Learn how to maintain, troubleshoot, and manage centrifugal dehydrators.
Hello, this is Minhee Hwang from ARK PR. This is the third installment of ARK's knowledgebase for environmental facility practitioners, sharing information on how to respond to and manage centrifugal dehydrator failures.
Part 2: Thermal Power Plant Wastewater Treatmentand in this installment, we're going to talk about the Part 1 Comparing conflicting terms for centrifuges, centrifuges, and centrifugal concentratorsThis is a follow-up to responding to and managing failures.
Centrifugal dehydrators are the most modern successor of environmental equipment and utilize the physical properties of centrifugal force to dewater and separate water, unlike conventional filter presses and belt presses.
This does not mean that filter presses or belt presses are significantly worse than centrifugal dehydrators.
However, in terms of management, the centrifuges are more convenient for practitioners and more advanced in terms of smart operation, automation, etc.
If you're not familiar with centrifugal dehydrators, the most advanced type of dehydrator, here are some troubleshooting and maintenance tips.
Source: Ministry of Environment Public Sewerage Facilities Maintenance Practical Guide 2005
What is a centrifugal dehydration plant?
A centrifugal dehydrator is a device that uses centrifugal force (rotation) to separate sludge and dehydrate filtrate, with transverse centrifugal dehydrators being the most common.
Centrifugal dewatering utilizes centrifugal forces of 1,500 to 3,000 times the acceleration of gravity on sludge that has been modified with polymer chemicals.
It quickly separates particulates that cannot be separated by sedimentation, and the structure of a transverse continuous centrifugal dehydrator is shown in Figure 1.
The influent sludge is mixed with chemicals to form a sludge floc, which is separated into dewatered filtrate (clarified liquor) and solids (dewatered sludge) by rotation of the dewatering machine.
The separated sludge is pressed by a screw conveyor driven at a lower speed than the rotor speed by a differential gear and discharged as dewatered sludge.
The sand and impurities contained in the incoming sludge can accelerate wear and tear on the dehydrator or cause clogging, making it necessary to remove sand and shred impurities through pretreatment.
Sludge treatment methods for centrifugal dewatering plants: chemical treatment and external mixed injection
There are two types of chemical injection methods: mixing with sludge outside the dehydrator and supplying it to the dehydrator, or separating the sludge supply pipe from the sludge with a double pipe and mixing it inside the dehydrator.
The method of external mixing and injection requires a high pre-dosing rate because the already formed sludge flocs are crushed during dewatering, while the method of separate injection in the dehydrator is widely used because it provides good liquid separation and requires less chemicals.
Nominal throughput capacity m³/h (throughput per hour)
The nominal treatment capacity of a centrifugal dehydrator is expressed in terms of sludge throughput (m³/h).
If the influent sludge solids concentration is very high, the influent sludge volume should be reduced to below the nominal treatment capacity as sludge may spill into the separation shrinkage, but if the influent sludge solids concentration is low, it can be treated above the nominal treatment capacity.
Centrifuge Operation Management
The operator of the centrifugal dehydrator shall pay attention to the following points when managing the operation. (1) Operation (2) Stopping (3) Operating precautions
Ⅰ. Operation management of centrifugal dehydrator
(1) For driving
Starting and stopping a centrifugal dehydrator is easier to operate than other types of dehydrators because there are fewer accessories.Starting and stopping a centrifugal dehydrator is easier to operate than other types of dehydrators because there are fewer accessories.
- Each part is checked beforehand and checked for anomalies.
- Make sure the water system is clear before driving.
- Once the prescribed rotation rate is reached, slowly feed the sludge and chemicals and increase the sludge volume up to the standard throughput, paying attention to the composition of the dewatering filtrate and the moisture content of the dewatered sludge.
- Keep the sludge inflow constant.
(2) About stopping
- Stop the supply of sludge and chemicals and remove all sludge from the machine.in the file.
- Flush water is drawn from the sludge supply to clean the inside of the dehydrator.
- After stopping the motive, flush the sludge from the supply piping if there is a risk of clogging.
- Clean the sludge in the supply piping if there is a risk of clogging after shutdown.
(3) Driving precautions
Decanter centrifuge Key driving precautions include.
- Since centrifugal dehydrators are high-speed rotating machines Refuel drives, pay close attention to airframe vibrationYou should.
- If there is a change in the dewatering situation, the sludge feed rate should be reduced first and the dewatering situation should be checked.
- Solids concentrations often change over time, so pay attention to changes.
- Carefully observe the flow meter's gauge because the injection rate is small, 0.5 to 1.01 TP2Ts.and ensure that the dose is appropriate.
- Care should be taken to remove any debris in the sludge as it can be deposited in the dehydrator.
- For device protection purposes Sludge feeding does not stop the centrifuge, and sludge feeding is in progress when the operation is stopped.It should be.
Ⅱ. Centrifugal Dehydrator Accessories
Centrifugal dehydrators have a variety of accessories, such as polymer feed pumps for feeding chemicals, sludge feed pumps, flow meters, etc. (1) Sludge feed pump (2) Chemical feed pumps (3) Flocculation mixer
Ⅲ. Centrifugal Dehydrator Operation Checklist
- Check the proper flow rate of the spindle water, reducer, and lubrication of the internal spindle water.
- Check the temperature of the spindle water.
- Record the following items in the inspection logbook and driving logbook for early detection of faults and proactive measures for effective operation management.
- Mechanical entries record the current value, temperature of the accumulator, and the presence or absence of abnormal sounds.
- Performance measures include the amount of influent sludge, chemical dosing, influent sludge solids concentration, filtrate SS concentration, and moisture content of dewatered sludge.
Ⅵ. Centrifugal Dehydrator Operating Indicators
(1) Influent sludge (2) Dewatering Filtrate (3) Dewatering Sludge (4) Centrifugal force (5) Dosing rate
(1) For feed sludge
See the section on medication infusion equipment.
(2) For the isolate
In a centrifugal dehydrator, the SS concentration of the separate changes depending on the solids concentration of the influent sludge and the solids load, so it is important to analyze the separate to detect abnormalities early.
(3) About dewatering sludge
The moisture content of dewatered sludge is usually 80% or less, and if the moisture content increases significantly, take measures by identifying the sludge composition, chemical type, and injection rate.
(4) For centrifugal force
The effect of centrifugal force on dewatering sludge moisture content and solids recovery is shown in
Ⅶ. Management during normal times
Management during normal operation shall be carried out with attention to the following points. (1) Sludge amount and composition of incoming sludge (2) Moisture content and dewatering filtrate of dewatered sludge
(1) Sludge amount and composition of incoming sludge
Keep the influent sludge volume as constant as possible; large changes in influent sludge volume will affect dewatering performance.
(2) For moisture content of dewatered sludge and dewatered filtrate
If the dewatering efficiency decreases significantly during operation, the dewatering efficiency can be adjusted by adjusting the sludge feed amount, adjusting the vehicle speed, adjusting the dewatering filtrate water level, etc.
Ⅷ. What to do if something goes wrong
If any of the following anomalies occur, take appropriate action to manage them.
(1) Mechanical failure of the dehydrator
(2) Dehydration abnormalities
If the dewatering efficiency decreases significantly during operation, the dewatering efficiency can be adjusted by adjusting the sludge feed amount, adjusting the vehicle speed, adjusting the dewatering filtrate water level, etc.
(1) For mechanical abnormalities of the dehydrator
If an abnormal phenomenon occurs during driving, the cause should be estimated from the phenomenon and appropriate measures should be taken, and the measures for the cause of the abnormality are as shown in
Korean 
English 
Russian