How to control the pressure drop of the activated carbon adsorption box?

Controlling the pressure drop of the activated carbon adsorption box needs to start from many aspects such as design, operation, and maintenance. The following are the specific control methods:
1. Optimize the performance of activated carbon
Select the right size
The larger the particle size of granular activated carbon, the smaller the bed resistance. For example, the selection of 4-8 mesh (about 2.36-4.75mm) activated carbon particles can significantly reduce pressure drop. However, the adsorption efficiency needs to be balanced, and if high concentrations of pollutants are treated, graded filling (coarse particle bottom + fine particle upper) can be used.
Replenish or replace activated charcoal regularly.
When the activated carbon is saturated or crushed, it is timely added with new carbon or replaced as a whole to avoid pore blockage resulting in a surge in resistance. For example, when dealing with dusty waste gas, it is recommended to check the activated carbon layer every 3 months, and it is found that the powder is serious and needs to be replaced immediately.
2. Improve equipment structure and design
Optimized airflow distribution
The air distribution plate or guide blade is installed at the intake port of the adsorption box to ensure that the gas evenly passes through the activated carbon bed to avoid excessive local flow rate. For example, the use of porous plates (20%-30% opening rate) with diversion cones can reduce the pressure drop by about 30%.
Increase the cross-sectional area and reduce the flow velocity of the empty tower.
The flow rate of the empty tower (gas flow rate/cross-sectional area of the adsorption tank) is controlled within the range of 0.1-0.3m/s, which can effectively reduce the pressure drop. For example, if the original design flow rate of the empty tower is 0.4m/s, the flow rate can be reduced to 0.2m/s by increasing the cross-sectional area of the adsorption box or connecting multiple devices in parallel.
Set up a blowback or self-cleaning device.
The compressed air backblowing system is installed on the top of the adsorption box to regularly purge the dust or impurities on the surface of the activated carbon. For example, backblowing for 30 seconds every 8 hours of operation can maintain the pressure drop within ±10% of the initial value.
3. Control intake conditions
Pretreatment to remove impurities
Add a cyclone, filter, or scrubber in front of the adsorption tank to remove dust, oil mist, or viscous substances in the exhaust gas. For example, when dealing with spray paint exhaust gas, the paint mist is removed with dry filter cotton first, which can extend the activated carbon pressure drop to more than 1 year without replacement.
Regulate temperature and humidity.
High temperature and high humidity environments can easily lead to activated carbon hydrolysis or pore plugging. It is recommended to control the intake air temperature below 40 ° C and the humidity ≤80% RH. If this cannot be avoided, a condenser or drying tower can be installed in front of the adsorption box.
4. Optimize operation parameters
Control adsorption time and regeneration cycle
For activated carbon that can be desorbed and regenerated (such as catalytic combustion regeneration), set a reasonable adsorption time (such as 2-4 hours) to avoid excessive adsorption resulting in increased resistance. The regeneration temperature should be strictly controlled within the tolerance range of activated carbon (usually ≤800℃).
Avoid frequent starts and stops.
Frequent start-stop will lead to increased friction of activated carbon particles and produce more dust. It is recommended to keep the equipment running continuously. If it needs to stop, reverse blow and purge should be performed first.
5. Regular maintenance and monitoring
Real-time differential pressure monitoring
Install a differential pressure sensor to trigger an alarm when the pressure drop exceeds 50% of the initial value, prompting you to check or maintain. For example, an electronics factory controlled the pressure drop fluctuation within ±15% through the differential pressure monitoring system.
Check and clean up regularly.
Check the activated carbon layer every month for hardening or ash accumulation, and conduct a comprehensive cleaning every six months. For the wastewater treatment adsorption tank, it is necessary to periodically backwash to remove the trapped suspended matter.