Partially closed reactor

Less Less Flow Excess ammonia in reactor. Release to work area, with amount released related to quantitative reduction in supply. Team member to calculate toxicity vs. flow reduction. 1. Valve A partially closed. 2. Partial plug or leak in pipe. Automatic closure of valve B on reduced flow from phosphoric acid supply. Set point determined by toxicity vs. flow calculation. 

Volume variations with conversion are large for constant-pressure gas-phase reactions with change in mole number. Here, as a rule, operation at constant volume poses no difficulties. Liquid-phase reactions may also entail volume contraction or expansion. However, these are not related to changes in mole number and can be predicted only if information on partial molar volumes is at hand. Because liquids are essentially incompressible, even at elevated temperature, it is unsafe to conduct liquid-phase reactions without a gas cap in a closed reactor. Some variation of liquid-phase volume with conversion therefore is apt to occur. Fortunately, the variation at constant temperature is usually so small that it can be neglected in the evaluation or accounted for by a minor correction. 

In many cases the reactor exit valve is opened and partially closed periodically to impose a pressure and flow pulse that helps keep the tube from plugging with polymer. Substantial pressure fluctuations occur in the reactor with this mode of operation. 

The feed to the partial oxidation reactor is a mixture of hydrocarbons, steam, and air or oxygen (or mixtures thereof). The reactor is in general adiabatic or auto-thermal and the exit gas is in many cases close to equilibrium at the exit temperature and pressure at chemical equilibrium. The exit composition can be determined based on the inlet temperature and composition, and on the assumption that all oxygen has reacted. In Fig. 9, product gas compositions are given at various conditions with oxygen as oxidant, assuming that chemical equilibrium is obtained. 

Isotopic exchange is generally carried out in a recycle, closed reactor coupled to a mass spectrometer, as represented on the Fig. 2. The recycle pump is necessary to avoid any diffusion effect in the gas phase, limiting the changes of partial pressme measured by the mass spectrometer. T T)ical curves of exchange are represented in Fig. 3 which shows the changes, with time, of the partial pressures of 02, and 2 dur-... 

If the reactor is closed or partially closed with respect to one or more components, the stoichiometrically least abundant component will be chosen. We can again apply definition [1.14] and equation [1.15] in order to calculate the quantities of different species lost or produced when the system is closed to the fractional extent a. 

Suppose the following data on the iodination of ethane have been obtained at 603 K using a recirculating gas-phase reactor that closely approximates a CSTR. The indicated concentrations are partial pressures in atmospheres and the mean residence time is in seconds. 

With A = 0.06 M and the rate constants of Ref. 14b, these equations admit a unique homogeneous steady-state solution (HSS). It is well known that the irreversible Oregonator 14 and its reversible counterpartl4b exhibit homogeneous limit cycle oscillations for realistic values of rate constants and buffered concentrations. My purpose here is to explore several other features of the reversible model (F) which explain a variety of observed behaviors in closed and open stirred reactors. To that end I begin with the stability properties of the unique HSS, as displayed in the partial phase diagram of Fig. 1. 

However, there are many other options to combine electricity with chemistry. One that has been studied intensively for a variety of different applications is plasma chemistry (see Fridman, 2008 for a recent overview). A plasma is a partially ionized gas, in which a certain percentage of the electrons is free instead of bound to an atom or molecule. Because the charge neutrality of a plasma requires that plasma currents close on themselves in electric circuits, a plasma reactor shows resemblance to an electrochemical cell, although due to the much lower ionization degree and conductivity, a plasma discharge will typically be operated in the range of hundreds of volts, compared to a few volts in the case of an aqueous electrochemical cell. 

The crew decided to open the drain valves on the 3-inch (7.6 cm) suction lines from the reabsorber and stripper bottoms pumps. About an hour later, when the level in the reabsorber dropped to about 75 percent, the crew closed the suction drains valves. They started the feed stripper bottoms pump, creating an even greater partial vacuum as the water stream was routed to the reactor. About 10 minutes later at 1 15 A.M., an employee observed the column slowly start tilting, and then toppling from the vertical position. By the time the stripper dropped to a 45-degree angle, the eyewitness reported it was falling very fast. 

Selective hydrocarbon oxidation reactions are characterised by both high activation energies and heats of reaction. If the desired partial oxidation products are to be safeguarded and the catalyst integrity ensured it is essential that close temperature control be maintained. In spite of the obvious attractions of the fluid bed for this purpose, mechanical considerations normally dictate that a multi-tubular fixed-bed reactor, comprising small diameter tubes between 2-4 cms. diameter, be used. 

Initially a few particularly sensitive tubes of the bundle will run away, i.e., the reaction changes, for example, from a selective partial oxidation to a total combustion, and the temperature rises rapidly. In a multitubular reactor with thousands of tubes every tube cannot be equipped with temperature profile measurements it is therefore likely that this runaway will remain undetected, especially if it involves only a few tubes. Although temperatures above 1000 °C can often be reached in the catalyst during such runaways, there is no safety risk, provided the tube is surrounded by a liquid heat-transfer medium. Because of the good heat transfer to the fluid the tube temperature remains close to that of the heat-transfer medium, and melting of the tube does not occur. 

The process is carried out by injecting preheated hydrocarbon, preheated oxygen, and steam through a specially designed burner into a closed combustion vessel, where partial oxidation occurs in the range of 2350°F to 2550°F (1290°C -1400°C). "Partial Oxidation" describes the net effect of a number of component reactions that occur with hydrocarbons within a reactor supplied with less than stoichiometric oxygen for complete combustion. The overall reaction is represented by ... 

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