Tubes fouling

Smaii-tube Tefion Chemical resistance of tubes no tube fouling. Clean fluids, condensing, cross-exchange. Low heat transfer coefficient. 2.0-4.0... 

Oil additives have been used for a number of years. They are normally introduced as suspensions of metallic oxides or other salts such as Mg (OFI)2, Ca (OH)2, AI2O3, etc., in fuel oil or water. Use of these compounds has been shown to be uneconomic, ineffective and to cause problems, i.e., tube fouling, increased soot blower usage, solids disposal, etc., rather than cure them. 

Teflon no tube fouling. cross-exchange. coefficient. 2.0-4.0... 

This tube has a ratio of outside to inside surface of about 3.5 and is useful in exchangers when the outside coefficient is poorer than the inside tube coefficient. The fm efficiency factor, which is determined by fm shape and size, is important to final exchanger sizing. Likewise, the effect of the inside tube fouling factor is important to evaluate carefully. Economically, the outside coefficient should be about V5 or less than the inside coefficient to make the finned unit look attractive however, this break-even point varies with the market and designed-in features of the exchanger. 

In a forced-draft air cooler, cool air is blown through the underside of the fin tube bundle. In an induced-draft air cooler, cool air is drawn through the underside of the fin tubes. Either way, road dust, dead moths, catalyst fines, and greasy dirt accumulate along the lower row of tubes. As the tubes foul, they offer more resistance to the airflow. However, note that... 

The total airflow discharged by the fan remains constant, regardless of the fin tube fouling. 

This is an exchanger that was designed to operate with a low tube-side velocity. Note how there is a rapid loss in the heat-transfer coefficient, as the tubes foul and plug, as a result of low velocity. The loss in heat-transfer coefficient U stops only when the terminal-tube velocity is reached in the unplugged tubes. 

The dimorphs pyrite (FeS2) and marcasite (FeS2) are the dominant sulfide minerals in coal pyrite is the more abundant. Pyrite and marcasite have different crystal forms pyrite is isometric and marcasite is orthorhombic. These two minerals are readily observed and, to some degree, easily removed as well as being especially interesting because they contribute significantly to the total sulfur content that causes boiler tube fouling, corrosion, and pollution by emission of sulfur dioxide when coal is burned (Beer et al., 1992). 

Among the interesting conclusions drawn from the study, the authors found that the magnitude of the effect of condenser tube fouling on unit output is sensitive to ... 

Curlett, P.L. and Impagliazzo, A.M., 1981, The impact of condenser tube fouling on power plant design and enconomics, in Chenoweth, J.M. and Impagliazzo, A.M. eds. Fouling in Heat Exchange Equipment. HTD, Vol. 17, ASME. 

An important observation made by Atkins [1962] was that in fired heater tubes fouling deposits appeared as two layers an outer porous (or tarry layer) and a hard crust of deposit next to the tube wall (see Fig. 11.6). 

Tubes fouled on the tube side Tubes fouled on the shell side Plugged tubesheet Shell leaks to the atmosphere Cracked tube Tubesheet leak... 

The feature of the fluidized-bed combustor is the (relatively) low operating tanperature, which ensures that (1) the ash does not fuse (melt) and can be easily removed and disposed off in solid form and (2) there is a lower amount of boiler tube fouling and corrosion. 

Fouled convective section. For oil-fired healers with finned convective tubes, fouling may reduce draft. A gradual loss of draft probably means the convective section needs to be water washed. Deposits from the burnt fuel oil have built up around the lubes thick enough to restrict the passage of flue gas. The increased pressure drop through the convective section reduces the vacuum in the firebox. Permanently installed soot blowers are one answer to this problem. 

Refinery management, 524-525 Refinery metallurgy, 415-429 metals used in refinery service, 415-416 stainless steel nomenclature, 416-418 corrosion resistance, 417, 419—426 embrittlement dangers, 426 rigorous service, 426-427 heat-exchanger tube fouling, 428 troubleshooting problems, 428... 

Heat transfer rates are calculated to the catalyst tube from the firebox flue gas, through the tube wall, tube fouling, and inside tube film to the bulk fluid, as well as from the bulk fluid to the catalyst surface. As reported in the literature, the catalyst pellets are assumed to have a uniform temperature, since very little resistance to intra-pellet heat transfer exists. 

Coolant filtering required to prevent fuel tube fouling... 

The use of organic coolant (terphenyl mixtures) in a D20-moderated system has been investigated in the Canadian WR-1 research reactor at Whiteshell, Manitoba. Experience has confirmed that zirconium-based alloys are suitable for extended operation in organic coolant provided there is careful control of the coolant chemistry to prevent excessive hydrogen uptake and fuel tube fouling. 

Corrosion allowance depends on the process fluid. It is applicable to all surfaces of tube bundle exposed to process fluid, except tubes. Foul lug factor also depends on the process fluid and flow velocity through the tubes. 

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