Supersonic, High Pressure, Low Radiation Flare System Design

Abstract Two years ago, Callidus Technologies Inc. recognized the need in the industry for a new and different method of flaring high pressure gases from onshore and offshore production facilities. After a review of the existing flare tip technologies currently available in the marketplace, a program was developed and implemented to design and prove, in full scale testing, a flare tip that would provide for lower radiation levels, lower flare tip weight, and improved smokeless performance. The flare tip is the first in the world to utilize converging-diverging super-sonic nozzle technology in the flaring of production gases. By using these nozzles to increase the waste gas exit velocities to greater than Mach 1, this flare tip inspirates significantly larger quantities of air into the combustion zone. This results in a much cleaner burning flame, lower emissions in the form of radiation, and a much higher momentum in the flame envelope due to the increased mass of material giving a stiffer and more up-right flame. All of these factors combine to produce shorter boom lengths, reduced flare emissions, and smaller relief header size due to higher flare backpressures. In addition to the combustion process improvements in the flare tip, an evaluation of the construction techniques and metallurgy's was undertaken and relevant improvements were made in these areas also. To prove the theoretical application of this supersonic nozzle technology, a test facility was designed and constructed to test the flare tip. Initially, a scale model was tested at relatively low flows, up to flows of 10 million standard cubic feet a day. This testing proved very successful. The test facility was then modified to flow larger rates, up to 200 million standard cubic feet a day of natural gas. Testing of the full size flare tips has proven achievement of the theoretical design goals for the project. This new design concept is now being introduced to the production industries worldwide. Introduction Flare systems are used in offshore and onshore production and drilling facilities to dispose of the associated gases and liquids from testing and production. In some parts of the world, these hydrocarbon streams can be vented directly to the atmosphere with acceptable environmental impact and with approval of local agencies/government. Combustion of these gases using a flare is used where the impact to the environment is determined to be significant, or safety issues associated with venting unburned hydrocarbons mandate. Flare systems can be separated into two basic types: Open flares with visible flames and Enclosed flares with non visible flames. Open flares are typically designated as high pressure type or "pipe" flare type.