exergy analysis of methane steam reformer utilizing

ISIJ International, Vol. 50 (2010), No. 9, pp. 1311–1318

1. Introduction

Steam reforming of natural gas is one of the most com-mon methods of producing hydrogen.1–3) In this method,natural gas is reacted with water to produce hydrogen at700–1 100°C. Because this reaction is endothermic, somenatural gas is combusted as fuel. However, from the view-point of energy cascade utilization,4–13) fossil fuels such asnatural gas should be used for high temperature processes,given their large potential as heat sources for temperaturesgreater than 2 000°C, and chemical process plants shouldrun on the waste heat from this high temperature process.Although it is well known that hydrogen separation byusing membrane shifts the equilibrium of the steam reform-ing reaction and reduces the reaction temperature,14–17) thisis still an endothermic reaction and the reaction heat neces-sary does not change. Therefore, the heat supply is an im-portant factor for sustainable hydrogen production. Severalresearchers have proposed new hydrogen production sys-tems that run on nuclear energy.18,19) In such systems, thereaction heat for methane steam reforming is supplied by anuclear reactor and the natural gas is only a reactant and nota fuel.

Waste heat from a high temperature process can also bean important heat source for steam reforming. One of themost common high temperature industries is the steelmak-ing one. Japanese steelmaking consumes up to 11% of thetotal national primary energy and releases 45% of it in the

form of waste heat.10) Although many equipments for energy saving have been introduced since the two oil crises,the high temperature waste such as blast furnace (BF) slagand LD converter slag still remains unused despite the hugepotential. Several reports6–13) describe methods to save energy and decrease carbon dioxide emissions. The LDconverter also releases high temperature waste gas (LDG),which has a temperature of over 1 873 K (1 600°C) and isproduce as a result of the oxygen stream blowing into theconverter. Most of its sensible heat is wasted despite itslarge potential.10) This is mainly because the temperature ofLDG is too high for efficient recovery with conventionaltechnologies and the emission is intermittent, not constant,due to unsteady operation: that is, charging of hot iron,oxygen blowing for de-carbonization, and discharging ofsteel. In addition, the incomplete seal created by the skirtsaround the converter makes direct heat recovery from LDGmore difficult. Existing off-gas (OG) boilers may be effec-tive for recovering heat from lower temperature LDG, butnot at higher temperarures.10) Therefore, a new technologyis needed to utilize the LDG heat at over 1 273 K (1 000°C).We proposed a heat recovery system in which the wasteheat intermittently emitted from the abovementionedprocesses was stored in the form of latent heat10–13,20–24) andefficiently converted into chemical energy by an endother-mic reaction6,7,10–13,20,21) such as the methane steam reform-ing reaction. From the viewpoint of energy cascade utiliza-tion,4–13) it is important to use high temperature waste heat

Exergy Analysis of Methane Steam Reformer UtilizingSteelmaking Waste Heat

Nobuhiro MARUOKA,1) Hadi PURWANTO2) and Tomohiro AKIYAMA3)

1) Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira Aoba-ku, Sendai 987-8577Japan. E-mail: [email protected] 2) Faculty of Engineering, International Islamic University Malaysia, JalanGombak 53 100 Kuala Lumpur, Malaysia . 3) Center for Advanced Research of Energy Conversion Materials, HokkaidoUniversity, Kita 13 Nishi 8, Kita-ku, Sapporo, 060-8628 Japan. E-mail: [email protected]

(Received on December 4, 2009; accepted on April 30, 2010 )

System analysis was conducted on a proposed combined system for methane steam reforming compris-ing conventional hydrogen production and waste heat recovery from steelmaking. Operating data for a con-ventional methane steam reforming system were collected and analyzed. The results showed that the con-ventional system utilized only 60% of the natural gas as raw material and the rest is consumed for supply-ing the reaction heat for methane steam reforming. On the basis of this data, the proposed system wasevaluated on five factors—natural gas consumption, enthalpy flow, CO2 emission, cost, and exergy loss. Forthe proposed system, the factors were only 59.6%, 59.7%, 62.8%, 86.5%, and 65.8% of those of theconventional system, respectively. This supports the feasibility of hydrogen production from recoveredwaste heat. Furthermore, the proposed system is expected to contribute to the production of ‘green’ hydro-gen that incurs less CO2 emission.

KEY WORDS: steam reforming; hydrogen production; system evaluation; exergy analysis; waste heat re-covery; steelmaking.

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as a heat source in the chemical industry. The previousstudy10) found that recovery of steelmaking waste heat wasfeasible on the assumption that only methane steam reform-ing occurs and that it proceeds completely without heatloss. The results showed that the reduction in carbon diox-ide emission by using the waste heat of Japanese steelworksis as high as 2.05 Mt per year. However, in practice, hydro-gen production involves many processes, with heat loss atevery stage. Therefore, the aim of this study is to analyzeoperating data of a conventional hydrogen production sys-tem and use this data to evaluate the feasibility of a pro-posed system that includes waste heat recovery from steel-works. Operating data collection, material and heat balanceanalyses, exergy analysis, and cost evaluation were carriedout to assess the entire system. The results indicate the pos-sibility of industrializing a process for producing hydrogenfrom recovered waste heat. Furthermore, the proposed sys-tem will contribute to the production of green hydrogen,which results in less carbon dioxide emission.

2. Analysis Method for the Conventional HydrogenProduction System

This study analyzes a hydrogen production system that istypically industrialized using a steam reformer with a pro-ductivity of 814 Nm3-H2/d. Figure 1 shows the schematicdiagram of the conventional hydrogen production system.This system consists of 3 main components: a reformer, ashift reactor, and pressure swing adsorption (PSA) system.The main process for the production of hydrogen is steamreforming of natural gas, whose major component ismethane (see Appendix). Steam and natural gas are used asraw materials and supplied into a steam reformer. Thesteam reformer is a radiant tube heated by the combustionof natural gas in the heating furnace. In this process, naturalgas reforms into water gas whose composition is 77.4%-H2,12.6%-CO, 8.6%-CO2, and 1.4%-CH4. The main reactionin the reformer is

...(1)

Water gas is introduced into the shift reactor through a

combination boiler in which the sensible heat of water gasis recovered by supplying heat to steam. In the shift reactor,the water gas is converted into a mixture gas whose compo-sition is 78.4%-H2, 2.6%-CO, 17.5%-CO2, and 1.4%-CH4.The main reaction in the shift reactor is:

...(2)

Finally, the PSA system purifies the mixture gas to99.999% of hydrogen. PSA offgas, whose composition is47.4%-H2, 6.36%-CO, 42.8%-CO2 and 3.42%-CH4, is burntin the heating furnace in order to supply reaction heat forsteam reforming. A portion of the refined hydrogen is intro-duced into the steam reformer for protecting the catalyst.

3. The Method of System Analysis

A system defined as a set of processes is represented by anumber of processes, as illustrated in Fig. 2. In the formu-lation of the hydrogen production system, first, the targetsystem was resolved into its component elements. The cir-cle in this figure represents a process, and the solid-line ar-rows toward and away from the circle denote the substancesbefore and after the change, respectively. The white arrowsrepresent the intermediary energy that is either released oraccepted energy such as heat, work, electricity, and light.The dotted line represents the system boundary, which does

CO H O CO H 4 kJ/mol2 2 2� � ��→ ΔH298 1

CH H O CO 3H 206 kJ/mol4 2 2� � �→ ΔH298

ISIJ International, Vol. 50 (2010), No. 9

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Fig. 1. Schematic diagram of the conventional hydrogen production system, which consists of reformer, heating furnace,combination boiler (C.B.), shift converter, preheating of gas (P.H. of gas), preheating of water (P.H. of water),pump, degasifier, cooling, water separator, pressure swing adsorption (PSA) and off-gas holder.

Fig. 2. Description of a process. Open circle shows a process, incontrast, solid-line arrow shows the flow of substance,and white open arrow, the flow of intermediary energysuch as heat, work, electricity and light. The doted line isthe system boundary.

not intersect any flow of intermediary energy.Then, operating data of the temperature, composition,

and pressure of substances were collected for each processto calculate the material balances; the difference was ad-justed to be about 0.01% of the input substance elementary.Third, the enthalpy and exergy are analyzed by the modifiedenthalpy method. The amount of heat loss is calculatedfrom the difference between input and output enthalpies.The results of enthalpy and exergy balances are representedby the enthalpy and exergy flow charts. Finally, the amountof CO2 emission and the production cost were evaluated.

4. Modified Enthalpy Method

In calculating enthalpy in general, we use standard con-ditions of 298.15 K (T0), 0.101325 MPa (P0) and define theenthalpy of all elements as zero. This is so called standardformation of enthalpy or standard heat formation, expressedby DH0 (kJ/mol). Based on this definition, the DH0 value ofcompounds is always negative. For example, regarding tocarbon, the enthalpy of carbon element is zero and the enthalpy of CO2 to be a negative value (�393.5 kJ/mol).However, in the balance sheet of enthalpy, the use of nega-tive value in- and out-flows of enthalpy is quite inconven-ient. In this study, therefore, we employed so-called “modi-fied enthalpy”13) for the analysis of the systems by changingthe definition of a standard substance. In calculating themodified enthalpy, we take T0, P0 as standard conditionsand the most stable materials in the atmosphere, such asCO2, as standard substance. Under this definition, the en-thalpy of element C is 393.5 kJ/mol and CO2, zero at T0 andP0. The most stable substances, for instance, O2, N2, H2O(l), Fe2O3, CaCO3, Al2O3 etc. are determined by JapaneseIndustrial Standards (JIS).

The abovementioned method gives modified standard en-thalpy of any materials, as a result the enthalpy of all mate-rials becomes positive value or zero. When a molar specificheat at constant pressure is expressed by Cp, enthalpy isgiven by the following equations:

......(3)

............(4)

where C�p,av is defined as an average specific heat(kJ/mol K) and obtained by modifying the following basicequation of Cp:

...............(5)

.............(6)

where, A, B, C and D are constants of average specific heatthat modified from a, b, c and d, respectively. The thermo-dynamic data base provides the values of a, b, c, and d as afunction of temperature. Therefore, re-arrangement of theoriginal data of specific heat into average specific heatvalue will be useful for calculating the enthalpy balance ofthe substances.

5. Results and Discussions

Figure 3 shows the process system diagram. The con-ventional system analyzed in this thesis consists of 12 unitsystems. Overall, air, natural gas, and water flow into thesystem while air, water, hydrogen, offgas, and waste gasflow out from the system. Apart from substances, worksources such as an electricity supply energy to the systemand then effectively unexploited energy is released to theheat sink (HS) in the form of intermediary energy.

Two types of natural gas exist: raw material consumed inthe reformer and fuel combusted in the heating furnace.First, natural gas as a raw material is pressurized to2.29 MPa using a compressor. It is then preheated to 618 Kby the waste heat of the mixture gas produced in the shiftconverter. Thereafter, it is introduced into the reformer

′C T A BT CT DTp,av ( ) ( )� � � ��2 2

C T a bT cT dTp ( ) ( )� � � ��2 2

′ ∫C C T dT TT

p,av p� �298 15

298 15.

( ) /( . )

H T H

C T dT C T TT

( ) ( . )

( ) ( )( . ).

�

� � �

298 15

298 15298 15∫ ′p p,av


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Fig. 3. Process-system diagram of the conventional hydrogen production system. (C.B.: combination boiler, P.H.: pre-heater, Comp: compressor, HS: heat sink, PSA: pressure swing adsorption).

along with a part of the produced hydrogen for preventingthe deactivation of the catalyst. Natural gas as fuel is com-busted in the heating furnace for supplying the heat required by the reformer.

Water is first flowed into the degasifier for removing dis-solved air and then pressurized to 2.78 MPa using thepump, third preheated to 418, 473 and 753 K at water pre-heater, combination boiler and steam preheater, respec-tively. Finally, it is introduced into the reformer. A part ofthe steam—called by-product steam—that is preheated inthe combination boiler flows out and is utilized in the othersystem. This implies that an extremely high amount of fuelis consumed for heating the by-product steam.

In the reformer, preheated natural gas and steam are reformed to water gas with the help of nickel based cata-lyst; here, the reaction heat is supplied from the heating fur-nace in the form of intermediary energy. Next, using theshift reaction, the water gas is converted to the mixture gaswith Fe–Cr catalysts in the shift reactor, thereby increasingthe hydrogen composition. Finally, the mixture gas is intro-duced to a PSA system for purifying hydrogen. The offgasfrom the PSA system is then combusted with air in a heat-ing furnace to generate the heat required for the reformer. Itshould be noted that a part of the offgas is still not utilizedefficiently. Sensible heats of gases are recovered in the com-bination boiler (C.B.) and degasifier for preheating water,steam, and natural gas, as well as by the gas preheater (P.H.of gas) and water preheater (P.H. of water).

Table 1 shows the total material, enthalpy, and exergybalances per unit volume of 1 Nm3-H2 of the conventionalhydrogen production system. In this system, 1 Nm3 of hy-drogen is actually produced with 0.57 Nm3 of natural gas,although the theoretical value of methane required for pro-ducing hydrogen is 0.31 Nm3-CH4/Nm3-H2 (see Table 2). Inpractice, 0.34 and 0.23 Nm3 of natural gas are consumed asraw material and fuel, respectively. This implies that asmuch as 40.3% of the input natural gas is consumed forcombustion in order to supply the reaction heat of methanesteam reforming, despite the theoretical value being only18.7%. The main reason for these phenomena is that theactual operation is not ideal. This implies that the reaction

does not proceed completely and that heat loss occurs, lead-ing to increments of exergy loss, cost, and carbon dioxideemission, as mentioned below. Appendix lists the operatingdata of each process in the conventional hydrogen produc-tion system. The input and output substances are listed foreach of the 12 processes, which includes the temperature,flow rate, compositions, enthalpy, and exergy.

Figure 4 shows the enthalpy flowchart of the conven-tional hydrogen production system for facilitating the visu-alization of Appendix. The white and black blocks repre-sent the substances and processes, respectively. The grayblock arrows show the heat loss from each process. The


1314© 2010 ISIJ

Table 1. The overall material, enthalpy and exergy balances inthe conventional hydrogen production system.

Table 2. Theoretical value and operating data of methane required for producing hydrogen.

Fig. 4. Enthalpy flowchart of the conventional hydrogen production system, in which in- and out-flows of enthalpy in theeach processes (see Fig. 2) were calculated based on the modified enthalpy method.

material flow is already explained in Fig. 3. In the reformer,natural gas and steam are reformed into the water gas byheat absorption from the heating furnace; here, only 1.84MJ/Nm3-H2 and 3.88 MJ/Nm3-H2 in thermal and chemicalenthalpies increase, respectively, although enthalpies ashigh as 10.0 MJ/Nm3-H2 are consumed in the heating fur-nace. Furthermore, PSA offgas which chemical enthalpy is5.2 MJ/Nm3-H2 is also combusted in the heating furnace.This value approximately corresponds to the enthalpy accepted from the heating furnace. Thus, only 25.5% of theinput enthalpy of the heating furnace is accepted in theform of chemical enthalpy by reforming methane. This iscaused by enormous heat losses from each process in com-parison to the input enthalpy in each system: 30.2%,15.5%, 0.74%, 0.73%, and 0.31% in the heating furnace,combination boiler, water preheater, degasifier, and reactantpreheater, respectively. The temperature of processes alsodecreases in the same order as above. The total heat loss ofthe conventional system is approximately equal to the enthalpy of input natural gas as a fuel. In consequence, theenthalpy of the produced hydrogen, 51.2% of total inputenthalpy, is less than that of the input natural gas as a rawmaterial, 59.7% of the total input enthalpy. In other words,the enthalpy of natural gas as a fuel was mainly lost as heatloss. If the heat required for the reaction is supplied by non-fossil fuels as waste heat, hydrogen can be produced byusing less natural gas.

Figure 5 shows the exergy flowchart of the conventionalhydrogen production system. In the analysis, the process isrepresented as a black trapezium because the exergy is notconserved; the exergy represents the quality of energy regardless of the enthalpy conservation between the inputand output of substances. The difference between the inputand output substances shows the exergy loss. The resultsshowed that the heating furnace is the major contributor ofexergy loss. This is because methane and carbon monoxideare converted into water and carbon dioxide in the heatingfurnace; the former reaction yields a large exergy while thelatter yields a small exergy. The exergy losses are 59.5%,11.9%, 0.68%, 0.53%, and 0.31% in the heating furnace,combination boiler, preheating of water unit, degasifier, andreactant preheater, respectively.

In the steam reformer, the thermal and chemical exergiesincrease 1.14 and 1.83 MJ/Nm3-H2, respectively. However,the exergy loss of a heating furnace is 11.63 MJ/Nm3-H2.Thus, only 15.7% of the exergy is utilized. In the hydrogenproduction system, the exergy loss of a shift reactor is mini-mum because there is no combustion. According to the exergy analysis, the reaction heat of reforming methaneshould be supplied from the waste heat because the exergyloss of the heating furnace is very large.

In the previous study,10–13) a new hydrogen productionsystem that utilizes waste heat was proposed. Figure 6shows the proposed hydrogen production system that iscombined with waste heat recovery of steelworks; here, theheating furnace is replaced by the high temperature processof steelworks. High temperature waste is first introducedinto the heat exchanger, then supplied for reformingmethane, and finally converted to chemical energy throughan endothermic reaction. The estimation was performedunder the assumption that waste heat is recovered from thehigh temperature of wastes reduced to a low temperature of423 K. Figure 7 shows the comparison of the exergy lossbetween the conventional and proposed hydrogen produc-tion systems. The exergy loss of a steam reformer in theconventional system, including a heating furnace and asteam preheater is 69.3% of the total exergy loss. The pro-posed system can achieve a drastic reduction in the exergyloss of the reformer. The exergy of natural gas is larger thanthat of waste heat. The energy levels—the ratio between enthalpy and exergy—of natural gas and waste heat at1 500 K are 0.97 and 0.67, respectively. Consequently, thetotal exergy loss is reduced to 65.8% in comparison withthe conventional hydrogen production system.

The temperatures of LD gas and slags are 1 773 and1 823 K, respectively (see Table 3). Table 4 lists the advan-tages of the proposed system for supplying waste heat tothe production of hydrogen. In this evaluation, the cost ofraw materials, primary cost, exergy loss, and amounts ofinput natural gas, total input enthalpies, and carbon dioxideemission, were calculated. The prime cost was estimated byadding 20 yen to the raw material cost as cost of the equip-ment, employment, and transportation. The results showedthat the proposed steam reformer can improve to 59.7%,


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Fig. 5. Exergy flow diagram of the conventional hydrogen production system.

62.8%, 86.5%, and 65.8% for the energy consumption,carbon dioxide emission, primary cost, and exergy loss, respectively.

Table 5 shows the predicted capacity of hydrogen pro-duction and the reduction of carbon dioxide emission byusing the high temperature waste heat of steelworks. Theresults show that 82.5 Nm3/steel of hydrogen can be pro-duced by utilizing waste heats of LD gas, BF, and LD slags.If the entire waste heat produced by Japanese steelworks issupplied for hydrogen production, 5.6 billion Nm3 of hy-drogen can be produced. This value corresponds to theamount of fuel required for 4.3 million FC-vehicles peryear. Similarly, the amount of carbon dioxide emission can

be reduced by 44.3 kg/steel and 3.3 Mt/year in the proposedsystem. This value corresponds to as much as 0.26% of theJapanese yearly emission.

6. Conclusions

The proposed hydrogen production system utilizing thewaste heat of steelworks was evaluated by analyzing theconventional system based on actual operating data.

The analysis of the conventional system showed the fol-lowing:

(1) For producing 1 Nm3 of hydrogen, the conventionalsystem uses 0.34 Nm3 of natural gas as raw material and0.23 Nm3 of natural gas as fuel and emits 1.48 kg of carbondioxide.

(2) Heat losses are 30.2%, 15.5%, 0.74%, 0.73%, and0.31% for the heating furnace, combination boiler, waterpreheater, degasifier, and reactant preheater, respectively.


1316© 2010 ISIJ

Fig. 6. Schematic diagram of the proposed two hydrogen production systems in the LD converter and the slag treatment.Heat required for methane steam reforming is supplied by the waste heat in the steelworks; (A) LD converter: Aheat exchanger with Phase Change material (PCM) can save intermittently emitted waste heat from a batch-wiseLD converter by melting the PCM and supply it to the endothermic reaction of methane steam reforming by solid-ifying the PCM.10,11) (B) Slag granulation treatment: A rotary cup atomizer (RCA) can granulate molten slag fromthe blast furnace (BF) and LD converter by centrifugal force and it is directly cooled by endothermic reaction ofmethane steam reforming. The reactive gas of methane and steam and the hot slag drops are countercurrently pre-heated through the moving bed.8)

Fig. 7. Comparison of exergy loss between the conventional andproposed hydrogen production systems.

Table 3. Waste heat of high temperature in the Japanese steel-making industry.

Table 4. Comparison of energy requirement, carbon dioxideemission, primary cost and exergy loss between theconventional system and the proposed one for hydro-gen production.

Table 5. Estimation of hydrogen production and reduction ofcarbon dioxide emission in the proposed system.

The total heat loss of the conventional system is approxi-mately equal to the enthalpy of the input natural gas as afuel.

(3) Exergy losses are 59.5%, 11.9%, 0.68%, 0.53%,and 0.31% for the heating furnace, combination boiler,water preheater, degasifier, and reactant preheater, respec-tively. The total exergy loss is 12.03 MJ/Nm3-H2.

The proposed hydrogen production system has the fol-lowing possibilities:

(4) In the production of hydrogen, the proposed systemuses only 0.34 Nm3 of natural gas and emits only 0.93 kg ofCO2.

(5) The energy consumption, carbon dioxide emission,primary cost, and exergy loss decrease to 59.7%, 62.8%,86.5%, and 65.8%, respectively.

(6) The utilization of waste heat of steelworks can leadto the production of 5.6 billion Nm3 in hydrogen and reducethe carbon dioxide emission to 3.3 Mt annually.

Acknowledgements

This research was partially supported by the New Energyand Industrial Technology Development Organization(NEDO), Japan.

Operating data of the hydrogen production system wasprovided by Nippon Steel Corporation Yawata Works.

REFERENCES

1) O. F. Dilmac and S. K. Ozkan: Int. J. Exergy, 5 (2008), No. 2, 241.2) P. Bernardo, G. Barbieri and E. Drioli: Chem. Eng. Sci., 65 (2010),

No. 3, 1159.3) J. Xu, Froment, and F. Gilbert: AIChE J., 35 (1989), No. 1, 88.4) Y. Shimazaki, A. Akisawa and T. Kashiwagi: Proc. of the Int. Conf.

on Thermodynamic Analysis and Improvement of Energy Systems,TAIES’97, Chinese Society of Engineering Thermophysics and

American Society of Mechanical Engineers, Beijig, (1997), 313.5) N. Hayajawam, Y. Wakazono, T. Kato, Y. Suzuoki and Y. Kaya:

IEEE Trans. Energy Convers., 14 (1999), No. 3, 795.6) T. Akiyama, K. Oikawa, T. Shimada, E. Kasai and J. Yagi: ISIJ Int.,

40 (2000), No. 3, 286.7) T. Akiyama, H. Sato, A. Muramatsu and J. Yagi: ISIJ Int., 33 (1993),

No. 11, 1136.8) T. Mizuochi, T. Akiyama, T. Simada, E. Kasai and J. Yagi: ISIJ Int.,

41 (2001), No. 2, 1423.9) T. Akiyama and J. Yagi: ISIJ Int., 38 (1998), No. 8, 896.

10) N. Maruoka and T. Akiyama: ISIJ Int., 42 (2002), No. 11, 1189.11) N. Maruoka, T. Mizuochi, H. Purwanto and T. Akiyama: ISIJ Int., 44

(2004), No. 2, 257.12) N. Maruoka and T. Akiyama: Energy, 31 (2006), No. 10–11, 1632.13) H. Purwanto, N. Maruoka and T. Akiyama: J. Chem. Eng. Jpn., 39

(2006), No. 5, 531.14) S. A. Simakov and M. Sheintuch: AIChE Annual Meeting, Conf.

Proc., American Institute of Chemical Engineers, New York, (2005),10123.

15) S. A. Simakov and M. Sheintuch: AIChE J., 54 (2008), No. 10, 2735.16) J.-H. Kim, B.-S. Choi and J. Yi: J. Chem. Eng. Jpn., 32 (1999), No.

6, 760.17) S. Wieland, T. Melin and A. Lamm: Chem. Eng. Sci., 58 (2002), No.

12, 2551.18) H. Sato, H. Ohashi, Y. Inaba, T. Nishihara, K. Hayashi and Y. Ina-

gaki: Trans. Atomic Energy Soc. Jpn, 5 (2006), No. 4, 292.19) T. Nishihara and Y. Inagaki: Nucl. Technol., 153 (2006), No. 1, 100.20) N. Maruoka, K. Sato, J. Yagi and T. Akiyama: ISIJ Int., 42 (2002),

No. 2, 215.21) N. Maruoka and T. Akiyama: J. Chem. Eng. Jpn., 36 (2003), No. 7,

794.22) A. Kaizawa, H. Kamano, A. Kawai, T. Jozuka, T. Senda, N.

Maruoka, N. Okinaka and T. Akiyama: ISIJ Int., 48 (2008), No. 4,540.

23) A. Kaizawa, N. Maruoka, A. Kawai, H. Kamano, T. Jozuka, T. Sendaand T. Akiyama: Heat Mass Trans./Waerme- und Stoffuebertragung,44 (2008), No. 7, 763.

24) A. Kaizawa, H. Kamano, A. Kawai, T. Jozuka, T. Senda, N. Maruokaand T. Akiyama: Energy Convers. Manag., 49 (2008), No. 4, 698.


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