Project HJE – Partial Offline cleaning Filter

Project HJE – Partial Offline cleaning Filter

AT A GLANCE:

• Partially offline cleaning filter
• Structural calculations for penthouse, access platform and offset support structure.
• Upgraded discharge system to handle 7tph at a bulk density of 2,487kg/m³
• Bespoke Controls system with integrated pulse control cleaning.

CONSULTANT’S REPORT:

After years of talking to our client and producing multiple quotes with various options we were finally awarded the project on variation L!

The main drive of the project was to replace the existing filter which had been installed over twenty-five years ago which served the rotary kiln dryer.

Our client is the leader in the responsible recycling and production of resources essential to modern life. Backed by an international network of smelters, they are the largest producer of lead and lead alloys used in energy storage solutions and a range of other industrial and commercial applications.

The site reclaims scrap batteries and use state of the art technology and a highly trained workforce to ensure the lead acid batteries they recycle into refined lead do not harm the environment, employees, or the community in which they work.

The existing filter was over 50m away from the rotary kiln dryer, and due to the large ducting run over a period of operation the system needed to be shutdown to allow the ducting to be cleaned due to the dust loading and density. This was having an impact on the production downtime and a significant cost.

The rotation dryer is used to dry the crushed lead acid battery products prior to inputting this into the furnace to reclaim the lead which is then made into ingots.

The equipment we supplied for this project broadly comprises of:

• Insulated CleanPulse ‘Partial offline’ bag filter designed for 56,018Am3/hr @ 100°c
• Large access platform which integrates with an existing walkway
• Fully cladded Penthouse with lifting beam for maintenance
• 20kW of Trace heating
• Acoustic cleaners
• One outlet valve per section for partial offline cleaning with local desiccant dryer for instrument air
• Discharge system (horizontal screw, Rotary valve, and inclined screw back into clients drag link conveyor
• Double Zoned spark detection and quench system with a filter deluge
• Filter inlet ducting with flow probe, air bleed valve and temperature probes
• Outlet header ducting with dust monitor and temperature probes
• Outlet ducting which connected to the existing filter inlet ducting
• Existing filter bypass ducting
• 160kW Centrifugal fan with discharge silencer & connecting ductwork
• Bespoke Siemens control hardware and software design

Originally, we were tasked with designing a bespoke filter which would be sited closer to the dryer to reduce the inlet ducting run and avoid shutdowns for cleaning.

The issue we faced was the location that the filter was going to be in was an inclined road which was used to transport the feedstock and other by-products around site using lorries and the sites large dumper loaders.

Therefore, we had to increase the length of the filter and reduce the width to avoid encroaching the road. We also had to ensure that the ducting was at a height to allow the traffic to pass under safely.

To ensure that the highly dense dust (2,287mg/m³) would be carried through the filter inlet ducting avoiding dropout, and then be balanced across the filter we carried out CFD analysis.

At first the client wanted the filter installed within a 5-week window to coincide with the site summer shutdown (2 weeks) Initially we were tasked with fitting the existing filter bypass ducting whilst the plant was operational two weeks before the shutdown dates.

The new discharge for the filter system compromised a large horizontal screw, rotary valve and inclined screw which then fed into the clients drag link conveyor to convey the dust discharged back into the dryer. The issue we had was the mammoth task of cutting a hole in the existing building to allow the inclined screw to be place above the drag link conveyor.

The concrete wall was a metre thick and required a specialist drilling company to undertake the works.

The meant that the filter placement was crucial.

Our client was tasked with ensuring that the ground was suitable to withstand the load of the filter and engaged a civils specialist to provide the pads for the filter to sit on.

It transpired that road wasn’t suitable without extensive modification and being on an incline we needed to stagger the filter support legs to match the concrete pads.

Due to above and the client wanting an access platform for maintenance for the outlet valves and a penthouse we used a structural engineering company to provide calculations for the additional load on the filter and support structure. This was then used to liaise with the civils engineers to design the plinths for the filter.

Once the filter support structure and hopper were craned into position and bolted down, the large excavation for the plinths was then back filled with 100cu.m of concrete to avoid any uplift of the filter in windy weather environments.

Once the filter and ducting has been installed, we installed the large penthouse and stairway to pick up with the existing walkway.

Client testimonial

As described in the case study, the problems seen were linked to the previously used filter was in poor condition and over 50 metres away. This left is in a vulnerable position of having regular down days to carry out cleaning tasks. Cleaning tasks not only caused downtime, but also exposed employees to a thankless task laden with risk.

Firstly, Health and Safety was at the forefront of Filter Designs project. The RAMs they developed, and the safety standards demonstrated were commendable. Each person attending site willingly accepted our strict rules surrounding PPE, RPE and safety practices, and was found to always adhere to them when audited.

Filter Designs provided an incredibly in-depth service, from design through to commissioning. We are not the easiest company to work alongside due to our unique processes, dust type and run rate requirements. Filter designs demonstrated incredible patience and perseverance to make the project successful. Due to unforeseen issues with our dust offloading system, we required the option to switch between the new and old system. Filter designs delayed the completion of the project for us whilst we became confident in our system, then came back to install the penthouse. What impressed me the most throughout the project was the focus being so heavily on providing solutions for problems and delivering a working system, when the problems encountered were unforeseen and no fault of Filter Designs. This demonstrated to me that their company ethos is proven to be delivering collaboration and customer satisfaction, not just selling a product.

Due to the success of the project, we have commissioned the designs of another filter. I would recommend anybody explore their dust filtering solutions with Filter designs.