WO2014033767A1

WO2014033767A1 - Apparatus and method for distribution and monitoring of gas in gas pipelines

Info

Publication number: WO2014033767A1
Application number: PCT/IT2013/000231
Authority: WO
Inventors: Giuliano Lotta
Original assignee: Energy Automation S.R.L.
Priority date: 2012-08-31
Filing date: 2013-08-30
Publication date: 2014-03-06
Also published as: ITUD20120150A1

Abstract

An apparatus and a method for the distribution and monitoring of gas fuel, capable to detect both huge and small gas leaks with a rapid detection of gas leaks. A plurality of pipelines for the fuel gas, are disposed within an interior compartment, and are all configured to allow the flow of the fuel gas, or, alternatively, to maintain the fuel gas inside them in static conditions for monitoring. By realizing a cyclically switch from operational to monitoring condition (and vice versa) of pipelines, it achieves a constant control of the correct functioning of the distribution of gas, and it is able to distribute the fuel gas securely to an engine even in case of leakage.

Description

APPARATUS AND METHOD FOR DISTRIBUTION AND MONITORING OF GAS IN

GAS PIPELINES

TECHNICAL FIELD

The present invention relates to an apparatus and a method for the distribution of gas in pipelines for gas, in particular in pipelines for supplying fuel gas to internal combustion engines, and for the monitoring and control of the correct operation of gas distribution.

The present invention is usable, preferably, but not exclusively, in internal combustion engines for naval propulsion.

BACKGROUND ART

It is known that, for example for naval propulsion, internal combustion engines are used, fueled by diesel (Diesel cycle) and/or natural gas, or other similar fuels, or even engines with combined Diesel and gas cycle (dual fuel).

It is also known, in the case of gas supply (simple or combined cycle), that the pipes for the supply of gaseous fuel to these engines must be controlled and monitored in order to avoid any loss or leakage of combustible gas, which would lead to seryoutube massaggioious security risks, as well as an increase in fuel consumption.

The need of monitoring the gas piping line is particularly important for those pipelines that, for example on board of a ship, need to pass in confined spaces.

A first known system for the distribution and monitoring of pipelines for gas, also called a "double pipe", consist of a first tube placed inside a second tube. In the first tube flows the fuel gas, and in the inter-space between the first and second tube is present an inert gas under pressure.

The pressure of the inert gas, greater than that of the fuel gas, is continuously monitored. Any losses of the first pipe will lead to a decrease in the pressure of the inert gas under pressure, due to the tendency of the inert gas to seep inside the first tube. Conversely, leaks or cracks in the second tube would lead to the reduction of the inert gas pressure. Both pressure variations are detected by suitable means of pressure measurement .

Although this known solution allows for both a rapid detection of gas leaks and possible sealing defects of the second pipe (even in the case of small leaks), it has the drawback of requiring high installation and operating costs. In particular, to maintain the inert gas at a desired high and constant pressure, the weldings are required to be absolutely leak-proof: the implementaion of these weldings is complex and expensive, and costly materials, having particular physical and mechanical characteristics, are required.

Another system, called "ventilated duct", with a structure similar to the previous "double pipe" system is known, where in the interspace between the first and the second tube air flows at a lower pressure compared to that of the fuel gas. The air is subject to forced ventilation and has a capacity to perform a high number of air changes per hour of the entire volume of the interspace where it flows.

The latter solution, although it is distinguished from the previous one because of the reduced costs of production, installation and management, has the drawback of slowly detecting leaks of fuel gas, resulting inefficient especially when it comes to small leaks. This detection, in fact, since it is done by measuring the pressure drop and/or the presence of fuel gas inside the first tube and/or variations of air flow into the compartment in between the first and the second tube, is only effective in the presence of evident breakage of the inner tube or the outer one.

A further drawback of the "ventilated duct" system is the fact that small leakage of fuel gas from the first pipe are substantially diluted within the flow of air, thus being hardly detectable. It is known, for example, that such known devices, in pipelines at high pressure, for instance about 250 bar, are able to detect only losses of fuel gas above a certain threshold, as 1 kg / s.

It is also a drawback of both systems, the inability of identifying with certainty and quickly the losses of fuel gas, in the presence of changing load conditions of the engine .

One purpose of the present invention is to develop a method, and to realize an apparatus for the distribution and monitoring of gas fuel to an internal combustion engine, that allow for detecting both huge gas leaks, and losses of small gas quantities.

A further purpose of the present invention is to provide a method, and to realize an apparatus, which enable a rapid detection of gas leaks .

It is also an additional purpose of the invention to achieve a method for monitoring of gas pipelines which ensures a constant control of the correct functioning of the distribution of the gas.

A further purpose of the present invention is to provide an apparatus for the distribution of gas that is able to distribute fuel gas securely to an engine even in case of leakage .

It is a still further goal of the invention to achieve an apparatus that allows to maintain low costs of construction and installation.

To overcome the drawbacks of the prior art and to obtain these and other purposes and advantages, the Applicant has devised, tested and embodied the present invention. DISCLOSURE OF INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In agreement with the above purposes, an apparatus for the distribution and monitoring of fuel gas according to the present invention, comprises an external pipe which defines an internal compartment in which flows a gaseous fluid subjected A further purpose of the present invention is toto forced ventilation.

According to an aspect of the present invention, the apparatus mentioned above includes a plurality of pipelines for the fuel gas, disposed within the above mentioned interior compartment, which are both configured to allow the flow of fuel gas and, alternately, to maintain' the combustible gas inside them in static conditions. Adjustment means are also arranged, associated to each of these pipelines, to switch alternately, in each pipeline, the flow condition into the static condition, in such a way that, when in use, at least one of the above pipeline has the fuel gas in flow condition, and at least another pipeline has the fuel gas in static condition.

In this way is obtained the advantage of selecting the pipeline, or pipelines, which performs, or carry, the distribution of fuel gas, for example to a equipment such as an internal combustion engine, being simultaneously able to close or to isolate, at least another pipeline, for example to monitor the operation. An apparatus thus realized has therefore a considerable flexibility, combined with the safety deriving from the detection of possible failures, or leakage, even during normal operation.

According to a further aspect of the invention, the pressure with which the gaseous fluid flows in the interior compartment is lower than the pressure with which the fuel gas flows in these pipelines.

This allows to easily detect any leaks or malfunctions of the pipelines, since the fuel gas leaked is led towards detectors by the gaseous fluid.

According to a further aspect of the present invention, the above mentioned adjustment means comprise at least a first control valve and a second control valve, which are associated to each of these pipes. These control valves have the function to selectively lead the pipelines to a normal operating condition, in which the first control valve and the second control valve are both open to allow the flow of the fuel gas, and a monitoring condition, in which the first control valve and the second control valve are both closed, to prevent the flow of the fuel gas and to maintain under pressure the fuel gas in a static condition.

In this way is achieved the advantage of constantly controlling the operation of the pipelines for the distribution of gas fuel, giving considerable safety to the apparatus under discussion. The fact that the monitoring of the pipelines occurs in a static condition makes the detection of any anomalies reliable and fast and allows for a rapid response in the case these are detected.

It is also an advantage associated with the monitoring in static conditions of the fuel gas, the fact that in this way such a monitoring is not affected or invalidated by any load variations in the load of its normal operation by equipment to which the gas fuel itself is distributed.

It is a further aspect of the present invention the fact that the apparatus includes at least a pressure meter ,

associated with each pipeline, and positioned downstream of the first control valve, with respect to the flow of fuel gas, in order to measure the pressure of the fuel gas at least in a stretch of that pipeline between the first control valve and the second control valve .

According to a further aspect of the present invention, the apparatus being discussed comprises a control unit, capable of controlling the opening, closing and adjustment of the above mentioned first and second control valve, to regulate the flow of the fuel gas and to let these pipelines assume alternately the above mentioned condition of normal operation and the monitoring condition.

It is also an aspect of the invention to assure that the above mentioned pressure meter is connected electronically to the control unit in order to send to the latter the signals correlated with the trend of the pressure in the aforementioned stretch of given pipeline.

The subject of the present invention is also a method for the distribution and monitoring of gas fuel which requires a flow in forced ventilation of a gaseous fluid along an inner compartment of an external pipe and which allows to operate a plurality of pipelines for the gas fuel in such a inner compartment alternately in a normal operating condition or a monitoring condition. In the condition of normal operation, the fuel gas flows within at least one of the pipelines, and in the monitoring condition at least one of the other pipelines has the fuel gas in a static condition and the internal pressure of the gas fuel is monitored, for the desired monitoring time.

Such an alternation advantageously allows to keep the distribution of fuel gas to the equipmnts both during the monitoring, as well as in the case in which a pipeline is closed, following the detection of malfunctions.

It is also an aspect of the invention to assure that during the monitoring time the pressure within the pipeline that has the fuel gas in a static condition is maintained constant.

This advantageously allows to effectively detect any loss or leakage, via the above mentioned pressure deviations with respect to the desired constant value.

Furthermore, the alternation of monitoring and normal operation allows for a rapid detection of any malfunction of a pipeline, since the response occurs at most after a period of time equal to twice the aforementioned monitoring time, which advantageously has a short duration.

BRIEF DESCRIPTION OF DRAWINGS

These and other features of the present invention will become apparent from the following description of an embodiment, given as a non-restrictive example, with reference to the attached drawings in which:

- The fig. 1 is a schematic representation of an apparatus according to the present invention;

- The fig. 2 is a diagram of one embodiment of the apparatus of fig. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the attached figures, is shown schematically an apparatus 10 for the distribution of fuel gas according to one embodiment of the present invention, associated with an internal combustion engine 11.

The apparatus 10 (fig. 1) picks based on known "ventilated duct", preserving the advantages, improving performance and overcoming the drawbacks.

The apparatus 10 comprises an external pipe 12, which defines an internal compartment 13, within which is contained a plurality of conduits 14, 15, in this case a first pipe 14 and a second pipe 15, in the case in example substantially parallel between them and the outer pipe 12 itself.

In the first conduit 14 and in the second conduit 15 flows fuel gas that comes from a supply line 16 (fig. 2) and which is conveyed towards a supply duct 17 of the engine 11. In the aforementioned first and second pipeline, 14, 15, the fuel gas can flow to a variable pressure depending on the load to which the engine 11 is subjected.

In the inner compartment 13 (fig. 1) flows air, or other similar gaseous fluid, subjected to forced ventilation. The air flow is such as to allow a total replacement of the air contained in the outer pipe 12 at least 30 times in an hour.

The air pressure in the inner compartment 13 is lower than that of the fuel gas in the pipes 14 and 15 which, instead, can reach high values, from a few bars up to hundreds of bars. In this way, any possible leakage, or loss, of fuel gas, flows from the first pipes 14 and second pipe 15, to the interior compartment 13. The fuel gas which may come from the pipes 14 and 15 shall then dragged from air to detectors, not shown in the figures, that detect the content of combustible gas in the air and possibly transmit a signal which causes the interruption of the operation of the engine 11 .

Both the first pipe 14 and the second pipe 15 are associated (fig. 2) to a first control valve 18, a second control valve 19 and a by-pass valve 20.

The apparatus 10 also includes a control unit 22 configured to manage the distribution and monitoring of the gas.

Furthermore, in embodiments of the apparatus 10, each pipeline 14, 15, is associated with a pressure meter 21, for measuring the pressure of the fuel gas downstream of the first control valve 18.

The operation of the apparatus 10 is continuously monitored, on the basis of a method that involves the monitoring of the alternating flow of fuel gas within the first pipeline 14 and the second pipeline 15. In particular, the method for monitoring according to the present invention, requires that while the first pipeline 14 is in a condition of normal operation, namely supply of fuel gas to the engine 11 , the second pipeline 15 is in a monitoring condition, for check its functionality, and vice versa, provide

In order to allow the passage from the above normal operating condition to the monitoring condition, and vice versa, the above-mentioned first control valve 18 , the second control valve 19 and by-pass valve 20 are used, for each pipeline 14 and 15 .

These valves have the task of regulating, and selectively allow or prevent the flow of fuel gas within the first pipeline 14 and the second pipeline 15 .

The control unit 22 , in some embodiments, may be associated with the pressure meter 21 , the control valves 18 , 19 , the by-pass valve 20 and the engine 11 . The control unit 22 is able to control the operation of the regulating valves 18 and 19 on the basis of signals received by the pressure meter 21 . On the basis of these signals, the control unit 22 is able, moreover, to interrupt or limit the operation of the engine 11 , in case of anomalies in the distribution of the fuel gas during the step of monitoring.

In a preliminary phase, or starting, after the apparatus 10 has been associated with the engine 11 , a preliminary test is performed to check for proper installation and proper functioning of the components of the apparatus 10 prior to their use.

By way of example, in the following will be described a preliminary test of control for the first pipeline 14 . Similarly, it is the procedure adopted for the second pipeline 15 .

Such pre-test requires that initially the supply line 16 , the first pipeline 14 and the second pipeline 15 are not under pressure and that the first control valve 18 , the second control valve 19 and the check valve by-pass 20 are closed. Thereafter, the supply line 16 is placed under pressure and the value of pressure measured by the pressure meter 21 is monitored, for a first period of the preliminary check, with duration proportional to the length and section of the pipe 23, and to a pressure of normal operation of the line of fuel gas. If this value increases, the control unit 22 indicates a defect in the sealing of the first control valve 18.

If any variation of pressure is not detected, the first control valve 18 is opened, while maintaining closed the second control valve 19 and the by-pass valve 20. During a second period of the preliminary check, corresponding with the transient time of pressurization of the portion 23 of the first pipeline 14 between the first control valve 18 and the second control valve 19, the value of pressure detected by the pressure meter 21 is monitored again. In the case in which the pressure meter 21 does not detect changes in pressure, the control unit 22 indicates a defect of the pressure meter 21 or the opening of the first control valve 18 or the closing of the second control valve 19 or the by-pass valve 20.

In the case of correct response of the pressure meter 21, after the pressurization of the portion 23, the first control valve 18 is closed and the measurement of the pressure meter 21 is monitored for a third period of preliminary check of duration proportional to the length and section of the pipe 23, and the normal operating pressure of the fuel gas line. If the pressure value detected by the pressure meter 21 decreases, the control unit 22 indicates a possible leakage of the first pipe 14, or a leak of the first control valve 18, or the second control valve 19, or even by-pass valve 20.

In the case in which, at the end of all three of the above mentioned periods of preliminary check, the measurements of the pressure meter 21 conform to what is expected, the normal operation of the apparatus 10 is started, fueling with gas fuel both the first pipeline 14 , and the second pipeline 15.

In the following, the method of monitoring of pipelines 14 and 15 will be described in detail, with reference to the monitoring of the first pipeline 14. Consider that for the second pipeline 15, the same considerations apply that will be made for the first pipeline 14, and that, as mentioned, the two pipes 14 and 15 are used cyclically and alternately.

The above mentioned condition of normal operation of the first pipeline 14 is determined by the simultaneous opening of the the first control valve 18 and the second control valve 19, while keeping closed the by-pass valve 20. In this way, the fuel gas flows properly from the supply line 16 to the suction pipe 17 of the engine 11.

From the condition of normal operation, after the desired time interval has elapsed, the first pipeline 14 is brought into the aforementioned monitoring condition, by closing the second control valve 19, and then the first control valve 18. This closure ordering is intended to keep the portion 23 of the first pipe 14 to the desired pressure, such as that of the supply line 16.

The pressure inside the first pipe 14, downstream of the first control valve 18, is therefore monitored by the pressure meter 21, for a desired monitoring time. The monitoring period should be long enough, being related to the internal volume of the pipe 23 and the normal operating pressure of the fuel gas line so as to prevent the measurement of the pressure meter 21 is altered by transients related to the opening and the closing of the regulating valves 18, 19.

If during this time of monitoring the pressure detected by the pressure meter 21 decreases, the control unit signals the presence of a leak in the first pipeline 14, or the failure of the by-pass valve 20.

In this case, the control unit 22 arranges for the block of the first control valve 18 and the second control valve 19 and the opening of the venting valve 20, excluding the first pipeline 14 by the distribution of gas fuel to the engine 11 and entrusting this distribution solely to the second conduit 15. The functioning of the apparatus 10 is then downgraded to the already known "ventilated duct." This possibility of excluding completely a pipeline without foreclosing the supply of fuel gas to the engine 11 achieves the flexibility of the apparatus 10 made according to the present invention, as well as high safety.

In the case anomalies in the pressure in the portion 23 are not detected, at the end of the above mentioned monitoring time the first pipeline 14 is returned to the normal operating condition. Subsequently, or simultaneously with this operation, the second control valve 19 and the first control valve 18 of the second pipe 15 are closed, in succession, bringing the latter pipe in the monitoring condition.

Elapsed again a time equal to the above mentioned monitoring time, the second pipeline 15 is returned to the condition of normal operation and, subsequently or simultaneously, the first pipeline 14 to the monitoring condition .

Such alternation of normal operation and monitoring condition is repeated cyclically during the functioning of the engine/equipment and allows to quickly detect any loss or leakage of fuel gas in the first pipeline 14 and the second pipeline 15, as the most time delay in detection is equal to twice the monitoring time.

Furthermore, the fact that the monitoring is carried out by isolating the pipelines 14, 15 from both the supply line 16 and the engine 11, allows to monitor the operation irrespective of any pressure variations due to load variations of the engine 11 itself. This gives reliability to the monitoring method according to the invention, which also allows to detect even small leaks, thanks to the controlled pressurization of the portion 23.

A variant of the method for the monitoring of pipelines described above, allows also to carry out the control of the functionality and reliability of the first control valve 18, the second control valve 19, the by-pass valve 20 and the pressure meter 21, at periodically predetermined intervals or occasionally on the basis of contingent needs. This variant allows that the control unit 22 suspends the cyclic alternation between a normal operating condition and monitoring condition, and arrange for a check of the components and the instruments associated with a given pipeline, keeping the other pipeline constantly in normal operating condition.

In this way, the procedure of continuous alternating monitoring described above, is coupled with a phase of random verification, further increasing the reliability and safety of the apparatus 10.

For example, to check the components associated with the first pipeline 14, when both the pipes 14 and 15 are in normal operation, the second control valve 19 and the first control valve 18 of the first pipeline 14 are closed in sequence, after which pressure is monitored in the stretch 23. If this pressure drops, the control unit 22 indicates a possible loss of the first pipeline 14 or a failure of the valve by-pass 20.

In case no abnormality is detected, the control unit 22 proceeds by opening the valve by-pass 20, the pressure in the portion 23 of the first pipe 14 is then monitored for a second time, via the pressure meter 21, to verify that the measured value decreases. In the negative case, the control unit 22 indicates a failure of the pressure meter 21 or by-pass valve 20. In the positive case, the control unit 22 proceeds by closing the valve by-pass 20. Is then monitored, for a third time, the pressure value measured by the pressure meter 21. If this value increases over time, the control unit 22 notifies a malfunction of the first control valve 18 and/or of the second control valve 19.

In the case of where all the monitoring mentioned above yield results consistent with the correct functionality of the monitored components_/ the control unit 22 returns the first pipeline 14 in the condition of normal operation and restart the cyclic alternating procedure of normal operation and monitoring operation.

It is clear that the method and apparatus described so far can be subject to modifications and / or additions of parts, without departing from the scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person skilled in the art shall certainly be able to achieve many other equivalent forms of method and apparatus for the distribution and the monitoring of pipelines for gas, having the characteristics expressed in the claims and hence all coming within the scope of protection defined thereby.

Claims

1. Apparatus for the distribution and monitoring of fuel gas, comprising an outer pipe (12) which defines an internal compartment (13) in which flows a gaseous fluid subjected to forced ventilation, characterized in that it comprises a plurality of pipes (14, 15 ) for the fuel gas, disposed within above mentioned interior compartment (13), which are both configured to allow the flow of the fuel gas, or, alternatively, to maintain the combustible gas inside them in static conditions, with adjustment means (18, 19) associated with each of above mentioned pipes (14, 15) in order to switch alternately, in each of the pipes (14, 15), from the condition of flow to the static condition, in such a way that, when in use, at least one of the pipes (14, 15) has the fuel gas in flow conditions, and at least another pipe (14, 15) has the fuel gas in static conditions.

2. Apparatus as in claim 1, characterized in that the pressure of the gaseous fluid flowing in above mentioned inner compartment (13) is lower than the pressure of the fuel gas that flows in the pipes (14, 15) in the flow condition.

3. Apparatus as in claim 1 or 2, characterized in that the adjustment means comprise at least a first control valve (18) and a second control valve (19), the first control valve (18) and the second control valve (19) being associated with each of the pipes (14, 15), in order to selectively set the pipes (14, 15) to a condition of normal operation, in which the first control valve (18) and the second control valve (19) are both open to allow the fuel gas to flow, and a monitoring condition, in which the first control valve (18) and the second control valve (19) are both closed, to prevent the flow of fuel gas and keep the fuel gas under pressure in static conditions .

4. Apparatus as in claim 3, characterized in that it comprises at least one pressure meter (21), associated with each of the above mentioned pipes (14, 15), and positioned downstream of the first control valve (18), relatively to to the flow of the fuel gas, to measure the pressure of the fuel gas in at least a portion (23) of a given pipe (14, 15) between the first control valve (18) and the second control valve (19).

5. Apparatus as in claim 3 or 4 , characterized in that it comprises a control unit (22), capable of controlling the opening, closing and adjustment, of the above mentioned first control valve (18) and the second control valve (19), to regulate the flow of the fuel gas and to let alternately the pipes (14, 15) to acquire the condition of normal operation or the monitoring condition.

6. Apparatus as in claims 4 and 5, characterized in that above mentioned pressure meter (21) is electronically connected to the above mentioned control unit (22) to send to the control unit the signals correlated with the trend of the pressure in the portion (23) of the given pipe (14, 15).

7. Method for the distribution and monitoring of gas fuel wherein a flow of a gaseous fluid is in forced ventilation along an inner compartment (13) of an external pipe (12), characterized by a plurality of pipes (14, 15 ) for the fuel gas disposed in the inner compartment (13), that are used alternately in a normal operating condition, in which the fuel gas flows inside at least one of the conduits (14, 15), and a monitoring condition, in which at least one of the other pipes (14, 15) has the fuel gas in static conditions, being the internal pressure of the fuel gas monitored, for a desired monitoring time.