Siemens new gas turbines use jet plane engine technology to reduce life-cycle operating costs

The Power Generation Group of Siemens is developing an efficient 165-MW-class V84.3A heavy-duty combustion turbine that combines Siemens design experience with the aeroengine technology of Pratt & Whitney. Siemens plans to introduce a family of these advanced machines over the next few months.

The basic design was adopted from the features of previous Siemens turbines, with standard features including a disk-type rotor, dry low NOx hybrid burner, two outboard bearings, cold-end generator drive and axial exhaust.

“The V84.3A is not a paper machine,” said John C. Bobrowich, Siemens` fossil division vice president. “It has successfully completed first-phase testing and is currently undergoing extensive second-phase testing at our factory in Berlin. Built with proven technology, the new machine will provide our customers with efficient, cost-effective power generation without the potential reliability, availability and maintenance risks associated with untested design concepts.”

Siemens took advantage of a long-standing technology exchange agreement with Pratt & Whitney to incorporate aerodynamic blading designs, materials and cooling techniques into the turbine section of the new machine. A superior compressor design derived from the PW4000 aircraft engine was also added.

Another new feature is the “Hybrid-Burner-Ring” (HBR) combustor, which Siemens calls a “natural evolution” from the multi-hybrid burner it introduced in 1986. For the HBR, a more compact combustion system was developed by eliminating the two large cylindrical combustion chambers of the V84.3 and by doubling the number of burners from 12 to 24 while making them smaller.

These adjustments significantly in-creased the fuel efficiency of the turbine, allowing it to operate at a slightly higher firing temperature than previous models without needing an external blade-cooling air system. These improvements are credited for the machines 38 percent simple- cycle efficiency, along with a 10 percent increase in output.

The higher firing temperature coincides with hotter exhaust, which can be ducted directly into a heat recovery steam generator. These improvements can combine to boost a plant`s overall efficiency to 58 percent in combined-cycle operation.

The HBR also uses a premix burner for natural gas and No. 2 fuel oil, allowing the V84.3A to achieve low dry NOx and CO emissions on either natural gas or distillate oil.

Siemens will soon introduce its V94.3A turbine for 50-hz applications and the V64.3A for 50-hz or 60-hz use. The V84.3A turbines will be built in Siemens` Milwaukee, Wis., USA, manufacturing headquarters, with the first unit scheduled for shipment in the second half of 1996.