Project AA – Food Grade stainless steel Circular CleanPulse filter with insulation and stainless cladding

AT A GLANCE:

• 304L Stainless Circular Filter with 50mm thick insulation with a stainless-steel outer skin
• Outer shell surfaces to have 2B mill finish, welds ground smooth, strip polish appearance.
• Internal welds ground smooth and all internal surfaces polished to 0.6Ra.
• ATEX rated with explosion panel and ducting.
• CFD Modelling for design for non-deformation at maximum suction pressure -0.14 Barg

PROJECT MANAGERS REPORT:

Our client was installing a new milling plant in Ireland which needed a filter to capture the milled caseinate product and abate the fugitive dust emissions.

This was our clients third repeat order for a circular reverse jet cleaning filter the last two filters were supplied by an alternative supplier.

The new filter was to be installed in place of an existing storage silo and therefore needed to fit within specific dimensions keeping in mind the filtration velocity and interstitial velocity which our client wanted to replicate what was already on site as they knew this worked for their process. The filter was also accessible across two levels so we needed to ensure that the top of the filter and the pulse tanks could easily accessed and that the filter support legs picked up with the steel framework below the floor this required a site survey prior to the final design.

The CPB228 is fully fabricated in stainless steel and had been designed for an operating pressure of - 0.14mbar. The filter is insulated with 50mm rockwool insulation and has been cladded with stainless steel sheets which have a 2B mill finish with the welds ground smooth with a strip polish appearance. All the filter internal welds have been ground smooth and all internal surfaces have been polished to 0.8Ra.

As the dust is organic with an explosive potential there are two explosion panels to be fitted with the explosion ducting to be vented to outside. The pulse cleaning equipment also needed to be ATEX zone 22 classification.

Our client’s client wanted to keep continuity of spares; we designed the filter to house the same size bags using the same filtration media. The stainless-steel cages were of a split design as there was a restriction on height.

Due to the process the filter needed to be able to withstand a maximum operating pressure of a -120mbar but the filter casing needed to be designed for a non-deformation at maximum suction pressure of -0.14 Barg. This meant that once we had designed the filter, we needed to carry out CFD and FEA studies on the proposed design.

To CFD study was done to examine flow through the filter body and to examine the flow directions across the bag interface. It was also intended to examine the impact of the flow diverter on the inlet to the filter.

The FEA study looked at four key elements.

The suitability of the filter roof design to with stand both the operating pressure and the maximum pressure the fan can generate.

The maximum “blow out” pressure for a panel to stop explosive pressure waves damaging the filter body.

The suitability of the PFC ring that supports the main filter body.

The lifting lugs being suitability for the design. Elements of the roof design were optimised to pass the required pressure tests with a safety factor, while minimising plate and section sizes.

The end user in Ireland had a preferred fabricator also in Ireland that they wanted us to use to manufacturer the filter. As part of our QA and due diligence we travelled over to Ireland to inspect the filter with our client and our clients’ client to ensure that our high manufacturing standards were in line with ours and our client’s expectations.

As this was a supply only we didn’t get involved with the installation or commissioning of the plant but due to us having a good relationship with our client we have been sent some photos of the installation.