Taking all of this into account, we can see that a medium voltage electric resistance system can significantly simplify site management and infrastructure, installation, operation and maintenance over traditional low voltage systems. Framing up a similar look when comparing medium voltage to traditional fuel fired systems, we can see the total cost of ownership evaluation reveals a much different
Cost of ownership
480V
4160V
Savings
Installation, $ Operating, $ Maintenance, $
753,650
528,655
224,995 633,140
873,940 240,800
61,200
10,200 69,500
51,000 94,155
10 yr life cycle replacements, $ 163,655
20 year costs, $
1,852,445 849,155 1,003,290
Annualised costs, $
92,622
42,458
50,165
Table 1 Cost of ownership
conversion. The true boiler operational efficiency is more complex to derive. While the burners may be capable of combustion efficiencies into the 90% range, this number is based on factors like excess air percentage and fuel specification. This is also specifically aimed at how well the boiler converts fuel to heat, but does not indicate whether that heat is driven into the process. This is where the true efficiency of a fuel fired boiler presents a much different story. Once the fuel has been burned, a percentage of that heat is immediately vented off through the flue stack. The heat that does pass through the boiler’s exchange system also faces challenges of its own, specifically how well that heat is transferred from the tubes into the process. As these boilers operate over time, soot from combustion will begin to coat onto components, reducing effective heat transfer.
picture compared to the myopic cost of energy discussion that we typically see. Particularly with a changing landscape with local and federal legislation aimed at decarbonisation, the chips continue to stack in favour of electric resistance heating. Cost of ownership So how does a medium voltage electric system compare to a traditional fuel fired system when a full cost of ownership evaluation is performed? In addition to medium voltage systems having nearly 99% total system efficiency, the inherent design of the electric heating element means the derived heat is surrounded by the medium to be heated, forcing that heat directly into the process. On the other hand, fuel fired systems advertise certain efficiencies but are only factoring in fuel
Figure 2 3D Model of Chromalox DirectConnect MVSGI Series electric steam generator
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