Boilers and It's Types

 

Introduction

 

        In this blog, we will learn about what a boiler is and how it works. 

But first, let us look at the phrase "heat." Heat is essential in everyone's daily existence. We all need heat in our daily activities, whether it is to warm up our surrounds or to cook food. 

  

Water and steam are excellent heat carriers that do not harm the environment. Water has a boiling point of 100°C (212°F) at atmospheric pressure. We can raise the boiling point by pressurizing the boiling system and securing it with an airtight seal. The operation of a pressure cooker is as follows. Increase the pressure in an airtight vessel to raise the boiling point. This allows the food to cook in a fraction of the time it would take in an open saucepan. 

 

However, how does it compare to boilers? So, let's get started on this subject. 

What are Boilers? 

According to the IBR Act 1923 (Indian Boiler Regulation), a steam boiler is any closed vessel with a capacity of more than 22.75 liters that is used expressly for producing steam under pressure. 

 

Applications of Boiler 

We use a boiler for: 

• Steam turbines 
• Sugar mills 
• Dairy milk 
• Papers Industry 
• Textile Industry 
• Hospitals and Health Care Facilities 
• Industrial laundry 
• Food preparation 
• Steam has a high heat content, making it ideal for process processes in a variety of industries, including sugar mills, textile mills, dairy plants, and chemical plants. 

Terms used in Boiler: 

 

• Shell: Shell is external cylindrical part of boiler. The boiler shell is made up of steel plates that are riveted or welded together to form a hollow cylindrical body. 
• Furnace: The furnace is the part of the boiler where the fuel is burned to generate heat. In the furnace, this heat is used to generate steam. 
• Grate: The grate is a flat surface where the fuel is burned. It is made up of a series of cast-iron bars that are arranged in such a way that the fuel can be poured on top of them. Between two consecutive bars, some space is often given so that fuel can flow to the fuel from below the Grate and ashes can fall into the ash pit provided underneath the Grate. The outline of the grates may be oval or rectangular. 
• Grate Area: Great area refers to the surface of the great where the fuel burns. The size of the grate is often expressed in square meter. 
• Heating Surface:  Hearing surface is surface of boiler whose one region which is exposed to hot gases, and on the other it is exposed to water. 
• Water space and Steam space: The volume of the boiler that is filled by water is known as water space. Although steam must be stored in the boiler before it is drawn off through the steam pipe, the remaining space is known as steam space. 
• Flue Gases: The mixture of fuels in the boiler furnace produces flue gases, which are hot gases. Water vapor (H2O), carbon dioxide (CO2), carbon monoxide (CO), and nitrogen are commonly found in flue gas (N2). Flue gas is made up of both complete and incomplete combustion materials. 

What Are the Different Boiler Types? 

 

        Boilers come in a variety of shapes and sizes, and they may be used for a variety of purposes. 

We will go through a few of the many types, as well as how each one generates heat, so you can become familiar with them and be able to accurately identify them. 

According to the circulation of gases: 

1. Fire-Tube Boiler 

 

The components of a Fire-Tube boiler are: 

• Furnace 
• Water tank acting as a boiler. 
• Smokestack 

 

Fig. Fire tube Boiler

         The heat from the furnace is carried by tubes that run through the water tank, and the smokestack vents the heat and gases produced by the heating action so that the pressure does not increase over the desired level. 

As a result, the fuel is consumed within the furnace. The heat from the furnace is transferred through the tubes to the water in the tank. The steam produced is then transferred downstream once it has been heated. 

 

Because of the thickness of the outer shell housing the water, fire-tube boilers are often the cheapest to manufacture due to their basic design. However, owing to the thickness of the outer shell carrying the water, they are often confined to low to medium pressure applications. 

2. Water-Tube Boiler 

 

Let us have a look at a water-tube boiler now that we've covered the fire-tube boiler. 

The architecture is like that of a fire-tube boiler, except that instead of firing fire tubes to heat water in a tank, the furnace warms water tubes within the furnace. 

Fig. Water Tube Boiler

Similarly, in the furnace, a fuel source is burnt, causing the water tubes inside to heat up. Steam is formed and pushed downstream once again when the water is boiled. 

A water-tube boiler is more effective in terms of heat transfer than a fire-tube boiler, but it is more difficult to build, and the water quality might be a limiting issue. 

To be most effective, the water may need to be filtered. 

 

Bab-cock and Wilcox boiler, Benson boiler, etc. are example of water tube boilers. 

According to Circulation of water: 

1. Free circulation 
2. Forced circulation. 

1.Free circulation 

Because water is a poor conductor of heat, heat is transferred from one location to another through convection in any water heating device. 

Allow a vessel containing water to be heated at its bottom; as the water in the bottom section of the vessel is heated, its density decreases in comparison to the density of water in the upper half of the vessel; as a result, the less dense water at the bottom portion of the vessel rises, while comparably more dense and cold water from the upper half of the vessel descends to take its place. As a result, a convection current is created in the water until the temperature of all the water is equal. 

The above-mentioned form of water circulation is known as free circulation. 

Water circulates freely in boilers such as Lancashire, Babcock, and Wilcox, among others. 

Advantages of free circulation: 

• The free circulation of water helps to maintain a constant temperature throughout the boiler, preventing unequal expansion of different regions of the boiler. 

• Water facilities that circulate freely the instantaneous escape of steam from the heating surface. The boilerplates do not stay in constant contact with water if steam does not escape quickly after formation, and as a result, these plates may be overheated. 

 

2. Forced circulation 

        Pumps are used in forced circulation to keep the water flowing continuously in the boiler. The circulation of water occurs in this case due to the pressure provided by the pump. More high-pressure, high-capacity boilers, all of which are water tube style boilers, use the forced circulation system. 

Advantages of Forced circulation:  

• The heat transfer rate from flue gases to water is faster. 
• It is possible to use tubes with a smaller diameter. This decreases the boiler's total weight. 
• It's possible that the number of boiler drums required can be decreased. 
• In the boilers, less scale forming is needed. 
• Steam can be generated quickly. 
• The load fluctuation can be easily managed without the use of any complicated control devices. 
• The chances of the boilerplates overheating are negligible to none. 
• There is less weight per unit mass of steam produced. 

According to the number of tubes used: 

1. Single tube boiler 
2. Multi-tube boiler 

Single tube boiler 

    A single tube boiler is one that has only one fire tube or one water tube. Cornish boilers and simple vertical boilers are examples of single tube boilers. 

Multi-tube boiler 

    Marc Seguin devised a two-pass boiler in 1828, with the second pass created by a bundle of several tubes. This was a major step forward. Multi-tubular boilers are those that have two or more water tubes or fire tubes. Multitube boilers include the Lancashire, Locomotive, Cochran, Babcock, and Wilcox boilers. Because of the many flue tubes, the Cochran boiler is referred to as a multi-tube boiler. 

According to the nature of use: 

1. Stationary boilers 
2. locomotive boilers 
3. Marine boilers 

Stationary boilers 

        Stationary boilers are used for the generation of thermal power and process operations (in the chemical, sager, and textile industries). 

locomotive boiler 

        The locomotive boiler is a multi-tubular, horizontal drum axis, natural circulation, forced circulation, mobile, medium pressure, solid fuel fueled fire tube boiler with an internally fired furnace. 

Marine Boilers 

        A large supply of high pressure superheated steam is needed by the ship's main engine and auxiliary power generators. Single or several water tube oil fired marine boilers produce this steam. The operation of the boilers is identical, but the number of drums varies. These drums have domed ends and are horizontal pressure vessels. 

According to pressure: 

High pressure boilers 

        Steam is heated at pressures more than 15 psi, and water is heated at pressures more than 160 psi in high-pressure boilers. High-pressure boilers can reach temperatures of over 250 degrees Fahrenheit. Because of the high pressure at which these boilers work, they must be constantly monitored to ensure their safety. Switches, valves, safety devices, and leaks must all be inspected daily by high-pressure boiler operators. Any malfunctions must be repaired right away to avoid further damage. 

Applications:  

• In Factories. 
• Power Plants 
• Laundromats 
• Locomotive Steam engines 

Low pressure boilers 

           Low-pressure boilers have a maximum pressure of 15 psi, and hot water heating boilers have a maximum pressure of 260 psi. A low-pressure boiler's temperature will not exceed 250 degrees Fahrenheit. Because these boilers function at lower pressures, they do not need to be examined on a regular basis; instead, they only need to be checked when they start to fail. 

Application: 

• In buildings to heat rooms via radiators. 
• In Hotels, restaurants  
• In Bathroom It may be utilized in the bathroom as well as other areas of the building. 

Safety measures for boilers:  

        We gathered a few industrial steam boiler safety measures and tips for boiler maintenance workers after conducting thorough research on boiler explosion accidents and the causes of boiler blasts. 

Precautions to Take Before Starting a Steam Boiler: 

• Before starting a boiler, hydraulic testing should be performed at a specific pressure. 
• At the start of a boiler, make sure the pump inlets are open. 
• To avoid ash accumulation in a furnace or other machinery, install an automated ash removal device in a boiler, such as rotary valves. The accumulation may cause a blockage or overheating of boiler parts, causing the boiler to fail. 
• At the start of the boiler, the pump must be primed. 
• Before starting your boiler, search for any loose or incorrect connections and make sure they are fixed. 
• To operate your boiler, you'll need to engage a qualified and experienced boiler operator. 

 

Precautions to be carried out Regularly: 

• Never run a boiler above the design load, and make sure all safety valves and fusible plugs are working properly. 
• The perforated line must be cleaned on a regular basis. 
• To extract dirt particles from boiler feed water and avoid feed line blockage, a Stainer must be placed before the pump and checked for proper operation. 
• To prevent dirt from accumulating in the boiler shell, water must be cleaned before being fed to it. 
• It is important to inspect and maintain the boiler, as well as its accessories and valves, on a regular basis to look for potential defects and cracks. 
• Make sure there are no obstructions in the boiler vents, such as fabric or other materials. 
• Always check for steam, water, air, and flue gas leaks from any suspected location. 
• Follow the instructions in your boiler's handbook to ensure that it operates safely and efficiently. 
• The panel should be cleaned on a regular basis and maintained in a cool, dry location away from your boiler. 
• Check to see if all of the boiler's hot parts are insulated; if they aren't, don't touch them with your bare hands. 
• Both the FD Fan and the ID Fan require regular maintenance, including checking for grease in all moveable components for ease of operation. 
• Cleaning moveable mechanical parts on a regular basis is required. 
• Both the FD Fan and the ID Fan require regular maintenance, including checking for grease in all moveable components for ease of operation. 
• Cleaning moveable mechanical parts on a regular basis is required. 
• For the safe operation of motors, do not increase the frequency of a drive above 50 Hz. 

Precautions to be carried out Occasionally: 

• Clean the boiler tubes on a regular basis to avoid ash build-up or scaling within or outside the tubes. Failure to do so will reduce boiler efficiency and eventually cause tube overheating, resulting in tube leakage issues. 
• According to fuel feeding, the primary and secondary air ratios must be maintained. 
• To avoid any thermal dangers, check the back pressure and line pressure of the burner on a regular basis. 

Hope you like this quick overview of Boilers. 

Do you have a friend, customer, or co-worker who might benefit from any of this information? Please spread the word about this article. 

Happy learning.