Project VC – Turnkey Flue Gas Treatment Plant for Waste Boiler

Working with CSS Renewables and end user VC Cooke in Beccles, Suffolk.

An empty warehouse is always a welcome place to start a project.  This is because we have a blank canvas with which to design an ideal layout for a flue gas treatment plant.  Once installed, our system cleans the gases from a waste boiler and waste infeed plant and will allow the end user to stop transporting waste around the country and manage it locally, save on transport costs and produce some electricity too.

Our scope started at the boiler outlet flange and ended at the chimney entry flange.  CEMS, the chimney and compressed air were by others.  Therefore, our scope included:

CleanSPARK spark arrest box

CleanPULSE hot gas bag filter

CleanSORB sodium bicarbonate silo and ash silo’s

CleanPAC activated carbon rip and tip hopper

After a period of layout and design work and a detailed internal design review, with client GA approval fabrications commence and are then periodically checked as the project progresses.

Once the fabrications are ready and have been checked, they are loaded to heavy haulage.

Assembly is checked at the fabricators  premises to ensure correct fitting alignment, then loaded in whatever assembly orientation suits site installation.  In this case due to low roof height and the need to extract filter bags from the top access doors of the filter, we split the installation on the horizontal plane, sending the filter hopper, main case section and top sections separately.

The 4.2m diameter silo just fitted out of the fabricator’s roller shutter doors.  With the silo skated out to the front door, the hiab on the heavy haulage transport lorry is used, with outriggers spanning over the road

Due to the 4.2m width, the first part of the silo’s journey required a police escort. Then a long slow 8 hour journey to site where the first larger pieces of kit are offloaded.

The hiab is made use of again to offload on site.

The use of transport cranes to install the bigger bits of equipment is an efficient use of modern vehicles.  In this case two hiabs are used to offload and install the filter case section on top of the hopper.

The sodium bicarbonate silo installation was particularly tight.  Correct planning using load charts and known weights, considering the capabilities of the lifting equipment is essential.

Once the main equipment is in place it is insulated, clad and painted.  A lot of smaller works can then commence – suction lines, compressed air pipework, electrical connections, blow lines and some operator training.

In the adjacent warehouse which houses the boiler, the CleanSpark box is installed next to the boiler.  This directs the incoming gases, which could contain embers alight if boiler conditions are not optimal, through a torturous path and finally through a grid.  It is optimised for pressure loss using computational fluid dynamics software.  The CleanSPARK box has two hoppers to each discharge point, which are combined into one for discharge into a sealed skip.

With a whole warehouse section dedicated to flue gas treatment, the layout is ideal.  Drawing in the gases from the boiler room in the adjacent warehouse, we dose sodium bicarbonate and activated carbon.  Ash collected by the main filter is drawn up into an ash silo for low maintenance operation.

The ash silo collects around 38 tonnes of waste ash or APCR.  This reduces labour effort and allows the most efficient disposal route via tanker.  The silo has various dust discharge aids all controlled using compressed air and a tidy air management panel.  Silo internal weight is continuously monitoring using the load cells it sits upon.

The silo is then able to discharge to an APCR tanker outside using loading bellows.  These bellows have a pendant control which allows the bellows cone to be raised and lowered.  Once the tanker is in position, the bellows are lowered, an integrated reverse jet pulse filter provides extraction and the dust is discharged.  A rotating paddle level probe indicates when the dust level in the tanker is high and then the process can be repeated at the next tanker loading port.

With this work done, cold commissioning was progressed to prove all of the motors, instruments and valves.  Suitable analogue feedback values are checked from temperature probes, motor directions are proven, air pressure are set ready for hot commissioning.