Monomers storage

Inerting Monomer Storage Tanks with Nitrogen. 26-77... 

The second context is the process reac tor. There is a potential for a runaway if the net heat gain of the system exceeds its total heat loss capabihty. A self-heating rate of 3°C/day is not unusual for a monomer storage tank in the early stages of a runaway. This corresponds to 0.00208°C/min, 10 percent of the ARC s detection limit. ARC data for the stored chemical would not show an exotherm until the self-heating rate was 0.02°C/min. Therefore, onset temperature information from ARC testing must be used with considerable caution. 

Examples of hazardous reaetions are given in Table 7.18. Table 7.19 gives basie preeautions in monomer storage Table 7.20 lists properties of eommon monomers. 

Examples of hazardous reactions are given in Table 6.17. Table 6.18 gives basic precautions in monomer storage Table 6.19 lists properties of common monomers. 

Precautions (Cont d) mineral oils, 159, 166 mixtures of chemicals, 170, 171 monomer storage, 249 oxides of nitrogen, 154 oxidizing agents, 235 oxygen, 260, 302 painting, 164, 167... 

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.)... 

Autopolymerization - Spontaneous polymerization of a monomer in the absence of an added initiator that usually occurs in monomer storage tanks and transport lines. Inhibitors can be added to prevent autopolymerization. For example, tetrafluoroethylene autopolymerization can be prevented by the addition of a-pinene or Ter-pene B. 

Since both acids have relatively high freezing points, 13-14°C, they must be prevented from freezing in cold conditions. If freezing occurs, thawing is a hazardous procedure since the distribution of inhibitor between solid and liquid is difficult to control, and runaway imcontrolled and potentially explosive polymerization of the liquid phase is always a threat. To avoid this potential hazard, monomer storage at temperatures in excess of their freezing points is recommended. 

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. 

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