TEMA换热器设计.pdf

SHELL-AND-TUBE HEAT EXCHANGERS
Effectively Design
Shell-and- fbe
Heat Exchangers
Thermal design of shell-and-tub
baffles: and
Yto make the most
heat exchangers (STHES)is
nozzles
done by sophisticated computer
Other components Include tie-rods and
software. However, a good un-spacers, pass partition plates, impinge
exchange
derstanding of the underlying principles ment plate, longitudinal baffle, sealing
design software,
of exchanger design is needed to use this strips, supports, and foundation
software effectively
The Standards of the Tubular Ex
one needs to
This article explains the basics of ex-changer Manufacturers Association
changer thermal design, covering such (TEMA)(1)describe these various com-
understand STHE topics as: STHE components; classifica
ponents in detail
tion of STHES according to construction
An STHE is divided into three parts
classification
and according to service: data needed for the front head. the shell. and the rear
thermal design: tubeside design: shellside head. Figure 1 illustrates the TEMA
exchanger
design, including tube layout, baffling, nomenclature for the various construction
and shellside pressure drop, and mean possibilities. Exchangers are described by
components, tube
temperature difference. The basic equa-the letter codes for the three sections
tions for tubeside and shellside heat for example, a BFL exchanger has a bon
layout, baffling
transfer and pressure drop are well- net cover, a two-pass shell with a longitu-
nown: here we focus on the application dinal baffle, and a fixed-tubesheet rear
pressure drop, and
f these correlations for the optimum de-head
sign of heat exchangers. A followup arti
mean temperature
le on advanced topics in shell-and-tube Classification
heat exchanger design. such as allocation based on construction
terence
of shellside and tubeside fluids. use o
Fixed tubesheet. A fixed-tubesheet
multiple shells, overdesign, and fouling, heat exchanger(Figure 2)has straight
is scheduled to appear in the next issue
tubes that are secured at both ends to
Rajiv Mlukherj
tubesheets welded to the shell. The con
Components of STHES
Engineers India Ltd
struction may have removable channel
It is essential for the designer to have a covers(e.g, AEL), bonnet-type channe
good working knowledge of the mechani-covers(e.g BEM), or integral tubesheets
cal features of STHES and how they in-(e.g,, NEN
fluence thermal design. The principal
The principal advantage of the fixed
components of an STHE are
tubesheet construction is its low cost be
shell
cause of its simple construction. In fact
Shell cover.
the fixed tubesheet is the least expensive
construction type, as long as no expan
sion joint is required
channel cover
Other advantages are that the tubes can
tubesheet
be cleaned mechanically after removal of
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