Granulation apparatus for producing solid recovered fuel particles and use thereof in torrefaction

Abstract

The granulation apparatus (100) according to the present application allows for the production of solid recovered fuel pellets from municipal solid waste without the need to separate the constituents of the municipal solid waste prior to starting the granulation process. Thus, a larger amount of municipal solid waste can actually be used for the production of solid recovered fuel pellets. The granulation apparatus (100) and method according to the present application can be used, inter alia, for the production of solid recovered fuel pellets which can be used for the production of a synthesis gas rich in hydrogen and / or carbon dioxide by treating the torrefied solid recovered fuel pellets with a subsequent gas.

Description

Technical Field

[0001] The subject of the invention is a method and an apparatus for producing solid recovered fuel particles from municipal solid waste and their use in torrefaction. Background Art

[0002] Municipal solid waste (MSW) is generated worldwide and must be treated. Furthermore, the products produced by incineration, such as fly ash, bottom ash, gypsum, and activated coal laden with heavy metals and / or dioxins, pose further challenges for their further use and / or disposal. Furthermore, waste-to-energy efficiency—the amount of calorific value transferred to thermal energy—is low, typically ranging from 20 to 25%. US 2011 / 021434 A1 discloses a method for producing fuel pellets from municipal waste and using them as fuel.

[0003] Alternatively, alternatives to incineration and landfilling of municipal solid waste have been discussed, primarily relying on the production of solid recovered fuel (SRF) pellets from the municipal solid waste to allow for further processing. However, the production of these pellets must take into account various legislative restrictions regarding chlorine content, ash content, heavy metal content, and respective calorific values, as outlined in the European standard EN 15359:2011. To meet this standard, for example, a portion of the municipal solid waste is typically separated to meet the chlorine restrictions, for example by separating polyvinyl chloride (PVC) and finer components (typically higher in heavy metals, moisture, ash, and biogenic components). Consequently, up to 40 weight percent (wt.%) of the municipal solid waste is lost to the production of SRF pellets. Furthermore, the required separation technology requires considerable technical effort and investment.

[0004] Based on this, it is an object of the present invention to improve the technology for producing solid recovered fuel particles from municipal solid waste. Summary of the Invention

[0005] The method for processing municipal solid waste into solid recovered fuel particles without cleaning out chlorine-containing materials and subsequently torrefying the particles according to the present invention comprises the following steps:

[0006] a) providing solid waste including municipal solid waste;

[0007] b) shredding whole solid waste into shredded solid waste;

[0008] c) applying a magnetic field to the shredded solid waste to remove ferromagnetic particles;

[0009] d) drying shredded solid waste;

[0010] e) eddy current separation of non-ferrous metals from shredded solid waste;

[0011] f) removing additional residues through a density classifier to produce a pre-cleaned material stream;

[0012] g) grinding the pre-cleaned material stream into a ground material stream;

[0013] h) pressing the milled material stream into solid recovered fuel particles; and

[0014] The solid recovered fuel particles are used in torrefaction at a temperature of 250°C to 300°C.

[0015] Steps a) to h) are performed chronologically. The solid waste in step a) comprises municipal solid waste. The shredding in step b) results in a maximum particle size of 80 mm. The entire solid waste is shredded, and no components are separated before the process begins. In particular, high-chloride components, such as PVC, are not separated in the shredded solid in step c). Furthermore, finer components, which are often high in heavy metals, moisture, ash, and biogenic components, are not separated upstream of the shredding step. In step c), a magnetic field is applied, for example, by an electromagnet. This magnetic field removes ferromagnetic particles, particularly ferrous metal particles, from the shredded solid waste.

[0016] Drying step d) reduces the moisture content of the solid recovered fuel particles, which is beneficial for further use of the solid recovered fuel particles, such as in torrefaction and gasification processes to produce hydrogen-rich syngas and / or a pure carbon dioxide stream as feedstock for other processes. The drying heat in step d) is preferably provided by the heat of evaporation from moisture-laden waste gas recycled through a scrubber and an electric heat pump system (such as disclosed in EP 3184946 A). In particular, the drying step is controlled so as to produce a moisture content of 10% by weight or less in the shredded solid waste downstream of the drying step.

[0017] In step e), an eddy current separator in combination with a second magnet is used to separate non-ferrous metals, in particular metals based on copper, aluminum and zinc. Other residues from step f) include, for example, minerals such as glass, stone and / or ceramics and other materials such as stainless steel.

[0018] The grinding in step g) is preferably performed using a low-RPM shredder. The grinding process in step g) preferably results in a maximum particle size of 30 mm, particularly 25 mm, in the ground material stream. This ensures reliable compaction of the solid recovered fuel particles in step h).

[0019] In step h), reliable solid recovered fuel particles are produced due to the precise moisture content and the precise particle size of the ground material stream.

[0020] The solid recovered fuel particles produced in steps a) to h) can be used in particular for torrefaction and gasification. With the moisture content provided in step d) a high output torrefaction and gasification can be ensured. That is, municipal solid waste with a high hydrogen and / or high carbon dioxide yield can be used in the subsequent torrefaction and gasification of the solid recovered fuel particles.

[0021] A further use of the solid recovered fuel particles in a torrefaction process at temperatures of 250 °C to 300 °C leads to a substoichiometric oxidation of the solid recovered fuel particles, i.e. a carbonization process of the solid recovered fuel particles. The resulting carbonized particles are subsequently subjected to a dry feed gas stream gasification, while the resulting gas is treated separately, in particular using the atmospheric thermal cracking process. The term "torrefaction" is understood as a thermochemical treatment of the solid recovered fuel particles at temperatures of 250 °C to 320 °C. It is carried out at atmospheric pressure and without the addition of further oxygen, e.g. without the provision of air. During the torrefaction process, the water contained in the solid recovered fuel particles evaporates as do the volatiles contained in the SRF particles. The biopolymers contained in the SRF particles partially decompose with the release of volatiles. The products of the torrefaction process are carbonized particles and a torrefaction gas.

[0022] The substoichiometric oxidation of the solid recovered fuel particles inhibits the formation of oxides from heavy metals. Instead, water-insoluble heavy metal sulfides are produced, while the formation of more volatile and well-soluble metal oxides and metal chlorides is advantageous in an oxidizing atmosphere. Thus, the chlorine, ash and heavy metal content is less critical in the present process. Thus, a front-end separation of high-chlorinated and heavy metal compounds can be avoided without affecting the environment.

[0023] According to a preferred embodiment, in step d) the moisture content of the shredded solid waste is adjusted to 5 to 10 wt.%. A moisture content in this range allows a stable pressing step and allows a stable and reliable torrefaction of the solid recovered fuel particles.

[0024] According to a preferred embodiment, in step d) the drying is carried out in a kiln which is heated by air which is guided downstream of the kiln through a scrubbing tower which is thermally connected to a heat pump for energy recovery. This allows a stable and energy-efficient heating of the kiln and thus a well-defined drying process for the shredded solid waste with a well-defined moisture content downstream of the kiln.

[0025] According to another aspect, a granulation apparatus for the treatment of solid waste comprising municipal solid waste into solid recovered fuel particles is presented, comprising the following elements:

[0026] A) a shredder for shredding the entire solid waste into shredded solid waste;

[0027] B) a first metal removal unit comprising a magnet;

[0028] C) dryers for drying shredded solid waste;

[0029] D) a second metal removal unit comprising an eddy current separator and a second magnet;

[0030] E) Density classifier;

[0031] F) grinding machines; and

[0032] G) Granulator;

[0033] The elements are arranged and connected such that the solid waste can be conveyed through the elements A) to G) in alphabetical order.

[0034] According to the invention, the pelletizing plant is part of a plant further comprising a torrefaction unit for substoichiometric oxidation of pellets that may be produced in a pelletizer.The pelletizing plant processes solid waste, including municipal solid waste, into solid recovered fuel pellets according to the method of the invention.

[0035] According to a preferred embodiment, the dryer comprises a kiln which is heated by air which, downstream of the kiln, is led through a scrubbing tower which is thermally connected to a heat pump for energy recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] It should be noted that the individual features specified in the claims can be combined with one another in any desired technically reasonable manner to form further embodiments of the present invention. This specification, particularly in conjunction with the accompanying drawings, further explains the present invention and specifically describes preferred embodiments of the present invention. The present invention and particularly preferred variations of the technical field will now be explained in more detail 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. In the drawings:

[0037] Figure 1 A view showing a granulation apparatus;

[0038] Figure 2 An example of a granulation apparatus included in a method for producing hydrogen from solid waste is shown; and

[0039] Figure 3 An example of a dryer used in a granulation apparatus is shown. DETAILED DESCRIPTION

[0040] according to Figure 1The granulation apparatus 100 includes a shredder 102. Solid waste 103 (e.g., municipal solid waste (MSW) and / or biomass) is supplied to the shredder 102, generating shredded solid waste 104. The shredded solid waste 104 is then conveyed by a first metal removal unit 105 including a magnet to remove iron residues 106 from the shredded solid waste 104. Thereafter, the shredded solid waste 104 is supplied to a dryer 107, where water 108 is removed from the shredded solid waste 104. The shredded solid waste 104 is then conveyed to a second metal removal unit 109 for removing metal residues 110 from the shredded solid waste 104. The second metal removal unit 109 includes a second magnet 139 for further removing ferrous metal and an eddy current for removing non-ferrous metal.

[0041] Afterwards, the minerals and stainless steel are removed as additional residue 111 in a density classifier 112. In the density classifier 112, high-density residues such as stainless steel particles, which cannot be removed by magnets or eddy currents, are removed based on the density difference between the additional residue 111 and the remaining portion of the shredded solid waste 104. The same applies to minerals such as glass or stone, which are removed from the remaining portion of the shredded solid waste 104 due to their density difference. A preferred example of the density classifier 112 is, for example, an air classifier.

[0042] After the removal of the additional residues 111, the shredded solid waste 104 is freed from ferrous metals (e.g., ferrous residues 106 and metallic residues 110), non-ferrous metals, stainless steel, and minerals (e.g., additional residues 111), as well as moisture in the form of water 108. The remaining portion of the shredded solid waste 104 is essentially identical to the solid waste 103 input to the granulation plant 100. In particular, in the granulation plant 100 of the present invention, it is not necessary to remove, for example, finer components of the solid waste 103 or chlorine-containing materials such as polyvinyl chloride (PVC). This means that the ratio of the mass of the pre-cleaned material stream 113 present downstream of the first metal removal unit 105, the second metal removal unit 109, and the density classifier 112 to the mass of the solid waste 103 input to the granulation plant 100 is greater than with known methods.

[0043] The pre-cleaned material stream 113 is then ground in a grinder 114, in particular to an average particle size of less than 25 mm, to produce a ground material stream 115. Subsequently, the ground material stream 115 is introduced into a pelletizer 116 to produce solid recovered fuel particles 117.

[0044] Figure 2Schematically shows a pelletizing plant 100, wherein solid recovered fuel particles 117 are provided to a machine 1 for converting solid waste into a gas comprising hydrogen, particularly into a synthesis gas comprising hydrogen and hydrogen. After particles are prepared from solid waste such as municipal solid waste 103 and / or biomass in the pelletizing plant 100, the corresponding particles 117 are transported to the machine 1 and provided to a torrefaction unit 200, in which the particles are substoichiometrically oxidized at a temperature of 250°C to 300°C. The torrefaction of the particles produces carbonized particles 201, which are gasified in a gasification unit 300. Another product of the torrefaction is a torrefaction gas 202, which is provided to a torrefaction gas treatment unit 400. The products of the torrefaction gas treatment unit 400 and the gasification unit 300 are both synthesis gases 301, 401 comprising water vapor, carbon monoxide and hydrogen. The two syngases 301 and 401 are introduced into a CO2 shift unit 500, where carbon monoxide (CO) reacts with water vapor (H2O) to produce carbon dioxide (CO2) and hydrogen (H2). A shifted syngas 501 with an increased hydrogen content compared to the syngases 301 and 401 is produced in the CO2 shift unit 500 and transferred to a gas purification unit 600, which separates a hydrogen-rich product gas stream 601, preferably having a hydrogen content of 99.5% by volume or greater, from the purified gas 602. The pelletizing plant 100 is preferably located off-site, that is, at a separate location from the machine 1 for converting solid waste into a gas containing hydrogen. An off-site pelletizing plant 100 is advantageous because it reduces the mass of municipal solid waste, as typically approximately 30 to 35% by weight of the municipal waste's water content is evaporated. This significantly reduces the mass required for transport. Furthermore, because the pelletizing plant 100 allows for the centralized production of solid recovered fuel pellets and subsequent delivery of these pellets to the desired chemical processing plant, the footprint of the chemical processing plant (e.g., plant 1) can be reduced.

[0045] Figure 3 Shown in Figure 1 An example of a dryer 107 used in the granulation apparatus 100 of FIG. The dryer 107 for drying the shredded solid waste 104 includes a kiln 118 for containing the shredded solid waste 104, a scrubber 119, which may also be referred to as a scrubber, a heat pump 120, and a radiator 121. Air is drawn into the dryer 107 through a dryer air inlet 122, which is generally in fluid communication with the atmosphere. The drawn air may be drawn through Figure 3The air conveyed into the radiator 121 is heated in the radiator 121 and exits the radiator 121 via a radiator air outlet 124. The heated air is conveyed towards the kiln 118, wherein a kiln air inlet 125 is in fluid communication with the radiator air outlet 124 via a duct. The shredded solid waste 104 is arranged within the kiln 118 and the air conveyed into the kiln 118 flows through the shredded solid waste 104 and exits the kiln 118 via a kiln air outlet 126. The temperature of the air entering the kiln 118 during the drying process is about 80 °C, wherein the air exiting the kiln 118 exhibits a temperature of about 45 °C. The relative humidity of the air exiting the kiln 118 is about 100 %.

[0046] The kiln 118 is in fluid communication with the washing tower 119, wherein the kiln air outlet 126 is in fluid communication with a washing tower air inlet 127. Within the washing tower 119, the air is in close contact with cold water. Thus, the humid and warm air is cooled, so that the humidity of the air is condensed out and the latent heat is converted into the sensible heat of the water. This results in heating the water from about 18 °C to about 25 °C to 28 °C and cooling the air from about 28 °C to 32 °C to about 22 °C to 24 °C. The cooled air exits the washing tower 119 through a washing tower air outlet 128, which is in fluid communication with a dryer air outlet 129.

[0047] The air exiting the washing tower 119 can also be conveyed to the dryer air inlet 122 via a recirculation line 130, so that the washing tower air outlet 128 is in fluid communication with the dryer air inlet 122. The respective arrangement results in a lower energy consumption of the device 100. The recirculation line 130 is not necessarily comprised in the device 100 and can be omitted.

[0048] With regard to the 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 washing tower 119 is located downstream of the kiln 118, and the dryer air outlet 129 is located downstream of the washing tower 119.

[0049] The washing tower 119 further comprises a washing tower water outlet 131 in fluid communication with a first heat pump inlet 132. A first heat pump outlet 133 is in fluid communication with a washing tower water inlet 134. Thus, the water is circulated between the washing tower 119 and the heat pump 120. The water can be conveyed by a pump, not shown in the figure. Figure 3 The washing tower 119 further comprises a washing tower water outlet 131 in fluid communication with a first heat pump inlet 132. A first heat pump outlet 133 is in fluid communication with a washing tower water inlet 134. Thus, the water is circulated between the washing tower 119 and the heat pump 120. The water can be conveyed by a pump, not shown in the figure.

[0050] Water is heated in the scrubber 119 by air entering the scrubber 119 through the scrubber air inlet 127, and the heated water leaves the scrubber 119 through the scrubber water outlet 131 and enters the heat pump 120 through the first heat pump inlet 132. The thermal energy of the water entering the heat pump 120 is then transferred to another heat cycle implemented 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 through the first heat pump outlet 133 has a temperature of approximately 18°C.

[0051] The first heat pump outlet 133 is in fluid communication with the scrubber water inlet 134. Therefore, water cooled in the heat pump 120 enters the scrubber 119 via the scrubber water inlet 134. Thus, a heat cycle is achieved between the scrubber 119 and the heat pump 120, wherein the heat energy of the water leaving the scrubber 119 is transferred via the heat pump 120 to a second heat cycle between the heat pump 120 and the radiator 121.

[0052] The second heat pump outlet 135 is fluidically and thermally connected to the radiator water inlet 136, and the radiator water outlet 137 is fluidically and thermally connected to the second heat pump inlet 138. Figure 3 A pump (not shown) is used to transfer heat between the heat pump 120 and the radiator 121. Therefore, a second heat cycle is achieved between the heat pump 120 and the radiator 121, and the heat energy of the water discharged from the scrubber 119 is transferred to the radiator 121 through the heat pump 120, and is transferred to the air flowing through the radiator 121 from the radiator air inlet 123 to the radiator air outlet 124.

[0053] The pelletizing apparatus 100 according to the present invention allows for the production of solid recovered fuel pellets from municipal solid waste without the need to separate the components of the municipal solid waste prior to the pelletizing process. Consequently, larger quantities of municipal solid waste can be used to produce solid recovered fuel pellets. The pelletizing apparatus 100 and method according to the present invention can be used, in particular, to produce solid recovered fuel pellets that can be used to produce hydrogen- and / or carbon dioxide-rich synthesis gas by torrefying the solid recovered fuel pellets with subsequent gas treatment.

[0054] Reference numerals

[0055] 1 Machine for converting solid waste into gas containing hydrogen

[0056] 100 Granulation Equipment

[0057] 102 Shredder

[0058] 103 Solid waste

[0059] 104 Shredded solid waste

[0060] 105 First Metal Removal Unit

[0061] 106 Iron residues

[0062] 107 Dryer

[0063] 108 Water

[0064] 109 Second Metal Removal Unit

[0065] 110 Metal Residues

[0066] 111 Additional Residues

[0067] 112 Density Classifier

[0068] 113 Pre-cleaned material flow

[0069] 114 grinder

[0070] 115 Grinded material flow

[0071] 116 Pellet Press

[0072] 117 Solid recovered fuel pellets

[0073] 118 Kiln

[0074] 119 Scrubber

[0075] 120 heat pump

[0076] 121 Radiator

[0077] 122 Dryer air inlet

[0078] 123 Radiator air intake

[0079] 124 Radiator air outlet

[0080] 125 kiln air inlet

[0081] 126 Kiln air outlet

[0082] 127 Scrubber air inlet

[0083] 128 Scrubber outlet

[0084] 129 Dryer air outlet

[0085] 130 Recirculation line

[0086] 131 Scrubber Outlet

[0087] 132 First heat pump inlet

[0088] 133 First heat pump outlet

[0089] 134 Scrubber water inlet

[0090] 135 Second heat pump outlet

[0091] 136 Radiator water inlet

[0092] 137 Radiator outlet

[0093] 138 Second heat pump inlet

[0094] 139 Second Magnet

[0095] 200 drying units

[0096] 201 Carbonized particles

[0097] 202 torrefaction gas

[0098] 300 Gasification Unit

[0099] 301 First Synthesis Gas Stream

[0100] 400 Torrefaction Gas Processing Unit

[0101] 401 Synthesis Gas

[0102] 500 CO conversion unit

[0103] 501 Shift Synthesis Gas

[0104] 600 Gas Purification Unit

[0105] 601 Hydrogen-rich product gas

[0106] 602 Purified Gas

Claims

1. A method for processing municipal solid waste into solid recovered fuel particles (117) without cleaning out chlorine-containing materials and subsequently torrefying the solid recovered fuel particles (117), the method comprising the following steps: a) providing solid waste including municipal solid waste (103); b) shredding the entire solid waste (103) into shredded solid waste (104); c) applying a magnetic field to the shredded solid waste (104) to remove ferromagnetic particles; d) drying the shredded solid waste (104); e) eddy current separation of non-ferrous metals from the shredded solid waste (104); f) removing further residue (111) via a density classifier (112) to produce a pre-cleaned material stream (113); g) grinding the pre-cleaned material flow (113) into a ground material flow (115); h) pressing the ground material stream (115) into solid recovered fuel particles (117); and The solid recovered fuel particles are used in a torrefaction process at a temperature of 250°C to 300°C.

2. The method according to claim 1, wherein In step d), the water content of the shredded solid waste (104) is adjusted to 5 to 10% by weight.

3. The method according to claim 1 or 2, wherein: In step d), the drying is carried out in a kiln (118) which is heated by air which is led downstream of the kiln (118) through a scrubbing tower (119) which is thermally connected to a heat pump (120) for energy recovery.

4. A device comprising a granulation device (100) for processing solid waste (103) including municipal solid waste into solid recovered fuel particles (117) according to the method according to any one of claims 1 to 3, the device comprising the following elements: A) a shredder (102), the shredder (102) being used to shred the entire solid waste (103) into shredded solid waste (104); B) a first metal removal unit (105), the first metal removal unit (105) comprising a magnet; C) a dryer (107), the dryer (107) being used to dry the shredded solid waste (104); D) a second metal removal unit (109), the second metal removal unit (109) comprising an eddy current separator and a second magnet (139); E) Density Classifier (112); F) a grinder (114); and G) Granulator (116); in, These elements are arranged and connected so that the solid waste (103) can be conveyed through these elements A) to G) in alphabetical order, and the device also includes a torrefaction unit (200) for substoichiometric oxidation of the solid recovered fuel particles (117) that can be produced in the pelletizer (116).

5. The device comprising a granulation device (100) according to claim 4, wherein The dryer (107) comprises a kiln (118) which is heated by air which is led downstream of the kiln (118) through a scrubber (119) which is thermally connected to a heat pump (120) for energy recovery.

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