Page 382 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

350 Applied Process Design for Chemical and Petrochemical Plants

Absolute Measurement Relations
(Reference to Mercury)
One inch mercury= 25.4 millimeters mercury= 0.491
COND. WATER INLET psi abs.
One inch = 25,400 microns
(micrometers)
EVACTOR AIR PUMP One millimeter = 0.03937 inch
One millimeter = 1,000 microns
One micron = 0.001 millimeter
BAROMETRIC
CONDENSER One micron = 0.00003937 inch
One kilogram/sq centimeter = 28.96 inches
One kilogram/sq centimeter = 14.22 psi abs
One kilogram/sq centimeter = 735.6 millimeter

Table 6-2
Standard Ejector Units Designations Conforming to Heat
Exchange Institute

Normal Range of Normal Range of
Letter Suction Pressures Disch. Pressures
No. Position in Series (Hg. Abs.) (Hg. Abs.)
-------------------------
z Atmospheric stages 3"-12" 30"-32"
y 1st of two stages .5''-4" 4."-10"
x lsL of three stages .1"-1" l"-3"
w lsL of four stages .2 mm-4mm 2 mm-20 mm
v 1st of five stages .02 mm-.4mm .4 mm-3 mm
u I st of six stages .01 mm-.08 mm .08mm-.4mm

The different types of condensing equipment used with
the various series are identified by the following letters:
FIRST STAGE
EVACTOR BOOSTER
B-Barometric Counter- C-Surface Coil Type Con-
Flow Condenser, Intercon- denser, Intercondenser and
denser and Aftercondenser Aftercondenser
S--Surface Type Condenser, N-Signifies no condenser
lntercondenser and After- in the series.
condenser
]-Atmospheric Jet Con-
denser, Intercondenser and
Aftercondenser,
The operating range of the condensing equipment
STEAM SUPPLY determines the nomenclature. Here are the basic divisions.
Condenser 1.5" Hg-4" Hg abs
Intercondenser 4" Hg-10" Hg abs
Aftercondenser 30" Hg-32" Hg abs
By permission, Croll-Reynolds Co., Inc.

Example 6-1: Conversion of Inches Vacuum to Absolute

A distillation column is operating at 27.5 inches mer-
cury vacuum, referenced to a 30-inch barometer. This is
the pressure at the inlet to the ejector, Due to pressure
Figure 6-78. Chilled water refrigeration unit using steam jet ejectors. drop through a vapor condenser and trays of a distillation
By permission, Croll-Reynolds Co., Inc. column, the column bottoms pressure is 23 inches vacu-