WO2019142209A1

WO2019142209A1 - System for cleaning the shell and tube heat exchanger and a method therefor

Info

Publication number: WO2019142209A1
Application number: PCT/IN2019/050036
Authority: WO
Inventors: Mohan Narhari Chavan
Original assignee: Mohan Narhari Chavan
Priority date: 2018-01-19
Filing date: 2019-01-15
Publication date: 2019-07-25

Abstract

Disclosed is a system (100) for cleaning a shell and tube heat exchanger and a method therefor. The method comprises an injection cycle, a collection cycle and a resting cycle. The system (100) comprises a bi-directional pump (102) that operates intermittently for a very small duration for the injection cycle and the collection cycle. The system (100) functions without using any electrically operated valves. The system (100) injects the cleaning bodies (118) very fast that is almost simultaneously to have effective cleaning of the tubes. The system (100) is more reliable and requires very little maintenance as there are no other moving/rotating parts except the bi-directional pump (102).

Description

SYSTEM FOR CLEANING THE SHELL AND TUBE HEAT EXCHANGER AND A

M ETHOD THEREFOR

Feld of the invention:

The present invention relates to heat exchangers and more particularly, to an online system for cleaning the inner walls of the tubes of a shell and tube heat exchanger. Background of the invention:

Shell and tube heat exchangers in the industries are prone to scaling or fouling when water flows th rough the tubes. In order to improve the heat transfer efficiency of the shell and tube heat exchangers it is important to keep the inside walls of the tubes clean. There are online condenser tube cleaning systems already available in the market which use cleaning sponge balls and brushes.

For example, patent no. US5388636 (A) discloses a system for cleaning the tubes of heat exchanger based on air injection. The system for cleaning inside the heat exchanger tube uses a plurality of balls entrained by liquid flowing through the system. The system employs a compressor to selectively provide a quantity of compressed air into the storage means to inject a portion of liquid from the storage along with the balls to upstream of the tubing. Here the compressed air gets m ixed with the water that is flowing through the heat exchanger or condenser and affects the heat transfer in the heat exchanger/ condenser. The pressure variation in the compressed air also affects the collection of the balls after passing through the heat exchanger/condenser. Another system for cleaning the tubing disclosed in patent US7036564 uses cleaning balls that are circulated with the fluid through the tubing. The cleaning balls are circu lated through the tubing by a suction force generated by the pressure difference at the entrance of a fluid supply pipe and the exit of the cleaning ball supply pipe. The suction force required to recirculate the cleaning balls are created by the pressure difference in the entrance of the cleaning ball return pipe and the exit of the fluid retu rn pipe. Here the system functions without pump but with increased n umber of elect rically operated valves. Accordingly, there exists a need to provide an effective and reliable system for cleaning a shell and tube heat exchanger that overcom es the above mentioned drawbacks of the prior art.

Objects of the invention:

An object of the present invention is to clean a shell and tube heat exchanger without using the electrically operated/ actuated valves.

Another object of the present invention is to clean the shell and tube heat exchangers with a provision to view the cleaning bodies.

Yet another object of the present invention is to provide an effective air vent and ball charging arrangement at a chamber without losing the cleaning bodies during start up.

Another object of the present invention is to effectively use a bi-directional pump for effective injection and collection of the cleaning bodies and to achieve efficient cleaning of the tubes. Summary of the invention:

Accordingly, the present invention provides a system for cleaning a shell and tube heat exchanger. Specifically, the system is used for cleaning the inner walls of the tubes of the shell and tube heat exchanger. The system comprises a cleaning body chamber, a bi-directional pump, a controller, a plurality of cleaning bodies, a cleaning body catcher, a first check valve, a second check valve, a plurality of valves, a cooling water inlet and a cooling water outlet. The plurality of valves is manual ball valves.

The cleaning body chamber (hereinafter“the chamber”) is a vessel having a half conical shape at a top portion and a dish shape at a bottom portion thereof. The chamber includes an air vent, a drain port, a perforated mesh, a sight glass, a water inlet and a water outlet. The air vent is positioned on a topmost portion of the chamber for venting the air. The air vent includes a manual ball valve configu red therein . The drain port is positioned on the bottom portion of the chamber. The drain port includes a manual ball valve configured therein. The perforated mesh is placed in the chamber for holding a plurality of cleaning bodies. The cleaning bodies are sponge balls or the spherical bodies made of flexible material like silicon of diameter slightly larger than internal diameter of the tubes of the heat exchanger. The sight glass is provided for viewing the quantity of the plurality of cleaning bodies. The water inlet and the water outlet are arranged on either sides of the chamber.

The bi-directional pump is f itted between the cleaning body chamber and the cooling water outlet. The bi-directional pump is capable of rotating in any one of a clockwise direction and an anti-clockwise direction to pressurize/depressurize the cleaning body chamber. The controller controls an operation of the bi- directional pump. The controller is a program mable logic controller based electronic controller.

The cleaning body catcher is installed at an outlet of the condenser for arresting the plurality of cleaning bodies. The cleaning body catcher includes an outer body and flanged ends. The outer body of the cleaning body catcher has any one of a cylindrical shape and a bottle shape. The outer body houses a cylindrical mesh and a conical shaped mesh therein. The cylindrical mesh and the conical shaped mesh includes round equidistant holes of 8 m m diameter.

The first check valve is connected to the cooling water inlet for injecting the plurality of cleaning bodies from the chamber into the condenser. The second check valve is connected to an outlet of the cleaning body catcher for carrying the plu rality of cleaning bodies therefrom to the clean ing body chamber. The heat exchanger tubes are cleaned by circulating the cleaning bodies along with a water therethrough.

In another aspect, the present invention provides a method for cleaning a shell and tube heat exchanger. The m ethod comprises a resting cycle, an injection cycle and a collection cycle that works at an interm ittent interval.

Brief description of the drawings:

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein

Figure 1 shows a schematic view of a system for cleaning a shell and tube heat exchanger, in accordance with the present invention ; Figure 2 shows a schematic view of a cleaning body chamber of the system for cleaning the shell and tube heat exchanger, in accordance with the present invention ;

Figure 3A shows a schematic view of a cleaning body catcher of the system for cleaning the shell and tube heat exchanger, in accordance with the present invention ;

Figure 3B shows a schematic view of a cleaning body catcher of the system for cleaning the shell and tube heat exchanger, in accordance with another embodiment of the present invention ;

Figure 4 shows a schematic view of a clean ing body injection cycle of the system for cleaning the shell and tube heat exchanger, in accordance with the present invention ; and

Figure 5 shows a schematic view of a cleaning body collection cycle of the system for cleaning the shell and tube heat exchanger, in accordance with the present invention.

Detailed description of the invention:

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiments.

The present invention provides a system for cleaning a shell and tube heat exchanger without consu ming/using any electrically actuated/ operated valves. The system works by using a bi-directional pump that rotates in both the directions to flow the cleaning bodies according to the requirements.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference nu mbers i ndicate corresponding parts in the various figures. These reference nu mbers are shown in bracket in the following description and in the table below.

Table:

Referring to figures 1 to 3B, a system (100) for cleaning a shell and tube heat exchanger in accordance with the present invention is shown. Specif ically, the system (100) is used for cleaning the inner walls of the tubes of the shell and tube heat exchanger. The system (100) comprises a bi-directional pump (102), a cleaning body chamber (103) (hereinafter“the chamber (103)”), a plurality of valves (101 , 107, 108), a first check valve (104), a second check valve (1 05), a cleaning body catcher (109), a condenser (1 10), a plurality of cleaning bodies (1 18) (hereinafter “the cleaning bodies (1 18)”), a controller (121 ), a cooling water inlet (122) and a cooling water outlet (132).

The bi-directional pump (102) is fitted between the chamber (103) and the cooling water outlet (132). The bi-directional pump (102) is capable of rotating in any one of a clockwise direction and an anti-clockwise direction to pressurize/depressurize the chamber (103) to inject/collect the cleaning bodies (1 18). The bi-directional pu mp (102) is any one of a th ree phase twin lobe type rotary pu mp, a liqu id ring centrifugal pump and any other type pu mp that is capable of rotating and operating in the clockwise/ anti-clockwise directions. The change in the direction is achieved by interchanging one of the phases of the three phase supply.

The operation of the bi-directional pump (102) is controlled by the controller (121 ). The controller (121 ) controls the start/stop and reverse speed operation of the bi-directional pump (102). In an embodiment, the controller (121 ) is a programmable logic controller (PLC) based elect ronic controller that controls the sequence of operation of the system (1 00). As shown in figure 2, the chamber (103) is a vessel having a half conical shape at a top portion and a dish shape at a bottom portion thereof . The chamber includes an air vent (1 1 1 ), a drain port (1 12), a perforated mesh (1 13), a sight glass (1 14), a water inlet (not numbered) and a water outlet (not numbered). The water inlet and the water outlet are arranged on either sides of the chamber (103).

The air vent (1 1 1 ) is positioned on a topmost portion of the chamber (103). The air vent (1 11 ) includes a manual ball valve (not numbered) configured therein. The air vent (1 1 1 ) facilitates venting of the air during startup of the system (100) and at the time of com mission ing or re-start of the system (100) after replacement of the cleaning bodies (1 18). The associated valve at the air vent (1 1 1 ) normally remains in a closed condition and is opened manually only for venting the air. The air vent (1 1 1 ) is welded to the perforated mesh (1 13) at a bottom portion thereof.

The perforated m esh is placed inside the chamber (103). The perforated m esh (1 13) holds the cleaning bodies (1 18) and ensures that the cleaning bodies (1 18) do not escape while venting the air from the chamber (103). In an embodiment, the cleaning bodies (1 18) are sponge balls or the spherical bodies made of flexible material like silicon of diameter slightly larger than an internal diameter of the tubes of the heat exchanger. The system (100) allows addition of additional number of cleaning bodies (1 18) into the chamber (1 03) as per the requirement.

The sight glass (1 14) is a transparent part that facilitates viewing of the quantity of the cleaning bodies (1 18) inside the chamber (103). The conical end of the chamber (1 03) has a flanged end and facilitates charging of the cleaning bodies (1 18) without opening the sight glass (1 14). The drain port (1 12) is positioned on the bottom portion of the chamber (103). The drain port (1 12) includes a manual ball valve (not numbered) that helps to drain the chamber (103) while replacing the cleaning bodies (1 18). The plurality of valves (101 , 108, 107) is manually operable. In an embodiment, the plurality of valves (101 , 107, and 108) is manual ball valves that remain open on normal condition and are operated only in case of shutdown or maintenance. However, it is understood here that the plu rality of valves (101 , 108, 107) may be of any other type in other alternative embodiments of the system (100). The first check valve (104) is connected to the cooling water inlet (122) for injecting the plurality of cleaning bodies (1 18) from the cleaning body chamber (103) into the condenser (1 10). The second check valve (105) is connected to an outlet (142) of the cleaning body catcher (109) for carrying the plu rality of cleaning bodies (1 18) therefrom to the cleaning body chamber (103). During an injection cycle, the check valve (105) restricts the water flow and the clean ing bodies (1 18) are injected at the cooling water inlet pipe (122) through the first check valve (104). During the collection cycle, the first check valve (104) restricts the water flow from the cooling water inlet pipe (122) to the chamber (1 03) for effective cleaning of the cleaning bodies (1 18) from the catcher (109) to the chamber (103) through the second check valve (105).

The cleaning body catcher (109) is a trap to arrest the cleaning bodies (1 18) exited out of the heat exchanger. The cleaning body catcher (109) is installed at an outlet of the condenser (1 10). In an embodiment, the cleaning body catcher (109) is a stationery body having an outer body (not numbered) in a cylindrical shape as shown in figure 3A. The diameter of the outer body is at least two inches larger than the diameter of a pipe on wh ich the cleaning body catcher (109) is fitted. The cleaning body catcher (109) includes flanged ends (not numbered) having the same diameter as that of the pipe on which the cleaning body catcher (109) is fitted. The outer body and the flanges of the cleaning body catcher (109) are joined with the help of dish ends (not numbered) in order to reduce the pressure drop. The outer body of the cleaning body catcher (109) houses a cylindrical mesh (1 15) and a conical shaped mesh (not numbered). The cylindrical mesh (1 15) is installed at an inlet side of the cleaning body catcher (109). The cylindrical mesh (1 15) includes rou nd equidistant holes of 8 mm diameter. The conical shaped mesh is connected to the cylindrical mesh and installed towards an outlet side of the cleaning body catcher (109). The conical shaped mesh includes round equidistant holes of 8 mm diameter. The con ical shaped mesh is further joined to the pipe to facilitate a smooth and efficient collection of cleaning bodies (1 18). The cleaning body catcher (109) is designed in such a way to be fitted in a straight cooling water pipe. The round equidistant holes of the cylindrical mesh (1 15) and the conical shaped mesh allow water to pass there th rough with minimum pressure drop and arrest the cleaning bodies (1 18). The cleaning bodies (1 18) arrested by the cleaning bodies catcher (109) exit through the outlet (142). The outlet (142) is connected to the chamber (103) through the valve (108) and the second check valve (105). The design of the cleaning bodies catcher (109) has reduced/negligible pressure drop.

In an alternate embodiment, the cleaning body catcher (109) is a stationery body having an outer body (not numbered) in a bottle shape as shown in figu re 3B. In this one embodiment, the cleaning body catcher (109) is bottle shaped with the sides parallel to the conical mesh fitted therein. The water outlet pipe (132) connection is made perpendicular to the axis.

Again referring to figures 1 -3B, in an operation, all the cleaning bodies (1 18) are housed in the chamber (103). The cleaning bodies (1 18) rest on the perforated mesh (1 13) initially. The bi-directional pu mp (102) injects and collects the cleaning bodies (1 18) f rom the chamber (1 03) and the clean ing body catcher (109) during the injection cycle and the collection cycle respectively. The controller (121 ) controls the start/stop operation and reverse speed operation of the bi-directional pump (102). The cleaning body catcher (109) catches the cleaning bodies that are injected into the condenser (1 1 0). The arrested cleaning bodies (1 18) are recollected in the chamber (103). Thus, the heat exchanger tubes are cleaned by circulating the cleaning bodies (1 18) along with the water thereth rough.

In another aspect, the present invention provides a method for cleaning a shell and tube heat exchanger. Specif ically, the method is described in conjunction with the system (100) of figure 1 . The m ethod comprises three cycles namely a resting cycle, an injection cycle and a collection cycle that works at an interm ittent interval.

In the resting cycle, as shown in figure 1 , the bi-directional pump (102) is provided with suction from the cooling water outlet pipe (132). The pressure of the cooling water outlet pipe (132) that is connected to the pump suction is always lower than pressure of the cooling water inlet pipe (122), hence the cleaning bodies (1 18) remain in the chamber (103) and cannot be injected unless the bi-directional pump (102) starts and pressurizes the chamber (103).

As shown in figure 4, in the injection cycle the clean ing bodies (1 18) are injected into the tubes of the condenser (1 10). The bi-directional pump (102) starts rotating either in clock wise or in anticlockwise direction and pressurizes the chamber (103). The cleaning bodies are then injected into the condenser inlet pipe th rough the first check valve (104) and the valve (107). The bi-directional pump (102) stops pressurizing once all the cleaning bodies (1 18) are injected. The water flow in the cooling water inlet pipe (122) carries the cleaning bodies (1 18) through the tubes and the cleaning bodies (1 18) comes out and gets arrested at the cleaning body catcher (109) installed at the downstream of the condenser (1 10). The water flows back to the cooling water outlet pipe (132). As shown in figure 5, in the collection cycle the cleaning bodies (1 18) that are arrested in the cleaning body catcher (109) during the injection cycle are collected back into the chamber (103). The bi-directional pump (102) starts rotating in the reverse direction thereby reversing the flow direction. The water and the cleaning bodies (1 18) rested at the cleaning body catcher (109) starts flowing through the valve (108) and the second check valve (105) back to the chamber (103). The cleaning bodies (1 18) are trapped back into the chamber (103) and water flows back to the cooling water outlet pipe (132). Advantages of the invention:

1 ) The system (1 00) functions without using any electrically operated/ actuated valves.

2) The system (100) injects the cleaning bodies (1 18) very fast that is almost simultaneously to have effective cleaning of the tubes.

3) The system (100) uses very less power as the bi-directional pump (102) has very small head and installed near the condenser. The bi-directional pump (102) operates interm ittently for a very small duration for the injection cycle and the collection cycle.

4) The system (100) is more reliable and requires very little maintenance as there are no other moving/ rotating parts except the bi-directional pump (102).

5) The system (100) requires m in imal amount of piping for the installation .

6) The system (100) is very cost effective and offers very attractive return on investment.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such om issions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention.

Claims

I Claim:

1. A system (100) for cleaning a shell and tube heat exchanger, the system (100) comprising:

a cleaning body chamber (103) having,

• an air vent (1 11 ) positioned on a topmost portion thereof for venting the air, the air vent (1 1 1 ) having a man ual ball valve configured therein,

• a drain port (1 12) positioned on a bottom portion thereof, the drain port (1 12) having a manual ball valve configured therein,

• a perforated mesh (1 13) placed therein for holding a plurality of cleaning bodies (1 18),

• a sight glass (1 14) for viewing the quantity of the plurality of cleaning bodies (1 18), and

• a water inlet and a water outlet arranged on either sides thereof ; a bi-directional pump (102) fitted between the cleaning body chamber

(103) and a cooling water outlet (132), the bi-directional pump (102) being capable of rotating and operating in any one of a clockwise direction and an anti clockwise direction to pressu rize/depressurize the cleaning body chamber (103) to inject/ collect the plurality of cleaning bodies (1 18);

a controller (121 ) for controlling an operation of the bi-directional pump (102);

a first check valve (104) connected to a cooling water inlet (122) for injecting the plurality of cleaning bodies (1 18) from the cleaning body chamber (103) into a condenser (1 10);

a cleaning body catcher (109) installed at an outlet of the condenser (1 10) for arresting the plurality of cleaning bodies (1 18), the cleaning body catcher (109) having an outer body and flanged ends, the outer body housing a cylindrical mesh (1 15) and a conical shaped mesh therein; a second check valve (105) connected to an outlet (142) of the cleaning body catcher (109) for carrying the plurality of cleaning bodies (1 18) theref rom to the cleaning body chamber (103); and

a plurality of valves (1 01 , 107, 108),

wherein, the heat exchanger tubes are cleared by circulating the cleaning bodies (1 18) along with a water therethrough.

2. The system (100) as claimed in claim 1 , wherein the cleaning body chamber (1 03) is a vessel having a half conical shape at a top portion and a dish shape at a bottom portion thereof.

3. The system (1 00) as claimed in claim 1 , wherein the cleaning bodies (1 18) are selected from any one of sponge balls and spherical bodies made of flexible material like silicon of diameter slightly larger than an internal diameter of the tubes of the heat exchanger.

4. The system (100) as claimed in claim 1 , wherein the controller (121 ) is a programmable logic controller based electronic controller. 5. The system (100) as claimed in claim 1 , wherein the outer body of the cleaning body catcher (109) has a cylindrical shape.

6. The system (100) as claimed in claim 1 , wherein the outer body of the cleaning body catcher (109) has a bottle shape.

7. The system (1 00) as claimed in claim 1 , wherein the cylindrical mesh (1 15) and the conical shaped mesh includes round equidistant holes of 8 m m diameter.

8. The system (100) as claimed in claim 1 , wherein the plurality of valves (101 , 107, and 108) is manual ball valves.

9. A method for clean ing a shell and tube heat exchanger, the method comprising:

• an injection cycle having the steps of

rotating a bi-directional pump (102) in any one of a clockwise direction and an anticlockwise direction to pressurize a cleaning body chamber (103), wherein, an operation of the bi-directional pump (102) is controlled by a controller (121 );

injecting plurality of cleaning bodies (1 18) from the cleaning body chamber (103) into a condenser (1 1 0) through a first check valve (1 04) and a manual valve (107),

stopping the bi-directional pump (102) once all the cleaning bodies (1 18) injected,

carrying cleaning bodies (1 18) along with water through tubes of the condenser (1 10); and

arresting the cleaning bodies (1 18) com ing out of the condenser (1 10) in a cleaning body catcher (109) installed at a downstream of the condenser (1 10), wherein the cleaning body catcher (109) having an outer body and flanged ends, the outer body housing a cylindrical mesh (1 15) and a conical shaped mesh therein;

• a collection cycle having the steps of

rotating the bi-directional pump (102) in the reverse direction thereby reversing the flow direction ,

collecting the plurality of cleaning bodies (1 18) arrested in the cleaning body catcher (109) back into the cleaning body chamber (103) th rough a second check valve (105) and a manual valve (108); and • a resting cycle, wherein the cleaning bodies (1 18) remain in the cleaning body chamber (103) till the start of the bi-directional pump (102).

10. The method as claimed in claim 9, wherein the cleaning bodies (1 18) are selected from any one of sponge balls and spherical bodies made of flexible material like silicon of diameter slightly larger than an internal diameter of the tubes of the heat exchanger.

1 1. The system (100) as claimed in claim 9, wherein the controller (121 ) is a programmable logic controller based electronic controller.

12. The system (100) as claimed in claim 9, wherein the outer body of the cleaning body catcher (109) has a cylindrical shape. 13. The system (100) as claimed in claim 1 , wherein the outer body of the cleaning body catcher (109) has a bottle shape.

14. The system (1 00) as claimed in claim 9, wherein the cylindrical mesh (1 15) and the conical shaped mesh includes round equidistant holes of 8 mm diameter.