Torrefaction and gasification of biomass for polygeneration: Production of biochar and producer gas at low load conditions

In this paper, a matter of biomass torrefaction and gasification is closely looked at from different points of view during low load and low equivalence ratio regime, defined as lambda = 0.08. Considering gas production, the hot gas efficiency of conversion (30%) and its energy content (4.14 MJ m(-3)) were not quite satisfying, however, this matter of fact was compensated by an interesting yield of biochar. This material was generated in 0.387 and 0.314 rates for torrefaction and torrefaction + gasification processes, respectively, which, in both cases, represents an attractive, alternative approach to the functional energy storage. It was determined that a CO2 offset of 721 kg and 660 kg could be achieved per 1 tonne of woodchips for gasification of raw woodchips and a 2-stage process with torrefaction and gasification, respectively. The measured data from both technological complexes were compared with the computational model, applying equilibrium reactions for gas components determination. In addition, the question of tar compounds contained within the producer gas, is investigated through GC-MS analysis on both qualitative and quantitative basis.Web of Science814413

Use of Hydrothermal Carbonization and Cold Atmospheric Plasma for Surface Modification of Brewer’s Spent Grain and Activated Carbon

This paper presents results that show the effect of hydrothermal carbonization and subsequent cold plasma jet treatment with helium and argon on the structure and sorption properties of a material—spent brewery grain. Treatment of activated carbon, with a cold atmospheric plasma jet, was used comparatively. The effect of activation on the pore structure of the materials was carried out by the volumetric method at low pressure (N2, 77 K). The specific surface area as well as the total pore volume, average pore size, and pore size distribution were determined using different theoretical models. A high improvement in the sorption capacity parameter was obtained for hydrochars after cold atmospheric plasma jet treatment with an increase of 7.5 times (using He) and 11.6 times (using Ar) compared with hydrochars before cold atmospheric plasma jet treatment. The increase in specific surface area was five-fold (He) and fifteen-fold (Ar). For activated carbon, such a large change was not obtained after plasma activation. Regardless of the gas used, the increase in structural parameter values was 1.1–1.3

Use of Hydrothermal Carbonization and Cold Atmospheric Plasma for Surface Modification of Brewer’s Spent Grain and Activated Carbon

This paper presents results that show the effect of hydrothermal carbonization and subsequent cold plasma jet treatment with helium and argon on the structure and sorption properties of a material—spent brewery grain. Treatment of activated carbon, with a cold atmospheric plasma jet, was used comparatively. The effect of activation on the pore structure of the materials was carried out by the volumetric method at low pressure (N2, 77 K). The specific surface area as well as the total pore volume, average pore size, and pore size distribution were determined using different theoretical models. A high improvement in the sorption capacity parameter was obtained for hydrochars after cold atmospheric plasma jet treatment with an increase of 7.5 times (using He) and 11.6 times (using Ar) compared with hydrochars before cold atmospheric plasma jet treatment. The increase in specific surface area was five-fold (He) and fifteen-fold (Ar). For activated carbon, such a large change was not obtained after plasma activation. Regardless of the gas used, the increase in structural parameter values was 1.1–1.3

Metoda wyznaczania szybkości spadku wydajności stosu ogniw paliwowych typu PEMFC na podstawie przesunięcia charakterystyki napięciowo-prądowej

The article presents mathematical model designed to estimate the rate of performance decrease in fuel cell stack. The fuel cell stack performance decrease rate is determined on the basis of stack average voltage measurements. The proposed model is used to determine power curve as well as exploitation indicators of fuel cell stack with a nominal power of 50 kW after 14 000 hours of continuous operation. The model is also used to determine the average voltage drop for the eleven-year fuel cell stack with a nominal power of 1,2 kW. In both studies, the values of exploitation indicators as well as their differences in relation to nominal values are determined.Artykuł przedstawia model matematyczny przeznaczony do wyznaczenia szybkości spadku wydajności stosu ogniw paliwowych. Szybkość spadku wydajności stosu ogniw jest wyznaczana na podstawie wartości napięcia średniego stosu. Zaproponowany model wykorzystano do wyznaczenia krzywej mocy i wskaźników eksploatacyjnych stosu ogniw paliwowych o mocy nominalnej 50 kW po 14 000 h ciągłej pracy. Model wykorzystano także do wyznaczenia szybkości zmiany wartości napięcia średniego jedenastoletniego stosu ogniw paliwowych o mocy 1,2 kW. W obu badaniach wyznaczono wartości wskaźników eksploatacyjnych oraz ich różnice względem wielkości nominalnych

Torrefaction and gasification of biomass for polygeneration: Production of biochar and producer gas at low load conditions

In this paper, a matter of biomass torrefaction and gasification is closely looked at from different points of view during low load and low equivalence ratio regime, defined as λ=0.08. Considering gas production, the hot gas efficiency of conversion (30%) and its energy content (4.14 MJ m−3) were not quite satisfying, however, this matter of fact was compensated by an interesting yield of biochar. This material was generated in 0.387 and 0.314 rates for torrefaction and torrefaction + gasification processes, respectively, which, in both cases, represents an attractive, alternative approach to the functional energy storage. It was determined that a CO2 offset of 721 kg and 660 kg could be achieved per 1 tonne of woodchips for gasification of raw woodchips and a 2-stage process with torrefaction and gasification, respectively. The measured data from both technological complexes were compared with the computational model, applying equilibrium reactions for gas components determination. In addition, the question of tar compounds contained within the producer gas, is investigated through GC–MS analysis on both qualitative and quantitative basis

Hydrothermal Carbonization of Brewery’s Spent Grains for the Production of Solid Biofuels

To make a beer there are four essential ingredients needed: water, malt, hops, and yeast. After brewing process, the main wastes are spent grains. These are often used as additions to fodders in animal husbandry. This study presents preliminary results of an investigation aiming to determine the feasibility of an alternative use of spent grains as a potential source of solid fuel. This source of energy could make breweries partly sustainable in terms of their energy supply. Such an approach may be feasible especially in large scale industrial breweries. This preliminary study presents encouraging results, showing improvements in terms of the fuel properties of the spent grain after its valorization through hydrothermal carbonization. Moreover, qualitative GC-MS analysis also indicates potential feasibility of the liquid byproduct of the hydrothermal carbonization of spent grain for biogas production. Results of proximate, ultimate, and DTG analyses show that hydrothermal carbonization of spent grain could improve its fuel properties and make it an especially suitable feedstock for fast pyrolysis and gasification. Improvement of HHV is also an improvement in terms of combustion

Torrefaction as a Valorization Method Used Prior to the Gasification of Sewage Sludge

The gasification and torrefaction of sewage sludge have the potential to make the thermal utilization of sewage sludge fully sustainable, thus limiting the use of expensive fossil fuels in the process. This includes sustainability in terms of electricity consumption. Although a great deal of work has been performed so far regarding the gasification of sewage sludge and some investigations have been performed in the area of its torrefaction, there is still a gap in terms of the influence of the torrefaction of the sewage sludge on its subsequent gasification. This study presents the results from the torrefaction tests, performed on a pilot scale reactor, as well as two consecutive steam gasification tests, performed in an allothermal fixed bed gasifier, in order to determine if torrefaction can be deemed as a primary method of the reduction of tar content for the producer gas, from the aforementioned gasification process. A comparative analysis is performed based on the results obtained during both tests, with special emphasis on the concentrations of condensable compounds (tars). The obtained results show that the torrefaction of sewage sludge, performed prior to gasification, can indeed have a positive influence on the gas quality. This is beneficial especially in terms of the content of heavy tars with melting points above 40 °C

Novel Concept of an Installation for Sustainable Thermal Utilization of Sewage Sludge

This study proposes an innovative installation concept for the sustainable utilization of sewage sludge. The aim of the study is to prove that existing devices and technologies allow construction of such an installation by integration of a dryer, torrefaction reactor and gasifier with engine, thus maximizing recovery of the waste heat by the installation. This study also presents the results of drying tests, performed at a commercial scale paddle dryer as well as detailed analysis of the torrefaction process of dried sewage sludge. Both tests aim to identify potential problems that could occur during the operation. The scarce literature studies published so far on the torrefaction of sewage sludge presents results from batch reactors, thus giving very limited data of the composition of the torgas. This study aims to cover that gap by presenting results from the torrefaction of sewage sludge in a continuously working, laboratory scale, isothermal rotary reactor. The study confirmed the feasibility of a self-sustaining installation of thermal utilization of sewage sludge using low quality heat. Performed study pointed out the most favorable way to use limited amounts of high temperature heat. Plasma gasification of the torrefied sewage sludge has been identified that requires further studies