Piping capacities

A pipe with accumulated mineral deposits, (left) The lengthwise section shows the formation of scale, (right) The cross section clearly indicates the reduction in pipe capacity. 

Heat pipe capacity (GJ/h) Area of permeation (m ) Methane conversion Steam conversion Product gas temperature ( K) Hydrogen yield... 

Ditches must be designed and constructed with sufficient carrying capacity for the anticipated runoff flow. Local contractors experience may be the best source of design data. If needed, porous pipe capacities may be obtained from the manufacturer, and the amount of water a gravel-filled ditch can carry may be estimated as illustrated in the example which follows ... 

A pipe with accumulated mineral deposits. The cross section clearly indicates the reduction in pipe capacity. 

Loss of efficiency. Insulation of heat exchanger tubings and pipelines by corrosion products reduces heat transfer and piping capacity. 

If the pump characteristic (discharge pressure vs. flow rate) is fairly flat and system frictional losses are quite small over the entire operating region, choose a linear valve. However, this situation occurs infrequently, because it results from an overdesigned process (pump and piping capacity too large). 

No internal piping and no conventional filter valve are needed with single-cell dmm filters where the entire dmm also operates under vacuum. The cake discharge is effected by air blowback from an internal stationary shoe mounted inside the dmm at the point of discharge. There are very close tolerances between the inside surface of the dmm and the shoe in order to minimize the leakage. The inside of the dmm acts as a receiver for the separation of air and filtrate conventional multicompartment dmm filters require a separate external receiver. This type of filter permits operation of the filter with thin cakes so that high dmm speeds, up to 26 rpm, can be used and high capacities can be achieved. Sizes up to 14 m are available. 

Assemblies of small disks are rotated in a planetary movement around a central screw conveyor. The disks are mounted on six hoUow axles and the axles revolve on overhanging bearings from the gearbox at one end of the vessel where they are driven, via a drive shaft, by an electric motor. The filtrate is collected from the disks via the hoUow shafts and a filter valve into a large collecting pipe. The hoUow shafts also collect the water and air from the dewatering process, in another part of the rotational cycle. The number of disks mounted on the shafts can be adjusted for different materials, depending on the required capacity and the cake thickness to be used. 

Handling Temperatures. Optimum temperature for pumping is in 37—48°C range. Piping should be stainless steel, aluminum, or galvanized iron. Valves and pumps should be bronze, cast-iron with bronze trim, or stainless steel. A pump of 3.15-L/s (50-gal/min) capacity unloads a tank car of warm glycerol in ca 4 h. 

Pipe StiU furnaces vary greatly and, in contrast to the early units where capacity was usuaUy 31.8—79.5 m /d (200—500 bbl//d), can now accommodate 3975 m (25,000 bbl) or more of cmde oU per day. The waUs and ceiling are insulated with firebrick and the interior of the furnace is partiaUy divided into two sections a smaller convection section where the oU first enters the furnace and a larger section fitted with heaters where the oU reaches its highest temperature. 

Pipe attachment devices are either integral or nonintegral with the shell of the pipe. The particular type is selected according to load-carrying capacity, severity of service, and the desirability of welding directly to the pipe. 

Cylindrical tmnnions are of more favorable contour for stress distribution and frequently are used in high temperature services. Their load-carrying capacity is high and their stmctural effect on the pipe shell can easily be deterrnined. 

Skirts are used in vessels and towers. They transmit high axial and bending loads and offer favorable geometry for thermal gradients. In piping, when loads are beyond the capacity of lugs and tmnnions, skirts are often favored. 

Packed-type joints are significant for their large-movement capacities and mggedness in body constmction. When properly adapted into a piping system, their performance is satisfactory in both moderate and severe services. However, as with any packed element subject to motion, joints of this type require occasional tightening and repacking. 

The Mid-America Pipeline System (MAPCO) (77) for ammonia transportation contains 1763 kkometers of 101 mm, 152 mm, and 203 mm pipe having a pumping capacity of 3885 metric tons per day and supporting terminal storage fackities. Peak dehvery from the system is 4,216 metric tons per day. 

The Gulf Central Pipeline system (78) contains 3220 km of 152 mm, 203 mm, and 254 mm pipe and has a pumping capacity of 2545 metric tons per day and supporting terminal storage fackities. The Tampa Bay Pipeline network services several ammonia plants along a 133 km route. 

Capacity. Pumps deHver a certain capacity, Q, sometimes referred to as flow, which can be measured directly by venturi, orifice plate (11), or magnetic meters (12) (see Flow measurement). The indirect way to determine capacity is often used. Whereas this method is less accurate than applying a flow meter, it often is the only method available in the field. The total head is measured and the capacity found from the pump head—capacity (H— curve (Fig. 2). More recently, sonic flow meters (13) have been used, which can be installed on the piping without the need for pipe disassembly. These meters are simple to use, but require relatively clean single-phase Hquid for reHable measurements. 

Magnetic filters have been used to clean paint sHps and Hquids. Filters that are open to the atmosphere or closed, ie, pressure type, are available where the filter inlets are matched to standard pipe connections from 10 to 50 mm, for low capacity appHcations. 

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