Solid Piston Pumps

Positive displacement slurry pumps are used in a number of industries (Table 9-1). Solid piston pumps are reserved for the pumping of slurries of a low to medium abrasiveness (Miller Number <50) such as chalk slurry, fine coal, flotation material, and driUlng mud sludge. 

The solid material is placed into a small vial that is introduced into a thermostated high-pressure chamber (volume 79 ml). The vial is attached to a suspension device that is magnetically coupled to the balance during measurement. The device is lowered to a neutral position when no recording of a mass point takes place, thus allowing for the balance to be tared before each measurement. This is of particular importance in slow processes in which thermodynamic equilibrium is attained only in the course of several hours or even days. The chamber may be evacuated with a vacuum pump at the beginning and at the end of each experiment. The dense gas is taken from a cylinder and, if necessary, compressed to system pressure with the help of a membrane piston pump. 

Microwave-assisted solid sample treatment PISTON PUMP... 

To minimize degradation of impurities, low-speed (1800 rpm) pumps with open impellers should be used. Where solids are large and floc-like, it may be advisable to use a recessed impeller centrifugal pump or a multistage piston pump with suitable aircushioning chambers. Reciprocating pumps should have ball valves. Gear or rotary pumps may be used where solids are not abrasive and filter aid is not present. 

Figure 5.3. An example of the proportioning accuracy of a reciprocating-piston pump in the composition range 0-10% B in 1% increments (A). The influence of the design of the solvent delivery system on gradient shape (B). The Broken line describes the set gradient and the solid line the gradient delivered to the column inlet. The dwell time is marked as tp.

Fig. 11.9. Schematic diagram of a filter press 1, piston pump 2, filtrate collector 3, standard tray 4, membrane tray 5, solid stainless-steel frame 6, compressed air circuit 7, polypropylene cloth 8, tank with pneumatic buffer 9, central input of product to be clarified...

Figure 4 Experimental setup used to integrate MAE with the subsequent steps of the analytical process. (1) Leaching step. CT, controller MO, microwave oven S, sample R, refrigerant WR, water reservoir TCPP, two-channel piston pump ER, extract reservoir (2) Clean-up/preconcentration step. SV, selecting valve M, methanol A, air B, buffer PP1 and PP2, peristaltic pumps F, filter EL, elution loop MC, minicolumn R, retention direction E, elution direction IV1-IV3, injection valves W, waste. (3) Individual separation-detection step. HPIV, high-pressure injection valve AC, analytical column DAD, diode array detector SR, solvent reservoirs. (Reproduced with permission from Luque de Castro MD and Luque-Garcfa JL (2002) Acceleration and Automation of Solid Sample Treatment Elsevier.)...

Automation of analyses involving liquid samples is facilitated by their usually adequate homogeneity and easy mechanical handling by use of peristaltic or piston pumps, or some other liquid management devices, i.e. a liquid driver. Nonetheless, this is not the case when dealing with solid samples, analysis of which frequently involves their prior conversion into liquids by dissolution. The dissolution step is the bottleneck of analytical processes involving solid samples, as it is frequently slow and must be performed manually. 

Wallrafen, G. 1983. Piston Pumps for the Hydraulic Transport of Solids. Bulk Solids Handling, 3, 1. Wallrafen, G. 1985. Backfilling with Viscous Slurry Pumps. Bulk Solids Handling 5, no. 4 Wilson-Snyder. 1977. Slurry Pumps. Texas Wilson Snyder. Publication ADWS 28-77 (3M). SmithW.1985. Construction of Solids-Handling Displacement Pumps. Chapter 9-17-3 in The Pump Handbook, Karassik 1. J., W. C. Krutzch, W. H. Fraser, and J. P. Messina (Eds.). New York McGraw-Hill. 

For surface application, first the compatibility with the other chemicals used in the preparation and also the shear stability have to be checked (e. g. with starch, optical brightener, dyes). It is advisable to meter the undiluted polymer by means of a piston pump to the circuit of the size-press, e. g. before the feed pump. To achieve a good effect, the PSA must penetrate sufficiently into the paper, e. g. an adequate quantity of sizing solution must be taken up. Quantities of 2-4 g solid polymer in combination with 40-80 g 1 starch are normally sufficient to achieve a hard sized paper sheet 1-2 g 1 solid polymer is sufficient for final sizing of a paper that has been presized internally. 

For metering, suitable devices are used, such as various types of balances containers or weigh hoppers, belt weigh types, etc., for gravimetric weighing or travelling band conveyer or screw conveyer for solid materials and rotameters, piston pumps, etc., for liquid components, in the case of volumetric metering [44]. 

Descriptions of Physical Objects, Processes, or Abstract Concepts. For example, pumps can be described as devices that move fluids. They have input and output ports, need a source of energy, and may have mechanical components such as impellers or pistons. Similarly, the process of flow can be described as a coherent movement of a liquid, gas, or collections of solid particles. Flow is characterized by direction and rate of movement (flow rate). An example of an abstract concept is chemical reaction, which can be described in terms of reactants and conditions. Descriptions such as these can be viewed as structured collections of atomic facts about some common entity. In cases where the descriptions are known to be partial or incomplete, the representation scheme has to be able to express the associated uncertainty. 

For the production of white wine, it is almost universally accepted that a relatively clear juice of 0.5-2.0 percent suspended solids is desired for fermentation. This is achieved by separating the juice from the skins, pulp, and seeds. Many of the small wineries use a horizontal basket press to receive their fresh must. These presses utilize either an inflatable bladder or a movable piston to press the crushed grapes. In many cases, the must is pumped directly to these presses from the crusher-stemmer. An exception to this method of operation in small wineries is the case where skin contact is desired. Several wineries will allow maceration for from four hours to twenty-four hours for V. vinifera cultivars Chardonnay and Gewiirztraimer. 

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