EP1818113A1

EP1818113A1 - Machine for un-incrusting pipe systems or circuits

Info

Publication number: EP1818113A1
Application number: EP06380032A
Authority: EP
Inventors: Felipe Romero Huesca
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-02-13
Filing date: 2006-02-13
Publication date: 2007-08-15
Anticipated expiration: 2026-02-13
Also published as: EP1818113B1; ATE504365T1; DE602006021133D1

Abstract

System for un-incrusting pipe circulating systems by introducing a pressurized gas (generally compressed air) and solvent mixture at an speed of 40 - 70 m/s.

To achieve this pressure, rising devices are installed, like a pump (1), a device for distributing and enriching the gas, a junction point where gas and solvent can get mixed, and a connection (10) for the injection of the mixture into the pipe system (8) to be cleaned, which does not need to be disassembled.

One second outlet connection (20) receives the mixture which goes through a filtration system (22) and after here, finally deposited into a waste collection tank (23).

The system incorporates safety devices and engineering, that allow its use in explosive atmospheres, such as purge control devices, armored and pressurized cabinets (30, 40), and control of most of its instrumentation by pneumatic signals.

Description

Field of the Invention

The present invention describes an un-incrusting system for the piping circuits that transport materials like paints, oils, waxes, liquid plastics, and any other substance that can get incrusted onto the pipe walls and therefore decreasing the net cross section of the pipes.

Technical Summary

The technical area to which this technology belongs to, is the cleaning of incrusted materials in internal walls of pipe systems. Especially when these materials are of a very difficult removal, like a greasy material, a solidified plastic, paint incrusting, residues of fuel, amongst others.
A clear example, but not limited to this, of this application is the color change procedure carried out in a paint system of an automotive paint plant.
There are known cleaning methods, as the one described in patent WO 9205888 in which a device equipped with brushes and nozzles is introduced inside the pipe system, through which a pressurized water current is flowing until the cleaning has been achieved. This system has several inconveniences, like un-assembling the pipe system to be cleaned, the difficulty of cleaning hard-to-reach areas and the time consuming job.
Other methods, deal with pumping a cleaning agent with suspended particles inside the system.
This is how it is described, for example, in the document EP 1131169 . This process does not guarantee the cleaning of all the areas of the piping system, especially elbows, zones near the valves and other areas with difficult access. Besides, this method requires big volumes of the cleaning agent, which is generally a toxic solvent.
A third method, deals with introducing a big volume of solvent into the system, and then pushing it by using a high-pressure gas. This process achieves an adequate cleaning, but it spends great amounts of solvent and the piping resistance might get affected by the pressure inserted by the gas into the pipe system, so this has to be disassembled to proceed with this type of cleaning.
Therefore, this is a time-consuming process, besides, the high pressure might bring risks of metal fatigue and bursting of the pipe system with its corresponding safety risks as well.

Description of the Invention

The present invention refers to a pipe cleaning system that works by injecting a pressurized mixture of solvent and a gas (compressed air) at the same time (liquid-gas phase). By doing this, the amount of solvent required is greatly reduced, providing by this, better safety and health conditions to the workers involved. Besides, this system does not require the piping to be disassembled, but it is applied on-site as it is, reducing a big deal the complexity of the cleaning, the shut-down time of the system and facilities in which this pipe circuit is a part of.
Moreover, the combination of pressurized compressed air with the cleaning solvent assures a very effective (it removes 98% of the incrusted residues) and fast cleaning, given that this process combines chemical and mechanical cleaning reducing by this the facilities shut-down time, by far.
Given that is common that the solvent or the material to be removed, be dangerous by creating an atmosphere heavy on Volatile Organic Chemicals (VOC's) (commonly called "explosive atmosphere") it is an added advantage of this invention, the great level of safety that can be reached in any of its options.
This system includes ways to increase the pressure (generally a pump) which takes the solvent from a tank through a solvent intake.
In parallel, there is an entry for compressed air and a filter for eliminating the dirt in it, as an option. This is followed by an air booster, which is a device to distribute and enrich the compressed air flow, this is like a diaphragm compressor that sends the compressed air to different applications within the machine.
Both flow lines, of solvent and compressed air, meet in a junction point, after the pressure rising and air booster devices, to generate the air-solvent mixture. The proportion of these elements in the mixture can be controlled by their respective actuators (a valve controlled by pneumatic signals) that regulate the air and solvent flow.
After here, the mixture passes through the exit sight gauge and then is introduced into the piping system to be cleaned. It is highly recommendable that the mixture be introduced into the system at a speed between 40 to 70 meters/second, this velocity will guarantee the un-incrusting of the residues in the pipe walls of the system. To achieve this, the pressure of the mixture must be introduced between 5 and 15 bars (500-1500KPa) and even more frequently between 6 and 10 bars (600 - 1000 KPa).
At the exit of the pipe system, there is a second sight gauge through which the mixture flows, now dirty, avoiding that the mixture be in contact with the environment to avoid contamination. After this connection, there is a filtration system that separates part of the dirt in the outcoming mixture, and a waste collection tank for depositing the gas-liquid residues at the end of the process. The mixtures condensates in this tank (vapors turn into liquid) so therefore there is no emissions in the working atmosphere. This waste collection tank is frequently part of the facilities in which these pipe un-incrusting works are being performed.
The standard invention incorporates the Teflon PTFE (Polytetrafluoroethylene) sight gauge in between the exit connection of the system and the filtration system of the machine, so the exit of the dirty air-solvent mixture can be seen and optically evaluated, for instance, how dirty it comes out. It is highly recommended that the Teflon used in the sight gauges be of the PTFE composition so nothing adheres to it, so nothing corrupts the visual inspection.
With regards the options developed to be used in explosive atmospheres, we can mention the addition of a variety of safety devices, like, but not limited to:

a) Locate all the electronic and electric equipment that controls the system (the machine) inside an armored and hermetic Stainless Steel cabinet, pressurized with compressed air to avoid the entry of flammable vapors inside, belonging either to the cleaning solvent or from the materials inside the pipe system to be cleaned.
This cabinet pressure can be monitored at all times, so in case it disappears due to air leaks, misuse or other types of personnel interference the electric current is automatically shut down by the Main Safety Control device.
At the same time, a smaller second pressurized cabinet receives the compressed air from the main cabinet, and sends it back to the original Main Safety Control devices that it is also the final air-purge unit. All pressurized cabinets perform a time-controlled air purge before any electric fluid is sent to these separate units. Besides, in the main pressurized cabinet there are the controls and regulation of the pressure of air and solvent that is injected into the pipe system to be cleaned.
b) Installation of Zener barriers to limit the internal voltage that elements of the system require.
c) Maximized use of pneumatic signals for controlling and performing of the equipments: by these means, the solvent pump can be of double diaphragm, the air booster, all valves are controlled by pneumatic signals operated from a centralized control panel. A set of electrovalves and pressure transducers inside the smaller pressurized cabinet, monitors and controls the operating conditions of solvent and air, in order to produce a highly efficient mixture.

Description of the drawings.

For a better understanding of this invention, we briefly describe next, an invention sketch as an illustrative example but not limited to it. For this, we will refer to the attached drawing, identified as Figure 1, in which we have represented a blueprint of the invention.

Description of a Performing Mode

In Figure 1 we can see a blueprint of the invention, where we can see the solvent entry (2) in connection with the devices for rising the pressure, a pump for example (1) which can be of double diaphragm.
The solvent intake (2) can be done, for better safety purposes, with a Kamlock quick connection. After the pump's exit we find a cross with a solvent pressure transmitter (on the upper side) and a solvent purge (on the lower side), next we have a solvent actuator (a set of a valve with a pneumatic mechanism to operate it) that controls the solvent dossification, then a check valve (7) that only allows flow forward, and avoids the return of the solvent either dirty or mixed with the gas.
Parallel to the solvent line, there is the gas entry (3) coming from a compressor, a deposit, or any other source (not indicated) through another Kamlock connection. This gas is generally compressed air, although, it can be another type of gas.
The compressed air goes through a microfilter (4) to eliminate dirt particles contained in it, after this, it passes through an air booster, which is an air distributor and enricher, that allows to controls the inlet pressure to the needs of the pipe system to be clean. This device can be, for instance, a diaphragm compressor.
Following the exit of this device (5) there is an actuator (6) that controls the air dosification, the check valve is found next, which has the same function as in the solvent line, to avoid any flow return.
After the check valves (7), both lines get together to produce the mixture compressed air-solvent, that is injected through inlet (10), a Kamlock connection for instance, into the piping system to be un-incrusted.
It is highly recommended that the mixture be injected at an average speed between 40 to 70 m/s, with these conditions, the mechanical removal of the incrusted materials is optimized without having a pressure drop, therefore, not requiring too high injecting pressures. In normal conditions the injecting pressure of the mixture must be between 5-15 Bars (500 - 1500 KPa), but more optimal between 6 -10 Bars (600 - 1000 KPa).
In order to control the injecting pressure, a set of manometers and pressure transducers are installed (12) (only a few of them have been indicated in the diagram) at the exit of the pump (1) and the device (5) . According to the signals of these instruments, the opening of closing of the actuators (6) to regulate the mixture, must be decided in the pneumatic control panel.
As extra safety measures, the system includes relief valves, in order to depressurize the pipe system connecting lines when needed.
Finally purge valves (9) are also installed before the solvent actuators (6) and after the junction point of the mixture air-solvent. These valves have the safety function of depressurizing the system when changes in the pipe system connections need to be made.
Near outlet (10), a transparent length of pipe made with Teflon PTFE (Polytetrafluoroethylene) the sight gauge, is installed to visually see the passing of the air-solvent flow.
Once the mixture has gone through all the pipe system, performing the cleaning by 2 actions, mechanically due to the power of the air, and chemically due to the power of the solvent, it passes through a second outlet (20). In order to prove the cleaning efficiency, near this second outlet (20), another transparent length of pipe can be installed (21). When the mixture passes really clean through this sight gauge, the cleaning of the pipe system can be confirmed to be finished.
The outcoming mixture passes through a filtration system (22) to retain part of the residues removed, and after here, the mixture continues his way to a waste collection tank (23) for its final treatment. By doing this, the solvent emissions to the working atmosphere are eliminated, and also those to the environment. Usually the waste collection tanks are part of the facilities to be clean and they are usually of a big capacity.
The filter bag of the filtration system (22) might have, for instance, a mesh size of between 10 - 25 microns. Even with this small size, the amount of retained residues is small due to the fact that the incrusted residues are completely disintegrated once they get in touch with the high-speed air-solvent mixture of our system.
It is an additional design characteristic of this invention, to incorporate safety systems to allow its use in explosive atmospheres.
These safety systems include the hermetic and pressurized cabinets (30, 40) that completely isolate the electronic and electric equipment, like the CPU (31) that operates the system, the equipment that allows to introduce commands to the operating system, like the touch pad screen (32), that can be accessed from the outside or any other electrovalve required.
It is mandatory to introduce in these cabinets (30, 40) a gas pressure, by compressed air for instance, the same one that is used for the cleaning mixture and at the same pressure. By this way, the flammable vapors can not get inside these cabinets. In case of losing the pressurization for any reason, such as faulty hermeticity or air leak, the electric flow is automatically cut off by the main safety device.
Since the very instant in which our system is turned on, a complete timely-operated air purge (45) will be carried out inside the cabinets, in the one that has the CPU and the touch pad screen (32), as well as the second pressurized cabinet with the set of electrovalves. The whole purging process comes out and comes back from the main safety device system that is reading this air flow continuously and at all times, and will send shut down signals if for any reason this flow is interrupted in any of the cabinets.
In addition to this, all cabinets are grounded for the dissipation of static electricity, and the inside metal parts are made of brass which do not produce sparks, in case of mechanical impacts. Zener barriers are also installed with the purpose of limiting the energy consumed in areas that might have an spark risk.
Finally, a maximum of elements , such as the pump and valves, are controlled pneumatically and not electrically, so the risk of sparks is almost impossible. The electronic and electric parts that the pneumatic system requires, are introduced in the pressurized cabinets. Not limited to this we can mention, the electrovalve that sends an air signal to the control panel of the air-solvent actuators, or the pressure transducer that receives the initial air parameter signals and displays it in the screen.
All this system can get installed on a portable equipment, that can get transported on-site where the pipe systems need to be clean. In addition to this, the pipe systems can be cleaned by applicating the regular forward flow path (forward flush), or backwards flow path (back flush), reaching by these improvements a cleaning efficiency of between, 95-99% (of all incrusted residues removal).
Once outlet (10) is installed, at the entry of the system that has to be clean, a set of valves are opened or closed in the piping system, with the purpose of selecting the piping flow path (8) that our cleaning mixture must follow, and there is a second outlet (20) at the exit of the system, to collect the mixture air-solvent and the residues removed. Again, the injection can be carried out on a forward or a backwards flush mode.
Once the system has been checked to be clean, the solvent flow is interrupted, so only compressed air is introduced, by doing this we remove the residues of solvent in the system. Finally the pressures comes down gradually as soon as we shut down the compressed air supply into the pipe system. After there is not pressure in the system, it can get disconnected and it is ready to be used again after it has been clean perfectly.

Claims

The system for un-incrusting pipe circuits and remove the materials deposited on its walls (8) by the introduction of a high speed mixture of solvent and compressed air includes:
- a gas intake (3);

- an air booster (5) to distribute and enrich the gas intake, and to bring the gas to an operating pressure;

- a solvent intake (2) from an solvent deposit;

- pressure rising devices after the entry of the solvent;

- a junction point to create an ideal mixture between compressed air and solvent ;

- an entry (10) to inject the air-solvent mixture into the pipe system (8) to be cleaned, at a pre-determined speed;

- a second outlet (20) to receive the mixture once this has gone through the pipe system (8); and

- a waste collection tank (23) to deposit the final residues
The system, according to claim No 1, is also characterized for its respective actuator sets (6), for both air and solvent lines, used to control and dosify their proportions into the mixture. Both lines are also provided with check valves (7) to avoid any flow return on either of them.
System, according to either of the claims 1 or 2, is characterized for including a filtration system (22) to collect the residues removed by the air-solvent mixture , in between the second outlet (20) and the waste collecting tank (23).
System, according to any of the claims from 1 to 3, characterized for the cleaning speed of the air-solvent mixture through the pipe system (8) in between 40 - 70 m/s.
System, according to any of the claims from 1 to 4, characterized for the injecting pressure of the air-solvent mixture into the pipe system (8) to be in between 500 - 1500 Kpa.
System, according to claim 5, characterized for injecting the mixture air-solvent into the pipe system (8) at a pressure in between 600 - 1000 Kpa.
System, according to any of the claims 1 to 6, characterized for including a sight gauge (13) located in a zone before and after the second connection (20).
System, according to any of the claims 1 to 7, characterized for including a second sight gauge (21) located in a zone before and after the second connection (20)
System, according to any of the claims 1 to 8, characterized for the gas to be compressed air.
System, according to any of the claims 1 to 9, characterized for including safety devices and systems for its use in explosive atmospheres.
System, according to claim 10, controlled by a variety of electronic equipments, characterized for installing such equipments inside hermetic and armored cabinets pressurized with compressed air.
System, according to either of the claims 10 or 11, characterized for including as the first device for rising the pressure, a double diaphragm pump (1).
System, according to any of the claims 10 to 12, characterized for the device (5) is an air booster.
System, according to any of the claims 10 to 13, characterized for the actuators (6) to be pneumatic, activated by a main pneumatic control panel that receives signals from the electrovalve (41) installed on an armored and pressurized cabinet (30, 40).