better data collection of recovery
In the previous chapters we have seen how instrumental the economic contribution of a good heat recovery system can be in keeping under control the costs of a modern finishing-house.
For some reason, however, the importance attributed to these systems is always, in a sense, treated as an accessory and not, as it should be, as a fundamental part of the process of energy generation needed to run the factory.
A quantity of heat equal to about one third of the entire consumption can be recovered with a relatively insignificant investment.
While a great effort is usually exerted in the correct analysis and accounting of efficiency data on power generation boilers (generation, distribution, consumption), very little or nothing is invested to check the operation of these "auxiliary generators" of energy which account for at least one third of the total thermal energy flow and are disseminated on the various machines.
At best four thermometers are mounted to support a heat exchanger, with no flow detection system and no system of data collection.
This implies that the continuous and constant efficiency control of installations is virtually impossible. A very superficial analysis of their functioning is left to the operators and maintainers and, generally, the reaction time for maintenance calls (that need to be part of the recovery process) is left only to a fixed schedule.
On the contrary, the problem of fouling is of fundamental importance.
Almost every exchanger suffers from the fact that the contaminants present in the waste water may be deposited on its surfaces, progressively decreasing the efficiency up to the point that they become practically unusable. The importance of loss of efficiency varies according to the treated material; it is depending on the operating characteristics of the machine and can affect significantly the cost of a process.
Especially when the machines are used intensively, even a limited variation in the efficiency of recovery systems can result in extremely relevant cost increases. It goes without saying that, if control is no longer entrusted to the discretion of the operators but objectively brought to the attention of those in charge, better economic results should be expected.
With a relatively small expenditure, each of them can be instrumented with an electromagnetic flow-meter, four temperature probes and one calculating instrument for the recovered energy and the efficiency of generated heat exchange.
These instruments can then be networked and all data can be collected in a concentrating software that can provide, automatically, information about the "well standing status" of each of the monitored heat exchangers.
The same centralized software can keep a log of the taken readings by generating reliable reports of the amount of plant-wide recovered energy.
In practice, this would result in a kit (energy-meter, log-analyzer), to be mounted on each of the recovery exchangers present in the factory, and in the creation of a light network that connects all of them to a central hub that can communicate with a normal PC on which the concentration software can be installed.
The advantages of such an instrument are relevant:
· Obtain objective information on the constant amount of heat re-generated inside the plant.
· Obtain objective information about the need of pro-active service for each monitored heat exchanger.
· Obtain reliable information about the determination of the energy cost of the performed processes.
· Get automatic alerts in case of eventual failure of each of the connected systems.
Given the considerable amount of involved energy, a global improvement of the efficiency of the systems equal to just a few % points can ensure the payback of a system of this kind in a very short time.