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FAQ - Drying and Dehumidifying

Model Selection

There are two methods to meet this application:
  1. Dryer with dehumidifying function, such as ALL-IN-ONE compact dryers SCD which includes dehumidifying,drying and conveying functions; Dehumidifying dryers SDD which include dehumidifying and dyring functions.
  2. Common dryers without dehumidifying function, such as Euro type hopper dryers SHD-U, hopper dryers SHD and compact dryers SDL ro SDL-U.
High temperature drying effect would be affected by ambient humidity except for cold area, such as northern in China, but the dyring effect of dehumidifiers could not be affected, so we suggest to use SDD or SCD because PA mateial have good hygroscopicity.
It is impossible to have any change on the original machine. You should change electric part and mechanism part. Because the machine, which can provide dyied material for two molding machines, is controlled by PLC and touch-screen.
For this situation, we suggest that you order SAL-900G2 with SVH-12L, in conjunction with a suction box of SBU-160-38D to finish above-mentioned function. When using, just run vacuum hopper on the SCD and close the SVH on SCD and shut-off value. Please refer to the usage of SAL-900G2.
Becase of using uncrystallized PET material, it is needed to select SCR (PET crystallizer) to processe PET in advance before drying in case PET get block. Based on the capacity, we suggest folliowing machine:
Crystallizer: SCR-900U
Dehumidifying and drying system: SD-1000H+SHD-2000U+ACF-5" +5” dehumidifying pipe system with stainless steel pipe.
This series of SCAD have no dehumidifying function, it uses the pressure dew-point of high-pressure air when it released into the atmosphere to reduce dew-point value. For example, high-pressure air 0.59MPa, 20℃,when it releases into the atmosphere ,its dew-point is about -7.7℃. The dew-point value of SCAD is about -5℃~-10℃. Base on above-commention, SCAD is unsuitable for drying PA which have good hygroscopicity. It is possible to get better dehumidifying effect when it works with HDD(heatless dehumidifying dryer) which can make the dew point of air reach down to -40 celsius degree.

Operational Doubts

Yes, SHD(EURO type hopper dryer) have this function,which could be convience for customer to controll working time of SHD through automatically swiching ON/OFF SHD. For example, it is possible to swich on SHD at 5:00 AM and switch off it at 8:00 PM, also do such action which turn on SHD at 5:00 AM on monday and turn off it at 8:00 PM on saturday to achieve continuous production.
It is needed to provide cooling water for SMD in order to keep it work at ideal status. Temperature of cooling water is about 10 celsius degree.
Press Timer button in controll panel of SCD for three times, adjusting shut off time by pressing UP or DOWN button, save this paramter through pressing ENTER button. This time will vary with the differenct application, it is relative with length of material conveying pipe, bulk density of material and so on. Default value of this parameter is 5 seconds.
Yes, this temperature could be set at higher value if heater power is enough, but we strongly suggest that customer don't change this value because higher temperature may reduce life time of honeycomb rotor.

Trouble Shooting

Maybe contacts of contactor was welded, which lead the heater run continuously, therefor the temperature exceeds the setting value of EGO and the alarm happens.
Alarm of E-09 stands for honeycomb rotor fault, the possible cause is that transmission part or detector were broken. It is possible to fix it according to following steps:
1.Check parameter F-19 whose default value is about 600s, if this parameter was set at a over smaller number, this alarm happens.
2.If F-19 is normal, disassembly left side plate, move rod of microswitch near rotor and alarm will reset automatically, then confirming if rotor rotates normally, if it runs normally, maybe detecting circuit is broken, otherwise transmission part is malfunctioned.
3.Confirming if the micorswitch could be switched ON/OFF normally by top point of block on honeycomb rotor, if not, adjusting position of microswitch until it can be turn ON/OFF regularly.
Please pay attention to confirm whether the surrounding air enter into the system. You can observe the change of dewpoint when the inlet of dehumidifier connects directly to outlet of itself.
Check the return air temp, usually it is lower than 35℃.
Check the pipeline whether there is gas leakage.
Check the dew point sensor and monitor if they are broken.

Maintenance

There are following suggestion:
  1. Clear air filter regularly. If containing lots of dust in material, clean it per week, otherwise clean it per month.
  2. No oil in material. If oil must be used, it is needed to equip with a oil filter in return air inlet.
  3. Suitable regenerative temperature. This temperature is 150 or 180 celsius degree when dewpoint is -40 or -150. Much higher temperature can reduce the lifespan of honeycomb rotor.

Other Issues

Drying hopper capacity (kg) = output (kg/hr) ×drying time (hr)
Actual drying hopper capacity (kg) =drying hopper capacity (kg) ×1.2(safety factor)
Notes: The hopper capacity of SHD series is calculated by the material density of 0.6 kg/L. If there are some differences in customer’s material density, hopper capacity should be adjusted proportionally. SHD-U series’ hopper capacity is calculated by unit liter, if the unit of needed output is kg/hr, it is needed to switch the unit into capacity unit (L).
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