Overflow pipe

Commercial chlorohydrin reactors are usually towers provided with a chlorine distributor plate at the bottom, an olefin distributor plate about half way up, a recirculation pipe to allow the chlorohydrin solution to be recycled from the top to the bottom of the tower, a water feed iato the recirculation pipe, an overflow pipe for the product solution, and an effluent gas takeoff (46). The propylene and chlorine feeds are controlled so that no free gaseous chlorine remains at the poiat where the propylene enters the tower. The gas lift effect of the feeds provides the energy for the recirculation of the reaction solution from the top of the tower. 

FIG. 6-30 Critical head for drain and overflow pipes. (Ftom Kalinske, Univ. Iowa Stud. Eng., Bull 26 [1939-1940].)... 

The make-up hall valve can he set a little high so that some water always goes down the overflow pipe. This is rather difficult to set initially, hut is reliable and cannot easily he tampered with. It will work at all times, and so will waste water if the plant is not running. 

Forms azeotropic mixts with butyl ale, acetic acid, heptane, toluene, nitroethane, perchioro-ethylene, w, etc. Prepn is by reacting propyl ale with coned nitric acid (d 1.41g/cc) dissolved in ethylacetate at 20°, followed by distn of the product. NPN can also be preod bv reacting a continuous stream of propyl ale below the surface of stirred mixed acid (20% nitric acid, 68% sulfuric acid and 12% w by wt) in a cooled (0—5°) open stainless steel vessel. Addnl mixed acid is also simultaneously introduced at about a third of the depth of the liq. An overflow pipe maintains a constant reactant level and the effluent prod is sepd, washed with 10% aq Na carbonate soln and dried by passage thru a Filtrol packed tower. Contact time of reactants can vary from 0.6 to 15 mins using about 50% isopropanol at 0° to yield 66.5% NPN (Ref 3b)... 

The water bath must not be allowed to exceed a given temperature. Usually it is controlled somewhat below this temperature by regulating the rate at which the cooling water enters. The level of the fluid and the material balance is determined by an overflow pipe on the tank. 

All the water from the steam condensate lines and the water baths (D-501) will be pumped into the hot-water storage tanks, unless they are full. In that case, a control valve will divert the water from the water baths into the wash-water tanks. An overflow pipe will send any excess water from these tanks to the waste treatment facilities. 

The problem of separating immiscible liquids in a centrifuge can best be understood by first considering the static gravity separation of immiscible liquids, as illustrated in Fig. 12-5, where the subscript 1 represents the lighter liquid and 2 represents the heavier liquid. In a continuous system, the static head of the heavier liquid in the overflow pipe must be balanced by the combined head of the lighter and heavier liquids in the separator, i.e.,... 

Pour the cooled water-glycol solution into the tester bath to a predetermined level 1/8 inch(3.2mm) below the top when the cup is in place. An overflow pipe is desirable for controlling the liquid level in the bath... 

As a measured amt, per unit time, of mixed acid is fed in from the bottom, a calcd amt of glycerin is fed in from the top at a level below that of the overflow pipe. The flow of materials into the nitrator is by means of automatically controlled air pressure. The propeller mixes the two liquids and glycerin is nitratec by acid to NG. 

In general, the outlet of an overflow standpipe is immersed into a bed in order to provide an adequate hydrostatic head or seal pressure in the standpipe, as shown in Fig. 8.19(a). The overflow pipe can be operated in either a moving bed or fluidized bed mode. Usually, solids occupy only a fraction of the pipe near the standpipe outlet. The solids flow rate in the pipe depends on the overflow rate from the fluidized bed. Consequently, no valve is needed at the pipe outlet. In the overflow standpipe system where solids transfer from one fluidized bed to the other, the pressure drops across the lower fluidized bed, the grid (distributor), the upper fluidized bed, and the height of solids in the standpipe. For a given standpipe system and given particles, the pressure distribution profile depends on the gas velocity. The difference in the pressure distribution reflects the difference in solids concentration,... 

The raw ethylsilicate formed is continually fed through an overflow pipe into one of distillation tanks 8. Usually there are several tanks while some are used for distillation, others are filled with etherification products. After the tanks are filled, the temperature is raised to 78-80 °C and during approximately 3 hours the alcohol vapours condensed in cooler 9 are directed through phase separator 10 back into the tank i.e. the tank operates in the self-serving mode. This makes the etherification more complete. After that the temperature is gradually (at the speed of 5-10 grad/h) raised to 140 °C. The excess pressure in distillation tanks should not exceed 0.02 MPa. 

The final dehydration of potassium acetate is carried out in reactor 6 (until the total elimination of moisture). For that purpose the washed and dried reactor is filled with toluene from batch box 2 then potassium acetate is sent at agitation through an overflow pipe. The potassium acetate has already been dried in vacuum drafts and weighed. The jacket of the reactor is filled with vapour (0.3 MPa), and cooler 5, with water. The dehydration is carried out by distilling the azeotropic mixture of toluene and water at 100-115 °C. The distilled mixture is sent into cooler 5 to condense. The condensate is collected in receptacle 7. The speed of the distillation of the azeotropic mixture is regulated by changing the vapour supply in the reactor jacket. After 200-250 1 of the azeotropic mixture have been distilled, toluene is returned from collector 7 into the reactor. The distilled water is collected in the lower part of collector 7, and the separated toluene is sent back into the reactor. 

These concepts may be transferred to gas phase reactions by imagining that the pump corresponds to the activation of molecules by collision, that the overflow pipe corresponds to the deactivation of activated molecules by collision, and that the discharge... 

The gas and electrolyte mixture flows through two openings in the front plate and passes to separator where the gas is separated from the electrolyte. The gases are then washed with distilled water and led to the gas holders. The hot electrolyte flows to the coolers and after cooling passes to the lower channels of the electrolyzer and then to the individual chambers. The feeding water is brought by a funnel to the upper part of the separator where it is first used to wash the gas. The separating columns connected by an overflow pipe also act as pressure controllers. 

Li, H. Hydrodynamics of moving-bed conical overflow pipe, M.S. Thesis, Institute of Chemical Metallurgy, Beijing, China (1981). 

In the present formulation the size of the fluidized bed is kept constant by the presence of an overflow pipe. Figure 1, and consequently Aq and Hq are constant. The fraction of dolomite in... 

The mathematical model for char combustion described in the previous two sections is applicable to a bed of constant volume, i.e., to a fluidized bed of fixed height, Hq, and having a constant cross-sectional area, Aq. The constant bed height is maintained by an overflow pipe. For this type of combustor operating for a given feed rate of char and limestone particles of known size distributions, the model presented here can predict the following ... 

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