Wet Chemical Method for Determining Levels of Ammonia in Syngas from a Biomass Gasifier

Permanent gas species, tar compounds, sulfur compounds, and ammonia produced from a bench-scale (∼1 kg/h) fluidized-bed biomass gasifier were analyzed. Two commercial Ni-based catalysts and one commercial ZnO sorbent were evaluated under varied conditions by quantifying contaminants from the reactor inlet and outlet with specific sampling and analysis methods. The Ni catalysts targeted tar destruction and ammonia reduction, and the ZnO sorbent was selected for sulfur compound removal. Tar components were identified by gas chromatography-mass spectrometry (GC-MS) and quantified by GC-flame ionization detector (FID). A total of 13 compounds (gC 6 ) were identified in raw product gas, principally "lighter tar" species with an average concentration of 15.5 g m -3 (dry gas basis). For tar species that were not detected by GC, a gravimetric method was used to quantify the portion of "heavier tar" (5.3 g m -3 dry gas basis). These data are raw gas tar concentrations for the gasifier-operating conditions used for the remainder of the tests. The performance of two commercial Ni catalysts were evaluated by comparing the concentrations of both "lighter tar" and "heavier tar" after the raw gas passed through the tarreforming reactor. Concentrations of hydrogen sulfide (H 2 S), carbonyl sulfide (COS), and thiophene (C 4 H 4 S) in the raw, dry, product gas averaged 93, 1.7, and 2.2 ppmv, respectively. C 4 H 4 S and two additional sulfur compounds, benzothiophene and one unidentified compound (UN1), were found in the tar-trapping solution. Removal of sulfur compounds using the ZnO sorbent at varied temperatures and gas hourly space velocities (GHSVs) was investigated. The primary sulfur component, H 2 S, was reduced to less than 1 ppmv; COS was not reduced significantly; and C 4 H 4 S concentrations were not affected at all. The average NO and ammonia concentrations were determined to be 8.2 and 2662 ppmv in the dry gas, respectively. Both were successfully converted to permanent gas species by Ni catalysts.

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“…Thereafter, only a single impinger was used for NH 3 collection. Similar capture efficiency has been reported elsewhere …”

Section: Methodssupporting

confidence: 90%

Contaminant Estimates and Removal in Product Gas from Biomass Steam Gasification

et al. 2010

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“…A very interesting behavior can be deduced from this comparison: the ammonia concentration obtained here for dried sewage sludge is lower than that reported by Zhou and co-workers for the leucaena gasification at 850 °C. It was expected that larger nitrogen content in the feedstock could give a larger NH 3 production. , Nevertheless, the reported results for leucaena and sewage sludge samples are in contradiction to this prediction. Besides, the N 2 production measured in the present work is higher than that obtained from leucaena gasification in similar conditions.…”

Section: Resultsmentioning

confidence: 90%

“…It is important to carefully analyze the evolution of all of the main nitrogen-containing products obtained from gasification, on a comprehensive basis, to check if a given decrease in the amount of one of them could produce an increase of the above-mentioned contaminant compounds. Several researchers have studied the formation of nitrogen-containing species during biomass (and coal) gasification − with only a few about the production of nitrogen-containing products from the gasification of sewage sludge. , However, little information is available regarding the distribution and interactions of the nitrogen-containing compounds, taking into account in the same study the solid, liquid, and gas phases. Zhou and co-workers investigated the effects of operational parameters and nitrogen content of six biomass feedstocks on the partitioning of fuel-bound nitrogen among nitrogenous gas species (N 2 , NH 3 , and HCN) and the nitrogen remained in char.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study Examining the Evolution of Nitrogen Compounds during the Gasification of Dried Sewage Sludge

et al. 2009

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Gasification of dried sewage sludge, which contains a high percentage of nitrogen, was experimentally studied to determine the effects of some operational parameters, such as freeboard temperature and equivalence ratio, on the partitioning of the fuel nitrogen among nitrogenous species. Experiments were performed using a bench-scale fluidized-bed gasifier and according to a well-specified procedure implemented to recover and quantify the nitrogen compounds. A mixture of argon and oxygen in similar proportions to air was used as a gasification agent in order to correctly quantify the N2 produced in the gasification process in an experimental way. Important findings of this research include the following: applying the analytical procedure developed in this work, a reasonably good inventory of nitrogen in the gasification products was obtained (mass balance closures near to 100%); most of the nitrogen goes to form gaseous products, N2 being the main gaseous nitrogen-containing product obtained; concentrations of N2, NH3, and N-tar in the producer gas strongly depend on the freeboard temperature, an increase of which causes an important decrease of both NH3 and N-tar contents and a substantial increase of the N2 amount.

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“…The NH3 concentration in syngas was in the range of 0.06 -0.4 % (Burch & Southward, 1999;Norton & Brown, 2005). Approximately 60 -80 wt.% organic nitrogen is converted to NH3 during gasification (Wang et al, 1999).…”

Section: Ammoniamentioning

confidence: 99%

Towards practical application of gasification: a critical review from syngas and biochar perspectives

You

Tsang

et al. 2018

Critical Reviews in Environmental Science and Technology

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Syngas and biochar production are mainly influenced by temperature, feedstock properties, gasifying agent, pressure, and the mass ratio between gasifying agent and feedstock with temperature being the most significant factor. Increasing temperature generally promotes syngas production while suppressing biochar production. The selection of gasifiers (fixed bed, fluidized bed, and entrained flow) is highly dependent on scale requirement (e.g., volume of feedstock and energy demand), feedstock characteristics (e.g., moisture and ash content), and the quality of syngas and biochar. Updraft fixed bed gasifiers are suitable for the feedstocks with a moisture content up to 50 wt.%. High ash feedstocks such as Indian coal, dried sewage sludge, and municipal solid waste that are not suitable for fixed bed gasifiers, have been successfully gasified in bubbling fluidized bed reactors. Woody biomass is not suitable for entrained flow gasifiers unless specialized feeding methods are employed such as wood torrefaction and grinding followed by the existing feeding methods for pulverized coals, biomass-oil biochar slurry preparation followed by pumping, wood or torrefied wood slurry preparation followed by pumping, etc. Syngas and biochar can potentially be contaminated by NH3, H2S, and tar, which can be removed using catalysts (e.g., Ni-based), metal oxides-based sorbents, and thermal and catalytic cracking methods. Existing syngas and biochar upgrading methods suffered from various problems such as economic infeasibility, limited productivity, and fouling, and future syngas and biochar upgrading methods should be aimed to have the features of reliability, security, affordability, and sustainability, towards the practical, largescale production of syngas-and biochar-based products. One potential solution is to develop integrated systems by combining biochar upgrading and application with syngas upgrading, which warrants an integrated perspective based on both life cycle assessment and economic analysis.

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Wet Chemical Method for Determining Levels of Ammonia in Syngas from a Biomass Gasifier

Cited by 12 publications

References 10 publications

Contaminant Estimates and Removal in Product Gas from Biomass Steam Gasification

Contaminant Estimates and Removal in Product Gas from Biomass Steam Gasification

Experimental Study Examining the Evolution of Nitrogen Compounds during the Gasification of Dried Sewage Sludge

Towards practical application of gasification: a critical review from syngas and biochar perspectives

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