Steam Flow Control

Aug. 30, 2011

Actuator: An actuator is a mechanical device for moving or controlling a mechanism or system. On a steam line actuators are needed to operate control valves. The actuator accurately locates

Actuator: An actuator is a mechanical device for moving or controlling a mechanism or system. On a steam line actuators are needed to operate control valves. The actuator accurately locates the valve plug in a position dictated by the control signal, and is used to move the valve to a fully-open or fully-closed position, or a more open or a more closed position (depending on whether ‘on / off’ or ‘continuous’ control action is used).

Boiler: An apparatus that generates heat (usually by burning fuel) and uses it to heat circulating water (or sometimes another liquid) in a closed system that is then used for heating, creating steam, other or industrial processes.

Condenser: A condenser is a water-cooled shell and tube heat exchanger installed on the exhaust steam system, which converts steam from its gaseous form to a liquid state at a pressure below atmospheric pressure.

Dryer: Steam used to create heat can be channeled through heat exchange coils for the purpose of drying. Industries, which use dryers, may include timber mills, dried fruit and food manufacturers, tobacco producers, etc.

Efficiency: The efficiency of steam and the heat exchanger are critical, as they will affect the annual fuel bill, and the product output volume from the steam system. Regular maintenance and careful design considerations are key to ensuring an efficient steam plant.

Flashing: Also known as flash steam, flashing is the spontaneous conversion of water into steam that can occur in the condensate recovery system. Flash steam can be harnessed and re-introduced to conserve energy.

Fouling: Fouling is when a fluid goes through the heat exchanger, and the impurities in the fluid precipitate onto the surface of the tubes, which can cause scale. This precipitation reduces the surface area for heat to be transferred and causes an increase in the resistance to heat transfer across the heat exchanger. Fouling can be prevented with proper water purification.

Heat Exchanger: Essentially, any device that transfers heat from one medium to another. For industrial processes, the type and size of heat exchanger can be customized to suit a process depending on the type of fluid, its phase, temperature, density, viscosity, pressures, chemical composition and various other thermodynamic properties.

Indirect Heating: Indirect heating typically involves a heat exchanger, in which steam passes across the surface area of the heat exchanger, and the heat is transferred to the substance being heated. The steam never comes into direct contact with the product being heated, and usually some Condensation occurs during the Heat Transfer.

Steam Injection: Steam injection is when a series of steam bubbles is pumped into a cooler liquid. The steam bubbles condense and give up their heat to the surrounding liquid.

Steam Trap: Steam traps are used to discharge condensate and non-condensable gases with a negligible loss of live steam from the pipeline. If condensate is not rapidly removed from the system, it has the potential to cool down the working steam and form more condensate, hence loss of energy.

Steaming: The rate, usually expressed in Lbs/Hr or KG/Hr, at which a boiler produces steam.

Strainer: A pipe strainer is a filter device used to mechanically remove solids from steam and fluids, by means of a perforated or wire mesh straining element. A steam strainer is a cost-effective way of protecting downstream equipment such as heat exchangers, pumps, compressors, meters, spray nozzles, turbines, steam traps, etc. from possible damages due to debris such as rust, pipe scale, sediment, and/or other solids.

Thermal Efficiency: In thermodynamics, the thermal efficiency (Nth) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a boiler, a furnace, or a refrigerator.

Thermodynamics: Thermodynamics is the study of energy conversion between heat and mechanical work, and includes various key interacting principles such as temperature, volume and pressure.

Vent Valve: Installed at the opposite end of the supply valve, float and thermostatic vent valves let air escape from the heating unit under pressure, but close against the passage of steam and condensate.

The terms and definitions for this issue’s Word Search were contributed by Wade Industrial, a South Africa-based firm specializing in industrial steam, boiler, condensate recovery, and water reticulation systems.

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