Biogas desulphurisation
This waste water treatment centre needed to replace the carbon media that they use for biogas filtration processes.
Key achievements
Extended lifetime
UL 900 certified (fire rating)
ISO 10121 ASTM D6646 qualified
Solution
In order to replace the exhausted non-fire rated media Camfil supplied 5 tonnes of Campure 32. This is a media specifically designed for biogas filtration, which was delivered and installed in the customers filters by February 2021.
The customer was concerned about monitoring the filtration capacity of the media so sensors were installed by the customer at the inlet and outlet of the filter to monitor the media’s performance and detect when it is time to change it.
Process overview
Our client is a wastewater treatment centre located in the North of France.
- Type of digester: Continuous liquid digester 5 m in diameter and 26 m high
- Biogas output: 530,000 Nm3 in 2023, i.e. 60.5 Nm3/h (biogas very rich in methane, ~ 80%)
- H2S concentration: 2000 ppm
- Use of biogas: fuel for a boiler used to heat a tank for digesting waste water sent by the nearby production and bottling site (digestion of the large quantities of sugar sent)
- Filter in place: conventional tank (cubic) measuring 2 x 2 x 1.5 m = approximately 6 m3 usable volume with biogas fed through the bottom of the filter filled with activated carbon.
The customer needed to quickly replace the carbon media, which had reached saturation point after a year’s operation. Their current supplier did not have any stock of this media type so they called Camfil.
Once the old media was removed from the filter beds, it was evident that the exhausted non-fire-rated media had began to burn, which could have caused a fire in the facility.
Challenges
Provide a filter media or “carbon” capable of filtering H2S emissions
Find a molecular media that does not ignite when used and removed from the tank
Results
Camfil sold the media replacement solution (nitrogen inerting, emptying of competing used carbon and refilling of the filter with new Campure 32 media). The customer noted an H2S content at the filter outlet of 0 ppm throughout the operating period.
It was not until November 2023, i.e. 34 months of use later (approximately 1020 days), that the performance of the media deteriorated very rapidly (load factor estimated at 82%) compared with approximately 12 months with the old competing media. 36 months later, at the beginning of 2024, the same service (inerting, emptying and refilling with new Campure 32) was renewed.
No start of fire was observed on the used Campure after it was removed from the tank: Campure 32 is UL 900 certified (fire rating It should be noted that filling the filter with the 5 tonnes of Campure 32 was completed fairly quickly, in around 45 minutes.
The customer is very satisfied because he has saved time and money by changing the media 3 times less often. Even with a purchase price of Campure 32 25 % higher than that of competing media, for a 3-year operation, he saves not only on the cost of the filtering media (the competing carbon should have been 2.4 times more expensive) but also on all the additional expenses (labour, handling, storage, transport, waste management, etc.).
