GCI TECH NOTES ©

Volume 11, Number 8
A Gossman Consulting, Inc. Publication
August 2006

This is part of a series of GCI Tech Notes focusing on the early development of the hazardous waste fuels programs during the early 1980s.  I was hired as the facility manager for the first commercial hazardous waste operation at a cement plant in early 1980.  Many of the developments in storage, processing, testing and use of hazardous waste fuels were the result of work done at a handful of plants in the early and mid 80’s.  Look for issues to include topics on storage, lab testing methods, processing and the impact of HWF on cement product quality and production.

Heat Content, Ash, Halogens and Sulfur Test Methods in HWF – The Early Years

by

David Gossman, Gossman Consulting, Inc.

In 1980, at the first commercial hazardous waste fuel facility at a cement plant, there were initial specifications for heat content, nitrogen, chlorine and sulfur.  Early attempts to develop methods for these parameters met with mixed success. Heat content was performed using an automated adiabatic Parr bomb colorimeter – model 1261 to be exact. Procedures were derived from ASTM Standards for coal but were modified to handle the volatile liquid waste fuels.  Early attempts to use gelatin capsules supplied by Parr and mylar film covers to avoid evaporative losses were quickly abandoned.  The method adapted was to agitate the sample and quickly withdraw a 0.5 – 1.0 g quantity into the bomb cup, covering that with a second inverted cup for weighing, and then as quickly as possible placing it into a prepared oxygen bomb. This basic method is still being used 26 years later. Better automation has simplified the bomb prep and computers now calculate the equilibration point, cutting the time for this determination in half. 

In 1980 there were methods for chlorine and sulfur in coal using analysis of the wash from the bomb. These were time consuming wet lab techniques. For example, sulfur required precipitation, filtering, and drying the filter in an oven.  A Hach turbidometer method adapted from sulfate determinations in water was used with success for some time.  Hach methods for chlorine and chloride did not work well on the bomb wash. Attempts to use a chloride ion probe met with similar failure.  Eventually a silver nitrate titration with a coloromatic endpoint determination was adapted. Many facilities today use a variation of this method where a chloride ion probe is used for the endpoint determination. 

Nitrogen was an altogether different story. Early attempts to use a Hach kit for nitrate identified a significant background level of nitrate in the bomb wash that varied depending on the heat content and amount of sample being combusted. Correction curves were developed and used for some time but QC issues continued to be a problem. 

The only procedure for ash was the traditional ceramic cup in a muffle furnace.  There was a tendency to get significant sample loss as the volatiles boiled off the sample and it was time consuming – but it worked.  Over the course of that first year we discovered we could get better, faster ash values from the residue in the oxygen bomb cup.  The cup itself needed to be set on a hot plate for a few minutes after it was carefully removed from the bomb so that the contents were not spilled.  It was also necessary to carefully remove any ignition wire beads that landed in the cup. That said, it was faster and easier than the muffle furnace technique. In addition we confirmed that sulfur and chlorine combustion products do not remain in the cup but instead condense in an aqueous phase on the lid, walls, and bottom of the bomb. 

Even with these “improvements” the time and manpower required to perform the determinations on truck after truck and tank after tank caused us to start looking at some new technology– ion chromatography (IC). Chemically suppressed ICs were available from Dionex but the system at that time were expensive and cumbersome to use – multiple solution preps and multiple pumps. Wescam came out with an electronically suppressed system that was much simpler to use and maintain. Now we could use IC to determine in 15 minutes and with a simple sample injection, chlorine, bromide, sulfur and even phosphorus in the waste fuel.  Nitrogen continued to be a problem but was dropped from the specifications as it was determined that the primary source of the NOx from cement kilns was thermal NOx and that fuel nitrogen had little impact.  We did want to add fluoride to the line-up but IC at that time had difficulty separating the fluoride peak from the water dip.  Even that was dealt with.  By placing IC eluent in the bomb and using IC eluent for the bomb wash and any subsequent diluting we eliminated the water dip.  Adding fluoride to our test regimen greatly aided in future AFR development. 

Technical creativity, supportive management at Systech, and critical QA/QC follow up allowed us to develop 26 years ago many of the methods that are still used today to test for alternative fuels and raw materials for cement kilns and make the sustainable development programs of today possible.
Please contact David Gossman at 563-652-2822 or by e-mail at dgossman@gcisolutions.com for additional information – or if you have memories to share.