Leakage in Steam Boilers and Preventive Measures
Friday, 23 September 2022
Steam Boilers are pivotal in manufacturing and process industries for heating and processing purposes. Although steam boilers are essential in industries, the maintenance of the boiler system is an important and challenging task for plant managers. One of the major steam boiler maintenance issues is boiler leakage. Boiler leakage should never be overlooked as it may lead to hazardous consequences such as corrosion of boiler components. Boiler leakages are found primarily during the winter season. It is because of the steam boiler operating overtime. As the temperature falls below zero, the water in the pipes and inside the steam boiler freezes into ice. Additionally, the condensate pipe removing the remaining steam and condensation from the steam boiler can freeze shut, hindering the steam boiler from functioning properly.
Detecting Boiler Leakages:
Determining boiler leakage helps in understanding the root cause of the leakages. It may be caused due to steam boiler pressure being too high or due to the pressure relief valve. Boiler leakages can be detected by
Causes of Boiler Leakages:
Let us learn some of the common causes of boiler leakages that can lead to the best course of action before causing any severe damage to the steam boiler system,
Pump:
The pump is a vital component of the steam boiler that constantly runs and circulates water in the entire boiler system. Due to its continuous operation, the pump valve or seal can break easily as the rubber seals are hardened or destroyed by elements passing through the steam boiler system.
The repair depends on the extent of damage caused to the pump. One solution involves resealing the pump with a gasket kit, while another solution suggests entirely replacing the boiler pump.
Pipes:
The pipes circulate water throughout the steam boiler system. Therefore, the pipes leading in and out of the steam boilers are possibly the reason for the boiler leakages. It is mostly due to improper installation or the degradation of pipe connection caused by corrosion over time. Both the issue requires the replacement of the component and proper installation.
Pressure Relief Valves:
The pressure relief valve safeguards the steam boiler system from generating excess pressure. During extremely high pressure, the steam boiler releases steam and water. Such situations can result in significant damage, and therefore, it is important to detect and address faulty valves as soon as possible. Pressure relief valves are repaired by removing lime or debris or resealing the valve.
Corrosion:
The rusting and corrosion in the boiler vessel deteriorate the boiler system and lead to water leakage. It is likely that the corrosion detected signifies an outdated steam boiler that needs immediate replacement. On the other hand, it is also possible that the corrosion is caused due to poor water quality.
A feedwater treatment system removes the harmful impurities, contributing to the build-up of scale in the steam boiler as well as the piping and fittings. Scaling in the steam boiler internals, safety equipment, and auxiliary piping indicates poorly treated feedwater.
Thermal Fatigue:
Thermal fatigue is usually caused due to improperly regulating feedwater temperatures and quality, resulting in boiler leakages. It is essential to assess the feedwater and examine if the feedwater temperature is too low as it leads to thermal shock cracking the welds in an area where the hot boiler water is introduced to the low-temperature feedwater. One of the primary issues internally of the steam boiler is the reduction of heat transfer to the components.
As the boiler tubes and tube sheets are the mediums between the hot combustion gases and the boiler water, the scale build-up can significantly reduce the heat transfer rate. It is because the scale acts as an insulator instead of a conductor. The reduction of heat transfer rate leads to overheating of the boiler components, causing metal fatigue and failure. It is mainly found in cases of cracks, ruptures, or complete boiler failure. Overlooking these issues can eventually result in boiler failures.
Preventive Measures for Boiler Leakages:
Short-Term Preventive Measures:
In some of the causes of boiler leakages, a simple fix is enough to avoid the leakages. If the water is leaked due to issues in the pump and pipes, resealing or replacing the part is ideal prevention. It is an easy and immediate fix that helps the steam boiler operate as soon as possible.
Long-Term Preventive Measures:
In certain situations, it is essential to replace the entire steam boiler system if the boiler leakage is caused by rust or corrosion. It indicates that the boiler is outdated and may fail in operating despite any short-term repairs.
Regular Maintenance:
Regular maintenance is the best method to avoid issues like boiler leakages by determining the cause at the initial stage before it can cause any damage to the steam boiler.
Conclusion:
Since our inception in 1983, Rakhoh Boilers have emerged as a leading boiler manufacturer in India and Overseas with 3000+ successful boiler installations in over 26 countries. Our product range includes efficient and reliable industrial steam boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories. We also provide excellent boiler services like energy audit, steam trap assessment, boiler automation, annual boiler maintenance, etc., to ensure the efficiency and productivity of steam boilers.
For more details, visit www.rakhoh.com
- Published in Boiler, Steam Boiler
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Know the History and Evolution of Steam Boilers
Thursday, 22 September 2022
Think about the world without steam. Transportation and communication were difficult, commerce was outdated, and processing industries were unheard of. The invention of the steam engine was an integral part of the industry during the Industrial Revolution. The term steam boiler is used to refer to heat generation. However, it is also applied to any type of equipment that heats water and stores or uses the steam for a specific purpose. The majority of steam boilers are considered high-pressure boilers. Pressure builds as large quantities of steam accumulate inside a contained vessel. When enough steam is produced, the released energy can power the moving parts of a machine.
The history and journey of advanced steam boilers found today go a long way back. Let us understand the evolution of steam usage and boiler manufacturing in the world.
The invention of the First Boiler:
It is said that the first-ever boiler existed as early as the 1st century. However, such boilers were nothing more than toys. Boiler manufacturing officially began in the 17th century as steam power was given importance for potential applications in daily life. The first steam boiler with a safety valve was manufactured in 1679 by France’s Denis Papin.
By the 18th century, steam boilers were used and manufactured in England from wrought iron. However, as the primary advantages of temperature and high pressure came into light, more and more boiler manufacturers turned to steel. The advanced steam boilers were made of alloy steel to withstand extremely high temperatures and pressures.
The History of Steam Boiler Manufacturing:
Looking at the history of steam boiler manufacturers in the USA, the first-ever steam boiler manufacturers were Steven Wilcox and George Babcock, founders of the steam-generating boiler in the U.S. The duo was the first to patent the boiler design that included tubes inside a firebrick-walled structure to generate steam.
A few decades later, in 1891, the two started the Babcock & Wilcox Company in New York. The first boilers of the company utilized lump coal and were relatively small that were fired by hand. Due to these factors, the first patented boilers by Babcock & Wilcox Company operated at an exceptionally less rate of heat input.
Introduction of Bent Tube Boilers:
As advanced technology changed the scenario, 1916 witnessed a new landmark for boilers. It was at this stage when an engineer brought improvement with bent tubes. The bent-tube discovery led to more compact boilers with an ability to handle the cold water feeds that were staples throughout this period.
Evolution of Cast Iron Bar:
As the bent tube boilers gained more popularity, the next improvement was cast iron boilers. Although bent tube boilers and fire tube boilers were ideal for delivering high-pressure steam, they also failed to provide efficient low-pressure steam for heating purposes.
However, the cast iron boiler came to be sufficiently durable for providing low-pressure steam. Although it was difficult to repair and heavy, cast iron boilers were manufactured in various types of shapes, a noteworthy change in the directional history of boilers.
Boilers in Post-War Industrial World:
During World War I and II, the marine boilers were highly dependent on the fuel steam-powered merchant ships and steam-powered combat boats. Marine boilers held an important place during the war years.
The post-war industrial world brought the need for more production from boiler manufacturers. The tube boilers were developed on a high scale. Later, the copper tube boilers gained popularity but presented a unique set of issues that required regular replacements.
Introduction of Condensing Boiler:
After the initial oil crisis in 1973 and environmental concerns in the 80s, boiler manufacturers started planning for more cost-effective solutions to minimize energy consumption in steam boilers due to an increase in energy prices. The solutions included operating boilers at lower water temperature and adjusting the water temperature in the boiler to the temperature outside. At present, condensing boilers offer an extensive range of benefits, such as:
Evolution of New Steam Boiler Design:
By the late 1970s and early 1980s, the growing disposal costs for landfills and increased demand for electric power led to the development of biomass-fired boilers. Steam boilers with fluidized bed technology were manufactured as an alternative method of burning solid fuels like coal. Depending on the boiler manufacturer, a fluidized bed boiler may include cyclones, combustion chambers, over-bed burners, collection hoppers, etc. The fluidized bed boiler involves a process through which solid fuels are suspended in an upward-flowing gas or airstream at the bottom. The burning fuel exists in a fluid-like state with a high heat transfer but reduced emissions.
Conclusion:
If you are looking for an efficient and reliable steam boiler for your process or manufacturing industry, Rakhoh is here to help. Since our inception in 1983, we have merged as the leading boiler manufacturers in the world. Our highly-skilled engineers will listen to your facility requirements and guide you to the best solution.
Learn more about our products and services at www.rakhoh.com
- Published in Boiler, Steam Boiler
Introduction to Mobrey and Its Application in Steam Boilers
Tuesday, 20 September 2022
Steam boilers are imperative for heating, processing, sterilizing, and power generation in manufacturing and process industries. Several factors are considered to ensure the proper functioning of the steam boilers. The water level and water quality play a vital role in hassle-free and safe operations of steam boilers. Water quality is assured by a process like a blowdown or by using water softeners, but water level requires precise management and is controlled by using mobrey. Mobrey is equipment to control the water level in the steam boilers. Let us learn more about mobrey in detail,
What is Mobrey in Steam Boilers?
Mobrey is an automatic boiler water level control included in the category of mountings and fittings in a steam boiler. Mobrey is usually found in smoke tube boilers due to its greater shell diameter compared to water tube boilers, regardless of the running capacity and working pressure of both types of boilers.
Mobrey is placed on the external of the smoke tube boilers, on the nozzles coming out of the boiler shell. It comprises a hollow cylindrical unit that hangs a float. The feed water is provided to the boiler shell by the feed pump to fill the shell. The water enters the hollow cylindrical of the mobrey through nozzles that cause the float to rise upwards.
As the steam boiler operates, the water gets heated and generates steam. As a result, the water in the boiler shell is reduced, leading to the float coming down as well. When the float covers a determined distance, the mobrey passes an electrical signal to the electrical panel that, resultantly, starts the feed pump to balance the water shortage. It causes the float to move up once again after refilling.
The coordination system between mobrey and feed pump is termed Cascade Control System. The Cascade Control System uses the output of the primary controller to influence the output of the secondary controller, as the second controller output is the required one. In this case, the primary controller is mobrey, and the secondary controller is the feed pump.
Components of Mobrey in Steam Boilers:
Modulating controller:
The modulating controller mounted on the steam boiler includes a chamber with a float and float rod attached to an actuator that moves freely up and down inside a steam tube around a mounted inductive coil A. The inductance of this coil varies by the movement of the actuator, changing in water level.
Modulating control valve:
Modulating control valve is placed in the boiler feed water line with an actuator and inductive coil B. The inductance of this coil varies by the movement of the valve spindle. The feedwater flow to the steam boiler is controlled by the modulating valve lid, operated by a piston, actuated by two solenoid valves on the modulating valve. The inlet solenoid valve allows water at feedline pressure to the cylinder and piston, reducing the modulating valve opening. The exhaust solenoid valve releases water from the cylinder and piston to increase the modulating valve opening.
Control box:
The control box includes a circuit board connecting mains input, solenoid valves, sensing coils, and the low-level alarm/burner cut-out functions. The control box identifies any difference in inductance balance between the modulating controller, thereby letting the appropriate solenoid valve to open.
Application of Mobrey in Steam Boilers:
Automatic cold start conditions:
It is utilized for all pumps capable of operating against closed discharge. With an increasing water level in the steam boiler, the modulating valve lid is decided by the capacity of the steam boiler.
Rising water level:
As the float rises, the actuator changes the inductance at coil A the control box detects the change and opens the inlet solenoid valve that allows feed pump pressure onto the piston to move the modulating valve lid downwards, reducing the flow of water into the steam boiler. The modulating valve continues its downward movement until the inductance at coil ‘B’ is in balance with coil ‘A’. The control box closes the inlet solenoid valve to lock the modulating valve in its new position.
Falling water level:
The falling water level is the reverse of the rising water level sequence, with the outlet solenoid valve releasing hydraulic pressure from the piston, causing the modulating valve to open. It results in increasing the flow of water to the steam boiler.
Conclusion:
Mobrey is essential equipment to maintain the water level in the steam boiler to enhance its overall safety in process operation by reducing manual intervention.
Rakhoh Boilers have been consistently contributing to the thermal sector since their inception in 1983. We have manufactured and successfully delivered our efficient and reliable steam boilers, waste heat recovery boilers, thermic fluid heaters, and boiler accessories in over 26 countries worldwide.
Learn more about our products and services at www.rakhoh.com
- Published in Boiler, Steam Boiler
Importance of Welding for Steam Boiler Manufacturing
Friday, 16 September 2022
Industrial steam boilers are irreplaceable in almost every industry throughout the world. The energy holding capacity and safety in using steam is a major cause of steam boilers being an ideal choice for process operations. Therefore, industries consider every factor while selecting a steam boiler manufacturer. The quality of the steam boiler is a crucial aspect in deciding on a boiler company. The precision and utilization of high-tech machinery play a vital role in ensuring the superior quality of steam boilers. A steam boiler is manufactured of three primary components i.e. a cylinder, a base, and a cover. Rakhoh Boilers, as a leading steam boiler manufacturer, ensures that the steam boilers are fabricated with utmost safety and precision with excellent welding.
Welding in Steam Boilers:
Welding is a process involving fabrication that joins materials, usually metals or thermoplastics, through fusion, varying from lower temperature metal-joining techniques like brazing and soldering that do not melt the base metal. Combined with melting the base metal a filler material is usually added to the joint, forming a pool of molten material to cool and form a joint. It is generally stronger than the base material. Pressure may also be used jointly with heat or by itself for producing a weld.
Contrary to brazing and soldering that do not involve the melting of base metal, welding includes a high heating process that melts the base material by usually adding filler material. As a result, the high heat causes a weld pool of molten material. Pressure is also used for producing a weld along with the heat or by itself. It also utilizes a shielding gas for protecting the melted and filler metals from contamination or oxidation. A weld joint in a steam boiler is designed for withstanding the subjected forces during its lifespan. Therefore, the design of the joint is decided by the type and load magnitude on the weld.
The welding process is generally categorized as:
Gas welding: Gas welding includes oxy-acetylene gas welding and hydrogen gas welding.
Arc welding: Arc welding includes metal arc welding (SMAW ), submerged arc welding (SAW ), gas metal arc welding (MIG, MAG), electrode slag metal arc welding, tungsten inert gas welding (TIG), flux-cored arc welding(FCAW ), etc.
Resistance welding: Resistance welding includes percussion welding, seam welding, and spot welding.
Thermit welding: Thermit welding involves producing heat by exothermic chemical reactions.
Solid-state welding: Solid-state welding involves friction welding, forge welding, pressure welding, etc.
Special welding process: Special welding processes include electron beam welding, diffusion welding, plasma arc welding, underwater welding, ultrasonic welding process, etc.
Requirements of Tube Welding in Steam Boilers:
The characteristics of boiler tube welding include,
The strength and consistency of the weld are pivotal considerations in determining the ideal way to weld the pressure vessel tubes as the tubes carry high-pressure steam or liquids in a flowing pattern that can cause a loss in efficiency due to turbulence or distortion.
One of the most crucial aspects of welding boiler tubes is to determine the ideal option between orbital welding and manual welding. Factors like industrial application tube quantity and safety should be the paramount priority. Therefore, manual welding is the least likely option because of the lack of accessibility.
Additionally, the welder must decide the best technique to apply. As gas-shielded welding processes are more consistent than other techniques, MIG and TIG are the ideal alternatives. However, MIG leads to the spattering of filler that negatively impacts the weld quality and bead appearance. On the other hand, TIG uses tungsten electrodes, producing the highest purity welds. Narrow Groove TIG or Thick Wall welding processes are best suited for the thick wall boiler applications found commonly in power plants.
Tungsten Inert Gas Welding with tungsten electrodes results in the highest-quality and consistent welds. Implementing an orbital welding process reduces the lack of accessibility, making it easier for consistency throughout the welding. However, attributes like good heat control, process stability, and fixed position tube welding capability with automated controls should be considered by steam boiler manufacturers for welding machines.
Common Hazards with Welding:
Welding leads to hazardous consequences for both welders and those working in the vicinity. Therefore, it is essential to ensure precautions to prevent accidents and injuries.
Electric Shock:
As a welder touches two metal objects with a voltage difference leads to the electric shock that can cause severe injuries or death. It is further classified as,
Primary shock:
It ranges from 230 to 260 volts that occur by having direct contact with the inside of welding equipment and other grounded metals. Primary shock is extremely hazardous
Secondary shock:
It is the most common type of shock occurring while touching the electrode circuit that ranges from 20 to 100 volts
Prevention for Electric Shock:
Fire Hazards:
Welding sparks spray up to 35 feet and may cause fire hazards, severely impacting the workers with grease on their clothing.
Prevention for fire hazards:
Fumes and Gases:
Welding introduces the personnel to gaseous fumes like ozone, nitrogen, and carbon monoxide that may cause asthma, pneumonia, or cancer.
Prevention for Fumes and Gases:
Physical Hazards:
Various physical hazards are involved in welding activities like burns, cuts, crushed fingers, and eye damage.
Prevention for physical hazards:
Conclusion:
Rakhoh Boilers is a leading steam boiler manufacturer since its inception in 1983. We are a trusted name in over 26 countries for delivering efficient steam boilers, waste heat recovery systems, thermic fluid heaters, boiler accessories, and boiler services of world-class quality.
For more details, visit www.rakhoh.com
- Published in Boiler, Steam Boiler
Importance of Heat Exchanger and Tips to Increase its Efficiency
Thursday, 15 September 2022
Steam boilers are imperative for the operation of the process and manufacturing industries. Steam is vital for heating and processing purposes in industries, and therefore, a steam boiler consists of various components that ensure the steam generation takes place seamlessly. One such component in the boiler system is a heat exchanger. Heat exchangers are long tubes of metal with openings at both ends. It enables the heat transfer from the gas in the burners that produce toxic byproducts when it burns. Heat exchangers are not coils but are usually made from steel sheet metal and enable the gas-to-air exchange.
Importance of Heat Exchangers in Steam Boilers:
In a boiler system, the hot-water radiators harness heat from hot gas jets, but initially, the water needs to absorb the heat energy from the gas. The heat exchanger safely allows the passing of heat energy from gas to the water. If water is heated directly from the gas, the flames would be extinguished by the water. The basic principle of the heat exchanger is that it allows the transferring of the heat without transferring the fluid (liquid or gas) carrying the heat. The surfaces through which heat passes are called heat transfer surfaces. Heat transfer takes place in the steam boiler, where hot gasses from the combustion of fuel transfer levels of intense heat through the steam boiler tubes to produce steam.
The build-up of any hindering material such as scale, corrosion products, or micro-organisms on heat transfer surfaces slows down the heat exchange.
Indications of Issues in Heat Exchangers:
Several indicators point towards issues in heat exchangers and require prompt actions. Some of them are as follows,
Black Soot:
Black soot around the furnace is a clear sign that the gas is not burning properly. Unhealthy and incomplete combustion leads to dirty soot around the furnace. It usually leads to a damaged heat exchanger or an issue with the burner or furnace flame.
Unpleasant Smell:
Although gasses such as carbon monoxide are odorless, any strange or unpleasant odor near the furnace or air ducts requires professional attention. Cracked heat exchangers can leak combustion gasses into the boiler system that can cause a clear and present odor. In such situations, it is crucial to immediately turn off the heating system and seek professional help to diagnose the situation.
Water Surrounding the Furnace:
If water is found on the floor near the furnace, it may indicate a problem with the heat exchanger. Whether it is condensation or a cracked heat exchanger, seek professional help right away to determine the cause.
Outdated System:
If there are complaints of other aging problems with the furnace, such as wear and tear, loud noises, it is ideal to have a professional diagnose the entire steam boiler system.
How to Increase the Efficiency of the Heat Exchanger in Steam Boiler?
The ideal method to reduce the operating expenses in a process plant is by using and maintaining energy-efficient equipment
Reduce carry-over to avoid impurities and ensure proper levels of BTU content at end-use.
Impact of poor heat transfer in the steam boiler:
Conclusion:
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
- Published in Boiler, Steam Boiler