Gas turbines: what they are and how they work

Capstone Green Energy, a Californian company world leader in the production of cogeneration energy systems with micro gas turbines, of which IBT Group is the exclusive distributor for the Italian market, has more than 100 registered patents and 9,000 installations in over 80 countries, of which more than 250 installed by IBT Group. In this article, we will focus on the analysis of gas turbines: from their structure to their operation, passing through the possible applications, here is all you need to know about them!

Gas turbines

Capstone’s gas turbines convert combustion energy into electrical energy through the generator and recover thermal energy from the exhaust fumes. This is possible thanks to oil-free technology, of aeronautical origin, which has many advantages: from the modulation of the electrical load from 0 to 100% to the reduced emission of pollutants into the atmosphere (NOx < 18mg/Nmc and CO < 50 mg/Nmc, the lowest available today), from low vibration and noise emissions to low maintenance costs, with a guarantee of 8,600 continuous hours/year. This type of system is particularly suitable for facilities that need to modulate their electrical power according to seasonal or daily peaks in consumption and, for this reason, is widely used, for example, in the hotel, hospital, paper, food&beverage and textile sectors.

What type of engine is a gas turbine?

The gas turbine is the result of experience gained in the aeronautical industry by the founders of Capstone Green Energy, and not surprisingly is reminiscent of the one used in a turbojet engine. Inside, the Capstone turbine has only one moving part (the shaft on which the turbine and compressor are mounted), which rests on air bearings that support the rotating turbine shaft without mechanical contact. The absence of cooling liquids, vibrations and lubricating oil also means that there is no need to dispose of used oil, and represents a drastic reduction in both maintenance costs and downtime. In addition, friction moments, which only occur during machine start-up and shutdown, are “stress-free” as they are cushioned by a specially designed support structure that ensures durability and functionality of the mechanical parts.

The operation of gas turbines

The Capstone turbine module is a single-stage type characterised by an air compression section splined to the turbine shaft and a generator with a permanent magnet rotor. As far as its operation is concerned, during the start-up phase the turbine is made to rotate by the electric generator working as an engine until the system reaches self-sustaining speed. At this point, the mixture of fuel and air required to operate the turbine itself is sent into the combustion chamber; in doing so, the turbine will increase its speed of rotation until it reaches its rated power. In addition, the recuperator makes it possible to increase the temperature of the air entering the combustion chamber, thereby increasing the efficiency of the turbine module. The Capstone turbine is the world’s most advanced oil-free turbogenerator for high-efficiency self-generation of electrical and thermal energy, and is available in six modular sizes (from 30KWE to 1MWE) that can run on both fossil and renewable fuels.