Background Art As per second edition of book namely, Heat Exchangers, Selection, Rating and Thermal design, authored by Sadik Kakac and Hongtan Liu and published by CRC Press in the Year 2002, pages 1 to 30, the heat exchangers are devices that provide the flow of thermal energy between two and more fluids at different temperatures. According to heat transfer processes, heat exchangers are classified as direct contact type and indirect contact type. In the direct contact type heat exchangers, heat is transferred between the cold and hot fluids through direct contact between these fluids. There is no separation wall between the hot and cold streams. In the indirect contact type heat exchangers, the heat energy is exchanged between hot and cold fluids through a heat transfer surface, which is a wall separating the fluids; the cold and hot fluids flow simultaneously while heat energy is transferred through a separating wall.

Indirect contact and direct transfer heat exchangers are also called recuperators, tubular (double-pipe or shell-and-tube), plate and extended surface heat exchangers. According to the fourth edition of the book namely, Perry's Chemical Engineer's Handbook authored by John H. Perry and published by McGraw-Hill Company in the Year 1963, page 11-2, the investment in chemical plant equipment indicates that heat exchangers are generally the most important items in a chemical plant. Individual exchangers may be small but the over all cost of heat-transfer equipment is such that careful attention should be paid to their design, specifications and performance.

In the prior art, the piping equipment in a chemical plant is often used to transport process fluids between two or more process equipments, whereas, indirect contact and direct transfer type heat exchanger equipment, major types of which are tubular, plate and extended surface heat exchangers, is used to cool or heat above referred process fluids to a required temperature. The piping equipment and said heat exchanger equipment are often used in combination, wherein, piping equipment transports process fluid to heat exchanger and heat exchanger equipment cools or heats process fluid to the required temperature, by means of coolant or a thermal fluid.

These methods of prior art have following disadvantages : 1) Installation of both equipments in a chemical plant that is, piping equipment and heat exchanger equipment, adds to capital cost and thereby increases total cost of building a chemical plant.

2) Each of the above equipment, that is piping equipment and heat exchanger equipment, requires a separate installation, which is costly.

Also, more space and longer installation time is required for building a chemical plant, when separate installations are required.

3) The plant layout becomes more complex, due to various piping connections are required between equipments, such as: piping equipment connection to heat exchanger equipment and piping equipment connection from heat exchanger equipment to other process equipment.

4) Each of the piping equipment and the heat exchanger equipment requires a separate maintenance job. Maintenance of more equipments and piping connections increases number of plant breakdowns and total downtime of the plant.

5) A double-pipe heat exchanger of indirect contact type is known, As per second edition of book namely, Heat Exchangers, Selection, Rating and Thermal design, authored by Sadik Kakac and Hongtan Liu and published by CRC Press in the Year 2002, pages 7 to 8, which consists of one pipe placed concentrically inside another pipe of a larger diameter with appropriate fittings to direct the flow of fluids. The

major use of the double-pipe heat exchanger however is where smaller heat transfer area is required. The major disadvantage is that it is bulky and expensive per unit of heat transfer surface area.

Due to above disadvantages, a chemical plant of prior art becomes more complex and costly to install and also less reliable and more expensive to operate.

Objects And Advantages Of Invention It is an object of this invention to devise a new modified piping system and method of making the same, and method of heat transfer using modified piping system, thereby combining into the modified piping equipment, simultaneous transport of process fluids as well as cooling or heating of process fluids from one or both sides, whereby, capital cost for installation of chemical plant is reduced and plant is made simple to operate and easy to maintain.

Accordingly, several objects and advantages of invention are : 1) A number of equipments to carry out heat transfer in a chemical plant are reduced by use of a modified piping system, which simultaneously transports as well as cools or heats the process fluids instead of using separate piping equipment for transport of process fluid and separate indirect contact heat exchanger equipment for cooling or heating of the process fluid. Due to this reduction in number of equipment to carry out heat transfer; the total cost of building a chemical plant is reduced.

2) Due to reduction in the installation of number of equipment in a chemical plant by use of modified piping system, the total installation cost of equipments is reduced. The reduction in number of equipment installation makes the plant construction faster and reduces the space required for building a chemical plant.

3) The reduction in number of equipments by use of a modified piping system reduces number of joints required to connect various equipments of the chemical plant, which thereby improves plant layout and makes plant construction simpler.

4) The use of modified piping system reduces number of equipments and

their interconnections, which thereby reduces number of plant breakdown for maintenance, due to maintenance jobs of fewer equipment and fluid leakages from their interconnection, therefore running time of plant is increased.

5) As modified piping system uses coaxially fitted multiple pipes, where coolant or thermal fluid flows through annular space on one or both sides of pipe carrying the process fluid, heat transfer is increased and thereby modified piping system becomes compact and less expensive.

6) The modified piping system with optional extended surfaces and turbulent surfaces further improves the heat transfer and makes the modified piping system more compact and more cost effective.

7) The modified piping system with multiple pipes can be used, wherever higher heat transfer area is required per unit space.

Other objects and advantages of invention are: 1) The flow ducts of modified piping system transporting coolant or thermal fluid are provided with extended surfaces. This provision of extended surfaces within flow ducts transporting coolant or thermal fluid increases contact surface area of coolant and thermal fluid and thereby increases the transfer of heat from or to the process fluid.

2) The modified piping system, with spiral extended surfaces in flow ducts which also forms annular flow ducts within flow ducts transporting coolant or thermal fluids improves the flow circulation and thereby improves heat transfer of coolant or thermal fluids.

3) The flow ducts of the modified piping system, transporting the process fluid is provided with spaced plates. The provision of these spaced plates within flow ducts transporting process fluid helps to uniformly distribute heat of the process fluid through extended surfaces to coolant or thermal fluids.

1) The provision of extended surfaces in flow ducts transporting coolant thermal fluid and provision of spaced plates in flow duct transporting process fluid improves the structural rigidity of the modified piping system and makes the equipment sturdy.

2) The modified piping system with spiral spaced plates, which also

forms annular flow ducts within flow ducts transporting process fluid, improves flow circulation and heat transfer of process fluid.

Brief Description of the Drawings FIG. 1 is a part sectional view of the modified piping system consisting of three pipes construction, according to the first most preferred embodiment of the invention.

FIG. 2 is a part sectional view of the modified piping system consisting of five pipes construction, according to second embodiment of the invention.

FIG. 3 is a part sectional view of the modified piping system consisting of two pipes construction, according to third embodiment of the invention.

FIG. 4 is the modified piping system according to the invention integrated into the chemical plant between two chemical equipment such as pump tank and tower.

FIG. 5 is the prior art where piping is used for transport and heat exchanger is used for heating or cooling between two chemical equipment such as pump tank and tower.

The list of reference numbers and the nomenclature of parts used in the drawings are described below: Reference Number Nomenclature of Parts 1. Inner pipe 2. Center pipe 3. Outer pipe 4. Support member 5. Extended surfaces in inner annular space 6. Spaced plates in center annular space 7. Extended surfaces in outer annular space 8. Center pipe inlet flange 9. Center pipe outlet flange 10. Inner pipe inlet flange 11. Inner pipe outlet flange 12. Outer pipe inlet flange 13. Outer pipe outlet flange 14. Process fluid pump tank

15. Process fluid pump 16. Center annular space of the modified piping syste 17. Inner annular space of the modified piping system. 18. Outer annular space of the modified piping system 19. Process fluid inlet flange 20. Process fluid outlet flange 21. Gas inlet flange 22. Gas outlet flange 23. The tower 24. The heat exchanger 25. The conventional piping 1) Inner pipe (1) is a cylindrical hollow pipe having outer diameter smaller than the inner diameter of the center pipe (2).

2) Center pipe (2) is the cylindrical hollow pipe having outer diameter smaller than the inner diameter of the outer pipe (3) and inner diameter larger than the outer diameter of the inner pipe (1).

3) Outer pipe (3) is the cylindrical hollow pipe having inner diameter larger than the outer diameter of the center pipe (2).

4) Support member (4) is the cylindrical rod or pipe with outer diameter smaller than the inner diameter of the inner pipe (l).

5) Extended surfaces in inner annular space (5) is the spiral plates, width of which corresponds substantially to difference in radii of interior surface of wall of the inner pipe (1) and the exterior surface of wall of the support member (4).

6) Spaced plates in center annular space (6) is the spiral plates, width of which corresponds substantially to difference in radii of interior surface of wall of the center pipe (2) and the exterior surface of wall of the inner pipe (1) 7) Extended surfaces in outer annular space (7) is the spiral plates, width of which corresponds substantially to difference in radii of interior surface of wall of the outer pipe (3) and the exterior surface of wall of the center pipe (2).

8) Center pipe inlet flange (8) is a thick metal ring having bolt holes. The 195 inside diameter of the ring is welded to one end of a piece of pipe. The other end of the same piece of pipe is welded to the same pipe size hole made in the center pipe (2). The process fluid enters the center pipe (2) of the modified piping system through the center pipe inlet flange (8).

9) Center pipe outlet flange (9) is a thick metal ring having bolt holes.

200 The inside diameter of the ring is welded to one end of a piece of pipe and the other end of the same piece is welded to the same pipe size hole made in the center pipe (2). The process fluid exits the center pipe (2) of modified piping system through center pipe outlet flange (9).

10) Inner pipe inlet flange (10) is a thick metal ring having bolt holes. The 205 inside diameter of the ring is welded to one end of the inner pipe (1). The coolant or thermal fluid enters the inner pipe (1) of the modified piping system through the inner pipe inlet flange (10).

11) Inner pipe outlet flange (11) is a thick metal ring having bolt holes.

The inside diameter of the ring is welded to the other end of the inner 210 pipe (1). The coolant or thermal fluid exits the inner pipe (1) of the modified piping system through the inner pipe outlet flange (11).

12) Outer pipe inlet flange (12) is a thick metal ring having bolt holes. The inside diameter of the ring is welded to one end of a piece of pipe and the other end of the same piece is welded to the same pipe size hole made in 215 the outer pipe (3). The coolant or thermal fluid enters the outer pipe (3) of the modified piping system through the outer pipe inlet flange (12).

13) Outer pipe outlet flange (13) is a thick metal ring having bolt holes.

The inside diameter of the ring is welded to one end of a piece of pipe and the other end of the same piece is welded to the same pipe size hole 220 made in the outer pipe (3). The coolant or thermal fluid exits the outer pipe (3) of the modified piping system through the outer pipe outlet flange (13).

14) Process fluid pump tank (14) is the tank holding the process fluid, which requires transportation to the tower (23) as well as heating or 225 cooling.

15) Process Fluid Pump (15) is the pump, which transports the process fluid from pump tank (14) and forces it through the center annular space of the modified piping system (16) into the tower (23).

16) Center annular space of the modified piping system (16) is the 230 annular space between center pipe (2) and inner pipe (1) and carries process fluid from process fluid pump (17) discharge, to the inlet of the tower (23).

17) Inner annular space of the modified piping system (17) is the annular space between inner pipe (1) and support member (4) and 235 carries coolant or thermal fluid.

18) Outer annular space of the modified piping system (18) is the annular space between outer pipe (3) and center pipe (2) and carries coolant or thermal fluid.

19) Process fluid inlet flange (19) is the ring having drilled holes. The 240 inner diameter of the ring is welded to one end of a piece of pipe and the other end of the same piece of pipe, is welded to the same size hole made in upper part of the tower (23). This ring is to be bolted to outlet flange for center pipe (9). The process fluid enters the tower (23) through this flange connection.

245 20) Process fluid outlet flange (20) is the ring having drilled holes. The inner diameter of the ring is welded to one end of a piece of pipe and the other end of the same piece of pipe, is welded to the same size hole made in lower part of the tower (23). The process fluid exits the tower (23) through this flange connection.

250 21) Gas inlet flange (21) is the ring having drilled holes. The inner diameter of the ring is welded to one end of a piece of pipe and the other end of the same piece of pipe, is welded to the same size hole made in lower side of the tower (23). The gas enters the tower (23) through this flange connection.

255 22) Gas outlet flange (22) is the ring having drilled holes. The inner diameter of the ring is welded to one end of a piece of pipe and the other end of the same piece of pipe, is welded to the same size hole made in top or top side of the tower (23). The gas exits the tower (23) through this flange connection.

260 23) The tower (23) is a cylindrical shell with closed top and bottom having various holes for connecting process fluid inlet flange (19), process fluid outlet flange (20), Gas inlet flange (21) and Gas outlet flange (22).

24) The heat exchanger (24) is the heat exchanger having inlet and outlet for the process fluid and inlet and outlet for the coolant or thermal fluid.

265 It is used for heating or cooling of the process fluid with the help of coolant or thermal fluid.

25) Conventional Piping (25) is the hollow pipe that is connected from process fluid pump (15) to the heat exchanger (24) and from heat exchanger (24) to the tower (23). It is used for transporting process fluid 270 from process fluid pump tank (14) to heat exchanger (24) and from the heat exchanger (24) to the tower (23) in a chemical plant.

Disclosure of the Invention This invention is explained with reference to accompanying drawings.

In FIG 1 to 5 extended surfaces (5,7) and spaced plates (6) are shown only 275 for partial length of pipes. In practice, they are provided for predetermined length of corresponding pipe, as required by the process.

The FIG. 1 is the first most preferred embodiment having three-pipe construction. The support member (4) has its length, greater than the length of inner pipe (1). The extended surfaces in the inner annular space (5), 280 comprising of spiral plates and having optional turbulent surface with its inner diameter substantially equal to the outer diameter of the support member (4) and outer diameter substantially equal to inner diameter of the center pipe (2) is disposed over the support member (4) until the full length, of the extended surfaces in the inner annular space (5) which is 285 substantially equal to length of the inner pipe (1) covers the support member (4). The inner pipe (1) having its inner diameter substantially equal to the outer diameter of the extended surfaces in inner annular space (5) and its length smaller than the length of the support member (4) is disposed over the outer edge of the extended surfaces in the inner annular space (5).

290 Due to very small difference in diameter between the inner diameter of the inner pipe (1) and the outer diameter of the extended surfaces in the inner annular space (5), the outer edge of the extended surfaces in inner annular space (5) presses against the inner surface of the inner pipe (1) and thereby makes a good thermal contact.

295 The spaced plates in center annular space (6) comprising of spiral plates and having optional turbulent surface with its inner diameter substantially equal to the outer diameter of the inner pipe (1) and outer diameter substantially equal to the inner diameter of the center pipe (2) is disposed over the inner pipe (1), until the full length of the spaced plates in 300 center annular space (6), which is substantially equal to the straight length of the center pipe (2) covers the inner pipe (1). The center pipe (2) having its inner diameter substantially equal to the outer diameter of the spaced plates in center annular space (6) and having its length smaller than the length of the inner pipe (1) is disposed over the outer edge of the spaced 305 plates in center annular space (6). Due to very small difference in diameter between the inner diameter of the center pipe (2) and the outer diameter of the spaced plates in the center annular space (6), the outer edge of the spaced plates in center annular space press against outer surface of the inner pipe (1) and inner surface of center pipe (2) and respectively, thereby 310 making good thermal contact.

The extended surfaces in outer annular space (7) comprising of spiral plates and having optional turbulent surface with its inner diameter substantially equal to the outer diameter of the center pipe (2) and the outer diameter substantially equal to the inner diameter of the outer pipe (3) is 315 disposed over the center pipe (2), until the full length of the extended surfaces in outer annular space (7), which is substantially equal to the straight length of the outer pipe (3) covers the center pipe (2). The outer pipe (3) having its inner diameter substantially equal to the outer diameter of the extended surfaces in outer annular space (7) and its length smaller 320 than the length of the center pipe (2) is disposed over the extended surfaces in outer annular space (7). Due to very small difference in diameter between the inner diameter of the outer pipe (3) and the outer diameter of extended surfaces in the outer space (7). The outer edge of the extended surfaces in outer annular space (7) presses against outer surface of the center pipe (2) 325 and inner surface of outer pipe (3) respectively and therefore makes a good thermal contact.

The ends of center pipe (2) are closed by two rings, each of the two rings having its inner diameter substantially equal to the outer diameter of the inner pipe (1) and having its outer diameter substantially equal to the 330 inner diameter of the center pipe (2). One of the two rings is inserted over and from one end of the inner pipe (1) and the other ring is inserted over and from the outer end of the inner pipe (1). Each ring is inserted to such an extent over the inner pipe (1), that full outer circumferential surface of the ring is disposed in substantial contact with inner surface of respective 335 end of the center pipe (2). The outer circumferential surface of each ring is welded at respective end of the center pipe (2) to its inner surface, and inner circumferential surface of each ring is welded to the respective outer surface of the inner pipe (1) to make a leak proof joint.

The ends of outer pipe (3) are closed by two rings, each of the two 340 rings having its inner diameter substantially equal to the outer diameter of the center pipe (2) and having its outer diameter substantially equal to the inner diameter of the outer pipe (3). One of the two rings is inserted over and from one end of the center pipe (2) and the other ring is inserted over and from the outer end of the center pipe (2). Each ring is inserted to such 345 an extent over the center pipe (2), that full outer circumferential surface of the ring is disposed in substantial contact with inner surface of respective end of the outer pipe (3). The outer circumferential surface of each ring is welded at respective end of the outer pipe (3) to its inner surface, and inner circumferential surface of each ring is welded to the respective outer surface 350 of the center pipe (2) to make a leak proof joint.

An inner pipe inlet flange (10) and an inner pipe outlet flange (11) with inner diameter of each of the flanges (10,11) substantially equal to the outer diameter of the inner pipe (1) are inserted from each end over the outer diameter of the inner pipe (1), until the outer flat surfaces of flanges 355 (10,11) are disposed in the same plane as the respective end surfaces of the inner pipe (1). The flanges (10,11) are then welded to the respective outer cylindrical surface of the inner pipe (1).

An inlet hole of diameter substantially equal to inner diameter of center pipe inlet flange (8) is made in the cylindrical surface of the center 360 pipe (2) near one end thereof, and an outlet hole of diameter substantially equal to inner diameter of center pipe outlet flange (9) is made in the cylindrical surface of the center pipe (2) near the other end thereof. A piece of pipe of predetermined length, having outer diameter thereof, substantially equal to the inner diameter of center pipe inlet flange (8), and also 365 substantially equal to the diameter of the inlet hole of center pipe (2), one end of this piece of pipe is welded to the center pipe inlet flange (8), and other end of the same piece of pipe is welded to circumferential surface of the inlet hole of the center pipe (2). Other piece of pipe of predetermined length, having outer diameter thereof substantially equal to the diameter of 370 center pipe outlet flange (9), and also substantially equal to the diameter of the outlet hole of the center pipe (2). One end of this other piece of pipe is welded to the center pipe outlet flange (9) and other end of the same piece of pipe is welded to circumferential surface of the outlet hole of the center pipe (2).

375 An inlet hole of diameter substantially equal to inner diameter of outer pipe inlet flange (12) is made in the cylindrical surface of the outer pipe (3) near one end thereof, and an outlet hole of diameter substantially equal to inner diameter of outer pipe outlet flange (13) is made in the cylindrical surface of the outer pipe (3) near the other end thereof. A piece 380 of pipe of predetermined length, having outer diameter thereof, substantially equal to the inner diameter of outer pipe inlet flange (12), and also substantially equal to the diameter of the inlet hole of outer pipe (3). One end of this piece of pipe is welded to the outer pipe inlet flange (12), and other end of the same piece of pipe is welded to circumferential surface of 385 the inlet hole of the outer pipe (3). Other piece of pipe of predetermined length, having outer diameter thereof substantially equal to the diameter of outer pipe outlet flange (13), and also substantially equal to the diameter of the outlet hole of the outer pipe (3). One end of this other piece of pipe is welded to the outer pipe outlet flange (13) and other end of the same piece of 390 pipe is welded to circumferential surface of the outlet hole of the outer pipe (3).

The FIG. 2 shows five pipe construction, according to second embodiment of this invention and its construction with five pipes is similar to the three pipe construction with this embodiment having five pipes and 395 two sets of spaced plates and three sets of extended surfaces in respective annular spaces.

The FIG. 3 shows two pipe construction, according the third embodiment of the invention and its construction with two pipes is similar to the three pipe construction with this third embodiment having two pipes 400 and only one spaced plates and one extended surfaces in respective annular spaces.

The FIG. 4 shows the modified piping system integrated into a chemical plant between two equipments of a chemical plant like a process fluid pump tank (14) and a tower (23). The process fluid stored in the 405 process fluid pump tank (14) requiring heating or cooling and also transport to the tower (23) is transported by a means of the process fluid pump (15).

The process fluid is transported from the pump tank (14) through the center annular space of the modified piping system (16) to the tower (23).

While the process fluid is being transported through center annular space of 410 the modified piping system (16), the process fluid is simultaneously heated or cooled by means of coolant or thermal fluid circulated through inner annular space of the modified piping system (17) and outer annular space of the modified piping system (18). The process fluid is therefore transported at the required temperature to a tower (23) by means of the modified piping 415 system through process inlet flange (19). The process fluid once again gets heated or cooled during its transport through the tower (23), due to its contact with the gases. The gases enters in the tower (23) through a gas inlet flange (21) and exits through a gas outlet flange (22). The heated or cooled process fluid leaves the tower (23) from a process fluid outlet 420 flange (20) into process fluid pump tank (14). The same operation described above continues and thereby the modified piping system accomplishes simultaneous transport and heating or cooling of the process fluid.

FIG. 5 shows the prior art in which separately a conventional piping (25) is utilized for transport of process fluid from process fluid pump 425 tank (14) to heat exchanger (24) and also from a heat exchanger (24) to a tower (23). A heat exchanger (24) is utilized for the heating or cooling of the process fluid.

Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example, and it is not to be taken by way of limitation. The spirit of the present invention is to be limited only by term of the appended claims.