Pipeline Mixing Applications

Pipeline devices are used in a broad spectrum of applications (Table 7-2). Performance criteria are well established. 

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Static mixers are widely used in situations where continuous in-line or pipeline mixing is required. Table 9.17 shows that applications span the entire spectrum from laminar to turbulent flow regimes, and they cover a wide variety of mixing processes involving the blending of gas-gas... 

When the flow is laminar, either single or multiphase, there is only one design class option static or motionless mixers. Other pipeline mixing devices described for turbulent flow are not usable for even the simplest mixing applications in the laminar regime. All rely on turbulence and cannot function at low Reynolds numbers. The only alternative technology is in-line dynamic mixers, which include extruders, rotor-stator mixers, and a variety of rotating screw devices. None of these has the benefits of simplicity and the little or no maintenance characteristic of static mixers. In-line mechanical mixers are discussed briefly later in the chapter. 

Fine chemicals There are many applications of the austenitic steels in the manufacture and storage of fine chemicals and pharmaceutical products. These include storage tanks, pipelines, valves, stills, steam-jacketed pans, mixing vessels, filters and tableting machinery. Considerable use has been made of these steels in penicillin production. 

Another interesting application of the data in Fig. 2.20 for dispersion coefficients in turbulent flow is in calculating the mixing that occurs in long pipelines. Many refined petroleum products are distributed by pipelines which may extend over hundreds of kilometres. The same pipeline is used to convey several different products, each... 

Mixed with additives, urea is used in solid fertilizers of various formulations, eg, urea—ammonium phosphate (UAP), urea—ammonium sulfate (UAS), and urea—phosphate (urea + phosphoric acid). Concentrated solutions of urea and ammonium nitrate (UAN) solutions (80—85 wt%) have a high nitrogen content but low crystallization point, suitable for easy transportation, pipeline distribution, and direct spray application. 

Rigid foams are based primarily on polyfunctional, low molecular weight alcohols and amines. Most global applications conventionally use polymeric isocyanates, TDI, or an undistilled grade of mixed TDI isomers. TDI prepolymers which have hydroxyl and isocyanate groups have been marketed as a low vapor pressure alternative to undistilled TDI. Density reduction is effected via the addition of chlorofluorocarbons, low molecular weight alkanes, or via the in situ generation of carbon dioxide. The resultant closed cell foams find applications as insulators in construction, appliance, transportation, pipeline, and tank end uses. 

The cost of transporting wood chips by truck and by pipeline as a water slurry was determined. In a practical application of field delivery by truck of biomass to a pipeline inlet, the pipeline will only be economical at large capacity (>0.5 million dry t/yr for a one-way pipeline, and >1.25 million dry t/yr for a two-way pipeline that returns the carrier fluid to the pipeline inlet), and at medium to long distances (>75 km [one-way] and >470 km [two-way] at a capacity of 2 million dry t/yr). Mixed hardwood and softwood chips in western Canada rise in moisture level from about 50% to 67% when transported in water the loss in lower heating value (LHV) would preclude the use of water slurry pipelines for direct combustion applications. The same chips, when transported in a heavy gas oil, take up as much as 50% oil by weight and result in a fuel that is >30% oil on mass basis and is about two-thirds oil on a thermal basis. Uptake of water by straw during slurry transport is so extreme that it has effectively no LHV. Pipeline-delivered biomass could be used in processes that do not produce contained water as a vapor, such as supercritical water gasification. 

An innovative technique involving the preparation of a lower-viscosity unstable slurry-emulsion system by mixing water with the oil as a means of conveying crude oil has yet to be proven on a commercial scale. The technical problems and issues limiting the application of this technique (analogous to crude-oil emulsion pipelining) are to sustain the two immiscible liquids in a stable emulsion during transport and to destabilize the emulsion... 

Limestone is generally applied from boats, which use the lake water to prepare a slurry containing up to 30 % by weight of calcium carbonate. Some systems prepare the slurry either on the lake shore, or adjacent to a nearby road, and pump the slurry via floating pipelines to a boat which disperses the slurry over the surface of the lake. Aerial application from fixed wing aircraft and helicopters is also used for remote lakes, using either powder, or pre-mixed slurry. 

Numerous construction products are formulated from asphalt and coal tar for such applications as driveway sealers, cutback asphalts, flashing cements, conerete primers, concrete cold mixes, roof cements, expansion joint fillers, patch liquids, waterproofing liquid-applied membranes, and pipeline eoatings. All these produets are likely to contain... 

The commoner and preferred alternative is to use air coolers of simple design. The heated ambient air up to temperatures of 250-400 C is mixed with the quench air of the NSD spray tower furnace. This direct application of heat is simple and cheap provided that the distance between the sulphonation operation and the NSD spray tower is no more than 1(X) m. A lagged pipeline connects the sulphonation plant and the spray tower furnace. 

In tnrbnlent flow, if there are no time or length restrictions, the simple pipeline nses the minimum energy and is often the best choice for blending applications. If there are energy limitations, the energy for mixing must be supplied by either the main stream or the side stream. 

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