Biological fouling often presents as a dark green to brownish slime on the surface of the plate. It has been discussed why the result of the use of a fixed fouling factor at the design stage does not solve, and in some cases exacerbates, the fouling problem for refinery operators. In the early years, only heat exchangers with specific fouling could be cleaned properly. The purpose of this guideline is to consider the influence of fouling of heat transfer surfaces as it affects waterchilling evaporators and watercooled condensers used in the air conditioning and refrigeration industry. Fouling layers with a thickness of 3 mm are indicated in dark grey, and with a thickness of 1 mm in light grey. Lets look at what heat exchanger fouling factors are and what choices the engineer has regarding them. These units are used to cool andor condense process streams with ambient air as the cooling medium rather than water. Fouling investigation of brazed plate heat exchangers. This article is primarily devoted to the fouling of industrial heat exchangers, although the same theory is generally applicable to other varieties of fouling. A risk based heat exchanger analysis subject to fouling part ii. The result is up to 30% higher efficiency and reduced fouling for reliable, costeffective performance. It reduces the heat transfer and decreases the overall thermal efficiency of the unit.
Pdf on sep 26, 2012, hassan alhaj ibrahim and others published fouling in heat exchangers find, read and cite all the research you need on. R sekulib university of kentucky introduction a heat exchanger is a device that is used for transfer of thermal energy enthalpy between two or more fluids, between a solid surface and a fluid, or between solid particulates and a. Since all heat exchangers considered in this experiment have a single pass for both the hot and cold fluids, the discussion below is limited to singlepass heat exchangers. The consequences of fouling accumulation include not only the economic loss, but heat transfer efficiency degradation, high flow resistance and pressure drops, and increased safety hazards, such as. Aircooled heat exchangers are second only to shellandtube exchangers in frequency of occurrence in chemical and petroleum processing operations.
Qualitative dependence of the fluid temperature on position inside a singlepass heat exchanger is shown in fig. What is a fouling factor in shell and tube heat exchangers. C4 fouling of heat exchanger surfaces springerlink. Haque eat exchanger fouling or scaling are general terms that involve the deposition of extraneous material on the heat transfer surface of a heat exchanger. Another form of fouling is corrosion and other chemical fouling. Fouling mitigation using helixchanger heat exchangers. Apr 18, 2016 lets look at what heat exchanger fouling factors are and what choices the engineer has regarding them. In several cases the heat exchangers were chemically cleaned after running. Heat exchanger fouling and cleaning vii, july 1 6, 2007, tomar, portugal fouling monitoring and cleaning optimisation in a heat exchanger network of a crude distillation unit andrea heins 1, ramon veiga 1, carlos ruiz 2, andres riera 2 1 argentinean technology center cta repsol ypf. Pdf 20 fouling of heat transfer surfaces semantic scholar. Optimizing the acid dissolution of sodalite scale, sebastien fortin and raymond breault article pdf.
After the specified time period of running oncethrough lake water through the heat exchangers, the exchangers were taken off line. For shell and tube heat exchanger, the common method is to use fouling factors. The heat transfer performance and efficiency decreases due to the fouling of the heat exchanger plates and tubes. The outside fouling factor, based on tube surface, must be divided by the surface ratio, bare to finned which results in a very small figure, negligible in most cases. Fouling is ubiquitous and generates tremendous operational losses, not unlike corrosion. A risk based heat exchanger analysis subject to fouling part. Fouling factors in heat exchangers resources hrs heat. Pdf fouling phenomenon and its effect on heat exchanger. Of the three, micro fouling is the one that is usually more difficult to. Introduction hex are designed for thermal processes to work within allowable pressure drop limits and for. Combining each of these resistances in series gives. Fouling is the accumulation of unwanted material on solid surfaces. A large amount of fouling in the flow areas of the heat exchangers could be seen for some conditions. In cooling technology and other technical fields, a distinction is made between macro fouling and micro fouling.
The fouling problem exists in more than 90 percent steinhagen r, 1993 of heat exchangers. Crystallization fouling under subcooled flow boiling conditions 6. In fact, fouling has been recognised for a in fact, fouling has been recognised for a long time, and research on heat exchanger fo uling was. Aircooled heat exchangers, such as that shown in fig. Heat exchangers 73 individual thermal resistances of the system.
This standard does not apply to heat exchangers used for change of phase or nonliquid heat transfer applications. It is also the only welded heat exchanger where all channels, both hot and cold, can be fully cleaned using a hydro jet, bringing performance back to 100% after every cleaning. How to achieve more compact heat exchangers high thermal efficiency balance between enhanced heat transfer and accompanied pressure drop material issues especially for high temperature applications manufacturing methodology fouling nonsteady operation. Chenoweth jm 1987 general design of heat exchangers for fouling conditions. Another large section is designed to give information on both online and offline cleaning of heat exchangers. The exchange can take place between a process stream and a utility stream cold water, pressurized steam, etc, a process stream and a power source electric heat, or between two. In todays air conditioning and refrigeration industry section 1. Fouling of heat exchangers is an issue because it reduces heat transfer efficiency and increases pressure drop and hence affects the economy of a processing plant toyoda and others 1994.
This type of fouling is called the biological fouling. Heat exchanger fouling and estimation of remaining useful life. A heat exchanger is a device that is used to transfer thermal energy enthalpy between two or more fluids, between a solid surface and. Scale formation in shell and tube heat exchangers 7. Further research on the problem of fouling in heat exchangers and practical methods for predicting the fouling.
Fouling of heat exchangers is an issue because it reduces heat transfer efficiency and increases pressure drop and hence af fects the economy of a processing plant toyoda and others. Bott fouling of heat exchangers chemical engineering. Bott fouling of heat exchangers chemical engineering monographs. Our gasketed plate heat exchanger range is the result of decades of experience, research and development in heat transfer technology. The fouling factor represents the theoretical resistance to heat flow due to.
Fouling of dod shipboard heat exchangers is a chronic and costly operating problem that requires significant maintenance. The fouling materials can consist of either living organisms or a nonliving substance inorganic or organic. Extended surfaces glossary bibliography and suggestions for further study summary the formation of crystalline deposits on the heat transfer surfaces is one of the main. Costs due to additional fuel consumption and maintenance, loss of production, etc. Fouling of heat transfer surfaces occurs in most chemical and process industries, including oil refineries, pulp and paper manufacturing, polymer and fiber production, desalination, food processing, dairy industries, power generation and energy recovery. For other types of heat exchangers, excess heat transfer area is often used. The cleaning of fouled heat exchangers often presents a significant challenge to the maintenance and operation of chemical, petroleum and food processes. Minimizing fouling in spiral heat exchangers at a bctmp mill. A risk based heat exchanger analysis subject to fouling.
The foulant layer imposes an additional resistance to heat transfer and the narrowing of the flow area, due to the presence of deposit, results in an increased velocity for a given volumetric flow rate. Of such factors some may be related to the feed properties such as its chemical nature, density, viscosity, diffusivity, pour and cloud points, interfacial properties and colloidal stability factors. Fouling of heat exchangers in processing industries is a chronic operating problem. Aircooled heat exchangers an overview sciencedirect. Fouling factor is a numerical allowance for possible coating of the tubes by dirt or precipitate in the heated or cooled fluid. Pdf the paper describes the mechanisms in the development of biofouling layers initial surface conditioning, microbial transport and. Nonetheless, heat exchanger fouling remains today one of the major unresolved problems in thermal science, and prevention or mitigation of the fouling problem is still an ongoing process. Even when cooling water is available aircooled exchangers are sometimes favored for economic or operational reasons. The thickness of the tube is normally small enough with sufficiently high conductivity that this factor. While the installation of excess heat transfer surface may extend the operation time of heat exchangers, it provides no remedy against the deposition of dirt.
Fouling of heat exchangers me485 heat exchanger and steam generator design fouling accumulation of undesirable deposit on a hex surface. Introduction to heat exchangers bengt sunden lund institute of technology. Poorly controlled cooling tower water can cause significant fouling issues in all heat exchangers in the closed loop circuit. Fouling in heat exchangers causes gradual impairment of its performance.
Fouling tends to degrade the performance of heat exchangers by decreasing the heat transfer coefficient and increasing the airside pressure drop across the heat exchangers. Costs due to overdesign, additional fuel consumption and maintenance, loss of production, etc. In this section several limitations of the traditional tema fouling factor approach to the design of heat exchangers and heat exchanger networks are highlighted. Method to detect fouling in heat exchangers oddgeir gudmundsson1, olafur petur palsson1, halldor palsson1, sylvain lalot2 1faculty of industrial engineering, mechanical engineering and computer science, university of iceland 2lme, university of valenciennes and hainaut cambrsis, le maont houy, france abstract heat exchangers are frequently used in district heating. Traditionally rf is computed from the difference between the two overall thermal resistances takemoto, 1997. Fouling factors in heat exchangers the fouling factors to be used in the design of heat exchangers are normally specified by the client based on their experience of running the plant or process. Marner 1990 observed the gasside fouling of heat exchangers caused by unclean fluid streams in applications like heat recovery systems and boilers. Although both deposits commonly occur together, deposits from fouling. There is a high degree of turbulence in plate heat exchanger, which increases the rate of deposit removal and, in effect, makes the plate heat exchanger less prone to fouling. For example, one estimate puts the losses due to fouling of heat exchangers in industrialized nations to be about 0.
Boost your efficiency and sustainability with alfa laval next generation plate heat exchangers. However, fouling is a selffulfilling prophecy and the selection of fouling factors or excess area must be done carefully. Advice on the selection, design, installation and commissioning of heat exchangers to minimise fouling is given. Heat exchanger fouling and cleaning challenges and. Fouling and scaling issues in heat exchangers and condensers. The manner in which fouling and fouling factors apply to plate exchangers is different from tubular heat exchangers. The fouling factors to be used in the design of heat exchangers are normally specified by the client based on their experience of running the plant or process.
Budair department of mechanical engineering, king fahd university of petroleum and minerals, dhahran 31261, saudi arabia abstract. By many, fouling is considered the single most unknown factor in the design of heat exchangers. The purpose of these publications is to provide improved understanding of the science and to give. Minimizing fouling in spiral heat exchangers at a bctmp mill by m. Pdf fouling of heat exchangers hamza shafiq academia. Minimized fouling allows compabloc to operate with cleaning intervals substantially longer than traditional heat exchangers, reducing lifetime maintenance costs. Heat exchangers may also be fouled by the growth of algae in warm fluids. Fouling represents additional resistance to heat transfer and causes the rate of heat transfer in a heat.
Heat exchangers heat exchangers are used to transfer heat between two sources. The last refinery process where heat exchangers are employed as feedeffluent heat exchangers is the reformer unit. The pulp mill has observed the formation of porcelain like hard scales on the surface of the heat exchanger. Scale formation in plate and frame heat exchangers 8. The fouling of heat exchangers may be defined as the accumulation of unwanted deposits on heat transfer surfaces. This biological fouling is best controlled via quality water treatment at the cooling tower. It has been discussed why the result of the use of a fixed fouling factor at the design stage does not solve, and in some cases exacerbates, the fouling. Heat exchanger fouling in phosphoric acid evaporators evaluation of field data, r. Fouling of heat exchangers chemical engineering monographs advisory editor. Aircooled heat exchangers an overview sciencedirect topics. Fouling can occur inside the tubes or outside the tubes. One of the best books for introduction of fouling in heat exchangers.
Despite efforts in the design of processes and hardware to minimize fouling, eventually the intricate interior surfaces of the exchanger. Sphere resting on a plate for two flat 48 fouling of heat exchangers determined by. The fouling of heat exchangers in processing industries is a chronic operating problem. Alfa laval gasketed plate heat exchangers are the most costeffective solution. Fouling of heat exchangers heat exchanger heat transfer. A large part of the text is devoted to the use of chemical and other additives to reduce or eliminate the problem of fouling. Introduction hex are designed for thermal processes to work within allowable pressure drop limits and for a specified time period. If uncontrolled, levels of fouling can negate any benefits produced by careful heat exchanger design.
In the co2 scrubbing process three plate heat exchangers are switched in parallel, two in operation a and b and one in standby c. Fouling in the feedeffluent heat exchangers can decrease the outlet preheat temperature of naphtha causing more fuel consumption in the furnace andor reduction in the naphtha flow rate. Esdu heat exchanger fouling case study heat exchanger fouling esdu reveals new developments in the reduction of crude oil fouling the source for critical information and insighttm buildup of dirt deposits, or fouling, on the metal surfaces of petrochem plant heat exchangers is a major economic and environmental problem worldwide. Heat exchanger fouling and cleaning conference series. Fouling and scaling issues in heat exchangers and condensers the problems related to heat exchanger fouling and scaling and their economic and environmental impact are commonly known as fouling and include both organic deposits as well as inorganic deposits also referred to as scaling. In fact, fouling has been recognised for a long time, and research on heat exchanger fouling was conducted as early as 1910 and the first practical application of this research was implemented in the 1920s. The factors that govern fouling in heat exchangers are many and varied. Coolingwater fouling in heat exchangers sciencedirect. The thermal and hydraulic performance of heat exchangers decreases continuously with time due to fouling, which is defined as the formation of deposits on heat transfer equipment. Heat exchanger fouling of course reduces the opportunity for heat recovery with its.
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