Energy Audit Services and Its Benefits
Steam Boilers are integral in process plants and manufacturing units. Several process operations rely heavily on efficient steam boilers for processing, drying, and sterilizing purposes. Plant managers take every measure to ensure the smooth functioning of steam boilers and the safety of the process plant and operating personnel. Regular maintenance inspects the wear and tear in steam boilers and prevents it before it leads to mishaps. However, one of the main concerns of most plant managers is the increased use of natural resources for the combustion process in steam boilers. It consequently results in higher demand for energy, adding to the expense of the manufacturing facilities.
Energy Audit in Industries:
Energy audits aid industries or manufacturing facilities in assessing energy utilization and identify the areas that lead to the high amount of energy waste and measures to improve it. The energy auditor directs the audit by coordinating with the plant managers and operating staff to ensure precision in data and proper execution of the suggestions.
With the increasing cost of energy, the industries might face considerable losses if they make changes on guesswork without proper auditing. Energy audit assists the industries in evaluating energy wastage and suggests measures to reduce energy consumption. Energy Audits usually take place in 3 stages:
Investigation Phase:
- Energy consumption since last 1 to 2 years
- Energy supply contracts and tariffs
- Floor area, number of staff members, production levels
- Benchmark level of energy use and cost
- Metering equipment
- Plant configuration
- Electricity configuration, condition, and controls
- Energy management process and policy
- Assessment management plan, if any
Monitoring Phase:
- Gas load profiles
- Internal temperature or humidity
- Ventilation rate
- Analysis of boiler flue combustion
Analysis and Reporting Phase:
- Finding complete energy efficiency
- Assessing Greenhouse Emission Index
- Analysis of life cycle cost
- Analysis of tariffs
Energy Audit for Efficiency Improvement in Steam Boilers:
Steam boiler systems with optimal efficiency lead to high production and eventually high profits for the manufacturing unit. Improving the boiler efficiency and capturing excess heat results in saving energy. Energy assessment of the steam boiler system includes the following factors:
Demand and Size of Boilers:
The heating demands during process operations may change in steam boilers, resulting in systems functioning below their optimum efficiency. Boilers are oversized due to factors such as unrequired additions and expansions. It results in boiler ‘short cycling,’ which occurs when the boiler quickly completes the process operation or heating demands and shuts down until the next process cycle. In such cases, a smaller size boiler that meets the required load demands of the facilities is ideal for saving energy.
Boiler Allocation:
Process facilities using multiple boilers can save energy by implementing boiler allocation strategies by operating it simultaneously under low-fire conditions. Such practice maximizes efficiency and reduces energy costs. Hot water boiler efficiency is also improved, by using automatic flow valves that shut off the boiler when not in use. It prevents the hot water from getting cool.
Flue Shut-off Dampers:
Heat loss to the chimney occurs significantly if the boilers shut down regularly because of load changes. Fully closing stack dampers help in preventing the loss of hot air. It functions when the boiler is not in operation.
Maintenance:
Negligence in the regular maintenance schedule can negatively impact the burners and condensate return system in steam boilers. Such factors can account for up to 20% to 30% of boiler efficiency over the 2-3 years. A timely maintenance program ensures optimal performance of all the boiler components, resulting in significant savings and reducing air pollutant emissions.
Reduction in Fouling:
It is essential to control the fouling of the fireside of boiler tubes and scaling of the waterside of boiler tubes. A soot layer of 0.03 inches can reduce the heat transfer by 9.5%, and 0.18 inches of layer reduces it by 69%. Scale buildup of 0.04 inches in water-tube boilers can increase fuel consumption by 2% and even result in boiler tube failures. Boilers burning solid fuels like coal have a higher tendency of fouling compared to liquid or gaseous fuels.
Blowdown Rate:
Improper blowdown causes boiler water carryover to the steam or deposit formation and exceeding the range results in waste of energy, water, and chemicals. The blowdown rate depends on various factors such as boiler design, operating pressure, makeup water quality, and water treatment. Depending on the feedwater flow rate, the blowdown rate can range from 4% to 8%. Reducing the blowdown rate can decrease the energy loss, makeup water, and chemical treatment costs.
Reducing Excess Air:
Excess air used in burning the fuel causes wastage of heat while heating the air. Lack of maintenance in boilers consists of up to 140% of excess air resulting in waste gas. Boiler efficiency is increased by 1% for reducing 15% of excess air. It is necessary to inspect the fuel-air ratios regularly.
Preheating Boiler Water with Economizer:
Boiler feedwater can be heated by flue gases through an economizer which increases the water temperature in the boiler inlet. It consequently reduces the amount of heat needed for steam generation, thus saving fuels. Economizers can reduce the fuel requirement by 5 % to 10% by recovering waste heat.
Condensate and Heat Recovery:
Installation of condensing economizer can improve the overall heat recovery and bring about 10% steam boiler efficiency. Up to 80% of heat released through blowdown is recoverable using flash vessels and heat exchangers.
Combined Heat and Power:
Combined Heat and Power (CHP) or Cogeneration produces two forms of energy by using a single fuel source. The fuel energy is converted into mechanical and thermal energy. Thermal energy generates steam, hot air, and hot water, whereas mechanical energy produces electricity.
Benefits of Energy Audit:
- Reduces energy costs
- Reduces dependence on procuring energy sources externally
- Reduces environmental damage
- Reduces consumption of natural resources
- Reduce greenhouse emission
- Optimal performance of boiler components
Rakhoh Boilers has been a trusted name in boiler manufacturing and service providers for more than 38 years. We manufacture a range of efficient and reliable steam boilers and provide boiler-related services like energy audit, boiler automation, steam trap assessment, annual boiler maintenance, etc.
Explore our products and services at www.rakhoh.com
- Published in Boiler
Importance and Advantages of Insulation in Steam Boilers
Steam boilers are a vital asset of the process and manufacturing industries globally. Plant managers take every measure to ensure that the boilers are well-functioned and deliver optimal results by following standard guidelines, regular maintenance, and steps to increase the efficiency of the steam boiler. One of the ways to ensure the optimum output of the steam boilers is proper insulation. Insulation is necessary for the safety of the process plant and energy efficiency. Poor boiler insulation is worse than a boiler without insulation. Therefore, it is paramount to assure proper insulation in steam boilers for effective results.
What is Insulation in Steam Boilers?
In simple terms, insulation helps a steam boiler in storing its thermal energy. Similar to the way a woolen garment retains heat in the body during the winter season. Boiler insulation is used to keep steam boilers and their pressure vessel units hot, prevent radiant heat loss and provide safety and protection to the processing unit and operating team. Proper insulation prevents the surface temperature of steam boiler doors and covers to exceed the required degrees of Fahrenheit. It results in causing danger to the operating personnel working in the vicinity of the boiler surface. It is advisable to insulate any surface that exceeds the temperature by 120°F. Boiler insulation includes insulating,
- Steam Boiler Doors
- Steam Drums Covers
- Steam Boiler Piping
Boiler piping insulation is important for its operation. However, it is often overlooked and may lead to significant heat loss. Proper insulation in team boilers results in energy conservation, plant and employee safety, and acceleration in efficiency for process operations.
Importance of Insulation in Steam Boilers:
Combustion in the furnace and the flue gases in the boiler shell tube heat the surface area that leads to steam generation or heating of water. Partial of the energy gets conducted away to the boiler shell surface.
As the steam boiler shell begins heating, it passes the heat to the surroundings to produce steam or heating water. Poor insulation causes loss of heat, resultantly reducing the efficiency of the steam boiler. Such situations are severe in rainy and winter seasons when the heat requirements increase significantly.
Therefore, both the water tube boiler and fire tube boiler must be properly insulated to prevent major heat losses. It has been found that in steam boilers, a loss of 20 to 22 degrees Celsius leads to a reduction of 1% of boiler efficiency.
Advantages of Boiler Insulation:
Considerable heat loss can lead to several issues, such as high expenses and a dangerous work environment. Proper boiler insulation prevents such significant loss and provides extensive benefits like,
Increased Efficiency:
As the steam boiler loses a significant amount of heat, it is required to operate intensively to attain the desired heat level to generate steam or hot water. Proper boiler insulation ensures that the heat is retained for easy and rapid heating of the boiler system. It leads to saving both time and money.
Saves Energy:
Proper boiler insulation can raise the temperature by 2° F to 4° F compared to steam boilers without or with poor insulation. Consequently, it can save up to 3% to 4% energy annually.
Safety and Reliability:
Proper boiler insulation ensures the safety of the process plant and the operating personnel. If boiler pipes are not insulated properly, it becomes excessively hot. Personnel operating near the vicinity of such structures are prone to get injured or burned due to excessively heated surfaces. It may also cause damage to the property of the processing unit.
Saves Expenditure:
Significant loss of heat leads to high expenditure. If steam boilers are left with poor insulation as they pass heated fluid, it requires additional energy to perform at an optimal level. Boiler insulation prevents thermal loss and thereby reducing loss of energy and expense.
Types of Boiler Insulation:
It is prudent to consider the type of insulation best suited for a steam boiler. There are two types of boiler insulation primarily preferred,
Removable Insulation:
As the name suggests, removable insulation can be removed easily and is ideal for steam boiler systems that frequent inspection and maintenance. It is easy to install and remove to access the component. It significantly reduces energy and heat loss without requiring any permanent fixture. The harness of the removable insulation is made from numerous materials including, snaps, straps, Velcro, and springs.
Permanent Insulation:
Permanent insulation is commonly found in boiler systems that do not require regular access to its components. Permanent insulation is sturdy and long-lasting that permanently encloses the surface that needs to be insulated. It is ideal for plants requiring long-term insulation without frequent inspection and maintenance.
Factors to Consider in Choosing Boiler Insulation:
Various factors should be considered while choosing boiler insulation, such as,
- The maximum temperature reached by the insulated component
- Potential exposure to the components
- Ambient temperatures
- Heat Retention Capacity
- Frequency of Insulation Removal
- Safety Requirements
- Space Availability
Since its inception in 1983, Rakhoh Boilers have strived to deliver efficient industrial steam boilers and thermal solutions to the clients. We are reputed to be a trusted name as a boiler manufacturer in over 26 countries worldwide. Over our journey of more than 38 years, we have provided efficient industrial boilers, waste heat recovery systems, boiler accessories, and boiler services to over 20 process industries.
Learn more about our products and services at www.rakhoh.com
- Published in Boiler
A Guide to Select Ideal Steam Boiler for Process Plants
Steam Boilers are the heart and soul of the process and manufacturing industries globally. Boiler manufacturers are working consistently with their research and development department for advancement in thermal engineering by introducing steam boilers with enhanced design, offering efficient and sustainable performance. With the emergence of reputed boiler manufacturers, process industries consider every factor before deciding on a steam boiler for their facility. Rakhoh Boilers, as a leading boiler manufacturer in India, ensures to deliver excellent steam boilers to their clients that are efficient and reliable in process operations. As a staunch supporter of advancement in thermal solutions, Rakhoh boilers have listed some important factors that process plant managers must consider before choosing a steam boiler.
Importance of Steam Boiler Selection:
Steam boiler selection plays a crucial role in increasing the overall efficiency of a processing plant. When choosing an industrial steam boiler, it is necessary to consider the specific requirements of the process operation. Compared to the fuel cost, the initial capital cost on the steam boiler is merely 15 % or less in the life span of the steam boiler.
The two most commonly used boiler types in process plants are firetube boilers and water tube boilers. Although firetube boilers are less expensive and operate easily, it includes a relatively small steam capacity. On the other hand, water tube boilers efficiently produce high-pressure steam and are usually preferred in applications requiring higher capacity.
However, other considerations should be accounted for while selecting the appropriate steam boiler and boiler manufacturer for your process plant requirements. These factors include:
- Boiler Design / Type:
Firetube boilers and water tube boilers are the two primary types of steam boilers used in process plants. Firetube boilers pass hot gas from a heat source through tubes placed in a water-filled shell that converts the water into steam. Firetube boilers require a low capital cost and are usually easily operated. However, they come with relatively small steam capacities.
On the other hand, water tube boilers pass water through the tubes heated by hot gases in the boiler shell. Although it consists of higher thermal efficiency as compared to firetube boilers, it is more expensive. Water tube boilers are generally used to produce high-pressure steam and are majorly found in applications requiring high capacities.
- Fuel/Heat Source:
The fuel type for generating heat is also an important factor to consider for selecting a steam boiler. Some of the primary fuel types used in steam boilers include:
Coal:
Coal-fired boilers are usually known for higher emissions, requiring expensive scrubbers and electrostatic precipitators for the removal of harmful gases and fly ash from flue gas.
Natural gas:
Gas-fired boilers are ideal for natural gas fuel that is cleaner than other energy sources, is highly combustible, and has a high energy-to-heat ratio. It also ensures relative safety for storage purposes and provides certain environmental benefits over other fuel sources.
Biomass:
Biomass-fired boilers are used primarily in the sugar, paper, and distillery industries as it uses the by-products of the operational processes as fuel and is significantly economical in process plants with biomass fuel available readily and cost-effectively.
- Proper Combustion:
Steam boilers offering combustion with coal, biomass, or petrochemical fuel uses different combustion technologies. For example, stoker uniformly spreads the coal through the burner on a moving grate. On the other hand, fluidized bed technology includes air bubbles through a bed of pulverized coal or biomass that provides oxygen for combustion. These technologies impact thermal efficiency. Therefore, steam boiler selection should consider proper combustion along with the capital and operating costs.
- Safety:
High pressures and temperatures can contribute to hazardous accidents in steam boilers. It is also advisable by boiler manufacturers to approach and operate low-pressure steam boilers with caution. While selecting a steam boiler, decide on the safest option that meets the requirements of the process plants. It is also vital to understand the maintenance required for the safe operation of the chosen steam boiler.
- Reliability:
Reliability is one of the most crucial factors as the process operations depend tremendously on a steam boiler. It is important to assess the water quality as it has a significant impact on the performance of the steam boiler. Water softeners, demineralizers, or reverse osmosis systems are the best methods to improve feed water quality.
- Cost:
It is natural for the process plants to consider the cost of the steam boiler as a priority of their purchase criteria. Although cost is important, while considering variables like run hours and fuel costs, it is challenging to know the precise cost of the steam boiler. Simply put, a cheap boiler is likely to cost more expenses down the road.
- Life Span Expenses:
Calculating and assessing the expenses of life span economics is an important consideration. Finding the minimal life cycle cost includes factors, such as initial cost, operating schedules, estimated steam boiler life, overall boiler efficiency, warranty, annual operating expenses for parts, and blowdown requirements.
- Performance of Steam Boilers:
Steam boiler applications may require additional performance with heat or pressure that is lost at a significant expense if the steam boiler fails. High-performance steam boilers provide consistent and dependable operation for these applications.
About Rakhoh Boilers:
Rakhoh Boilers has been a trusted boiler manufacturer since 1983, delivering a range of efficient and reliable steam boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories. We provide excellent boiler services to ensure optimal efficiency and productivity of the steam boilers to your clientele, spread over 26 countries worldwide.
For more information on our products and services, visit www.rakhoh.com
- Published in Boiler
An Overview of Scaling and Corrosion in Boiler Water
One of the most important factors ensuring the proper functioning of steam boilers is boiler water quality. As the steam is generated through the fuel combustion and heating of water, boiler water quality plays an integral role in steam production. Steam boiler receives the boiler water as a combination of freshwater, such as ground or surface water, purified with a water treatment system, and condensed water that is returned from the process of steam boiler. Both types of water consist of impurities that impact the efficiency of the steam boiler. Therefore, it is necessary to determine the impurities present in these streams for a proper feedwater treatment system.
Causes of Scaling in Steam Boilers:
Scaling in a steam boiler is caused by deposits formed on the internals of piping and heat transfer surfaces as the water is heated and impurities precipitate. The deposits later build up and hinder heat transfer or, in severe situations, cause failure of the tube and steam boiler system. Boiler water includes suspended solids such as silica in it. When boiler water containing silica is heated for steam generation, it leads to forming extremely hard deposits on the internals of the steam boiler on heat transfer surfaces.
The primary boiler water contaminants causing scaling in the steam boiler are:
- Silica
- Calcium
- Aluminum
- Iron
- Magnesium
The intensity of scaling in the steam boiler depends on the amount of the impurities as well as the pressure of the operating steam boiler. High-pressure boilers require a higher quality of boiler water containing lesser impurities compared to lower pressure boilers.
Causes of Corrosion in Steam Boilers:
Corrosion in steam boilers is the breakdown of the metal components that are caused due to various reasons. One of the primary reasons is the dissolved oxygen and carbon dioxide presence that destroys the areas of the steam boiler and causes stress and cracking in the steam boiler system.
Corrosion usually takes place in the most heated parts of the steam boiler that leads to high temperatures, and cracking of the metals increases the breakdown of the materials. It is essential to note that different metals and materials in the steam boiler react differently with the gases and contaminants present, resultantly causing corrosion.
Various types of corrosion that take place in a steam boiler include:
- Galvanic corrosion
- Acidic corrosion
- Caustic corrosion
- Oxygen attack
- Carbon dioxide attack
- Hydrogen embrittlement
Types of corrosion depend on the appropriate pH, oxygen level, amount of solids, and steam boiler design.
Preventing Scaling and Corrosion in Steam Boiler:
- Determining the impurities in boiler water:
As mentioned, boiler water includes two types of water used for steam generation. It consists of fresh water derived from the plant and condensed water returned from the operational process of the steam boiler. Both water types have their share of impurities that will impact the efficiency of the steam boiler.
- Examining unique chemistry of boiler water:
Plant managers follow general guidelines provided by the boiler manufacturer for the steam boiler, depending on its operational pressure. It is advisable to refer to these guidelines while planning a boiler water treatment plan.
- Assessing if the steam boiler is at risk:
High-pressure steam boilers need higher quality boiler water with minimal contaminants present. Therefore, a boiler water treatment program must be performed to prevent the formation of scale and corrosion in steam boilers.
- Regular boiler water treatment program:
Regular and proper pre-treatment for the boiler water manages the internal chemistry of the steam boiler and handles return line corrosion, which is crucial to prevent and control the scale formation and corrosion in steam boilers.
Working of Boiler Water Treatment:
Effective boiler water treatment involves the utilization of chemicals to eliminate corrosive substances, balancing pH levels, and managing the conductivity of boiler water.
Boiler water treatment chemicals are injected into the feedwater at predetermined points for removing the substances that cause corrosion and scaling. These boiler water treatment chemicals include:
- Oxygen Scavengers:
Oxygen scavengers include sulfite that effectively removes the oxygen that remains after the passing of water through the deaerator as oxygen is a catalyst for corrosion.
- Scale Inhibitors:
Scale inhibitors involve introducing phosphates to the boiler water stream to bind the calcium ions and managing them from binding to metal parts that cause scale formation in steam boilers.
Solution for Scaling and Corrosion in Steam Boilers:
Without the proper material, the chemical treatment of boiler water impacts the flow rate, strength, and pressure of the steam boiler systems because:
- A high amount of sulfites are corrosive to various common types of metallic materials.
- Acid phosphate solutions can be corrosive to metallic feed systems with orthophosphate treatments producing deposits in the feed line.
Rakhoh Boilers have been proficient in steam boiler manufacturing and thermal solution since their inception in 1983. We manufacture a range of efficient steam boilers, waste heat recovery boilers, thermic fluid heaters, and boiler accessories. To ensure high efficiency and performance of the steam boiler, we provide excellent boiler services like steam trap assessment, boiler automation, fuel conversion, energy audit, annual boiler maintenance, etc.
Learn more about our products and services by visiting www.rakhoh.com
- Published in Boiler
An Overview of Air Venting in Steam Boilers
Steam Boilers are the backbone for processing operations in industries. Steam in boilers is generated by the combustion of fuel that heats the water for steam production. The operating personnel in process plants take every measure to ensure that the steam boiler is operating safely, without any hindrance. However, some boiler issues are inevitable that require immediate action once detected. Air vent is one of such issues of steam boilers. When air is mixed with steam by flowing with it, the air pockets remain at the heat exchange surfaces. The steam condenses, leading to a thin layer building up and forming an insulating blanket, resultantly hindering heat transfer.
What is Air Vent in Steam Boilers?
Air is usually used in the steam boiler as an insulator due to its low conductivity. Air is also used for reducing the heat loss from steam pipes. In most cases, the insulating material consists of microscopic air cells. The air is found in the insulator while the solid material retains its position. The film of air on the steam side of a heat transfer surface shows resistance to the heat flow, reducing the heat transfer rate. With the addition of air to the steam, the heat content of the mixture is less than the same volume of pure steam. Therefore, the mix temperature is reduced.
The air present in the steam boiler has a dual impact:
- It is resistive to heat transfer through its layering effect.
- It reduces the steam space temperature, leading to reducing the temperature gradient throughout the heat transfer surface.
Why is Air Vent Important in Steam Boilers?
During the shutdown in steam boilers, the steam and condensate are eliminated from the steam boiler system, causing the space inside to be occupied by air. A minimal amount of air and other condensable gases enters the boiler with the steam. In the next operational cycle, air and non-condensable gases should be eliminated from the steam boiler, as it causes severe impacts on process operations and equipment like more warm-up times and reduced efficiency and performance. Therefore, an air-vent is essential to remove the air trapped in the process equipment.
Effects of Improper Air Vent in Steam Boiler:
- Reduction in heat transfer rates and productivity:
Air is highly resistant to heat transfer than the metal wall. Compared to iron or steel, air shows more than 1500 times resistance to heat transfer and around 13000 times more resistance than copper. Therefore, a 0.5 mm film of air offers the same amount of resistance to heat transfer that a 6.5 m copper would.
- Malfunctioning of traps:
Air in the condensate tremendously impacts the performance of traps. The condensate removal capacity of steam traps depends on the air and other non-condensable gases present in the condensate that can cause waterlogging if overlooked. It impacts the time required for process operations and product quality. Traps with air venting are ideal than other traps to avoid any issues in the steam boiler.
- Increased corrosion:
As air includes gases like oxygen and carbon dioxide that cause the corrosion of the metal walls and equipment, air can lead to high corrosion in the steam boiler. When carbon dioxide dissolves in water, it forms carbonic acid that is highly corrosive. Corrosion in steam boilers may remain undetected, causing a sudden, unexpected failure.
- Reduction in steam pressure:
The pressure applied by gas or a mixture of gases is determined with Dalton’s law of partial pressure. The law states that the total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the individual gases in the mixture.
Therefore, the actual steam pressure is less than the pressure displayed on the gauge. With the air inside the steam, the actual pressure is less than that displayed in the gauge. Consequently, the temperature of the steam boiler will be less than required for the process operation. The lack of an optimal amount of pressure leads to a longer duration of process operation.
Signs of Air in Steam Boilers:
It is paramount to eliminate air from the steam boiler. Some indicators for the presence of air in steam boilers are as follows,
- A drop in the output of the steam boiler
- Condensate with air bubbles.
- Corrosion in the steam boiler.
Air Removal from Steam Boilers:
- Device for Air Vent:
Automatic devices are the most effective method of air removal. With the blend of air with steam reducing the mix temperature, it facilitates the thermostatic device to vent the steam boiler. An air vent installed on the steam space of a vessel or at the end of a steam main opens with air present. In order to carry the discharge and prevent it from entering a condensate return line that restricts the free release of air and causes corrosion, steam boilers are fitted with pipes.
As an air vent is fitted to a steam trap, it acts as a steam trap after the air vent, and discharges condensate. Therefore, it is necessary to reinstall the air vent to the condensate line after the trap.
- The placement of Air Vent:
A coil or a vessel with a relatively small cross-section leads to steam acting as a piston by pushing the air to a remote point from the steam inlet. The remote point is the ideal placement for the air vent.
Conclusion:
Rakhoh Boilers are the leading manufacturers of steam boilers in Pune with over 38+ years of expertise in providing efficient and reliable steam boilers and thermal solutions. Our global network is spread across 26 countries worldwide with more than 3000 successful boiler installations.
For more details on our products and services, visit www.rakhoh.com
- Published in Boiler