Mist Eliminator Research Articles

Behavior and Control of Metals in a Hazardous Waste Incinerator

In conjunction with a performance test series used to develop trial burn test conditions, supplementary sampling and analysis were performed to study the behavior of metals in an incinerator's combustion system and the control of metals in the incinerator's air pollution control equipment (APCE) train. The test incinerator was a Nichols Monohearth primary chamber with an afterburner; APCE consisted of a spray dryer, a cooler/condenser, a venturi scrubber, a baffle-absorber, and a mist eliminator. Multiple metals stack sampling was performed at the inlet to the APCE system, concurrent with incinerator feed and stack sampling. Analysis of these additional samples allowed evaluation of metals partitioning in the combustion system as well as APCE removal efficiencies as a function of chlorine feed concentration and venturi differential pressure. X-Ray diffractometry was applied to selected samples to speciate any crystalline phases present, and scanning electron microscopy with energy dispersive X-ray spectroscopy was used to study the morphology, size, and composition of particles captured via conventional sampling techniques. Arsenic, beryllium, cadmium, chromium, and lead compounds were spiked at known rates, and additionally, several nontoxic metals natively present in the feeds were evaluated as potential surrogates, including copper, iron, titanium, and zinc.

Experimental approach and techniques for the evaluation of wet flue gas desulfurization scrubber fluid mechanics

The fluid mechanics within wet flue gas desulfurization (FGD) scrubbers involve several complex two-phase gas/liquid interactions. The fluid flow directly affects scrubber pressure drop, mist eliminator water removal, and the SO 2 mass transfer/chemical reaction process. Current industrial efforts to develop cost-effective high-efficiency wet FGD scrubbers are focusing, in part, on optimizing the fluid mechanics. The development of an experimental approach and test facility for understanding and optimizing wet scrubber flow characteristics is discussed in this paper. Specifically, scaling procedures for downsizing a wet scrubber for the laboratory environment with field data comparisons are summarized. Furthermore, experimental techniques for the measurement of wet scrubber flow distribution, pressure drop, spray nozzle droplet size characteristics and wet scrubber liquid-to-gas ratio are discussed. Finally, the characteristics and capabilities of a new hydraulic test facility for wet FGD scrubbers are presented.

Seawater Test Results of Open-Cycle Ocean Thermal Energy Conversion [OC-OTEC] Components

Key components of open-cycle ocean thermal energy conversion (OC-OTEC) systems—the flash evaporator, mist eliminator, passive predeaerator, two surface condenser stages, and mo direct-contact condenser stages—have been tested using seawater. These components operate at lower steam pressures and higher inlet noncondensable gas concentrations than do conventional power plant heat exchangers. The rate of heat exchanged between the evaporator and the condenser is on the order of 1.25 MW (thermal), requiring a warm seawater flow of about 0.1 m3/s; the cold seawater flow is on the order of half the warm water flow. In addition to characterizing the performance of the various components, the system has produced potable water from condensation of the steam produced in the evaporator. The information obtained in these tests is being used to design a larger-scale experiment in which net power production is expected to be demonstrated for the first time using OC-OTEC technology.

Contamination in an Experimental Gallium Arsenide Etch System

A study in a university setting was undertaken on the by-products which accumulated within a plasma etching reactor system from two years of sporadic dry etching of gallium arsenide wafers. The deposits on the reactor chamber walls, in the vacuum pump oil and its filter, in the oil mist eliminator, and in the exhaust charcoal canister were analyzed for 33 elements by simultaneous inductively coupled plasma atomic emission spectroscopy. A mass balance showed that gallium and arsenic have separate accumulation points. Gallium residues were detected only on the wall of the reactor chamber. Most of the arsenic residues were found in the rotary pump oil. The large amount of inorganic chloride in the charcoal filter indicates a potential emission of volatile chlorine-containing compounds, such as HCI and volatile metal chlorides. Arsenic was not detected in the charcoal filter.

Stability of materials in the environment of a mist eliminator in a sulfuric-acid evaporation unit

Stability of materials in the environment of a mist eliminator in a sulfuric-acid evaporation unit

メッシュエリミネータに付着する液滴の形態

Forms of droplets held on a wire mesh (type: mist eliminator) was observed by solidification of melting paraffin wax under conditions of stationary air and by a borescope in air flow.Droplets were held in the valley part of the waved mesh in the stationary and low velocity regions. When the flow velocity exceeds the loading point, the diameter of droplets increases remarkably. Droplets were carried away from the mesh at the flooding point, and the diameter increased with increase in the flow velocity.A balance equation of forces acting on a droplet could explain the observed data. The estimated radius of meniscus between a droplet and a wire of the mesh was calculated to evaluate adhesive forces other than gravity and drag.

Update on ammonia scrubbing. A state‐of‐the‐art review, highlighting, recent successes and pointing to problem areas with recommended solutions

A review is presented of the history and development of the ammonia scrubbing process leading to the design of the 1970's, with an analysis of the successes and problems to update the state of the art for use in the 1980's. The analysis is highlighted by the many successes, including SO/sub 2/ emission control, reliability, controllabiling, energy efficiency, and low capital cost. Problem areas include corrosion of booster blowers and mist eliminators that are easily solved by proper material choice or alternate blower location. Numerous alternates for by-product ammonium sulfate handling are reviewed, providing alternate means of processing.

Design guidelines for an optimum scrubber system

The revised New Source Performance Standards (NSPS) for the utility industry mandates reduced particulate matter and sulfur dioxide emissions from new utility boilers. A wet scrubber system can be an advantage in controlling both of these emissions. Existing wet scrubber systems may meet the new standards with significant increase in power consumption. A careful design of the entire scrubber system, based on the experience gained at the existing installations, is necessary to ensure cost effectiveness. The experience with existing wet scrubber systems used on coal-fired utility boilers is reviewed and their performance is correlated with power consumptions. Based on a correlation of scrubber pressure drop against outlet concentration, conventional scrubber systems would be able to meet the revised NSPS for particulate matter with a theoretical scrubber pressure drop of 43±5 cm H 2O. Overall system pressure drop, however, could easily run as high as 76 cm H 2O. Novel scrubber systems such as the electrostatically augmented scrubber may provide the necessary collection performance at lower pressure drops. The performance of the various scrubber components such as mist eliminators and reheaters is reviewed. Operating problems are also discussed.

The New ES Energy Saver Mist Eliminator. From Any Angle It Saves You Money.

The New ES Energy Saver Mist Eliminator. From Any Angle It Saves You Money.

水平流エリミネーターのミスト捕集性能に関する実験的研究

When a mist eliminator is installed in horizontal-flow, collected liquid on the eliminator flows down easily by gravity. In a horizontal-flow, therefore, it is expected that pressure drop across the eliminator is lower and gas velocity at a re-entrainment point is higher than those in an up-flow.In this paper, experimental work was carried out on pressure drop across the eliminator and collection efficiency of the eliminator for water mist in a horizontal-flow.Expanded metal and three kinds of wire mesh mist eliminators which are commercially available were used as a mist eliminator. Experimental results are compared with the results of York et al. in an up-flow. In a horizontal-flow, pressure drop across the eliminator was lower and gas velocity at the re-entrainment point was higher than those in the up-flow under same test conditions. Experimental collection efficiencies are considerably lower than those of theoretical calculation. This reason is considered that water droplets impinged on the eliminator were ruptured to fine mists which were too fine to be collected with the eliminator.

Pollution control in the fatty acid industry

AbstractOperations of the fatty acid industry create waste‐waters, emissions to the air, and solid wastes which have the potential of insulting the quality of the environment in a number of wasy. Some of the controversy and the problems that are current in the national environmental effort are discussed. As to the fatty acid industry prospects, some attention may come to the industry if toxics are found to be in the industry's wastewaters. New air emissions permit will be difficult if not impossible to obtain. Long delays and expensive data gathering will be involved. Disposal of solid waste classified as hazardous materials will become extremely costly and involve much paperwork. Wastewaters can originate from any of the process steps: spills and tank bottoms from receiving and storage, foots from alkaline extraction pretreatment, condensate from pressure reduction after fat splitting, condensing water and condensate from fatty acid distillation, and condensing water from glycerine evaporation and distillation. The organic matter in the wastes is biologically degradable so one pollutional effect is reduction of the oxygen level in receiving streams. Oil not in soluble or finely dispersed state is objectionable for the additional reason that it forms slicks or films in the water surface. Fatty acids in soluble forms are toxic to fish in fairly low concentrations. Heavy metal catalysts used for fat splitting or hydrogenation such as zinc are objectionable at trace levels. Source control methods include good operator attention to minimize avoidable losses, optimum recovery of fatty acids and oil in recovery steps, mist eliminators and entrainment separators in distillation and evaporator vapor conduits, and use of indirect condensers in place of direct spray condensers. Treatment of wastewaters includes removal of floatable fat and fatty acids by gravity settling. The residual wastewaters so pretreated are susceptible to treatment processes using bacteria for their degradation. Most fatty acid producers discharge the wastewater to municipal systems in which they receive biological treatment along with residential sewage. Air emissions are minimal for the standard criteria of particulates, organics, etc., because of the low vapor pressure of the materials involved. Odor is not subject to federal legislation, and local regulations and circumstances of concern vary. Odors originate from storage tank vents, from noncondensables vented to the atmosphere from condensers on pressure‐relief operations, and from stills. Cooling tower recirculating systems may release odors condensed in the condensing sprays, or odors may be generated from bacteria growth in the system. Odors are controlled by wet scrubbers on off gases and by conveying the gases (air) to the boiler as air supply. This practice incinerates the odor‐producing compounds. Solid wastes include spent clay used in pretreatment and foots from glycerine stills. Deposit in sanitary landfills is the usual disposal. If solid wastes contain much metal catalysts, their disposal must be to special sites approved for hazardous waste materials.

Quench Tower Particulate Emissions

Particulate emission sampling was conducted at Dofasco’s No. 2 Coke Want Quench Tower in August 1977. The sampling was performed by York Research Corporation using EPA developed quench tower sampling techniques. Particulate emissions averaged 0.245 lb/ton of coal over 17 tests. The mist eliminator in the tower consists of two rows of zig-zag baffles inclined at 20° from the vertical. Particle size data indicated that the majority of the particulate emissions were less than 10 microns in diameter. A mathematical model was used to predict the effect of particle size and gas velocity on collection efficiency. Pressure drop and re-entrainment are two restrictions which are considered in baffle design. Quench towers are the largest contributor to Dofasco’s allowable off-the-property suspended particulate impingement concentration.

Retention of fluoride from diets containing materials produced during aluminium smelting.

1. Using male rats, the availability of fluoride from five by products of the aluminium smelting industry was tested. This was done by considering the balance between fluoride administered in controlled diets and the total fluoride content of waste products eliminated over an experimental period of 1 week. 2. Results indicated that yields of available fluoride expressed as percentage weight of original material were cryolite (Na3ALF6), 45.9%; sodium fluoride (NaF), 41.7%; aluminium fluoride (AFL3.H20), 9.1%; mist eliminator grid solids (with CaF2), 9.4%; reclaimed alumina with adsorbed F, 0.27%. 3. Of the various tissues analysed for fluoride content, only the kidney and femur showed any significant correlation with the amounts of fluoride absorbed or retained.

Author's reply

Numerical simulation of the performance of an idealized wave-plate mist eliminator is used to assess the influence of drainage channels in the mist eliminator passages. The effect of the drainage channels on the primary gas flow and on the evolution of the liquid droplet distribution is calculated for a range of gas speeds, wave-plate spacing, channel sizes and inlet droplet size distributions. The ability of drainage channels to increase the droplet collection efficiency is confirmed and several features of the flow are predicted which have implications for the design of wave-plate mist eliminators.

Effectiveness of Vertical Mist Eliminators In a Cross Flow Scrubber

Three types of vertical mist eliminator—knitted wire mesh, crushed aluminum turnings, and multiple pass louvers—have been studied in a packed, cross flow scrubber. The knitted wire mesh had a maximum efficiency of 92% with a pressure drop of 0.43 in. W.G. at a velocity of 13 ft/sec, while at the maximum velocity possible in the equipment, 16 ft/sec, the louver eliminator was the most effective (76%). The Souders-Brown equation : , recommended for conventional horizontal mist eliminators is equally applicable to vertical units, with 10% higher velocities.

Solids from Wet Limestone Scrubbing of Power Plant Stack Gases

Optical and scanning electron microscopic examinations were made of the solids in aqueous suspensions of crushed limestone that had been used to scrub sulfur oxides from power plant stack gas. Most of the sulfur was recovered as CaSO3 0.5H2O which formed small thin plates that settled slowly; the relatively small amount of gypsum, CaSO4 · 2H2O, that was formed was present as massive crystals that settled rapidly. Scaling was encountered in significant amount only on the mist eliminator which had been washed periodically with the supernatant solution from which the solids had been settled. The scale was composed principally of massive gypsum crystals, but the plastic surfaces on which scale had formed were covered with a fine-grained mixture of fly ash and calcium sulfite that acted as the nucleating surface for the gypsum. The fly ash in the scrubber solids was present mostly as spheres, and these acted only as inert diluents of the solids.

Performance of Commercially Available Equipment in Scrubbing Hydrogen Chloride Gas

Six fume scrubbers were tested to establish a comparative rating for the different types of equipment that are commercially available for removing hydrogen chloride (HC1) gas from plating room exhaust air. Bids were sent out to several manufacturers asking them to quote on a scrubber that would remove 90% of the contaminant from a 2500 scfm gas stream consisting of ambient air with a concentration of 20 mg/m3 of HC1 gas. Scrubbers were chosen on the basis that they were representative of the different types of equipment available for this application. The units were connected to ductwork and piping simulating actual production conditions. The contaminant was carefully metered into an accurately measured air stream being drawn through the scrubber. A continuous sample of the scrubber discharge was recorded by a conductivity meter. The results have been published in a series of curves plotting Efficiency vs. Water Rate. Efficiencies of close to 100% were obtained with the vertical packed scrubber and the extended surface scrubber. The horizontal packed scrubber and the plate scrubber attained efficiencies of better than 95%. The fan-type scrubber was entirely unacceptable and is not recommended for use with a gaseous contaminant. The tests also revealed that optimum efficiencies can be obtained at much lower water rates than are generally recommended by the manufacturers. This makes it practical to use non-recirculated water in production scrubbers. Variations in scrubber design and effectiveness of mist eliminators are also discussed.

Balance of Payments and Government Policies

Articles cover the effects of urban meteorology on air pollution distribution; effects of air pollutants on plant life, metals and coatings; and pollution control and equipment, including mist eliminators, filtration and incineration.

Air pollution control with fibre mist eliminators

AbstractDifficult air pollution problems caused by the emission of submicron mists have been solved with fibre mist eliminators. This new equipment is the result of extensive research and development at Monsanto.This paper describes some air pollution problems which have been solved successfully with fibre mist eliminators and suggests some new problems which should be solved in the future.