Lean Gas Low Calorific Flare

The Uniflare Lean Gas flare is targeted mainly at the stage of a landfill site where gas is of a quality unsuitable for power generation but is still a considerable environmental risk. Sites where the flare stack installed was designed for a much higher calorific gas and a flow much higher than is now available. This causes a number of issues but mainly its cause an erratic extraction of gas from site. The current flares need to allow the gas quality and quantity to build before it can operate. During this time migration can occur and odour is released. This can also break the seal around the well. Once the flare operates this causes over extraction causing air increase, dramatically increasing the risk of fires. This can lead to large areas of the site being isolated due to high CO readings. Again, this makes balancing the field difficult and ultimately leads to uncontrolled migration. This operation massively increases the labor required on a site due to nuisance trips needing additional balancing. It also causes public nuisance coinciding in complaints and increased scrutiny from agencies. Again, bringing fines and increased management time.

The Uniflare lean gas flare is designed and has proven to remove all of the above. Due to its operating range we spend time commissioning the flare stack, effectively carrying out a pumping trial to match production and control migration. This is included in the cost of the flare package The Uniflare Flare operates within a wide range of calorific values and has a wide flow range at these low gasses. This results in the ability to apply steady extraction on the site removing all of the issues listed above. In addition to a controlled approach to extraction the Uniflare Lean Gas Flare has a remote access and remote reporting feature included in every package. In the unlikely event should the fully automated control fail. Our remote system will notify a select number of engineers to inform them. It will detail the cause of the failure, log this in the reporting system and allow the engineer to reset the fault and restart the unit without attending site. This reduces downtime, callouts, loss of extraction to the field, migration, complaints and fines.

Please see our specification below.

The UniFlare™ UFLG10 range is a Uniflare Standard design that has been widely used across the UK and globally for more than 20 years. It provides a neat compact unit designed for sites with declining gas flows and gas quality which are either closed or had power generation removed. The unit is unique in its design in that it can operate with both high and low calorific values of landfill gas and further into the future when gas qualities drop further to below 11% – 15% CH4. The unit comes complete with the equipment required to combust this low CV gas without further modification.

The UniFlare™ UFLG10 can come both containerised and non containerised depending on budget and requirements. The container can be supplied in either 10 foot or 20 foot with the larger option providing a larger control room for items such as a desk, workshop and storage, which can prove useful especially when the site is closed and there are no other onsite facilities.

The UniFlare™ UFLG10 is fully proven technology and been supplied to many Waste Management Companies and Local Authorities it is fully compliant in terms of, DSEAR, ATEX, CE and meets all the Environment Agency Guidelines for Flaring Landfill Gas and Emissions Compliance.

The minimum methane concentration for combustion at specified temperature: 11%

The UniFlare™ UFLG10 pipework is supplied in Stainless Steel for longevity and skid frame in galvanised mild steel as standard.

SPECIFICATION

• Nominal LFG flow: 5-500 Nm3/hr
• Typical methane range: 11-55%
• Minimum Methane Concentration: 11%
• Combustion Temperature: 1000 °C
• Standard Pressure rise 120mb
• Remote Access and Operation to mobile or PC/Tablet
• HMI with Data Logging
• Compact Design – Skid Mount, Trailer Mount or Containerised
• Easy Installation
• LFTGN-05 Emissions Compliant
• DSEAR, ATEX, Compex and CE complaint
• Can operate and support mini gen or micro turbine generation

Site Trial

Rivacre is a closed site with a declining gas yield. The current flare stack is now operating outside of its design parameters in both flow Nm3hr and Quality % Methane. To operate with this flare stack, it is necessary to over extract on the site for a period of time until the site depletes of gas and then switch of the flare to allow the field to recover. This is not an optimal way to run the site from both and Environmental and safety point of view. This approach can cause migration to occur due to the time between the site depleting of gas and recovering being affected by various influences, atmospheric pressure, leachate levels over extraction etc. The time between depletion and recover can vary significantly and missing this timing can create an overpressure in the site creating migration pathways.

We worked Cheshire County Council to trail the Uniflare Lean gas flare stack to steady the flow of gas from the site. The flare stack needs to be emission compliant, be able to operate at a wide range of flows and gas quality. Due to the location of the flare compound and the public access the flare also needs to be extremely quiet.

The flare stack was installed and after commissioning and initial pumping trial has ran continuously only stopping due to external factors, extremely high winds being one of the causes, but a fix has been installed to overcome this issue.

As you can see from the reports the flare continues to perform well. The remote access monitoring and the ability to remote start / stop the flare stack has significantly reduced the number of manual interventions required both on site and on the equipment. Site performance can be monitored remotely, and correct action taken based on suction pressure, quality or gas quality in the form of balancing the field. This can now be programmed in rather than it being an emergency response to site.