The rapidly changing world of marine engine propulsion is reflected in KBB’s turbocharger product range
As a turbocharger manufacturer of more than 60 years’ standing, Kompressorenbau Bannewitz (KBB) recognises that the maritime engine world is at what it calls “a technological crossroads”, with many options on the market for owners. According tio the company: “The question lingers of what technology will be the winner: two stage turbocharging, SCR or EGR?
The company’s product range is designed to reflect this and to offer options for those seeking answers to this question. Reflecting the requirements of new generation engines KBB now offers an upgrade of the well-accepted single-stage turbocharger series ST27 for pressure ratios up to 6 (new name: ST27-EP).
KBB has also developed the two-stage turbocharger system K2B, which can currently achieve charging pressures of up to 10 bar. Furthermore, KBB is dealing with high pressure EGR solutions for single- and two-stage turbocharged engines and with new concepts of turbocharger operation monitoring.
The ST series has a high efficiency and pressure ratio. It also features inboard journal bearings and is lubricated by the engine oil system. The oil is supplied through the turbo support. The ST series also allows for speed measurements and is interchangeable with the HPR-generation and can be installed on engines up to 4.8MW. With extended area in the top efficiency, reductions in emissions can be achieved (to support IMO II requirements).
The ST series is a simple and compact design, which offers customers long intervals between overhauls and a long lifetime of components.
KBB’s most recent two-stage turbocharging system is the K2B ‘knowledge to boost’. The K2B can be used on different L- and V-engines (diesel, HFO, gas). The two-stage turbocharging with K2B can be applied to engines with outputs between 0.5 and 5MW and has an overall compressor pressure ratio of up to 10:1. Since its launch in 2014, the K2B system has been installed on several diesel and gas engines and has now passed a significant operation time to evaluate the system. In fact, 2014 saw the first series application of the K2B two-stage turbocharger on a Yanmar 6-cylinder main propulsion MDO/HFO engine with a significant reduction of fuel.
At SMM 2016 in Hamburg, the company exhibited a scale model of the K2B system. The model consists of the HPA7000 and one HSR6; the HSR6 is a high-pressure turbocharger (2nd stage) with the HPA7000, the larger of the two units, is a low-pressure turbocharger (1st stage). The K2B range is the eighth generation of turbochargers produced by KBB.There is also a demand for effective EGR solutions in the field of diesel engines with an output range between around 0.5 MW and 1.5MW. The combination of one-stage turbocharging and HP-EGR in particular offers an alternative to exhaust-gas after-treatment in locomotive and marine applications. KBB has therefore developed an EGR turbocharger that goes by the name ERT20 especially for these applications.
The ERT20 is based on an oil-cooled exhaust-gas turbocharger with a radial turbine as used in commercial vehicles. Due to the much severer operating conditions in EGR operation, only the turbocharger shaft, the shaft bearing and individual screwed connection elements of the original series-produced turbocharger were used in the new product. All other ERT20 components were newly developed or modified. New features of the turbocharger include speed measurement and a modified oil supply.
The demands on the design of the ERT20 compressor and turbine are much higher for operation on a single-stage turbocharged engine than they would be for two-stage turbocharged engine operation. There is a significant mismatch between the compressor and turbine relative to a typical turbocharger. The pressure drop across the EGR-TC turbine is much higher than the pressure difference that has to be bridged by the compressor in part-load and full-load operation.
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