Gaswaschanlagen für saure und basische Abgase unter Berücksichtigung der neuen TA-Luft

Gas scrubbing plants for acid and caustic exhaust gases with consideration of the new TA-Luft . When designing gas scrubbing plants for acid and caustic exhaust gases from manufacturing plants of the chemical and pharmaceutical industry it is important to pay special attention to the aerosol formation which occurs in the exhaust gas systems and absorbers if the emission values should remain under the determined limit values stated in the Technical Instructions for air-pollution control (TA-Luft). The present study explains under what conditions aerosols can occur, how its formation can be prevented, and which gas scrubbers are appropriate for a combined gas-/aerosol separation. A comparison between two exhaust air scrubbing plants of several stages shows that a gas scrubbing plant for an exhaust air pick-up system with separation of the acid and caustic components as well as with source exhaust air pick-up of the highly charged gas flows is considerably more favourable with respect to price than the alternative scrubbing plant for an integrated exhaust air system in which large quantities of fine salt aerosols occur and have to be separated with high energy consumption.     

Assessment of postcombustion carbon capture technologies for power generation

A significant proportion of power generation stems from coal-combustion processes and accordingly represents one of the largest point sources of CO₂ emissions worldwide. Coal power plants are major assets with large infrastructure and engineering units and an operating life span of up to 50 years. Hence, any process design modification to reduce greenhouse gas emissions may require significant investment. One of the best options to utilize existing infrastructure is to retrofit the power station fleet by adding a separation process to the flue gas, a practice known as postcombustion capture (PCC). This review examines the recent PCC development and provides a summary and assessment of the state of play in this area and its potential applicability to the power generation industry. The major players including the various institutes, government, and industry consortia are identified along with flue gas PCC demonstration scale plants. Of the PCC technologies reviewed, amine-based absorption is preeminent, being both the most mature and able to be adapted immediately, to the appropriate scale, for power station flue gas with minimal technical risk. Indeed, current commercial applications serve niches in the merchant CO₂ market, while a substantial number of smaller scale test facilities are reported in the literature with actual CO₂ capture motivated demonstrations now commencing. Hybrid membrane/absorption systems, also known as membrane contactors, offer the potential for the lowest energy requirements, possibly 10% of current direct scrubbers but are at an early stage of development. Other methods being actively pursued as R&D projects include solid absorbents, solid adsorbents, gas membrane separators, and cryogenic separation. The variety and different maturities of these competing technologies make technical comparison largely subjective, but useful insights could be gained through the development and application of econometric techniques such as ‘real options’ within this context. Despite these limitations, it is clear from this review that amine scrubbing is likely to be adapted first into the existing power station fleet, while less mature technologies will grow and become integrated with the development of future power stations.     

Assessment of postcombustion carbon capture technologies for power generation

A significant proportion of power generation stems from coal-combustion processes and accordingly represents one of the largest point sources of CO₂ emissions worldwide. Coal power plants are major assets with large infrastructure and engineering units and an operating life span of up to 50 years. Hence, any process design modification to reduce greenhouse gas emissions may require significant investment. One of the best options to utilize existing infrastructure is to retrofit the power station fleet by adding a separation process to the flue gas, a practice known as postcombustion capture (PCC). This review examines the recent PCC development and provides a summary and assessment of the state of play in this area and its potential applicability to the power generation industry. The major players including the various institutes, government, and industry consortia are identified along with flue gas PCC demonstration scale plants. Of the PCC technologies reviewed, amine-based absorption is preeminent, being both the most mature and able to be adapted immediately, to the appropriate scale, for power station flue gas with minimal technical risk. Indeed, current commercial applications serve niches in the merchant CO₂ market, while a substantial number of smaller scale test facilities are reported in the literature with actual CO₂ capture motivated demonstrations now commencing. Hybrid membrane/absorption systems, also known as membrane contactors, offer the potential for the lowest energy requirements, possibly 10% of current direct scrubbers but are at an early stage of development. Other methods being actively pursued as R&;D projects include solid absorbents, solid adsorbents, gas membrane separators, and cryogenic separation. The variety and different maturities of these competing technologies make technical comparison largely subjective, but useful insights could be gained through the development and application of econometric techniques such as ‘real options’ within this context. Despite these limitations, it is clear from this review that amine scrubbing is likely to be adapted first into the existing power station fleet, while less mature technologies will grow and become integrated with the development of future power stations.     

Studies on the hydrolysis of urea for production of ammonia and modeling for flow characterization in presence of stirring in a batch reactor using computational fluid dynamics

Ammonia is a highly volatile noxious material with adverse physiological effects, which becomes intolerable even at very low concentrations and presents substantial environmental and operating hazards and risk. But ammonia has long been known to be useful in the treatment of flue gases from the fossil fuel combustion process, such as in industrial furnaces, incinerators and coal-fired electric power generating plants. The present study is concerned with the methods and means to safely produce relatively small amount (i.e., up to 50 kg/hour) of ammonia. Current study involves experimental investigation for hydrolysis of urea for production of ammonia in a batch reactor at different temperature ranging from 110 °C to 180 °C against different initial feed concentration (10, 20, and 30 wt%) with different stirring speed ranging from 400 rpm to 1,400 rpm. Three-dimensional geometry and meshing of reactor is created in Gambit, a preprocessor of the commercial software, Fluent, for hydrodynamic study.     

CHEMICAL AND BIOCHEMICAL PROCESSES FOR NOx CONTROL FROM COMBUSTION OFF-GASES

Nitrogen oxides (NO_x) are major air pollutants as they have adverse effects on health and the environment. Various types of combustion equipment, including biosolids incinerators, are the sources of NO_x emissions in the atmosphere. Various source control measures in the form of the use of low NO_x burners and burner staging techniques, for example, are commonly practiced by the generators. Treatment processes such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are also widely used, especially by power plants. Newer processes involving chemical scrubbing of the flue gas have been under development for the past two decades and are being gradually introduced in full-scale commercial operation. This article provides a comprehensive review of recently developed chemical and biochemical processes for NO_x control. Equations for the reaction rates, scrubber sizes, and chemical requirements are also presented.     

添加剂对水合物法回收烟气中二氧化碳影响的研究进展

阐述了目前基于添加剂环境下水合物法分离烟气中CO2的研究进展,主要对烟气水合物热力学、动力学、分离效果3个方面的研究状况进行了总结。重点对当前应用于烟气体系研究较多的几类添加剂——四正丁基溴化铵(TBAB)、四氢呋喃(THF)、环戊烷(CP)的性质、原理、优势及不足进行了介绍和对比,对一级水合物法处理烟气的研究现状进行了分析和评价,并预测了有效提高水合物法分离效果的可行方法。     

The operation of rotary kilns with boiler-utilizers and electric filters

Summary Cellular heat exchangers built into the furnace enabled the specific fuel consumption to be reduced and the output of the rotary furnace to be increased, but there was an accompanying increase in dust removal.Boiler-utilizers are an effective means of reducing the temperature of flue gases and of increasing the thermal efficiency of the furnace. The wear of the boiler pipes is very low.Experience with boiler-utilizers showed that it is possible to operate them normally even when the flue gases contain a lot of dust.To obtain highly effective and steady working conditions in existing and newly erected electric filters, it is necessary for the Magnesit plant to investigate the composition and physical parameters of the flue gases and the properties of the magnesite dust, and to develop an optimum working cycle for the electric filters.     

GMC高温脉喷袋除尘器及其应用介绍

立窑烟气具有烟气量、烟气温度和湿含量波动范围大,露点温度高,烟气中粉尘的颗粒较细及碱含量高等特性,必须选用高效的电除尘器或袋除尘器,才能达到新标准GB4915-2004要求的排放浓度,其中袋除尘器更具优越性和应用性。合肥水泥研究设计院开发的GMC高温脉喷袋除尘器除尘效率高,烟气排放浓度(标况下)低于50mg/m3,还能有效去除SO2,NOX和CO等有害气体,是立窑烟气治理的有效设备。     

A Mathematical Model to Compare the Efficiency of Cyclones

Tangential cyclones modified to form spiral cyclones are very efficient in separating solid particles from dust laden gases. They offer a lower gas pressure drop and higher particle separation efficiency when compared to basic tangential cyclones. Their high performance is believed to be related to their special structure. A mathematical model is introduced to explain why a spiral cyclone is more efficient than a tangential one. An experimental apparatus is designed to compare both the performances of spiral and tangential cyclones and to check the effectiveness of the model equations. The experimental data were found to be consistent with the model predictions.     

The effect of fly ash on fluid dynamics of CO2 scrubber in coal-fired power plant

Uncaptured fly ash and/or suspended solids from wet flue gas desulfurization (WFGD) scrubbing solutions are one of several factors that will influence the performance and robustness of carbon dioxide capture systems in coal-fired power plants which will be installed prior to the exhaust stack. In this study, a 100 mm ID packed column scrubber was tested with different concentrations of ash in various chemical solutions to evaluate the influence of solids on the fluid dynamics of the packing material. Data reported here are collected from three solutions including water, 30 wt% MEA (monoethanolamine), and 20 wt% potassium carbonate. The packing selected for this study was a 16 mm polypropylene pall rings. Compressed air was used to simulate flue gas at near ambient temperature and pressure.     

Fortschritte bei der Abscheidung von Stäuben im Elektrofilter unter Berücksichtigung der Schadgas-Adsorption

Progress in dust collection by electrostatic precipitators with due attention to adsorption of noxious gases . It is shown on the basis of the present state of the art that the stipulations of the pollution control legislation for large boilers can be met by electrostatic precipitators and that fine dust and heavy metals are collected to a sufficiently high degree. Recent developments are dealt with which bring about a fundamental improvement of the collection in the precipitator. Noxious gases have to be separated together with the dust to an ever-increasing extent. With dry processes, fluidized beds are arranged upstream of the electrostatic precipitator for the adsorption of, for instance, HCl, HF, and SO₂. In these cases the dusts will be highly concentrated and of varying chemical composition. Dry gas cleaning in the expanded, circulating fluidized bed downstream of refuse incineration plants and defluorination of waste gases from aluminium electrolysis are considered as examples. The separation of dust under difficult conditions is then dealt with.     

CHEMICAL AND BIOCHEMICAL PROCESSES FOR NOx CONTROL FROM COMBUSTION OFF-GASES

Nitrogen oxides (NO_x) are major air pollutants as they have adverse effects on health and the environment. Various types of combustion equipment, including biosolids incinerators, are the sources of NO_x emissions in the atmosphere. Various source control measures in the form of the use of low NO_x burners and burner staging techniques, for example, are commonly practiced by the generators. Treatment processes such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are also widely used, especially by power plants. Newer processes involving chemical scrubbing of the flue gas have been under development for the past two decades and are being gradually introduced in full-scale commercial operation. This article provides a comprehensive review of recently developed chemical and biochemical processes for NO_x control. Equations for the reaction rates, scrubber sizes, and chemical requirements are also presented.     

祥光铜业废水处理与烟气超低排放技术的发展历程

介绍了祥光铜业从建设初期至今废水处理与烟气超低排放技术的发展过程.通过对全厂水资源的统一调配,对生产废水循环利用和梯度利用,最终实现了生产废水的资源化和减量化.在烟气治理方面,遵循分而治之的思路,根据各工序产出的烟气性质不同,对烟气处理系统不断优化,采用布袋除尘、高温陶瓷膜除尘、湿法洗涤除尘、高浓度SO2制酸、钠碱法脱...     

Development of New Ceramic Materials for High-Temperature Filters

The technology for fabrication of ceramic cells of high-temperature filters, designed for simultaneous treatment of industrial flue gases for dust and nitrogen oxides, was studied. Two types of ceramic cells for use in industrial plants with a two-stepped scheme of gas treatment are proposed. Parameters characterizing the efficiency of gas treatment for dust and nitrogen oxides at the 1st and 2nd steps and the corresponding overall parameters are determined.     

Zum Stand der Extraktion mit komprimierten Gasen

The state of the art of extraction with compressed gases . Gases under high pressure have the properties of solvents. Their utilization has led to the development of novel methods of separation, extending materials separation process engineering by a new group of process techniques. Catalysts can be dissolved in high-density gas phases and thus effect favourable reaction conditions. In the neighbourhood of the critical temperature, liquid-like densities of the compressed gas are already achieved at relatively moderate pressures in the range from 50 to about 300 bar. A comparatively high solvent power of the gaseous phase ensues. This property of a compressed gas can be varied within wide limits by a change of pressure and temperature. With decreasing density it approaches the behaviour of a normal gas, with increasing density that of a liquid. Thus, there is the possibility of separating out the dissolved material again. The working temperature of such a process is largely determined by the critical temperature of the gas employed. Since a number of readily available gases have critical temperatures in the region up to 50°C, the first separations to be examined during the development of this process were those of temperature-sensitive and low-volatile mixtures. Polar materials having substantially higher critical temperatures such as ammonia, methanol and water promise a further series of possible applications.     

A sustainable mediated electrochemical process for the abatement of NOx from simulated flue gas by using Ag(I)/Ag(II) redox mediators

Electrochemical removal of NO and NO₂ by using Ag(I)/Ag(II) redox mediator system in nitric acid medium by two-stage scrubbing process was investigated. Experiments were carried out for the complete removal of NO and NO₂ from the stimulated flue gas at room temperature and atmospheric pressure. The process parameters like current density, Ag(I) concentration, HNO₃ concentration, initial concentration of NO, Ag(I) concentration and temperature were studied and optimized. A removal efficiency of >99% was achieved using this sustainable redox process. Ag(II)/Ag(I) can be regenerated and reused for the scrubbing of waste gases continuously and there is no other gases emission during scrubbing.     

燃煤矸石锅炉烟气处理工艺的选择与探讨

分析了国内燃煤电厂及煤矸石电厂锅炉烟气排放现状和存在的问题 ,针对本厂特点 ,选用了高压静电除尘、石灰石 -石膏法脱硫、水力除尘清灰闭路循环等烟气治理工艺 ,改造原有的烟气处理工艺 ,取得了令人满意的效果。     

Aerosol formation by heterogeneous nucleation in wet scrubbing processes

The phenomenon of aerosol formation is often watched in industrial wet scrubbing processes especially if strong acid gases are absorbed in aqueous solutions. Although the basic principles of aerosol formation are well known in general, there exist nearly no specific rules for the design of industrial processes in which aerosol formation can be expected. There are two reasons for the fragmentary knowledge concerning aerosol formation in wet scrubbing processes. Firstly, it is a very complex task to describe the formation and the growth of aerosols theoretically under typical conditions of industrial processes. Secondly, no reliable experimental data, especially for the validation of theoretical work, has been available to date. To bridge this gap, a semi-technical wet scrubbing plant has been developed and erected in which the formation and the growth of aerosols under realistic conditions can be studied and the characteristic aerosol parameters can be measured in situ. It is shown that HCl-aerosols are formed in a quench cooler for hot flue gases of about 200°C even at low HCl feed concentrations of about l000 mg m⁻³, but only in the presence of foreign nuclei. The aerosol droplets in the quench cooler grow up to 1–1.5 μm and can be enlarged in a direct-contact-cooling column up to about 2.5 μm. Furthermore, a strategy for aerosol evaporation is discussed.     

Technico‐economical assessment of MFI‐type zeolite membranes for CO2 capture from postcombustion flue gases

A detailed survey of the effect of moisture on the CO₂/N₂ permeation and separation performance of Mobile Five (MFI) zeolite membranes in view of downstream postcombustion CO₂ capture applications in power plants and incinerators is presented. The membranes, displaying a nanocomposite architecture, have been prepared on α‐alumina tubes by pore‐plugging hydrothermal synthesis at 443 K for 89 h using a precursor clear solution with molar composition 1 SiO₂:0.45 tetrapropylammonium hydroxide:27.8 H₂O. The synthesized membranes present reasonable permeation and CO₂/N₂ separation properties even in the presence of high water concentrations in the gas stream. A critical discussion is also provided on the technico‐economical feasibility (i.e., CO₂ recovery, CO₂ purity in the permeate, module volume, and energy consumption) of a membrane cascade unit for CO₂ capture and liquefaction/supercritical storage from standard flue gases emitted from an incinerator. Our results suggest that the permeate pressure should be kept under primary vacuum to promote the CO₂ driving force within the membrane. © 2011 American Institute of Chemical Engineers AIChE J, 58: 3183–3194, 2012     

CFD simulation of chemical reaction between sulfur dioxide and water in a venturi scrubber

ABSTRACT

The use of fossil fuel, i.e., coal, was first initiated in 1880s for electricity generation. It was used extensively worldwide due to its cheap rate. Consequently, there is an adverse effect on the environment that results in a climate change. Many industries were working on cleaning flue gases emitted from coal power plants according to Environmental Protection Agency (EPA) standards by using different scrubbing technologies and venturi scrubber is one of them having ability to remove particulates and toxic gases simultaneously. Industries were using computational fluid dynamics (CFD) techniques to fully understand the gases behavior inside scrubbing technologies prior employed in the project. This research represents CFD simulation to study abatement process of sulfur dioxide through chemical reaction with water in a venturi scrubber. Parameters such as mass concentration of sulfurous acid formation, sulfur dioxide and water mass content distribution inside venturi scrubber were analyzed. The sulfur dioxide removal efficiency was also investigated. The results show that water mass content distribution was greatly influenced by sulfur dioxide mass flow rates. Desulfurization efficiency depreciates with an increase in sulfur dioxide mass flow rate, whereas efficiency increases with accession in liquid to gas ratio. Maximum sulfur dioxide removal was observed at lower sulfur dioxide concentration comparatively to higher concentration of sulfur dioxide.