Feed pipes

A thickener has several basic components a tank to contain the slurry, feed piping and a feedwell to allow the feed stream to enter the tank, a rake mechanism to assist in moving the concentrated sohds to the withdrawal points, an underflow solids-withdrawal system, and an overflow launder. The basic design of a bridge-supported thickener mechanism is illustrated in Fig. 18-86. 

The unit consists essentially of tvv o rotating elements, the outer being a solid-shell conical-shaped bowl and the inner comprising a helical-screw conveyor revolving at a speed slightly lovv er than that of the bowl. Raw feed sliiri v is delivered through a stationai"v feed pipe... 

Improper (non-symmetrical) feed piping to a distributor. Poor separation. Liquid maldistribution. Design en or. 

Solution Since the distributor annular space w as capable of handling the vapor flow, the riser was simply blanked off. Adding a hat or relocating the feed pipe w ere possible alternate. solutions. 

Torbaeke and Rasmuson (2001) report the empirieal influenee of different seales of mixing in reaetion erystallization of benzole aeid in a loop reaetor. The authors infer that the proeess is mainly governed by mesomixing in terms of liquid eireulation rate but find anomalous behaviour in respeet of feed pipe diameter. 

Einleitungsrohr, n. inlet tube, tube by which gases are introduced, feed pipe, elnlenken, v.t. guide (a missile, a ship), einleuchten, r.t. be clear. 

Zufluss, m. flow, flux, afflux, influx, inflow (Tech.) feed reaoiirces (of a stream) tributary, -behalter, m. feed tank, feed vessel, -rohr, n. supply tube or pipe, feed pipe. 

Zufiihrungs-draht, m. (Elec.) lead wire, -rohr, n. supply pipe, feed pipe, supply tube, -vorrichtung, /. feeding device, -walze, /. feed(ing) roller, feed roll. zufilUen, v.t. pour in, add fill up. 

Initially, 4.5 g (0.08 mol) pulverized potassium hydroxide was dissolved in 300 ml isopropanol in a 500 ml four-neck flask equipped with stirrer, intensive cooler, dropping funnel and feed pipe for the gas treatment with nitrogen. 

Feed Pipe for Liquids Heovier man I V Tank Contents... 

Feed Pipe for Gas or Liquids Lighter than Tank Contents... 

D = inlet diameter, feed pipe ft f = fanning friction factor dimensionless tj) = average value of tj)... 

LTHW systems are usually under a pressure of static head only, with an open expansion tank, in which case the design operating temperature should not exceed 83°C. Where MTHW systems operating above 110°C are pressurized by means of a head tank, an expansion vessel should be incorporated into the feed and expansion pipe. This vessel should be adequately sized to take the volume of expansion of the whole system so that boiling will not occur in the upper part of the feed pipe. On no account should an open vent be provided for this type of system. MTHW and HTHW systems require pressurization such that the saturation temperature at operating pressure at all points in the circuit exceeds the maximum system flow temperature required. A margin of 17 K (minimum)... 

A liquid hydrocarbon is fed at 295 K to a heat exchanger consisting of a 25 mm diameter tube heated on the outside by condensing steam at atmospheric pressure. The flow rate of the hydrocarbon is measured by means of a 19 mm orifice fitted to the 25 nnn feed pipe. The reading on a differential manometer containing the hydrocarbon-over-water is 450 mm and the coefficient of discharge of the meter is 0.6. 

The critical feed time t it depends on the location and number of feed pipes, stirrer type, and mixing intensity, and increases with increasing reactor volume. When a constant power-to-volume ratio is preserved, ta-u is proportional to and where D., is the stirrer diameter and Vr the reactor volume (Bourne and Hilber, 1990 Bourne and Thoma, 1991). The productivity of the reactor expressed as the amount of product formed per unit time becomes almost independent of reactor volume. The reason is that the reaction goes to completion in the zone nearby the stirrer tip. The size of this zone increases independently of the tank size it only depends on the velocity of the liquid being injected, the location of the nozzle, and the stirrer geometry and speed of rotation. Accordingly, for rapid reactions, the feed time will also be the reaction time. 

There are many parameters influencing the size-related performance of a reactor where feed mixing is important concentrations of reactants, feed flow rate, feed pipe velocity, geometry and size of both reactor and stirrer, and stirrer rotational speed. The following remarks should be kept in mind when composing an experimental program for engineering studies ... 

The feed should be introduced into zones of the highest turbulence, i.e. near the tip of the stirrer at the plane of the agitator or slightly above this plane the velocity of injected reactants should prevent backmixing of the reaction mixture into the feed pipe if the addition time will be too long, consider a multi-injection system with nozzles located at different angular positions. 

Recommended u/ut for selected geometries for turbulent feed pipe flow conditions... 

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