Monomer storage vessels

This system prevents the reactor contents from siphoning back into the monomer storage vessel, even if the block valves leak. This prevents an unexpected chemical reaction in the storage tank. 

The behavior shown in Figure 5.5 is typical of systems that have two stable steady states. The realized steady state depends on the initial conditions. For this example with a() = 1, the upper steady state is reached if T0 is greater than about 398 K, and the lower steady state is reached if T0 is less than about 398 K. At the lower steady state, the CSTR acts as a styrene monomer storage vessel with Tout Tin and there is no significant reaction. The upper steady state is a runaway where the reaction goes to near completion with Tout Tin + ATadiabatic- (In actuality, the styrene polymerization is reversible at very high temperatures, with a ceiling temperature of about 625 K.)... 

Example 9-7 Design of a New Jet Mixer. A monomer storage vessel is 10 m in diameter with a straight-side height of 8 m. Thirty minutes after delivery of a fresh shipment of monomer, the vessel contents are sampled and analyzed. A jet mixer will be installed in the vessel to blend the new shipment with the existing fluid. The monomer has a density of 850 kg/m and viscosity of 1.2 mPa s. Design the jet mixer. 

Because chloroprene is a flammable, polymerisable Hquid with significant toxicity, it must be handled with care even in the laboratory. In commercial quantities, precaution must be taken against temperature rise from dimerisation and polymerisation and possible accumulation of explosive vapor concentrations. Storage vessels for inhibited monomer require adequate cooling capacity and vessel pressure rehef faciUties, with care that the latter are free of polymer deposits. When transportation of monomer is required, it is loaded cold (< — 10° C) into sealed, insulated vessels with careful monitoring of loading and arrival temperature and duration of transit. 

Figure 2. Schematic representation of the reactor system computer-controlled pumps (PI, P2) pump controllers (fc) reactor (CSTR) reception vessel valves (S1-S4) monomer and initiator storage vessels (Tl, T2). (a) Digital input from GPC injection valve (b) analogue output from GPC (c, d) digital outputs to recorder chart drive and event marker (e, f) analogue outputs for pump set-point adjustment (g,h) reactor feeds (i) reactor output (j-m) digital outputs to reception system valves (n) manual sampling of products by GPC,...

Materials. Tetrahydrofuran. The monomer was refluxed over potassium until a small amount of distillate easily developed the green sodium naphthalene complex. It was then distilled from potassium under nitrogen, and a center cut was stored in vacuo in the presence of a sodium naphthalene complex. When needed, the monomer was distilled under high vacuum from the storage vessel into breakseals and weighed. 

Figure 10.3 Healing monomer stored in (a) discreet storage vessels such as hollow fibers or (b) interconnected storage vessels, such as microvascular networks. Reprinted with permission from Refs. [24, 83].

Because process heating is expensive, lagging is invariably applied to heated process vessels to minimise heat loss, particularly during long-term hot storage. Such adiabatic or near-adiabatic systems are potentially hazardous if materials of limited thermal stability, or which possess self-heating capability, are used in them. Insufficiently stabilised bulk-stored monomers come into the latter category. 

Storage of monomers and solvents also requires special precautions. The vessels must be specially constructed and be closed with a self-sealing cap through which the distilled contents can be transferred with a pipette or hypodermic syringe under inert gas. The contents should also not come in contact with tap grease. 

If a monomer or an oligomer is delivered in heated tanks, it is immediately pumped into a heated vessel for storage in controlled conditions. Other products, which are liquid during transportation, are treated in the same way. Components with melting points higher than room... 

An enhanced robustness can benefit a process in a number of ways. Since the polymer-stabilized miniemulsions are less susceptible to disturbances, their polymerization is less hkely to be affected by operator error, fluctuations in feed stream concentrations and residual contaminants in the reaction vessel. Many monomers contain species that can act as inhibitors or retarders as a result of monomer production, storage, or processing. These contaminants also cause batch-to-batch variability in particle number in macroemulsions. Therefore, miniemulsion polymerization may be an alternative to seeded polymerization as a way of maintaining robust control of particle number. 

Commercial monomers are sold with added inhibitor to prevent their premature polymerization during storage and transportation. These inhibitors are either removed or extra initiator is added to reactor vessels to reactively consume the inhibitors. Retarders and inhibitors differ only in the frequency with which propagating radicals react with them rather than monomer and also in the ability of these resulting macroradicals to reinitiate. Fig. 1 schematically illustrates the difference in polymerization kinetics in the presence of retarders and inhibitors. 

The monomer, catalyst, and water are metered into the reaction vessel, provided with a stirrer. The. incoming mixture displaces an equal amount through the outlet which contains the polymer in suspension. The polyacrylonitrile is separated from the liquor by the rotary suction filter and conveyed thence through a drier to a pulverizer and finally collected in a storage bin. 

Vinyl chloride may be stored in ordinary steel cylinders, tank cars, and storage tanks. The monomer must be stored under pressure to maintain a liquid state. Vessels are loaded or unloaded by use of inert gas pressure or most commonly by using pumps. 

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