saka semi-automatic industrial rotary dryers, capacity: 1 ton to 500 tonnes per hour, | id: 1964264233

saka semi-automatic industrial rotary dryers, capacity: 1 ton to 500 tonnes per hour, | id: 1964264233

We offer Industrial Rotary Dryers. They consist of a relatively long cylindrical shell, supported by two riding rings running on a set of rollers. They are slightly inclined from the horizontal, the slope enables the material to move from the feed to the discharge end under gravity. They are suitable for a wide range of materials of varying size and composition.

Internal lifters, or flights, are used to lift, distribute and transport the material. This produces a shower, or cascade, of wet feed material through the hot gas stream, which promotes evaporation of the moisture and breaks up lumps to produce a more uniformly dried material. The hot air is introduced either at the feed end such that it moves in the same direction as the material (co-current) or at the discharge end such that it moves in the opposite direction (counter-current).

The co-current direct-heat rotary dryer is the most common, wet material is in contact with the hot gas stream as its highest temperature, which causes rapid evaporation of surface moisture. As it progresses through the dryer, heat energy is lost to the material it is drying and it leaves the dryer at a comparatively low temperature. In co-current dryers, the initial heat transfer is high, which causes a considerable drop in temperature thus preventing overheating of the material and the dryer itself. The final dried product is discharged with the gas stream at its lowest temperature, which ensures the moisture content can be readily controlled. Counter current dryers are more suitable for material that must be dried to very low moisture contents or where the last traces of moisture are difficult to remove.

Saka Engineering Systems Pvt. Ltd. is among the fastest growing organisations in the realm of Industrial Drying and Evaporation Systems. We offer a wide range of spray drying systems including Spray Dryers, Fluidized Bed dryers, Vacuum Dryers, Flash Dryers and Conduction Dryers. In addition we also offer drying system accessories such as two fluid nozzles, rotary atomizers, industrial drying chambers, air dispersion systems.We design and Manufacture Best in class Calcium Chloride Granulation Systems and Granulators for other chemicals like Magnesium Chloride, Calcium Nitrite etc.Saka Engineering systems also Provide Industrial Pollution control equipments like Wet scrubbers, Bag filters, Cyclone separators, Zero discharge systems and effluent treatment plants. These are manufactured with graded stainless steel and mild steel ensuring maximum durability of the equipments. Our mission is to satisfy our customers by providing optimum solutions to their requirements. We understand the fact that each customer has a unique requirement which can be met by a unique design.

Our designs are not only cost-effective, but also very efficacious in their functionality. SESPL is driven by strong leadership and highly experienced team of Engineers dedicated to optimize the system catering to the needs of our customers. The designs of equipments, buildings and control systems are finalised after rigorous research by the R&D team ensuring high reliability and innovation. We manufacture these equipments at our state-of-the-art ultramodern manufacturing facility. Our infrastructure also incorporates modern quality testing facilities that enable us to meet both national and international standards. Furthermore, we also provide effective after sales service to our valued clients to ensure trouble free functioning of the plants.SAKA Engineering Systems uses CFD (Computational Fluid Dynamics) Analysis method to test and ensure optimal performance equipments. This is done by our highly qualified inhouse team of engineers in our own CFD Analysis Facility.Our Objectives

wood chips dryer - sunco machinery

wood chips dryer - sunco machinery

Wood Chips Dryer Detailed Description: Wood Chips Drier is one type of rotary drum dryer which is well know as "workhorse" in the drying industry. Wood Chip Dryer from Sunco Machinery can reduce the wood chips moisture content from 40-55% to below 10% according to the customers' request. Why need to dry wood chips ? heating value of dry wood in average 19 MJ/kg,different forms of wood fuels, e.g. split billets,wood chips and pellets, saw dust, bark, etc.moisture lowers the net heating value of wood chips. At harvest the moisture content of wood isaround 50 % (total weight),to evaporate 1 kg of water takes about 2,5MJ/kg H2O (0,8 kWh/kg H2O),e.g. 2 kg of wood chips, moisture content 50 %,= 1 kg dry-matter of wood + 1 kg water net heating value (19 2,5) MJ 16,5 MJ 8,25 MJ/kg of fuel. Moisture content affects greatly on netheating value of wood fuel (see tables 1 & 2 ): In practice the heating effect of small-scaleboilers decreases even more. --- the total efficiency of the boilerdecreases rapidly when the moisture contentrises (boiler tests are usually made with fuel that contains 30 % or less moisture/water) --- moisture content decreases conversionefficiency into energy and increases gaseousemissions (incomplete combustion) --- when using dry fuels the boiler stays cleaner,malfunctions and need for maintenancedecreases uptime increases. As a result, in order to increase the calorific value of the wood chips, we have to find ways to reduce the moisture content of wood chips to be about 20%. Thewood chip drying machineof Sunco Machinery can successfully to solve this problem. And it can use waste heat or normal fuel to generate hot air for the wood chip drying system. Wood Chips Dryer Working principle: Wood Chips Dryermainly consists of a horizontally inclined rotating cylinder, air duct tube, hor air furnace, highpressuredraught fan, electric control box, etc. Wet wood chip are fedat the feed inlet hole, and discharged at the dischaging hole.It is direct-type heated rotary dryers, hot gases move through the cylinder in direct contact with thewet wood chips, either with or against the direction ofthe wood chips' moving direction. The cylinder is equipped with lifting plates which lift the wood chips, and shower it up anddown through the hot flue gas. Wood Chips Drier Advantages: Reasonable structure; High heat and drying efficiency; Low energy consumption; Fast drying, large processing capacity; Environment friendly, stably working situation, etc. Capacity ofWood Chips Dryer: Sunco Machinerycan design and supply the Wood Chips Dryer Machine for the customers specially according to the information as follows: 01. Usual size (Length x Width x Thickness) (mm) of wood chips ? 02. Loosen bulk density (kg per cubic meter) of wet woodchips ? 03. Initial moisture content (%) of wet woodchips ? 04. Output moisture content (%) of dry woodchips needed ? 05. Input Capacity (ton per hour) needed ? 06. Prefered fuel such as waste wood, coal, diesel, or natural gas, etc ? 07. Other special requirements if have ? For detail and price of Wood ChipsDryer machine, please refer to: Email:[email protected] Mobile: Video:https://www.youtube.com/watch?v=i2GiO1HLn0A https://www.youtube.com/watch?v=qdIU7fWnUOk

Wood Chips Drier is one type of rotary drum dryer which is well know as "workhorse" in the drying industry. Wood Chip Dryer from Sunco Machinery can reduce the wood chips moisture content from 40-55% to below 10% according to the customers' request.

At harvest the moisture content of wood isaround 50 % (total weight),to evaporate 1 kg of water takes about 2,5MJ/kg H2O (0,8 kWh/kg H2O),e.g. 2 kg of wood chips, moisture content 50 %,= 1 kg dry-matter of wood + 1 kg water net heating value (19 2,5) MJ 16,5 MJ 8,25 MJ/kg of fuel.

Wet wood chip are fedat the feed inlet hole, and discharged at the dischaging hole.It is direct-type heated rotary dryers, hot gases move through the cylinder in direct contact with thewet wood chips, either with or against the direction ofthe wood chips' moving direction. The cylinder is equipped with lifting plates which lift the wood chips, and shower it up anddown through the hot flue gas.

sand preparation equipments, rotary sand driers, fluidized sand coolers, manufacturer

sand preparation equipments, rotary sand driers, fluidized sand coolers, manufacturer

Ganesh rotary sand drier is specially designed to improve the quality of sand which ultimately reflects in quality and economy of castings. Moisture is removed from sand effectively.Ganesh sand drier is sturdy in design and rigid in construction. The drum body is specially designed to withstand high temperature of firing unit. To avoid the heat loss drum is wrapped with asbestos sheet. This machine is designed to for maximum sand drying capacity in minimum time. The sand is conveyed from one side to other with fin type screw conveyor. The drum is rotated on rollers. Requires less floor space and minimum oil consumption. Cone type sand drier and double drum type sand drier are also available.

Ganesh drum type sand Siever is intensively used in large and medium type foundry.The drum is fabricated and mounted on two rigid frames. The drum is wrapped with required M.S. mesh sieve. Sieve is replaceable.

Ganesh portable vibratory sand Siever is specially designed for small foundries. The salient feature of this machine is that it can be moved easily moved at any corner of foundry. The pan is suspended and vibrated with unbalanced weight. The pan is designed in such a way that sieved sand goes in one direction and unsieved sand goes on other side.

Ganesh 2 deck and four deck sievers are designed to sieve two or four different grades of sands. These are special machines manufactured as per customer requirement. Pan is designed to ensure that no mixing of grades is possible.

Ganesh sand Muller is designed for mixing of heterogeneous mass of two or more dry or wet material into homogeneous uniformly blended and bonded product. This machine is sturdy designed made from heavy channels and plates. The rollers are spring loaded to adjust mulling pressure.

Ganesh portable sand aerator is most useful in all foundries to give high flowability to sand. The sand is sheared by strips mounted on endless belts. The drum is rotated in ball bearings so as to give smooth operation. The sand is fed in hopper and then it passes on endless belt which throws away with high speed.

Ganesh sand mixer is proven design. Specially designed s- shaped blades ensures that sand mixing takes place in minimum time. Ganesh sand mixer blades are exchangeable. These blades are hard spot welded which prevents the blades from wear. Weighing and mixing of material are automatically controlled. Ganesh co2 sand mixers and Ganesh no-bake sand mixers are also available

Ganesh intensive sand mixer is specially designed for mixing core sand and similar materials. The s type impellers are fabricated and hard spot welded. The wear plates are exchangeable. Pneumatic door opening is provided. This is advanced design for big and small foundries.The breakers are also provided to break the heterogeneous mass. Ganesh co2 sand mixers and Ganesh no-bake sand mixers are also available.

1 ton per hour alfalfa rotary dryer plant for sale

1 ton per hour alfalfa rotary dryer plant for sale

Fresh alfalfa moisture content is between 70 ~ 85%, and storage performance is very poor, the safety storage water about 14%. This is a 1 t/h alfalfa rotary dryer plant help our customers achieve alfalfa grass storage.

Alfalfa is high yield and good quality of leguminous grass, rich nutrition. The crude protein in dry matter quantity that is one half of bean cake, 1 ~ 1.5 times higher than corn, and alfalfa at the same time are rich in carbohydrates, minerals and vitamins, and other important nutrients, known as the "king of the grass" reputation; And alfalfa high yield (worthy of the hay production 7.5 tons per hectare); which has a broad international market.

used sand dryer for sale. huarui equipment & more | machinio

used sand dryer for sale. huarui equipment & more | machinio

Industrial Sawdust Sand Sludge Sea Salt Single Cylinder Rotary Dryer Product Description Packaging & Shipping Brief introduction: 1.It can be used to indirectly heat or cool paste, granular, powder, and paste ma...

The Rotary Drier is widely used in the field of building materials, metallurgies, chemical industry, cement and so on. The Rotary Drier is widely used in the field of building materials, metallurgies, chemical in...

1.This zircon sand washing plant is widely used for zircon sand recovery in Nigeria. 2.Most zircon sand miners get the 60%-65% zircon sand from this flow and make lots profit. 3.This flow is including: Feeding-gr...

Product Features 1. Flexible Operation The operating parameters can be changed according to the nature of the material, and the stable material curtain makes the heat exchange more sufficient. 2. Various Drying M...

Product Features 1. Flexible Operation The operating parameters can be changed according to the nature of the material, and the stable material curtain makes the heat exchange more sufficient. 2. Various Drying M...

Usage: This machine is suitable for heating. The heating method uses up and down heating, dual use of coal and electricity. Stainless steel chain plate structure is inside of the machine. Oven chain, curtain rods...

Rotary dryer is used of drying sand, coal, sludge, coal slurry, brown coal, fly ash, gypsum, clay, kaolin, grain(corn, wheat),mineral powder, slag, iron powder, mill scale, sawdust/woodchips, chicken manure, feed...

Three Cylinder Silica Sea River Quartz Yellow Sand Dryer Equipment Product Description 1.Three pass river sand drum rotary dryer adopts the latest European energy saving technology,clamp type structure. 2. Intern...

Small Tumble Dryer Industrial Rotary Drum Drying Equipment Coal Slurry Sawdust Saw Sand Dryer Product Description 1.Three pass river sand drum rotary dryer adopts the latest European energy saving technology,clam...

Industrial silica sand Browncoal wood sawdust rotary drum dryer machine, three cylinders drum dryer price Baichy three drum dryer three cylinder dryer for hot sale -- Introduction Three-cylinder rotary dryer is m...

Sand dryer rotary iron ore dryer Product Description The tumble dryer has large processing capacity, low fuel consumption, and dry Drying costs are low. The dryer has the characteristics of high temperature resis...

Briefintroduction: 1, Application: The machine is for wool washing, remove fat, sweat, grass and sand. It's rather first selection for raw wool washing machine. 2,Whole equipment list : 1 . B031-152 Wool feeding...

Product Description Product Application: Since sand with lower water content is well needed and sold in the market, we developed a new series of dewatering screen. The TS dewatering screen is mainly used for coar...

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.

techno-economic and environmental evaluation of biomass dryer - sciencedirect

techno-economic and environmental evaluation of biomass dryer - sciencedirect

The pros and cons of various types of biomass dryers have been documented in this paper. Using dry biomass significantly reduces the cost of handling, transportation and pyrolysis. The main choices for drying biomass are rotary dryers, flash dryers, stationery bed dryers and fluidised bed dryers. The drying medium can be hot air, hot air mixed with steam, and/or superheated steam. A typical example for wood chip drying using a financial model is described, including the environmental performance. The energy requirements and greenhouse gas emissions have been estimated for drying biomass. From this study, it is evident that increasing temperature will decrease drying time and increase throughput but not necessarily decrease the drying cost. This is due to higher energy use and higher cost of capital inputs such as loading/unloading and heat plant. Thus, low drying temperature can be used if throughput is not a key issue for an operation. The global warming potential of the biomass drying process 9.2kg CO2-e/t of oven-dry biomass. This assumes that wood waste is used as fuel and drying is on a moving belt dryer. If this dry biomass is used in a power station as fuel for steam boiler, there is a significant reduction potential of CO2 emission from a typical black coal-fired power plant due to fuel switching. This assumes that trees are planted to produce this biomass sustainably. Environmental impacts of any dryer type should be considered for selection in addition to its traditional techno-economic performance.

hemp dryers - vulcan drying systems

hemp dryers - vulcan drying systems

MENUMENUProducts POPULAR DRYERS Hemp DryersFrac Sand DryersPaper Pulp Dryers SYSTEMS Direct Fired Drying SystemsDrill Cuttings SystemsMunicipal Biosolids SystemsTank Bottom Systems DRYING EQUIPMENT Used Drying EquipmentNew Components Reconditioned Portable Drying System ServicesTechnologiesApplicationsAboutCareers

The Vulcan Drying Systems Hemp Drying System is custom-designed and manufactured to improve a customer's individual drying needs. These drying systems consist of a correctly sized drum and a burner mounted in a concurrent configuration. Vulcan Drying Systems Hemp Drying Systems are designed specifically to dry up to 10 tons per hour of hemp with an output moisture content between 10-12%.

Chopped hemp is fed into the rotary dryer by a feed conveyor. The dryer dries at low temperature by mounting a burner to a long combustion chamber to prevent direct contact with the burner flame. The burner flame is also cooled by a manifold of forced ambient air that passes through the combustion chamber as well. After passing through the dryer, the dried product is discharged to a transfer conveyor for further sorting, separation and processing. The vapor from the process is pulled through a large negative pressure chamber at the exit of the dryer to allow additional product drop out. Finally, the vapor is pulled through a cyclone or a baghouse to eliminate further airborne particulates.

The workhorse of the Vulcan Drying Systems Hemp Dryer is the heavy-duty, low-temp, direct-heating rotary drum dryer. The low-temp dryer is extremely energy-efficient and can be configured to utilize a variety of fuels to perform the drying process. Our single-pass system is a simple, low-cost method of producing a marketable product from biomass material. Low temperature is maintained by mounting a burner to a long refractory-lined chamber. Auxiliary air is added in the chamber to keep the temperature levels low.

On discharge, all processed material is sent to the client mandated location for re-purposing and re-sale. However, the Vulcan Drying Systems Hemp Dryer doesn't stop there. This system ensures that all particulate matter is removed in a safe and secure fashion.

Drying is an essential part of processing hemp for CBD oil extraction, but the process can take a significant amount of time and effort. Hemp biomass often has a high moisture content, even up to 85%, which has to be reduced to an acceptable level in order to extract quality CBD oil. With the proper equipment, you can dry hemp correctly and efficiently, resulting in a product ready for CBD oil extraction or other industrial or medical purposes.

The Vulcan Drying Systems Hemp Drying System is custom-designed and manufactured to improve a customer's individual drying needs. This system consists of a correctly sized drum and burner mounted in a concurrent configuration. Vulcan Drying Systems Hemp Drying Systems are designed specifically to dry up to 10 tons per hour of hemp with an output moisture content between 10-12%.

Hemp is created through the agricultural process of growing and harvesting hemp plants. Hemp is an organic product and causes no harm to the environment or public health. However, there can be some negative impacts on the surrounding environment if pesticides or excessive water are used during the growing season.

Regulations on hemp production vary by state. All producers should check with their state prior to growing or processing hemp. The growth of hemp for marijuana is only legal in some states, while the growth of hemp for CBD oil and other products is strictly regulated at the state and federal level. See more about the USDA regulations on hemp production here.

Hemp is in high demand and can be used in a variety of products, but is especially popular for natural medical products for the treatment of anxiety, depression, seizures and even assistance with the negative effects of cancer treatments. Hemp with high CBD content has a variety of industrial and commercial issues that make it a valuable product.

A wide variety of marketable products can be made from hemp and CBD oil, including paper, rope, textiles, biodegradable plastics, health food, natural treatments and even some construction materials and fuel.

Thorough and fast drying of hemp results in a higher quality product for processing or market. Our drying systems allow growers to dry hemp much faster, resulting in a product ready for CBD oil extraction or other industrial or medical purposes.

Since hemp was legalized in the 2018 Farm Bill, interest in growing industrial hemp for CBD production has skyrocketed. When properly dried and processed, CBD oil can be extracted from the hemp plant for use in a variety of products. While most people associate hemp only with medicinal uses, the material can also be used in textiles, paper, construction, and even fuel.

The U.S. Hemp industry produced approximately $820 million in revenue in 2017 and is expected to grow at least 14% by 2022, while the global hemp market is expected to reach over $10 million by 2025. This rapidly growing market offers a promising option for farmers looking for a product with constantly expanding potential.

head over heels for rotary drum dryers | 2014-02-11 | process heating

head over heels for rotary drum dryers | 2014-02-11 | process heating

Figure 1. Products that have nonuniform particle sizes such wood are good candidates for a rotary drum dryer. However, the flighting system would be different for the sample on the left than for the sample on the right.

Rotary drum dryers are the workhorse of the drying industry because of their capacity, efficiency and ability to adapt to new purposes. This article will discuss what a rotary drum dryer is, what applications a rotary drum dryer is best suited for, and common concerns and solutions regarding rotary drum dryers.

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-foot-diameter drums seem to be the largest practical size for manufacturing, transport and installation purposes. Depending on length, an 18-foot drum could evaporate 120,000 pounds per hour of water. If, for example, the product to be dried starts at 50 percent moisture-content wet basis (mcwb), this drum could handle 120 tons per 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-foot dryer drum is not the only option. Rotary dryer drums as small as 4-foot diameter can evaporate anywhere from 200 to 500 pounds per hour. Rotary drums much smaller than this have efficiency losses, so an alternate drying system may be more beneficial. Using the same example as above, with a product at 50 percent mcwb, a small rotary drum dryer can take care of 400 to 1,000 pounds per hour of product, or 1,680 to 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 corrosive materials. A basic carbon steel drum is designed to withstand inlet temperatures from 1000 to 1100F (537 to 593C). 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 that need to be broken up while others flow like water and need to be slowed down. Other pieces might be long and stringing and easily can get trapped. Different flighting designs can solve these and other problems.

With so many specialized dryers available today, it seems that every 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 can look at the flow characteristics of the material in question and determine what kind of flights are necessary, thereby converting the dryer to suit a new purpose at a smaller cost than buying a new dryer.

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

Products that have nonuniform particle sizes such wood are perfect candidates for a rotary drum dryer (figure 1). 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 shown in figure 1, 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 overdry 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 also can 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 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 shaking and vibrating. Some drums have been measured to continually be 0.25" wider than tall, flexing every time they rotate. 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 it breaks. However, given the right design, construction materials and fabrication techniques, a well-built rotary drum dryer should last more than 20 years without any major structural issues such as cracks in the shell or headplates.

Lack of versatility is another perceived issue associated with rotary drum dryers. The importance and flexibility of different flighting packages is often misunderstood in the industry. Many rotary drum dryers available today only have an option for one type of flighting package. To get the most out of a rotary drum, find a manufacturer 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, already discussed in this article, is by utilizing the right flighting package for your product.

The next method is through the use of exhaust gas recycle (EGR) also known as flue gas recycle (FGR) where 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 overdried or charred outside and wet inside. (Think of it like putting a burger on the grill when the coals are too hot.) Overdrying or charring the outside gives off volatile organic compounds (VOCs), which will cause a haze and bad smell outside the plant if a back-end cleanup system has not been utilized.

Not overdrying the outside decreases the chance of creating VOCs, which results in lower emissions. Another 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 overdrying, so lowering the inlet temperature will also reduce the potential for VOC emissions.

Rotary drum dryers are the workhorses 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, you can overcome any perceived problems and achieve effective drying.

Are your trunnion wheel shafts breaking? This is often caused by thrust in the system being applied to the trunnion wheels incorrectly, causing the shaft to fail. To correct this problem, the nature of the misapplied thrust should be investigated to determine how to correct the problem.

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Vacuum Heat Treatment is a comprehensive introduction and technical resource for vacuum processes and equipment, focusing on subjects that engineers, heat treaters, quality assurance personnel and metallurgists need to know.

Check out the June 2021 edition of Process Heating, featuring temperature uniformity optimization in process ovens and dryers, retrofitting a convection oven with gas catalytic infrared heaters, an equipment overview on convection and conduction heaters and much more!

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