Frequently Asked Questions
About Turbine Inlet Air Cooling
WHICH ARE THE KEY FACTORS OF A TURBINE INLET AIR COOLING PLANT DESIGN?
- Proper study of the gas turbine filterhouseshall be performed to minimize the Filterhouse modification and introduce the extended surface heat exchangers (ESHX) the most efficient way for indirect cooling.
- Proper simulation of the cooling demandshall be performed to optimize the size of the chillers and thermal energy storage.
- Selection of the heat rejection methodis also important (cooling towers, air cooled devices, seawater or river water cooled systems). The simulation will also be helpful to determine the most feasible solution by comparing the energy and water consumptions all around the year.
- Selection of the state-of-the-art equipment: chillers with highest efficiencies, VFDs for pumps etc.
- Proper control system with robust equipmentto avoid failures and blackouts. Also the control will be very important to make the plant work with correct efficiency and mitigate the low delta-t problems.
WHAT ARE THE MAIN BENEFITS OFFERED BY TIAC TECHNOLOGY?
- Selectable and constant inlet air temperature with ARANER Adaptative Temperature (AAT).
- Fast system delivery compared with new turbine installation.
- Avoid GT output fluctuation produced by ambient conditions.
- Lower price per generated megawatt compared with new GT plant.
- No extra auxiliaries’ equipment needed (same transformer and generator).
- Recognized green technology with carbon credits.
IS THE TIAC SYSTEM ACCEPTED BY THE GAS TURBINES OEMs?
Gas Turbines OEMs accept our system case by case when we work with them, as long as it complies with several requirements such as a limited pressure drop, uniform temperature distribution, and appropriate selection of materials for the GT Filterhouse modification.
In ARANER we have made studies for several OEMs such as MHPS, GE, ANSALDO or SIEMENS among others.
WHEN IS A THERMAL ENERGY STORAGE (TES) SYSTEM BENEFICIAL?
Especially when the turbine inlet air cooling is needed only during some hours a day (peak demand), it is extremely beneficial to implement a TESTIAC configuration, which combines TIAC with a Thermal Energy Storage Tank.
With a TES Tank the net increase in power output is maximized and the cooling plant required is reduced, reducing also the cooling plant cost.
WHY COGENERATION AND TRI-GENERATION ARE BECOMING SO POPULAR?
Cogeneration and tri-generation systems are a successful way of integrating the production of different energy types in a single plant and in the most efficient way.
The advantages of these systems is that the amount of waste energy is reduced to the minimum making the systems to be very efficient and respectful with the environment.
Cogeneration means the production of electricity and heat or cooling energies. Usually a diesel or gas engine is used to produce the electricity. Gas turbines can be used too.
The exhaust heat of the engine/turbine is used to produce heat or sent to an absorption chiller to produce cooling. The system is very efficient because maximizes the use of the primary energy.
The concept of tri-generation is quite similar but with the production of electricity heat and cooling. In case of using a diesel or gas engine, the heat from engine jacket can be also recovered to maximize the system efficiency.
IS TIAC AN ENVIRONMENTALLY FRIENDLY SOLUTION?
TIAC has been demonstrated to be a cost effective environmental energy solution for the power generation industry reducing emissions of pollutants and providing more efficient and sustainable power plants.
TIAC reduction on carbon emission has been well recognized by international institutions. The United Nations Framework Convention on Climate Change (UNFCC) prepared a report which illustrates the reductions in CO2 emissions due to the increase in efficiency and reduction in fuel consumption of the combined cycle in Jebel Ali Power Plant (Dubai).
A total of 65,799 tons of CO2 were reduced during the monitoring period between January 2013 to December 2014 (5.54 % reduction when compared with the emissions without TIAC).
Turbine Inlet Air Cooling (TIAC) is not only the most effective solution for power augmentation in gas turbines, but it also reduces carbon footprint at the same time. TIAC technologies are able to produce the same power output than a new turbine, however with lower installation cost and higher efficiency of fuel utilization.
WHAT ABOUT OF OPERABILITY AND MAINTAINABILITY OF THE TIAC PLANT?
Regarding the operability and maintainability issues for TIAC system, it is very easy. Thanks to our control system the TIAC plant operates automatically.
ARANER’S TIAC control system has a very simple and intuitive HMI. Very few and simple orders are required from the operator. The level of difficulty is very low, and after 1 day training, operators will master the system.
The maintenance is very easy. Main equipment of TIAC system are compressors, pumps and heat exchangers. All equipment to be installed is robust, industrial grade and tested on site to assure their correct performance. From our experience, important damages on TIAC equipment are very rare and they always result from an incorrect maintenance.
The main maintenance operations required are related to the water pumps and the compression units, and these are very basic compared to the general maintenance of the power plant.
Maintenance staff at the power plant is normally used to maintain these kind of equipment. This means that the same operators from the power plant can operate and maintain also our TIAC system.
The basic maintenance activities are limited to a chemical analysis once per year, the cleaning of the water and oil strainers, change of bearings once they have reached their service life and, an overhaul of the main equipment every 5 to 6 years.
All the required maintenance procedure and frequencies are included in ARANER’s TIAC maintenance manual to avoid any trouble during operation.
DO I HAVE TO STOP THE POWER PLANT PRODUCTION TO INSTALL THE TIAC SYSTEM?
The only point of interference between the TIAC plant and the gas turbine is the Filterhouse, where the Extended Surface Heat Exchangers (ESHX) are installed.
The gas turbine filterhouse modification period usually takes around 1-4 weeks depending on site conditions and the filterhouse size, and will be coincident with the gas turbine annual maintenance period, so no additional shutdown is required.
The only specific required action is a good coordination between the GT annual maintenance operation and the filterhouse modification so both of them can be carried out in parallel.
WHAT IS THE REQUIRED WATER QUALITY FOR THE SYSTEM?
It must be clean water, but there is no additional minimum quality requirement because chemicals are injected during the filling of the system at the commissioning phase.
As the chilled water circulates through a closed loop, no continuous make-up water is required. No continuous chemical injection is required either. It is only recommended to perform an analysis of the water quality every year.
Typical frequency of chemical injection would be every 5 years, depending on many factors such as the use of the water or how clean the installation is.
WHAT ARE THE POSSIBLE USES OF THE CONDENSATE RECOVERED FROM THE ARATRAP?
This is practically distilled water and at chilled temperature. From our own experience, it is typically used as make-up water for other processes in the plant, but it could be used also for irrigation or even Air Conditioner units if they are close to the turbine.
The condensate quality will depend on the system’s cleanliness and the quality of the filters inside the filterhouse. As it is an open circuit, this condensate water will take particles of dirt from the pipe with it, also from the filters if not properly cleaned, etc.
For this matter, an in situ analysis must be performed and if the resulting quality is not correct, then the appropriate filtration system should be installed to fit the condensate’s later use.
THE PRESSURE DROP INTRODUCED BY THE EQUIPMENT AFFECTS THE GAS TURBINE PRODUCTION?
Negative. The extended surface heat exchangers (ESHX) are installed after the filters in the gas turbine Filterhouse. The pressure drop of these heat exchangers is very low and limited below a maximum value established by the OEMs themselves to make sure that the gas turbine production is not affected.
Besides, the pressure drop introduced by the TIAC system is far less than the pressure drop related to dirty filters that are not correctly maintained.
CAN THE AUXILIARIES OF THE GAS TURBINE SUPPORT THE TURBINE’S POWER AUGMENTATION?
Since the power output of the gas turbine increases when the TIAC system is installed, the capacity of the gas turbine auxiliaries, such as the generator and the power transformer, shall meet this increase of power as well.
Gas turbine generators and power transformers are usually oversized so that they never limit the gas turbine production in any ambient conditions.
However sometimes the capacity of these equipment cannot meet the power increase of the turbine, and therefore they need cooling as well. In this situation, the same TIAC system can refrigerate them also in order to meet the increase of capacity.
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