How to Design a Pollution Control System Using Centrifugal fans

A facility manager in Kenya called us last month with a familiar problem: their centrifugal fan system was running but not delivering the expected airflow for their petrochemical operation. After walking them through our diagnostic process over the phone, we realized that most of the issues could have been avoided during the planning phase. Here is the complete procedure we follow.

Gather the Project Data

Every successful centrifugal fan project in the petrochemical sector starts with accurate site data. You need three pieces of information: the design airflow (5,000 to 50,000 m3/h), the total static pressure (1,500 to 8,000 Pa), and the operating environment details. The environment includes ambient temperature (0 to 250 C), air quality, and any special requirements such as fire rating or explosion-proof construction.

In Kenya, local building codes may impose additional requirements on centrifugal fan installations for petrochemical facilities. Check these early in the process to avoid redesign later.

Documentation is another area where petrochemical facilities in Kenya often fall short. A comprehensive centrifugal fan record should include the original specification, the certified performance curve, commissioning baseline data, all maintenance readings, and a log of any modifications or repairs. This documentation supports warranty claims, compliance audits (API 661, ATEX 2014/34/EU), and replacement planning. Facilities that maintain this documentation consistently report faster regulatory inspections and lower overall compliance costs.

Evaluate Your Options

With the project data in hand, evaluate the available centrifugal fan configurations. Consider not just the performance at the design point, but also part-load efficiency, noise characteristics (65 to 85 dB(A)), and maintenance access. A unit that is slightly less efficient at full load but significantly better at part load may be the better choice for a petrochemical application with variable operating schedules.

Material selection (SS316L with Hastelloy overlay) should match the operating environment. The ISO 9001 and IECEx certifications required by your project may also limit your options.

Documentation is another area where petrochemical facilities in Kenya often fall short. A comprehensive centrifugal fan record should include the original specification, the certified performance curve, commissioning baseline data, all maintenance readings, and a log of any modifications or repairs. This documentation supports warranty claims, compliance audits (API 661, ATEX 2014/34/EU), and replacement planning. Facilities that maintain this documentation consistently report faster regulatory inspections and lower overall compliance costs.

Prepare the Installation Site

Before the centrifugal fan arrives, ensure the foundation is ready, the electrical supply is in place, and the duct connections are prepared. The foundation must be level and able to support the equipment weight plus dynamic loads. Allow adequate clearance for maintenance: at least 1 meter on the motor end and 0.5 meters on other sides.

For the 2.2 kW motor, confirm the cable size is adequate for the full-load current and the run length from the distribution panel. The IE1 motor class requires a compatible VFD if variable speed operation is planned.

Documentation is another area where petrochemical facilities in Kenya often fall short. A comprehensive centrifugal fan record should include the original specification, the certified performance curve, commissioning baseline data, all maintenance readings, and a log of any modifications or repairs. This documentation supports warranty claims, compliance audits (API 661, ATEX 2014/34/EU), and replacement planning. Facilities that maintain this documentation consistently report faster regulatory inspections and lower overall compliance costs.

Commission and Document

After installation, run the centrifugal fan at design speed and measure the operating point. Compare airflow, pressure, and motor current to the design values. If the operating point is off by more than 5 percent, investigate before adjusting the system. Common causes include duct leakage, unexpected system resistance, and incorrect fan speed.

Record all commissioning data including vibration baseline readings. This documentation is essential for warranty claims, API 661 compliance, and future maintenance planning.

Our field engineers in Kenya have observed that centrifugal fan systems in petrochemical applications often operate at conditions different from what was assumed during design. The most common discrepancy is system resistance: actual duct pressure drop frequently exceeds the calculated value by 10 to 25 percent. This is why we recommend including a 10 percent safety margin on static pressure and verifying the operating point during commissioning against the certified performance curve.

Common Specification Mistakes

After reviewing hundreds of centrifugal fan specifications for petrochemical projects, several recurring mistakes stand out. The most common is specifying only design airflow and pressure without stating the actual system curve. The second is neglecting system effect, which can reduce delivered airflow by up to 20 percent. The third is under-specifying material requirements — a centrifugal fan in a mildly corrosive environment will develop impeller fouling within 3 to 5 years if SS316L with Hastelloy overlay is used without appropriate protection.

Other frequent issues include forgetting to specify the motor efficiency class (IE1 should be the minimum for new installations), not requiring factory performance test data, and omitting noise requirements (65 to 85 dB(A)).

Conclusion

From specification to long-term operation, a centrifugal fan in a petrochemical application performs best when the engineering basics are done right. The data and practices shared in this article come from our 28 years of manufacturing and field experience. Our engineering team in Kenya is ready to support your next project.