Heat exchanger

Claim 2

In a method of operating a fluid-heating system in which the heated fluid is piped away from a heat exchanger and is returned to the heat exchanger to be reheated and any heated fluid which is not returned is compensated for by a cold fluid makeup, the improvement which comprises combining most of the recycled fluid and the makeup fluid in a first conduit exteriorly of the heat exchanger and feeding them to the heat exchanger through a bottom inlet, combining some small proportion of said recycled fluid and some small proportion of said makeup fluid in a second conduit exteriorly of the heat exchanger and feeding them to an inlet at the top of the heat exchanger, the relative proportions of recycled fluid and makeup fluid introduced into said second conduit being adjustable to alter the temperature characteristics of the second conduit flow relative to those of the first conduit flow, causing said second flow comprising the small proportions of recycled fluid and makeup fluid to flow through a control chamber within said heat exchanger such that the temperature of said second flow is sensed by a temperature responsive means which is adapted to regulate the heat to the heat exchanger.

Claim 3

The method of operating a heating system as claimed in claim 1 in which when there is no flow of recycled fluid and makeup fluid through the inlet at the top of the heat exchanger, the fluid in the body of the heat exchanger circulates through said control chamber and about said temperature responsive means.

Claim 4

The method of operating a heating system as claimed in claim 1 in which the volume of flow through said inlet at the top of the heat exchanger is less than 10 percent of the volume of flow through the inlet at the bottom of the heat exchanger.

Claim 5

The method of operating a heating system as claimed in claim 3 in which the proportion of flow through said inlet at the top of the heat exchanger and said inlet at the bottom of the heat exchanger is variable.

Claim 6

A heat exchanger comprising: a shell; a plurality of heating coils within the shell; a first inlet at the bottom of the shell; a second inlet at the top of the shell; an outlet at the top of the shell; a control chamber inside said shell adjacent said second inlet and adapted to receive fluid admitted into said shell therethrough; temperature control means located within said control chamber responsive to the temperature of fluid admitted thereinto from said second inlet to regulate the heating effecting of said heating coIls; first conduit means for discharging heated liquid from said outlet at the top of said shell; second conduit means for introducing recycled heated liquid into said first inlet at the bottom of said shell; third conduit means for introducing cold makeup fluid into said second conduit means upstream of said first inlet whereby a mixture of recycled fluid and makeup fluid may be introduced into said shell through said first inlet; fourth conduit means for conveying a portion of recycled fluid from said second conduit means to said second inlet at the top of said shell whereby a portion of the recycled heated liquid is introduced into said shell through said second inlet; fifth conduit means for conveying a portion of said cold makeup fluid from said third conduit means to said fourth conduit means upstream of said second inlet whereby a mixture of recycled fluid and makeup fluid may be introduced into said shell through said second inlet; first valve means in said fourth conduit for regulating the flow of recycled fluid therein relative to the flow thereof in said second conduit; and second valve means in said fifth conduit for regulating the flow of makeup fluid therein relative to the flow thereof in said third conduit; said first and second valve means together regulating the amount of fluid entering the shell through the second inlet relative to that entering the bottom inlet and regulating the ratio of makeup fluid relative to recycled fluid entering the shell through said second inlet independently to said ratio entering the shell through said first inlet.

Claim 7

A heat exchanger comprising: a shell; a plurality of heating coils within the shell; a first inlet at the bottom of the shell; a second inlet at the top of the shell; an outlet at the top of the shell; a control chamber inside said shell adjacent said second inlet and adapted to receive fluid admitted into said shell therethrough; temperature control means located within said control chamber responsive to the temperature of fluid admitted thereinto from said second inlet to regulate the heating effecting of said heating coIls; first conduit means for discharging heated liquid from said outlet at the top of said shell; second conduit means for introducing recycled heated liquid into said first inlet at the bottom of said shell; third conduit means for introducing cold makeup fluid into said second conduit means upstream of said first inlet whereby a mixture of recycled fluid and makeup fluid may be introduced into said shell through said first inlet; fourth conduit means for conveying a portion of recycled fluid from said second conduit means to said second inlet at the top of said shell whereby a portion of the recycled heated liquid is introduced into said shell through said second inlet; fifth conduit means for conveying a portion of said cold makeup fluid from said third conduit means to said fourth conduit means upstream of said second inlet whereby a mixture of recycled fluid and makeup fluid may be introduced into said shell through said second inlet; first valve means in said fourth conduit for regulating the flow of recycled fluid therein relative to the flow thereof in said second conduit; and second valve means in said fifth conduit for regulating the flow of makeup fluid therein relative to the flow thereof in said third conduit; said first and second valve means together regulating the amount of fluid entering the shell through the second inlet relative to that entering the bottom inlet and regulating the ratio of makeup fluid relative to recycled fluid entering the shell through said second inlet independently to said ratio entering the shell through said first inlet.

Claim 8

The heat exchanger as claimed in claim 5 in which the walls of said control chamber are perforated to permit the fluid in the shell of the heat exchanger to circulate about the temperature responsive means, when there is no flow of recycled fluid and makeup fluid through said inlet at the top of the heat exchanger.