How we can make our system more efficient and greener?
After the upgrading the gas in the DMT plant, the CO2 is separated from the CH4. The CH4 upgraded up to 99% goes into the gas grid and the CO2 to the atmosphere.
The whole idea is to finish the process with a CO2 recovery technology. Pentair Haffmans, a Dutch Company, has been involved in CO2 recovery systems for years where the CO2 is upgraded up to 99.99% and it can be sold as a product.
The CO2 recovery system consists of a process where CO2 coming from the DMT is cleaned. The process starts with the gas coming from the DMT (CO2 98.7% + CH4 1.3% + none condensable gases) being compressed up to 17Bars.
Then the gas goes through an ACF drier where some impurities are eliminated. The last part of the process is where the CH4 and none condensable gases are eliminated due to a different condensation point temperature. The reboiler contains CO2 liquid that boils the gas coming from the ACF. This gas is cooled down to -30 degrees and -43 degrees in two steps. The none condensable gases are eliminated and the CO2 in the liquid phase goes to the storage tanks with a 50 m3 capacity each, a total of 150 m3.
The final step is to certify the tanks with CO2 liquid. This operation is done by AirLiquid where the CO2 is analysed for a quality check. Once it is certified the same company will send tankers to collect the CO2. Our daily production is 32 tons of CO2.
The CO2 recovery means that our system has no waste. The separator separates the liquid from the solids and both of these are the perfect fertilizers and the gas from the digesters is used to produce electricity, gas into the gas grid and the CO2 is recovered from the upgrading plant and sold as a by-product.