One of the most integral equipment in the process and manufacturing industries is the industrial boiler system. Steam is essential for performing the various operations in the plants. Therefore, industries take various factors into account before deciding on a boiler manufacturer for their plants. Not only is investing in a new boiler system an expensive affair, but it also needs assurance of longer performance and efficiency for seamless operations. The process plant tries to get as many years out of the boiler as possible, by conducting routine maintenance. It results in not only extending the life of the steam boiler but also improving its efficiency. On the other hand, regardless of how well anyone maintains a boiler system, it will eventually need to be replaced.
Factors to consider while selecting a new industrial boiler system:
Several factors are taken into account by the plant owners before they decide on a boiler manufacturer. Some of the noteworthy factors are as follows,
Expenses spend for repairs:
It is necessary to take a closer inspection on how much money is spent on repairs. It is necessary to stop investing money into repairs if there is a significant increase in the repair bills or if frequent assistance of boiler maintenance is required for the process plant. Even though replacing a boiler is an expensive process, it is even more expensive to continue repairing the old system. If the cost of repairs is rapidly growing, it is time to install a new boiler for the industry.
How old is the current boiler?
It is also important to consider how old the current industrial boiler is. Boilers can function for several years depending on when it was manufactured, what purpose it serves, and its maintenance. If process plants have had the same commercial boiler for a couple of decades, it may be time to replace it.
Energy efficiency is a major factor to take into account while choosing an industrial boiler system. Boiler manufacturers in India and all over the world consider the environmental impacts of their manufactured products.
Warranty of the boiler:
Top boiler manufacturers advise to always consider the terms of the warranty. A warranty is particularly important in inspecting how reliable the boiler system will be. Most of the warranties range from 10 to 15 years. However, industries must always be on the lookout for a longer warranty with good terms and conditions.
Size and space considerations:
The size of the steam boiler is imperative to fit it in the boiler room. Usually, process plants look for a boiler that has as small of a footprint as possible, as it saves both space and money. The smaller-sized boiler creates flexibility in space. It creates additional space in the boiler room and the possibility for multiple modular boilers working on the same system to improve efficiency and reduce the operating costs even further.
Safety of the boiler:
Safety should always be the utmost priority while choosing a new boiler. Sometimes, conventional steam and hot water boilers become overheated, leading to the build-up of high-pressure steam that can cause a hazardous explosion. One way to prevent the risk is installing a boiler system designed for low water content operation. With such industrial boilers, the amount of steam build-up cannot do excessive damage even if the unit malfunctions.
Another risk with conventional boilers is their design itself. The maintenance for these units requires the opening of heavy steel doors, realigning them, and closing them again by standing on a ladder which may result in various injuries.
With the ever-increasing air pollution, greenhouse gasses, and the environment, boiler manufacturers are making sure to prevent any harm caused by the industrial processes. Various industries face difficulties due to emissions from the use of conventional boiler systems. Even while using natural gas, these boilers release large amounts of CO2 and toxic nitrogen oxides (NOx) into the atmosphere, damaging the environment.
It is also important to consider how frequently the maintenance of the boiler system will require it to function at its best for as long as possible. Low-quality boilers require regular repairs that lead to excess costs and may result in replacing the boiler sooner than expected. A well-maintained steam system includes more than the pressure vessel condition itself. Effective monitoring and control systems can also help in identifying and fixing small problems before they turn into bigger issues.
Rakhoh Boilers is one of the trusted boiler manufacturers in Pune since 1983. With 39+ years of experience and expertise in thermal solutions, we deliver highly efficient and reliable industrial steam boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories to over 20 process industries in 27 countries worldwide. We provide excellent boiler services to boost the efficiency and productivity of the boilers.
Visit www.rakhoh.com for more details on our products and services
Steam Boilers are crucial for the processing operations in manufacturing industries throughout the world. As a leading boiler manufacturer and thermal solutions provider, Rakhoh Boilers are proficient in detecting inefficiency in the steam boiler system. However, reduced efficiency does not necessarily call for boiler replacement. It is important to understand that boiler replacement is an expensive and time-consuming process that should be considered a last resort. Steam boilers are an integral asset that operates efficiently for two to three decades if properly and regularly maintained. It is essential to understand signs that detect the requirement of boiler replacement and take the necessary course of action.
Factors to Consider for Steam Boiler Replacement:
While considering boiler replacement, it is prudent to assess three important factors- Safety, Economic, and Requirement Changes
Safety issues are usually detected during regular inspections as the inspectors check the condition of pressure vessels and boiler safety equipment. Along with a regular examination of steam boilers, it is necessary to monitor the process operations.
Consistent starting and shutting off steam boilers increases the thermal cycles that impact the pressure vessel. Fatigue in boiler steel is caused due to excess thermal cycles and resultant stress.
High Stack Temperature:
Stack temperature exceeding the normal level indicates poor heat transfer and hazardous conditions due to poor water quality, improper combustion, and low water levels.
Improper Starting and Shutting:
Irregular starting and shutting indicate the improper functioning of the operating and safety controls of the steam boiler.
Poor Combustion Tuning:
Error in fuel and airflow leads to pulsations and surging. It is usually caused by problems in the combustion fan, improper burner adjustment, improper stack design, and conditions.
Safety issues in steam boilers generally occur as waterside issues or fireside/combustion side issues. In most cases, issues in waterside are caused by poor water treatment that includes,
Scaling develops on the steam boiler tubes due to the absence of a water softener or improper water treatment. The scale formation hinders the heat transfer and results in overheating.
Poor Water Chemistry:
Lack of water chemistry control leads to caustic embrittlement that causes tubes to lose their vital mechanical properties.
Presence of Oxygen:
Improper water treatment system leads to oxygen pitting on the surface of the tube that consequently leads to corrosion.
Improper tuning leads to improper combustion and carbon deposits.
Outdated control equipment:
Outdated controls result in poor air and fuel control
Unsafe operating controls and safety equipment:
It includes unreliable flame scanners, safety relief valves, pressure and temperature switches, etc.
Reduced efficiency in steam boilers is a significant reason to consider boiler replacement. That is because inefficiency in the boiler leads to acceleration in fuel costs and operating hours. Therefore, improvements towards the efficiency of the steam boiler can considerably save the costs of the processing facilities. Along with it, consideration of the extent of reparation determines the need for boiler replacement. Sometimes, the cost of repairing can be expensive enough that boiler replacement would be a better alternative.
Advancement in technology and steam boiler design indicates that investing in boiler replacement would be a wise decision in the long run. An oversized boiler operating in a low range and occupying the majority of space is less desirable than boiler systems that are optimal for the load requirement. Such boilers can substantially reduce the excess costs and provide enhanced efficiency and performance. Plant managers can consult expert boiler manufacturers to understand their processing unit requirements.
These considerations must be given due attention before deciding on boiler replacement. Along with it, current and future plant loads should also be considered before replacing the boiler system.
Tips for Boiler Replacement:
Rakhoh Boilers is a trusted boiler manufacturer in Pune since 1983. With 38+ years of experience and expertise in thermal solutions, we deliver highly efficient and reliable industrial steam boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories to over 20 process industries in 26 countries worldwide. We provide excellent boiler services to boost the efficiency and productivity of the boilers.
Visit www.rakhoh.com for more details on our products and services
As we are aware, steam boilers play an integral role in the manufacturing and process sector for heating, processing, and sterilizing purposes. Although most process industries aim for high efficiency and production in minimal time, one of the most overlooked factors in the heating process is the dust collection and management that causes severe harm to the operating personnel and the environment. Yet, dust collectors are pivotal in ensuring that the steam boilers are functioning efficiently and safely. Just like any other equipment, industrial dust collectors too require regular maintenance. The dust collector system consists of ductwork, hoods, air-material separators, explosion protection, different airlocks, and exhaust fans and includes cyclone dust collector, baghouse, electrostatic precipitators, wet scrubbers, etc.
A Brief Overview of Dust Collectors:
Multi-cyclone dust collectors have been used along with air preheaters and steam boilers in energy generation and other process industries since the 1950s. Gradually, it has evolved in design and purpose, yet its function remains crucial in many process heating applications. In some cases, dust collectors are installed with air preheaters and steam boiler economizers for the purpose of recycling material and to add another layer of erosion protection. Multi-cyclone dust collectors without moving parts use centrifugal force for separating the particulate from the flue gas as it exits the steam boiler. Dust collectors can remove anywhere from 60% to 99% of the debris from the flue-gas stream.
Components of Dust Collection System:
Dust Collector Hoods:
Dust Collector Hoods are an essential component of a dust collector system that can produce remarkable results with minimum modifications. It is important to examine blown, ripped, or broken filter media, cracked filter assembly, airflow speed to ensure the designed airflow, inaccurate installation, separated bag filter, or a mechanical breakdown of the tube sheet due to abrasion. It must be ensured that it is operating in the right position, if the restricted damper is found by hood for balancing.
Ductwork is used to extract the dirt and air from the accumulating point of the collector. It must be sized precisely for producing a carrying velocity to keep dust moving.
Explosion Protection Equipment:
An explosion can be caused by a dust collection system preserved incorrectly. A properly designed dust collector managing combustible dust always includes an explosion protection system. The purpose of the explosion protection equipment is to restrain an explosion and reduce hazardous damage.
Air Material Separators:
An air material separator is a mechanical device to divide the conveying air from the material being conveyed.
A rotary airlock separates the dust collector hopper externally allowing the collected dust to exit the system. Usual types of airlocks include rotary valves, trickle valves, double dump valves, and knife gates.
The main objective of a rotary airlock valve is to provide an air seal at the outflow opening of the dust collector hopper. It is installed usually between the hopper flow and a conveyor or release bin.
Trickle valves, also known as vacuum valves, are used for managing the airlock seal on the dust collector tank and for discharging bulk solid material.
Dust Collector Exhaust Fans:
Dust collection systems require an exhaust fan for stimulating ventilation air from the position of acceleration through the ductwork.
Corrosion and Erosion of Metal in Dust Collector System:
Dust collectors become ineffective due to significant damage caused by erosion or corrosion. Multi-cyclone dust collectors are impacted by abrasion through fly ash, particulate mass, and high-velocity gas flow that causes corrosion from chemical attacks. In severe cases, an ineffective dust collector leads to the failure of vital equipment like tubular air heaters, induced-draft fans, precipitators, or baghouse components. Additionally, a dust collector’s operating efficiency may drop significantly due to changes in velocity and pressure drop when ash or other particles plug a cyclone or tube. An overload of particulates may also plug other equipment in the path of the flue-gas flow.
Therefore, regular inspections allow temporary internal repairs during the inspection process, prolonging the life of the equipment and delaying its replacement.
Advantages of Regular Maintenance of Dust Collector System:
Rakhoh Boilers are one of the leading manufacturers of industrial steam boilers in Pune since 1983. Over 38+ years, Rakhoh has successfully installed more than 3000 boilers in 26 countries worldwide. We also provide excellent boiler services like energy audit, boiler automation, steam trap assessment, annual boiler maintenance, fuel conversion, etc.
For more details on our products and services, visit www.rakhoh.com
Steam boilers are classified into two types, namely fire tube boilers and water boilers. As the name suggests, fire tube boilers function by flue gases passing through fire tubes immersed in water, whereas water tube boilers operate by water flowing through water tubes placed in a firebox. Steam boilers are an important asset for the process operations in the industries but can be a potential bomb if left overlooked. Boiler explosions can cause tremendous loss and injure the operating personnel. Therefore, boilers include safety equipment to avoid any hazardous mishap. One such equipment is the fusible plug that prevents the exceeding temperature in fire tube boilers resulting in a boiler explosion.
What is a Fusible Plug?
A fusible plug is equipment that boosts the safety of the steam boiler and acts as a warning device against overheating. Fusible plugs are found in fire tube boilers and are usually considered the last resort or warning to avert any hazardous failure such as a boiler explosion. Just like safety valves help to protect the boiler system from overpressure, fusible plugs help to safeguard steam boilers from over temperature. Fusible plug is widely acknowledged as the preferred safety equipment for fire tube boilers by many industries due to its simple design, effectiveness, and improvement in safety.
Design and Material of Fusible Plug:
Fusible plugs include a fusible alloy made of tin material. The fusible plug itself is made of brass, bronze, or gun material with a threaded plug body that makes it easy to install. It is a hollow gun metal plug screwed at the apex of the firebox. The main metal plug and hollow gun metal plug are separated through an annulus fusible material. A flange protects the material from the fireside. The fusible plug has a high melting point, while the fusible alloy has a low melting point of 232°C (450°F).
The Role of the Fusible Plug:
The fusible remains immersed in water with the water in the fire tube boiler at a normal level. As the temperature does not reach the melting point of the fusible alloy, the heat is transferred to the water. As the temperature in the boiler increases, the water level starts decreasing and generates steam. On the other hand, the fusible plug above the firebox gets overheated by the exceeding temperature, and the fusible alloy starts melting. It results in steam and water immediately rushes through the fusible plug to extinguish the fire in the firebox, thus preventing boiler explosion. The fusible plug body is shaped in a way to alert the operating personnel of system pressure vents by a whistling sound. Fusible plugs reduce the possibility of boiler accidents taking place due to low water firing. The low water level in the boiler system leads to overheating of the heat transfer surfaces that can cause catastrophic accidents. It is advisable to replace the fusible plug after two years as they probably get defective after a long period of use.
Where is the Fusible Plug Installed?
Fusible plugs in fire tube boilers are located around 1 to 2 inches above the top row of tubes. Usual locations for the fusible plugs include the crown sheet i.e., the apex of the combustion chamber, rear tube sheet, and front tube sheet. The fusible plug location depends on the boiler design.
Faults and Inspection of Fusible Plugs:
Rakhoh Boilers are one of the globally leading boiler manufacturers for more than 38 years. We have provided efficient and reliable water tube boilers, fire tube boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories for over 20 process industries worldwide. With proficiency in thermal solutions, we offer the best boiler services like energy audit, steam trap assessment, boiler automation, annual boiler maintenance, etc., that enhances the productivity and lifespan of the boiler.
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Steam Boilers are of paramount importance in the process and manufacturing industries. However, merely the excellence of the boiler manufacturer does not assure the boiler’s safety. The boiler system also requires precision in handling and operations to prevent hazardous consequences. Although plant managers take every precaution to ensure the safety of the plant and the personnel, some boiler issues are inevitable and require immediate action. Despite the usage of steam boilers in industries from the mid-1800s, process plants continue to face common issues with their operation.
Some of the most common boiler issues include:
- Low water conditions
- Improper techniques of blowdown
- Improper warm-up
- Poor water treatment
- Training of operating team
- Neglect of preventive maintenance
- Proper documentation
- Overlooking outdated equipment
- Manual factor
Low Water Conditions in Steam Boilers:
Facing low water in a boiler system is a hazardous situation but can be easily prevented with proper maintenance and precautions. The low water level in a steam boiler occurs when the water reaches below the base safe, that is the working level recommended by the boiler manufacturer. With the low water level, the tubes remain exposed and no longer cooled by the boiler water. It leads to the rapid increase of the metal temperature, resulting in reducing the metal’s strength and causing rupture as the metal’s strength decreases.
The likelihood of severe or even catastrophic damage to a steam boiler due to low water conditions is easy to understand, considering that the temperature of the furnace exceeds 1,800 oF., yet, the steel strength drops significantly at temperatures above 800 oF. The only factor that enables a boiler system to withstand the furnace temperatures is water in or around (depending on whether the boiler is a fire tube or a water tube design) the pressure parts at all times when a fire is present. Therefore, low water conditions can melt the steel pressure parts.
Generally, industrial steam boilers are natural circulation boilers that do not use pumps for circulating water through the pressure vessel. The units depend on the varying density between hot and cold water for providing circulation. As the water eliminates heat from the pressure parts, the water temperature increases and rises to the steam chamber. As a result, sufficient heat is transferred, generating steam. Cold feed water replaces the rising water, causing natural circulation.
Because of the crucial need for water, advanced boiler systems are equipped with automatic low water trip switches. However, some outdated boilers do not include these relatively inexpensive devices. If the boiler does not have low-water trips, it is necessary to promptly initiate its installation to prevent any accidents and expensive repairs in the process plant. The resultant repairs can range from re-tubing to unit destruction if the overheating is neglected. In the situation of low water, the low water trips will trip the burner or fuel flow for solid fuel boilers and shut down the forced draft fan. It leads to shutting down the heat input.
The trips need to be installed at a water level to prevent damage. Low-water trips are installed at 6” lower than the acceptable operating level. The control of the boiler water level is challenging, and even the best-tuned control systems cannot ensure complete prevention of a low-water condition. The water level in a pressure vessel is, in fact, an unstable compressible mixture of water and steam bubbles that can shrink and swell with pressure changes and will ultimately shrink momentarily when more cold feedwater is introduced.
Some of the common causes of low water levels in the steam boiler are:
- Failure of feedwater pump
- Failure of control valve
- Water loss to the deaerator or make-up water system
- Failure of drum level controller
- The drum level controller is left in the manual position
- Plant air pressure loss to control the valve actuator
- Lifting of safety valve
- Large, sudden change in steam load
Impact of Low Water Levels On Steam Boilers:
Some of the commonly found damage caused by low water levels are:
- Loose tubes
- Cracked tubes
- Melted metal
- Leaking water
One of the most hazardous results of low water takes place when the water is added to the boiler, but the system has already passed the point of no return where the boiler vessel is significantly overheated. It causes the water to immediately turn into steam, resulting in extreme pressure being created, and the boiler potentially exploding. It is one of the most dangerous consequences in a process plant with any boiler system and should be prevented at all costs.
Prevention from Low Water Level:
Steam boilers should be fitted with low water cut-offs (LWCO) for detecting the low water condition and shut down the boiler to prevent the impact of low water levels. Additionally, controls need to monitor the water level and take appropriate action such as sounding the alarm, shutting down the burners, and the feedback supply. It is also crucial to provide an external indication of the water level.
A low level of boiler water is checked through the sight glass. It is the only visual available to check the steam boiler’s water level.
Some boiler systems use floating bulbs with the LWCO shutting down the boiler if the bulb hits the cutoff level. With a float system, the device must be regularly blown down to prevent buildup.
Some LWCO systems utilize a probe that enters directly into the water and shuts down the boiler again if the water gets below the permissible water level.
Rakhoh Boilers is a trusted boiler manufacturer in Pune since 1983. With 39+ years of experience and expertise in thermal solutions, we deliver highly efficient and reliable industrial steam boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories to over 20 process industries in 27 countries worldwide. We provide excellent boiler services to boost the efficiency and productivity of the boilers.
Visit www.rakhoh.com for more details on our products and services