3 replies to this topic

[ankur2061]

Dear all,

The question is very simple. Can you locate equipment e.g. a Blower for Low-Pressure Air Assisted flare inside the sterile radius of a flare?

I am of the opinion that locating such an equipment within the sterile radius is fraught with danger due to equipment getting exposed to high thermal radiation and getting damaged.

However, I would like to know the opinion of knowledgable forum members.

Regards,
Ankur.

[gvdlans]

The extent of the sterile zone is based on the thermal radiation that a man/woman with normal clothing can endure (for a short period of time). People have the advantage over equipment that they can run away. On the other hand, equipment may have a higher resistance against thermal radiation.

So it really depends on what type of equipment you have and what the radiation levels can be. Below 10 kW/m2 (about 3000 BTU/hr/ft2) I would not worry to much about the equipment. Above that, you may get problems with instruments, cables etc.

Also, you may consider to put the equipment below some heat shield, or at least the vulnerable parts.

So my advise is to do radiation calculations for your flare. Based on the radiation contours you select a good location for your particular equipment and/or to provide heat shielding. You may also have to consider that the equipment cannot be maintained etc. while the plant is in operation (since it is located in a sterile area...) unless special protective measures are taken.

[JoeWong]

Ankur,
Basically Guido has covered most of the points.

Air assisted flare will have blowers at the bottom of the stack. These blowers may need maintenance and inspection from time to time. Flare stack will be raised high enough such that allowance of maintenance operator carry out maintenance activities and allow several seconds for evacuation during maximum flaring event. Example is thermal radiation at the stack bottom limited to 6.31 kW/m2 during maximum flaring...Generally blower, cable, instrument , etc can take this thermal radiation.

If several flare stack are locating at the same place (quite normal), then it will make the flare stack very high. May have to design sterile away from stack bottom. Under this condition, higher thermal radiation at the stack bottom. Operator will need special heat resistance clothing. Stack bottom may be design for 9.46 kW/m2 (probably the equipment, cable, etc can take even higher thermal radiation) with 6.31 kW/m2 at sterile zone.

Locating blower far from stack would lead to potential delay in air supply. Pressure drop is potentially high and heavy duty blower is required.

[astro]

I would add that while from a technical perspective you can work up an effective design for kit within the sterile zone, your biggest potential hurdle is user acceptance from Operations & Maintenance.

Unless they're in tune with the design philosophy you end up with, you will be dealing with problems at project handover. I would bet that these personnel considerations will dictate your final design.