KHD is a customer-focused engineering, equipment supplier, and service company, providing a full-line of competitive and environmentally friendly technologies to the cement industry.KHD, founded back in 1856,is a global leader in cement plant technology, equipment, and services and hence, the right partner for all your demands.
KHD is committed to continuously improving our technology and offering to customers. KHD understands the changing needs of our customers, andhas a long history of innovation. KHD was the first to introduce many industry leading products and processes, like our COMFLEX grinding system, PYRORAPID Kiln and PYROCLON Low NOxCalciner.
In order to provide the highest level of support for our customers, KHD has strategically placed sales offices in emerging markets around the world. With 750 employees worldwide, and CSCs and sales offices in growing markets, KHD customers are ensured the same high quality of service and products, regardless of location.
KHD is fully committed to understanding all of our customers and to being close to our customers through our local customer service centres. As a supplier of engineering, equipment, and plant services, KHD is a critical part of the supply chain to build new capacity and to upgrade and service existing capacity.
KHDs goal is to provide highly effective and competitive technology to our customers. This means understanding our markets, investing in research and development, providing cost effective solutions based on the concept of lifetime cost of ownership, and delivering world class performance.
Looking after the environment will be one of recurring themes throughout the next decades. KHD is committed to developing environmentally friendly products, saving natural resources, increasing the energy efficiency of our products, and reducing potentially harmful emissions.
KHDs goal is to create a world leading plant service business to support our engineering and equipment supply business. KHD recognises the cyclical nature of the industry in which we operate and has set a long term strategic goal of generating a major portion of revenues from plant services in the future.
KHDs greatest asset is its employees. KHD is truly a people business that strives to support, develop and treat its employees with respect. Our goal is to empower and motivate our employees to deliver global excellence.
Kiln plants with two and three station rotary kilns from KHD Humboldt Wedag are top of the line. One reason: highly efficient precalcining systems, which were developed by KHD Humboldt Wedag, revolutionizing the clinkering process.
Rotary kilns no longer have to function as calciners which mean that they can be substantially smaller in size. The advantage for customers is lower investment and operating costs. These systems quickly gained excellent reputations among our customers.
The three-station kiln from KHD Humboldt Wedag is a classic kiln which has been thoroughly tried and tested over the decades. Its proven standardized parts are also used in the PYRORAPID kiln. Regular optimization of standardized parts leads to even greater operational reliability and efficiency. The interaction of all components ensures the overall problem-free continuous operation of the kiln:
Lime production is a relatively complicated thermal decomposition reaction process of calcium carbonate to calcium oxide. Due to different kiln types, different equipment configurations, different raw material quality and composition, and different fuel types and calorific values, each will appear Various problems and faults The following are the analysis and treatment methods for common problems and faults.
If the top temperature of the calcination belt of the common shaft kiln is increased in the middle of the kiln body, the ash temperature is reduced, the CO2 content is reduced accordingly, the air volume is large, and the excess oxygen increases. The upper part of the kiln burned early. When the charge is lowered to the calcination zone, the fuel has no firepower, the amount of raw lime burning increases naturally, the top temperature control is too high or the fuel entering the kiln is fragmented and burns prematurely. The wind pressure and air volume are too large, or the size of the limestone is too large, the ventilation is smooth, and the unloading amount is unbalanced, which is also the reason for the upward movement of the calcination area. Eventually, a big burn is formed. In this case, you should:
When it is found that the top temperature is low and the ash temperature is increased, the fire and fire are not exhausted when the fuel is serious. Lime also increases the calcination, and the CO2 concentration decreases, which means that the calcination zone has moved down. The main reason for this situation is that the air volume is small, the amount of stone loading is large, and the amount of ash discharge is large, which makes the mixture move down quickly, and the cooling zone is shortened. The air fails to be preheated enough to enter the calcination zone, and the amount of calcium carbonate decomposed Reduced, CO also decreased accordingly. This causes an increase in the amount of lime burned.
In addition, the raw material is fragmented or the particle size deviation is large, and the resistance in the kiln increases. At this time, the air pressure is not low, but the actual air volume is not enough. In this case, the stone loading and ash discharge should be appropriately reduced, and the air volume should be appropriately increased. In this case, if the top pressure is too large, the batch can be appropriately reduced, the raw material can be changed, and the proportion of large particles should be appropriately increased to reduce the particles. The level difference reduces the resistance in the kiln. Adjust the fuel and stone mass to meet the technological requirements.
The extension of the calcination zone will cause the top temperature, the ash temperature will be higher, the CO2 will decrease, and the amount of lime burning will also increase. The formation of nodules or poor local ventilation in the kiln is due to excessive fuel ratio and poor uniformity of limestone, and the formation of nodules or poor ventilation in the kiln. At the same time, there are nodules or kiln wall hanging materials in the kiln, and the ventilation is segregated. The nodules or hanging materials prevent the materials from falling normally and have poor ventilation. Because the nodules fall off under the impact of the material flow, the calcination zone will also be extended for a certain period of time.
When this happens, the production should be properly reduced, the particle size of the raw materials should be adjusted, and the fuel ratio should be reduced to increase the air volume. After temporarily reducing the height of the material layer, the material is restored to the normal material level.
Rotary kilns are incredibly diverse in their processing capabilities, a characteristic that has pushed them into a growing number of applications. While rotary kilns are reliable machines, they can experience issues, especially when not properly designed, monitored, or maintained.
Knowing why such issues occur, as well as how to recognize and resolve them is critical to maximizing the longevity of a rotary kiln. And while issues are often specific to the unique parameters of the operation at hand, some of the most common challenges rotary kiln operators face are highlighted here, along with their causes, how to spot them, and potential avenues to resolution. Many of these issues can also be identified through a process or equipment audit.
Slag or dam ring formation in a kiln refers to a buildup around the circumference of the kilns interior in such a way that material is either prevented from passing through, or is significantly inhibited.
The formation of a material ring in the kiln has several implications, including affecting residence time and causing product quality issues, creating problems with material buildup in the feed-end seal, reducing throughput, and promoting material backup in the kiln. It can also significantly reduce throughput. Further, if the ring (or a portion of the ring) breaks free, it has the potential to completely block the kiln outlet, resulting in more severe problems.
The slagging temperature is the point at which the material will fuse together, allowing it to solidify. If a change in feed composition that reduces the slagging temperature is allowed to occur, ring formation will result.
The slag ring can either be manually removed, or dissolved by increasing the operating temperature of the system. If utilizing the temperature adjustment approach, once the ring has been broken down, the temperature can again be lowered to below the point at which slag can form.
To prevent additional slagging in the future, the combustion chamber thermocouples and monitoring systems should be checked to ensure they are functioning properly for adequate temperature monitoring. Feed material specifications should also be compared to original process parameters to ensure a change in feedstock is not to blame.
Material sticking in the kiln is a problem for a number of reasons. As with ring formation, it restricts the flow of material through the kiln, ultimately disrupting the loading and throughput capacity. It also has the potential to break loose and block the kiln discharge, as well as cause damage to the refractory.
Unfortunately, sticking can be caused by almost innumerable issues, making the source of it difficult to pinpoint. It is typically specific to how the materials unique chemical composition and physical characteristics interact with heat. Material may also become more sticky as it moves through the chemical or physical changes induced by the kiln.
For these reasons, rotary kiln testing is a critical part of process development; testing helps to identify such problems prior to production, allowing the kiln to be engineered to work around the material characteristics.
Some materials are likely to stick only between given temperature and moisture ranges. As such, by increasing the kiln temperature, the material may become less sticky, or could reduce in moisture enough to move out of the range at which it is likely to stick.
Knockers are a device used to knock the shells exterior in order to dislodge any potential buildup. They are available in different designs depending on the needs of the project. A wear plate on the kilns exterior provides protection to the shell while still allowing the energy from the knock to dislodge any buildup.
As mentioned, batch and pilot testing such as that carried out in the FEECO Innovation Center are crucial to developing an efficient and reliable high-temperature thermal process. When working with an existing kiln system, testing can be used to troubleshoot and resolve sticking or other performance inhibitors in the kiln.
Refractory protects the kiln shell from the high temperatures passing through the unit. When refractory is allowed to fail, the kiln shell can become damaged, even requiring total replacement in extreme cases. Further, frequent failures significantly increase downtime, adversely affecting processing capacity; at a minimum, refractory repair takes three to five days to correct a minor problem. In most applications, plant managers should plan on replacing up to 5% of the refractory system as a result of normal wear and tear on an annual basis.
While refractory is less commonly employed in indirect kilns (calciners), when it is used in these applications, a failure has the potential to reduce the thickness of the kiln shell, resulting in deflection, ovality, or even cracking.
The most common cause of refractory wear is the amount of cycling that the kiln undergoes. Cycling is the shutdown and startup of the kiln. This heating up and cooling down puts stress on the refractory, and if carried out frequently, substantially increases wear and decreases the life of the refractory.
Not far behind cycling, is improper material selection. The chemical and physical composition of refractory must take into account the material to be processed, as well as the specific operating parameters of the application.
Unfortunately there is no simple fix for resolving refractory wear. Refractory can be patched or repaired, but the underlying cause will continue to promote wear. As such, it is essential to ensure chemical and physical compatibility of the material and process parameters with the refractory, while also minimizing cycling as much as possible.
Misalignment is another commonly encountered issue when working with kilns. Proper alignment of the kiln affects every mechanical component of the unit; when a kiln falls out of alignment, it often results in premature wear on tires, trunnions, and thrust rollers, and puts added strain on other mechanical components.
Additionally, misalignment has the potential to impact the effectiveness of the seals. Because rotary kilns are a carefully controlled processing atmosphere, a reduction in seal effectiveness can change process conditions, causing process upset or under-processed material.
All rotary kilns gradually become misaligned over time as a result of normal operation, meaning kilns should be routinely realigned as part of a preventative maintenance program. Its important to recognize that any significant maintenance or repairs can also affect kiln alignment, so kilns should always be realigned after any major repair work.
Several factors can expedite the path to misalignment. This might include sinking foundations or changes in the structural integrity of the system, fugitive material allowed to build up on components, and even humidity, among other things.
Misalignment can present itself in a number of different ways, but is a common underlying problem of other issues. Signs of a misaligned kiln often include wear on load-bearing surfaces after resurfacing, audible vibrations or chattering, or damage to any of the following: tires/riding rings, thrust rollers, trunnion wheels, pinion/girth gear.
While misalignment is easily resolved, its essential to recognize that if the root cause of misalignment is not addressed, the kiln will immediately begin to fall out of alignment again. A full rotary kiln inspection should be conducted to determine the cause of the issue and assess any resulting damage.
Carryover is the entrainment of material in the exhaust gas system. While most kilns experience some level of carryover, an excessive amount of carryover is highly problematic. Carryover puts added stress on downstream components such as air pollution control equipment and often results in a reduction in processing capacity.
Since carryover is the picking up of material in the exhaust gas stream, the causes of excess carryover are fairly limited. A change in the amount of carryover is typically a result of a change in the bulk density or particle size of the material being processed, allowing it to be more easily picked up in the air flow. Similarly, an increase in the gas velocity could allow the gas to pick up particles that were previously too heavy to pick up.
Excess carryover can be discovered through a variety of indicators. A lower product output from the kiln could signal that more material is exiting with the exhaust gas. Similarly, an increase in the amount of material in the air pollution control equipment also points to increased entrainment.
Resolving excessive carryover in a kiln most often centers around adjusting either the feed material parameters (bulk density or particle size), or making changes to the gas velocity to prevent entrainment.
The capital expenditure that a rotary kiln represents demands that the investment be protected through proactive maintenance. For this reason, in addition to routine maintenance and walk-throughs, FEECO recommends a minimum of annual inspections be conducted by a qualified service provider.
Those experiencing process issues or inefficiencies may also benefit from a rotary kiln process audit, which looks at the system as a whole, along with process parameters, to identify any issues or opportunities for improvement.
Rotary kilns provide an efficient and reliable approach to a wide range of thermal processing applications. Recognizing where potential for issues exists, as well as how to identify and correct these issues, is essential to maximizing the life of the unit. Process and equipment audits, along with annual inspections, are powerful tools in a preventative maintenance program and can also help to improve kiln process efficiency.
FEECO Customer Service Engineers are highly skilled in the mechanical and operational aspects of rotary kilns and in addition to identifying issues, can also help to carry out repairs such as realignment, tire and trunnion grinding, retrofitting solutions, and so much more. For more information on our extensive rotary kiln parts and service support, contact us today!
For evaporating moisture from concentrates or other products from plant operations, Rotary Dryers are designed and constructed for high efficiency and economy in fuel consumption.Whenever possible to apply heat direct to the material to be dried, Rotary Dryers of the Direct Heating Design are used. If it is not possible to apply heat direct to the material to be dried, Rotary Dryers of the Indirect Heating Design can be furnished so that the heated gases will not come in direct contact with the material.
Rotary Dryer is a simple, inexpensive unit for reducing the moisture content of flotation concentrates, as well as chemical and industrial products. Frequently the saving of shipping weight so effected will pay for the dryer in a few months. Difficulties from freezing while in transit are also eliminated. Many industrial projects are now using Dryers for control and production purposes on many materials.
Three main types of Rotary Dryers can be supplied. The direct heat unit is used when it is permissible for the drying gases to come in direct contact with the material being dried. Partition plates increase the heating surface. Drying may be by hot air or exhaust gases from other operations. If this drying gas has a deleterious effect on the product, then an indirect type of dryer can be supplied. A further derivation is the Tedrow Steam Dryer.
Of the different types of dryers that there are the most common is the ROTARY DRUM DRYER/Kiln, This type of drier is common not only in the mining industry but you will find them in fertilizer plants, Cement plants, and peat hogs to name but a few.
The theories behind these machines are very simple, heat an air space up, and then tumble the material to be dried through this space until it is dried. All though it sounds simple there are problems that have to be solved before the required results are met. But first, so you know what we are talking about lets go through the design of a drier.
First is the KILN, this provides the heat, The BURNER is inside this portion. The fuel for the burner is usually diesel although heavy crude oil could be used in some cases. To be able to generate enough heat to dry the concentrate air must be added by way of a BLOWER. In front of the kiln is the point that the wet concentrate enters the drier. It is put into the revolving SHELL. The shell is on a slight incline. As the Concentrate is tumbled through the hot air mass of the drier it travels down this incline to the exit of the drier.
At this exit point the concentrate is either deposited straight into a storage area or taken to the storage area by a conveyor. It is also at this point that there is an EXHAUST HOOD. This provides a controlled escape passage for the fumes and water vapor that is generated by the concentrate drying. This is a very important function and the operator will have to be sure that it is open at all times. If it should become blocked the water vapor will not be able to escape. The concentrate will become wet and sticky which will result in the discharge plugging. The wet sticky concentrate will also lower efficiency level of the drier for an extended period of time. This happens because inside the drier shell are what are termed FLIGHTS these are flat pieces of metal that are bolted onto the shell.
They are there to lift the concentrate up to the top of the shells rotation and drop the concentrate through the hot air. If the water vapor isnt taken away, the concentrate becomes sticky from reabsorbing the water. This sticky concentrate will fill the spaces between the flights.
The concentrate will not be lifted and dropped through the hot air. This results in a long term condition of poor performance even after the initial problem has been cured. These flights will remain buried in concentrate. This removal of the water vapor is one of the functions of the blower. It assists the natural process of air movement as the hot air mass expands. To prevent the buildup of concentrate on the flights there are often CHAINS attached to them. As the drier revolves the chains slap the flights preventing concentrate from building up on dryers walls.
The drier shell is rotated separately from the stationary kiln section. To achieve the rotation a BULL GEAR is attached around the shell section. There are also two flat rings attached to the shell. These provide surfaces for support rollers to roll on. There is another problem that the inclined shell has, the incline causes the shell to want to slide in the direction of the incline. To prevent this additional rollers are attached to the last set of rollers.
Increase your energy efficiency with our innovative graphite seal that works on any kiln any size, any manufacturer. We deliver a module that is designed to integrate with your existing casing and cooling mantle with no modification required
Much of the Kiln Graphite Seal Module is pre-assembled in our workshop, which means easy installation and less downtime for you. It also allows us to deliver top quality, ensuring the straightness of the flanges.
Unlike other block seals on the market, our Carbon Graphite Kiln Seal uses a staggered arrangement with two rows of graphite blocks held in place by a wire rope system. That means youll get a strong and effective seal against the outer air casing.
Our design lets the graphite blocks move independently with the radial movement of the kiln without getting damaged or stuck. And locking plates installed on the rear flange keep false air from entering the rotary kiln system.
How does it work? The casing, hopping, and ducting act as a material buffer. They guide the excess raw meal to a bin, or to a conveyer system. Meanwhile, the hopper comes with a sloping plate that helps stop dust build-up on the graphite kiln seal.
Our Kiln Graphite Seal works on any rotary kiln, not just the kilns we manufacture ourselves. Well also work with you to adjust any existing equipment, such as kiln shells, fans and hoppers in order to keep installation cost to a minimum.
Two types of Kiln Graphite Seals are available; both are designed to maintain optimal kiln operating conditions and minimise energy loss.The Kiln Inlet Seal provides an interface between the kiln and preheater, while the Kiln Outlet Seal creates an interface between the kiln and the cooler.
FLSmidth provides sustainable productivity to the global mining and cement industries. We deliver market-leading engineering, equipment and service solutions that enable our customers to improve performance, drive down costs and reduce environmental impact. Our operations span the globe and we are close to 10,200 employees, present in more than 60 countries. In 2020, FLSmidth generated revenue of DKK 16.4 billion. MissionZero is our sustainability ambition towards zero emissions in mining and cement by 2030.
We develop an effective model based on spatiotemporal features of flame clip for the recognition of burning condition.The unsteady state condition of rotary kiln is first studied in this paper, and the proposed method achieves high recognition accuracy for it.We propose two computationally simple and effective 3D dynamic texture and structure descriptors, 3DBLBP and HOPC-TOP, to characterize dynamic texture and structure of flame.
In the coal-fire industry, recognition of burning condition is vital for combustion control and optimization as it can provide early warning of abnormal conditions in the combustion system. We propose an effective model based on spatiotemporal features extracted from flame video for burning condition recognition especially for unsteady state condition. This model extracts features from both the spatial and temporal dimensions based on multiple adjacent frames to capture the appearance and motion information of the flame. Two new three-dimensional (3D) descriptors are developed to characterize the dynamic characteristics of the flame video stream. A computationally simple and fast dynamic texture descriptor, 3DBLBP, is designed to extract flame dynamic texture and motion from three adjacent frames of a video block, and a dynamic structure descriptor, HOPC-TOP is developed by extracting 3D phase congruency information of video clip from three orthogonal planes to capture structure and motion characterizes of flame. The two descriptors are combined to extract spatiotemporal features from flame clip for burning condition recognition. Experiment results show the proposed framework can achieve a high recognition accuracy in the real-world data, thus verifying the effectiveness of our proposed framework for the recognition of burning conditions in a rotary kiln.Get in Touch with Mechanic