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Steam generator (boiler)

Inspection of Steam Generator (New)
Steam Generators (boilers) have the potential to injure personnel or cause large amount of damage to property. Boiler Inspections are required by law to ensure proper safety mechanisms are functioning to specific standards. A few safety mechanisms inspectors check are the nameplate, relief or safety valve, control safety devices, expansion tanks, and visual inspections.

Nameplate
Inspectors inspect the nameplate to ultimately determine what safety mechanisms that specific boiler contains. The nameplate also states what year the boiler was made, who certified the boiler, type of boiler, max operating temperature, max operating pressure, input firing rate, output firing rate, and blow off pressure of the relief or safety valve.

Relief or Safety Valve
The relief or safety valves function ability is important due to the possible chance of overheating or pressurizing a boiler. Overheating or over pressurizing a boiler can cause a boiler to explode.(Boiler, 2017)

Control Safety Devices
Another safety mechanisms of boilers is the control safety devices. One control safety device is the low water cut off switch. This device detects the amount of water in the boiler. A low amount of water flowing to a boiler could potentially cause a boiler to overheat ultimately damaging the boiler. The safety mechanism used to control firing rate of boiler is called the operating switch. This operating switch also has the ability to turn the boiler on and off. This switch is inspected to ensure proper functioning ability. Pressure control devices include the operating switch and the high temperature limit switch. These prevent over pressurizing of the boiler by controlling firing rate and providing an automatic shut off if temperature reaches beyond safe operating conditions. Expansion tanks are used in boilers to allow the expansion and contraction of water to travel somewhere.

Components of Boilers (New)
The components of boilers are necessary for the safe and efficient functioning of a boiler. A few of those components include a burner, superheater, economizer, and a deaerator.(What The Inspector Looks, 2017)

Burner
A burner mixes fuel and air to a specific ratio and sends it into the boiler. Many different fuels are used in boilers. A few include diesel, coal, oil, wood chips, natural gas, and others. Burners control the efficiency of which the fuel and air and burning along with the control of the flame produced.

Superheaters
Superheaters heat saturated steam to a temperature above saturation point to ensure dry steam is being produced. Superheaters are necessary for when steam is being discharged to a turbine. Moisture in steam can damage the turbine blades, therefore superheated steam (very dry steam) is necessary.

Economizers
Economizers improve the overall efficiency of a boiler. Economizers use the exhaust gas from the boiler to transfer heat to a heat exchanger containing water. This water can then be heated and turned into steam to run another turbine. Economizers can also use a heat exchanger to heat the feed water for a boiler. Deaerators purpose is to remove non-condensable gases out of the feed water for boilers. These gases cause corrosion in which can affect the safety of the boiler. The deaerator uses trays in which feed water runs off. Steam is used to lift the non-condensable gases out of the water. Therefore allowing the feed water to be free of non-condensable gases.

Different Steam Traps on Boilers
A few different types of traps include thermostatic, mechanical. Traps are designed to capture a desired substance and allow another substance to transfer into its desired location. During operation of a boiler, a trap would be used to capture condensate and allow steam to flow free of any unwanted condensate.

Thermostatic Traps
Thermostatic traps capture condensate from steam by opening the valve only when the condensate has cooled below steam temp. Examples of thermostatic traps include bimetallic and bellows. The bellows trap uses the temperature change in the substance to activate the evaporation or condensation of the alcohol inside the trap. This evaporation or condensation allows for the valve to close or open, therefore controlling the phase of the substance. Bimetallic traps use two strips of dissimilar metals to close the valve when steam is present. The valve will then reopen once the steam has cooled allowing the condensate to flow.

Mechanical
Unlike thermostatic traps, mechanical traps use the different density of steam and water to control the position of the valve. Mechanical traps commonly use a bucket or float to correlate the position of the valve. A few different types of traps include float and thermostatic, and open bucket traps. Open bucket traps rise as condensate rises, this allows for the valve to open. Once the bucket starts to fill with water it begins to close. Float and thermostatic traps use a float to correspond to a condensate level. When the condensate level rises, the valve opens. When the condensate level lowers the valve closes.