Methane enrichment of biogas by carbon dioxide fixation with calcium hydroxide and activated carbon (original) (raw)
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Generation of Biogas and Enhancing its Methane Content by Chemical Absorption Technique
In this paper we will discuss India's existing biogas potential as a substitute to fossil fuels for domestic purpose. In the second part of the paper we will discuss the technique of upgrading the biogas using a chemical absorption technique for use in S.I engines as a substitute to compressed natural gas. A huge quantity of bio waste is generated in housing societies in metropolitan cities. Conversion of bio waste into biogas would result in localized municipal solid waste (MSW) management reducing the cost of transportation, eliminating the need of empty spaces for dumping grounds and also presenting an alternative source of fossil fuels. For experimentation, biogas was produced in a floating drum digester tank from daily produced kitchen waste and then with the chemical absorption technique using sodium carbonate (Na2CO3) as the scrubbing liquid, biogas was upgraded to bio-methane. The outcomes of the experiment was a combustible biogas consisting of 44.14% CO2, 53.19% CH4 and traces of other gases with a calorific value of 21180.25kJ/kg which when upgraded had around 88.39% methane and 8.05% carbon dioxide with a calorific value of 35196.89kJ/kg. I. INTRODUCTION Rapid urbanization and industrial growth puts the limited energy resources of developing countries under pressure resulting in the augmentation of new and existing renewable energy options. Dependency on thermal power plants for energy requirements causes depletion of fossil fuel reserves of the country and associated emissions of greenhouse gases into the atmosphere. A greenhouse emission further causes global warming, climatic changes and damage to human and animals respiratory systems[1]. Specifically in India, the current energy scenario reveals a wide gap between the supply and demand of energy. Three-quarters of India energy demand is met by fossil fuels[2]. It becomes extremely essential to explore the unearthed and untouched renewable energy reserves of the country in an organized way. This will decrease the dependency on fossil fuel imports and improve the energy economy of the country. In India, there is tremendous potential of renewable energy like solar, wind, biomass, biogas, tidal energy etc. As of 30 April 2017, the country's solar grid had a cumulative capacity of 12.50 GW, wind power grid had a cumulative capacity of 32.28 GW, small hydro plants had a cumulative grid capacity of 4.38 GW, biomass had a cumulative grid power capacity of 8.18 MW and biogas had a cumulative off grid capacity of 49.56 MW [3]. There is huge potential of waste to energy conversion in India. Around 30 million tons of solid waste and 4400 cubic meters of liquid waste is produced in India every year. The municipal solid waste (MSW) generation range is from 0.25 to 0.66 kg/person/day with an average of 0.45 kg/person /day [4]. With proper segregation and organized channelling, all these waste can be converted to useful biogas which is a potential substitute to LPG useful for cooking and water heating. In this paper we will discuss the biogas generation process in a floating type digester tank installed at Rajiv Gandhi Institute of technology and in the second part we will discuss the methodology of upgrading the biogas using chemical absorption technique. Upgraded biogas is an alternate for CNG and when compressed to a pressure of 200bar can be directly used to propel IC engines [5]. Paper is organized as follows. Section II describes biogas generation process in a floating drum digester tank using food waste. Biogas generated can be used directly in cooking stove and for water heating purpose. Raw biogas has a low calorific value for its use in engines. Section III describes the process of biogas scrubbing using solution of sodium carbonate. The complete setup will be discussed in this section. Biogas obtained after scrubbing is enhanced in methane content. Section IV presents experimental results showing graphs for raw and upgraded biogas obtained by gas chromatography technique. Finally, Section V presents conclusion.
Enhancement of Production and Upgradation of Biogas Using Different Techniques- A Review.pdf
Biomass is one of the most promising renewable energy sources which are utilizable to produce biogas through anaerobic digestion (AD), a feasible alternative for fossil fuel as well as organic solid waste disposal. The methane yields in biogas can be improved through co-digestion, a combination of hydrolysis, acidogenesis, acetogenesis and methanogenesis four anaerobic treatment stages which are capable to establish a synergy between the digestion medium and supply of missing nutrients. The most common constraints during biomass digestion are: the large HRT, P H , temperature and contaminant by CO 2 , with traces of water vapor and hydrogen sulfide. To use in mechanical power or in the natural gas grid it is necessary to remove the contaminants, as well as to adjust the calorific value. Usually the high density CO 2 is separated through pressure swing adsorption, membrane separation, or chemical absorption method. Air dosing, addition of iron chloride into the biogas digester and adsorption on iron oxide pellets, are common for removal of H 2 S. Condensation and drying methods are used to remove water in combination with foam and dust. However, different upgrading methods are differs in functioning, quality of incoming gas and the operational efficiency. This paper reviews the accelerate process of biogas generation from various sources the respected variation in the parameters and the comparative methane upgrading techniques. Besides, investment, operation and maintenance costs are also taken into consideration.
2018
This study evaluates methane enrichment on biogas generated from Anaerobic Digester (AD) through CO 2 adsorption process so that biogas can be used as fuel for vehicle engines, power plants, and natural gas substitutes. The experiment was observed by passing biogas synthesis (45% CH4 + 55% CO 2 ) and biogas from cattle manure ±59.7% CH 4 , ± 37.1% CO 2 and ±3.2% other gases) in spontaneously pressurized adsorption column. In addition, observation of CO 2 adsorption capacity at various pressure and fixed temperature (27°C) was performed using pure CO 2 (±98%). Methane in biogas has been successfully purified to 92% at 0.5 L/min flowrate and 79.6 seconds retention time. The adsorbent will be saturated after gas flowing for 60 and 80 minutes for synthesis biogas and biogas from AD on the amount of adsorbent of 266 grams. A change of surface area of activated carbon (AC) after thermal regeneration at 160°C for 2 hours was 7.51% and regeneration efficiency was 67%. The adsorption process...
Applied Biochemistry and Biotechnology, 2013
Biogas from anaerobic digestion of organic materials is a renewable energy resource that consists mainly of CH 4 and CO 2. Trace components that are often present in biogas are water vapor, hydrogen sulfide, siloxanes, hydrocarbons, ammonia, oxygen, carbon monoxide, and nitrogen. Considering the biogas is a clean and renewable form of energy that could well substitute the conventional source of energy (fossil fuels), the optimization of this type of energy becomes substantial. Various optimization techniques in biogas production process had been developed, including pretreatment, biotechnological approaches, co-digestion as well as the use of serial digester. For some application, the certain purity degree of biogas is needed. The presence of CO 2 and other trace components in biogas could affect engine performance adversely. Reducing CO 2 content will significantly upgrade the quality of biogas and enhancing the calorific value. Upgrading is generally performed in order to meet the standards for use as vehicle fuel or for injection in the natural gas grid. Different methods for biogas upgrading are used. They differ in functioning, the necessary quality conditions of the incoming gas, and the efficiency. Biogas can be purified from CO 2 using pressure swing adsorption, membrane separation, physical or chemical CO 2 absorption. This paper reviews the various techniques, which could be used to optimize the biogas production as well as to upgrade the biogas quality.
AIMS Energy, 2015
Biogas, which generated from renewable sources can be used as a sustainable energy to achieve resourceful targets of biofuel for internal combustion engines. This process can be achieved in combined absorption and adsorption chemical way. This method can be employed by aqueous solutions of calcium hydroxide, activated carbon, iron(II) chloride, silica gel and sodium sulfate respectively. The presence of CO 2 , H 2 S and H 2 O in the biogas has lowering the calorific value and detrimental corrosion effects on the metal components. Removal of these contaminants from the biogas can therefore significantly improve the gas quality. A comparison study was investigated using combined chemical methods of improving the calorific value of biogas. Experiment results revealed that the aqueous solution used effectively in reacting with CO 2 in biogas (over 85-90% removal efficiency), creating CH 4 enriched biogas. The removal efficiency was the highest in method 1, where efficiency results were 91.5%, 97.1% and 91.8%, for CO 2 , H 2 S, and H 2 O, respectively. The corresponding CH 4 enrichment was 97.5%. These results indicate that the method 1 is more suitable compare to method 2. However, both methane enrichment processes might be useful for cleaning and upgrading methane quality in biogas.
Biogas, which generated from renewable sources can be used as a sustainable energy to achieve resourceful targets of biofuel for internal combustion engines. This process can be achieved in combined absorption and adsorption chemical way. This method can be employed by aqueous solutions of calcium hydroxide, activated carbon, iron(II) chloride, silica gel and sodium sulfate respectively. The presence of CO 2 , H 2 S and H 2 O in the biogas has lowering the calorific value and detrimental corrosion effects on the metal components. Removal of these contaminants from the biogas can therefore significantly improve the gas quality. A comparison study was investigated using combined chemical methods of improving the calorific value of biogas. Experiment results revealed that the aqueous solution used effectively in reacting with CO 2 in biogas (over 85-90% removal efficiency), creating CH 4 enriched biogas. The removal efficiency was the highest in method 1, where efficiency results were 91.5%, 97.1% and 91.8%, for CO 2 , H 2 S, and H 2 O, respectively. The corresponding CH 4 enrichment was 97.5%. These results indicate that the method 1 is more suitable compare to method 2. However, both methane enrichment processes might be useful for cleaning and upgrading methane quality in biogas.
A review of chemical absorption of carbon dioxide for biogas upgrading
Chinese Journal of Chemical Engineering, 2016
The use of biogas generated in landfills has gained importance in developing countries like Colombia. Taking into account that this biogas presents poor combustion properties that make interchangeability with other combustible gases difficult, the elimination of gases and vapors, such as CO 2 and H 2 O, through a cleaning process, in which the biogas is converted to biomethane, improves the biogas properties as a fuel gas for general use. In this work, we simulated the generation of biogas at El Carrasco sanitary landfill in Bucaramanga, using the US EPA (United States Environmental Protection Agency) landfill gas emissions model. Additionally, we simulated the biogas cleaning process to extract the remaining moisture using the ProMax software; for this, we used three different amines (MDEA, MEA, and DEA), followed by a glycol dehydration process. The results showed that the amine MEA produced the largest increase in the concentration of CH 4 (90.37 %) for the biogas generated in the landfill. Furthermore, dehydration with glycol was an efficient process to obtain a gas with a high percentage of methane (91.47 %) and low water presence (1.27 %); this would allow the use of biomethane in conventional industrial combustion processes and power generation.
Biogas: Production, properties, applications, economic and challenges: A review
Results in Chemistry, 2024
Biogas is obtained from the breakdown of biomass by microorganisms and bacteria in the absence of oxygen. Biogas is considered a renewable source of energy, similar to solar energy and wind energy. Biogas can be produced from biomass or bio-waste; thus, it is environmentally friendly. Biogas is obtained in a suspended monoxide decomposition process by anaerobic bacteria or in a fermentation process of decomposable materials such as agricultural manure, sewage, municipal waste, green waste (gardens and parks), plant material and agricultural products. Biogas is a renewable natural energy source that leaves effective effects on nature and industries. This gas is produced from the decomposition of organic materials, including animal manure, food waste and sewage. Fertilizers and waste produce biogas through anaerobic digestion (ie without the presence of oxygen). Biogas is a mixture of gases generated by decaying biodegradable material without the presence of oxygen. Its main contents are 50–70 % of methane (CH4) by volume, 30–50 % of carbon dioxide (CO2), and traces of other gases, like hydrogen sulfide (H2S) and water vapor (H2O). CO2, H2S, and water vapor content in biogas may affect the performance and life of the energy conversion devices; consequently, their removal before end-use is essential for improving the quality of biogas. This combination is an ideal option for making renewable energy. The most important advantages of biogas (production of energy, reduction of the amount of discarded waste, reduction of pathogens, conversion of waste containing organic matter into high quality fertilizer, protection of vegetation, soil, water, increasing productivity in the field of livestock and agriculture) and It is also one of the disadvantages of biogas (incomplete and small technologies, containing impurities, the effect of temperature on biogas production, unsuitable for urban and dense areas, not affordable). For economical use of biogas, the fermentation process can be carried out under controlled conditions in a relatively simple device called a digestion reservoir. This review summarizes the current state-of-the-art and presents future perspectives related to the anaerobic digestion process for biogas production. Moreover, a historical retrospective of biogas sector from the early years of its development till its recent advancements give an outlook of the opportunities that are opening up for process optimization.
Recent Advances of Biogas Production and Future Perspective
Biogas - Recent Advances and Integrated Approaches, 2020
The production of biogas via anaerobic digestion (AD) provides significant benefits over other techniques of bioenergy production. Biogas consists of several undesired components, such as H2S, CO2, nitrogen, hydrogen, oxygen, and water vapor, which contribute to lower the calorific value when compared with natural gas. The pollutants founded in low concentration effects the biogas commercial application in large scale, and therefore it must be taken out before usage. Various cleaning and upgrading techniques to improve the quality of raw biogas are discussed and categorized into physiochemical and biological technologies. Advanced techniques, such as hydrate separation, cryogenic separation, biological methods, membrane enrichment, in-situ upgrading, multistage and high-pressurized anaerobic digestion, represent the modern developments in biogas upgrading techniques. Biogas is a renewable green source of energy, and presently, it is utilized in a lot of developing countries as an al...
The presence of CO 2 in biogas does not give to contribute to the colorific or heating value and are often washing out in purification plant in order to obtain a gas with almost 100% (volume/volume) and dangerous effect on environment. Therefore, CO 2 must be eliminated from the biogas and the corresponding phenomena of mass transfer with chemical reaction of packed column have to be studied. The purpose of this research is to analyze theoretically mass transfer phenomena of CO 2 chemical absorption in biogas using aqueous NaOH. 1M in packed column and to support procurement of energy alternative in Indonesia This study assumed studied state and isothermal condition. The system studied consists of packed column 10 cm in diameter filled with 1 cm in diameter ball to the height of 80 cm. The gas flow rate was held constant at F = 600 ml/s, liquid flow rate (L) was 50 cm 3 /s, pressure (P) was varied from: 350 to 700 mm H 2 O, and the concentration of aqueous NaOH 1M in let absorbent was held constant. The results showed that the percentage of absorbed CO 2 can be enhanced by in creasing pressure. Using column with packing height of 100 cm. gas flow rate of 600 l/s, using absorbeut containing NaOH 1 M with flow rate: 600 ml/s and at pressure of 350 mm H 2 O and temperature of 30 ˚c, the percentage recovery of CO 2 reacked the valued of above: 80%