Hydrothermal Biomass Gasification – Effects of Salts, Backmixing and Their Interaction

Kruse, Andrea; Faquir, M.

doi:10.1002/ceat.200600409

Cited by 61 publications

(39 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Sinag et al [64] investigated the influence of K2CO3 on the gasification of glucose. Similarly, Kruse and Faquir [65] and Kruse et al [66] tested the influence of other potassium containing alkali compounds such as KOH and KHCO3. The authors found that the presence of alkali salts increases the total gas yield as well as hydrogen yield and the amount of phenols.…”

Section: Effect Of Salts and The Role As Homogeneous Catalystsmentioning

confidence: 99%

“…For real biomass processes, rapid heating of the feed can overcome such coke and tar formation behavior as the positive effect of rapid heating on less tar production and higher gas yields are reported by other researchers [145,146] as well. Another possible solution to coke and tar formation was given by Kruse and Faquir [65]. The authors proposed a reaction process in which a continuously stirred tank reactor (CSTR) is followed by a tubular reactor in order to benefit from the "active hydrogen" formation in the CSTR due to its backmixing.…”

Section: Process Challenges and Reactor Technology Aspects For Industmentioning

confidence: 99%

See 1 more Smart Citation

Supercritical Water Gasification of Biomass: A Literature and Technology Overview

Yakaboylu

Harinck

Smit³

et al. 2015

Energies

172

View full text Add to dashboard Cite

Abstract:The supercritical water gasification process is an alternative to both conventional gasification as well as anaerobic digestion as it does not require drying and the process takes place at much shorter residence times; a few minutes at most. The drastic changes in the thermo-physical properties of water from the liquid state to the supercritical state make it a promising technology for the efficient conversion of wet biomass into a product gas that after upgrading can be used as substitute natural gas. The earliest research goes back as far as the 1970s and since then, supercritical water has been the subject of many research works in the field of thermochemical conversion of wet biomass. This article reviews the state of the art of the supercritical water gasification technology starting from the thermophysical properties of water and the chemistry of reactions to the process challenges of such a biomass based supercritical water gasification process plant.

show abstract

Section: Effect Of Salts and The Role As Homogeneous Catalystsmentioning

confidence: 99%

Section: Process Challenges and Reactor Technology Aspects For Industmentioning

confidence: 99%

Supercritical Water Gasification of Biomass: A Literature and Technology Overview

Yakaboylu

Harinck

Smit³

et al. 2015

Energies

172

View full text Add to dashboard Cite

show abstract

“…If hydrogen is the product desired, however, far higher temperatures of about 600°C are needed. Studies of hydrothermal hydrogen production from biomass [1,2] revealed that the combination of a continuously stirred tank reactor and tubular reactor is particularly advantageous [3,4]. The reason is the positive influence of backmixing at the beginning of gas formation on chemical kinetics [1,4].…”

mentioning

confidence: 98%

Measurement of Residence Time in Hot Compressed Water: 2. Salts in Continuously Stirred Tank Reactors

Kruse¹,

Ederer²,

Ernst³

et al. 2009

Chem Eng & Technol

Self Cite

View full text Add to dashboard Cite

The behavior of alkali salts in a continuously stirred tank reactor is of particular interest with respect to the development of the hydrothermal biomass gasification process. On the one hand, alkali salts increase gas formation. On the other hand, they may plug reactors due to precipitation. To obtain information on the potential enrichment of salts in continuously stirred tank reactors, cumulative residence time distribution functions were measured using K 2 CO 3 and NaHCO 3 tracers and phenol as a reference. TaskWater at high temperatures and pressures has special properties that promote the decomposition of biomass. The main product generated depends on the reaction conditions. These so-called "hydrothermal" processes have significant advantages over nearly water-free thermochemical processes. "Dry processes" require a temperature of at least 1000°C for the nearly complete conversion of the organic biomass fraction into gases. In water this is achieved already from about 340°C. If hydrogen is the product desired, however, far higher temperatures of about 600°C are needed. Studies of hydrothermal hydrogen production from biomass [1,2] revealed that the combination of a continuously stirred tank reactor and tubular reactor is particularly advantageous [3,4]. The reason is the positive influence of backmixing at the beginning of gas formation on chemical kinetics [1,4]. As the biomass naturally contains salts and the solubility of salts in supercritical water is comparably small, the question arises as to whether these salts remain in the continuously stirred tank reactor and/or are entrained heterogeneously. The latter would cause plugging of the downstream tubular reactor. In this respect, Na and K carbonates are of particular interest, as they are used as catalysts [5]. Moreover, carbonates are formed by hydrothermal biomass gasification when the organic anions like the other organic substances are converted into hydrogen and carbon dioxide as main products. This is why the behavior of NaHCO 3 and K 2 CO 3 in a continuously stirred tank reactor was studied by way of example. The concentrations of 0.5 % (g/g) corresponded to the usual concentrations applied when these compounds are used as catalysts [6].The study was based on the phase behavior of the alkali carbonates (see Figs. 1, 2). Fig. 1 shows the vapor pressure curves of the saturated solutions of Na 2 CO 3 [7] and K 2 CO 3 [8]. In the case of K 2 CO 3 , the critical curve of the water-salt system is continuous. In the case of Na 2 CO 3 , the curve is discontinuous [9]. The vapor pressure curve of the saturated Na 2 CO 3 solution ends at the point of intersection with the critical curve (see Fig. 1). The vapor pressure curve of K 2 CO 3 is continuous

show abstract

“…As regards the differences between biomasses and model compounds, it should be considered that biomass usually contains salts acting as catalysts [40]. Despite the long reaction time, catalytic effects seem to be important, leading to higher CGE for biomasses.…”

Section: Gas Composition and Equilibrium Yieldsmentioning

confidence: 99%

“…From a stoichiometric point of view, this means that the organic compounds in the liquid phase are more hydrogenated because the lower H 2 and CH 4 content means less hydrogen in the gas. Hydrogenated organic compounds should be less reactive concerning polymerization [40], which leads to less solid residue by depressed polymerization or improved splitting of the biomass. Further investigation is needed to clarify such reaction kinetics aspects.…”

Section: Observation Of the Alumina Surfacementioning

confidence: 99%

Supercritical Water Gasification of Biomass in a Ceramic Reactor: Long-Time Batch Experiments

et al. 2017

View full text Add to dashboard Cite

Supercritical water gasification (SCWG) is an emerging technology for the valorization of (wet) biomass into a valuable fuel gas composed of hydrogen and/or methane. The harsh temperature and pressure conditions involved in SCWG (T > 375 • C, p > 22 MPa) are definitely a challenge for the manufacturing of the reactors. Metal surfaces are indeed subject to corrosion under hydrothermal conditions, and expensive special alloys are needed to overcome such drawbacks. A ceramic reactor could be a potential solution to this issue. Finding a suitable material is, however, complex because the catalytic effect of the material can influence the gas yield and composition. In this work, a research reactor featuring an internal alumina inlay was utilized to conduct long-time (16 h) batch tests with real biomasses and model compounds. The same experiments were also conducted in batch reactors made of stainless steel and Inconel 625. The results show that the three devices have similar performance patterns in terms of gas production, although in the ceramic reactor higher yields of C 2+ hydrocarbons were obtained. The SEM observation of the reacted alumina surface revealed a good resistance of such material to supercritical conditions, even though some intergranular corrosion was observed.

show abstract

Hydrothermal Biomass Gasification – Effects of Salts, Backmixing and Their Interaction

Cited by 61 publications

References 22 publications

Supercritical Water Gasification of Biomass: A Literature and Technology Overview

Supercritical Water Gasification of Biomass: A Literature and Technology Overview

Measurement of Residence Time in Hot Compressed Water: 2. Salts in Continuously Stirred Tank Reactors

Supercritical Water Gasification of Biomass in a Ceramic Reactor: Long-Time Batch Experiments

Contact Info

Product

Resources

About