Nutsche Filter Dryer Design Considerations

There are many different applications, process requirements and preferences to consider for filtration and drying equipment. Pope’s applications professionals are on hand to assist clients with specification and quotation of optimized Nutsche filter dryers.

Pope’s Custom Nutsche Design Considerations

Larger custom Nutsche filter dryers are available in volumes including 10, 20, 30, 40, 50, 100, 200, and up to 1000 liters, plus any special volumes in between. “Typical” units are offered providing a similar feature set as the Pope Benchtop series, but can be customized with a broad range of unique options. 316L stainless steel construction is standard, other alloys, coatings and special finishes are available. ASME certification is standard, CE/PED and others also available.

The starting point for this is our Nutsche Application Questionnaire. Sizing of units typically depends on the total slurry volume, the quantity of expected filter cake; Pope’s Nutsche Cake Depth Volume Chart is utilized in this determination. Other design considerations include:

Vessel Flanges

Sanitary clamp type flanges can be utilized on up to 10” diameter vessels. The lower flange is a special variation that allows for holding and sealing a variety of filter screens and fabrics. Upper removable lids and flanges are also available. Beyond 10” diameters, heavy duty flanges with bolts or clamps are utilized.

Geometry

The most basic vessel geometry is a single lower flange only. With this design, the entire body is raised up, or the bottom end is lowered from the body to harvest the filter cake. Another option is to also have a removable top head. This provides the user with two means of access and harvesting, removing either the top or the bottom head, or both. Some users prefer to have an additional flange for vessel break-apart a short distance or midway up from the bottom filter flange. This allows teh filter cake to be contained when the upper section of the vessel is removed, and convenient cake harvesting without spillage. There are other variations including “removable basket” design. See photos for examples.

Support

Nutsche vessels normally come with legs with locking castors. Depending on geometry, (see above) the number and location of legs may vary. With vessels larger than 8” diameter, the vessel sections can become heavy and inconvenient for manual movement and lifts are typically provided for safe raising/lowering and movement across rooms. Variations can include self-contained lifts, platforms, and specialized frame for manual or automated rotation of vessel. See photos for examples.

Agitation

In many cases, though not all, some means of agitation is required or preferred. Pope’s Series 700, 800 or 900 mixers are offered for conventional type stirring of slurry before or during filtration or after reslurrying. Raising/Lowering cake churning and smoothing agitators are also offered. These provide greater efficiency in breaking up clumps and shortening drying time. Pope’s cake agitators can also be utilized for removing the filter cake from the Nutsche. An “S” shaped blade can dig into the cake, smooth it, and discharge through a side valve.

Heating

Vessel jacket heating is offered to help in drying the filter cake. Heated dry air or nitrogen can also be admitted at a fixed rate. These, in conjunction with vacuum and cake agitators optimize drying efficiency. Electric heaters are available as an alternative to liquid jackets on Pope’s smaller units.

Filters

Multi layers stainless steel filter screens are available from 1 to 200 micron pore size. 20 micron filters are “standard”, covering a wide range of applications. In addition, polypropylene cloth and other special type membrane filters can be used. Pope’s designs provide customers with a choice and changing from one type to another without any further Nutsche unit modification.

Other Features

Many options are offered including sight glasses, valving, pressure and temperature indication/control, other sensors, sampling ports, spray head, and side discharge harvesting ports. Special skid mounted systems combining liquid and vacuum pumps, reactors, control systems and other turnkey features are also available. Pope also works with companies focused on containment for operator protection, such as with HPAPI’s, or product protection and can offer both flexible and rigid isolation solutions.