Fouling heat exchanger pdf

The fouling of heat exchangers in processing industries is a chronic operating problem. The sondex spiral heat exchanger is a circular heat exchanger with two. A plate heat exchanger, phe, is a compact heat exchanger where thin corrugated plates some 0. If uncontrolled, levels of fouling can negate any benefits produced by careful heat exchanger design. Fouling on the surface of heat exchanger additionally acts as a hindrance to the flow of air causing an increase in the pressure drop, resulting in reduced air flow, therefore decreasing the heat transfer indirectly. While some improvements in fouling and cleaning were observed for some of the coatings, there is only, to the authors knowledge, the alfa. Mtd mean temperature difference normally, this equation is solved for the surface area or a, since the heat load is known, and the overall heat transfer coefficient and the mtd can be calculated, based on known information.

Heat exchanger fouling and cleaning challenges and. Fouling layers with a thickness of 3 mm are indicated in dark grey, and with a thickness of 1 mm in light grey. Final program heat exchanger fouling and cleaning 2017. Pdf fouling phenomenon and its effect on heat exchanger. The foulant layer imposes an additional resistance to heat transfer and the narrowing of the flow area, due to the presence of deposit, results. 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. Fouling of dod shipboard heat exchangers is a chronic and costly operating problem that requires significant maintenance. The fouling factor represents the theoretical resistance to heat flow due to. In heat transfer equipment, where the primary concern is often the effect of fouling on heat transfer, fouling can be quantified by the increase of the resistance to the flow of heat m 2 kw due to fouling termed fouling resistance, or by development of heat transfer coefficient wm 2 k with time. Heat exchangers are designed to handle fluids, either gases or liquids. Fouling of heat transfer surfaces is one of the most important problems in heat transfer equipment. The fouling layer on the heat transferring surface forms an additional heat conducting resistance and reduces the efficiency of the heat exchanger.

Pdf fouling of heat transfer surfaces researchgate. Kavanaugh and rafferty 1997 describe several other methods for coping with heat exchanger fouling including permanently installed brush systems. Table 811 lists the uvalues for various types of equipment, and fouling factors of some flowing media are shown in table 812. This weeks monday morning minutes post explores heat exchanger fouling factors and suggests a couple of rules of thumb to follow. Fouling factors in heat exchangers resources hrs heat. Heat exchanger fouling and estimation of remaining useful life. In the co2 scrubbing process three plate heat exchangers are switched in parallel, two in operation a and b and one in standby c. Comparison of crude oil fouling using two different probes, a.

The fouling resistances inside the phe are much lower than that inside the shell and tube heat exchanger. Bott fouling of heat exchangers chemical engineering monographs. However, one major phenomenon that limits heat exchanger performance is attributed to fouling. Fouling is generally defined as the accumulation and formation of unwanted materials on the surfaces of processing equipment, which can seriously deteriorate the capacity of the surface to transfer heat under the temperature difference conditions for which it was designed. 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. Table 8 illustrates a heat exhanger specification form. The heat transfer performance and efficiency decreases due to the fouling of the heat exchanger plates and tubes. Its single channel geometry and turbulence, with resulting high shear stress, dramatically reduce fouling and make shes to a large extent selfcleaning. Fouling and scaling heat exchangers buffalo brewing blog. Fouling and fouling mitigation on heat exchanger surfaces. Therefore, it acts as a resistance to heat transfer resulting in heat exchanger performance degradation. This increases the required heat transfer area for a given production capacity as well as the energy demand and thus ultimately increases co 2 emission.

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. One of the most misunderstood items in the heat exchanger schedule is the fouling factor. Based on this, various studies and approaches have focused on reduction, elimination and mitigation. This increases the required heat transfer area for a given production capacity as well as the. Their fouling tendency and potential cleanup, george f. Fouling characteristics of a light australian crude oil, zaid s.

Reverse solubility salts become less solute as the temperature increases and thus deposit on the heat exchanger surface. In todays air conditioning and refrigeration industry section 1. It is to be expected therefore, that the flow of the fluids through the exchanger will influence to a lesser or greater degree, the laying down of deposits on the surfaces of heat. Fouling may be classified by mechanism into six basic categories. Extensive technical literature is available on heat exchanger design, operation and maintenance, but it is widely.

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. Heat exchangers are used in numerous steps throughout the process. Effect of the flow fluid type on the fouling to show the effect of the flow fluid type on the fouling resistance, chenoweth 7 collected data from over 700 shell andtube heat exchangers. Different types of heat exchangers in addition, the overall heat transfer equation for the exchanger must be solved simultaneously.

Fundamentally, fouling may be characterized as a combined, unsteady state, momentum, mass and heat transfer. It has extensive domestic and industrial applications. 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. Heat exchanger is equipment used to transfer heat from one fluid to another. While this may help the heat transfer, the small gaps between fins are magnets for fouling. Calculate the required heat transfer rate, q, in btuhr from specified information about fluid flow rates and temperatures. Kazi department of mechanical and materials engineering, faculty of engineering, university of malaya, kuala lumpur, malaysia 1. The dirty truth about heat exchanger fouling heatcalc. 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. The theory behind heat transfer plate heat exchangers. Analysis and steps to mitigate heat exchanger fouling in an aromatics plant, shinji isogai and mitsutaka nakamura article pdf. This unique and comprehensive text considers all aspects of heat exchanger fouling from the basic science of how surfaces become fouled to very practical ways of mitigating the problem and from mathematical modelling of different fouling mechanisms to practical methods of heat exchanger. While significant progress has been made in the mitigation of heat exchanger fouling, the challenge to reduce its impact on heat exchanger performance is still enormous.

Costs due to additional fuel consumption and maintenance, loss of production, etc. Engineers are often faced with interoffice scheduling traditions. Heat transfer theory the natural laws of physics always allow the driving energy in a system to flow until equilibrium is reached. Antifouling treatment for heat exchangers technologies. Factors governing the selection of process fluids in the tube and shell sides of an exchanger are illustrated in table. Pdf 20 fouling of heat transfer surfaces semantic scholar. U overall heat transfer coefficient, btuhrsq ft of a surface area, sq ft. Heat exchanger fouling and estimation of remaining useful life tutpol ardsomang1, j. Fouling resistance an overview sciencedirect topics. In spite of the fact that the large surface in the heat exchangers cools down the heated, liquid foodstuffs again quickly, microbes can remain stuck in the numerous grooves and recesses of the heat exchanger, persistent biofilms can form or sticky residues accumulate. Smooth tube over finned tube many heat exchangers will use fins to increase the heat exchanger area. Make an initial estimate of the overall heat transfer coefficient, u, based on. 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. Fouling refers to any change in the solid boundary separating two heat transfer fluids, whether by dirt accumulation or other means, which results in a decrease in the rate of heat transfer occurring across that boundary.

Fouling mitigation of a reboiler by optimization of additive and operating conditions, shinji isogai and mitsutaka nakamura article pdf. The fouling of heat exchangers may be defined as the accumulation of unwanted deposits on heat transfer surfaces. Introduction heating or cooling of one medium by another medium is performed in a heat exchanger. Traditionally rf is computed from the difference between the two overall thermal resistances takemoto, 1997. Scrubbing and scouring effects if fouling starts to occur in the heat transfer channel of an she, the crosssection of. Disassembly and cleaning of bolted plate frame heat exchangers is also another maintenance option for fouling mitigation.