Turbine air cooling is a group of technologies and techniques consisting of cooling the incoming air of a gas turbine. The immediate consequence of turbine inlet air cooling is the augmentation of the power output. It can also improve the energy efficiency of the system. This technology is widely used in hot climates with high environmental temperatures that usually coincide with the peak demand period.
Video Turbine inlet air cooling
Principles
The gas turbine takes the filtered fresh air and compresses it in the compressor stage. Compressed air is mixed with fuel in the combustion chamber and ignited. This generates high-temperature and high-pressure flows from the exhaust gases that enter the turbine and produces a shaft work output commonly used to convert the electric generator and ignite the compressor stage.
Karena turbin gas adalah mesin volume konstan, volume udara yang dimasukkan dalam ruang bakar setelah tahap kompresi ditetapkan untuk kecepatan poros tertentu (rpm). Dengan demikian aliran massa udara secara langsung terkait dengan densitas udara, dan volume yang diperkenalkan.
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The performance of the gas turbine, its efficiency (heat rate) and the resulting power output are highly dependent on climatic conditions, which can degrade the output power rating by up to 40%. To operate turbines under ISO conditions and restore performance, some air conditioning systems have been promoted.
Maps Turbine inlet air cooling
Applied technology
Different technologies are available in the market. Each particular technology has its advantages and discomforts according to different factors such as ambient conditions, investment costs and payback times, increased power output and cooling capacity.
Fogging
The fogging water inlet consists of spraying the finely atomized water (mist) into the inlet airflow from the gas turbine engine. Water droplets evaporate rapidly, which cools the air and increases turbine power output.
Demineralized water is typically pressurized up to 2000 psi (138 bar) then injected into the inlet air duct through a stainless steel mist nozzle array. Demineralized water is used to prevent fouling of the compressor blades that would occur if water with mineral content was evaporated in airflow. The mist system usually produces water sprays, with about 90% of the water stream being in droplets that are 20 microns in diameter or smaller.
Inlet fogging has been used commercially since the late 1980s and is a popular retrofit technology. By 2015, there are over 1000 fogging systems installed around the world. The incoming fog system, "simple, easy to install and operate" and cheaper than other power enforcement systems such as evaporative cooling and cooling.
Inlet fogging is the cheapest gas inlet air conditioning inlet option and has a low operating cost, especially when one accounts for the fact that the fog system only imposes a negligible pressure drop on the inlet airflow when compared to an evaporative media type refrigerant.
Fog nozzle manifolds are usually located in the air intake right downstream of the final air filter but other locations may be desirable depending on the design of the inlet channel and the intended use of the fog system.
On a hot afternoon in desert climates, it is possible to cool as much as 40 Â ° F (22.2 Â ° C), whereas in a humid climate the cooling potential of a hot afternoon can be only 10 Â ° F (5.6 Ã, Â ° C ) or less. However, there are many successful inlet-fogging installations in humid climates such as Thailand, Malaysia and the Gulf States.
Inlet fogging reduces the emission of Nitrogen Oxide (NOx) because additional water vapor extinguishes hot spots in the combustors of gas turbines.
Wet Compression
The fog system can be used to generate more power than can be obtained by evaporative cooling alone. This is done by spraying the fog more than is necessary to fully saturate the incoming air. Droplets of excess fog are brought into the gas turbine compressor where they evaporate and produce inter-effects, which results in a further power boost. This technique was first used in an experimental gas turbine in Norway in 1903. There are many successful systems today.
Some gas turbine manufacturers offer wet and fogging compression systems. The system is also available from third-party manufacturers.
Evaporative cooling
An evaporative cooler is a damp, rigid medium in which water is distributed throughout the header and where air passes through a porous, wet surface. Part of the water is evaporated, absorbing a reasonable heat from the air and increasing its relative humidity. Air dry-bulb temperature decreases but wet-bulb temperature is not affected. Similar to the fogging system, the theoretical limit is the temperature of the wet bulb, but the evaporative coolant performance is usually about 80%. Water consumption is less than fog cooling.
Steam compression chiller
In mechanical compression chiller technology, the coolant is circulated through the cold coil heat exchanger put into the filter housing, downstream from the filtration stage. Downstream from the coil, the droplet catcher is installed to collect moisture and water droplets. Mechanical chillers can improve turbine output and performance better than wet technology due to the fact that inlet air can be cooled under wet ball temperatures, indifferent to weather conditions. Compression chiller equipment has higher electricity consumption than evaporative systems. The initial capital cost is also higher, but the addition and efficiency of the turbine power are maximized, and the additional costs are amortized due to increased output power.
The majority of such systems involve more than one chiller unit and the cooling configuration can have a major effect on the power consumption of the parasitic system. Series counterflow configurations can reduce the compressor work required on each chiller, increasing the overall chiller system by 8%.
Other options such as steam-driven compression are also used in industry.
Steam evaporative chiller
In steam absorption cooling technology, heat energy is used to produce cooling, not mechanical energy. The heat source is usually the vapor remaining from the combined cycle, and is bypassed to drive the cooling system. Compared to mechanical cooling, chillers absorption has a low performance coefficient; however, it should be considered that this chiller typically uses waste heat, which lowers operating costs.
Combination with heat energy storage
The thermal energy storage tank is a natural stratification thermal accumulator that allows storage of cold water generated during off-peak time, to use this energy later during peak times to cool turbine inlet air and increase power output. Thermal energy storage tanks reduce operating costs and refrigeration plant capacity. One advantage is the production of cold water when demand is low, using excess power generation, which usually coincides with the night, when low environmental temperatures and chillers perform better. Another advantage is the reduced capacity and operating costs of a frozen plant when compared to the online cooling system, which results in delays during low demand periods.
Benefits
In areas where there is a demand for cooling, the summers daily heat coincides with the highest atmospheric temperature, which can reduce efficiency and electric gas turbines. With steam mechanical compression technology, cooling can be used during this period so that turbine power performance and output may be less affected by ambient conditions.
Another benefit is the lower cost per kilowatt of additional inlet-cooling compared to the newly installed gas turbine kilowatt. In addition, additional inlet-cooling kilowatts use less fuel than the new turbine kilowatts due to lower heat levels (higher efficiency) than cooled turbines. Other benefits may include increased steam mass flow in combined cycles, reduction of turbine emissions (SOx, NOx, CO2), and an increase in power-to-install volume ratio.
Calculating the benefits of turbine air cooling requires research to determine the payback period, taking into account several aspects such as ambient conditions, water costs, hourly electricity demand, fuel costs.
See also
- Psychrometric
- Load the duration curve
- Thermal energy storage
- Vapor compression cooling
- Request response
- Heat recovery steam generator
- Ingestion refrigeration
- Water injection (machine)
References
External links
- Turbine Inel Cooler Association
- Heat Rate Basics
- On the Peak Request Technique
- ASHRAE American Society on Heating, Cooling, and Air Conditioning Engineers
- International Energy Agent
Source of the article : Wikipedia
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