Heat recovery projects

The matter of different investment criteria for energy users versus regulated utilities is exemplified by comparison of the feedwater heater project (41) to the cement kiln heat recovery project referred to above. The utility chose to replace the de-... 

Several hot or cold utilities may be used in a heat recovery project. GCC is the appropriate conceptual tool. Let s review the heat integration of the streams presented in Table 10.1. The same hot load as in Fig. 10.14 can be shared between two steam levels high-pressure (HP) and low-pressure (LP) steam. In the GCC the solution is simple represented by horizontal segments placed at temperatures corresponding to their pressures, as in Fig. 10.23 for three steam levels. This feature makes possible to specify exactly the amount required by each utility. Simple targeting can be applied to optimise their amount if the prices are significantly different. 

The researches have also pointed out that the waste heat recovery project is only profitable when one is faced with great energy consrrmptions together with high cost of the unit electric energy. 

THE EXISTING CONDITIONS IN SOUSELAS PLANT OF CIMPOR JUSTIFYING A WASTE HEAT RECOVERY PROJECT... 

Considering that Cimpor s factoiy at Souselas has an installed capacity of 2 million cement tons, which represents electric eneigy consumptions of about 200 GWh per year, and due to the high cost of the kwh suppUed, thus are assembled all the economical conditions for the development of a waste heat recovery project in this plant (great consumptions, very expensive electric energy). In this sense some specialised companies in this matter have been contacted, being elected NIHON CEMENT COMPANY (NCC), a Japanese Company from Tokyo, with well succeeded experiences in this field. 

This term is most familiar to people as the return on investment, or ROI. The ROI is defined as the interest rate that would result in a return on the invested capital equivalent to the project s return. For illustration, if we had an air abatement project where heat recovery was involved, and there was an overall ROI of 30 percent, that s financially equivalent to investing resources in the right stock and having its price go up 30 percent. This is called a Primitive ROI. ... 

In these systems, the turbine generator is about 1/3 of the total cost with the other costs including the heat recovery steam generator, electrical equipment, interconnection to the grid, labor, project management and financing. 

A typical ioo kW reciprocating engine costs i,5oo/kW fully installed, and an 800 kW unit might cost i,ooo/kW. The engine itself accounts for only one-quarter of this price (or less for the smallest units). Again, the bulk of the price comes from the heat recovery system, the interconnect/electric system, labor and materials, project management, construction, and engineering costs. 

The independent mode is essentially an adaptation of the WBP project combined-cycle plant concept operating with bagasse and trash. In independent mode, for one BIG-GT module based on the LM 2500 gas turbine and a HRSG operating at 60 bar/500 C, a net electric output of 33 MWe, and a net electric efficiency of 40% can be achieved for bagasse but with cane trash, the efficiency on an LHV basis is 34 to 37%, the lowest value associated with a dry fuel during the off-season period when low level heat recovery in the dryer is no longer appropriate. 

The two curves can now be matched to determine how much heat can be recovered from the hot streams in the process to the cold streams in the process. The composite curves are shown in Fig. 4 matched such that there is a minimum temperature difference (Ar in) of 10°C. The hot composite curve must be above the cold composite curve by at least at all points for feasible heat transfer. The relative position of the two curves has been adjusted such that they are separated by a specified minimum temperature difference. In this case, ATmin = 10°C. The overlap between the composite curves represents the heat recovery potential between the hot and cold streams in the process, shown in Fig. 4. The monotonic nature of the construction of the composite curves allows for maximum overlap between the curves. This in turn allows the construction to determine the maximum heat recovery potential (Qrec)- By maximizing the heat recovery, the residual demand for heating and cooling utilities is minimized. In Fig. 4, the part of the cold composite curve that projects beyond the start of the hot composite curve represents the external heating utilities required The part of the hot... 

Solar Industrial Process Heat (including use of solar energy to generate steam for enhanced oil recovery projects)... 

Wood Combustton (for both industrial and utility application) Solar Industrial Process Heat (including use of solar energy to generate steam for enhanced oil recovery projects) Non-Battery Storage Facilities for Utilities (including underground compressed air and underground hydro)... 

A 100-kW reciprocating engine generating system may cost 1,500/ kW installed, while an 800-kW unit can cost l,000/kW. The engine cost is about one fourth of the total price. The rest of the cost comes from the heat recovery system, interconnect/electrical system, labor, materials, project management, construction and engineering. 

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