Vertical Cantilever Sump Pumps for Fume & Odor Scrubbing

Process Background

Chemical Processors and industrial manufacturers can generate large amounts of exhaust gases, which when vented to atmosphere need to comply with air quality regulations to ensure dust, harmful gases and odors are not emitted to nearby housing or occupants but also comply with environmental legislation. 

Scrubbers remove or neutralize harmful contaminants such as Sulphur, Dust, Chemicals and odors which are emitted by treating exhaust emissions to prevent pollutants being vented to atmosphere. Their operation is similar to that of a catalytic converter found within cars.

Units can be wet or dry, with Dry Scrubbers absorbing contaminants through the use of filters, or absorbers. Wet Scrubbers utilise chemicals such as Sulphuric Acid, Hydrochloric Acid, Urea, Chemicals, or fresh water to saturate emissions ensuring particulates are captured, neutralized or processed.

Recirculation Pumps are used within scrubbers, to atomise or inject fluids via nozzles situated within the emissions stack delivering the required spray pattern to capture and treat contaminants.

Current Issues

A packaging manufacturer was experiencing a drop in flow and pressure on their immersible sump pumps and removed them for inspection. On inspection it was found that the units had suffered from severe corrosion with the main suction pipe and immersed casing severely corroded.

The customer initially wanted us to perform an emergency repair however, when the unit was dismantled for inspection the impeller was so badly corroded it split in two, falling from the shaft. 

Inspection had been performed adhocly over the years with some parts replaced in more resistant metals – Stainless Steel to deal with the corrosion, but with other parts overlooked leading to an issue whereby the impeller was so badly corroded it was ineffective meaning that it was only able to recirculate fluid within the casing and not generate enough pressure to transfer the fluid to process.

When an impeller fails to discharge fluid from the pump it can lead to dangerous heating of the fluid, as the energy from the motor is transferred to the fluid within the tank. This can have severe consequences if the fluid is a chemical or flammable. This can be experienced not only as the impeller wears but also when the pump operates against a discharge head too high for the unit to handle meaning it operates below the minimum safe continuous flow area of its curve. 

The customer needed spare parts to enable the units to get backup and running, before looking at two replacement units which were needed urgently.

Cantilever Pump Design

The units installed were vertical Cantilever Sump pumps which are immersible pumps, with the motor stationed outside of the fluid. This enables the unit to handle corrosive and aggressive media which may otherwise penetrate the motor, and seals leading to failure.

Our XVI Cantilever pump design is of seal less design with only metallic or chemically resistant plastic parts installed within the fluid. Only one seal is situated within the fluid – a casing O ring and the only seals found outside of the fluid include a lip seal for protection of the bearings. 

Fluid is drawn into the casing via the mouth immersed in the liquid before being discharged through an outlet pipe located adjacent to the main column. The main column contains a set of double bearings helping to absorb heavy radial forces at the top of the column stationed outside of the liquid above a mounting plate. A sleeve bearing at the bottom of the immersed unit absorbs vibration and allows linear movement. The unit is long coupled to a motor via a separate coupling.

A self priming or immersed pump is a far more robust design of unit for this type of application. As they are not fully submerged within the fluid, they are less prone to motor failure and require infrequent inspection. These installed units had worked for over 12 hours a day, for 13 years with minimal maintenance required.  Conventional submersible pumps which are often used in sumps require frequent inspection (typically every 6 months). They use a close coupled motor typically manufactured by the pump manufacturer (only available from them), where as an immersed design utilizes standard motor sizes which are widely available. There are many benefits of an immersed pump to a submerisble which is explored in further detail in our Self Priming Vs Vertical Immersion vs Submersible Pump Guide. 

Our Solution

North Ridge immediately worked to supply spare parts to enable the customer to be back up and running within a short amount of time, with 2 units placed on order complete with emergency spares to prevent downtime in the future.

They produce 175M³H, and 45M³H, were 1M long and used to transfer and recirculate fluids injected into the emission stack.