Piping drops

Figure 4-6 Pipe hangers corrode and pipe drops to the ground.

Water is pumped into a pipe at the rate of 250 kg/hr at 950 kPa and 175°C. Because of friction in the pipe, pressure losses due to pipe fittings and valves, the pressure at the exit of the pipe drops to 760 kPa. Is the entering water liquid, vapor, or a mixture of both Determine the fraction of each. Is the exit water liquid, vapor, or both Determine the fraction of each. From the steam tables or similar source, determine the density of the overall mixture in the pipe at both locations. How many degrees of freedom exist according to the phase rule at each location ... 

Ellis, G.H. (1920). Car for current-meter gaging stations. Engineering News-Record 84(2) 80. Ellis, G.H. (1920). Hydraulics of the intake to a pipe drop. Engineering News-Record 85(12) 565. 

Alarm and monitoring unit - this unit Is fitted Immediately above the control valve and monitors the pressure In both sides of the control valve. An alarm is activated If the pressure In either the supply pipes or the range pipes drops or a flow of water is detected in the system, which indicates the operation of a sprinkler head. 

The measurement of a crude oil s viscosity at different temperatures is particularly important for the calculation of pressure drop in pipelines and refinery piping systems, as well as for the specification of pumps and exchangers. 

As in the construction industry, piling of the conductor is done by dropping weights onto the pipe or using a hydraulic hammer until no further penetration occurs. In an offshore environment the conductor is either piled (e.g. on a platform) or a large diameter hole is actually drilled, into which the conductor is lowered and cemented. Once the drill bit has drilled below the conductor the well is said to have been spudded. 

The gas processing options described in the previous section were designed primarily to meet on-site usage or evacuation specifications. Before delivery to the customer further processing would normally be carried out at dedicated gas processing plants, which may receive gas from many different gas and oil fields. Gas piped to such plants is normally treated to prevent liquid drop out under pipeline conditions (dew point control) but may still contain considerable volumes of natural gas liquids (NGL) and also contaminants. 

A fume hood is constructed in the manner shown in figure 6. Strike drew the frame as being made of lumber but it can be made of rebar or, preferably, from PVC pipes and joints so that it can be assembled and disassembled with ease. The frame is enclosed with plastic drop cloths or any semiclear plastic sheeting. The front face of the hood is halfway covered with plastic while the bottom half is exposed to allow one to move objects in or out and to manipulate things. On top of the chamber is attached some clothes dryer duct or some such crap which is led to a leaf blower or blower motor. The exhaust from the blower is led away to the outside. 

Measurement Requirements. Any analysis of measurement requirements must begin with consideration of the particular accuracy, repeatabihty, and range needed. Depending on the appHcation, other measurement considerations might be the speed of system response and the pressure drop across the flow meter. For control appHcations repeatabihty may be the principal criterion conversely for critical measurements, the total installed system accuracy should be considered. This latter includes the accuracy of the flow meter and associated readout devices as well as the effects of piping, temperature, pressure, and fluid density. The accuracy of the system may also relate to the required measurement range. 

Flow Nozzles. A flow nozzle is a constriction having an eUiptical or nearly eUiptical inlet section that blends into a cylindrical throat section as shown in Figure 8. Nozzle pressure differential is normally measured between taps located 1 pipe diameter upstream and 0.5 pipe diameters downstream of the nozzle inlet face. A nozzle has the approximate discharge coefficient of an equivalent venturi and the pressure drop of an equivalent orifice plate although venturi nozzles, which add a diffuser cone to proprietary nozzle shapes, are available to provide better pressure recovery. 

Good gas distribution is necessary for the bed to operate properly, and this requites that the pressure drop over the distributor be sufficient to prevent maldistribution arising from pressure fluctuations in the bed. Because gas issues from the distributor at a high velocity, care must also be taken to minimize particle attrition. Many distributor designs are used in fluidized beds. The most common ones are perforated plates, plates with caps, and pipe distributors. 

Figure 13 shows two pipe distributors, one in a branched and one in a ring configuration. These distributors minimize weeping, have good turndown, may requite the lowest pressure drop, and avoid the need for a plenum chamber. They are also well suited to multiple-level fluid injection. The disadvantages of these distributors are that there are defluidized soHds beneath the distributor and the mechanical design is more complex. 

In pipe distributors, the pressure drop requited for good gas distribution is 30% of the bed pressure drop for upward facing holes, but only 10% for downward facing ones. The pressure drop calculation and the recommended hole density are the same as for a perforated plate. To maintain good gas distribution within the header system, it is recommended the relation... 

The pressure drop accompanying pipe flow of such fluids can be described in terms of a generalized Reynolds number, which for pseudoplastic or dilatant fluids takes the form ... 

The upward flow of gas and Hquid in a pipe is subject to an interesting and potentially important instabiHty. As gas flow increases, Hquid holdup decreases and frictional losses rise. At low gas velocity the decrease in Hquid holdup and gravity head more than compensates for the increase in frictional losses. Thus an increase in gas velocity is accompanied by a decrease in pressure drop along the pipe, a potentially unstable situation if the flows of gas and Hquid are sensitive to the pressure drop in the pipe. Such a situation can arise in a thermosyphon reboiler, which depends on the difference in density between the Hquid and a Hquid—vapor mixture to produce circulation. The instabiHty is manifested as cycHc surging of the Hquid flow entering the boiler and of the vapor flow leaving it. 

Measurement by Electromagnetic Effects. The magnetic flow meter is a device that measures the potential developed when an electrically conductive flow moves through an imposed magnetic field. The voltage developed is proportional to the volumetric flow rate of the fluid and the magnetic field strength. The process fluid sees only an empty pipe so that the device has a very low pressure drop. The device is useful for the measurement of slurries and other fluid systems where an accumulation of another phase could interfere with flow measurement by other devices. The meter must be installed in a section of pipe that is much less conductive than the fluid. This limits its appHcabiHty in many industrial situations. 

A distributor is frequently installed at the top of the column for use during backwash. It collects water evenly and prevents resin from escaping the column should unexpected surges develop in the water flow during backwash. Columns lacking an upper distributor or screen to prevent loss of resin should have an external system to prevent resin from being lost to the drain. It is referred to as a resin trap and may consist of a porous bag that fits over the outlet pipe or a tank designed to lower the linear velocity. Resin drops to the bottom of the tank and is returned to the column when convenient. 

---