Slurry service

Both wetted-sensor and clamp-on Doppler meters ate available for Hquid service. A straight mn of piping upstream of the meter and a Reynolds number of greater than 10,000 ate generally recommended to ensure a weU-developed flow profile. Doppler meters ate primarily used where stringent accuracy and repeatabiHty ate not requited. Slurry service is an important appHcation area. 

FIG. 10-53 Pneumatically actuated diaphragm pump for slurry service. (Coutiesy of Dotr-Olvier Inc.)... 

These special throttling valves use an elastomer diaphragm to restrict or stop flow (Figure 15-7). They are suitable for slurry service and make an excellent valve for sand drains. Unfortunately, they do not provide a reliable, positive shut-off and should be installed in series with a ball or other on/off valve if positive shut-off is required. 

Pinch The industrial equivalent of controlling flow by pinching a soda straw is the pinch valve. Valves of this type use fabric-reinforced elastomer sleeves that completely isolate the process fluid from the metal parts in the valve. The valve is actuated by applying air pressure directly to the outside of the sleeve, causing it to contract or pinch. Another method is to pinch the sleeve with a linear actuator with a specially attached foot. Pinch valves are used extensively for corrosive material service and erosive slurry service. This type of valve is used in applications with pressure drops up to 10 bar (145 psi). 

Top- and side-mounted level switches for sludge or slurry services. (Courtesy of Delavan, Inc.)... 

In slurry service, UF is used primarily as a concentration technology. The UF reject stream can then be recycled back to a tank containing the concentrated slurry that can then be dewatered with a filter press. The permeate will contain little, if any, suspended solids and can be sent for metals removal treatment or to recycle/reclaim if metals have already been removed. 

Exchanger tube diameters of 2.54 cm (I in.) are recommauded to prevent blockage by small chunks, Spisal heat exchnagers also work quite well in slurry service. 

FIG. 10-53 Pneumatically actuated diaphragm pump for slurry service. 

EXHIBIT 8-24 Primary and Standby Pump for Hot Slurry Service... 

Hjn = head developed in slurry service, metres of slurry... 

Fig. 2. Definition of the cavitation inception point (flow rate Qc) when pumping slurries. Hw and Hm are heads for water and slurry, respectively. The influence of cavitation, He, is defined as a 3% reduction of the head (Hm) developed in slurry service.

Problems in Slurry Service Instrumentation, presented at National ISA Conference, Houston, Tex. 1951. 

Slurry steam generators. The mechanical design of heat exchangers for slurry service should not differ greatly from that for solution service. However, the design must assure that... 

In slurry service, metallic trims such as those above have been satisfactory for low-pressure valves but unsatisfactory for long life in high-pressure service. Ceramic materials appear promising, but little experience has been obtained to date. 

Slurry service valves. In addition to the erosiveness of slurries, other problems are introduced by their tendency to settle out in the primary bellows seal or at stem guiding surfaces, thus interfering with valve action. This may be avoided by purging slurry from the bellows compartment with distilled water. It is likely that the hydrodynamic design of slurry valves... 

Capacitance Prohe. An aluminum oxide capacitance prohe, manufactured by Fielden Instrument Division, has been recently received by ORNL but has not yet heen evaluated. This instrument senses the dielectric constant of the medium it contacts. Its ceramic-to-metal seal is rated at 2000 psi and 636°F. This type of instrument may prove useful in water or slurry service. 

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