| Gas turbine combined cycle, as an advanced power generation technology, is one of the main power generation methods in the world nowadays. There are already a number of gas turbine combined cycle power plants putted into operation in China, including 25 power plant projects and 59 gas turbine units. Although the gas turbine combined cycle power generation technology has promising prospect, but the situations of power generation of quite a number of natural gas fired combined cycle power plants become less optimistic than the present situation in China as the fuel supply becomes a major factor affecting the natural gas power generation.China is rich in coal and lean in gas. In a rather long period, coal will hold a firm position in China's consumption primary energy. China consumed 2.58 billion tons of standard coal in 2007. Coal has secured energy supply to China's economy development, but the environment pollution caused by direct coal combustion is not negligible. Sulfer oxides, nitrogen oxides, heavy metals, solid particles and other pollutants are generated from coal combustion, as well as green-house gas like carbon dioxide etc. By increasing the proportion of clean gasification process in the usage of coal, China's advantage in coal resource can be further and effectively utilized while mitigating the impact on environment.All of those provide a feasibility and necessity in developing the integrated gasification combined cycle (IGCC) power generation technology. The commitments our country has taken in carbon dioxide emission reduction and relevant policies and constraints will determine the generation model of our country in the future, but also is the most important factors that will decide the future IGCC development of our country. In an integrated gasification combined cycle (IGCC) process, coal is first converted into syngas of medium or low heat value, followed power generation through the use of gas turbine and steam turbine, realizing the indirect use of coal as fuel in the combined cycle. Not only IGCC enjoys higher thermal efficiency, but also the syngas stream is much smaller in volume than the flue-gas in common process and therefore easy for cleaning treatment. That is to say, zero effluent of sulfur and nitrogen is possible by IGCC. On the other hand, carbon dioxide can be captured and sequestered to show even better environment performance.Currently there are more than 36 IGCC power stations in operation or under construction in the world, with total capacity of 11000MW, 4050MW IGCC power stations has already been putted into business operation. These IGCC power stations are located in United States, Spain, Netherlands, Italy, Japan and India etc. China has also positively developed IGCC technology, the near zero emission coal based power demonstration project established by Huaneng GreenGen will be putted into operation in 2010.Gas turbine is a core device in the IGCC technology power generation, because of the diversity of IGCC systems and gasification technology, and the design of a gas turbine is a complicated and massive project, so it is impossible for each of the specific circumstances of IGCC power plant re-design a gas turbine to fueled with the syngas of medium and low heat value produced by coal gasification. The current approach used is to make an appropriate retrofit on the original design of gas turbines fueled with natural gas to meet the requirements of gas turbine using the syngasThis paper mainly investigates the off-design characteristics when gas turbine burned syngas. For each specific fuel, because of different heat value and nature, the retrofit requirements of the gas turbines are not the same accordingly. Aimed on the research content of the paper and specificity of gas turbines in IGCC, the main research work done in the paper was listed as following:1. Paper selected the PG9351FA gas turbine as research object and collated a large number of different operating conditions of powerplant data to calculate operating condition characteristics of gas turbine compressor. The paper analyzed the applicability and thermal economy of PG9351FA unit under the different heat value conditions.2. In this paper, I have compiled the program to calculate the combustor generation under different element and different component of the fuel.3. Mathmatic modeling on compressor,combustor and turbine have been done and all of this consisted gas turbine simple cycle.4. Based on the cauculation of different heat value syngas fired gas turbine we can know that: when the lower heat value (LHV) of the syngas upper than 10476kJ/kg, the compressor inlet guilde vane adjust are needed; Once the LHV of syngas lower than 4240kJ/kg, we have a bypass air bleed besides compressor inlet guilde vane adjust to meet the flow passage ability of turbine and safe operation of the units. All of this provided useful reference data for a conventional combined cycle units retrofit into IGCC power plants. |
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