JP4850503B2 - Gaseous fuel supply system for energy generation unit of ship for transportation of liquefied gas - Google Patents

Description

  The present invention relates to an apparatus for supplying gaseous fuel to an energy generating unit of a ship for transporting liquefied gas, wherein the gaseous fuel is supplied before being supplied to the energy generating unit via at least one feed manifold. Compressed to a supply pressure by one or more devices.

  The present invention relates to adjusting and servo-controlling the gas supply under pressure to an energy generator supplied with gas from a liquefied gas carrier, the unit comprising, for example, a set of one or more diesel generators Or may include one or more gas turbines. The operating characteristics of an energy generator supplied with gas are generally that the gas supply should be carried out at a relatively low supply pressure, and that pressure can be, for example, around 4 bar (0.4 MPa). Is implied. In stable conditions, this supply is generally accurately performed by existing compressor equipment capable of delivering gas at the desired flow rate and supply pressure. By way of example, such devices include pumps that supply compressors and / or evaporators, which generally feed the feed manifold so as to maintain the feed manifold pressure close to the value of the reference supply pressure. In particular, it is controlled by a pressure regulator.

  When the energy generator load changes, the change leads to an increase or decrease in gas consumption, which generally causes a decrease or increase in supply pressure in the manifold. Given the limited manifold volume, the distance between the compressor and the feed manifold, and the response time of the compressor, the pressure servo control achieved by the compressor based pressure regulator is not negligible. Suffer from hysteresis. As a result, after a change in the energy generator load, a certain time interval occurs before a stable supply pressure is established again in the manifold.

  Such a change in the load of the energy generating unit is due to the fact that a speeding up or slowing down of the ship is required, or that an energy-consuming item such as a cargo pump or the like is activated or stopped. Can happen. During this time interval, the speed of the energy generator and the power it supplies are disturbed, so the transition causes an undesired shutdown of the energy generator due to a shortage of fuel gas pressure, or with regard to the minimum or maximum allowable pressure It is possible that the compression constraints cannot be met and the compression device is damaged.

  In prior art devices, for example as described in published French patent application 2,837,783 or indeed in French patent application 04/50945, the evaporator is submerged in the bottom of the tank. Supplied by a pump. The flow rate of the evaporator is controlled based on the pressure in the tank and / or the pressure in the feed manifold by a valve arranged upstream. These devices suffer from problems with the evaporator response time following the changes in pressure in the feed manifold. Response time is the result of, inter alia, the time required to change in synchrony to fill the evaporator. This unavoidable inertia has a significant effect on changing the pressure in the feed manifold in the event of a change in the load of the energy generating unit and is therefore of importance to the risks mentioned above.

To date, this issue has never been highlighted and has not become the subject of any conventional research.
French Patent Application No. 2,837,783 French patent application No. 04/50945

  Accordingly, an object of the present invention is to reduce the inertia of forced evaporation.

  For this purpose, the present invention provides an apparatus for supplying gaseous fuel from the contents of at least one cargo tank of the ship to the energy generation unit of a liquefied gas transport ship. The apparatus includes at least one compressor having an inlet for intake of gas phase gas from the tank, and an outlet from the compressor delivers to a feed manifold of the energy generation unit, the apparatus comprising: The pump further includes a pump submerged in the bottom of the tank and connected to the inlet of the evaporator, and the outlet from the evaporator is connected to the feed manifold of the energy generating unit via a feed pipe. The apparatus is configured such that the pump supplies liquefied gas to the evaporator at a pressure higher than the supply pressure of the unit, and the feed pipe adjusts the flow rate of the gas supplied to the feed manifold. It is characterized in that the regulator means can be attached.

  When the load on the energy generating unit changes and the supply pressure tends to fluctuate temporarily, the flow regulator means gradually releases the gas at the supply pressure in the manifold, thereby adjusting its pressure And work to stabilize.

  In this way, the supply conditions to the energy generation unit are optimized even during the transition phase of the load change.

  Advantageously, a flow control means for adjusting the flow rate of the gas supplied to the feed manifold is connected to the means for measuring the pressure in the manifold.

  In an advantageous embodiment, a buffer tank is arranged upstream from the flow regulator means. In this way, it is possible to store the gas permanently at a pressure higher than the supply pressure of the energy generating unit for the purpose of mitigating any fluctuations in the pressure in the manifold. This technique of using a buffer tank increases the gas storage capacity at high pressure if the pipe capacity does not provide sufficient safety capacity by itself when given its length and / or its diameter. Is possible.

  In another advantageous embodiment, a cooling device is arranged at the outlet of the evaporator and means for adjusting the gas pressure at the outlet from the evaporator are arranged upstream from the evaporator. Thus, the cooling device can reduce the temperature of the gas to the evaporator outlet, and the pressure regulator means can keep the pressure at the evaporator outlet lower than the outlet pressure from the pump Thereby ensuring that the cooling device operates while maintaining a gas pressure upstream from the flow regulator means and higher than the pressure in the feed manifold.

  Advantageously, the pressure regulator means is connected to means for measuring pressure downstream from the cooling device.

  The cooling device may also include a device that evaporates the liquefied gas coming from at least one storage tank and is activated by the temperature measured in the outlet pipe from the cooling device.

  In an advantageous embodiment, means for adjusting the flow rate of the gas supplied to the feed manifold are also connected to means for measuring the gas flow rate, which gas is produced by the compressor and the evaporator, and It is consumed by the energy generating unit and by a gas incinerator, sometimes referred to as an “incinerator”. This embodiment calculates the difference between the gas flow generated and the gas flow consumed and adjusts the pressure at the outlet from the evaporator, thus increasing the stability and reactivity of the device. It becomes possible.

  The invention will be described in greater detail below with reference to the accompanying drawings. The drawings illustrate embodiments of the invention as non-limiting examples.

  With reference to FIGS. 1 and 2, elements dedicated to the generation of energy in a methane tanker are shown schematically, and in this example, a unit 1 for generating electrical and / or thermal energy is included. Unit 1 can include a diesel engine that drives an alternator that generates electrical energy for onboard electrical equipment and to propel the ship, or Unit 1 can be a steam turbine to drive a propeller. A conventional unit may be included in the form of a steam generating boiler that feeds into the unit.

  As is usually done with methane tankers, the energy generation unit 1 is fed with gas taken from one or more cargo tanks 2 of the tanker. The supply gas is usually methane taken directly from the tank and is raised to a supply pressure of several bar (several hundred kPa).

  This feed gas is taken in parallel in two different ways. First, gas phase gas 4 is collected directly from the surface of liquid methane 5 in tank 2 and compressed by compressor 6 driven by an electric motor (not shown). This gas is then injected into the feed manifold 7 at the pressure desired to be supplied to the energy generating unit 1. Second, an electric pump 8 sunk in the bottom of the tank 2 collects the liquid methane 3 and sends it to the evaporator 9. At the outlet from the evaporator 9, the methane is likewise in a gaseous state so that it is supplied via the feed pipe 10 to the feed manifold 7 of the energy generation unit 1.

  An overpressure exhaust pipe is connected to the feed manifold 7 downstream from the connection between the pipe 10 and the feed manifold, leading to a device 11 for oxidizing the gas. Such an overpressure may occur, for example, after the load on unit 1 suddenly drops and its gas consumption suddenly decreases.

  In the embodiment shown in FIG. 1, a gas flow regulator valve 12 is arranged at the outlet from the pipe 10 upstream from the feed manifold 7 of the unit 1 so as to reduce fluctuations in the supply pressure in the feed manifold 7. Is done. The valve 12 can be particularly servo-controlled by a pressure regulator 13 connected to the feed manifold, and more generally is controlled by an automatic regulator.

  The pump 8 supplies the liquefied gas to the evaporator 9 at a pressure higher than the supply pressure of the energy generation unit 1. As a result, the gas in the gas phase is delivered at the outlet from the evaporator 9 at a pressure higher than the supply pressure established in the feed manifold 7, thereby establishing the stored gas in the pipe 10 at a high pressure. Can be used to feed the feed manifold via regulator valve 12 when unit 1 requires. When the load of the unit 1 fluctuates, the valve 12 that connects the pipe 10 to the feed manifold 7 changes its opening size so that part of the stored gas in the pipe 10 is at the required supply pressure in the manifold. Release to manifold. Thus, for the purpose of maintaining the supply pressure at the supply pressure reference value, for example, it is possible to compensate for a decrease in the supply pressure of the manifold due to an increase in the load of the unit 1.

  In the embodiment shown in FIG. 2, the buffer tank 14 disposed in the pipe 10 upstream from the regulator valve 12 is expanded by the pressure at the outlet from the evaporator 9, and the pressure is higher than the supply pressure of the unit 1. . This allows the capacity available in the pipe 10 between the outlet from the evaporator 9 and the inlet to the valve 12 to be sufficient for this function for a given pipe length and / or its diameter. Whenever it is not, it is guaranteed that there is sufficient safe gas capacity at a pressure higher than the supply pressure. Therefore, by using this gas volume at the higher pressure associated with the regulator valve 12, the pressure in the feed manifold 7 can damage the compressor and lead to an unnecessary shutdown of the energy generation unit 1. Reactivity is obtained that is fast enough to avoid any significant drop or rise.

  FIG. 2 shows a cooling device 15 including a device for injecting liquefied gas coming from at least one cargo tank 2. This cooling device cools the gas at the outlet from the evaporator 9 to a temperature and pressure within a certain range, so that the valve 12 reacts sufficiently to reduce the supply pressure in the manifold. It becomes possible to ensure that the reference value is maintained. For this purpose, the cooling device 15 is activated by measuring the temperature at the outlet from the evaporator 9, the measuring means being conventional and not shown in the figure. In order to allow proper operation of the cooling device 15, another regulator valve 16 is arranged at the inlet to the evaporator 9 and the pressure at the outlet from the evaporator 9 is measured by means 17. The pressure is adjusted based on the pressure value. This ensures that this pressure is lower than the pressure at the outlet from the pump 8 that feeds the cooling device 15, thereby making it possible to ensure the suction of liquid. This valve 16 also serves to adjust the pressure to a value higher than the supply pressure in the feed manifold 7, thereby allowing the valve 12 to perform its function.

  In the last variant of the invention (not shown in the drawings), the valve 16 comprises means for measuring the flow rate of gas consumed by the energy generating unit 1 and the gas oxidizer 11, the compressor 6 and the evaporator 9. Can also be adjusted by determining the difference between the respective product gas flow rate and the consumption gas flow rate by means for measuring the flow rate produced by and controlling the valve 16 accordingly. This variant makes it possible to achieve further pressure stability at the outlet from the evaporator 9 due to better reactivity.

It is a figure of the 1st Embodiment of this invention. It is a figure of the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Energy generation unit 2 Cargo tank 3, 5 Liquid methane 4 Gas 6 Compressor 7 Feed manifold 8 Pump 9 Evaporator 10 Feed pipe 11 Oxidizer 12 Flow regulator valve 13 Pressure regulator 14 Buffer tank 15 Cooling device 16 Other adjustment Valve 17 Means

Claims (6)

An apparatus for supplying gaseous fuel from the contents of at least one cargo tank (2) of the liquefied gas transport ship to the energy generation unit (1) of the liquefied gas transport ship;
The apparatus comprises at least one compressor (6) having an inlet for sucking gas-phase gas from the cargo tank (2);
The outlet from the compressor (6) delivers to the feed manifold (7) of the energy generation unit (1),
The apparatus further comprises a pump (8) submerged in the bottom of the tank (2) and connected to the inlet of the evaporator (9);
An outlet from the evaporator (9) is connected to the feed manifold (7) of the energy generation unit (1) via a feed pipe (10) ;
The apparatus, wherein the pump (8) is configured to supply liquefied gas to the evaporator (9) at a pressure higher than the supply pressure of the energy generating unit (1) ,
The feed pipe (10) is fitted with flow regulator means (12) for regulating the flow rate of the gas supplied to the feed manifold (7), the flow regulator means (12) being connected to the feed manifold. (7) is connected to means (13) for measuring the pressure in the apparatus according to claim Rukoto. Device according to claim 1, characterized in that a buffer tank (14) is arranged upstream from the flow regulator means (12). A cooling device (15) is arranged in the feed pipe (10) at the outlet from the evaporator (9),
Pressure regulator means for regulating the gas pressure at the outlet from the evaporator (9) (16), characterized in that disposed upstream from the evaporator (9), in claim 1 or 2 The device described. It said pressure regulator means (16), characterized in that it is connected from the cooling device (15) to means (17) for measuring the pressure of the feed pipe (10) downstream, claim 3 The device described in 1. The cooling device (15) comprises an evaporation device for evaporating the liquefied gas coming from at least one cargo tank (2);
5. A device according to claim 3 or 4 , characterized in that the evaporator is activated by a temperature measured in the feed pipe (10) at the outlet from the cooling device (15). The pressure regulator means (16) measures the flow rate of gas produced by the compressor (6) and the evaporator (9) and is consumed by the energy generating unit (1) and the oxidizer (11). 6. A device according to claim 4 or 5 , characterized in that it is connected to means for measuring.

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