DEVICE AND METHODFOR PRODUCING SUBSTITUTE NATURAL GAS AND NETWORK
COMPRISING SAME
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device and method for producing substitute natural
gas and a network comprising same. It applies in particular to industrial methanation and the
cogeneration of thermal energy and methane.
5
STATE OF THE ART
Methanation is an industrial process that catalytically converts hydrogen and carbon
monoxide or carbon dioxide into methane.
The formula for the methanation reaction varies according to the nature of the carbon-
10 based compound. Depending on the case, this formula is:
CO +3 HZ 3 CH4 + Hz0
C02 +4 Hz 3 CH4 + 2 Hz0
Usually, a biomethane production device for which biomass is the main input
comprises three main elements. The first element is a means of gasifying the biomass into
15 synthetic gas (also called "syngas"). This syngas is mainly composed of non-condensable
gases such as, for example, HZ, CO, COZ or CH4. For certain methods, as well as the syngas
produced the gasif~cation means also produces tar-type condensable gases, hereinafter
referred to as "tars", and solid residues of "char" type, i.e. a solid portion resulting from
pyrolysis of a solid combustible.
20 The gasification means is associated with a combustion means in which the solid
residues, such as the chars, are burnt to maintain the temperature of the gasification means.
This combustion means is normally a moving or circulating bed reactor. This fluidized
medium is preferably comprised of particles of olivine catalyst, and more preferably of a heattransfer
solid such as sand, for example. This fluidized medium makes it possible to facilitate
25 the extraction of residual chars that have not reacted in the gasif~cation means and to
facilitate the transporting of these chars to the combustion means.
The second main element is the catalytic methanation of the gasified biomass, this
methanation consisting of converting the HZ and CO into CH4 (SNG, for "Synthetic Natural
Gas").
The third main element is bringing the residual SNG up to specification, i.e.
eliminating the residual HZ, CO, H20 and C02 so as to produce an SNG as close as possible
to the specifications for injection into the natural gas grid, in particular in terms of higher
heating value, referred to as "HHV", and the Wobbe index. As a reminder, the Wobbe index
5 makes it possible to evaluate the capacity for interchangeability between gases, fuels or
combustibles.
The main drawback of the current systems stems from the absence of optimization in
the SNG yield on output from the system due to numerous carbon and energy losses
throughout the chain described above.
10
SUBJECT OF THE INVENTION
The present invention aims to remedy all or part of these drawbacks.
To this end, the present invention envisages, according to a first aspect, an integrated
device for producing substitute natural gas that comprises:
15 - a gasifier configured for producing a gaseous compound from a biomass, comprising:
- an inlet for the biomass;
- an inlet for an oxidizing agent; and
- an outlet for the gaseous compound comprising carbon monoxide;
- a means for methanating the carbon monoxide to produce substitute natural gas from
20 the gaseous compound output from the gasifier, the carbon monoxide methanation
means comprising at least one inlet for water and an inlet for the gaseous compound
coming from the gasifier;
. - a means for methanating carbon dioxide to produce substitute natural gas
comprising at least one inlet for water and an inlet for the carbon dioxide coming from
25 the carbon monoxide methanation means;
- a means for producing dihydrogen from water and electric current comprising:
- an electrical power supply;
- an inlet for water and
- a dihydrogen outlet supplying the carbon dioxide methanation means.
30 It is noted that a "gasifier" is, by misuse of the language, sometimes called a
"gasificator".
Thanks to these provisions, the carbon dioxide present on output from the carbon
monoxide methanation means is transformed into SNG by the carbon dioxide methanation
means, thus increasing the carbon conversion yield of the device as a whole. In addition, the
35 presence of a means of electrolyzing water allows "power to gas" types of applications to be
realized. As a reminder, power-to-gas applications consist of converting unused electrical
energy, for example produced at night by a nuclear power station, into substitute gas that
can be used subsequently to regenerate electrical energy.
In some embodiments, the device that is the subject of the present invention also
comprises a combustion means comprising:
5 - an inlet for a solid portion resulting from pyrolysis of a non-gasified solid combustible,
also called "char", coming from the gasifier and transported by a heat transfer
medium;
- an oxidizer inlet;
- a non-gasified char combustion means for heating the heat transfer medium;
10 - a heat transfer medium outlet linked to a heat transfer medium inlet of the gasifier;
and
' - an outlet for flue-gases.
The advantage of these embodiments is that they allow the gasifier's yield to be
increased by using non-gasified carbonized residuals to generate heat heating the gasifier.
15 The combustion of these carbonized residuals also allows the heat-transfer medium
transporting the carbonized residuals to be heated.
In some embodiments, the dihydrogen production means is configured to carry out an
electrolysis of water, comprising a dioxygen outlet supplying the oxidizer inlet of the
combustion means.
20 These embodiments have the advantage of dramatically increasing the yield of
substitute natural gas by making it possible to avoid injecting a portion of the synthetic gas
coming from the gasifier into the combustion means so as to make combustion possible. In
particular, these embodiments allow a power-to-gas application's efficiency to be maximized
by using all of the products from the electrolysis of water and by optimizing the yield of
25 substitute natural gas.
In some embodiments, the device that is the subject of the present invention
comprises, between the gaseous compound outlet of the gasifier and the gaseous compound
inlet of the carbon monoxide methanation means, a separator configured to separate the
gases from the solids andlor tars in the gaseous compound and to transmit the separated
30 solids andlor tars to the combustion means.
The first advantage of these embodiments is that they allow the synthetic gas coming
from the gasifier to be purified by removing solids that might be transported with the gas. The
second advantage of these embodiments is that they allow the solids to be recycled by using
them in the combustion means, thus increasing the yield of the combustion means.
In some embodiments, the device that is the subject of the present invention
comprises a means of recycling a portion of the flue-gas, on output from the combustion
means, comprising dioxygen, towards an oxidizer inlet of the combustion means.
These embodiments allow the yield of the combustion means to be ~ncreased by
5 recycling a portion of the products from the combustion means. These embodiments make it
possible for a given piece of equipment to be able to operate equally well with air-combustion
as with oxy-combustion. For a method initially designed to operate using air-combustion, the
fact of switching to oxy-combustion results in a drastic fall in speeds and leads to the
stopping of the circulation of the heat-transfer solid, and therefore of the production of gas. In
10 this case, in order to switch to oxy-combustion either a new combustion means with a
smaller diameter, to have suitable transport speeds, or a recirculation of flue-gas, to
compensate for the absence of nitrous oxide in the oxidizer, is necessary. The choice of fluegases
is certainly the most relevant since this is a product coming from the same system.
In some embodiments, the device that is the subject of the present invention
15 comprises, downstream from the flue-gas outlet of the combustion means, a carbon dioxide
separator configured to supply the carbon dioxide methanation means with carbon dioxide.
These embodiments allow the yield of the carbon dioxide methanation means to be
increased.
In some embodiments, the device that is the subject of the present invention
20 comprises a dihydrogen separator downstream from the carbon monoxide methanation
means in order to supply said carbon monoxide methanation means with dihydrogen.
These embodiments allow the yield of the carbon monoxide methanation means to be
increased. These embodiments are preferred in the case where the Wobbe index or the
higher heating value of the synthetic gas does not comply with the requirements of the gas
25 transmission network to which the synthetic gas is supplied.
In some embodiments, the device that is the subject of the present invention
comprises downstream from the carbon monoxide methanation means, a carbon dioxide
separator for supplying the carbon dioxide methanation means.
These embodiments make it possible to separate the methane on output from the
30 carbon monoxide methanation means from the carbon dioxide to be supplied to the carbon
dioxide methanation means. In this way, the gas has a higher concentration of carbon
dioxide on input to the carbon dioxide methanation means, as a result increasing the yield on
output from the carbon dioxide methanation means.
In some embodiments, an outlet from the carbon dioxide methanation means is linked
35 to an outlet from the carbon monoxide methanation means.
These embodiments make it possible to minimize the number of devices required
between the outlets from each methanation means and a substitute natural gas outlet of the
device.
In some embodiments, the device that is the subject of the present invention
5 comprises, downstream from the carbon monoxide methanation means andlor from the
combustion means, a condenser configured to condense the water contained in vapors and
to supply the electrolysis means with water.
These embodiments allow the yields of the electrolysis means to be increased.
According to a second aspect, the present invention envisages a network, which
10 comprises at least one device that is the subject of the present invention.
As the particular features, advantages and aims of the network are identical to those
of the device that is the subject of the present invention, they are not repeated here.
In some embodiments, the network that is the subject of the present invention also
comprises a multi-energy management means for controlling:
15 - the production, with at least one device that is the subject of the present invention,
and storage of methane during periods of surplus electricity production; and
- the production of electricity with the stored methane outside these periods.
These embodiments allow the amount of energy available in the network to be
optimized during the periods when the electricity produced is not in surplus.
20 In some embodiments, the network that is the subject of the present invention
comprises gas distribution pipelines, the storage of methane for generating electricity being
realized by overpressure above the nominal pressure of the pipelines.
These embodiments allow the methane produced by the device that is the subject of
the present invention to be stored at lower cost.
25 According to a third aspect, the present invention envisages a method for producing
substitute natural gas that comprises:
- a gasification step for producing a gaseous compound from a biomass, comprising:
- a step of inputting the biomass;
- a step of inputting an oxidizing agent; and
- a step of outputting the gaseous compound comprising carbon monoxide;
- a step of methanating the carbon monoxide to produce substitute natural gas from
the gaseous compound output from the gasification step, the carbon monoxide
methanation step comprising at least one input step for water and for the gaseous
compound from the gasifier;
- a step of methanating carbon dioxide to produce substitute natural gas comprising at
least one input step for water and an input for carbon dioxide coming from the carbon
monoxide methanation step;
- a step of producing dihydrogen from water and electric current comprising:
5 - a step of supplying electrical power;
- a water input step and
- an output step for dihydrogen used during the carbon dioxide methanation
step.
As the particular features, advantages and aims of the network are identical to those
10 of the device that is the subject of the present invention, they are not repeated here.
BRIEF DESCRIPTION OF THE FIGURES
Other particular advantages, aims and features of the invention will become apparent
from the non-limiting description that follows of at least one particular embodiment of the
15 device and method for producing substitute natural gas and of the network comprising said
device that are the subjects of the present invention, with reference to drawings included in
an appendix, wherein:
- figure 1 represents, schematically, a particular embodiment of the device for
producing substitute natural gas that is the subject of the present invention;
20 - figure 2 represents, schematically, a particular embodiment of the network that is the
subject of the present invention; and
- figure 3 represents, in the form of a logical diagram, steps in a particular embodiment
of the method that is the subject of the present invention.
25 DESCRIPTION OF EXAMPLES OF REALIZATION OF THE INVENTION
The present description is given as a non-limiting example.
It is now noted that the figures are not to scale.
Figure 1 shows an embodiment of the integrated device for producing substitute
natural gas that is the subject of the present invention. This device comprises:
30 - a gasifier 102, comprising:
- an inlet 104 for biomass;
- an inlet 106 for an oxidizing agent; and
- an outlet 108 for synthetic gas comprising carbon monoxide;
- a separator 138 configured to transmit separated solids and tars to the combustion
35 means 124;
- a means 110 of methanating the carbon monoxide output from the gasifier 102,
comprising at least one inlet 112 for water and for synthetic gas coming from the
gasifier 102, supplying methane and carbon dioxide;
- a dihydrogen separator 144;
5 - a first carbon dioxide separator 146;
- a carbon dioxide methanation means 114, comprising at least one inlet 116 for water
and for carbon dioxide coming from the carbon monoxide methanation means,
supplying methane;
- a means 11 8 of electrolyzing water comprising:
10 - an electric power supply 176;
- a water inlet 120;
- a dioxygen outlet 136; and
- a dihydrogen outlet 122; and
- a combustion means 124, comprising:
15 - an inlet 126 for non-gasified char transported by a heat transfer medium
coming from the gasifier 102;
- three inlets 128;
- a combustion means 130 for the non-gasified char, tars and make-up syngas
for heating the heat transfer medium;
- a heat transfer medium outlet 132 linked to a heat transfer medium inlet of the
gasifier 102 and
- an outlet 134 for flue-gases;
- an inlet 168 for non-gasified char and for tars separated from the gas coming
from the gasifier 102; and
25 - a means 140 of recycling a portion of the flue-gas coming from the combustion
means 124;
- a second carbon dioxide separator 142; and
- two condensers 148;
- three cooling means 150;
30 - two heating means 172;
- a first water vapor inlet 152;
- a dioxygen outlet 158;
- an ash and solid residues outlet 160;
- a first water outlet 154;
35 - a second water outlet 162;
- an outlet 164 for gas not used by the device;
- a second water vapor inlet 166; and
- a substitute natural gas outlet 170.
The gasifier 102 is, for example, a reactor in which the supplied biomass undergoes a
thermochemical conversion to form a synthetic gas (also called "syngas") containing
5 dihydrogen, carbon monoxide, carbon dioxide, water, tars, or, in general, any type of
carbonized compound. This gasifier 102 comprises a biomass inlet 104 that is, for example,
a valve, a dispensing screw or a hopper allowing the biomass to be introduced into the
reactor. This gasifier 102 also comprises an oxidizing agent inlet 106 that is, for example, a
valve allowing water vapor to be introduced into the reactor. Upstream from this oxidizing
10 agent inlet 106, a heating means 172 is positioned such that the incoming oxidant does not
disturb the thermal balance inside the gasifier 102.
The gasifier 102 also comprises a non-gasified char outlet (not shown) that is, for
example, a pipe into which a fluidized heat-transfer medium is transferred. This fluidized
heat-transfer medium consists, for example, of olivine or sand, and supplies the necessary
15 energy to the thermochemical conversion of the biomass. This gasifier 102 also comprises a
fluidized heat-transfer medium inlet, not shown. Lastly, this gasifier 102 comprises a
synthetic gas outlet 108 that is, for example, a pipe connected to the reactor.
In order to heat the gasifier 102, the device comprises a combustion means 124. This
combustion means 124 is, for example, a reactor. This combustion means 124 comprises an
20 inlet 126 for non-gasified char transported by a heat-transfer medium from the gasifier 102
that is, for example, a pipe linking the gasifier 102 to the combustion means 124. This
combustion means 124 also comprises three oxidizer inlets 128 that are, for example, valves
linked to pipes allowing the oxidizer to be introduced into the combustion means 124. One
inlet 128 is configured to insert air, nitrogen or dioxygen, or a mixture of all of these, for
25 example air enriched with dioxygen, into the combustion means 124. Upstream from this inlet
128, an, optional, means 172 of heating the oxidizer is placed such that the oxidizer input
does not disturb the internal thermal balance of the combustion means 124. Another inlet
128 is configured to insert dioxygen coming from the electrolysis of water into the combustion
means 124. The last inlet 128 is configured to insert, if necessary, synthetic gas coming from
30 the gasifier 102 into the combustion means 124, as a thermal booster in the case where char
and tars are not sufficient.
In some variants, these oxidizer inlets 128 can be combined into two or just one
oxidizer inlet. The combustion means 124 performs the combustion of the non-gasified char
andlor tars coming from the inlet 168 so as to heat the heat-transfer medium, this heat-
35 transfer medium leaving the combustion means 124 by means of a heat-transfer medium
outlet 132 linked to a heat-transfer medium inlet of the gasifier 102 that is, for example, a
pipe linking the combustion means 124 and the gasifier 102. This combustion means 124
also comprises an outlet 134 for flue-gases that is, for example, a pipe connected to the
combustion means 124.
Using dioxygen as an oxidizer improves the energy yield of the combustion means
5 124. Using dioxygen allows, in particular, a dramatic reduction in the synthetic gas coming
from the gasifier 102 being reused as oxidizer. The surplus dioxygen produced by the
electrolysis means 118 can also be recycled in other ways. In addition, the efficiency of the
separation chain comprising the condenser 148 and the carbon dioxide separator improves
as the dioxygen content in the oxidizer increases.
10 The composition of the synthetic gas generated by the gasifier 102 changes under
the action of the water vapor or of another oxidizing agent, such as for example dioxygen or
air, input into the reactor as a result of the thermochemical balances and the production of
compounds by heterogeneous gasification of char. For this reason, the synthetic gas
produced generally contains pollutants harmful to the lifespan of a catalyst contained in the
15 carbon monoxide methanation means 110. For this reason, a cooling or heat recovery
means 150 is placed at the outlet from the gasifier 102 and, at the outlet from this cooling
means 150, a separator 138 configured to transmit the separated solids and tars to the
combustion means 124. This cooling means 150 is, for example, a heat exchanger. This
cooling means 150 enables an exchange of heat to be performed, the heat being recovered
20 to be used elsewhere in the device.
The separator 138 is, for example, a filter configured to retain the solid compounds
paired to an absorber to retain the tars. This separator 138 supplies the combustion means
124 with solids thus separated by means, for example, of a pipe. The solids thus retained
can be organic compounds, inorganic compounds such as tars, hydrogen sulfide, carbon
25 monoxide sulfide, or a large portion of the water and solids transported with the gas flow. A
portion of the gas on output from the separator 138 can be supplied, as necessary, to the
combustion means 124.
Similarly, the flue-gas on output from the combustion means 124 is treated in the
same way by a cooling or heat recovery means 150 such as, for example, a heat exchanger,
30 cooling the flue-gases, and a gaslsolids separator 174 conf~gured to transfer the filtered
solids to an outlet 160 for ash and elutriated solids. A portion of the gas, containing dioxygen,
on output from this separator 174 can be supplied, as necessary, to the combustion means
124 as oxidizer.
The device comprises a means 110 of methanating the carbon monoxide output from
35 the gasifier 102 that is, for example, a catalytic methanation reactor. This catalytic
methanation reactor is, for example, a fixed-bed or fluidized bed reactor, or a
reactorlexchanger type. This catalytic methanation reactor transforms the carbon monoxide,
dihydrogen and water into carbon dioxide and methane. This carbon monoxide methanation
means 110 comprises an inlet 112 for water and for synthetic gas coming from the gasifier
102. This inlet 112 is for example a valve enabling water vapor and synthetic gas to be
5 inserted into the carbon monoxide methanation means 110.
The water vapor enters into the device by means of a first water inlet 152 that
supplies the inlet 112 for water and synthetic gas. The addition of water vapor allows the
dihydrogen to carbon monoxide ratio to be adjusted close to stoichiometry through the water
gas shift reaction (CO + H20 = Ha + C02) and thus to avoid a premature deactivation of the
10 catalyst by coke deposit. The carbon monoxide methanation means 110 produces, on
output, methane and carbon dioxide.
The gas mixture on output from the methanation means 110 is cooled by a cooling
means 150 that is, for example, a heat exchanger. The output synthetic gas is dehydrated by
a condenser 148. This condenser 148 can employ all water reduction techniques or their
15 associations, such as for example heat condensation, adsorption or absorption. The water
recovered in this way is transmitted to a water outlet 154. The water output in this way can
be evacuated from the device or be supplied to the electrolysis means 118.
The gas mixture on output from the condenser 148 is injected into a carbon dioxide
separator 146. The carbon dioxide separator 146 can use all known methods or their
20 combinations, such as, for example, the use of cryogenics, absorption or adsorption. The
person skilled in the art will select the solution of his choice provided this solution makes it
possible to obtain carbon dioxide with purity above 85% by volume. Too great a volume of
carbon monoxide present with the carbon dioxide favors the carbon monoxide methanation
reaction at the expense of the carbon dioxide methanation reaction in a methanation reactor
25 114.
In some variants, the recovered carbon dioxide is treated by an additional purification
means configured to remove the carbon monoxide present with the carbon dioxide. In
addition to the conventional solutions, such as, for example, adsorption or absorption, the
mixture containing the carbon dioxide separated by the separator 146 can undergo thermal
30 oxidation in the combustion means 124. It should be noted that thermal oxidation can only be
envisaged if the combustion means 124 operates with pure dioxygen or if the device
comprises a carbon dioxide separator on output from the combustion means 124.
In other variants, the device comprises a final carbon monoxide methanation means
upstream from the carbon dioxide methanation means 114.
35 The device comprises a means 114 of methanating the carbon dioxide output from
the gasifier 102 that is, for example, a catalytic methanation reactor. This catalytic
methanation reactor is, for example, a fixed-bed or fluidized bed reactor, or a -
reactorlexchanger type. This catalytic methanation reactor transforms the carbon d~oxide,
dihydrogen and water into carbon dioxide and methane. This carbon dioxide methanation
means 114 comprises an inlet 116 for water and for synthetic gas coming from the separator
5 146. This inlet 116 is for example a valve enabling water vapor and synthetic gas to be
inserted into the carbon dioxide methanation means 114. The water vapor enters into the
device by means of a first water inlet 166 that supplies the inlet 116 for water and synthetic
gas. The carbon dioxide methanation means 114 produces, on output, methane and water.
In addition to the carbon dioxide separated on output from the carbon monoxide
10 methanation means 110, carbon dioxide is recovered from the flue-gases on output from the
methanation means 124. To achieve this, the device comprises on output from the gas-solid
separator 174 on output from the methanation means 124 a condenser 148 configured to
dehydrate the flue-gas output from the separator 174. The water recovered is transferred to a
water outlet 162 enabling water to be evacuated from the device or this water to be
15 transferred to the water electrolysis means 118.
On output from this condenser 148, the remaining gas mixture enters a carbon
dioxide separator 142 similar to the carbon dioxide separator 146 on output from the carbon
monoxide methanation means 110. The gases separated from the carbon dioxide are
supplied to an outlet 164 of gases not used by the device. The carbon dioxide separated by
20 the separator 142 is supplied on input to the carbon dioxide methanation means 114.
The methane and water outlet 156 from the carbon dioxide methanation means 114 is
connected to the outlet, not shown, from the carbon monoxide methanation means 110,
downstream from the cooling means 150.
Downstream from the carbon dioxide separator 146, the device comprises a
25 dihydrogen separator 144. This dihydrogen separator 144 enables the specifications of the
synthetic gas to be adjusted to the characteristics of the natural gas. This dihydrogen
separator 144 can employ all of the usual methods or a combination of them. The separated
dihydrogen is supplied on input to the carbon monoxide methanation means 110 by means
of a pipe 156.
30 The synthetic gas on output from the dihydrogen separator 144 is supplied to a
synthetic gas outlet 170 of the device.
The device comprises a water electrolysis means 118 configured to transform the
water into dioxygen and dihydrogen. This electrolysis means 118 is, for example, an
electrolytic cell comprising two electrodes immersed in the water, each connected to an
35 opposite pole of a source 176 of direct current. This electrolysis means 118 comprises a
water inlet 120 that is, for example, a valve enabling water to be injected into the electrolysis
means 118. This electrolysis means 118 also comprises a dihydrogen outlet 122 supplying
the carbon dioxide methanation means 114. In addition, this electrolysis means 118
comprises a dioxygen outlet 136 supplying an oxidizer inlet 128 of the combustion means
124. Lastly, this device comprises a dioxygen outlet 158 for removing the surplus dioxygen
5 from the device.
Figure 2 shows an embodiment of the network that is the subject of the present
invention. This network comprises:
- a device 205 for producing substitute natural gas as described in figure 1;
- a multi-energy management means 210;
10 - a pipeline 21 5 for transporting or distributing gas;
- a means 220 for converting gas into electricity; and
- a generator 225 of direct current.
The multi-energy management means 210 is, for example, a switch that controls:
- the production, by the device 205, and the storage of methane during periods of
15 surplus electricity production; and
- the production of electricity with the stored methane outside these periods.
The periods of surplus electricity production can be predefined in the system or come
from an external information source, such as a server for example.
When the multi-energy management means 210 identifies a surplus electricity
20 production period, this management means 210 commands the production of methane. To
achieve this, the surplus electricity is used by the direct current generator 225 to supply an
electrolysis means, not shown, of the device 205 for producing substitute natural gas. In
parallel, biomass and an oxidizing agent is inserted into the gasifier of the device 205 so as
to produce synthetic gas. The device 205 produces, on output, substitute natural gas stored
25 by overpressure, above the nominal pressure of the pipelines, in a gas distribution pipeline
215. This overpressure is, for example, of the order of 10%.
When the multi-energy management means 210 identifies a period when the
electricity produced is not in surplus, this management means 210 commands the gas-toelectricity
conversion means 220 to produce electricity. The gas-to-electricity conversion
30 means 220 is, for example, a gas thermal power plant using the substitute natural gas stored
by overpressure in the pipeline 215 to produce electricity.
Figure 3 shows logical diagram of steps in a particular embodiment of the method that
is the subject of the present invention. This method comprises:
- a gasification step 305 to produce a synthetic gas, comprising:
35 - a step 310 of inputting biomass;
- a step 315 of inputting an oxidizing agent; and
- a step 320 of outputting synthetic gas comprising carbon monoxide;
- a step 325 of methanating the carbon monoxide output from the gasification step 305,
comprising a step 330 of inputting water and synthetic gas coming from the
gasification step 305, and a step 335 of supplying methane and carbon dioxide;
5 - a step 340 of methanating the carbon dioxide, comprising a step 345 of inputting
water and carbon dioxide coming from the carbon monoxide methanation step 325,
and a step 350 of supplying methane;
- a water electrolysis step 355 to transform water into dioxygen and dihydrogen,
comprising:
10 - a step 370 of supplying electrical power;
- a step 360 of inputting water, and
- a step 365 of outputting dihydrogen used during the carbon dioxide
methanation step 340.
The gasification step 305 is carried out, for example, by utilizing a gasifier, which is a
15 reactor in which the supplied biomass undergoes a thermochemical conversion to form a
synthetic gas ("syngas") containing dihydrogen, carbon monoxide, carbon dioxide, water,
tars, or, in general, any type of carbonized compound.
The gasification step 305 comprises a step 310 of inputting biomass, carried out, for
example, by utilizing a valve supplying biomass to the gasifier. The gasification step 305 also
20 comprises a step 315 of inputting an oxidizing agent, carried out, for example, by utilizing a
valve supplying oxidizing agent to the gasifier. The gasification step 305 further comprises a
step 320 of outputting synthetic gas comprising carbon monoxide, carried out, for example,
by utilizing a pipe connected to the gasifier.
The method comprises a step 325 of methanating the carbon monoxide output from
25 the gasification step 305, carried out, for example, by utilizing a fluidized bed carbon
monoxide methanation means. This carbon monoxide methanation step 325 comprises a
step 330 of inputting water and synthetic gas coming from the gasification step 305, carried
out, for example, by utilizing a valve of the methanation means. This carbon monoxide
methanation step 325 also comprises a step 335 of supplying methane and carbon dioxide +
30 HZO, carried out, for example, by utilizing a pipe on output from the carbon monoxide
methanation means.
The method comprises a carbon dioxide methanation step 340, carried out, for
example, by utilizing a fluidized bed carbon dioxide methanation means. The carbon dioxide
methanation step 340 comprises a step 345 of inputting water and carbon dioxide coming
35 from the carbon monoxide methanation step 325, carried out, for example, by utilizing a
water and carbon dioxide insertion valve of the carbon dioxide methanation means. The
carbon dioxide methanationstep 340 comprises a step 350 of supplying methane, carried
out, for example, by utilizing a pipe on output from the carbon dioxide methanation means.
The method comprises a water electrolysis step 355 to transform water into dioxygen
and dihydrogen, carried out, for example, by utilizing two electrodes immersed in the water
5 and each connected to an opposite pole of a direct-current generator. The electrolysis step
355 comprises a step 360 of inputting water, carried out, for example, by utilizing a water
injection pipe between the two electrodes used during the electrolysis step 355. The
electrical supply step 370 is carried out, for example, by connecting the two electrodes to a
source of direct current. The electrolysis step 355 comprises a step 365 of outputting
10 dihydrogen used during the carbon dioxide methanation step 340, carried out, for example,
by utilizing a pipe.
In some variants, the method 30 also comprises a combustion step, comprising:
- a step of inputting a solid portion resulting from pyrolysis of a non-gasified solid
combustible, also called "char", coming from the gasifier and transported by a heat
15 transfer medium;
- an oxidizer input step;
- a non-gasified char combustion step for heating the heat transfer medium;
- a heat transfer medium output step linked to an input of heat transfer medium for the
gasifier; and
20 - a step of outputting flue-gases.
In some variants, the dihydrogen production step carries out water electrolysis
comprising a step of outputting dioxygen supplying the oxidizer inlet of a combustion means
utilized during the combustion step.
In some variants, the method 30 comprises, between the step of outputting gaseous
25 compound from the gasifier and the step of inputting gaseous compound of the carbon
monoxide methanation step, a step of separating the gases from the solids and/or tars in the
gaseous compound, and a step of transmitting the separated solids andlor tars to the
combustion means utilized during the combustion step.
In some variants, the method 30 comprises a step of recycling a portion of the flue-
30 gas, on output from the combustion step, comprising dioxygen, towards an oxidizer inlet of
the combustion means utilized during the combustion step.
In some variants, the method 30 comprises, downstream from the flue-gas output
step of the combustion step, a carbon dioxide separation step to supply the carbon dioxide
methanation means, utilized by the carbon dioxide methanation step, with carbon dioxide.
In some variants, the method 30 comprises a dihydrogen separation step,
downstream from the carbon monoxide methanation step, to supply the carbon monoxide
methanation means, utilized during the carbon monoxide methanation step, with dihydrogen.
In some variants, the method 30 comprises, downstream from the carbon monoxide
5 methanation step, a carbon dioxide separation step to supply the carbon dioxide methanation
means, utilized during the carbon dioxide methanation step.
In some variants, an output step of the carbon dioxide methanation step is linked to
an output step of the carbon monoxide methanation step.
In some variants, the method 30 comprises, downstream from the carbon monoxide
10 methanation step andlor from the combustion step, a step of condensing the water contained
in vapors and supplying the electrolysis step with water.

CLAIMS
1. Integrated device for producing substitute natural gas, comprising:
- a gasifier (102) configured for producing a gaseous compound from a biomass,
comprising:
- an inlet (104) for biomass;
- an inlet (106) for an oxidizing agent; and
- an outlet (108) for the gaseous compound comprising carbon monoxide;
- a means (110) for methanating the carbon monoxide to produce substitute natural
gas from the gaseous compound output from the gasifier, the carbon monoxide
methanation means (1 10) comprising at least one inlet (1 12) for water and an inlet for
10 the gaseous compound coming from the gasifier;
- a means (114) for methanating carbon dioxide to produce substitute natural gas
comprising at least one inlet (116) for water and an inlet for the carbon dioxide
coming from the carbon monoxide methanation means;
- a means (1 18) for producing dihydrogen from water and electric current comprising:
15 - an electrical power supply;
- an inlet (120) for water and
- an outlet (122) for dihydrogen supplying the means for methanating carbon
dioxide (1 18).
20 2. Device according to claim I, that also comprises a combustion means (124), comprising:
- an inlet (126) for a solid portion resulting from pyrolysis of a non-gasified solid
combustible, also called "char", coming from the gasifier (102) and transported by a
heat transfer medium;
- an oxidizer inlet (128);
25 - a non-gasified char combustion means (130) for heating the heat transfer medium;
- a heat transfer medium outlet (132) linked to a heat transfer medium inlet of the
gasifier (102) and
- an outlet (134) for flue-gases.
30 3. Device according to claim 2, wherein the dihydrogen production means (1 18) is configured
to carry out an electrolysis of water, comprising a dioxygen outlet (136) supplying the oxidizer
inlet (128) of the combustion means.
4. Device according to one of claims 2 or 3, that comprises between the gaseous compound
outlet (108) of the gasifier (102) and the gaseous compound inlet (112) of the carbon
monoxide methanation means (IIO), a separator (138) configured to separate the gases
from the solids andlor tars in the gaseous compound and to transmit the separated solids
5 andlor tars to the combustion means (124).
5. Device according to one of claims 2 to 4, that comprises a means (140) of recycling a
portion of the flue-gas, on output from the combustion means (124), comprising dioxygen,
towards an oxidizer inlet (128) of the combustion means.
10
6. Device according to one of claims 2 to 5, that comprises, downstream from the flue-gas
outlet (134) of the combustion means (124), a carbon dioxide separator (142) configured to
supply the carbon dioxide methanation means (1 14) with carbon dioxide.
15 7. Device according to one of claims 1 to 6, that comprises a dihydrogen separator (144)
downstream from the carbon monoxide methanation means (110) in order to supply said
carbon monoxide methanation means (1 10) with dihydrogen.
8. Device according to one of claims 1 to 7, that comprises downstream from the carbon
20 monoxide methanation. means (IIO), a carbon dioxide separator (146) for supplying the
carbon dioxide methanation means (1 14).
9. Device according to one of claims 1 to 8, wherein an outlet from the carbon dioxide
methanation means (114) is linked to an outlet from the carbon monoxide methanation
25 means (I 10).
10. Device according to one of claims 1 to 9, that comprises, downstream from the carbon
monoxide methanation means (110) andlor from the combustion means (124), a condenser
(148) configured to condense the water contained in vapors and to supply the electrolysis
30 means (1 18) with water.
11. Network, characterized in that it comprises at least one device (205) according to one of
claims 1 to 10.
35 12. Network according to claim 11, that comprises a multi-energy management means (210)
for controlling:
- the production, with at least one device (205) according to one of claims 1 to 10, and
storage of methane during periods of surplus electricity production; and
- the production of electricity with the stored methane outside these periods.
5 13. Network according to claim 12, that comprises gas distribution pipelines (215), the
storage of methane for generating electricity being realized by overpressure above the
nominal pressure of the pipelines.
14. Method for producing substitute natural gas, comprising:
10 - a gasification step (305) for producing a gaseous compound from a biomass,
comprising:
- a step of inputting (310) the biomass;
- a step of inputting (315) an oxidizing agent; and
- a step of outputting (320) the gaseous compound comprising carbon
15 monoxide;
- a step (325) of methanating the carbon monoxide to produce substitute natural gas
from the gaseous compound output from the gasification step, the carbon monoxide
methanation step (325) comprising at least one input step (330) for water and for the
gaseous compound from the gasifier;
20 - a step (340) of methanating carbon dioxide to produce substitute natural gas
comprising at least one input step (345) for water and an input for carbon dioxide
coming from the carbon monoxide methanation step;
- a step (355) of producing dihydrogen from water and electric current comprising:
- a step (370) of supplying electrical power;
25 - a step (360) of inputting water, and
- an output step (365) for dihydrogen used during the carbon dioxide
methanation step.
15. Method according to claim 14, that also comprises a combustion step, comprising:
30 - a step of inputting a solid portion resulting from pyrolysis of a non-gasified solid
combustible, also called "char", coming from the gasifier and transported by a heat
transfer medium;
- an oxidizer input step;
- a non-gasified char combustion step for heating the heat transfer medium;
35 - a heat transfer medium output step linked to an input of heat transfer medium for the
gasifier; and
- a step of outputting flue-gases.
16. Method according to claim 15, wherein the dihydrogen production step carries out water
electrolysis comprising a step of outputting dioxygen supplying the oxidizer inlet of a
5 combustion means utilized during the combustion step.
17. Method according to one of claims 15 or 16, that comprises, between the step of
outputting gaseous compound from the gasifier and the step of inputting gaseous compound
of the carbon monoxide methanation step, a step of separating the gases from the solids
lo andlor tars in the gaseous compound, and a step of transmitting the separated solids andlor
tars to the combustion means utilized during the combustion step.
18. Method according to one of claims 15 to 17, that comprises a step of recycling a poriion
of the flue-gas, on output from the combustion step, comprising dioxygen, lowards an
15 oxidizer inlet of the combustion means utilized during the combustion step.
19. Method according to one of claims 15 to 18, that comprises, downstream-fr6h the.fluegas
output step of the combustion step, a carbon dioxide separation step to supply the
carbon dioxide methanation means, utilized by the carbon dioxide methanation step, with
20 carbon dioxide.
20. Method according to one of claims 14 to 19, that comprises a dihydrogen separation
step, downstream from the carbon monoxide methanation step, to supply the carbon
monoxide methanation means, utilized during the carbon monoxide methanation step, with
25 dihydrogen.
21. Method according to one of claims 14 to 20, that comprises downstream from the carbon
monoxide methanation step, a carbon dioxide separation step to supply the carbon dioxide
methanation means, utilized during the carbon dioxide methanation step.
30
22. Method according to one of claims 14 to 21, wherein an output step of the carbon dioxide
methanation step is linked to an output step of the carbon monoxide methanation step.
23. Method according to one of claims 14 to 22, that comprises, downstream from the carbon
35 monoxide methanation step andlor from the combustion step, a step of condensing the water
contained in vaoors and supplying the electrolysis step with water.