Inflow vessel

Figure 7.4 Microcomputer programming of a hatch cooling crystallizer. A, crystallization vessel, B, control heater, C, control cooler. surrounding the draft-tube), D, contact thermometer, E, discharge plug and conical baffle), F, recorder, G, relay, H, temperature programmer, I, cooling water pump, J, cooling water reservoir, K, water inflow L, water outflow after Jones and Mullin, 1974)...

As long as pressure, level, and temperature control devices are operating correctly, the safety system is not needed. If the control system malfunctions, then pressure, level, and temperature safety switches sense the problem so the inflow can be shut off. If the control system fails and the safety switches don t work, then relief valves are needed to protect against overpressure. Relief valves are essential because safety switches do fail or can be bypassed for operational reasons. Also, even when safety switches operate correctly, shutdown valves take time to operate, and there may be pressure stored in upstream vessels that can overpressure downstream equipment while the system is shutting down. Relief valves are an essential element in the facility safety system. 

One source of an oil spill could be the filling of a vessel that has an outlet to atmosphere until it overflows. Whenever inflow exceeds outflow, the tank can eventually overflow. Another source is a rupture or sudden inability of a piece of equipment to contain pressure. Events leading to rupture are listed in Figure 14-2. Note that some of these events can be anticipated by sensing changes in process conditions that lead to the rupture. Other events cannot be anticipated from process conditions. 

Inflow exceeding outflow is sensed by a high-level sensor (LSH). Back-up protection is furnished by the PSH (to keep the relief valve from operating) or an LSH in a downstream vent scrubber if the vessel gas outlet goes to atmosphere. That is, a vent scrubber must be installed downstream of any vessel that discharges directly to atmosphere. 

Zufluss, m. flow, flux, afflux, influx, inflow (Tech.) feed reaoiirces (of a stream) tributary, -behalter, m. feed tank, feed vessel, -rohr, n. supply tube or pipe, feed pipe. 

The portal vein is the primary vessel leading into the liver it receives deoxygenated venous blood flow from the small intestine, stomach, pancreas, and spleen (Fig. 19-1). The inflow from these organ systems accounts for approximately 75% of... 

Equation (II-9) simply says that the rate of change of total property P(t) equals the total property inflow minus the total property outflow plus the nucleation term (p(t,t) denotes property at birth, i.e. t=x) plus the growth terms. Remember that nxoT(t,t) denotes, in the general case, particles nucleated in the vessel which grew to the property p(t,x) and particles nucleated somewhere else, which entered the reactor with the inlet streams and subsequently grew to p(t,x). 

With these observations in mind, the simplest practical measure to reduce electrostatic discharge risks associated with vessel loading is to reduce the rate at which the dry solids are added to the vessel. This approach works because the slower rate of flow provides an opportunity for accumulating charge to relax away by various mechanisms before hazardous conditions become established. Often, the same type of flow limitation is effective in reducing the likelihood of ESD during vessel unloading. In many cases, the maximum safe rate of inflow (or outflow) has to be determined by empirical means. 

Outflow Rate Exceeds Inflow Rate If material is being withdrawn from a tank or vessel faster than the incoming rate to compensate for the removal suction a vacuum will occur. If the vessel or tank is not strong enough to withstand the negative pressure levels it will collapse in on itself... 

The CSTR model, on the other hand, is based on a stirred vessel with continuous inflow and outflow (see Fig. 1.2). The principal assumption made when deriving the model is that the vessel is stirred vigorously enough to eliminate all concentration gradients inside the reactor (i.e., the assumption of well stirred). The outlet concentrations will then be identical to the reactor concentrations, and a simple mole balance yields the CSTR model equation ... 

In the steady-state approach to determining the rate law, solutions containing reactants are pumped separately at a constant flow rate into a vessel ( reactor ), the contents of which are vigorously stirred. After a while, produets and some reactants will flow from the reactor at the same total rate of inflow and a steady state will be attained, in which the reaction will take place in the reactor with a constant concentration of reactants, and therefore a constant rate. This is the basis of the stirred-flow reactor, or capacity-flow method. Although the method has been little used, it has the advantage of a simplified kinetic treatment even for complex systems. 

An autoclave (7) is supplied with an aqueous solution that contains 600 g of ammonium nitrate and 40 g of ammonia per litre. Calcium cyanamide in the ratio of 500 g CaCN2 to every litre of solution is then added from container (2) after being weighed at (3). The autoclave is closed, carbon dioxide is introduced, while the contents are cooled with water so that the temperature does not exceed 100°C. When no more carbon dioxide is absorbed, the supply is stopped, and so is the inflow of cooling water. The reaction mixture is now steam heated to 160°C. Afterwards a communicating valve joining the autoclave (7) with a second autoclave (75) is opened. The other vessel (75) is filled with ammonium nitrate solution prepared for the next charge. In this way the major part of the ammonia passes from autoclave (7) over to autoclave (75). After the reaction is finished the mixture is raised from the auto-... 

Derivative control is sensitive to noise that is made up of random higher frequency perturbations, such as splashing and turbulence generated by inflow in the case of liquid level control in a vessel, so that it is not satisfactory in such situations. The variety of composition controllers arises because of the variety of composition analyzers or detectors. 

Now suppose the feed contains a reactant A that irreversibly goes to a product B. Let cin be the concentration of A in the feed and c its concentration both in the tank and the effluent (the assumption of good mixing ensures the last two will be the same), and let the reaction be of the first order so that it proceeds at a rate kc, where k is a constant. The concentrations are in moles/ unit volume and the rate is in moles/(unit volume unit time). A is not conserved as mass was, for the whole point of the reactor is to get A to become B, but we must still be able to account for it. Coming in with the feed stream there are qmcm moles/unit time leaving, unreacted, in the product stream there are qc moles/unit time. When the volume is V, the rate of disappearance of A by reaction is Vkc and the number of moles of A in the vessel is Vc. The rate of change of this last must be the difference between the inflow and the total rate of disappearance of A by outflow and reaction. Thus... 

The composition of the reaction mixture in the vessel will be maintained at a constant low conversion by continuous withdrawal of the product stream and a steady inflow of fresh o-xylene. Under these conditions the reaction rate is approximately independent of the o-xylene concentration and is pseudo first-order with respect to the dissolved oxygen concentration C0. 

Tests in which solutions in test vessels are renewed continuously by the constant inflow of a fresh solution, or by a frequent intermittent inflow. Synonymous term is "dynamic". Volume 1(10). 

Titration. An automatic titrating device with an anticipation unit is available for titrations having an electrometric endpoint. The flow of titrant into the reaction vessel proceeds continuously until the amplified potential produced by the sensing electrodes in the solution reaches the first preset value in the anticipation unit. This actuates the valve controlling the inflow, causing it to reduce the continuous flow to one which is dropwise. The titrant is added dropwise to prevent overshooting until... 

The number of bubbles formed is equal to the volume of air in the vessel divided by the average volume of a single bubble. The volume of air in the vessel is equal to the rate of inflow of air ga times its detention time t . The detention time, in turn, is equal to the depth of submergence h (see Figure 6.7g) divided by the average total rise velocity of the bubbles. If Vj is the average rise velocity of the bubbles... 

Let the average volume of a single bubble at the surface of the vessel be Vto and let the influent absolute pressure of the air in gi be P . In order to accurately compute the number of bubbles, g should be corrected so its value would correspond to Vbo at the surface when the pressure becomes the atmospheric pressure Since pressure and volume are in inverse ratio to each other, the rate of inflow of air corrected to its value at the surface of the vessel is then (PilPJQi- Thus, the number of bubbles n formed from a rate of inflow of air g is... 

For the vessel in Problem 6.1, at what detention time should it be operated for it to function effectively At what rate of inflow should it be operated For the vessel in Problem 6.2, at what detention time should it be operated for it to function effectively At what rate of inflow should it be operated ... 

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