NYS Governor's Awards for Pollution Prevention - Olin Corporation
Olin Corporation, Niagara Falls, New York
Olin Corporation, located in Niagara Falls is a chlor-alkali manufacturing facility that produces chlorine gas by electrolysis of a sodium chloride solution (brine). Most of the chlorine gas is liquefied for shipment to customers but a portion, composed of inert gases that cannot be liquefied (commonly known as "tailgas"), has historically been neutralized by mixing/scrubbing with a caustic solution, treating and then discharging as a salt/carbonate waste stream to the City of Niagara Falls wastewater treatment facility. By modifying the process operation, Olin was able to recover and recycle this former waste stream.
Methodologies and Procedures
This waste stream elimination was accomplished by installing additional equipment and modifying the process operation to allow the recycle and recovery of the solutions generated from tailgas scrubbing. Specifically, a relatively chlorine-rich tailgas stream has been separated in the process and is now used to produce a dilute sodium hypochlorite solution used as "raw bleach" feed to the Olin sodium hypochlorite manufacturing facility. Sodium hypochlorite is the chemical name for bleach, the active ingredient in household laundry bleach sold in grocery stores everywhere.
In order to match raw bleach generated from tailgas scrubbing with consumption in the Olin finished bleach operations, this project installed a two-tank raw bleach storage and pumping system housed in a new diked area adjacent to the Olin Bleach production area. Olin bleach manufacturing operations have been modified to use the new raw bleach stream.
In addition, a relatively CO2 -rich tailgas stream has also been separated in the process and is now processed in a new scrubbing and hypo decomposition system. The new system consists of three caustic-containing titanium sparge tanks in which this tailgas is scrubbed in batches. The sparge tanks are vented to a final scrubber to insure that all traces of gaseous chlorine are neutralized prior to atmospheric discharge. The sparge tanks contain a catalyst, which causes the bleach formed by the chlorine reaction to continuously decompose to sodium chloride (salt). At the end of the batch, the sparge tanks contain sodium chloride solution (brine) that is also rich in sodium carbonate. The resulting brine/carbonate stream is recycled to the Olin chlor-alkali process brine treatment system, displacing purchased materials. In this manner, "waste" streams previously treated and discharged to the City of Niagara Falls wastewater treatment facility are now captured and recycled for use in the Olin chlor-alkali facility.
Eliminates the daily sewering of approximately 16,500 gallons of brine containing about 18 tons/day of dissolved salts to the Niagara River via the City of Niagara Falls wastewater treatment facility. These salts are now recycled to the Olin chlor-alkali process.
Recovers raw material value from previously wasted chlorine tailgas streams. Extensive testing prior to implementation of the project was used to ensure that the resulting raw bleach and recovered brine streams would not compromise existing process control and product quality requirements.
Conserves energy and raw materials. Chlor-alkali manufacturing consumes large quantities of electric power as a raw material. Recovering previously wasted chlorine and caustic as raw material for bleach manufacture and brine treatment further enhances the use of electric energy and other raw materials.
The total cost of the project was $6.5 million with a four-year payback period.