Different mountings fitted on a boiler

Introduction

A boiler just cant run on its basic working system. There are many external equipments that help a boiler run efficiently. For example, it would have been too difficult to keep a continuous watch on the boiler water level had there not been cascade or boiler automation system. In the same way there are a few important boiler mountings that are fitted on the boiler body itself for a safe and efficient running of the boiler. These fittings are the basic requirements of the whole steam production system.

The main boiler mountings are:

Safety Valves

You would always find safety valves mounted in pairs on main boiler body. Safety valves are provided on a boiler to protect the boiler from overpressure. All the safety valves are preset at a particular fixed boiler pressure. This means that the valves are set at a particular lifting pressure and locked to prevent any kind of manipulation later on. The safety valves operate automatically when the boiler reaches the pre-set blow off pressure.

Main Steam Valve

This is the most important valve of the whole system. Main steam stop valve is a non return valve, fitted on the main steam line just near to the boiler. It is the main valve by which the supply of steam from the boiler to all the ship’s systems can be started or stopped.

Auxiliary Stem Stop valve

This is like a back up valve to the main steam stop valve. This means that in case some problem occurs with the main steam stop valve, the auxiliary valve still protects the system from any kind of damage. It is also a non return valve type.

Feed Check or Control valve

These valves are also found in pairs. One of the valve out of the two valves is the main valve and the other is an auxiliary or stand by valve. These valves are also non return valves and they always carry an indication of their open or closed position.

Feed Check Or Control valve

These valves are also found in pairs. One of the valve out of the two valves is the main valve and the other is an auxiliary or stand by valve. These valves are also non return valves and they always carry an indication of their open or closed position.

Water level gauges

Water level gauges are one of the most important mountings of the boiler. Always found in pair, the water level gauges help in maintaining and monitoring the appropriate water level in the boiler. Thus they help in preventing accidents and damage to the boiler. The gauges are always fitted at the opposite ends of the boiler to prevent wrong reading due to motion of the ship. The type of the water gauge fitted depends on the the working pressure of the boiler

Pressure Gauge Connection

Pressure gauges are fitted on the boiler drums and superheaters for pressure readings. They should be periodically checked to prevent accidents due to wrong readings.

Air release Cock

An important equipment for the boiler starting procedure, the air release cock are fitted in boiler drums, headers etc to purge out the air when filling the boiler or during raising steam

Sampling Connection

This connection is mainly for taking feed water samples for testing and analysis purposes. The samples are collected through this connection and if any kind of chemicals that are to be added to the boiler water they are injected through the this connection.

Blow Down Valve

Used for emptying the boiler water, the blow down valve is fitted at the lowermost end of the boiler. It is also used for partial emptying the boiler and is an important valve in the blow down process.

Scum Valve

This valve is used for removal of impurities from the boiler water. The scum or impurities float on the top of the water. A shallow dish is positioned at the normal water level to collect the scum from the top of the water level.

Whistle Stop valve

It is small bore non return valve which is used to supply steam to the whistle straight from the boiler drum

Additional mountings on Water Tube boiler

Water tube boilers use less water and produce more steam in comparison to it.Due to this reason the chances of accidents due to high temperature and pressure are greater. Due to this reason, water tube boilers have extra mountings

Automatic feed water regulator

Fitted in the feed water line just near the main check valve, the automatic feed water regulator ensures correct water level in the boiler in spite of the fluctuating load conditions. Boilers having high evaporation rate use multiple element feed water regulator

Low alarm level

Produces an alarm sounding when the boiler reaches low water level condition

High alarm level

Produces an alarm sounding when the boiler reaches high water level condition

Super heater circulating valves

Used during the initial warming up process and during the boiler starting procedure, the valves ensures a steady flow of steam and also act as air vents

Sootblowers

Generally used during the boiler maintenance procedure.Sootblowers use pressurized steam or compressed air to blow off the soot and other combustion products deposits from the surface of the tube.

References

Introduction of Marine Engineering 2nd Edition by D.A Taylor