Search results for "hydrothermal liquefaction"
showing 7 items of 17 documents
Effect of transition metals and homogeneous hydrogen producers in the hydrothermal liquefaction of sewage sludge
2022
Hydrothermal liquefaction (HTL) of sewage sludge (SS) was performed in the presence of metallic Zn, Fe and Ni to investigate their effect on the performances of the process in terms of product yields and quality. Experiments were performed in subcritical water at 350 ◦C for 10 min using each metal individually and in the presence of homogenous hydrogen producers like formic acid (FA) and KOH. Interesting results were obtained with Zn that when used alone or in the presence of KOH, increased the cumulative biocrude (BC) yields and resulted in energy recoveries (ER) higher than 100% with respect to initial energy content of the biomass, thus indicating that HTL of SS is globally endothermic. …
Hydrothermal liquefaction of waste biomass in stirred reactors: One step forward to the integral valorization of municipal sludge
2020
Abstract Hydrothermal liquefaction (HTL) of municipal sludge (MS) was performed at 350 °C for 30 min (subcritical water) and at 400 °C for 0 min (supercritical water) at fixed kinetic severity (LogR0 = 8.9) in static and stirred batch reactors to study the effect of the flow regime on the energy recovery (ER) of the process and on the quality of the products. With adopted experimental procedures it was possible to reduce to less than 10% the yield of lost organic compounds, termed volatiles (VT), and to collect and quantify a liquid hydrocarbon fraction (HC) separated from the biocrude (BC). The highest value of the HC yield, 25% w/w, was obtained in supercritical conditions. The C content …
Hydrothermal liquefaction of sewage sludge: towards the effects of transition metals in the presence of homogeneous hydrogen producers
2022
Waste carbonaceous matrices, such as sewage sludge (SS) seem to have a great potential, because they are namely costless matrices compared to the microalgae and hydrothermal liquefaction (HTL) can be considered an interesting route to dispose and valorize them [1-5]. However, SS are characterized by high amount of non-biogenic fractions, such as plastics, salts and metals. In particular SS contains a high amount of inorganics [5], such as Al, Ba, Ca, Cr, Cu, Fe, Ni, K, Mg, Mn, Na, P, S, Ti, Zn, Si which are distributed in the products at the end of the reaction. The presence of heavy metals represent a big challenge for the implementation of HTL on the industrial scale as they can affect pr…
Hydrothermal liquefaction of municipal sludge in sub- and super- critical water
2020
Hydrothermal liquefaction of municipal sludge was conducted to investigate the effects of sub- and supercritical water and of the fluid dynamic regime on the quality of the products. Preliminary experimental runs were performed at two different temperatures (350°C and 400°C) changing reaction time in order to work at fixed kinetic severity of the process. An improvement of the C content in the solid residues and of the ratio H/C of the biocrude was obtained when a stirred reactor was used both in sub- and supercritical water. A hydrocarbon fraction was separated from biocrude whose maximum yield of 25% w/w was achieved in supercritical conditions. Results showed that the cumulative energy r…
Hydrothermal liquefaction of wet waste biomass: a practical assessment to achieve an integral valorization of municipal sludge
2020
Hydrothermal liquefaction of municipal sludge was conducted to perform a practical assessment to achieve an integral valorization of this wet waste biomass. Experiments were done to investigate the effects of sub- and supercritical water and of the fluid dynamic regime on the energy recovery of the process and on the quality of the products. Experimental runs were performed at two different temperatures (350°C and 400°C) changing reaction time in order to work at the same kinetic severity of the process (LogR0=8.9, calculated as in ref. [3]). An improvement of the C % in the solid residues and of the ration of H/C of the biocrude was obtained when stirred reactor was used both in sub- and s…
Hydrothermal co-liquefaction of sewage sludge and formic acid
2019
The biocrude produced by non-catalytic hydrothermal liquefaction (HTL) has a too high heteroatom content to be used directly as a fuel [1-3]. Several studies found that different H2 initial pressures during HTL experiments were ineffective in improving the biocrude yield [4-6], nevertheless it was observed that higher initial pressures of H2 brought an improvement of the concentration of light compounds in the biocrude, decreasing the average molecular weight of biocrude oil. To date H2 is mainly generated from fossil sources and realization of a possible hydrogen economy from alternative sources presents many challenges. The use of a liquid hydrogen storage media could represent for the HT…
Catalytic hydrothermal liquefaction of municipal sludge in subcritical water
2021
In the last decades, the dwindling of the fossil sources of energy coupled with the growth of energy demand and of waste production prompted the research in developing novel industrial technologies for renewable energy production and waste valorization. Hydrothermal liquefaction (HTL) is a good alternative to transform wet biomasses as microalgae, macroalgae, agricultural residues, food waste, and municipal sludge (MS) into value-added products with high efficiency and decreasing the amounts that has to be disposed of. HTL takes place in an aqueous environment, without the energy cost of drying the biomass, at 300-400°C and pressure of 10-40 MPa [1,2]. At these operative conditions, an inte…