Steam Boiler: Appurtenances of Steam Boiler

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Boiler Sootblower

Boiler sootblower is one of important equipment to maximize steam boiler efficiency. Efficiency of boiler is influenced mostly by heat transfer process. One among the most necessary operations to increase heat transfer process is clean metal surfaces for absorb heat. The cleaning metal surfaces is performed to ensures appropriate heat transfer process and in addition avoids parts of steam boiler from growing to be plugged and blocked. Plugged parts could limit gas circulation and lead to load restrictions.

Boiler sootblower is specially needed on coal fired boiler and oil fired boiler. If oil fuel consist of low content of ash and generate small residue, the cleaning method of furnace wall can be performed by water washing for the duration of twelve-monthly shutdown. This is why; boiler sootblower which is installed on furnace wall is not needed on the oil fired boiler.

In the reheater and superheater parts of oil fired boiler, there's ash accumulation on metal surfaces. Excessive-oil vanadium subject matter that contains chemicals to resist high-temperature corrosion, tend to be specifically vulnerable to the following. However while solid powder chemicals are utilized, the deposits of ash boost seriously in the high temperature of gas locations. The good thing is, the deposits fall and easily cleaned with boiler sootblower.

Coal fired boiler need many sootblower which is installed permanently. Reasons like high content of ash and ash-fusion temperatures determine simply what exactly sootblowing area is needed. Boiler sootblower usually utilizes compressed air or superheated steam as medium to eliminate deposits, utilizing rotary or retractable types. The efficient blowing regularity varies according to slag accumulation; however a usual could be four until eight hours. The steam boiler parts such as reheater and superheater is suitable to use long retractable type of sootblower to clean radiant heat surfaces.

Differential Pressure Transmitter

Differential pressure transmitter is one of pneumatic transmitter types. Pneumatic transmitter uses high-pressure air as the medium. The air pressure is generated by compressor. The air is supplied to the transmitter with pressure approximately 20 Psi. The next step, transmitter issue standard signal with pressure 3-15 Psi.

Pneumatic transmitter types are often used for measurement is Differential Pressure Transmitter as show in Figure 1 below.

Figure 1: Differential Pressure Transmitter

In differential pressure transmitter, the pressure of fluid that will be measured is connected on two sides of transmitter; high pressure side and low pressure side, where both sides are mounted in area between diaphragm capsules. The side that has low pressure will flow on the right side of diaphragm capsule. At high pressure side, fluid flows greater than fluid at low pressure side, so the push force of diaphragm from left side to right side of diaphragm will be greater.

The change force of diaphragm is then channeled through flexible bar to move the force bar, where the bar rotates counter-clockwise. Seal diaphragm acts as a fulcrum and as a result, cavity between nozzle and flapper becomes smaller. So air will normally come out from nozzle cavity. Nozzle gap must be limited so that the pressure generated by nozzle transmitter will increase and the output will get reinforcement from pneumatic amplifier.

Part of the output is used as feed back bellows which is modified in the form of reinforcement. The reinforcement of differential pressure transmitter is used by range bar and use range wheel as a fulcrum. By making changes to the flapper position will reduce pressure transmitter. The end result is difference pressure between before diaphragm and after diaphragm will occur. Gap between flapper and nozzle transmitter that has been reduced will increase the output and stabilize it, by this way both pressure will be balanced.

The Role of Valve in Steam Boiler

Valve has important role in steam boiler. Valve is one of required equipments in steam boiler to control flow of water or steam. Control velocity, debit, volume of fluids, and to make flow start or stop, are some of roles of valve.

Valve can be classified by internal configuration. Based on internal configuration valve can be classified as globe valve, ball valve, check valve, non return valve, gate valve, and butterfly valve.

Gate valve is valve that is used to make flow fully stop or fully open, there is minimum restriction in this type and usually used for straight line flow. Globe valve is valve which is used to regulate flow, and the fluids will has more resistance if flow through globe valve than gate valve.

Check valve is valve which is used for flow one way direction or non return direction. Non return valve is used to eliminate steam flow back into a steam boiler if the pressure of steam line piping is under the pressure of header in steam boiler; this type is automatic stop check valve.

Butterfly valve is valve which is used for regulate and isolate flow, it allow for quick stop flow. Ball valve has similar function with butterfly valve, the differences is ball valve use spherical disc to regulate flow.

Valve can be also classified by function in steam boiler, Based on its function valve can be categorized as vent valve, safety valve, control valve, safety shut off valve, and so on. Vent valve is used for release air or steam when steam boiler is being filled with water; it is usually located on the highest level. Safety valve is used for protect steam boiler if operating pressure exceed maximum allowable working pressure, the valve will automatically pop up to release excess pressure. Control valve is automatic control to regulate how many percent debit flow of fluid will be allowed. Safety shut off valve is used to close and stop line flow of fluid.

Appurtenances of Steam Boiler

Appurtenances are devices which are installed to the steam boiler readily to make steam boiler can be performed safely. Appurtenances can also be known as mounting and fitting. Safety should be paramount in designing steam boiler. The following below are some of appurtenances that are installed to steam boiler:

1. Safety Valve
Safety valve is protective device that be used in the steam boiler to avoid overpressure; pressure that occurred in the steam boiler exceeds the Maximum Allowable Working Pressure (MAWP). If the pressure increases until it reaches MAWP, the safety valve will pops up until pressure drops.

2. Pressure Gage
Pressure gage is measuring device that be mounted in the steam boiler to look working pressure in the steam boiler at various point. The pressure is maintained in allowable pressure range.

3. Water Column
A water column has some fitting such as gage glass (a device as primary indicator of water level in the steam drum), and try cocks (a device as secondary indicator ofwater level). Water column is used to decrease turbulence in water gage, so water gage can be read accurately.

4. Blowdown Devices
Blowdown devices are device to discharge scale and sludge from the steam boiler.

5. Fusible Plug
Fusible Plug is device to prevent inadequate water in the steam boiler; it gives warning if condition in the steam boiler is low water.

6. Soot blower
Soot blower is device to remove soot and slag around pressure part and maintain heat transfer on the surface of pressure part.

7. Steam Boiler Venting
Steam boiler venting is device to remove air when filling water and warming the steam boiler.