Installing Basic Controllers

Let us go through the details of iustalliug a level controller on the base of the column. There are several ways to select control elements and drop them on the Process Flowsheet Window. 

To install a controller, click the PIDIncr icon, move the cursor to the flowsheet window and drop the controller at the desired location (see Fig. 7.10). The controller can be 

The action of the controller should be Direct because if the level increases, the signal to the valve should increase (PVt. OP]) to remove more bottoms. In some columns, base level is controlled by manipulating a valve in the feed to the column. In that control structure, the base level controller action should be Reverse. 

As we want proportional-only control, the controller gain is set equal to 2 and the integral time is set at a very large number (9999 min shown in Fig. 7.15b). 

The faceplate is located at some convenient spot in the window where we can keep an eye on what is going on with this level loop. Remember there will eventually be five controller faceplates. 

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Remote control units. These units are used to control unit processes. Basic control functions such as the PID algorithm are implemented here. Depending on other hardware components used, data acquisition capability may be required to perform digital control. They may be configured to supply process set points to single-loop controllers. Radio telemetiy may be installed to communicate with MUX units located at great distances. 

A fundamental element of fire prevention is the control of ignition sources. The process should be designed, installed, and operated to minimize or prevent the release or spill of flammable gases, liquids, or combustible dusts, as well as eliminate or control ignition sources. The basic controls for these unwanted ignition sources are ... 

The 1990 CAA Amendments set new NESHAPS for 188 hazardous air pollutants. In addition, the Act required EPA to develop standards based on maximum achievable control technology, or MACT. Thus, the NESHAPS are commonly called the MACT standards. The law calls for EPA to review the technology-based MACT standards for each source category every eight years to determine whether any residual risk exists for the source category, and if necessary, revise the standards. Basically, the CAA requires major stationary sources to install pollution control equipment and to maintain that equipment in good working order. 

Burton, T, D. Sharpe, D. Jenkins, and E. Bossanyi. 2001. Wind Energy Handbook. New York John Wiley Sons. Although beginning with a chapter on wind as a basic resource, the primary focus of this book is on wind turbine aerodynamics, design, installation, and control. 

In this chapter, we have tried to indicate a systematic procedure for the design of the basic control scheme. In addition, some attention was paid to protection and optimal control. This did not lead to a cookbook recipe, which produces ready to install control schemes. On the contrary, the final selection of the process control system is still a matter of different aspects, affected by local circumstances. In addition, close cooperation between people from different disciplines is necessary. It is probably a good idea to highlight a few of these circumstances, although this hst will not be complete. 

Prior to the advent of the basic control systems without feedback, the only way to control the quantities deposited was to set the delivery pressures and eliminate the effects of pump pulsing to give a steady flow of material to the applicator. This gives a degree of control and has been used successfully in many installations but it is a compromise between delivery rates and applicator speed. 

Control philosophies for clarifiers are based on the idea that the overflow is the most important performance criterion. Underflow density or suspended sohds content is a consideration, as is optimal use of flocculation and pH control reagents. Automated controls are of three basic types (I) control loops that optimize coagulant, flocculant, and pH control reagent additions (2) those that regulate underflow removal and (3) rake drive controls. Equahzation of the feed is provided in some installations, but the clarifier feed is usually not a controlled variable with respect to the clarifier operation. 

Our present discussions relate only to the laboratory testing of safety-related secondary systems, as are employed in critical areas such as areas of emergency power supply and reactor power control supply etc. of a nuclear power plant (NPP) according to IEEE 344 and lEC 60980. There are other codes also but IEEE 344 is referred to more commonly. Basically, all such codes are meant for an NPP but they can be applied to other critical applications or installations that are prone to earthquakes. 

Different microstructural regions in a material which has an almost uniform composition can also lead to the formation of corrosion cells (e.g., in the vicinity of welds). Basically, corrosion cells can be successfully overcome by cathodic protection. However, in practice, care has to be taken to avoid electrical shielding by large current-consuming cathode surfaces by keeping the area as small as possible. In general, with mixed installations of different metals, it must be remembered that the protection potentials and the protection range depend on the materials (Section 2.4). This can restrict the use of cathodic protection or make special potential control necessary. 

Most EDS systems are controlled by minicomputers or microcomputers and are easy to use for the basic operations of spectrum collection and peak identification, even for the computer illiterate. However, the use of advanced analysis techniques, including deconvolution of overlapped peaks, background subtraction, and quantitative analysis will require some extra training, which usually is provided at installation or available at special schools. 

This chapter introduces the basic items of design and specification for the principal systems and components of an electrical industrial installation. Electrical supply systems are discussed with regard to interface with the supply authorities and the characteristics. Salient features of switchgear, transformers, protection systems, power factor correction, motor control equipment and standby supplies are identified and discussed together with reference to the relevant codes of practice and standards. The equipment and systems described are appropriate to industrial plant installations operating at typically 11 kV with supply capacities of around 20MVA. 

A main control and annunciator panel should be installed when the fire alarm system requires more than a single alarm zone. The panel should be installed in the control room or other continuously staffed location. Separate detection zones should be provided for each distinct fire area and identified by a permanent label. A detailed map of the area should also be provided at the annunciator that identifies which zone relates to which annunciator lamp. Systems with more than ten separate zones should be provided with an electric or electroniczone "mimic" panel showingthe location of all alarms on the graphic display of the platform. Basic arrangements of equipment and system design should be in accordance with NFPA 72. A locked main fire panel and control cabinet should be provided. 

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