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EP-4735392-A1 - DOWNDRAFT FIXED-BED GASIFICATION REACTOR ASSEMBLY FOR THE GASIFICATION OF SLUDGE

EP4735392A1EP 4735392 A1EP4735392 A1EP 4735392A1EP-4735392-A1

Abstract

The invention relates to a downdraft fixed-bed gasification reactor assembly (10) for the gasification of dewatered or partially dewatered sludge having a sludge dry solids content of at least 20%, which is introduced into a gasification reactor (12) through an inlet (16), the assembly comprising a gasification reactor (12) having: a drying zone for further drying the sludge; a pyrolysis zone for chemically converting the organic components into pyrolysis products; an oxidation zone for the partial oxidation of the pyrolysis products; and a reduction zone for the reduction of the pyrolysis products and oxidation products to form syngas and ash. The downdraft fixed-bed gasification reactor assembly is characterized in that the interior of the gasification reactor (12) is cylindrical and has a constant cross-section across the entire height, and in the area of the oxidation zone, lateral openings (22, 24) are provided in the wall of the gasification reactor (12), through which openings gaseous oxygen, air or another oxygen-containing gas can be guided into the oxidation zone.

Inventors

  • HABICHT, Fabian
  • HEINE, Nina

Assignees

  • Shit2Power GmbH

Dates

Publication Date
20260506
Application Date
20240625

Claims (17)

  1. 1. Downdraft fixed bed gasification reactor arrangement (10) for gasifying dewatered or partially dewatered sewage sludge with a dry matter content of at least 20%, which is introduced into a gasification reactor (12) via an inlet (16), with a gasification reactor (12) containing (a) a drying zone for further drying of the sewage sludge; (b) a pyrolysis zone for the chemical conversion of the organic components into pyrolysis products; (c) an oxidation zone for partial oxidation of the pyrolysis products, and (d) a reduction zone for reducing the pyrolysis and oxidation products into synthesis gas and ash, characterized in that (e) the interior of the gasification reactor (12) is cylindrical with a constant cross-section over its entire height; and (f) in the region of the oxidation zone, lateral openings (22, 24) are provided in the wall of the gasification reactor (12), through which gaseous oxygen, air or another oxygen-containing gas can be fed into the oxidation zone.
  2. 2. Reactor arrangement (10) according to claim 1, characterized in that a rotary valve or another air seal is arranged in the inlet region of the gasification reactor.
  3. 3. Reactor arrangement (10) according to one of the preceding claims, characterized in that a screw conveyor is provided which conveys the dewatered or partially dewatered sewage sludge into the gasification reactor.
  4. 4. Reactor arrangement according to one of the preceding claims, characterized in that the bottom of the gasification reactor comprises a permeable grid.
  5. 5. Reactor arrangement according to one of the preceding claims, characterized in that the openings (22, 24) for oxygen-containing gas are arranged at different heights.
  6. 6. Reactor arrangement according to one of the preceding claims, characterized in that a fan, a pump or other means for generating a negative pressure are provided at the lower end of the gasification reactor (12).
  7. 7. Reactor arrangement according to one of the preceding claims, characterized in that a housing (28, 40) is provided in which the gasification reactor is held, wherein between the outer wall of the gasification reactor (12) and the inner wall of the housing (28) a cavity (50) is formed through which the product gas generated in the gasification reactor can flow.
  8. 8. Reactor arrangement according to claim 7, characterized in that the housing (28) has an outlet (54) in the region of the cavity (50) through which the product gas produced can be discharged to the outside.
  9. 9. Reactor arrangement according to claim 7 or 8, characterized in that the housing (28) opens at the lower end into an ash collecting container (46).
  10. 10. Reactor arrangement according to one of claims 7 to 9, characterized in that the housing (28) has a cover (32) at the upper end and the gasification reactor (12) extends through the cover (32) upwards out of the housing (28).
  11. 11. Reactor arrangement according to one of claims 7 to 10, characterized in that the housing (28, 40) below the gasification reactor (12) has a closable opening (46) for a starter burner or a starter burner.
  12. 12. Reactor arrangement according to one of the preceding claims, characterized in that sensor ports (52) for sensors are provided in the wall and/or in a cover of the gasification reactor (12) and/or the housing (28, 40).
  13. 13. Reactor arrangement according to claim 12, characterized in that a control is provided which is supplied with the signals from sensors connected to the sensor ports (48, 52) and with which the amount of oxygen supplied through the lateral openings (22, 24) can be controlled in such a way that maximum energy can be generated.
  14. 14. Reactor arrangement according to one of the preceding claims, characterized by an outlet-side cyclone separator (58).
  15. 15. Module arrangement for constructing a reactor arrangement (10) according to one of the preceding claims, characterized in that the reactor arrangement (10) or parts of the reactor arrangement form modules which can be transported to the place of use by road-worthy vehicles.
  16. 16. Module arrangement according to claim 15, characterized in that the modules can be connected to connection interfaces which use quick-release fasteners, click fasteners, plug-and-play fasteners, bayonet fasteners or flanges which can be connected and detachable with conventional tools or without tools.
  17. 17. Process for processing sewage sludge comprising the steps: (a) drying the sewage sludge; and (b) gasifying the sewage sludge in a reactor arrangement according to one of claims 1 to 13; characterized in that (c) the amount of oxygen supplied through the side openings (22, 24) is controlled so that maximum energy is generated.

Description

patent application Downdraft fixed bed gasification reactor arrangement for the gasification of sewage sludge technical field The invention relates to a downdraft fixed bed gasification reactor arrangement for gasifying dewatered or partially dewatered sewage sludge with a dry matter content of at least 20%, which is introduced into a gasification reactor via an inlet, with a gasification reactor containing (a) a drying zone for further drying of the sewage sludge; (b) a pyrolysis zone for the chemical conversion of the organic components into pyrolysis products; (c) an oxidation zone for partial oxidation of the pyrolysis products, and (d) a reduction zone for reducing the pyrolysis and oxidation products into synthesis gas and ash. The invention further relates to a module arrangement for constructing such a reactor arrangement and a method for processing sewage sludge with the steps: (a) drying the sewage sludge; and (b) Gasification of the sewage sludge in such a reactor arrangement. Sewage sludge is a thin biomass. The raw sludge from a sewage treatment plant contains about 99% water and about 1% solids (TS content). These solids contain organic solids, heavy metals and critical ingredients, such as medicines. This composition distinguishes sewage sludge from uncontaminated biomass. Typically, the sewage sludge is disposed of and burned, for example, together with garbage or coal. For smaller sewage treatment plants, the energy contained in the sewage sludge has so far been too expensive due to the high investment costs. The sewage sludge is therefore transported to a distant disposal facility and disposed of there. The transport of sewage sludge required for this is labor- and energy-intensive and therefore expensive. It is therefore common practice to dry sewage sludge before transport. In addition to gravity thickening, in which the solids sink due to gravity, mechanical dewatering in a press or centrifuge is also known. Polymers can be used as flocculants, for example. Sewage sludge dewatered in this way has a water content of, for example, 70% to 75%. Dewatering can reduce the transport volume and thus the costs. State of the art In addition to the direct combustion of sewage sludge, there are a number of processes for gasifying sewage sludge. The gases produced can be used, for example, to generate electrical energy. Some of the sewage sludge remains as tar and ash, which must be disposed of in another way. Typically, the gasification or pyrolysis of the sewage sludge takes place in fluidized bed reactors. These are operated economically for population numbers of more than half a million inhabitants. An example of such a process with a fluidized bed reactor is disclosed in EP 3 214 155 B1. A pyrolysis reactor is connected upstream of the fluidized bed reactor, in which the sewage sludge is moved horizontally by a screw and pretreated at 600°C to 650°C with the exclusion of oxygen. The arrangement is comparatively complex and requires high investment and maintenance costs. Another example of a fluidized bed reactor is disclosed in EP 2 356 200 B1. WO 97/32 945 A1 discloses a smaller gasification plant with connection values of significantly less than half a million inhabitants, for example from 50,000 inhabitants. The disclosed gasification takes place in a continuously operable direct current fixed bed gasification reactor, which has an air or oxygen supply via an annular channel that is connected to the oxidation zone via a number of openings. In the area of the annular channel, the reactor cross-section is reduced, which leads to high temperatures. Pyrolysis takes place at approx. 1000°C. At this temperature, the ash melts and forms slag. The slag is removed from the gasification reactor using a specially designed slag separator and a discharge flap. This is complex. During discharge, the product gas flow is interrupted. DE10 2017 102 789 Al discloses the gasification of sewage sludge in a bulk material moving bed. The dry sewage sludge is mixed with a non-gasifiable material such as calcium oxide to form bulk material and gasified in a vertical shaft furnace. EPI 687 390 Bl discloses a process for the catalytic gasification of biomaterials. The reactor is conical in shape. This carries the risk of clogging with tar residues. EP 3 519 537 B1 discloses a gasifier for producing low-tar synthesis gas with a pyrolysis zone, an oxidation zone and a reduction zone. The gasifier has a perforated bottom with several openings, which is inclined. disclosure of the invention It is the object of the invention to provide a simple downdraft fixed bed gasification reactor arrangement of the type mentioned at the beginning, with which the sewage sludge can be used economically with a high energy yield through gasification even with smaller quantities of sewage sludge. According to the invention, the object is achieved in that (e) the interior of the gasification reactor is cylindrical with a constant cross-