| OCR Text |
Show composition is approximately 27oo°F with 2 % oxygen in the combustion products. As with PSA gas flexicoker off gas is normally frred in combination with other fuel gases, generally contributing between 50 % and 85 % of the heat duty. Depending on the quantity of PSA or flexicoker off gas frred in combination with other fuels and many other variables including the burner type the NOx emissions can range from 12 - 15 ppm to 60 - 70 ppm corrected to 3 % O2 in the combustion products. When the low heating value fuel gases are frred alone, the NOx emissions can be less than 10 ppm for PSA off gas and in the range of 5 - 7 ppm for flexicoker gas, all values corrected to 3 % O2 in the combustion products. There are various other low heating value gases that are frred in various types of heat transfer equipment throughout the industrialized world. Many of these gases are primarily mixtures containing various amounts of carbon monoxide, hydrogen, and inert components such as nitrogen, carbon dioxide, and water vapor. Since little defInitive information is available regarding the NOx generated when frring many of these gases and since the heating value can vary considerably more than the variation between PSA and flexicoker off gas heating value, it was decided to gather additional data by frring various mixtures of hydrogen and carbon dioxide. The primary objectives were to evaluate the NOx emissions for the various mixtures and to determine the minimum heating value mixture that would provide stable operation with typical excess air levels. Tests were conducted with mixtures that ranged from 100% hydrogen to 26 % hydrogen. VI. Correlation of NOx with Adiabatic Flame Temperature The data available for PSA off gas frring, flexicoker off gas frring, and hydrogen/carbon dioxide mixture frring can be used to develop a correlation that makes it possible to estimate the NOx emissions for various low heating value gas mixtures if the NOx emissions are known for another specifIc base fIring case. The correlation is given in Figure 1 The information is 6 |
