Energy recovery utilization

Example 16.1 The process stream data for a heat recovery network problem are given in Table 16.1. A problem table analysis on these data reveals that the minimum hot utility requirement for the process is 15 MW and the minimum cold utility requirement is 26 MW for a minimum allowable temperature diflFerence of 20°C. The analysis also reveals that the pinch is located at a temperature of 120°C for hot streams and 100°C for cold streams. Design a heat exchanger network for maximum energy recovery in the minimum number of units. 

The pinch design method developed earlier followed several rules and guidelines to allow design for minimum utility (or maximum energy recovery) in the minimum number of units. Occasionally, it appears not to be possible to create the appropriate matches because one or other of the design criteria cannot be satisfied. 

Determine the pinch temperatures and the minimum utility requirements for the streams set out in the table below, for a minimum temperature difference between the streams of 20°C. Devise a heat exchanger network to achieve the maximum energy recovery. 

According to [4], two coincineration routes can be utilized with good energy recovery coincineration in coal-fired thermoelectric plants and coincineration in cement furnaces to replace fossil fuels, which in the Brazilian case is generally petroleum coke (petcoke). The substitution in power plants is up to 10% and in cement plants up to 30% by weight. The calorific power of the SRF in the study by [4] is 18 MJ/kg or 4,300 kcal/kg, which corresponds to 6% of the calorific power of coal. 

Demirbas, M. F., Technological options for producing hydrogen from renewable resources. Energy Sources, Part A Recovery, Utilization, and Environmental Effects 2006, 28(13), 1215-1223. 

Peter J. Loftus, D.Phll. Principal, ENVIRON International Corp. Member, American Society of Mechanical Engineers (Heat Generation, Thermal Energy Conversion and Utilization, Energy Recovery)... 

This forms the basis of constructing an enthalpy budget in which the total enthalpy flux is compared with the scalar heat flux, 7q(W m-3), obtained from dividing heat flow by size (volume or mass) of the living matter. If account is made of all the reactions and side reactions in metabolism, the ratio of heat flux to enthalpy flux, the so-called energy recovery ( Yq/H = Jq/Jh) will equal 1. If it is more than 1, then the chemical analysis has failed fully to account for heat flux and if it is less than 1, then there are undetected endothermic reactions. Account for all reactions may seem a formidable task, but it should be borne in mind that anabolic processes dissipate insignificant amounts of heat compared with those of catabolism and that ATP production and utilization are balanced in cells at steady-state. Catabolism is generally limited to a relatively few well-known pathways with established overall molar enthalpies. So, as will be seen later, the task is by no means mission impossible. ... 

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