METHOD AND ARRANGEMENT FOR HANDLING VENT GAS MIXTURE

Abstract

A method for handling a vent gas mixture originating from a fuel system and comprising fuel vapours and inert gas. The method involves: directing the vent gas mixture from the fuel system to a condenser, the condenser condensing at least a majority of the fuel vapours into liquid fuel such that the vent gas mixture comprises liquid fuel and inert gas, separating the liquid fuel and the inert gas of the vent gas mixture from the condenser in a vapour-liquid separator, and selectively directing the liquid fuel from the separator to a boiler system, when the boiler system is in a hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture, or storing the liquid fuel in the separator and/or in a separate storage tank until the boiler system is in the hot condition and is ready to receive/combust the liquid fuel.

Claims

1. A method for handling a vent gas mixture comprising fuel vapours of a fuel and inert gas, the vent gas mixture originating from a fuel system, the method comprising: directing the vent gas mixture from the fuel system to a condenser, the condenser condensing at least a majority of the fuel vapours into liquid fuel such that the vent gas mixture comprises liquid fuel and inert gas, separating the liquid fuel and the inert gas of the vent gas mixture from the condenser in a vapour-liquid separator, and selectively directing the liquid fuel from the vapour-liquid separator to a boiler system, when the boiler system is in a hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture, or storing the liquid fuel in the vapour-liquid separator and/or in a separate storage tank until the boiler system is in the hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture.

2. The method according to claim 1, wherein the fuel is an alcohol.

3. The method according to claim 1, further comprising directing the inert gas of the vent gas mixture from the vapour-liquid separator to atmosphere.

4. The method according to claim 1, wherein the vent gas mixture originates from a fuel tank of the fuel system.

5. The method according to claim 1, wherein the vent gas mixture is directed from the fuel system to the condenser in response to an action of emptying a fuel tank, which action includes venting fuel vapours from the tank with said inert gas.

6. The method according to claim 1, wherein the vent gas mixture is directed from the fuel system to the condenser in response to a pressure build-up in response to an action of filling fuel to a fuel tank.

7. The method according to claim 1, wherein the vent gas mixture is directed from the fuel system to the condenser in response to a leakage in the fuel system.

8. The method according to claim 1, further comprising igniting a self-sustained flame of the liquid fuel of the vent gas mixture.

9. The method according to claim 1, further comprising igniting a support flame and combusting the liquid fuel of the vent gas mixture using the support flame, or combusting the liquid fuel of the vent gas mixture using a primary flame of the boiler system as a support flame.

10. The method according to claim 1, further comprising bypassing the condenser and the vapour-liquid separator by directing the vent gas mixture from the fuel system to the boiler system, when the boiler system is in the hot condition and is ready to receive and combust the vent gas mixture.

11. The method according to claim 10, wherein bypassing the condenser and the vapour-liquid separator includes directing the vent gas mixture from the fuel system via a heat exchanger and a gas valve train to the boiler system, wherein the heat exchanger at least partly evaporates any liquid phase of the vent gas mixture.

12. The method according to claim 1, wherein the inert gas is nitrogen.

13. An arrangement for handling a vent gas mixture comprising fuel vapours of a fuel and inert gas, the vent gas mixture originating from a fuel system, the arrangement comprising: a boiler system, and a vent gas handling system, wherein the boiler system comprises a burner, and a fuel inlet configured to selectively supply a fuel and thereby selectively sustain a primary flame in the burner for production of heat and/or steam in the boiler system, wherein the vent gas handling system comprises a condenser for condensing the fuel vapours in gas phase into liquid fuel, and a vapour-liquid separator for separating the liquid fuel and the inert gas, wherein the arrangement further comprises piping configured to direct the vent gas mixture from the fuel system to the condenser condensing the fuel vapours into liquid fuel such that the vent gas mixture comprises liquid fuel and inert gas, direct the vent gas mixture from the condenser to the vapour-liquid separator separating the liquid fuel and the inert gas, and selectively direct the liquid fuel from the vapour-liquid separator to the boiler system, when the boiler system is in a hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture, or store the liquid fuel in the vapour-liquid separator and/or in a separate storage tank until the boiler system is in the hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture.

14. The arrangement according to claim 13, wherein the fuel inlet is connected via a fuel supply line to a fuel source, the fuel source being configured to supply a fuel for a primary flame, the fuel being selected from the group consisting of liquefied natural gas, distillate and residual fuels.

15. The arrangement according to claim 13, wherein the boiler system is configured to ignite a self-sustained flame of the liquid fuel of the vent gas mixture.

16. The arrangement according to claim 13, wherein the boiler system is configured to ignite a support flame and to combust the liquid fuel of the vent gas mixture using said support flame, or to combust the liquid fuel of the vent gas mixture using a primary flame as a support flame.

17. The arrangement according to claim 13, wherein the burner is a multi-fuel burner system configured to burn at least two different fuels, or to burn one or more liquids fuels in combination with burning one or more gaseous fuels, wherein the one or more liquid fuels is burnt simultaneously as the one or more gaseous fuels is burnt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The invention will by way of example be described in more detail with reference to the appended schematic drawings, which shows a presently preferred embodiment of the invention.

[0063] FIG. 1 schematically discloses an arrangement for handling a vent gas mixture, which comprises fuel vapours of a fuel and inert gas.

[0064] FIG. 2 schematically discloses a method for handling a vent gas mixture, which comprises fuel vapours of a fuel and inert gas.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0065] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the disclosure to the skilled person.

[0066] With reference to FIG. 1, there is disclosed an arrangement 100 for handling a vent gas mixture comprising fuel vapours of a fuel and inert gas. The fuel may be an alcohol or an alcohol-based fuel. Preferably, the fuel is methanol. The fuel may be used as a fuel in an engine propelling a ship. Alternatively, the fuel may be a fuel stored as cargo and transported by a ship. It should however be noted that other fuels may be used as well. The inert gas may be nitrogen. It should be noted that the inert gas may be any other inert gas or mixtures of inert gases as well.

[0067] The arrangement 100 comprises a boiler system 110, a fuel system and a vent gas handling system 130. The vent gas mixture originates from the fuel system 120.

[0068] The boiler system 110 comprises a boiler 111, a burner 113 and a fuel inlet 114. The fuel inlet 114 may be configured to selectively sustain a primary flame in the burner 113 for production of heat and/or steam in the boiler system 110. The fuel inlet 114 is connected via a fuel supply line 116 to a fuel source 151. The fuel source 151 may be configured to supply a fuel for the primary flame in the burner 113. The fuel for the primary flame may liquified natural gas (LNG), distillate or residual fuels. However, it should be noted that the fuel may be other fuels as well. The fuel may comprise one or more type of fuels. The fuel source 151 may be configured to supply fuel to the boiler system 110 via a further fuel supply line 154 and a pump 153. The boiler system 110 comprises a further fuel inlet 112. The further fuel inlet 112 is connected via piping 118 to the vent gas handling system 130.

[0069] The burner 113 of the boiler system 110 may be a multi-fuel burner system configured to burn at least two different fuels. The burner 113 may be configured to burn one of the at least two different fuels at the time. The burner 113 may be configured to burn one or more liquid fuels in combination with burning one or more gaseous fuels. The one or more liquid fuels may be burnt simultaneously as the one or more gaseous fuels is burnt. Preferably, one liquid fuel of the one or more liquid fuels is burnt simultaneously as one gaseous fuel of the one or more gaseous fuels.

[0070] The fuel system 120 comprises a fuel tank 121. As depicted in FIG. 1, the fuel system 120 further comprises a cofferdam construction 123. The cofferdam construction may act as a secondary barrier and extending fully or partly around a fuel tank 121. The cofferdam 123 may have the purpose to enclose a potential leak in the fuel tank 121. The fuel tank 121 and/or the cofferdam 123 is connected via a supply line 122 to an engine 125 of the fuel system 120. Although not illustrated, the fuel system 121 may comprise more than one fuel tank 121.

[0071] The vent gas handling system 130 comprises a condenser 131 for condensing the fuel vapours in gas phase into liquid phase. The vent gas handling system 130 also comprises a vapour-liquid separator 133 for separating the liquid fuel and the inert gas.

[0072] The vent gas handling system 130 is connected to the fuel system via a piping 139 and is connected to the boiler system 110 via a piping 118. The piping 139 is configured to direct the vent gas mixture from the fuel system 120 to the vent gas handling system 130. More in detail, the piping 139 is configured to direct the vent gas mixture from the fuel system 120 to the condenser 131 of the vent gas handling system 130. The condenser 131 is configured to condense at least the majority of the fuel vapours into liquid fuel such that the vent gas mixture comprises liquid fuel and inert gas. The condenser 131 is connected to the vapour-liquid separator 133 via a piping 132. Thus, the piping 132 is configured to direct the vent gas mixture from the condenser 131 to the vapour-liquid separator 133. The vapour-liquid separator 133 is configured to separate the liquid fuel and the inert gas. The vapour-liquid separator 133 is connected to a storage tank 135 via a piping 134 and connected a pump 137 via a piping 138. The storage tank 135 is connected to the one or more fuel pumps 137 via a piping 136.

[0073] The vapour-liquid separator 133 may be configured to selectively direct the liquid fuel to the boiler system 110 via the pump 137 and the piping 118. This is especially relevant when the boiler system 110 is in a hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture.

[0074] If the boiler system 110 is not in the hot condition, the vapour-liquid separator 133 may be configured to store the liquid fuel until the boiler system 110 is in the hot condition. Alternatively, or in combination, the vapour-liquid separator 133 may be configured to supply the liquid fuel to and store the same in the separate storage tank 135 until the boiler system 110 is in the hot condition. As said, when the boiler system 110 is in the hot condition, it is ready to receive and combust the liquid fuel of the vent gas mixture.

[0075] Although not illustrated, when the liquid fuel and inert gas have been separated, the vapour-liquid separator 133 may be configured to direct the inert gas of the vent gas mixture to atmosphere.

[0076] The vent gas mixture may be directed from the fuel system 120 to the condenser 131 in response to an action of emptying the fuel tank 121 in the fuel system 120. The action preferably includes venting fuel vapours from the fuel tank 121 with the inert gas. Alternatively, the vent gas mixture may be directed from the fuel system 120 to the condenser 131 in response to a pressure build-up in response to an action of filling fuel to the fuel tank 121. Alternatively, the vent gas mixture may be directed from the fuel system 120 to the condenser 131 in response to a leakage in the fuel system 120.

[0077] Referring back to the boiler system 110 which may be further configured to ignite a self-sustained flame of the liquid fuel of the vent gas mixture. Thus, the boiler system 110 may be configured to ignite the support flame and to combust the liquid fuel of the vent gas mixture using the support flame or may be configured to combust the liquid fuel of the vent gas mixture using the primary flame as the support flame.

[0078] As further depicted in FIG. 1, the fuel system 120 may be connected via a piping 142 to a heat exchanger 141. The heat exchanger 141 is configured to fully evaporate any liquid phase of the vent gas mixture. The evaporator 141 is connected via a piping 144 to a gas-vale train 143. The gas-valve train 143 is connected via piping 146 to the boiler system 110. Thus, the arrangement 100 may be configured to direct the vent gas mixture from the fuel system 120 to the boiler system 120 by bypassing the vent gas handling system 130. The vent gas handling system 130 is bypassed by preferably selectively directing the vent gas mixture from the fuel system 120 to the boiler system 130. This may be possible when the boiler system 110 is in the hot condition and is ready to receive and combust the vent gas mixture.

[0079] Although the heat exchanger 141 and the gas-valve train 143 are depicted in FIG. 1, they may be omitted from the arrangement 100 such that the fuel system 120 is connected via a piping to the boiler system 110. In this case, the vent gas mixture is introduced directly to the boiler system 110, preferably via a pump, from the fuel system 120.

[0080] With reference to FIG. 2, a flow chart 200 illustrating a method for handling vent gas mixture comprising fuel vapours or a fuel and inert gas is shown by way of example.

[0081] Generally, a first step S202 of the method 600 may be to directing the vent gas mixture from the fuel system 120 to the condenser 131 being configured to condensing at least a majority of the fuel vapours into liquid fuel. Thereby, the vent gas mixture comprises liquid fuel and inert gas. In a second step S204, the liquid fuel and the inert gas of the vent gas mixture may be separated in the vapour-liquid separator 133.

[0082] Thereafter, the method 200 may provide a third step S206 or a fourth step S208 depending on if the boiler system 110 is in a hot condition or not. In the third step S206, when the boiler system 110 is in the hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture, the liquid fuel is selectively directed from the vapour-liquid separator 133 to the boiler system 110. Otherwise, the liquid fuel is stored in the vapour-liquid separator 133 and/or in the separate storage tank 135 of the vent gas handling system 130 until the boiler system 110 is in the hot condition and is ready to receive and combust the liquid fuel of the vent gas mixture.

[0083] The person skilled in the art realizes that the present disclosure by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.