Sep-2020

Horizontal incinerator reactor scans identify catalyst loss and provide insight to repair efficiency issues

Tracerco technology can see inside the very heart of operations to determine why processes are not operating as expected.

Nicola Porter
Tracerco

Article Summary

Most people have the idea that tower scanning is limited to vertical equipment, but if we apply a little bit of innovation, engineering and physical access, we can perform vertical scans on unique catalyst incinerator horizontal vessels as well. In most cases, scans can identify mechanical placement of internals if proper techniques are applied.

Refineries are proactively reducing their energy consumption and emissions of greenhouse gases with harmful pollutants such as sulphur trioxide (SO3) by replacing their thermal incinerators with a catalytic variant. These incinerators are the final step in the sulphur complex and are designed to convert the remaining traces of sulphur compounds, including H2S, COS and CS2, to less harmful SO2 before being released to the atmosphere.
Thermal incinerators are normally operated around 700°C and can produce SO3. Catalytic incineration provides an energy-saving alternative, as it operates at about 300°C. The use of catalyst behind a tail-gas unit can offer savings of 60% in fuel that would be required for a similar thermal incinerator.

The Field Test
In this specific case our customer’s incinerator reactor had not been performing as expected. There were issues with abnormal temperature distribution throughout the catalyst bed and H2S readings at the stack above the expected.

The customer contacted Tracerco to see if our gamma scans could provide detailed information that would shed some light on why the vessel was not operating as expected.

Tracerco performed nine vertical scans over the length of the vessel at key positions to investigate the air distributor and catalyst bed positions as shown in Figure 1.

Figure 2 is the density graph profile generated from the nine scans. The height of the density responses from the nine scanlines were measured, in relation to the bottom of the bed support.

Percent responses were then overlaid on the vessel drawing. Figure 3a illustrates the scanline responses to remaining bed height %, allowing our customer to visualise the internal bed profile.
 
The Conclusion
The scans revealed a large volume of catalyst was missing from its intended position with less than 30% remaining above the gas distributor. Scan results played a key role in the customer’s decision to shutdown the incinerator reactor for inspection. Receiving the scan results in a timely manner allowed the client to preorder and have this unique catalyst onsite prior to entry, reducing unnecessary downtime waiting for materials.

If the customer had shutdown the incinerator reactor and discovered these issues after entry, they could have incurred additional replacement costs on an emergency basis and additional downtime waiting for this unique catalyst to be shipped to the plant site.

After entry and repairs were completed, the client relayed their findings to our team. Tracerco is ready to help when more information is needed when troubleshooting your own process plant problems or trying to optimise process efficiency.