GB2520229A

GB2520229A - Nozzle, Apparatus and Process for Dispensing Dry Ice

Info

Publication number: GB2520229A
Application number: GB1312523.2A
Authority: GB
Inventors: Richard Nimmons; David Ernest Nimmons
Original assignee: DRY ICE INTEGRATION Ltd
Current assignee: DRY ICE INTEGRATION Ltd
Priority date: 2013-07-12
Filing date: 2013-07-12
Publication date: 2015-05-20
Also published as: GB201312523D0

Abstract

A nozzle 12 for use in dispensing dry ice pellets comprises an inlet 28, an outlet 30, a hollow shaft 32 (pipe) between the inlet and outlet wherein the width of at least part of the hollow shaft is smaller than the width of the outlet. The nozzle may have a biconcave shape. A hose 14 may be connected to the nozzle and a source of dry ice pellets 20 is in fluid communication with the hose. The nozzle and hose may be of a size to fit inside a conduit 100 that may be condenser / heat exchange tube requiring cleaning by the dry ice pellets. Compressed air from a compressor (34, fig 2) passing through the nozzle may impart motion to the dry ice. A vacuum pump (36) may impart suction to the conduit. Scale inside the conduit may be detected using electromagnetic or sound waves 24, 26 and a monitoring device (42) may comprise feedback to control the position of the nozzle to direct the dry ice pellets to where scale is required to be removed.

Description

NOZZLE, APPARATUS AND PROCESS FOR DISPENSING DRY ICE

Field of the Invention

The present invention relates generally to a nozzle for use in the dispensing of dry ice, and in particular to the use of dry ice to clean scale and the like from devices having conduits, such as heat exchangers and cooling condensers. In one aspect the present invention relates to an apparatus for use in dry ice cleaning, and in another aspect the present invention relates to a cleaning process using dry ice.

Background of the Invention

Many industrial processes involve the use of heat exchangers or cooling condensers. These are often in the form of a series of tubular pipes connected by U-bends or similar in order to create a continuous serpentine arrangement, and can extend to a continuous flow path of nine metres or more. Cooling condensers are often used in power stations that generate steam, the steam being cooled to generate liquid water.

Specifically, the steam generated by the turbine passes through a cooling condenser in order to be cooled before exiting the boiler. The temperature differential between steam entering the boiler and the water exiting the condenser helps to drive the overall steam cycle. However, the cooling of the steam also results in impurities in the steam precipitating on the inside surface of the cooling condenser, resulting in fouling or the build-up of scale. For example, it is known that calcium carbonate collects on the inside surface of power station cooling condensers.

In power stations, the build-up of scale in condenser tubes restricts the flow of water and therefore heat transfer performance, thereby reducing turbine performance. Clean condenser tubes enable a greater heat transfer, and therefore better cooling efficiency. This improves turbine performance.

Many different techniques have been used to clean scale from the inside of cooling condensers. For example, treating with nitric acid is commonly used. However, nitric acid is extremely corrosive, and its use is associated with a high level of risk. Furthermore, as it is so corrosive, nitric acid damages the inside surface of the cooling condenser. This process also generates highly corrosive waste, which must be handled and disposed of safely.

An alternative method of cleaning the inside of cooling condensers is by using ultra high pressure water (up to 3,000 bar). However, this technique creates a large volume of liquid waste, and requires the use of a very large quantity of water. Furthermore, it requires a significant amount of energy to generate ultra high pressure.

A further alternative method of cleaning the inside of cooling condensers is to use an abrasive scrubbing device such as a wire brush. This technique is extremely laborious and is quite ineffective, often leading to imperfect cleaning. Furthermore, the use of abrasive scrubbing devices leads to scoring of the internal surface of the cooling condenser (i.e., physical damage). This shortens the lifespan of the condenser, and presents scored areas where the build-up of scale is more likely to take place, thus exacerbating the problem and making blockages more likely.

There is therefore a need for a device, apparatus and/or method for cleaning the inside of cooling condensers or the like, which mitigates damage to the inside surface of the cooling condenser, which effects good cleaning, and which is safer and more environmentally friendly.

The use of dry ice (frozen carbon dioxide (C02)) to clean surfaces has been known for some time. One of the reasons for using dry ice for cleaning is that it sublirnates from a solid directly to a gas, thus leaving no residue. Typically, dry ice is forced through a nozzle under high pressure, forcing the dry ice to sublimate when it hits the surface of an object to which it is directed. However, current dry ice cleaning technology suffers from several limitations and drawbacks. For example, the nozzles that are currently used tend to choke and release, which stops the sublimation and which can cause a build-up of solid dry ice, making dry ice cleaning all but impossible to achieve in confined spaces, such as piping.

Therefore, it is an object of the present invention to obviate, or at least mitigate, at least some of the drawbacks associated with the prior art.

Further aims and objects of the invention will become apparent from a

reading of the following description.

Summary of the Invention

According to a first aspect of the invention there is provided a nozzle for use in dispensing dry ice pellets, said nozzle comprising an inlet, an outlet and a hollow shaft located between said inlet and said outlet, wherein the width of at least part of the hollow shaft is smaller than the width of the outlet.

Typically, the width of at least pad of the hollow shaft proximal to the outlet is smaller than the width of the outlet.

The width of at least part of the hollow shaft may be smaller than the width of the inlet.

The width of the hollow shaft may taper between the inlet and the outlet, said hollow shaft having a smaller width than the width of the inlet and the outlet.

Typically, the width of the hollow shaft is largest in proximity to the inlet and the outlet.

The width of the hollow shaft may be smallest approximately half way along its length.

At least part of the nozzle in cross section may be biconcave-like in shape.

Typically, the biconcave-like shape terminates at one end at the outlet.

According to a second aspect of the invention, there is provided an apparatus for use in dispensing dry ice pellets, said apparatus comprising: a nozzle for use in dispensing dry ice pellets; a hose or the like fluidly attached to the nozzle; a source of dry ice fluidly connected to the hose or the like; and a means for applying motion to the dry ice, said motion directing said dry ice through the nozzle.

Dry ice (frozen carbon dioxide (Ca2)) sublimates from a solid directly to a gas, thus leaving no residue.

The means for applying motion may be a compressed fluid, optionally a compressed gas.

Typically, the means for applying motion is a compressor.

The nozzle and hose or the like may be sized and shaped to fit inside a conduit or the like.

The source of dry ice may be a hopper in fluid connection with the hose or the like.

The hopper may be in fluid connection with the means for applying motion to the dry ice.

The apparatus may further comprise a means for imparting suction to a conduit or the like.

The means for imparting suction to a conduit or the like may be a vacuum pump configured to attach to said conduit or the like.

Typically, the apparatus further comprises a means for detecting scale or the like on an inside surface of a conduit.

The means for detecting scale or the like may comprise: one or more sources of electromagnetic or sound waves configured to reflect off the inside surface of the conduit and/or scale or the like attached thereto; and one or more detectors, configured to detect the electromagnetic or sound waves.

The one or more sources of electromagnetic or sound waves may be a laser.

The means for detecting scale or the like on an inside surface of a conduit may be located between the nozzle and the hose.

Typically, the nozzle has an inlet fluidly connected to the hose, and an outlet for dispensing dry ice or the like, said means for detecting scale or the like on an inside surface of a conduit being located between the nozzle outlet and the hose.

Typically, the nozzle has an inlet fluidly connected to the hose, and an outlet for dispensing dry ice or the like, said means for detecting scale or the like on an inside surface of a conduit being located between the nozzle outlet and the source of dry ice.

The apparatus may further comprise a monitoring device for monitoring the detection scale or the like on an inside surface of the conduit.

Typically, the monitoring device comprises a feedback mechanism, said feedback mechanism being configured to control the position of the nozzle.

The apparatus may comprise the nozzle of the first aspect.

According to a third aspect of the invention there is provided a process for cleaning the inside of a conduit or the like having an inside surface, said process comprising the steps of: providing a nozzle sized and shaped to fit inside said conduit or the like; providing dry ice in pellet form or the like; inserting the nozzle into an orifice in said conduit or the like; and imparting motion to said dry ice such that said dry ice is dispensed from the nozzle in the direction of the inside surface of the conduit.

The process as described can be used to detach scale or the like from the inside surface of the conduit.

The nozzle may be fluidly attached to the hose or the like shaped to fit inside said conduit or the like.

The dry ice may be dispensed from the nozzle at an angle of less than approximately 45° relative to the longitudinal plane of the nozzle.

The motion of the dry ice may be accelerated in the nozzle section.

The motion may be imparted by a compressed fluid, optionally a compressed gas.

The process may comprise the further step of applying a vacuum at an orifice in said conduit or the like to remove debris created by the cleaning process.

The vacuum may be applied at an orifice other than the orifice at which the nozzle is inserted.

The process may comprise the further step of detecting scale or the like on the inside surface of the conduit.

The detection of scale or the like may be performed on the inside surface of the conduit after the inside surface of the conduit has been cleaned.

The conduit may be a pipe, said pipe having an inside surface.

The pipe may be pad of a heat exchanger or a cooling condenser.

Brief Description of the Drawings

There will now be described, by way of example only, embodiments of the invention with reference to the following Figures, of which: Figure 1 shows a side view of part of a dry ice cleaning apparatus; and Figure 2 shows a schematic view of a dry ice cleaning apparatus.

Detailed Description

Referring to Figure 1, there is shown at 10 part of a dry ice cleaning apparatus having a nozzle 12 and a hose 14, and being inserted pad way into a cooling condenser tube 100. The cooling condenser tube 100 has a diameter of approximately half an inch (circa. 1.3 cm). The hose 14 and nozzle 12 are fed into the cooling condenser tube 100 by a hose feeder controller 16, equipped with rollers 18 for moving the hose 14 and nozzle 12 in and out of the cooling condenser tube 100.

Attached to the hose 14 at the opposite end to the nozzle 12 is a dry ice hopper 20, which acts as a source of dry ice. Also attached to the dry ice hopper 20 is tubing 22 which connects to an air compressor (not shown), which acts as a source of compressed air.

The nozzle 12 is equipped with lasers 24 and detectors 26, which act as means for detecting scale. The nozzle 12 has an inlet 28 and an outlet 30 between which is a hollow shaft 32. As can be seen, the width of the hollow shaft 32 is in part smaller than the width of the outlet 30, and is also smaller than the width of the inlet 28. In particular, the width of the hollow shaft 32 is largest in proximity to the inlet 28 and the outlet 30. The width of the hollow shaft 32 proximal to the outlet 30 is smaller than the width of the outlet 30, and the width of the hollow shaft 32 is smaller than the width of the inlet 28. As can also be seen, the width of the hollow shaft 32 tapers between the inlet 28 and the outlet 30.

In cross section, the nozzle 12 is in part biconcave-like in shape, the biconcave-like shape terminating at one end at the outlet 30, the width of the hollow shaft 32 being smallest approximately half way along the length of the biconcave-like shaped section.

Also shown by way of a dashed line is a longitudinal plane through the nozzle and an angle of 45° relative to that longitudinal plane.

Referring now to Figure 2, there is shown at 200 a schematic dry ice cleaning apparatus having a nozzle 12 and a hose 14 fluidly connected to an inlet 28 of the nozzle 12, and being inserted part way into a cooling condenser tube 100. The nozzle 12 and hose 14 are sized and shaped to fit inside the conduit 100. The nozzle 12 also comprises an outlet 30 for dispensing dry ice. The cooling condenser tube 100 has a diameter of approximately half an inch (circa. 1.3 cm). Fluidly attached to the hose 14 at the opposite end to the nozzle 12 is a dry ice hopper 20, which acts as a source of dry ice. Also fluidly attached to the dry ice hopper 20 via tubing 22 is an air compressor 34, which acts as a source of compressed air. The air compressor 34 acts as a means for applying motion to the dry ice, thereby directing the dry ice through the nozzle 12.

Alternative methods of applying motion to the dry ice may be used, such as mechanical projection. Typically, motion is applied using a compressed fluid, most typically a compressed gas such as compressed air.

Still referring to Figure 2, the apparatus 200 is equipped with lasers 24 and detectors 26, which act as means for detecting scale. The lasers 24 and detectors 26 are located between the nozzle 12 and the hose 14, and can also be located between the nozzle outlet 30 and the hose 14, or between the nozzle outlet 30 and the dry ice hopper 20. The lasers 24 and detectors 26 are typically located in proximity to or on the nozzle 12.

The lasers 24 are sources of electromagnetic waves and are configured to reflect off the inside surface of the conduit 100 and/or scale or the like attached thereto. The detectors 26 are configured to detect the reflected light from the laser 24 after it has reflected off the inside surface of the conduit 100 and/or scale or the like attached thereto.

Alternative electromagnetic waves can be used, and alternative ways of detecting scale such as sound waves (in particular ultrasound) can also be used. The detectors 26 can be chosen to detect the type of electromagnetic or sound waves used.

Referring once again to Figure 2, a monitor 42 acting as a monitoring device shows a user which parts of the inside surface of the cooling condenser 100 are clean, and which still retain scale. Thus a user can decide how to direct the cleaning process.

In one embodiment, the monitor 42 comprises a feedback mechanism which controls the position of the nozzle 12 in an automated fashion.

Again referring to Figure 2, there is provided a vacuum pump 36 which attaches to the cooling condenser 100 at an end at which the nozzle 12 and hose 14 are not inserted. The vacuum pump 36 acts as a means for imparting suction. The vacuum pump 36 removes a scale, debris and CO2 gas mix 38, which is a by-product of the cleaning process. This mix 38 is suctioned by the pump 36 to a collection tank 40.

In use, the nozzle and hose of the apparatus are inserted into a cooling condenser and dry ice pellets from the hopper are projected at high speed (using compressed air) through the nozzle and towards the inside surface of the cooling condenser thereby detaching scale or the like from the inside surface of the cooling condenser. The dry ice pellets are typically around 1.5 to 3 mm in diameter and 0.5 to 2 cm in length. The dry ice is projected or dispensed at an angle of less than approximately 45° relative to the longitudinal plane of the nozzle, the speed of the dry ice increasing as it travels through the nozzle. A vacuum is applied to the cooling condenser at an orifice other than that at which the nozzle and hose are inserted, aiding the acceleration of the dry ice and the removal of the scale, debris and CO2 gas mix. As the cleaning progresses, detectors measure whether there is scale remaining on the inside surface of the cooling condensers and feed this information back to the user by way of a monitor.

The nozzle is so configured to ensure that the dry ice is projected at an angle of less than approximately 45° relative to the longitudinal plane of the nozzle. Also, the nozzle is so configured so as to accelerate the dry ice as it travels through the nozzle, but without creating points of impact within the nozzle, thus preventing sublimation of the dry ice before it exits the nozzle, whilst generating sufficient speed that the dry ice pellets sublimate on contact with the scale on the inside surface of the cooling condenser.

Typically, the nozzle is made from stainless steel, but could be made from another suitable material as is known in the art.

By using the dry ice cleaning apparatus and process described, the inside of cooling condensers and the like can be efficiently cleaned without the use of corrosive liquids or abrasive scrubbing devices. Thus, damage to the inside surface of the cooling condensers is mitigated. Furthermore, the only waste product from use of the present apparatus and method is the scale itself and waste gasses (CO2 and air). Therefore, this cleaning technique is very energy efficient, not requiring ultra high pressure.

Furthermore, the waste product is a lot easier to handle, the waste solids and gases being easily separated. Moreover, as the technique avoids the use of water, it is more environmentally friendly and does not result in large volumes of liquid waste for disposal.

Applying suction by way of a vacuum pump makes the process more efficient, accelerating the dry ice and helping to direct the debris to a collection chamber. By monitoring the cleaning process, the user can ensure that areas with more scale are given more attention, and that areas with less scale are given less attention, therefore making the overall process more efficient, and resulting in better overall cleaning. Monitoring also allows the user to verify that the cooling condenser is clean.

The present invention therefore provides an apparatus and process for cleaning a cooling condenser conduit or the like without damaging the inside surface of the cooling condenser, which effects good cleaning, and which is safer and more environmentally friendly.

The configuration of the nozzle enables optimal dispersion of dry ice pellets such that maximum cleaning is obtained with minimum wastage of dry ice. Furthermore, the shape of the nozzle enables dry ice to be accelerated in the nozzle and to be dispersed without choking of the nozzle. Also, the unique shape of the nozzle enables the dry ice to be dispersed in a way which is of particular use in cleaning the inside of a conduit such as a pipe.

The present invention therefore also provides a nozzle with an improved configuration and for dispensing dry ice at high speed, thereby limiting wastage of dry ice by way of unwanted and inefficient sublimation.

While this invention has been described with reference to the sample embodiments thereof, it will be appreciated by those of ordinary skill in the art that modifications can be made to the structure and elements of the invention without departing from the spirit and scope of the invention as a whole.

Claims

CLAIMS1. A nozzle for use in dispensing dry ice pellets, said nozzle comprising an inlet, an outlet and a hollow shaft located between said inlet and said outlet, wherein the width of at least part of the hollow shaft is smaller than the width of the outlet.
2. A nozzle as claimed in claim 1, wherein the width of at least part of the hollow shaft proximal to the outlet is smaller than the width of the outlet.
3. A nozzle as claimed in claim 1 or claim 2, wherein the width of at least part of the hollow shaft is smaller than the width of the inlet.
4. A nozzle as claimed in any one of claims 1 to 3, wherein the width of the hollow shaft tapers between the inlet and the outlet, said hollow shaft having a smaller width than the width of the inlet and the outlet.
5. A nozzle as claimed in claim 4, wherein the width of the hollow shaft is largest in proximity to the inlet and the outlet.
6. A nozzle as claimed in any preceding claim, wherein at least part of the nozzle in cross section is biconcave-like in shape.
7. A nozzle as claimed in claim 6, wherein the biconcave-like shape terminates at one end at the outlet.
8. A nozzle as claimed in claim 6 or claim 7, wherein the width of the hollow shaft is smallest approximately half way along the length of the biconcave-I ike shaped section.
9. An apparatus for use in dispensing dry ice pellets, said apparatus comprising: a nozzle for use in dispensing dry ice pellets; a hose or the like fluidly attached to the nozzle; a source of dry ice fluidly connected to the hose or the like; and a means for applying motion to the dry ice, said motion directing said dry ice through the nozzle.
10. An apparatus as claimed in claim 9, wherein the means for applying motion is a compressed fluid, optionally a compressed gas.
11. An apparatus as claimed in claim 9 or claim 10, wherein the means for applying motion is a compressor.
12. An apparatus as claimed in any one of claims 9 to 11, wherein the nozzle and hose or the like are sized and shaped to fit inside a conduit or the like.
13. An apparatus as claimed in any one of claims 9 to 12, wherein the source of dry ice is a hopper in fluid connection with the hose or the like.
14. An apparatus as claimed in any claim 13, wherein the hopper is in fluid connection with the means for applying motion to the dry ice.
15. An apparatus as claimed in any one of claims 9 to 14, wherein the apparatus further comprises a means for imparting suction to a conduit or the like.
16. An apparatus as claimed in claim 15, wherein the means for imparting suction to a conduit or the like is a vacuum pump configured to attach to said conduit or the like.
17. An apparatus as claimed in any one of claims 9 to 16, wherein the apparatus further comprises a means for detecting scale or the like on an inside surface of a conduit.
18. An apparatus as claimed in claim 17, wherein the means for detecting scale or the like comprises: one or more sources of electromagnetic or sound waves configured to reflect off the inside surface of the conduit and/or scale or the like attached thereto; one or more detectors, configured to detect the electromagnetic or sound waves.
19. An apparatus as claimed in claim 18, wherein the one or more sources of electromagnetic or sound waves is a laser.
20. An apparatus as claimed in any one of claims 17 to 19, wherein the means for detecting scale or the like on an inside surface of a conduit is located between the nozzle and the hose.
21. An apparatus as claimed in any one of claims 17 to 20, wherein the nozzle has an inlet fluidly connected to the hose, and an outlet for dispensing dry ice or the like, said means for detecting scale or the like on an inside surface of a conduit being located between the nozzle outlet and the hose.
22. An apparatus as claimed in any one of claims 17 to 21, wherein the nozzle has an inlet fluidly connected to the hose, and an outlet for dispensing dry ice or the like, said means for detecting scale or the like on an inside surface of a conduit being located between the nozzle outlet and the source of dry ice.
23. An apparatus as claimed in any one of claims 17 to 23, said apparatus further comprising a monitoring device for monitoring the detection scale or the like on an inside surface of the conduit.
24. An apparatus as claimed in claim 23, wherein said monitoring device comprises a feedback mechanism, said feedback mechanism being configured to control the position of the nozzle.
25. An apparatus as claimed in any one of claims 9 to 24, comprising the nozzle of any one of claims 1 to 8.
26. A process for cleaning the inside of a conduit or the like having an inside surface, said process comprising the steps of: providing a nozzle sized and shaped to fit inside said conduit or the like; providing dry ice in pellet form or the like; inserting the nozzle into an orifice in said conduit or the like; and imparting motion to said dry ice such that said dry ice is dispensed from the nozzle in the direction of the inside surface of the conduit.
27. A process as claimed in claim 26, wherein the nozzle is fluidly attached to the hose or the like shaped to fit inside said conduit or the like.
28. A process as claimed in claim 26 or claim 27, wherein the dry ice is dispensed from the nozzle at an angle of less than approximately 45° relative to the longitudinal plane of the nozzle.
29. A process as claimed in any one of claims 26 to 28, wherein the motion of the dry ice is accelerated in the nozzle section.
30. A process as claimed in any one of claims 26 to 29, wherein the motion is imparted by a compressed fluid, optionally a compressed gas.
31. A process as claimed in any one of claims 26 to 30, comprising the further step of applying a vacuum at an orifice in said conduit or the like to remove debris created by the cleaning process.
32. A process as claimed in claim 31, wherein the vacuum is applied at an orifice other than the orifice at which the nozzle is inserted.
33. A process as claimed in any one of claims 26 to 32, comprising the further step of detecting scale or the like on the inside surface of the conduit.
34. A process as claimed in claim 33, wherein the detection of scale or the like is performed on the inside surface of the conduit after the inside surface of the conduit has been cleaned.
35. A process as claimed in any one of claims 26 to 34, wherein the conduit is a pipe, said pipe having an inside surface.
36. A process as claimed in claim 35, wherein said pipe is part of a heat exchanger or a cooling condenser.