MXPA97002925A - Cleaning system - Google Patents

Abstract

The present invention relates to a method for cleaning a reactor vessel for a chemical process, comprising a tank and one or more ducts associated with the preparatory tank for carrying out the chemical process in the reactor vessel, the method comprises a step of adding a cleaning solvent in which is added a volume of a cleaning solvent for contaminants contained in the reactor vessel, to the reactor vessel, and a circulation stage of cleaning solvent in which the volume of the solvent is circulated. cleaning solvent in the reactor vessel, characterized in that during the circulation step of the cleaning solvent, at least a portion of the volume of the cleaning solvent is purified and recycled back into the reactor vessel to force at least a portion of the volume of the cleaning solvent through a filter system that has an entrance in fluid communication with the container of reactor, an output in fluid communication with the reactor vessel and a flow path between the inlet and the outlet which contains an adsorbent for contaminants

Description

CLEANING SYSTEM TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for cleaning a container and the conduits associated with said container, by adding a cleaning solvent to the container and circulating solvent through the conduits again to the container. The container can be a reaction container for chemical processes. The invention also relates to an apparatus for use in the above method, and to a filter unit that is part of such an apparatus.

BACKGROUND OF THE INVENTION Reactors, for example large containers for chemical processes, frequently operated under elevated temperatures and high pressures, have to be cleaned periodically during use or after use to remove any contaminants or other material that deteriorates the chemical process carried out in the reactor. or that influences performance. Cleaning is particularly important when the REF: 24479 reactor has to be used for another process. Said cleaning is normally carried out in different steps, such as a first rough cleaning of the reactor, by means of jet cleaning of high pressure liquid, if necessary supplemented by mechanical cleaning, followed by cleaning with solvent in which a suitable solvent ( chosen depending on the contaminants to be eliminated) is circulated through the container and through the pipes and pipes connected to it. A typical solvent is for example ethanol. In a commonly used method, which for example can be termed "forced circulation", the solvent is simply pumped through the system in such a way that the liquid contacts all contaminated parts of the system. After some time the solvent will be contaminated to a degree that causes a continuous circulation of the solvent will only recontaminate the reactor system, and the solvent must consequently be replaced by fresh and pure solvent. In another commonly used method the solvent can be added to the reactor and brought to the boiling point, the solvent thus being at least partially vaporized. The vaporized solvent is conducted to a cooler in which it is condensed, preferably in the cooler normally associated with the reactor, and the condensed solvent is allowed to flow in a direction that is opposite to the normal direction of flow in the reactor system. , and the ducts associated with it in order to dissolve and remove any contaminants. This procedure is sometimes called "reflux" and will be so called in the following discussions. Since contaminants can also be volatile, at least to some degree, the amount of the contaminant after the vaporized solvent returns to the reactor system, and to some degree the recontamination of the reactor system, will increase in proportion to the increase in contaminants. in the solvent. At a certain point, cleaning / recontamination will reach a balance and the contaminated solvent will consequently have to be removed and replaced with new pure solvent. These previous solvent cleaning procedures are repeated until the required degree of decontamination has been obtained. The degree of decontamination necessary for pharmaceutical purposes can for example be ascertained by UV spectral analysis within a specific wavelength range, for a specific solvent, by filter tests and by visual control of the cleaning solvent, the amount of the The contaminants in the circulation solvent indicate the degree of contamination remaining in the control system. However, these processes are very time consuming and very economical with respect to the cleaning solvent, since the solvent has to be replaced several times before the solvent has reached a level of purity indicating that the reactor and the pipe associated with it It has a degree of cleaning that is sufficient for the purposes of the chemical processes to be carried out in the reactor system. It is of course also difficult and expensive to recycle or otherwise take care of such large amounts of contaminated solvent, not least from an environmental point of view. The additional costs that arise as a consequence of the long delay before the reactor system can be used again, are high. German Patent DE 3918285-A1 (Elastogran Polyurethane GmbH) describes a process and apparatus for rinsing or cleaning mixing apparatuses for multi-component plastics, especially polyurethane. The rinsing agent may be fed back into the rinsing agent cycle after it has been cleaned on a filter. The rinsing agent is simply drained to a collection and recycled container manually as required. U.S. Patent No. 2312091 (Gray / Gray Company, Inc.) discloses an apparatus for cleaning automobile engines. The solvent is circulated internally throughout the length of the engine, where it collects varnish, mud, rubber deposits, carbon dirt and the like. After the engine is stopped again, the solvent carrying the dirt is pumped out and gravitationally filtered through one or more filter units, which clean the solvent. The cleaned solvent is collected in a tank, and is manually recycled again, as required. These two documents are related to the cleaning devices in which the solvent is cleaned after the cleaning process has occurred. In this way, if the cleaning has to be continued, considerable delay is caused by: - stopping the cleaning process, draining the solvent, filtering it, feeding it back into the reactor system, and - the start again of the cleaning system.

On the other hand, for example in US Pat. No. 1635115 (Deutsch et al. / Deutsch), cleaning systems have been used in which a cleaning liquid is constantly conducted through a filter, as it is circulated. This has the disadvantage that the delay is caused by: constantly driving the solvent to the filter, constantly filtering them, and constantly feeding it back into the reactor system.

In the event that the filter is blocked, the cleaning process could be stopped, since circulation is no longer possible.

DESCRIPTION OF THE INVENTION It has now been found that the above disadvantages can be eliminated by the use of a method of the type described above, in which the cleaning solvent can additionally be intermittently forced through a filter unit which contains an appropriate absorbent material and is left flowing from the ducts towards a container, said container and the ducts in this way are intermittently flushed with the pure solvent. Thus, according to the present invention, there is provided a method for cleaning a container and the conduits associated with said container, by adding a cleaning solvent to the container and circulating the solvent through the conduits again towards the container, characterized in that the cleaning solvent can be additionally intermittently forced through a filter unit, which contains an appropriate absorbent and is allowed to flow through said ducts towards the container, the container and the ducts are This mode intermittently flushed with purified solvent. Such a method allows the consumption of the cleaning solvent and the time necessary for cleaning to be minimized, and also minimizes the environmental problems associated with large amounts of contaminated solvents. It is advantageous to have the solvent that makes contact with as many of the contaminated surfaces as can reasonably be achieved. This can be done by circulating the solvent by heating the solvent to the boiling point, and driving the resulting vaporized solvent to a cleaning unit located above the container, and allowing the condensed solvent to flow through the conduits back into the container. container. In this way, all contaminants are gradually dispersed in the solvent and can be filtered again. A pump can be used to ensure that the solvent is circulated in such a way that the solvents come in contact with all contaminated surfaces. The passage of the solvent through the filter is preferably carried out in a controlled manner. This can be achieved by orienting the filter unit in such a way that the flow direction in use is vertical and upward direction. An absorbent material that effectively leaves the solvent in a purified form must be chosen, although that does not need to be left completely free of contaminants. An appropriate absorbent material in the filter unit is granulated activated carbon. The method can be used for the cleaning of any apparatus in which a container is associated with ducts, such as chemical process equipment. This is ideally suited for the cleaning of reactor vessels for chemical processes. This can also be adapted for use with, for example, glove boxes. According to a further aspect of the present invention, an apparatus for use in a method of the specified type is provided. The apparatus can be adjustable, so that a portion of the cleaning solvent can be forced through the filter unit at the same time that the rest of the solvent is diverted from the filter container to return to the container. A particularly versatile system allows all the solvent to be forced through the filter unit, all this to avoid the filter unit or the solvent portions to follow both routes, as desired. A specific filter unit has an optimal flow velocity for the solvent through it. In this way, ideally the flow rate through the filter unit will be able to be adjusted to a predetermined value. One or more particle filters can be provided, as well as the main filter unit, the filters being connected in series with a pump for connection to the container. This ensures that the main filter unit does not get clogged quickly with large particles. According to a further aspect of the present invention, there is provided a filter unit for use in a method of an apparatus of the specified type, characterized in that the filter unit comprises a tubular housing for the absorbent material, an upper end portion which it contains a plunger with a filter to hold and compress the absorbent material, and a lower end part with a filter to hold the absorbent material. One of the end portions, preferably the top part, will be removable to allow the absorbent material to be replaced. The absorbent material can therefore be • discarded from time to time, minimizing the possibility of cross-contamination. The absorbent material must ideally be sufficiently compressed so that it can not move around. This prevents the relatively contaminated lower end from mixing with the relatively clean upper end, in use. It is possible that the compression of the absorbent material will change as the material settles. This can be prevented by the agitation of the material, and at the same time the application of a sustainable twist. An elegant way to compress the absorbent material is through the use of a cam mechanism comprising a tightening nut and a locking nut mounted on a threaded rod, the nuts are separated by a slotted bracket, whereby a selected element of the bar and the bracket is mounted on the plunger and the other is mounted on the housing.

BRIEF DESCRIPTION OF THE APPENDIX DRAWINGS Figure 1 is a schematic view of a conventional reactor system into which a filter unit according to the invention has been connected, Figure 2 illustrates a filter unit according to a preferred embodiment, The figure. 3 illustrates the lower end portion of the filter unit in Figure 2, Figure 4 illustrates the elongated middle section of the filter unit embodiment in Figure 2, Figure 5 illustrates the upper end portion of the filter unit in Figure 2, Figure 6 shows the partially sectioned upper end portion of the intermediate section in Figure 4; Figure 7 is an end view of the upper end portion in Figure 6, Figure 8 is a plunger placed in the upper end part of the filter unit in Figure 2, to maintain and compress the activated carbon in the unit, Figure 9 is an alternative embodiment of such plunger, Figure 10 shows the bracket of figure 8, Figure 11 shows a view of the bracket of Figure 10 in the direction XI, Figure 12 shows the backing plate of Figure 8, Figure 13 shows a view of the backing plate of figure 12 in the direction XIII, Figure 14 shows in section, the upper end of a tube in which the plunger of Figure 9 can be inserted, and Figure 15 shows a view of the tube of Figure 14 in the XV direction.

DETAILED DESCRIPTION OF A PREFERRED MODE OF THE INVENTION A schematic illustration of a filter unit 1 according to the invention is shown in FIG. 1, connected to a receptacle comprising a conventional reactor vessel 30 with a conventional cooling unit 31. The cooling unit or chiller 31 is connected in series to the reactor vessel 30 by means of conduits 32 and 33 provided with valves 34 and 35. The lower end of the reactor is provided with an observation glass 37 as is conventional in the art. This observation glass can be used in the visual control of the purity of the solvent in connection with the standard tests mentioned above. In this mode, the reactor system is intended to be cleaned by the "reflow" method. There are of course also other conduits in the system, which are cleaned apart from conduits 32 and 33, but these other conduits are not illustrated. The parts in figure 1 related to the invention, are structured by means of dashed line 20. The filter unit 1 comprises a tubular housing 2 filled with an absorbent material, which in this particular case is granulated active carbon 3. The Filter unit is oriented vertically in use. The carbon is held in the housing 2 by means of a filter 4 of fixed particles, at the lower end of the housing, and by a movable and insurable plunger 17, provided with a filter 13 at the upper end of the housing. Filters 4 and 13 have a mesh size that is small enough to prevent carbon granules from passing through the filters. The plunger 17 can be moved into the housing 2 in order to compress the granulated carbon to a sufficient degree to prevent the granules from moving when the solvent to be cleaned in the filter unit 1 is forced through the activated carbon 3. , and to prevent the formation of open channels through carbon granules. Although the plunger 17 is illustrated positioned at the upper end of the filter unit 1, the filter 4 and the plunger 17 can of course be exchanged with each other without changing the function of the filter unit. Starting from the lower outlet 36 of the reactor vessel, a first optional particulate filter 7 is connected in series with a pump II and the lower end of the filter unit 1 via the valves 8, 9, 10 by means of of a conduit 12. Whether or not a first particle filter 7 is used, effectively, this depends on the risk for the presence of larger particles in the contaminated solvent, which can block the filter unit 1. The pump 11 is a high-pressure, commercially available, standard pump, which is capable of handle boiling liquids together with vapors of the same, for example a pump of the type of the centrifugal pumps APV Rosista, manufactured and sold by APV Sweden AB. The pump must be able to distribute a sufficient pressure to force the liquid through the active carbon 3 in the filter unit 1. The particle filter 13 at the downstream end of the filter unit 1, consequently has to be designed to be able to withstand the pressure of the liquid on the activated carbon and the pressure that is a result of the compression of the carbon granules, while the particulate filter 4 at the end 4 of upstream of the filter unit 1 has to be designed to resist the compression pressure of the carbon grains, only. The upper end of the filter unit 1 is connected inside the cooler 31 in series with a second particulate filter 14, and the valves 15, 16 by means of a conduit. The function of the second particulate filter 14 is to ensure that care is taken for any particles that may accidentally pass the filter net in the plunger. The carbon granules used in the preferred embodiment can be "Merck 2514", or "Chemviron Coal type F2.00", which are commercially available. The size of the granules can be 1.5-2.5 mm.

The size, hardness and compressibility of the carbon granules, as well as the compressive force on the granules, is, however, generally determined by the capacity of the pump and the desired flow through the filter unit. Some cleaning solvents that can be used in the method according to the invention are methanol, ethanol, water, acetone, toluene, methyl isobutyl ketone, isopropyl alcohol, ethyl acetate or methylene chloride, used at temperatures varying from about 10-20 ° C to the respective boiling point. As indicated above, the cleaning process is usually initiated with a rough cleaning by means of jet cleaning with high pressure liquid .. A sufficient amount of solvent is then added to the reactor vessel and circulated through the system by means of the "reflux" method, described above (or, of course, alternatively, by the "forced circulation" method). As soon as the solvent is considered to have been contaminated to a degree at which the reactor system will be re-contaminated again, the outlet 36 of the reactor vessel 30 is connected to the pump 11 and the boiled contaminated liquid is pumped through the filter unit 1. This will of course be before the cleaning / re-contamination equilibrium, mentioned above, is reached. The dissolved contaminants and small contaminant particles in the cleaning solvent will thus be absorbed in the granular activated carbon. The absorption initially takes place at the lower end of the filter unit and gradually moves upward at the same rate as the saturation of the active carbon with the contaminants. As long as the saturation front has not reached the upper end of the filter unit, the pure, filtered solvent will leave the filter unit through the unpolluted, pure activated carbon and then flow to the refrigerant unit and down to the reactor vessel. The reactor system will thus be flushed with pure solvent, since the solvent is forced through the orifice of the filter unit, thereby effectively removing the contaminant. The size, or length of the filter unit and the amount of active carbon contained therein, can be adapted to the size of the reactor system and the amount of cleaning solvent that is necessary, so that most of the activated carbon has absorbed contaminants when the reactor system has reached the desired degree of cleanliness. Alternatively, the flow through the filter unit can be varied by adjusting the valve 16, so that the optimum flow rate for a particular filter unit is reached. The solvent can be allowed to flow through the filter unit at the same time as cleaning of conduits 32 and 33 occurs, leaving all valves partially open. The system is highly versatile, whether all or none of the solvent can pass through the filter unit, or some of the solvent can pass through the filter unit, and some of it drifts, through judicious adjustment of the various valves. The solvent can then be recycled or possibly used again without any pretreatment. The amount of solvent used is limited to the first amount added to the reactor vessel. Two or more filters can be included, each with its own valves, to allow additional system versatility.

The activated carbon in the filter unit containing the contaminants can easily be discarded. The pump filter unit, the particle filters and the conduits can be advantageously designed as a separate unit that can be transported and temporarily connected to any reactor, to be cleaned, or can of course also be more or less permanently connected to a reactor. reactor system. The main advantages consequently are that the solvent can be kept in a purer state throughout the cleaning system, without having to use fresh solvent. The process will consequently be faster and much more economical with respect to the amount of solvent used in the process of the prior art processes, described above. In view of the small amount of contaminated solvent that eventually has to be discarded, the environmental aspect is very much taken into account. The time required to empty and refill the reactor vessel several times is also eliminated. Another advantage is the possibility of connecting several reactor systems to a filter unit, thus saving more time.

Figure 2 illustrates a preferred embodiment of the filter unit 1 in an assembled state, with a main housing 2 in the form of a pipe 40, an upper end part 41 and a lower end part 42. The pipe 40 is made of steel stainless steel having an internal diameter of approximately 100 mm and a full length of 1720 mm. The tube 40 in use is almost completely filled with granulated activated carbon of the type described above. A filter unit of this size is adapted for reactor systems of different sizes, of the type used for chemical processes. The size of the filter unit and the amount of absorber is decided by the total size and the degree of contamination of the reactor system. The lower end portion 42, which is provided with a ball valve 43, having a connecting tube 44 for connection to the conduit from the pump -11, is provided with an upper flat surface, adapted to receive a backing plate for a filter network. The backing plate is made of steel, stainless steel and has a thickness of 1.5 mm and is perforated by uniformly distributed holes, having a diameter of 5 mm. The area of the holes is 35% of the total effective area of the backing plate. The filter net, which has a size of 0.077 mm, is placed upstream of the backing plate. The lower end part is also provided with a coupling part 46 for coupling to a corresponding flange 47 on the pipe 40. A complete view of the pipe 40 is shown in Figure 4. The upper end of the pipe is provided with coupling threads 48 and a bracket 49 for securing the plunger 17. The details of the upper end of the tube and the upper end portion are shown in Figures 5-8. The plunger 17, and consequently also the bracket 49, is to be housed in the upper end part 41. The part 41 is provided with a coupling nut 50 which fits over the threads 48 on the tube 40. The lower end of the the part 41 is provided with a flange 51 with a tapering surface 52, designed to fit a corresponding conical widening surface at the upper end of the tube. The bracket 49, which is made of 6 mm stainless steel, is provided with a transversely oriented slit 53 designed to receive a 12 mm stainless steel bar 54, provided with an M12 thread along its entire length. The bar 54 is part of the plunger 17, which further comprises a backing plate 55, perforated 1.5 mm, of stainless steel for a filter network 57. The backing plate is transversely oriented relative to the bar 54. The holes in the backing plate they have a diameter of 5 mm and are uniformly distributed on the plate. The area of the perforations is 35% of the effective flow area of the plate. The backing plate is reinforced by brackets 56. The filter net 57, which has a mesh size of 0.077 mm, is clamped against the backing plate 55, together with a circumferential sealing ring 58, designed to be coupled to the inner surface of the tube 40, by means of a clamping ring 59 coupled to the backing plate 55, by means of bolts 60. The free end of the bar 54 is provided with a movable locking nut 62. Another moving nut 61 is positioned on the threads of the bar 54. When the plunger is to be mounted, the bar 54 is inserted into the transverse groove 53 in the bracket 49, with the back plate 55 and the nut 61 placed between the bracket and The tube.

When the nut 61 is bolted outwardly against the bracket 49, the plunger will move towards the tube, in engagement with the absorbent material with the tube. A specific torsion when tightening the nut 61 will give a specific compression force on the absorbent material. For the specific type of effective carbon granules defined above, and with the specific dimensions of the tube given above, it has been found that a torsion of about 15 N.m. is appropriate, to have the granules securely and to prevent the formation of channels. When the specific torsion has been achieved, the securing nut 62 is pressed against the bracket 49, thereby securing the nut 61, as well as the plunger. The length of the bar 54 may be chosen to allow a variation in the amount of absorbent material in the tube, in order to adapt the filter unit to reactor systems of different size and / or different degrees of contamination. It will be appreciated that a different orientation may be chosen, so that one or more threaded rods are mounted on the tubular housing 40 and the grooved bracket is mounted on the plunger 17.

The details of an alternative plunger 17 and the upper end of the tube 40 are shown in Figures 9-15. The piston 17 is made up of a number of components, namely a threaded stainless steel rod 54, a back plate 55, a sealing ring 58, a filter net 57 and a bracket 49. The backing plate 55 is of annular shape and is tightened by a series of brackets 56 accommodated in conical formation. The brackets terminate in a shirt 63 centrally positioned. The threaded stainless steel bar 54 passes through the sleeve 63 and is permanently held in place by two locknuts 64 and 65. Between the sleeve 63 adjacent to the nuts are the washers 66 and 67. The part The annular plate of the backing plate 55 is coupled to the filter network 57, separated by the sealing ring 58. The sealing ring is a Teflon ™ package and the filter net is a perforated disk. The bracket 49 comprises a U-shaped steel member. The notched flanges 68 are provided at both ends. These are adapted to engage the grooved edges 69 within the upper end of the tube 40. The plunger unit is positioned by engaging the notched flanges 68 with the notched edges 69. This is accomplished primarily by insertion. of the piston 17 inside the upper part of the tube 40 with the bracket 49 facing away from the notched edges 69 in the tube, and then rotating it until the flanges and edges are engaged. The bracket 49 has a groove in the form of a centrally placed hole, and is again placed between two movable locking nuts 61 and 62. The lower nut 61 is tightened with a torque wrench to obtain a specific torsion. The upper nut 62 is then tightened until the bracket 49 is firmly held in place between the two securing nuts. It is important to ensure that the absorbent material 3 is sufficiently compressed, otherwise it can move, causing the relatively contaminated lower end to mix with the relatively clean upper end, and with use. This can be done by vibrating the column before applying the torsion pressure. Ideally, a torsion could be applied, sustainable after the device has been assembled, once additional compression is no longer possible.

Once the particular cleaning process has finished, the plunger 17 can be removed and the absorbent material discarded, if necessary. This eliminates the possibility of cross contamination if it is reused. It should be emphasized that, as already mentioned, all the dimensions and sizes given above refer to a specific modality adapted to specific reactors, and that the dimensions and sizes may have to be adapted to fit other reactors and other types of reactors. containers and ducts that have to be cleaned.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (13)

1. A method for cleaning an apparatus, comprising a container and one or more ducts associated with the container, the method comprising holding the apparatus to a cleaning step in which the cleaning solvent is circulated around the container and in one or more ducts, characterized in that the cleaning step is a continuous circulation of the cleaning solvent around the container and the ducts, by a plurality of cleaning cycles, and because the intermittent cleaning cycles comprise a filtration step in which the less a portion of the cleaning solvent is filtered to remove contaminants • introduced into the cleaning solvent during the preceding cleaning cycles, which do not comprise the filtration step.

2. The method according to claim 1, characterized in that the solvent is circulated by heating the solvent to the boiling point, and the resulting vaporized solvent is conducted to a refrigerant unit placed above the container, and which allows the condensed solvent to flow through the ducts back to the container.

3. The method according to claim 1, characterized in that the solvent is circulated by means of a pump, in such a way that the solvent is brought into contact with all contaminated surfaces.

4. The method according to any of the preceding claims, characterized in that the filter unit is oriented in such a way that the direction of flow in use is vertical and upward direction.

5. The method according to any of the preceding claims, characterized in that the absorbent material in the filter unit is granulated activated carbon.

6. The method according to any of the preceding claims, characterized in that the container is a reactor vessel or container for chemical processes.

7. The apparatus for use in a method according to any of the preceding claims.

8. The apparatus according to claim 7, characterized in that the apparatus is adjustable, so that a portion of the cleaning solvent can be forced through the filter unit at the same time that the rest of the solvent is diverted from the filter container, to return to the container.

9. The apparatus according to claim 8, characterized in that the flow rate through the filter unit is able to be adjusted to a predetermined value.

10. The apparatus according to any of claims 7 to 9, characterized in that the system comprises a first particulate filter, optional / a pump, a filter unit and a second particulate filter, connected in series for connection to the container.

11. A filter unit for use in a method or apparatus according to any of the preceding claims, characterized in that the filter unit comprises a tubular housing for the absorbent material, an upper end part containing a plunger with a filter, to maintain and compressing the absorbent material and a lower end part with a filter to maintain the absorbent material.

12. The filter unit according to claim 11, characterized in that the compression of the absorbent material is achieved by agitation of the material, and at the same time the application of a sustainable twist.

13. The filter unit according to claim 11 or 12, characterized in that the compression is achieved by means of a cam mechanism comprising a clamping nut and a securing nut mounted on a threaded rod, the nuts are separated by a bracket slotted, whereby a selected element of the bar and the bracket is mounted on the plunger and the other is mounted on the tubular housing.