Dual pressure ports

As mentioned in the previous section, a major drawback of the simplex atomizer is the poor atomization quality at the lowest flow rate due to too-low pressure differential if swirl ports are sized to allow the maximum flow rate at the maximum injection pressure. This problem may be resolved by using dual-orifice, duplex, or spill-return atomizers. Alternatively, the atomization processes at low injection pressures can be augmented via forced aerodynamic instabilities by using air or gas stream(s) or jet(s). This is based on the beneficial effect of flowing air in assisting the disintegration of a liquid j et or sheet, as recognized in the application of the shroud air in fan spray and pressure-swirl atomization. 

Fig. 2.4. Schematic view of the modular capillary electrochromatograph with a 90 kV dual power supply and pressurisable chambers for column inlet en outlet (reproduced from Ref. [26] with permission of the publisher). 1, 60 kV power supply 2, 30 kV power supply 3, digital electrometer 4 and 5, electrodes 6 and 7, reservoir for mobile phase or the sample 8, pressurisable chambers 9, packed capillary column 10, cell for on-column detection 11, detector 12, four-port two-way valve 13, four-port three-way valve 14, pressure gauges 15, from nitrogen cylinder 16, vent 17, ground.

Figure 1 is a schematic of one of the two supercritical flow reactors used in this work. The system is first brought up to the operating pressure by an air compressor. An HPLC pump forces the reactant solution through the reactor, the ten-port valve and dual-loop sampling system, and into the product accumulator, where the flow of products displaces air through a back-pressure regulator. The reactant inflow is rapidly heated to reaction temperature by an electric entry heater/water jacket combination, and maintained at isothermal conditions by a Transtemp Infrared furnace and an exit electric heater/water jacket combination. 

The RO system consists of nine first-pass and three second-pass skids. The RO membranes are 20 cm spiral-wound TFC polyoxide type. The membrane pressure vessels have side-entry front/rear permeate ports. The high-pressure first-pass SWRO unit is supplied by a multi-pump system (three on-Hne, one on-standby). The SWRO feed pressure is 60 bar g TDH (total dehvery head). The second-pass RO unit treats the first-pass permeate and, therefore, operates at much lower feed pressure. The SWRO unit deploys dual work exchanger energy recovery devices. The plant is among the most energy efficient in the world, with an average efficiency of 3.58 kWh/m. The ERDs recover about 97% of the energy required to convert seawater to product permeate. 

Liquid level in crystallizers usually is controlled by measuring the pressure differential between the vapor space and some poim in the crystallizer. Problems are encounter with this approach because of changitig liquid properties due to boiling and the presence of solids. Sometimes dual systems are used to increase the reliability of level control. Many crystallizers have viewing ports to observe the liquid level. Closed-circuit television monitors can be us if level control is critical and/or extremely difficult. 

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