COVER STORY


PUMPS IMPROVE OPEX COSTS AT EFW PLANT


Peristaltic hose pumps outperform centrifugal pumps in flue gas desulphurisation (FGD) at a major energy from waste (EfW) plant


refineries, use lime to remove sulphur dioxide (SO2) from their flue gas output. The abrasive nature of lime presents a


I


problem to the dosing pumps and many facilities using centrifugal pumps, for example, have experienced recurring problems with seal failures, leading to excessive maintenance and repair costs. The solution is peristaltic hose pumps, such as the Bredel range from Watson-Marlow Fluid Technology Group (WMFTG). A recent case has seen the adoption of


eight Bredel pumps as part of a flue gas desulphurisation (FGD) process at a European energy from waste (EfW) plant. Used for dosing abrasive limestone slurry, the Bredel pumps help the facility gain greater control over its processes and reduce OPEX costs.


Lime is highly effective Lime plays a key role in many air pollution control applications. Calcium oxide (CaO - quicklime), calcium hydroxide (Ca(OH)2 - hydrated lime) and calcium carbonate (CaCO3 - limestone or chalk), can all be used to neutralise acidic gases and remove SO2 from flue gases. It is wet scrubbing that is


considered the principal flue gas abatement technique, where crushed limestone is added to water before the resulting alkaline reagent slurry is sprayed into a flue gas scrubber or tower. In a typical system, the gas to be cleaned enters the bottom of a cylinder-like tower and flows upwards through the limestone slurry spray. During a site visit to a


major EfW plant, running a 15- hour wet scrubbing operation, it was noted that centrifugal pumps were experiencing frequent failure when transferring abrasive lime slurry reagent. The


14 NOVEMBER 2021 | PROCESS & CONTROL


n order to stay within strict emissions thresholds, coal-fired and energy-from- waste (EfW), steel plants and oil and gas


principal problem is that slurry entering the scrubbers is both high in temperature and contains up to 25% dry solid content. Adding to these challenging characteristics, the slurry crystallises as it cools. Realising the requirement to change its


pumps in the wet scrubbing process to meet stringent industry demands, the European EfW plant trialled Bredel hose pumps. Such was their success in performing lime


slurry transfer operations across a five-day duty cycle that the plant now employs eight Bredel hose pumps.


The Bredel hose pump advantage The actual pumping principle is based on alternating compression and relaxation of the


reinforced rubber hose, drawing content in and propelling product away from the pump. As a result, the fluid being transported is only in contact with the hose, making it ideal for handling aggressive or abrasive chemicals, such as lime. • Pumps are virtually maintenance-free as


there are no expensive seals, valves, diaphragms, glands, rotors, stators or pistons to leak, clog, corrode or replace, leading to a much more controlled process and lower OPEX costs • A unique rotor design which does not rely


on the gearbox shaft protects the bearings of the gearbox from overloads which might occur in other hose pumps. This ensures trouble-free and long lasting operation, even in heavy duty operations • Hose life is repeatable, and is not impacted by abrasion or crystallisation


255,000 tonnes of waste incinerated Following the change from centrifugal pumps to peristaltic hose pumps, the energy from waste (EfW) plant reported a more controlled operation and much improved OPEX costs. On a typical basis, some 255,000 tonnes of


waste are incinerated at the facility from a total of 1 million tonnes collected. This process leads to the generation of 139,000 MWh of electricity, around 35,000 MWh of which is used by the plant, with the remaining 104,000 MWh sent to the grid. The success of the Bredel pumps is helping


the plant continue these operations and maintain its commitment to the environment.


Watson-Marlow Fluid Technology Group www.wmftg.com


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66