Gas Treatment Process Research Articles

On the design, development and operation of an energy efficient CO2 removal for the oxidative coupling of methane in a miniplant scale

The catalytic oxidative coupling of methane to higher hydrocarbons (OCM) as an alternative route to ethylene or liquid fuels obtained much attention. Besides the intensive research and novel developments in the catalyst field are a number of investigations conducted with reaction and separation engineering aspects at the TU Berlin. The aim of this research is the demonstration of the technical feasibility of the OCM process, including product recovery in a miniplant scale. In this article the gas treatment of the reaction product gas is discussed as a key part of the production chain from raw material to the product. In the OCM process the CO2 is treated as an unwanted by-product or waste. Nevertheless, the energy and the costs requirements for the whole OCM process are crucial for industrial applicability and must be kept as low as possible to operate economically. Therefore different separation methods are examined and several process alternatives are investigated. In this article the energy saving of a hybrid separation process based on a membrane-absorption process for the CO2 capture of the OCM process is presented and proved experimentally in miniplant scale. In a case study of the oxidative coupling of methane (OCM) process the development of an integrated gas treatment process for CO2 capture in the miniplant scale is presented and experimental results are discussed.

Degradation studies of amines and alkanolamines during sour gas treatment process

Aqueous solutions of alkanolamines are widely used for the removal of acidic gases such as H 2S, CO 2, COS and CS 2 in the sour gas treatment process. In spite of the resistance of alkanolamines to chemical breakdown, plant and laboratory reports indicate that, on prolonged use, alkanolamines may be transformed into undesirable products from which the amines are not easily recovered. This phenomenon, commonly referred to as 'amine degradation', not only leads to amine losses, but may also contribute to operational problems such as foaming, corrosion, high solution viscosity and fouling as a result of decreasing the plant life. Amine based gas purification plants having absorption and stripping system, solvents are degraded at these two units mainly by oxidative degradation at absorber condition and thermal degradation at stripper condition. Identification of amine degradation routes, remediation of degradation, types of degradation products and studies on degradation reaction mechanism becomes essential for successful plant operation. Gas chromatography-mass spectrometry (GC-MS), ion chromatograph (IC), high performance liquid chromatography (HPLC), nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared absorption spectrometry (FT-IR) are extensively used to identify the various degradation products. A comprehensive review of the latest research activities on alkanolamines degradation, best method for identification, various properties of degradation products and their classification is presented in this paper. This study would help to develop better understanding of amine degradation. © 2011 Academic Journals.

Multicriterial analysis of post-combustion carbon dioxide capture using alkanolamines

The most promising technology for carbon dioxide capture from coal and natural gas fired power plants at large scale applications is based on post-combustion method using gas–liquid absorption. The paper evaluates carbon dioxide absorption, at low partial pressures, from flue gases by post-combustion capture using aqueous solutions of various alkanolamines: monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), 2-amino-2methyl-1-propanol (AMP) and their corresponding mixtures. At a constant capture rate of about 90%, the performance of these aqueous alkanolamine solutions is compared in terms of solvent loading and overall energy consumption.The objective of the present paper is to assess using a multicriterial analysis (e.g. energy consumption, environmental and operational criteria) the carbon dioxide capture using the above alkanolamines and to investigate the effect of using alkanolamine mixtures as solvent on the gas treatment process. The evaluation was based on Aspen Plus® simulations. As illustrative example, the case of an IGCC coal-fired power plant generating 375–450MWe net electricity with and without post-combustion capture was presented in details.

Microwave catalytic NOx and SO2 removal using FeCu/zeolite as catalyst

Non-thermal plasma technology is a promising process for flue gas treatment. Microwave catalytic NOx and SO2 removal simultaneously has been investigated using FeCu/zeolite as catalyst. The experimental results showed that a microwave reactor with FeCu/zeolite only could be used to microwave catalytic oxidative 91.7% NOx to nitrates and 79.6% SO2 to sulfate; the reaction efficiencies of microwave catalytic reduction of NOx and SO2 in a microwave reactor with FeCu/zeolite and ammonium bicarbonate (NH4HCO3) as a reducing agent could be up to 95.8% and 93.4% respectively. Microwave irradiation accentuates catalytic reduction of SO2 and NOx treatment, and microwave addition can increases SO2 removal efficiency from 14.5% to 18.7%, and NOx removal efficiency from 13.4% to 18.7%, separately. FeCu/zeolite catalyst was characterized by X-ray diffraction (XRD), X-ray photoelectron spectrum analysis (XPS), scanning electron microscopy (SEM) and the Brunauer Emmett Teller (BET) method. Microwave catalytic NOx and SO2 removal follows Langmuir–Hinshelwood (L–H) kinetics.

Biotechniques for air pollution control (biotechniques 2009)

‘‘Biotechniques 2009’’ was the 3rd edition of the International Congress on Biotechniques for Air Pollution Control. This congress is organised every 2 years, with a steadily increasing number of delegates since its first edition. Although the legislation in most countries is more developed for wastewater and water pollution in general, concern and regulation related to air pollution is nowadays also becoming more significant. The first and second congress of this series were organised at the Congress and Exhibition Centre of La Coruna (Spain) in October 2005 and October 2007, respectively, and were already great successes, with the presence of around one hundred delegates from more than 20 countries from Europe, North and South America, Asia, Australia, Middle-East and North Africa. Both engineering and more basic aspects were addressed by experts working on air pollution control at research institutes, universities and industries. Data were presented from both laboratory-scale and full-scale experiences in the biological treatment of polluted air from various sources, including industry and agriculture. Many different bioreactor configurations and operating strategies were discussed, aimed at improving waste gas treatment processes. The 3rd Congress was held at UNESCO-IHE in Delft (the Netherlands) on September 28–3

Electrochemical and corrosion behavior of carbon steel in SULFIRAN ® process

Corrosion behavior of carbon steel was evaluated in Fe-EDTA solution designed to be used in acid gas treatment process (SULFIRAN ® plant) in the temperature range between 35 °C and 45 °C. Electrochemical techniques, i.e. polarization curves and electrochemical impedance spectroscopy (EIS) were applied for laboratory evaluations. Linear polarization resistance (LPR) and weight loss techniques were used to determine the corrosion rate for pilot tests. In addition, several surface analysis techniques such as XRD, XRF, SEM and optical microscopy were employed to determine the corrosion morphology. Metallurgical and SEM investigations of the carbon steel corrosion showed corrosion-induced damages in SULFIRAN ® process. The corrosion demonstrated in the forms of severe uniform corrosion, wide shallow pits formation, under deposit corrosion, hydrogen micro-void formation, and hydrogen induced disbonding between the interfaces of the inclusion (MnS) and metal matrix. The corrosion rate of carbon steel alloy is predicted to be very high (>200 mils per year or mpy) in this process.

Potentials of pervaporation to assist VOCs’ recovery by liquid absorption

Gas treatment by liquid absorption is a well-known process to remove volatile organic compounds (VOCs) from industrial waste gases. Usually the liquid is an organic solvent of high boiling point; however, after VOCs’ absorption it must be regenerated for the possible reuse and this step is classically achieved by heating the liquid. The paper presents the work directed to investigate an alternative regeneration step based on a liquid–vapour membrane separation, i.e. pervaporation. Because most of the energy required in pervaporation processes is consumed to remove the minor component from the initial mixture by selective permeation through the membrane, one can expect a significant energy cut in the operational costs linked to the regeneration of the liquid if the pervaporation step can substitute the heating one. The results reported here show that the technological possibility to use pervaporation is first governed by the stability of the membrane in the absorption liquid. The viability of the overall process is actually controlled by the mutual affinity between the VOCs, the solvent phase and the polymeric material. As a matter of fact, whereas VOCs have to exhibit strong affinities to both the solvent and the membrane material, the polymer has to be well resistant and even repellent to the solvent to avoid the possible sorption in the membrane that would drastically depress the pervaporation efficiency. In other words the membrane transport properties must be specific for the VOCs. This goal was reached following several experimental approaches, going from membrane modifications to the selection of suitable heavy protic solvents. Hence it has been shown for the case of dichloromethane (DCM) that low molecular weights polyalcohols (e.g. glycols) appeared to be suitable media to allow in particular the specific transport of DCM. On the other hand, polydimethylsiloxane (PDMS) based membranes were selected for their stability in these polyglycols and for their marked affinity for DCM. The simulation of the hybrid gas treatment process at pilot-scale was also achieved by a simple model relying on experimental data for both vapour liquid equilibria and permeation flux. A simple comparison of the energy needed to regenerate the heavy solvent by each possible step has also been made.

Light scattering by small particles

On-line turbidimeters are currently used for monitoring particle concentration in water and gas treatment processes. For small particle concentration, the intensity of scattered light is a linear function of the particle concentration, as long as a number of other parameters are kept constant: the refractive indexes of the particles and the surrounding medium, size, measuring angle and wavelength of the light. An international standard has been created in order to define the characteristics of the turbidimeters and the calibration suspension. The effects of the parameters are described and quantified. The special aspects of the measurement of very low turbidity values in water are treated: the zero value of water and the definition of the calibration conditions. A measuring method is presented which grants long-term stability without recalibration. The first industrial application for on-line turbidimeters was the monitoring of beer filtration in breweries, which started about 50 years ago. In the meantime, turbidimeters have been used in very diversified fields such as dust measurements in stacks, visibility in road tunnels and filtration control in the chemical industry. However, their main application today is the monitoring of drinking water treatment plants: control of the flocculation process by measuring the variations in the raw water (rivers, lakes, ground-water, sources) and the resulting properties, sand filtration survey and final quality control.

Environmental release and mass flux partitioning of PCDD/Fs during normal and transient operation of full scale waste to energy plants

The paper reports on global release and mass partitioning in the flux of residues of PCDD/Fs, evaluated with dedicated field campaigns at a municipal solid waste incineration plant during normal and transient operation. Results are compared with those obtained in other installations equipped with furnaces, energy recovery options and flue gas treatment technologies representative of most of the European incineration plants currently in operation. Levels of the pollutants of interest were determined in all the solid, liquid and gaseous residues produced by every single facility, and the results analysed in terms of the effects arising from the fed waste and the configuration of the plant. PCDD/Fs total release between 1.5 and 45 microg I-TEQ per ton of burned waste was evaluated, with lower values resulting from the adoption of catalytic conversion process for flue gas treatment. Most of the mass flux emitted is associated with solid residues deriving from activated carbon PCCD/F dry removal options, with significant contributions also from fly ash produced by particulate removal devices located immediately downstream the boiler and from scrubber blowdowns treatment sludge. During transient operating conditions the dioxin total release may increase by 50% with comparison to steady-state functioning.

Measurement and thermodynamic modeling of the phase equilibrium of aqueous 2-amino-2-methyl-1-propanol solutions

The accurate design of acid gas treatment processes requires the knowledge of vapor–liquid equilibrium of acid gas aqueous alkanolamine systems, and, consequently, that of the binary systems involved. This study presents: (a) vapor pressure measurements of pure 2-amino-2-methyl-1-propanol (AMP), and (b) isobaric vapor–liquid equilibrium (VLE) measurements at 66.7, 80.0 and 101.3 kPa of aqueous AMP solutions. The data measured in this work along with some excess enthalpy data, which were taken from the literature, were used for the thermodynamic modeling of the water/AMP binary system.

Liquid Holdup and Pressure Drop Determination in Structured Packing with CFD Simulations

AbstractIt is discussed how Computational Fluid Dynamics (CFD) can be used for hydrodynamics calculations within structured packings. Three dimensional (3D) simulations, in which the influence of mesh size and turbulence models were tested, have been carried out for dry pressure drop determination. Two dimensional (2D) Volume of Fluid gas‐liquid flow simulations have been used for liquid holdup determination. Numerical results are compared to tomographic liquid holdup measurements. Then, a comparison with data from a gas treatment pilot plant shows that wet pressure drop can be predicted by combining these two types of information (dry pressure drop and liquid holdup).

Novel Waste Gas Treatment Process, Able to Cope with Fluctuating Loads, Poorly Water Soluble VOCs and Biomass Accumulation

Chemie Ingenieur TechnikVolume 76, Issue 9 p. 1235-1236 Vortrag Novel Waste Gas Treatment Process, Able to Cope with Fluctuating Loads, Poorly Water Soluble VOCs and Biomass Accumulation M. Studer, M. Studer studer@ipe.mavt.ethz.ch Search for more papers by this authorP. R. von Rohr Prof. Dr. , P. R. von Rohr Prof. Dr. ETH Zürich, Institute of Process Engineering, Sonneggstrasse 3, CH-8092 ZürichSearch for more papers by this author M. Studer, M. Studer studer@ipe.mavt.ethz.ch Search for more papers by this authorP. R. von Rohr Prof. Dr. , P. R. von Rohr Prof. Dr. ETH Zürich, Institute of Process Engineering, Sonneggstrasse 3, CH-8092 ZürichSearch for more papers by this author First published: 01 October 2004 https://doi.org/10.1002/cite.200490239AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume76, Issue9September, 2004Pages 1235-1236 RelatedInformation

Characteristics and desulfurization-regeneration properties of sol–gel-derived copper oxide on alumina sorbents

Mesoporous alumina supported copper oxide granular sorbents were synthesized by the sol–gel method using different raw materials. The copper loading in the sorbents was varied from 5 to 20-wt.% CuO. The effect of the copper content on the surface area of the sorbents and dispersion of the active species was studied. Samples with <14 wt.% CuO did not show any crystalline copper containing phase. For CuO/γ-Al 2O 3 with 8 wt.% CuO, most of the copper species consisted of Cu 2+ ions and no sulfide species were found. The optimum temperature for operation of the sol–gel derived sorbents was 400 °C at which more than 85% of the initial sulfation capacity is maintained up to three sulfation-regeneration cycles. The pore structure, crush strength, sulfation capacity and regeneration properties of the sol–gel derived sorbents were studied and compared with those of the similar commercial sorbents used in pilot scale fluidized-bed copper oxide process for flue gas treatment. The sol–gel-derived mesoporous copper oxide coated alumina granules, with a surface area of 220–248 m 2/g, pore volume of 0.46–0.48 cm 3/g, and pore diameter of 6.7–8.8 nm, offer higher surface area, more uniform pore size distribution, and higher crush strength than the commercially available sorbents for the copper oxide process. For similar copper oxide content the sol–gel derived sorbents showed superior sulfation and regeneration properties than the commercial sorbents, in terms of sulfation capacity, regenerability, and SO 2 concentration in the regenerated effluent.

Hydrogen sulphide removal by activated sludge diffusion

Odours from wastewater treatment plants comprise a mixture of various gases, of which hydrogen sulphide (H2S) is the main constituent. Microorganisms commonly found in wastewater can degrade sulphurous compounds. Therefore, the use of activated sludge (AS) for odour control offers an alternative to traditional waste gas treatment processes, such as biofilters, bioscrubbers and biotrickling filters, both in practical terms (use of existing facilities) and economically (minimal capital cost). The performance of AS diffusion as a bioscrubber for removing H2S at concentrations at 25, 75 and 150 ppmv was evaluated. Pilot-scale trials were undertaken using parallel 60-L aeration tanks and 20-L clarifier reactors at the Bedford Sewage Treatment Works, Carington, UK. Olfactometry measurements were also carried out to determine whether there was any increase in odour concentration owing to H2S diffusion. Hydrogen sulphide removal rates of 100% were obtained, with no noticeable increase in odour concentration throughout the trials as measured by olfactometry. Odour concentration was highest at the beginning of the trials and lowest during the high H2S dosing period, with similar values being obtained for test and control. It was concluded that AS diffusion is an effective bioscrubber for the removal of H2S odour.

ごみ焼却施設における有機ハロゲン化合物のモニタリングについて(その他の環境関連技術(6),その他の環境関連技術)

Monitoring methods of dioxin or dioxin surrogate compounds for management of the emission in MSW (Municipal Solid Waste) incineration plant have been widely developed. In this study, OHCs(Organic Halogenated Compounds) ,which have been studied a possibility of dioxin surrogate compounds, were selected for the index of the emission. Field study was conducted at a MSW incineration plant. OHC concentrations and behavior in gas treatment process at a MSW incineration plant were investigated. OHC concentrations were reduced during gas treatment process, and the behavior showed high removal efficiency in ACR (Activated Carbon Reactor). Moreover the OHC behavior was similar to that of aromatic compounds (DXN, CBz, and CPh) in ACR.

Chemical absorption models for coke-oven gas treatment process : Shen, J. Jishu Yu Xunlian, 2002, 27, (1), 1–10. (In Chinese)

Chemical absorption models for coke-oven gas treatment process : Shen, J. Jishu Yu Xunlian, 2002, 27, (1), 1–10. (In Chinese)

Activated sludge biotreatment of sulphurous waste emissions

Odours from wastewater treatment plants are comprised of a mixture of various gases, of which hydrogen sulphide (H2S) is the main constituent. Sulphurous compounds can be degraded by microorganisms commonly found in wastewater. The use of activated sludge (AS) diffusion as a dual-role system, for the treatment of wastewater and for odour control, offers an alternative to traditional sulphurous waste gas treatment processes, such as biofilters, bioscrubbers and biotrickling filters, both in practical terms (use of existing facilities) and economically (minimal capital cost). Activated sludge diffusion avoids the common problems associated with these processes such as media plugging, excess biomass accumulation, gas short-circuiting, and moisture control and maintaining the correct biofilm thickness. The design issues to be considered when using AS diffusion for odour abatement, comprise odourous air pre-treatment,blowers and diffuser types, corrosion protection and increase in odour emission intensity. Nitrification inhibition depends on the composition and acclimation of the biomass, the concentration of H2S and other components of the wastewater. Hydrogen sulphide removal rates of >98% were consistently achieved for loads of 3–34 mg H2S/g MLSS/h, in two case studies, which also showed that sludge type has an impact on the ability of the sludge to degrade H2S. Wastewater process performance measured as five-day biological oxygen demand (BOD5), chemical oxygen demand (COD) and effluent suspended solids removal was not affected by H2S diffusionat 5 ppm. A change in the microorganism population dynamics of anactivated sludge was observed when it was exposed to H2S for aperiod of more than 21 days.

Mechanism of NO x removal by electron beam process in the presence of scavengers

In this study NO x removal efficiency, with/without SO 2 in electron beam flue gas treatment process, was evaluated in the presence of different additives: ammonia, water, and alcohol. It was found that NO x removal efficiency increased by 20% and in the presence of alcohol, more than 70% NO x was oxidized/reduced at 6 kGy for the initial concentration of 500 ppm NO. Humidity and ammonia addition increased the NO x removal efficiency but not more than 10%. Organic products and inorganic products were analyzed by a GC-MS and ion chromatography, respectively. The focus of this paper is on the mechanism that accounts for the increased efficiency in NO x removal.

Flue gas treatment by activated carbon obtained from oil-fired fly ash

The treatment of the solid particulates derived from the combustion of heavy oils (that is, oil-fired fly ash) with acidic solutions (HCl and HF) followed by activation at 900 °C with CO 2 and then with O 2 (1%) in N 2 at 800 °C, produces activated carbon having high surface area values (measured both by N 2 adsorption at 77 K and by CO 2 adsorption at 273 K) and surface basic characteristics. This carbon appears to be suitable for SO 2 and NO X adsorption and hence for industrial flue gas treatment processes. By submitting the activated carbon thus obtained to some adsorption/desorption cycles of gaseous mixtures having a similar composition to that of flue gases, its general characteristics (surface areas, sorbent properties etc.) change as expected of a typical activated carbon. Based on the results obtained, these particulate materials, produced in large amounts by heavy oil combustion, are assumed to be fully exploitable for flue gas treatment.

Nutrient Stimulation of Sulfolane Biodegradation in a Contaminated Soil from a Sour Natural Gas Plant and in a Pristine Soil

Natural gas in western Canada can contain up to 35% H2S. The Sulfinol® process for sour gas treatment makes use of sulfolane and an amine to remove H2S and other sour components from natural gas. Sulfolane has leached into groundwaters at sour gas treatment plant sites, and poses a risk for off-site contamination. Sulfolane biodegradation was monitored in shake-flask cultures and air-sparged microcosms inoculated with uncontaminated topsoil or with sulfolane-contaminated soil obtained near a Sulfinol process building at a sour gas treatment facility in western Canada. For both soils, supplementation with a source of fixed nitrogen stimulated sulfolane biodegradation. Topsoil cultures and microcosms were only slightly affected by the addition of phosphate. Contaminated soil microcosms and cultures were stimulated by phosphate addition, but not to the same degree as by the addition of nitrogen. For these cultures and microcosms, amendment with both fixed nitrogen and phosphate produced an additive effect. It was possible to predict the nutrient requirements of air-sparged microcosms inoculated with each soil type using shake-flask cultures. Shake-flask cultures require less time and effort and fewer materials than the more complex air-sparged soil microcosms, and will be useful for large-scale experiments to predict the nutrient supplements required for bioremediation of sulfolane-contaminated sites.