Plant operating requirements

Operating requirements typical of those required for the production of phosgene in a modern plant are given in Table 4.2 [311a]. In addition, the modern phosgene plant will 

TYPICAL MODERN PLANT OPERATING REQUIREMENTS [311a,823b] 

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Unless some discipline is imposed, engineering personnel, especially where contractors are involved, will define far more alarms than plant operations require. This situation may be addressed by simply setting the alarm hmits to values such that the alarms never occur. However, changes in alarms and alarm hmits are changes from the perspec tive of the Process Safety Management regulations. It is prudent to impose the necessary discipline to avoid an excessive number of alarms. Potential guidelines are as follows ... 

Table III summarizes the basic plant operating requirements in terms of utilities, manpower, and ash disposal. Electric power consumption figures are provided for three different system designs simple incineration without heat recovery or an air pollution control device, incineration with heat recovery but no air pollution control device, and incineration with both heat recovery and air pollution control (stack gases filtered through a baghouse).

Quantitative and health risk assessments are complex and, of necessity, include simplifications. The plant safety professionals should review the assessments thoroughly to be aware of their basic assumptions and/or limitations. Plant operating requirements may change, and changes need to be viewed in the light of the risk assessments. 

Plant operation can be hazardous. The elimination or control of hazards, and the establishment of safe operating practices, are prerequisites of plant operation, requiring priority attention during plant design. Environmental impact is also invariably an issue. 

Successful plant operation requires theoretical knowledge and observational knowledge.Typically, the engineering staff is trained in theory, whereas operators control the observational area. An operator who possesses both theoretical and observational skills will be a valuable asset to the company. Corporate rightsizing and restructuring should require technicians of the future to perform more challenging and technical job functions. 

At the same time, some obvious plant operational requirements will have to be satisfied Thus noise control measures must not ... 

During normal operation, protection systems are in standby, therefore failures of components may not be detected. For these old plants, periodic tests are performed to provide some confidence in the capability of protection systems to fulfil their function. These tests are designed to simulate Reactor Protection actions following an accident or incident situation and have to trigger the whole protection chain from the sensors to the actuators. Manual testing during plant operation requires time and could be the source of errors in addition any untimely protection actuation has to be avoided during or after the test, as well as unwanted inhibition when the plant is in operation. 

A rack and frame press uses heavy nylon cloth positioned in a wooden frame inside a rack. A measured amount of apple or other fmit mash is added from a hopper above the frame. The mash is leveled with a hand trowel and the edges of the nylon cloth are folded over the mash to encase it and create a cheese. The frame is removed, and a second rack is placed on top of the first cheese the process is repeated until a stack of cheeses is prepared. A hydrauhc ram then appHes gradually increa sing pressure on the stack and expresses the juice. A high yield of juice (80%) is obtained and no press aid is required. Because this process is labor intensive (17), it is mostly used for small farm and pilot-plant operations. 

Operational Constraints and Problems. Synthetic ammonia manufacture is a mature technology and all fundamental technical problems have been solved. However, extensive know-how in the constmction and operation of the faciUties is required. Although apparendy simple in concept, these facihties are complex in practice. Some of the myriad operational parameters, such as feedstock source or quaUty, change frequendy and the plant operator has to adjust accordingly. Most modem facihties rely on computers to monitor and optimize performance on a continual basis. This situation can produce problems where industrial expertise is lacking. 

Demand. The demand for uranium in the commercial sector is primarily determined by the requirements of power reactors. At the beginning of 1993, there were 424 nuclear power plants operating worldwide, having a combined capabity of about 330 GWe. Moderate but steady growth is projected for nuclear capacity to the year 2010. The capacity in 2010 is expected to be about 446 GWe (29). 

Defining the requirements for a pilot-plant control system is often difficult because process plant experience for comparison and evaluation is commonly lacking and the design is frequentiy performed by personnel inexperienced in either instmmentation systems or pilot-plant operations. The isolated and often intermittent nature of pilot-plant operations also inhibits evolution and promotes individual unique installations. This compHcates the selection process. 

In converting ESBR latex to the dry mbber form, coagulating chemicals, such as sodium chloride and sulfuric acid, are used to break the latex emulsion. This solution eventually ends up as plant effluent. The polymer cmmb must also be washed with water to remove excess acid and salts, which can affect the cure properties and ash content of the polymer. The requirements for large amounts of good-quaUty fresh water and the handling of the resultant effluent are of utmost importance in the manufacture of ESBR and directly impact on the plant operating costs. 

The demand for uranium ia the commercial sector is primarily determined by the consumption and inventory requirements of nuclear power reactors. In March 1997, there were 433 nuclear power plants operating worldwide with a combined capacity of about 345 GWe (net gigawatts electric)... 

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