Liquid Process Streams

The basic reason for using different control-valve trims is to keep the stability of the control loop fairly constant over a wide range of flows. Linear-trim valves are used, for example, when the pressure drop over the control valve is fairly constant and a linear relationship exists between the controlled variable and the flow rate of the manipulated variable. Consider the flow of steam from a constant-pressure supply header. The steam flows into the shell side of a heat exchanger. A process liquid stream flows through the tube side and is heated by the steam. There is a linear relationship between the process outlet temperature and steam flow (with constant process flow rate and inlet temperature) since every pound of steam provides a certain amount of heat. 

Starting from this basis, the development and industrial use of a new generation of membranes adapted to the ultrafiltration and microfiltration of process liquid streams. 

The limiting factors for successful soil mixing treatment include the presence of boulders and subsurface utilities such as underground wires or piping. Depth to the water table may adversely impact the vapor extraction components effectiveness because vapor phase off-gas systems cannot process liquid streams. The vendor claims that depth to the water table may also influence lateral migration of processing gases. 

The power loss from a process liquid stream going through a pressure letdown valve could be significant. If a power expander is considered to replace the letdown valve, equation (8.1) could be used to estimate the power recovery potential, and a typical power generation efficiency for a liquid expander is 75%. 

For the process shown in Figure 4.1, a process liquid stream from the hot separator with mass rate of 1817.2gpm and pressure of 2635.3 psig reduces its pressure through a pressure letdown valve to the hot flash drum at 285.3 psig. Equation (8.1) gives an estimate of power recovery potential of 1.38 MW if a liquid expander is installed. 

Extensive reports of the Maillard reaction can be found in the scientific literature, most focus on aqueous systems, and few monitor the reaction with time. An interesting system for processing liquid streams of reactants under precise time-temperature conditions was described by Stahl and Parliment [1]. Analysis of the data resulted in a plot of flavor and color generation with time from which the kinetics of the reactions could be easily calculated. Gaining the same sort of data from food matrices that dehydrate on heating is more difficult, and there are few published reports. 

Sample Withdrawal from Process A number of considerations are involved in the design of sample-withdrawal devices that wih provide representative samples. For example, in a horizontal pipe that conveys process fluid, a sample point on the bottom of the pipe wih collect a maximum amount of rust, scale, or other solid materials being carried along by the process fluid. In a gas stream, such a location will also collect a maximum amount of liquid contaminants. A sample point on the top side of a pipe will, for liquid streams, collec t a... 

The orifice-riser distributor is designed to lay the hquid carefully onto the bed, with a minimum of contact with gas during the process. It can be designed to provide a large number of liquid streams, with the limit of sufficient liquid head to provide uniform liquid flow through the orifices. The gas risers must oe designed to accommodate the expected variations in flow rate, often with a minimum of pressure drop. For veiy distribution-sensitive packings, it is necessaiy to include pour points in the vicinity of the column wall (to within 25 mm). 

C. Liquid Distributor (see Figures 4-9). According to Strigle, This is the most important column internal from a process standpoint. A liquid distributor is required at all locations in the tower where an external liquid stream is introduced. High-performance distributors provide a flow rate variation per irrigation point that is a maximum of 5% of the average flow. The geometric uniformity of... 

There are a large number of processes in the chemical industries that handle a variety of suspensions of solid particles in liquids. The application of filtration techniques for the separation of these heterogeneous systems is sometimes very costly. If, however, the discrete phase of the suspension largely contains settleable particles, the separation can be effected by the operation of sedimentation. The process of sedimentation involves the removal of suspended solid particles from a liquid stream by gravitational settling. This unit operation is divided into thickening,... 

It is difficult to determine the point at which a condensate stabilizer becomes a gas plant. Typically, if the liquid product is sold as a condensate, the device would be considered a condensate stabilizer. If the product is sold as a mixed natural gas liquid stream (NGL) or is fractionated into its various components, the same process would be considered a gas plant. The least volatile NGL stream has an RVP between 10 and 14 and has sufficient light hydrocarbons such that 25% of the total volume is vaporized at 140°F. 

By decreasing the pressure and increasing the bottoms temperature more methane and ethane can be boiled off the bottoms liquid and the RVP of the liquid stream decreased to meet requirements for sales or further processing. Typical liquid recovery levels are ... 

The activated sludge process usually must be preceded by neutralization and some metal removal, and possibly by solids removal. The process is normally followed up by a separation step, usually sedimentation, to remove the biological sludge from the waste liquid stream. 

Many processes require the separation of immiscible liquid/liquid streams that is, water/hydrocarbon. The setding unit must be of sufficient height (diameter) and length to prev ent entrainment of the aqueous phase into the hydrocarbon and vice versa. Horizontal units are usually best for setding and possibly vented units for decanta-don (but not always). 

Waste Heat Boiler Produces steam from condensate or boiler feed water by removal of sensible heat from high temperature level process or waste gas streams. (Sometimes liquid streams serve this function.)... 

However, a strong caustic solution is used to remove mercaptans from gas and liquid streams. In the Merox Process, for example, a caustic solvent containing a catalyst such as cobalt, which is capable of converting mercaptans (RSH) to caustic insoluble disulfides (RSSR), is used for streams rich in mercaptans after removal of H2S. Air is used to oxidize the mercaptans to disulfides. The caustic solution is then recycled for regeneration. The Merox process (Fig. 1-3) is mainly used for treatment of refinery gas streams. ... 

The droplets so formed undergo desolvation as they traverse a heated region of the interface and ions are formed from analytes contained in the liquid stream by means of ion-molecule reactions, cf. chemical ionization, and/or ion-evaporation processes (see Section 4.7.1 below), depending upon the properties of both the liquid stream and the analyte. 

Electrospray The process whereby a liquid stream is broken up into droplets by the action of a high potential. 

The two different, but related, considerations in waste disposal are hazard control and loss prevention in the treatment and disposal operations, and the control of environmental hazards. With gas and liquid streams the control of on-site hazards arising from the chemical properties and processing operations generally follows the principles summarized in earlier chapters. The measures necessary with solid wastes may, however, differ, particularly if they are heterogeneous in nature and disposed of on land. 

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