Description:TECHNICAL FIELD

[001] Present disclosure relates to process heaters. Particularly, the present disclosure relates to an air heater that increases the temperature of hydrocarbons.

BACKGROUND OF THE DISCLOSURE

[002] The information in this section merely provides background information related to the present disclosure and may not constitute prior art(s) for the present disclosure.

[003] Air heaters are generally utilized in refineries and petrochemical industries. The air heaters are utilized to increase the temperature of the hydrocarbons. The hydrocarbons may be propane and butane which generally have sub zero temperatures, The said propane and butane are mainly utilized to prepare Liquid Petroleum Gas (LPG). In order to prepare the Liquid Petroleum Gas (LPG), there is a requirement to increase the temperature of the propane from -43℃ to approximately 5 to 10oC and of the butane from -5℃ to approximately 10℃. The conventional air heater includes a plurality of tubes through which the propane and butane in liquid state flow from one fluid source to the other fluid source. The said tubes are positioned within the conventional air heater such that the ambient air comes in contact with the tubes and heat transfers from the ambient air to the hydrocarbons.

[004] Typically, in conventional air heaters, multiple fins are provided on the outer surfaces of the tubes. These fins are positioned on the tubes such that gaps are formed among the tubes. During the winter season, when the temperature of the ambient air is low compared to the summer season, ice forms and solidifies among the fins, which prevents exchanging heat between the hydrocarbons and the ambient air. Further, in order to remove the ice from the tubes, the air heater is required to be shut down for a certain time for defrosting, and a stand by air heater unit is employed which ensures continuous operation. Further, sprinkling the water over the tubes for a defrosting process is also a cumbersome task and incurs additional costs, which are undesired.

[005] The present disclosure is directed to overcome one or more limitations stated above or any other limitations associated with the prior art.

[006] The drawbacks/difficulties/disadvantages/limitations of the conventional techniques explained in the background section are just for exemplary purposes and the disclosure would never limit its scope only such limitations. A person skilled in the art would understand that this disclosure and below mentioned description may also solve other problems or overcome the other drawbacks/disadvantages of the conventional arts which are not explicitly captured above.

SUMMARY OF THE DISCLOSURE

[007] The one or more shortcomings of the prior art are overcome by the configuration of an air heater as claimed, and additional advantages are provided through the provision of the air heater as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

[008] In one non-limiting embodiment of the present disclosure, an air heater is disclosed. The air heater includes a housing, a plurality of tubes, a plurality of fins, and an air source. The housing may be defined with a first header box and a second header box at either ends of the housing. At least one of the first header box and the second header box may be filled with at least one cold liquid. The plurality of tubes may be positioned within the housing. Each tube of the plurality of tubes may be configured to interconnect the first header box and the second header box to allow flow of the at least one cold liquid between the first header box and the second header box. Further, the plurality of fins may be defined at outer portions of each tube of the plurality of tubes. The density of the plurality of fins increases along a direction of flow of the ambient air. Furthermore, the air source may be positioned to cover the housing and configured to supply ambient air towards the housing in a direction perpendicular to the flow of at least one cold liquid. The ambient air flows over the plurality of tubes to allow exchange of heat between the ambient air and at least one cold liquid. The systematic arrangement of the fins prevents ice formation among the fins and aids in maintaining the performance of the air heater.

[009] In an embodiment of the present disclosure, each tube of the plurality of tubes may be arranged parallel to each other.

[0010] In an embodiment of the present disclosure, every alternative tube of the plurality of tubes may be offset from an adjacent tube of the plurality of tubes.

[0011] In an embodiment of the present disclosure, each of the first header box and the second header box may be defined with one or more partition plates to define two or more chambers, wherein the two or more chambers may be formed within the first header box and the second header box to form zig zag flow pattern of the liquid between the first header box and the second header box.

[0012] In an embodiment of the present disclosure, each fin of the plurality of fins may have circular cross section.

[0013] In an embodiment of the present disclosure, the density of the plurality of fins may be in a range from 7 fins/inch to 11 fins/inch.

[0014] In an embodiment of the present disclosure, pitch of the plurality of tubes decreases along with a direction of flow of ambient air.

[0015] In an embodiment of the present disclosure, the at least one cold liquid includes propane and butane.

[0016] In an embodiment of the present disclosure, each tube of the plurality of tubes may be defined with a first end and a second end, wherein the first end may be fluidly coupled to the first header box to receive at least one cold liquid, and the second end may be fluidly coupled to the second header box to supply processed liquid to first header box after exchanging heat.

[0017] In an embodiment of the present disclosure, the air source may be a fan.

[0018] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

[0019] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0020] The novel features and characteristics of the disclosure are set forth in the description. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:

[0021] Figure 1 illustrates a front view of an air heater, according to an embodiment of the present disclosure,

[0022] Figure 2 illustrates a cut-sectional view of the tubes of the air heater in Figure 1,

[0023] Figure 3 illustrates a perspective view of a tube of the air heater of Figure 1, and

[0024] Figure 4 illustrates a cut-sectional view of a portion of the tubes of the air heater in Figure 1.

[0025] Skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of embodiments of the present disclosure.

DETAILED DESCRIPTION

[0026] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in Figures 1-4 and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims.

[0027] Before describing detailed embodiments, the novelty and inventive step that are in accordance with the present disclosure reside in an air heater. It is to be noted that a person skilled in the art can be motivated by the present disclosure and modification of the air heater. However, such modification should be construed within the scope of the present disclosure. Accordingly, the drawings show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0028] In the present disclosure, the term “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or implementation of the present subject matter described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0029] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusions, such that a device that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such device. In other words, one or more elements in a device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the device.

[0030] The terms like “at least one” and “one or more” may be used interchangeably or in combination throughout the description.

[0031] Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, the same numerals will be used to refer to the same or like parts. Embodiments of the disclosure are described in the following paragraphs with reference to Figures 1-4. In Figures 1-4, the same elements or elements that have the same functions are indicated by the same reference signs.

[0032] Referring to Figure 1, it illustrates a front view of an air heater (100). The air heaters (100) may be utilized in process industries like refineries, petrochemical industries, etc. The air heaters (100) may be configured to raise the temperature of hydrocarbons as per the next process requirements. The hydrocarbons may be propane, butane, and the like, which may be required to be at temperatures in between a range of approximately 5℃ to 10℃ in order to produce the Liquid Petroleum Gas (LPG) from said hydrocarbons.

[0033] Referring further to Figure 1, the air heater (100) includes a housing (10). The housing (10) may be configured to support other components of the air heater (100). The housing (10) may be defined with a first header box (20) and a second header box (30) positioned at either ends of the housing (10). At least one header box of the first header box (20) and the second header box (30) may be filled with fluid, for example, cold liquid, for which temperature may be desired to be increased within the air heater (100). In a preferred embodiment, a first chamber (FC) of first header box (20) may be fluidly coupled to a fluid source (not shown in Figures). The first chamber receives cold liquid (propane or butane) to be processed within the air heater (100) in order to raise its temperature. Further, at least one header box of the first header box (20) and the second header box (30) may be coupled to an external equipment in order to supply the liquid after processing.

[0034] The air heater (100) includes a plurality of tubes (40). The plurality of tubes (40) may be positioned within the housing (10). The plurality of tubes (40) may be located between the first header box (20) and the second header box (30) such that each tube of the plurality of tubes (40) interconnects the first header box (20) and the second header box (30), and they allow the liquid to flow between the first header box (20) and the second header box (30). Each tube of the plurality of tubes (40) may be defined with a first end and a second end. The first end may be fluidly coupled to the first header box (20) to receive at least one cold liquid, and the second end may be fluidly coupled to the second header box (30) to supply processed liquid to first header box (20) after exchanging heat. In an embodiment, each tube of the plurality of tubes (40) may be arranged parallel to each other. The flow of liquid in the tubes (40) may be a concurrent flow w.r.t ambient air flow direction.

[0035] In an embodiment, each of the first header box (20) and the second header box (30) may be defined with one or more partition plates (70), as shown in Figure 1. The partition plates (70) may be oriented within each of the first header box (20) and the second header box (30) such that each of the first header box (20) and the second header box (30) defines two or more chambers. The chambers may be formed to flow liquid between the first header box (20) and the second header box (30) in a zig zag flow pattern. For example, the liquid flows through a first chamber of the first header box (20) to a first chamber (FC) of the second header box (30) through a first row and second tube row of the plurality of tubes (40) and then the received liquid flows from the first chamber (FC) of the second header box (30) to a second chamber (SC) of the first header box (20) through a third tube row of the plurality of tubes (40). This pattern of the flow of liquid remains continuous and exits from a third chamber (TC) or the last chamber of the first header box (20). This configuration of the air heater (100) aids in extending a flow path of the liquid.

[0036] Referring further to Figure 1, the air heater (100) includes an air source (60). The air source (60) may be positioned proximal to the housing (10). In an exemplary embodiment, the air source (60) may be placed above the housing (10) to provide ambient air to the housing (10). The air source (60) may be configured to supply ambient air towards the housing (10) in a direction perpendicular to the flow of at least one cold liquid. The ambient air provided by the air source (60) flows over the plurality of tubes (40) to allow the exchange of heat between the ambient air and at least one cold liquid. When the ambient air flows over the tubes (40), the heat may be transferred from the ambient air to the tubes (40) and further, the heat may be transferred from the tubes (40) to the cold liquid. Accordingly, the temperature of the cold liquid present in the tubes (40) may be increased. In an embodiment, the air source (60) may be a fan.

[0037] In an embodiment, every alternative tube of the plurality of tubes (40) may be offset from an adjacent tube of the plurality of tubes (40). For example, the tubes (40) may be oriented in multiple rows such that one row of the tubes (40) may be offset from the adjacent row of the tubes (40), as shown in Figure 2. This arrangement of the tubes (40) may be provided so that the ambient air may flow over the maximum surface area of the tubes (40).

[0038] Referring to Figure 3, each tube of the plurality of tubes (40) includes a plurality of fins (50). The fins (50) may be defined at outer portions (40a) of each tube of the plurality of tubes (40). Each fin of the plurality of fins (50) extends away from the outer portion of the tube (40). In an embodiment, each fin of the plurality of fins (50) has a circular cross section. In an alternate embodiment, the fin may have different shapes other than circular, without limiting the scope of the present disclosure. Each fin may be configured to increase the surface area. Due to the large surface area, the maximum volume of the ambient air contacts the tube portions thereby the heat exchange rate may be maximized.

[0039] Further, the fins (50) may be placed strategically on the tubes (40) such that the density of the fins (50) increases along a direction of flow of ambient air. In an embodiment, the density of the plurality of fins (50) may be in a range of 7 fins/inch to 11 fins/inch.

[0040] In an embodiment, the number of fins (50) in the rows of the tubes (40) positioned proximal to the air source (60) may be less, accordingly, a gap among the fins (50) in said rows of the tubes (40) may be more. Further, the number of fins (50) at the rows positioned away from the air source (60) may be more, accordingly, a gap among the fins (50) at said rows of each tube may be less. At the initial stage, when the cold liquid starts to flow in the tubes (40), the temperature difference between the cold liquid and the air ambient may be more, thus the heat exchange rate between the cold liquid and the ambient air proximal to the first end of each tube may be high. Therefore, maximum heat exchange occurs between the cold liquid and the ambient air without having a large number of fins (50) at the said portion of tubes (40). Accordingly, by reducing the number of fins (50), the ice formation within the gap of the fins (50) may be less. Further, the provision of increasing fin density along the direction of ambient air aids in maintaining a proper heat transfer rate at the entire plurality of tubes (40) thereby the performance of the air heater (100) may be increased. Furthermore, this configuration makes the operation of raising the temperature of cold fluid economical.

[0041] Referring to Figure 4, which illustrates cross sections of two adjacent rows of tubes (40). The tubes (40) may be placed within the housing (10) such that pitch (P1, P2) of the plurality of tubes (40) decreases along the direction of the flow of ambient air. The pitch (P1, P2) may be referred to indicate a longitudinal pitch (P1) and a transverse pitch (P2). The longitudinal pitch (P1) may be further referred to indicate distance between two adjacent rows of the tubes (40) and the transverse pitch (P2) may be referred to the distance between two adjacent tubes (40) of the same row of tubes (40). Due to decreasing pitch (P1, P2) among the tubes (40) and rows of tubes (40). This configuration aids in increasing the number of tubes (40) within the air heater (100).

[0042] In an operational embodiment, the cold liquid flows filled in a first chamber of the first header box (20) enters the tubes (40) of a first and second row, and travels towards the second header box (30). Due to the flow of the cold liquid in the tubes (40), the heat exchanges between the tubes (40) and the cold liquid, and the temperature of the tubes (40) decreases. At the same time, the air source (60) provides ambient air over the tubes (40), thereby the heat exchange between the tubes (40) and the ambient air, which in turn the heat exchanges between the ambient air and the cold liquid and the temperature of the cold liquid increases to an extent. Subsequently, the liquid exits from the second ends of the tubes (40) and enters into a first chamber of the second header box (30). The received liquid further enters into the tubes (40) of a third row and travels towards a second chamber of the first header box (20). This process runs continuously and in each row of the tubes (40), the heat exchanges between the liquid and the ambient air. This process may be continuously performed in order to achieve the desired temperature of the liquid.

[0043] In accordance with the present disclosure, the air heater (100), as explained in the above paragraphs, prevents ice formation among tubes (40). Further, the air heater (100) of the present disclosure aids in the loss of load capacity by 50-60%. Also, the air heater (100) of the present disclosure is simple, easy to manufacture, and makes the operation of raising the temperature of the cold liquid economical.

[0044] The various embodiments of the present disclosure have been described above with reference to the accompanying drawings. The present disclosure is not limited to the illustrated embodiments; rather, these embodiments are intended to fully and completely disclose the subject matter of the disclosure to those skilled in this art. In the drawings, like numbers refer to like elements throughout. The thicknesses and dimensions of some components may be exaggerated for clarity.

[0045] LIST OF REFERENCE NUMERALS
Sr. No. Description
100 Air heater
10 Housing
20 First header box
30 Second header box
40 Tubes
40a Outer portions
50 Fins
60 Air source
70 Partition plates
P1 First pitch
P2 Second pitch
FC First chamber
SC Second chamber
TC Third chamber

[0046] EQUIVALENTS:

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.
Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
 
We claim:
1. An air heater (100) comprising:
a housing (10) defined with a first header box (20) and a second header box (30) at either ends of the housing (10), at least one of the first header box (20) and the second header box (30) is filled with at least one cold liquid;
a plurality of tubes (40) positioned within the housing (10), each tube of the plurality of tubes (40) is configured to interconnect the first header box (20) and the second header box (30) to allow flow of the at least one cold liquid between the first header box (20) and the second header box (30);
a plurality of fins (50) defined at outer portions (40a) of each tube of the plurality of tubes (40), wherein density of the plurality of fins (50) increases along a direction of flow of the ambient air; and
an air source (60) positioned to cover the housing (10) and configured to supply ambient air towards the housing (10) in a direction perpendicular to the flow of the at least one cold liquid, wherein the ambient air flows over the plurality of tubes (40) to allow exchange of heat between the ambient air and the at least one cold liquid.

2. The air heater (100) as claimed in claim 1, wherein each tube of the plurality of tubes (40) are arranged parallel to each other.

3. The air heater (100) as claimed in claim 1, wherein every alternative tube of the plurality of tubes (40) is offset from an adjacent tube of the plurality of tubes (40).

4. The air heater (100) as claimed in claim 1, wherein the each of the first header box (20) and the second header box (30) is defined with one or more partition plates (70) to define two or more chambers, wherein the two or more chambers are formed within each of the first header box (20) and the second header box (30) to form zig zag flow pattern of the liquid between the first header box (20) and the second header box (30).

5. The air heater (100) as claimed in claim 1, wherein each fin of the plurality of fins (50) has circular cross section.

6. The air heater (100) as claimed in claim 1, wherein the density of the plurality of fins (50) are in a range from 7 fins/inch to 11 fins/inch.

7. The air heater (100) as claimed in claim 1, wherein pitch (P1, P2) of the plurality of tubes decreases along with a direction of flow of ambient air.

8. The air heater (100) as claimed in claim 1, wherein the at least one cold liquid includes propane and butane.

9. The air heater (100) as claimed in claim 1, wherein each tube of the plurality of tubes (40) is defined with a first end and a second end, wherein the first end is fluidly coupled to the first header box (20) to receive at least one cold liquid, and the second end is fluidly coupled to the second header box (30) to supply processed liquid to first header box (20) after exchanging heat.

10. The air heater (100) as claimed in claim 1, wherein the air source (60) is a fan. , Claims:PLEASE SEE THE ATTACHMENTS.