Conversion of solid waste to syngas and hydrogen.

Abstract

The method and plant 1 for converting solid recovered fuel pellets 117 made from municipal solid waste 103 allows for the conversion of municipal solid waste 103 into hydrogen at high yields, instead of landfilling or incinerating the municipal solid waste 103. The hydrogen-rich product gas stream 601 can be used as a feedstock for chemical reactions or can be used to store energy in a releasable manner.

Description

[Technical Field]

[0001] The subject of the present invention is the conversion of solid waste, such as municipal waste or biomass in the form of solid recovered fuel (SRF) pellets, into a hydrogen-rich product stream, preferably pure hydrogen. [Background technology]

[0002] Municipal solid waste (MSW) is generated worldwide and requires addressing. In the Western Hemisphere, MSW is either landfilled or incinerated. In contrast to recycling or reusing MSW contents at a molecular scale, such as through chemical recycling, incineration focuses on maximizing the energy content of MSW. Incineration raises concerns about the emission of pollutants into the atmosphere, which, depending on national or regional regulations, requires significant technological efforts to meet national / regional regulatory limits. Furthermore, products generated by incineration, such as fly ash, bottom ash, gypsum, and activated carbon containing heavy metals and dioxins, present additional challenges for their further use and disposal. Furthermore, waste-to-energy efficiency, i.e., the amount of calorific value transferred to thermal energy, is low, typically in the 20–25% range. Summary of the Invention [Means for solving the problem]

[0003] Based on this, the object of the present invention is to overcome the drawbacks known from the prior art.

[0004] This object is solved by the features of the independent claims. The respective dependent claims relate to further embodiments of the invention. Further embodiments can be inferred from the description, including the figures and the respective description of the figures.

[0005] The method for processing solid recovered fuel pellets according to the present invention comprises the following steps: a) torrefying the pellets at a torrefying temperature of 250°C to 300°C to produce carbonized pellets and torrefaction gas. Step a) is preferably carried out in a torrefying apparatus as described below; b) pulverizing the carbonized pellets from the first pulverization step to produce coarsely pulverized carbonized pellets. Step b) is preferably carried out in a second pulverizer as described below; c) removing metal residues from the coarsely pulverized carbonized pellets. Step c) is preferably carried out using a third metal removal device as described below; d) pulverizing the coarsely pulverized carbonized pellets into finely pulverized carbonized pellets. Step d) is preferably carried out in a third pulverizer as described below; e) gasifying the finely pulverized carbonized pellets into raw syngas by entrained-flow gasification. Step e) is preferably carried out in a gasifier as described below; and f) performing a CO shift reaction on the raw syngas to produce shifted syngas. Step f) is preferably carried out in a CO shift device as described below. g) removing carbon dioxide and hydrogen sulfide from the shifted syngas to produce syngas; and h) generating a hydrogen-rich product gas stream by purifying the syngas. Steps g) and h) are preferably carried out in a gas purification unit as described below.

[0006] Steps a) to h) are carried out according to the present invention in the stated order, i.e., first step a), then step b), then step c), and then step d). The term torrefaction in step a) is understood as a thermochemical treatment of the solid recovered fuel pellets at a temperature of 250°C to 320°C. The torrefaction is carried out under atmospheric pressure and without the addition of additional oxygen, e.g., without the supply of air. During the torrefaction process, water contained in the solid recovered fuel pellets evaporates, as do volatile components contained in the solid recovered fuel pellets. Biopolymers contained in the solid recovered fuel pellets are partially decomposed as volatile substances are released. The products of the torrefaction process are carbonized pellets and torrefaction gas.

[0007] The term hydrogen-rich gas stream or hydrogen-rich gas stream is understood as a gas containing at least 90% by volume of hydrogen, preferably at least 95% by volume of hydrogen, in particular at least 99.5% by volume of hydrogen. The remainder is composed of argon (Ar), nitrogen (N), carbon monoxide (CO) and carbon dioxide (CO). Preferably, in steps g) and h), carbon dioxide and hydrogen sulfide are first removed by adsorption, and then hydrogen is separated from the remainder by a second pressure swing adsorption (PSA) process to form a hydrogen-rich product gas stream having a hydrogen content preferably of at least 99.5% by volume.

[0008] Preferably, solid recovered fuel pellets are produced from municipal waste, which may also contain biomass, preferably in connection with a pelletizing facility as disclosed below, with particular reference to Figures 1 and 3. In the process described, most metal residues are removed from the waste before producing the solid recovered fuel pellets. Nevertheless, this process may not completely remove the metal residues. Therefore, step c) after step b) further reduces the amount of metal residues in the carbonized pellets. When applying eddy current technology, both ferrous and non-ferrous metal residues can be removed from the coarsely ground carbonized pellets.

[0009] In step b), a crushing process is carried out to produce a first particle distribution having a first maximum particle size preferably equal to or less than 10 mm (millimeters). In step d), a crushing process is carried out to produce a second particle distribution having a second maximum particle size significantly smaller than the first maximum particle size. Preferably, the second maximum particle size is 350 μm (micrometers). The second maximum particle size is preferably selected to enable efficient entrained-flow gasification in step e). This allows for both efficient removal of metal residues in step c) and efficient entrained-flow gasification in step e).

[0010] The entrained-flow gasification in step e) is preferably carried out by thoroughly quenching the synthesis gas generated during entrained-flow gasification with water. This quenching results in any solids contained in the synthesis gas, even if they are in a molten state, being solidified and recovered as slag during the process. The quench water is preferably used in a cyclical manner, i.e., no water is discharged from the system. The wastewater from this process is treated and evaporated, ultimately producing sodium chloride (NaCl) as a by-product. The condensate is reused during the process as make-up water.

[0011] The method according to the invention allows for the chemical recycling of municipal waste to produce hydrogen, which can be used as a feedstock in chemical processes or for energy storage, or both.

[0012] According to an embodiment, the torrefaction gas produced in step a) is pyrolyzed to produce torrefied syngas, which is mixed with the raw syngas produced in step e) prior to step f).

[0013] The pyrolysis of the torrefaction gas is carried out in a torrefaction gas treatment apparatus described in detail below, in particular as shown in Figure 4. The pyrolysis is preferably carried out using a sub-stoichiometric oxidation process to decompose long-chain hydrocarbons that may be present in the torrefaction gas and the fuel gas used for pyrolysis. Preferably, an oxygen-rich gas stream containing 95% by volume of oxygen is used in the pyrolysis process, preferably pure oxygen. Pyrolysis of the torrefaction gas also allows the torrefaction synthesis gas to be used for chemical recycling instead of being combusted.

[0014] According to an embodiment, in step b), the carbonized pellets are crushed to a particle size of 10 mm or less, which allows for efficient removal of metal residues in step c), which is preferably carried out in a second crusher as described below.

[0015] According to an embodiment, the metallic residues are removed in step c) using eddy current techniques. Applying eddy currents in this manner removes both ferrous and non-ferrous metallic residues. Step c) is preferably carried out using a third metal removal device as described below.

[0016] According to an embodiment, in step d), the coarsely pulverized carbonized pellets are pulverized to a particle size of 500 μm (micrometers) or less. This allows for efficient entrained-flow gasification of the finely pulverized carbonized pellets. As described below, pulverized biomass can be added to the finely pulverized carbonized pellets before entrained-flow gasification. Step d) is preferably performed in a third pulverizer, as described below.

[0017] According to an embodiment, in step g), carbon dioxide (CO2) and hydrogen sulfide (HS) are removed from the synthesis gas by adsorption. Each carbon dioxide is purged from each of the at least one adsorber and used as a feedstock for chemical processing or purged to the ambient. Hydrogen sulfide is converted to elemental sulfur using the Claus process. The tail gases of the Claus units are hydrotreated and recycled to the respective adsorber.

[0018] According to an embodiment, Process h) In the process, hydrogen is separated from the synthesis gas using pressure swing adsorption (PSA) to produce a hydrogen-rich product gas stream and a purge gas.

[0019] According to an embodiment, at least a portion of the purge gas is supplied to the CO shift reaction in step f), which can improve the conversion efficiency in the CO shift device and increase the total yield of hydrogen.

[0020] According to an embodiment, a portion of the purge gas is used as fuel gas.

[0021] The purge gas includes at least one of carbon monoxide (CO), carbon dioxide (CO2), nitrogen (N2), hydrogen (H2), and argon (Ar).

[0022] According to another aspect of the present invention, there is provided a plant for processing solid recovered fuel pellets into a hydrogen-rich product gas stream, comprising: a torrefaction device for torrefying the solid recovered fuel pellets into carbonized pellets; a second crusher for crushing the carbonized pellets into coarsely crushed carbonized pellets; a third metal removal device including an eddy current for removing metal residues from the coarsely pulverized carbonized pellets; a third crusher for crushing the coarsely crushed carbonized pellets into finely crushed carbonized pellets; a gasification system comprising an entrained flow gasifier for gasifying pulverized carbonized pellets into raw synthesis gas; a CO shift unit for performing a CO shift reaction on the raw syngas to produce a shifted syngas; a gas purification system comprising adsorption means for removing carbon dioxide and hydrogen sulfide from the shifted synthesis gas and a hydrogen separator for separating hydrogen from the purge gas to generate a hydrogen-rich product gas stream; A plant is proposed comprising:

[0023] According to an embodiment, the plant further comprises a torrefaction gas treatment device for pyrolyzing torrefaction gas that can be generated in the torrefaction device.

[0024] According to an embodiment, the hydrogen separator comprises a pressure swing adsorption system.

[0025] It should be noted that the individual features specified in the claims can be combined with one another in any desired technically significant manner to define further embodiments of the present invention. The present invention is further described herein, particularly in conjunction with the figures, which specify particularly preferred embodiments of the present invention. Particularly preferred variants and technical fields of the present invention are described in more detail below with reference to the accompanying drawings. It should be noted that the exemplary embodiments shown in the drawings are not intended to limit the present invention. The drawings are schematic and may not be drawn to scale. [Brief explanation of the drawings]

[0026] [Figure 1] 1 shows a visualization of the pelletizing equipment. [Figure 2] 1 shows an example of a plant for converting solid waste into a product gas stream containing hydrogen. [Figure 3] An example of a dryer used in a pelletizing facility is shown below. [Figure 4] The torrefaction and gasification equipment is shown. [Figure 5] 1 shows a torrefaction gas treatment device. [Figure 6] Carbon monoxide (CO) shift device shown. [Figure 7] 1 shows a gas purification device. DETAILED DESCRIPTION OF THE INVENTION

[0027] FIG. 1 is a schematic diagram of a pelletization facility 100, in which solid recovered fuel pellets 117 produced in the pelletization facility 100 are supplied to a plant 1 for converting solid waste into hydrogen-containing gases, particularly hydrogen and hydrogen-containing syngas. After pellets are produced in the pelletization facility 100 from solid waste, such as municipal solid waste 103 or biomass, each pellet 117 is transported to the plant 1 and supplied to a torrefaction unit 200, where the pellets are oxidized substoichiometrically at temperatures between 250°C and 300°C. The torrefaction of the pellets results in carbonized pellets 201, which are then gasified in a gasification unit 300. Another product of the torrefaction is torrefaction gas 202, which is supplied to a torrefaction gas treatment unit 400, which will be described in more detail below with reference to FIG. 5. The output of the torrefaction gas treatment unit 400 is torrefied syngas 401, and the output of the gasification unit 300 is raw syngas 301. The torrefied syngas 401 and the raw syngas 301 contain water vapor, carbon monoxide, and hydrogen. Both the raw syngas 301 and the torrefied syngas 401 are introduced into a CO shift unit 500 where the carbon monoxide (CO) reacts with water vapor (H2O) to form carbon dioxide (CO2) and hydrogen (H2) as follows: [C1] CO + H2O ⇔ CO2 + H2

[0028] A shifted syngas 501, having an increased hydrogen content relative to the syngas 301, 401, is generated in the CO shift unit 500. The shifted syngas 501 is then transferred to a gas purification unit 600, which separates the hydrogen from a purge gas 602 to produce a hydrogen-rich product gas stream 601. The hydrogen content of the hydrogen-rich product gas stream 601 is at least 99.5% by volume. The gas purification unit 600 separates carbon dioxide and hydrogen sulfide from the remaining gas stream to produce a feed hydrogen stream, which is fed to a pressure swing adsorption system. The pressure swing adsorption system allows hydrogen to pass through while adsorbing all other molecules. A purge gas is generated by cyclically reducing the pressure and purging with hydrogen using multiple adsorbers. A hydrogen-rich product stream with a hydrogen content of at least 99.5% by volume is simultaneously generated. The pelletization facility 100 is preferably external, i.e., not co-located with the plant 1 for converting solid waste to a hydrogen-containing gas. The external location of the pelletizing facility 100 is advantageous because it reduces the mass of the municipal waste, typically by evaporating approximately 30-35% by weight of its moisture content. This significantly reduces the mass to be transported. Furthermore, the pelletizing facility 100 allows for the centralized production of solid recovered fuel pellets and subsequent transport of these pellets to chemical plants where they are needed, thereby reducing the footprint of chemical plants such as plant 1.

[0029] Referring to FIG. 1 , a pelletizing facility 100 includes a crusher 102. Solid waste 103, such as municipal solid waste (MSW), which may further contain biomass, is fed into the crusher 102 to produce crushed solid waste 104. The crushed solid waste 104 is then conveyed to a first metal removal device 105, which includes magnets, to remove ferrous residues 106 from the crushed solid waste 104. The crushed solid waste 104 is then fed to a dryer 107, where water 108 is removed from the crushed solid waste 104. The crushed solid waste 104 is then conveyed to a second metal removal device 109 for removing metallic residues 110 from the crushed solid waste 104. The second metal removal device 109 includes a second magnet 139 for further removing ferrous metals and an eddy current for removing non-ferrous metals.

[0030] Thereafter, stainless steel and minerals are removed as further residue 111 in a gravity separator 112. In the gravity separator 112, high-density residue that cannot be removed by magnets or eddy current, such as stainless steel particles, is removed based on the difference in specific gravity between the further residue 111 and the remainder of the crushed solid waste 104. The same applies to minerals such as glass and stone, which are removed from the remainder of the crushed solid waste 104 based on the difference in specific gravity. A preferred example of the gravity separator 112 is, for example, an air separator.

[0031] After removing the further residue 111, ferrous metals (such as the ferrous residue 106 and the metal residue 110), non-ferrous metals, stainless steel and minerals as the further residue 111, and moisture 108 in the form of water remain removed from the shredded solid waste 104. The remainder of the shredded solid waste 104 is essentially the same as the solid waste 103 input into the pelletizing facility 100. In particular, the pelletizing facility 100 of the present invention does not require separation of fine fragments of the solid waste 103 or chlorine-containing materials such as polyvinyl chloride (PVC). This means that the ratio of the mass of the unwashed material stream 113 present downstream of the first metal removal device 105, the second metal removal device 109, and the density separator 112 to the mass of the solid waste 103 input into the pelletizing facility 100 is greater than in known techniques.

[0032] The raw material stream 113 is then pulverized in a first pulverizer 114, particularly to an average particle size of less than 25 mm, to produce a pulverized material stream 115. The pulverized material stream 115 is then fed into a pellet press 116 to produce solid recovered fuel pellets 117.

[0033] FIG. 3 shows an example of a dryer 107 used in the pelletizing facility 100 shown in FIG. 1. The dryer 107, which dries the shredded solid waste 104, is composed of a kiln 118 for receiving the shredded solid waste 104, a washing tower 119 (which may also be called a scrubber), a heat pump 120, and a radiator 121. Air is drawn into the dryer 107 through a dryer inlet 122, which is typically fluidly connected to the atmosphere. The drawn air can be sent to the radiator 121 through a vent (not shown in FIG. 3). The dryer inlet 122 is fluidly connected to a radiator inlet 123 of the radiator 121 through a duct. The air sent to the radiator 121 is heated by the radiator 121 and exits the radiator 121 through a radiator outlet 124. The heated air is sent toward the kiln 118. The kiln air inlet 125 is fluidly connected to the radiator exhaust 124 via a duct. The shredded solid waste 104 is placed inside the kiln 118, and air is delivered to the kiln 118, flows through the shredded solid waste 104, and exits the kiln 118 through the kiln exhaust 126. During the drying process, the air entering the kiln 118 has a temperature of approximately 80°C, and the air exiting the kiln 118 has a temperature of approximately 45°C. The relative humidity of the air exiting the kiln 118 is approximately 100%.

[0034] Kiln 118 is fluidly connected to scrubber 119. Kiln exhaust 126 is fluidly connected to scrubber air inlet 127. Inside scrubber 119, air is forced into intimate contact with chilled water, which cools the moist warm air, condensing the air's humidity and converting latent heat to sensible heat in the water. This results in the water being heated from approximately 18°C ​​to approximately 25°C-28°C and the air being cooled from approximately 28°C-32°C to approximately 22°C-24°C. The cooled air exits scrubber 119 via scrubber exhaust 128, which is fluidly connected to dryer exhaust 129.

[0035] The air leaving the scrubber 119 can also be sent to the dryer air inlet 122 via a recirculation path 130, with the scrubber exhaust 128 being fluidly connected to the dryer air inlet 122. A corresponding arrangement results in lower energy consumption for the apparatus 100. The recirculation path 130 does not necessarily need to be included in the apparatus 100 and can be omitted.

[0036] In terms of air flow, the radiator 121 is located downstream of the dryer air inlet 122, the kiln 118 is located downstream of the radiator 121, the scrubber 119 is located downstream of the kiln 118, and the dryer exhaust 129 is located downstream of the scrubber 119.

[0037] The scrubber 119 further includes a scrubber outlet 131, which is fluidly connected to a first heat pump water inlet 132. The first heat pump outlet 133 is fluidly connected to a scrubber water inlet 134. Thus, water circulates between the scrubber 119 and the heat pump 120. The water can be transported by a pump (not shown in FIG. 3).

[0038] Water is heated in the scrubber 119 by air entering the scrubber 119 via the scrubber air inlet 127, and the heated water leaves the scrubber 119 via the scrubber outlet 131 and enters the heat pump 120 via the first heat pump inlet 132. The thermal energy of the water entering the heat pump 120 is then transferred to another heat cycle established between the heat pump 120 and the radiator 121. The water entering the heat pump 120 has a temperature of approximately 26°C to 28°C, and the water leaving the heat pump 120 via the first heat pump outlet 133 has a temperature of approximately 18°C.

[0039] The first heat pump outlet 133 is fluidly connected to the scrubber water inlet 134. Therefore, the water cooled inside the heat pump 120 enters the scrubber 119 through the scrubber water inlet 134. Thus, a heat cycle is realized between the scrubber 119 and the heat pump 120, and the thermal energy of the water leaving the scrubber 119 is transferred to a second heat cycle between the heat pump 120 and the radiator 121 via the heat pump 120.

[0040] The second heat pump outlet 135 is fluidly connected, and therefore thermally connected, to the radiator water inlet 136. The radiator outlet 137 is fluidly connected, and therefore thermally connected, to the second heat pump inlet 138. This allows a pump (not shown in FIG. 3 ) to pump water between the heat pump 120 and the radiator 121. As a result, a second heat cycle is realized between the heat pump 120 and the radiator 121.

[0041] Thermal energy from the water coming out of the scrubber 119 is transferred to the radiator 121 via the heat pump 120 and transferred to the air flowing from the radiator air inlet 123 through the radiator 121 to the radiator outlet 124 .

[0042] The pelletizing system 100 according to the present invention allows for the production of solid recovered fuel pellets from municipal waste without separating a portion of the municipal waste before the pelletizing process begins. Thus, a greater amount of municipal waste can actually be used to produce solid recovered fuel pellets. The pelletizing system 100 and method according to the present invention can be used to produce solid recovered fuel pellets that can be used to produce synthesis gas that is rich in hydrogen or carbon dioxide, or both, particularly by torrefying the solid recovered fuel pellets through subsequent gas treatment.

[0043] FIG. 4 shows an example of a torrefaction apparatus 200 and a gasification apparatus 300. In the torrefaction apparatus 200, solid recovered fuel pellets 117 are fed into a furnace 203, which is a multi-stage furnace in this embodiment. The torrefaction of the solid recovered fuel pellets 117 is carried out in the furnace 203. The term torrefaction is understood to mean a thermochemical treatment of the solid recovered fuel pellets 117 at a temperature of 250°C to 320°C. The torrefaction is carried out under atmospheric pressure and without the addition of additional oxygen, for example, without the supply of air. During the torrefaction process, water contained in the solid recovered fuel pellets 117 evaporates, and similarly, volatile components contained in the solid recovered fuel pellets 117 evaporate. Biopolymers contained in the solid recovered fuel pellets 117 are partially decomposed as the volatile substances are released. Products of the torrefaction process are carbonized pellets 201 and torrefaction gas 202.

[0044] The torrefaction gas 202 is fed to a torrefaction gas treatment device 400, described below with reference to FIG. 5. The carbonized pellets 201 contain carbonized plastic or organic fractions and may contain metal inclusions because the metal portion of the solid recovered fuel pellets 117 is not carbonized during the torrefaction process. The carbonized pellets 201 are fed to a second crusher 204 for coarse crushing to a particle size of 10 mm or less. A third metal removal device 205, based on eddy current removal, then removes metal residues 206 that were not removed during the production of the solid recovered fuel pellets 117. The third metal removal device 205 removes both ferrous and non-ferrous residues. The remaining coarsely crushed carbonized pellets 207 are transferred to a third crusher 208, where they are crushed into finely crushed carbonized pellets 209 with particle sizes of 500 μm or less.

[0045] The pulverized carbonized pellets 209 are supplied as feedstock 303 to a gasification apparatus 300 including an entrained-flow gasifier 302. Biomass 304, such as dried sludge, can be added to the pulverized carbonized pellets 209 after being pulverized to a particle size on the same order as that of the pulverized carbonized pellets 209. The biomass 304 is pulverized in a corresponding fourth pulverizer 305. The pulverized biomass 306 is then added to the feedstock 303 upstream of the entrained-flow gasifier 302. Alternatively, although not shown in FIG. 4 , the biomass 304 can be pulverized together with the carbonized pellets 201 and thus fed into the second pulverizer 204 together with the carbonized pellets 201.

[0046] The feedstock 303 is fed to the entrained-flow gasifier 302 together with an oxygen-rich gas 307 having an oxygen content of at least 95% by volume, preferably at least 98% by volume, in particular 99.5% by volume or more. The gasification reaction takes place in a co-current flow in a dense cloud of very fine particles. The gasification takes place at a temperature of 2000°C and a pressure of 40 bar.

[0047] The resulting intermediate product gas 308 is fed to a quenching zone 309 where it is quenched with quench water 310. The temperature of the quench water 310 is preferably between 180°C and 220°C. The solid or molten solids solidify during this quenching process, forming slag 311. This slag 311 can be extracted and used in civil engineering. The resulting raw syngas stream 312 is fed to a water wash cooling tower 313, where it is contacted with water 314 at a temperature between 180°C and 200°C, lower than the temperature of the raw syngas 312 (approximately 214°C), thereby condensing the water contained in the raw syngas 312. The cooled and washed raw syngas 301 is fed to a CO2 shift unit 500. Excess bleed water 315 is fed to a slurry stripper (not shown) to remove gases from the excess bleed water 315. Make-up water 316 is supplied from a low-temperature heat recovery device 524 of the CO shift device 500, which will be described later.

[0048] FIG. 5 shows a torrefaction gas treatment apparatus 400. The torrefaction gas 202 generated in the torrefaction apparatus 200 is introduced into a combustion chamber 402. Furthermore, a fuel gas 403 and an oxygen-rich gas stream 404 are introduced into the combustion chamber 402. The fuel gas 403 can be natural gas, an on-site fuel gas, or both. The fuel gas contains at least one of methane, ethane, nitrogen, and hydrogen. The so-called on-site fuel gas is generated, for example, in a steam cracker. The oxygen-rich gas stream 404 contains at least 95% by volume of oxygen, preferably at least 98% by volume, and particularly 99.5% by volume or more. In particular, when the gasifier 300 uses entrained-flow gasification in parallel, pure oxygen is readily available. That is, the oxygen-rich gas stream 307 used in the gasifier 300 can be supplied from the same source as the oxygen-rich gas stream 404. The combustion chamber 402 has a first inlet 436 for introducing the oxygen-rich gas stream 404, a second inlet 437 for introducing the fuel gas, and a third inlet 438 for introducing the torrefaction gas 202. The resulting raw syngas 301 is fed to a CO shift device 500.

[0049] In the combustion chamber 402, sub-stoichiometric oxidation occurs by pyrolysis of larger hydrocarbon molecules from the torrefaction gas 202 and / or fuel gas 403 and converting them into a synthesis gas 407 containing carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2) and water (H2O). The high moisture content of the torrefaction gas 202, typically at least 50% by volume, reduces the generation of elemental carbon and therefore soot.

[0050] The temperature of the combustion chamber 402 is in the range of 1000°C to 1200°C. After passing through the combustion chamber outlet 405, the syngas 407 is quenched to a temperature of 730°C to 770°C, preferably 740°C to 760°C, and in particular to a temperature of about 750°C, by the recycled syngas 406 acting as a quench gas. The syngas 407 is introduced into the mixing chamber 408 for quenching and subsequent mixing with the recycled syngas 406. This results in a quenched syngas 409 cooled in the mixing chamber 408. This quenching takes place in a quenching zone 439 having an inlet 440 for the recycled syngas 406. The effect of the quenching, i.e., the sudden drop in temperature due to the introduction of the cooler recycled syngas 406, is to solidify any solids or molten solids present in the syngas 407. These solids may be introduced together with the torrefaction gas 202. Both the combustion chamber 402 and the mixing chamber 408 are internally insulated and are not cooled.

[0051] Downstream of the mixing chamber 408, the quenched syngas 409 is introduced into a heat recovery system 410, in which thermal energy of the quenched syngas 409, i.e., heat energy, is transferred in a first heat exchanger 441 to a heat transfer medium 411, preferably a thermal oil. Downstream of the energy transfer to the heat transfer medium 411, further thermal energy is transferred in a second heat exchanger 442 to a boiler feed water 412 to produce high-pressure steam 413, at least a portion of which is transferred via a fourth heat exchanger 414 to heat the recycled syngas 406, preferably to a temperature above 200°C, in particular about 225°C. In the heat recovery system 410, in a superheater 443 downstream of the second heat exchanger 441 with the boiler feed water 412, further thermal energy from the quenched syngas 409 is transferred to low-pressure steam 415, which is superheated to generate superheated low-pressure steam 416. The heat transfer medium is heated, for example, to a temperature of 300°C to 400°C, and can be used, for example, to indirectly heat the torrefaction apparatus 200. The high-pressure steam 413 leaves the heat recovery system 410 at, for example, a pressure of 140 bar and a temperature of 350°C. The superheated low-pressure steam leaves the heat recovery system 410 at a temperature of approximately 275°C, and is preferably used for torrefaction in the torrefaction apparatus 200. The quenched synthesis gas 409 leaves the heat recovery system 410 at a temperature of approximately 170°C or higher to avoid the formation of ammonium chloride (NH4Cl), which can cause corrosion and fouling. To ensure that this temperature of approximately 170°C is not reached, boiler feed water 412 is introduced into the heat recovery system 410 at a temperature of 140°C or higher.

[0052] Downstream of the heat recovery system 410, the quenched syngas 409 is introduced into a wet scrubbing system 417 to remove solids and halogens (primarily chlorides). The wet scrubbing system 417 is a typical wet scrubbing tower. A drain 419 of the wet scrubbing system 417 discharges spent scrubbing water 418, which is recycled and transported to a wastewater treatment facility (not shown). The wet scrubbing system 417 outputs purified syngas 420 at its tip 421. A first portion of the purified syngas 420 is used as recycled syngas 406 and is reheated and used to quench the syngas 407, as described above. Using the purified syngas 420 as recycled syngas 406 reduces the concentration of contaminants (e.g., solids, halogens, especially chlorides) in the quenched syngas 409 and prevents damage, especially corrosion, to the heat exchange surfaces of the heat recovery system. In particular, corrosion of surfaces used to superheat low pressure steam 415 to superheated low pressure steam 416 is avoided. At the same time, the high moisture content of 60% by volume or more increases the heat capacity of recycled syngas 406, resulting in improved cooling efficiency during the quenching process. Recycled syngas 406 is compressed by compressor 423.

[0053] The second, remaining portion 424 of the purified syngas 420 is introduced into a two-stage water wash cooling tower 422. In tower 422, water in the syngas 424 condenses against cooler water. The heat of condensation heats the wash water in tower 422. Wash water 426 from a water collection hole 425 is fed to a heat pump 427 for cooling, for example, from a temperature of about 85°C to 75°C. Low-pressure steam is generated in heat pump 427 and preferably used to control the process in torrefaction unit 200. The majority of wash water 426 is introduced into the center of tower 422 and distributed to both the first stage 428 and the second stage 429 of tower 422. The smaller portion of wash water 426 is further cooled by air cooler 430, preferably to a temperature of about 25°C, resulting in a syngas 424 at a temperature of about 30°C upon leaving tower 422. The syngas 422 is cooled, resulting in removal of approximately 60% of its mass as water. Excess wash water 431 is used in part as makeup water 432 for the wet scrubbing system 417. The excess wash water 431 can be directed as bleed water 433 to a removal system (not shown) where gases are removed from the bleed water 433, particularly ammonia (NH), carbon dioxide (CO), and hydrogen sulfide (HS).

[0054] A syngas conveying means 434, preferably a fan or blower, is used to convey the torrefied syngas 401 from tower 422 to a CO shift unit 500 (see FIG. 2) or a flare 435, or both. The syngas conveying means 434 creates a negative pressure that draws the quenched syngas 406 through a heat recovery system 410.

[0055] The torrefaction gas treatment device 400 makes it possible to chemically recycle torrefaction gas 202 produced from solid recovered fuel pellets 117 and the like by torrefaction without the need to combust the torrefaction gas 202.

[0056] 6 is a schematic diagram of a carbon monoxide (CO) shift device 500 included in the plant 1. In the CO shift device 500, a carbon monoxide (CO) shift reaction occurs in which carbon monoxide (CO) reacts with water (HO) to form carbon dioxide (CO) and hydrogen (H) as follows: [Case 2] CO + H2O ⇔ CO2 + H2

[0057] This reaction is in chemical equilibrium and can be influenced in either direction by conventional methods, such as by using the respective temperatures and specific catalyst concentrations. Because the reaction is endothermic, water is typically supplied as steam. A steam-to-carbon monoxide molar ratio of about 2.3 to 2.7, particularly about 2.5, has been found to be advantageous for shifting the chemical equilibrium toward the product and increasing hydrogen production. Steam is preferably supplied at a pressure above the pressure at which the shift reaction occurs, preferably about 40 bar. With a steam-to-carbon monoxide molar ratio of 2.5, 1.5 moles of excess steam are left in the reactor for every mole of carbon dioxide. This results in a significant amount of water in the CO shift reaction product gas. When this product gas is cooled, significant condensation occurs, cooling the product gas to ambient temperature while providing a large amount of low-level heat to the cooling train. Typically, most of this energy is wasted, resulting in low energy efficiency.

[0058] The raw syngas 301 produced by the gasifier 300 is introduced into a high-pressure washer 502. The high-pressure washer 502 is a conventional wet scrubber device in which, for example, higher hydrocarbons are removed from the raw syngas 301. The high-pressure washer 502 is supplied with feed water 503, which is condensate 508 from low-temperature heat recovery, which will be described later. Water 505 collected in a water collection hole 504 of the high-pressure washer 502 is sent to a bleed water conduit 507 by a conveying means 506. Excess condensate 508 that is no longer needed as feed water 503 is also sent to the bleed water conduit 507. The purified syngas 509 produced in the high-pressure washer 502 is supplied to a first heat exchanger 518 downstream of the high-pressure washer 502. The term conveying means in this specification is understood to mean a pump, a compressor, or both. The high pressure washing device 502 can simultaneously clean the raw syngas 301 and control the moisture content of the purified syngas 509 .

[0059] The torrefied syngas 401 produced in the torrefaction gas treatment device 400 is sent to the saturator 510 by a conveying means 511. The torrefied syngas 401 is compressed by the conveying means 511, preferably to a pressure of 40 bar. The conveying means 511 may include multiple compressors with intercoolers, thereby subjecting the torrefied syngas 401 to multiple stages of intercooling and compression. Similarly, the purge gas 602 from the gas purification device 600 is also sent to the saturator 510 by a conveying means 512. The purge gas 602 is compressed by the conveying means 512, preferably to a pressure of 40 bar. The conveying means 512 may include multiple compressors with intercoolers, thereby subjecting the purge gas 602 to multiple stages of intercooling and compression. The saturator 510 is a conventional wet scrubber, and treated water 513 is supplied from a low-temperature heat recovery device 524 (described later) via a conveying means 514. Water 515 collected in water collection hole 516 of saturator 510 is used as treated water in low-temperature heat recovery unit 524, which will be described later. Saturator 510 mixes torrefied synthesis gas 401 and purge gas 602, and simultaneously adds moisture to the resulting saturator product gas 517. The moisture content of saturator product gas 517 can be controlled depending on the operating parameters of the saturator, namely, in particular, the water flow and water temperature.

[0060] Saturator tower product gas 517 is fed to first heat exchanger 518 along with purified syngas 509. In first heat exchanger 518, energy is transferred from hot CO2 shift reactor tail gas 519 to purified syngas 509 and saturator tower product gas 517, which are combined downstream of first heat exchanger 519 to form mixed syngas stream 520. The heat exchange in first heat exchanger 518 heats purified syngas 509 and purified gas stream 517 while cooling each hot CO2 shift reactor tail gas 519. Saturator tower 510 is preferably operated so that mixed syngas stream 520 has a steam to carbon monoxide molar ratio of 2.0 to 3.0, preferably 2.4 to 2.6, and particularly about 2.5.

[0061] The mixed syngas stream 520 is fed downstream of the first heat exchanger 518 to a high temperature CO shift reactor 521 where the shift reaction described above occurs. The high temperature CO shift reactor off-gas 519 has a reduced water / steam and carbon monoxide content and an increased hydrogen (H) content compared to the mixed syngas stream 520. The high temperature CO shift reactor off-gas 519 is directed through multiple heat exchangers, including the first heat exchanger 518, to reduce its temperature, as described below, to a low temperature CO shift reactor 522 where the CO shift reaction described above occurs. The low temperature CO shift reactor off-gas 523 has an increased hydrogen (H) content compared to the high temperature CO shift reactor off-gas 519 entering the low temperature CO shift reactor 522.

[0062] The low-temperature CO2 shift reactor off-gas 523 is directed downstream of the low-temperature CO2 shift reactor 522 through a low-temperature heat recovery unit 524, where the heat contained in the low-temperature CO2 shift reactor off-gas 523 is used to raise the temperature of multiple water streams. After entering the low-temperature heat recovery unit 524, the low-temperature CO2 shift reactor off-gas 523 is subsequently directed through a second heat exchanger 525, a third heat exchanger 526, a fourth heat exchanger 527, a fifth heat exchanger 528, and a sixth heat exchanger 529. While passing through these heat exchangers 524, 525, 526, 527, 528, and 529, the temperature of the low-temperature CO2 shift reactor off-gas 523 gradually decreases before it leaves the low-temperature heat recovery unit 524 as synthesis gas stream 530, optionally passing through an air cooler 531 if necessary. This syngas stream 530 is then fed to the gas purification system 600 as described above.

[0063] In the first, the second heat exchanger 525, the heat content of the synthesis gas stream 530 is used to heat the feed water 508 used in the gasifier 300. This water 508 can thus be heated, for example, to 158°C to 205°C. In the second, third heat exchanger 526, water is heated that can be used, for example, to generate high-pressure steam. The water is typically heated to 155°C to 200°C. In the third, fourth heat exchanger 527, the process water 513 is typically heated to 135°C to 158°C and used in the saturation tower 510. This water can then be used as the feed water 508, especially after passing through the second heat exchanger 525. In the fourth heat exchanger 527, the low-temperature CO2 shift reactor exhaust gas 523 is cooled below its dew point, so that a large amount of condensation heat is released and used for the respective heat transfer. In the fourth fifth heat exchanger 528, boiler feed water 536 is heated, typically to between 35°C and 155°C, and is preferably used to generate high pressure steam. In the fifth sixth heat exchanger 529, water is heated, typically to between 25°C and 135°C, for use in gasifying the carbonized pellets 201 in the gasifier 300.

[0064] The feed water 508 for the gasifier 300 is at least a portion of the water 515 collected at the water collection hole 519 of the saturator 510, as described above. The water 515 collected at the water collection hole 516 of the saturator 510 enters the fourth heat exchanger 527. Water 521 from a wastewater treatment device (not shown) may be mixed with the water 515 after passing through the sixth heat exchanger 529. Downstream of the second heat exchanger 527, the heated fourth heat exchanger effluent stream 533 is partly used as treated water 513 from low-temperature heat recovery in the saturator 510, and partly guided through the second heat exchanger 525, where it is used partly as condensate 508, partly as feed water 503 for the high-pressure washer 502, and partly as treated water for the torrefaction unit 200. A further portion of the water downstream of the sixth heat exchanger 529 is used as condensate 534, for example to be supplied to a water stripper. Other water, such as external high-pressure boiler feed water 535 from applications external to the plant 1, is guided through the fifth heat exchanger 528 and is partly used as boiler feed water 536, for example to the gasifier 300, for low-pressure steam generation, torrefaction plant 200, etc. Another portion of the boiler feed water 535 is guided downstream of the fifth heat exchanger 528 through the second heat exchanger 526 and then passes through a seventh heat exchanger 537.

[0065] The CO shift unit 500 as part of a plant 1 for converting solid waste to a product gas stream containing hydrogen allows low temperature thermal energy in the low temperature heat recovery unit 524 to be used in an energy efficient manner to heat the treated water stream used in the plant 1.

[0066] 7 shows gas purification unit 600 in more detail. The output of CO shift unit 500, shifted syngas 501, is introduced into gas purification unit 600 and subsequently passes through hydrogen sulfide adsorption unit 603 and carbon dioxide adsorption unit 604. Shifted syngas 501 then passes through pressure swing adsorption unit 605, which generates a hydrogen-rich product gas stream 601 having a hydrogen content of at least 99.5% by volume. Preferably, pure hydrogen is generated. Often, a single adsorber of pressure swing adsorption unit 605 is purged with hydrogen, generating purge gas 602.

[0067] The hydrogen sulfide recovered by the hydrogen sulfide adsorption means 603 is used to produce sulfur 606 by the Claus process. The carbon dioxide 607 adsorbed by the carbon dioxide adsorption means 603 can be extracted therefrom and used for other processes.

[0068] The method and plant 1 for converting solid recovered fuel pellets 117 made from municipal solid waste 103 allows for the conversion of municipal solid waste 103 into hydrogen at high yields, instead of landfilling or incinerating the municipal solid waste 103. The hydrogen-rich product gas stream 601 can be used as a feedstock for chemical reactions or can be used to store energy in a releasable manner. [Explanation of symbols]

[0069] 1. Plant for converting solid waste into gas containing hydrogen 100 Pelletizing equipment 102 Crusher 103 Solid Waste 104 Crushed solid waste 105 First metal removal device 106 Iron Residue 107 Dryer 108 Water 109 Second Metal Removal Device 110 Metal residue 111 Further residue 112 Gravity separator 113 Material flow before cleaning 114 First Crusher 115 Pulverized Material Flow 116 Pellet press 117 Solid Recovered Fuel Pellets 118 Kiln 119 Washing Tower 120 Heat Pump 121 Radiator 122 Dryer air supply port 123 Radiator air intake 124 Radiator exhaust port 125 Kiln air intake 126 Kiln exhaust port 127 Washing tower air intake 128 Washing tower exhaust outlet 129 Dryer exhaust vent 130 Recirculation path 131 Washing tower outlet 132 First heat pump inlet 133 First heat pump outlet 134 Washing tower water inlet 135 Second heat pump outlet 136 Radiator water inlet 137 Radiator drain 138 Second heat pump inlet 139 Second Magnet 200 Torrefaction device 201 Carbonized pellets 202 Torrefied Gas 203 Furnace 204 Second Crusher 205 Third Metal Removal Device 206 Metal residue 207 Coarsely crushed carbonized pellets 208 Third Crusher 209 Finely ground carbonized pellets 300 Gasifier 301 Unprocessed Syngas 302 Entrained flow gasifier 303 Feedstock 304 Biomass 305 Fourth Crusher 306 Finely ground biomass 307 Oxygen-rich gas stream 308 Intermediate Gas 309 Quenching Zone 310 Rapid cooling water 311 Slag 312 Unprocessed Syngas 313 Water washing cooling tower 314 Water 315 Excessive bleed water 316 Makeup water 400 Torrefaction Gas Treatment Equipment 401 Syngas 402 Combustion chamber 403 Fuel Gas 404 Oxygen-rich gas stream 405 Combustion chamber outlet 406 Recycled Syngas 407 Syngas 408 Mixing room 409 Quenched Syngas 410 Heat Recovery System 411 Heat medium 412 Boiler feed water 413 High-pressure steam 414 Fourth Heat Exchanger 415 Low Pressure Steam 416 Superheated low pressure steam 417 Wet Cleaning System 418 Used cleaning water 419 Water collection hole 420 Purified Syngas 421 Tip 422 2-stage water washing cooling tower 423 Compressor 424 Remaining portion of purified syngas 425 Water collection hole 426 Cleaning water 427 Heat Pump 428 First paragraph 429 Second paragraph 430 Air Cooler 431 Excessive washing water 432 Makeup water 433 Bleed Water 434 Syngas transport means 435 Flare 436 First Inlet 437 Second Inlet 438 Third Inlet 439 Quenching Zone 440 Quenching zone inlet 441 First Heat Exchanger 442 Second Heat Exchanger 443 Superheater 500 CO shift device 501 Shift Syngas 502 High-pressure cleaning equipment 503 Supply water 504 Water collection hole 505 Water 506 Transportation 507 Bleed water conduit 508 Condensed water 509 Purified Syngas 510 Saturation Tower 511 Transportation 512 Transportation 513 Treated water from low-temperature heat recovery 514 Transportation 515 Water 516 Water collection hole 517 Saturated tower product gas 518 First Heat Exchanger 519 High-Temperature CO Shift Reactor Exhaust Gas 520 Mixed Hot Syngas Stream 521 High-Temperature CO Shift Reactor 522 Low-Temperature CO Shift Reactor 523 Low-temperature CO shift reactor exhaust gas 524 Low-temperature heat recovery equipment 525 Second Heat Exchanger 526 Third Heat Exchanger 527 Fourth Heat Exchanger 528 Fifth Heat Exchanger 529 6th Heat Exchanger 530 Syngas Stream 531 Air Cooler 532 Wastewater treatment equipment 533 Fourth heat exchanger drain stream 534 Condensate 535 High pressure boiler feed water 536 Boiler feed water 537 7th Heat Exchanger 538 Saturated tower product gas 600 Gas Purification Equipment 601 Hydrogen-rich product gas 602 Purge gas 603 Hydrogen sulfide adsorption means 604 Carbon dioxide adsorption means 605 Pressure Swing Adsorption Means 606 Sulfur 607 Carbon Dioxide

Claims

1. 1. A method for processing solid recovered fuel pellets (117), comprising: a) torrefying the pellets (117) at a torrefying temperature of 250 to 300°C to produce carbonized pellets (201) and torrefying gas (202); b) crushing the carbonized pellets (201) in a first crushing step to form coarsely crushed carbonized pellets (207); c) removing metal residues (206) from the coarsely pulverized carbonized pellets (207); d) pulverizing the coarse carbonized pellets (207) into finely pulverized carbonized pellets (209); e) gasifying the pulverized carbonized pellets (209) to raw synthesis gas (301) in an entrained flow gasification process; f) subjecting the raw synthesis gas (301) to a CO shift reaction to produce a shifted synthesis gas (501); g) removing carbon dioxide and hydrogen sulfide from the shifted synthesis gas (501) to produce synthesis gas; h) generating a hydrogen-rich product gas stream (601) by purifying said synthesis gas; A method comprising:

2. 10. The method of claim 1, The torrefied gas (202) generated in step a) is pyrolyzed to generate torrefied synthesis gas (401), The torrefied syngas (401) is mixed with the raw syngas (301) generated in step e) before step f). method.

3. 3. The method of claim 1 or 2, In step b), the carbonized pellets (201) are crushed to a particle size of 10 mm or less. method.

4. The method according to any one of claims 1 to 3, In step c), the metal residues (206) are removed using eddy current techniques. method.

5. The method according to any one of claims 1 to 4, In step d), the coarsely pulverized carbonized pellets (207) are pulverized to a particle size of 500 μm [micrometers] or less. method.

6. The method according to any one of claims 1 to 5, In step g), carbon dioxide (CO ) is adsorbed from the synthesis gas. ２ ) and hydrogen sulfide (H ２ S) is removed method.

7. The method according to any one of claims 1 to 6, In step h), hydrogen is separated from the synthesis gas using a pressure swing adsorption system to produce a hydrogen-rich product gas stream (601) and a purge gas (602). method.

8. 8. The method of claim 7, At least a portion of the purge gas (602) is fed to the CO shift reaction in step e). method.

9. 9. The method of claim 7 or 8, A portion of the purge gas (602) is used as fuel gas. method.

10. 1. A plant (1) for processing solid recovered fuel pellets (117) into a hydrogen-rich product gas stream (601), comprising: a torrefaction device (200) for torrefying the solid recovered fuel pellets (117) into carbonized pellets (201); a second crusher (204) for crushing the carbonized pellets (201) into coarsely crushed carbonized pellets (207); a third metal removal device (205) including an eddy current for removing metal residues (206) from the coarsely pulverized carbonized pellets (207); a third crusher (208) for crushing the coarsely crushed carbonized pellets (207) into finely crushed carbonized pellets (209); a gasification system (300) comprising an entrained-flow gasification furnace (302) for gasifying the pulverized carbonized pellets (209) into raw synthesis gas (301); a CO shift unit (500) for performing a CO shift reaction on the raw synthesis gas (301) to produce a shifted synthesis gas (501); A gas purification device (600), comprising: adsorption means (603, 604) for removing carbon dioxide and hydrogen sulfide from the shifted synthesis gas (501); a hydrogen separator for separating hydrogen from the purge gas (602) to generate a hydrogen-rich product gas stream (601); A gas purification device (600) comprising: A plant equipped with:

11. 11. The plant of claim 10, The torrefaction gas treatment device (400) is further provided for pyrolyzing the torrefaction gas (202) that can be generated in the torrefaction device (200). plant.

12. 12. A plant according to claim 10 or 11, The hydrogen separator comprises a pressure swing adsorption means (605). plant.

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