15 Boiler Spare Parts to Ensure Optimal Operation of Steam Boilers
Steam Boilers are undeniably one of the most important assets for the manufacturing processing operation in several industries. However, it is also an acknowledged fact that if not handled properly, steam boilers have the potential of an explosive bomb. Several guidelines are followed during boiler operations and boiler manufacturers ensure that the steam boilers are equipped with safety devices. Yet, it is prudent to take every precaution rather than risking a boiler failure or explosion. Boiler spare parts are the solution to ensure extra safety and seamless operation of steam boilers.
Here are 15 spare parts that should be present in every process plant.
- Auxiliary and Primary Low Water Cut-Off Switches:
Auxiliary and Primary Low Water Cut-Off Switches are vital to identify low water conditions in the boiler. It also ensures that a master fuel trip shut the burner off during such situations. On average, Low Water Cutoffs have a lifespan of ten years, provided that it is cleaned thoroughly on an annual basis. If maintenance is overlooked, low water devices require sooner replacement, and their reliability is reduced during operations. These level switches are essential to run the steam boiler safely.
- Pressure Control Device:
Pressure Control Device is a part of a PLC-based controller in large systems, whereas it is an independent pressure controller in smaller systems. The absence of such a pressure controller means that the operator assesses the boiler pressure gauge and manually adjusts the boiler firing rate to maintain system pressure without tripping the boiler or lifting the safety valves. It is a difficult task and not a reliable method of pressure control with precision. Therefore, a spare part like a pressure control device can enhance the safety of the steam boiler operation.
- Flame Detector:
A flame detector is an important boiler spare part that prevents the steam boilers from filling with raw fuel during the absence of flame. Several technologies are used in flame detection. In the case of industrial steam boilers, it is usually a flame scanner. Due to the sensitive nature of such devices, it is necessary to have boiler spare parts at hand for any emergency.
- High Pressure / High-Temperature Cutout Switch:
It is a simple pressure switch used for steam boilers. Combustion safety codes include this safety switch for every installation. Therefore, it is vital to install this relatively inexpensive part to avoid production loss.
- Safety Relief Valves:
Safety valve springs are damaged in a short period, causing venting of the valve even when pressure is not at a set point. The codes expect an annual inspection of safety relief valves. Therefore, it is advisable to have a boiler spare part in case of replacement during operation.
- Fuel Safety Shutoff Valves:
Fuel Safety Shutoff Valves ensure that the fuel does not leak into the steam boiler when it is off and prevent it from filling with fuel that can cause an explosion or runaway boiler fire. It is essential to have extra boiler spare parts for large valves to prevent requiring a full assembly. Although the valves can be repaired, in rare cases when they cannot, they can lead to steam boiler failure.
- Water Level Device:
Feedwater control setups in steam boilers use different technologies and devices to control the water level. Operating a steam boiler without feedwater controls needs a full-time operator to adjust a manual valve. However, it does not make sense to have operators standing around with nothing to do. Therefore, it is essential to have boiler spare parts and a loop control device if something fails.
- High And Low Gas Pressure Switches:
High and Low Gas Pressure Switches are vital to ensure that the steam boiler is not receiving excessive or too little gas. The absence of these switches can result in steam boilers being too lean or rich and cause major damage or an explosion. Therefore, a spare must be kept installed by a qualified technician.
- Gas Regulator:
Gas Regulators are probably the most overlooked boiler spare part in many process plants. But, it is important to have an extra on hand. It is also essential to inspect the regulator vent lines.
- Igniter Parts:
Lighting an oily rag on a stick is an outdated method of combustion in a steam boiler. Therefore, having a spare igniter is a good decision to ensure hassle-free combustion.
- Combustion Air Switch:
A combustion air switch stops a burner from opening the fuel valves in the absence of airflow. As the flow switch can prevent your steam boiler in its tracks, it is ideal to have a spare of it.
- Gaskets:
Gaskets are frequently replaced and made of different materials that depend on if they reside on the fireside or water side of the steam boiler. It is usually replaced every 12 months or during any inspections of the steam boiler. Since it is replaced so frequently, it is ideal to carry replacement or spare gaskets. It also shortens downtime in case of a leak.
- Valve Packing Sets:
Steam boilers can operate even if the packing on a few valves is leaking, and tightening the snot out of the stem packing can stop the small leaks. However, valves do not function properly with over-tightened packing. Therefore, it is advisable to keep a spare packing set for all control valves. If a leak is unable to stop by snugging up the packing gland, it can be changed with the packing set out.
- Boiler Level Sight Glass:
It aids in identifying the correct amount of water in the steam boiler. Even a slight leak from the boiler sight glass or packing will impact the water level reading, resulting in unsafe operating conditions. It is crucial that the sight glass is clear and clean, and does not leak. If the sight glass becomes hard to read and is dirty, then it should be replaced. By having this boiler spare part, it can be changed easily should an issue arise.
- Observation Port Glass and Packing:
Process plants need to examine the flame during the operations. However, the observation port glass is often filthy, sooty, broken, leaking, extremely hot, or all of the above. Therefore, it is sensible to have a spare of it ready for such situations.
Conclusion:
Rakhoh Boilers is a leading boiler manufacturer in Pune since 1983. We manufacture a range of efficient steam boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories and provide excellent boiler services like steam trap assessment, boiler automation, energy audit, annual boiler maintenance, etc.
To learn more, visit www.rakhoh.com
- Published in Boiler
Types, Design, and Advantages of Bag Filters in Steam Boilers
Process industries release a substantial emission that leads to ever-increasing air pollution, water pollution, and causes harm to the climate. It is imperative to monitor the pollutants with the aid of pollution control equipment. Industrial pollution is a serious concern faced worldwide that affects the environment and health of people living nearby to process plants. It has been found that those living near the source of pollution are at 20% more risk of death from lung cancer. Disposing of industrial waste in water causes the death of around 1 million seabirds and 100,000 sea mammals every year. Bag filter is one of the pollution control equipment that helps in controlling the wastes from industries.
What are Bag Filters?
Bag Filters are pollution control equipment, primarily used with steam boiler facilities to control the hazardous pollutants released during process operations such as sulfur dioxide and various others. Bag filters are effective and efficient for the filtration of flue gases by separating the particles and collecting them at their bottom. The flue gas is passed through the outlet while the hazardous particulates are disposed of. The bag filters are ideal for resisting high temperatures with a range of gas flow rates.
Types of Bag Filters:
There are three types of bag filters commonly found in process industries:
Pulse Jet Type:
Pulse jets are the most preferred bag filters in process industries, designed to ensure low-pressure drop and ease of installation and maintenance with components like cages, tube sheets, and venturies. It assures complete gas tightness across the tube sheet that prevents polluted gases ingression into clean air. It is designed with an optimal air-to-cloth ratio as per its process requirements. Pulse jet type bag filters are primarily used in process industries such as cement, power, steel, etc.
Reverse Air Bag:
The Reverse Air Bag is ideal for handling high-temperature gases in large volumes. It can facilitate the emission level of 20 to 50 mg/ nm3. The PLC control panel ensures its cleaning operations, optimum pressure drop, and longer lifespan of the baghouse. The hook assembly and springs at the top help in the suspension of filter bags and appropriate tensioning. The complete gas tightness is ensured by casing, hopper, and tube sheet that prevents ingression of polluted gases to clean airside. The design of the reverse airbag includes balanced gas distribution of the inlet and outlet plenums that ensures uniform distribution of gases.
Mechanical Shakers:
The mechanical shaker bag filters are designed by attaching tubular filter bags on a cell plate at the bottom and suspending it from the horizontal beams at the top. The polluted gases enter from the bottom and pass through the filter. On the other hand, the pollutants get collected on the internal surface of the bags. Mechanical shaker filter bags have high space requirements due to relatively low air-to-cloth ratio. It is widely used in mineral processing industries.
Design of the Bag Filter:
Filter bags are made of filter cloth and are cylindrical or round in shape. The filter bag fabric must be as per the requirements of the process operations of the industries and the dust and chemical characteristics.
The design of the bag filter consists of the upper part and the lower part. The lower part can be opened or closed as required, while the upper part is open with elements for fixing, such as metal fastening rings, springs, and various others. The seam connecting both ends needs considerable attention to ensure that the bag filter handles the load.
The primary component of the bag filter is the filtering sleeves that must be of quality material to withstand the chemical properties of the pollutants released from the process operations of steam boilers. Filtering sleeves often wear out and require regular replacement.
Cleaning the Bag Filter:
As the bag filters aid the processing industries with the emission released from steam boilers, they must be cleaned and maintained regularly. Bag filters are cleaned in the following ways:
Reverse Push of Air: The method utilizes continuous low-pressure air flows to remove the solids collected in the cell
Pulse Regeneration: The pulse regeneration method removes the solid particles through a compressed stream of air at high pressure
Mechanical shaking or vibration for the removal of the dust particles
Advantages of Bag Filter:
- Highly tolerant with a wide range of temperature
- Filtration of various sized particles
- High dirt holding capacity
- Hassle-free process operations
- Easy to install and maintain
- Long life cycle
Rakhoh Boilers, being one of the leading steam boiler manufacturers, deliver highly efficient and reliable steam boilers and boiler services to their extensive clientele. We manufacture boiler accessories and pollution control equipment of world-class quality to enhance productivity and efficiency in the process industries.
Know more about us at www.rakhoh.com
- Published in Boiler
Deposition and Fuel Ash Corrosion in Steam Boilers
Fuels are integral for combustion in steam boilers. Except for natural gas, almost every type of fuel consists of impurities that cause corrosion and deposition on the fireside of the boiler components. Compounds of sulfur, sodium, chlorine, etc., lead to severe damage due to corrosion of boiler metal. Fireside corrosion takes place in three primary temperature regimes. Dew-point corrosion occurs below 300oF when sulphuric acid condenses. Water-wall corrosion takes place between 500oF and 750oF in coal-fired boiler systems due to the formation of pyrosulfates of sodium and potassium. Temperature exceeding 1000oF causes corrosion in superheaters. The corrosive component varies for coal-fired and oil-fired steam boilers.
Ash Corrosion and Deposition:
Ash passing through the boiler is blended with several chemical reactions, causing ash deposition on boiler surfaces. The corrosion mechanisms are similar for both coal-fired boilers and oil-fired boilers. The constituents of the ash are from a mixture of various compounds with a low melting point. It can damage the protective layer of iron oxide in boilers. It results in oxygen coming in contact with the bare metal of the steam boiler.
Ash deposition is mainly categorized as slagging and fouling. Slagging refers to molten, partially fused deposits on the furnace walls and the other surfaces in contact with radiant heat. Slagging also occurs in the convective surface if flue gas temperature is not reduced. Fouling is formed by high-temperature deposits on surfaces that absorb convection heat like superheaters. The compounds condense on ash particles and heat surface as heat is absorbed and temperature reduces. It results in the formation of a layer that helps in deposition.
Source of Fireside Deposition:
In oil-fired boilers, oil containing more than 0.05% of ash is termed high ash oil, whereas oil with less than 0.02% ash is termed low ash oil. Combustion of high ash oil leads to deposition on convection surfaces of boilers such as superheat, reheat, and components of the economizer. Oil ashes containing vanadium causes severe damage as it reacts with oxygen to form various oxides. Similarly, sodium reacting with oxygen produces fouling compounds.
Combustion of solid fuels like coal can lead to fireside slagging. Solid fuels consist of sodium, calcium, silica, sulfur, and iron, along with metal oxides such as alumina, potassium oxide, and titania that encourage slagging. Metal oxides such as alumina, potassium oxide, and titania can also form slagging. Proper boiler furnace design, operational methods, and chemical treatments are factors that can aid in preventing fireside deposition.
Factors Affecting Deposition in Steam Boilers:
Apart from ash characteristics and boiler design, several other factors impact the deposition in steam boilers such as,
Air Distribution:
An imbalance between air and fuel in the ducts and coal piping system results in excess air at some burners and low air at others. It may cause localized reducing conditions that lead to increased slagging. A high coal-air ratio causes a long time in combustion that allows the burning particles to contact the furnace walls and other heat transfer surfaces. It must be ensured that burner adjustment resulting in a flame impact on furnace walls is avoided.
Fuel Distribution:
Fuel should be distributed evenly and uniformly to each burner to ensure there is no excess or low fuel in some burners. It would cause a disturbance in combustion.
Fuel Density:
Fuel with higher density causes a delay in combustion as coarse particles require high residence time for burnout. It leads to slagging in the lower furnace.
Excess Air:
Excess air impacts the temperature within the furnace and the temperature on exiting the furnace. It also reduces the localized reducing conditions in the burners.
Prevention for Fouling:
- Additives containing magnesium, silica, manganese, and aluminum can control fouling by increasing the melting points of deposits.
- The melting point of untreated ash can be as low as 1000oF, increasing by several hundred degrees with proper metal oxides. Magnesium and aluminum are the most commonly used additives to increase the melting point of untreated ash.
- Soot blowers are ideal for preventing dry, loosely bonded deposits that usually take place in the initial stages of deposition.
- Proper cleaning equipment like a soot blower for a coal-fired steam boiler is vital to avoid deposit formation.
- Load reductions during the off-peak operational process allow soot blowers to function effectively and significant cooling to get rid of the deposition.
Conclusion:
Deposition and corrosion cause major harm to the efficiency of steam boilers that significantly reduces their lifecycle. Therefore, it is necessary to properly check the boiler components and ensure regular maintenance of the steam boiler.
Rakhoh Boilers, with their 38+ years of expertise and experience, has emerged as a leading industrial steam boiler manufacturer and boiler service provider globally. We manufacture a range of efficient steam boilers that work effectively with various fuels along with waste heat recovery boilers, thermic fluid heaters, and boiler accessories. Our exceptional boiler services include boiler automation, energy audit, annual boiler maintenance, steam trap assessment, boiler retrofitting, and upgrading to enhance the productivity and lifespan of the steam boiler.
Visit our website www.rakhoh.com to explore our products and services.
- Published in Boiler
An Overview of Steam Quality in Boilers
Boiler efficiency is an important factor in process and manufacturing industries defined by the amount of combustion energy converted into steam energy. On the other hand, steam quality determines the amount of liquid or water present in the generated steam. Steam is beneficial as a heat transfer medium for processing operations as it releases a large amount of heat by condensing with water. Additionally, steam is safe and non-flammable with the capability to transfer heat at a constant and controlled temperature. Compared to other heating mediums, steam is cost-effective and completely recyclable. Despite the many advantages of the steam, process plants experience various problems like safety issues, equipment failures, and poor efficiency of the steam boiler. It may lead to severe boiler problems such as frequent boiler shutdowns, damaged steam pipes and valves due to water hammer, vibration, erosion, corrosion, reduced steam heater capacity, and overloaded steam traps. The most common cause for boiler problems is low steam quality, also known as wet steam or water carryover.
Although standards of steam quality depend on the application, it is necessary to ensure required actions by,
- Assessment of steam utilization and costs
- Managing the water quality
- Optimizing steam boiler design
- Incorporating best maintenance practices
Factors Influencing Steam Quality:
Applications of Steam:
The degree of steam quality varies by its application. High steam quality is vital for industries like power generation and food processing. Pharmaceutical industries require high-quality pure steam, whereas hotels can tolerate steam boilers with a relatively low steam quality but optimal efficiency.
Understanding the Challenges:
Lack of maintenance and knowledge is one of the common threats faced in manufacturing and process units. Secondly, the advanced age of steam boiler systems hinders the steam-generating capacity. Water carryover is the primary cause of low steam quality that results from incomplete separation of steam and water. Both mechanical and chemical factors lead to water carryover. It not only impacts steam quality but also affects steam boiler efficiency and safety. Carryover reduces the dryness of steam and heat content as well as causes erosive damage to piping and equipment of steam boilers. Steam quality also includes risks of tuning of the control system for adapting component usage and wear.
Steam Usage and Costs:
Proper boiler maintenance depends on understanding steam usage. It is necessary to determine the amount of steam used compared to the cost of the steam. In regular maintenance of the steam traps, examine the amount of steam used, method, and purpose of use, assessing if there are ways that would improve the steam quality.
Quality of Feed Water:
Ensuring high-quality feed water is the best way to eliminate steam quality issues. Water consists of impurities like dissolved salts, silica, and organics. It is essential to monitor the feed water quality and maintain it to industry standards to prevent water impurities from being carried over with steam. Scrubbing steam is an ideal way to achieve clean steam.
Steam Boiler Design:
Steam quality depends on the design and piping of the steam boiler. With the latest developments in technology and design, steam boilers are fabricated to reduce maintenance costs. The tolerance of carryover is a major consideration while selecting a steam boiler system. Once the system is installed, it must be ensured that the steam lines are properly insulated.
Maintenance Practices:
Proper and regular maintenance practices can prevent steam quality issues. Some of the essential steps advised by the boiler manufacturers are,
- Auditing the Boiler system and control equipment to detect weak points and make necessary improvements.
- Re-tuning of process control loops
- Introducing and improving automation control
- Train the operating staff for the proper handling and maintaining of the boiler system.
Effects of Low Steam Quality:
Proper operating practices and maintenance of steam boilers ensure high steam quality, necessary for controlling the heat transfer efficiency and steam boiler performance. Low steam quality impacts the boiler system in various ways such as,
Decreased heat transfer efficiency:
Low steam quality can reduce the heat transfer efficiency by around 65%. The excess liquid in low-quality steam accumulates on the surface of the heat exchanger that causes a buildup of liquid. It reduces the ability to transfer the steam energy to the product.
Failure of Valves:
When low steam quality containing liquid passes through control valves, it erodes the internal of valves and causes failure.
Failure of Turbine Component:
Liquid introduced with steam in turbine operation reduces the lifespan of the internal components.
Water hammer:
Excess liquid due to poor steam quality leads to a water hammer. It is a safety issue in a steam boiler that may cause failure in the system.
Rakhoh Boilers is one of the leading boiler manufacturers in Pune since its inception in 1983. We provide efficient steam boilers and thermal solutions in over 20 process industries globally. We offer the best boiler services like steam trap assessment, boiler automation, energy audit, annual boiler maintenance, etc. to boost the efficiency and productivity of steam boilers.
For ensuring high steam quality, it is necessary to follow the given guidelines,
- Insulation of steam lines and components
- Proper startup procedures
- Proper chemical treatment of feed water
- Installation of steam separators if required
Learn more about our products and services at www.rakhoh.com
- Published in Boiler
Wetback Steam Boilers | Definition, Key Factors, and Advantages
Steam boilers are paramount to accomplish the operational processes in the manufacturing and process industries. Plant managers consider various factors before opting for the ideal type of steam boiler for their facility. Steam boilers are primarily classified as fire-tube boilers and water-tube boilers. However, fire-tube boilers are further divided into two types of design namely; wetback designed boiler and dry back designed boiler. The major difference between both the boiler designs is its rear wall. The designs can be identified by the type of reversal chamber or the rear part of the combustion chamber that passes the flue gas through the furnace to the second-pass tubes for heating the water in the steam boiler.
What is Wetback Steam Boiler Design?
To define it in simple terms, the wetback boiler consists of a rear wall surrounded with water, whereas the dry back boiler comes with a rear wall lined with refractory. As the main objective of the steam boiler is to heat the water for generating steam, wetback boiler systems are considered relatively more efficient than a dry back boiler.
The wetback steam boiler design includes a reversal chamber that is jacketed or entirely surrounded by water. It is used for directing flue gases from the furnace to the tube banks. The burner heat is absorbed by the surrounding water that boosts the boiler efficiency by heating the water directly through combustion gases rather than refractory. The wetback boiler design includes separate tube sheets between tube passes that are more tolerant of load changes.
Fire tube boilers with wetback design offer optimum footprint by spilt-hinged doors that do not requires a cool-down period and can be opened immediately. Although there is no excess expenditure on maintaining refractory, internal pressure vessel maintenance may prove challenging. Usually, the wetback boiler produces more hot water as the combustion gets hotter.
Key Factors of Wetback Design in Fire tube Boilers:
Some of the major factors while incorporating wetback design in fire tube boilers are as follows,
- The input from the wetback must be supported by other heating mediums when the solid fuel burner is not in use.
- The level of emission for the solid fuel burner, incorporating the water jacket needs to be determined because the particulates emission increases as the water jacket cools the combustion process.
- Installing water jackets within the firebox reduces the heat output to the adjoining space.
- The open-vented supply line should incorporate a valve for allowing the water to replenish during overheating, as it causes a drop in the line pressure, activating the valve to replace the water lost from the top of the vent pipe.
- Wetbacks are not suitable for the local water with high lime content as they can build up inside the coil.
- Water needs to run through the wetback during combustion.
Advantages of Wetback Design in Fire Tube Boilers:
- Wetback boilers have a higher upfront cost, long-term fuel cost savings, ownership cost, and minimum downtime.
- Liftoff or split-hinged doors do not require a cool-down period and can be opened immediately.
- The door is designed in a way that reduces the requirement for floor space
- No excess expense of refractory maintenance however, pressure vessel maintenance can be complex
- Water absorbing the burner heat accelerates the efficiency of the steam boiler
- Separate tube sheets expand and contract independently depending on the temperature difference between the passes.
3 Pass Wetback Boilers:
3 pass wetback design fire tube boilers are preferred by many industries for the operational process. Rakhoh’s Optipac model comes with 3 pass fully wetback design that ensures optimal utilization of heat. The large water capacity allows it to meet the high steam demands in relatively less time. The quality of the generated steam is high because the saturation value is close to one. The dry steam enables significant savings in energy and reduces return through the condensation discharges fitted on the boiler system.
Rakhoh is a leading steam boiler manufacturer in Pune since 1983, delivering efficient steam boilers in India and overseas. We manufacture a range of steam boilers that perform effectively with various fuels, waste heat recovery boilers, thermic fluid heaters, and boiler accessories.
Our Optipac model is widely preferred for wetback design boilers. It offers twin furnace arrangements for above 4 TPH capacity, an inbuilt moisture separator for up to 98% dry steam, and a high grate area. It comes with an auto fuel feeding and handling system with an online monitoring system that can be mechanized by the client’s requirement. It is equipped with an air preheater, water preheater, and multi cyclone dust collector to enhance the efficiency of the steam boiler.
Explore our products and services at www.rakhoh.com
- Published in Boiler