Showing papers on "Fouling published in 1977"

Effect of alkalinity on the scaling of simulated cooling tower water

Abstract: The scaling behavior of simulated cooling tower water on a heat transfer surface was investigated. The alkalinity was the main parameter investigated. The fouling vs. time curves were fitted to the equation which was derived from a simple model of the fouling process. Correlation coefficients ranging from 0.81 to 0.987 were obtained in fitting the data to the model. No particular pattern was observed for delay times and they appeared not to have a significant influence on the asymptotic fouling resistance. The latter is a complex function of the alkalinity but generally increases with alkalinity for the conditions of the experiment. Scale strength appears to be a strong function of the non-calcium carbonate components of the scale.

Phosphorus containing compounds as antifoulants in ethylene cracking furnaces

Abstract: Phosphate and phosphite mono and diesters in small amounts function as antifoulant additives in ethylene cracking furnaces which are subjected to elevated temperatures from about 500° - 1700° F. These furnaces produce material that deposits and accumulates upon furnace surfaces including furnace coils and transfer line exchangers. The present antifoulant additives inhibit and suppress fouling and also help clean up previously fouled furnace surfaces.

Condensation cleaning of exhaust gases

Abstract: Exhaust gases, such as those produced by the incineration of municipal refuse, are cleaned by water scrubbing the gases in an open tower and thereafter further cooling the gases by heat exchange to condense water vapor and to trap and remove particulate material and other contaminants Fouling and plugging of the heat exchanger during the condensation step is avoided by use of a spiral flow-cross flow type of heat exchange element

Noise and fouling reducer for powder-actuated tool

Abstract: A chamber is formed on a powder-actuated tool into which the combustion gases generated by firing the tool are directed. The chamber contains a plurality of baffle plates which absorb noise and provide increased surface area for precipitation of fouling deposits carried by the combustion gases. The plates are easily removable for cleaning. The chamber is formed in a box-like housing which can be secured to a conventional indirect firing tool with minimal adaptation necessary.

Crystallization apparatus and process

Abstract: A crystallization apparatus and process especially useful for the continuous regeneration of metal processing solutions, such as copper etchants, where direct recovery of metal values in the form of large crystals of high solids content is achieved and fouling of heat exchange surfaces is obviated by a scouring action obtained through addition of preformed crystals to the heat exchange zone.

Water base, non-polluting, slow leaching, anti-fouling paint

Abstract: A water-base vinyl paint containing a toxicant for the protection of underwater surfaces from fouling growth. Suitable modified vinyl acetate resins are dissolved in a water solution brought to a pH of at least about 8 by a suitable poly-functional amine. A suitable toxicant, such as cuprous oxide is dispersed in the solution, and after the addition of modifiers, the finished product is then painted onto a surface to be protected from fouling growth when immersed into the ocean. The dried coating dissolves or leaches slowly in alkaline water, such as sea water, providing constantly fresh toxicant to prevent fouling growth. Desired characteristics of the coating may be modified by adding other agents, such as defoamers, urea formaldehyde resins, to the coating solution.

Further studies on the use of heat treatment to control biofouling in seawater cooling systems

Abstract: The response of fouling organisms to simulated heat treatment regimes was tested in a flow through cooling water system conduit simulation facility at San Onofre. Results indicated that constant elevated temperature discharge conduits foul at lower rates than intakes and consequently do not have to be heat treated as often. Observations of annual growth rates of the major fouling organisms resulted in predictive growth models for Mytilus edulis and Balanus tintinnabulum. By utilizing these growth models, heat treatment can be implemented based upon actual need and intervals can be significantly extended during colder water winter periods. These studies indicate potential savings in operating costs while minimizing environmental impact, through a reduction in temperature, duration, and frequency of heat treatment operations for the control of marine fouling at coastal electric generating stations.

Characteristics of Rheinisch Brown Coals With Respect to Their Combustion and Fouling Behavior in Thermal Power Stations

Abstract: In the paper first results of a several years’ research programme into the combustion and fouling characteristics of Rheinish brown coals are given. As described, fouling of the heat transfer surfaces causes severe difficulties for power station operation. The deposit formation is strongly dependent on both the composition of the inherent ash of the fuel and the extraneous impurities. The phenomenon of fouling can be influenced by operating parameters like excess air level and mixing between fuel and combustion air. The temperature of the heat receiving surface as well as its geometry play an important role.

Fouling control means fuel savings for the u.s. navy

Abstract: Based upon a detailed study of the subject by the Navy, the paper reviews the characteristics of fouling and describes current underwater hull cleaning and inspection methods. It discusses the interactions among fuel consumption, fouling, and the compatibility of under water cleaning methods with the antifouling paint coating on a hull.

Method for protecting ships against fouling

Abstract: To protect the underwater surfaces of a ship against fouling and corrosion, several layers of wax are applied, one layer on top of the next but each layer having a successively lower melting point and/or degree of hardness. After a certain length of time, when the outermost layer of the treated surface has become fouled or roughened in some way, it is thus possible to remove whichever layer is outermost by melting or brushing, since the treatment can be regulated such that the underlying layer(s) will not be affected.

Method for prevention of fouling and corrosion utilizing technetium-99

Abstract: The growth of organisms on the surface of a substrate in contact with water is prevented, while simultaneously preventing corrosion of such substrates. This is accomplished by a method wherein technetium metal is imbedded in, or cast, electroplated or sputtered onto the substrate, or is otherwise included in the surface layer of the substrate being used on or under water.

Studies of biofouling in ocean thermal energy conversion plants

Abstract: Efforts to extract energy from the ocean's thermal gradients by means of closed-cycle Ocean Thermal Energy Conversion (OTEC) plants require very large heat exchangers. The sea water passing through these will be heated (or cooled) by only a few degrees. Under these conditions it is feared that biological fouling (biofouling) may seriously impede heat transfer unless appropriate measures are taken. There exists surprisingly little data on biofouling under conditions approximating those expected to exist in an OTEC heat exchanger. For these reasons we have undertaken a study of biofouling in simulated OTEC heat exchangers. Currently, the effect of fouling on the heat transfer coefficient is being investigated as a function of the material used and water velocity. Next, the effectiveness of several means of biofouling prevention will be determined. Later stages of the study will include investigation of variation with a number of other phenomena important to OTEC design and operation.

Recent developments in antifoulings

Abstract: Largely as a result of increasing fuel costs, detailed investigation has recently been carried out on the problem of controlling the growth of fouling on the underwater hulls of ships. The biology of fouling organisms has been extensively studied and there is now a much better understanding, particularly of algal fouling. Fouling is an extreme aspect of the general problem of hull roughness which develops as a consequence of the traditional approaches to underwater hull maintenance. It is suggested that the practice of cleaning and repainting at frequent intervals, using traditional materials, does not provide the ideal answer either in terms of fouling control or long-term control of roughness. The more recent approaches of diffusion control by hydrophilic varnishes, the introduction of scrubbable coatings, and self-polishing copolymer antifouling systems give an indication of the effort that the marine coatings industry has made towards providing improved ship performance. Order from: BSRA as No. 47,359.

Prevention of foulingof sea life

Abstract: PURPOSE:To prevent the fouling of sea life by covering the surface of a solid substrate with water-swelling urethane gel composition containing a anti-fouling agent, thereby controlling the release of the anti-fouling agent to an adequate rate.

Protective Coatings and Antifouling Paint that can be Applied Underwater

Abstract: Protective coatings and antifouling paints have been developed that can be applied by brush, roller, or plastic applicator to underwater surfaces. Field studies to date indicate that steel surfaces can be protected from corrosion and marine fouling using these products for at least 1 1/2 years. Field testing to determine surface preparation requirements for underwater coating showed that surface preparation by abrasive blasting is best, but that power wirebrushing or waterblasting may provide satisfactory surfaces for coating underwater. All of the formulations containing organotin biocides displayed some degree of resistance to marine fouling and those with 6-percent tin compared quite favorably with the standard Navy copper-based antifouling paint used for comparison purposes. The new formulations can be used to repair damaged coatings or restore fouling resistance on waterfront and offshore structures and on hulls of ships without their removal or drydocking, thus resulting in considerable savings in time or money.

Titanium solves corrosion problems in petroleum processing

Abstract: Titanium answers many severe corrosion problems caused by sulfides, chlorides, and other corrodents in refinery products and cooling water. Consequently, the metal is used in many refinery processes, the main application being heat exchanger tubing. Ti resists corrosion because a stable, protective, strongly adherent film of TiO/sub 2/ forms instantly when a fresh surface is exposed to air or moisture. The potential--pH equilibrium diagram for the Ti--H/sub 2/O system at 25C is discussed, and the idea of anodic protection is explained. Corrosion resistance can be increased by thickening the oxide film, adding oxidizing agents or certain multivalent metal ions which passivate Ti, or impressing a direct current (anodic protection). Because of its high hardness, smooth surface, and resistance to corrosion, Ti resists fouling or deposit buildup in most environments. In general, Ti failures fall into one of three categories: crevice corrosion, pitting, and cracking. Many applications in the chemical process industries involve high-temperature brines; the use of Ti is limited because of its susceptibility to crevice corrosion. Such applications can be handled by an alloy designated Ti-Code-12, which contains 0.3 Mo and 0.8 Ni. 3 figures, 1 table. (RWR)

Removal of sodium from Illinois coal by water extraction

Abstract: Sodium, a relatively abundant element in Illinois coal, is reported to cause fouling of utility boiler heat exchange surfaces. Distilled water extraction of 22 Illinois coal samples resulted in average removal of more than 50% of their included sodium. Chlorine was the dominant anion. Extraction rate conformed to Fick's law of diffusion. Extraction with hot water increased both the rate and maximum amount removed. A commercial-scale countercurrent staged process can be envisioned as technically feasible.

Repellents against marine fouling animals

Abstract: PURPOSE:Polyoxyethyleneether repellents which are effective especially against bivalves such as blue mussels and are readily biodegradable

Way of purifying exhaust gas

Abstract: PURPOSE:To remove micro-grains efficiently and economically regardless of the kind of fouling substance,and to make granular fouling substance in exhaust gas condense into moisture and to make the granulars larger.