Dewatered Sludge Cake Pump Working Principle and Applications
One of the applications of the cake pump is that using this dewatered pump, which has a broad throat input and is offered in both standard and maintained-in-place configurations.
Sludge Cake Pump
the thickened and mixed sludge may be moved and handled with ease. This is made possible by the working principle of the cake pump's combination of features.
Along with slurries, thick non-flowing pastes, and viscous sludge cakes, dewatered sludge cakes with a dry solids percentage of more than 30% can also be transferred.
It was necessary for the wastewater treatment plant in the town of Speedway, Indiana, to have a device that could pump dewatered sludge.
This system is equipped with a progressive cavity pump that moves sludge cake from a belt filter press that has a solids concentration of approximately 20% to one of four valved discharge points in a sludge storage facility.
The solid concentration in the sludge cake is approximately 20%. During the process of conveying the muck, approximately 130 feet are covered.
Through ductile iron pipes that range from 6 to 12 inches in diameter and are covered with glass on the interior. A data set for eight months that covers seventy-four working days has been collected, and the system has been operating without a hitch for almost a whole year.
The purpose of this case study is to review the design features that contribute to the system's smooth operation, to compare the design discharge estimates with actual operating data, and to compare the operating data with empirical methods of estimating discharge pressure found in the literature.
These goals will be accomplished by examining the following: the design features that contribute to the system's smooth operation; the actual operating data; and the empirical methods of estimating discharge pressure.
- A large auger and a screw conveyor are used for input. A screw conveyor is responsible for the continuous pumping of the sludge cake. This conveyor goes on to the compression region, where the sludge cake is pushed into the rotor and stator.
- It is possible to separate the suction and delivery pipework of the keep-in-place model without having to detach the rotor and screw conveyor assembly of the keep-in-place model, and the rotor and stator can be removed without having to dismantle the entire unit.
- You have your choice of a number of different rotor and stator materials, in addition to several hopper and bridge breaker combinations.
- These are motors, gearboxes, and other moving parts that are built to last and have been specially selected for their longevity. There is a choice of direct-coupled or variable-speed topologies for electric motor drive units, as well as the presence or absence of a mechanical variable-speed or frequency converter.
Because of their low running rates and lower wear, pumps can go for longer periods of time without needing to be serviced. Useful in circumstances that call for a large quantity of cake.
Positive displacement pumps make it simple to move dewatered bio solids, commonly called sludge cake. Sludge cake is another name for dewatered bio solids.
However, the popularity of pumps has fluctuated throughout history due to changes in their designs, which were made to enhance the functioning and dependability of the pumps. When it comes to moving sludge cakes from one location to another, using pumps rather than conveyors offers a number of advantages.
Since pumps are able to carry cake across both horizontal and vertical segments of pipe, they make better use of available space than conveyors, which are limited to a single inclination level.
By enclosing the cake in a pipe, the process is made even more hygienic as the conveyor bearings and other potential wear spots are removed from the equation. In contrast, the installation and maintenance of a traditional pump calls for a higher level of technical expertise than that of a conveyor.
In addition, the output of the dewatering device must be matched with the speed of the pump, which may require the employment of additional employees, the purchase of a more expensive automated system, or the acquisition of more advanced maintenance knowledge. When pumping sludge cake, only positive displacement pumps are capable of handling the high pressures and fibrous character of the material.
Pumps that use positive displacement do so by drawing liquid into a contained space. This is true of all positive displacement pumps.
Due to the high apparent viscosity of sludge cake, the design of any pump must take into account the following two factors:
- Because atmospheric pressure on its own will not be sufficient to force the cake through the limitations that typically block the entrance to the pump chamber, the design will need to include a mechanism to feed the material into the hollow.
- When pumping a substance with such a high viscosity, it is critical to ensure that the internal mechanisms of the pump are devoid of any blockages that could lead to an increase in backpressure.
Because pumping concrete is the most prevalent application for reciprocating pumps, it stands to reason that this type of pump would be the sort of pump that is deployed the most frequently in this particular application.
In order for these pumps to be able to deal with the aforementioned requirements, they need to be equipped with a screw feed device and a non-restrictive check valve system. The most general type of rotary positive displacement (PD) pump is known as the progressive cavity (PC) design.
Because the cavities in PC pumps are sealed by a compression fit between the rotor and stator, the regulation of the flow of fluid is accomplished without the use of any valves in these pumps. Due to their adaptability, the inlets of these pumps are able to accept feed from a variety of sources.
In each of these systems, the feed screws have a dual role. On the one hand, they help to press the cake into the chamber, and on the other hand, they reduce the cake's apparent viscosity.
Sludge cakes are comparable to other types of slurries and sludge that contain water in that they are shear-thinning, non-Newtonian materials.
They are described as "thixotropic" in common parlance, which indicates that their viscosity lessens as the shearing force and the amount of time increases. When the liquid is less viscous, it is more likely to pass more quickly through the aperture of the pump.
Similar to how the opening into the cavity of a positive displacement pump can be compared to the hole in the base of a Zahn cup, which is used to determine the ideal paint dilution for an aerosol spray gun, the opening into the cavity of a positive displacement pump is also analogous to this. In general, the quicker the liquid will flow through the aperture, the thinner the liquid, and the smaller the opening.
To put it another way, the internal movement of the liquid within the pump is constrained by the rate at which the liquid can flow past the limitations on the inlet side of the cavity while being subjected to the force of atmospheric pressure. If the viscosity can be increased, then the amount of time needed to fill the pump cavity can be reduced, and the frequency with which the cavity is filled can be increased.
PC pumps frequently make use of components that work toward reducing the cake's viscosity, whereas piston pumps make use of feed screws to fill the cylinder without creating a significant amount of shear.
Both types of pumps are used to pump cake. Piston pump manufacturers have an easier and often more advantageous time extending the cavity diameter and reducing intake limitations than PC pump OEMs do.
On the other hand, makers of PC pumps report less difficulty when attempting to attach feed augers to the rotating coupling rod located at the pump's inlet.
It is necessary to have a mechanism with a rotating auger that is located outside of the OEM piston pump in order to supply the reciprocating action of the pump.
The cake that is produced by piston pumps is typically denser and more resistive to flow than the cake that is produced by other types of pumps, but piston pumps are typically more expensive and sophisticated than other types of pumps.
For many, the PC pump's cake doesn't rise correctly and has a more liquid consistency than they'd desire. Take into consideration that the quantity of solids has not been reduced in any way. There is no water in the mixture.
As time goes on, the consistency of the sludge will change to become more cake-like. However, if you do not take the necessary precautions to protect yourself, the cake that is produced by a PC pump may become an even bigger disaster.
Some people believe that it is simpler to load any container, including a dump truck, with a product that has a more liquid consistency, such as frosting.
This is because a product with a more liquid consistency has less air pockets and flows more easily into corners than a real cake. However, there are some landfill corporations that would prefer the finished outcome to be more cake-like.
By lowering the cake's apparent viscosity, it will be possible to increase the pump speed while using a pump that is both smaller and less expensive.
As was the suit in the past, the feed devices that are used in conjunction with these pumps are capable of performing dual duties, either filling the cavity or reducing the cake's viscosity. This is the point at which the screw mechanism of a PC pump diverges significantly from that of a piston pump.
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