Co‐gasification of woody biomass and sewage sludge in a fixed‐bed downdraft gasifier

Abstract

Experimental and numerical studies of cogasification of woody biomass and sewage sludge have been carried out. The gasification experiments were performed in a fixed-bed downdraft gasifier and the experimental results show that 20 wt % dried sewage sludge in the feedstock was effectively gasified to generate producer gas comprising over 30 vol % of syngas with an average lower heating value of 4.5 MJ/Nm 3 . Further increasing sewage sludge content to 33 wt % leads to the blockage of gasifier, which is resulted from the formation of agglomerated ash. The numerical models were then developed to simulate the reactions taking place in four different zones of the gasifier (i.e., drying, pyrolysis, combustion, and reduction zones) and to predict the producer gas composition and cold gas efficiency. The deviation between the numerical and experimental results obtained was lower than 10%.a Typical sewage sludge examples were collected from Ulu Padan wastewater treatment plant, Singapore.

Evaluation of selected sewage sludge gasification technological parameters

“…Where: G fuel -fuel stream (kg/h),V conv -stream of gasification agent (air) (kg/h) Description of sub processes areas of sludge air gasification in countercurrent pipeline gas generator shown in Fig.1 was prepared in accordance with [15,16] . asi i ati n pr ess nsists di erent sub pr esses where spe i i hemi al rea ti ns urs [ ] Rem ving uel humidity starts at the beginning Then in primary and se ndary rea ti ns gases like: methane, steam, arb n m n xide and als tars are rmed The last pr du t is ra ked in the ra king area in a rdan e with p st pr essing tars [ ] C n entrati ns syngas mp unds rmed in gasi i ati n were sh wn in Fig Fig.…”

Numerical Study on the Efficiency of Biomass and Municipal Waste Fixed-Bed Co-Gasification

“…The process is considered to be steady. The height of reaction zone is 0.25 m, internal diameter of reactor is 0.2 m (values are given corresponding to work [22]). Fuel flow rate is 10 kg/h, gasification agent flow rate (air heated to 30°С) is approximately 3-4 nm 3 /h.…”

“…The co-gasification of sludge with other fuels makes it possible to increase moisture of the processed sludge. For example, in [21,22] the authors consider gasification of woody biomass and sewage sludge with a moisture of 20%. In [21], the authors demonstrate that with a switch from sludge to the mixture with a wood pellet content of 30%, chemical efficiency increases from 20-30% to 30-50%.…”

“…Equilibrium thermodynamic models are used most often to estimate transformations of organics [28,32] and mineral part [33]. In [22,34], the authors proposed nonstationary zonal and spatially one-dimensional models and used them to study process conditions in fixed-bed gasifiers. One-dimensional model of rotary kiln oxypyrolysis reactor was used in [35] to study effects of staged air supply.…”

Clean Poultry Energy System Design Based on Biomass Gasification Technology: Thermodynamic and Economic Analysis

“…Previous work tested the performance of a 30 kW micro-turbine using gasification syngas products shows biomass gasification is an attractive technology for high-efficiency biomass conversion with lower NOx emissions [17]. Moreover, gasification of wood, rice husk, and sewage sludge have been carried out in fixed bed gasifier both experimentally and numerically to demonstrate its fuel flexibility and low tar emission [18,19]. However, the gasification technology application on poultry treatment is a novel idea and its efficiency and economic characters are absent.…”