The problem
SBI Group runs a landfill site in Victoria, Australia, and needed to deal with residual odour from its landfill gas stream. The gas doesn’t arrive clean: it’s a lean, wet mixture — 25% to 50% methane by volume, saturated with moisture, carrying 0% to 5% oxygen, and flowing at a modest 25 to 100 Nm³/hour. Before combustion, the gas passes through a bioscrubber that strips hydrogen sulphide down to below 200 ppm. What’s left after that still needs to be destroyed, not just vented, and the destruction has to clear the Victoria EPA’s bar of greater than 98% efficiency.
The site already had space built for the equipment but no gas-moving equipment in place — meaning any solution had to bring its own blower as well as its own combustion unit.
Why an enclosed flare, and why this class of enclosed flare
Landfill gas flares aren’t a single product — vendors like Organics offer a spread of classes, and the choice between them is really a choice about how much heat and residence time you’re willing to pay for.
At the simple end, open (AC-range) flares burn gas in an elevated, non-luminous flame with no real control over the combustion environment beyond aeration — a reasonable no-frills option where regulatory scrutiny is light. Enclosed flares go further: they trap the flame inside a shrouded combustion chamber, holding the gas at a controlled temperature for a fixed “retention time” so trace contaminants actually get destroyed rather than just burned off visibly.
Within the enclosed category there’s a further split. SC-class flares — the type specified here — hold combustion gases at a minimum of 1,000°C for at least 0.3 seconds. MC-class flares push that further, to 1,200°C for 0.6 seconds, which improves destruction of some trace gases but comes with a real cost: above roughly 1,200°C, thermal NOx formation starts increasing sharply, so the higher-spec unit can trade one emissions problem for another. For a project driven by odour control and a >98% destruction requirement rather than trace-gas elimination, SC class is the proportionate choice — MC class would be over-specified for the stated problem.
There’s a second, smaller decision worth noting: the proposal explicitly excludes a fixed hydrogen sulphide gas sensor from the scope, recommending a hand-held analyser instead. The reasoning given is practical rather than cost-driven — H₂S is highly corrosive, and a portable analyser can be serviced and calibrated without dismantling a fixed sensor that lives in the gas stream permanently. It’s a small example of the proposal choosing a maintenance-friendly answer over a technically “more complete” one.
Design envelope
| Parameter | Value |
|---|---|
| Maximum gas flow | 100 Nm³/h |
| Minimum gas flow | 25 Nm³/h |
| Max burner capacity | 500 kW |
| Min burner capacity | 100 kW |
| Thermal turndown ratio | 5:1 |
| Inlet gas temperature | 20°C |
| Moisture content | Saturated |
| Methane concentration | 25%–50% by volume |
| Oxygen concentration | 0%–5% by volume |
| Flange connection | DN80, PN16 |
| Sound pressure at 15 m / 2 m height | 70 dB(A) |
| Hazardous area protection | ExN / ExD (subject to zoning); IP56 |
| Electricity supply | 50 Hz / 60 A / 400 V |
| Retention time | ≥ 0.3 sec |
| Combustion chamber temperature | > 1,000°C |
| Blower total head | 150 mbarg max |
| Suction pressure at plant inlet | 50 mbarg max |
| Supply pressure to flare | 50 mbarg max |
| Number of blowers | One |
| Pipework / skid / shroud / KO pot material | Hot-dip galvanised carbon steel |
| Flare shroud insulation | 100 mm ceramic blanket |
| Destruction efficiency (Victoria EPA requirement) | > 98% |
How it works
Gas enters through an inlet butterfly valve and passes first into a condensate knockout pot, where a polypropylene mesh demister strips droplets from the stream — the filter is rated to remove 99% of particles above 6 microns, at a pressure drop of less than 3 mbar. A level switch in the pot watches for condensate build-up before it can reach the blower.
From there, a single multi-stage centrifugal gas blower — gas-tight, EExN-rated, and built for continuous outdoor duty — moves the gas onward through stainless steel bellows and flexible joints, past a second set of isolation valves, through an ATEX-compliant flame arrester fitted with thermocouples for flashback detection, and into the safety train proper: an electro-hydraulically actuated slam-shut valve, plus a double-block-and-bleed arrangement of two actuated butterfly valves with a manual bleed valve between them. All of these fail closed on loss of power or an alarm condition, and none of them need a compressed air supply — they’re hydraulically actuated instead.
At the flare itself, a propane pilot burner (regulated between 10 and 50 mbar g) provides electric ignition with ionisation flame detection, and the whole start-up sequence — igniters, twin UV flame sensors, and a secondary air damper — is run automatically by a PLC. Once alight, a PID controller manages a combustion-air-actuated louvre to hold the chamber at or above 1,000°C when methane concentration is above 25%, tapering to a cooler flame as methane content falls toward 20%. Four DN125 sampling ports, spaced at 90-degree intervals near the top of the stack, allow emissions testing without shutting the unit down.
Physically, the package ships in two pieces: the blower and flare base arrive as one skid-mounted assembly, while the flare’s upper section — fitted with lifting lugs for lockable U-shackles — is craned into place on site and bolted on, meaning a mobile crane and appropriate access are part of the installation, not an afterthought.
Running costs and utilities
The unit’s stated electrical connection is 50 Hz / 60 Amps / 400 Volts three-phase, which sets the ceiling for blower and control-panel draw rather than describing continuous consumption — actual running load will sit below that depending on flow rate and blower duty point. Beyond electricity, the only other consumable is propane for the pilot burner, supplied and regulated by the customer between 10 and 50 mbar g; the propane bottle and regulator themselves are outside the supplied scope. There’s no water or other process input, since this is dry gas combustion rather than a scrubbing or quench process.
Scope and exclusions
What’s actually excluded is a longer list than what’s included, and it’s worth reading closely before assuming a “turnkey” price:
- Dewatering equipment ahead of the plant inlet — the system isn’t designed to accept liquid streams.
- Condensate removal or management facilities, unless separately specified.
- Third-party inspection or approval of electrical, structural, or fabrication work.
- Import duties, customs charges, and local taxes — all for the customer’s account.
- Safety Integrity Level analysis, DSEAR, or other formal safety studies.
- Flue gas analysis, and test/acceptance by any regulatory authority.
- Supply, installation, and connection of piping to the flare itself.
- Electrical supply and connection to the control panel, including fuses and switchgear.
- Signal or telemetry cabling to anything not supplied as part of this package.
- Earthing equipment and lightning protection.
- Foundation and civil works — Organics provides the design, but construction is the customer’s responsibility.
On top of the base flare and blower package, several compliance and monitoring items — regulatory approvals administration, a methane analyser, oxygen analysers, and an orifice-plate flow meter — sit outside the core scope as separately specified additions rather than being bundled in by default. Pricing and payment terms have been left out of this piece deliberately; they’re available on request.
Timeline reality
Quoted delivery is 12 to 16 weeks, running from order date and receipt of first-stage payment, and excluding public holidays. That estimate comes with real caveats attached: any delay in customer payment produces an equal delay in the delivery programme, and site access has to be confirmed in writing before equipment mobilises — the access road needs to take heavy vehicles and cranes and stay serviceable through heavy rain. Commissioning itself needs a minimum of two weeks’ prior notice and depends on foundations, gas, electricity, and water connections already being in place before the commissioning engineer arrives; if site prep isn’t ready, the completion date can slip regardless of how the equipment build itself is tracking.
Precedent
This isn’t a one-off design. The vendor’s project list spans 1989 to 2023 and runs into the thousands of reference numbers, with SC-class ground flares specifically appearing repeatedly across UK county councils, Irish local authorities, Hong Kong waste operators, and installations in Spain, Thailand, Indonesia, Malaysia, and New Zealand — several with power-generation or CDM-registered biogas-to-energy scope attached rather than flaring alone. It’s a technology with a long, largely unglamorous track record rather than a new entrant’s pitch.
Takeaway
An SC-class enclosed flare package like this one is a sensible, proportionate answer when the driver is odour control and a defined destruction-efficiency target rather than elimination of a wide spectrum of trace contaminants — and when there’s no existing gas-moving infrastructure on site to tie into. It’s not the right choice if the emissions target demands the higher retention time and temperature of an MC-class unit, and it’s not a complete site solution either: civil works, electrical supply, piping to the flare, and regulatory approvals administration all sit outside the box the equipment arrives in. The honest reading of a proposal like this is less “buy a flare” and more “buy a combustion skid, and budget separately for everything that has to surround it.”
