Control installation factors

Most baghouse systems are provided as complete assemblies by the vendor. While the unit may require some field assembly, the vendor generally provides the structural supports, which in most cases are adequate. The only controllable installation factors that may affect performance are the foundation and connections to pneumatic conveyors and other supply systems. 

Figure 14.2 Instrumentation and control installation factors as a function of scale and complexity.

M = total number of pieces of equipment fp = installation factor for piping fer = installation factor for equipment erection fei = installation factor for electrical work fi = installation factor for instrumentation and process control fc = installation factor for civil engineering work fs = installation factor for structures and buildings fl = installation factor for lagging, insulation, or paint. 

Planned maintenance or regular replacement of plant equipment to avoid failure by corrosion is an essential adjunct to design and constitutes the third phase of control. The factors contributing to a policy of planned maintenance philosophy are (i) predictable and reasonable rate of corrosion for material (ii) discounted cash flow advantage over life of plant in using a cheaper less-resistant material (iii) factors other than corrosion dictating regular maintenance (iv) no feasible alternative to corrodible material (v) installed spare preferred policy for reliability of plant. 

Cyliiuiriciil vessels me very frequently used in the petrochemical industry. They are easy to fabricate and install and economical to maintain. The required thickness is generally controlled by internal pressure, although in some instances applied loads and external pressure have control. Other factors such as thermal stress and discontinuity forces may also influence the required thickness. 

Power Supplies and Controls. Induction heating furnace loads rarely can be connected directiy to the user s electric power distribution system. If the load is to operate at the supply frequency, a transformer is used to provide the proper load voltage as weU as isolation from the supply system. Adjustment of the load voltage can be achieved by means of a tapped transformer or by use of a solid-state switch. The low power factor of an induction load can be corrected by installing a capacitor bank in the primary or secondary circuit. 

In addition, restrictions on industrial air emissions under the Clean Air Act (CAA) as amended in 1977, the Clean Air Act Amendments (CAAA) of 1990, and other state and local statutes and regulations have universal impact on the storage of toxic materials, with direct and significant effects on the design and operation of toxic material storage facilities. Whereas the primary factors which once determined how air emissions from storage tanks were handled were fire protection and loss prevention, in recent years environmental protection concerns nearly always determine the extent and nature of the air emission controls required to be installed. 

Two approaches exist to gain control of this factor altering the environment and isolating the metal from the environment. These are remedial measures and can be implemented during or after installation of the equipment. 

In the selection of control equipment, the most important waste-gas characteristics are volumetric flow rate, concentration and composition of organic compounds in the waste-gas, waste-gas temperature and humidity, and rbe content of particulate matter, chlorinated hydrocarbons, and toxic pollutants. Other factors influencing the equipment selection are the required removal efficiency, recovery requirements, investment and operating costs, ease of installation, and considerations of operation and maintenance. The selection of a suitable control method is based on the fundamental selection criteria presented as well as the special characteristics of the project. 

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. 

The majority of industrial installations will receive all or part of their electrical energy from an area electricity board supply authority. The factors that will affect the way in which this energy is imported to the site and subsequently controlled are ... 

Capacitors as bulk units can be connected to the supply busbar via a fuse switch, molded-case circuit breaker of air circuit breaker. In this type of installation control is purely manual, and in cases of a reasonably constant load and where the amount of power factor correction is limited such a manually controlled system is perfectly adequate. The supply authority may, however, require to be informed that a capacitor bank is permanently connected to the supply. Capacitors are more generally connected either in banks controlled from a VAR sensitive relay or across individual loads (e.g. motors). 

A factor which previously limited installation of automatic corrosion monitoring systems was the cost of cabling between sensors and control room instrumentation-this was particularly relevant to the electrical resistance (ER) systems. Developments to overcome this have included transmitter units at the probe location providing the standard 4-20 mA output (allowing use of standard cable) for onward transmission to data systems or the use of radio linkage which has been successfully used for other process-plant instrumentation. 

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