Energy conservation process efficiency

Enei y. In recent years the concern for energy conservation has resulted in many innovative process improvements to make the manufacture of citric acid more efficient. Eor example, heat produced by the exotherm of the neutralization of citric acid with lime is used in another part of the process where heat is requited, such as the evaporation/crystallization step. 

Pollution Prevention the use of materials, processes, or practices that reduces or eliminates the creation of pollutants or wastes at the source. It includes practices that reduce the use of hazardous materials, energy, water, or other resources and practices that protect natural resources through conservation or efficient use. 

Direct Photolysis. Direct photochemical reactions are due to absorption of electromagnetic energy by a pollutant. In this "primary" photochemical process, absorption of a photon promotes a molecule from its ground state to an electronically excited state. The excited molecule then either reacts to yield a photoproduct or decays (via fluorescence, phosphorescence, etc.) to its ground state. The efficiency of each of these energy conversion processes is called its "quantum yield" the law of conservation of energy requires that the primary quantum efficiencies sum to 1.0. Photochemical reactivity is thus composed of two factors the absorption spectrum, and the quantum efficiency for photochemical transformations. 

Utilities include the costs of electricity, generating steam, cooling water etc., and emphasises the importance of good equipment and efficient processing and energy-audits for energy conservation and consequent financial savings. 

The combination of fast kinetics and favorable thermodynamics makes the process virtually irreversible and highly efficient. The overall energy yield (the percentage of the photon s energy conserved in QH2) is >30%, with the remainder of the energy dissipated as heat. 

Many older processes (developed before the 1970s oil price crisis) were less energy efficient than those developed more recently. This should be apparent by consideration of the energy conservation features included in new plants, and the subsequent increase in complexity of the associated P ID. Energy conservation is discussed in Section 8.2.1. The selection of a process route for production of a chemical will depend upon the following factors/considerations ... 

Seader, J.D. Thermodynamic Efficiency of Chemical Processes, Industrial Energy-Conservation Manual 1, Gyftopoulos, E.P. (ed.), MIT Press Cambridge, MA, 1982. 

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