PET Flakes Crystallizer and Dryer

PET is highly hygroscopic and absorbs moisture from the atmosphere. Tiny amounts of moisture can hydrolyse PET within the melt part, reducing molecular weight. PET should be dry just prior to processing, and amorphous PET needs crystallization prior to drying so that the particles don’t stick together as they’re going through glass transition.

Hydrolysis can occur due to moisture and this often can be seen as a reduction in the IV (Intrinsic Viscosity) of the product. PET is “semi-crystalline”. When the IV is reduced, the bottles are more brittle and tend to fail at the “gate” (injection point) during blowing and filling. It is very possible that due to the initial moisture level in the resin, and the amount removed during vacuum that a significant amount of moisture still remains as it is reaching its melt phase in the extruder.

In its “crystalline” state it has both crystalline and amorphous portions in its molecular structure. The crystalline portion develops where the molecules can align themselves in a very compact linear structure. In the non-crystalline regions the molecules are in a more random arrangement. By insuring that your crystallinity is high, prior to processing, the result will be a more uniform and higher quality product.

Another thing to consider is the number of times the PET has been processed. Each time the PET is processed there is a reduction in IV. Therefore, PET that has been used to make a bottle, recycled and used again, does not have the IV of the original bottle. Each time the bottle is recycled, the IV is further reduced. This is why a percentage of virgin resin is often added to increase the products properties.

Flake size is determined by the grinder. I have seen customers who think that ¼ inch is perfect and those who think ¾ is best. The smaller the flake the more fines will be produced and the better the material will flow in the drying hopper and vacuum chambers. Extremely fine grinds tend to lead to higher pressure drop in the hopper and can cause reduced air flow and uneven distribution. Large grinds can sometimes cause uneven hopper material flow.

60% regrind or more is common in extrusion. Most bottle applications are less than 10% for food and beverage and less than 30% otherwise. It depends on the source of the regrind and the end product. Blow molding is more difficult when you use material with different heat history and IV. Fines can also cause processing problems.

The disadvantage of using regrind versus virgin resin is that regrinds have a heat history and have a significantly lower IV (Intrinsic Viscosity). Lower IV in the finished part causes it to be more brittle/less flexible. The second disadvantage is that there tends to be more “yellowing” in regrind materials that can cause a color or haziness issue.

It is more important to remove the moisture than to heat it. However, it is very difficult to measure moisture on-line in a process so time and temperature is generally used to set the moisture level achieved. For instance, with PET processing, it is generally assumed that if there is 4-6 hours in the drying hopper at 325-350° F, the moisture will be reduced to less than 50 ppm.

After the PET has been formed into a sheet, there isn’t typically any additional pre-conditioning required before thermoforming. The sheet will undergo heat in the thermoforming and as long as it doesn’t approach the melt temperature the process just changes the shape of the already formed sheet and the stresses imparted to the sheet tend to give it strength.

In general, crystallizing master batch can have a lot of drying/crystallizing issues. Unless the quantity is so large that you can afford to purchase a crystallizer, buying crystallized master batch is probably preferred.

We at KERONE have a team of experts to help you with your need for PET flakes crystallizer and dryer in various products range from our wide experience.

How to compost food waste and use as organic fertilize

Composting is the natural process of decomposition and recycling of organic material into a humus-rich soil amendment known as compost. Food waste is composed of organic matter which can be used for composting to make fertilizer. It is an effective and eco-friendly way of disposing of food waste in your kitchen.

By using leftovers and other food waste, you can convert these smelly items from the kitchen waste into a highly organic product rich in nutrients that you can use to grow vegetables or flowers with it. Things like paper, twigs, and leaves are rich in carbon while grass, coffee, and tea grounds, fruit, and vegetables are rich in nitrogen. The proper mixture is key to good compost.

Why use food waste as fertilizer?

Food waste is a major challenge in the present world, tons of food is thrown away in the garbage. We could use all the food waste and prepare compost out of them which can be used as organic fertilizer. This way we save the earth from the pollution caused by food waste and also do something productive.

Food waste is unique as a composting agent; it is the main source of organic matters. Fruits, vegetables, grains, coffee filters, eggshells can be composted.

How to prepare the compost:

  • Collect and separate your edible kitchen waste (vegetable peels, fruit peels, and small amounts of wasted cooked food) in a container.
  • Now collect some dry organic matter like dried leaves, sawdust, and wood ash in a small container
  • Take a big container or earthen pot or a bucket and drill 4 5 holes around the container at different levels to let air inside.
  • Now fill the bottom of the container with a layer of soil.
  • Now start adding food waste in layers alternating wet waste (food scraps, vegetable, and fruit peels) with dry waste (straw, sawdust, dried leaves).
  • Cover this container with a plastic sheet or a plank of wood to help retain moisture and heat.
  • Check the container every few days and if you think the pile is too dry, sprinkle some water so that it is moist.

You can also add wood ash and sawdust to the compost to help speed up the composting process. Vegetables and fruit peelings are the number one food remnants you should use. To come up with a nutrient-rich fertilizer, you need to add some natural waste to your compost like the grass clippings and leaves from your lawn.

The next is drying and cooling process, organic fertilizer drying and cooling usually can be combined together. After granulating, the organic granules are often with high moisture and heat, for making better quality organic fertilizer, the content of them should be reduced to a certain percentage.

Rotary drum fertilizer dryer is used to dry organic fertilizer granules and after drying, the moisture content can be decreased to 10%. And about organic fertilizer granules cooling, fertilizer rotary drum cooler will help remove the heat for granules. Granules enter from the inlet and cooling air enter from outlet join adversely. The fertilizers of low temperature will be discharged through outlet after transferring the heat to the cooling air. It can greatly improve cooling rate.

We at KERONE have a team of experts to help you with your need for organic fertilizer in various products range from our wide experience.

Heat and Mass Transfer Modeling for Fruit Drying

Drying is an efficient technique for fruit storage/preservation. Drying may retain quality end product that is difficult, because all fruits are variable in structure, so, heat and mass transfer modeling (operating parameters) is a helpful technique to deal with it. This could only be done by selecting the proper sort of drying equipment and understanding the science behind the drying method as well as thermal properties of fruit. Drying method have several effects on different heat sensitive fruits elements and equipment (sensors etc.) also that result into increase in maintenance price, diffusion rate goes to critical limits etc. Because, choice of an acceptable drying technique and equipment is most significant regarding product quality and its amount. Modeling of a drying method considering different drying parameters and their effects on final quality of product and economic importance are mentioned here. we must always have information regarding the drying mechanics. So, that knowledge of heat and mass transfer method for fruit drying helps to identify best operating conditions and saves the most quantity of energy.

Food is the necessity for mankind as it provides energy, growth, and repair to the body. Fruit is an agricultural commodity and most of the agricultural commodities are seasonal. Fruits are present in bulk amount during their season, but during the offseason, this seasonal fruit is unavailable because it gets wasted due to improper storage techniques. About 40% of the fruits production in Pakistan was wasted due to improper handling and preservation techniques. Fruit production in Pakistan in 2016–17 is 5,685,000tons and 440,000tons were exported and 2,274,000tons get wasted. To make food secure one should reduce post–harvest losses. Fruits get wasted due to improper harvesting, transportation, processing, and preservation methods. Agricultural products are sometimes categorized on the basis of water contents present in them; perishable, semi–perishable and non–perishable products. For few days fruit can be save according to its shelf life (perish ability value), but after these days sensory parameters like taste, flavor, texture, color degrades and finally, fruit becomes unable to eat. In order to prolong its shelf life for months, dry it by proper means and in a hygienic environment.

Drying is a unit operation that is carried out to preserve fruit, instead of a unit process, which is a chemical process. Drying is the removal of moisture from fruit products up to a certain level and dehydration is the bone–dry condition of that product. Drying is a physical process performs to stabilize fruit as biological changes in fruit lead to deterioration. Cost of transportation decreases and handling becomes easy as its weight and volume reduces, consumption is followed with calculated rehydration.

Objectives of drying:

Drying slows down the microbial and enzymatic activity by lowering water activity. Apple has a water activity of 0.85–0.95 and drying reduces water activity to about 0.5.2 Fruits are dried due to many reasons; to consume seasonal fruits and to export these products in non–production areas of such fruits. Dried fruits enhance the taste of food products when used as food formulations in many food products such as ice creams, frozen desserts, sweets, bakery products, baby foods, jellies, crackers, horseradish, miscellaneous, and sauces etc.

Heat transfer:

Temperature difference is the driving force for heat transfer. So, heat transfer exchanges thermal energy from high concentration to low concentration between physical systems. There are three modes of heat transfer namely, conduction, convection, and radiation.

Specific heat:

Quantity of heat required to change a unit temperature of unit mass of product, without changing in its original state.

Thermal conductivity:

Quantity of heat is conducted through per unit thickness, per unit time of the product, if two materials having a unit temperature difference.

Thermal diffusivity:

Ratio of thermal conductivity to specific heat and density.

Mass transfer:

Mass transfer is the movement of chemical species from high concentration region to low concentration region and the presence of these two regions are necessary, but fluid flow moves from one location to another and occurs on a macroscopic level

Drying process:

Drying is a coupled heat and mass transfer mechanism. There are different types of drying units/machinery used in this modern era. Food Engineers are working very hard to develop more efficient methods for drying of perishable agricultural products that least alter its quality.

Fruit in its biological structure is variable and complex so every fruit needs a different model to dry it by retaining quality, which is challenging. So, modeling and simulation is a useful technique to deal with it. Mathematical model based on heat and mass transfer is used to study the behaviour of drying operation.

Fruits due to high water content and heat sensitive compounds in it are tough to dry, by maintaining quality. Understanding heat and mass transfer process and its parameters are mandatory for the drying processes, which minimally have an effect on the sensory and different quality parameters of edible fruit. Calculations for heat and mass transfer greatly help to optimize the efficiency of drying unit, drying rate and as well as reduces energy consumption, it additionally helps to identify the most appropriate operating conditions.

We at KERONE have a team of experts to help you with your need for Heat Transfer in various products range from our wide experience.

Evaluation of food drying with air dehumidification system

The main challenge in global food demand is how to obtain high quality dry food products in efficient processing. The dry food or its extract can be a good option due to the long life storage and consumer convenience. To realize this preference, drying process offers the major role corresponding to the moisture removal from wet product. In general, the agriculture and food products with high moisture content (vegetables, herbs, starch products) are dried at low to moderate temperatures to conserve the valuable ingredients (protein, vitamins, enzymes, oil) as well as physical appearance such as color, and texture.

Meanwhile, the modern drying technology has been widely developed with attractive results in the product quality aspects. However, the efficient dryer development has been scared. For example, the energy efficiency in freeze and low temperature dryers is lower than that of a conventional convective dryer. This is due to the low value of driving force for moisture transfer and higher latent heat of moisture evaporation. Recently, the energy usage has become an important issue with respect to the limitation of fossil fuel supply. On the other hand, the availability of biomass as side product of agriculture crops has not been intensively used as renewable energy resource in drying process.

Conventional dryer with sunlight is very advantageous due to its low energy cost, and environmentally benign. The dryer has been widely used for a long time in various sectors, such as agriculture, fishery, forestry, and herbal medicine products. Unfortunately, the uses of this dryer is also restricted by main drawbacks of this dryer such as sustainability and product quality, which are rooted from its climate dependent.

Thus, the application of dryer with pre-dehumidified air for various food or agriculture crops drying can be an attractive option.

Materials and Methods

Based on the model and simple experimental test, the adsorption dryer with zeolite has shown attractive performances. In this study, the dryer was tested in wider range application for agriculture crops drying. This work consisted of two main steps. Firstly, the two types of dryer (fluidized bed and tray dryers) were constructed in laboratory scale equipped with an air dehumidification section with zeolite. The dryers were used for different application (fluidized bed dryer for paddy drying, and tray dryer for onion drying). Secondly, the dryers performances were evaluated based on product quality, drying time, and or/ heat efficiency. The heat efficiency was estimated referring to the total heat used for evaporated water divided by the total heat introduced in the system. The product quality was analyzed based on physical properties as well as important substance content.

Paddy Drying

The paddy drying system was designed as a fluidized bed dryer. The dryer was equipped with a blower to deliver air for the fluidization process. Initially, ambient air at a relative humidity (RH) of 70 – 80% and temperature about 30°C was flown to the heater at a velocity of 4.0 m.s-1. The air was heated up to dryer temperature (designed as 40°C). The air was then used for paddy drying with initial moisture content of about 25% (w/w).

Onion Drying

Generally, onion was harvested from a farm with 88 – 92% moisture content. After drying, the average moisture content in the onion was desired to be 80 – 85%. The onion drying was conducted in tray dryer completed with zeolite, as presented. The fresh air was heated up to 50°C by an electric heater. The air was used for onion drying with addition of a zeolite pack.

Heat Efficiency Estimation

The paddy and onion drying were continued with rice husk combustion as a heat source. The rice husk with combustion heat value up to 15 was obtained as a side product of rice mill industries. Theoretically, with latent heat of moisture evaporation about 2.5 , one kilogram of rice husk can evaporate 6 kg of free moisture.


The air dehumidification has been applied for tray and fluidized bed dryers. The dryers were used for paddy and onion drying. The zeolite as moisture adsorbent performed well. Therefore, the air may be significantly dehumidified. Based on product quality retention, drying time estimation, and heat utilization, the air dehumidification affected the drying performance positively. The fluidized bed and tray dryers were then operated with rice husk as a heat supply. Results showed that the heat efficiency can achieve around seventy fifth. This performance may be promising for sustainable food drying development.

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Validation of Dry Heat Sterilization Processes

Dry Heat Sterilization is a sterilization process that can be used to terminally sterilize health care products, medical devices, equipment, components or bulk active pharmaceutical ingredients by exposing the items to a temperature of ≥ 160°C for a defined time.

For heat stable items, such as glassware or stainless steel equipment, a dry heat sterilization cycle can be run at 250°C to remove bacterial endotoxins from the items. This process is also referred to as Depyrogenation. Bacterial endotoxins are fever inducing compounds, or pyrogens, that are released when the cell walls of gram negative bacteria such as Escherichia coli are destroyed.

Validation of dry heat sterilization cycle(s) is required by ANSI, AAMI, ISO, USP and the FDA to ensure that all items that are required to be sterile or pyrogen free are able to consistently and reliably be sterilized to reduce the chance of introducing or spreading an infectious microorganism or pyrogen.

Installation Qualification (IQ)

Validation of a dry heat sterilization cycle begins with the execution of the Installation Qualification (IQ) protocol on the equipment (oven, tunnel, or cabinet) which will be used to perform the dry heat sterilization. The IQ protocol verifies and documents that the equipment is installed correctly and meets all of the manufacturer and user requirements. During the execution of the IQ protocol, the equipment drawings, calibration status of critical instruments, instrument and valve information, utility information, and standard operating procedures for the equipment are all confirmed.

Operational Qualification (OQ)

The next step in the validation of a dry heat sterilization cycle is the execution of the Operational Qualification (OQ) protocol of the equipment. The OQ protocol verifies and documents that the equipment is programmed and operating correctly, and is able to meet all of the manufacturer and user requirements. Execution of the OQ protocol involves verifying the parameters/settings (e.g. general system options, cycle length, airflow, sterilization temperature) of the dry heat sterilization cycle(s). It also ensures that the system alarms are operating correctly, that the equipment is functioning properly (e.g. verification that the control system functions as specified by the equipment manufacturer or system interlocks), and that the equipment is able to achieve and maintain the required sterilization conditions during the dry heat sterilization cycle(s).

Performance Qualification (PQ)

The execution of the IQ and OQ protocols covers the validation of the equipment. In order to validate a dry heat sterilization cycle, a Performance Qualification (PQ) protocol must be executed. The PQ demonstrates that the dry heat sterilization cycle(s) can repeatedly achieve the required Sterility Assurance Level (SAL) 1. In order to confirm that the necessary SAL can be reached, the dry heat sterilization cycle must be temperature mapped.

Temperature Mapping

To perform a temperature mapping, data loggers are placed throughout the equipment chamber (distribution data loggers) and the load being sterilized (penetration data loggers). In order to temperature map a depyrogenation cycle it is sometimes necessary to use thermal barriers to protect the data loggers from the extreme heat. All of the data loggers used should have at least a 3 point NIST-traceable calibration performed prior to use.

Kerone have the knowledge and experience needed to help you complete the IQ/OQ/PQ for your dry heat sterilization and depyrogenation equipment and processes. Our experts have your back, so you can rest assured that your dry heat sterilization or depyrogenation cycles are being completed – optimally, reproducibly, and consistently.

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Effect of Drying Characteristics of Garlic

Natural sun drying is one of the most common ways to preserve agricultural product. the most purpose in drying farm manufacture is to reduce its water activity from the harvest level to the safe storage level in order to increase its shelf life. Once the product has been dried, its rate of deterioration because of respiration, insects, and microbial activity and biochemical reactions should diminish resulting in maintenance of quality of the stored product. It does improve bargaining position of the farmer to keep up comparatively constant value of his product. Drying reduces post-harvest losses and transportation prices since most of the water are taken out from the product throughout the drying method. In India, sun drying is the most typically used technique to dry the agricultural material like grains, fruits and vegetables. In sun drying, the garlic is spread in a very skinny layer on the bottom and exposed on to solar radiation, ambient temperature, wind velocity, relative humidity, initial moisture content, absorptive, exposure time and mass of product per unit exposed area.

Garlic is a bulbous perennial vegetable spice. The bulb is composed of pungent bolblets, commonly known as cloves. Garlic is a semi-perishable product. Due to lack of suitable storage and transportation facilities, about 30% of fresh crop is wasted by respiration and microbial spoilage. At times of shortages, India imports garlic of Chinese origin from Taiwan or via Nepal. Fresh garlic, dehydrated garlic flakes, dehydrated garlic powder and garlic oil is exported from India. India was once a leader in this field but is losing out to China in the overseas market. China has an edge over India in terms of both quality and quantity.

Food drying is one of the oldest methods of preserving food for later use. Food drying is a very simple, ancient skill. It is one of the most accessible and hence the most widespread processing technology. Sun drying of fruits and vegetables is still practiced largely unchanged from ancient times. Traditional sun drying takes place by storing the product under direct sunlight. Sun drying is only possible in areas where, in an average year, the weather allows foods to be dried immediately after harvest. The main advantages of sun drying are low capital and operating costs and the fact that little expertise is required. The main disadvantages of this method are as follows: contamination, theft or damage by birds, rats or insects; slow or intermittent drying and no protection from rain or dew that wets the product, encourages mould growth and may result in a relatively high final moisture content; low and variable quality of products due to over-or under drying; large areas of land needed for the shallow layers of food; laborious since the crop must be turned, moved if it rains; direct exposure to sunlight reduces the quality (colour and vitamin content) of some fruits and vegetables. Moreover, since sun drying depends on uncontrolled factors, production of uniform and standard products is not expected. The quality of sun dried foods can be improved by reducing the size of pieces to achieve faster drying and by drying on raised platforms, covered with cloth or netting to protect against insects and animals. In open sun drying, there is a considerable loss due to various reasons such as rodents, birds, insects and microorganisms. The unexpected rain or storm further worsens the situation. Further, over drying, insufficient drying, contamination by foreign material like dust dirt, insects, and micro-organism as well discolouring by UV radiation are characteristic for open sun drying. In general, open sun drying does not fulfil the quality standards and therefore it cannot be sold in the international market.

The major quality issues faced throughout garlic drying loss of flavour, discoloration and poor rehydration characteristics of the dried garlics. Garlic flavour and colour are usually perceived as important quality attributes. In drying, diffusivity is employed to indicate the flow of moisture from the material. in the filling rate amount of drying moisture removed is controlled mainly by molecular diffusion. Diffusivity is influenced by shrinkage, case hardening throughout drying, moisture content and temperature of the material.

Methods of Drying:

 Hot air drying

Hot-air drying of garlic slices in a common fixed bed method is unfortunately not suitable due to a significant decrease in the quality of dried product related to the fresh one. Applying high temperature (about 60°C) in a fixed bed drying causes an increase in drying period, energy consumption, color degradation and mass transfer.

Solar and Open sun drying

Recent efforts to enhance on sun drying have led to solar drying. Solar drying additionally uses the sun because the heat source. A foil surface within the dehydrator helps to extend the temperature. Ventilation speeds up the drying time. Shorter drying times reduce the risks of food spoilage or mold growth. it’s a complex operation involving heat and mass transfer which can cause changes in product quality. Physical changes which will occur include shrinkage, puffing and crystallization.

Infra-Red drying

Microwave and infrared (IR) drying are studied for achieving quick drying and reducing quality loss of fruits and vegetables. a mixture of hot air and microwave drying of osmotic dehydrated blueberries had similar or higher product quality compared with freeze-dried product with a lot of reduced drying time.

Fluidized bed drying

Thin layer drying properties of high moisture garlic sheets under semi fluidized and fluidized bed conditions with high initial moisture content (about 154.26% d.b.) were studied. Air temperatures of 50, 60, 70 and 80°C were applied to garlic samples. Among the applied models, Page model was the best to predict the thin layer drying behavior of garlic sheets.

Dried garlic Products

Garlic Powder: In Asian country thanks to lack of appropriate storage, transport and process facilities, significant losses are incurred both in terms of quality and quantity thanks to respiration, transpiration and microbiological spoilage. Through garlic is made abundantly and consumed as such, little efforts have so far been made to supply dehydrated garlic and garlic powder.


To obtain the dehydrated product of prime quality, the drying method should be specified it allows effective retention of colour appearance, flavour, taste and nutritive value, comparable to recent vegetables. The technique of drying is perhaps the oldest technique of food preservation practiced by human race for the extension of food period. The utilization of artificial drying to preserve agricultural commodities is increasing, making a requirement for a lot of fast drying techniques and ways that reduce the big quantity of energy needed in drying processes. Just in case of garlic is an antioxidant product used for many medicative purposes. New and innovation techniques that increase drying rates and enhance dried garlic quality are receiving substantial attention.

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Continuous Granulation and Drying Techniques Trends

The term “continuous” is applied to all production or manufacturing processes that run with a continuous flow. With that definition, continuous processing of solid dosage products in the pharmaceutical industry means starting the process from the synthesis of API to the final packaging of tablets or capsules 24/7 all year-round.

The pharmaceutical industry has been slow to adopt or even consider the concept of continuous processing, even though its value has already been proven in other industries—polymer, food, dairy, electronics, automobile and petrochemical/chemical—which have implemented fully continuous production processes for many years.

The pharmaceutical industry is also dominated by batch processes due to the smaller amounts that must be processed compared to other industries. The small material quantities available during the development stage also dictate the use of a batch process during the design phase of the formulation and manufacturing process, and these same batch-wise processes are often scaled up to production. Batch-processing equipment is the most flexible and convenient to use. There is reluctance from the industry to embrace continuous manufacturing because of the additional capital investment required along with the prospect of the current vast disposition of batch process equipment and staff training that would be required.

Continuous granulation

The granulation aspect is defined as “A unit operation of mechanical process engineering characterised by a combination with a change in particle size using pressure, solvent or binder.”

There are completely different techniques utilized within the industry to produce granulated product depending on the physico-chemical properties of the composition, intended product attributes needed, and therefore the access to the process technology needed to produce the dosage form.

Achieving the vision of continuous manufacturing of solid dosage, where product starting as API and ending up as a finished dosage form via wet granulation, will not happen immediately. To start you need to ensure that the necessary technology and skills are sufficiently available.

Much of the product quality should be achieved by designing an effective process at the design stage and supplemented, as needed, by additional in-process controls, monitoring and end product testing.

Many unit operations are intrinsically continuous and are well understood. For all remaining unit operations, equipment is accessible. Experiences with continuous wet granulation are positive. Opportunities to a adopt continuous method exist and may depend upon QbD approach, for that it’ll need a lot of advanced management systems with simple and more complex PATs. It should be realised that not all product or processes are manufactured with continuous granulation approach. each API will have to be evaluated for its capability to be a candidate for continuous granulation and a pertinent method will have to be developed for it.

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Drying System Temperature Control for a Large Format Textile Printer

In the digital giant format textile business, the drying system is one amongst the most vital subsystems within the printer. The objectives of this method are dry the media enough in order that there’s no transfer between the rolled media and also the following one, and to produce a hot air (airflow and temperature) within the print zone to reduce bleed and coalescence. And one amongst the most critical parameters within the dryers is that the management of the temperature uniformity on the scan axis within the print zone. A fine control of the temperature uniformity will increase the media versatility by enabling lower temperatures within the print zone whereas drying and increase the throughout capability level. Also improves bleed and coalescence and alternative image quality artifacts. In many printers, the drying system is based on convection with a hot chamber flowing hot air through several diffusers to the print zone.

In those drying systems, in most of the cases, the temperature uniformity can be achieved by separating the chamber in several modules. Each module controlled independently.

The main drawback resolved by this invention is that the improvement of the temperature uniformity in each the hot chamber and therefore the print zone on the scan axis. Within the dryer convection systems (that are using many local fan/heaters assemblies on the chamber) it’s difficult to confirm the uniform temperature and pressure. but if the variability of the temperature may be controlled and reduced then the temperature may be reduced (allowing wider media ranges) or the drying capability may be improved.

Prior solutions and their disadvantages to improve the temperature uniformity in the convective dryers, in the hot chambers, are:

Use a unique hot chamber along the scan axis:

There is a unique chamber and many fan/heaters assemblies on the scan axis and the temperature sensors may be implemented or not.

These are the main disadvantages of this configuration:

  • Large variability of temperature along the hot chamber and the print zone
  • When there is no temperature sensor in the chamber, the air temperature cannot be controlled. In some printers, the heater is only used to warm‐up the printer when the external temperatures are low.

Use several hot multi‐chambers along the scan axis:

There are several chambers (depending on the printer width) with a fan/heater/temperature sensor in each chamber. Each module can control de air temperature with temperature sensor. The main disadvantage of this configuration is the cost implied and the overall complexity. Each module required each hardware supports and PCA controls.

Increase the number of fans/heaters in a unique chamber along the scan axis:

Another option can be used to improve the temperature uniformity can be increase the numbers of fans/heaters assemblies along the scan axis. The more fan/heaters assemblies, better temperature uniformity can be got.

The main disadvantage of this configuration is the cost of the components

  • Fan
  • Heater
  • Temperature sensors

Advantages of the solution over what has been done before:

  • As stated before, this solution offers much better temperature uniformity along the scan axis hot chamber and reducing the cost and the complexity of the drying system.
  • Another important advantage is that, since the temperature sensor is not located in the hot airflow, the measurement variability is much accurate.
  • And another important advantage of the solution is that the whole assembly (fan + heater + air distributor + temperature sensor) serviceability is very good. All the components of the Drying System can be replaced very easily by service or even trained customers.

We at KERONE have a team of experts to help you with your need for Drying Systems in various products range from our wide experience.

Microwave Heating Systems for Sintering of Ceramics

Processing of ceramic materials has also a strong impact in the quality of the consolidated body, as it plays a key role in the resulting microstructure and, as a consequence, in its final properties. Advanced ceramic materials are commonly processed as powders and densified via a high-temperature process. Traditional processing techniques include hot isostatic pressing, mold casting, and sintering in conventional ovens. As ceramics require very high processing temperatures compared to metals and polymers, these processes tend to be very energy intensive and result in higher production costs to the manufacturers. Therefore, new technologies known as nonconventional sintering techniques, such as microwave technology, are being developed in order to reduce energy consumption, while maintaining or even improving the characteristics of the resulting ceramic material. This novel and innovative technology aims at helping industrial sectors lower their production costs and, at the same time, lessen their environmental impact. On the other hand, it is interesting and necessary to know and explore the basic principles of microwaves to advance in the development of materials that demand, every day more, the different industrial sectors.

High-temperature processes are required to consolidate ceramic powders, such as zirconia, alumina, silicon carbide, and so on, in order to obtain full densification of the material. Sintering is a common material processing technique aimed at fulfilling this task. The fundamental principle behind sintering consists in the thermal activation of mass transfer mechanisms when exposing a powder compact, known as a “green” body, to a high-temperature process, at a dwell temperature below the melting point of the material. The main purpose of sintering is to obtain a dense and resistant body with properties as close as possible to those of a theoretical, fully dense solid. However, in some cases, sintering can also be employed to adjust some of the properties based on the performance requirements of the material by not reaching full consolidation, such as in porous materials.

Two main types of sintering can be identified based on the nature of the process: liquid phase and solid phase. Even though the term liquid phase may suggest exceeding the melting point of the material, it is used to describe the addition of compounds with significantly lower melting points that aid in the consolidation of the main powder, which is regarded as the matrix phase and provides the main properties of the consolidated body.

The most important advantages of microwave sintering against conventional sintering methods are listed as follows:

  • Shorter sintering time and lower energy consumption;
  • Higher heating rates can be used.
  • Materials with a finer (Nano metric) microstructure with a high degree of densification and enhanced mechanical properties may be obtained due to the densification mechanisms involved;
  • Flexible due to the possibility of processing near-net-shape materials.

Microwaves have been used since the 1960s for heating purposes, particularly for food- and water-based products. Industrially, the use of microwave energy has become increasingly important because it represents an alternative to traditional with high-temperature processes. For example, so far, it has been employed in wood drying, resin curing, and polymer synthesis. The growing interest in industrial microwave heating is due mostly to the reduction of production costs resulting from lower energy consumption and shorter processing times.

Microwave sintering is considered a relatively new ceramic material processing technique that differs significantly from conventional sintering methods due to the nature of the heat transfer mechanisms involved. Hence, microwave sintering is classified as a non-conventional sintering technique. This method presents itself as a fast, economical, and flexible processing tool. Some of the most important advantages against conventional sintering systems include lower energy consumption and production costs, reduction of processing times, higher heating rates, and, in some cases, even an improvement in the physical properties of the consolidated material

In a general sense, microwave sintering increases the densification of the material at lower dwell temperatures when compared to conventional sintering, employing shorter times and less energy, and resulting in an improvement of the microstructure and mechanical properties.

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Drying Evaluation of Green Coconut Pulp

The world production of coconut (Cocos nucifera L.) was about 60 million tons in 2008 [1] — 85% in Asia, 8.5% in America, 2.9% in Africa and 3.2% in Oceania. Some of the coconut-based products are coconut oil, coconut water, copra and shredded coconut. Coconut products can also be found in beverages, cosmetic and toiletries products. The fresh or industrialized coconut water is much appreciated as a natural isotonic in Brazil. Its demand reaches 1.4% of soft drink market. A serious environmental problem has come up due to the inappropriate disposal of the husks. It is estimated that 350 million liters of green coconut water are consumed in Brazil every year and this consumption produces approximately 2 million tons of green coconut husk. 70% of the waste generated in Brazilian coastal urban centers is green coconut husk.

Green coconut husk is an excellent bio-material for the adsorption of Indigo Blue from textile industries. Other studies showed that the young pulp, in its very early maturation stage, presents interesting properties to be used as ingredient in ice cream, bread and cake.

Drying is another possibility to preserve the pulp that is discarded inside the husk. There are studies of drying coconut pulp in a CD and in a conventional fluidized bed. The low efficiency of CD and the lack of uniformity of the material, which favors channeling and agglomeration under conventional fluidization, led to the innovative-pulsed fluidization technique. Product quality was evaluated by Aw, enzymatic activity, color (parameter L), moisture content and texture analyses and the results were related to the process variables. Mathematical modeling of drying curves was done too.

Material and Methods :

Cabinet drying and pulsed fluid bed drying were performed to determine drying curves at 60, 70 and 80 °C. The initial and final Aw, moisture content and product luminosity, along with the visual aspect, were the parameters used to choose the best drying conditions. After the temperature was established, the variation of luminosity, enzymatic activity, Aw and texture were determined throughout the drying process.

Extraction of coconut pulp :

The green coconut used in this work was the Nana Griff kind (Dwarf Coconut Palm), grown in the Brazilian Northeast. Coconuts were sanitized with NaClO, and coconut water was drained. The husks were cut to have the pulp extracted. The pulp was then vacuum packed, frozen and kept at -20 °C until use. The analyses were performed at least in triplicate.

Sampling :

Due to the lack of product homogeneity, the samples for the analyses were obtained by fragmentation of various pieces of pulp, thus compensating for heterogeneity.

Moisture Content :

The moisture content was determined as described in A.O.A.C.

Luminosity :

The color analyses were performed using the colorimeter COLOR EYE XTH calibrated with 10 degrees of observation angle. The parameter used was the luminosity (L*). Browning of the material was inferred by the decrease in luminosity.

Fat Content :

Coconut pulp samples were ground in mixer, dehydrated and the fat content was determined by A.O.A.C.

Enzymatic Activity :

10 g of pulp were homogenized with 100 mL of 5% polyvinylpolypyrrolidone (PVPP) suspension. The homogenate was centrifuged at 1600×g for 15 minutes at 4 °C centrifuge. Polyphenoloxidase (PPO) and peroxidase (POD) activities were determined by spectrophotometric method using a UV-VIS spectrophotometer (Varian Cary 100). The PPO activity unit was defined as an increase of 0.001 min-1‡ ǻ$420 min-1‡ (ml sample) -1, using catechol as substrate. One POD activity unit was defined as the amount of enzyme capable of producing the conversion of 1 mmol of guaiacol per second under the test conditions.

Water Activity :

Water activity was measured by a hygrometer at 25 °C

Texture Analyses :

A Texture Analyzer with a 5-mm stainless steel cylindrical probe, in a load cell of 25 kg was used. A sample was placed on a hollow planar base and the force was applied by the probe at the constant speed of 1.0 mm.s-1 and 3 mm of penetration. Force deformation data were recorded. The maximum force and the number of peaks indicated the crispness.

Cabinet Dryer (CD) :

Cabinet Dryer was manufactured by Armfield, UK (Figure 1). It consists of a 28 cm × 28 cm square duct and a fan (a) with adjustable speed, which blows the air through electric resistances (b), controlled by a PID device. A 5.0 × 102 g layer of material was spread over the surfaces of two 20 cm × 20 cm trays in the chamber. The trays were held by an analytical scale (c) enabling mass measuring during drying. Air velocity was 2.1 m-s -1 in all tests.

Pulsed Fluid Bed Dryer (PFB) :

The gas distribution system is the distinctive feature of the PFB equipment. In the experimental set-up used in this work, the distribution of airflow is provided by two disks installed upstream of the drying chamber, on opposite sides of the gas distribution chamber. These disks are synchronized for they share a common shaft.

In case of high production yield, the recommended equipment is PFB dryer because it has great productivity by allowing the drying of large amounts of green coconut pulp. The results showed that the dehydration is a good way to make the green coconut pulp useful, increasing its shelf life and providing a snack-like product.

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