Improved Flare Radiation Criteria in Terms of Solar Radiation Contribution
Ankita Taneja (1), Delphine Laboureur (2), Bin Zhang (1), M. Sam Mannan (1)
1. Texas A&M University, College Station, TX, USA 778401
2. The von Karman Institute for Fluid Dynamics, Belgium2
At chemical processing plants, a flare stack is used to get rid of unwanted or excessive gases and relieve the system of excess pressure by combustion, thus causing high heat to radiate to atmosphere. Heat radiated from flare is important for siting flare at a proper location. The heat radiation should not exceed recommended threshold level so that people on-site and the equipment are not affected. Thus, to have a well-designed flare, knowledge of total radiation emitted from a flare is important to know. It will aid in accurately estimating the flare height and the area near the flare which would sustain high level of thermal radiation.
A common point of contention while calculating radiation level emitted from flare is the decision of including solar radiation (SR) in the calculations. API 521 mentions it to be discretionary upon the flare design company. However, some literature states that for all practical purposes, solar radiation contribution can be discounted.
The work performed aims at presenting a framework which quantitatively addresses aforementioned obscurity. The analysis helps flare designers to more objectively decide whether to include SR or treat it insignificant. The work studies the factors that cause variation in SR value: location, time, and orientation of the surface. Considering all these parameters, an appropriate value of SR is chosen to be the contribution of Sun to thermal radiation from flare. The effect of SR to design of flare is quantified by studying the change in effect distance near the flare and the height of flare. Consequence analysis software PHAST is used to obtain these calculations. In addition, the outcome that SR inclusion will have on the risk posed by the flare due to thermal radiation on personnel is also examined. This is studied by measuring the change in lethality and heat stress caused by radiation exposure.