scholarly journals Studies on the Gasification Performance of Sludge Cake Pre-Treated by Hydrothermal Carbonization

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1442 ◽  
Author(s):  
Sang Yeop Lee ◽  
Se Won Park ◽  
Md Tanvir Alam ◽  
Yean Ouk Jeong ◽  
Yong-Chil Seo ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Moisture Content ◽  
Energy Recovery ◽  
Calorific Value ◽  
Hydrothermal Carbonization ◽  
Treatment Technique ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Sludge Cake ◽  
Gas Efficiency

Proper treatment and careful management of sewage sludge are essential because its disposal can lead to adverse environmental impacts such as public health hazards, as well as air, soil, and water pollution. Several efforts are being made currently not only to safely dispose of sewage sludge but also to utilize it as an energy source. Therefore, in this study, initiatives were taken to valorize sewage sludge cake by reducing the moisture content and increasing the calorific value by applying a hydrothermal treatment technique for efficient energy recovery. The sludge cake treated at 200 °C for 1 h was found to be the optimum condition for hydrothermal carbonization, as, in this condition, the caloric value of the treated sludge increased by 10% and the moisture content removed was 20 wt.%. To recover energy from the hydrothermally treated sludge, a gasification technology was applied at 900 °C. The results showed that the product gas from hydrothermally treated sludge cake had a higher lower heating value (0.98 MJ/Nm3) and higher cold gas efficiency (5.8%). Furthermore, compared with raw sludge cake, less tar was generated during the gasification of hydrothermally treated sludge cake. The removal efficiency was 28.2%. Overall results depict that hydrothermally treated sewage sludge cake could be a good source of energy recovery via the gasification process.

scholarly journals Comparative Study of Municipal Solid Waste Fuel and Refuse Derived Fuel in the Gasification Process Using Multi Stage Downdraft Gasifier

2021 ◽  
Vol 4 (2) ◽  
pp. 97-103
Author(s):  
Sigit Mujiarto ◽  
Bambang Sudarmanta ◽  
Hamzah Fansuri ◽  
Arif Rahman Saleh
Keyword(s):  
Alternative Energy ◽  
Performance Indicator ◽  
Calorific Value ◽  
Alternative Energy Source ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Multi Stage ◽  
Refuse Derived Fuel ◽  
Gas Efficiency ◽  
Cold Gas

Municipal solid waste (MSW)  is a type of general waste that includes households, traditional markets, commercial areas, and the rest from public facilities, schools, offices, roads, and so on. Refuse Derived Fuel (RDF) is obtained from the remnants of MSW which cannot be used anymore, which is flammable waste and is separated from parts that are difficult to burn through the process of chopping, sifting, and air classification. RDF has potential as an alternative energy source. In this study, RDF fuel was compared with MSW fuel both by proximate and calorific value, then the gasification process was carried out using a multi-stage downdraft gasifier to see gasification performance indicators such as syngas composition, LHV, cold gas efficiency, and tar concentration. The results showed that the gasification performance indicator for MSW biomass resulted in the syngas composition of CO = 19.08% v, H2 = 10.89% v, and CH4 = 1.54% v. The calorific value (Low Heating Value, LHV ) of syngas is 4,137 kJ/kg, cold gas efficiency is 70.14%, and tar content is 57.29 mg/Nm3. Meanwhile, RDF obtained the composition of CO gas: 18.68% v, H2: 9.5446% v, and CH4: 0% v. The maximum LHV syngas is 3365.08 kJ/kg, cold gas efficiency is 57.19 % and the smallest tar content is 80.24 mg/Nm3. When compared to RDF, MSW produces a better gasification performance indicator. However, RDF can still be used as an alternative energy source using the gasification process. The results of this study can be used to optimize the further RDF gasification process.

Gasification: An alternative solution for energy recovery and utilization of vegetable market waste

2016 ◽  
Vol 35 (3) ◽  
pp. 276-284 ◽  
Author(s):  
Sunil L Narnaware ◽  
NSL Srivastava ◽  
Samir Vahora
Keyword(s):  
Power Generation ◽  
Energy Recovery ◽  
Combustion Engine ◽  
Calorific Value ◽  
Maximum Load ◽  
Thermochemical Conversion ◽  
Small Scale ◽  
Vegetable Waste ◽  
Cold Gas Efficiency ◽  
Gas Efficiency

Vegetables waste is generally utilized through a bioconversion process or disposed of at municipal landfills, dumping sites or dumped on open land, emitting a foul odor and causing health hazards. The presents study deals with an alternative way to utilize solid vegetable waste through a thermochemical route such as briquetting and gasification for its energy recovery and subsequent power generation. Briquettes of 50 mm diameter were produced from four different types of vegetable waste. The bulk density of briquettes produced was increased 10 to 15 times higher than the density of the dried vegetable waste in loose form. The lower heating value (LHV) of the briquettes ranged from 10.26 MJ kg−1 to 16.60 MJ kg−1 depending on the type of vegetable waste. The gasification of the briquettes was carried out in an open core downdraft gasifier, which resulted in syngas with a calorific value of 4.71 MJ Nm−3 at the gasification temperature between 889°C and 1011°C. A spark ignition, internal combustion engine was run on syngas and could generate a maximum load up to 10 kWe. The cold gas efficiency and the hot gas efficiency of the gasifier were measured at 74.11% and 79.87%, respectively. Energy recovery from the organic vegetable waste was possible through a thermochemical conversion route such as briquetting and subsequent gasification and recovery of the fuel for small-scale power generation.

Effect of Swirl on Gasification Characteristics in an Entrained-flow Coal Gasifier

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Rongbin Li ◽  
Mingzhuang Xie ◽  
Hui Jin ◽  
Liejin Guo ◽  
Fengqin Liu
Keyword(s):  
Coal Gasification ◽  
Three Dimensional ◽  
Reaction Model ◽  
Gas Temperature ◽  
Swirl Number ◽  
Entrained Flow ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Product Composition ◽  
Gas Efficiency

AbstractThe three-dimensional (3-D) comprehensive mathematical model was developed to simulate the coal gasification process in an entrained flow gasifier with a swirl burner. The models employed or developed includes the coal devolatilization model, the char combustion and gasification model, the gas homogeneous reaction model, the random-trajectory model, gas turbulence model, and the P-1 radiation model. The solution of models was executed based on the computational fluid dynamics (CFD). By qualitatively comparing the results at different swirl number, the significant influences of swirl on characteristics of coal gasification such as flow distributions, gas temperature and product composition including hydrogen (H2), carbon monoxide (CO), etc., and on the performance of coal gasification such as averaged exit product composition, carbon conversion rate and cold gas efficiency, were in detail discussed. Especially, a proper swirl number (S ≤ 0.65) in favor of gasification was found for the investigated gasifier in this paper.

The Effect of Biomass Contents with Heavy Metal on Gasification Efficiency during Fluidized Bed Gasification Process

2012 ◽  
Vol 512-515 ◽  
pp. 575-578
Author(s):  
Hsien Chen ◽  
Chiou Liang Lin ◽  
Wun Yue Zeng ◽  
Zi Bin Xu
Keyword(s):  
H2 Production ◽  
Heating Value ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Zn Concentration ◽  
Lower Heating Value ◽  
Gasification Efficiency ◽  
Waste Gasification ◽  
Gas Efficiency ◽  
Cu And Zn

Catalysis was used to increase the H2 production, syngas heating value, enhanced carbon conversion efficiency and cold gas efficiency during gasification. Due to Cu and Zn were abundant in waste according to previous researches, this research discussed the effect of Cu and Zn on artificial waste gasification. The syngas composition and total lower heating value (LHV) were determined in this study. The results showed that the existence of Cu and Zn increased production of H2 and CO. However, the production of CH4 and CO2 decreased. At same time, total LHV was also increased. Additionally, the different Cu concentration affected gas composition and LHV, but the effect of Zn concentration was not significant.

Characteristics of Sewage Sludge Affecting Dewatering by Belt Press Filter

1990 ◽  
Vol 22 (12) ◽  
pp. 143-152 ◽  
Author(s):  
M. Hashimoto ◽  
M. Hiraoka
Keyword(s):  
Sewage Sludge ◽  
Moisture Content ◽  
Charge Density ◽  
Suspended Solids ◽  
Factors Affecting ◽  
Solids Concentration ◽  
Sludge Cake ◽  
Extension Degree ◽  
Dewatered Sludge ◽  
Belt Press

Dewatering characteristics of sewage sludge were determined by conditioning the sludge with the most effective cationic polyelectrolyte studied, and dewatering using a belt press filter. The characteristics of sludges (16 mixed, and 8 anaerobically digested) were measured for 33 factors affecting dewaterability. The correlations of sludge factors with sludge dewaterability were investigated. The results revealed the following. A factor affecting the gravitational filterability of conditioned sludge is the suspended solids concentration of raw sludge. A factor affecting the moisture content of dewatered sludge cake is viscosity of the sludge adjusted to 4.0 % of suspended solids concentration. Factors affecting the viscosity are the intrinsic viscosity of alkaline extracts, the ratio of (VSS-Fiber)/SS : Ash/SS : Fiber/SS, and the charge density of sludge particles. A factor affecting the extension degree of dewatered sludge cake is the charge density of sludge particles. Factors affecting the amount of residual solids on the filter cloths are the charge density of sludge particles and the fibrous substances content of sludge. As for polyelectrolytes, a highly cationized polyelectrolyte is effective to lower the moisture content, the extension degree and the amount of residual solids on filter cloths. And a factor affecting the required dosage of a polyelectrolyte is anionic substances content in the liquid of raw sludge.

scholarly journals Effect of Gasification Temperature on Synthesis Gas Production and Gasification Performance for Raw and Torrefied Palm Mesocarp Fibre

2020 ◽  
Vol 19 (2) ◽  
pp. 138
Author(s):  
Najwa Hayati Abdul Halim ◽  
Suriyati Saleh ◽  
Noor Asma Fazli Abdul Samad
Keyword(s):  
Synthesis Gas ◽  
Gas Production ◽  
Energy Applications ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Bubbling Fluidized Bed ◽  
Pre Treatment ◽  
Gas Efficiency ◽  
Solid Biomass ◽  
Gasification Temperature

Biomass gasification is widely used for converting solid biomass into synthesis gas for energy applications. Raw biomass is commonly used as feedstock for the gasification process but it usually contains high moisture content and low energy value which lowering synthesis gas production. Thus, torrefaction as a pre-treatment process is necessary in order to upgrade the properties of feedstock for producing more synthesis gas production and improving gasification performance. The objective of this work is to study the effect of gasification temperature on the synthesis gas production and gasification performance using raw and torrefied palm mesocarp fibre (PMF). The gasification process is conducted using bubbling fluidized bed using steam as gasifying agent. Based on experimental work, by increasing gasification temperature from 650 – 900 °C, the compositions of hydrogen and carbon monoxide gases were enhanced greatly while carbon dioxide and methane gases were decreased for both raw and torrefied PMF. In terms of gasification performance, synthesis gas yield for raw and torrefied PMF is increased from 0.91 to 1.23 Nm3/kg and 1.10 to 1.35 Nm3/kg respectively. Besides, lower heating value (LHV) of torrefied PMF is 0.04 MJ/Nm3 higher than raw PMF at 900 °C. The result showed that the percentage of cold gas efficiency (CGE) reached maximum of 67% for raw PMF while carbon conversion (CC) at 85.6% for torrefied PMF at a gasification temperature of 900 °C. The higher CC obtained by torrefied PMF is because of the increment of carbon content from 45.2% to 53.7% as a result of torrefaction. Gasification temperature of 800 °C showed the best performance of the PMF gasification since the maximum performances of LHV is achieved and started to decrease once the gasification temperature is operated beyond 800 °C.

scholarly journals TINJAUAN PEMANFAATAN SLUDGE CAKE PABRIK PULP KRAFT SEBAGAI ENERGI ALTERNATIF MELALUI PROSES GASIFIKASI

2015 ◽  
Vol 5 (01) ◽  
Author(s):  
Syamsudin Syamsudin
Keyword(s):  
Moisture Content ◽  
Alternative Energy ◽  
Combustion Process ◽  
Pulp Mill ◽  
Calorific Value ◽  
Steam Gasification ◽  
Gaseous Fuel ◽  
Biomass Waste ◽  
Lime Kiln ◽  
Sludge Cake

Kraft pulp mills generate large amounts of sludge cake with typical calorific value of 24 MJ/kg (dry and ash-free basis). Sludge cake could be utilized as an alternative energy through gasification to produce medium gaseous fuel. Sludge cake has a high moisture content and low dewaterability, probably due to biomass from the microbial growth in the wastewater treatment by activated sludge. These problems could be overcome by the addition of filtration aid utilizing biomass waste from pulp mill and dewatering processes by TAMD method. Drying was continued by utilizing hot flue gas from the boiler or lime kiln. Steam gasification of sludge cake by allothermal model could produce a gaseous fuel with a calorific value of 11 MJ/Nm3. Allothermal gasification model of two reactors was able for handling sludge cake with a moisture content of <55%, but produce gas with a high tar content.Gasification or combustion of sludge cake on this model should be performed at temperatures >1200°C to prevent slagging and fouling problem. In contrast, allothermal gasification model of three reactors could produce gas with a low tar content. Heat of gasification reaction might be supplied from thecombustion of volatile gas. Pyrolysis could be performed at temperatures <500oC to permit adequateheat supply for gasification and high char yield. Substitution of natural gas with producer gas need topay attention to the redesign of the combustion process associated with the lower heat of combustion.Keywords: sludge cake, dewatering, gasification, steam, CO2, medium gaseous fuelABSTRAK Pabrik pulp kraft menghasilkan sludge cake dalam jumlah besar dengan nilai kalor tipikal 20 MJ/kg (dasar kering dan bebas abu). Sludge cake dapat dimanfaatkan sebagai energi alternatif melalui gasifikasi untuk menghasilkan bahan bakar gas medium. Sludge cake memiliki kadar air tinggi dan dewaterability rendah, disebabkan adanya biomassa hasil pertumbuhan mikroba pengolahan air limbahsecara lumpur aktif. Kendala ini diatasi dengan penambahan media bantu  filtrasi memanfaatkan limbah biomassa pabrik pulp dan proses dewatering dengan metode TAMD. Pengeringan dilanjutkan dengan memanfaatkan gas panas dari boiler atau lime kiln. Proses gasifikasi-kukus allothermal terhadap sludge cake dapat menghasilkan gas bakar dengan nilai kalor 11 MJ/Nm3. Gasifikasi allothermal model dua reaktor mampu menangani sludge cake dengan kadar air <55%, namun menghasilkan gas dengan kadar tar yang tinggi. Gasifikasi atau pembakaran sludge cake pada model ini sebaiknya dilakukan pada suhu di bawah 1200oC untuk menghindari terjadinya slagging dan fouling. Sebaliknya, gasifikasi allothermal model tiga reaktor dapat menghasilkan gas dengan kadar tar rendah. Panas reaksi gasifikasi mungkin dapat dipenuhi dari pembakaran gas volatil hasil pirolisis. Pirolisis dapat dilakukan pada suhu <500ºC dengan mempertimbangkan kecukupan suplai panas gasifikasi dan yield arang tinggi. Penggantian gas bumi dengan gas produser perlu memperhatikan redesign proses pembakaran terkait dengan panas pembakaran yang lebih rendah.Kata kunci: sludge cake, dewatering, gasifikasi, kukus, CO2, bahan bakar gas kalor medium

scholarly journals Coupling hydrothermal carbonization with anaerobic digestion: an evaluation based on energy recovery and hydrochar utilization

2021 ◽  
Vol 8 (3) ◽  
pp. 1444-1453
Author(s):  
Mahmood Al Ramahi ◽  
Gábor Keszthelyi-Szabó ◽  
Sándor Beszédes
Keyword(s):  
Anaerobic Digestion ◽  
Energy Recovery ◽  
Oxygen Demand ◽  
Hydrothermal Carbonization ◽  
Steam Gasification ◽  
Post Treatment ◽  
Point Of View ◽  
Yield Potential ◽  
Treatment Technique ◽  
Dairy Sludge

This work evaluates the effect of hydrothermal carbonization (HTC) as a pretreatment and post-treatment technique to anaerobic digestion (AD) of dairy sludge. HTC's effect on AD was evaluated based on energy recovery, nutrient transformation, and hydrochar utilization. The first approach was executed by performing HTC under a range of temperatures before mesophilic AD. HTC optimal pretreatment temperature was 210 °C for 30 min residence time. HTC pretreatment significantly increased the methane yield potential by 192%, the chemical oxygen demand removal by 18%, and the sludge biodegradability during AD by 30%. On the other hand, the application of HTC after AD (post-treatment) increased the total energy production, i.e., in addition to methane, a hydrochar with a caloric value of 10.2 MJ/kg was also obtained. Moreover, HTC post-treatment improved the steam gasification performance of the AD digestate. From the fertilizer quality point of view, HTC implementation generally boosted the concentrations of macro, micro, and secondary nutrients, suggesting its suitability for use as a liquid fertilizer. Overall, the findings of the present study indicate that if bioenergy production were the main target, HTC post-treatment following AD would lead to the most promising outcomes.

scholarly journals Mechanical Dewatering and Thermal Drying Characteristics of Pulp Mill Sludge Cake

2020 ◽  
Author(s):  
Kevin Prawiranto ◽  
Syamsudin ◽  
Herri Susanto
Keyword(s):  
Energy Consumption ◽  
Moisture Content ◽  
Water Content ◽  
Calorific Value ◽  
High Water Content ◽  
Initial Water Content ◽  
Main Concern ◽  
Coal Powder ◽  
Thermal Drying ◽  
Sludge Cake

Sludge cake is a type of solid waste in pulp and paper mills which may harm the environment if disposed without treatment. Its proximate analysis (adb) are: ash 26.74%; volatile matter 59.09%; fixed carbon 11.04%; moisture 3.13%, while its ultimate analysis (adb) are: C 33.46%; H 4.5%; N 1.14%; S 0.35%; O 33.81%. Having a calorific value of 3000 cal/g (adb), sludge cake may be used as renewable fuel. Unfortunately it has a high water content, so reduction of water content become a main concern in utilizing sludge cake. A combination of mechanical dewatering and thermal drying has been considered for water removal with a minimum energy consumption. Moreover, the application of pressurized mechanical dewatering may also play a role in formation of briquettes.Experiments on mechanical dewatering and thermal drying were carried out using 50 g sludge cake with initial water content 73%. With a pressure of 400 kg/cm2 for compression, water content at the end of mechanical dewatering was 57%. This dewatered slugde was subsequently treated using thermal drying to a moisture content of 15%. Calculated total energy for this combination of mechanical dewatering and thermal drying was about 1080 J/g. This value was lower than the energy consumption of 1520 J/g required for direct thermal drying from its moisture content of 73% down to 15%. Experiments on the use of coal powder as compression aid were also trial to improve sludge dewaterability and briquettes calorific value. Mechanical dewatering of slugde with addition of 20%-w/w coal powder resulting a briquette with moisture content of 38% at compression pressure of 400 kg/cm2. The drying curves of briquette did not affected with its size if its diameter was less than 0.5 cm. Briquette with 1 cm thickness took significantly more time to remove its water content.

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