Johann Vetter explains how giant progressing cavity pumps with capacities of up to 1,000m3/h are being designed and built
The global hunger for oil and gas continues unabated, which means that exploration companies are striving to achieve higher and higher yields and are increasingly developing difficult sources, such as heavy fuel oils with an extremely high solid content.
Progressing cavity pumps, which ensure stable conveying rates irrespective of consistency, are used for the smooth transport of the respective media, in most cases abrasive and corrosive mixtures of oil, gas, sand and water.
For the high volumes required, Netzsch developed the L.Cap high-performance pumps for up to 1,000m3/h at pressures of up to 20 bar. The company has now built a new, specially designed production hall at its headquarters in Waldkraiburg, Germany to assemble the machines that are up to 15m long and weigh up to 25 tonnes.
As with all progressing cavity pumps, the technological basis for the L.Cap is the interplay of a helix rotor turning in a stator that is geometrically adapted to it. This conveying principle ensures transport at stable pressures with consistent flow rates, even where there are highly viscous and multiphase fluids with high sand or gas content.
The metal and elastomer materials used are specially selected to suit the relevant field of application and, in combination with the conveying area that is designed to optimise flow, keep wear of the small number of wearing parts very low. This means long service lives and maintenance intervals can be achieved, in spite of the abrasive sand and the chemical effects of oil and gas.
Outsize pumps
With the L.Cap pumps, the positive features of the progressing cavity principle have been transferred to a very large design with a correspondingly high performance.
When a leading oil and gas company ordered eight L.Caps at the end of 2015, each with an overall length of 9.8m, not including the drive, and each weighing around nine tonnes, Netzsch decided to build a production hall that is specifically tailored to the requirements of this product line.
The new hall offers optimum conditions for delivering large components and taking finished pumps away, especially with trucks being able to drive right into the building to load and unload.
The building itself is soundproofed and its 34 x 24m of surface area and 14m of height mean it provides enough space for construction of the large aggregates.
The heavy-duty equipment was needed, because a rotor for the pump that was ordered alone measures nearly 6m and tips the scales at 1.25 tonnes.
On top of this, there are three 1.9m long stator parts weighing 1 tonne, a coupling housing weighing 0.85 tonnes and a bearing housing weighing 1 tonne, as well as other components.
The new hall also includes two double-walled vacuum tanks each with 20,000l of water and oil for measuring the NPSH. An additional circulation pump enables media to be cooled or heated in a targeted way to enable simulation of the application conditions.
The values of the pump that are established on the test benches are transferred to a separate area where the customer can simultaneously view them and compare them with the requirements. If the machine fulfils the requirements, it is split into three parts, comprising the motor, the gearbox and the actual pump, and then packed.
Delivery of the first pump to be carried out in this way will be in March 2017. In view of the growing demand for pumps for large volumetric flows in the oil and gas sector, further L.Cap high-performance pumps are soon expected to follow. l
For more information visit www.engineerlive.com/iog
Johann Vetter is head of project management at Netzsch.
