Power Generation Applications
 
Water Wash Tanks

Application

The compressor of a gas turbine ingests a large amount of air containing particulate matter, aerosols of hydrocarbons and other organic compounds and gases. Although the larger particulate matter is filtered out, the other compounds are deposited on the compressor blades. Compressor washing removes this deposited fouling and restores the aerodynamic profile and compressor efficiency. Also used for cleaning generator or other machinery and equipment components, water wash is periodically discharged as waste water.

Challenges

Water wash is collected in a dedicated collection tank monitored for level with typical capacities of 50 to 100 gallons.

Suitable Products

Eclipse® Guided Wave Radar

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Flash Tank

Application

A flash tank serves as a collection system for a variety of condensate drain lines. Flash tanks receive high pressure condensate which is then exposed to a low pressure steam source. When this occurs, a certain percentage of condensate will "flash” to steam at the lower pressure. This steam can be "recycled” on other low pressure steam heat transfer devices. Smaller in size than traditional flash tanks, flash separators utilize cyclonic action to instantly separate steam and condensate.

Challenges

Level measurement is necessary to control flash tank level. The challenges are elevated temperatures and pressures.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Steam Drums

Application

The steam drum is the primary interface between water and steam. In a coal fired plant, boiler feedwater passes through the economizer and into the drum where the steam separates from the feedwater and is drawn off to the superheater. In combined-cycle operations, a Heat Recovery Steam Generator (HRSG) serves the same purpose as a boiler. It is a gas-to-water heat exchanger that extracts energy from the gas turbine exhaust gases and uses it to create steam for the steam generator. HRSG Drums can be high or low pressure varieties.

Challenges

Maintaining constant liquid level in the upper part of the drum is necessary to provide the proper quality of steam. Instrumentation must withstand high temperatures and pressures.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Feedwater Heaters

Application

Feedwater heaters use extraction steam from the turbine to raise the temperature of water destined for the boiler. Water first passes through low-pressure heaters and into the deaerator where excess oxygen is removed. The feedwater then passes into the high-pressure heaters where it is further heated and pressurized. Two separate level control loops should manage each feedwater heater—according to ASME standards.

Challenges

Feedwater heater level is controlled to (1) prevent level from rising into the extraction line; (2) keep the tube surfaces in the condensing zone immersed; and (3) keep the drain cooler flooded. Level instrumentation must withstand moderate to high temperatures and pressures and turbulent conditions.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Deaerator

Application

The deaerator is an open-faced water heater which removes non-condensable gases from the feedwater. In addition to the condenser hotwell, the deaerator's storage tank is the remaining reservoir in the turbine cycle. Positioned below the deaerator and before the boiler feed pumps, the deaerator storage tank serves as a surge tank for the boiler feedwater. Tank level is often controlled by a control valve on the condensate supply line to the deaerator.

Challenges

Pressure fluctuations are extensive in the deaerator storage tank and result in flashing. Level controls must contend with the tank's fluctuating temperatures and pressures.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Condenser Hotwell

Application

Steam enters the condenser where it cools and condenses into water before being sent to the low-pressure feed-waterheater. The condenser hotwell serves as a water reservoir for the turbine cycle. When hotwell level reaches the low point, a valve opens to supply make-up water to the cycle. When hotwell level reaches the high end of the level range, a dump valve opens to move the condensate from the hotwell to a condensate storage tank.

Challenges

Water loss in the turbine cycle due to leakage, steam venting or other usage depletes make-up water. Level control in the hotwell ensures adequate make-up water is supplied to the cycle or diverted to storage.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Ammonia Storage

Application

Vaporized ammonia is used in catalytic and noncatalytic reduction systems for emissions control. Ammonia is injected into the flue gas stream and acts as a reducing agent. It is also used to enhance precipitator efficiency for particulate control. Pure ammonia is stored in a pressure vessel rated for 250 to 300 psig. Aqueous ammonia (70 to 80% water) is stored in a tank rated for 25 to 30 psig. Storage requirements for aqueous ammonia are three to four times that of pure ammonia.

Challenges

Accidental atmospheric release of pure ammonia vapor can be hazardous, so safety and environmental measures may be required which affect the level control selected.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Natural Gas Separator

Application

Natural gas separators remove solid particles and liquids from a continuous gas stream supply. Dust, dirt, sand and pipe scale as well as water, natural gas liquids and light hydrocarbons can be removed. In a typical system, an inlet separator allows particles and liquids to settle out and the gas to rise. The gas collects at the top of the separator where it is removed by means of a gas compressor. The collected particles and liquids are then dumped into a water tank.

Challenges

Liquid level control precisely modulates the amount of water that is drawn off to ensure that the level does not rise too high and enter the compressor inlet.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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