Design of disposal systems

CCPS111 gives comprehensive guidance on the design of the different types of disposal system. Other useful references are as follows. 

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Appropriate mechanical design of disposal systems is important. In some cases, the disposal system may need to be a pressure vessel. Mechanical design requirements for disposal systems.are addressed in references 3 and 4. 

McIntosh, R.D., Nolan, P.F., Rogers, R.L. and Lindsay, D. (1995) The design of disposal systems for runaway chemical reactor relief. Journal of Loss Prevention in the Process Industries, 8 (3), 169-83. 

Prevention of releases by process and equipment design, operating procedures and design of disposal systems. 

This matters most when designing a disposal system, when it is important that the back pressure exerted by flow through the disposal system does not reduce G. It may be prudent to ensure that the back pressure is at least less than 50% of the upstream reactor pressure to ensure that choking in the relief system is maintained. For safety valve systems, lower back pressures may be necessary, even for balanced valves, see 9.7.3. ... 

Requirements on treatment and disposal of hazardous chemical waste under RCRA, especially the intention to limit contamination of groundwater, are based to some extent on considerations of risks to public health and the environment posed by waste. However, requirements on waste treatment and the siting, design, operation, and closure of disposal facilities are not based on long-term projections of the ability of disposal systems to limit releases of hazardous substances to the environment, nor is any consideration given to... 

The specific design most appropriate for biomass, waste combustion, and energy recovery depends on the kiads, amounts, and characteristics of the feed the ultimate energy form desired, eg, heat, steam, electric the relationship of the system to other units ia the plant, iadependent or iategrated whether recycling or co-combustion is practiced the disposal method for residues and environmental factors. 

In this design, the inboard labyrinth of the DGS is fed with seal gas that is compatible with the process gas. The outboard labyrinth is injected with an inert gas. With this arrangement, the bearing housing is purged with inert gas, the seal gas leakage is minimized, and the mixture of seal gas and inert gas is vented to a flare or disposal system. Figure 6-21 shows a cross-section of a turboexpander with AMB and DGS. 

The equipment for the pollutant removal system includes all hoods, ducting, controls, fans, and disposal or recovery systems that might be necessary. The entire system should be engineered as a unit for maximum efficiency and economy. Many systems operate at less than maximum efficiency because a portion of the system was designed or adapted without consideration of the other portions (4). 

Conventional Flare System - The majority of pressure relief valve discharges which must be routed to a closed system are manifolded into a conventional blowdown drum and flare system. The blowdown drum serves to separate liquid and vapor so that the vapor portion can be safely flared, and the separated liquid is pumped to appropriate disposal facilities. The blowdown drum may be of the condensible or noncondensible type, according to the characteristics of the streams entering the system. Selection criteria, as well as the design basis for each type of blowdown drum, are detailed later in this volume. The design of flares, including seal drums and other means of flashback protection, is described later. 

This chapter covers the design of facilities to handle equipment drainage and contaminated aqueous effluents that are sent for appropriate disposal blowdown drum systems to receive closed safety valve discharges, emergency vapor blowdowns, etc. and facilities for process stream diversion and slop storage. Also covered are criteria for selecting the appropriate method of disposal. Design of flares is covered in a subsequent chapter. 

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