With the widespread use of engineering plastics, dehumidifying dryers have now gradually replaced traditional hot air blowers, and are increasingly used in the injection molding industry. They can not only improve drying efficiency, but also ensure the final molding quality of products, which brings enterprises to production. Numerous advantages. The ratio of the drying method of the dehumidifying dryer and the traditional hot air blower can not only improve the drying efficiency and shorten the drying time, but also is not restricted by the environment, ensuring an excellent drying effect. The dehumidifying dryer first draws the air in the environment to remove the moisture in the air under low dew point, and then heats the dried air into one or more standard drying hoppers, which can improve the drying efficiency and change the drying time. If a traditional hot air blower is used, when the plastic is taken out of a moisture-proof sealed packaging bag with a wet plastic and exposed to the atmosphere, it will begin to absorb moisture from the atmosphere. The traditional hot air blower cannot prevent the plastic from continuing to absorb moisture. , The drying effect is poor. The following is an introduction to the drying method of the dehumidifying dryer. What causes the low efficiency of the dehumidifying dryer? Is there a certain type of dehumidifying dryer? Operation precautions, fault detection and troubleshooting methods, maintenance procedures, what standard reference when purchasing? Let's take a look!
Drying method of dehumidifying dryer
1. Heating and drying method
Generally, dehumidifying dryers use air to dry materials. The air is heated in advance and sent to the dryer, which will be passed to the materials. After the moisture in the vaporized materials is heated and dried at high temperatures, the moisture can be removed to reach the product or raw material. The required conversion rate.
2. Mechanical dehydration method
The mechanical dehydration method usually can only remove part of the free water in the material, and the combined water still remains in the material. Therefore, the material will still contain water after the material is mechanically dehydrated, and the drying effect is not obvious. However, mechanical dehydration is relatively the most economical method.
3. Chemical dehumidifying
Chemical dehumidifying is to remove a small amount of moisture in gas, liquid, and solid materials through hygroscopic agents. Due to the limited dehumidifying capacity of hygroscopic agents, they are only used to remove trace moisture in materials, so they are rarely used in production.
What causes the low efficiency of the dehumidifying dryer?
The decisive factors for a good drying efficiency are drying temperature, drying time, air volume, and dew point. These four factors are interlinked, and any change in conditions will affect the drying effect of the dehumidifier dryer.
1. Drying temperature:
Drying temperature refers to the temperature of the air entering the drying barrel. Due to its physical properties, such as molecular structure, specific gravity, specific heat, selectivity and other factors, the drying temperature must be limited. If the temperature is too high, part of the additives in the raw materials will be volatilized or agglomerated. If the temperature is too low, some crystalline raw materials cannot reach the required drying conditions. In addition, it is necessary to choose an insulated dry barrel to avoid drying. Temperature leakage causes insufficient drying temperature or waste of energy.
2. Drying time:
It refers to the pre-drying time of the raw materials that need to be dried before molding. A reasonable drying time should be customized according to the required drying raw materials. If the drying time is too short, the moisture content of the raw materials will be too high, and the drying purpose cannot be achieved. Too long will cause the raw materials to agglomerate or deteriorate, which greatly wastes energy.
3. Dry air volume:
The only medium that can take away the moisture in the raw materials is the dry air volume, which affects the dehumidifying effect. Too much air volume will cause the return air temperature to be too high, causing overlap and affect the stability of the dew point. If the air volume is too small, the moisture in the raw materials cannot be completely taken away. The air volume is the representative of the dehumidifying capacity of the dehumidifying dryer.
4. Dew point temperature:
It means that when the gas is cooled to a temperature that condenses high-concentration moisture into water droplets, the less moisture in the gas, the lower the dew point temperature. It is a unit for measuring the degree of dryness or proximity of the gas. Generally, a dew point temperature of -40 ℃ is a good dehumidifier dew point.
There is a certain type of dehumidifying dryer
At present, the main types on the market can be divided into different types, namely hot air dryers, compressed air dryers, vacuum dehumidifying dryers, and three-in-one dehumidifying dryers.
1. Hot air dryer
Hot air dryer is the most commonly used drying equipment in the past. It has a relatively simple structure and consists of a fan, a heating tube, a temperature controller, and a drying barrel or drying box. This type of dryer is easily affected by the ambient air temperature, and the drying effect is very small. In dry weather, the drying effect will be much better than in vertical weather. It is only suitable for plastic materials with low hygroscopicity and low requirements for drying effect. At present, many manufacturers have gradually reduced their use.
2. Compressed air dryer
The compressed air dryer mainly uses the principle of air force to reduce the moisture in the air, and then uses the dehumidified air to heat to dry the raw materials. This type of dryer has relatively high requirements for the use environment, requiring an air compressor in the workshop, and the high-pressure gas generated by the air compressor must be absolutely clean, the moisture content must not be too high, and there must be no oil, otherwise the dehumidifying tower will be blocked And it will contaminate raw materials. Appropriate because the price is relatively cheap and affordable. However, most factories cannot provide stable dry air pressure, so it is not recommended to purchase air pressure dryers.
Three, vacuum dehumidifying dryer
The vacuum dehumidifying dryer uses vacuum to reduce the boiling point of water to remove the moisture in the raw materials. It can be dehumidified and dried without any chemical agents, effectively avoiding the acidification, substitution, and yellowing of the materials, and it will not pollute the raw materials in the cylinder. Clean up. The vacuum dehumidifying dryer has the characteristics of fast drying speed, reduced drying time, increased productivity, and energy saving. It is suitable for dehumidifying and drying small batches of raw materials.
Four, three-in-one dehumidifying dryer
Its working principle is to absorb moisture in the air through a hygroscopic material (dehumidifying), and then compare the dew point after dehumidifying. This type of dehumidifying dryer is suitable for dehumidifying and drying engineering plastics with strong hygroscopicity and has a low dew point. Stable, good drying effect, etc., suitable for most plastic manufacturers.
Precautions for operation of dehumidifying dryer
1. Make sure that the dehumidifying dryer has been installed and adjusted;
2. Turn on the power switch on the control box power supply and the dehumidifier panel;
3. Check the temperature indication of the material barrel frequently, and repair it in time if any malfunction is found;
4. When the temperature rises to the specified temperature, check whether it is consistent with the temperature of the lower part;
5. Keep the barrel full at any time during production;
6. The raw materials can be produced only after the specified drying time is fully reached;
7. When the drying is completed, when you want to stop, first close the feeding plate, and then close the feeding system after pumping the bottom raw materials.
Fault detection and elimination methods of dehumidifying dryer
1. When the dehumidifying dryer is powered on:
After the system is powered on, if there is a failure, the system cannot be turned on (cannot have any output), and the corresponding fault code is displayed, and the corresponding fault processing is performed at the same time. When the fault is removed, the system will return to the shutdown state and needs to be restarted .
2. During the operation of the dehumidifying dryer:
1), Fan overheating fault input:
(Passive contact normally open signal, normal when plugged in, fault when closed) When an overload fault is detected, the fault indicator lights up, the system shuts down heating, the heating relay is interrupted, the heating relay is extinguished, the fan is turned off, the fan relay is on, and the fan indicates When the light is off, the system stops all output. At the same time, the alarm relay outputs (on-off) alarm signals. When the fault is eliminated, the system returns to the shutdown state.
2), too many fault inputs:
(Passive contact normally open signal, normal when plugged in, fault when closed) When an overheating fault is detected, the fault indicator will be on, the system will immediately shut off the heating, the heating relay will be disconnected, and the heating will flicker off, and the fan can work normally. At the same time, the alarm relay outputs (on-off) alarm signals. When the fault is eliminated, the system returns to the shutdown state.
3), Reverse phase failure:
(Passive contact is normally closed signal, that is, it is normal when closed, and malfunctions when alternate) When the reverse phase is detected, the fault indicator light is on and the system stops all outputs. At the same time, the alarm relay outputs (on-off) alarm signals. When the fault is eliminated, the system returns to the shutdown state.
4) The fan does not turn and the hot air emits smoke:
It is mainly caused by motor failure and the electromagnetic switch has been closed, which can be solved by checking and replacing the motor and repairing and replacing the electromagnetic switch.
5), the fan is running but no temperature:
The cause of the failure is mainly caused by the fusion of the lead piece connected to the heat pipe, the failure of the electromagnetic switch, the failure of the electric heating pipe, the failure of the thermostat and no output, and the failure of the thermocouple. The failure can be eliminated through inspection, replacement and repair of the parts.
6) The fan is running but the temperature is extremely high:
Mainly because the air duct is blocked, the temperature controller is faulty or the error is too large, clear, replace the temperature controller or adjust the fine-tuning button to eliminate such faults.
dehumidifying dryer maintenance procedures
1) Maintenance of dehumidifying dryer:
1) Record the daily operation and maintenance of the dehumidifying dryer and establish files;
2) Regularly train operators, especially new employees;
3) Regular maintenance of the single machine in the system;
4), regularly check for leaks in the transmission pipeline, especially the vacuum pipeline and compressed air line;
5) Clean the dust on the electrical part of the equipment regularly.
2. Maintenance of dehumidifying dryer:
1) During the drying process of the material, all parts of the equipment in contact with the material need to be cleaned and disinfected;
2) The best operating temperature range of the dehumidifying dryer is 15°C~40°C to avoid excessively low or excessively high temperatures, which may affect the dehumidifying efficiency or damage the equipment;
3) Regularly clean the central filter in the dehumidifying dryer, and replace it if it is damaged;
4) Clean the air filter regularly (about once every two weeks) to maintain the dehumidifying, dust removal efficiency and life of the machine;
5) After cleaning the suction hopper and drying barrel, install them in place;
6) In order to improve the solubility, instant dissolution, and dry products, they should be continuously discharged from the drying chamber and packaged after cooling.
What are the standard references when purchasing a dehumidifying dryer?
1. The dehumidifier product belongs to the national compulsory certification product, and the product should have the 3C compulsory certification mark.
2. It is best to choose products with humidity control capabilities.
3. Choose products with beautiful appearance, neat fins of evaporator and condenser, uniform gap, no "collapse" phenomenon, good finish of plastic parts, and high manufacturing technology level.
4. Check whether the noise value is marked. The noise value is generally marked on the product nameplate or product manual. The smaller the noise value, the quieter the product. Variables, you can also feel the vibration of the machine running by hand. The compressor-type dehumidifying dryer will have the sound of the compressor running, but because the background sound of the store is sometimes very loud, it may not be able to hear the sound of the machine. In theory, the more severe the vibration The sound will happen.
5. Pay attention to product energy efficiency. Usually the product power of dehumidifying products also changes, and the dehumidifying capacity per unit input power is a key indicator reflecting the energy efficiency of dehumidifier products. In order to prevent false bids of enterprises, consumers should try their best to choose products of well-known brands.
6. Purchase products that match the dehumidifying capacity and production capacity. The daily dehumidifying capacity (liters) of the dehumidifier can be selected according to the number of plastics to meet the dehumidifying requirements.
7. Purchase according to the living environment. The dehumidifying power is not as large as possible. If the air in the plastic production area is not humid enough, the dehumidifier will not achieve the desired effect. It is best to choose according to the humidity level of the living area. The stronger the dehumidifying capacity is needed.
The drying method of the dehumidifying dryer explained in the above compilation, what causes the low efficiency of the dehumidifying dryer? Is there a certain type of dehumidifying dryer? Operation precautions, fault detection and troubleshooting methods, maintenance procedures, and what standard references are there when purchasing, I hope these knowledge about dehumidifying and dehumidifying can help everyone! Of course, the relevant personnel should pay attention to regularly adjusting the air volume of the dehumidifying dryer, because when the air supply is reduced, the total air volume of the dehumidifying dryer is also reduced accordingly, and the air volume of the dehumidifying dryer needs to be adjusted at this time. If no measures are taken to reduce the air volume of the blower of the tube dehumidifying dryer, the static pressure in the air duct may rise, which will increase the power consumption of the dehumidifying dryer fan, and may increase the air leakage of the system. To make the fan of the dehumidifying dryer work stably, and the dehumidifying dryer cannot be excessively throttled during operation, then a static pressure controller needs to be set to adjust the air volume of the dehumidifying dryer.
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