Siemens Researching Clean Combustion Processes for Hydrogen Gas Turbines
19 March 2010
Siemens Corporate Technology (CT) is conducting research into clean combustion processes for future hydrogen-fired gas turbines for electricity generation. The Siemens researchers are working with the Russian National Research Nuclear University (MePhl) to identify combustion processes that produce the lowest possible amounts of nitrogen oxides.
They are also attempting to use new methods to keep the flame, which compared to natural gas flames is extremely hot, as small as possible to protect the turbine blading against the temperatures.
Combusting hydrogen with oxygen to obtain water and extract a large amount of energy with zero environmental pollution is still a long way off, Siemens notes. The production of pure oxygen is too costly and the combustion temperatures of 3,200 degrees Celsius are too high for the turbine blading used in the power plants. Natural gas, which burns at approximately 1,950 degrees Celsius, already requires air cooling of the blading. Siemens CT in Munich is therefore also conducting research into heat-resistant ceramics for use in turbines.
The first generation of future hydrogen-fired gas turbines will therefore combust the gas with air. Just as in conventional gas-fired power plants, however, this process produces nitrogen oxides. Emissions rise with the temperature, but so does the efficiency of the combustion process.
The researchers are now simulating combustion processes to identify burner concepts that generate the lowest possible emissions at the highest possible combustion temperatures. One important lever is the flame, which propagates extremely quickly in hydrogen. The smaller and more stable the researchers can keep the flame, the fewer the nitrogen oxides that are produced.
Trials with a recently developed swirl burner have already shown significantly reduced emissions. A patent has since been granted for another method that uses the enhanced mixing of air and hydrogen to reduce the size of the flame. This reduces emissions while at the same time keeping the hot flame as far away as possible from the combustion chamber and the turbine blading.
I've been researching closed cycle combustion in submarines. According to some people I talked to they said it was easier cleaning up after a nuclear submarine than one running closed cycle combustion. But if you injected hydrogen and oxygen and used nitrogen or argon as a working medium who cares if it makes a ton of NOx as long as you keep it in a closed system like a refrigerator. So your only emissions would be water and power. If you used chemical vapor deposition you could make diamonds from carbon fuels. Use biofuels to strip CO2 from the air then capture it in a diamond. You could make wheels out of diamonds. The only problem would be global colding from the CO2 reduction.
What is the optimum CO2 level?
How much work can you get from a gallon of fuel?
Can you get more than its total amount of heat?
Let's say a diesel is 40% thermal efficient. What percent is from thermal and what percent is from chemical boom energy. Carnot's engine only factored in heat right?
Posted by: jason.thompson | 19 March 2010 at 09:11 AM
burning the H2 with an air/water aerosol would have two effects : it would lower the burning temperature (lowering NOX and protecting the blades) and dramatically increase the pressure (because the liquid water becomes a gas at 1800°C). The loss in heat due to evaporation of the water is relatively small and can mostly be recovered if the exhaust gasses are used in counter-current to heat the water for the second turbine (a classical steam turbine).
This principle would also allow for combustion in pure O2 (and water), which only gives pure CO2 and H2O as exhaust, making CCS much easier.
Posted by: Alain | 19 March 2010 at 09:22 AM
Aircraft engine manufacturers have already reduced, and are reducing further, NOX from normal turbine engines by better fuel atomization to provide shorter (hot) residence time plus other measures.
Posted by: ToppaTom | 19 March 2010 at 12:12 PM