SULFUR BURNING AND SULFITE LIQUOR PREPARATION PLANTS

A. H. Lundberg, Inc. Acid Plants are designed to fulfill the needs of pulp mills requiring
sulfite pulping liquors. The acid sulfite liquors contain a certain amount of free sulfur
dioxide in solution, while neutral liquors do not.

The Lundberg Acid Plants can be used to make pulping liquors from any of the common
bases. The bases include sodium, supplied either as carbonate or hydroxide; ammonia,
magnesium, and calcium.

Each Acid Plant is custom designed to satisfy the mill's requirements for liquor
composition and quantity.

In these Acid Plants, sulfur dioxide, derived from burning sulfur in air in the unique
Lundberg sulfur burner, is reacted in an absorption tower with water containing the base.
Variations in absorption tower design and make-up Systems are required to accommodate
the base which is used. These absorption towers provide for gas inlets, liquor inlets and
recirculation as required. The circumstances of the particular system will also at times
require special heat exchanger considerations for the recirculating liquor.

Sulfur can be received at the mill either in bulk or molten form. If it arrives in the preferred
molten form it can be stored in a molten sulfur storage tank and pumped to the sulfur
burner as required. If the sulfur arrives in a dry form, it must be transferred from dry
storage to a sulfur melter from which it can be pumped or gravity fed to process.

The Sulfur Burner is the critical equipment which determines the ease of operation of the
acid plant. This unit is utilized to produce sulfur dioxide gas from elemental sulfur.

The Lundberg Sulfur Burner is designed to incorporate efficient sulfur burning with low
sulfur losses and ease of operation.

A positive flow of molten sulfur to the burner is controlled by a steam jacketed standpipe,
or a positive displacement pump. When the sulfur reaches the Lundberg spray nozzle,
it is atomized with a steam jet for instantaneous combustion. This unique system of
control and atomization facilitates the rapid start-up and shut-down of the entire system.
The hot SO2 gases leave the combustion chamber and achieve total combustion in the
hot gas pipe. The hot gas pipe delivers the SO2 gases to the Primary Cooler.

The Primary Cooler is a direct contact spray type cooler with a sealed water underflow
at the weir box. The function of the Primary Cooler is to drop the temperature of the hot
gases from 2000 degrees F. to 180 degrees F. instantaneously. This rapid temperature drop limits
the
amount of S03 formation. Most of the cooling takes place due to evaporation of cooling
water. Depending upon the process desired, the cooled gases may be cooled further in
a Secondary Cooler or delivered to an absorption tower, where it is converted to either
an acid sulfite liquor, or a neutral sulfite liquor.

The draft through the sulfur burner and absorption towers is maintained by a special
corrosion resistant fan of Lundberg design. By control of the draft, a slight vacuum is
maintained throughout the burning and absorption units preventing the escape of noxious
sulfur dioxide gases into the working areas of the mill.

Other important features of the burning system include: the Lundberg sulfur atomizing
nozzle with replaceable wear parts and the Lundberg designed team jacketed control
valve for regulation of molten sulfur flow to the standpipe. The Lundberg weir box, which
provides a positive water seal on the primary cooler water underflow, is also provided with
a turbidity alarm. This turbidity alarm alerts the operator of upset conditions causing
pulling of sulfur. Sulfur burners with rated capacities from one (1) to fifty (50) tons of
sulfur burned per day are available. Turn-downs of 70 to 80 percent can be accommodated.

Sulfur Burning Gas Cooling System
SA-1075-D