Solar Radiation for Flare Heat Radiation Intensity

[MacProcess]

Hi.

I will calculate flare stack heat radiation intensity.

If I consider to include solar radiation, can I just add solar radiation to the cacluated heat intensity from flare stack?

I wonder if there is any formula for heat radiation calculation when I consider solar radiation.

Thanks.

[f81aa]

Hi MacProcess:

Consider a value of 500 BTU/hr ft2 as the permissible design level of the design flare release at any location where personnel are continuously exposed.

In this example, if solar radiation were neglected, a person would be exposed to 500 BTU/hr ft2 PLUS the value of the solar radiation, whatever it might be. If a value of 320 BTU/hr ft2 were used for solar radiation intensity on a clear, hot summer day, then the combined radiation value would be higher and personnel would no longer be allowed to be continuously exposed.

Deduct the value of the highest solar radiation expected from the value of the radiation intensity (500 BTU/hr ft2) in order to obtain the new endpoint (180 BTU/hr ft2) for calculating the distance from the flare to personnel continuously exposed. This new value will cause a significant increase in cost.

Let´s keep in mind that Table 9 of API 521 (2008) gives 4 permissible design levels, 500 BTU/hr ft2 being one of them, and the lowest one. Also, the flare owner/operator shall determine the need for a solar-radiation-contribution adjustment to the values given in Table 9 on a case-by-case basis.

As the permissible design level increases, the impact (of adding solar radiation in the calculation) on the flare cost diminishes.

Section 6.4.2.3 of API 521 (2008) has a good explanation of thermal radiation.

Regards