Introduction; Evaporator - Thermo Scientific 2112 Series Operating Manual And Parts List

Evaporator

Thermo Scientific

Introduction

Section 2
Thermo Scientific electrically heated water stills are available in four sizes;
1, 2, 5 and 10 gallons per hour of distilled water. The distilled water
produced by the stills contains not more than 1.0 ppm total solids, with a
pH value of 5.4 to 7.2 and an electrical resistance of not less than 300,000
ohms at 25°C when the stills are operated on most potable water. The stills
are designed to use not more than 9 gallons of cooling water and feedwater
combined, for each gallon of distilled water produced. The still consists of:
an evaporator with its heat supply, a condenser, and devices to control the
water level and salt concentration in the evaporator, a Q baffle for pyrogen
removal and a low water cutoff control. The operating characteristics for
each size still are shown in the Installation Diagram.
Still evaporators are the vertical, cylindrical double-wall type with air-
insulating space. The evaporators are built sufficiently high and wide to
provide ample vapor disengaging space and operation at low velocity.
The evaporator shell is of polished stainless steel. The inner shell (boiler) is
fabricated of copper, brass and bronze. The evaporator cover is brass,
finished in polished nickel and is provided with a Q baffle. All surfaces
that contact the vapor and distillate are coated with pure tin to prevent
metallic contamination. A water level sight glass is provided on all 5 and
10 gph stills.
Condenser
Distillate
Water
Outlet
Cooling Water/
Constant Level
Figure 2-1. Electrically Heated Stills
Inlet Tube
Device
Preheated
Feedwater Tube
Q-Baffle
Deconcentrator
Valve
Evaporator
Classic Elec Heated Stills 2-1