US3847174A

US3847174A - Radiant heat absorber

Info

Publication number: US3847174A
Application number: US00336403A
Authority: US
Inventors: F Doyle
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-02-28
Filing date: 1973-02-28
Publication date: 1974-11-12
Anticipated expiration: 1991-11-12

Abstract

An apparatus for reducing the consequence of the Joule-Thompson effect when gas is expanded wherein pipes carrying the low pressure gas after expansion through the regulator are exposed to controlled ambient conditions to define a source of heat thereto and to prevent ice formation on piping and equipment downstream of the regulator.

Description

United States Patent Doyle Nov. 12, 1974 RADIANT HEAT ABSORBER 2.446.498 8/1948 Underwood 137/338 xv 3.023.776 3/1962 Franz i 137/334 X [761 lnvemor- Frank Doyle, Raymond 3351,7313 11 1967 Kuhn 137 341 x 62560 3410286 11/1968 Satuke 1 137/341 x 1423.570 1/1969 Trabilcy 137/341 X [22] 1973 3714.960 2/1973 Yumada 137 341 [21} Appl. N0.: 336,403

Primary E.\'aminerHenry T. Klinksiek .[52] U.S. Cl. 137/334 [511 1111.01. F16k 49/00 [57] ABSTRACT [58] Field 61 Search 137/334, 335, 336, 337, An apparatus for reducmg the COnsequenCe 9f the 137/338, 339, 340, 341 Joule-Thompson effect when gas is expanded wherein pipes carrying the low pressure gas after expansion 5 References Cited through the regulator are exposed to controlled ambi- UNITED STATES PATENTS ent conditions to define a source of heat thereto and 7 H8 869 5/1939 S I [37/334 X to prevent ice formation on piping and equipment perze 1.709.396 4/1929 Granger 137/336 x downstream of the regulator 31816654 11/1939 Davenport 137/335 X 9 Claims, 7 Drawing Figures PATENTEU NOV 12 I874 SHEH 1 OF 3 'FIGJA FIGJ PATENIED um 12 1924 sum a or 3 Fl G.3A

MENTEUHUV 12 I914 SHEEI 30F 3 FIG.4

RADIANT HEAT ABSORBER The present invention relates to an improved means for elimination of ice and freeze-up in regulator stations employed in the transmission of gas and particularly to apparatus to control conditions on the discharge side of a regulator valve associated with the transmission of gases and liquids and on the piping associated therewith.

The concept disclosed herein relates to a device for use in regulating stations associated with the transmission of natural gas, or the like. It is commonly known that various gases and liquids, including natural gas, are transported along pipe lines that extend from gas fields in the south and southwest portionsof the United States to the consumer area. Some consumer areas, of course, are located in northern latitudes where it is common to have a relatively low ambient temperature during substantial portions of the year.

The transmission of gases and liquids in the manner, noted above requires that the flow be regulated at various distributing points to provide gas to the consuming area at these points at the appropriate pressure level and to provide means to determine the volume of gas used in the particular consuming area. It is economically essential to provide simple means for regulating the flow and measuring the consumption of such gases and liquids and to provide means which require a minimum of attention so that the labor cost involved in monitoring such systems will be minimized.

Gas pressure regulators of the type set forth in my US. Pat. No. 3,103,951 do result in a significant reduction in the cost of operation in view of the fact that they do not require monitoring or attention of the type characteristic of other regulators. One problem that arises with ordinary regulators employed along such transmission lines is that ice commonly forms on the piping, valves, meters and other apparatus on the down-stream side of the valve and so-called freeze up may occur in the regulator as a result of moisture in the gas freezing before expansion due to reduced temperature levels in the valve or regulator body. It is commonly known that natural gas is not a perfect gas, as such, and therefore it does not regain its before expansion temperature when it exits from the high velocity port of the throttling orifice of the regulator.

In passing a gas at high pressure through a small aperture a difference of temperature between the compressed and the released gas occurs. This phenomenon is called the Joule-Thompson effect. At temperatures below the inversion temperature of a particular gas the type of expansion noted here results in a cooling of the gas.

The amount of cooling which occurs because of the expansion of gas through the regulator may be significant. For example, in one installation the inlet temperature of the gas was measured at 4091 which, in that installation, represented the ground temperature of the pipe below the frost line as measured during the winter. The gas pressure was approximately 700 pounds per square inch. The gas then was passed through the regulator and expanded to a pressure of 90 psig. The resultant temperature varied from 4 F. to F. in the discharge pipe. With a gas flow varying from 17,500 cubic feet per hour to 58,000 cubic feet per hour the discharge pipe and regulator quickly assume the temperature of the gas at the discharge side.

When the dew point of the ambient atmosphere is above the temperature of the discharge pipe, vapor from the atmosphere will form ice on the discharge pipe, manual valve, meter and other apparatus. It should be noted, of course, that during the warmer months water will simply condense into liquid form on the apparatus rather than freezing and the icing problem may not occur during the summer depending, of course, upon ambient conditions.

The freezing condition occuring at the regulating stations presently is controlled by burning some of the gas being transmitted through the lines at said stations to prevent the regulators from freezing; That is, the gas is burned in appropriate heating devices to pre-heat the gas before expansion through the regulator and to elevate the gas to a temperature where it will be above the dew point of the ambient atmosphere after expansion. 1 have found that-it takes substantially less heat to prevent formation of ice at the low pressure side of the regulator and apparatus.

In one form of my inventive concept 1 have provided a radiant heat absorber with the discharge pipes of tubes arranged within an enclosed portion in a horizontal direction and displaced with respect to each other so that condensate from the tubes will not drip on the tube below but, rather will fall to the bottom of the reflective plate of the absorber.

I discovered a surprising result in that it was not essential to heat the gas within the tubes to a temperature above 32 F (freezing point of water to avoid formation of ice on the gas line). It was necessary only to heat the gas to a temperature which would bring it above the dew point of the atmosphere. For example, at a dry bulb temperature of minus 15 F. (atmospheric temperature) the dew point usually is at some lower temperature. Accordingly, it is not necessary to heat the gas to a temperature as high as 32 F. when the dew point is substantially lower. It is necessary only to heat the low pressure gas line to a temperature somewhat above the dew point without reference to the freezing temperature of water. This, of course, may significantly reduce the amount of heat which must be supplied to the radiant heat absorber, thereby reducing gas consumption in the burners of the absorber.

The radiant heat units contemplated in the apparatus disclosed herein operate at 3% inches of water pressure and in this manner it is possible to connect the vent of the relay as shown in my U.S. Pat. No.

3,247,865, for example, to the supply pipe of the heaters. Normally, the gas escaping from this vent is exhausted to atmosphere. With the present concept it is possible to utilize this vent gas as a portion of the fuel for the heaters.

In another form of the inventive concept disclosed herein the radiant heat absorberis arranged so that all sides of the tubes are exposeddirectly to a source of radiant heat. In thisform the tubes may-be arranged in any desired manner, including a stacked array with the tubes disposed one above the other. The advantage of this arrangement is that the overall dimension of the tube array will be relatively small and, therefore, more economical to construct.

As noted above, the present invention is directed to the provision of a radiant heat absorber intended to eliminate ice formation and accumulation on the downstream side of the regulator valve associated with socalled-border stations in transmission of gases and liquids along continental pipe lines thereby avoiding the problems associated with icing on the exit side of the regulator after the gas being transmitted, for example, goes through expansion.

It is, accordingly, a primary object of the present invention to provide a radiant heat absorber to eliminate the icing effect commonly occuring at regulating sta- ,tions associated with the continental transmission gases.

Other objects and advantages of the present invention reside in the provision of a radiant heat absorber for use in eliminating icing at the regulating stations for transmission of gases wherein the device avoids the accumulation of ice on the exit side of the regulator and the pipes, meter, and other apparatus associated therewith on the exit side thereof; which is economical to manufacture; which is economical to use particularly in the design characteristic which permits the heat absorber to utilize gases otherwise vented to atmosphere as a portion of the fuel for generation of the heat required by the absorber; which is automatic in operation and therefore does not require constant monitoring; and which is readily adapted to use in present installations;

The novel features which are believed to be characteristic of the invention are set forth in the appended claims. The invention itself, however, together with additional objects and advantages thereof may best be understood by reference to the following detailed description taken in connection with the drawings, in which:

FIG. 1 is a schematic representation of the radiant heat absorber of the present invention showing some means as installed in an appropriate shelter;

FIG. 1A is a side view of the schematic illustration of the FIG. 1;

FIG. 2 is a fragmentary side elevation of the radiant heat absorber of the present invention showing the installation with end plates and tubes in assembled relation but without the heater and reflector plates associated therewith;

FIG. 2A is an end view schematically representing the absorber disclosed herein and showing the heater and reflector elements in association with the tube array of the absorber;

FIG. 3 is a side elevation showing in fragmentary form .a modified version of the absorber disclosed herein with the tubes being arranged in stacked arrays in the heat absorber and between the end plates thereof;

FIG. 3A is an end view of the absorber modification illustrated in FIG. 3; and

FIG. 4 is a schematic station installation showing a piping arrangement and associated apparatus including the concept set forth herein.

Referring more particularly now to the drawings the radiant heat absorber 10, expansion valve V and shelter S are schematically illustrated in FIGS. 1 and 1A. The shelter S may be provided for the absorber installation to define means for more economical operation of the device in that it will protect the installation from heat loss to the atmosphere. Additionally; the so-called green house effect may be used to advantage in utilizing solar radiation to heat the interior of the shelter -S during daylight hours.

A shelter of the type employed with the installation disclosed herein may be approximately 8 feet square.

The height of the shelter, of course, will be sufficient to permit an average size individual to move about in a normal upright stance. The 8 X 8 dimension of the shelter S provides an area sufficiently large to accommodate the radiant heat absorber apparatus 10 and auxiliary apparatus associated with the station.

It should be observed that the shelter S noted above is not a required element of the installation. The radiant heat absorber disclosed herein will function without use of the shelter but it must be recognized that the operation cannot be as economical or efficient as it would be when placed within such a shelter. The shelter itself, of course, forms no part of the inventive concept disclosed herein.

As a practical matter the shelter should be built with a flat roof sloping toward the North, with North being indicated to the left in FIG. 1A as the shelter is schematically represented there. An overhang would be defined on the South wall of the shelter S for the absorber. This would define a structure which would naturally avoid the build-up of icicles on the structure and provide for more efficient operation of the installation. The radiant heat absorber 10 would be mounted approximately 4 feet above the base of the shelter to provide adaquate clearance below for discharge of condensate and for ease of installation and maintenance.

The radiant heat absorber is illustrated generally at 10 in FIGS. 1, 2 and 2A. The absorber 10 is defined, in part, by a plurality of tubes 12 disposed with in the absorber in a staggered array and arranged such that condensate dripping from the bottom of any tube in the array will not drop on any tube below that tube in that array. In the particular configuration illustrated in FIGS. 2 and 2A, the tubes 12 are arranged in an inverted V configuration to define the off-set interrelationship of the tubes, as noted above. Heater elements are mounted along either side of the tube array and extend laterally of the tubes in spaced relation to the outer perimeter thereof and generally along the longitudinal axis of the tubes, as illustrated in FIG. 2A. The heater elements 14 (and tube array) are enclosed by a suitable insulating material 16 so that heat is not radiated from the back of the heaters 14 away from the tubes 12 but rather is directed inwardly toward the tubes. An outer shell 18 may be provided on the outer It can readily be seen from FIG. 2A that when the heaters 14 are operative, radiant heat from the burners will be directed toward the tubes 12 in the V-shaped array to cause the tubes and the gas passing therethrough to be heated in accordance with the B.T.U. output of the heaters 14. One side of the tubes will be heated directly by the radiant heaters 14 while the other sides of the tubes 12 will be heated by reflection of heat energy from the reflector plates 20 of the array. The insulating

bodies

16 and 22 are provided in the assembly to avoid heat loss and to provide for more efficient operation of the assembly.

A vent 24, which in the illustrated embodiment of the inventive concept is approximately 2 inches in diameter, is provided in the top of the assembly to permit the products of combustion emanating from the heaters 14 to be discharged to atmosphere.

The bottom of the legs defined by the inverted V- shaped configuration of the tube array and heater assembly are open as indicated at 26 and 28. During operation of the assembly the heaters 14 will, of course, be'operating to burn fuel supplied to the heaters and to generate heat for use in the assemblypThe heat emanating from the heaters 14 will elevate the temperature of the tubes 12. The control condition of this operation, as noted above, requires that the temperature of the tubes be raised to a level above the dew point of the atmosphere to prevent accumulation of ice on the tubes and on the discharge side of'the expansion valve and the apparatus associated therewith. As indicated above, the gas flow through the exhaust tubes associated with the expansion valve in one particular installation varied from 17,500 cubic feet per hour to 58,000 cubic feet per hour. It can readily be appreciated that cold gas moving through the exhaust tubes 12 at this rate will be capable of absorbing a significant amount of heat from the surrounding apparatus or the devices within which the gas is contained. The gas pressure before the expansion valve may be around 700 pounds per square inch and is expanded to a pressure of approximately 90 psig. This gives rise, because of the Joule-Thompson effect, to a significant drop in temperature of the gas because it is not a perfect gas and the substantial cooling may give rise to problems of the type noted above.

A body, whether it be gas, solid or liquid tends to stabilize with respect to the conditions surrounding that body. That is, two bodies ofliquid situated at differend levels, if-inter-connected, will stabilize so that they eventually will be at the same level and thereby reach a static condition. Likewise, a given body at one temperature when placed in an atmosphere at another temperature will tend to give up or absorb heat from its new environment until it stabilizes at a temperature level which is the same as its new environment. When the bodies are equalized, with respect to. temperature,

they achieve a static condition and further energy exchange between them is indicental in character.

ln like manner, the highly cooled gases after expansion tend to rapidly extract heat from the exhaust port of the expansion valve, heaters, exhaust piping and other apparatus associated with the regulator assembly. The large volume of gas and rate of gas flow will, of course, constantly bring cooled gases into contact with the apparatus noted above and will constantly be extracting heat energy from the apparatus to move toward a stabilized condition where the two bodies will be at the same temperature. This heat loss must be compensated or eventually the surface temperature of the valve, meter, pipes, and the like, will be depressed to a point where they will be below the dew point condition of the surrounding atmosphere. If the temperature becomes depressed to a point where it is below the dew point of the atmosphere condensation and freezing then will occur on the apparatus and the icing condition which is objectionable in unattended stations will occur. The character and amount of freezing in some instances may completely encompass the piping and other devices at the station thereby creating problems in valve operation if an emergency should occur which would require access to the apparatus at the station. It can readily be seen that this can give rise to a vary serious situation. This condition, of course, is one which the apparatus disclosed herein is intended to eliminate.

As noted above, some devices have been provided wherein heat is added at regulating stations to avoid the freeze-up characteristic of the condition noted above. However, all of these installations have involved the addition of heat energy to the gas and apparatus prior to the time of expansion and when the gas in its high pressure condition. The addition of heat at this point in the apparatus and processing must be substantially large to elevate the gas temperature to a level where it will not be cooled after expansion to a point below the dew point of the atmosphere in which the apparatus exists. I have found that heating of the apparatus (and gas) after expansion is much less demanding in that less heat energy is required to maintain the apparatus at a temperature above the dewpoint of the existing atmospheric conditions to thereby avoid condensation of vapor and accumulation of ice. Surprisingly, I also observed that it was not necessary to maintain the apparatus at a temperature above 32 F. in order to avoid ice accumulation on the gas line extending from the absorber. It is necessary only to heat the apparatus and gas above the dew point of the atmosphere. This, of course, significantly reduces the amount of heat energy which must be supplied to the radiant heat absorber and thereby reduces gas consumption making the operation more efficient.

A tube sheet 30 is provided at either end of the absorber assembly and defines protection for the manifold extending from the flanged connections 32 into the tube array 12 and also for the ends of the absorber assembly itself. The tube sheet is approximately 24 inches in diameter and approximately l- /2 inches thick in the illustrative form of the absorber disclosed herein. The tubes 12 in the form disclosed are approximately 2 inches in diameter and are mounted on 4 inch axial spacings in the V-shaped staggered configuration illustrated in FIG. 2A. This provides a spacing from tubeto-tube of one tube diameter which provides for radiation of heat to the reflector plate to prevent ice buildup on the sides of 'the tubes 12 away from the heaters 14 by re-radiation of heat from the reflector plates 20 to the opposite sides of the tubes 12.

A modified form of the absorber assembly disclosed in FIGS. 2 and 2A is schematically illustrated in FIGS. 3 and 3A of the drawings. As shown, the modified form involves a tube array which is vertically aligned so that the tubes 12 are vertically stacked in the absorber 10'. The tubes 12 are 2 inches in diameter and are mounted within the absorber on 4 inch axial spacings. The tubes 12 are provided with a core defining a helix guide 32 for passage of material therethrough. This particular configuration forms no part of the present inventive concept except in combination with the apparatus illustrated herein.

As illustrated in FIGS. 3 and 3A, the modified form of the absorber assembly is defined in a generally rectangular condiguration with the heater units 34 being disposed vertically along either side of the tube array and extending laterally along the tubes in a direction generally coplanar with the longitudinal axis of the tube in the array. An insulating body 36 enclosed the top, sides and a part of the bottom of the absorber to prevent heat loss from the absorber in a direction away from the tube array. The absorber is open at the bottom as illustrated at 38 to permit condensate to be discharged from the absorber to the area below the absorber. A reflector plate 40 is provided at the top of the absorber to re-direct heat energy down toward the tubes 12. A vent 42 is provided at the top of the absorber to permit products of combustion to be discharged from the absorber through the vent.

Tube sheets 44 are provided at either end of the absorber assembly to encapsule the manifold extending from the flanged connections 46 to the absorber and to enclose the ends of the absorber for protection thereof. The tube sheets are approximately 7 inches by inches and 1 inch thick in the illustrative embodiment set forth in the drawings and disclosed herein. The general construction of the absorber assembly illustrated in.

FIGS. 3 and 3A is less expensive in that vertical tube arrays are used and a thinner and smaller tube sheet is employed at either end of the assembly. Also, it will be noted that the reflector plates in the central portion of the assembly illustrated in FIGS. 2 and 2A is eliminated and the heat loss through the insulation backing 22 of the reflector plates 20 is likewise eliminated. The tubes 12 are heated around the entire periphery in-view of the fact that they are exposed to burners or heaters 34 on either side thereof. The spacing of the tubes in the staggered linear array as illustrated in FIG. 3A is such that all tube surfaces are exposed to a heat source to give rise to a condition where the tube surfaces may be heated to a level above the dew point of the atmosphere in which the assembly is mounted.

Referring more particularly now to the schematic illustration of FIG. 4, the piping installation for the station is represented for ease in description of the environment in which the radiant heat absorber of the present invention is employed. 7

The high pressure line 50 from the transmission line extends through the shut-off valve 52 t0 the regulator 54 where the gas is expanded and the pressure reduced, as noted in detail hereinabove. The expanded gas then is passed through the line 54 to the manifold and into the radiant heat absorber 10, the modification represented in FIGS. 3 and 3A. The heated and expanded gases then exit from the absorber 10' to the transmission line 56 to consuming areas.

When the ambient dew point is at the levels noted hereinabove, ice formation will occur on the regulator 54 at the bottom thereon and at the intake manifold to the absorber 10'. The bottom portion of the regulator 54, of course, is the position where the gas has already been expanded and cooled and is discharged from the regulator. The body of the valve at this area quickly assumes the temperature of the expanded gases and ice formation can occur under proper conditions.

The installation represented in FIG. 4 includes a stand-by regulator 60 in the event problems occur in use of the regulator 54 wherein the expanded gases will by -pass the absorber and be transmitted to the consuming areas as required. This, of course, involves a safety condition and not one normally in use in that the gases are shunted past the absorber 10 and freeze up may occur under the proper atmospheric conditions.

While a specific embodiment of the present invention is shown and described it will, of course, be understood that other modifications and alternative constructions may be used without departing from the true spirit and scope of the invention. It is intended by the appended claims to cover all such modifications and alternative constructions as fall within their true spirit and scope.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A radiant heat absorber apparatus for use in regulating stations associated with transmission of gases, or the like, wherein condensation and freezing of water vapor occurs on devices employed to regulate said gas flow, which freezing impairs the operation or maintenance of said stations, the apparatus comprosing, in combination:

an array of conduits extending from the discharge orifice of the throttling device associated with said regulating station, said conduits having sufficient capacity to handle the maximum design flow of said regulating device, said array of conduits being placed in ordered, spaced apart relation with respect to each other;

an enclosure extending about said array of conduits,

the enclosure having side and top closures and being open at the bottom thereof; and

heating means associated with said enclosure and disposed about said array of conduits to supply heat energy to said conduits, said heating means being arranged in association with the conduits such that all portions of the conduits are exposed to heat energy to elevate the temperature of the conduits in controlled manner to a level above the dew point of the atmosphere in which the apparatus is operating whereby the temperature of the conduits is s uf ficiently high to avoid accumulation of frozen condensate thereon and wherein the condensate, if

formed, is maintained in liquid condition to drop from the conduits through the open bottom of the enclosure.

2. The apparatus of claim 1 wherein the array of conduits is arranged in a generally inverted V-shaped configuration with the conduits being vertically staggered so that condensate dropping from one conduit will not fall upon the conduits below it.

3. The apparatus of claim 2 wherein the enclosure is defined by an outer wall extending along each outer portion of the \/-shaped array of conduits to define a generally V-shaped inverted outer enclosure.

4. The apparatus of claim 3 wherein the heating means is disposed within the outer enclosure and is adapted to directly heat the walls of the conduits exposed thereto.

5. The apparatus of claim 3 wherein a reflecting surface is defined along the inner walls of the V-shaped conduit array and in spaced relation to the conduits I and the outer enclosure to reflect heat from the heating means back toward the conduits on the sides thereof away from the heating means.

6. The apparatus of claim 1 wherein the array of conduits is vertically aligned in a stacked array.

7. The apparatus of claim 6 wherein the enclosure extends about the top and sides of the aligned array in substantially uniformly spaced relation thereto;

8. The apparatus of claim 7 wherein the array of conduits is disposed in spaced apart vertically aligned of the enclosure whereby heat energy emanating from the heating means will directly impinge upon all conduit surfaces to elevate the temperature of the conduits in controlled manner to a level above the dew point of the atmosphere in which the apparatus is operating.

Claims

1. A radiant heat absorber apparatus for use in regulating stations associated with transmission of gases, or the like, wherein condensation and freezing of water vapor occurs on devices employed to regulate said gas flow, which freezing impairs the operation or maintenance of said stations, the apparatus comprosing, in combination: an array of conduits extending from the discharge orifice of the throttling device associated with said regulating station, said conduits having sufficient capacity to handle the maximum design flow of said regulating device, said array of conduits being placed in ordered, spaced apart relation with respect to each other; an enclosure extending about said array of conduits, the enclosure having side and top closures and being open at the bottom thereof; and heating means associated with said enclosure and disposed about said array of conduits to supply heat energy to said conduits, said heating means being arranged in association with the conduits such that all portions of the conduits are exposed to heat energy to elevate the temperature of the conduits in controlled manner to a level above the dew point of the atmosphere in which the apparatus is operating whereby the temperature of the conduits is sufficiently high to avoid accumulation of frozen condensate thereon and wherein the condensate, if formed, is maintained in liquid condition to drop from the conduits through the open bottom of the enclosure.

3. The apparatus of claim 2 wherein the enclosure is defined by an outer wall extending along each outer portion of the V-shaped array of conduits to define a generally V-shaped inverted outer enclosure.

5. The apparatus of claim 3 wherein a reflecting surface is defined along the inner walls of the V-shaped conduit array and in spaced relation to the conduits and the outer enclosure to reflect heat from the heating means back toward the conduits on the sides thereof away from the heating means.

7. The apparatus of claim 6 wherein the enclosure extends about the top and sides of the aligned array in substantially uniformly spaced relation thereto.

8. The apparatus of claim 7 wherein the array of conduits is disposed in spaced apart vertically aligned stacked arrays with the conduits in adjacent arrays being offset with respect to each other in a step-like manner.

9. The apparatus of claim 8 wherein the enclosure extends about the top and sides of the aligned arrays and wherein the heating means is mounted in the side walls of the enclosure whereby heat energy emanating from the heating means will directly impinge upon all conduit surfaces to elevate the temperature of the conduits in controlled manner to a level above the dew point of the atmosphere in which the apparatus is operating.