Hostname: page-component-76fb5796d-skm99 Total loading time: 0 Render date: 2024-04-26T15:00:16.062Z Has data issue: false hasContentIssue false
  • English
  • Français

Conversion of Organic Streams in Supercritical Water

Published online by Cambridge University Press:  15 February 2011

Eckhard Dinjus ,
Nikolaos Boukis ,
Johannes Abeln  and
Andrea Kruse
Eckhard Dinjus
Affiliation:
ITC-CPV, Forschungszentrum Karlsruhe, Herrmann von Helmholtz Platz 1, 76344 Karlsruhe, Germany
Nikolaos Boukis
Affiliation:
ITC-CPV, Forschungszentrum Karlsruhe, Herrmann von Helmholtz Platz 1, 76344 Karlsruhe, Germany
Johannes Abeln
Affiliation:
ITC-CPV, Forschungszentrum Karlsruhe, Herrmann von Helmholtz Platz 1, 76344 Karlsruhe, Germany
Andrea Kruse
Affiliation:
ITC-CPV, Forschungszentrum Karlsruhe, Herrmann von Helmholtz Platz 1, 76344 Karlsruhe, Germany
Get access

Abstract

Thermal treatment of aqueous streams loaded with organics can be efficiently performed at pressures and temperatures above the critical data for water (Pc = 22.1 MPa, Tc = 374 °C). Two applications are under investigation using supercritical water (SCW) as solvent and reactant: supercritical water oxidation (SCWO) and supercritical water gasification (SCWG).

SCWO is typically operated at 25-35 MPa and 600-900 °C, because water, oxygen (or air), CO2 and most of the organics form a single fluid phase with rapid oxidation kinetics. Thus, SCWO can be processed with high space-time yield and in some cases self-sustaining.

Moreover, expensive off-gas treatment is prevented because NOx formation is suppressed. Other heteroatoms form acids like HCl, H2SO4 and H3PO4 or their corresponding salts. However, acids may lead to corrosion, formation or presence of salts to plugs.

To avoid these problems a transpiring wall reactor (TWR) has been developed and installed. Results of SCWO of different industrial effluents are very promising. Destruction of the organic waste compounds was close to 100 %, even for effluents containing solids and salts up to 5%wt., each.

In accompanied studies material tests have been performed. Long time runs clearly indicate that alloy 625 is most suited to withstand the aggressive environment at temperatures higher than about 500 °C. A corrosion mechanism has been proposed.

The SCWG process of biomass is performed under SCW conditions. The aim of this work is to study the conversion of biomass (e.g.) to fuel gas with high energetic value. R&D is focused on process optimization particularly with respect to energy efficiency as well as applicability to extended feedstocks even with high amounts of solids. At SCW conditions organic matter reacts with water to form a hydrogen containing gas. The feed carbon is converted preferentially to CO2, which can be separated by e.g. stripping, and to methane. While the organic carbon is oxidized to CO2, water is reduced to from hydrogen, e.g. for glucose:

C6H12O6 + 6 H2O → 6 CO2 + 12 H2

In basic studies of the biomass gasification, the main reaction pathways were identified. In addition the influence of ingredients of biomass and additives / catalysts was investigated. Here the influence of salts is of special interest, because biomass with an high water content, which is most suitable for the SCWG process, usually contain high salt contents. The changes in selectivity of different reaction pathways observed, opens the possibility to manipulate the chemistry of biomass gasification in supercritical water. Therefore high gas yields with different feedstock of various compositions can be achieved.

SCWG process is performed using efficient heat exchangers at SCW conditions.

Compression work is low since non compressible water slurry is pressurized. The reaction of the organic substances with water proceeds fast and completely, thus with high space-time yield. At about 600 °C and 25 MPa high gasification yield can be achieved. Advantageously, formation of CO, tar and char is low enhancing the efficiency of the SCWG process.

Consequently, based on lab scale plants, a 100 kg/h SCWG plant called Verena has been installed and is operated since few years. A high thermal efficiency of about 80% for diluted educt streams (only 5 wt% OM) has been measured. Experimental results with the Verena plant confirmed the production of a hydrogen rich gas and the high thermal efficiency of the process.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 884: Symposium GG – Materials and Technology for Hydrogen Storage and Generation , 2005 , GG5.3
Copyright
Copyright © Materials Research Society 2005

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

[1] Schmieder, H.; Abeln, J., SCWO: Facts and Hopes, Chem. Eng. Technol. 11, 1999, p. 903–908 Google Scholar
[2] Vogel, F.; Smith, K.A.; Tester, J.W.; Peters, W.A: Engineering Kinetics for Hydrothermal Oxidation of Hazardous Organic Substances, AlChE Journal, 48 (8), 2002, p.1827–1839 Google Scholar
[3] Abeln, J., Kluth, M., Böttcher, M., Sengpiel, M.: Supercritical Water Oxidation (SCWO) Using a Transpiring Wall Reactor: CFD Simulations and Experimental Results of Ethanol Oxidation, Environmental Engineering Science 21, 2004, p.93–99 Google Scholar
[4] Wellig, B.; Lieball, K.; vonRohr, P.R.: Transpiring Wall Reactor for SCWO-Experimental Results, Proc. High Pressure in Venice, 22–25 9 2002 Google Scholar
[5] Hodes, M.; Marrone, P.A.; Hong, G.T.; Smith, K.A.; Tester, J.W.: Salt precipitation and scale control in supercritical water oxidation – Part A: fundamentals and research, Journal of Supercritical Fluids, 29, 2004, p.265–288 Google Scholar
[6] Kritzer, P.; Boukis, N.; Dinjus, E., Corrosion of Alloy 625 in High-Temperature, High-Pressure Sulfate Solutions, Corrosion 54, 1998, p.689–699 Google Scholar
[7] Marrone, P.A.; Hodes, M.; Smith, K.A.; Tester, J.W., Salt precipitation and scale control in supercritical water oxidation – part B: commercial/full-scale applications, Journal of Supercritical Fluids, 29, 2004, p. 288–312 Google Scholar
[8] Abeln, J.; Kluth, M.; Petrich, G.; Schmieder, H., Supercritical Water Oxidation (SCWO): A Process for the Treatment of Industrial Waste Effluents, High Pressure Research 20, 2001, p.537–547 Google Scholar
[9] Abeln, J.; Kluth, M.; Schmieder, H., Petrich, G., Waste Treatment by SCWO Using a Pipe and a Transpiring Wall Reactor, Proceedings of the Joint ISHR&ICSTR, Kochi, Japan, July 25-28, 2000, p. 191–194 Google Scholar
[10] Goldacker, H., Abeln, J., et al.: Oxidation of Organic Material in Supercritical Water and Carbon Dioxide, 3rd International Symposium on High Pressure Chemical Engineering, Zürich, 7.-9.10.1996 Google Scholar
[11] McGuinness, T.G.: Supercritical Oxidation Reactor Apparatus and Method, PCT, WO 94/ 18128, 18.8.94 Google Scholar
[12] Boukis, N., Franz, G., Habicht, W., Dinjus, E., Corrosion resistant materials for SCWOapplications. Experimental results from long-time experiment, NACE, Corrosion 2001, USA, Paper No. 01353Google Scholar
[13] Boukis, N., Habicht, W., Franz, G., and Dinjus, E., Behavior of Ni-base alloy 625 in methanol - supercritical water systems, Materials and Corrosion Vol. 54, 5, 2003, 326–330 Google Scholar
[14] Kritzer, P.; Boukis, N. and Dinjus, E., Review of the Corrosion of Nickel-Based Alloys and Stainless Steels in Strongly Oxidizing Pressurized High-Temperature Solutions at Subcritical and Supercritical Temperatures, Corrosion, 56, 2000,1093–1104 Google Scholar
[15] Sinag, A., Kruse, A., and Rathert, J., Influence of the Heating Rate and the Type of Catalyst on the Formation of Selected Intermediates and on the generation of Gases during Hydropyrolysis of Glucose with Supercritical Water in a Batch Reactor, Ind. Eng. Chem. Res 43, 2004, p. 502–508.Google Scholar
[16] Bühler, W., Dinjus, E., Ederer, H. J., Kruse, A., and Mas, C., Ionic reactions and pyrolysis of glycerol as competing reaction pathways in near- and supercritical water, The Journal of Supercritical Fluids 22, 2002, p. 37–53.Google Scholar
[17] Kruse, A., Meier, D., Rimbrecht, P., and Schacht, M. Gasification of Pyrocatechol in Supercritical Water in the Presence of Potassium Hydroxide, Ind. Eng. Chem. Res 39, 2000, p. 4842–4848.Google Scholar
[18] Sinag, A., Kruse, A., and Schwarzkopf, V., Key compounds of the Hydropyrolysis of glucose in supercritical water in the presence of K2CO3., Ind. Eng. Chem. Res 42, 2004, p. 3519–3521.Google Scholar
[19] Kruse, A. and Gawlik, A.; Biomass Conversion in Water at 330-410°C and 30-50 MPa. Identification of Key Compounds for Indicating Different Chemical Reaction Pathways., Ind. Eng. Chem. Res. 42, 2003, p.267–279.Google Scholar
[20] Sasaki, M., Kabyemela, B., Malaluan, R., Hirose, S., Takeda, N., Adschiri, T., and Arai, K., Cellulose hydrolysis in subcritical and supercritical water, The Journal of Supercritical Fluids 13, 1998, p. 261–268.Google Scholar
[21] Antal, M. J. Jr, Mok, W. S., and Richards, G. N., Mechanism of formation of 5-(hydroxymethyl)-2-furaldehyde from D-fructose an sucrose, Carbohydrate Research 199, 1990, p. 91–109.Google Scholar
[22] Kabyemela, B. M., Adschiri, T., Malaluan, R. M., and Arai, K. Glucose and Fructose, Decomposition in Subcritical and Supercritical Water: Detailed Reaction Pathway, Mechanisms, and Kinetics, Ind. Eng. Chem. Res 38, 1999, p. 2888–2895.Google Scholar
[23] Elliott, D.C. and Sealock, L.J., Aqueous catalyst systems for the water-gas shift reaction. 1. Comparative catalyst studies, Industrial & Engineering Chemistry Product Research and Development 22, 1983, p. 426–431 Google Scholar
[24] Boukis, N., Diem, V., Habicht, W., and Dinjus, E., Methanol Reforming in Supercritical Water, Ind. Eng. Chem. Res.; Vol. 42, 728–735, 2003 Google Scholar
[25] Boukis, N., Galla, U., Diem, V., D'Jesus, P., Dinjus, E., Hydrogen generation from wet biomass in supercritical water, 2nd World Conference and Technology Exhibition on Biomass for Energy, Industry and Climate Protection, 2004, May 10-14, Rome, ETAFlorenz, ISBN 88-89407-04-2, p. 738–741 Google Scholar
[26] Diem, Volker, Boukis, Nikolaos, Hauer, Elena, and Dinjus, Eckhard, Hydrothermal Reforming of Alcohols and Bio Crude Oil, Chemical Engineering Transactions, 4, 2004, 99–104 Google Scholar
[27] Boukis, Nikolaos, Galla, Ulrich, Diem, Volker, D'Jesus, Pedro and Dinjus, Eckhard, Hydrogen production from biomass in supercritical water, Chemical Engineering Transactions, 4, 2004, 131–136 Google Scholar