Waste processing system and method

Abstract

Disclosed herein is a syngas production system for producing syngas from fish waste, the system comprising: a gasifier; and a feedstock input that is configured to supply a feedstock comprising fish waste to the gasifier; wherein the gasifier is configured to generate syngas by performing a gasification process on the received feedstock.

Description

[0001] WASTE PROCESSING SYSTEM AND METHOD

[0002] Field of the invention

[0003] The present invention relates to the processing of waste products. Embodiments include processing fish waste to generate syngas. This may be integrated with a further processes such that bio-fuel / bio- oil, hydrogen, ethanol or other products are generated in dependence on the syngas.

[0004] Background to the invention

[0005] A substantial proportion of the world’s population are heavily reliant on liquid hydrocarbon fuels, that have been obtained from crude oil, for transportation and other uses. A problem with the use of such non-renewable energy sources is that they substantially increase greenhouse gas emissions. There is therefore a lot of interest in the generation and use of bio-fuels / bio-oils that are not derived from crude oil.

[0006] There is a general need to improve techniques for producing bio-fuels / bio-oils, as well as other products, without substantially increasing greenhouse gas emissions.

[0007] Summary of the invention

[0008] Aspects of the invention are set out in the appended independent claims. Optional aspects are set out in the dependent claims.

[0009] Brief description of the drawings

[0010] Figure 1 schematically shows an oil / fuel generation system according to a first embodiment;

[0011] Figure 2 schematically shows a hydrogen generation system according to a second embodiment; and

[0012] Figure 3 schematically shows an ethanol generation system according to a third embodiment.

[0013] Detailed description of the invention

[0014] Embodiments concern the generation of bio-oils, including bio-fuels and other useful products, from waste materials. In particular, embodiments include the generation of syngas from fish waste. Due to fish waste being a carbon source, the generated syngas may be referred to as bio syngas. The syngas may be used to generate bio-fuels / bio-oils, such as aviation fuel, green hydrogen and / or ethanol. The processes for generating fuel, and other end products, may be integrated with the processes for generating syngas.

[0015] Embodiments of the present invention use steam gasification to convert waste materials into syngas. A preferred waste material is fish waste. This is a waste product from fish farms that may be obtained at low, or no, cost. Advantages of fish waste also include its low level of impurities, its abundance and its similar calorific value to woody biomass. Embodiments include using the Fischer-Tropsch (FT) process to generate fuels, such as aviation fuel, in dependence on the syngas. Embodiments also include using a sorption enhanced water gas shift process to produce hydrogen, that may be referred to as green hydrogen. Embodiments also include performing bioconversion on hydrogen rich syngas to produce ethanol.

[0016] Figure 1 schematically shows an oil / fiiel generation system according to a first embodiment. The oil / fuel generation system comprises a syngas generation system 100 and a Fischer-Tropsch (FT) system. The syngas generation system 100 receives a feedstock 101 and generates a syngas supply 105 in dependence on the received feedstock 101. The FT system receives the syngas supply 105 from the syngas generation system 100 and generates fuel in dependence on the syngas supply 105.

[0017] The feedstock 101 may comprise fish waste, that may alternatively be referred to as fish sludge. The fish waste comprises waste products from a fish farm, such as sludge from fish farming, fish silage and / or fish manure. The fish waste may be filtered to remove any dead fish. In particular, embodiments include the fish waste comprising dewatered fish faeces and residual fish feed. Embodiments also include the fish waste substantially consisting of dewatered fish faeces and residual fish feed.

[0018] Table 1 shows the composition of typical dry fish waste according to embodiments. The compositions are shown with their dry weights (dw). The results in Table 1 were obtained following an analysis of a fish waste sample. The actual composition of the fish waste is expected to vary from what is shown in Figure 1 in dependence on a number of factors, such as the conditions in the fish farm, the type of fish and the constituents of the fish feed.

[0019] The feedstock 101 may be dried before it is supplied to the syngas generation system 100.

[0020] Accordingly, when the feedstock 101 is fish waste, the syngas generation system 100 may receive dried fish waste.

[0021] The syngas generation system 100 may comprise a gasifier 102 and a combustor 126. The gasifier 102 may receive the feedstock 101 and may also receive steam from a steam supply 123. The gasifier 102 may perform a gasification process so as to generate syngas. The gasification process may be a steam gasification process.

[0022] The gasifier 102 is preferably a dual bubbling fluidized bed (DFB) reactor. The DFB reactor may be based on that implemented at TU Wein as published in S. Koppatz, C. Pfeifer, R. Rauch, H. Hofbauer, T. Marquard-Moellenstedt, M. Specht, Fuel Processing Technology 2009, 90, 914-921. A catalyst, or catalysts, may be used in the gasifier 102. The catalyst(s) may improve the efficiency of the gasification process and / or convert any formed tar by the gasification process to hydrocarbons. Alternatively, the tar conversion catalyst may be used in a separate downstream reactor.

[0023] The gasification process may be performed on the contents on the gasifier 102 at a temperature in the range of about 550°C to about 800°C, and preferably about 650°C to about 700°C. The gasification process may be performed at a pressure of about 1-5 bar. An advantage of the gasification process being performed below about 800°C is that any Ca present will remain in a solid phase and will mainly be attached to char. This will reduce the impurities in the generated syngas.

[0024] The contents of the gasifier 102 may include the received feedstock 101 and steam from the steam supply 123. The contents of the gasifier 102 may also include a reactive material. The reactive material may comprise a sorbent for removing carbon dioxide and preferably also impurities from the syngas product of the gasification process. The reactive material may be multi-functional to the extent that it both removes impurities and reduces the carbon dioxide concentration of the syngas. It also has the effect of increasing the hydrogen (H2) to carbon monoxide (CO) ratio in the syngas without excess steam being added. Advantageously, this reduces costs and the generated syngas may be efficiently used in a Co-based FT process.

[0025] Preferably, the reactive material comprises a mixture of CaO (e.g. limestone) and red mud (see https: / / en.wikipedia.org / wiki / Red mud. as viewed on 5thApril 2024). The reactive material may also include the reaction product of CaO with CO2, which is CaCO ,. The reactive material may also include the reaction products of the red mud. The specific reaction products of the red mud depend on the specific composition of the feedstock 101 and red mud. The reactive material preferably is in the form of solid spherical pellets. The high surface area of a spherical pellet provides a large heat flux. The reactive material may comprise pellets that comprise CaO and separate pellets that comprise red mud. The pellets of the reactive material that comprise CaO may be modified to also include, for example, a binding material so as to improve their longevity and / or performance. Both red mud and CaO may serve as efficient catalysts for high temperature water gas shift (WGS) reactions, and the CaO may also capture CO2 in-situ. The red mud may comprise reducible Fe oxides that are catalysts for chemical looping reforming. The red mud may comprise FC2O3 that is a catalyst for the cracking of tar and NH3. Mixed oxides containing MnO may be impregnated to red mud and this may selectively remove the impurities such as N and alkaline (Na and K), thereby makes gas cleaning simpler.

[0026] The gasifier 102 comprises an outlet through which the syngas generated in the gasifier 102 is output as a syngas stream 103. The syngas stream may comprise: H2 / CO ratiodry > 2.0

[0027] CH4 < 2vol%dry

[0028] CO2 < 2 VOl%dry tar < 0.5 gm / m3

[0029] The H2:C0 ratiodry may be is greater than 2.0 and is preferably 2. 1 or greater. The light hydrocarbon content, which may have molecules with 4 carbon atoms or less, may be less than 2 vol%dry.

[0030] The heat for the gasification process may be provided by the combustor 126. The combustor 126 may receive an internal supply of fuel from the gasifier 102, an external supply of fuel as fuel stream 119, and an air stream 124. The internal supply of fuel may be a product of the gasification process of the feedstock 100, such as charcoal. The external supply of fuel may be any fuel source but is preferably a product of the later described FT process. The fuel in the combustor 126 may be combusted with the air in the combustor 126. The combustion process may generate an operating temperature in the combustor 126 in the range of about 600°C to about 850°C, and preferably about 700°C to about 750°C. The combustion process may be performed at a pressure of about 1-5 bar.

[0031] The contents of the combustor 126 may also include the above-described reactive material. Heat from the combustion process may regenerate some, or all, of the CaCO , in the reactive material to form CaO and CO2.

[0032] The reactive material may be moved in a cycle between the gasifier 102 and the combustor 126. The CaO in the reactive material is a sorbent that may capture CO2 in the gasifier 102 by reacting to form CaCOs. The CaCOs may then be transferred to the combustor 126 where it reacts to release CO2 and re-form CaO. The CaO may then be supplied back to the gasifier 102 and re-used to capture CO2. Embodiments include a number of techniques for moving the reactive material in a cycle between the gasifier 102 and the combustor 126. For example, lock hoppers or loop seals may be used to transfer the reactive material from the gasifier 102 to the combustor 126, and from the combustor 126 back to the gasifier 102, without substantial gas transfer occurring between the gasifier 102 and the combustor 126. A system for looping a solid sorbent between a gas capture system and sorbent regeneration system is disclosed in at least the published International patent application WO / 2020 / 165440, the entire contents of which are incorporated herein by reference.

[0033] The cycling of the reactive material between the gasifier 102 and the combustor 126 may additionally be used to transfer heat from the combustor 126 to the gasifier 102. That is to say, the CaO and / or red mud, and / or the reaction products of the CaO and / or red mud, may be a heat transfer material between the combustor 126 and the gasifier 102.

[0034] The combustor 126 may comprise a first outlet for a first output stream of gaseous products. The first output stream may mainly comprise CO2 and N2. The CO2 and N2 may be separated from each other and the CO2 compressed and transported for storage and / or use.

[0035] The combustor 126 may also comprise a second outlet 125 for a second output stream of solid products, such as the reaction products between the red mud and the feedstock 101. The second output stream may comprise ash that is the resulting product from burning charcoal.

[0036] The syngas supply 105 is an output of syngas from the syngas generation system 100. The syngas may be used on site for a number of different purposes, or transported away for use elsewhere or storage.

[0037] There may be a return syngas stream 106 that is a flow of some of the syngas stream 103 output from the gasifier 102 back to the combustor 126 and / or gasifier 102. This provides fluidisation in the combustor 126 and / or gasifier 102.

[0038] In a preferred embodiment, syngas generation system 100 is integrated with a Fischer-Tropsch (FT) system. The syngas supply 105 may be the source of syngas used in the FT system. The syngas generation system 100 may receive and use fuel and / or heat from the FT system.

[0039] The FT system may comprise a syngas cleaning system 107, a FT reactor 114 and a fuel separation system 116.

[0040] The syngas cleaning system 107 may be arranged to receive and clean the syngas supply 105. The syngas cleaning system 107 may be any of a number of known designs of syngas cleaning system. The syngas cleaning system 107 may comprise a wet scrubber. The syngas supply 105 may be washed with a cleaning liquid, that is preferably water, as it flows through the wet scrubber with wet scrubber operating below 100°C. The output flow 108 of cleaning liquid from the wet scrubber may be cooled in a heat exchanger 109. A pump 111 may then pump the cleaning liquid back to an inlet of the wet scrubber so that it may be used to wash the syngas flow again. If water is sufficient for cleaning the syngas, then this is the preferred cleaning liquid because it is cheap and widely available. If cleaning the syngas requires a stronger solvent than water, then other chemicals may additionally, or alternatively, be used in the syngas cleaning system 107. The cleaned syngas stream 110 is preferably ultra-pure. The cleaned syngas stream 110 may flow out of the wet scrubber and to a compressor 112. The compressor 112 may compress the received syngas stream and output a compressed syngas stream 113 for supplying to the FT reactor 114. The pressure of the compressed syngas stream 113 may be about 15 to 25 bar, and preferably about 20 bar. The FT: CO ratiodry of the compressed syngas stream 113 may be greater than 2.0.

[0041] The FT reactor 114 receives the compressed syngas stream 113 and performs an FT process to generate fuel. The FT reactor 114 may be any of a number of known designs of FT reactor. The FT process for generating fuel in dependence on syngas was developed a long time ago and suitable FT reactors are commercially available. The FT reactor may comprise a plurality of reactors that perform FT processes.

[0042] The FT reactor 114 may perform an FT process on syngas with syngas that has an H2 / CO ratiodry > 2.0. The pressure of the FT process may be about 15 to 25 bar, and preferably about 20 bar. The temperature of the FT process may be about 170°C to 270°C, and preferably about 220°C.

[0043] The FT reactor 114 may output a fuel stream 115 that is a bio-based crude oil. The fuel stream 115 is supplied to the fuel separation system 116. The fuel separation system 116 may be any of a number of known designs of fuel separation system. The fuel separation system 116 may be a dedicated biorefinery. The fuel separation system 116 may separate the components of the fuel stream 115 by evaporation and / or condensation.

[0044] The lighter components of the fuel stream 115 comprise fuel molecules with 1 to 5 carbon atoms. The lighter components may be separated into a light fuel stream 119.

[0045] The remaining liquid fuel components may be separated further so as to generate fuel streams that are usable in specific applications, such as for aviation fuel. A preferred component of the a fuel stream 115 is paraffinic kerosene because this may be used as a sustainable aviation fuel (SAF). The liquid fuel components may be output from the oil / fuel generation system in the fuel output stream 127.

[0046] The light fuel stream 119 may be supplied to the combustor 126 where it is used as a fuel for the combustion process.

[0047] The light fuel stream 119 may additionally, or alternatively, be supplied to a second combustor 120. The second combustor 120 may bum the light fuel stream 119 in air. The heat from the combustion process in the second combustor 120 may be used to generate steam for use in the gasifier 102. For example, a flue gas stream 121 may be output from the second combustor 120 and supplied to a heat exchanger in a steam generator 122. The steam generator 122 may be a water boiler that heats water to generate the steam supply 123 to the gasifier 102.

[0048] Figure 2 schematically shows a hydrogen generation system according to a second embodiment. The hydrogen generation system comprises a syngas generation system 100 and a sorption enhanced water gas shift (SEWGS) system 200. The syngas generation system 100 receives a feedstock 101 and generates a syngas supply 105 in dependence on the received feedstock 101. The SEWGS system 200 receives the syngas supply 105 from the syngas generation system 100 and generates a substantially pure hydrogen stream 205 in dependence on the syngas supply 105.

[0049] The syngas generation system 100 of the second embodiment may be substantially the same as the syngas generation system 100 of the first embodiment. Accordingly, it may receive a waste product, such as fish waste, and generate syngas. The SEWGS system 200 converts the syngas generated by the syngas generation system 100 into a hydrogen stream 205 and a carbon dioxide stream 206.

[0050] The hydrogen generation system may comprise further components than those shown in Figure 2. In particular, the hydrogen generation system may comprise a syngas cleaning system 107 arranged to clean the syngas output from the syngas generation system 100. The syngas cleaning system 107 may be substantially the same as the syngas cleaning system 107 as described in the first embodiment.

[0051] The SEWGS system 200 may comprise further components than those shown in Figure 2. In particular the SEWGS system 200 may comprise a water / steam supply.

[0052] The water-gas -shift reaction reacts carbon monoxide with steam to generate hydrogen and carbon dioxide. The SEWGS system 200 perform the water-gas-shift reaction in the presence of a sorbent of the carbon dioxide so that the products of the reactions are hydrogen and the reacted sorbent. The sorbent may be any sorbent of carbon dioxide. A preferred sorbent is based on calcium oxide. If the sorbent is calcium oxide, then the SEWGS system 200 may comprise a first reactor 201 for supporting the below reaction:

[0053] CO + H2O + CaO = H2 + CaCO3

[0054] Accordingly, the carbon monoxide in the syngas supply 105 is converted to hydrogen, leaving hydrogen as substantially the only remaining gas in the first reactor 201. The reaction in the first reactor 201 may be performed at approximately 400°C to 450°C. The generated hydrogen may output as a substantially pure hydrogen stream 205. The solid calcium carbonate may flow out of the first reactor 201, in sorbent stream 202, to a second reactor 203. In the second reactor 203, the sorbent may be regenerated so that it releases carbon dioxide. The sorbent may be regenerated by heating it. The sorbent regeneration reaction shown below:

[0055] CaCO3= CaO + CO2

[0056] The reaction in the second reactor 203 may be performed at approximately 800°C to 1000°C, and preferably at about 900°C. The released carbon dioxide may flow out of the second reactor 203 as carbon dioxide stream 206. The sorbent may flow back to the first reactor via the sorbent flow path 204.

[0057] In a preferred implementation of the second embodiment, the SEWGS system 200 is based on the combined sorption enhanced reforming, SER, and SEWEGS system as disclosed in WO2019 / 115831, the entire contents of which are incorporated herein by reference.

[0058] In a SER reaction, methane is reacted with H2O to generate CO, CO2 and H2. WO2019 / 115831 discloses a system that receives methane, performs SER to generate syngas, and then performs SEWGS to generate substantially pure hydrogen.

[0059] The SEWGS system 200 of the second embodiment may differ from the disclosure in WO2019 / 115831 by the system not performing SER to generate syngas. The syngas is instead supplied by the syngas generation system 100. The SEWGS system 200 may otherwise be substantially as described in WO2019 / 115831.

[0060] In the second embodiment, the syngas generation system 100 and the SEWGS system 200 are preferably integrated together. For example, heat exchangers and / or heat loops may be used to transfer heat between the syngas generation system 100 and the SEWGS system 200 to improve the overall efficiency of the hydrogen generation system.

[0061] Figure 3 schematically shows an ethanol generation system according to a third embodiment. The ethanol generation system comprises a syngas generation system 100 and a bioreactor system 300. The syngas generation system 100 receives a feedstock 101 and generates a syngas supply 105 in dependence on the received feedstock 101. The bioreactor system 300 receives the syngas supply 105 from the syngas generation system 100 and generates an ethanol stream 301 in dependence on the syngas supply 105. The syngas generation system 100 of the third embodiment may be substantially the same as the syngas generation system 100 of the first embodiment. Accordingly, it may receive a waste product, such as fish waste, and generate syngas. The bioreactor system 300 converts the syngas generated by the syngas generation system 100 into an ethanol stream 301 and a carbon dioxide stream 302.

[0062] The ethanol generation system may comprise further components than those shown in Figure 3. In particular, the ethanol generation system may comprise a syngas cleaning system 107 arranged to clean the syngas output from the syngas generation system 100. The syngas cleaning system 107 may be substantially the same as the syngas cleaning system 107 as described in the first embodiment. The bioreactor system 300 may comprise further components than those shown in Figure 3. The bioreactor system 300 may be any type of reactor for performing a bioconversion of syngas to generate ethanol. The bioconversion may use a biocatalyst. A suitable bioreactor system 300 has been developed by at least LanzaTech, and there are publications of suitable bioreactor systems 300, such as of example https: / / www.sciencedirect.com / science / article / pii / S259014()()2()300022 (as viewed on 12thMay 2024).

[0063] In the third embodiment, the syngas generation system 100 and the bioreactor system 300 are preferably integrated together. For example, heat exchangers and / or heat loops may be used to transfer heat between the syngas generation system 100 and the bioreactor system 300 to improve the overall efficiency of the ethanol generation system.

[0064] A fourth embodiment is shown in Figure 4. The fourth embodiment is based on the first embodiment and includes improved heat integration of the performed processes. Accordingly, the fourth embodiment provides an oil / fuel generation system. The oil / fuel generation system comprises a syngas generation system and a Fischer-Tropsch (FT) system. The syngas generation system receives a feedstock and generates a syngas supply in dependence on the received feedstock. The FT system receives the syngas supply from the syngas generation system and generates fuel in dependence on the syngas supply. The feedstock may comprise fish waste that may be the earlier described fish waste of the first embodiment.

[0065] As shown in Figure 4, there is a source of wet fish waste 401. The water content of the wet fish waste may be up to about 60% to 80%vol liquid water. In some circumstances, such as if mechanical dewatering of the fish waste has already been applied, the water content of the wet fish waste may be lower.

[0066] The wet fish waste is dried in a dryer 402. The dryer 402 may use any of a number of known processes for reducing the water content of the wet fish waste. For example, the dryer may use mechanical de-watering processes, flocculation, filtration, screw presses and / or centrifuges. The dryer 402 may comprise a rotating disc dryer arrangement, such as that described in the International patent application PCT / EP2021 / 053743 the entire contents of which are incorporated herein by reference. The water content of the fish waste output from the dryer 402 may be less that 10%vol water.

[0067] The fish waste output from the dryer 402 is supplied to a gasification system 404. The supply of the fish waste output from the dryer 402 may be the feedstock 101 as described for the first embodiment. The gasification system 404 is a system for performing a gasification process that generates syngas. The gasification system 404 of the present embodiment may comprise the gasifier 102, that is a gasification reactor, as described for the first embodiment. However, in the present embodiment the gasification system 404 may alternatively include any known type of gasification reactor for performing gasification processes. Accordingly, the heat supply to the gasification reactor of the present embodiment may differ from that described for the first embodiment.

[0068] The dryer 402 may also output steam that may be supplied to the gasification system 404 via a first heat exchanger 414. The heat exchanger may heat the received steam so that the output of the first heat exchanger 414 is superheated steam. The temperature of the superheated steam may be 600°C to 700°C. The gasification system 404 may therefore receive superheated steam.

[0069] The gasification system 404 may receive and further products required by the gasification process from a product supply 403. The further products supplied by the product supply 403 may include catalyst(s) and sorbents(s).

[0070] Further inputs to the gasification system 404 may include fuel and oxygen. The oxygen may be supplied as substantially pure oxygen, oxygen enriched air, or air.

[0071] The outputs of the gasification system 404 include syngas and solid reaction products. The solid reaction products, that may be output separately from the syngas, may include ash and / or calcium carbonate.

[0072] The syngas output from the gasification system 404 may be supplied to a first cleaning system 406. The first cleaning system 406 may comprise a dust separator for removing solid products from the syngas. The solid products output from the gasification system 404 and the first cleaning system 406 may be supplied to a first waste product output 405. The syngas output from the first cleaning system 406 may be supplied to a second cleaning system 408 via a second heat exchanger 407. The second cleaning system 408 may comprise the syngas cleaning system 107 as described for the first embodiment. The second cleaning system 408 may comprise a scrubber for cleaning the syngas. The scrubber may wash out residual solid particles and unwanted chemical constituents in the gas phase that can poison the Fischer-Tropsch catalyst and also sustain unwanted chemical reactions. The scrubber may wash the syngas with aqueous H2SO4 (sulfuric acid) received from a fluid supply 423.

[0073] The outputs of the second cleaning system 408 include cleaned syngas and waste products from the cleaning process. The waste products, that may be a sludge, may be supplied to a second waste product output 409.

[0074] The syngas output from the second cleaning system 408 may be supplied to a compressor 410. The compressor 410 may be the compressor 112 as described for the first embodiment. The compressor may compress the syngas to a preferred pressure for an FT reaction, which may be about 20 bar.

[0075] The pressurised syngas may be supplied to as FT system 411. The FT system 411 may comprise the FT reactor 114 as described for the first embodiment. The FT system 411 may generate liquid fuels that are supplied to a liquid fuel output 413. A third heat exchanger 12 may extract heat from the liquid fuel output from the FT system 411.

[0076] The heat integration of the processes performed in the fourth embodiment is described further below.

[0077] The amount of power required by the dryer 402 to dry the wet fish waste depends on the water content of the wet fish waste. However, an example of the power requirement is 1000 to 2000 kW per tonne of output dry fish waste by the dryer 402. The drying of fish waste is typically a low temperature process using an indirect heating medium in the form of hot water, hot oil or steam. Part of the drying may be under vacuum to lower the boiling point of the water so that the heat source can have a temperature below 100°C, but preferably the heat source has a temperature above 100°C, and more preferably in the range 120-180°C, so that conventional disc dryers can be used.

[0078] The gasification and fuel synthesis processes require substantial heat input and / or produce excess heat in the different process steps. Some of these energy streams are preferably integrated with each other and / or the drying process. The dryer may receive heat from the gasification and fuel synthesis processes and this is shown in Figure 4 by the heat flow path 415. The heat may be received from the later described heat flow paths 419, 420 and 421.

[0079] The gasification process requires a supply of superheated steam at a temperature of about 600-700°C. Preferably the source of the steam is at least partially steam, i.e. evaporate, from the drying process performed in the dryer 402. If all of the required steam is evaporate from the dryer 402, this avoids an additional energy requirement for generating the required steam.

[0080] Further heat is still required to superheat the steam to generate dry steam. At least some, and preferably all, of the heat used to generate the superheated steam is preferably heat extracted from the syngas by the second heat exchanger 407. The second heat exchanger 407 may generate a working fluid that has a temperature in the range 100°C to 650°C. The working fluid may flow to the first heat exchanger 414 that superheats the steam. The flow of heat away from the second heat exchanger 407 is shown by heat flow path 418 in Figure 4. The flow of heat to the first heat exchanger 414 is shown by heat flow path 416 in Figure 4. Preferably, over 75% of the required heat to generate superheated steam may be supplied by the working fluid. A further heat source, not shown in Figure 4, may be used to generate the superheated steam if additional heat is required.

[0081] The gasification system 404 requires energy to perform gasification processes. The preferred temperature for the gasification processes may be as described for the first embodiment. For example, the preferred reaction temperature of the gasification processes may be about, or above, 650°C. As described for the first embodiment, the FT system 411 produces a certain fraction of light hydrocarbon gas (with 1 to 5 carbon atoms in each molecule). About 15-20%vol of the fuel produced by the FT system 411 may be in the form of light hydrocarbon gas. At least some, and preferably all, of the light hydrocarbon gas may be supplied to the gasification system 404 where it is combusted to generate heat required energy by the gasification processes performed by the gasification system 404. The flow of the light hydrocarbon gas from the FT system 411 is shown by flow path 422 in Figure 4. The flow of the light hydrocarbon gas into the gasification system 404 is shown by flow path 417 in Figure 4. Preferably, the combustion is with a source of pure oxygen, or oxygen enriched air, because any addition of nitrogen in the gasification system 404 may reduce the overall efficiency of the processes. Accordingly, the heat for the gasification processes in the gasification system 404 may be provided by direct heat transfer from a combustion process.

[0082] Alternatively, or additionally, the heat for the gasification processes in the gasification system 404 may be supplied indirectly from an external heat source to the gasification reactor of the gasification system 404. There may be a heat flow from the external heat source, through the outer walls of the gasification reactor, and to the reaction zone of the gasification reactor. The temperature of the external heat source may at, or higher than, 700°C. The fuel for the external heat source may be the light hydrocarbon gas generated by the FT system 411. The light hydrocarbon gas may be combusted in a separate combustor and the hot flue gas circulated in heating jackets installed on the outer walls of the gasification reactor. Fins may be installed to increase the effective heat transfer area. The heat may additionally, or alternatively, be exchanged via a high temperature molten salt loop or high temperature sodium heat pipes arranged inside or on the walls of the gasification reactor. The heat loop or heat pipes may be arranged in a pattern that attempts to optimise heat transfer. Embodiments also include installing heating tubes that support a catalytic total combustion reaction inside, or on, the walls of the gasification reactor. For example, the heating tubes may be as described in the International patent application PCT / EP2023 / 072770 the entire contents of which are incorporated herein by reference.

[0083] Embodiment include performing processes that intensify the gasification processes inside the gasification reactor, and this is particularly advantageous when indirect heating of the gasification processes is used. The processes enhance the heat exchange from the walls of the gasification reactor into the bed of reactants and catalyst / sorbent inside the gasification reactor. For example, the injection nozzles may be used to inject the superheated steam. The steam jets may increase the circulation of products inside the gasification reactor and the collisions between the products and the heated walls. Pre-compression of the steam before superheating may be used in order to increase the injection velocity to intensify the fluidization, heat exchange and internal friction in the reactor. Alternative techniques for process intensification include the use of mechanical agitation and in-situ generation of friction, such as described in WO 9608544 Al . Steel balls may also be used in the gasification reactor with magnetic forces being used to move the steel balls.

[0084] In the second cleaning system 408 waste heat may occur, such as due to condensation of water vapour present in the syngas. At least some of the waste heat in the second cleaning system 408 may be harvested at a temperature of about 50°C to 100°C. For example, the heat in the second cleaning system 408 may be used to heat a working fluid. The working fluid may flow to the dryer 402 and be used to pre-heat the fish waste before evaporation starts. Heat flow path 419 in Figure 4 shows the flow of heat away from the second cleaning system 408.

[0085] The compressor 410 may be cooled so that the supplied pressurised syngas to the FT system 411 is at the preferred temperature for the FT reactions. The heat extracted at the compressor 410 may be used to heat a working fluid, that may have a temperature of at, or above, about 100°C. The working fluid may flow to the dryer 402 and be used, for example, to pre-heat the fish waste before evaporation starts or, if the temperature of the working fluid is substantially above 100°C, to further heat the steam. Heat flow path 420 in Figure 4 shows the flow of heat away from the compressor 410.

[0086] The FT reactions in the FT system 411 are exothermic. Heat generated in the FT system 411 may be used to heat a working fluid, that may be at the temperature of the FT processes. The working fluid may flow to the dryer 402 and be used, for example, to pre-heat the fish waste before evaporation starts or, if the temperature of the working fluid is substantially above 100°C, to further heat the steam. Heat flow path 421 in Figure 4 shows the flow of heat away from the compressor 410.

[0087] As described earlier, the light hydrocarbon gas generated by the FT system 411 may be combusted to generate heat for the gasification processes. If the light hydrocarbon gas is combusted outside of the gasification reactor, after the flue gas has been used to indirectly heat the gasification processes the flue gas may be supplied to the dryer 402 to heat the fish waste and / or steam.

[0088] The transfer of heat between the different processes in the present embodiment may be performed by one or more heat transfer systems. The one or more heat transfer systems may use known technologies such as heat loops and heat pipes. The heat loops and heat pipes may be as described in the International patent application PCT / EP2020 / 053968 the entire contents of which are incorporated herein by reference.

[0089] The heat integration techniques of the fourth embodiment increase the overall efficiency of the system. The re-use of heat from the downstream processes of the gasification system 404 greatly reduces the heat supply requirement to for the drying processes, gasification processes and the generation of superheated steam. The present embodiment includes the use of other heat sources for the drying processes, gasification processes and the generation of superheated steam if required. However, if the source of wet fish waste 401 is mechanically de watered to a dry solids content of about 40%vol before the fish waste is supplied to the dryer 402, the overall system may be selfsupplied with heat.

[0090] Embodiments also include using heat integration to improve the efficiency of the overall processes performed in the second and third embodiments.

[0091] Further embodiments include using the syngas generated by the syngas generation system of all of the first to fourth embodiments to generate other products than liquid fuels, hydrogen and ethanol.

[0092] Advantageously, the system according to embodiments converts fish waste into the useful product syngas. Embodiments include using the syngas to generate liquid fuel, hydrogen, ethanol and other useful products. The carbon dioxide generated by the performed processes is captured so it is not directly released into the atmosphere.

[0093] Embodiments include a number of modifications and variations to the above described processes.

[0094] The feedstock 101 to the gasifier 102 may be substantially only fish waste. However, embodiments also include the feedstock 101 being a mixture of fish waste and other products, such as biomass. Advantageously, mixing the fish waste with other products prior to the gasification process provides more control over the specific composition of the syngas stream 103.

[0095] Embodiments also include the feedstock 101 to the gasifier 102 being other waste products than fish waste. For example, the feedstock 101 may be, or comprise, pulp and paper waste, waste water sludge and municipal solid waste.

[0096] The oil / fiiel generation system, hydrogen generation system and ethanol generation system according to embodiments may be operated in a number of different configurations with the system using different components in each of the configurations. One or more of the components shown in Figures 1 to 3 may therefore be optional to the extent that embodiments include a configuration of the system that does not use the one or more components.

[0097] The oil / fiiel generation system, hydrogen generation system and ethanol generation system according to embodiments may also comprise further components to those shown in Figures 1 to 3. For example, the system may comprise pumps, coolers, heaters, heat exchangers, valves, manifolds, temperature sensors, pressure sensors, controllers and any other components required for the operation of the system.

[0098] The oil / fiiel generation system may comprise one or more further reactors for upgrading the output fuel. For example, a reactor may be used to perform a mild hydrocracking process (e.g. at 40-80 bar, 300°C to 400°C).

[0099] Embodiments include the fuel separation system 116 alternatively being located remotely from the FT reactor 114 and the fuel stream 115 being transported to the fuel separation system 116.

[0100] Embodiments include the gasifier 102 being any type of gasifier 102. For example, the gasifier 102 may be any of a fixed bed, fluidized bed and entrained flow gasifier. Embodiments also include alternative techniques for transferring heat from the combustor 126 to the gasifier 102. For example, heat may be transferred from the combustor 126 to the gasifier 102 by conduction through the walls of the reactors. Embodiments also include heat being transferred from the combustor 126 to the gasifier 102 via heat pipes or other heat transfer techniques. The gasifier 102 and the combustor 126 may be comprised by a single reactor system.

[0101] Embodiments include the use of any technique for generating syngas from the feedstock 101. In particular, embodiments include performing a thermal hydrolysis process on the feedstock 101. The feedstock may be processed by a hydrothermal gasification reactor system to generate syngas. The processes and / or reactor system used to process the feedstock 101 may be substantially as described here: https: / / www.cambi.com / what-we-do / themial-hydrolvsis / (as viewed on 10thApril 2024), with the key difference of embodiments being that the feedstock is based on fish waste. Fish waste typically comprises lower impurity levels than known alternative feedstocks, it is suitable for generating syngas and is available at low cost.

[0102] The flow charts and descriptions thereof herein should not be understood to prescribe a fixed order of performing the method steps described therein. Rather, the method steps may be performed in any order that is practicable. Although the present invention has been described in connection with specific exemplary embodiments, it should be understood that various changes, substitutions, and alterations apparent to those skilled in the art can be made to the disclosed embodiments without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. CLAIMS1. A syngas production system for producing syngas from fish waste, the system comprising: a gasifier; a feedstock input that is configured to supply a feedstock comprising fish waste to the gasifier; and a steam input configured to supply steam to the gasifier; wherein: the gasifier is configured to generate syngas by performing a steam gasification process on the received feedstock; and the gasifier is configured to perform the gasification process at a temperature in the range of about 550°C to about 800°C, and preferably about 650°C to about 700°C.

2. The system according to claim 1, wherein the gasifier is configured to perform the gasification process at a pressure in the range of about 1 to 5 bar.

3. The system according to any preceding claim, further comprising a combustor configured to perform a combustion process for generating heat for the gasification process.

4. The system according to any preceding claim, wherein the combustor is configured to perform the combustion process on solid products of the gasification process and / or a separate fuel supply to the combustor.

5. The system according to any preceding claim, wherein the combustor is configured to operate at a temperature in the range of about 600°C to about 850°C, and preferably about 700°C to about 750°C.

6. The system according to any preceding claim, wherein the combustor is configured to operate at a pressure in the range of about 1 to 5 bar.

7. The system according to claim 3, or any claim dependent thereon, further comprising a reactive material; wherein:the gasifier is configured to perform the gasification process in the presence of the reactive material; and the combustor is configured to perform the combustion process in the presence of the reactive material; wherein the reactive material is a sorbent of CO2 and / or removes impurities from the products of the gasification process.

8. The system according to claim 7, wherein the reactive material comprises CaO, red mud, CaCOs and / or reaction products of red mud.

9. The system according to claim 7 or 8, wherein the gasifier and the combustor are configured so that, in use, the reactive material moves in a cycle between the combustor and the gasifier.

10. The system according to any preceding claim, wherein the gasifier is configured to output the generated syngas; and the output syngas has the properties:H2 to CO ratiodry > 2.0CH4 < 2vol%dryCO2 < 2 vol%dry tar < 0.5 gm / m311. The system according to any preceding claim, wherein the feedstock comprises substantially only fish waste.

12. The system according to any preceding claim, wherein the fish waste comprises dewatered fish faeces and residual fish feed; and / or wherein the fish waste has been filtered to remove dead fish.

13. The system according to any preceding claim, wherein the fish waste is dried fish waste with a water content of less than 10%vol.

14. The system according to according to any preceding claim, further comprising a heat source configured to generate heat for the gasification process in the gasifier; wherein the heat source and gasifier are configured so that the heat transfer between the heat source and gasifier is an indirect heat transfer.

15. The system according to according to claim 14, wherein the heat source is configured to generate heat by combusting light hydrocarbon gasses.

16. The system according to according to claim 14 or 15, further comprising heat loops and / or heat pipes for indirectly transferring heat from the heat source to the gasifier.

17. The system according to according to any of claims 14 to 16, wherein the heat source is a combustion tube.

18. The system according to claim 17, wherein the heat source is arranged inside the gasifier, in the walls of the gasifier, and / or around the outside of the walls of the gasifier.

19. The system according to according to any preceding claim, wherein the steam input comprises nozzles for injecting the steam into the gasifier.

20. The system according to according to any preceding claim, wherein the temperature of the steam supplied the gasifier is about 600°C to 700°C.

21. An oil / fuel generation system for producing oil / fiiel from fish waste, the system comprising: the syngas production system according to any preceding claim; and a Fischer-Tropsch, FT, system configured to receive syngas generated by the syngas production system and generate oil / fiiel in dependence on the received syngas.

22. The system according to claim 21, further comprising a syngas cleaning system configured to: clean the syngas output from the syngas production system; supply the cleaned syngas to the FT system.

23. The system according to claim 22, wherein the syngas cleaning system comprises a wet scrubber.

24. The system according to any of claims 21 to 23, further comprising a fuel separation system configured to separate the fuel output from the FT system into at least light fuel and other fuel components.

25. The system according to claim 24, when dependent on claim 3, further comprising conduit(s) arranged to receive light fuel components from the fuel separation system and to supply at least some of the light fuel components to the combustor.

26. The system according to claim 24 or 25, further comprising: a second combustor; a steam boiler; and conduit(s) arranged to receive light fuel components from the fuel separation system and to supply at least some of the light fuel components to the second combustor; wherein: the second combustor is configured to generate heat by combusting the received light fuel components; the second combustor is configured to supply the generated heat to the steam boiler so that the steam boiler generates steam; and the steam boiler is configured to supply the steam to the gasifier.

27. The system according to claim 24, when dependent on claim 14, further comprising conduit(s) arranged to receive light fuel components from the fuel separation system and to supply at least some of the light fuel components to the heat source.

28. The system according to any of claims 21 to 27, further comprising a dryer configured to dry the feedstock before the feedstock is supplied to the gasifier.

29. The system according to claim 28, further comprising one or more heat transfer systems configured to transfer heat from the FT system to the dryer.

30. The system according to claim 28 or claim 29, when dependent on claim 22, further comprising one or more heat transfer systems configured to transfer heat from the syngas cleaning system to the dryer.

31. The system according to any of claims 28 to 30, further comprising: a compressor configured to compress the syngas and supply the compressed syngas to the FT system; and one or more heat transfer systems configured to transfer heat from the compressor to the dryer.

32. The system according to any of claims 21 to 31, further comprising a heat transfer system configured to transfer heat from syngas generated by the syngas production system to the steam supply to the gasifier of the syngas production system.

33. An oil / fuel generation system for producing oil / f el from fish waste, the oil / fuel generation system comprising: a syngas production system; a feedstock input that is configured to supply a feedstock comprising fish waste to the syngas production system; and a Fischer-Tropsch, FT, system configured to receive syngas generated by the syngas production system and generate fuel in dependence on the received syngas; wherein the syngas production system is configured to generate syngas in dependence on the received feedstock.

34. A hydrogen generation system for producing hydrogen from fish waste, the system comprising: the syngas production system according to any of claims 1 to 20; and a sorption enhanced water gas shift, SEWGS, system configured to receive syngas generated by the syngas production system and generate hydrogen in dependence on the received syngas.

35. An ethanol generation system for producing ethanol from fish waste, the system comprising: the syngas production system according to any of claims 1 to 20; and a bioreactor system configured to receive syngas generated by the syngas production system and generate ethanol in dependence on the received syngas.

36. A method of producing syngas from fish waste, the method comprising: obtaining a feedstock comprising fish waste generating syngas by performing a steam gasification process on the feedstock wherein: the steam gasification process is performed at a temperature in the range of about 550°C to about 800°C, and preferably about 650°C to about 700°C.

37. A method of producing oil / fuel from fish waste, the method comprising: the method of producing syngas according to claim 36; and generating oil / fuel by performing a Fischer-Tropsch, FT, process on the produced syngas.

38. A method of producing hydrogen from fish waste, the method comprising:the method of producing syngas according to claim 36; and generating hydrogen by performing a sorption enhanced water gas shift, SEWGS, process on the produced syngas.

39. A method of producing ethanol from fish waste, the method comprising: the method of producing syngas according to claim 36; and generating ethanol by performing a bioreaction process on the produced syngas.

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