Design of coolers for use in an existing cooling water network

This paper presents a procedure for the specification of design conditions for the incorporation of new coolers into existing cooling water networks. In practical terms, the location for the placing of a new cooler into an existing network will depend among other things on the plant layout; once this is decided upon, there are various ways in which the new unit can be incorporated, namely: (a) in a totally new parallel branch; (b) in series with other units in an existing branch and, (c) in parallel with an existing exchanger. This paper looks at the thermo–hydraulic effects that result when each of these options is considered. On the one hand, it is shown that the placing of a new unit in series with existing branches leads to reduced thermo–hydraulic disturbances upon the other units and, on the other, the installation of new exchangers in new branches results in increased disturbances which may prove less economical. The procedure involves the thermo-hydraulic simulation of the cooling water network which includes consideration of pump performance and cooling tower performance. An approximate sizing approach for new coolers based on the flow resistance factor (K) is introduced and incorporated into the analysis. Another important element considered in this work is fouling due to crystallization of inverse solubility dissolved salts. Results confirm the findings of other researchers that arbitrarily installing new coolers on new parallel branches is not a good practice. It is shown that the design of new coolers needs to be carried out in the context of the subsequent performance of the cooling network.

► A procedure for the thermo-hydraulic effects of the incorporation of new coolers into existing cooling systems is presented.
► Pump and cooling tower performance are incorporated into the model.
► The effect of fouling upon the thermo–hydraulic performance of the systems is analyzed.