scholarly journals Heat Exchanger for Bio-Digester under Thermophilic Range

2019 ◽  
Vol 5 ◽  
pp. 79-88
Author(s):  
Prajwal Sapkota ◽  
Laxman Poudel
Keyword(s):  
Heat Exchanger ◽  
Anaerobic Digestion ◽  
Heat Exchangers ◽  
Heating System ◽  
Gas Production ◽  
Cow Dung ◽  
Digestion Rate ◽  
Digestion Process ◽  
Different Temperatures ◽  
Long Time

Bio-gas has been one of the sources of renewable energy and has been used from long time. It is produced by the anaerobic digestion or decomposition of organic compounds and has different process. The digestion process is carried out by bacteria present in the waste and it is highly dependent on the bacteria which work differently on different temperatures. The rate of anaerobic digestion is highest at hemophilic temperature (55°C). Similarly, it is moderate at mesophilic temperature (35°C) and is lowest at psychrophilic (below 20°C). Thus, to attain the highest digestion rate a thermophilic heating system has beend eveloped. The heating system uses five heat exchangers to heat the influent at digester which is of 35m3 volume, to maintain temperature at 56°C. The volume of bio-gas production from this system which uses cow dung as digestingmaterial is about 28 m3 per day.

A Mathematical Model for the Anaerobic Digestion Process Applied to a Mixture of Night Soil and Septic Tank Sludge

1986 ◽  
Vol 18 (7-8) ◽  
pp. 239-248 ◽  
Author(s):  
Sung Ryong Ha ◽  
Dwang Ho Lee ◽  
Sang Eun Lee
Keyword(s):  
Mathematical Model ◽  
Anaerobic Digestion ◽  
Biomass Concentration ◽  
Gas Production ◽  
Septic Tank ◽  
Volatile Acid ◽  
Hydraulic Residence Time ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Proposed Model

Laboratory scale experiments were conducted to develop a mathematical model for the anaerobic digestion of a mixture of night soil and septic tank sludge. The optimum mixing ratio by volume between night soil and septic tank sludge was found to be 7:3. Due to the high solids content in the influent waste, mixed-liquor volatile suspended solids (MLVSS) was not considered to be a proper parameter for biomass concentration, therefore, the active biomass concentration was estimated based on deoxyribonucleic acid (DNA) concentration in the reactor. The weight ratio between acidogenic bacteria and methanogenic bacteria in the mixed culture of a well-operated anaerobic digester was approximately 3:2. The proposed model indicates that the amount of volatile acid produced and the gas production rate can be expressed as a function of hydraulic residence time (HRT). The kinetic constants of the two phases of the anaerobic digestion process were determined, and a computer was used to simulate results using the proposed model for the various operating parameters, such as BOD5 and volatile acid concentrations in effluent, biomass concentrations and gas production rates. These were consistent with the experimental data.

Failure Analysis of Heat Exchangers

2021 ◽  
pp. 3-19
Author(s):  
Dusan P. Sekulic
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Failure Analysis ◽  
Thermal Energy ◽  
Solid Surface ◽  
Heat Exchangers ◽  
Heat Transfer Surface ◽  
Tubular Heat Exchanger ◽  
Erosion Corrosion ◽  
Different Temperatures

Abstract Heat exchangers are devices used to transfer thermal energy between two or more fluids, between a solid surface and a fluid, or between a solid particulate and a fluid at different temperatures. This article first addresses the causes of failures in heat exchangers. It then provides a description of heat-transfer surface area, discussing the design of the tubular heat exchanger. Next, the article discusses the processes involved in the examination of failed parts. Finally, it describes the most important types of corrosion, including uniform, galvanic, pitting, stress, and erosion corrosion.

Highly Efficient Anaerobic Digestion with Thermal Pretreatment

1985 ◽  
Vol 17 (4-5) ◽  
pp. 529-539 ◽  
Author(s):  
M. Hiraoka ◽  
N. Takeda ◽  
S. Sakai ◽  
A. Yasuda
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Pilot Plant ◽  
Molecular Size ◽  
Gas Production ◽  
Thermal Pretreatment ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Before And After ◽  
Pilot Plant Study

The effectiveness of an anaerobic digestion process with thermal pretreatment at a comparatively low temperature was examined. The waste activated sludge was thermally pretreated in the process. A laboratory scale experiment and a pilot plant study were conducted. Changes in volatile acids concentration, in major constituents of sludge and in molecular size distribution were examined before and after thermal pretreatment and anaerobic digestion. Thermal pretreatment resulted in an increase of more than 30 percent in digestion gas production. The major substrates decomposed were fats in the pilot plant study. Glyceride fatty acids are decomposed with thermal pretreatment and produce volatile acids such as acetic and propionic acids. The volatile acids are directly utilized by anaerobes to produce methane. Organic matter such as fats and carbohydrates are depolymerized with thermal pretreatment and produce soluble intermediate compounds such as higher fatty acids. The intermediates are utilized in the anaerobic digestion process. These two major effects facilitate the methane production process.

scholarly journals Kinetic Study on Biogas Production from Cabbage (Brassica oleracea) Waste and Its Blend with Animal Manure Using Logistic Function Model

2021 ◽  
pp. 34-43
Author(s):  
Christian C. Opurum
Keyword(s):  
Anaerobic Digestion ◽  
Kinetic Parameters ◽  
Goodness Of Fit ◽  
Biogas Production ◽  
Logistic Function ◽  
Gas Production ◽  
Cow Dung ◽  
Function Model ◽  
Biogas Yield ◽  
Significant Difference

This research paper aimed to evaluate the kinetics of anaerobic digestion (AD) of mixtures of cabbage waste (CW) with (Poultry dropping (PD) and Cow dung (CD). The study was conducted in 10L bio-digesters for 35 days under mesophilic conditions (25 - 35OC). Logistic function equation was used to simulate the experimental data to test for its goodness of fit and kinetic parameters namely: maximum biogas potential (Pb), the maximum biogas production rate (Rm), and the lag phase duration (λ) were estimated in each treatment. Chemical analysis showed that individual substrates possess characteristics that could support microbial activities in biogas production. The biogas yield in terms of added  volatile solids (VS) in decreasing order was as follows: 0.022, 0.018, 0.017, 0.014, 0.014 and 0.013 dm3/g VS for CW/CD 2:1, CW/PD3:1, CW/CD 1:1, CW alone, CW/PD1:1 and  CW/PD 2:1, respectively. A significant difference (P ≤ 0.05) in biogas yield was recorded in CW/CD 2:1 with 7.19 dm3 (53.29% increase). The kinetic parameters (Pb, Rm, and λ) for CW/CD 2:1 was 7.01 dm3, 1.58 dm3.d, and 2.29 days, respectively. This was followed by CW/PD 3:1 (5.84 dm3); with 24.92% increase in gas production and CW/CD 1:1 (5.42 dm3) with 15.53% increase relative to CW alone, 4.69 dm3. The digesters fed with CW/PD 1:1 and CW/PD 2:1 exhibited inhibitory effects on biogas production, with 7.51 and 2.05% decrease in gas yield, respectively. The logistic function model demonstrated a strong relationship between the experimental and model-predicted data. The high correlation coefficient (R2) ranging between 0.978 - 0.993 is evident. The model proved to be a useful tool in predicting anaerobic digestion and biogas production process.

scholarly journals Investigation on mesophilic anaerobic co-digestion of community waste and cow dung: effect of operating parameters

2019 ◽  
Vol 4 (6) ◽  
Author(s):  
KO Ansah Amano ◽  
E Appiah-Danquah ◽  
E Adom ◽  
AG Ntiri-Asiedu ◽  
ES Amoamah ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Ph Value ◽  
Cow Dung ◽  
Waste Generation ◽  
Batch Mode ◽  
Biogas Yield ◽  
Digestion Process ◽  
Ph Range

Management of waste is a key concern in several communities in Ghana. The exponential growth in waste generation imposes serious threats such as environmental pollution, health risk and scarcity of dumping site to our society. A large variety of organic rich materials inherent in this waste have high potential to be treated by the use of anaerobic digestion. In this study, eight (8) Laboratory scale biodigesters were used for the anaerobic co-digestion of household and market waste with cow dung as inoculum, controlled at a pH range of 6.53-7.04 and at a mesophilic temperature of 35±2˚C. The study was also conducted in batch mode at a hydraulic retention time of 21 days. The anaerobic co-digestion process was developed and optimized at varying feedstock to inoculum ratio to determine the potential biogas yield from each proportion. The results obtained indicate sample S8, containing market waste and inoculum in the ratio of 6:1 produced the optimum concentration of methane (51% v/v biogas) while the least was recorded by sample S2 primarily made up of market waste. ANOVA results show that the concentration of methane produced from the substrate is significantly affected by the hydraulic retention time and pH value of the anaerobic digestion process.

scholarly journals Anaerobic digestion of tannery solid waste by mixing with different substrates

2015 ◽  
Vol 49 (2) ◽  
pp. 119-124 ◽  
Author(s):  
SR Basak ◽  
MA Rouf ◽  
MD Hossain ◽  
MS Islam ◽  
T Rabeya
Keyword(s):  
Anaerobic Digestion ◽  
Solid Waste ◽  
Total Solid ◽  
Volatile Matter ◽  
Domestic Sewage ◽  
Gas Production ◽  
Cow Dung ◽  
Optimum Result ◽  
Volatile Solids ◽  
Tannery Solid Waste

The tannery solid waste (fleshing) was collected from Hazaribagh, Dhaka. It has been found that fleshing contains 82.57% volatile matter. Further characterization of fleshing showed that it contains low C/N ratio of 2.64 and high pH of 10.99. These characteristics were not suitable for using fleshing as a substrate for anaerobic digestion. The study has been carried out in different ratio of waste fleshing, domestic sewage and cow dung at total solid 6% concentration. In all the reactors fleshing and domestic sewage were mixed at 1:1 ratio. On the basis of the performance of the reactors it was evident that the reactor which contains 75% fleshing with domestic sewage and 25% cow dung showed optimum result. Under optimum condition volatile solids destruction 52%, specific gas production 0.476 L/g volatile solids feed and methane yield 73% were achieved. DOI: http://dx.doi.org/10.3329/bjsir.v49i2.22006 Bangladesh J. Sci. Ind. Res. 49(2), 119-124, 2014

OPTIMIZATION OF HEAT EXCHANGERS FOR GEOTHERMAL DISTRICT HEATING

2009 ◽  
Vol 33 (2) ◽  
pp. 239-256
Author(s):  
P. Bahadorani ◽  
G. F. Naterer ◽  
S. B. Nokleby
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
District Heating ◽  
Heating System ◽  
Power Input ◽  
Design Tool ◽  
Geothermal Systems ◽  
District Heating System ◽  
Wide Range ◽  
Net Profit

This paper analyzes the optimal configuration and operating parameters of a heat exchanger in a geothermal district heating system. An optimization algorithm is presented for the nonlinear constrained problem to maximize the annual net profit for a system of counter-flow heat exchangers. Several parameters that affect the net profit are examined, including the mass flow rates of working fluids and heat transfer area, which both directly affect the outgoing temperatures. The performance of the heat exchanger and fuel savings by reducing fuel consumption to generate heat are modeled within the problem formulation. Also, power input to the pump for fluid circulation is included. By formulating these multiple parameters over a wide range of design conditions, the algorithm presents a useful new design tool for the improvement of heat exchanger networks in geothermal systems.

scholarly journals Effectiveness Analysis of Anaerobic Digestion Method in Making Biogas from Animal Manure and Tofu Liquid Waste

2021 ◽  
Vol 16 (2) ◽  
pp. 84-94
Author(s):  
Fahmi Arifan ◽  
Abdullah Abdullah ◽  
Siswo Sumardiono
Keyword(s):  
Anaerobic Digestion ◽  
Organic Waste ◽  
Raw Materials ◽  
Liquid Waste ◽  
Methanogenic Bacteria ◽  
Chicken Manure ◽  
Cow Dung ◽  
Digestion Method ◽  
Anaerobic Digestion Process ◽  
Digestion Process

Organic waste has high COD and BOD content, so it is dangerous if disposed of directly into the environment. Organic waste processing, such as waste from livestock manure and liquid tofu waste, requires a process that can reduce COD and BOD levels as well as produce valuable products. Anaerobic digestion method is the proper process to convert complex compounds in waste into simpler compounds with methanogenic bacteria into a renewable energy product, namely biogas. On the other hand, the anaerobic digestion process can reduce COD and BOD levels in the biogas formation process. This study uses raw materials such as cow manure and chicken manure, and liquid tofu waste. The variables that produced the largest biogas were those with a ratio of 70% cow dung, 15% chicken manure, and 15% tofu liquid waste with a total of 3,251.5 mL. Then, the COD and BOD levels decreased significantly with more than 98% COD removal, and more than 95% BOD removal in all variables at the end of the anaerobic digestion process.

scholarly journals Biocomposites from anaerobically digested Eichhornia crassipes ((Mart.) Solms), as an alternative solution for the post-phytoremediation process

2021 ◽  
Vol 2 (2) ◽  
pp. 139-144
Author(s):  
Gabriella Marsaulina ◽  
◽  
Taufik Taufikurahman ◽  
Andira Rahmawati
Keyword(s):  
Anaerobic Digestion ◽  
Water Hyacinth ◽  
Eichhornia Crassipes ◽  
Chromium Content ◽  
Liquid Waste ◽  
Absorption Capacity ◽  
Cow Dung ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Water Hyacinths

Water hyacinth (Eichhornia crassipes) is a plant species commonly used for phytoremediation to reduce high chromium content in tannery liquid waste in Garut, West Java. Water hyacinth materials harvested from the phytoremediation can be used for the anaerobic digestion process to produce biogas and bio-slurry. This study aimed to determine the reduction of chromium content found in water hyacinths due to the anaerobic digestion process, and utilization of bio-slurry from the anaerobic digestion process as a biocomposite material. The anaerobic digestion process was carried out for 33 d using biodigesters and the composition of the biodigesters were varied into 100% dried water hyacinths and 80% water hyacinths with the addition of 20% cow dung. The bio-slurry from the anaerobic digestion process was then used for making biocomposites with 3 different compositions, i.e., 75 and 25%; 50 and 50%; and 25 and 75% of cement and bio-slurry, respectively. The average chromium content found in water hyacinths from the phytoremediation process without anaerobic digestion process was 41.964 mg/l. The results show a reduction in the amount of chromium after the anaerobic digestion process was found in each composition of bio-slurry, which were 15.979 mg/l (100% water hyacinth) and 14.861 mg/l (80% water hyacinth + 20% cow dung). Biodigester with a composition of 80% water hyacinth + 20% cow dung produced the highest average volume of biogas which was 0.424 l. The biocomposite of 75% cement and 25% bio-slurry had the highest compressive strength value of 30.598 MPa and water absorption capacity of 37.25%. It can be concluded that biocomposite with the composition of 75% cement and 25% water hyacinth bio-slurry is promising to be used as an alternative material for buildings.

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