Reactor venting

The basic process usually consists of a large reaction vessel in which air is bubbled through pressuri2ed hot Hquid toluene containing a soluble cobalt catalyst as well as the reaction products, a system to recover hydrocarbons from the reactor vent gases, and a purification system for the ben2oic acid product. 

Gas Phase Olefin Polymerization Process with Recovery of Monomers from Reactor Vent Gas by Absorption, U.S. Patent 5,521.264, May 28, 1996. 

Table 5. Initial Data Sheet for Reactor Venting Episode...

The RSST can rapidly and safely determine the potential for runaway reactions. It also measures the temperature rates and, in the case of gassy reactions, pressure increases to allow reliable determinations of the energy and gas release rates. This information is combined with analytical tools to evaluate reactor vent size requirements. This is extremely useful when screening a large number of different chemicals and processes. 

A runaway reaction occurs when an exothermic system becomes uncontrollable. The reaction leads to a rapid increase in the temperature and pressure, which if not relieved can rupture the containing vessel. A runaway reaction occurs because the rate of reaction, and therefore the rate of heat generation, increases exponentially with temperature. In contrast, the rate of cooling increases only linearly with temperature. Once the rate of heat generation exceeds available cooling, the rate of temperature increase becomes progressively faster. Runaway reactions nearly always result in two-phase flow reliefs. In reactor venting, reactions essentially fall into three classifications ... 

Lahiere, R. J., et al. Membrane Vapor Separation Recovery of Vinyl Chloride Monrtmer From PVC Reactor Vents. Ind. Eng. Chem. Res. 32 (1993), pp. 2236-2241. 

Reactor vent cooler is RE-1 Reactor vent condenser is RE-2 Reactor recycle pump is RP-1 Level control valv e is Rl C-1 Relief valve is RSV-1... 

JACOBS AND KRUPA Safe Reactor Vent Systems... 

This chart was prepared to be a guide to insurance inspectors and not a design technique. Experience indicates, however, it is often used by designers to estimate a reactor vent size. 

Use of thermal stability tests (DTA s) to determine the heat sensitivity of a given process mixture is desirable. Recent advances in analytical methods permit good calorimetric determination of heat of reaction. Heat of reaction data are critical for exothermic reactor vent sizing. Heat impact from fire is usually small in comparison, but should not be neglected. 

The reactor venting problem consists of several key parts each of which must be understood and carefully handled 1) the heat input either from exothermic reactions or other miscellaneous heat sources,... 

Water is used in the chrome pigment industry mainly to cool most of the equipment such as heat exchangers, generate steam in the boilers, make slurry of raw materials, scrub the reactor vent... 

Develop sketches of reactor vent systems for the following four cases ... 

By using open or vented cells, data are obtained to determine if the full-scale reactor vent flow will be single or two-phase, and if a tempered or nontempered reaction occurs [192]. A tempered reaction is one that can be controlled through the latent enthalpy of evaporation. 

In both processes, the vents from the reactor must be carefully designed. Actually, because of the high temperature configuration, the reactor vent in this process is from the overhead of the purification column. 

The reactor vents are due to the non-condensables in both the chlorine and ethylene feeds. In the case of chlorine, the non-condensables are largely the oxygen and inerts (carbon dioxide and nitrogen) as produced from the electrolysers. In the case of ethylene, the non-condensables are largely ethane, which is unreactive. The vent is also saturated with EDC vapour at the vent condenser temperature. 

If a Safety Interlock System exists, describe what is to happen when shutdown is triggered for example, reactor feed MV closes, reactor vent MV opens, etc.)... 

R.W. Baker, K.A. Lokhandwala, M.L. Jacobs and D.E. Gottschlich, Recover Feedstock and Product from Reactor Vent Streams, Chem. Eng. Prog. 96, 51 (2000). 

The simpler and most reliable approach to the use of the DIERS methodology is the use of FAUSKY s reactive system screening tool (RSST). It is an experimental autoclave which simulates actual situations that may arise in industrial systems. The RSST runs as a differential scanning calorimeter that may operate as a vent-sizing unit where data can readily be obtained and can be applied to full-scale process conditions. The unit is computerized and records plots of pressure vs. temperature, temperature vs. time, pressure vs. time, and the rates of temperature rise and pressure rise vs. the inverse of temperature. From these data it determines the potential for runaway reactions and measures the rates of temperature and pressure increases to allow reliable determinations of the energy and gas release rates. This information can be combined with simplified analytical tools to assess reactor vent size requirements. The cost of setting up a unit of this kind is close to 15,000. 

Finally, safety is always a prime consideration in the selection of an appropriate polymerization reactor. Venting to the atmosphere in a safe and environmentally sound manner should always be a part of polymerization reactor design. Some additional useful information and insight into the... 

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