US20090065181A1

US20090065181A1 - System and method for heat exchanger fluid handling with atmospheric tower

Info

Publication number: US20090065181A1
Application number: US11/851,892
Authority: US
Inventors: Eldon F. Mockry; Glenn S. Brenneke; Peter W. Falcone; Thomas M. Dendy
Original assignee: Selas Fluid Processing Corp; SPX Cooling Technologies Inc
Current assignee: SPX Cooling Technologies Inc; Linde Engineering North America Inc
Priority date: 2007-09-07
Filing date: 2007-09-07
Publication date: 2009-03-12
Also published as: CN101815918A; BRPI0816271A2; WO2009032682A1; CN101815918B

Abstract

A system connects fluid heat exchange devices such as a submerged combustion LNG vaporizer and a heating tower. The fluid handling system has a first heat exchange device having a first fluid inlet and a first fluid outlet, and a second heat exchange device having a second fluid inlet and a second fluid outlet. A first conduit connects the first fluid outlet to the second fluid inlet, a first reservoir receives fluid from the first fluid outlet, a second reservoir receives fluid from the second fluid outlet, a second conduit connects the second reservoir to the first fluid inlet; and a third, fluid equalization, conduit connected to the first reservoir and the second reservoir equalizes the fluid levels in the first and second reservoirs with each other.

Description

FIELD OF THE INVENTION

The invention pertains generally to the field of hydraulics and fluid handling. More particularly, the invention relates to a hydraulic system and method for handling fluids that are used in heat exchangers. More particularly, the invention pertains to a system for circulating heat exchange fluid between two heat exchange devices, where one device is an atmospheric heating or cooling tower.

BACKGROUND OF THE INVENTION

Heat exchangers are in wide use in industry. Many of these heat exchangers involve some form of circulating fluid. The fluid may be water, water treated with chemicals, or some other liquid. The words “water” and “fluid” are used interchangeably in this specification.
One type of heat exchanger is an atmospheric cooling tower. Such cooling towers are traditionally used in industrial applications to cool fluid that is supplied to the tower at a relatively warm temperature, i.e., above an ambient temperature, down to a relatively cooler temperature closer to the ambient temperature. Cooling towers in some cases involve the spraying of the warm fluid from the top of the tower, sometimes over a fill medium, and also in some instances using a fan to force air through the tower so that the water falls through the tower, contacting the fill medium and the air and falls into a collection basin at the bottom of the tower. As the warm fluid falls through the tower, it will generally be cooled to a cooler temperature. These are called open loop cooling towers because the fluid being cooled contacts the air. There are also closed loop towers where the fluid being cooled circulates through a closed coil in the tower, but another fluid is sprayed over the coil as discussed above. Also, dry cooling towers use only the coils and do not have the falling spray water. The details of these and other types of cooling towers are well known to those skilled in the art.
It is also possible to operate a cooling tower type structure to be a heating tower. In such circumstances where the fluid is supplied to the tower starting at a temperature cooler than the ambient air temperature, the supply of the cool fluid into the top of the tower will result in a warming of the fluid so that the fluid collected at the basin at the bottom of the tower is warmer than when it entered the tower.
It has generally been most common in industrial applications to utilize heat exchange towers as cooling towers. However, there are arising certain situations where a heating tower can be beneficial. One such situation is in the case of liquid natural gas (LNG) evaporators. In these evaporators, liquid natural gas is vaporized by the addition of heat. This can result in a supply of cold fluid which is desired to be warm.
Turning to a different aspect of LNG vaporization, there are some known heat exchangers for use in LNG vaporization. One example is a so-called open rack vaporizer. An open rack vaporizer is essentially a large water tank having a closed coil submerged in the tank. The LNG is passed through the closed coils. Water is drawn from a relatively warm external source, such as sea water, and is circulated into and through the tank. The LNG is warmed by the vaporization coil being in contact with the warm sea water. The water becomes cooled by contact with the vaporization coils and then is discharged, usually back into the sea. In some instances there are environmental limits on the use of these evaporators.
Another type of LNG evaporator is a shell and tube arrangement with the LNG in tubes that have a shell surrounding the tubes having warmer water passed through it.
Yet another type of LNG evaporator is a so-called submerged combustion vaporizer (SCV). An SCV is similar to an open rack vaporizer in that it is essentially a tank of water having the vaporization coils submerged therein. However, rather than circulating any water into and out of the tank in an SCV, heat is continually added by means of a gas fired burner submerged in the tank. The details of SCVs can vary, but in general the gas fired burner is operated so as to add heat into the water tank at substantially the same rate at which heat is being drawn out from the water by the vaporization coil. The amount of heat added by the submerged burner can be relatively steady, controlled by modulating the gas burn rate and using the water as a temperature change buffer. Although the water in the SCV is generally self-contained, there is some water produced in the combustion process and condensed out of the hot gas stream. It is removed to prevent flooding the burner, usually by an overflow outlet port.
Each of the methods described above is useful in industry and has various advantages. However, it would be desirable to have a heat exchange fluid handling system and method that provides in some instances a more controllable, energy efficient, or otherwise beneficial-to-operate arrangement.

SUMMARY OF THE INVENTION

The invention in one aspect pertains to a fluid handling system, comprising a first heat exchange device having a first fluid inlet and a first fluid outlet; a second heat exchange device having a second fluid inlet and a second fluid outlet; a first conduit connected to the first fluid outlet to the second fluid inlet; a first reservoir that receives fluid from the first fluid outlet; a second reservoir that receives fluid from the second fluid outlet; a second conduit connected to the second reservoir to the first fluid inlet; and a third, fluid equalization, conduit connected to the first reservoir to the second reservoir and equalizes the fluid levels in the first and second reservoirs with each other, further comprising a weir in fluid communication with the second fluid outlet, wherein the weir is disposed between the second fluid outlet and the second reservoir so the second reservoir receives fluid from the weir. The second heat exchange device comprises a liquefied natural gas (LNG) vaporizer.
Another aspect of the invention pertains to a fluid handling system, comprising an atmospheric heating tower having a first fluid inlet and a first fluid outlet; a submerged combustion vaporizer (SCV) having a second fluid inlet and a second fluid outlet; first means for connecting the first fluid outlet to the second fluid inlet; and second means for the second fluid outlet to the first fluid inlet.
Yet another aspect of the invention pertains to a fluid handling method, providing a first heat exchange device having a first fluid inlet and a first fluid outlet, a second heat exchange device having a second fluid inlet and a second fluid outlet, a first conduit connected to the first fluid outlet to the second fluid inlet, a first reservoir that receives fluid from the first fluid outlet, a second reservoir that receives fluid from the second fluid outlet, a second conduit that connects the second reservoir to the first fluid inlet, and equalizes the fluid levels in the first and second reservoirs with each other.
In another aspect of the invention, a fluid handling method comprises providing an atmospheric heating tower having a first fluid inlet and a first fluid outlet; a submerged combustion vaporizer (SCV) having a second fluid inlet and a second fluid outlet, circulating fluid from the first fluid outlet to the second fluid inlet, and circulating fluid from the second fluid outlet to the first fluid inlet.
There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a heat exchange system according to a first preferred embodiment.

FIG. 2 is a schematic diagram of a heat exchange system according to a second preferred embodiment.

DETAILED DESCRIPTION

FIG. 1 illustrates a system involving two heat exchangers which can be useful for several purposes. One useful purpose for this heat exchanger system is the vaporization of LNG. Although the vaporization of LNG will be used as an example throughout the specification, it will be appreciated that the system could be useful for the vaporization of other materials and for any other industrial or other operation where it is desired to add heat to a material. Also, although one example described below uses an atmospheric heating tower to add supplemental or entire heat to a LNG vaporizer such as an SCV, it will be appreciated that some aspects of the system can be used for an atmospheric cooling tower to provide supplemental or entire cooling to other individual systems.
Turning to FIG. 1, an SCV 10 is shown, which in this instance is for vaporization of LNG. This SCV 10 has a water inlet and water outlet so in addition to, or instead of, heat being supplied to the SCV coil via the SCV gas burner, heat can also be supplied to the coil by supplying warm water to the SCV 10, and drawing out cooler water. However, instead of an SCV, the arrangement could in some applications be a heat exchanger that adds heat. In this example, the SCV 10 includes an LNG vaporization coil 12 having a liquid gas inlet 14 and a vaporized outlet 16. LNG enters the coil at inlet 14 and heat is added to it so that the vaporized gas exits at outlet 16. The coil 12 is suspended within a tank 18 which is filled with water or another heat exchange fluid 20. One way of adding heat to the fluid 20 is the use of a gas combustion device 22, which may burn natural gas and other fuel. The combustion device 22 may provide hot flue gas via a flue 24 which may be provided beneath the coil 12 to conduct heat into the fluid 20, and also to exhaust hot gas bubbles over the coil 12, further adding heat to the material being vaporized.
In some conditions, the use of the combustion device 22 by itself may not be the most efficient way to add heat to the system. Therefore, in the embodiment of FIG. 1 an atmospheric heating tower 30 is also utilized. The heating tower 30 draws air in to a lower air inlet 32 and exhausts the air out of a fan-powered outlet 34. A pump 36, labeled P1, is provided to draw fluid out of the SCV 10 via a conduit 35 and pump it through a conduit 37 to a series of spray heads 38 near the top of the tower 30. The fluid thus drawn from the SCV is sprayed over a fill material 40 so that as it falls over the fill material 40 it contacts the air and has heat imparted to it. This will occur as long as the fluid drawn from the SCV 10 and being sprayed out the nozzles 38 is cooler than the ambient air.
After the fluid falls beneath the fill material 40, it is collected in a lower basin 42. The fluid in the lower basin 42, which is warmer than the fluid that was drawn from SCV 10, can now be supplied back to the SCV 10 using a conduit 43 and a pump 44, labeled P2. The pump 44 supplies the warmer fluid through a conduit 45 which may simply terminate into the SCV, or may distribute the warm water through a variety of outputs 46.
It will be appreciated depending upon atmospheric conditions and other conditions within the equipment, as well as factors such as gas cost, it may be desirable sometimes to operate only with the heating tower, for example, if the ambient air is extremely warm and the heating tower is scaled so that it can add enough heat for vaporization. However, due to climactic changes, or other design factors, it may be desirable to operate the SCV part of the time. It is possible to control and modulate the SCV, as well as the heating tower, to operate both of them to supply heat at the same time and at different rates, or to operate only one or the other of the heating tower and the SCV. In this way, use of fuel can be reduced, and other operating efficiencies can be obtained.
In the example shown in FIG. 1, the pumps 36 and 44 are operated at substantially the same flow rate so that the fluid is basically pumped in a cycle out of the SCV towards the heating tower, and then back from the heating tower back into the SCV. This is a first embodiment. However, one aspect of this system is that in most conditions the atmospheric heating tower will actually generate additional fluid in the form of water due to condensation that occurs in the tower. Therefore, some provision can be provided, such as an overflow discharge port 50 provided at a maximum desired fluid level of the basin 42. An overflow discharge port 52 can similarly be provided in the SCV 10.
The system described in FIG. 1 does have some possible disadvantages. For example, if the pump 44 fails, or if the conduits associated with pump 44 fail, it is possible that the re-supply of fluid back into the SCV 10 could be reduced or blocked entirely. In such a case, if the pump 36 continues to run, it is possible that water will continue to be pumped out of the SCV 10 and the SCV 10 could be “run dry” or at least partially dry. This condition can be undesirable. The water that is pumped out from the SCV 10 by the pump 36 would be added into the heating tower, but would fall into the basin 42 as overflow and be discharged out the overflow discharge port 50.
Another possible undesirable condition is if pump 36 fails. In such a case, it is possible that the pump 44 will feed excess water into the SCV 10 which is not removed, which could in some instances “swamp” the SCV burner.
Depending on the relative installation height of the SCV 10 and the heating tower 30, it may be possible to operate a system using only one pump (pump 36), if the heating tower were installed high enough that its head distance could provide the function presently shown by the pump 44. However, in most practical installations it is expected that a two pump system would be more desirable.
It can some times be desirable to have a system that would maintain the operating fluid levels at desired levels where a first heat exchanger (such as an SCV, for example) is connected to a second heat exchanger (such as a heating tower, for example). It can also some times be desirable to accommodate the failure of the pumps that are running in either direction from one device to another. It is noticed that while the examples of an SCV and an atmospheric heating tower are given, the systems described herein could be applied to any types of heat exchangers that involve the addition and removal of fluid from the heat exchangers to provide fluid communication between the heat exchangers, with at least one of the heat exchangers having a fluid level that is vented to the atmospheric pressure.
Turning now to FIG. 2, a second embodiment of an improved fluid handling system is shown in which reference numerals in FIG. 2 depict like components as in FIG. 1. Continuing with FIG. 2, the SCV 10 is shown having a fluid 20 at an operating level L1. As discussed above, it is typically desirable to have L1 to be maintained in a range so that it is not too high such that it would swamp the burner, and not too low such that it would fail to add heat to the coils, which could lead to coil freezing or other undesirable situations.
Somewhat similar to the embodiment of FIG. 1, the heating tower 30 can be connected to the SCV 10 such that the heating tower 30 can supply warmed water to the SCV. In the case of such a supply, L1 will raise to a level and fluid will exit the SCV via a main outlet port 60, which may have a valve associated therewith. The exiting fluid flows from the main outlet port 60 into a holding weir 62. Should the valve associated with the port 60 be closed, or should the increase in the fluid level L1 become greater than handled by the outlet 60, as the fluid level L1 raises, it will reach an overflow port 64. Upon reaching the height of the overflow port 64, fluid will exit the SCV and also enter the weir 62. This provides a beneficial feature by which the fluid level in the SCV will not swamp the burner.
The weir chamber 62 has a sidewall 66, and as the level in the weir chamber 62 exceeds the height of the sidewall 66, the fluid will further be transferred into a buffer tank 68. A conduit 35 for drawing water out of the holding reservoir 68 leads to the pump 36 which pumps the fluid through conduit 37 and up to the nozzles 38 in the heating tower.
The fluid is passed over the fill medium 40 and falls into the basin 42. Fluid is drawn from the basin 42 out by the pump 44 via conduit 43 and is supplied back to the SCV through the supply openings 46. Should the rate of supply of water into the basin 42 exceed the rate of the withdrawal of fluid from the basin 42, the level L2 of the basin fluid will increase. Should the level L2 of the basin fluid exceed a predetermined level, basin fluid will flow into a holding reservoir 70 as shown.
The holding reservoir 70 is in fluid communication with the holding reservoir 68 via a flow equalization pipe 72. Thus, the level L3 of the holding reservoir 70 will generally stay substantially equal to the level L4 of the holding reservoir 68. In this way, if either the heat exchanger basin 42 or the SCV fluid 20 is receiving an oversupply of fluid, the oversupply of fluid is deposited into the holding reservoirs 68 and 70, where they will equalize. Since the pump 36 draws from conduit 35 which is in fluid communication with both holding reservoirs 68 and 70, some fluid will always be available to be pumped into the heating tower.
As has been noted above, in some instances the heating tower will add water to the system via condensation. Thus, the additional water will overflow into the holding reservoirs 68 and 70, causing L3 and L4 to increase. A single overflow bleed device 80 can be provided at either the holding reservoirs 68 or 70. In the example shown, the overflow bleed device 80 is provided on the reservoir 68 such that when L4 reaches a suitably high level, the excess fluid will be removed. The height of the bleed device 80 will generally be less than a wall 82 that defines a side of the reservoir 70 and a wall 84 that defines a height of the weir chamber 62. Thus, the two separate overflow discharges such as 50 and 52 in FIG. 1 are not reached. However, for redundancy in case of blockage of the flow equalization pipe 72, an additional overflow discharge (not shown) can be added to holding reservoir 70.
A benefit of the arrangement illustrated in FIG. 2 is that in the case of a failure of either of the pumps 36 and 40, by virtue of the flow equalization pipe 72, the problems of swamping the burner, emptying the SCV or draining of the whole system can be avoided. For example, if pump 36 fails, pump 44 will draw water out of the basin 42 and supply it to the SCV 10. However, all the water that is added to the SCV 10 will exit via the outlet tube 64 and main port 60 to avoid an overflow, and will enter the weir 62 and the reservoir 68, and by virtue of the flow equalization pipe 72 the levels L3 and L4 will rise together. As the level L3 reaches the height of the port 43, the water will be fed directly to the basin 42 and continue to re-circulate as described above. In such a system, the heating tower will not be adding heat to the water, but essentially a short circuit is created such that water is not lost and the SCV can continue to operate on its own.
In the case of a failure of pump 44, pump 36 will withdraw fluid from the reservoir 68 and pump it through the cooling tower 30. Since pump 44 is inoperative, the fluid in the basin will rise such that it exits the weir 41 and enters the reservoir 70, traveling through the flow equalization pipe 72 back to the reservoir 68. In this case, another short circuit is provided where the heating tower will operate but will not be interacting in any way with the SCV. Thus, the SCV can continue to operate on its own.
Valves 90 and 92 can be provided as shown so that the SCV 10 can be isolated from the heating tower when desired. The valve at the outlet port 60 may also be closed in connection with this.
In the illustrated embodiment of FIG. 2, it will be appreciated that the levels L4 and L3 will tend to stay equalized with each other due to the flow equalization pipe 72. The reservoir 68 is depicted as being essentially attached to the SCV 10, and the reservoir 70 as essentially attached to the cooling tower 30. However, when the terrain of installation requires that the cooling tower be of a substantially different elevation from the SCV, then suitable plumbing modifications can be made so that these reservoirs can exist at the same height.
Similarly, in the illustration of FIG. 2, the levels L1 and L2 are shown as being substantially the same. However, again, where the cooling tower 30 is installed at a substantially different elevation than the SCV 10, these levels do not need to be the same as each other. Rather, suitable plumbing can be implemented to connect to the reservoirs to their respective heat exchange devices.
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims

1. A fluid handling system, comprising:

a first heat exchange device comprising an atmospheric heat exchange tower having a first fluid inlet and a first fluid outlet;

a second heat exchange device having a second fluid inlet and a second fluid outlet;

a first conduit connected to the first fluid outlet to the second fluid inlet;

a first reservoir that receives fluid from the first fluid outlet;

a second reservoir that receives fluid from the second fluid outlet;

a second conduit connected to the second reservoir to the first fluid inlet; and

a third, fluid equalization, conduit connected to the first reservoir to the second reservoir and equalizes the fluid levels in the first and second reservoirs with each other.

2. The system of claim 1, wherein the first heat exchange device comprises an atmospheric heating tower.

3. The system of claim 1, wherein the second heat exchange device comprises a liquefied natural gas (LNG) vaporizer.

4. The system of claim 2, wherein the second heat exchange device comprises a liquefied natural gas (LNG) vaporizer.

5. The system of claim 1, wherein the second heat exchange device is a submerged combustion vaporizer (SCV).

6. The system of claim 2, wherein the second heat exchanger is a submerged combustion vaporizer (SCV).

7. The system of claim 1, further comprising a weir in fluid communication with the second fluid outlet, wherein the weir is disposed between the second fluid outlet and the second reservoir so the second reservoir receives fluid from the weir.

8. A fluid handling system, comprising:

an atmospheric heating tower having a first fluid inlet and a first fluid outlet;

a submerged combustion vaporizer (SCV) having a second fluid inlet and a second fluid outlet;

a first fluid connection connecting the first fluid outlet to the second fluid inlet; and

a second fluid connection that connects the second fluid outlet to the first fluid inlet.

9. The system of claim 8, further comprising at least one pump that circulates fluid between the heating tower and the SCV.

10. A fluid handling system, comprising:

first heat exchanging means having a first fluid inlet and a first fluid outlet;

second heat exchanging means having a second fluid inlet and a second fluid outlet;

first connecting means for connecting the first fluid outlet to the second fluid inlet;

first holding means that that receives fluid from the first fluid outlet;

second holding means that receives fluid from the second fluid outlet;

second connecting means for connecting the second reservoir to the first fluid inlet; and

fluid level equalizing means for equalizing the fluid levels in the first and second holding means with each other.

11. The system of claim 10, wherein the first heat exchanging means comprises an atmospheric heating tower.

12. The system of claim 10, wherein the second heat exchanging means comprises a liquefied natural gas (LNG) vaporizer.

13. The system of claim 11, wherein the second heat exchanging means comprises a liquefied natural gas (LNG) vaporizer.

14. The system of claim 10, wherein the second heat exchanging means is a submerged combustion vaporizer (SCV).

15. The system of claim 11, wherein the second heat exchanging means is a submerged combustion vaporizer (SCV).

16. The system of claim 10, further comprising a third holding means in fluid communication with the second fluid outlet, wherein the third holding means is disposed between the second fluid outlet and the second holding means so the second holding means receives fluid from the third holding means.

17. A fluid handling system, comprising:

first means for connecting the first fluid outlet to the second fluid inlet; and

second means for connecting that connects the second fluid outlet to the first fluid inlet.

18. The system of claim 17, further comprising at least one pump that circulates fluid between the heating tower and the SCV.

19. A fluid handling method, comprising:

providing a first heat exchange device comprising an atmospheric heat exchange tower having a first fluid inlet and a first fluid outlet, a second heat exchange device having a second fluid inlet and a second fluid outlet, a first conduit connected to the first fluid outlet to the second fluid inlet, a first reservoir that receives fluid from the first fluid outlet, a second reservoir that receives fluid from the second fluid outlet; a second conduit that connects the second reservoir to the first fluid inlet, and

equalizing the fluid levels in the first and second reservoirs with each other.

20. A fluid handling method, comprising:

providing an atmospheric heating tower having a first fluid inlet and a first fluid outlet, and a submerged combustion vaporizer (SCV) having a second fluid inlet and a second fluid outlet;

circulating fluid from the first fluid outlet to the second fluid inlet; and

circulating fluid from the second fluid outlet to the first fluid inlet.