Method for determining the quantity of at least one chemical compound

Abstract

The invention relates to a method for determining the value of a quantity relating to a quantity of at least one chemical compound emitted by a heat engine, comprising: - determining (100) an initial value of a quantity relating to a quantity of hydrocarbons introduced into the heat engine (1) and deducing therefrom an initial value of a quantity relating to a quantity of carbon atoms introduced into the engine, - determining (400) the concentrations of a plurality of carbon-based chemical compounds expected in the exhaust gases, - deducing (500), from said initial value of the quantity relating to the quantity of hydrocarbons introduced into the heat engine determined previously and from the concentrations of said plurality of carbon-based chemical compounds, a final value of a quantity relating to a quantity of carbon dioxide released in the exhaust gases and deducing therefrom said value of said quantity relating to the quantity of the compound.It also relates to an associated system. Figure for the abbreviation: 1.

Description

Title of the invention: Method for determining the quantity of at least one chemical compound technical field

[0001] The invention relates to the field of methods for determining the quantity of a chemical compound emitted by a heat engine.

[0002] It finds a particularly advantageous application in determining the quantity of a chemical compound emitted by a ship's internal combustion engine. Technological background

[0003] In recent years, various reasons have motivated the need to measure emissions of gases and other components produced by ship propulsion in order to control and restrict them.

[0004] The general objective is to reduce the exposure of marine and coastal ecosystems, marine and port operators, passengers and coastal populations to polluting emissions from ship engines into the atmosphere.

[0005] One of the tools of this strategy is to assign a rating to each ship based on the calculation of a carbon dioxide CO2 emission intensity index (Cil) (see resolution MEPC.352(78)). The calculation of this index is itself based on the assessment of the quantity, by mass, of greenhouse gases (GHGs) emitted by the ship.

[0006] The counting requirements for the calculation of the Cil currently only concern carbon dioxide CO2 but will be extended to other GHGs, for example CH4 and N2O.

[0007] In the prior art, it is known to perform a direct measurement of such a quantity, for example for carbon dioxide (CO2): the mass of CO2 emitted is obtained by multiplying the total mass flow rate of the exhaust gases by the concentration of CO2 in these exhaust gases. It is also known to perform a calculation whereby the mass of CO2 emitted is obtained by multiplying the mass flow rate of the fuel by a predetermined factor depending on the fuel used.

[0008] The prior art method based on direct measurement has low accuracy and reliability because the volumetric or mass flow rates of exhaust gases are difficult to measure. There is no reliable mass flow meter solution for gases circulating at atmospheric pressure, high temperature, and with very low pressure drop. Volumetric flow meters for this type of application exist (ultrasonic, Pitot tube, vortex, etc.) but represent a high cost in terms of supply, installation, and maintenance. Furthermore, a flow measurement Volumetric would require conversion to mass flow rate, which would decrease the accuracy of the result.

[0009] The calculation-based method gives satisfactory results for counting carbon dioxide, which is predictive: when a hydrocarbon molecule burns, it almost always produces CO2. The method makes it possible to provide a rapid assessment of CO2 mass flow rates and therefore of cumulative masses over time, simply from a measurement of the mass flow rate of the fuel concerned, or even from a variation in the fuel used over time, while eliminating the need for (i) a concentration measurement, (ii) a measurement of emission flow rate.

[0010] On the other hand, other carbonaceous chemical compounds emitted by the engine, such as methane (CH4), are gases resulting from the naturally imperfect operation of an engine. Their quantities therefore cannot be calculated deterministically. The method does not allow for the evaluation of unburned fractions and therefore does not allow for the evaluation of engine CH4 emissions, nor N2O emissions.

[0011] In addition, the predetermined factor used in the calculation-based method is determined according to the family of fuel used and is not precisely adapted to the fuel used, which leads to inaccuracy.

[0012] Future maritime transport regulations plan to use empirical formulas developed from engine tests on test benches at deliberately restrictive operating speeds. It is highly likely that these formulas will provide overestimated results and therefore be unfavorable to ship owners. Summary of the invention

[0013] One idea underlying the invention is to provide accurate and reliable results for determining the quantity of a carbonaceous chemical compound emitted in the exhaust gases of a heat engine.

[0014] According to one embodiment, the invention provides a method for determining the value of a quantity relating to a quantity of at least one chemical compound, said chemical compound being emitted by a heat engine fueled at least partially by hydrocarbons, comprising the following steps: - determine an initial value of a quantity relating to a quantity of hydrocarbons introduced into the heat engine and deduce from this an initial value of a quantity relating to a quantity of carbon atoms introduced into the engine, - determine the concentrations of a plurality of expected carbon-based chemical compounds in exhaust gases, - deduce, from the said initial value, the quantity relating to the amount of hydrocarbons introduced into the heat engine determined previously, and the concentrations of the said plurality of expected carbonaceous chemical compounds measured in the gases of exhaust, a final value of a quantity relating to a quantity of carbon dioxide released in the exhaust gases and deduce said value of said quantity relating to the quantity of the chemical compound emitted in the exhaust gases.

[0015] Thanks to these characteristics, it is possible to determine the quantity of the chemical compound emitted accurately and reliably. No exhaust gas flow measurement is necessary.

[0016] According to one embodiment, - the quantity relating to the amount of at least one chemical compound is a mass flow rate of the chemical compound or a mass, - the quantity relating to the amount of hydrocarbons introduced into the heat engine is a mass flow rate or a mass, - the quantity relating to the amount of carbon atoms introduced into the engine is a molar flow rate or a number of moles, - the quantity relating to the amount of carbon dioxide released in the exhaust gases is a molar flow rate or a number of moles.

[0017] According to one embodiment: - The quantity relating to the amount of at least one chemical compound is a mass, - The quantity relating to the amount of hydrocarbons introduced into the heat engine is a mass flow rate - the quantity relating to the amount of carbon atoms introduced into the engine is a molar flow rate, - the quantity relating to the amount of carbon dioxide released in the exhaust gases is a molar flow rate, We determine a value for a mass flow rate of the chemical compound and we deduce from this the said value of the mass of the chemical compound emitted in the exhaust gases over a time period by integrating the mass flow rate determined over this time period.

[0018] According to one embodiment, for a given composition of hydrocarbons supplying the heat engine, a value of a quantity characteristic of the hydrocarbon composition is determined depending on a reference ratio between a number of carbon atoms and a number of hydrogen atoms characteristic of this hydrocarbon composition, and this value of the characteristic quantity is taken into account to determine the initial value of the quantity relating to the quantity of carbon atoms introduced into the heat engine.

[0019] According to one embodiment, the engine is powered by two fuels of different compositions, each having a reference ratio, and said characteristic quantity depends on the reference ratios of the two fuels.

[0020] According to another embodiment, said characteristic quantity is equal to the inverse of the sum of the molar mass of carbon and the ratio between the molar mass of hydrogen and the reference ratio.

[0021] According to one embodiment, said characteristic quantity is equal to a conversion factor between the consumption of hydrocarbons of the heat engine and the emission of carbon dioxide by this heat engine.

[0022] According to one embodiment, said characteristic quantity is equal to the reference ratio.

[0023] According to one embodiment, the final value of the quantity relating to the amount of carbon dioxide released in the exhaust gases is deduced from the initial value of the quantity relating to the amount of carbon atoms introduced into the heat engine and from each ratio between the concentration of each expected carbon chemical compound in the exhaust gases and the concentration of carbon dioxide in these exhaust gases.

[0024] According to one embodiment, the expected carbonaceous chemical compounds comprise at least carbon dioxide and carbon monoxide and the chemical compound is chosen from one of the following chemical compounds: carbon dioxide, methane, carbon monoxide, nitrous oxide, nitrogen oxides, sulfur oxides.

[0025] According to one embodiment, the concentrations of at least some of the expected carbonaceous chemical compounds in the exhaust gases are measured using a gas analysis device by gas spectrometry.

[0026] According to one embodiment, at least one exhaust gas sample is taken from said heat engine, this sample is cooled and / or the water vapor is removed from this sample before it passes through the gas analysis device.

[0027] According to one embodiment, the value of the quantity relating to the amount of the chemical compound emitted in the exhaust gases is deduced from the final value of the quantity relating to the amount of carbon dioxide released in the exhaust gases and from the ratios between the concentration of each expected carbonaceous chemical compound in the exhaust gases and the concentration of carbon dioxide in these exhaust gases.

[0028] According to one embodiment, the invention also provides a system for determining the value of a quantity relating to a quantity of at least one chemical compound, said chemical compound being emitted by a heat engine fueled at least partially by hydrocarbons, comprising a computer unit including one or more processors programmed to implement the following steps: - determine an initial value of a quantity relating to a quantity of hydrocarbons introduced into the heat engine and deduce from this an initial value of a quantity relating to a quantity of carbon atoms introduced into the engine, - determine the concentrations of a plurality of expected carbon-based chemical compounds in exhaust gases, including carbon dioxide, - calculate, based on the aforementioned initial value of the quantity relating to the amount of hydrocarbons introduced into the internal combustion engine determined previously and the concentrations of said plurality of carbonaceous chemical compounds in the exhaust gases, a final value of a quantity relating to the amount of carbon dioxide released in the exhaust gases and deduce therefrom the said value of said quantity relating to the amount of the chemical compound emitted in the exhaust gases.

[0029] According to one embodiment, this determination system further comprises a gas analysis device using gas spectrometry.

[0030] According to one embodiment, the system further comprises a fuel analysis device.

[0031] According to one embodiment, the invention further relates to a ship equipped with a system as described above. Brief description of the figures

[0032] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0033] Fig. 1 schematically represents the steps of a method for determining a quantity of at least one chemical compound, said chemical compound being emitted by a heat engine fueled at least partially by hydrocarbons,

[0034] Fig. 2 schematically represents a system for determining such a quantity, adapted to implement the method of Fig. 1. Description of the implementation methods

[0035] The steps of a method for determining the value of a quantity relating to a quantity of at least one chemical compound emitted by a heat engine fueled at least partially with hydrocarbons have been schematically represented in [Fig.1].

[0036] Fig. 2 schematically represents a system 20 implementing this method in a transport vehicle equipped with three thermal engines 1.

[0037] Each internal combustion engine 1 conventionally receives air and fuel as its inlet 2. Fuel 2 includes, for example, a primary fuel and a secondary fuel called a "pilot fuel," used to initiate combustion. The fuel The main and / or pilot fuel contains hydrocarbons. Exhaust gases 3 are released from engine 1.

[0038] In particular, the fuel may comprise: either only a main fuel of the liquid hydrocarbon type, or a main fuel other than hydrocarbons for example methanol, ethanol or ammonia and a pilot fuel of the liquid hydrocarbon type, or only a main fuel of the gaseous hydrocarbon type.

[0039] The transport vehicle is for example a ship, in particular a methane tanker or a ship using Liquefied Natural Gas as fuel.

[0040] The system 20 for determining a value of a quantity relating to a quantity of at least one chemical compound emitted by a heat engine fueled at least partially by hydrocarbons includes in particular a computer unit 11 comprising one or more processors programmed to implement the method described below and one or more memories.

[0041] Thanks to the method described below, it is possible to evaluate the quantity emitted of a chemical compound, based on the following data: - a measured value of the overall fuel flow rate, - a measured value of the concentrations of the expected carbonaceous chemical compounds in the exhaust gases and of the chemical compound emitted in the exhaust gases.

[0042] The chemical compound whose quantity is determined by the method according to the invention comprises, for example, one of the following carbonaceous chemical compounds: carbon dioxide CO2, methane CH4, carbon monoxide CO.

[0043] In the following description, particular consideration is given to the case where the quantity of carbon dioxide, carbon monoxide and methane emitted by the heat engine is determined.

[0044] It may also include another non-carbon chemical compound such as nitrous oxide N2O or nitrogen oxides NOx or sulfur oxides SOx.

[0045] In this case, the concentration of this non-carbon chemical compound in the exhaust gases is further determined, as will be described in detail below.

[0046] The proposed method consists of considering that all the carbon atoms C entering the heat engine are supplied by the fuel, and that these C atoms are either transformed (by oxidation) into CO2 and CO, or are unburned, giving for example CH4, and evacuated in the exhaust gases.

[0047] In what follows, the quantity of carbon atoms supplied by the air introduced into the heat engine is considered negligible compared to the quantity of carbon atoms contained in the fuel. Indeed, the air admitted into the engine as oxidant contains only -0.042% by volume of CO2, which will not react during combustion.

[0048] It is thus considered that all the carbon atoms introduced into the engine and then transformed into CO2 / CO or released as unburned come from the fuel alone.

[0049] Carbon-based fuels, known and used in industry and particularly in the maritime sector, consist almost exclusively of hydrocarbons containing chemical compounds such as alkanes (CnH2n+2), alkenes (CnH2n), and all types of cyclic and acyclic unsaturated hydrocarbon compounds, all of which are chains made up exclusively of hydrogen and carbon atoms. These compounds contribute a number of carbon atoms (nc) and a number of hydrogen atoms (nH) to the internal combustion engine. The case of methanol and ethanol, which also contain carbon atoms, will be further described below.

[0050] In the case of liquid fuels (Fuel Oil ISO8217), the non-carbonaceous chemical compounds of the fuel are: - sulfur compounds, which can reach up to -5% by mass for residual fuels such as Heavy Fuel Oil (HFO), - heavy metals, - dissolved gases, - various particles and solid residues.

[0051] For the last three types, the fractions are negligible. The method can nevertheless take into account the mass fraction of sulfur contained in the fuel in question.

[0052] In the case of gaseous fuels of the type liquefied natural gas or liquefied petroleum gas (LNG, LPG), the non-carbon chemical compounds of the fuel are: - nitrogen compounds dissolved up to -1.5% by mass maximum, - other gases dissolved in negligible quantity.

[0053] The method according to the invention comprises the following steps: - We determine 100 an initial value of a quantity relating to the amount of hydrocarbons introduced into the heat engine 1 and from this we deduce an initial value of a quantity relating to the amount of carbon atoms introduced into the engine, - we determine 400 the concentrations of the expected carbonaceous chemical compounds in the exhaust gases 3, - 500 is deduced from the said initial value of the quantity relating to the amount of hydrocarbons introduced into the heat engine 1 determined previously and from the concentrations of the expected carbonaceous chemical compounds in the exhaust gases 3, a final value of a quantity relating to a quantity of dioxide of carbon released in the exhaust gases 3 and from this we deduce 600 said value of said quantity relating to the quantity of the chemical compound emitted in the exhaust gases 3 sought.

[0054] Here, "a quantity relative to a quantity" means a quantity that represents that quantity. A quantity relative to a quantity can generally be one of the following: a mass flow rate, a mass, a volumetric flow rate, a volume, a molar flow rate, a number of moles.

[0055] In particular, here, - the quantity relating to the amount of at least one chemical compound is a mass quantity, for example a mass flow rate or a mass, - the quantity relating to the amount of hydrocarbons introduced into the heat engine is a mass quantity, for example a mass flow rate or a mass v, - the quantity relating to the amount of carbon atoms introduced into the engine is a molar quantity, for example a molar flow rate or a number of moles, - the quantity relating to the amount of carbon dioxide released in the exhaust gases 3 is a molar quantity, for example a molar flow rate or a number of moles.

[0056] The mass of a chemical compound introduced into the engine or emitted by the engine during a fixed period can be obtained from the mass flow rate by integrating it over that period. It can be obtained from the volumetric flow rate by integrating it over the said period and multiplying the result by the density of the chemical compound. It can be obtained from the volume by multiplying it by the density of the chemical compound. It can be obtained from the molar flow rate by integrating it over the said period and multiplying the result by the molar mass of the chemical compound. It can be obtained from the number of moles by multiplying it by the molar mass of the chemical compound.

[0057] The number of moles of a chemical compound introduced into the engine or emitted by the engine during a fixed time period can be obtained from the molar flow rate by integrating it over that time period.

[0058] According to a preliminary step, the mass flow rate of hydrocarbons introduced into the heat engine by the fuel is determined (block 100 of [Fig.1]).

[0059] This determination can be made on the basis of a measurement or on the basis of an estimate or a precise calculation.

[0060] To this end, the system 20 here comprises at least one sensor 7 disposed in the fuel supply circuit of at least one internal combustion engine 1. This is, for example, a mass or volumetric flow meter measuring the mass or volume of fuel entering the internal combustion engine 1 per unit of time. As shown by an arrow in [Fig. 2], the data measured by the sensor 7 are transmitted to Computer unit 11. Mass flow rate can be deduced from volumetric flow rate by multiplying the latter by the density of hydrocarbons.

[0061] In the case where the vehicle in question has several internal combustion engines 1, a flow meter is preferably provided on the path of the supply circuit of each internal combustion engine 1 or a single flow meter measuring the supply of all the internal combustion engines together.

[0062] As mentioned above, the total mass flow of fuel measured includes a non-carbon portion.

[0063] The mass flow rate of hydrocarbons in the fuel is deduced by subtracting from the total mass flow rate of fuel measured the mass flow rate of non-carbon fuel, namely the mass flow rate of fuel consisting of sulfur or nitrogen chemical compounds, i.e. 5% of the total mass flow rate for liquid fuel and 1.5% of the total mass flow rate for gaseous fuel.

[0064] In other words, the hydrocarbon mass flow rate of the fuel is equal to 95% of the total mass flow rate for a fuel of the liquid fuel type and 98.5% of the total mass flow rate of the fuel for a fuel of the gaseous fuel type.

[0065] It is possible to consider any other method of determination, for example the reception of this information by the computer unit 11 or its determination from tabulated or estimated fuel hydrocarbon consumption data.

[0066] For this determination, all carbonaceous chemical compounds entering the engine are taken into account, in particular the hydrocarbons of the main fuel alone if no pilot fuel is used, the hydrocarbons of the main fuel and pilot fuel introduced into the heat engine if pilot fuel is used or the hydrocarbons of the pilot fuel alone if the main fuel does not contain hydrocarbons.

[0067] We will see later detailed examples in which the engine is supplied only by a primary fuel or by a primary fuel and a secondary fuel.

[0068] According to another preliminary step, for a given composition of the hydrocarbons supplying the heat engine 1, a value of a quantity characteristic of the composition of these hydrocarbons is further determined depending on a reference ratio RC / H between a number of carbon atoms and a number of hydrogen atoms characteristic of this hydrocarbon composition (block 200 of [Fig.1]), i.e. RC / h = number of C / number of H = (mass % of C / mass % of H) * 1 / 11.915.

[0069] [Math.l] * M» %moss_C' 1 VJ- =■ " - - : ■----- . : . . . . * Mc %inass_H 11.915

[0070] The value of this quantity is calculated by the computer unit 11 or retrieved by it from a database. It can also be received by it using communication means.

[0071] The computer unit 11 can be programmed to determine the reference ratio based on data relating to the fuel composition. This can be a predetermined reference ratio for a generic fuel type or a ratio determined based on the precise measured composition of the fuel used. In particular, the hydrocarbon composition can be determined in order to determine the reference ratio Rc / H.

[0072] The hydrocarbon composition of the fuel can be measured by taking a sample from the fuel supply circuit of each internal combustion engine 1. For this purpose, as shown in [Fig.2], the system can include a fuel sampling device 8 from the supply circuit of the internal combustion engines 1, a conditioning device 9 and an analysis device 10, for example by gas phase spectrometry.

[0073] The conditioning device includes, for example, a condenser, i.e., a system that produces cold and allows the water vapor to condense. This system cools the (initially hot) gases to a temperature acceptable for the analyzer (for example, no more than 40°C).

[0074] The computer unit 11 receives the analysis results from the analysis device and determines the reference ratio on this basis.

[0075] In the case where the fuel is almost exclusively composed of the same molecule, for example methanol, the reference ratio is calculated based on the C and H composition of this molecule.

[0076] In the case where the fuel is composed of a known and limited mixture of molecules, for example in the case of LNG, the concentrations of these molecules can vary from one tank refill to another and also over time during a journey. The concentrations of these molecules are then measured by the fuel analysis device 10 and used to determine the reference ratio.

[0077] In other cases, particularly when the fuel is composed of a mixture of molecules that is unknown and limited, the reference ratio cannot be easily calculated; it is measured upstream and provided by the supplier. Tabulated values ​​from the literature can be used.

[0078] The reference report is for example stored in the memory of the computer unit 11.

[0079] We first describe here the case where each thermal engine of the vehicle is powered by a single fuel: the main fuel, without the addition of pilot fuel.

[0080] According to a first embodiment, the quantity is denoted afuei and is equal to the inverse of the sum of the molar mass of carbon Mc and the ratio between the molar mass of hydrogen and the reference ratio RC / H, according to the formula:

[0081] [Math.2]

[0082] According to a second embodiment, this quantity is equal to a conversion factor CFenter the hydrocarbon consumption of the heat engine 1 and the carbon dioxide CO2 emission by this heat engine 1.

[0083] This conversion factor is determined, for example, according to the nature of the fuel used. Its values ​​are standardized and listed in resolution MEPC.364(79), "2022 guidelines on the method of calculation of the attained energy efficiency design index for new ships", paragraph 2.2.1.

[0084] The corresponding table is reproduced below:

[0085] [Tables 1] Fuel Type Conversion Factor cF Diesel / Gasoline (e.g., ISO8217 grade from DMX to DMB) 3.206 Light Fuel (e.g., ISO8217 grade from RMA to RMD) 3.151 Heavy Fuel (e.g., ISO8217 grade from RME to RMK) 3.114 Liquefied Propane Gas (LPG, propane) 3.000 Liquefied Butane Gas (LPG, butane) 3.030 Liquefied Natural Gas (LNG) 2.750 Methanol (MeOH) 1.375 Ethanol (EtOH) 1.913

[0086] This quantity CF is an approximation of the product of the characteristic quantity afuei defined above and the molar mass of carbon dioxide.

[0087] In a step of said method (block 300 of [Fig.1]), a molar flow rate of carbon atoms introduced into the engine (nc_fUei) by the main fuel is determined.

[0088] For this purpose, the value of the characteristic quantity afuei, CF defined above and the mass flow rate of hydrocarbons introduced into the heat engine by the main fuel determined previously are taken into account.

[0089] This step is carried out by calculation by the computer unit 11 of the system 20.

[0090] According to the first embodiment in which the characteristic magnitude afuei is determined, we obtain the initial value of the molar flow rate of carbon atoms nc_fuei introduced into the heat engine by the following formula, by multiplying the initial value of the mass flow rate of hydrocarbons me Hx_fuei introduced by the value of the characteristic quantity afuei:

[0091] [Math.3]

[0092] Indeed, we have: mCHx_fuei = mc_fUei + mH_fuei with mc_fuei and mH_fuei the mass flow rate of carbon and the mass flow rate of hydrogen introduced into the engine.

[0093] Let: mCHx_fuei = nc_fuel * Mc + nH fuei * MH with nc_fuei and nH fuei the molar flow rate of carbon and hydrogen introduced into the engine and Mc = 12.011 g / mol and MH = 1.008 g / mol.

[0094] Or: mCHx_fuei = nC fuei * Mc + (nc_fuei / RC / H) * MH

[0095] And finally: nc_fuei = mCHx_fuei*afuei.

[0096] According to the second embodiment in which the characteristic quantity CF is determined, the initial value of the molar flow rate of carbon atoms nc_fuei introduced into the heat engine by the main fuel is obtained using the following formula, by multiplying the initial value of the mass flow rate of hydrocarbons mc hx introduced by the value of the characteristic quantity CF and dividing this product by the molar mass of carbon dioxide CO2.

[0097] [Math.4] ™CO2

[0098] As presented in the assumptions stated above, the proportion of carbon atoms supplied by the air is negligible, and it is therefore assumed that all the carbon atoms contained in the exhaust gases come entirely from the hydrocarbons of the main fuel, i.e., nc_exh = nc_fuei + nc_air = nc_fuei, with nc_exh the molar flow rate of carbon in the exhaust gases, nc_fuei the molar flow rate of carbon in the fuel introduced into the engine, and nc_ii the molar flow rate of carbon in the air introduced into the engine.

[0099] According to another step of the method (block 400 of [Fig. 1]), the concentrations of the expected carbonaceous chemical compounds in the exhaust gases are determined.

[0100] The carbonaceous part of the exhaust gases consists mainly of CO2, but also potentially of CO, unburned CH4 and other unburned hydrocarbons.

[0101] Unburned hydrocarbons other than CH4 are not considered toxic pollutants or greenhouse gases and are in negligible quantity. They are not taken into account in the following.

[0102] In other words, it is determined that the concentration of unburned hydrocarbons other than methane is equal to zero for the remainder.

[0103] We will therefore have: nc_fuei = nc_exh=nC02_eXh + nC0_eXh+ nCH4_eXh-

[0104] At least a portion of the concentrations of carbonaceous chemical compounds are measured expected. Preferably, the concentrations of all expected carbonaceous chemical compounds are measured.

[0105] The expected carbonaceous chemical compounds include carbon dioxide and carbon monoxide and possibly methane.

[0106] If it is known that the fuel cannot emit CH4, only the concentrations of carbon dioxide (CO2) and carbon monoxide (CO) are measured. For fuel containing Liquefied Natural Gas, methane emissions are expected; the concentration of methane in the exhaust gases is also measured.

[0107] The system 20 includes an exhaust gas sampling device 4, and an analysis device 6 for the exhaust gases sampled, for example by gas phase spectrometry.

[0108] In order to cool and remove water vapor from the exhaust gases before they pass into the analysis device 6, the system 20 further includes a conditioning device 5 disposed on the path of the exhaust gases sampled by the sampling device 4, as described in more detail below.

[0109] In the case where the vehicle equipped with system 20 includes several internal combustion engines 1, system 20 may include one analysis device per engine or a single analysis device for which the sample collection is carried out successively in the exhaust duct of one engine and then another, for example according to variations in engine operating speed, or simultaneously in all the exhaust ducts of the engines.

[0110] The concentration in the exhaust gases of each expected carbonaceous chemical compound in the exhaust gases is thus measured: for example, the concentrations of carbon dioxide, carbon monoxide and methane.

[0111] It is also possible to measure by the same technique the concentration of at least one non-carbon chemical compound, such as nitrous oxide N2O, nitrogen oxides NOx and sulfur oxides SOx.

[0112] The concentration of said carbonaceous or non-carbonaceous chemical compound in the exhaust gases is measured for example using the gas analysis device by gas spectrometry.

[0113] For this purpose, at least one exhaust gas sample 3 is taken from said internal combustion engine 1.

[0114] With a remote infrared gas spectrometry analysis device, the actual concentrations of the chemical compounds of the exhaust gas 3 in the exhaust duct cannot be directly measured.

[0115] The exhaust gas sample taken from the exhaust pipes must be conditioned before introduction into the analysis device 6: the sample taken is cooled and the water vapor is removed from this sample by passing through the conditioning device 5 before its analysis by gas phase spectrometry by the infrared spectrometer.

[0116] In the case where the vehicle in question has several internal combustion engines, it is preferable to take a sample of the exhaust gases from each internal combustion engine and to determine the quantity of the carbonaceous and, possibly, non-carbonaceous chemical compound emitted by all the internal combustion engines.

[0117] According to the ideal gas law, the volume concentrations of gases are equal to the molar concentrations for each of the gases constituting a mixture of ideal gases.

[0118] Under the pressure and temperature conditions of the gases entering the gas analysis device 6, the ideal gas law can be considered valid and can be applied.

[0119] Consequently, it can be considered that the molar concentrations of the exhaust gases 3 entering the analysis device 6 are equal to the volumetric concentrations measured by the analysis device.

[0120] The analysis device 6 thus provides the molar concentrations xi anaiyser of carbonaceous chemical compounds and the molar concentrations xj anaiyser of non-carbonaceous chemical compounds of the analyzed exhaust gases.

[0121] As represented by an arrow on [Fig.2], the analysis results of device 6 are transmitted to the computer unit 11. This unit thus receives measurement data of the concentration of the expected carbonaceous chemical compounds in the exhaust gases.

[0122] According to another step of the method (block 500 of [Fig.1]), a final value of the molar flow rate of hydrocarbons mc Hx _fuei introduced into the heat engine determined previously and of the concentrations of the expected carbonaceous chemical compounds in the exhaust gases, x; _anaiyser measured in the exhaust gases, is deduced.

[0123] This determination is carried out taking into account that all the carbon C present in the fuel is found in the exhaust gases mainly as CO2, and in smaller quantities as CO and CH4.

[0124] This step is carried out by calculation by the computer unit 11.

[0125] More specifically, the initial value of the molar flow rate of carbon atoms nc fuei introduced into the heat engine is deduced from the initial value of the mass flow rate of hydrocarbons introduced into the engine, taking into account the characteristic quantity of the hydrocarbon composition, as described above.

[0126] Then, the final value of the molar flow rate of carbon dioxide nCO2_exh released in the exhaust gases is deduced based on the initial value of the molar flow rate of carbon atoms nc_fUei introduced into the heat engine and the sum of the ratios between the concentration of each carbonaceous chemical compound x; _ anaiyser measured in the exhaust gases by the analysis device, including carbon dioxide, and the concentration of carbon dioxide xCO2_anaiySer measured in these exhaust gases, for example according to the formula:

[0127] [Math.5] „ nCJuel ^COl exh V

[0128] We have indeed, for two chemical compounds i and y: n; = x; * ntotai and ny = xy * ntotai, and therefore, n; = x; / xy.

[0129] More precisely, here, the final value of the molar flow rate of carbon dioxide nCO2_exh released in the exhaust gases is deduced based on the initial value of the molar flow rate of carbon atoms nc fuei introduced into the heat engine and the sum of the ratios between the concentration of each other expected carbonaceous chemical compound in the exhaust gases and the concentration of carbon dioxide xco2_anaiySer in these exhaust gases. For example, here the concentrations of dioxide The concentrations of carbon, carbon monoxide, and methane are determined using the following formula:

[0130] [Math.6] ^c^anaiyser , xÜÆ<ana-îyser ^Ç£> 2_an a lyse r ^GO2_anaîyser

[0131] Indeed, we have the following relationship:

[0132] [Math.7] '^OZ.sxS. ' -^COS.exft * ......... ' ^■caz.gæà. * ........... '•*£02^ " ACG2_exA Where xCo 2 _exh denotes the concentration of CO2 in the exhaust gases sampled, *co_exh denotes the concentration of CO in the exhaust gases sampled, *c H4 _exh denotes the concentration of CH4 in the exhaust gases sampled, nco2_exh denotes the molar flow rate of CO2 released in the exhaust gases 3.

[0133] That is:

[0134] [Math. 8]

[0135] And:

[0136] [Math.9] ex?î. 1 .............~.......... 4 ...............~..........

[0137] As explained above, the exhaust gas sample taken from the exhaust ducts is dried before introduction into the analysis device 6.

[0138] The sample is therefore modified and the concentrations measured by the analysis device are therefore different from the actual concentrations in the exhaust pipes.

[0139] However, drying the sample only reduces the amount of moisture in the sample taken.

[0140] For all compounds i and y that are not impacted by drying, then the quantities are conserved and there is an equality between the number of moles of chemical compound i or y in the sample taken (ni sampie, nysampie) and in the analyzed sample, i.e., with nt otai_sampie the total number of moles of the sample taken and nt otal anaiyseJe the total number of moles of the analyzed sample:

[0141] Hi_sample Hi _ analyze ^i_sample Ht otal_ sample ^-i_analyser otal_ analyze,

[0142] Hy_sample Hy _ analyze ^y_sample Ht otal_ sample ^y_analyser Ht otal_ analyze*

[0143] And. Xi sampie / Xy_samp^e Xi_analyser / Xy_analyser .

[0144] Finally, the concentrations in the exhaust gases are considered to be the same as in the sample taken, therefore xi exh / xy_exh = xi anaiySer / Xy_anaiySer.

[0145] Since the calculation method uses concentration ratios, it is then possible to use the concentration measurements of the gas analysis device without correcting the values ​​obtained.

[0146] According to another step of the method (block 600 of [Fig. 1]), the mass flow rate of the chemical compound emitted in the exhaust gases is determined. This step is performed by calculation using computer unit 11.

[0147] To determine the value of the mass flow rate of each carbonaceous chemical compound m; _ exh emitted in the exhaust gases, a final value of a molar flow rate of each carbonaceous chemical compound niexhrejected in the exhaust gases is deduced from the final value of the mass flow rate of carbon dioxide released in the exhaust gases and the ratio between the concentration of said carbonaceous chemical compound Xi_anaiySer measured in the exhaust gases and the concentration of carbon dioxide Xco2_anaiySer in these exhaust gases.

[0148] We have ni_exh — WcO2_exh* Xi_analyser / XcO2_analyser.

[0149] This final value of the molar flow rate of the carbonaceous chemical compound is then multiplied by the molar mass of the carbonaceous chemical compound. Finally, the value of the mass flow rate of each carbonaceous chemical compound can be obtained according to the formula. 111 _ ex|, n _ex|, IVI Mi Uco2_exh Xj _analyze / XcO2_analyze.

[0150] The mass flow rate of carbon dioxide emitted is determined directly by multiplying the molar flow rate of carbon dioxide by the molar mass of carbon dioxide.

[0151] We have the following formula: mCO2_exh = nCO2_exh*MCo2-

[0152] For all non-carbon chemical compounds of the type nitrous oxide N2O, nitrogen oxide or sulfur oxide whose concentration in the exhaust gases is determined by the analysis device 6, the same formula applies and we have nj exh = HcO2_exh Xj_analyzer / XcO2_analyzer.

[0153] In other words, the same steps are performed for a non-carbon chemical compound. A final value is determined for the molar flow rate of each non-carbon chemical compound nj released in the exhaust gases, from the final value of the mass flow rate of carbon dioxide released in the exhaust gases, and from the ratio between the concentration of said non-carbon chemical compound Xj to be analyzed measured in the exhaust gas and the concentration of carbon dioxide xCO2_anaiySer in these exhaust gases.

[0154] In practice, we thus have:

[0155] mC02_exh = nC02_exh * MC02, with MCO2 = 44.01 g / mol,

[0156] nicH4_exh = nCO2_exh * MCH4*XCH4_anaiysel / xC02_analyser, SVCC MCH4 = 16.04 g / mol,

[0157] mN2O_exh = HcO2_exh^' MN2o'1' XN20_analyser / XC02_analyser,aVeC MN2O = 44, 01 g / mol.

[0158] Once one or more values ​​of the mass flow rate of the chemical compound sought have been determined over a given period, the said value of the mass of the chemical compound emitted in the exhaust gases during this period is deduced by integrating the value or values ​​of the mass flow rate determined over this period.

[0159] When the main fuel is ammonia and the pilot fuel is hydrocarbons, the method described above is applied taking into account only the quantity of pilot fuel used, consisting of hydrocarbons.

[0160] In the case of heat engines requiring the additional injection of pilot fuel composed of hydrocarbons in addition to the main fuel, the number of carbon atoms supplied by this pilot fuel is taken into account.

[0161] The reference ratio of the pilot fuel may differ from the reference ratio of the main fuel. A pilot fuel with a reference ratio RC / H_piiof is then considered. The main fuel has the reference ratio RC / H as described previously.

[0162] We will consider the parameter em which corresponds to the mass proportion of hydrocarbons in the pilot fuel and hydrocarbons in the main fuel such that the mass flow rates of pilot fuel mCHx_Piiot and main fuel mCHx_fuei satisfy:

[0163] IîlCHx_pilot em lllf nx _fuel*

[0164] We then have the molar flow rate of carbon atoms supplied by the pilot fuel as a function of the mass flow rate of hydrocarbons in the pilot fuel, which is written with a relationship similar to that established for the main fuel:

[0165] ric_piiot — rncti\_p iot ctpiiot

[0166] with

[0167] [Math. 10]

[0168] The total molar flow rate of carbon atoms nc tot introduced into the heat engine(s) is therefore:

[0169] nc_tot— ne jue +Hc_pUot*

[0170]

[0171]

[0172]

[0173]

[0174] Let mc Hx _fuel^ ^fuel+ÏÏlc Hx _pilot^ ^pilot Hx _fuel^ HIq Hx _ fuel^ ^pilot . We can then define an equivalent alpha relating to the main fuel: Hc_tot— lïlc Hx _fuel^ (^fuel+em Ctpilot) — Hic Hx _fuel^ C^equi . with CteqUi Clfuel + of the CtpilQt* The method is then similar to that described previously for the case where only one primary fuel is used. The same formulas are used, substituting nc_fuei by nc_tot.

[0175] We then have . nco2_exh Hc_tot / (1 + X(2O_analyser / Xco2_analyser"^ X(2H4_analyser / Xq q 2_analyser)*

[0176] In the case where the internal combustion engine is fueled with methanol CH3-OH or ethanol C2H5-OH, the use of these fuels will produce only CO2 and no CH4 or N2O.

[0177] The established formulas and the method described above can nevertheless be applied. We then have the following for methanol:

[0178] nicHx_fuei = nc_f ue 1 * (Mc + 4* MH+MO) = nC f ue 1 * Mch3_Oh and afuei = 1 / Mch3_Oh

[0179] MCh3 oh = 32.04 g / mol and afuei = 0.03121.

[0180] For ethanol:

[0181] nicHx_fuei = nc_f ue 1 * (2*Mc + 6* MH+M0) = nC f ue 1 * Mc 2hs oh and afuei = 2 / Mc 2hs oh

[0182] Mc 2H5 oh = 46.068 g / mol and afuei = 0.04341.

[0183] In the case of the use of a sulfur-containing fuel, such as liquid hydrocarbon fuels, the mass of sulfur compounds is subtracted from the total mass of the fuel as described above.

[0184] In the case of residual heavy fuels containing too high a sulfur content, regulations require the implementation of a scrubber, an engine exhaust fume cleaning system (EGCS).

[0185] The main action of scrubbers is to reduce SOx (SO2 and SO3 in particular), that is to say to limit the quantity of these molecules released in the exhaust gases.

[0186] During the combustion of a sulfur-containing fuel, the sulfur atoms (S) are transformed primarily into sulfur oxides (SOx) (mainly SO2, with SO3 representing less than 4% of the SOx). The remaining fraction of sulfur atoms contributes to the formation of various soot particles. The mass fraction of these soot particles is negligible.

[0187] Sulfur does not impact the formation of CO2 and CO for a hydrocarbon fuel liquid. The action of a scrubber, regardless of its removal rate, does not influence the determination method presented above. The method described below can therefore be used in the presence or absence of a scrubber.

[0188] Therefore, provided that the mass of sulfur to be subtracted from the mass of fuel for the calculation of the hydrocarbon mass share has been correctly quantified, it is not necessary to take into account the action of the scrubber and its effectiveness.

[0189] In the case of liquefied natural gas (LNG) used as fuel, it has already been explained above that the mass of dissolved nitrogen (whatever its quantity) must be subtracted from the total mass of fuel supplied to the engines.

[0190] The fuel supply for the thermal engines of a ship powered by LNG is a mixture of naturally evaporated gas and vaporized LNG, which implies that the nitrogen content and the corresponding mass flow rate are not predetermined and vary according to operating conditions and operator demand. These values ​​are therefore measured.

[0191] Arzew LNG, for example, is one of the most loaded with dissolved nitrogen, it contains 0.71% in molar percentage, or -1.23% by mass.

[0192] It is estimated that naturally evaporated LNG contains -15.54% dissolved nitrogen by molar percentage, or -24.3% by mass.

[0193] Consequently, if only natural boil-off gas is consumed, the corresponding CO2 calculation based on the total fuel flow rate in the internal combustion engine would be overestimated by +24.3%. Subtracting the amount of sulfur compounds is therefore an important correction for improving the accuracy of determining the amount of CO2 emitted.

[0194] The following table gives the reference ratios typically determined and the corresponding quantities for different types of fuels.

[0195] [Tables2] Fuel Type Designation Main Characteristics Reference Ratio RC / h Quantity of Fuel Marine Fuel MGO Fuel No. 2, Bunker A 0.53-0.56 0.0718-0.0724 MDO Fuel No. 3: 10% Fuel No. 6 max + 90% Fuel No. 2 0.52-0.56 0.0716-0.0724 NFSO Fuel No. 5, Bunker B: 75-80% Fuel No. 6 + 20-25% Fuel No. 2 0.48 0.0710 IFO 180, IFO 38 0 90% Fuel No. 6 + 10% Fuel No. 2 0.57-0.64 0.0726-0.0736 HFO, RFO Fuel No. 6, Bunker C Liquefied Petroleum Gas Propane C3 100% 0.4 0.0688 Butane C4 i / n 100% 0.375 0.0680 Propane / Butane Mixture C3 / C4 50 / 50% 0.390 0.0685 LE Pure Ethane C2 100% 0.3333 0.06651 Cargo Ethane 0.3337 0.06653 Liquefied Natural Gas (LNG) Pure Methane CH4 100% 0.250 0.0623 Alaska Cl 99.7% 0.250 0.0623 Brunei Cl 90.2% 0.268 0.0634 Libya Cl 82.57% 0.275 0.0638

[0196] System 20 equips for example a ship, in particular a methane tanker or a ship using Liquefied Natural Gas as fuel.

[0197] Some of the elements of the computer unit 11 can be implemented in various forms, either individually or in a distributed manner, using hardware and / or software components. Usable hardware components include ASICs, FPGAs, or microprocessors. Software components can be written in various interpreted or compiled programming languages, for example, C, C++, Java, Python, SQL, or VHDL. This list is not exhaustive.

[0198] Thanks to the method and system described above, the quantity of chemical compounds released in the exhaust gases of an engine at least partially supplied with hydrocarbons can be determined quickly and accurately.

[0199] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0200] The use of the verb "comprise", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

[0201] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. A method for determining a value of a quantity relating to a quantity of at least one chemical compound, said chemical compound being emitted by a heat engine (1) fueled at least partially by hydrocarbons, comprising the following steps: - determining (100) an initial value of a quantity relating to a quantity of hydrocarbons introduced into the heat engine (1) and deducing therefrom an initial value of a quantity relating to a quantity of carbon atoms introduced into the engine, - determining (400) the concentrations of a plurality of carbon-based chemical compounds expected in the exhaust gases (3), - deducing (500) from said initial value of the quantity relating to the quantity of hydrocarbons introduced into the heat engine (1) determined previously and from the concentrations of said plurality of carbon-based chemical compounds expected in the exhaust gases (3),a final value of a quantity relating to a quantity of carbon dioxide released in the exhaust gases (3) and deduce therefrom (600) said value of said quantity relating to the quantity of the chemical compound emitted in the exhaust gases (3).,

2. Method of determination according to claim 1, wherein: - the quantity relating to the amount of at least one chemical compound is a mass flow rate of the chemical compound or a mass, - the quantity relating to the amount of hydrocarbons introduced into the heat engine is a mass flow rate or a mass, - the quantity relating to the amount of carbon atoms introduced into the engine is a molar flow rate or a number of moles, - the quantity relating to the amount of carbon dioxide released in the exhaust gases (3) is a molar flow rate or a number of moles.

3. A method according to any one of claims 1 and 2, wherein: - the quantity relating to the amount of at least one chemical compound is a mass, - the quantity relating to the amount of hydrocarbons introduced into the heat engine is a mass flow rate - the quantity relating to the quantity of carbon atoms introduced into the engine is a molar flow rate, - the quantity relating to the quantity of carbon dioxide released in the exhaust gases (3) is a molar flow rate and a value of a mass flow rate of the chemical compound is determined and the said value of the mass of the chemical compound emitted in the exhaust gases (3) is deduced during a time period by integrating the mass flow rate determined during this time period.

4. A method according to any one of claims 1 to 3, furthermore, for a given composition of hydrocarbons supplying the heat engine (1), a value of a quantity characteristic of this composition is determined, this characteristic quantity depending on a reference ratio between a number of carbon atoms and a number of hydrogen atoms characteristic of this hydrocarbon composition, and this value of the characteristic quantity is taken into account to deduce the initial value of the quantity relating to the quantity of carbon atoms introduced into the heat engine (1).

5. Method according to claim 4, wherein said characteristic quantity is equal to the inverse of the sum of the molar mass of carbon and the ratio of the molar mass of hydrogen to the reference ratio.

6. Method according to claim 4, wherein said characteristic quantity is equal to a conversion factor between the hydrocarbon consumption of the heat engine (1) and the carbon dioxide emission by this heat engine (1).

7. A method according to any one of claims 4 to 6, wherein the heat engine is supplied with two fuels of different compositions, each having a reference ratio, and said characteristic quantity depends on the reference ratios of the two fuels.

8. A method according to any one of claims 1 to 7, wherein the final value (500) of the quantity relating to the amount of carbon dioxide released in the exhaust gases is deduced from the initial value of the quantity relating to the amount of carbon atoms introduced into the heat engine (1) and from each ratio between the concentration of each expected carbonaceous chemical compound in exhaust gases (3) and the concentration of carbon dioxide in these exhaust gases (3).

9. A method according to any one of claims 1 to 8, wherein the expected carbonaceous chemical compounds comprise at least carbon dioxide and carbon monoxide and the chemical compound is selected from one of the following carbonaceous chemical compounds: carbon dioxide, methane, carbon monoxide, nitrous oxide, nitrogen oxides, sulfur oxides.

10. A method according to any one of claims 1 to 9, in which the concentrations of expected carbonaceous chemical compounds are measured in the exhaust gases (3) using a gas analysis device (6) by gas spectrometry.

11. Method according to claim 10, wherein at least one exhaust gas sample (3) is taken from said heat engine (1), this sample is cooled and / or the water vapor is removed from this sample before it passes through the gas analysis device.

12. A method according to any one of claims 1 to 11, wherein the value of the quantity relating to the amount of the chemical compound emitted in the exhaust gases is deduced from the final value of the quantity relating to the amount of carbon dioxide released in the exhaust gases and from the ratios between the concentration of each expected carbonaceous chemical compound in the exhaust gases and the concentration of carbon dioxide in these exhaust gases.

13. A system (20) for determining the value of a quantity relating to a quantity of at least one chemical compound, said chemical compound being emitted by a heat engine (1) fueled at least partially by hydrocarbons, comprising a computer unit (11) comprising one or more processors programmed to carry out the following steps: - determine (100) an initial value of a quantity relating to a quantity of hydrocarbons introduced into the heat engine (1) and deduce therefrom an initial value of a quantity relating to a quantity of carbon atoms introduced into the engine, - determine (400) the concentrations of a plurality of expected carbon-based chemical compounds in the exhaust gases (3), - calculate (500), on the basis of said initial value of the quantity relating to the quantity of hydrocarbons introduced into the engine

14.

15.

16. thermal (1) determined previously and the concentrations of said plurality of carbonaceous chemical compounds expected in the exhaust gases, a final value of a quantity relating to a quantity of carbon dioxide released in the exhaust gases (3) and deduce therefrom (600) said value of said quantity relating to the quantity of the chemical compound emitted in the exhaust gases. System (20) for determination according to claim 13, further comprising a device for analyzing exhaust gases by gas spectrometry. A system (20) for determining fuel consumption according to any one of claims 13 and 14, further comprising a fuel analysis device (10). A vessel equipped with a system according to any one of claims 13 to 15.

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