CHEMICAL RESIDUE DISPOSAL WITH HEAT RECOVERY
Warren G. Hudson, Senior Staff Engineer
Union Carbide Corporation
Engineering and Technology Services Division
South Charleston, West Virginia 25303
INTRODUCTION
A Corporation survey showed that there were 550 million pounds per year of liquid residues being
produced by the chemical plants of Union Carbide Corporation. To keep this survey manageable and
focused on fuelable residues, it only included the liquid residue streams that met the following criteria:
Stream consisted of more than 20,000 pounds per year.
Major components in stream were organics.
Residue stream was not presently sold.
Of the 550 million pounds per year of residues produced, 475 million pounds per year were burned
in boilers or process heaters. The remaining 75 million pounds per year were disposed of without heat
recovery.
This paper details reasons why the 75 million pounds per year of residues were not burned with
heat recovery. Also covered are the definitions of four classifications of residues used by Energy Systems (Utilities Department) to determine the rate of compensation to the producing units for their
residues.
ALTERNATIVE METHODS OF CHEMICAL RESIDUES DISPOSAL
Union Carbide uses a hierarchy for deciding the best method of chemical residue disposal whenever choices are available. The residue streams that are produced during the manufacture of chemicals
are usually disposed of in the following preferred order; however, the characteristics of the residue
may also influence the method of their disposal. This hierarchy starts with reprocessing of the residues.
Reprocess
Don't make any residues. Sound absurd? Maybe, but it is possible that process innovations in the
chemical unit could result in reductions in the quantities of residues requiring disposal. At one plant,
the cost of the producing units for residue disposal was significantly increased. The result was a drastic reduction in the quantities of the residues produced.
Recycling or reprocessing is using a material as-is as a process material or processing it to reclaim a
component for use as a process material. Reprocessing may be done within the unit that produces the
material or it may be done and/or utilized in another chemical unit or even another plant. The trick
sometimes is to find a match between the material (residue) and a user.
Sell
Selling is attractive because it always eliminates disposal costs and generates income. What is residue (waste) to one can be raw material (food) to another. For example, the waste sent to a wastewater
treatment plant is food for the biomass. Here again, one must be the match maker between the producer and the buyer.
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