Pumps capacity, temperature

Feed Slurry Temperature Temperature can be both an aid and a limitation. As temperature of the feed slurry is increased, the viscosity of the hquid phase is decreased, causing an increase in filtration rate and a decrease in cake moisture content. The limit to the benefits of increased temperature occurs when the vapor pressure of the hquid phase starts to materially reduce the allowable vacuum. If the hquid phase is permitted to flash within the filter internals, various undesired resiilts may ensue disruption in cake formation adjacent to the medium, scale deposit on the filter internals, a sharp rise in pressure drop within the filter drainage passages due to increased vapor flow, or decreased vacuum pump capacity. In most cases, the vacuum system should be designed so that the liquid phase does not boil. 

Process flow diagrams are more complex and show all main flow streams including valves to enhance the understanding of the process as well as pressures and temperatures on all feed and product lines within all major vessels and in and out of headers and heat exchangers, and points of pressure and temperature control. Also, information on construction materials, pump capacities and pressure heads, compressor horsepower, and vessel design pressures and temperatures are shown when necessary for clarity. In addition, process flow diagrams usually show major components of control loops along with key utilities. 

For proper selection and corresponding operation, a pump capacity must be identified with the actual pumping temperature of the liquid in order to determine the proper power requirements as well as the effects of viscosity. 

However, all pump discharges are subject to friction and other losses, and it is therefore necessary to refer to various pump curves and design data in order to establish the correct pump design and to provide a precise match in terms of pump capacity, FW temperature, head demands, and mode of pump operation. 

Because the quantity of crude carried over in the gas exceeded the knock-out boot pump capacity, the temperature had to be lowered to about 86°F (30BC] so that the entrainment decreased to a manageable quantity. Attempts to reach the design operating temperature did not improve the situation. 

The sample container rests on a boundary layer at the top of the shelf surface. Such a layer is a region where the flow of heat transfer fluid is minimal or zero (i.e. the fluid is stationary). As a result, the sublimation step, which involves the transfer of heat from the fluid to the shelf surface, creates a temperature gradient across the boundary layer that depends on the thermal load exerted by the sublimation process and on the nature (viscosity, thermal conductivity and flow across the shelves) of the heat transfer fluid. The temperature gradient also depends on the number of shelves, their design and build, and on the pumping capacity of the circulation pump. These variables in turn depend on the size and particular manufacturer of the freeze-dryer, so the software used should include an input of data for the materials used, and for the dryer s design and build. 

Temperature control by this strategy is not balanced for adiabatic cooling to allow recovery if the target temperature is undershot however, it does permit higher heat transfer rates without wall fouling encountered from jacket cooling. An additional caution is required for vessels with retreat curve impellers. These have adequate pumping capacity for solids suspension but seldom... 

The advantage of a semicontinuous flow reactor is that only pure SCF needs to be pumped. Standard HPLC pumps can be used without fear of clogging the check valves. As in all flow reactors it is necessary to sub-cool the fluid to avoid cavitation and loss of pumping capacity. With CO2 it is usually enough to cool to approximately -5 °C at the pump head. A cooling jacket around the pump head is needed experience suggests that the temperature of the cooling liquid should be about -20 °C. 

Since the source pressure has to be maintained within the pumping capacity or conductance of the vacuum system, low carrier gas flow rates are necessary or various types of interface are used to reduce the carrier gas component in the GC effluent. Interfaces and transfer lines have to be maintained at or above the maximum column temperature used. 

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