Wet Scrubber System Research Articles

Oxidative Absorption of Elemental Mercury from Flue Gas Using a Modified Fenton-like Wet Scrubbing System

A novel oxidative absorption process of elemental mercury (Hg0) from flue gas using a Mn2+-modified Fe3+/H2O2 wet scrubbing system (i.e., Mn2+-modified Fenton-like wet scrubbing system) was propose...

Oxidation Removal of CO from Flue Gas Using Two Fenton-like Wet Scrubbing Systems

Advanced oxidation removal of carbon monoxide (CO) from flue gas using two Fenton-like wet scrubbing systems was studied in a bubbling scrubber for the first time. Influence of several technological parameters (e.g., H2O2 concentration, Fe3+/Cu2+ concentration, temperature, solution pH, CO inlet concentration, and gas flow rate) on the oxidation removal of CO was evaluated. Free radicals, products, and mechanism of CO oxidation removal were also studied. The results demonstrate that pH and temperature of the solution and concentration of H2O2 have double influence on the removal efficiency of CO. The increase of Fe3+/Cu2+ concentration elevates the removal efficiency of CO. The CO removal efficiency is reduced by raising the CO inlet concentration and the gas flow rate. Hydroxyl radical (•OH) oxidation is proved to be responsible for the oxidation removal of CO in the two studied Fenton-like wet scrubbing systems (H2O2/Cu2+ and H2O2/Fe3+). The main products of CO oxidation removal are bicarbonate, carbonate, and CO2 and can be effectively treated using a simple postprocessing strategy. The new removal process will not produce subsequent pollution, and may even provide a new option for green emission reduction of CO from exhaust gas.

Experimental study on aerosol scrubbing efficiency of self-priming venturi scrubber submerged in water pool

Scrubber nozzles are key pieces of equipment used to remove aerosols in a wet-type filtered containment venting system (FCVS). This study deals with the aerosol scrubbing efficiency of a scrubber nozzle operating in self-priming mode. The scrubber nozzle that has been developed in this work consists of a reducer, a throat, a diffuser, a liquid suction slit, and an end cap with a rectangular section area. The aim of this study was to characterize scrubbing efficiency under various thermal hydraulic and aerosol conditions including nozzle inlet pressure (250–600 kPa(g)), nozzle inlet temperature (102–164 °C), nozzle inlet flow rate (air: 42–132 m3/h, steam: 112–269 m3/h), submergence from the nozzle exit (0.7–2.7 m), aerosol size (0.5, 0.7, 3 µm), nozzle inlet aerosol concentration (0.1–3 g/m3), and steam mass fraction in the main carrier gas (0–1). Aerosol scrubbing efficiency was measured based on the inlet and outlet aerosol concentrations of the scrubbing vessel with isokinetic sampling systems including a glass microfiber filter. Experimental results show that the scrubbing efficiency increased with increasing aerosol size, steam mass fraction, nozzle submergence, and inlet aerosol concentration. We also showed that the scrubbing efficiency increased with an increase in inlet pressure at low scrubber nozzle submergence. However, at higher scrubber nozzle submergence, the nozzle inlet pressure did not significantly influence the scrubbing efficiency. The aerosol scrubbing efficiency with the developed self-priming scrubber nozzle submerged in the pool was over 97% for various thermal–hydraulic conditions. Thus, the experimental results can be used to design a wet scrubber system considering upstream conditions such as operation of the FCVS.

Wet Scrubber Systems – Each Operating Modes and Main Features

Wet Scrubber Systems – Each Operating Modes and Main Features

Исследование процесса тепломассообмена в пре-скруббере системы мокрой газоочистки доменного газа проекта компании Paul Wurth

Исследование процесса тепломассообмена в пре-скруббере системы мокрой газоочистки доменного газа проекта компании Paul Wurth

L’Aquila Smart Clean Air City: The Italian Pilot Project for Healthy Urban Air

Exposure to atmospheric pollution is a major concern for urban populations. Currently, no effective strategy has been adopted to tackle the problem. The paper presents the Smart Clean Air City project, a pilot experiment concerning the improvement in urban air quality. Small wet scrubber systems will be operating in a network configuration in suitable urban areas of L’Aquila city (Italy). The purpose of this work is to describe the project and show the preliminary results obtained in the characterization of two urban sites before the remediation test; the main operating principles of the wet scrubber system will be discussed, as well as the design of the mobile treatment plant for the processing of wastewater resulting from scrubber operation. Measurements of particle size distributions in the range of 0.30–25 µm took place in the two sites of interest, an urban background and a traffic area in the city of L’Aquila. The mean number concentration detected was 2.4 × 107 and 4.5 × 107 particles/m3, respectively. Finally, theoretical assessments, performed by Computational Fluid Dynamics (CFD) codes, will show the effects of the wet scrubber operation on air pollutants under different environmental conditions and in several urban usage patterns.

A Study on the Characteristics of the Gas Flow in Wet Scrubber System for Deodorization

It is necessary to develop a device for the design of wet scrubber with a more efficient deodorization performance in order to enhance the odor reducing effect of the wet scrubber. Therefore in this study, the superiority of the new wet scrubber with the centrifugal separation function different from the conventional wet scrubber was analyzed by the computational fluid dynamics. From CFD analysis, the pressure and velocity distribution, the peak vorticity, the retention time and the flow uniformity were calculated and compared with the performance characteristics of the centrifugal separator. As the results of CFD analysis, the peak vorticity and retention time of the gas flow were increased about 22% and the flow uniformity was improved about 7.2% by the centrifugal separator. Therefore the centrifugal separator in the wet scrubber will improve the deodorizing effect and the cleaning condition of the gas.

Experimental study on particle removal with gas-liquid cross-flow array system

Abstract It is considered to be a valid method for using the waste water of an industrial plant in a wet scrubber to control the air pollution of the exhaust gas of the same plant. A new Gas-Liquid Cross-flow Array (GLCA) wet scrubber system is proposed to reduce the particulate matters of the exhaust gas. Thereby, the plant’s waste water is formed into a continuing and regular liquid columnar array to separate the exhaust gas particles. The principle of this method is that many continually falling waste water liquid columns act as dust collectors. These dust collectors are perpendicularly streamed by the dusty gas flow and particles can be captured by the water stream due to inertial, diffusion and interception mechanisms. Generally the GLCA system is applied to exhaust gas purification with hot temperatures, where inertial, interception, diffusion, condensation, and thermophertic mechanisms could occur. However, in the first scientific investigation the gas temperature was fixed close to the water temperature. So the condensation and thermophertic effects can be nearly excluded. A model approach for this “cold version” was developed to optimize the design and operating parameters. Experiments on a lab-scale test rig are shown, by which the pressure drop and the grade penetration efficiency were measured for different parameters (number of unit rows, geometric parameters and gas velocities…). To get the optimal GLCA parameters for a high separation efficiency with lowest pressure drop the quality-factor is used. Further a method is presented to calculate the single unit row grade penetration and pressure drop from measurements of the total grade penetration and total pressure drop of a high number of unit rows. With these method it was possible to calculate for a certain given particle size separation efficiency, the needed number of unit rows, respectively the length of the GLCA filter apparatus and the expected total pressure drop.

Assembly Programmable Logic Control (PLC) in the Rotary Dryer Machine for Processing Waste Liquid System

Programmable Logic Controller (PLC) is widely used to control systems on the manufacturing industry, automotive industry and etc. PLC is used to regulate the production process and machine systems to work simultaneously and continue. PLC has system to regulate the movement of machine components, displacement system of product, system settings motion or displacement of other components. PLC is a control system with some advantages such as simple in design, easy to use and circuit modification, low cost, easy maintenance, high reliability and safe. In this paper, we will focus on the PLC that used in the control of equipment movement on the rotary dryer system for waste liquid processing. PLC will be control the movement of the motor for drum of dryer, heating system, water circulation in the wet scrubber system, vacuum cleaner and smoke systems. All these systems are connected by PLC and working by arranged the setting time of system. The first process, PLC will activate the motion system of motor to drive the dryer drum rotating to left or right side. Then the burner is active for heating the drum of dryer. Effect in this process made smoke and dust happen in the rotary dryer system. The pump automatically will be activating to spray water on a wet scrubber system to catch the dust and smoke. Dust and smoke will be inhaled by the blower and flow back into the rotary dryer machine. Therefore there is no smoke and dust flowing into the environment. The results show that the PLC can be control the motion system and processes machine rotary dryer to drying the waste liquid in short time. Such as 20 minutes to 5 liters of liquid waste volume and 30 minutes to 15 liters and made the waste liquid be friendly environment.

Technological and life cycle assessment of organics processing odour control technologies

As more municipalities and communities across developed world look towards implementing organic waste management programmes or upgrading existing ones, composting facilities are emerging as a popular choice. However, odour from these facilities continues to be one of the most important concerns in terms of cost & effective mitigation. This paper provides a technological and life cycle assessment of some of the different odour control technologies and treatment methods that can be implemented in organics processing facilities. The technological assessment compared biofilters, packed tower wet scrubbers, fine mist wet scrubbers, activated carbon adsorption, thermal oxidization, oxidization chemicals and masking agents. The technologies/treatment methods were evaluated and compared based on a variety of operational, usage and cost parameters. Based on the technological assessment it was found that, biofilters and packed bed wet scrubbers are the most applicable odour control technologies for use in organics processing faculties. A life cycle assessment was then done to compare the environmental impacts of the packed-bed wet scrubber system, organic (wood-chip media) bio-filter and inorganic (synthetic media) bio-filter systems. Twelve impact categories were assessed; cumulative energy demand (CED), climate change, human toxicity, photochemical oxidant formation, metal depletion, fossil depletion, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial eco-toxicity, freshwater eco-toxicity and marine eco-toxicity. The results showed that for all impact categories the synthetic media biofilter had the highest environmental impact, followed by the wood chip media bio-filter system. The packed-bed system had the lowest environmental impact for all categories.

습식 스크러버의 분무유량, 형상비 및 충진율 변화가 스모크 저감에 미치는 영향

There has been increased amount of atmospheric pollutants including NOx and SOx which cause acid rain and photochemical smog as a result of increased use of fossil fuels. In order to reduce the amount of pollutants produced by fossil fuel, wet scrubber system is introduced in this experiment. Wet scrubber system is applied to a diesel engine (3,298 cc) and the amount of smoke is measured before and after the application in terms of aspect ratio, filling rate, and flow rate. The result showed a lot of smoke reduction when wet scrubber system was applied, and also the aspect ratios and water spray flow rate were the important factors to improve smoke reduction.

습식세정장치에서 발생되는 마이크로버블을 이용한 음식물쓰레기 발생 복합악취 처리

The objective of this work was to treat complex mal-odor of food waste with micro-bubbles from enhanced wet scrubber system, where the pilot plant was operated. Micro bubbles from the enhanced reactor of venturi scrubber were successfully generated through the air atomizing process with high velocity more than 60 m/sec and played an important role in the removal of mal-odor. Mal-odor was effectively changed into the micro-bubble and treated with washing chemicals together. Through establishing two series connection of the reactors, 85.2 % removal efficiency of complex mal-odor was obtained in case of average 940 times of input air. 0.35 kg/hr of sulfuric acid, 0.188 kg/hr of sodium hydroxide and 0.043 kg/hr of hypochlorite were injected for chemical washing.

Using quadrupole mass spectrometry for on-line gas analysis – Gasification of biomass and refuse derived fuel

A quantitative method of on-line gas analysis was developed, using quadrupole mass spectrometry to measure gas composition when charcoal, wood, straw, and refuse derived fuel were gasified. Despite overlapping between some of the species, the method was demonstrated on small-scale laboratory gasifiers, recording the main components (e.g. N2∼54–67vol.%; H2∼5–13vol.%; CO2∼15–17vol.%; CO∼10–17vol.%), and lower levels of CH4 (∼1–2vol.%) and O2 (∼0.1–1vol.%) in the gas. Trace levels of H2S (∼100–300ppmv) and COS (∼10–30ppmv) were also measured (important for gas clean-up strategies). On-line measurements were performed on a commercial pilot-scale down-draft gasifier (using waste wood), and the concentrations of H2S varied from 200 to 700ppmv, and COS from 7 to 17ppmv. The ratio of H2S: COS was higher than in the laboratory trials – probably because of COS hydrolysis reactions taking place in the wet scrubbing systems.

Study on washwater effluent quality discharged by ship exhaust gas DeSO<SUB align="right">x system with magnesium and seawater desulphurisation method

The latest convention of ship pollution prevention was carried out by the International Maritime Organization (IMO), which requires that sulphur dioxide emissions from ships around the world must be further reduced. A novel wet scrubber system with MgO and seawater (M&S) as desulphuriser was proposed to deal with the new convention. The quality of the washwater effluent discharged by M&S DeSO x system has not been studied systematically yet. This paper used a variety of methods to analyse the effluent, including chemical method, spectrophotometry and X-ray diffractometer. The effluent was detected to contain a large amount of chloride, sulphate and nitrate ions, and the mass fraction of chloride ion was as high as 3.2%. The main components of suspended solids were magnesium hydroxide, magnesium sulphite, and silicon dioxide. In the effluent, COD, SS, total oil content and turbidity were above the limitation set by the washwater discharge criteria. Based on the analysis of the effluent quality, the sulphite, nitrite, PAHs and total oil content were regarded as the main factors affecting COD.

Investigation of carboxylic acids and non-aqueous solvents for the selective leaching of zinc from blast furnace dust slurry

The recycling of iron bearing dusts produced during iron and steel manufacturing processes is vital to the sustainability of these processes; however, contamination of these dusts with zinc increases the difficulty to do this. Blast furnace dust, collected by a wet scrubber system, was sampled and characterised to investigate the removal of zinc to produce a treated residue with low zinc content suitable for recycling through the blast furnace.This paper examines a leaching process for the dust using different organic carboxylic acids, to establish if they were capable of extracting high levels of zinc and low levels of iron. Prop-2-enoic acid was found to be particularly effective, extracting high levels of zinc up to 85.7% and low levels of iron, 8.5%. The paper also discusses the mechanisms of extraction more specifically for organic carboxylic acids and found that the iron extraction was well explained by the variation in pH and the Bronsted–Lowry theory; whereas zinc extraction was well explained by substituent group effects and the Lewis acid/base theory.The novel use of a non-aqueous solvent with prop-2-enoic acid, to minimise the ion solvating ability and proton dissociation, was found to reduce the level of iron extraction from 8.5% to 0.1% without detrimental effect on zinc extraction when leaching. A range of mineral and carboxylic acids were also tested to investigate and compare the effect of pH and chemical structure on the leaching efficacy.

Development of a Biphasic Electroreactor with a Wet Scrubbing System for the Removal of Gaseous Benzene

An efficient, continuous flow electroreactor system comprising a scrubbing column (for absorption) and a biphasic electroreactor (for degradation) was developed to treat gas streams containing benzene. Initial benzene absorption studies using a continuous flow bubble column containing absorbents like 40% sulfuric acid, 10% silicone oil (3, 5, 10 cSt), or 100% silicone oil showed that 100% silicone oil is the most suitable. A biphasic batch electroreactor based on 50 mL of silicone oil and 100 mL of activated Co(III) (activated electrochemically) in 40% sulfuric acid demonstrated that indirect oxidation of benzene is possible by Co(III). Combined experiments on the wet scrubbing column and biphasic electroreactor (BP-ER) were performed to determine the feasibility of benzene removal, which is reside in the silicone oil medium. In semidynamic scrubbing with BP-ER experiments using an aqueous electroreactor volume of 2 L, and an inlet gas flow and a gaseous benzene concentration were 10 Lmin(-1) and 100 ppm, respectively, benzene removal efficiency is 75% in sustainable way. The trend of CO2 evolution is well correlated with benzene recovery in the BP-ER. The addition of sodiumdodecyl sulfate (SDS) enhanced the recovery of silicone oil without affecting benzene removal. This process is promising for the treatment of high concentrations of gaseous benzene.

Speciation of mercury in FGD gypsum and mercury emission during the wallboard production in China

During combustion of pulverized coals, most of the mercury (Hg) in coal volatilizes. With the wide use of dry and wet scrubber systems for flue gas desulfurization (FGD), various amounts of Hg are captured by coal combustion byproducts, such as, FGD gypsum. The specification of Hg in FGD gypsum is essential not only to determine the risk when the wastes are recycled or disposed but also to understand the behavior of Hg during coal combustion and the mechanisms of Hg oxidation along the flue gas path. In this study, a temperature-programmed decomposition technique was used in order to acquire an understanding of the Hg species associated with FGD gypsum. A series of Hg reference compounds were used to obtain the characteristic temperature of decomposition for each Hg compound. The decomposition temperature of the Hg species is in an increasing order as Hg2SO4<Hg2Cl2<HgCl2<black HgS<HgO<red HgS<HgSO4. The results also indicate that HgCl2 and HgS are the primary Hg compounds in FGD gypsum samples. Hg stability during the reutilization of FGD gypsum is important due to its health and environmental impact, and its value in improving the Hg emission inventory. The industrial calcining process of wallboard production is simulated in order to determine the Hg emission percentage during the reutilization of FGD gypsum. Results indicate that 12.1–55.1% of total Hg would be emitted from FGD gypsum in this process. A larger percentage of Hg will be emitted when the proportion of Hg2Cl2 and HgCl2 is higher. The Hg re-emissions from FGD gypsum during wallboard production in China were estimated to be 4.7tons in 2008.

Sulphur based thermochemical cycles: Development and assessment of key components of the process

HycycleS was a cooperation of nine European partners and further non-European partners and aimed at the qualification and enhancement of materials and components for key steps of solar and nuclear powered thermochemical cycles for hydrogen generation from water. The focus of HycycleS was the decomposition of sulphuric acid (H2SO4) which is the central step of the sulphur-based family of those processes. Emphasis was put on materials and components for H2SO4 evaporation, decomposition, and sulphur dioxide separation. The suitability of materials and components was demonstrated by decomposing H2SO4 and separating its decomposition products in scalable prototypes. Silicon Carbide (SiC) turned out as the material of choice for the components facing the most corrosive environment of the process: the sulphuric acid evaporator and decomposer. Candidate catalysts for the high temperature reduction of sulphur trioxide have been screened and analysed. Cr–Fe mixed oxide (Fe0.7Cr1.3O3) was the most promising material among the ones examined. Based on the use of the highlighted construction and catalyst materials prototype decomposers have been developed and tested. The successful fabrication and testing of a large size heat exchanger/reactor prototype composed of SiC plates shows promise with respect to its use for H2SO4 decomposition in the SI and HyS cycle. A solar specific decomposer prototype was developed, realised and successfully tested on sun in a solar furnace. A novel approach of using dense oxygen transport membranes, made from complex ceramics, for oxygen removal from the H2SO4 decomposition product in order to shift the equilibrium in favour of increased decomposition was investigated. The membranes stability and suitability for carrying out this separation was investigated experimentally. Parallel to this, a conventional oxygen separator, a low-temperature wet scrubbing system, was investigated as well. Scale-up scenarios of components and of the process were addressed.

CFD Based Parametric Analysis of Gas Flow in A Counter-Flow Wet Scrubber System

Environmental protection measures regarding industrial emissions and tightened regulations for air pollution led to the selection of a counter-flow wet scrubber system based on applicability and economic considerations. The flow dynamics of gas transporting particulate matter and gaseous contaminants is a key factor which should be considered in the scrubber design. In this study, gas flow field were simulated using ANSYS Fluent computational fluids dynamic (CFD) software based on the continuity, momentum and k-ε turbulence model so as to obtain optimum design of the system, improve efficiency, shorten experimental, period and avoid dead zone. The result shows that the residuals have done a very good job of converging at minimum number of iterations and error of 1E-6. The velocity flow contours and vectors at the inlet, across the scrubbing chamber and the outlet shows a distributed flow and the velocity profiles have fully conformed to the recommended profile for turbulent flows in pipes. The total pressure within the scrubber cross-section is constant while the minimum and maximum pressure drops was obtained to be 0.30pa and 3.03pa which has conformed to the recommended pressure drop for wet scrubbers. From the results obtained, it can be deduced that the numerical simulation using CFD is an effective method to study the flow characteristics of a counter-flow wet scrubber system.

An assessment of dioxin contamination from the intermittent operation of a municipal waste incinerator in Japan and associated remediation

Significant dioxin (polychlorinated dibenzo-para-dioxins (PCDDs)/polychlorinated dibenzo-furans (PCDFs)) pollution from a municipal solid waste incinerator was discovered in 1997 in Osaka prefecture/Japan. The cause and mechanism of pollution was identified by a detailed assessment of the environment and incinerator plant. The primary sources of PCDD/PCDF pollution were high dioxin releases from an intermittently operated waste incinerator with PCDD/PCDF emissions of 150 ng-TEQ/Nm(3). PCDD/PCDF also accumulated in the wet scrubber system (3,000 μg TEQ/L) by adsorption and water recirculation in the incinerator. Scrubber water was air-cooled with a cooling tower located on the roof of the incinerator. High concentrations of dioxins in the cooling water were released as aerosols into the surrounding and caused heavy soil pollution in the area near the plant. These emissions were considered as the major contamination pathway from the plant. Decontamination and soil remediation in and around the incinerator plant were conducted using a variety of destruction technologies (including incineration, photochemical degradation and GeoMelt technology). Although the soil remediation process was successfully finished in December 2006 about 3% of the waste still remains. The case demonstrates that releases from incinerators which do not use best available technology or which are not operated according to best environmental practices can contaminate their operators and surrounding land. This significant pollution had a large impact on the Japanese government's approach toward controlling dioxin pollution. Since this incident, a ministerial conference on dioxins has successfully strengthened control measures.