Flare Gas Mass Flow Measuring
Thermal Flow Meters Offer Most Flexible & Economic Solution
Oil wells almost always produce natural gas (“associated gas”) along with the petroleum. In many cases, it is uneconomical to process due to heavy contamination. As a consequence, this gas is combusted, “flared off” or simply vented as-is during upset conditions in the process. Newly updated EPA regulations like 40 CFR Part 60 Subpart OOOO (also known as Quad O) as well as the new RSR MACT rule for refineries, requires oil & gas companies to report the fl are gas emitted to our atmosphere. Monitoring the fuel at the inlet of the flare is part of meeting these EPA requirements (See Figure 1). Flare and combustor gas measurement is a challenging application because each well has its unique and constantly changing characteristics that include depth, temperature, pressure, flow rate, soot content, and varying gas composition.
Sierra’s advanced QuadraTherm 640i Thermal mass Flow meters accurately measures the flow rate with the changing gas compositions, very low flows, and high velocity at upset conditions and offer a more reliable solution than turbine meters and orifice plates.
High Turndowns of 100:1 & Measures Very Low Flows
Handle very low flows and high flows at upset conditions; flow range 0 to 60,000 sfpm (0 to 305 smps).
Most Accurate Thermal Flow Meter-Easily Meets EPA Regulations
With four-sensor thermal sensor technology and the on board Raptor II operating system, accuracy specifications are +/- 0.75% of reading, comparable to four-path ultrasonic meters at a much more economical price. Eliminate drift with patented DrySense™ sensor with lifetime warranty.
Figure 1: QuadraTherm 640i Thermal Mass Flow Meter in flare gas measuring application.
Very Low Pressure with Variable Temperatures
The multivariable 640i VT measures very low pressure gas with no pressure loss.
Uniform Flow Profile
Flare stacks generally have asymmetric and swirling flow. The 640i has a Reynolds’ number correction built in to smooth the Flow Profile.
Figure 2: QuadraTherm™ 640i Insertion Thermal Mass Flow Meter
• Achieve high accuracy +/- 0.75% of reading (+/- 0.5% for 780i inline with built in flow plates): Multivariable outputs
• High flows up to 60,000 sfpm (0 to 305 smps): 100:1 turndown
• Eliminate drift with patented DrySense™ sensor-Lifetime sensor
• qMix Gas Mixing App manages changes in gas composition in the field—no recalibration needed
• In-situ ValidCal™ Diagnostics, Dial-A-Gas & Dial-A-Pipe
• Low and high pressure hot tap
• 40 CFR Part 60 (Quad 0), Boiler MACT Greenhouse Gas (GHG) certified
• Digital communications
• cFMus, ATEX, IECEx approvals
Easy-to-Install-Dial-A-Pipe to Cover Various Pipe sizes
Roaring flames, difficult access and regulatory requirements make flares difficult to service. Insertion thermal flow meters come with hot tap option for no process shutdown, and Dial-A-Pipe to use one flow meter for varying pipe sizes—without factory recalibration.
Figure 3: qMix™ Gas Mixing App in Smart Interface Portal (SIP).
qMix App Adjusts for Changing Gas Composition—No Recalibration Needed.
Flare gas composition and density varies over the lifetime of the fl are. With changing gas compositions, a typical total flow measurement error could be as high as 20% in applications with widely varying compositions. QuadraTherm thermal fl ow meters can manage the changes in fl are gas composition through the qMix gas mixing app which computes the mass flow rate of any gas composition and retains accuracy without factory recalibration.
Through the on board qMix gas mixing app: