A list of commonly asked questions & answers about products, orders, shipping & policies
What is a decanter centrifuge and how does it work?
A decanter centrifuge, also known as a horizontal bowl centrifuge, solid bowl centrifuge or scroll centrifuge, is a machine used to separate a solid material from a liquid(s) using a high-speed and continual rotational process. While wastewater treatment of biosolids is a primary application, the separation of one solid material from one liquid (2-phase dewatering) in a slurry is also important for a number of industries including chemical, food, oil, and mining to name a few.
Sludge Dewatering
Mechanical dewatering with a decanter centrifuge can result in a 95% reduction in volume and a concentration of between 15% to 35% dry solids, compared with 80% volume reduction and solids concentration of 3% to 7% with a sludge thickening-only operation. By removing more water and thereby producing a drier cake product, dewatering will offer significant savings in treatment, handling, and disposal costs.
Decanter Centrifuges for Sludge Thickening & Dewatering
The cost of biosolids storage, transportation, and end-use or disposal can significantly impact the choice of decanter centrifuges to perform thickening or dewatering functions. Generally speaking, sludge thickening before dewatering will reduce the tankage needed for storage by removing water; dewatering works to remove more water producing a drier cake material.
Servicing & Maintaining a Decanter Centrifuge
In this section, we’ll discuss some routine maintenance procedures a plant operator can undertake. We’ll also offer details on Centrisys’ Suggested Plant Maintenance Guidelines, and the Centrisys Service Inspection Program (CSI).
A decanter centrifuge maintenance schedule should include daily, weekly, monthly, and annual measures. A trained plant operator can perform many if not most of these. Some more critical centrifuge service issues may require the equipment and expertise of a dedicated centrifuge service and repair facility or a Centrisys field service technician to evaluate the centrifuge at your plant - more on this later.
What is the Differential Speed of a Centrifuge?
A Centrisys decanter centrifuge has the ability to operate both as a leading and lagging scroll. A leading scroll runs faster than the bowl. A lagging scroll runs slower than the bowl. This innovative scroll design prolongs the life of the discharge nozzles on both the bowl and the scroll. The benefit to our customers is less maintenance since a scroll can operate as both leading and lagging.
What's the Quickest Way to Verify the Differential Speed?
The quickest indicator of a correctly adjusted differential speed is the cleanliness of the centrate. As long as the centrate is clear and clean, the differential speed can be reduced to optimize the dryness of the cake solids.
Decanter Centrifuge Service & Maintenance Resources
Give your centrifuge some love by learning from the experience of others
Operating a Decanter for Extreme Weather Conditions
Your centrifuge may be subject to severe weather: rain, snow, and freezing temperatures.
A Proactive Approach to Ensure More Centrifuge Uptime
Centrifuge inspections shouldn’t be viewed as a burden. Knowing the condition of your centrifuge or sludge thickener will reduce repair costs and enhance performance reliability. Not only that, but a forward-thinking centrifuge maintenance plan allows for proactive budgeting and a safer environment for your plant operators. For these reasons and more, Centrisys has developed the Centrifuge Service Inspection (CSI) Program, a 40+ point inspection for your decanter centrifuge or sludge thickener.
Maintaining the Optimum Differential Speed
EIn most cases, the differential speed of a decanter centrifuge is set by the manufacturer or service provider based on the customer’s application for dewatering or sludge thickening. Optimization of the differential speed of the bowl and scroll may be necessary to achieve optimal solids removal and the driest cake.
The Importance of Balancing a Decanter at Operational Speed
Just as a centrifuge’s differential speed needs to be recalibrated if it’s running outside its normal operating parameters, a centrifuge bowl and scroll will need to be rebalanced under certain conditions. This section will cover the ins and outs of balancing a centrifuge and why it’s important to balance at operational speed.
Why Balance a Decanter Centrifuge?
An out-of-balance decanter centrifuge is like having unbalanced car tires. When a tire is out of balance, it bounces against the road, which results in multiple performance problems involving steering, speed, safety, and the premature wear and tear of parts. Underestimating the power of accurate centrifuge balancing is a big mistake. High vibrations cause premature damage and wear to centrifuge parts and structural components, creating more expensive repair costs and unnecessary process downtime.
Where and How Should a Decanter Centrifuge be Balanced?
It's important to balance a centrifuge at operating speed. Centrifuges can run at very high speeds: 2000 to 4000 times the speed of gravity (what is referred to as G-force). The only way to accurately balance a centrifuge bowl and scroll is to balance them at their normal operating speeds.
