Abstract
The paper deals with the load distribution between a number of boilers operating in parallel, with a view to obtaining minimum fuel consumption. The application of the theory of minima leads to a graphical solution, and it is demonstrated that maximum plant efficiency can generally be obtained only when all boilers share in the load fluctuations to an extent depending on the input-output characteristics of the various boilers and on the momentary load. The division of a plant into groups of boilers operating at base load and fluctuating load, respectively, is generally not economical. Automatic boiler control not only increases the operating efficiency of the individual boiler but can be used also for maintaining the most economical load distribution between the units, and thereby also raises the efficiency of the plant as a whole.
The paper also discusses how many and which units should be used to cover a given load range, and when a boiler ought to be banked or connected to the line again. This depends upon the ratio between standby and operating periods; but generally it will be more economical to operate all boilers down to their minimum load than to bank some of them.
The same principles of load distribution can be applied to the parallel operation of any kind of machines other than boilers.
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