If a site already has gas boosters and condensate drainage, a bolt-on ground flare can be added with only three connections: a pipe from the booster outlet, power to the flare panel, and a start/stop signal from the existing controls. This worked example from a quotation for a landfill services contractor shows what the flare package includes, what the client must supply, and the questions to settle first.

The challenge: more flaring without rebuilding the plant

The contractor operated an existing gas extraction facility. It had boosters and drainage that worked. What it needed was extra flaring capacity, with a high-temperature enclosed flare, without paying for a second set of boosters or a new knockout pot.

The approach: a flare that slots into the existing controls

The interface

The supplier defined the boundary precisely:

• Steel pipework from the existing booster outlet to the flare inlet flange.
• Power to the flare’s control panel.
• A start/stop signal from the existing facility controls.

When the flare receives the start signal it lights the landfill gas pilot and begins its ignition cycle. When the signal is removed, it shuts down. The existing plant therefore runs the flare just like another item of plant.

The flare package

• A pressure switch on the booster outlet, a manual trim valve and a stainless steel flame arrester on the feed line.
• An SC Range ground flare rated at 1,000 m³/h, with a 7 m shroud.
• A combustion chamber temperature of at least 1,000°C when methane is above 25%. It burns cooler as methane falls to 20%.
• A residence time of at least 0.3 seconds, and a 5:1 turndown, so the minimum flow is about 200 m³/h.
• Automatic temperature control with a PID controller, a combustion air louvre and an electric actuator.
• Automatic ignition, a UV flame sensor, a slam-shut valve and a temperature read-out from an Inconel thermocouple.
• A choice of “continue running” or “shut down” on flame failure, and vent-only operation.

The skid arrives separate from the chimney. A crane lifts the skid by its four corner eyes. A telescopic crane then lifts the chimney into place, using lifting points at the top of the shroud that let the hooks fall free once the jib is lowered.

Choosing the size

The quote priced three sizes: 1,000, 750 and 500 m³/h. The specification was otherwise the same. There was also a stainless steel option for the shroud and pipework, and a discount structure for ordering several flares.

Why it works

It works because the booster is already doing the hard part. A flare only needs gas delivered at the right pressure and a signal to start. Leaving out the boosters, knockout pot and drainage avoids duplicating plant that already works.

The trade-off is dependency. The flare relies on the existing booster’s output and on its controls. If the booster is undersized, the new flare will not make up the difference. The supplier also left out civil works, cranes, the power supply, the signal cable and any modification to existing pipework or controls.

What to consider for your own project

1. Check booster capacity. It must deliver the full flare flow at the right pressure.
2. Check the drainage. The flare package does not include condensate management.
3. Define the start signal. Decide who owns it and what happens on signal loss.
4. Allow for crane access. The chimney lift needs a suitable telescopic crane and a clear approach.
5. Confirm the regulator’s temperature and residence time. Look at the LFTGN03 guidance for your site type.

See also our post on sizing the gas booster for a ground flare.

FAQ

What is a bolt-on flare?

It is a flare package that connects to a site’s existing boosters and controls instead of bringing its own.

What does the flare need from the existing plant?

Gas at pressure from the booster outlet, a power supply and a start/stop signal.

What is turndown?

The ratio of maximum to minimum flow the flare can handle. 5:1 on a 1,000 m³/h flare means about 200 m³/h at the lowest.

Can the flare burn low-methane gas?

Yes, at lower temperatures, down to about 20% methane. Below that the pilot will not ignite and the unit can vent instead.

Adding flare capacity?

Tell us about your existing plant and we will outline a bolt-on option.