Upstream gas turbine
An upstream gas turbine ( VGT for short ) is a gas turbine that is connected upstream of another process (usually a steam power plant ), although the main focus in terms of output is on the downstream process and the VGT only has a supporting effect. This differs from gas turbines in conventional combined cycle power plants , where the GT contributes the main part (about two thirds) of the total output.
Conventional power plant units that are equipped with a VGT are often referred to as a combination unit.
In a steam power plant, the VGT can be used on the gas or air side as well as on the water or steam side:
- With the upstream connection on the air side, the exhaust gas from the gas turbine is used as an oxygen carrier for combustion in the main furnace. This is possible because gas turbines, due to the Joule process , run high air ratios and therefore have a relatively high residual oxygen content in the exhaust gas. The principle is the same as with a waste heat boiler with additional combustion , with the difference that the additional combustion is the main combustion here.
- With the upstream connection on the water side, the VGT has its own waste heat boiler separate from the main boiler, which is only used to preheat the condensate and feed water.
In both cases, the efficiency of the overall system increases compared to a pure steam power plant - for the same reasons as with a combined cycle power plant, but in a weaker form. In addition, the power plant becomes more flexible, can run faster load gradients and is therefore suitable for use in medium or even peak loads . The upstream connection of a GT is therefore also a retrofit option for older power plants with lower efficiency and slow firing. Another advantage of the VGT circuit is that power plants with fuels that are not suitable for gas turbines (solid fuels, especially coal) can be upgraded to combined power plants with improved efficiency.
Executed systems
The following systems, among others, are equipped with a VGT:
- Emsland natural gas power plant , Lingen (air side)
- Gersteinwerk coal-fired power station , Werne (air side)
- Weisweiler power plant , Block G and H (water side)
- Altbach / Deizisau power plant
- Mainz-Wiesbaden power plants, power plant 2
- Simmering power plant , Vienna (air side)
- Landesbergen power plant , block 4 (air side)
Individual evidence
- ↑ a b WINGAS: What is what ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ Aachener Zeitung: Gas system at the Weisweiler power plant goes back online , press release from November 28, 2017 on az-web.de.
