addressing uncertainty in oil and natural gas industry greenhouse

Coke burn rate
approach
(Equation 5-4)
“K 1 , K 2 , K 3 ”
approach
(Equation 5-5),
Air blower rate
approach
(Equation 5-6)
Table 5-5. Uncertainty Comparison for FCCU Estimation Methods
Contribution CO 2 CH 4 N 2 O
Coke Burn 408,348 ± 16.0%
CO Boiler 46,516 ± 7.07% 0.88 ± 11.2% 0.86 ± 50.2%
Total 454,864 ± 14.4% 0.88 ± 11.2% 0.86 ± 50.2%
Total, CO 2 Eq. 454,149 ± 14.4%
Contribution CO 2 CH 4 N 2 O
Coke Burn 411,862 ± 15.9%
CO Boiler 46,516 ± 7.07% 0.88 ± 11.2% 0.86 ± 50.2%
Total 458,378± 14.3% 0.88 ± 11.2% 0.86 ± 50.2%
Total, CO 2 Eq. 458,663 ± 14.3%
Contribution CO 2 CH 4 N 2 O
Coke Burn 419,859 ± 15.9%
CO Boiler 46,516 ± 7.07% 0.88 ± 11.2% 0.86 ± 50.2%
Total 466,375± 14.4% 0.88 ± 11.2% 0.86 ± 50.2%
Total, CO 2 Eq. 466,660 ± 14.4%
Rounding is limited to the uncertainty values to facilitate comparison.
5.3.3 Uncertainty Comparison for Hydrogen Plant Emission Estimation Methods
The API Compendium provides two rigorous calculation approaches for estimating the CO 2 generation rate
from the hydrogen plant, both using a specific feed gas composition. The approaches are based on either the
volume of feedstock used or the hydrogen production rate. This section compares the uncertainty estimates
associated with these methods. For this comparison, the following operating parameters and uncertainties are
assigned:
• A hydrogen plant has a feedstock rate of 3×10 9 ± 15% standard cubic feet per year and produces
13×10 9 ± 15% standard cubic feet of hydrogen per year.
• The feed gas composition (molar basis) is CH 4 = 85%, C 2 H 6 = 8%, C 4 H 10 = 3%; the balance is inerts
(assume N 2 for the inerts). Table D-2 of this Uncertainty document provides reproducibility
uncertainty associated with natural gas samples. These values can be applied to account for the
measurement error in the composition sample. An additional 5% uncertainty is assigned by expert
judgment to account for potential variability and bias in the gas composition during the month.
• It is assumed that no CH 4 is entrained in the hydrogen product.
For both methods, the uncertainty associated with the feedstock composition is needed. The combined
uncertainty of the reproducibility and variability is calculated by applying Equation 4-4, using the absolute
uncertainties. The calculation is demonstrated for ethane below; results for all of the compounds are shown in
Table 5-6.
Pilot Version, September 2009 5-14