Vertical Liquid Chlorine For Chlorine and other Toxic, Liquefied Gases
Under normal atmospheric conditions chlorine (CL2) is a greenish, yellow gas with a
biting penetrating odor. It is nonflammable, but it supports combustion at higher
temperatures. Chlorine, like other halogens, is highly reactive. When it reacts with
water, it forms hydrochloric and hypochlorous acids, both of which are highly corrosive.
Chlorine is compressed and liquefied for shipping, storage, and handling because it
boils at -30°F at atmospheric pressure.
Chlorine is very reactive and potentially deadly. Liquid chlorine can burn the skin.
Inhalation can cause sneezing, coughing, shortness of breath, tightness in the chest,
severe restlessness or anxiety as well as nausea and vomiting. Immediate death
can occur, as a result of suffocation. Later fatalities can occur as a result of
pulmonary edema (fluid in the lungs).
With chlorine being such a hazardous substance, the Chlorine Institute recommends only top
outlets, as opposed to bottom outlets, for chlorine storage tanks. This represents a
serious restriction in designing a liquid chlorine transfer system from storage tanks to
loading facilities or other processes. The Lawrence Vertical Liquid Chlorine pump
has been specifically developed for mounting on the top nozzle of the pressurized liquid
chlorine tank.
With these considerations in mind, Lawrence has designed its Vertical Chlorine pump for
efficient transfers without loss or contamination, high capacities and high heads,
full automation and protection, with high reliability and long service life.
The use of a Centrifugal Pump to handle liquid chlorine provides a faster transfer
than through padding (pressurizing a vessel with air), and allows the
chlorine to be transferred without subjecting the chlorine vessel to the high pressure
which padding imposes.
Capabilities: Flows to 800 GPM (180 m3/hr) Heads to 800 ft (244 m) Temperatures from -60° F to 125° F (-15° C to 52° C)
In addition to liquid chlorine, these pumps can handle anhydrous hydrogen cyanide,
phosgene, bromine, sulfur trioxide, and other dangerous liquefied gases which must be
contained to satisfy environmental laws and safety regulations.
Design Features
All models are vertical, top entry units to eliminate hazardous side or bottom
connections. Liquid chlorine is pumped in both boiling and suppressed conditions.
To prevent chlorine gas leakage to the atmosphere, a buffer gas - dry air or nitrogen
- is used between the lower and upper sealing element. For a vapor pressure range up
to 60 PSIG (4.2 kg/cm2), packing is used. Higher pressures require a
specially-developed, mechanical gas seal for the upper box.
An adjustable gland mechanism permits packing tightening from the outside. In case of
packing failure, the emergency seal may be pressurized to prevent chlorine leakage.
The instrumentation package provides for a controlled flow of buffer gas to the air
chamber. Vapor pressure in tank is reference pressure.
Thermocouples monitor the temperature of the lower packing. Excess heating
automatically shuts the pump down.
The excess flow check valve is a feature which stops the flow of liquid chlorine should
a line rupture occur above the mounting plate. The ball in the check valve is
designed for the capacity output of the pumping equipment. When a line fractures the
capacity of the pump increases, and in doing so the ball rises and seats properly in
the valve, which stops the flow of liquid chlorine while the pump is operating.
The sudden closing of the check valve creates a high pressure water-hammer effect. The
chamber is filled with liquid chlorine gases and when the check valve slams shut the
water-hammer shock waves are absorbed by the surge chamber. The shockwaves are kept
from passing down the discharge pipe into the the stages of the pumping equipment which
could result in fracturing the pump casing internals.
The diffuser casing design completely balances the radial thrust around the entire
360° circumference of the impeller. Regardless of the number of stages used, or
the head developed by the pump, the radial load carried by the sleeve bearings is
minimal.
The enclosed carbon steel impellers are equipped with sealing surfaces on both the
front and back shrouds. For "wet" chlorine applications monel is available, as is
stainless steel for toxic services other than CL2. The radial sealing ring surfaces allow variations in impeller
clearances without affecting overall performance. Since chlorine is usually pumped
when boiling, NPSHA is equal to submergence above the centerline of the impeller
minus friction losses in the suction. To avoid pumping down under cavitation
conditions, a suction inducer is available on all sizes. It will lower NPSHR and
thereby reduce chlorine inventory in the tanks.
Product Applications
Liquefied Chlorine Gas
Other Toxic Liquefied Gases
Chemical Processing Industry