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Title:
MOBILE APPARATUS FOR PRODUCING COMPRESSED AIR
Document Type and Number:
WIPO Patent Application WO/2013/037512
Kind Code:
A1
Abstract:
The method for producing compressed air, comprises the steps of prearranging a plurality of units (2) for generating compressed air mounted in parallel and suitable to feed a tank (6) of air under pressure; connecting the plurality units (2) for generating compressed air to an automatic start and stop system of the units (2) for generating compressed air; assigning to each unit (2) for generating compressed air a start pressure value and a stop pressure value in such a way that each generator unit (2) is started or stopped automatically as a function of the pressure of the air inside the tank (6), each start pressure value and each stop pressure value being different to each other so as to define a start and stop in sequence of the plurality of units (2) for generating compressed air; starting the plurality of generators (2) of compressed air so as to determine an increase of pressure inside the tank (6) until reaching a predefined pressure value; stopping automatically and in sequence the plurality of units (2) for generating compressed air while the pressure inside the tank (6), increasing, goes progressively over the stop pressure values of each unit (2) for generating compressed air until reaching the predefined pressure value; distributing compressed air through a distribution unit (10) fed by the tank (6).

Inventors:
VINCIGUERRA WALTER (IT)
Application Number:
PCT/EP2012/056439
Publication Date:
March 21, 2013
Filing Date:
April 10, 2012
Export Citation:
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Assignee:
R C N ITALIA DI ACCIARO M LUCIA (IT)
VINCIGUERRA WALTER (IT)
International Classes:
F04B35/06; F04B41/02; F04B49/02
Foreign References:
US20070077151A12007-04-05
US20070134104A12007-06-14
JPH08296566A1996-11-12
US4080103A1978-03-21
US20070134104A12007-06-14
GB769869A1957-03-13
EP1477676A12004-11-17
US2312728A1943-03-02
US20070077151A12007-04-05
JPH08296566A1996-11-12
EP0213092A21987-03-04
DE1088181B1960-09-01
US20100111724A12010-05-06
EP1975407A22008-10-01
US4080103A1978-03-21
US2626100A1953-01-20
Attorney, Agent or Firm:
MANZELLA & ASSOCIATI (Via Nosadella 9, Bologna, IT)
Download PDF:
Claims:
Claims

Method for producing compressed air, comprising the steps of

a. prearranging a plurality of units (2) for generating compressed air, such units being mounted in parallel and suitable to feed a tank (6) of air under pressure;

b. connecting said plurality of units (2) for generating compressed air to an automatic start and stop system for said units (2) for generating compressed air;

c. assigning to each unit (2) for generating compressed air a start pressure value and a stop pressure value in such a way that each said generator unit (2) is started or stopped automatically as a function of the air pressure inside said tank (6), each said start pressure value and each said stop pressure value being different from each other so as to define a start and stop in sequence of said plurality of units (2) for generating compressed air, said stop values of said plurality of units (2) for generating compressed air being comprised between 26,5 and 28 bar;

d. starting said plurality of units (2) for generating compressed air so as to determine an increase of pressure inside said tank (6) until reaching a predefined pressure value;

e. stopping automatically and in sequence said plurality of units (2) for generating compressed air while said pressure inside said tank (6), increasing, goes progressively over said stop pressure values of each said unit (2) for generating compressed air until reaching said predefined pressure value;

f. distributing compressed air by means of a distribution unit (10) fed by said tank (6). Method according to claim 1 , characterized in that it comprises the further steps of g. in case of a decrease of pressure inside said tank (6) due to said distribution of compressed air, starting automatically and in sequence said plurality of units (2) for generating compressed air while said pressure inside said tank (6), decreasing, progressively reaches said start pressure values of each said unit (2) for generating compressed air, so as to compensate said decrease of pressure inside said tank (6). Method according to claim 2, characterized in that, said start values of said plurality of units (2) for generating compressed air are comprised between 22 bar and 25 bar

Method according to any one of the previous claims, characterized in that said predefined pressure value is comprised between 22 and 28 bar.

Mobile apparatus for producing compressed air, comprising

a plurality of units (2) for generating compressed air mounted in parallel independent from each other, each said unit (2) for generating compressed air being provided with a manostat;

a feed collector (3) connected at the outlet of said plurality of units (2) for generating compressed air; a tank (6) connected at the outlet of said feed collector (3) and suitable to contain compressed air fed by said plurality of generator units (2);

a distribution unit (10) connected at the outlet of said tank (6) and suitable to enable the distribution of compressed air from said tank (6);

an automatic sequential start and stop system connected to said plurality of units (2) for generating compressed air and suitable to automatically perform the start and stop in sequence of said plurality of units (2) for generating compressed air as a function of the pressure inside said tank (6), the apparatus being characterized in that

it is mounted on a mobile device which enables the displacement thereof.

6. Apparatus according to claim 5, characterized in that said device is installed on a skid.

7. Apparatus according to claim 5, characterized in that it comprises said mobile device, said mobile device being a skid, on which said plurality of generator units (2), said feed collector (3), said a tank (6), said distribution unit (10), said automatic sequential start and stop system are entirely installed in a compact way, for enabling an easy transportation, for example overland or by sea.

8. Apparatus according to claim 5, characterized in that it comprises said mobile device, said mobile device being a platform or a trolley provided with wheels, on which said plurality of generator units (2), said feed collector (3), said a tank (6), said distribution unit (10), said automatic sequential start and stop system are entirely installed in a compact way, or a standardized container, in which said plurality of generator units (2), said feed collector (3), said a tank (6), said distribution unit (10), said automatic sequential start and stop system are entirely installed in a compact way, for enabling an easy transportation for example overland or by sea.

9. Apparatus according to any one of the claims from 5 to 8, characterized in that said distribution unit (10) comprises a collector member (1 1) connected to at least one outlet line (12a, 12b, 13) suitable to simultaneously distribute compressed air at varying pressure.

10. Apparatus according to any one of the claims from 5 to 9, characterized in that said plurality of units (2) for generating compressed air comprises four units (2) for generating compressed air.

Description:
Description

MOBILE APPARATUS FOR PRODUCING COMPRESSED AIR

Technical Field

[01] The present invention regards a method and a mobile apparatus for producing compressed air.

Background Art

[02] Nowadays has been known the use of mobile plants for producing compressed air to feed pneumatic apparatuses such as, for example, air motors, air control tools or various pneumatic automatisms, in the ambit of the industry in general, and oil industry in particular. Such apparatuses are mostly indispensible for the involved operating activity and cannot be interrupted.

[03] As an example, patent application US 2007/0134104 teaches a portable compressor package comprising a sub-frame module that comprises on its turn the machinery for a compressor, a containment frame module for supporting and transporting the sub-frame module and a canopy module for covering the compressor.

[04] A limitation of the known air plants stands in the fact that they comprise one only compressor, or a plurality of compressors connected between them in series, and in case of breakdown on a compressor, it is necessary to stop the entire plant for being able to perform the operations of repair or substitution of the non functioning compressor, with detrimental consequences on the productivity of the pneumatic apparatuses.

[05] The English patent GB 769,869 illustrates a mobile air compressor unit comprising at least two air compressors supported on a vehicle provided with a tubular chassis and serving as a collecting container for the compressed air. Both compressors are independent from each other and it is possible to perform the substitution of one without stopping the other.

[06] But such a solution does not completely satisfies the exigencies of the sector, as a defect on one compressor determines in anyway the lack of half the pumping capacity of the plant and the substitution operations result difficult to be performed. Furthermore, such an apparatus is not able to provide a high air flow rate during a prolonged time.

[07] Other examples for known solutions in the technical field in suit are illustrates in EP1477676A2, relating to a method of controlling a plurality of compressors, as well as in US2,312,728 relating to a compressor control system, in US2007/0077151A1 relating to a control system for air-compressing apparatus, in JP8296566 relating to a control device for the number of compressor, in EP0213092 relating to a method of controlling the pressure of a medium delivered by a compressor plant, in DE1088181 relating to a control system for a compressor plant, in US2010/011 1724A1 relating to an air compressing assembly, in EP1975407A2 relating to a two-pump air compressor, in US4,080, 103 relating to a portable air compressor system for respirator, in US2,626, 100 relating to a compressed air supply system.

Disclosure

[08] The task of the present invention is that of solving the aforementioned problems, devising an apparatus for producing compressed air which enables to provide a high air flow rate under pressure during a prolonged time in a reliable way.

[09] Within such task, it is a further scope of the present invention that of providing an apparatus for producing compressed air which is able to face up unexpected situations, as for example a breakdown of a compressor, without having negative consequences on the operations.

[10] Another object of the invention is that of providing an apparatus for producing compressed air, which is easy to maintain.

[11] A further object of the present invention is that of providing an apparatus for producing compressed air, having a simple conception, a securely reliable functioning and versatile use, as well as relatively economic cost.

[12] The cited scopes are attained, according to the present invention, by the method and by the mobile apparatus for producing compressed air according to claims 1 and 6.

[13] According to the present invention, the method comprises the steps of prearranging a plurality of units for generating compressed air, mounted in parallel and suitable to feed a tank of air under pressure; connecting said plurality of units for generating compressed air to an automatic start and stop system for said units for generating compressed air; assigning to each unit for generating compressed air a start pressure value and a stop pressure value in such a way that each said generator unit is started or stopped automatically as a function of the air pressure inside said tank, each said start pressure value and each said stop pressure value being different from the others so as to define a start and stop in sequence of said plurality of units for generating compressed air; starting said plurality of units for generating compressed air in a way as to determine an increase of pressure inside said tank until reaching a predefined pressure value; stopping automatically and in sequence said plurality of units for generating compressed air while said pressure inside said tank goes progressively over said start pressure values of each said unit for generating compressed air until reaching said predefined pressure value; distributing compressed air from a distribution unit fed by said tank.

[14] The invention further concerns a mobile apparatus for producing compressed air, comprising a plurality of units for generating compressed air mounted in parallel independent from each other, each said unit for generating compressed air being provided with a manostat; a feed collector connected at the outlet of said plurality of units for generating compressed air; a tank connected at the outlet of said feed collector and suitable to contain compressed air fed by said plurality of generator units; a distribution unit connected at the outlet of said tank and suitable to enable the distribution of compressed air from said tank; an automatic sequential start and stop system connected to said plurality of units for generating compressed air and suitable to perform automatically the start and stop in sequence of said plurality of units for generating compressed air as a function of the pressure inside said tank.

Description of Drawings

Details of the invention shall be more apparent from the detailed description of a preferred embodiment of the apparatus for producing compressed air according to the invention, illustrated for indicative purposes in the attached drawings, wherein:

figure 1 shows a schematic functional view of the apparatus in hand.

Best Mode

With particular reference to such a figure, the mobile apparatus for producing compressed air according to the present invention is indicated in its entirety with 1.

The apparatus 1 comprises a plurality of units 2 for generating compressed air, installed in parallel, which feed a feed collector 3. In the present case are illustrated four generator units 2 but the number can be anyone according to the exigencies.

Each generator unit 2 comprises a compressor 4 suitable to compress air to be dispensed and a dehumidifier 5 arranged in line, downstream of the compressor 4 and suitable to dehumidify the air at the outlet of the same. Each dehumidifier 5 is suitable to be started in an automatic way upon the starting of the compressor 4 to which it is connected.

The compressors 4 can be of any type, for example piston compressors, centrifugal compressors or screw compressors. To make the maintenance of the apparatus 1 easier, it is preferable that the compressors 4 to be all equal, but it is possible to provide compressors 4 of types or capacities different to each other, if required by the application. Preferably, each compressor 4 is provided with a manostat, not represented, connected to an automatic start and stop system of the compressor 4, in a way as to enable the automatic start and stop of each compressor 4 on the basis of detected pressure values. It is to be underlined that each automatic start and stop system connected to a compressor 4 is adjusted to predefined start and stop pressure values different to each other, so as to obtain a start and a stop in sequence of the compressors 4.

It is possible to provide that each one of the compressors 4 to be provided, downstream, with a refrigeration member, not illustrated, suitable to enable the control of the temperature of the discharge air.

Preferably, downstream of each dehumidifier 5 is installed a humidity discharger, not illustrated, suitable to discharge the condensate which accumulates at the outlet of the same dehumidifier 5.

It is to be noted that each one of the generator units 2 is provided with an individual electric board, known per se and not represented for simplicity, so as to be totally independent from each other, with the scope in particular of making the operations of substitution of a generator unit 2 easier in case of malfunctioning of one of them.

The mobile apparatus 1 also comprises a tank 6 suitable to contain a reserve of air under controlled pressure. The tank 6 is connected to the feed collector 3, so as to receive the compressed air at the outlet of the collector 3. The tank 6 provides a security valve 7, so as to avoid overpressures, and a calibration device 8 suitable to control and maintain the pressure at a constant level inside the tank 6. The tank 6 is also provided with a condensate discharger 9 suitable to discharge the possible accumulated condensate. It is to be noted that it is possible to program the frequency with which such a condensate discharger 9 intervenes.

The apparatus 1 comprises a unit 10 for distributing the compressed air, connected at the outlet of the tank 6. Such a distribution unit 10 comprises a collector member 1 1 to which are connected a plurality of outlet lines 12 suitable to dispense the compressed air with a predetermined pressure. In the illustrated example the distribution unit 10 includes a first and a second outlet line 12a, 12b, but it is possible to provide a different number of outlet lines according to the exigencies. The distribution unit 10 also comprises a manual valve 13 for the drawing of air.

In the illustrated example the first and the second outlet lines 12a, 12b are constructed differently as to each other, and are suitable to dispense air compressed under different pressures.

In the illustrated embodiment, the first outlet line 12a comprises a valve 120a connected, in series and upstream, to a pressure reducer 121 a suitable to reduce the pressure of the air at the outlet of the tank 6. A bypass valve 22a is linked in parallel to the reducer 2 a. Such a bypass valve 122a is preferably of the fine adjustment type, and is suitable to increase the air-drawing flow rate in the case wherein the flow rate of the compressed air through the reducer 121a is insufficient.

The first outlet line 12a further comprises a security valve 123a, provided with a calibration device 124a, connected in series and downstream of the pressure reducer 121a and suitable to protect devices arranged downstream of the same pressure reducer 121a. Downstream of the cited calibration device 124a are connected in series a filter 125a, preferably of the coalescence oil extractor type, suitable to remove impurities in the compressed air until a predefined limit, for example 1 mg/m 3 , and a lubricator member 126a. Such a lubricator member consists, for example, in an oiler suitable to nebulize an oil in the air flow, according to the requirements. At last, the first outlet line 12a comprises a dispenser member 127a through which the air under pressure is dispensed. In the illustrated example, the dispenser 127a consists in two end valves 128a, 129a mounted in parallel, but it is possible to provide any number of valves, or any type of dispenser according to the exigencies.

[30] The second outlet line 12b comprises a valve 120b connected, in series and upstream, to a pressure reducer 121 b analogous to the pressure reducer 121a of the first outlet line 2a. Moreover, the second outlet line 12b comprises a security valve 122b provided with a calibration device 123b, connected downstream to the pressure reducer 121 b. Downstream of the calibration device 123b is connected in series a filter 124b, of the coalescence oil extractor type, suitable to remove impurities in the compressed air. At the end of the second outlet line 12b is provided a dispenser member 125b through which is dispensed the air under pressure. The dispenser 125b consists in two end valves 126b, 127b mounted in parallel, but it is possible to provide any number of valves, or any type of dispenser according to the exigencies.

[31] It is to be noted that the apparatus 1 is suitable to be mounted on a device which enables the displacement thereof, such as for example a trolley provided with wheels, or skid.

[32] More precisely, the apparatus 1 comprises a device which enables its displacement, that is its transportation for example overland or by sea, such as for example a standardized container, a trolley or a platform provided with wheels or simply a standardized pallet or a skid. In any case the components of apparatus 1 , previously described, that is the generator units 2, the tank 6, the feed collector 3, the distribution unit 10, the automatic sequential start and stop system are entirely installed therein or thereon in a very compact way in order to constitute an easily deliverable and transportable item.

[33] It is also to be noted that the elements of the apparatus 1 , except the units 2 for generating compressed air, are electrically supplied through a general electric board with a suitable feed system, for example a three-phase system with neutral wire at a voltage of 400V and a power of 70 kW.

[34] The functioning of the mobile apparatus for producing compressed air turns out easy to understand from the preceding description.

[35] Firstly one provides to the determination of the pressure values for starting and stopping the compressors 4. It is preferable to define start and stop pressure values different for each compressor 4 so as to obtain a start and a stop in sequence of the plurality of compressors 4.

[36] In particular, in the preferred embodiment of the present invention, a first compressor 4a is programmed to stop when the pressure reaches, going up, a value of 28 bar, and to start when the pressure is less than 25 bar, or when the pressure decreases until this pressure value. Analogously, a second compressor 4b is programmed to start at a pressure inferior to 24 bar, or when the pressure goes down to such a value, and to stop when the pressure reaches the value of 27,5 bar. The start and stop pressure values of a third compressor 4c are respectively 23 bar going down and 27 bar going up, and for the fourth and last compressor 4d the start and stop pressure values are respectively 22 bar going down and 26,5 bar going up.

So it is to be noted that in the illustrated example, the aforesaid start and stop values of the compressors 4a, 4b, 4c, 4d are such as to maintain the pressure of the air contained inside the tank 6 between 22 and 28 bar.

The selection of the above mentioned ranges of the stop and/or start values is particularly effective as it results in a steady functioning of the compressed air producing apparatus 1. Before the start of the apparatus 1 according to the present invention, it is necessary to close the valves 121 a, 121 b and 13 on the distribution unit 10 downstream of the tank 6. In the following one provides to electrically supply the compressors 4a, 4b, 4c, 4d of the generator devices 2.

Upon starting the apparatus 1 , the pressure inside the tank 6 is substantially equal to the atmospheric pressure, that is 1 bar. At such a pressure value, the four compressor 4a, 4b, 4c, 4d are automatically started to feed the tank 6 with compressed air, providing so to increase the pressure inside the tank 6.

When the pressure detected in the tank 6 reaches the value of 26,5 bar, corresponding to the stop value of the compressor 4d, this latter stops, and the air under pressure is fed inside the tank 6 by the compressors 4a, 4b and 4c still working.

The pressure keeps increasing, and when it reaches the pressure value of 27 bar, the compressor 4c is automatically stopped. As there are still the compressors 4a and 4b in function, the feed of compressed air continues. Upon reaching a pressure of 27,5 bar, corresponding to the stop pressure value of the compressor 4b, the same compressor stops. Then the pressure keeps increasing, until reaching the stop value of the compressor 4a, equal to 28 bar in the illustrated example, provoking the stop thereof. At this point the compressors 4 are all stopped, and the tank contains a reserve of air at a pressure of 28 bar. So it is possible to proceed with the withdrawal of air through one of the lines 12a, 12b of the distribution unit 10, or through both simultaneously.

The proceeding for drawing compressed air provides the opening of the end valves 128a, 129a, 126b, 127b of the chosen outlet line 12a, 12b, maintaining the valves 120a, 120b closed. Then one provides to adjust the opening of the end valves according to the desired pressure of the drawn air.

In the following, one provides to open the valves 120a, 120b of the chosen outlet line 12a, 12b to enable the passage of the compressed air. At this point the pressure of the pressure reducer 121 a, 121 b is adjusted to the desired pressure value.

In the outlet line 12a, the pressure reducer 121a is suitable to reduce the air pressure until a value comprised between 1 ,5 and 15 bar. The in line connection of the filter 125a and of the lubricator 126a enables the dispense of a dried, filtered and lubricated air with a pressure comprised between 1 ,5 and 15 bar.

[47] In the outlet line 12b, instead, the pressure reducer 121 b is suitable to reduce the air pressure until a value comprised between 1 ,5 and 10 bar. The connection in series of the filter 24b enables the dispense of a dried and filtered, but not lubricated air, at a pressure comprised between 1 ,5 and 10 bar.

[48] It is to be noted that the presence of the valve 13 directly connected to the collector 11 enables to draw air directly from the tank 6, at a pressure comprised between 22 and 28 bar, according to the illustrated example.

[49] Distribution of air under pressure through an outlet line 12a, 12b or the valve 13 determines a decrease of the pressure of the air contained inside the tank 6. If the pressure decreases until reaching the start pressure value of the compressor 4a, equal to

25 bar, the same compressor 4a automatically starts to compensate the flow of the drawn air.

[50] Nevertheless if the flow of the compressor 4a is not enough, the pressure still decreases, and when it reaches the value of 24 bar, the compressor 4b starts automatically. In the same way, if the flow of the compressors 4a and 4b is not sufficient to stop the decrease of pressure inside the tank 6, when the pressure value of 23 bar is reached, the compressor 4c is automatically started. If, notwithstanding the further contribution of the compressor 4c, the pressure keeps decreasing, reaching the value of 22 bar determines the automatic start of the last compressor 4d.

[51] It is to be noted that, the compressors 4 being arranged in parallel and independent from each other, it is possible to proceed with the substitution of one of them without preventing the normal functioning of the other ones. In such a circumstance, only one quarter of the pumping capacity is temporarily lacking, in the case wherein the compressors 4 are identical.

[52] The method and the apparatus in hand attains the scope of providing a high flow of compressed air during a prolonged time in a reliable way. Such a result is obtained in particular thanks to the inventive idea of providing a plurality of units for generating compressed air mounted in parallel and independent from each other, which feed a tank of air under pressure.

[53] A characteristic of the method and of the apparatus in hand consists in the fact that the units for generating compressed air are programmed to start and stop automatically in sequence, so as to maintain automatically the pressure inside the tank in a predefined interval, also during the dispense of compressed air. The planning of the start and stop in sequence of the units for generating compressed air further enables to use only the necessary compressors and so to limit the electric consumption. Another advantage of the apparatus in hand is that of enabling the substitution of a broken unit for generating compressed air without provoking the total stop of the apparatus. As the units for generating compressed air are mounted in parallel and independent from each other, the dismounting of one of them implies the loss of only part of the flow rate of compressed air.

A further advantage of the apparatus in hand is that of being easy to maintain, as the units for generating compressed air are easy to dismount.

Moreover, the apparatus in hand being mounted on a skid in a compact manner, it results easily and rapidly transportable according to the exigencies.

The apparatus described for indicative purpose is susceptible of numerous modifications and variants according to the diverse exigencies.

In practice, the embodiment of the invention, the materials used, as well as the shape and dimensions, may vary depending on the requirements.

Should the technical characteristics mentioned in each claim be followed by reference signs, such reference signs were included strictly with the aim of enhancing the understanding the claims and hence they shall not be deemed restrictive in any manner whatsoever on the scope of each element identified for exemplifying purposes by such reference signs.