User:Mattrhames/Gas Turbine Inlet Systems

New article name is Gas Turbine Inlet Systems

Gas Turbines Inlet Systems (GTIS) are a method designed to protect Gas Turbines when they operate in harsh conditions. The primary function of an Inlet System is to increase the density of inlet air, thus increasing the efficiency of gas turbine.

Introduction
When Gas Turbines are operated in severe environments, Gas Turbine Inlet Systems are incorporated to stop outages. Inlet systems vary, depending on the conditions. Besides inlet filters and turbine inlet cooling, there’s a wide range of ancillary equipment that can be incorporated into the system, such as full acoustic packages, high performance weather protection, moisture eliminators, ventilation systems and structural steelwork.

Development
'''Anything we can add about who invented this, when, why, etc. Maybe a link to the inventor’s Wikipedia page? ''' Due to its inherent design and the enormous amount of air consumed (e.g. 1296 lb/s or 587 kg/s for the MS9001F), gas turbines are sensitive to air quality. Filtration is applied to provide protection against the effects of contaminated air that may degrade gas turbine performance and life: erosion, fouling, corrosion, and cooling passage plugging. The need for proper filtration has increased in significance due to the complex designs of the advanced technology 7F and 9F machines.

Inlet filters
These are often elevated to improve air quality entering the gas turbine. If the compartment uses high-efficiency filters, elevation prolongs the filter life. The entering air first encounters a bird screen, then the weather louvres. The access door is just downstream of the weather louvres. Entry is via a caged ladder and service platform. The compartment includes interior lighting and convenience outlets, and a junction box for electrical power. An alarm is provided to indicate that the pressure drop of the inlet filters is excessive. If corrective action is not taken and pressure drop rises further, pressure switches will automatically initiate an orderly shutdown of the gas turbine. The alarm is a signal to stop and service wornout filters.

Turbine inlet cooling
An inlet cooling system is a useful gas turbine option for applications where significant operation occurs in the warm months with low relative humidity. Cooled air which is denser, gives the machine a higher massflow rate and pressure ratio, resulting in an increase in turbine output and efficiency. This will add machine capacity during the period when peaking power periods are usually encountered on electric utility systems.

Full acoustic packages
The inlet system environment is ambient air with low velocity air flow over interior surfaces. Materials of construction are generally low carbon steel, including the inter baffles used over acoustic material to reduce the noise level. In selected marine environments, a corrosion-resistant steel may be used for these interior baffles. Standard protection practice for the inlet system is an inorganic zinc primer paint and/or galvanizing.

High performance weather protection
In cold climates, ingestion of large quantities of snow or freezing rain can cause icing of inlet components which may result in physical damage to the inlet duct or the gas turbine compressor. In warmer climates, prolonged downpours may overload inertial separators, allowing water to be transmitted downstream. If there are high-efficiency filters, this prolonged wetting will increase the pressure drop and weaken the filter media structure. For these reasons, weather protection, such as an inlet hood or weather louvers, are often required.

Moisture eliminators
Potentially corrosive liquids are removed by moisture separators. The number of stages in the moisture separator is a function of the allowable salt ingestion criteria and the expected wind velocities at the site. North Sea sites have statistically higher wind velocities than Gulf of Mexico sites and therefore require three stages instead of one. The moisture separators, particularly the coalescer pads, must be protected from drilling mud and cement, sandblasting material, and, in some locations, duststorms. This will prevent frequent changeout of the coalescers due to plugging from these materials. Prefilters upstream of the separators may be necessary to remove these contaminants.

Ventilation systems
The ventilation pattern chosen for a given design depends on the length of the machine and the temperature distribution in its various components. Gains in product efficiency can be achieved by optimizing the ventilation circuit to minimize pressure drop while maximizing cooling effectiveness. Advances in Computational Fluid Dynamics (CFD) analysis allow detailed evaluation and prediction of the flow in various parts of the ventilation circuit. FLUENT/UNS, a general-purpose computational package for solving a variety of heat transfer and fluid dynamics problems, is used extensively in generator ventilation and cooling analyses. Numerous models are generated, with each one focused upon a given element of the ventilation circuit. Results of an analysis are often applied as boundary conditions for the adjacent model.

Structural steelwork
The most critical components in the rotor are the turbine wheels because of the combined conditions of elevated temperatures and the requirements for strength and toughness. Further, unlike the aircraft gas turbine, these wheels are of very large diameter and section thickness. For this reason, extensive use of steel wheels has been made in heavy-duty gas turbine designs. This has been made possible by the lower compressor pressure ratios (i.e., lower compressor discharge temperatures) and by using long shank buckets, permitting lower temperature operation of the dovetailed periphery of the wheels. With increasing firing temperatures, the incorporation of air cooling of wheels has also extended the application of steel wheels.

Oil and gas
Turbines for the oil and gas industries are often located in remote locations, such as jungles, deserts, offshore platforms and Floating Production Storage and Offloading units. The ingestion of airborne salt, either in wet or dry form, has long been proven to hurt turbine performance and reduce the lifetime of an engine.

Power generation
Combustion turbines for this industry are frequently located in industrial areas, often leaving the turbines vulnerable to high levels of small particulate, such as carbon. These contaminants can significantly impair the performance of a turbine.

Marine
For years, turbines have been used in naval applications as marine propulsion systems, and now, that’s also spread to the fast ferry, cruise ship and LNG (liquefied natural gas) carrier markets. For cruise ships, the gas turbines have also been adopted because of hotel load.