Heat Exchanger with Multiple Internal Diverters

Abstract

The present application provides improved heat exchangers for controlling the rate of flow through the heat exchanger. The heat exchanger includes an inlet coolant box, and an outlet coolant box, wherein the inlet coolant box and the outlet coolant box are separated by a partition, wherein the partition comprises a first diverting device and a second diverting device, and wherein the range of flow rates over which the first diverting device diverts fluid is different then the range of flow rates over which the second diverting device diverts fluid.

Description

TECHNICAL FIELD

The present application relates to heat exchangers and more particularly relates to heat exchangers with multiple internal diverters for controlling flow rates of the cooling medium through the heat exchanger.

BACKGROUND OF THE INVENTION

Generally described, the rate of flow of the cooling medium through a heat exchanger has both a minimum level and a maximum level. The minimum level is determined by the amount of flow required to perform the heat exchanging function of the heat exchanger, and the maximum level is determined by the fluid velocity limits of the heat exchanger. In practice, the amount of fluid that is actually delivered to a heat exchanger may be greater than the minimum amount of fluid that is required to run the exchanger.

A variety of methods currently exist for controlling the rate of flow through heat exchangers. One method involves installing bypass piping outside of the heat exchanger between the fluid inlet piping and the fluid outlet piping. Unfortunately, this fixed design is only effective over a limited range of flow rates, and increases the weight and footprint of the heat exchanger unit. Another method involves installing an external control valve on the fluid piping and using digital controllers to adjust continuously the valve so as to control the flow rate. Although this method may be able to control the rate of flow, the control valves, controllers, and pressure sensors may be prohibitively expensive.

What is desired, therefore, is a heat exchanger that can provide a more consistent rate of flow through the heat exchanger over a wide variety of total fluid flow rates. The heat exchanger may be relatively inexpensive, and may allow for a relatively small heat exchanger footprint.

BRIEF DESCRIPTION OF THE INVENTION

The present application thus provides a heat exchanger that controls the rate of flow through the heat exchanger and a method for exchanging heat. The heat exchanger may include an inlet coolant box, and an outlet coolant box, wherein the inlet coolant box and the outlet coolant box are separated by a partition, wherein the partition comprises a first diverting device and a second diverting device, and wherein the range of flow rates over which the first diverting device diverts fluid is different then the range of flow rates over which the second diverting device diverts fluid. The method may include providing a heat exchanger comprising an inlet coolant box and an outlet coolant box, wherein the inlet coolant box and the outlet coolant box are separated by a partition; feeding a fluid into the inlet coolant box at a total rate of flow, wherein the total rate of flow varies over time between a minimum and a maximum; diverting a first portion of the fluid across the partition and into the outlet coolant box during periods of time when the total rate of flow is above a first rate of flow between the minimum and the maximum; and diverting a second portion of the fluid across the partition and into the outlet coolant box during periods of time when the total rate of flow is above a second rate of flow between the minimum and the maximum.

These and other features of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional side view of a prior art steam condenser heat exchanger.

FIG. 2 is a cross sectional side view of one embodiment of a heat exchanger coolant box.

FIG. 3 is a partial cross sectional side view of the heat exchanger coolant box of FIG. 2.

FIG. 4 is a raised perspective view of the heat exchanger coolant box of FIG. 2 with the end cover removed.

FIG. 5 is a lowered perspective view of the heal exchanger coolant box of FIG. 2 with the end cover removed.

DETAILED DESCRIPTION OF THE INVENTION

The present application provides an improved heat exchanger and improved methods for exchanging heat.

I. General Heat Exchanger Structure

Referring now to the drawings, FIG. 1 shows a cross sectional side view of a prior art steam condenser heat exchanger 100. The heat exchanger 100 may be used to convert steam into condensate (water).

The heat exchanger 100 may include a tube side 102 and a shell side 104. The tube side 102 may include an inlet coolant box 106, an outlet coolant box 108, and an intermediate coolant box 110. The Inlet coolant box 106 and the outlet coolant box 108 may be separated by a partition 112. The shell side 104 may include one or more baffles 114. The baffles 114 may direct the flow of fluid through the shell side 104.

A cooling fluid, typically water, may enter the inlet coolant box 106 through a cooling fluid inlet 116. The cooling fluid may then flow from the inlet coolant box 106 into a first bundle of tubes 118. After passing through the first bundle of tubes 118, the cooling fluid may enter the intermediate coolant box 110, pass through a second bundle of tubes 120, and enter the outlet coolant box 108. The cooling fluid may then exit the heat exchanger 100 through a cooling fluid outlet 122,

A hot fluid, typically steam, may enter the shell side 104 through a hot fluid inlet 124. The hot fluid may then pass around the baffles 114 and over the tubes 118 and 120 so as to exchange heat with the cooling fluid and condense. The condensed steam (water) may exit the heat exchanger 100 through a condensate outlet 126, and air and any remaining steam and may exit the heat exchanger 100 through a vapor outlet 128. Similar designs are known.

II. Heat Exchanger With Multiple Internal Diverters

Referring again to the drawings, FIG. 2 shows a partial cross-sectional side-view of one embodiment of a heat exchanger with multiple internal diverters 200 as described herein.

The heat exchanger 200 may include an inlet coolant box 202 and an outlet coolant box 204. The inlet coolant box 202 and the outlet coolant box 204 may be separated by a partition 206. The heat exchanger 200 also may have an end cover 208 for allowing access into the heat exchanger 200.

A cooling fluid, typically water, may enter the inlet coolant box 202 through a cooling fluid inlet 210. The cooling fluid may then flow from the inlet coolant box 202 through one or more bundles of tubes (not shown). After passing through the tubes, the cooling fluid may enter the outlet coolant box 204. The cooling fluid may then exit the heat exchanger 200 through a cooling fluid outlet 212.

The partition 206 may contain multiple internal diverting devices that divert flow within the heat exchanger. The diverting devices may comprise essentially any type of diverting device known in the art. Importantly, the range of flow rates over which each of the diverting devices operates is different then the range of flow rates over which the other diverting devices operate. Non-limiting examples of suitable diverting devices include flow control orifices, lift valves, and “flapper” style valves, in one embodiment, the diverting devices comprise “flapper” style valves that utilize a spring. The spring may counteract the pressure of the cooling fluid at low flow rates so as to keep the flapper closed, and my allow the flapper to open at high at high flow rates.

In a particular embodiment, the diverting devices may comprise a first lift valve 302 and a second lift valve 304. Details of the first lift valve 302 and the second lift valve 304 are illustrated in FIG. 3, which shows a partial cross sectional side view of the heat exchanger coolant box of FIG. 2. The first lift valve 302 may include a first lift disk 306, and the second lift valve 304 may include a second lift disk 308. The lift disks 306 and 308 may be positioned respectively over a first opening 310 and a second opening 312 in the partition 206.

Over a first lower range of flow rates, the first lift disk 306 may cover the first opening 310 so as to block the flow of fluid through the partition 206. Over a first high range of flow rates, the first lift disk 306 may move up a first guide rod 314 so as to allow fluid through the first opening 310 in the partition 206. Similarly, over a second lower range of flow rates, the second lift disk 308 may cover the second opening 312 so as to block the flow of fluid through the partition 206. Over a second high range of flow rates, the second lift disk 308 may move up a second guide rod 316 so as to allow fluid through the second opening 312 in the partition 206.

The range of flow rates over which the first lift valve 302 operates and the second lift valve 304 operates may differ due to the design of the lift valves. In a particular embodiment, the first lift disk 306 has a mass that is different than the mass of the second lift disk 308 so that the first lift disk 306 moves up the first guide rod 314 at ranges of flow that are different than the ranges of flow at which the second lift disk 308 moves up the second guide rod 316. In another embodiment, the first opening 310 has an area that is different than the area of the second opening 312 so that the first lift disk 306 moves up the first guide rod 314 at ranges of flow that are different than the ranges of flow at which the second lift disk 308 moves up the second guide rod 316. In yet another embodiment, the first lift disk 306 has a mass that is different than the mass of the second lift disk 308 and the first opening 310 has an area that is different than the area of the second opening 312 so that the first lift disk 306 moves up the first guide rod 314 at ranges of flow that are different than the ranges of flow at which the second lift disk 308 moves up the second guide rod 316.

The use of diverting devices that operate over different ranges of flow rates can provide significant advantages as compared to the use of diverting devices that operate over the same range of flow rates. For example, diverting devices that operate around the low end of the total range of flow rates may be completely open around the high end of the total range, resulting in uncontrolled flow rates through the heat exchanger at high levels of total flow rates. Likewise, diverting devices that operate around the high end of the total range of flow rates may be completely closed around the low end of the total range, resulting in uncontrolled flow rates through the heat exchanger at low levels of total flow rates. By using diverting devices that operate over different ranges of total flow rates, the amount of flow through the heat exchanger may be effectively controlled at the lower end of the total range by one diverting device, and the amount of flow through the heat exchanger may be effectively controlled at the upper end of the total range by a second diverting device, so that the rate of flow through the heat exchanger may be effectively controlled over a broad range of total flow rates.

The heat exchanger 200 may he used to exchange heat between a cooling fluid, typically water, and a hot fluid, typically steam. The method of exchanging heat may include feeding a cooling fluid into the cooling fluid inlet 210 of the inlet coolant box 202 at a total rate of flow, wherein the total rate of flow varies over time between a minimum and a maximum; diverting a first portion of the fluid with the first diverting device across the partition 206 and into the outlet coolant box 204 during periods of time when the total rate of flow is above a first rate of flow between the minimum and the maximum; diverting a second portion of the fluid with the second diverting device across the partition 206 and into the outlet coolant box 204 during periods of time when the total rate of flow is above a second rate of flow between the minimum and the maximum; passing a third portion of the fluid through the tubes (not shown) of heat exchanger 200 and into the outlet coolant box 204; and feeding the first portion, the second portion, and the third portion of the fluid through the cooling fluid outlet 212 of the outlet coolant box 204, wherein the first rate of flow is different than the second rate of flow. As a result, the first diverting device may divert fluid when the total rate of flow is above the first flow rate, the second diverting device may divert fluid when the total rate of flow is above the second flow rate, and both the first diverting device and the second diverting device may divert fluid when the total rate of flow is above the first flow rate and the second flow rate.

In those embodiments in which the first diverting device includes the first lift valve 302 and the second diverting device includes the second lift valve 304, the step of diverting the first portion of the fluid may include opening the first lift valve 302, and the step of diverting the second portion of the fluid may include opening the second lift valve 304. Furthermore, in those embodiments in which the first lift valve 302 includes the first lift disk 306 positioned over the first opening 310 in the partition 206 and the second lift valve 304 includes the second lift disk 308 positioned over the second opening 312 in the partition 206, the step of opening the first lift valve 302 may include lifting the first lift disk 306 off the first opening 310 in the partition 206, and the step of opening the second lift valve 304 may include lifting the second lift disk 308 off the second opening 312 in the partition 206.

It should be understood that the foregoing relates only to the preferred embodiments of the present application and that numerous changes and modifications may be made herein without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.

Claims

1. A heat exchanger comprising:

an inlet coolant box; and

an outlet coolant box;

wherein the inlet coolant box and the outlet coolant box are separated by a partition,

wherein the partition comprises a first diverting device and a second diverting device, and

wherein the range of flow rates over which the first diverting device diverts fluid is different then the range of flow rates over which the second diverting device diverts fluid.

2. The heat exchanger of claim 1, wherein the first diverting device comprises a first lift valve and the second diverting comprises a second lift valve.

3. The heat exchanger of claim 2, wherein the first lift valve comprises a first lift disk positioned over a first opening in the partition and the second lift valve comprises a second lift disk positioned over a second opening in the partition.

4. The heat exchanger of claim 3, wherein the first lift disk is mounted on a first guide rod and the second lift disk is mounted on a second guide rod.

5. The heat exchanger of claim 3, wherein the first lift disk comprises a first mass, and the second lift disk comprises a second mass.

6. The heat exchanger of claim 3, wherein the first opening comprises a first area, and die second opening comprises a second area.

7. The heat exchanger of claim 3, wherein the first lift disk comprises a first mass, the second lift disk comprises a second mass, the first opening comprises a first area, and the second opening comprises a second area.

8. A heat exchanger comprising:

an inlet coolant box; and

an outlet coolant box;

wherein the inlet coolant box and the outlet coolant box are separated by a partition,

wherein the partition comprises a first lift valve and a second lift valve,

wherein the first lift valve comprises a first lift disk positioned over a first opening in the partition and the second lift valve comprises a second lift disk positioned over a second opening in the partition, and

wherein the first lift disk comprises a first mass, and the second lift disk comprises a second mass.

9. The heat exchanger of claim 8, wherein the first lift disk is mounted on a first guide rod, and the second lift disk is mounted on a second guide rod.

10. The heat exchanger of claim 8, wherein the first opening comprises a first area, and the second opening comprises a second area.

11. A method of exchanging heat comprising:

providing a heat exchanger comprising an inlet coolant box and an outlet coolant box, wherein the inlet coolant box and the outlet coolant box are separated by a partition;

feeding a fluid into the inlet coolant box at a total rate of flow, wherein the total rate of flow varies over time between a minimum and a maximum;

diverting a first portion of the fluid across the partition and into the outlet coolant box during periods of time when the total rate of flow is above a first rate of flow between the minimum and the maximum; and

diverting a second portion of the fluid across the partition and into the outlet coolant box during periods of time when the total rate of flow is above a second rate of flow between the minimum and the maximum.

12. The method of claim 11,

wherein the step of diverting the first portion of the fluid comprises opening a first lift valve of a first diverting device; and

wherein the step of diverting the second portion of the fluid comprises opening a second lift valve of a second diverting device.

13. The method of claim 12,

wherein the first lift valve comprises a first lift disk positioned over a first opening in the partition and the second lift valve comprises a second lift disk positioned over a second opening in the partition;

wherein the step of opening the first lift valve comprises lifting the first lift disk off the first opening in the partition; and

wherein the step of opening the second lift valve comprises lifting the second lift disk off the second opening in the partition.

14. The method of claim 11,

wherein the first rate of flow is different than the second rate of flow.