Have you ever wondered what are the different equipment attached to a boiler to keep it running safely and efficiently? Well, those are what we call boiler accessories and boiler mountings.
Boilers on ships are fabricated and operated on a very large scale and like the hazards of boiling water on your kettle at home – ship boilers present the same hazards and dangers too. The only difference is, that it is multiplied by a hundred times.
So, for you young folks dreaming to become ship engineers someday, might be a good idea to continue reading. The succeeding parts will let you be equipped with knowledge that could save your life.
What are boiler mountings?
Boiler mountings are equipment fitted on the steam cycle that is essential in controlling and regulating steam production and steam pressure. I would like to reiterate that it is essential because without these mountings it is impossible to operate ship boilers. These items can either be on the side, top, or even at bottom of the boiler structure. One thing always in common between these items is they are always attached to the boiler body.
Controlling a boiler does not only mean regulating the steam. Boiler mountings are also responsible for making sure all other factors for steam production are controlled and monitored. The water level on a boiler is regulated, it cannot go either too low or too high.
The too low water level may cause a very high temperature in the boiler tubes which can weaken the structure and rupture. Either way, the water level cannot be too high as well because it may cause over-production of steam or in technical terms is referred to as over pressure. An over-pressurized boiler can also be managed by boiler mountings. As you see these mountings play really important to the boiler operation.
A quick list of boiler mountings is safety valves, manholes, feed water regulators, water level gauges and etc. These items will be discussed thoroughly later on.
What are boiler accessories?
Boiler accessories are equipment fitted on the steam cycle that is not essential, however, increase the efficiency of the system. Well, unlike boiler mountings boiler accessories were developed later. Why? Because without these items steam can still be produced by the boiler it itself with its mountings. Accessories, on the other hand, improve steam production with the same or even less raw material.
Basically, since the boiler is about heat transfer, from the exhaust gas to water-steam. We can say boiler accessories in general are apparatus used to minimize loss during the heat transfer. These items are normally not attached to the boiler structure but are present with the steam cycle system. Even it is not as important as boiler mounting one should still pay an equal amount of interest with these accessories because it is still part of the system and is maintained by the ship’s engineers regularly.
A few identified accessories are economizer, steam trap, superheater, feed water pump and etc.. These items will be discussed deeply in the later of this article.
What is the difference between boiler accessories and boiler mountings?
By the definition stated and you read above there are significant differences we can layout of easily identify an item whether it is an accessory or a mounting. Please refer to the table below.
|An item that promotes efficiency in the steam production||An item that promotes the safety of the steam production|
|Item installed around the boiler system||Item installed at the boiler structure itself|
|An item that can be removed but still continue steam production||Items when removed stop the steam production|
|Items to improve steam production||Items to regulate/control production|
However, there is one similarity we can see between these items- they are both used for steam production.
I hope the simplified comparison made will help you identify easier and faster a boiler mounting over and accessory. In the last part of this article, the accessories and mounting will be identified one by one and will be discussed briefly one after the other.
What Are Boiler Mountings And Accessories?
Now that we know how essential steam production aboard the system also requires automation and control. The steam is very hazardous as it harnesses a vast amount of energy when mishandled and can cause serious injury or even death.
For this boiler mountings and accessories are equipped on board to control and regulate steam production safely as it cycles around the ship.
Boiler mountings are equipment fitted on the steam cycle that is essential in controlling and regulating steam production and steam pressure. These are safety valves, manholes, feed water regulators, water level gauges and etc. These items will be discussed thoroughly later on.
On the other hand, boiler accessories are equipment fitted on the steam cycle that is not essential, however, increases the efficiency of the system. They are economizer, steam trap, superheater, feed water pump and etc.. These items will be discussed deeply in the later of this article.
Physically, boiler mountings are devices fitted around the boiler itself while the boiler accessories are items installed along with the steam cycle system.
List of boiler mountings
- Water level indicator – A water level indicator is commonly fitted on the front of the boiler drum. They are manual inspection glass that always indicated the water level inside the boiler drum. Oftentimes, these water level indicator glasses are installed in pairs to ensure the accuracy of the boiler drum water level.
- Safety valve – safety valves are located at the steam boiler top portion. The purpose of the safety valve is to prevent excessive steam pressure inside the boiler. Safety valves open and release the excess steam pressure to the atmosphere when the boiler’s internal pressure is greater than its designed working pressure. Usually, two (2) safety valves are fitted on boilers. Main and auxiliary safety valves. The redundancy of such fitting is to safeguard safety valve function in case of main safety valve failure.
- Feed water regulator – The feed water regulator can be located along the feed water line of the steam boiler system. This device is fitted to maintain the proper water level on the boiler drum under different load conditions.
- Stop valve – Stop valves are located at the very top of the boiler. This valve is the foremost control of steam pressure from the boiler steam drum to the steam consumers. They are also typically installed in pairs; a main and auxiliary steam stop valves.
- Pressure gauge – A pressure gauge like the water level glass indicator is installed in front of the boiler drum. This gauge measures and indicates the steam pressure inside the steam drum.
- Top blow valve – Top blow valve is a passage when opened will drain the dirt contamination or concentration developed on the upper area of the boiler water drum. It is located at the side of the boiler drum before the top area.
- Bottom blow valve – The bottom blow valve, like the top blow valve, is used to drain sediments and contaminants on the feed water on the boiler drum, however, these bottom blow valves are located below a portion of the boiler. For greater cause, these valves are also used to drain the boiler fully during maintenance.
- Manhole – The manholes of a boiler are located both at the top and below the portion of the boiler drum. These manholes are used for inspections and cleaning of the tubes from top to bottom portion.
List of boiler accessories
- Feed water pump – feed water pumps can either be automatically or manually operated. But usually, in automatic operation, the feed water pump is signaled by the water drum level indicator to pump and compensate for the water evaporating rate and fill the boiler water drum. These pumps suck water from the condensate drain tank.
- Superheater – A superheater is a composite of tube bundles like the boiler itself. The main purpose of a superheater is to increase the steam temperature without increasing its pressure (isobaric). It uses the exhaust gases (flue gas) as a means of a heating element of the steam. With the use of a superheater, the steam carries more heat energy without increasing pressure on the system making it more efficient. Less steam consumption by volume but same heat energy output.
- Economizer – Economizers are heat exchangers between the feed water and exhaust gas. This heat exchange warms up the feed water before entering the boiler water drum. The warm feed water takes less heat energy to boil off thus increasing efficiency in the system.
- Soot blower – Soot blowers are boiler accessories used to flush the soot or dirt accumulated by the flue gas inside the tube bundle while the boiler is in operation. This dirt deposit gets thicker and thicker over time. The thicker the deposit the less heat transfer rate between the hot exhaust gas and water.
- Steam trap – Steam traps also known as steam separators are fitted along with the steam line system. The purpose of such is to drain and remove water particles from steam traveling along the steam line.
- Pressure reducing valves – Pressure reducing valves are used to maintain the steam pressure on the steam line system, and regulate and maintain the designed working pressure while the steam travels to each consumer.