A catalyst production facility operates a calciner that generates a small stream of hot dirty gas. The exhaust is cleaned using a particulate/SO2 scrubber followed by a vertical entrainment separator. The configuration is problematic for operation. The scrubber requires a long duct run from near grade to the scrubber inlet flange. There is a U-shaped bend to the inlet flange. Particulate condenses in the duct and plugs over time. The process is routinely shut down to clean out accumulated material. This limits production capacity. The customer sought to redesign the scrubber to increase production while maintaining as much of the original equipment as possible.
The customer selected Envitech to redesign and supply a scrubber to be retrofit into the existing system. The scrubber inlet was replaced with a high efficiency Hastelloy Venturi scrubber for particulate removal. The Venturi length was significantly decreased and oriented at an angle to the entrainment separator inlet. The shorter distance and angled orientation significantly reduced the duct run from the calciner outlet to the scrubber inlet, minimizing fouling potential.
The top of the entrainment separator was replaced with a packed bed absorber to neutralize and remove SO2. Structural modifications to the existing vessel ensures the new packed bed is well supported.
After the Venturi, the gas enters the bottom of the packed bed and travels vertically upward, counter current to downward flowing water. Excess water from the Venturi and the packed bed collects in a common sump. Caustic solution injected into the recirculation line neutralizes acid gases. Liquid recirculates back to the Venturi throat and top of the packed bed. The gas passes through a vertical entrainment separator above the packing to remove water droplets before exiting the system.
The scrubber was put into service in early 2021. A continuous emissions monitoring system (CEMS) confirms emission limits are met. The duct clean out time has been reduced from 24 to 36 hours to < 1 hour. System uptime has improved from < 60% to > 80%, enabling higher production capacity. The Venturi scrubber is significantly smaller in size, making replacement cost less expensive. The scrubber is designed to meet the process conditions below:
- Flow rate: < 1,000 acfm
- Inlet Temp, 400 oF
- Particulate removal: > 99.8%
- SO2 removal: > 99.9%
Click on the link below to download literature about the catalyst Calciner scrubber.