Siemens Energy SGT-700 Industrial Gas Turbine

Overview

The Siemens Energy SGT-700 is an industrial gas turbine derived from the proven SGT-600 and developed for higher output, higher efficiency and lower emissions, with wide fuel capability for power generation and mechanical drive. It is offered in 33 MW and 35 MW ratings; at the 35 MW rating the Siemens Energy SGT-700 technical data poster gives a gross efficiency of 38.0 %, a heat rate of 9 466 kJ/kWh, a turbine speed of 6 500 rpm and an exhaust temperature of 531 °C. Like its predecessor, the turbine is stated to be capable of burning up to 75 % hydrogen by volume in natural gas. Siemens Energy reports more than 142 units sold with over 5.8 million operating hours, and a fleet leader beyond 162 000 hours.

Seven Star LLC supplies Siemens Energy SGT-700 related auxiliary equipment, instrumentation, monitoring hardware and spare parts to oil and gas operators, power producers and process industries in the Sultanate of Oman and the GCC, with engineering support in Muscat. Our role is to help maintenance and project teams source the items they specify quickly and with the correct part numbers.

Operating Principle of the Siemens Energy SGT-700

The Siemens Energy SGT-700 is a compact twin-shaft engine. Its gas generator uses an 11-stage axial-flow transonic compressor incorporating current aerodynamics and variable guide vanes, which maintain stable operation and good part-load efficiency over a wide range of ambient and load conditions. Hot gas leaving the gas generator expands through a two-stage uncooled free power turbine with a nominal shaft speed of up to 6 500 rpm. For mechanical drive the power turbine may run at 50 to 105 % of nominal speed, and it can be matched for optimal performance at different ambient conditions, which matters in hot climates where air density falls during the summer months.

As general engineering background, efficiency in a simple cycle gas turbine rises with pressure ratio and turbine inlet temperature. The step from the 14.0:1 pressure ratio of the SGT-600 to 20.4:1 on the 35 MW rating of this model is one of the main reasons for its higher efficiency, while a high exhaust temperature still leaves substantial heat for recovery steam generators in cogeneration and combined cycle plants.

Engineering Design of the Siemens Energy SGT-700

Combustion uses a third-generation dual-fuel DLE system with the same burners for gas and liquid fuel and on-load changeover in both directions. Siemens Energy states low NOx capability of 15 ppmvd or less on gas at both ratings, low emissions on liquid fuel without water injection and a required site gas supply pressure of 28 bar(a). The fuel range covers gases with high inert, hydrogen and heavy hydrocarbon content, as well as Diesel No. 2 liquid fuel.

Power generation and mechanical drive packages share the same driver and feature a modular design with single-lift capability. The manufacturer gives an approximate weight of 169 755 kg and dimensions of 18.8 by 4.6 by 4.0 m for the 35 MW power generation package, and 63 050 kg with 11.7 by 4.0 by 4.0 m for the mechanical drive package. Maintenance can be carried out on site or by removing the gas generator for off-site overhaul, with 30 000 equivalent operating hours between hot section inspections, burners accessible from outside, horizontally split compressor casing and borescope ports, supported by remote diagnostic services.

Key Features of the Siemens Energy SGT-700

Highlights published by the manufacturer for the Siemens Energy SGT-700 are:

• Evolution of the SGT-600 designed for higher power output, efficiency and lower emissions.
• 35 MW rating with 38.0 % gross efficiency in simple cycle power generation, and a 33 MW rating.
• Mechanical drive output of 36.2 MW at the 35 MW rating, with drive shaft speeds from 3 250 to 6 825 rpm.
• 11-stage transonic compressor with variable guide vanes and two-stage uncooled free power turbine.
• Dual-fuel DLE combustion with NOx capability of 15 ppmvd or less on gas.
• Hydrogen capability of up to 75 vol% in natural gas according to the data poster.
• 30 000 equivalent operating hours between hot section inspections.
• Single-lift modular packages suited to desert, arctic and harsh industrial environments.

Industrial Applications

Siemens Energy recommends the Siemens Energy SGT-700 for industrial power generation, oil and gas power generation and mechanical drive, and its high exhaust heat makes it a strong option for cogeneration and combined cycle plants. For a 2×1 combined cycle configuration the manufacturer quotes 91.6 MW(e) at 53.1 % net plant efficiency. In the Omani context, typical opportunities include large gas compression and reinjection trains, field power plants with heat recovery, refinery and petrochemical cogeneration in Sohar and Duqm, and pipeline compression across the GCC.

As general engineering background for Gulf installations, gas turbine output and efficiency fall as ambient temperature rises, because warmer air is less dense and the compressor moves less mass. Operators of a Siemens Energy SGT-700 in Oman therefore pay close attention to inlet air filtration against sand and dust, inlet cooling options, compressor washing routines and the condition of instrumentation that protects the machine. Planning these auxiliaries and their spares together with the turbine maintenance programme helps a Siemens Energy SGT-700 keep its rated performance through the hottest months of the year.

Seven Star LLC supports operators of this class of machine with vibration and protection systems such as the Bently Nevada 3500/42M Proximitor seismic monitor, and also assists sites running the larger SGT-800 industrial gas turbine or the smaller SGT-300 industrial gas turbine. Part numbers and nameplate data are the quickest route to a confirmed offer.

Technical Specifications

Performance values below are for the 35 MW rating at ISO conditions on natural gas, as published by the manufacturer:

How to Order

For Siemens Energy SGT-700 spares, auxiliaries or instrumentation, send Seven Star LLC the package serial number and the list of part numbers or item descriptions you need. Our Muscat team will confirm availability, prepare a formal quotation and arrange delivery anywhere in Oman or the GCC. The manufacturer technical data poster can be downloaded from this page.