Hose Pump Cuts Waste-to-Energy Plant Maintenance Costs

The trial of a new APEX35 hose pump from Watson-Marlow Fluid Technology Group at EEW Saarbrücken GmbH, a producer of energy from waste, has indicated the significant potential savings in pump maintenance costs, the company says.

Not only is the APEX35 pump able to run without clogging, for a much longer period when pumping abrasive brine at EEW, but downtime and the cost of replacement parts is reduced greatly.

EEW Saarbrücken GmbH, MHKW Pirmasens operates a waste-heat power plant in Pirmasens, Germany. Each year the facility recycles around 180,000 tons of waste, generating around 75,000 MWh of electricity as well as 25,000 MWh of district heating. These figures also allow some 52 million liters of heating oil to be saved in energy production every year.

Among the site’s operations is the separation of crystalline sodium chloride from its highly concentrated solution in the process water before disposal. Here, a special centrifuge is used as a thickener to separate the solution from the abrasive salt slurry (density 2.16 kg/l), which is called brine or “solebrei.”

EEW has been using a progressive cavity pump to feed the centrifuge (flooded suction, 1 bar back pressure), for approximately 1.5 hours every three to four hours in a 24/7 operation. However, the abrasive nature of the brine demanded the repair of the pc pump stator or rotor every month, along with occasional replacement of the linings. Furthermore, not only would it take a minimum of four hours to perform the repairs (using expensive replacement consumables), but the pump would also have to be removed from the process line.

Dissatisfied with the situation, plant engineers at EEW requested a trial of the new Bredel APEX35 hose pump. This model was selected because it was thought to offer the greatest potential maintenance savings in this abrasive handling, intermittent duty application.

During the first six months of the trial, the APEX35 required no maintenance whatsoever. Additionally, as the only wear part in APEX pumps is the hose, this could be replaced quickly (20 minutes) and easily without removing it from the process line. Considering that a replacement stator alone for the progressive cavity pump costs around €1500 ($1,686), the projected payback period for the APEX35 hose pump is extremely short, the company says. In addition, there is the saving in inventory as only the hose will need to be kept in stock.

When handling abrasive substances, a major advantage of hose pumps is that they have no costly wearing components like seals, valves, membranes, stators, rotors or glands to maintain. Self-priming, dry running, and with no internal valves, hose pump technology also helps users improve their processes by eliminating troublesome ancillary items like anti-siphon valves, back-pressure valves, degassing valves or run-dry protection. Consequently, APEX hose pumps are suited for handling difficult fluids — abrasive, corrosive, viscous, shear-sensitive, gaseous, crystallising, or even fluids with a combination of these properties.

Emissions at the Metro Vancouver waste-to-energy facility have been reduced by 53 percent since the beginning of the year due to an updated emission control system by Covanta.