Knocks For NOX
By Wayne Cooper, Ph.D.
July 1995

Air pollution control is an increasing part of modern industry's responsibility. It can be taken to include air which contains materials that discolor it, make it irritating to breathe, render it potentially harmful to health or environment-threatening. One of the contaminants which is familiar to urban dwellers is widely known as NOX, oxides of nitrogen. Nitrogen and oxygen are the major components of the air we breathe, but when the combination is exposed to high temperatures, NOX can be formed. Because of the presence of nitrogen in the air, all devices that require air to burn hydrocarbon fuels (gasoline, diesel, natural gas, coal, etc.) may produce NOX as a byproduct of fuel combustion.

In today's technology, borates cannot possibly be produced on an industrial scale without some NOX emissions. However, Borax at Wilmington has recently achieved remarkable reductions - in smog-notorious Los Angeles - and as a result has become joint winner of the 1995 Clean Air Award from the South Coast Air Quality Management District (SCAQMD) for new technology development.

Reduction of the NOX emissions from the Wilmington facility of U.S. Borax was accomplished in response to increasingly stringent emission controls and with the help of new air pollution control technology previously untried on a commercial scale. The Wilmington facility is located in the Los Angeles Basin and is a part of the SCAQMD. In order to meet the requirements of the recently amended federal Clean Air Act, the District has developed a program for progressively reducing emissions year by year (until at least 2003). At the same time, the program encourages industrial activity in the area. At first sight these two desirable aims would appear incompatible since more production surely means more emission; but read on.

Based on historical emission levels, each operation in the SCAQMD is allotted 'emission credits'. These credits, which in effect determine the quantity of material which each plant is allowed to emit to the air, are reduced on a yearly basis. This means that overall the air will get cleaner year by year. However, emission credits can also be switched from plant to plant, or even be bought and sold. Thus a company which wishes to increase production can use emission credits from another company which has reduced its own pollution. This helps industrial growth on the one hand and defrays the cost of environmental protection on the other - and all within a planned air improvement program.

Borax in its continuing effort to find technology to reduce emissions was approached by Radian Corporation. Radian had developed a new burner technology thought to be capable of ultra low NOX generation, and proposed a test of its unit. After some discussion and negotiations, a cooperative test was agreed upon. The burner was installed on the primary steam boiler. The burner used was a 26 million BTU/hr. unit. To put the size into a more easily understood perspective, it is the equivalent to energy delivered by 425-450 household heating furnaces or about 650 domestic hot water heaters. The NOX levels generated from the burner were predicted to be less than nine parts per million (PPM), substantially less than the permitted level of 30 PPM generated in the boiler's existing burner system which itself was meeting the current best available technology standards. NOX levels from the boiler furnace were expected to be reduced by about 70 percent.

Installation of the new burner was relatively simple, requiring removal of the old burner, and installation of an air blower assembly and control system. Most of the other apparatus associated with the original burner remained in place and was used with the new burner. Design of the new burner was essentially a variation in the mixing of the fuel (natural gas) and the air resulting in greatly improved fuel and air blending and consequently less NOX production.

Evaluation

Installation and operation of the new burner did reduce the NOX generated in the production of steam. The NOX levels were lowered from just under 30 PPM to about seven PPM - even lower than predicted by the manufacturer. Coincidentally, the carbon monoxide emissions were reduced from about 400 PPM, the permitted level, to less than nine PPM. The burner did indeed operate as predicted, resulting in NOX emission reductions of greater than 70 percent. Emission evaluation was carried on by an independent third party as well as by Borax and Radian.

Frequently, technologies do not operate or produce as claimed. This one did and as a result, the technology is being installed on other applications at the Wilmington facility and at other Borax plants. The Radian Ultra Low NOX burner is being installed on a drying unit at Wilmington and in a different drying application at the Boron facility. Other potential applications are being studied.

This ultra-low NOX technology has possible application at almost any operation where a burner is in use, e.g. dryers, ovens, furnaces, steam boilers, etc. Having been proven at Wilmington, the burner technology is now being promoted collaboratively by its inventor, Radian, and a satisfied user, U.S. Borax. Obtaining recognition for installation of a technology to make the air cleaner and healthier in an air district with some of the most stringent emission requirements in the world, is indeed worth noting. Today it is making Los Angeles just a little cleaner, and tomorrow who knows?

Wayne Cooper is senior environmental scientist at Boron.