Qizhuang Yu

Use of amino phase adsorbent for biomass tar sampling and separation

Abstract To reduce sampling and sample separation time, a highly efficient method based on solid-phase adsorption (s.p.a.) on amino phase was designed. This method is suitable for intermittent trapping of tar compounds ranging from benzene to coronene prevailing in product gases from thermal decomposition of biomass at 700–1000°C. Using eluotropic elution, adsorbates are selectively desorbed into aromatic and phenolic fractions and then determined by gas chromatography with flame-ionization detection. The sampling step allows collection of one to three samples per minute, compared with one or two samples per hour using conventional cold trapping (c.t.) techniques, and correspondingly more information is obtained. As a result of this improvement, the progress of pyrolysis and gasification processes in terms of molecular distribution is easily followed. Furthermore, the method can be readily applied to establish cold-trap and filter performance and for industrial emission control. The usefulness of the method is compared with the cold-trapping techniques and the novel solid-phase micro extraction (s.p.m.e.) technique, not tested earlier for tar sampling.

Tar evolution profiles obtained from gasification of biomass and coal

The tar content of the product gases from gasification of biomass is one of the major factors affecting the subsequent process stages. In this work, evolution profiles of the main tar constituents, ...

Promoted reactivity of char in co-gasification of biomass and coal: synergies in the thermochemical process

An experimental study on co-gasification of woody biomass and coal in oxygen-containing atmosphere was carried out in a pressurized fluidized bed reactor. The wood used was birch from a Swedish paper mill, while the coals used were Daw Mill coal of UK origin and a bituminous coal from Poland. The operation temperatures were 900 and 700°C, and the pressure was 0.4 MPa. The ratio of coal to wood was varied in the investigation. The study was focused on possible synergetic effects in the thermochemical treatment of the fuels. The char formed was examined. The tar produced in the process was analyzed. The nitrogen compounds emitted were detected. A noticeable phenomenon was that the mixtures of the fuels and their char formed in situ demonstrated an unexpected high reaction rate of gasification under the studied conditions. The yield of char diminished and consequently the production of gas increased. Further, both the formations of tar and nitrogen compounds also seemed affected synergetically in the co-gasification experiments of the fuels. The yields of tar and of ammonia were lower than expected.

Characteristics of evolution of tar from wood pyrolysis in a fixed-bed reactor

The thermally induced interrelation between total tar, chemical distribution of principal tar constituents and the three C2 compounds (ethane, ethene, ethyne) obtained from wood pyrolysis at atmospheric pressure in a continuous bench-scale fixed bed reactor was investigated. Total tar and certain tar constituents exhibit a close correlation with the C2 compounds over the temperature range 700–900°C. Some characteristic compound ratios, namely indene to naphthalene (IN), phenols to aromatics (PA) and saturated to unsaturated C2 compounds, were identified. These reactor-specific correlations have obvious potential application for on-line continuous monitoring of non-gaseous products that so far are determined off-line. The analysis methods used were designed for quantification of aromatics, phenols, N-organics, asphaltenes and preasphaltenes.

Reactivity of char from pyrolysis of birch wood

Abstract Pyrolysis of biomass from birch was carried out both in a free-fall tubular reactor and a thermobalance. The char obtained was further gasified with carbon dioxide and steam in the thermobalance. It was observed that the reaction rates of the char with the reagents were strongly affected by the time-temperature history of the char formation. A rapid heating rate of the raw material in free-fall reactor gives a char which possesses higher reactivity in reaction both with carbon dioxide and steam compared with the char formed under slow heating rate in the thermobalance. The treatment condition and environment of the char precursor during devolatilization are the most important factors affecting the reactivity of the char in gasification with the used reagents. The kinetic study focused on whether a surrounding pyrolysis gas atmosphere exerts negative effects on the reactivity of the formed char.

Temperature impact on the formation of tar from biomass pyrolysis in a free-fall reactor

Abstract Tar evolution was measured as a function of temperature during wood pyrolysis in a free-fall reactor operated at near atmospheric pressure. The yields of total tar and phenolic compounds were markedly reduced whereas aromatic compounds increased with increasing temperature between 700 and 900°C. The chemical distribution of principal tar constituents at selected time points was obtained by intermittent sampling using a new method based on solid-phase adsorption (S.P.A.). Using cluotropic solvent elution, adsorbates were subsequently desorbed into aromatic and phenolic fractions and then determined by gas chromatography with flame-ionization detection (GC-FID).

Pyrolysis/Gasification of Biomass in Presence of Dolomite in a Pressurized Fluidized Bed

Pyrolysis/gasification of biomass in presence of dolomite was studied in a pressurized fluidized bed reactor. The dolomite used was from the Swedish quarry, Glanshammar. The dolomite was calcined and milled to powder. The wood particles were mixed with the dolomite and pyrolyzed at 650°C under a pressure of 0.5 MPa.

Co-Gasification of Coal/Biomass Blends in a Pressurized Fluidized-Bed Gasifier: The Advantageous Synergies in the Process

An experimental study on co-gasification of coal and biomass blends in an oxygen-containing atmosphere has been carried out in a pressurized fluidized-bed gasifier. Several different biomass materials including wood and energy crops were used in the study, whereas two coals ranked of bituminite from Poland and UK were used in the investigation. The gasifier used was a Laboratory Development Unit (LDU) with an inner diameter of 144 mm. The operation temperature was 900 °C, and the pressure was 0.4 MPa. The research was part of the European Commission’s APAS and JOULE III clean coal technology programs.The study was focused on possible synergistic effects in the thermochemical treatment of the fuel blends. The char formed was examined. The tar produced in the process was analyzed. The environmentally concerned nitrogen compounds emitted from the process were detected. An unexpected result was that the blends of the fuels and their char formed in situ exhibited higher gasification reaction rate under the studied conditions. The yield of char diminished and consequently the gas production increased. Furthermore, both the formation of tar and nitrogen compounds seemed also affected synergistically in co-gasification process of the fuel blends. The yields of tar and ammonia were lower than expected.Copyright