Quality Of Producer Gas Research Articles

The Effect of Potassium Hydroxide (KOH) Concentration, Temperature and Resistance Time on Quality of Producer Gas

The Effect of Potassium Hydroxide (KOH) Concentration, Temperature and Resistance Time on Quality of Producer Gas

Development of cooling and cleaning systems for enhanced gas quality for 3.7 kW gasifier-engine integrated system

Energy from biomass based gasifier-engine integrated systems are becoming more popular for power generation applications in rural and urban driven societies. The quality of producer gas from the down draft gasifiers plays a significant role in power generation aspects. During gasification, tar is produced and its magnitude depends on the type of gasification process and biomass feedstock used which can vary from biomass to municipal solid waste (MSW) available. The pollutants generated from gasification include particulate matter, tars, and char and acid gases. A major challenge for commercializing the gasification process is to reduce tar. In order to address these tar related problems a cleaning and cooling system has been developed in house that facilitates tar removal to acceptable levels tolerated by the internal combustion (IC) engine and meets emission standards as well. The main objective of the present work is to reduce tar level and develop control strategies for improving the performance and emission of diesel engines. Results showed that the brake thermal efficiency of the dual fuel engine used was increased by 2-4% and tar was reduced from 325 mg/Nm3 in the gasifier to 60-50 mg/Nm3 entering the engine. In addition, the emission levels such as hydrocarbon, carbon monoxide were reduced comparatively with developed cooling-cleaning system provided in the conventional gasifier-engine system. The biomass consumption rate was 40kg/h. Air and gas flow rates were measured to be 18.8 m3/h and 20.12 kg/h respectively. The temperature of the gas after developed cooling and cleaning system was found to be 34 °C.Keywords: Dual fuel engine, cooling-cleaning system, Rice bran oil methyl ester, tar, performance, emissions

The influence of different parameters on biomass gasification in circulating fluidized bed gasifiers

The mechanism of biomass gasification has been studied for decades. However, for circulating fluidized bed (CFB) gasifiers, the impacts of different parameters on the gas quality and gasifiers performance have still not been fully investigated. In this paper, different CFB gasifiers have been analyzed by multivariate analysis statistical tools to identify the hidden interrelation between operating parameters and product gas quality, the most influencing input parameters and the optimum points for operation. The results show that equivalence ratio (ER), bed material, temperature, particle size and carbon content of the biomass are the input parameters influencing the output of the gasifier the most. Investigating among the input parameters with opposite impact on product gas quality, cases with optimal gas quality can result in high tar yield and low carbon conversion while low tar yield and high carbon conversion can result in product gas with low quality. However using Olivine as the bed material and setting ER value around 0.3, steam to biomass ratio to 0.7 and using biomass with 3mm particle size and 9wt% moisture content can result in optimal product gas with low tar yield.

Performance and chemical composition of waste palm cooking oil as scrubbing medium for tar removal from biomass producer gas

Producer gas, a product of biomass gasification contains not only combustible gases but also tar which is an unwanted and detrimental substance to downstream applications. This paper presents a study on tar removal using laboratory prepared waste palm cooking oil (LWPCO), restaurant collected waste palm cooking oil (CWPCO), diesel oil and water as scrubbing mediums. The experiment succeeded in removing class 4 tar using diesel oil and CWPCO as scrubbing mediums. The unsaturated hydrocarbons (oleic and linoleic acids) present in the CWPCO resulted in the highest tar removal efficiency of 86% (excluding benzene). Besides utilizing unused residual material, application of CWPCO for tar removal can reduce operational cost. Combination of CWPCO with activated carbon provides a high quality producer gas with tar content of 0.022 gmn−3 and tar removal efficiency of 98%, which can be safely used in internal combustion engines (ICE).

Bottom Ash Characterization and its Catalytic Potential in Biomass Gasification

Biomass gasification has received much attention in recent years due to efforts in finding alternatives to fossil fuels. However the inefficiencies of the process and also the by-product produced during the gasification makes this process unsuitable for commercial applications. Thus, catalyst is used to improve the product gas quality and to reduce the tar formation. Commercial catalyst such as dolomite, nickel and olivine are widely used in biomass steam gasification, but it has limitation such as short active lifetime and expensive. The potential of the bottom ash as the substitute catalyst in biomass steam gasification is discussed, thus the characterization of the bottom ash is performed to determine the surface morphology, chemical compound, pore size, pore volume, surface area and bulk density of the bottom ash. The result shows that the bottom ash contains elements such as SiO2, Fe2O3, Al2O3, CaO and MgO which have been used as the catalyst in biomass steam gasification. The pore volume of the bottom ash is 3.01nm which falls into mesoporous category and the pore volume is 0.04 cm3/g with surface area of 58.01 m2/g and bulk density of 2.53 g/cm.

Tar Decomposition at low Temperatures within staged Gasification Reactors-first Approach towards Mechanisms and Background

AbstractThe reduction or decomposition of tar in biomass derived fuel gases is one of the biggest challenges in its utilization for power generation. The floating-fixed-bed technology demonstrated a reduction of tars within the floating-bed reduction reactor (FBRR) of >99% reaching less than 50mg/m3 of tar even before cleaning the product gas. In order to gain more details about the mechanisms being involved in tar release and tar decomposition and to find an explanation for the good product gas quality of this gasification system, different studies conducted directly at a gasification pilot plant and studies concerning tar reduction mechanisms are summarized and compared in this work.

Optimization of Combustion Behavior and Producer Gas Quality from Reclaimed Landfill Through Highly Densify RDF-Gasification

The growth in population, technology, and economy are resulting in the rapid increase of Municipal Solid Waste (MSW), which has a significant direct impact to the environment. MSW is generally disposed by landfill, which requires a lot of land space. Moreover, it is considered as a non-sustainable solution, by which only decomposable material is decayed where plastic and paper still remain inside. In order to provide the land space for recently large amount of waste, the old MSW need to be reclaimed and used as alternative fuel for sustainable disposal and converted into green and clean energy through gasification process. However, using an as-receive reclaimed product faces the challenges of combustion behaviour because it is non-homogeneous and loosens. This study discusses the improvement of the characteristics of the as-received reclaimed product by converting it into high density Refuse Derived Fuel (RDF). The surrogate reclaimed landfill RDF used has been made of waste plastic (polyethylene) and paper with a ratio of 75:25%-wt. After densification by extrusion, RDF-5 has a density higher than 600kg/m3. The experiment was conducted in a laboratory scale downdraft gasifier by feeding surrogate RDF 10kg/hr with the air flow rate 12, 15 and 18 Nm3/hr, respectively. Charcoal was added as an additive at the same weight of RDF in order to increase the fraction of fixed carbon and improve concentration of producer gas. The influences of the additive on the producer gas concentration and combustion characteristics were investigated. Results showed highest CO% and LHV were affected by air flow rate of 12 Nm3/hr at 22.02%-vol and 4.39MJ/Nm3, respectively, whereas highest H2% was obtained with air flow rate of 15 Nm3/hr. It was found that the densification of the reclaimed landfill and the mixing of the additive optimized the combustion behavior in terms of temperature distribution along the gasifier height and improved the producer gas quality.

Pilot scale autothermal gasification of coconut shell with CO2-O2 mixture

This paper explored the feasibility and benefit of CO2 utilization as gasifying agent in the autothermal gasification process. The effects of CO2 injection on reaction temperature and producer gas composition were examined in a pilot scale downdraft gasifier by varying the CO2/C ratio from 0.6 to 1.6. O2 was injected at an equivalence ratio of approximately 0.33–0.38 for supplying heat through partial combustion. The results were also compared with those of air gasification. In general, the increase in CO2 injection resulted in the shift of combustion zone to the downstream of the gasifier. However, compared with that of air gasification, the long and distributed high temperature zones were obtained in CO2-O2 gasification with a CO2/C ratio of 0.6–1.2. The progress of the expected CO2 to CO conversion can be implied from the relatively insignificant decrease in CO fraction as the CO2/C ratio increased. The producer gas heating value of CO2-O2 gasification was consistently higher than that of air gasification. These results show the potential of CO2-O2 gasification for producing high quality producer gas in an efficient manner, and the necessity for more work to deeply imply the observation.

Chemical Process Modelling of Underground Coal Gasification and Evaluation of Produced Gas Quality for End Use

The chemical process at the heart of Underground Coal Gasification (UCG) is the engineered injection of a blend of gasification (normally O2, air, H2O) agents into the coal resource. Established surface gasifier chemical modelling principles are adapted for modelling UCG processes. Model configurations developed in Aspen Plus are used to simulate the Linked Vertical Wells and the Controlled Retractable Injection Point gasifier layouts. Sensitivity analyses were conducted to investigate the effect of operational parameters and performance indicators. Model outputs were validated using reported UCG trial results. The gasification designs developed could form the basis for developing an integrated UCG model.

ANALYTICAL AND EXPERIMENTAL STUDIES ON A 50 kWth DOWNDRAFT GASIFIER WITH BIOMASS BLENDS AVAILABLE IN THE HILLY REGIONS OF SOUTH INDIA

Biomass Gasification has emerged as the most promising technology for the decentralized heat and power applications. The prediction of the performance of biomass blends in gasifiers is an important area of study for the implementation of this technology in various applications, relevant to remote villages. This paper presents the theoretical and experimental studies conducted on a 50 kWth downdraft biomass gasifier with various combinations of the biomass materials such as wood, coconut shell, rubber seed kernel and coir pith, which are abundantly available in the villages of South India. Two zone kinetic equilibrium model is used for the theoretical simulation. The influence of equivalence ratio and composition of feedstock blends on the quality of producer gas and the conversion efficiency of gasifier were studied, and reported. The experimental and theoretical studies show that the effective utilization of biomass materials as blends can meet the rural energy demand.

Cogasification of blended coal‐biomass in an air/steam BFB gasifier: Experimental investigation and model validation

A series of cogasification experiments were performed at a 100 kW bubbling fluidized bed (BFB) gasifier to gasify the blended pellets made from two types of coals and woody biomass, with biomass‐to‐fuel mass ratios of 0–30%. In the cogasification, a mixture of air and steam was fed from the BFB gasifier bottom as gasification agent and the blended biomass‐coal pellets were fed into the bed layer. Impacts of biomass mass fraction in the binary pellets and gasification operation temperature on producer gas composition were experimentally investigated. The experimental results have been used to validate a mathematical model developed in this study. From both experimental observation and model prediction, it was found that adding biomass into coal has overall negative impact on producer gas quality in terms of combustible substance contents, and the extents of the blending effect were different among fuel types which have different properties. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1639–1647, 2015

Parametric analysis of a circulating fluidized bed biomass gasifier for hydrogen production

Biomass is considered a potential energy source which can be efficiently converted to useful gaseous products via a gasification process. Circulating fluidized bed (CFB) gasifiers have attracted significant attention due to their high reaction rates and thermal efficiency. This study aims to investigate the CFB biomass gasification process to generate H2-rich synthesis gas. A process simulator is used to analyze the gasifier performance by assuming that the gasification is fast and reach equilibrium. Parametric analysis of the CFB gasifier shows that steam gasification generates the synthesis gas attained the highest H2 content (50–65 vol.%) and the highest product gas quality (higher heating value, HHV = 10–13 MJ/Nm3) at operating temperatures approximately 650–700 °C. High-temperature steam cannot provide enough energy for the gasifier, reducing the gross cold gas efficiency of this process to only 16%. The biomass air-steam gasification process is investigated while avoiding high energy consumption, but less H2 is produced under these conditions.

Simulation of Biomass Gasification and Application in Pilot Plant

AbstractIn the present work, a revised equilibrium model (gas–solid) was built. The temperature approach to equilibrium for the methane cracking reaction was specified to improve the prediction accuracy. The model was applied and validated in pilot scale experiments using a 150 kg h−1 two‐stage downdraft gasifier and a gasifier from the Energy Research Centre of the Netherlands (ECN). The type of gasification agent is a dominant factor that determines product gas composition, quality, and end‐use. A theoretical analysis of the effect of gasifying agent on product gas quality and process efficiency was executed based on the model calculation. The optimal operation conditions were established for the three (air, steam, oxygen–steam) gasification processes. For air gasification, an optimal value of equivalence ratio (ER) of 0.31 corresponds to the maximum gasification efficiency. The optimal range of steam/carbon ratio (SR) is between 0.7 and 0.8 for the equilibrium of the water–gas shift and steam reforming reactions. For autothermal oxygen–steam gasification, the H2 concentration reaches the highest value for SR=1.0.

Enhanced hydrogen production using steam plasma processing of biomass: Experimental apparatus and procedure

A two-stage high-temperature steam plasma system is analyzed experimentally for the production of high-hydrogen content product gas obtained from biomass. The first stage uses contact glow discharge electrolysis (CGDE) to convert an electrolyte into a steam, mainly composed of steam and a small fraction of hydrogen and carbon dioxide. The second stage uses the output stream from the first stage as the gasifying agent to produce a steam plasma to gasify the biomass. Measurements show molar fractions of hydrogen in the product gases in excess of 50% for six different types of biomass tested. The experimental results are also used to validate a thermodynamic model of the combined process. The model is used to analyze the effect of feedstock mass flow rate on product gas quality.

A TECHNICAL REVIEW OF PRODUCER GAS AS AN ALTERNATIVE FUEL FOR INTERNAL COMBUSTION ENGINE

This paper describes the current state of available gasification technology for utilizing producer gas for I.C engine application & different ways to optimize the performance. Producer gas is promising alternative fuel to meet energy demand in many countries which is defined as gas generation from solid waste through thermo chemical conversion route (also termed as gasification) can be used for fuelling a compression ignition (CI) engine in duel fuel mode or a spark ignition (SI) engine in the gas alone mode. This technology is also environmentally benign and holds large promise for the future. This paper summarizes the work conducted using biomass derived producer gas in reciprocating internal combustion engines. Survey in the field of producer gas based engines reveals modest research work have been carried out since the inception of biomass/ charcoal gasification systems. Producer gas contains a large fraction of inert (> 50%) and with laminar burning velocity being high (due to presence of H2), smooth operation at higher Compression ratio does not seem impossible. These aspects are very vital in establishing the fact that close to comparable power (with a lesser extent of de-rating 15-20%) with producer gas by operating in engine at higher compression ratio. This could be attributed to two reasons, namely non- availability of standard gasification system that could generate consistent quality producer gas and the other relating to misconceptions about producer gas (related to compression ratio limitation due to knock tendency and de-rating). The knock tendency can be expected to be better on account of large fraction of inert gas as compared to natural gas. However, there has not been any research on octane rating test conducted on producer gas fuel and moreover it is not clear if any established test procedure exists for producer gas like the methane number test for natural gas and biogas. De-rating could be due to reduction in the mixture energy density and the product-toreactant mole ratio. If one were to summarize earlier studies, it becomes evident that no systematic investigation has been attempted so far in identifying if limitation of knock exists with producer gas operation at compression ratio comparable with the diesel engine operation.

Fluidized Bed Gasification of Palm Empty Fruit Bunch Using Various Bed Materials

Gasification of palm empty fruit bunch was investigated in a pilot scale air-blown fluidized bed. Silica sand and calcined dolomite were used as the bed materials. The gasification performance was assessed at the bed temperature range of 650 to 850°C. Maximum heating value of 4.48 and 5.33 MJ/Nm3, gas yield of 1.62 and 1.68 Nm3 gas/kg, carbon conversion of 82.5 and 83%, and cold gas efficiency of 50.1 and 58.9% were, respectively, achieved for sand and dolomite at 850°C. Although the quality of producer gas improved at high temperatures, bed agglomeration, however, was observed as the major issue above 800°C for silica sand.

Fuel gas production from peanut shell waste using a modular downdraft gasifier with the thermal integrated unit

Downdraft gasifier is a preferable method for carrying out biomass gasification because the produced gas has viable heating value with low tar content and can be cleaned to high purity, suitable for IC engine usage and chemical processing applications. This is due to throat section design in the downdraft gasifier which helps reducing the tar content through intense heat. In this study, a modular concept is applied to bring the gasification process to the place where feedstock is abundant which may yield better economic returns through additional utilization of various wastes and reduced transportation cost. The main objective is to study the potential of peanut shell waste conversion using a modular fixed bed gasifier coupled with thermal integration unit. The thermal integration unit was applied to return hot fuel gas exiting the gasifier to drying and pyrolysis zones of the reactor. The effects of gasification on gas flow rate of approximately 1.62–3.54 m3/hr and the performance of the gasification process were characterized in term of gas composition, conversion, gasification efficiency, biomass consumption rate, and specific gasification rate. The thermal integration unit also improved gasification reaction in which lower tar content and high gas production efficiency can be achieved. The results suggested that the air flow rate had integrated effects on product yield and composition; optimum of air flow rate resulted in the conversion of carbon converted to CO, CO2, and CH4 of 47.21%, 37.88%, and 8.76% respectively whereas hydrogen converted to H2 and CH4 were 49.31% and 20.91%, respectively at 3.06 m3/hr air. This was due to the chemical decomposition in the presence of oxygen and heat from combustion which supported the gasification reactions. The quality of product gas is found to be dependent on the air flow rate and continuity of feeding material. The produced gas from gasification of peanut shell waste contained quality combustible gases, which can be readily used in heat and power applications.

Autothermal Catalytic Reforming of Pine-Wood-Derived Fast Pyrolysis Oil in a 1.5 kg/h Pilot Installation: Performance of Monolithic Catalysts

The autothermal catalytic reforming of pyrolysis oil for the production of syngas has been studied in a 1.5 kg/h pilot unit. The influence of the feed ratio’s air-fuel-steam and the catalyst amount on the product gas quality were determined. While using a combination of nickel and platinum group metal (PGM) catalysts in monolithic form, a nearly tar- and methane-free product gas could be produced. The maximum syngas yield was obtained at an equivalence ratio of 0.36 and a space time of 1.3 s. These conditions resulted in the production of 47 mol syngas per kg of pyrolysis oil, which corresponds to 97% of the theoretical maximum. The total syngas production decreased at lower equivalence ratios primarily due to increased formation of carbonaceous solids. Incomplete conversion of methane at lower equivalence ratios had a smaller impact on the syngas production. Decreasing the space time to 0.7 s increased both the methane and tar concentrations in the product gas. Tar concentrations remained below 6 mg/Nm3 ...

A Non-Isothermal Thermo Gravimetric Kinetic Analysis of Malaysian Poultry-Processing-Dewatered-Sludge

Poultry processing dewatered sludge which consisting of trimmings, fat, feathers and liquid discharges from processing slaughtered chicken is typically land filled in specialized sites. It is a costly process to manage and if not handled according to stringent procedures can be harmful to the surrounding environment. The use of this waste material as an alternative fuel can be an effective solution, as it not only contributes as an energy source but also solves environmental issues related to poultry sludge disposal. Combustion, gasification and pyrolysis are efficient techniques of utilizing energy effectively from poultry sludge. The performances of mathematical models to predict the product gas quality is rely on characterization of feed materials as well as the reaction kinetics of their thermal degradation. The aim of this study is to determine selected physical and chemical properties of poultry sludge associated with thermochemical conversion. Thermogravimetric analyses were performed at heating rates of 10, 20, 30, and 40 K/min in an air (oxidizing) atmosphere. The parameters of the reaction kinetics such as activation energy and reaction order were obtained by the application of OzawaFlynn Wall and Vyazovkin kinetic models.

PERFORMANCE STUDIES ON DOWNDRAFT GASIFIER WITH BIOMASS ENERGY SOURCES AVAILABLE IN REMOTE VILLAGES

Increasing global concern over the environmental is sues and depletion of fossil fuels, significant int erest has been shown by the researchers to develop alternate energy technologies like biomass, biogas, solar to meet the future energy demand. The prediction of the performance of different biomass energy sources in gasifie rs is needed for the implementation of this technology to fulfil the need of decentralized heat and power applications, relevant to remote villages. This stu dy presents the theoretical and experimental studie s conducted on a 50 kW downdraft biomass gasifier with various biomass materials such as wood, coconut shell, rubber seed kernel and coir pith which are g enerally available in villages. Two-zone kinetic eq uilibrium model approach is used to predict the composition a nd temperature of the producer gas. The influence o f equivalence ratio on the reaction temperature, qual ity of producer gas and gasifier conversion efficie ncy are discussed. The experimental and theoretical studies show that the rubber seed kernel can be effectivel y used as a feedstock of the biomass gasifier to meet the rur al energy demand.