adsorption 2 (Optimization of CO2 Recovery System and Proposal of Actual Plant). Kagaku Kogaku Ronbunshu 2006, 32, 146. (8) Ko, D.; Kim, M.; Moon, I.; Choi, D.-K. Analysis of Purge Gas Temperature in Cyclic TSA Process. Chem. Eng. Sci. 2002, 57, 179. (9) Gales, L.; Mendes, A.; Costa, C. Recovery of Acetone, Ethyl Acetate and Ethanol by Thermal Pressure Swing Adsorption. Chem. Eng. Sci. 2003, 58, 5279. (10) Sullivan, P. D.; Rood, M. J.; Dombrowski, K. D.; Hay, K. J. Capture of Organic Vapors Using Adsorption and Electrothermal Regeneration. J. EnViron. Eng. 2004, March, 258.

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(11) Nastaj, J. F.; Ambrozek, B.; Rudnicka, J. Simulation Studies of a Vacuum and Temperature Swing Adsorption Process for the Removal of VOC from Waste Air Streams. Int. Commun. Heat Mass Transfer 2006, 33, 80. (12) Matsukuma, Y.; Takatani, S.; Inoue, G.; Minemoto, M.; Kamishita, N. Optimization of Rotor-Type Solvent Recovery System for LowConcentration Solvent. Kagaku Kogaku Ronbunshu 2006, 32, 402. (13) Matsukuma, Y.; Takatani, S.; Inoue, G.; Minemoto, M.; Kamishita, N. Optimization of Rotor-Type Solvent Recovery System for LowConcentration Solvent (Optimization with Gas Concentration, Flow Rate Change and Adsorption Deterioration). Kagaku Kogaku Ronbunshu 2006, 32, 477. (14) Kuma, T.; Mitsuma, Y.; Ota, Y.; Hirose, T. Removal Efficiency of Volatile Organic Compounds, VOCs, by Ceramic Honeycomb Rotor Adsorbents. Fundamentals of Adsorption, Proceedings of the International Conference on Fundamentals of Adsorption, 5th; LeVan, M. D., Ed.; Kluwer: Boston: 1996; p 481. (15) Mitsuma, Y.; Ota, Y.; Hirose, T. Performance of Thermal Swing Honeycomb VOC Concentrators. J. Chem. Eng. Jpn. 1998, 31, 482.

(16) Keller, G. E., II. Adsorption: Building upon a Slid Foundation. Chem. Eng. Prog. 1995, Oct, 62. (17) Mitsuma, Y.; Kuma, T.; Yamauchi, H.; Hirose, T. On Improvement and Scaling-up of Thermal Swing Honeycomb Adsorbent for VOC Concentrators. Kagaku Kogaku Ronbunshu 1998, 24, 248. (18) Kuma, T.; Okano, H. Active Gas Absorbing Element and Method of Manufacturing. U.S. Patent 4,886,769, 1989. (19) Kuma, T. Method of Manufacturing A Gas Absorbing Element or Catalyst Carrier Having A Honeycomb Structure. U.S. Patent 5,194,414, 1993. (20) Kuma, T. Gas Adsorbing Element and Method for Forming Same. U.S. Patent 5,348,922, 1994.

ReceiVed for reView September 8, 2006 ReVised manuscript receiVed February 26, 2007 Accepted April 4, 2007 IE061184E