Fired heaters the selection of a heat exchanger depends on many factors including capital and operating costs, fouling, corrosion tendency, pressure drop, temperature ranges, and safety issues tolerance to leakage. Apr 23, 2016 design and operation of heat exchangers are still to a major extent determined by the processrelated formation of deposits on the heat transfer surfaces, i. In fact, fouling has been recognised for a long time, and research on heat exchanger fo uling was conducted as early as 1910 and the. Fouling in heat exchangers 61 detailed analysis of deposits from the heat exchanger may provide an excellent clue to fouling mechanisms. Since the fluid flows continuously in one single channel the force of the fluid acts against. Fouling, not only for preheat exchangers of crude distillation units, but also for other units, is one of the most serious operating problem and source for energy loss in oil refineries. The consequences of fouling accumulation include not only the. Costs due to overdesign, additional fuel consumption and maintenance, loss of production, etc. Fouling and reduced heat transfer in heat exchangers. Examples of components that may be subject to fouling and the corresponding effects of fouling. Engineering page heat exchangers typical fouling factors. Tm is the log mean temperature difference given as t t. In order to consider heat exchanger fouling, specification of the fouling factor for each particular unit is allowed. Pdf heat exchangers as a heat transfer device has gained wide applications across different levels of domestic and industrial setups.
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. Heat exchanger fouling and estimation of remaining useful life. Heat exchanger enhancement must always satisfy the primary goal of providing a cost advantage relative to the use of a conventional heat exchanger6. Fouling of heat exchangers occurs in a variety of different industries. It has extensive domestic and industrial applications. Biyearly conferences on heat exchanger fouling have been organised by. Since the thermal conductivity of such deposits is low, see table 1, their resistance to heat transfer may well exceed that of the clean fluids, resulting in significantly. An apparatus was built to study heat transfer fouling on different heat exchanger pipe surfaces by visually observing the progressive fouling deposition under the.
Other factors that should be addressed include fouling potential, reliability and safety. Heat exchanger fouling and cleaning conference series. It is very detrimental to the heat exchanger performance since it leads to a loss of its thermal duty and an increase of its pressure drop. A 2shell passes and 4tube passes heat exchanger is used to heat glycerin from 20c to 50c by hot water, which enters the thinwalled 2cmdiameter tubes at 80c and leaves at 40c. If uncontrolled, levels of fouling can negate any benefits produced by careful heat exchanger design. Nonetheless, heat exchanger fouling remains today one of the major unresolved problems in thermal science, and prevention or mitigation of the fouling problem. Heat exchangers consist primarily of bundles of pipes, tubes or plate coils. Jamialahmadi article pdf bayer process heat exchangers cleaning efficiency.
Optimizing the acid dissolution of sodalite scale, sebastien fortin and raymond breault article. 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. Fouling layers with a thickness of 3 mm are indicated in dark grey, and with a thickness of 1 mm in light grey. Fouling of a specific heat exchanger is, besides from the fouling agent. Heat exchanger fouling in phosphoric acid evaporators evaluation of field data, r.
A heat exchanger is a system used to transfer heat between two or more fluids. At some point the heat exchanger will need to be taken out of operation for cleaning. Pdf fouling of heat exchangers hamza shafiq academia. The operating time of an uncoated heat exchanger varies between 6 to 9 months depending on the season where thereafter the increase in thepressure drop to unacceptable values together with the inability to cool the. Heat exchangers are used in both cooling and heating processes. Biological fouling may be defined as the growth of living matter on heat exchanger surfaces. Fouling factors in heat exchangers resources hrs heat. In contrast to the parallel flow heat exchanger, the counter flow heat exchanger can have the hottest coldfluid temperature greater than the coldest hotfluid temperatue. Pdf fouling and cleaning of modified stainless steel plate heat exchangers processing milk products, m. C4 fouling of heat exchanger surfaces springerlink. Reverse solubility salts become less solute as the temperature increases and thus deposit on the heat exchanger surface. Pdf fouling phenomenon and its effect on heat exchanger. Materials and application techniques have been developed for.
A truly zero fouling heat exchanger must have zero fouling on the tubeside as well as on the shellside. In general, they are subject to the accumulation of contaminants, termed fouling, on the waterside of heat transfer surfaces. Heat exchanger fouling and cleaning challenges and. Heat exchanger surfaces reduces thermal efficiency, decreases heat flux, increases temperature on the hot side, decreases temperature on the cold side, induces underdeposit corrosion, increases use of cooling water. The deposits consist primarily of organic material that is predominantly.
May, 2020 advanced lowsurface energy coating materials targeted for heat exchanger fouling in a range of crude fouling services have expanded curran internationals tube coating portfolio. For shell and tube heat exchanger, the common method is to use fouling factors. Fire tube or smoke tube heat exchanger arguably, the most cleanable design is a shell and tube style heat exchanger in which the exhaust travels through the tubes with no bends. Published online coatings and some of the results will be presented in this paper. The worldwide costs, associated specifically with crude oil fouling in preheat trains were equated to around 20% of all heat exchanger fouling mullersteinhagen.
Apr 18, 2016 shell and tube heat exchanger fouling factors engineers are often faced with interoffice scheduling traditions. The following provides background information on many different types of heat exchanger enhancements. These water systems may be closed or open loop systems. Fouling detection in heat exchangers is still challenging. Heat exchanger is equipment used to transfer heat from one fluid to another. The zero fouling heat exchanger explained in this article is derived from the wellknown selfcleaning fluidized bed heat exchange technology where the selfcleaning action is only employed in the tubes. 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 phenomenon and its effect on heat exchanger. Detailed chemical analysis shows that fouling deposits formed in operating heat exchangers contain mainly inorganic material bonded by heavy hydrocarbons. Counter flow heat exchangers are the most efficient of the three types.
Pdf on sep 26, 2012, hassan alhaj ibrahim published fouling in heat exchangers find, read and cite all the research you need on researchgate. Heat exchanger fouling and cleaning challenges and opportunities. Fouling is one of the most important problems of the heat transfer equipment such as. The sondex spiral heat exchanger is a circular heat exchanger with two.
While some improvements in fouling and cleaning were observed for some of the coatings, there is. Scaling is the most common type of fouling and is commonly associated with inverse solubility salts such as calcium carbonate caco 3 found in water. The former may include bacteria, fungi or algae, while the latter includes mussels and barnacles. Chapter 5 heat exchangers faculty of engineering and. For other types of heat exchangers, excess heat transfer area is often used. May 04, 2009 coefficient of the heat exchanger is 640 wm 2 k, determine the length of the heat exchanger required to achieve the desired heating. The design, installation, commissioning and operation of heat exchangers to minimise fouling. A heat exchanger is a device that is used to transfer thermal energy enthalpy between two or more fluids, between a solid surface and a fluid, or between solid particulates and a fluid, at different temperatures and in thermal contact. Fouling of dod shipboard heat exchangers is a chronic and costly operating problem that requires significant maintenance. The phenomenon usually associated with water systems, e. Maintenance of fouled tubular heat exchangers can be performed by several. He found out that fouling agents can contain inorganic materials such as airborne dust and grit, waterborne mud and silt, as well as organic materials including biological substances and elemental carbon. Fouling of heat exchangers in processing industries is a chronic operating problem.
Extensive technical literature is available on heat exchanger design, operation and maintenance, but it is widely. The dirty truth about heat exchanger fouling heatcalc. Bott fouling of heat exchangers chemical engineering. The new heat transfer coefficient for the heat exchanger is calculated by adding the additional resistance due to fouling. 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. Awad 2011 studied the fouling of heat transfer surfaces in general. Figure 2 shows the fouling resistances for cooling water inside a plate heat exchanger in comparison with fouling resistances on the tubeside inside a shell and tube heat exchanger for the same velocity. A lot of the headache from fouling can be avoided through informed design choices. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. This section introduces the basic mechanisms of heat excahnger fouling, hx physical model, aakr and gpm with bayesian updating. However, fouling is a selffulfilling prophecy and the selection of fouling factors or excess area must be done carefully. The fouling problem exists in more than 90 percent.
Fouling resistance an overview sciencedirect topics. While we were working with a local engineer on a heat exchanger application, she asked why the office always specified a. It can be used to identify and provide valuable information about such mechanisms. The heat transfer performance and efficiency decreases due to the fouling of the heat exchanger plates and tubes. The two papers present an introduction to the relationships between flow velocity, surface temperature, heat exchanger construction materials, water quality, entering and exiting temperatures, and. Fouling of heat exchangers chemical engineering monographs advisory editor.