Jul 04
GN363 Decanter Centrifuge

The normal operating parameters of the decanter centrifuge include a maximum mud feed volume and a maximum inflow solid volume. When the actual mud feed volume exceeds the maximum value, the decanter centrifuge will lose the dynamic balance of the solid phase and the liquid phase, and the torque becomes too large . In severe cases, the decanter centrifuge will be damaged, or the decanter centrifuge will be overloaded and stop running. Therefore, during the operation, the amount of sludge and solids flowing into the decanter centrifuge should be strictly controlled.

Select the appropriate feed flow method: first, adjust the feed flow to a smaller value (under frequency control, generally adjusted to 60%~70%), then start the decanter machine and work for a while, know that the solid phase is out The speed of the material is balanced. Then sample 500 mL at the entrance of the decanter centrifuge to determine the sedimentation ratio of the mud. It is normal if the precipitation amount is within 100~150 mL within 5 minutes. Otherwise, the bypass valve needs to be opened to reduce the feed concentration.

The water to be processed by the sludge treatment system is not always with the same quality, there might be much difference. And the different sludge particles will cause serious wear on the decanter centrifuge. In addition, there are many uncertain factors that may affect the outside environment of the decanter centrifuge. What’s more, there are many types of processing equipment in the system, and the processing links are interleaved. Therefore, to ensure the normal operation of each link and give full play to the role of facilities and equipment, it is necessary to strengthen daily operation management. Supervise the operation management personnel to do a good job in daily operations. Familiar with the function of each equipment, handle the nodes of each link, and strengthen the coordination between the processes.

written by Decanter Centrifuge

Jun 25

There are some important safety precautions when using a decanter centrifuge. We hope all the users can read and implement them carefully.

1. The decanter centrifuge must not be used to separate flammable, toxic, corrosive and radioactive materials.

2. Before preparing to install or operate a decanter centrifuge, please read and follow all requirements in the manual carefully.

3. Do not operate centrifuges with warning signs that are damaged or without warning signs.

4. If the vibration amplitude of the machine exceeds 24mm/sec, please stop immediately!

5. When the feed temperature exceeds the limits specified in the data list of the three manuals for installation, operation and maintenance, centrifuges are not allowed.

6. When there is ice water, freezing or hard material in the drum, the decanter centrifuge cannot be started.

7. Do not operate the centrifuge at a speed exceeding the maximum speed of the drum and the maximum density of solids as specified in the data list of the manual or as indicated on the nameplate of the centrifuge.

8. Do not operate the centrifuge without the belt guard and other protection facilities.

9. Regularly check all automatic shut-off devices and monitoring systems to ensure their normal operation.

10. If you are not sure whether the centrifuge is completely stopped, whether the main power supply is completely disconnected, and whether the main switch is disconnected and safely locked, please do not disassemble the centrifuge. 11. Do not operate the centrifuge when there are cracks, dents, voids or grooves in the drum, motor or support frame of the centrifuge.

12. When the running direction of the motor is opposite to the direction of the indicated arrow, please do not perform any operation on the centrifuge.

13. When the centrifuge is not completely installed, the machine must not be started.

14. Follow all lubrication procedures and steps of the equipment.

15. At least annually check the base of the centrifuge and motor and all supporting frames, casing and connecting pipes.

16. Do not place rags or loose clothing near rotating parts.

17. When disassembling, installing or operating, operating and servicing the machine, please strictly follow the normal steps.

18. Only specially trained technicians can operate, clean, disassemble and install decanter centrifuges.

written by Decanter Centrifuge

Jun 25

The application of decanter centrifuges in environmental protection mainly refers to the dewatering of sludge generated in the process of industrial and civil wastewater treatment. Today’s environmental issues have become the focus of common concern around the world. Under this background, the value of decanter centrifuges has been manifested. In the past, sewage plants or related treatment plants used self-settlement or belt filter presses to dewater and concentrate sludge. The test proves that the sludge moisture content is reduced from 98% to 80%, and its volume can be reduced by 10 times. Because of this, the horizontal spiral centrifuge has the characteristics of large processing capacity, automatic operation, and good dehydration effect. The field of protection has been widely used and promoted. The single product sales of decanter centrifuges account for about half of all centrifuge products, laying its irreplaceable position. In foreign countries, decanter centrifuges are preferred for sewage treatment equipment.

Application for different industry:

Sludge dewatering

Grain size classification

Liquid phase clarification

Power plant sludge

Titanium dioxide

Peanut protein

Paper sludge


fruit juice

Natural gas desulfurization sludge

Drilling mud paddle


Calcium carbide sludge

Pulverized coal flotation

Vegetable oil

Fiberboard sludge

Crystal flotation

Citric acid

Drilling mud paddle


Waste oil purification

Chlorinated mud


Wash water purification

Beating sludge


Orange juice

Activated sludge

porcelain clay

Fermentation broth

Gypsum paddle


Plant extract

GN dewatering decanter centrifuge is P series decanter centrifuge with beach angle of 11 degrees. GN P series decanter centrifuge is usually used dewatering and thickening purpose. It is widely used for maximum dewatering requirements of municipal and industrial wastewater sludge. The dewatering decanter centrifuge is designed for easy separation material include large particle size, high density difference of solid and liquid, low viscosity, high concentration, high treatment capacity and higher dryness than clarity. The materials like sludge or wastewater containing fine particles usually need to be added with flocculants to gather the fine particles condensed into large ones, and then dewatered with P series decanter centrifuge.

written by Decanter Centrifuge

Jun 11

The cold weather in winter is a period when the sludge dewatering decanter centrifuge might get seriously damaged. The sludge dewatering decanter centrifuge must be inspected and maintained on a regular basis to do the pre-prevention work. Below we will tell you how to maintain the sludge dewatering decanter centrifuge in winter.

   The manufacturer of sludge dewatering decanter centrifuge should start from the basic work of sludge dewatering decanter centrifuge management, establish lubrication maintenance and daily maintenance of the main components, and require the operator to pay attention to the water supply of each part of the sludge dewatering decanter centrifuge to prevent freezing before shutting down. Carry out maintenance on all parts, and pay special attention to the filter.

The first is to check the flushing water system of the belt-type sludge dewatering decanter centrifuge, the second is to check the bearing lubricating oil, the third, the filter is to prevent the ice from damaging the filter before starting, the fourth is to check the appearance of the solid parts, and to lubricate the contact parts, the fifth is Check whether the air compressor is clean, so that the air source is unobstructed. Sixth, check the emergency shutdown to increase safety, etc., and make lubrication maintenance records.

GN dewatering decanter centrifuge is P series decanter centrifuge with beach angle of 11 degrees. GN P series decanter centrifuge is usually used dewatering and thickening purpose. It is widely used for maximum dewatering requirements of municipal and industrial wastewater sludge. The dewatering decanter centrifuge is designed for easy separation material include large particle size, high density difference of solid and liquid, low viscosity, high concentration, high treatment capacity and higher dryness than clarity. The materials like sludge or wastewater containing fine particles usually need to be added with flocculants to gather the fine particles condensed into large ones, and then dewatered with P series decanter centrifuge.

written by Decanter Centrifuge

Jun 04

       The decanter centrifuges made in China are different from the imported ones. The imported decanter centrifuge with the same function is about 6 to 10 times cost than the domestic one.

 The reason is that the imported decanter centrifuge is durable, and the control of temperature and speed is more accurate. The price difference between centrifuges of the same grade is not very big, mainly distinguished in performance and configuration. The difference of the equipment is that in terms of performance, centrifuges with freezing are much more expensive than ordinary ones. Some centrifuges also have heating functions. The more control programs, the higher the price of the centrifuge. The big difference is the configuration. Sometimes the price of accessories is higher than the price of the equipment. When purchasing, please note that in addition to the equipment, the selected rotor (number and type), plus the necessary centrifuge tubes, tube sleeves, special centrifuge bottles or blood bags, all of which add up to a complete centrifuge price. Centrifugation is to use the strong centrifugal force generated by the high-speed rotation of the centrifuge rotor to accelerate the sedimentation speed of particles in the liquid, and separate the substances with different sedimentation coefficients and buoyancy density in the sample. Therefore, it is necessary to use a centrifuge to generate a strong centrifugal force in order to force these particles to overcome the diffusion and generate a settling motion.


A decanter centrifuge is a machine that uses centrifugal force to separate components in liquid and solid particles or a mixture of liquid and liquid. The centrifuge is mainly used to separate the solid particles in the suspension from the liquid; or to separate two liquids with different densities in the emulsion that are incompatible with each other (such as separating cream from milk); it can also be used to exclude Liquid in wet solids, for example, dry clothes in a washing machine; special super-speed tubular separator can also separate gas mixtures of different densities; the use of solid particles with different densities or particle sizes to settle in liquids at different speeds, some of them settle The centrifuge can also classify solid particles according to density or particle size. Centrifuges are widely used in chemical, petroleum, food, pharmaceutical, mineral processing, coal, water treatment and shipping sectors.

       In ancient China, people used one end of the rope to tie the pottery pot, held the other end of the rope, and flicked the pottery pot to generate centrifugal force to squeeze out the honey in the pottery pot. This was the early application of the principle of centrifugal separation.

written by Decanter Centrifuge \\ tags:

May 29

The main functions are as follows:

 (1) The control system has two operating conditions: manual control and automatic control: in the manual control state, various system parameters can be adjusted and set during operation; in the automatic control state, the system parameter settings are adjusted. The flow rate and dosing amount of the feed pump are controlled by the concentration meter in the sludge tank. The dosing amount and dilution water amount are controlled fuzzyly according to the turbidity of the separation liquid of the decanter centrifuge. The control system is an intelligent automatic control process.

    (2) With automatic and continuous measurement of the rotating speed and differential speed of the centrifuge;

    (3) It has status monitoring, fault alarm, data display and print report of various operating parameters of the system;

    (4) Automatically save mud volume through concentration detection, so that the centrifuge is always in the best working state;

    (5) It has system working status, alarm signal, various operating parameters and historical records transmitted to the host computer;

    (6) Monitoring and display of parameters such as current, voltage, flow rate, host speed, differential speed, pushing torque, running cumulative time, temperature, etc .;

    (7) With dynamic screen display and parameter setting of each operation unit;

    (8) Through the network configuration software of the host computer, remote fault diagnosis function can be realized; animation display of operating status; real-time data report; historical data search;

(9) The entire control system is fully automatic controlled by PLC + LCD touch screen, so that the system is in intelligent full-automatic operation in operation, which is an ideal turnkey project.

Four ways of processing industrial sewage:

A. Physical method: use physical action to separate suspended matter and emulsion in wastewater. Common methods include grille, sieve, decanter centrifuge, clarification, filtration, and oil separation.

B. Chemical method: the use of chemical reaction to remove dissolved substances or colloidal substances in water. Common ones include neutralization, precipitation, redox, catalytic oxidation, photocatalytic oxidation, micro-electrolysis, electrolytic flocculation, and incineration.

C. Physical and chemical method: Physical and chemical effects are used to remove dissolved or colloidal substances in water. Common methods include coagulation, flotation, adsorption, ion exchange, membrane separation, extraction, stripping, stripping, evaporation, crystallization, and incineration.

D. Biological treatment method: the use of microbial metabolism to convert organic pollutants and inorganic microbial nutrients in wastewater into stable and harmless substances. Common methods include activated sludge method, biofilm method, anaerobic biological digestion method, stabilization pond and wetland treatment. The biological treatment method is divided into aerobic treatment (such as activated sludge method, biofilm method) and anaerobic treatment (various anaerobic digestion methods) according to whether oxygen is supplied.

written by Decanter Centrifuge

May 23

Analysis of actual difference between belt press machine and decanter centrifuge

1 Applicable media problems

Decanter centrifuge is suitable for all kinds of sludge; belt machine is also suitable for all kinds of sludge, but for oily, viscous, remaining activated sludge, it needs a large amount of medicine and dehydration is difficult.

2 The problem of feed control

The decanter centrifuge can automatically adjust the slip and torque according to the change of the feed concentration, and the belt machine must be manually adjusted.

3 Problems of solid recovery rate and dosage

The solid recovery rate of the centrifuge is indeed higher than that of the belt machine, but this does not mean that the solid recovery rate of the belt machine cannot be used if it is low. In fact, the belt filter must be returned to the front and reprocessed.

The dosage of medicament is added. A 15 × 104t / d urban sewage treatment plant designed by the author adopts a decanter centrifuge for dehydration. The measured consumption of PAM per ton of dry sludge after production is 1.7-2.0kg. The lower the consumption of medicine with machine (PAM) is generally 4kg / (t [dry mud]).

4 Power consumption problem

The difference in power consumption is not as claimed by the manufacturer of the machine. It is actually controversial. The decanter centrifuge manufacturers will also say that their centrifuges use less electricity. The author speaks a jargon here: power consumption differs mainly depending on the model and the amount of processing capacity.

The noise of the centrifuge is large, but the noise with the machine is not the machine itself, mainly the sound of washing water, the sound feels better than the centrifuge;

5 The life of the belt press machine

The bearing life of a good-quality belt press machine is theoretically 20a, which is similar to the life of the host machine. The filter belt needs to be replaced frequently. The filter belt is generally replaced continuously for 2000h operation. If it is intermittently operated and maintained well, then it depends on the length of use and shutdown In contrast, regardless of whether it is a domestic or imported belt machine, the filter belt can generally be replaced with a domestic filter belt, so the cost of replacing the filter belt is not high, and the current domestic equipment of the decanter centrifuge is reliable, stable, and easy to maintain and maintain.

In theory, the running time of the belt press machine can also run for 24 hours. Of course, the continuous operation of the belt machine is not as reliable as the centrifuge.

6 Calculation of operating expenses

When the belt filter press dehydration machine manufacturer calculates the dehydration and centrifuge core operating costs, there are many problems in the calculation method used. The operating costs mainly include: pharmaceutical fees, electricity costs and water costs. In addition to the belt machine, there are downtime costs and flushing costs. The author took an 8 × 104t / d sewage treatment plant as an example to calculate the actual operating cost of sludge treatment. Therefore, from the perspective of operating costs, the use of centrifuges and Not higher than with the machine.

7 Investment issues

From the perspective of investment, if the above-mentioned belt integrated machine is an imported high-end product, the full set is about 200,000 US dollars, and the domestic production is lower, while the above set of centrifugal concentration dehydration machine is about 300,000 US dollars, and the domestic production is lower, due to the difference in product grades. Or other specific reasons, the price will be outstanding, but generally speaking, the product of the same grade, the price of the centrifuge is higher than that with the filter, however, because the centrifuge occupies less space, the construction cost of the sludge concentration and dewatering room can be saved In some cases, the two basically offset each other, which means that the investment costs of the belt machine and the centrifuge are similar.

From the above analysis, we can draw the following conclusions: The advantage of the centrifuge is that the mud is dry and the closed environment is good. It can run continuously without flushing water. The advantages of the belt machine are power saving and low noise. Therefore, whether to use centrifuge or belt machine for sludge (concentration) dehydration must be analyzed concretely.

written by Decanter Centrifuge

May 15

The principle of the decanter centrifuge is to use the centrifugal force brought by the high-speed mechanical rotation to achieve the purpose of solid-liquid separation, and some noise and vibration will be generated during the operation of the equipment. It will affect the surrounding environment of the device, so when using the device, some techniques can reduce noise and vibration. The following are some common technical solutions:

When the whole set of equipment runs empty and the inlet and outlet are closed, the average noise at 1 meter around the equipment will not exceed 85dB when tested in the manufacturing plant.

When the centrifuge is idling, without water, and tested in the manufacturer, the vibration is not higher than 5mm / S. If the vibration is too large during the operation of the machine, in order to ensure safety, it can be stopped by the vibration switch.

1. There is no need to disassemble the machine when there is a material blocking failure, only need to start the automatic slag discharge of the screw pusher to clear the accumulated material.

2. After the decanter centrifuge is shut down, backwash must be performed. Backwash only needs to open the flushing water valve and flushing water pump to complete.

3. The centrifuge is equipped with emergency shutdown, motor overheating / overload, screw feeder overload, bearing temperature, vibration and other protection functions.

GN can not only provide users with Dewatering Decanter Centrifuges, rely on GN rich production line of separation and conveying equipment. GN can also provide users with turnkey solutions for the material dewatering process, including solutions for material transportation, classification and dewatering. 

With complete machine monitoring and alarm system. When overload, short circuit and lack of phase occur in the course of operation, the centrifuge will be automatically protected; the speed of centrifuge, bearing temperature, vibration of the whole machine, lubrication system oil pressure, main and back motors’ current, push torque and other operating parameters are monitored in real time, and alarm is started when the parameters are abnormal. In case of blocking materials, the device will automatically switch to the plugging procedures; if plugging procedures cannot be dredged, it will then automatically switch to the shutdown procedures to ensure the safety of personnel and equipment.

written by Decanter Centrifuge

May 08

Sewage and sludge in the paper industry need to be treated in a sludge thickening tank. Now the main sludge treatment process is: pre-dehydration, dewatering by decanter centrifuge, crawler dehydration. After the sludge concentration is increased, the dewatering efficiency of the decanter centrifuge will increase accordingly. But it should be avoided that the sludge concentration becomes too high, which will cause the sludge transportation pipeline to block the concentration is too low.

    The papermaking wastewater mainly comes from the two production processes of pulping and papermaking in the paper industry. Both processes discharge large amounts of wastewater. The wastewater from pulping is the most polluted. The waste water discharged during washing is black-brown, which is called black water. The concentration of pollutants in black water is very high, BOD is as high as 5-40g / L, and it contains a lot of fibers, inorganic salts and pigments.

    The process of the decanter centrifuge to deal with the papermaking sewage is to make the sludge pass through the gravity dehydration zone, then to the pressure dehydration zone, and finally to the pressurized dehydration zone. After these three steps, a relatively dry mud cake is produced. The concentration suitable for dehydration is generally about 10%.

The decanter centrifuge has the advantages of low investment, automatic control, continuous operation, low energy consumption, high dehydration efficiency, easy management, low maintenance cost, low noise, and low dosage of chemical agents. Therefore, dewatering decanter centrifuges are recommended for papermaking wastewater and mud dewatering projects.

GN dewatering decanter centrifuge is P series decanter centrifuge with beach angle of 11 degrees. GN P series decanter centrifuge is usually used dewatering and thickening purpose. It is widely used for maximum dewatering requirements of municipal and industrial wastewater sludge. The dewatering decanter centrifuge is designed for easy separation material include large particle size, high density difference of solid and liquid, low viscosity, high concentration, high treatment capacity and higher dryness than clarity. The materials like sludge or wastewater containing fine particles usually need to be added with flocculants to gather the fine particles condensed into large ones, and then dewatered with P series decanter centrifuge.

written by Decanter Centrifuge

Apr 25

Important factors about choosing a Decanter Centrifuge

1.1 Differential ratio

The settling velocity of solids in different media is different, and the degree of aggregation is different, so different differential speed ratios should be used. When the other parameters remain unchanged, the differential speed is large, the solid material is pushed out faster, the amount increases, and the liquid content increases, the shaft power generally decreases, but the separation effect will decrease, that is, the solid content in the filtered liquid Will increase. As the differential speed increases, it actually acts as a stirrer in the drum. Choosing the right differential ratio is the first factor to consider when choosing a model.

1.2 Length-to-diameter ratio

The aspect ratio is the ratio of the axial length of the Decanter Centrifuge drum to its diameter. The working area of the Decanter Centrifuge is divided into several areas such as feeding, sedimentation, drying, and unloading. The length of the settlement area is the main parameter that determines the separation effect. The longer the settlement area, the greater the aspect ratio, the better the separation effect, but the greater the shaft power. Different length-to-diameter ratios should be selected according to different media properties (mainly settlement performance), and should be considered in combination with differential speed ratios.

1.3 Power

The use of larger power can improve the processing capacity, especially when the settlement performance of the medium is very good. The user has certain difficulty in choosing the model. In the face of new media or media without successful use experience, relevant tests should be conducted.

2 Determination of operating parameters

2.1 Adjustment of overflow diameter

There are four options for the overflow diameter of the general Decanter Centrifuge. The larger the diameter of the overflow, the longer the drying zone, and the lower the water content of the filter cake, but the higher the solid content of the filtered liquid, so the appropriate overflow diameter should be adjusted. For the “three mud” that is not easy to settle, it should be smaller, and for the medium that is easy to settle, such as TA residue, it should be larger.

2.2 speed

According to the working principle of the Decanter Centrifuge, the higher the speed, the better the separation effect, the dryer the filter cake, the clearer the filtered liquid, and the greater the shaft power. This is an important parameter in actual operation, but it is not that the higher the speed, the better the effect. Generally speaking, for the medium that is easy to settle, the higher the speed, the greater the shaft power, which is easy to cause the mechanical or solid material to be pushed out, causing the material to block. Therefore, the appropriate speed should be selected according to the factors such as the power of the Decanter Centrifuge, the feed, the dehydration effect and other factors. For the “three muds” that are not easy to settle, when the rotation speed is high to a certain value, there will be a phenomenon that the separation effect decreases, the sludge production decreases, and the solid content in the filtered liquid increases. When the rotation speed is reduced, the mud production fork will increase. This is because the material slips in the drum and cannot be pushed out. At the same time, as the speed increases, the absolute differential increases, and the stirring effect of the spiral drum is enhanced.

written by Decanter Centrifuge