EnviroPro Combustion & Waste Heat Recovery Solutions

Flares used in the production field or hydrocarbon processing plant are defined by API RP521 as “a device or system used to safely dispose of relief gases in an environmentally compliant manner through the use of combustion.” A properly designed flare must operate continuously over a wide range of flow and process conditions. Understanding the various cases a flare must handle as well as the available utilities and environmental conditions are critical to properly designing a flare system. The information below discusses what information is needed.

Flare Design Parameters

Total Hydraulic Capacity: A flare must be sized large enough to handle all possible flows from everyday operations to upset conditions. All possible waste gas sources must be identified so that flow rates and gas compositions can be determined. Be careful not to oversize too much as most flares rarely operate at design conditions.

Smokeless Capacity: CFR 60.18 para c(1) states “Flares shall be designed for and operated with no visible emissions…except for periods not to exceed a total of 5 minutes during any 2 consecutive hours.” Smokeless Capacity is often expressed as a percentage of total hydraulic capacity and has a large impact on flare design and utility requirements. A flare begins to smoke when there is not enough air in the combustion zone to convert all of the hydrocarbon to CO2. This shortage of oxygen results in some of the carbon atoms joining together to create black smoke. Flare tips can use utilities such as steam or air blowers to get more air into the combustion zone and increase the amount of hydrocarbon that be burned smokeless.

Radiation Requirements/Limitations: There are multiple methods for estimating radiation from the basic API521 model, to the Brzustowski Sommer Model, to proprietary vendor models. The proximity of equipment, personnel, even the property line can have a large impact on the height of the flare stack design. In some applications radiation is a factor that drives a plant to look away from standard elevated flares and go to enclosed ground flare designs.

Noise Requirements/Limitations: Noise must also be considered when designing the flare. The requirements of the operating facility as well as surrounding community have an impact. Noise sources include both combustion noise and noise created by related utilities (i.e. steam or air blowers).

Environmental Conditions: The weather conditions and surrounding neighbors can all have an impact on how a flare is designed. A flare designed to operate in Alaska is not likely to be suitable for the same application in South America.

EnviroPro has the technical expertise to help you evaluate the advantages and disadvantages of each type of flare system and select the design that is best suited to your project. Give us a call or click on the links below to learn more about basic flare design and the equipment we can provide:

Contact EnviroPro to discuss your flare applications!