Resistance fouling

City or Well Water (Such as Great Lakes) River Water . 001. 001. 002. 002 

Reformer charge Reformer effluent Hydrocracker charge effluent Recycle gas 

Caustic liquid, Salt-free 20% (steel tube) 3-8 0.0005  

High temperature cracking or coking, polymer buildup 0.02-0.06  

Standards of Tubular Exchanger Manufacturers Association, Inc., (TEMA) 7th Ed. 

Condensing Boiling Refrigerants (vapor condensing and liquid cooling) 

Refrigerants (continued) Ammonia Propylene Chloro-fluoro-refrigerants Caustic liquid, 

50% (nickel tube) 73% (nickel tube) Gases (Industrially clean) 

Air (compressed) Flue Gases Nitrogen Hydrogen Hydrogen (saturated with water) 

Polymerizable vapors with inhibitor High temperature cracking or coking, polymer buildup Salt Brines (125 F. max.) Carbon Dioxide (Sublimed at low temp.) 2 4 0.003 0.02- 0.003 0.002 0.2- 1-0.03 -0.06 0.004 0.003 -0.3 

Ludwig, E. E., Applied Process Design for Chemical and Petrochemical Plants, 2nd Ed., Vol. 3, Gulf Publishing Co., 1983. 

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Hollow-fiber designs are being displaced by spiral-wound modules, which are inherently more fouling resistant, and require less feed pretreatment. Also, thin-film interfacial composite membranes, the best reverse osmosis membranes available, have not been fabricated in the form of hoUow-fine fibers. 

Work in connection with desahnation of seawater has shown that specially modified surfaces can have a profound effect on heat-transfer coefficients in evaporators. Figure 11-26 (Alexander and Hoffman, Oak Ridge National Laboratory TM-2203) compares overall coefficients for some of these surfaces when boiling fresh water in 0.051-m (2-in) tubes 2.44-m (8-ft) long at atmospheric pressure in both upflow and downflow. The area basis used was the nominal outside area. Tube 20 was a smooth 0.0016-m- (0.062-in-) wall aluminum brass tube that had accumulated about 6 years of fouhng in seawater service and exhibited a fouling resistance of about (2.6)(10 ) (m s K)/ J [0.00015 (fF -h-°F)/Btu]. Tube 23 was a clean aluminum tube with 20 spiral corrugations of 0.0032-m (lA-in) radius on a 0.254-m (10 -in)... 

An interesting effect is sometimes observed when cupronickels are galvanically coupled to less noble materials. The corrosion rate of the active metal is increased and the corrosion rate of the cupronickel is diminished, as expected. The diminished corrosion rate of the cupronickel can, however, diminish its fouling resistance since reduced production of copper ions lowers toxicity to copper-ion-sensitive organisms. 

Tables 1 and 2 have fouling resistances suggested by TEMA. In Table 3 they are from Ludwig. ...

Transfer Rate - Service Clean Fouling Resistance Shell Tubes... 

A, = area of inside of. surface for heat transfer, such as coil, flat surface, or other barrier, sq ft/ft h = inside heat transfer fluid side coefficient, in coil, flat plate, or otlier barrier, Btu/hr/sq fl/°F ro = fouling resistance (factor) associated wTth fluid on outside (tank process side) of heat transfer... 

Figure 10-39. Chart for determining U-dirty from values of U-clean and the sum of tube-side and shell-side fouling resistances. Note Factors refer to outside surface. Fouling resistance is sum of (r + rj, as hr-ft -°F/Btu. (Used by permission Standards of Tubular Exchanger Manufacturers Association 1959 and 1968. Tubular Exchanger Manufacturers Association, Inc. All rights reserved.)...

Fouling Resistances For Industrial Fluids Fouling Resistances for Natural Gas-Gasoline Processing Streams... 

For fouling resistances of significant magnitude, a correction is usually made to convert all values to the outside surface of the tube see Equation 10-37. Sometimes only one factor is selected to represent both sides of the transfer fouling films or scales. 

In the tables the representative or typical fouling resistances are referenced to the surface of the exchanger on which the fouling occurs—that is, the inside or outside tubes. Unless specific plant/equipment data represents the fouling in question, the estimates in the listed tables are a... 

Zanker has presented a graphical technique for determining the fouling resistance (factor) for process or water fluid systems based on selected or plant data measurements, as shown in Figures 10-43A, 10-43B, and 10-43C. The design determination procedure presented by ZankeD is quoted here and used by permission from Hydrocarbon Processing... 

Figure 10-41. For many cooling waters, the fouling resistance increases rapidly, then decreases, and finally approaches an asymptotic value. (Used by permission Knudsen, J. G., Chemical Engineering Progress. V. 87, No. 4, 1991. American Institute of Chemical Engineers. All rights reserved.)...

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