Energy Loss Assessment

What are the major energy losses in a process This is the first question that people should ask before embarking on a significant effort to improve process energy efficiency. The answer to this question could lead to identification of major improvement opportunities and help to define the need for large energy improvement effort. 

In a process, energy losses consist of both thermal and mechanical losses. Thermal losses are typically originated from column overhead condensers, product mn down coolers, furnace stack, steam leaks, poor insulation of heat exchangers/piping and vassals and so on. Mechanical losses could also be significant, which usually occurs in rotating equipment, pressure letdown valves, control valves, pump spill back, heat exchangers, pipelines, and so on. Some of the thermal and mechanical losses are recoverable with a decent payback of investment but many others do not. 

An energy loss audit, as discussed here, seeks to identify key recoverable losses. The audit is relatively quick and is designed to determine improvement potential. If the energy loss audit identifies large energy losses, more detailed energy assessment efforts will be undertaken later if so required. Detailed assessment methods will be discussed in the later chapters. 

Energy and Process Optimization for the Process Industries, First Edition. Frank (Xin X.) Zhu. 

---

TABLE 8.3. Idea List from Energy Loss Assessment... 

Linked with its qualities, assessed above, as an imaging and structural tool, the STEM assumes prime importance when considered as a microanalytical instrument. As pointed out in the introduction, the interaction of the fine probe in STEM with, potentially, only a small volume of the sample suggests the possibility of microanalysis on a scale hitherto unattainable. Two main areas will be considered here -the emission of characteristic A -rays by the sample, and the loss of energy from the primary beam in traversing the latter. Ideally, a fully equipped analytical electron microscope will utilize both techniques, since, as a result of the relative positions of A"-ray detector and the energy loss spectrometer in the electron optical column, simultaneous measurements are possible. However, for the sake of convenience we will consider the methods separately. 

The quartz crystal microbalance (QCM) is an excellent tool for these investigations since the frequency change produced by the adsorption on the surface of a piezoelectric crystal can be used to assess the mass (to a few ng/cm ) of the adsorbent using the Sauerbrey equation. Since the adsorbed protein layers can have some degree of structural flexibility or viscoelasticity that is undetectable by the determination of the resonance frequency alone, the energy loss, or dissipation factor (D), due to the shear of the adsorbent on the crystal in aqueous solution must also be determined.The technique is termed QCM-D and as well as representing an improvement in the study of biomolecular-surface interactions, it presents an opportunity to observe the adsorption of AFP and PVP, on a model nucleator with a hydrophilic surface. 

Polymers, as well as elastomers, are reinforced by the addition of small filler particles. The performance of rubber compounds (e.g. strength, wear resistance, energy loss, and resilience) can be improved by loading the rubber with particulate fillers. Among the important characteristics of the fillers, several aspects can be successfully interrogated by AFM approaches. For instance, the particle and aggregate size, the morphology, and in some cases the surface characteristics of the filler can be assessed. 

To conclude this section we might assert that the main techniques for assessing the problem of Rydberg and valence excited states of organic molecules are, in practice, far-UV absorption spectra, photoelectron spectra, and advanced quantum chemical calculations. It should be added that the electronic spectra can also be obtained from electron-impact (energy loss) and circular dichroism spectra. The reader is referred to Robin s Volumes I to III [S, 23] he systematically considers the three kinds of spectra when they are available. 

---