Operating envelope

Design equipment to accommodate maximum operating envelope. Appropriate use of Safety-Related Systems (SRS) such as Safety-Instrumented Systems (SIS). 

Equipment used in different processes during its lifecycle. Surplus equipment or existing equipment reused for different use. Possibility of equipment being used outside its safe operating envelope. 

Available equip- Procure equipment that can be used in other ment determines processes (current or future) without operating the process chem- close to its operating envelope, istry selected., Provide equipment with comparable pressure Operating close to rating for the entire system the safe operating envelope of the batch sizes to equipment capabilities equipment and the relief capability. ... 

High temperature material fed to vessel. Temperature excursion outside the safe operating envelope resulting in a runaway reaction. 

All compressors have an operating envelope. The size is dependent on the compressor type and the application. If the appropriate design considerations were implemented, then operation within the envelope should be problem-free. The first problem stems from a communication gap. Engi... 

The source of vapor shall be the operating envelope and stored position of the outboard fiange connection of the ioading arm (or hose). 

The impeller configuration has a major impact on stability and operating envelope. There are two impeller configurations in-line and back-to-back, or opposed. With the in-line design, all impellers face in the same direction. With the opposed design, impeller direction is reversed in adjacent stages. 

The acceptable operating envelope for centrifugal compressors is very limited. Therefore, care should be taken to minimize any variation in suction supply, back-pressure caused by changes in demand, and frequency of unloading. The operating guidelines provided in the compressor vendor s O M manual should be followed to prevent abnormal operating behavior or premature wear or failure of the system. 

The mode of operation of a specific application should be the first consideration. The inherent design of each type of compressor defines the acceptable operating envelope or mode of operation that it can perform with reasonable reliability and life cycle costs. For example, a bullgear-type centrifugal compressor is not suitable for load-following applications but will prove exceptional service in constant-load and volume applications. 

Mounting configuration and operating envelope Industrial standards, such as the rathbone severity chart, assume that the machine is rigidly mounted on a suitable concrete foundation. Machines mounted on deck-plate or on flexible foundations have higher normal vibration profiles and cannot be evaluated using these standards. 

In addition, industrial standards assume a normal operating envelope. All machines and process systems have a... 

Since variations in process variables, such as load, have a direct effect on the vibration energy and signature generated by a machine-train, the actual operating envelope for each baseline data set must also be clearly identified. If this step is omitted, direct comparison of other data to the baseline will be meaningless. The label feature in most vibration monitoring systems permits tagging the baseline data set with this additional information. 

Coupling selection is highly dependent on the mode of operation, which includes torsional characteristics, speed, and the operating envelope. 

The operating envelope defines the physical requirements, dimensions, and type of coupling needed in a specific application. The envelope information should include shaft sizes, orientation of shafts, required horsepower, full-range of operating torque, speed ramp rates, and any other data that would directly or indirectly affect the coupling. 

For small vessels and slow reactions, corrections must be made because of the heat content of the reaction vessel itself. For large-scale reaction vessels and for rapid reactions, the system will be close to adiabatic operations. This aspect must be taken into account in scale-up. In effect, the extrapolation of data obtained in small-scale equipment has limitations as discussed in [193]. In case of a runaway, the maximum temperature in the reaction system is obtained from the adiabatic temperature rise, that is, Tmax = (Tr + ATad). In reality, the adiabatic temperature rise is significantly underestimated if other exothermic reaction mechanisms occur between Tr and (Tr + ATad). Therefore, a determination must be made to see if other exothermic events, which may introduce additional hazards during a runaway, occur in the higher temperature range. This can determine if a "safe operating envelope" exists. 

Therefore, the data that can be obtained from these tests, which will help in specifying the safe operating envelope on the full-scale plant, include ... 

Transient issues are important in transport applications and should be addressed early by testing. The challenge is to demonstrate the operation at high sulfur content over the full operating envelope of the vehicle power unit - start-up, transients, shutdown, sulfur spikes in the fuel, etc. using the same processor. 

Preventive measures either take automatic remedial action or allow for manual intervention to prevent the conditions for uncontrolled reaction being achieved. They include the use of sensors, trips, alarms, control systems, and other safety features. These measures require a.thorough understanding of the safe operating envelope within which the process must be maintained.. . ... 

At PPG, Class 1 Prooftesting also covers 250 Safety Instrumented System loops in the PSM Safety Systems. A Safety Instrumented System (SIS) is composed of sensors, logic solvers, and final control elements for the purpose of taking the process to a safe state when predetermined conditions are violated. SISs are normally controlled by a PLC with the sole function of monitoring a process to insure operation is maintained within the safe operating envelope. 

Raising a reactor operating temperature within the safe operating envelope. 

Proposals to operate at significantly different pressures, temperatures, flow rates, acidity, etc., which are considered outside the well-understood and documented Safe Operating Envelope. ... 

The Safe Operating Envelope has been defined as the range of process parameters (such as temperature, pressure, flow, level, composition) that are critical to safe operation. The Safe Operating Envelope upper/lower limits are listed in the Safe Operating Envelope tables maintained under Process Safety Information. Operating beyond these limits will cause a process upset. Key maximum and minimum Emits are set based on manufacturers specifications, theoretical calculations, or operating experience. 

Does the change involve revisions to critical operating procedures that could result in operating outside of the defined safe operating envelope ... 

Multifunctional Reactors Reaction may be coupled with other unit operations to reduce capital and/or operating costs, increase selectivity, and improve safety. Examples are reaction and distillation and reaction with heat transfer. Concepts that combine reaction with membrane separation, extraction, and crystallization are also being explored. In each case, while possibly reducing cost, the need to accommodate both reaction and the additional operation constrains process flexibility by reducing the operating envelope. 

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