Combustion temperatures have increased at a pace of roughly 20 °C per year to reach 1500 °C since the 1980s when the commercial operation of power generation plants with a combustion temperature of 1100 °C started.
Additional increases run into a variety of technical challenges, such as the need for stronger materials and a reduction in NOx emissions. The period of rapid economic expansion during which a specific increase in electricity demand could be anticipated has also come to an end. It is necessary to develop new items that can adapt to the social and economic climate of today.
Additionally, as environmental concerns throughout the world rise, it is crucial to build more highly efficient power plants in order to reduce CO2 emissions.
Increasing cycle temperature
The efficiency of energy conversion is enhanced when the maximum temperature of a thermal cycle is raised, in accordance with the second law of thermodynamics. The steam turbine recovers power from low-temperature heat energy at 600 °C or less, while the gas turbine uses high-temperature heat energy at 1100 °C. This is a perfect combination. Thermal efficiency in combined cycles can be improved more than in simple cycles by utilizing heat cascades in the combination of two temperature ranges.
In order to raise peak temperatures, industries have created a number of cutting-edge technologies. In one, the steam cycle is used to cool the high-temperature components of a gas turbine. By using this technique to cool the combustor, the gas temperature at a combustor’s outlet (first vane inlet) and the temperature on the downstream side of the outlet can both be raised. Additionally, the first blade’s incoming gas temperature can be raised still higher by chilling steam at the first vane. The mixing of cooling air into the main gas flow can be decreased and the maximum cycle temperature can be raised using conventional materials by utilizing the steam’s large specific heat’s cooling impact.
Gas turbines have been fueled by refinery gas left over and gas from blast furnaces at ironworks in addition to natural gas. The use of extra gas is anticipated to increase in the future. Ironworks require over 40% of the imported coal into Japan, including that needed to make coke. Since coal produces nearly 1.5 times as much CO2 per unit of heat as natural gas does, improving ironworks’ energy efficiency would have a major impact on cutting CO2 exhaust.
The largest 1300°C class blast furnace gas-fired combination plant in the world was placed into commercial operation in July 2004. Industries have also developed blast furnace gas-fired combined plants with combustion temperatures ranging from 1100 to 1250°C. Compared to a traditional boiler firing plant, the CO2 output has decreased by about 25%. According to estimates, the energy used to produce one unit of iron in Chinese ironworks is equivalent to about 150 percent of the energy used in Japanese ironworks.
In 2003, the 300MW M701F VR IGCC was commercialized. Together with an oxygen-blown vacuum residue gasifier, this was used. The facility has successfully accumulated running hours since June 2003. NOx values were less than 25 ppm at base load conditions (16 percent O2) with steady combustion. There have been 16,500 operating hours as of April 2005.
Additionally, construction on a coal gasification combined cycle plant that is now being developed as a national project began last year, and operation is expected to commence in 2007. The need for highly effective power generation from diverse alternative fuels is anticipated to rise in the future. In addition to conventional fuels, there are low-pollution liquid fuels like DME (dimethyl ether) and GTL (gas-to-liquid), which are synthesized from natural fossil fuels, and fuel gases made from waste products like biogas. Future fuel usage of these fuels is anticipated.
Gas turbine Control system
With the assistance of a gas turbine control system, the gas turbines can increase safety and security in performance. GE Turbine control systems parts like IS220PDIOH1A, IS2020LVPSG1A, IS200EDCFG1A, IS420ESWBH3A, and IS230TCATH1A are some examples of control system spare parts.
Peak power generation
Large gas turbines’ unit capacities have increased as a result of rising combustion temperatures. Currently, the maximum unit capacity for the M701G2 turbine is 330 MW, while its maximum unit capacity for single-shaft combined power generation is 500 MW. However, in order for 500 MW turbine power production plants to remain commercially viable over the long run, there must be a substantial demand for such facilities.
Additionally, as air conditioners proliferate, there is a tendency for daytime and nighttime demand discrepancies to widen. As a result, there is a higher demand for gas turbine combination plants, which are crucial for controllable thermal power plants. Future energy needs will call for intermediate capacity, high-efficiency plants with a low utilization factor of roughly 40%.
As a result, combined cycle gas turbines will separate into two types of operating systems: base load systems that prioritize efficiency and intermediate-range machines that prioritize efficiency while minimizing startup expenses and increasing operating flexibility.
Although an increase in combustion temperature results in an increase in overall thermal efficiency, there are many technical challenges that must be overcome in order to use heat energy as effectively as possible at the highest combustion temperature that fossil fuels can achieve, which is between 2000 and 2500°C.
To achieve even greater gains in thermal efficiency, experts have been investigating the possibility of fusing the existing gas turbines with other cycles.
The overall thermal efficiency is increased by combining gas turbines with fuel cells by using the fuel that is still available after the majority has been chemically transformed into electricity in a gas turbine combined cycle.
In this analysis, the two trends relating to intermediate capacity peak power generation and fuel flexibility were cited as near-future trends, while the two trends relating to further rises in gas turbine combustion temperatures and difficulties in developing new cycles were cited as mid- and long-term trends.
It is anticipated that the cost of power-producing facilities will rise as cycles proliferate in number and become more sophisticated. On the other hand, environmental concerns are getting progressively worse, and as fossil fuel resources are depleted, improving thermal efficiency will present a significant challenge.
The development of power production facilities may be sped up and concerns related to rising costs brought on by cycles’ growing complexity could be resolved if a plan for compensating extra costs could be formed through new business prospects like CO2 ECO Right.
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