Fumes emitted from coffee bean roasters contain various chemicals such as aldehydes, pyridine, volatile fatty acids, and ketones. These chemicals have high odor intensities and are sensitive to human breathing organs and eyes. In Taiwan, most of these fumes are not well controlled before venting to the atmosphere. This research attempted to eliminate these odorous and offensive chemicals by chemical scrubbing methods. Sodium hypochlorite oxidation followed by hydrogen peroxide reduction (hypochlorite-peroxide) was investigated first. After that, ozone oxidation followed by hydrogen peroxide reduction (ozone-peroxide) was also tried. In both methods, hydrogen peroxide acted as a reducing agent for the elimination of either residual chlorine or ozone emitted from the oxidation reaction. Experimental results indicated that both methods were effective. An oxidative scrubbing liquid with an initial effective chlorine content of 200 mg/L and a pH of 12, and an reducing scrubbing liquid with an initial hydrogen peroxide concentration of 1% and a pH of 12 could remove an average of 85% of total hydrogen carbons (THC) in the fume gas from a coffee bean roaster. With a dose of 10 ppm ozone in the fume gas to the oxidative scrubbing liquid (water only) followed by an reducing scrubbing liquid with an initial hydrogen peroxide concentration of 0.3% and a pH of 12, an average removal of 80% of the THC could be removed. An odor intensity (expressed by the dilution to threshold ratio) of 9,772 in the original fume could be reduced to as low as 31 by both methods. As indicated by the data from GC/MS (gas chromatography-mass spectrometry) analysis for the hypochlorite-peroxide method, acrolein, vinyl acetate, 2-butanone, and acetone in the roaster fume could almost completely be eliminated. Traces of chlorinated hydrocarbons as potential secondary pollutants were detected in the treated gases from the hypochlorite-peroxide scrubbing system. While by the ozone-peroxide one, satisfactory results were also obtained with no chlorinated hydrocarbons emitted. An economical analysis shows that the ozone-peroxide approach is a practical one for actual control applications.

Organic solvents in varnish can easily cause volatile organic compounds (VOCs) and odorous problems in manufacturing plants of enamel insulated wire. In general, the related process exhaust gases are treated by catalytic incinerators. However, the slight odors in the incinerated exhausts may induce uncomfortable feels to the inhabitants in the vicinity of the plants. Main components of odors are reported to be xylenes and to a lesser extent ketones. This study intended to oxidize the odorous compounds by chemical scrubbing method with either sodium hypochlorite or ozone as an oxidant and hydrogen peroxide as a reducing agent for the elimination of residual chlorine or ozone emitted from the oxidation scrubber. An additional study was the oxidation of aqueous mixed xylenes by sodium hypochlorite. The first part of the study was the chemical oxidation of aqueous xylenes by sodium hypochlorite. Results indicated that more than 95 % of 20 mg/L xylenes could be converted to some oxygenated hydrocarbons with an initial effective chlorine concentration of 180 mg/L at pH 6.5 over a prolonged reaction time of over 120 min. With pH < 3 and a reaction time of 120 min, xylenes could be oxidized to benzene carboxylic acid that precipitated as organic crystalline solids to the reactor bottom. The second part was chemical scrubbing of the odorous gases emitted from the catalytic incinerator. Operation conditions were an effective chlorine concentration of 1,500 mg/L and pH 6.5 for the oxidative scrubbing liquor, and a hydrogen peroxide concentration of 700 mg/L and pH > 12 for the reductive one. Results indicated that on an average, around 59 % of the influent xylenes could be removed, and the scrubbed gas was nearly odorless. 65.0 - 98.5 % of the influent non-aromatic compounds could be removed with trace amounts of chlorinated compounds in the gas were detected. The third one was the treatment of the odorous gases by using ozone as an oxidant and followed by activated carbon adsorption. 18 - 34 mg/m3 of ozone was added to the test gas with initial xylene concentrations of 25 - 55 mg/m3. Results indicated that only around 35 % of the added xylene was removed with ozone contact times of 0.15 - 0.6 min. Although 99.9 % of the residual ozone and odors were removed by the activated carbon, a longer operation time should be tested to verify the performance. Trace amounts of ring cleavage precursors of 2.4-dimethylphenol and ring cleavage products were found in the ozonized gas.

With the increases of environmental awareness and attention by the government and audiences, people begin to prosecute the pollution makers instead of tolerance. This study tried to control an air pollution source from a wallpaper plant for the purpose of attenuating odor prosecutes by residents near the plant. This study investigated chemical scrubbing, ozonation followed by GAC (Granular Activated Carbon) adsorption and biotrickling filtration techniques as control methods for eliminating odorous compounds from a waste gas stream emitted from the wallpaper plant. Scrubbing test results indicate that with an oxidative solution of 800 mg/L residual chlorine at pH 7.0 and a reductive solution of 0.2% hydrogen peroxide at pH = 12, around 90% of the VOCs (volatile organic compounds) in the tested gas could be removed. Odor intensities could be reduced from 2,317 (expressed as dilutions to threshold) to 130. Results also indicate that around 85 % of the carbonyl compounds, 41% of the alkenes and 22% of the alkanes in the waste gas could be eliminated. No removal of aromatic and halo-hydrocarbons was observed. It requires around NT$70 for chemicals to treat 1000 m3 of the gas. Ozonation-GAC adsorption tests indicate that with an ozone dosage of 5 ppm in the waste gas and a gas-ozone contact time of 12 s followed by GAC adsorption, around 95% of the VOCs in the tested gas could be removed. Odor intensities were reduced from 2,317 to <55. Around 94 % of the carbonyl compounds, 79% of the alkanes, 76% of halo-hydrocarbons, 41% of the alkenes and 20% of aromatics in the waste gas could be removed. Around NT$ 15,700 for ozone and GAC is required to treat 1000m3 of the gas. Results from biotrickling filtration tests indicate that with the supplementations of nitrogen and phosphorous nutrients to biofilms attached to wood-chip packings, around 83% of the influent VOCs could be biodegraded. Odor intensities could be reduced from 1,737 to <55. Around 61 % of the carbonyl compounds, 67% of the alkanes, 18% of halo-hydrocarbons and 33% of aromatics in the waste gas could be removed. Around NT$ 13 is required to treat 1000m3 of the gas. For an actual application, it is suggested that a process that a combination of chemical scrubbing and ozonation-GAC adsorption may be a proper solution to the control of the odorous emission from the plant. Biotrickling filtration can be best after verifying the performances of the technique by a pilot test.

Since odor-complaint events have been increased year by year in Taiwan, odor control has become an important issue in the air pollution control field. Thus, this paper attempted to investigate if ¡§ozone scrubbing-activation carbon adsorption¡¨ is feasible for efficiently reducing the odor intensity of vented gas from recycled polypropylene (PP) fusion operations. A pilot scrubber (0.17 m L ¡Ñ0.17 m W ¡Ñ1.2m H, packed with Intalox saddles to a total volume of around 0.018 m3) was used for the feasibility test. Odorous gases vented from the fusing operation kept at 200 ¢J in a temperature-controlled oven were used as the target waste gases. Results indicated that with operation conditions of VOCs (as methane) 10-40 ppm, an ozone concentration of 4.0 ppm in the influent gas, a liquid/gas (L/G) ratio of 0.030 L/m3 in the scrubber, and an empty bed retention time of around 9.7 s in the packed section, around 60% of the VOCs in the influent gas was removed. Most alkenes in the gas were converted into sweet-smell ketones in the ozonated gas. Vented gas from the scrubber was further treated by a granulated activated carbon (GAC) adsorption column with an EBRT of less than 1 s for the gas. An overall VOC removal of around 70% was observed for the full ozonation-GAC process. Only trace amounts of original fume-like and sweet-ketone smells were detected in the treated gases. A test indicated that the overall odor (expressed as the dilution to threshold D/T value) removal was around 70% and the D/T were 733, 309, and 232, respectively, for the influent, ozonation-scrubbing effluent, and GAC effluent. It was estimated that the cost is around NT$ 9.57 for treating 1,000 m3 of the teat gas by the system. Efforts should be made by decreasing the cost by other alternative technologies.

Carbon dioxide (CO₂) capture and sequestration (CCS) at fossil-fueled power plants is a critical technology for CO₂ emissions mitigation during the transition to a sustainable energy system. Post-combustion amine scrubbing is a relatively mature CO₂ capture technology, but barriers to implementation include high capital costs and energy requirements that reduce net power output by 20-30%. Capture energy requirements are typically assumed constant, but work investigates whether flexibly operating amine scrubbing systems in response to electricity market conditions can add value to CO₂ capture facilities while maintaining environmental benefits. Two versatile optimization models have been created to study the electricity system implications of flexible CO₂ capture. One model assesses the value of flexible capture at a single facility in response to volatile electricity prices, while the other represents a full electricity system to study the ability of flexible capture to meet electricity demand and reliability (ancillary) service requirements. Price-responsive flexible CO₂ capture has limited value at market conditions that justify CO₂ capture investments. Solvent storage can add value for price arbitrage by allowing flexible operation without additional CO₂ emissions, but only with favorable capital costs. The primary advantage of flexible CO₂ capture is an increased ability to provide grid reliability services and improve grid resiliency at minimum and maximum electricity demand. Flexibility mitigates capacity shortages because capture energy requirements need not be replaced, and variable capture at low demand helps respond to intermittent renewable generation. / text

Alkaline fuel cells (AFC's) using renewable fuels are a developing technology capable of meeting market niches in standby, standalone and distributed power generation. AFC's generate electricity, heat and water using hydrogen and oxygen as fuels. While AFC's have been known and the principles demonstrated for over sixty years, their use has been restricted primarily to space applications. Recent technological developments have seen the cost of AFC stacks fall considerably; this together with several other advantages over competing fuel cell technology, has rekindled interest in commercial systems. The main deterrent to wide spread commercialisation of AFC systems is susceptibility to carbon dioxide (CO2) in atmospheric air used as the oxygen supply. AFC's require a low cost, low energy, continuous scrubbing device to reduce CO2 in air from approximately 380 parts per million (ppm) atmospheric concentration to below 50 ppm. Current technology to overcome this problem, a solid expendable absorbent called soda lime, is not viable for commercial systems. The project scope included concept generation of a device to remove CO2 from air, the development of a CO2 measurement technique, investigation of chemistry and flow phenomena to determine design relations, and product design and embodiment. The scrubber system conceived specifically for AFC systems uses the temperature swing chemistry of a liquid chemical absorbent, monoethanolamine, and a packed bubble column apparatus to provide intimate gas-liquid interaction. Prototype development proved the Carbon Dioxide Continuous Scrubber (CDOCS) concept and a Patent Cooperation Treaty (PCT) patent was granted, followed by a full American patent. A gas chromatographic measurement technique was developed to measure low ppm concentration CO2 in air, enabling regular monitoring of scrubbed gas. Carbon dioxide was separated from a small sample of scrubbed air by chromatographic columns, and the gases analysed with a thermal conductivity detector. The GC system was capable of measuring to 10 ppm with good resolution and accuracy. Experimental studies were carried out to characterise the flow dynamics and absorption phenomena in the packed bubble column absorber. The relationship between absorption performance and gas-liquid contact time, an important operating parameter for use with AFC's, was theoretically determined and later confirmed by experiment. The regeneration process was studied and the optimal regenerator design determined to be second, smaller packed bubble column. Experiments were conducted to establish design relations for regeneration temperature, flush gas flow rate and the effect of multiple regeneration cycles. A prototype CDOCS system was built to enable experimental characterisation of scrubbing performance as a function of primary design and operating parameters including liquid depth, regenerator operating temperature and solution composition. This resulted in a good understanding of the system, and an optimised experimental run was performed for cost and performance comparison to existing scrubbing technology. The CDOCS was capable of reducing CO2 in air from 380 to 80 ppm for thirty days, providing low cost, low maintenance scrubbing compared to soda lime. The capital cost of the CDOCS is considerably more than for soda lime scrubbers, and the penalty for extended operation is parasitic power consumption by the CDOCS system totalling less than 7% of fuel cell output. It is suggested that a combination of the two technologies be used initially to provide effective, low cost scrubbing for AFC and CDOCS co-development. Future work on the CDOCS project should include reduction of chemical vapour carry over to the fuel cell, followed by integration with an AFC system. This would allow further development, refinement and design for production to reduce capital cost.

Submitted by Stéfany Moreira (stemellra@yahoo.com.br) on 2013-02-25T18:47:05Z No. of bitstreams: 1 DISSERTAÇÃO_AtriçãoMinérioFerro.pdf: 1828689 bytes, checksum: 4b39df4eb1fd16cd896fd105c1755f72 (MD5) / Approved for entry into archive by Neide Nativa (neide@sisbin.ufop.br) on 2013-02-27T15:18:22Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO_AtriçãoMinérioFerro.pdf: 1828689 bytes, checksum: 4b39df4eb1fd16cd896fd105c1755f72 (MD5) / Made available in DSpace on 2013-02-27T15:18:22Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO_AtriçãoMinérioFerro.pdf: 1828689 bytes, checksum: 4b39df4eb1fd16cd896fd105c1755f72 (MD5) Previous issue date: 2012 / A presença de lamas na flotação reversa do minério de ferro é reconhecidamente prejudicial sob vários aspectos. Tradicionalmente, a deslamagem cumpre o papel de remover parte dessa lama. No entanto, dependendo da porosidade e a forma como ela se apresenta em relação aos minerais e a ganga, a deslamagem pode não ser suficiente para maximizar os resultados da concentração. A retirada das lamas pode ser mais eficiente adotando-se o processo de atrição seguida de deslamagem em meio disperso, no caso dessas lamas estarem aderidas as cavidades dos minerais ou adsorvidas em sua superfície. O atrito entre grãos maiores e mais duros uns contra os outros visando a limpeza superficial pode ser tanto melhor quanto for o ajuste de suas variáveis do processo. A atrição está inserida em fluxogramas de beneficiamento de fosfato e areia industrial. Existem pesquisas quanto sua aplicação para o pré-concentrado de zircão e minério de ferro. Porém, pouco se conhece sobre a influência das variáveis desse processo para o minério de ferro. Esse trabalho teve como objetivo investigar as possibilidades de aumento da recuperação metalúrgica e seletividade na flotação reversa do minério de ferro hematítico, beneficiado na instalação de tratamento de minério de Vargem Grande com a adoção da etapa de atrição da polpa de alimentação, seguida de deslamagem em meio disperso. Utilizou-se o planejamento e análise fatorial para identificação das variáveis significativas da atrição na recuperação metalúrgica e índice de seletividade na flotação reversa do minério de ferro, proveniente das Minas do Tamanduá e Capitão do Mato, Quadrilátero Ferrífero. A partir da realização de testes em escala de bancada, concluiu-se que a velocidade de rotação do impelidor da célula de atrição é o principal efeito da atrição com relação à recuperação metalúrgica na flotação, independente do percentual de sólidos na polpa e do tempo de atrição. As lamas obtidas após a atrição no processo de deslamagem eram compostas essencialmente por hematitas e o concentrado da flotação apresentou baixa porosidade. ____________________________________________________________________________________________________ / ABSTRACT: The presence of sludge in iron ore reverse flotation is known to be harmful in many ways. Traditionally, desliming fulfills the role of removing some of this sludge. However, depending on the porosity and how it is presented on minerals and gangue, desliming may not be sufficient to maximize the concentration results. The sludge can be removed more efficiently by adopting the scrubbing then dispersed through the desliming. The friction between larger and harder grains in each other in order to clean surface can be better as for the adjustment of their process variables. The scrubbing is embedded in flowcharts beneficiation of phosphate and silica sand. There is research and its application to pre-concentrate of zircon and iron ore. However, little is known about the influence of the iron ore process variables. This study aimed to investigate the possibilities of increasing the metallurgical recovery and selectivity in reverse flotation of hematite iron ore received at the Instalação de Tratamento de Vargem Grande by adopting the scrubbing of the pulp supply, then in the midst of desliming dispersed. The experimental planning was used for identification of significant variables of attrition in the metallurgical recovery and selectivity index in reverse flotation of iron ore from the Mina Capitão do Mato e Tamanduá, both in Quadrilátero Ferrífero. The testing bench scale, it was concluded that the rotational speed of the impeller scrubbing cell is the major effect of metallurgical recovery at flotation, regardless of the percentage of solids in the pulp and the time scrubbing. The sludge obtained in desliming after the scrubbing were essentially composed of hematite and the flotation concentrate showed low porosity.

O objetivo deste trabalho foi investigar, sob o enfoque da modelagem matemática, a operação de escrubagem da bauxita proveniente da jazida Miltônia 3, da Mina de Bauxita de Paragominas-PA, com vistas a fornecer parâmetros para previsão de seu desempenho e otimização. Para isso, foi realizada uma campanha de experimentos de escrubagem, em um tambor desagregador de laboratório, baseada em planejamento fatorial. Os parâmetros operacionais avaliados foram os seguintes: grau de enchimento, tempo de residência da polpa e velocidade de rotação. A variável de resposta selecionada foi a quantidade de finos (partículas menores que 0,037 mm) no produto desagregado. O programa de experimentos permitiu a análise da influência de cada variável operacional selecionada na desagregação da bauxita. De acordo com os resultados obtidos, o parâmetro operacional que produziu o efeito mais significativo na variável de resposta foi o grau de enchimento. O modelo desenvolvido foi validado através da comparação entre os valores obtidos em ensaios de escrubagem em uma unidade piloto e aqueles previstos pelo modelo. Os valores da quantidade de finos, no produto desagregado, previstos pelo modelo apresentaram uma excelente aproximação com os dados experimentais da operação em escala piloto. / The aim of this study was to investigate and model the bauxite scrubbing of bauxite samples from Miltonia 3, a Vale operation at Pará state, Brazil. The experimental program included the design of a standard laboratory test, from which parameters were derived for predicting the operation of a scrubber in steady state conditions. Three main variables were selected for the laboratory experimental program using the factorial design technique. These were load fraction, residence time and rotation speed. The amount of fines was determined through screening both feed and product of the scrubbing test. The former was considered as a material characteristic while the second was the dependent variable, i.e. the result of the scrubbing process. An empirical model was developed according to which the load fraction was found the most important variable to the scrubbing process. Residence time was also included in the model due to its importance in designing scrubbers for industrial plants. To validate the model a comprehensive pilot plant program was carried out with the same bauxite sample from Miltonia 3 deposit used in the laboratory investigations. The comparison between experimental data and model calculated values indicated a good agreement, as most values were within ±10% deviation range.

No description available.

No description available.