Grid adaption

Abstract

The invention relates to a method for and a plant capable of abruptly shifting the electricity consumption in a Power-to-X methanol production facility. The facility comprising: - An electrolysis unit - A carbon capture unit - A compressor for compressing a stream of H2 and a stream of COX into a syngas for methanol production - A methanol reactor having an operational pressure and comprising a catalyst for production of methanol - A recirculation system for recirculating unreacted H2 and / or COX - A rerouting system for rerouting the stream of COX Where the ratios in changes in the streams are within range 0.2 to 5 for a time period t, where t is between 0.3 and 30 seconds.

Description

[0001] TITLE

[0002] Grid adaption

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a method for fast shifting to a low electricity consumption regime in a Power-to-X methanol plant.

[0005] BACKGROUND OF THE INVENTION

[0006] Recently a new concept called Power-to-X has emerged. In this concept renewable power is used to produce hydrogen in an electrolyzer and then hydrogen is used either directly or processed further to other products like methanol, ammonia or e-natural gas. In the methanol case the hydrogen is then forced to react with carbon to form a combustible liquid fuel, methanol. In figure 1 is illustrated a conceptual Power-to-X methanol plant. Here renewable power is used to electrolyze water into hydrogen and oxygen. The carbon source is a COx stream either freshly captured from e.g a fluegas or it can be freshly released from a carbon captured storage e.g. from liquid COx transported by tankers or similar. At some point the H2stream and the COx stream are combined and compressed in a syngas compressor to a syngas stream ready for methanol reaction in the methanol reactor.

[0007] The increased amount of electricity being provided by wind and solar energy results in fluctuations in the available amount of electricity e.g. if suddenly there is an overcast or the wind stops blowing. To compensate for that there is a market where you can offer services if you are able to reduce your consumption on a very short notice e.g. within a couple of seconds.

[0008] For industries with high electricity consumption, such as the Power-to-X industry, the fee for those services are highly attractive and may contribute a significant competitive advantage. However, it is a challenge for chemical process facilities to regulate their power consumption fast as this often leads to imbalances in the chemical process, which may cause trips of the facility. Starting up a power to x facility from zero is a costly and a lengthy exercise. In the case the facility is involving catalysts a fast reduction in reaction rates or sudden stop of production typically leads to fouling of the catalysts or the reactor. Worst case is that the catalysts have to be replaced or be regenerated before the process can be restarted. This leads to costly downtime and the cost for replacement of catalysts can be significantly larger than the fee given for fast reduction in electricity consumption. One way of solving this issue is to produce an extra amount of H2 and store it for periods with scarce electricity. This, however, has the disadvantage of requiring large storage facilities and it is insufficient in case of prolonged periods requiring a reduced electricity consumption. Hence, there is a need for a method of switching to a low electricity consumption mode fast and without tripping the plant and / or harming the catalysts or the reactor so that production can be increased or even restarted as soon as renewable energy becomes available again and without needing a large storage of H2.

[0009] The inventors haves found a new way to shift a Power-to-X methanol plant into a low electricity consumption regime.

[0010] GB 2603059A describes a carbon dioxide processing system where methanol could be produced. However, the configuration of the plant in GB 2603059 A is not capable of absorbing sudden fluctuations in the supply of the available amount of electricity.

[0011] SUMMARY OF INVENTION

[0012] According to the invention there is provided a method for abruptly shifting the electricity consumption in Power-to-X methanol production facility running in normal operation regime to a low electricity consumption regime, said Power-to-X methanol production facility comprising:

[0013] - An electrolysis unit for generating a stream of H2

[0014] - A carbon capture unit for releasing a stream of COx

[0015] - A compressor for compressing the stream of H2and the stream of COx into a syngas for methanol production

[0016] - A methanol reactor having an operational pressure and comprising a catalyst for converting the syngas for methanol production into methanol A recirculation system for recirculating a portion of unreacted H2 and / or COx to the syngas for methanol production

[0017] A rerouting system for rerouting the stream of COx said method comprising the steps of:

[0018] Providing a stream of H2by electrolyzing water

[0019] Providing a stream of COx by releasing it from a carbon capture unit Compressing the stream of H2and the stream of COx into a syngas for methanol production

[0020] Reacting the syngas for methanol production in the methanol reactor thereby producing methanol

[0021] Reducing electrolysis of water with a rate of reduction of at least 0.5% / s calculated on basis of the stream of H2released during normal operation regime

[0022] Increase rerouting of the stream of COx to the carbon capture unit or to a place up stream of the carbon capture unit with a rate of increase of at least 0.5% / s calculated on basis of the stream of COx released during normal operation regime - where the ratio between an average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t is between 0.2 and 5, wherein the time t is between 0.3 seconds and 30 seconds maintaining the operational pressure in the methanol reactor

[0023] The inventors have found that by balancing the rerouting of COx with the reduction of H2production in the electrolyzer and the thereby resulting stream of H2in combination with a syngas compressor capable of maintaining the pressure in the methanol system, the methanol plant can hastily shift to a low electricity consumption mode. The methanol reactor will not experience an abrupt change due to its own recirculation system. The higher the amount of recirculation in the methanol reactor, the less the methanol reactor will experience the abrupt change in influx of reactants. Preferably the methanol reactor recirculates 70% of the syngas, preferably at least 80%, more preferably 90 % and most preferably at least 95%. In some cases, the methanol reactor recirculates more than 99% of the syngas. The inventors have found that in such methanol reactors, neither the catalysts, nor the reactor are damaged by the sudden shift in reaction mixture production. This is also the case when the change is done in a timeframe of less than seconds. Hence, it is now possible to operate a power-to-X methanol production plant in a way that allows for the facility to offer significant and sudden power consumption reductions as a service to the market.

[0024] A person skilled in the art knows that there are many ways to maintain an operational pressure in a reactor such as a methanol reactor. This can e.g. be done by adjusting the outflow of methanol when the syngas stream is reduced as a consequence of increased rerouting of COx and reduced electrolysis. It can also be done by adjusting the compression of H2, COx and / or the syngas. Usually it is the compression of the syngas that is adjusted or the outflow of methanol or a combination of the two that is used for maintaining the operational pressure.

[0025] The time t over which the ratio between the average rate of reduction and the average rate of increase can be anywhere along the route from normal operation regime to the regime of reduced electricity consumption. Preferable the time t is between 0.4 and 15 seconds and even more preferred is the time t between 0.5 and 10 seconds.

[0026] Preferably the electrolysis of water is reduced with a rate of reduction of at least 1 % / s calculated on basis of normal operation regime, more preferred the rate of reduction is at least 2% / s, and even more preferred the rate of reduction is at least 3% / s and most preferred the rate of reduction is at least 5% / s.

[0027] Preferably the rerouting of the stream of COx to the carbon capture unit or to a place up stream of the carbon capture unit is increased with a rate of increase of at least 1% / s calculated on basis of the stream of COx released during normal operation regime, more preferred the rate of increase is at least 2% / s, and even more preferred the increase is at least 3% / s and most preferred the rate of increase is at least 5% / s.

[0028] The inventors have found that by applying the main part of the electricity reduction to the electrolyzer and balancing that by rerouting of COx in combination with the usage of a methanol reactor with high recirculation of syngas it is possible to operate the plant so that it can accommodate e.g. Fast Frequency Reserve (FFR) and Frequency Containment Reserve (FCR-D) as defined by Svenska Kraftnat and others, or other needs of fast changing of electricity demand.

[0029] The carbon capture unit can either be a unit that directly captures COx from e.g. fluegas or other industrial processes or it can be a carbon capture unit that releases COx captured elsewhere e.g. COx being transported to the unit via shipping or the like. Preferably the carbon capture unit is capturing COx itself i.e. capturing COx on site and releasing a stream of COx into the plant. In a preferred embodiment the Power-to-X methanol plant comprises both a unit that directly captures COx and a carbon capture unit that releases COx captured elsewhere. It can also consist of one and the same unit that capture COx to both the Power-to-X methanol plant and releases it elsewhere. The advantage of such a plant is that the source of direct capture of COx will not experience any changes during FFR or FCR-D.

[0030] COx can be carbon monoxide, carbon dioxide and mixtures thereof. In a preferred embodiment COx is carbon dioxide.

[0031] With normal operation is understood the production and releases under conditions where the plant is operating under no restrictions from the electricity suppliers i.e. in the planned operational mode.

[0032] The invention further relates to a Power-to-X methanol plant adapted to carry out the method according to the invention, said Power-to-X methanol plant comprises

[0033] - An electrolysis unit for generating a stream of H2

[0034] - A carbon capture unit for releasing a stream of COx

[0035] - A compressor for compressing the stream of H2 and the stream of COx into a syngas for methanol production

[0036] - A methanol reactor having an operational pressure and comprising a catalyst for converting the syngas for methanol production into methanol

[0037] - A recirculation system for recirculating a portion of unreacted H2 and / or COx to the syngas for methanol production

[0038] - A rerouting system for rerouting the steam of COx

[0039] Means for maintaining the operational pressure in the methanol reactor

[0040] In a further aspect the invention relates to a Power-to-X methanol plant adapted to carry out the method according to the invention, the Power-to-X methanol plant comprises

[0041] - An electrolysis unit for generating a stream of H2

[0042] - A carbon capture unit for releasing a stream of COx

[0043] - A compressor for compressing the stream of H2 and the stream of COx into a syngas for methanol production

[0044] - A methanol reactor having an operational pressure and comprising a catalyst for converting the syngas for methanol production into methanol

[0045] - A recirculation system for recirculating a portion of unreacted H2 and / or COx to the syngas for methanol production

[0046] Means for maintaining the operational pressure in the methanol reactor, wherein the Power-to-X methanol plant (1) further comprises: A rerouting system (18) for rerouting the stream of COx to the front end (19) of the carbon capture unit (3) or to a place up stream of the carbon capture unit.

[0047] The rerouting of the stream of COx to upstream of the carbon capture unit has the advantage that the carbon capture unit is kept running in a form for idle mode without the carbon capture unit is experiencing any change. Thereby a matching response to a sudden change in the H2from electrolysis is much easier to achieve. In a preferred embodiment the place upstream of the carbon capture unit is a flue stack e.g. the flue stack from which the COx initially was captured.

[0048] The place upstream of the carbon capture unit can also be in the carbon capture unit if the piping is connected before the actual capturing process.

[0049] The means for maintaining the operational pressure in the methanol reactor is well known to a person skilled in the art. It can be the compressor for compressing the stream of H2and the stream of COx into a syngas that is adjusted, it can be by a valve, back pressure system or the like, that regulates the outflow of methanol from the reactor and thereby maintains the operational pressure.

[0050] In a preferred embodiment the Power-to-X methanol plant comprises both a unit that directly captures COx and a carbon capture unit that releases COx captured elsewhere. The advantage of such a plant is that the source of COx neither will experience any changes during FFR or FCR-D.

[0051] DETAILED DESCRIPTION

[0052] The invention will now be described in further details which shall not be considered to limit the invention in any way.

[0053] As explained the inventors have found that by balancing the rerouting of COx with the reduction of H2production in the electrolyzer and the thereby resulting stream of H2in combination with a syngas compressor capable of maintaining the pressure in the methanol system or in combination with other means to maintaining the pressure in the methanol reactor, the methanol plant can hastily shift to a low electricity consumption mode. The balance between the increase in rerouting of COx with the reduction of H2 production is expressed with the following ratio. average rate of reduction

[0054] Ratio = - - - , meassured over time t avarage rate of increase

[0055] Where the ratio is between 0.2 and 5 preferable between 0.5 and 2. The time t can be any time interval along the path from normal operation regime to low electricity consumption regime and t is between 0.3 seconds and 30 seconds. It is not critical that t covers the entire path from normal operation regime to low electricity consumption regime, the ratio only has to be fulfilled for at least a part of the path.

[0056] For some methanol reactors it can be desirable with a safety regulation to secure that either COx or H2 does not reach the reactor in overstoichimetric ratios. Hence is can be desirable to start the regulation of one of the components shortly before the other and / or to continue regulation for a longer period with a lower rate. Alternatively an initial fast change in one of the components can be followed by the balanced change. According to the invention it is only required that there is an interval of time t, where the ratio is fulfilled.

[0057] For other methanol reactors it is desired that the ratio is fulfilled not only over the time t but also when looking at narrower intervals of t. In a preferred embodiment the time t is divided into at least 5 intervals of equal length where in each of the at least 5 intervals ratio between the average of the rate of reduction, and the average of the rate of increase is between 0.2 and 5. In case the average rate of increase is 0 in an interval the interval is combined with a neighboring interval.

[0058] In a preferred way of carrying out the method the time t starts when from the point in time where both the rate of increase and the rate of reduction is above 0.5% / s and lasts until either the rate of increase or the rate of reduction or both comes below 0.5% / s. Preferably t starts when the rates begin to change and lasts for 30 seconds or until the regime of low electricity consumption regime is reached whichever comes first.

[0059] When reduction of electrolysis of water is balanced with rerouting of COx and at the methanol reactor with high recirculation is used it is possible to do e.g. FFR and FCR-D with the Power-to-X plant. Preferably this balance is kept for a substantial part of the path from normal operation to a low electricity consumption regime and not only as an average measured over the time t. Hence in a preferred version of FFR and FCR-D the ratio between the average of the rate of reduction, and the average of the rate of increase is between 0.2 and 5 for at least 5 intervals of equal length of t. In case the average rate of increase is 0 in an interval the interval is combined with a neighboring interval

[0060] In one embodiment, when implementing FFR the electrolysis of water is reduced with a rate of reduction of at least 1% / s calculated on basis of normal operation regime, preferably with a rate of reduction of at least 5% / s and more preferred with a rate of reduction of at least 7% / s.

[0061] In one embodiment, when implementing FFR the rerouting of the stream of COx to the carbon capture unit or to a place up stream of the carbon capture unit is increased with a rate of increase of at least 1% / s calculated on basis of the stream of COx released during normal operation regime, preferably with a rate of increase of at least 5% / s and more preferred with a rate of increase of at least 7% / s.

[0062] Preferably, when implementing FFR, the ratio between an average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t is between 0.5 and 2; and t is between 0.4 and 2 seconds. Preferably t starts when FFR is started.

[0063] In one embodiment, when implementing FCR-D the electrolysis of water is reduced with a rate of reduction of at least 3% / s calculated on basis of normal operation regime, preferably with a rate of reduction of at least 4% / s and more preferred with a rate of reduction of at least 5% / s.

[0064] In one embodiment, when implementing FCR-D the rerouting of the stream of COx to the carbon capture unit or to a place up stream of the carbon capture unit is increased with a rate of increase of at least 3% / s calculated on basis of the stream of COx released during normal operation regime, preferably with a rate of increase of at least 5% / s and more preferred with a rate of increase of at least 7% / s.

[0065] Preferably, when implementing FCR-D, the ratio between an average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t is between 0.5 and 2; and t is between 5 and 30 seconds. Preferably t starts when FCR- D is started.

[0066] It is particularly preferred that when implementing FCR-D the time t is divided into at least 10 intervals of equal length where in each of the at least 10 intervals ratio between the average of the rate of reduction, and the average of the rate of increase is between 0.5 and 2. In case the average rate of increase is 0 in an interval the interval is combined with a neighboring interval

[0067] Preferably when running FFR the reduction of electrolysis is completed after no more than 3 seconds, preferably no more than 2 seconds and most preferred after no more than 1 second. The Power-to-X plant is then kept at the reduced level reached after that time and remains there until normal operation is resumed.

[0068] Preferably when running FCR-D in the reduction of electrolysis is completed in steps with different reduction rates,. Preferably the reduction of electrolysis is implemented by reducing the electrolysis with a first and higher rates of reduction followed by a second and lower rate of reduction.

[0069] In a preferred embodiment the FCR-D is implemented by reducing electrolysis with a rate of reduction of at least 3% / s for at least 4 seconds followed by rate of reduction of at least 0.5% / s for at least 10 seconds until the total reduction is at least 40%, preferably at least 50%.

[0070] In one embodiment the reduction of electrolysis is reduced with a rate of reduction of 5% / s for 5 seconds followed by a rate of reduction of 1% / s in 25 seconds, thereby reaching a 50% reduction in 30 seconds. The Power-to-X plant is then kept at the reduced level reached after that time and remains there until normal operation is resumed.

[0071] LIST OF FIGURES

[0072] Fig. 1 is a schematic illustration of a Power-to X methanol plant

[0073] Fig. 2 is a schematic illustration of a Power-to X methanol plant where the method can implemented when FRR or FCR-D is requested

[0074] Fig. 3 is an illustration of a path from normal operation regime to a low electricity consumption regime

[0075] DESCRIPTION OF DRAWINGS

[0076] Figure 1 illustrates a conceptual overview of a Power-to-X methanol plant where renewable power (ren. Power) is used to run an electrolyzer so as to generate a H2stream. From a COx source COx is either freshly captured or captured one place and released in the plant so as to create a COx stream. The H2stream and the COx stream are combined into one stream and compressed in a syngas compressor (compr) to create a compressed syngas that is lead into a reactor that converts it into methanol. The present invention addresses the steps prior to the syngas compressor so as to improve the operation of Power-to-X methanol plants.

[0077] Figure 2 illustrates a part of a Power-to-X plant 1 capable of carrying out the method of the invention. The Power-to-X plant 1 comprises an electrolyzer 2 which uses renewable power such as wind power to electrolyze water into hydrogen H2and oxygen O2. The oxygen is released to the atmosphere or sold elsewhere whereas a H2stream is collected and turned into a H2stream, said H2stream contains a lot of moisture because it originates from the electrolysis of water. The power-to-X plant 1 further comprises a carbon capture unit 3. Preferably the COx is carbon dioxide but the invention will work equally well with carbon monoxide or mixtures of carbon monoxide and carbon dioxide. In the plant of figure 2 COx is captured on site. In the plant there is also a syngas compressor 4 with a syngas compressor inlet 5 and a syngas compressor outlet 6. In the syngas compressor the syngas is conditioned and compressed to conditions as defined by the methanol reactor 7. The syngas compressor outlet 6 is connected to the methanol reactor 7 in which the syngas reacts and forms methanol. Methanol reactors 7 are known in the field. From the electrolyzer the H2stream is conveyed to a H2compressor inlet 9 and from there into the H2compressor 8. In the H2compressor 8 the H2stream is compressed and during that compression moisture condensate and is removed from the stream. The result is a compressed H2stream leaving the H2compressor 8 via the H2compressor outlet 10. The Power-to-X plant 1 further comprises a guard reactor 16. The reactants for the guard reactor 16 can come from the original or partly be supplied from elsewhere as is known in the art. The guard reactor 16 is positioned upstream of the methanol reactor 7 and protects the methanol reactor from impurities that might the present in the reactant streams, such as impurities in the COx stream. The guard reactor can get its reactants from various places which is know the person skilled in the art

[0078] From the carbon capture unit 3 the COx stream is conveyed to a COx compressor 11 having a COx compressor inlet 12 and a COx compressor outlet 13. Before the COx compressor inlet 12 there is a branching point 17 where a COXrerouting piping 18 is connected to the front end 19 of the carbon capture unit 3. The exact position of the COXrerouting pipping 18 is not important. The branching point 17 can be between the carbon capture unit 3 and the COx compressor or it can be after the COx compressor and other positions will also work. The same is true for the front end 19 of the carbon capture unit 3 whereto the rerouting stream of COXstream is reconnected with the piping leading to the carbon capture unit 3 or directed to the flue gas stack. The purpose of the COx rerouting piping is that the forward flow of COx to the guard reactor 16 or the methanol reactor 7 is decreased and doing it with recirculation results in that methanol reactor 7 will not experience dramatic changes even when there is an abrupt change in supply. Further the plant is ready for a fast return to normal operation. In the COx compressor COx is compressed so that moisture and carbon capture solvent is condensed. The condensed carbon capture solvent and at least a part of the condensed moisture is returned via a recirculation piping 14 to the carbon capture unit 3 where is can be used directly. Via the COx compressor outlet a stream of compressed COx is combined with the main stream of compressed H2. The steams are combined prior to reaching the syngas compressor inlet 5. With the term syngas compressor inlet is understood that the streams also can be combined inside the syngas compressor with the same result.

[0079] When a Fast Frequency Reserve or a Frequency Containment Reserve Disturbance is initiated as described in the examples a part of the COx stream and / or the compressed COx stream is returned to an upfront position of the carbon capture unit 3 via the COx rerouting piping 18. It is known by a person skilled in the art how to regulate the flow between rerouting and forward flow.

[0080] Figure 3 is an illustration of a fast reduction in the electricity consumption in a power-to-X methanol plant. The figure is only for illustrative purposes. On the Y-axis is the percentage relative to normal operation regime shown while on the X axis the time is shown in seconds. When the abrupt change is implemented it can be seen that the electrolysis is reduced from 100% to 50% with a faster reduction in the beginning. Simultaneously the rerouting is increased from 0% to 50% also with a faster change in the beginning. The rate of reduction and the rate of increase is the tangent to the curves respectively. Further it can be seen that there is a little delay in the response in form of the out put of methanol. This is illustrated by the little shift in the methanol production curve to the right. The exact delay is plant specific. In the illustration the time t is set from 4 seconds to 14 seconds but it could have been on numerous points along the curves. Further it can be seen that t is divided into 5 intervals (1 , 2, 3, 4 and 5) of equal size. Over the time interval t the electrolysis is reduced from 80% to 66% over the 10 seconds which gives an average rate of reduction of 1.4% / s. Over the same time interval t the rerouting is increased from 20% to 34% which gives an average rate of increase of 1.4% / s; and thereby a ratio between the average rate of reduction and the average rate of increase of 1. If the same is applied to each of the 5 intervals the following is illustrated.

[0081] Interval 1 :

[0082] Rate of reduction = (80%-74%) / 2s = 3% / s

[0083] Rate of increase = (26%-20%) / 2s = 3% / s

[0084] Ratio = (3% / s) / (3% / s) = 1

[0085] Interval 2:

[0086] Rate of reduction = (74%-72%) / 2s = 1% / s

[0087] Rate of increase = (28%-26%) / 2s = 1% / s

[0088] Ratio = (1 % / s) / (1 % / s) = 1

[0089] Interval 3:

[0090] Rate of reduction = (72%-70%) / 2s = 1% / s

[0091] Rate of increase = (30%-28%) / 2s = 1% / s

[0092] Ratio = (1 % / s) / (1 % / s) = 1

[0093] Interval 4: Rate of reduction = (70%-68%) / 2s = 1 % / s

[0094] Rate of increase = (32%-30%) / 2s = 1 % / s

[0095] Ratio = (1% / s) / (1 % / s) = 1

[0096] Interval 5:

[0097] Rate of reduction = (68%-66%) / 2s = 1 % / s

[0098] Rate of increase = (34%-32%) / 2s = 1 % / s

[0099] Ratio = (1 % / s) / (1 % / s) = 1

[0100] EXAMPLES

[0101] Example 1 implementation of Fast Frequency Reserve (FFR) in a Power-to-X methanol plant with direct capturing of CO2 said plant having a 140 MW electrolyzer.

[0102] The plant has a capacity to make FFR with up to 9.8 MW in 0.7 seconds, and this is activated. The production of H2 via electrolysis in the electrolyzer is reduced with 10% / s until the total reduction of 9.8 MW is reached which means that there is a rate of reduction of 10% / s. This takes 0.7 s and corresponds to a reduction of 7% of the H2. Simultaneously, the carbon capturing unit go from zero rerouting to reroute 7% of the recovered CO2 stream to the front end of the carbon capturing unit. The rerouting is implemented within 1 second corresponding to a rerouting increase with ~7% / s (a rate of increase of 7% / s) and controlled to reach a ratio as close to 1 as possible. After the reduction in H2production and the rerouting of CO2the plant is kept at that level for as long as the activation of FFR is requested. Such activations can be repeated after 15 minutes.

[0103] The result of such an activation is that the production of methanol is reduced with 7% for as long as the FFR activation takes place.

[0104] If t is set to 0.7 s the average rate of reduction is 10% / s and the average rate of increase in rerouting is 7% / s which results in a ratio between the average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t of 1.4 (10% / s divided with 7% / s).

[0105] The same is true if t is set to 0.4 s or 0.5 s.

[0106] Further the example shows that there is balance along the path from normal operation regime to the low electricity consumption regime. If t is 0.6 s and this is divided into 6 intervals of equal length then each interval is 0.1 s. In the table below the rate of reduction and the rate of increase is shown for each interval and the ratio is calculated.

[0107] An alternative path that will lead to the same result but not being quite as balanced along the path is shown in the table below.

[0108] For completion the following 0.4 seconds are as follows, where it is seen that the ratios no longer are with in limits in all of the intervals

[0109] The result after 1 second is that the hydrogen production is reduced with 7% (0,7 s times 10 % / s) and the rerouting is increased with 7% (1 s times 7% / s) so the plant from there runs at 93% of the capacity during normal operation.

[0110] Example 2 Implementation of Frequency Containment Reserve Disturbance (FCR-D) in a Power-to-X methanol plant with direct capturing of CO2 said plant having a 140 MW electrolyzer.

[0111] The plant is requested to reduce the power consumption with 70 MW. The production of H2via electrolysis in the electrolyzer is reduced with 5% / s (rate of reduction)until the total reduction of 35 MW is reached and this is followed by further reduction with 1 % / s until the further reduction of 35 MW is reached. This gives a total reduction of 70 MW in power consumption. Simultaneously with the reduction in H2production the carbon capturing unit rerouting system reroutes 50% of the recovered CO2calculated on basis of the CO2stream leaving the carbon capturing unit during normal operation to the front end of the carbon capturing unit or to the flue gas stack. The rerouting is implemented according to the hydrogen production reduction i.e. with 5% / s (rate of increase) for the first 5 seconds follow by 1 % / s for additional 25 seconds.

[0112] In this way of implementing FCR-D the ratio ratio between an average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t is close to 1 the whole time.

[0113] If t is 10 s, and it is divided into 10 intervals of equal length then each interval is 1 s; the rates are as illustrated in the table below:

[0114] The ratio average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t where t is 10 s is the calculated as follows:

[0115] (5 + 5 + 5 + 5 + 5 + 1 + 1 + 1 + 1 + l) / 10 3 ratio = - - — -

[0116] (5 + 5 + 5 + 5 + 5 + 1 + 1 + 1 + 1 + l) / 10 3= 1The methanol production is reduced to correspond to the production of H2.

[0117] With this scheme the plant is able to return to normal production after the disturbance has ended. The plant can be restored to normal production without having to change or regenerate the catalysts.

[0118] A less balanced but still fully functional way of implementing FRC-D and also having a ratio of 1 over the first 10 seconds is illustrated below:

[0119] The ratio average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t where t is 10 s is then calculated as follows:

[0120] Though being less balanced, this way of implementing FCR-D has the advantage that it is secured that COx does not appear in overstoichiometric ratio in the reactor. If it was desired to have it the other way around the rate of reduction would have been faster in the initial phase.

[0121] REFERENCES

[0122] 1 Power to X plant

[0123] 2 electrolyzer

[0124] 3 carbon capture unit

[0125] 4 syngas compressor

[0126] 5 syngas compressor inlet

[0127] 6 syngas compressor outlet

[0128] 7 methanol reactor

[0129] 8 H2 compressor

[0130] 9 H2 compressor inlet

[0131] 10 H2compressor outlet

[0132] 11 COx compressor

[0133] 12 COx compressor inlet

[0134] 13 COx compressor outlet

[0135] 14 rerouting pipping

[0136] 16 guard reactor

[0137] 17 branching point 18 COx rerouting piping

[0138] 19 front end of the carbon capture unit

Claims

CLAIMS1 . A method for abruptly shifting the electricity consumption in Power-to-X methanol production facility (1) running in normal operation regime to a low electricity consumption regime, said the Power-to-X methanol production facility (1) comprising:- An electrolysis unit (2) for generating a stream of H2- A carbon capture unit (3) for releasing a stream of COx- A compressor (4) for compressing the stream of H2and the stream of COx into a syngas for methanol production- A methanol reactor (7) having an operational pressure and comprising a catalyst for converting the syngas for methanol production into methanol- A recirculation system for recirculating a portion of unreacted H2and / or COx to the syngas for methanol production- A rerouting system (18) for rerouting the stream of COx said method comprising the steps ofProviding a stream of H2by electrolyzing waterProviding a stream of COx by releasing it from a carbon capture unit (3)Compressing the stream of H2and the steam of COx into a syngas for methanol productionReacting the syngas for methanol production in the methanol reactor (7) thereby producing methanolReducing electrolysis of water with a rate of reduction of at least 0.5% / s calculated on basis of the stream of H2released during normal operation regimeIncrease rerouting of the stream of COx to the carbon capture unit (3) or to a place up stream of the carbon capture unit (3) with a rate of increase of at least 0.5% / s calculated on basis of the stream of COx released during normal operation regime- where the ratio between an average of the rate of reduction measured over a time t, and an average of the rate of increase over the time t is between 0.2 and 5, wherein the time t is between 0.3 seconds and 30 seconds maintaining the operational pressure in the methanol reactor (7).

2. A method according to claim 1 , wherein the COx stream is generated from freshly on site captured COx.

3. A method according to claim 1 or 2, wherein the time t is divided into at least 5intervals of equal length where in each of the at least 5 intervals ratio between the average of the rate of reduction, and the average of the rate of increase is between 0.2 and 5.

4. A method according to claim 1 or 2, wherein the time t is divided into at least 5 intervals of equal length where in each of the at least 5 intervals ratio between the average of the rate of reduction, and the average of the rate of increase is between 0.5 and 2.

5. A method according to any one of the preceding claims wherein the rate of reduction for a first period is larger than the rate of increase.

6. A method according to any one of the preceding claims wherein the rate of reduction is at least 3% / s.

7. A method according to any one of the preceding claims wherein the rate of increase is at least 3% / s.

8. A method according to any one of the preceding claims wherein the rate of reduction has a first regime with a first and higher rate of reduction followed by a second regime with a second and lower rate of reduction.

9. A Power-to-X methanol plant (1) adapted to carry out the method according any one of claims 1-8, said Power-to-X methanol plant (1) comprises- An electrolysis unit (2) for generating a stream of H2- A carbon capture unit (3) for releasing a stream of COx- A compressor (4) for compressing the stream of H2and the stream of COx into a syngas for methanol production- A methanol reactor (7) having an operational pressure and comprising a catalyst for converting the syngas for methanol production into methanol- A recirculation system for recirculating a portion of unreacted H2and / or COx to the syngas for methanol productionMeans for maintaining the operational pressure in the methanol reactor (7),C H A R A C T E R I Z E D in that the Power-to-X methanol plant (1) further comprises:- A rerouting system (18) for rerouting the stream of COx to the front end (19) of the carbon capture unit (3) or to a place up stream of the carbon capture unit (3).

10. A Power-to-X methanol plant (1) according to claim 9, wherein the place up stream of the carbon capture unit (3) is a flue gas stack.

11. Use of the method according to any one of claims 1- 8 for FFR.

12. Use of the method according to any one of claims 1-8 for FCR-D.

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