Reactor control configuration

Sherwin-Williams has developed such a polymer process control system. The methodology used to accommodate the contrasting requirements has two key elements. First, the software is based on a simple architecture that places the definition of changing reactor hardware elements and characteristics in easily modified configuration files (5). Second, the language uses a small number of basic commands to describe formulations and reactor control. Complex operations are described by reference to commands tables (macros) built using several basic commands or other macros. 

Figure 4.58 Experimental configuration employed for operation of the basic system in a fed-batch reactor. (.) control lines (----) ...

Note that in the following analyses, we will drop the prime symbol. It should still be clear that deviation variables are being used. Then this linear representation can easily be separated into the standard state-space form of Eq. (72) for any particular control configuration. Numerical simulation of the behavior of the reactor using this linearized model is significantly simpler than using the full nonlinear model. The first step in the solution is to solve the full, nonlinear model for the steady-state profiles. The steady-state profiles are then used to calculate the matrices A and W. Due to the linearity of the system, an analytical solution of the differential equations is possible ... 

A variety of methods and configurations can be used for heat transfer. These are described in Section 1.5. Since heat transfer is one of the key issues in reactor control, the CSTR is usually more easily controlled than a tubular reactor. It is physically difficult to adjust the heat removal down the length of a tubular reactor. 

A potential choice of manipulated inputs to address the control objectives in the slow time scale is [ 3 Mrsp]t, i.e., the product flow rate from the column reboiler, and the setpoint for the reactor holdup used in the proportional feedback controller of Equation (3.35). This cascade control configuration is physically meaningful as well intuitively, the regulation of the product purity 23 is associated with the conversion and selectivity achieved by the reactor, which in turn are affected by the reactor residence time. 

Figure 5.26 Dynamic response of HDA reactor inlet temperature to -8°C setpoint change for three different process and control configurations.

Cascade control is one solution to this problem (see Fig. 8-35). Here the jacket temperature is measured, and an error signal is sent from this point to the coolant control valve this reduces coolant flow, maintaining the heat transfer rate to the reactor at a constant level and rejecting the disturbance. The cascade control configuration will also adjust the setting of the coolant control valve when an error occurs in reactor temperature. The cascade control scheme shown in Fig. 8-35 contains two controllers. The primary controller is the reactor temperature coolant temperature controller. It measures the reactor temperature, compares it to the set point, and computes an output, which is the set point for the coolant flow rate controller. This secondary controller compares the set point to the coolant temperature measurement and adjusts the valve. The principal advantage of cascade control is that the secondary measurement (jacket temperature) is located closer to a potential disturbance in order to improve the closed-loop response. 

Consider the following problem. In the petrochemical industry, many reactions are oxidations and hydrogenations that are very exothermic. Thus, to control the temperature in an industrial reactor the configuration is typically a bundle of tubes (between 1 and 2 inches in diameter and thousands in number) that are bathed in a heat exchange fluid. The high heat exchange surface area per reactor volume allows the large heat release to be effectively removed. Suppose that a new catalyst is to be prepared for ultimate use in a reactor of this type to conduct a gas-phase reaction. How are appropriate reaction rate data obtained for this situation ... 

FIGURE 3.2 Block diagrams of two automotive emission control configurations, (a) Thermal reactor plus EGR. (b) Catalytic exhaust purification. 

Periodic flow reversal inducing forced unsteady-state conditions [339]. The flow to the reactor is continuously reversed before the steady state is attained. A dual hot-spot temperature profile, characterized by a considerably lower temperature than in the single hot spot that would develop in the traditional flow configuration, forms in exothermic oxidation reactions. An increase in selectivity and better reactor control (lower risk of runaway) is possible over fixed-bed reactor operations, but compared... 

The operation of the microreactors is monitored through the Microreactors tab on the main control panel. This panel displays the position of the SOVs, the feed gas flow rate to each microreactor channel, and whether or not the microreactor heaters are enabled. Additional information on the operation of each of the microreactor channels can be obtained by clicking on the Open Panel button next to the reactor name. In addition, pressing the Configure Reactor Control button opens a sub-panel where the operator can configure the temperature control mode for each of the microreactor channels to be either manual or automatic PID control. Some salient aspects of the reactor control panel are given below since this is the key system component. 

What is split-range control In Example 20.6 we have a situation with split-range control. To control the pressure in the reactor we could use valve V, or valve V2 with simple control configurations or both valves in a split-range control configuration. Which of the three is better Why ... 

Figure 25.3 Alternative control configurations needed for a feed-effluent heat exchanger system around a reactor.

Figure 21.27 Control configurations for the alternative reactor configurations (a) single CSTR (b) two CSTRs in series.

The suitability of the LEADIR-PS concept to reactors of larger output was assessed, and a reactor ou ut limit of about 1000 MWjh established. Reactors with outputs above about 600 MWth require an annular core configuration (similar to MHTGR). The central reflector blocks provide additional heat capacity to accommodate postulated accident conditions, and locations for the control and shutdown rods necessary for reactor control and shutdown. 

The reactor configuration, shown in Fig. t, consists of a large outer cylindrical reflector shell of beryllium, into which the fuel (in the form of a cylindrical shell Of uranium carbide fuel elements) and an inner beryllium reflector are assembled by a ram which lifts them into the reflector. Originallyi the reactor control and safety systems consisted of rotary drums with a 120-deg boron sector running the full length of the core, which resided permanently in the outer beryllium reflector and were spring loaded for fail-safe control. ... 

Introduction of membranes may, in some cases, lead to more flexibility in the design and study of chemical oscillators. The continuous-stirred tank reactor (CSTR) configuration, which is often used to study chemical oscillators because it maintains reaction and product concentrations away from equilibrium [1, 2], controls the transport of reactants, intermediates, and products by fluid flow, and does not discriminate among species. Membrane selectivity between chemical species can provide a basis for selection of dynamical behaviors that are unavailable with a CSTR. 

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