Valves, and Pipes

As in SFC time ranges are shorter than on any other preparative chromatography technologies (some purifications can be handled with cycle times shorter than a minute), flow control is then a key point to obtain reproducible chromatograms. 

The pumps have to deliver a constant flow despite the high pressure that can be generated. The modifier pump pumps a liquid and its flow rate is easy to control. 

As CO2 is a compressible gas, a good control of the CO2 flow rate requires  

To summarize, SFC uses high-pressure liquid pumps, to introduce CO2, modifier, and the feed. These pumps are piston or membrane pumps. 

Compared to HPLC, SFC provides much higher efficiencies, so the piping has to be accordingly designed. From the introduction of the feed to the collection of the different fractions, the pipes are designed to minimize the volume, to avoid peak tailing and pollutions. 

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Solids materials that are insoluble in hydrocarbon or water can be entrained in the crude. These are called bottom sediments and comprise fine particles of sand, drilling mud, rock such as feldspar and gypsum, metals in the form of minerals or in their free state such as iron, copper, lead, nickel, and vanadium. The latter can come from pipeline erosion, storage tanks, valves and piping systems, etc. whatever comes in contact with the crude oil. 

The regenerative nature of the Wulff operation permits the recovery of most of the sensible heat in the cracked gas. The gases leave the furnace at temperatures below 425°C, thus obviating the need for special high temperature alloys in the switch valve and piping system. 

Chemical-Porcelain Pipe Made of dense, nonporous material and fired at 1230°C (2250°F), chemical-porcelain pipe, fittings, and valves are inert to all acids except hydrofluoric but are not usually recommended for alkalies. Surfaces, except when ground for gasketing, are usually glazed for easy cleaning. Working pressures of 0.3 to 0.7 MPa (50 to 100 Ibftin") are recommended for valves and piping. Temperatures of 200°C (400°F) or more can be used, but sudden thermal shocks must be avoided. 

This book is dedicated to pumps but we should mention that cavitation eould occur in other parts of the pumping system. Under the correct eireumstanees, valves and pipe elbows are also candidates to suffer damage from cavitation. 

Keep regulators, valves and piping on compressed gas systems clean and free from oil and grease Close the cylinder valve when not in use... 

P 1 diagrams contain four important pieces of information, namely, all vessels, valves and piping, along with a brief description and identifying specifications of each all sensors, instruments and control devices, along with a brief description of each the control logic used in the process and, finally, additional references where more detailed information can be obtained. 

Pressure-reduction valve and pipe leading to the flash tank... 

The MAWP of the vessel cannot exceed the MAWP of the no valves, and pipe connected to the vessel. As discussed in Volui Chapter 9, pipe flanges, fittings and valves are manufactured in dan dustry standard pressure rating classes. Table 12-2 is a... 

JE) Graphic. Symbols for Pipe Fittings, Valves and Piping, ANSI orASAZ32.2.3... 

The austenitic irons also show good corrosion resistance in caustic alkalis containing sulphides and mercaptans and have therefore proved useful materials for the construction of pumps, valves and piping in caustic soda regenerators in oil refineries. 

As mentioned earlier, pneumatic and hydraulic systems have been extensively used in hazardous environments to provide the power necessary to move and drive machinery to complete needed tasks. Their use has demanded development of complex logic systems which involve the addition of valves and piping. These logic control systems are often hard to design, debug, construct, and maintain. 

Are all major components, valves, and piping clearly and unambiguously labeled ... 

It should be noted that vapor depressuring may not be practical when the vessel design pressure is less than 100 psig (690 kPa) because valves and piping can become unreasonably large and costly or when the vapor depressuring load governs the size of pressure relief and flare headers. Refer to API RP 521,... 

A typical test loop includes a pump capable of pressure development to 1000 psig and sufficient valving and piping to permit multistation installation of fiber samples. Feed solutions are delivered from reservoirs which are thermostated and isolated in order to maintain constancy of temperature and composition. The facility is so established that both permeate and concentrate are returned continuously to the reservoir. 

Chromatographic systems are also designed to facilitate effective CIP. Internal surfaces of the column, its valves and piping, are smooth, impervious and devoid of recesses which could harbour microorganisms or other contaminants. 

Specifications for the equipment (storage tanks, heat exchangers, pumps, valves and piping components) to be used for water treatment and pretreatment... 

Blockages of valves and pipes can also occur by gas hydrates. Such adducts can be formed by a number of gases with water. In Fig. 7.1-5 the pressure-temperature diagram of the system propane/water with an excess of propane is presented. The line, (g), shows the vapour-pressure curve of propane. Propane hydrate can be formed at temperatures below 5.3°C. At pressures below the vapor pressure of propane a phase of propane hydrate exists in equilibrium with propane gas (Fig. 7.1-5, area b). At higher pressures above the vapor pressure of propane and low temperatures a propane hydrate- and a liquid propane phase were found (area d). In order to exclude formation of gas hydrates these areas should be avoided handling wet propane and other compounds like ethylene, carbon dioxide [14], etc. 

Q. Side-entering ports for acid, base, and antifoam addition (valved and piped as required)... 

Nuclear Boiler Assembly. This assembly consists of the equipment and instrumentation necessary to produce, contain, and control the steam required by the turbine-generator. The principal components of the nuclear boiler are (1) reactor vessel and internals—reactor pressure vessel, jet pumps for reactor water circulation, steam separators and dryers, and core support structure (2) reactor water recirculation system—pumps, valves, and piping used in providing and controlling core flow (3) main steam lines—main steam safety and relief valves, piping, and pipe supports from reactor pressure vessel up to and including the isolation valves outside of the primary containment barrier (4) control rod drive system—control rods, control rod drive mechanisms and hydraulic system for insertion and withdrawal of the control rods and (5) nuclear fuel and in-core instrumentation,... 

The temperature is controlled by a pressure control valve, which provides a technically simple system. The condensate drains from the jacket via a purge, which continues to maintain the required pressure in the system when the condensate is drained off (Figure 9.3). The drawback is that for high temperatures, the valves and piping system become heavy and expensive, for example, 240 °C requires a pressure of over 30 bar. Another important point is that when the... 

Consider again Eq. (6.11). Each valve and pipe fitting is to receive an independent pipe size resistance coefficient K. A number of works have been published that derive these coefficients for every type and size of pipe fitting and valve. Proposed here is a new variable we shall call ft. Referring to the Crane Technical Paper No. 410 [10], these ft variables are given in Table 6.1. 

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