American Petroleum Institute

MANUAL ON DISPOSAL OF REFINERY WASTES VOLUME ON ATMOSPHERIC EMISSIONS CHAPTER 15-FLARES
 N PUBL 931 C15

Annotation

Introduction

Refinery flares are special burners used to destroy unavoidable emissions of hydrocarbon and other combustible gases. It is necessary to burn such gases in order to (a) prevent deleterious effects on people, animals. and plants as discussed in Chapters 2, 7, 10, 14, and 16 and (b) comply with federal, state, and municipal regulations as covered in Chapter 3.

The methods available to prevent such emissions or to recover them before they escape are described in Chapters 7, 14, and 16. While these processes can be very efficient, there are always small residual emissions which must be destroyed. In most cases the gases can be burned in a flare. but some gases may require the special incinerators discussed in Chapters 14 and 16.

In addition to these small emissions, the refinery flare must be capable of handling very large releases of hydrocarbons which exceed the capacity of the system for control and recovery. Such releases can occur in emergencies resulting from the failure of equipment or from fires.

Basically a flare system consists of piping to collect the gases, devices to remove entrained liquid, and a terminal burner operating in the open with no provision to recover heat or to treat the combustion products. A typical refinery flare system is illustrated in Figure 15-1.

The system consists of the following elements:

I. Flare header from the process units

2. Knockout drums to remove and store condensable and entrained liquids

3. Proprietary seal. drum. or purge gas to prevent flashback