rotary dryers capacity and their prices

rotary dryer versatility

rotary dryer versatility

If you need a dryer, you have surely already waded through the plethora of options on the market today. How will you ever choose the best one for your application? The purpose of this article is to inform you about rotary drum dryers, because they can be the most affordable and economic choice when considering a new or used dryer. Plus, they are the most versatile of all dryer designs today.

Rotary drum dryers can be chosen for projects as large as evaporating half a million tons of water to as small as evaporating several tons of water. They come in all sizes to accommodate many products, quantities, and moisture content ranges. Although, they can be larger, 18 diameter drums seem to be the largest practical for manufacture, transport, and installation. Depending on length, an 18 drum could evaporate 120,000-lbs/hr of water. Say the product to be dried starts at 50% moisture content wet basis (mcwb), this drum could handle 120-ton/hour or more. At 8,400 operating hours per year, youre looking at a million tons of product infeed going through every year, or about half a million tons per year of final product.

An 18 dryer drum is not the only option. Rotary dryer drums as small as 4 diameter can evaporate anywhere from 200 500-lbs/hr. Rotary drums much smaller than this have efficiency losses so an alternate drying system may be more beneficial. Using the same example above, with a product at 50% mcwb, a small rotary drum dryer can take care of 400 1,000-lb/hr of product, or 1,680 4,200-ton/year infeed and approximately half that of product out. Obviously, these numbers depend on a variety of variables not the least of which is the moisture content of the infeed and the desired moisture content of the final product.

Rotary drum dryers can be designed to withstand extremely high temperatures and/or corrosive materials. A basic carbon steel drum is designed to withstand inlet temperatures from 1,000F 1,100F. Of course rotary drum dryers can be designed to handle different inlet temperatures. Stainless steel can be used in place of carbon steel if the product is known to be corrosive. Other materials can be substituted as well depending on the nature of the product to be dried.

Rotary drum flighting is the primary material handling mechanism in a drum. Flighting can be designed to accommodate different flow characteristics of the materials to be dried. Some materials clump and potentially form balls which need to be broken up, while others flow like water and need to be slowed down. Other pieces might be long and stringing and can easily get trapped. Different flighting designs can solve these, and other, problems.

With so many specialized dryers available today, it seems that every single product has a different dryer designed specifically for it. What happens if you quit making a particular product that had a specialized dryer? Can the dryer be modified to dry something else? If it is a rotary drum dryer the answer is yes, another wonderful feature of a rotary drum dryer is that the flighting system can be changed to repurpose a used or existing dryer. A flighting designer, oddly enough they do exist, can look at the flow characteristics of the material in question and determine what kind of flights are necessary, thereby converting the dryer to a new purpose at a fraction of the cost of buying a new dryer.

Rotary drum dryers can dry many different types of products. Not only are they great for uniform solid particles, but they are the best solution for non-uniform solid particles. The number one factor in deciding a dryer is whether the material handling of the dryer matches what the product needs.

Products that have non-uniform particle sizes are perfect candidates for a rotary drum dryer, like the wood in the picture above. However, the flighting system would be different for the sample on the left than for the sample on the right. It is important to know the characteristics of the infeed product to choose the best flighting design.

A rotary drum dryers greatest asset is its ability to accommodate a product that has multiple size particles and moisture contents by utilizing the right flighting package. As seen in the picture above the wood is in a variety of shapes and sizes. The larger, heavy particles will be carried less distance by the drying gases than the smaller, lighter particles. This means that the smaller particles can exit the dryer before they become over-dry and the larger particles can remain in the drum until they have dried a sufficient amount. The flights can be designed to keep the larger pieces in the drum longer and allow the smaller pieces to flow more quickly. The right flighting package can help achieve uniform product quality and can also lead to reduced emissions.

Unfortunately, rotary drum dryers seem to have fallen into a niche market. Dryer manufacturers and purchasers have been shying away from rotary dryers recently because of perceived reliability, quality and versatility issues.

One of the perceived issues is lack of reliability. Drum shell, headplate, or tire flexing can lead to premature failure. Rotary drum dryers get a bad rap due to some drums not being designed and built correctly or drums being repurposed without upgrading them for the new product or application. Without proper internal and external support, the drum has a tendency to flex while rotating in some instances causing horrible shaking and vibrating. Some drums have been measured to continually be wider than tall, flexing every time it rotates. Imagine if you will, a water balloon rolling down the sidewalk. When steel flexes to that degree eight times per minute (based on 4-RPM), it does not take long before the thing breaks. Given the right design, construction materials, and fabrication techniques a well-built rotary drum dryer should last for 20+ years without any major structural issues, such as cracks in the shell or headplates.

Another perceived issue is lack of versatility. The importance and flexibility of different flighting packages is often misunderstood in the industry. Many of the rotary drum dryers that are available today only have the option of one type of flighting package. To get the most out of your rotary drum find a manufacture that offers flighting packages for your applications and products.

Another challenge facing rotary drum dryers is a reputation of poor product quality and excessive emissions. This can be overcome in a few ways, two of which are discussed here. The first way we already discussed above by utilizing the right flighting package for your product. The next way is through the use of Exhaust Gas Recycle, EGR, (also known as Flue Gas Recycle, FGR) the product can be protected from hot, dry, drying gases by recycling water vapor back through the system and increasing the wet bulb temperature. The higher wet bulb temperature allows the particle internals to heat at the same rate as the externals, thereby allowing an even evaporation rate. If the wet bulb temperature is low because the system does not have enough moisture, the outside of the particle can flash dry and act as an insulator to the inside, not allowing the moisture to migrate to the surface. The particle can reach the end of the drum with an over-dried or, worse yet, charred outside and wet inside. This is kind of like putting a burger on the grill when the coals are too hot. Over-drying or charring the outside gives off volatile organic compounds (VOCs) which will cause a haze and/or bad smell outside the plant if a back-end cleanup system has not been utilized. Not over-drying the outside means less potential VOCs which means lower emissions. Another added benefit of EGR and the right flighting package for your product is the potential to lower the inlet temperature. High inlet temperatures cause most of the over-drying, so lowering the inlet temperature will also reduce the potential for VOC emissions.

In conclusion, rotary drum dryers are the work horse of the drying industry because of their longevity, capacity and ability to be adapted to new purposes. Do not overlook a rotary drum dryer when trying to decide how to improve or expand your drying equipment as you can see how easy it is to overcome these perceived problems.

rotary dryer faqs

rotary dryer faqs

Rotary drum dryers are one of the most widely used types of industrial dryers on the market today. Their heavy-duty design, high throughput, long-term reliability, and simple operation has lent them to a wide range of applications in a variety of industrial process settings. They are the dryer of choice for processing fertilizers and soil amendments, animal feeds, minerals and ores, and so much more.

While rotary dryers have a relatively straight-forward design, many questions often arise in considering a rotary drum dryer for a given application, even when the application is well-established. Below are answers to some of the most frequently asked questions surrounding rotary drum dryers.

Rotary dryers consist of a large, rotating drum through which wet solids are passed. As the material moves through the dryer, heat and air are used to remove the desired amount of moisture, with the mode of heating dependent on whether the unit is of the direct or indirect configuration. Most dryers are of the direct design, in which the material is in direct contact with the combustion gases, as this is the most efficient approach to moisture removal.

The material is cascaded in the dryer at carefully controlled temperatures for a predetermined amount of time (referred to as the retention or residence time) to reach the desired final moisture content.

The principle difference between a direct rotary drum dryer and an indirect one, is how heat is introduced to the material. Direct dryers rely on convective heat transfer from direct contact between the material being processed and the combustion gases to efficiently dry the material. Conversely, indirect dryers avoid contact between the material and combustion gases, instead relying on heat transfer to occur through the drum shell wall via conduction.

While this approach is less efficient than the direct dryer type, it is an essential processing option when working with materials that must be processed in an inert atmosphere, such as when processing sterile products. The indirect configuration is also chosen when processing ultra-fine materials, as it avoids the risk of solids becoming entrained in the gas flow and ending up in the exhaust gas system.

Since rotary dryers are best designed around the specifications of the given application and material to be processed, standardized designs, while less costly and requiring less production time, are inherently not as effective or efficient.

For a truly high-performance rotary dryer, the design process must take into account a wide range of factors such as inlet and outlet moisture, bulk density, heat transfer properties, material consistency and fragility, and more.

The rotary dryer manufacturer will gather the necessary data points and use computer dryer sizing calculations to determine the optimal drum size. Depending on the process goals and application, dryer feasibility testing may be necessary to assess the materials behavior in the dryer and define the process data necessary for scale-up.

In addition to the process data, the dryer manufacturer will also consider material characteristics and process goals that will influence the design. This might mean selecting different materials of construction, assessing flight design, adding customizations such as knocking systems or trommel screens, and more.

Rotary dryers and kilns are similar in design, but are employed for different reasons. Rotary dryers serve to remove moisture from the material, while rotary kilns are intended to cause a chemical reaction or physical change in the material by adding heat. For this reason, rotary kilns are typically operated at higher temperatures than dryers, and therefore, are designed with a higher heat tolerance in mind.

Rotary drum dryers can be constructed from a wide range of materials, the choice of which is dependent on the temperatures employed and the characteristics of the material to be processed. Common materials of construction include:

The dryer may also utilize multiple materials of construction to meet the needs of the material being processed as well. For example, the sticky nature of some materials may benefit from using polished stainless steel for the inlet section, and carbon steel for the remainder of the drum shell. The polished stainless steel will discourage sticking near the inlet and give material a chance to dry a bit before it reaches the carbon steel, at which point the potential for sticking will be reduced.

While there is some overlap between these two industrial dryer types, the choice between a rotary dryer and fluid bed dryer is a matter of capabilities. Rotary dryers are best suited for demanding drying applications, such as those found in the mining industry. They are also a better choice when variation in feedstock is common. For more information, see Rotary Dryer or Fluid Bed Dryer.

Yes: Rotary dryers are easily automated. Depending on the manufacturer, automation capabilities may differ. FEECO has partnered with Rockwell Automation to offer dryer automation capable of monitoring, collecting, and trending various data points such as current (amps), fan speed, feed rate, fuel usage, gas sampling & analysis, horsepower, system pressures, temperatures, and more.

FEECO is the leading provider of custom rotary dryers, with hundreds of installations around the world. Our rotary dryers are built to the highest quality standards and are engineered around the unique characteristics of the material to be processed for an optimal drying solution. For more information on our dryers, contact us today!

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rotary dryers

rotary dryers

Weve built a reputation on building the best rotary dryers in the industry. All of our dryers are custom designed to suit the unique processing needs of your material. Whether you require low or high inlet temperatures, short or long residence times, counter current or co-current flow, FEECOs design team can design a rotary drum dryer for your application.

Rotary dryers are a highly efficient industrial drying option for bulk solids. They are often chosen for their robust processing capabilities and their ability to produce uniform results despite variance in feedstock.

The drum is positioned at a slight horizontal slope to allow gravity to assist in moving material through the drum. As the drum rotates, lifting flights pick up the material and drop it through the air stream in order to maximize heat transfer efficiency. When working with agglomerates, the tumbling action imparted by the dryer offers the added benefit of further rounding and polishing the granules.

All FEECO equipment and process systems can be outfitted with the latest in automation controls from Rockwell Automation. The unique combination of proprietary Rockwell Automation controls and software, combined with our extensive experience in process design and enhancements with hundreds of materials provides an unparalleled experience for customers seeking innovative process solutions and equipment.

Rotary dryers are known as the workhorse of industrial dryers. They are able to process a wide variety of materials, and can lend a hand in nearly any industry requiring industrial drying solutions. Some of the most common industries and materials in which rotary dryers are employed include:

Unlike direct dryers, indirect dryers do not rely on direct contact between the material and process gas to dry the material. Instead, the rotating drum is enclosed in a furnace, which is externally heated. Contact with the heated drum shell is what dries the material.

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Our rotary dryers are built to the highest quality standards, with longevity in mind. The best part about buying a FEECO rotary dryer, is that you get the security of knowing your equipment is backed by over 60 years of experience, material and process knowledge, and a proven track record.

rotary dryers - an overview | sciencedirect topics

rotary dryers - an overview | sciencedirect topics

Rotary dryers are mainly used in the chemical and mineral industry. In the area of food, their most common applications are for dehydrating waste materials (citrus peels, vegetable trimmings) and animal feedstuffs (alfalfa). Rotary dryers consist of a metal cylinder with internal flights or louvers (Fig. 22.21). The cylinder is slightly inclined. The material is fed at the high end and discharged at the low end. Hot air is blown in cocurrent or countercurrent direction. As the cylinder rotates, the material climbs in the direction of rotation. When it reaches a position where its angle of repose has been exceeded, the material falls back to the bottom of the cylinder (Fig. 22.21). Most of the drying takes place while the material falls through the air blast. Using very hot air or combustion gases, rotary dryers can also function as roasters for nuts, sesame seeds, and cocoa beans. A detailed method for the design of rotary dryers, based on a heat exchange approach has been described by Nonhebel (1971).

Rotary dryers are often used for particulate material. Particles and hot air are continually fed to the drum. These large rotating drums have lifting flights which carry the particles upward as the drum rotates. The particles leave the lifting flight near the top of the drum and fall through the air stream. Heat is transferred to the particles both from the air and from contact with the dryer. The drums may have concentric sections so that the particles and air traverse the length of the drum up to three times. Residence time is on the order of minutes. Friable material, such as wafers or flakes, may be dried on trays or belts instead of in drums. Very fine material, such as fiber board furnish, might be dried in a tube dryer in which the air carries the fiber through the tube in seconds.

For particulate solids, a rotary dryer may help promote uniform and more rapid drying (Fig. 14.14). In the rotary cascade dryer, the material is placed in a rotating cylinder through which a hot air stream is passed. Flights on the cylinder wall lift and cascade the product through the air. In a variant, louvers are used instead of flights so that the product is mixed and rolled instead of dropped. The dryer is typically sloped, so that the product enters and gradually falls toward the discharge end. In direct rotary dryers, the air is passed through burners, and directly comingles with the product. Rotary dryers have been used to dry seeds, corn gluten, distillers grains, and some fruit.

A rice combine harvester usually performs with less loss of paddy; however, the potential shortcoming is that the paddy must be harvested at high moisture content, that is, ranging from 20% to 28%. The high moisture content of harvested paddy is conducive to rapid deterioration in quality such as discoloration, yellowing, germinating, and damage to milling quality.

The only practical means of preventing grain quality deterioration is immediate drying of high moisture paddy, because sun drying, the conventional method, is inadequate to guarantee the quality and quantity of the produce. Thus there is a high demand for mechanical drying facilities.

Most mechanical dryers available are suitable for rice millers and farm cooperatives that handle thousands of tons of paddy. Small-scale dryers were developed for farm use, such as a fixed bed dryer and solar rice dryer (Exell and Kornsakoo, 1977); however, those were not widely accepted because of the potential inconvenience in loading/unloading of paddy and unequal drying.

Jindal and Obaldo (1986) and Puechkamutr (1988) worked on accelerated drying of high moisture paddy using conduction heating for a rotary dryer. Their studies demonstrated the potential of high temperature for quick drying of paddy without significant damage to the grain. This technique is promising from an energy consumption point of view.

Puechkamutr (1985) developed a rotary dryer for paddy based on conduction and natural convection heating. Paddy was effectively dried from moisture content of 23% to 16% (w.b.) using a pipe heat exchanger at surface temperatures of 170C200C with a residence time of 3070s. Rapid drying and good milling quality of the paddy could be achieved with such a dryer.

A combination conductionconvection heating type rotary dryer was developed for on-farm drying as a first stage. It consisted of double cylinders: the external cylinder with 500mm diameter, attached to an inside surface with straight flight; and an inner cylinder, hexagonal in shape with an outer tray and firing device installed inside as a part of the inlet cylinder. The grain cascaded inside the external cylinder with a concurrent flow of air. Experimental results showed that about 3% of moisture content could be removed with single pass with a small reduction in milling quality (Likitrattanaporn, 1996).

Another study of a combined conductionconvection type rotary drum dryer was made by Regalado and Madamba (1997) on thermal efficiency. The fresh ambient air forced inside the drum in a counter flow direction of grain brought evaporative cooling of the hot grain as shown by the increase in moisture reduction whenever air velocity was increased.

A further improved prototype of a combined conductionconvection type rotary drum dryer used ambient air that was forced inside the drum in counter flow to the direction of the cascading grains. The grain was heated by conduction heating as drying proceeded and followed by convection heating as cooling occurred of the heated grain. The results showed that its partial drying capacity was approximately double that of the predryer developed by the International Rice Research Institute requiring only a single pass operation. Neither drum surface temperature nor ambient air velocity and their interaction influenced total milling recovery and head rice recovery.

Likitrattanaporn et al. (2003) designed and developed a combined conduction and convection heating rotary dryer for 0.5t/h capacity using liquefied petroleum gas (LPG) as the heat source, to dry high moisture paddy under farm conditions. The main aim was to find an affordable way of drying field paddy on the day of harvesting to facilitate handling and for higher returns of produce for the farmer. Emphasis was placed on operating conditions in which up to 3% moisture could be removed in a short time while grain quality should be closed to fresh paddy. Performance of the rotary dryer in terms of moisture removal, residence time, energy consumption, and milling quality were evaluated.

An experimental rotary dryer designed with concurrent flow system comprising two primary parts, a double cylinder and a discharge cover, is shown in Fig. 12.1. Forward movement of paddy takes place by inclination angle and rotary motion of the cylinder, while air is blown through the cylinder by the suction fan located on top of the discharge cover. A 1-hp motor with 1:60 reduction gear was used for driving the rotary dryer. The LPG lamp on the entry end heats up the air and heated air moves to other end by suction fan. During forward motion, paddy first contacts the outer surface of the inner cylinder where conduction heating takes place followed by a cascading action along the inside of the external cylinder resulting in convection heating. After this the paddy falls into the discharge cover and out of the dryer, while the suction fan sucks the moist air.

Relatively less moisture was removed during the last (third) pass at temperatures of 100C and 110C, that is, 1.5% and 1.7%, respectively. At 120C temperature, moisture content of 2.1% could be removed. Clearly, this is because there was less free water available at the third pass of drying.

The conduction and convection zones are shown in Fig. 12.2, along with the inlet and outlet temperatures of grain and the hot air. It can be seen that high temperature in the conduction zone can remove a higher amount of water than in the convection zone, which is, in turn, sucked out by hot moist air. It can also be observed that outlet grain temperature was dropped to the safe range (max. 52C) within a very short time (23min).

To demonstrate the dryers heat exchange efficiency, comparison of the effects of conduction heating and convection heating on moisture removal showed that the major moisture content of paddy was removed by the conduction heating for all temperatures, whereas the convection heating could remove moisture less than 0.4%.

Being designed as a mobile unit for drying paddy in the field, energy consumption is one of the most important aspects of consideration. The difference in weight before and after running a pass was recorded. A statistically insignificant difference was found in weight of LPG consumed at all temperatures. The average power consumption was, however, 0.6kWh and power of 0.46kg/h LPG. It was estimated that the operating cost of removing up to 1% of the moisture content of 1t of paddy was $0.23 in the first pass. The cost would increase up to $0.33 in the second pass and subsequently increase in the third pass depending on the availability of free moisture.

Likitrattanaporn et al. (2003) designed and developed a combined conduction and convection heating rotary dryer for 0.5ton hr1 capacity using liquefied petroleum gas (LPG) as the heat source, in order to dry high moisture paddy under farm conditions. The main aim was to find an affordable way of drying field paddy on the day of harvesting to facilitate handling and for higher returns of produce for the farmer. Emphasis was placed on operating conditions in which up to 3% moisture could be removed in a short time while grain quality should be closed to fresh paddy. Performance of the rotary dryer in terms of moisture removal, residence time, energy consumption, and milling quality were evaluated.

An experimental rotary dryer designed with concurrent flow system comprising two primary parts; a double cylinder and a discharge cover is shown in Figure 10.1. Forward movement of paddy takes place by inclination angle and rotary motion of the cylinder, while air is blown through the cylinder by the suction fan located on top of the discharge cover. A one horse power motor with 1:60 reduction gear was used for driving the rotary dryer. The LPG lamp on the entry end heats up the air and heated air moves to other end by suction fan. During forward motion, paddy first contacts the outer surface of the inner cylinder where conduction heating takes place followed by a cascading action along the inside of the external cylinder resulting in convection heating. After this the paddy falls into the discharge cover and out of the dryer, while the suction fan sucks the moist air.

Relatively less moisture was removed during the last (third) pass at temperatures of 100C and 110C, i.e. 1.5% and 1.7%, respectively. At 120C temperature, moisture content of 2.1% could be removed. Clearly, this is because there was less free water available at the third pass of drying.

The conduction and convection zones are shown in Figure 10.2, along with the inlet and outlet temperatures of grain and the hot air. It can be seen that high temperature in the conduction zone can remove a higher amount of water than in the convection zone which is, in turn, sucked out by hot moist air. It can also be observed that outlet grain temperature was dropped to the safe range (max. 52C) within a very short time (23min).

To demonstrate the dryers heat exchange efficiency, comparison of the effects of conduction heating and convection heating on moisture removal showed that the major moisture content of paddy was removed by the conduction heating for all temperatures, whereas the convection heating could remove moisture less than 0.4%.

Being designed as a mobile unit for drying paddy in the field, energy consumption is one of the most important aspects of consideration. The difference in weight before and after running a pass was recorded. A statistically insignificant difference was found in weight of LPG consumed at all temperatures. The average power consumption was, however, 0.6KWh and power of 0.46kg/hr LPG. It was estimated that the operating cost of removing up to 1% of the moisture content of 1 tonne of paddy was 0.23$ in the first pass. The cost would increase up to 0.33$ in the second pass, and subsequently increase in the third pass depending on the availability of free moisture.

Dried citrus peel is one of the most common feeds. It is manufactured by pressing peel through a rotary dryer and adding citrus molasses to help the drying process and help prevent the peel from burning. The moisture content of dried peel must be below 10%. Many experiments published in the 1970s have shown that dried orange pulp, partially or completely replacing cereals in concentrate mixtures, are particularly useful in reducing feeding costs in dairy cows, have no influence on production, and have a good palatability. Dried pulp has also been used in swine, which have been shown to utilize it at a ratio of up to 2025%. Besides its use as a substitute for maize, up to 20% in diet has no influence on the growth and production of laying hens. The dried pulp can be pelletized and is consumed more easily by ruminants with advantages of storage, shipping, and microbial spoilage. Pellets made from dried pulp have different dimensions, and several factors affect their characteristics, such as the energy used in pelletizing and the proportions of citrus molasses (about 515% of the total weight gives excellent results) used as binding agents.

Thermal desorption is a technology of physical separation based on heating the contaminated soil to volatilize water and organic contaminants. Soils are heated in a thermal desorption system, the rotary dryer being the most commonly used equipment. Thesystems require the treatment of the off-gas to remove particlesand contaminants. Its effectiveness depends on the contaminant. Decontaminated soil usually returns to the original site. Based on the operating temperature, these processes can be categorized into two groups: high-temperature thermal desorption ranging from 320 to 560C and low-temperature thermal desorption ranging from 90 to 320C. Thermal desorption can be used in a place where some other cleanup methods cannot be used, such as at sites that have a high soil contamination, and can be a soil remediation method that is faster than others.

Thermal methods may also be applied as an in situ technique. In this case, heat is applied to soil to volatilize semivolatile organic compounds (SVOCs), which can be extracted via collection wells and treated. It is a particular case of SVE. Heat can be introduced into the subsurface by electrical resistance heating, radio frequency heating, or injection of hot air or steam. Thermal methods can be particularly useful for dense nonaqueous phase liquids (DNAPLs) or light nonaqueous phase liquids (LNAPLs).

staartechno stainless steel rotary dryer machine, automatic grade: automatic, capacity: 5 ton, | id:

staartechno stainless steel rotary dryer machine, automatic grade: automatic, capacity: 5 ton, | id:

Staartechno Equipments has gained a remarkable position in the market and commenced in the year 2000 as a Sole Proprietorship based firm. The headquarter of our corporation is situated in Chennai, Tamil Nadu. We are the leading Manufacturer and Exporter engaged in offering a supreme quality range of Electroplating Plants, Ladling Machine, Industrial Grinder, Stainless Steel Elevators, Industrial Dryers, Shot And Sand Blasting Machine, Industrial Conveyors etc. Offered products are extensively demanded their unmatched quality and reasonable prices.

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