Showing papers on "Fouling published in 1984"

Treatment of fouling with microcapsules

Abstract: A method for controlling, preventing, or removing fouling deposits comprising microencapsulating fouling control chemicals in a slow release capsule. The microcapsules are applied to the substrate to be treated, where they stick to the substrate and slowly release the active treating agents.

Fouling of Heat Exchanger Surface: Measurement and Diagnosis

Abstract: Fouling in heat exchange equipment results in a significant energy toss by increasing heat transfer resistance and fluid frictional resistance. This paper deals with an effective way to monitor fouling and describes a potentially useful diagnostic approach for discriminating different types of deposit in situ. Information regarding deposit type would be useful in selecting an appropriate treatment procedure. Some cautions regarding the indiscriminate use of fouling factor or fouling resistance are also discussed.

Process for treating combustion systems with pressure-hydrated dolomitic lime

Abstract: A process for eliminating, reducing or modifying slagging, convective tube fouling, corrosion, sulfur trioxide formation, acid smut and plume visibility by intermittently injecting pressure-hydrated dolomitic lime consisting of porous, particles having a high specific surface and a low settling rate in water into the interior of a combustion system.

Method of controlling iron induced fouling in water systems

Abstract: A method of inhibiting corrosion and controlling deposition in aqueous mediums, such as in cooling water systems, wherein iron containing well water is used as a water make-up source, is disclosed. The method comprises addition of certain water soluble acrylic acid type/allyl hydroxy propyl sulfonate ether copolymers to the desired aqueous medium.

Anti-fouling coating process

Abstract: A mechanical process for preventing the fouling of metalic objects such as ship propellers, hulls and other types of hardware exposed to seawater by application on the exposed surface of a ceramic coating. The coating is applied by thermal spraying. The ceramic coating is formulated to have sufficient hardness to prevent encrustation of barnacles, tube worms and other parasites, but retains enough malleability to prevent brittleness and to provide sufficient resistance to impacts.

A survey of gas-side fouling measuring devices

Abstract: A survey of measuring devices or probes, which were used to investigate gas side fouling, was carried out. Five different types of measuring devices are identified and discussed including: heat flux meters, mass accumulation probes, optical devices, deposition probes, and acid condensation probes. A total of 32 different probes are described in detail and summarized in matrix or tabular form. The important considerations of combustion gas characterization and deposit analysis are also given a significant amount of attention. The results show that considerable work was done in the development of gas side fouling probes. However, it is clear that the design, construction, and testing of a durable, versatile probe - capable of monitoring on-line fouling resistances - remains a formidable task.

Combined cycle power plant

Abstract: A compact, unfired, staggered tube, once-through steam generator or boiler of simple construction intended primarily for combined cycle power plants in which the thermal energy utilized to generate steam is obtained from the exhaust gases of a gas turbine engine The boiler provides steam at two different pressure levels, which maximizes recovery of thermal energy; and all wettable components in the steam/water loop are fabricated of corrosion resistant materials This eliminates the need for controlling the pH of the feedwater and the need for chemically controlling its dissolved oxygen content, thereby reducing maintenance and operating costs and making automatic, unattended, remotely controlled operation of the boiler practical as well as eliminating the need for blowing down the boiler and minimizing requirements for make-up water The boiler can be operated dry to remove gas side fouling; and feedwater flow rates can be directly controlled Orifice-generated pressure drops at the inlets of the boiler tubes which are relatively large compared to the pressure drop in the rest of each tube eliminate the flow instability that is characteristic of once-through boilers

An Evaluation of the Use of Porous Membranes for the Dewatering of Wellhead Bitumen/Water/Mineral Emulsions

Abstract: In-situ bitumen and heavy oil recovery by steam stimulation can produce large volumes of oil-in-water emulsions. Several difficulties facing recovery operations are the limited water supply in relation to the volumes required for steam injection and the processing of water-rich emulsions to low-water content bitumen. In current practice these emulsions require substantial amounts of chemical additives with large settling tanks and elevated temperatures. An evaluation of the use of porous membranes for the treatment of these emulsions has been made which has led to the development of a process that will produce single pass (80%) steam quality water as membrane permeate and a bitumen-rich stream which can be processed by existing dewatering methods. Details of the performance of several membranes of various pore sizes are given and a comparison is made with existing single-pass steam boiler requirements. Of those tested, cellulose membranes resisted fouling by the bitumen, and thus are the most pro...

Fouling of heat exchangers: are we solving the problem?

Abstract: Problemes d'encrassement, solutions disponibles. Prediction et controle de l'encrassement. Recherches necessaires

Process for removing hydrogen sulfide with reduced fouling

Abstract: A gas scrubbing operation wherein a mixture of gases is scrubbed with a gas scrubbing medium to remove at least one gas component from the mixture is improved by reducing the fouling of apparatus used in the scrubbing operation by adding to the scrubbing medium an antifoulant effective amount of a hydroxylamine compound

Bivalve fouling of nuclear power plant service-water systems. Volume 1. Correlation of bivalve biological characteristics and raw-water system design

Abstract: Fouling of raw-water systems in nuclear power plants in the US can affect the safe operation of a power plant. This report describes correlations between the biology of bivalve organisms and the design and operation of power plants that allow bivalves to enter and reside in nuclear power plants. Discussions are focused on safety-related raw-water systems subject to fouling by the Asiatic clam (Corbicula fluminea), the blue mussel (Mytilus edulis), and the American oyster (Crassostrea virginica). Score sheets to rate fouling potential of power plant systems and components are provided.

The Mechanism of Magnetite Dissolution in Chelant Solutions

Abstract: Chelating agents are used to remove fouling deposits and surface films from industrial equipment. This paper discusses the mechanisms by which magnetite (Fe3O4) dissolves in chelating solv...

Industrial fouling: problem characterization, economic assessment, and review of prevention, mitigation, and accommodation techniques

Abstract: A comprehensive overview of heat exchanger fouling in the manufacturing industries is provided. Specifically, this overview addresses: the characteristics of industrial fouling problems; the mitigation and accommodation techniques currently used by industry; and the types and magnitude of costs associated with industrial fouling. A detailed review of the fouling problems, costs and mitigation techniques is provided for the food, textile, pulp and paper, chemical, petroleum, cement, glass and primary metals industries.

Comparison of low-rank coal ash sintering characteristics with pilot plant ash fouling tendencies

Abstract: The objective of this work was to develop a simple laboratory test for evaluating the fouling tendencies of low-rank coal ashes. Simultaneous ash shrinkage-electrical resistance measurements were performed to determine the sinter points of various coal ashes. In addition, the compressive strength of sintered ash pellets was determined to give an indication of the apparent bonding strength. The factors studied include ash composition, ash time-temperature history and particle size. Sintering tests appeared, from this preliminary evaluation, to be a satisfactory bench-scale method for evaluating the fouling behavior of low-rank coals. These tests correlated well with the observed fouling behavior of coals in the UNDERC test furnace. There was a strong correlation between pilot plant ash fouling tendency and the amount of shrinkage observed and the compressive strength of ASTM and fly ash samples heated above their sinter points. In summary, the small amount of material required, the ability to use laboratory-produced ash rather than fly ash, and the low cost of the techniques are desirable characteristics for a test of fouling propensity. In addition, these techniques should prove useful in studies to clarify the mechanisms of particle-to-particle bonding involved in deposit formation. This together with information of the metal-ash bondingmore » should help to both explain and predict fouling behavior of low-rank coal in combustion systems. 10 references, 9 figures, 5 tables.« less

Recovery of Citrus Cloud from Aqueous Peel Extract by Microfiltration

Abstract: Microfiltration of reconsituted aqueous peel extract resulted in linear flux decline with time. Feed stream of reconstituted peel extract does not foul the membrane and flux decline is due solely to increased retentate viscosity. Cloud was concentrated up to 6.3% of washed dry matter, compared with 1.5% achieved by vacuum heat concentration. Permeate was at constant low viscosity during filtration experiment, free of insolubles, and crystal clear. Soluble sugars do not contribute to fouling gel layer; their permeation flux is constant, and is only a function of viscosity. Soluble high-molecular-weight polymers, such as pectins, cause membrane fouling and flux depression. Fluxes for soluble constituents, sucrose and pectin, were higher than those of reconstituted peel extract with similar viscosity.

Copper-nickel coated steel plate and preparation thereof

Abstract: PURPOSE:To prevent the corrosion of a steel plate due to sea water and the fouling of ocean microorganisms thereto when the steel plate is used in sea water, by a method wherein the surface of the steel plate is cleaned and the cleaned steel plate is subjected to vapor deposition of Ni and Cu under vacuum. CONSTITUTION:The surface of a steel plate used in a vessel or a seashore structure is subjected to shot blast treatment to remove scale. In the next step, the treated steel plate is irradiated with high speed electron beams in a mixed gas atmosphere consisting of 70-90% hydrogen and 10-30% argon or nitrogen to reduce residual iron oxide on the surface thereof to be cleaned. The cleaned steel plate is introduced into a vacuum tank with a vacuum degree of 10 -10 torr and coated with Ni and Cu from a Ni melting crucible and a Cu melting crucible heated by electron beams by vacuum vapor deposition to form a Ni-Cu alloy vapor deposition layer. The obtained steel plate is prevented from corrosion due to NaCl in sea water and surface roughening due to the fouling ocean microorganisms.