Develop a preliminary process design for a modified ammonia scrubber system to increase the overall system capacity at a chemical manufacturing facility.
Process Engineering Associates, LLC (PROCESS) was subcontracted by the client, an engineering and design firm, for the ultimate client, a US chemical company manufacturing paint pigment, to perform an FEL-1 preliminary process design to modify the design of a purchased ammonia scrubber unit to achieve expanded capacity. The end client desired to scrub an ammonia-laden air stream with sulfuric acid using a previously purchased scrubber unit. The process was modeled in Chemstation’s CHEMCAD software. Process chemistries were modeled using OLI Systems’ OLI flowsheet software to predict scrubber pH and salt points. A material & energy balance was developed for the scrubber at the new vapor design rates. The updated design significantly increased the capacity of the scrubber by increasing sulfuric acid feed rates and adding a large scrubber sump for heat dilution while avoiding the addition of a new heat exchanger.
A sensitivity analysis was also performed on scrubber sulfuric acid concentration to minimize heat of absorption while maximizing brine concentration in the spent acid. System hydraulic analyses for various operating cases were performed to determine the required changes to the existing scrubber blower. A batch time sheet was prepared to determine scrubber brine neutralization, pump-out, and charge times. Scrubber internals were checked at the new design rates. The existing packing was deemed acceptable but new distributor spray nozzles were specified by PROCESS. Ancillary equipment, including sulfuric acid and caustic delivery systems, were specified and equipment process data sheets generated. A modified process PFD and P&IDs were also provided to the client as part of the deliverables package.
- Preliminary process design
- Scrubber system design.