INDUSTRY APPLICATIONS SERIES Level Instrumentation for Power Generating Plants

Level Controls in a Coal-Fueled Plant 9 POST COMBUSTION SYSTEM STEAM GENERATING SYSTEM 10 POLLUTION CONTROL SYSTEM STEAM BOILER SO2 REMOVAL COMBUSTION FUEL SYSTEM COAL SILO IGNITION FUEL STORAGE LEVEL APPLICATION LEVEL APPLICATION CONDENSATE DRIP LEGS . . . .11 BOILER BLOWDOWN TANK . . .12

POWER CONVERSION SYSTEM COOLING TOWER WATER TREATMENT CIRCULATING WATER SYSTEM LEVEL APPLICATION LEVEL APPLICATION WATER WASH TANK . . . . . . . . .17 Please Note: The level instruments recommended in this guide are based on field experience with similar applications and are included as a general guide to level control selection. Because all applications differ, customers should determine suitability for their own purposes.

Level Controls in a Combined-Cycle Plant POST COMBUSTION SYSTEM COMBUSTION FUEL SYSTEM 9 2 POLLUTION CONTROL SYSTEM FUEL HRSG HEAT RECOVERY STEAM GENERATOR GAS  TURBINE STEAM  TURBINE STEAM GENERATING SYSTEM LEVEL APPLICATION LEVEL APPLICATION CONDENSATE DRIP LEGS . . . .11

POWER CONVERSION SYSTEM COOLING TOWER WATER TREATMENT CIRCULATING WATER SYSTEM LEVEL APPLICATION LEVEL APPLICATION WATER WASH TANK . . . . . . . . .17 Please Note: The level instruments recommended in this guide are based on field experience with similar applications and are included as a general guide to level control selection. Because all applications differ, customers should determine suitability for their own purposes.

Level Controls for Power Generation since 1932. ne hundred years ago, electric power become more and more dynamic to reflect the cost was over 20 cents a kilowatt-hour— of providing electrical service. Deregulation will also more than twenty times today’s cost. provide new impetus for improvements in power Back then electricity was used primarily generation and allied technologies. The cost of electric power was well beyond the Radar in 1998, Magnetrol® has brought leading- means of most families, and even rudimentary edge level control to the power industry at reduced appliances were absent...

COAL YARD STORAGE PLANT AREA: Combustion Fuel Application: Raw coal is delivered to a coal yard in aggregate pieces of approximately 6" that are later reduced in size by a crusher to approximately 1.5". Enclosed storage of crushed coal is common in frigid climates and where containment of coal dust is controlled to protect populated areas. Hoppers and silos store active and reserve crushed coal prior to its pulverization into the powdered form suitable for boiler combustion. Challenges: Some severe power plant accidents in years past have been traced to coal dust ignition, and the atmospheres...

PLANT AREA: Combustion Fuel Application: Fuel-fed ignitors initiate the boiler flame in coal-fed plants using natural gas or atomized fuel oils such as light grade #2 or heavy grade #6. Natural gas and propane can also be used. In combined-cycle plants, gas turbines often use natural gas and liquid fuel oils as ignition fuel. Large gas turbines are designed to operate alternately or simultaneously with both gas and liquid fuels. In dual-fuel plants, a False Start Tank will temporarily hold diesel fuel after an unsuccessful attempt to fire the turbine. Challenges: Crude oils with lower flash points...

CONDENSER HOTWELL PLANT AREA: Steam Generation Application: Steam enters the condenser where it cools and condenses into water before being sent to the low-pressure feed-water heater. 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...

PLANT AREA: Steam Generation 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....

FEEDWATER HEATERS PLANT AREA: Steam Generation 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...

BOILER BLOWDOWN TANK PLANT AREA: Steam Generation Application: The concentration of undesirable solids in boiler water can be reduced through the use of a continuous purge or blowdown system. A blowdown tank receives continuous blowdown from the steam drum and blowdowns of variable temperatures and pressures from the steam generator. A blowdown tank can also function as a gravity feed drain for the steam generator when the generator is drained for maintenance. Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter with 7YS Steam Probe or E3 MODULEVEL Displacer-Actuated Transmitter...

DEMINERALIZATION TANKS PLANT AREA: Circulating Water Application: Because modern high-pressure boilers evaporate several million pounds of water every working hour, the purity of feedwater circulating inside the boiler is essential. Chemical treatment reduces scale-forming materials and corrosive oxygen content. A Feedwater Evaporator can be used as an alternative method to chemicals by removing impurities through evaporating raw water with extraction steam. Most often, the purity of feedwater is achieved by chemical treatment. Challenges: Because support chemicals for water treatment can include...