Vacuum system

Abstract

Vacuum system (1) for generating the vacuum in a sterilisation chamber (2) of a steriliser (3), wherein said vacuum system (1) comprises an inlet (4) connected to the outlet of the sterilisation chamber (2) and a discharge outlet (5), and wherein said vacuum system (1) further comprises a dry vacuum pump (6) for generating vacuum without the use of water inside the sterilisation chamber (2), having a pump inlet coupled to the inlet (4) of the system (1) and a pump outlet coupled to the discharge outlet (5) of the system (1), and a plurality of valves (11, 12, 13, 14, 15) arranged between the inlet (4) and the discharge outlet (5) of the system (1) for regulating the amount of condensate within the system (1), wherein the dry vacuum pump (6) is a variable speed pump.

Description

[0001] Vacuum system

[0002] TECHNICAL FIELD

[0003] The present invention relates to a system for generating the vacuum without water consumption applied to a steam sterilisation chamber and to a method for limiting as much as possible the formation of condensate within the same system.

[0004] STATE OF THE ART

[0005] Systems for generating a vacuum inside a sterilisation chamber usually use vacuum pumps connected to the chamber outlet to remove the air inside the chamber and to eliminate any condensate that forms inside it and dry its contents. Generally, the known systems require large quantities of water, which leads to high water management costs, both for pre-treatment and disposal.

[0006] In addition, a known problem is the formation of condensate during the steam injection phase, which occurs every time the vacuum system is activated, whether using liquid ring pumps or alternative dry systems. In the latter case, the presence of condensate can reduce the efficiency of the pump and, if not properly managed, limit the vacuum performance achievable inside the sterilisation chamber.

[0007] Document W02015 / 079013 Al describes a waterless vacuum system to be coupled with a sterilisation chamber comprising a vacuum pump and a set of valves located between the inlet and outlet of said system. To reduce condensate inside the pump, the system is equipped with a curved pipe connecting the vacuum and air inlet valves to the pump inlet.

[0008] Document EP 2 060 275 Al describes a steam steriliser comprising a vacuum pump operating under saturated or near-saturated steam conditions at high temperatures, without a cooling system. The steriliser comprises a lubrication circuit with a tank in which a lubricating fluid circulates . This fluid is resistant to high temperatures and has high anti-emulsifying properties, with filtration means designed to separate the steam from the lubricating fluid. Here, condensate is reduced by circulating steam inside special cavities .

[0009] Although both documents describe a solution to the condensate problem for a vacuum pump, the condensate that is treated is limited by the structure of the ducts and components of the systems used. Furthermore, condensate removal cannot be optimised according to the sterilisation cycle.

[0010] Accordingly, the purpose of the present invention is to provide an effective and easy- to-apply solution to the above-mentioned problems relating to the generation of condensate in the use of a vacuum system that uses a dry pump. In particular, the purpose of this invention is to provide a dry vacuum system and a corresponding dry vacuum generation method capable of eliminating or substantially minimising the presence of condensate inside the pump during vacuum generation applied to a steam sterilisation chamber.

[0011] DESCRIPTION OF THE INVENTION

[0012] These purposes are achieved by a vacuum system and a method for generating a vacuum in a sterilisation chamber according to the claims at the end of this description.

[0013] In a first aspect of the invention, a vacuum system is provided for generating a vacuum without the use of water in a sterilisation chamber of a steam steriliser, wherein said vacuum system comprises an inlet connected to the outlet of the sterilisation chamber and a discharge outlet, and wherein said vacuum system further comprises a dry vacuum pump for generating vacuum without the use of water inside the sterilisation chamber having a pump inlet coupled to the inlet of the system and a pump outlet coupled to the discharge outlet of the system, and a plurality of valves arranged between the inlet and the discharge outlet of the system for regulating the amount of condensate within the system, wherein the dry vacuum pump is a variable speed pump.

[0014] Thanks to this system, it is possible to vary the speed of the pump and therefore vary the quantity of fluid (air / vapour) eliminated from the sterilisation chamber over time, for example by intensifying elimination during a specific period in the vacuum generation cycle, such as in each vacuum demand phase when the pump itself needs to be started. This reduces condensate inside the pump body, extending the pump's service life and maintaining high performance throughout the cycle under all conditions .

[0015] In a second aspect of the invention, a method is provided for generating a vacuum without the use of water in a sterilisation chamber of a steam steriliser by means of a sterilisation cycle, wherein the method comprises generating vacuum inside the sterilisation chamber by means of a dry vacuum pump coupled to the outlet of the sterilisation chamber, and regulating the amount of condensate inside the system through a plurality of valves, wherein the vacuum is generated at variable speed at least during an initial period of each phase of the cycle when vacuum is required.

[0016] It should be noted that the vacuum system described above is used with this method and serves to optimise condensate removal according to the various sterilisation cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] These and other aspects of the present invention will become more apparent in light of the following description of certain preferred embodiments described below.

[0018] Fig. 1 shows a schematic representation of a system for generating a vacuum in a steam sterilisation chamber according to one example .

[0019] Fig. 2A shows a functional diagram of the system for vacuum generation according to an example.

[0020] Fig. 2B shows a detail of the functional diagram of figure 2A.

[0021] Fig. 3A shows the temperature variation over time in a sterilisation cycle according to an example.

[0022] Fig. 3B shows the pressure variation over time in a sterilisation cycle according to an example .

[0023] DETAILED DESCRIPTION OF EMBODIMENTS

[0024] OF THE INVENTION

[0025] Figure 1 shows a schematic representation of the vacuum generation system 1 applied to a steam steriliser 3. The system 1 is used to generate a vacuum inside sterilisation chamber 2 of the steriliser 3. Therefore, the vacuum system 1 comprises an inlet 4 connected to the outlet of the sterilisation chamber 2 and a discharge outlet 5 for expelling or releasing air, steam, condensate or gas extracted from sterilisation chamber 2. As schematically shown in Figure 1, the system 1 comprises a dry vacuum pump 6 for generating a vacuum inside the sterilisation chamber 2, having a pump inlet coupled to the inlet 4 of the system 1 and a pump outlet coupled to the discharge outlet 5 of the system 1. In addition, the system 1 comprises a set of valves 11, 12, 13, 14, 15, for regulating the amount of vacuum generated and the treatment of condensate generated within system 1. Note that between the inlet of the system 1 and that of the dry vacuum pump 6, as well as between the outlet of the dry vacuum pump 6 and the discharge outlet 5, there may be one or more valves to control the flow of air / gas / vapour to be extracted from chamber 2 and thus regulate the condensate.

[0026] The dry vacuum pump 6 is a dry pump and a variable speed pump, which is advantageous. In particular, said pump can be controlled by an electronic control system that allows the desired speed to be set according to the application specifications . The inclusion of speed control allows an acceleration ramp to be created at start-up, i.e. in the initial phase of each vacuum generation cycle, which helps the pump 6 to draw in air / gas / vapour progressively, allowing fluids to be introduced gradually into the pump, reducing localised condensate inside the pump body 6, increasing the life of the pump itself and improving its performance .

[0027] In one example, the vacuum system 1 comprises a pressure transducer 7 positioned downstream of the dry vacuum pump 6. The inclusion of a pressure control on the outlet of the dry vacuum pump 6 optimises its operation. In fact, since dry vacuum generation technology operates on the same principle as a compressor but with the connection reversed (the fluid is compressed on the discharge side) , if there were any back pressure on the discharge side, the pump 6 would not be able to discharge. This causes a sort of "blockage" that could damage the pump itself 6 as it continues to extract air from the compression chamber 2. The pressure transducer 7 can be coupled to a control unit that receives and analyses the signal generated by the transducer 7, i.e. reads the pressure value on the discharge. The control unit can activate an alarm procedure and interrupt the vacuum generation cycle to prevent damage to the pump 6.

[0028] Figure 2A shows a functional diagram of the vacuum system 1 in a sterilisation device 3. Figure 2B shows a detail of the diagram in Figure 2A, in particular the connections to the dry vacuum pump 6 and the discharge outlet 5.

[0029] With reference to Figures 2A and 2B, the multiple valves comprise an inlet valve 11 connected to the inlet 4 of the system 1. This valve 11 opens whenever the cycle phase requires a vacuum in the sterilisation chamber 2. In particular, the inlet valve 11 opens when the dry vacuum pump 6 starts up, controlled by an acceleration ramp, so that the condensate gradually moves from the sterilisation chamber 2 to the dry vacuum pump 6.

[0030] It should be noted that the operation of the variable speed pump 6 is intrinsically linked to the control of the adjacent valves according to the cycle sequence. The vacuum system 1 is configured to activate (e.g. open or close) one or more valves 11, 12, 13, 14, 15 depending on the speed reached by the pump 6. Specifically, the vacuum system 1 is configured to activate one or more valves 11, 12, 13, 14, 15 and keep them in a specific open or closed condition for a set period of time depending on the speed reached by the pump 6. For example, one or more valves 11, 12, 13, 14, 15 can be activated and then kept in an open or closed condition only during the period of time in which the speed of the pump 6 is variable, and then deactivated when the pump 6 has reached a constant speed. Alternatively, one or more valves 11, 12, 13, 14, 15 can be activated or deactivated cyclically and based on the operating time of the pump 6.

[0031] To ensure proper operation and a certain progression in vacuum generation, as mentioned above, the vacuum system 1 is configured to activate the inlet valve 11 according to the variable speed of the vacuum pump 6. In particular, the method for generating the vacuum described here comprises opening the inlet valve 11 immediately before starting the dry vacuum pump 6, and reaching the maximum speed of the dry vacuum pump 6 after a period of time at variable speed. In particular, the inlet valve 11 is activated (opened) each time pump 6 is switched on. The inlet valve 11 opens right before the vacuum pump 6 starts, when the pressure inside the chamber has been restored to atmospheric pressure. Under these conditions, variable speed, with maximum speed reached within a defined period of time, allows the condensate present in the initial suction phase to enter gradually. For example, this period of time may be between 10 and 15 seconds .

[0032] Furthermore, the multiple valves comprise an air inlet valve 12 connected to the inlet valve 11 to let air at atmospheric pressure into the system 1. The air inlet valve 12 (or ballast gas) opens to cool the dry vacuum pump 6 and to assist its drainage at the end of each cycle. This allows the dry vacuum pump 6 to draw in fresh air from outside, increasing the speed and flow rate of the air sucked into the discharge path of the remaining fluids.

[0033] More specifically, thanks to the use of the variable speed pump 6, the vacuum system 1 is configured to activate the air inlet valve 12 according to the variable speed of the vacuum pump 6. In particular, the method for generating the vacuum described here comprises opening the air inlet valve 12 at the same time as opening the inlet valve 11 for a time longer than that required for the dry vacuum pump 6 to reach its maximum speed. For example, the air inlet valve 12 is activated / opened for approximately 15 seconds (a duration greater than or equal to the total ramp time up to maximum speed) . Opening the air inlet valve 12 allows air at atmospheric pressure to enter from the external environment. This air intake has a diluting effect on the vapours in the initial phases of the vacuum, ensuring better performance and preventing damage to the impeller of the pump 6 due to corrosion caused by the impact of the vapour itself.

[0034] When the pump 6 is switched off, its variable speed is used in reverse, i.e. there is a decrease in the number of revolutions and during this period, for approximately two seconds after the start of the deceleration sequence, the air inlet valve 12 opens while the inlet valve 11 closes . When slowing down, this allows the pump 6 to restore atmospheric pressure inside itself, facilitating the movement of condensate to the discharge area.

[0035] In addition, the plurality of valves comprises a discharge valve 14 positioned between the air inlet valve 12 and the discharge outlet 5 of the system 1. The discharge valve 14 opens when direct discharge of the system 1 is required, emptying it of condensate or steam down to atmospheric pressure.

[0036] In addition, the plurality of valves comprise a stabilisation valve 13 connected in series to a condensate drain 15 which, during sterilisation, stabilises the pressure inside the chamber, ensuring the supply of steam to maintain a constant temperature. This valve 13 opens during the sterilisation plateau maintenance phase and allows gradual discharge of condensate through the pulsed introduction of new steam, maintaining saturated steam conditions inside system 1 to ensure a constant temperature. The condensate drain 15 allows the condensate generated to be drained through the stabilisation valve 13 without causing a sudden drop in pressure during the sterilisation plateau.

[0037] In particular, the stabilisation valve 13 and the condensate drain 15 are connected in parallel to the discharge valve 14 between the air inlet valve 12 and the discharge outlet 5 of the system 1.

[0038] In another example, the vacuum system 1 also comprises an evaporation system 8 at the dry vacuum pump 6 and upstream of the discharge outlet 5. For greater efficiency in condensate evaporation phenomenon, after entering the suction port of the pump 6 and passing through the two lobes, the vapour passes through a sort of evaporation system 8, which may be in the form of a labyrinth or coil, before being discharged.

[0039] In particular, the evaporation system 8, integrated inside the dry pump in the discharge area, may comprise at least one region maintained at a high temperature, in particular at a temperature that is also locally higher than 100°C. A pump preheating function (when the steriliser is first switched on) and the operation of the pump itself ensure that this temperature is reached and maintained. The presence of walls maintained at a high temperature allows additional re-evaporation of condensate coming from the chamber or generated in the suction path inside the vacuum system.

[0040] In one example, the vacuum system 1 further comprises a secondary discharge line 9 connecting the dry vacuum pump 6 to the discharge outlet 5. This secondary discharge line 9 is activated only at the end of the cycle (i.e. between one cycle and the next) in order to drain any residual condensate present in the drain labyrinth itself while the pump is running. In particular, the secondary discharge line 9 comprises an additional discharge valve 10. This valve 10 opens at the end of the cycle and, together with the air inlet valve 12, allows the pump discharge section 6 to dry, facilitating the drainage of any steam condensate that the pump was unable to evaporate or dispose of through the discharge outlet 5 during the cycle. In particular, the method for generating the vacuum described here comprises closing an inlet valve 11, opening the air inlet valve 12 and opening the additional discharge valve 10 at the end of the sterilisation cycle of the dry vacuum pump 6 for a period of time that is dependent on the operating period of the dry vacuum pump 6 in a cyclic manner.

[0041] In particular, at the end of the sterilisation cycle, the pump 6 remains on with the inlet valve 11 closed and the air inlet valve 12 and the additional discharge valve 10 remain open for a period of time that depends on the operating time of the dry vacuum pump 6 in a repeated manner, for example, for fifteen seconds every sixty seconds of the pump 6 operation. During the fifteen seconds when the valves 12 and 10 are open simultaneously, the pump 6 gradually increases speed until it reaches maximum speed, allowing air to gradually enter from outside. This pushes any residual condensate that the pump 6 was unable to evaporate during the normal cycle towards the outlet of the additional discharge valve 10. This sequence is repeated several times so that any condensate residue in the discharge section of the pump 6 can also be evacuated via the additional discharge valve 10. The rhythmic sequence of acceleration, followed by the progressive increase and decrease in flow rate during this phase, allows for better drying of the discharge path compared to the use of a fixed flow rate pump, which does not exhibit the same fluid dynamic phenomena.

[0042] The system 1 may also comprise an outlet check valve 16 (e.g. a clapet valve) upstream of the discharge outlet 5 and downstream of the dry vacuum pump 6. This valve 16 prevents discharge fluids from rising back up towards the dry vacuum pump 6.

[0043] Similarly, the system 1 may comprise an inlet check valve 17 upstream of the dry vacuum pump 6, in particular upstream of the inlet valve 11, to prevent liquid or gas flows from flowing in a single direction either in the vacuum condition during suction by the pump 6 or during condensate discharge from the system 1. In addition, upstream of the inlet check valve 17, there is a mechanical filter 18 to prevent objects from falling into the system 1 inside the circuit and thus into the dry vacuum pump 6.

[0044] In addition, the system 1 may comprise, at the inlet 4, a monitoring system comprising at least two analogic temperature probes 19, one of which is a control probe and the other a monitoring probe, which serve to monitor the temperature trend throughout the cycle. The monitoring system may also include two pressure transducers 20, one for control and the other for monitoring, to monitor the pressure inside the system 1 both when the dry vacuum pump is in operation (value lower than atmospheric pressure) and when steam is introduced into the chamber (value higher than atmospheric pressure) . In the event of a vacuum phase, the transducers read a value lower than atmospheric pressure, down to the full scale point of the dry vacuum pump 6 itself (i.e. down to approximately 45-40 mbar) .

[0045] Figures 3A and 3B show the temperature and pressure trends over time within a cycle. The cycle generally consists of an initial conditioning phase lasting approximately 20 minutes, which may vary depending on the load placed inside the steriliser; a subsequent heating phase and a sterilisation phase in which the temperature and pressure reach a value that is maintained for the set sterilisation time (plateau) . The sterilisation phase is followed by a discharge phase, a drying phase and, if necessary, a prolonged drying phase. Finally, the cycle ends with an aeration phase.

[0046] In detail, as shown in Figure 3A, the temperature trend is pulselike during the conditioning phase, with steadily increasing peaks, since during each alternating pulse, air is removed from the vacuum pump and steam is introduced. During the sterilisation phase, this value is adjusted to keep it steady for the whole sterilisation time. Thereafter, during the unloading, drying and ventilation phases, the values recorded are not significant given the rapid fluctuation of the recording itself.

[0047] As shown in Figure 3B, the pressure trend is defined by the programme set points which, for example in the initial stages of conditioning, alternate steam injections (positive pressure peaks) and vacuum generation (negative pressure peaks) to allow the sterilisation chamber and its contents to heat up gradually. Thereafter, the pressure rises until the sterilisation temperature is reached and, if the steam condition reached is that of saturated steam, the pressure is linked to the temperature by a specific table correspondence on the Mollier curve. During the unloading, drying and aeration phases, the programme 's pressure set points control the activation of the vacuum pump or the introduction of external air until atmospheric pressure is restored, allowing the chamber to open and identifying the end of the cycle.

[0048] A person skilled in the art may make a number of further modifications and variations to the system 1 and method described above in order to meet additional and contingent requirements, all of which are included within the scope of protection of this invention as defined by the attached claims .

Claims

CLAIMS1. Vacuum system (1) for generating the vacuum without the use of water in a sterilisation chamber (2) of a steam steriliser (3) , wherein said vacuum system (1) comprises an inlet (4) connected to the outlet of the sterilisation chamber (2) and a discharge outlet (5) , and wherein said vacuum system (1) further comprises : a dry vacuum pump (6) for generating a vacuum without the use of water inside the sterilisation chamber (2) , having a pump inlet coupled to the inlet (4) of the system (1) and a pump outlet coupled to the discharge outlet (5) of the system (1) , and a plurality of valves (11, 12, 13, 14, 15) arranged between the inlet (4) and the discharge outlet (5) of the system (1) for regulating the amount of condensate within the system (1) , wherein the dry vacuum pump (6) is a variable speed pump.

2. Vacuum system (1) according to claim 1, further comprising a pressure transducer (7) positioned downstream of the dry vacuum pump (6) .

3. Vacuum system (1) according to one of the preceding claims, further comprising an evaporation system (8) at the dry vacuum pump (6) and upstream of the discharge outlet (5) .

4. Vacuum system (1) according to claim 3, wherein the evaporation system (8) comprises at least one region maintained at a high temperature, in particular at a temperature greater than 100°C.

5. Vacuum system (1) according to one of the preceding claims, further comprising a secondary discharge line (9) connecting the dry vacuum pump (6) to the discharge outlet (5) .

6. Vacuum system (1) according to claim 5, wherein the secondary discharge line (9) comprises an additional discharge valve (10) .

7. Vacuum system (1) according to one of the preceding claims, wherein the plurality of valves (11, 12, 13, 14, 15) comprise an inlet valve (11) connected to the inlet (4) of the system (1) , an air inlet valve (12) coupled to the inlet valve (11) for introducing air at atmospheric pressure into the system (1) , a stabilisation valve (13) positioned between the air inlet valve (12) and the discharge outlet (5) of the system (1) and a discharge valve (14) connected in series to a condensate drain (15) .

8. Vacuum system (1) according to claim 7, wherein the stabilisation valve (13) and the condensate drain (15) are connected in parallel to the discharge valve (14) between the air inlet valve (12) and the discharge outlet (5) of the system (1) •9. Method for generating the vacuum without the use of water in a sterilisation chamber (2) of a steam steriliser (3) by means of a sterilisation cycle, wherein the method comprises: generating vacuum inside the sterilisation chamber (2) by means of a dry vacuum pump (6) coupled to the outlet of the sterilisation chamber (2) ; and regulating the amount of condensate inside the system (1) through a plurality of valves (11, 12, 13, 14, 15) , wherein the vacuum is generated at variable speed at least during an initial period of each phase of the cycle when the vacuum is required.

10. Method according to claim 9, further comprising monitoringthe presence of back pressure at the outlet of the dry vacuum pump (6) .

11. Method according to one of claims 9 to 10, further comprising the activation of an additional evaporation process at the dry vacuum pump (6) and upstream of the discharge outlet (5) .

12. Method according to one of claims 9 to 11, further comprising drying at the end of the cycle of the discharge region of the dry vacuum pump (6) .

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