WO2016043594A1

WO2016043594A1 - A method and a system for cleaning cooling pipes in heat exchangers

Info

Publication number: WO2016043594A1
Application number: PCT/NO2015/000022
Authority: WO
Inventors: Egil FALLMYR; Morten HARSVIK
Original assignee: Multi Solutions As
Priority date: 2014-09-19
Filing date: 2015-09-18
Publication date: 2016-03-24
Also published as: NO337291B1; NO20141141A1

Abstract

A method for the cleaning of a bundle of pipes (112) in a heat exchanger fitted in a holder (113) is described, where the pipe bundle is brought into contact with a liquid like cleaning agent to remove the impurities from the pipe surfaces in the pipe bundle. It is characterised in that an upward, open bag-formed casing (1) is brought to surround the pipe bundle and its upper opening rim is fastened in the holder unit (113) of the exchanger-pipe bundle (12) and the bag is supplied with and filled up with cleaning agent which thereby comes into contact with the pipe surfaces, whereupon the cleaning agent with the removed impurities is removed from the bag form (1). The system according to the invention is characterised by - a first unit A comprising an upward, open bag-formed casing (bag) (1) designed to surround the cooling pipes and means for fastening to the cooling box, and also means for connecting pipes/hoses for the supply of the cleaning agent and a removal for the used cleaning agent, said pipes/hoses are connected with another unit B, where the unit B comprises a container for cleaning agent, outflow pipe pieces to connect hoses to the bag (1), and also pump(s) for the delivery of fluid/cleaning liquid, a motor for the operation of the pumps and also a filter unit for cleaning and further handling of used cleaning agent from the bag, and return (recirculation) of cleaned cleaning agent to the bag (1).

Description

A METHOD AND A SYSTEM FOR CLEANING COOLING PIPES IN

HEAT EXCHANGERS

The present invention relates to a method and a device for the cleaning of the fluid- carrying pipes in connection with heat exchangers, as can be seen in the

introduction of the subsequent claims 1 and 7. In particular, one aims to clean the cooling pipe surfaces of heat exchangers of the box coolers type. Also described is a use of the method and the system. With fluid-carrying pipes one considers, in particular, the pipe circuits that bring forward the fluid that shall be heated up or be cooled down by the heat exchange. In connection with box coolers, these are cooling pipes where the fluid shall be cooled by the surrounding seawater.

Today, a large number of box coolers are used on board ships, and these must be cleaned regularly to maintain their effectivity. With today's solutions for cleaning, the box cooler must be dismantled while the ship is in a harbour/dry dock and the cooler is flushed clean. See the description later in this document.

Prior art:

With regard to prior art, reference is made to the following patent publications:

DE10202406 describes external cleaning of radiators. Liquid-carrying nozzles are placed on the top side. On the bottom side the liquid is captured in a container and is recycled/pumped back to the nozzles. DE20004531 relates to the cleaning of the outside of convectors/radiators. The radiator is surrounded from above with a watertight foil that extends vertically towards a container /dish that lies below to receive the liquid from the liquid-carrying nozzles placed on the top side of the radiator. Here, the cleaning can take place without dismantling of the convector.

DE-202012007061 relates to a device similar to the one described in DE10202406. Here, a final treatment with clean water is carried out. DE-19725631 relates to flushing of radiators, similar to the above mentioned publications. The flushing water is recirculated and can be cleaned by using filters. WO00/78605 describes a device to, among other things, prevent or protect against marine growth on the cooling pipes of the box coolers on ships by increasing the temperature.

The first of the given publications does not relate to cleaning of box coolers on board ships, but relates to cleaning of the outside of the radiators with the help of flushing equipment. WO00/78605 does not describe the placing of a watertight bag around the pipe bundle of the cooling pipes and that the bag is filled with a cleaning agent for the cleaning of the cooling pipes. It is an aim of the invention to provide a method and a device that will make the cleaning of the heat exchanger pipes in box coolers simpler and more reliable than previously known.

The present invention relates to a method for the cleaning of a pipe bundle in a heat exchanger fitted in a holder, where the pipe bundle is brought into contact with a liquid-formed cleaning agent to remove impurities from the pipe surfaces in the bundle of pipes, characterised in that an upward, open bag-formed casing is made to surround the pipe bundle, and its upper opening brim is fastened to the holding unit of the exchanger-pipe bundle, and the bag is supplied and filled up with a cleaning agent which thereby comes into contact with the pipe surfaces whereupon the cleaning agent, with the removed impurities, is removed from the bag-form.

In one embodiment, the cleaning agent is fed into a lower part of the bag to come into contact with the pipes and is removed together with the impurities from an upper part of the bag. In one embodiment, the cleaning agent is sprayed out through appropriate nozzles and directly towards the pipe surfaces by being supplied via a separate cleaning agent circuit. In one embodiment, the cleaning agent is sprayed out through adapted nozzles placed in the upper part of the bag.

In one embodiment, the cleaning agent is brought to the two circuits by pumping from a common pump body in the unit (the pump housing) (B).

In one embodiment, used cleaning agent is received in the unit (B) and recirculated in that the impurities are separated out and retained, while the cleaned cleaning agent is returned to the cleaning agent circuits to be supplied to the bag. In a second aspect, the present invention relates to a system for cleaning of a fluid- carrying pipe bundle in a heat exchanger fitted in a holder characterised by

- a first unit A comprising an upward, open bag-formed casing (bag) designed to surround the pipes, and means for the fastening to the cooling box, and also means for connection of pipes/hoses for the supply of the cleaning agent and side- streaming of the used cleaning agent.

In one embodiment, said pipes/hoses are connected to another unit B, where

the unit B comprises a container for the cleaning agent, outlet pipe pieces to connect hoses to the bag, and also pump(s) for the delivery of fluid/cleaning liquid, a motor for the operation of the pumps and also a filter unit for the cleaning and further handling of the used cleaning agent from the bag, and return (recycling) of cleaned cleaning agent to the bag.

In one embodiment, the unit A with an upward, open bag is set up to surround the pipe bundle and comprises an inlet in the lower part for the supply of the cleaning agent and an upper outlet to remove the cleaning agent as the inlet and outlet, respectively, are connected to associated pipes connected to the unit B for cleaning agent, in a first cleaning agent circuit and that comprises pumps for the supply of cleaning agent through pipes/hoses, and also filter equipment for the removal of impurities in the used cleaning agent, so that clean cleaning agent can be recirculated to the bag.

In one embodiment, the system comprises a further cleaning agent circuit comprising a number of pipes with spraying nozzles that are arranged on the carrier frame of the bag in its upper part and comprises mouth pieces with spraying nozzles that are directed towards the pipe surfaces.

In one embodiment, the bag is manufactured from a flexible, watertight cloth, in particular, a reinforced, flexible plastic cloth which is thereby easy to fit onto and around the cooling pipes.

In a third aspect, the present invention relates to use of a method or a system as given above, for the cleaning of heat exchanger pipes in cooling boxes on board ships, where the cooling box is placed in a bottom section of the ship and where an insulated circulation circuit of fluid (gas liquid) is cooled in a heat exchange with seawater.

In a preferred embodiment of the invention, the method and system according to the preceding claims are applied to the cleaning of heat exchanger pipes in cooling boxes on board ships, where the cooling box is placed in a bottom section of the ship, and where an insulated circulation circuit of fluid (gas liquid) is cooled in heat exchange with seawater (fresh water in a lake or ocean saltwater).

However, the method and the system according to the invention can also be used on cooling boxes that are not placed on board ships, such as, for example, on a rig. As cooling boxes on ships are the first practical embodiment of the invention, such cooling boxes on ships are used to describe and exemplify the invention. In more detail, the device constitutes a large open bag that is fed, from below and upwards, outside the box cooler. The bag is manufactured from a watertight cloth material. The box coolers are normally fastened to the ship, such as the framework or hull of the ship, at the top section of the box coolers, so that the bag and the vertical wall sections of the set of cooling pipes are freely exposed and accessible. The bag has fastening means in its top section and can be fitted in the top section of the cooler, or directly to the ship (framework) above the cooler. Now, the bag surrounds the whole of the cooler with its cooling ribs. Cleaning liquid can be supplied to the bottom section of the bag. The bag is gradually filled with the liquid and the liquid level rises to the top. The liquid will flow around the cooling pipes in each cooling pipe set and will then flow out through the adapted outlet adjoining the upper brim edge section of the bag. The cleaning fluid that is suppled from below will now flow around the pipes and clean all the pipe parts in the box cooler. According to one embodiment, the bag is fastened with longitudinally running pipelines (given as 4 in figure 2), and these are fitted with a number of nozzles for the spraying of the pipe sticks in the box cooler.

The supply of cleaning water from the bottom section of the bag or from above with the help of nozzles is also a technique that is not described in the publications referred to.

The invention shall now be described in more detail in the following with reference to the enclosed figures, in which:

Figure 1 shows a typical application of cooling boxes on a ship and for which the present invention can be used.

Figure 2 shows the principle for cleaning a system where the bag 1 (unit A) surrounds the cooler 3, as the cleaning fluid is recirculated (and is cleaned) via the container (4), also given as unit B, the pump house. Figure 3 shows in more detail the bag (container 1 ) and the pipelines for the supply and outlet of cleaning liquid and the pipelines with nozzles for spraying.

Figure 4 shows a side outline of the unit in figure 3.

Figure 5 shows a cross-section of the bag according to figure 3, while figure 6 shows an even larger section of a detail in figure 5.

Figure 1 shows a typical application of cooling boxes with heat exchanger pipes placed at the bottom of a ship, and where an insulated circulation circuit of fluid (gas liquid) is cooled in a heat exchange with seawater. The figure shows a lower section of the hull/cooling section 100 of a ship, where fitted inside the section 101 in the hull is a heat exchanger 1 10 with heat exchanger pipes 1 12 mounted in bundles. The bundle of pipes 1 12 is fastened to a frame 1 13 in an above-lying deck 1 14, and is freely suspended downwards in the room 101 where seawater from the outside can freely flow in and out through openings/grids 1 15 and 1 16, respectively, in the hull side and/or the bottom of the hull.

At the top, the heat exchanger 1 10 comprises necessary fittings, such as pumps, to make the fluid flow through the cooling circuit, or this can be carried out from other locations on the ship. The top plate 1 13 comprises outlets that are connected to each pipe.

In the concrete case, the fluid (gas liquid) in the pipe circuits 1 12 will be cooled by the colder seawater. The cooled fluid is then used for different cooling needs inside the ship, such as in cool rooms and to drive the air conditioning units on board.

As the cooling pipes are in contact with seawater from the free body of seawater, a covering (growth) on the surfaces of these pipes 1 12 is formed, something which over time reduces the heat exchange capacity. Therefore, there is a need to clean the pipes at regular time intervals. Today, this is carried out, for example, in that the whole pipe circuit 1 12 with the frame 1 13 must be dismantled and be removed from the ship to be flushed clean with a cleaning agent at an appropriate cleaning station, whereupon the frame with the pipes is screwed back to the deck 1 14 again and the use of the heat exchanger can start up again.

It has been found that this is a time demanding and costly process and it is an aim to provide an improved cleaning method. In particular, it is an aim to be able to carry out the cleaning without having to dismantle the frame with the pipe circuits 1 12.

Figure 2 shows a system that will be able to do this, i.e. without that pipe circuit being dismantled. The figure shows the two units A and B of the system.

The unit A comprises a bag to surround the cooling pipes and means for fastening it to the cooling box.

The unit B comprises a container for the cleaning agent, outlet pipe pieces to connect hoses to the bag, and also pump(s) for delivering the fluid/cleaning liquid, a motor for operation of the pumps and also a filter unit for cleaning and further handling of used cleaning agent from the bag and return of cleaned cleaning agent to the bag. The unit A comprises a bag, sack or an upward, open watertight container 1 with means for supplying and removing the cleaning liquid to the room inside the bag. The figure at A is shown with the bag that surrounds the exchanger pipes 1 12.

The unit B is a box-formed apparatus - with a pump house - and which comprises a series of instruments for the handling of the cleaning agent, a chamber to contain clean cleaning agent, a chamber for the return of used cleaning agent and a filtration unit for removal of impurities, pumps and motor(s), such as electro motors for the operation of these, for the recirculation of the cleaning agent.

These instruments are fitted in a rack 40 (figure 2), generally with legs on wheels, and comprise couplings for the connection of hoses that lead to and from,

respectively, the bag, a pump to bring the cleaning liquid inside the bag in a unit A through suitable pipes/hoses (the two circuits that are shown in figure 2), and to receive the cleaning fluid with impurities from the pipe surfaces in return. The box also encompasses a cleaning unit in the form of a filter unit that removes the impurities and a storage chamber for cleaned cleaning liquid that can then be led in return to the bag, i.e. that a recirculation of cleaning liquid is set up.

The box B is a mobile unit that is easy to carry, as hoses can easily be disconnected, and is stretched up to the bag construction (unit A) for connection to this.

As a cleaning agent, liquids such as water or suitable liquid chemicals can be used, and which can contain additives/materials that can promote the cleaning of the pipe surfaces for growth (marine shells) and impurities. The system also has the possibility to provide a cleaning liquid such as hot water at a suitable temperature up to 89-90 degrees Celsius.

The top plate 1 13 and the cooling pipes 1 12 are shown uppermost in the unit A in figure 2. The top plate 1 13 can be a hollow box, i.e. the same 1 13 which is shown in figure 1 , and can encompass a part of the fastening mechanism for temporary fastening and holding the top edge of the bag 1 in place. The set of cooling pipes extends downwards below the plate 1 13.

In figure 2, the bag 1 is placed up and around the cooling box 1 12,1 13. The bag 1 is a watertight cloth such as a plastic that is opened upwards. A frame-form 12 is integrated around the upper brim edge 1 1 of the bag 1 , and which is used in the fastening to the cooling box and which contributes to keeping the opening wide open. At the bottom of the bag 1 , i.e. adjoining the bag bottom 14, a pipe piecel 3 is integrated for the connection to an external hose 5 from the unit B for delivery of cleaning agent to the bag or removal from the bag. In the upper part, at the brim edge 1 1 , a pipe piece 15 is also integrated for delivery/withdrawal of cleaning agent to/from the bag via the hose 9 back to the pump house B.

The bag 1 is manufactured from a flexible, watertight cloth, in particular, a reinforced, flexible plastic cloth which is thereby easy to install up and around the cooling pipes. Such construction is necessary as it shall be adapted to be displaced inside the chamber 101 in the bottom part of the ship, with limited space, to be positioned in under the cooling pipe bundle 1 12, and then be pulled up around the pipe bundle 1 12. It is a great advantage with the invention that the bag 1 which is used in the cleaning has a flexible form, i.e. that it is very simple to fit and dismantle after the cooling pipes have been cleaned. In addition to that the liquid can be delivered via the pipe piece 13, the system also includes that the frame to which the upper brim edge 1 1 of the bag is fastened comprises a number of pipes with spray nozzles that are made to spray out the cleaning liquid more directly towards the cooling pipe surfaces. In the example in figure 1 , three such mutually parallel pipes 16,17,18 are shown, where the two outermost, no. 16 and 18 lie in parallel with their own longitudinally running brim edge opening of the bag 1 , while the middle pipe 17 remains lying in the middle of the opening of the bag 1 . The pipes are assembled in a square frame form with the help of crossways rails 27 and 29, respectively, one at each end of the brim edge opening of the bag, see figure 3. It can be seen in figure 6 that the rails around the circumference comprise a number of fastening eyelets or holes 31 that are used to fasten the bag construction 1 to the cooling pipe frame 1 12, so that the bag sits securely in place and can withstand the weight it is subjected to by the water that fills the bag 1 . When the cooling pipe loops in a box cooler can comprise units of a given mutual distance apart uppermost in the box, the frame formed by pipes 16-17-18 and the rails 27,29 can, to some extent, be placed on top so that, for example, the middle pipe 17 lies between the two such cooling pipe units, cf. as outlined in figure 3.

The three pipes 16,17,18 are fluid- connected with a common supply hose 7 from the pump box A. Branching hoses 19,20,21 run from a common manifold connection at 19 and further into the parallel pipes 16,17,18. Each parallel pipe comprises a number of mouth pieces with spraying nozzles 125 that are set to spray towards the pipe surfaces. This means that the cleaning agent can be supplied uppermost 15 in the bag 1 , and be removed from the bottom 13, or vice-versa. It is most preferred to supply the cleaning agent into the bag 1 via the lowest pipe piece 13, and remove the cleaning agent with impurities from the uppermost pipe piece 15. By pumping the cleaning agent in at the bottom, it will be possible to collect the impurities that float up in an upper layer of liquid in the bag 1 .

In that the cleaning liquid is pumped into the bag 1 at a suitable pressure, such as in a powerful jet stream, one gets a circulation of the liquid around the individual pipes in the cooling circuit 1 12, something that reinforces the cleaning of the pipe surfaces. In addition, the liquid can be water that contains very powerful cleaning additives, for example, soap materials that improve the cleaning.

By the presence of the pipes 16-18 with spray nozzles, the cooling pipes 1 12 can thereby be cleaned in two modes. The one is that the cleaning agent is pumped in through the pipe piece 1 3 and is removed via the pipe piece 15, at the same time as cleaning fluid is sprayed towards the cooling pipes through the nozzles 125.

When one starts the cleaning, one mode can be to pump in liquid until the bag 1 is completely full and then stop the pumping in and allow the liquid in the bag 1 to stand for a while to let the liquid cleanse the pipe surfaces before the liquid with the impurities such as solid flakes, particles or liquid dissolved impurities, is removed from the bag. This filling mode can continue until the surfaces of the pipes 1 12 are clean.

Thereafter, the bag 1 can be emptied completely and coupled from the cooling box inside the chamber, whereupon the cooling box can restart its normal heat exchanger function in the ship.

With the present invention, where a flexible upward open bag is used to surround a cooling box, a solution is provided that eliminates the time consuming and costly cleaning operations that have been used until now. Therefore, it represents a huge forward step in the area related to cleaning of cooling boxes.

Claims

1 . Method for the cleaning of a bundle of pipes (1 12) in a heat exchanger fitted in a holder (1 13), where the pipe bundle is brought into contact with a liquid cleaning agent to remove impurities from the pipe surfaces in the pipe bundle, characterised in that an upward, open bag-formed casing (1 ) is brought to surround the pipe bundle, and its upper opening brim is fastened in the exchanger-pipe bundle (1 12) holder unit (1 13) and the bag is supplied with and filled up with cleaning agent which thereby comes into contact with the pipe surfaces, whereupon the cleaning agent with the removed impurities is pulled away from the bag form (1 ).

2. Method according to claim 1 , characterised in that the cleaning agent is brought into a lower part (13) of the bag to come into contact with the pipes (1 12) and is removed together with the impurities from an upper part (15) of the bag.

3. Method according to claim 1 , characterised in that the cleaning agent is sprayed out through appropriate nozzles (125) and directly towards the pipe surfaces by the supply via a separate cleaning agent circuit (7-19,20,21 -16,17,18).

4. Method according to claim 3, characterised in that the cleaning agent is sprayed out through appropriate nozzles (125) arranged in the upper part of the bag-form

(1 )-

5. Method according to one of the preceding claims, characterised in that the cleaning agent of the two circuits is brought forward by pumping from a common pump body in the unit (the pump house) (B).

6. Method according to one of the preceding claims, characterised in that the return of used cleaning agent is received in the unit (B) and recycled in that the impurities are separated and retained, while the clean cleaning agent is returned to the cleaning agent circuits for supply to the bag (1 ).

7. System for the cleaning of a fluid-carrying bundle of pipes (1 12) in a heat exchanger fitted in a holder (1 13), characterised by

- a first unit A comprising an upward, open bag-formed casing (bag) (1 ) designed to surround the pipes in the pipe bundle, and means for fastening to the heat exchanger, and also means for connection of pipes/hoses for the supply of the cleaning agent and a removal for the used cleaning agent.

8. System according to claim 7, characterised in that the pipes/hoses are connected to another unit B, where

the unit B comprises a container for a cleaning agent, outlet pipe pieces to connect hoses to the bag (1 ), and also pump(s) for the delivery of fluid/cleaning liquid, a motor for operation of the pumps and also a filter unit for cleaning and further handling of the used cleaning agent from the bag, and return (recycling) of cleaned cleaning agent to the bag (1 ).

9. System according to claim 8, characterised in that the unit A with the upward, open bag (1 ) is set up to surround the pipe bundle and comprises an inlet (15) in the lower part for supply of the cleaning agent, and an upper outlet (13) for removal of the cleaning agent, as

the inlets (13) and outlets (15), respectively, are connected to associated pipes connected to the unit (B) for the cleaning unit, in a first cleaning agent circuit, and which comprises pumps for delivery of the cleaning agent through pipes/hoses, and also filter equipment for removal of impurities in the used cleaning agent so that clean cleaning agent can be recycled to the bag (1 ).

10. System according to claims 7-9, characterised in that a further cleaning agent circuit comprising a number of pipes with spraying nozzles that are arranged connected to the carrier frame (16-17-18; 27,29) of the bag (1 ) in its upper part, and comprises mouth pieces with spraying out nozzles (125) that are directed towards the pipe surfaces (1 12).

1 1 . System according to one of the claims 7-10, characterised in that the bag (1 ) manufactured from a flexible watertight cloth, in particular, a reinforced flexible plastic cloth, which thereby is easy to fit up and around the cooling pipes.

12. Application of a method and a system according to the preceding claims for the cleaning of heat exchanger pipes in cooling boxes on board ships where the cooling box is placed in a bottom section of the ship and where an insulated circulation circuit of fluid (gas liquid) is cooled in a heat exchange with seawater.