Refrigeration heat integration

Figure 24.37 Heat integration of a single-level refrigeration system.

Refrigeration cycles offer many opportunities for heat integration with the process. These can be explored using the grand composite curve. 

Compressed gas at 450 psig is dried and chilled. A double demetha-nizing stripping system (8,9) operating at medium pressure and reboiled by cracked gas minimizes the refrigeration required (heat integration) as well as the investment cost for separating methane (top) and C2+ cut (bottoms). A dual column concept—absorber (10) concept—is applied between the secondary demethanizer overheads and the chilled cracked... 

The second situation may be found in heat integrated flowsheets, when duty is exchanged between different units. An example is the simulation of heat integrated distillation systems (integration of condensers and reboilers of distillation columns, coupling with a refrigeration system, etc.). The transmission of information prevents the formation of internal recycle loops, occasionally quite large, whose iterative computation would penalise the overall solution (see the Example 3.4). 

For a liquid cracker, a double demethanizing stripping system operating at medium pressure and reboiled by cracked gas, minimizes the refrigeration required (heat integration) as well as the investment for... 

In the new revamp study (Alanis and Sinclair, 2002), a pinch analysis study considering both process changes and heat integration was conducted to identify process design changes that can reduce refrigerant compressor shaftwork. Pinch and... 

More detailed heat integration with different utilities (cold water, refrigerator, steam), restrictions and forbidden matches was carried out simultaneously with the synthesis of the reactor/separator/HEN network. Reactors were modelled as adiabatic reactors due to practical constraints. 

Heat Pumps. Because of added capital and complexity, heat pumps are rarely economical, although they were formerly commonly used in ethylene/ethane and propylene/propane spHtters. Generally, the former spHtters are integrated into the refrigeration system the latter are driven by low level waste heat, cascading to cooling water. 

Continuous Multicomponent Distillation Column 501 Gas Separation by Membrane Permeation 475 Transport of Heavy Metals in Water and Sediment 565 Residence Time Distribution Studies 381 Nitrification in a Fluidised Bed Reactor 547 Conversion of Nitrobenzene to Aniline 329 Non-Ideal Stirred-Tank Reactor 374 Oscillating Tank Reactor Behaviour 290 Oxidation Reaction in an Aerated Tank 250 Classic Streeter-Phelps Oxygen Sag Curves 569 Auto-Refrigerated Reactor 295 Batch Reactor of Luyben 253 Reversible Reaction with Temperature Effects 305 Reversible Reaction with Variable Heat Capacities 299 Reaction with Integrated Extraction of Inhibitory Product 280... 

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