295
CHAPTER 8
HEAT EXCHANGERS,
VAPORIZERS, CONDENSERS
Joseph W. Palen
Consultant
Eugene, Oregon
1 HEAT EXCHANGER TYPES AND
CONSTRUCTION
295
1.1 Shell and Tube Heat Exchangers
295
1.2 Plate-Type Heat Exchangers
299
1.3 Spiral Plate Heat Exchangers
299
1.4 Air-Cooled Heat Exchangers
300
1.5 Compact Heat Exchangers
301
1.6 Boiler Feedwater Heaters
301
1.7 Recuperators and Regenerators
301
2 ESTIMATION OF SIZE AND
COST
302
2.1 Basic Equations for Required
Surface
302
2.2 Mean Temperature Difference
303
2.3 Overall Heat-Transfer Coefficient 304
2.4 Pressure Drop
304
3 RATING METHODS
305
3.1 Shell and Tube Single-Phase
Exchangers
305
3.2 Shell and Tube Condensers
308
3.3 Shell and Tube Reboilers and
Vaporizers
312
3.4 Air-Cooled Heat Exchangers
316
3.5 Other Exchangers
318
4 COMMON OPERATIONAL
PROBLEMS
318
4.1 Fouling
319
4.2 Vibration
320
4.3 Flow Maldistribution
321
4.4 Temperature Pinch
322
4.5 Critical Heat Flux in Vaporizers
322
4.6
Instability
323
4.7
Inadequate Venting, Drainage,
or Blowdown
323
5 USE OF COMPUTERS IN
THERMAL DESIGN OF
PROCESS HEAT EXCHANGERS
324
5.1
Introduction
324
5.2
Incrementation
324
5.3 Main Convergence Loops
324
5.4 Rating, Design, or Simulation
326
5.5 Program Quality and Selection
327
5.6 Determining and Organizing
Input Data
327
NOMENCLATURE
330
REFERENCES
332
1 HEAT EXCHANGER TYPES AND CONSTRUCTION
Heat exchangers permit exchange of energy from one fluid to another, usually without per-
mitting physical contact between the fluids. The following configurations are commonly used
in the power and process industries.
1.1 Shell and Tube Heat Exchangers
Shell and tube heat exchangers normally consist of a bundle of tubes fastened into holes,
drilled in metal plates called tubesheets. The tubes may be rolled into grooves in the tube-
sheet, welded to the tubesheet, or both to ensure against leakage. When possible, U-tubes
are used, requiring only one tubesheet. The tube bundle is placed inside a large pipe called
a shell, see Fig. 1. Heat is exchanged between a fluid flowing inside the tubes