One of the key issues during the herbs drying process is the high moisture content, which is usually above 70%. During the processes and stages of picking, transportation, storage, and sales, if not handled properly, the materials are prone to deterioration and spoilage. Especially in tropical and subtropical regions, it is estimated that the loss rate can reach as high as 35%-45%.

The advantages of Naisda's drying and dehumidification machine drying solution

(1) The fully automatic control system can select the optimal drying temperature and humidity according to the process requirements of different products, completely solving the problems such as long drying time, high temperature and high energy consumption that exist in other drying methods. It has unparalleled superiority.

(2) The use of high-efficiency centrifugal fans ensures strong air force, uniform air flow distribution, and low noise. This enables the material to dry evenly and quickly.

(3) During the drying process, the material does not deform, crack, change color, deteriorate, oxidize, or become spoiled. The drying is thorough, and the rehydration property after drying is good. The loss of nutritional components is minimal. The storage period is long, and it more effectively protects the color, aroma, taste, shape and active ingredients of the dried product.

(4) The overall design of the unit is integrated, and it can be put into use by simply connecting the pipelines and power supply on site. The operation is convenient. Once the parameters are set, automatic control can be achieved, and the reliability is high.

(5) It requires less investment and yields quick results. It can be transformed using old kilns, garages, etc., and can be relocated to save land area. It is simple and convenient.

Constant-speed drying stage

The Naisida high-temperature dryer takes about 5-6 hours to heat up. After being placed in the curing room, the temperature reaches 60℃ within two hours. The purpose is to make the fresh sausages reach a uniform internal and external temperature within 2 hours. The long-temperature process is also a seasoning and fermentation process for the meat, which can control the meat from changing color or flavor. After preheating, the temperature is adjusted to 45-50℃, and the humidity is within the range of 50-55%. During this stage, the surface moisture has evaporated, and the color changes from the initial grayish-white to a light red. This stage is the color-changing period. Then, the sausages are taken out of the curing room, their heads and tails are reversed and hung, and they are sent back into the curing room to enter the second stage of drying process for the sausages.

2. Decelerated drying stage

The process lasts for 15 to 18 hours, divided into two stages: the coloring stage and the contraction setting stage. During the coloring stage, the temperature is controlled at 52-54℃ for 4-6 hours, with the humidity maintained at 45%. The sausage gradually changes from light red to bright red, and the casing begins to contract. To prevent the surface of the casing from forming a hard shell, after the coloring stage, ventilation cooling methods should be adopted for processing. The drying dehumidifier stops heating, the exhaust port is opened to discharge the hot and humid air, and cold air is added for cold air drying. This can cause the surface temperature of the sausage to drop rapidly, facilitating the migration of moisture from the internal part of the anus to the surface. The contraction setting stage is divided into two parts: the contraction setting stage. It lasts for 11-12 hours. During this period, the amount of water in the sausage's interior continues to decrease, and the sausage significantly contracts. The surface appears uneven. The overall shape is basically determined. In the middle stage of the contraction setting, that is, 5-6 hours after the start of the contraction setting, a half-hour cold air cooling method is adopted to alleviate the contradiction between surface water evaporation and internal water migration. By the end of the contraction setting, it is completed.

3. Rapid drying stage

In this stage, the determining factor that restricts the drying speed is temperature. To enhance the drying speed, the temperature is raised to 55-60℃, and the drying time is controlled at 22-24 hours. The relative humidity is maintained at around 35%, and the final drying moisture content of the sausage is controlled below 17%.

The moisture content of ceramic bodies generally ranges from 5% to 25%. The moisture of the body consists of equilibrium moisture and free moisture. Under a certain air condition, the limit of drying is to make the body reach the equilibrium moisture. The equilibrium water is a part of the bound water. Its amount depends on the temperature and relative humidity of the drying medium. When the bound water is removed, the volume of the body does not shrink, which is relatively safe.

Under stable drying conditions, there is a certain relationship between the surface temperature, moisture content, drying rate and time of the raw material. Based on the changing characteristics of this relationship, the drying process can be divided into three stages: heating stage, constant-rate drying stage, and decelerated drying stage.

Heating stage

Since the heat transferred by the drying medium to the surface of the clay body per unit time is greater than the heat consumed by the evaporation of surface moisture, the temperature of the heated surface gradually increases until it equals the wet-bulb temperature of the drying medium. At this point, the heat gained by the surface and the heat consumed by evaporation reach a dynamic equilibrium, and the temperature remains constant. During this stage, the moisture content of the clay body decreases and the drying rate increases.

2. Constant-speed drying stage

During this stage, the non-bound water is still being discharged. Due to the high moisture content in the green body, the amount of water evaporated from the surface determines how much water can be replenished internally. That is to say, the speed of water movement within the body (internal diffusion speed) is equal to the water evaporation speed at the surface and also equal to the external diffusion speed. Therefore, the surface remains in a moist state. When the constant-rate drying stage ends, the moisture content of the material drops to the critical value. At this point, although the internal part of the material still contains non-bound water, bound water begins to appear in the surface layer.

3. Decelerated drying stage

During this stage, the moisture content of the raw material decreases. The internal diffusion rate cannot keep up with the evaporation rate of surface moisture and the external diffusion rate. The surface no longer remains moist, and the drying rate gradually decreases. Due to the reduced heat required for surface moisture evaporation, the material temperature begins to gradually increase. The vapor pressure of water on the material surface is lower than the saturated vapor pressure at the surface temperature. This stage is for removing bound water. The material does not undergo volume contraction and does not produce dry waste. When the water evaporation rate of the material decreases to be equal to the equilibrium moisture content, the drying rate becomes zero and the drying process stops.

The key points to consider in drying seafood

1. Temperature - The drying of seafood generally requires a relatively low temperature to be carried out to prevent high temperatures from affecting the quality of the dried products.

2. Humidity - The general moisture content of seafood is relatively high. Therefore, controlling the amount of moisture discharge is an important factor in determining the quality of the drying process. Additionally, since the moisture in seafood is contained in fats and oils, dehydration is more difficult, and controlling the dehydration speed is crucial.

3. Drying time - The drying process for seafood usually takes a relatively long time. Rapid drying would generally compromise the quality of the dried product.

4. Color - It is of utmost importance to maintain the color of dried seafood.

5. Circulating Air - For the drying of seafood products, a relatively large amount of circulating air is usually required, and the air velocity should also be relatively high to prevent water vapor from remaining on the surface of the materials.

Wood contains a certain amount of moisture. The amount of moisture in wood varies depending on the tree species, age of the tree, and the harvesting season. To ensure the quality of wood and wood products and extend their service life, appropriate measures must be taken to reduce the moisture content (specific humidity) in the wood to a certain level. To lower the moisture content of wood, the temperature of the wood must be increased, causing the moisture in the wood to evaporate and move outward. In a certain flow rate of air, the moisture leaves the wood rapidly to achieve the purpose of drying. To ensure the quality of the dried wood, the humidity of the drying medium (such as the currently commonly used humid air) must also be controlled to achieve the effect of drying the wood quickly and with high quality.

Current status of paper tube / paper reel drying

Large-scale factories mostly use electric heating curing rooms, which consume a lot of electricity and have high costs.

2. The electric heating drying method has a relatively high temperature, which can easily cause uneven heating of the paper tube/paper shaft, resulting in deformation, layering and delamination, and even gumming or fire in severe cases.

3. The lifespan of a typical heating element is three to five months, and frequent repairs and replacements are required.

4. Some factories use steam for drying. Due to improper control of the steam temperature, it is prone to cause the temperature to rise too high, resulting in quality issues during the drying process.

5. Small-scale factories use methods such as natural sun-drying or air-drying. The production cycle is long and the efficiency is low. They are greatly affected by the weather and cannot carry out continuous production. The labor intensity is high and the quality of drying is difficult to be effectively controlled.

Several important issues

1. Temperature - The drying temperature for the paper tubes is relatively high, typically above 45℃.

2. Humidity - The paper tubes contain a relatively low moisture content. The glue used for laminating the paper tubes and for bonding purposes is present. Controlling the moisture removal can help save energy consumption.

3. Drying time - The general drying time for a continuous process is usually between 8 and 10 hours; this is significantly influenced by the diameter and thickness of the paper tube, as well as the properties of the glue.

4. Straightness/Circularity - For many paper tube products, maintaining the straightness and circularity of the paper tube after drying is of utmost importance; during the drying process, the deformation along the axial and radial directions of the paper tube must be controlled.

5. Hardness/Strength - This is also an important indicator of the quality of the paper tube.