Process for processing sludge to a granulate

• US 20040182953A1
• Filed: 03/19/2003
• Published: 09/23/2004
• Est. Priority Date: 03/19/2003
• Status: Abandoned Application

• Current Assignee: Innoplana Umwelltechnik AG
• Original Assignee: Innoplana Umwelltechnik AG
• Inventors: Knoer, Peter
• Application Number:
  US10/391,842
• Publication Number:
  US 20040182953A1
• Time in Patent Office: Days
• US Class Current: 241/23
• CPC Class Codes: B01J 2/20 by expressing the material, e.g. through sieves and fragmenting the extruded length
• CPC Class Codes: C02F 11/12 by de-watering, drying or thickening
• CPC Class Codes: C02F 11/13 by heating
• CPC Class Codes: C05F 7/00 Fertilisers from waste water, sewage sludge, sea slime, ooze or similar masses
• CPC Class Codes: C05G 5/12 Granules or flakes
• CPC Class Codes: F26B 1/00 Preliminary treatment of solid materials or objects to facilitate drying , e.g. mixing or backmixing the materials to be dried with predominantly dry solids F26B5/005 takes precedence
• CPC Class Codes: F26B 17/08 the belts being arranged in a sinuous or zig-zag path F26B17/026 takes precedence; superimposed tray conveyors F26B15/146
• CPC Class Codes: F26B 2200/18 Sludges, e.g. sewage, waste, industrial processes, cooling towers
• CPC Class Codes: F26B 25/002 for bulk goods F26B17/103 takes precedence
• CPC Class Codes: Y02A 40/20 Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses

Abstract

On processing pasty materials, the material is conveyed with a relatively high dry fraction of 40 to 75% through the holes (62) of the perforated plate (42) of a granulator, in that a feed element (50), forming with the perforated plate (42) a wedge-shaped gap space (61), strokes with its trailing edge (53) over the perforated plate (42). The material strands (63) pressed out of the holes (62) are cut off by a knife-like separating device (64) stroking over the discharge-side surface of the perforated plate (42). Thus, particles of a particularly small size can be produced with a relatively low energy cost from the sludge and without the granulator being blocked by a damming up of fibres, e.g. in the form of hair contained in the sludge.

Claims

1. Process for processing sludge, particularly sewage sludge from municipal sewage plants to a granulate of identical particle size, with pre-evaporation by heating the sludge, producing a granulate from the pre-evaporated material and afterdrying the granulate, the material being pre-evaporated to a dry fraction of more than 40% and fed during granulation through the holes of a perforated plate, wherein feeding through the holes (62) of the perforated plate (42) takes place by means of at least one feed element (50, 51, 52) which strokes over the feed-side surface of the perforated plate (42) and forms therewith a wedge-shaped gap space (61), so that the pressure for feeding through the perforated plate (42) is produced by the stroking movement in the wedge-shaped gap space (61), the material strands (63) forced out of the holes (62) being cut off by a knife-like separating device (64) stroking over the discharge-side surface of the perforated plate (42).

2. Process according to claim 1, wherein the material is granulated with a dry fraction of 40 to 75%.

3. Process according to claim 2, wherein the material is granulated with a dry fraction of 60 to 70%.

4. Process according to claim 1, wherein the feeding through the holes (62) of the perforated plate (42) takes place with an identical hole width in the range 2 to 4 mm.

5. Process according to claim 4, wherein the material strands (63) are cut off with a length of 2 to 4 mm.

6. Process according to claim 1, wherein the feed pressure in the wedge-shaped gap space (61) is formed in addition to a pressure with which the material is supplied to the at least one feed element (50, 51, 52), so that between the feed-side and discharge-side surface of the perforated plate (42) there is a pressure difference to which is added the supply pressure.

7. Process according to claim 1, wherein the cut off granulate particles are exposed to a heated gas flow on passing through a drop path leading to an afterdryer (4).

8. Process plant for performing the process according to claim 1 with a pre-evaporator (1) having an inlet duct (5) and an outlet duct (12), a granulator (3), which is connected by means of a conveyor (12, 2) to the pre-evaporator (1) and with an afterdryer (4) located below the granulator (3), which has at least one feed element (50, 51, 52) enclosed within its casing (30) and a perforated plate (42) provided with a feed-side and discharge-side surface, wherein the at least one feed element (50, 51, 52) extends from a trailing edge (53, 54, 55) engaging on the feed-side surface of the perforated plate (42) with a shallow angle (60), so that it forms with the surface of the perforated plate (42) a feed pressure-producing wedge gap (61), as well as a doctor blade-like separating device (64) engaging on the discharge-side surface of the perforated plate (42) for the separation of the granulate strands (63) from the perforated disk (42) and for a relative movement between the feed element and the perforated plate a drive is connected to one of these.

9. Process plant according to claim 8, wherein at least one feed element (50, 51, 52) is provided in rotor blade-like manner on a hub body (60) of a rotor (35) and engages with its radially extending trailing edge (53, 54, 55) on a circular perforated plate (42) surrounding with distance the driving shaft (36) of the rotor (35), a guide element (72) being arranged in baffle-like, fixed manner in the granulator casing (30) surrounding the rotor (35).

10. Process plant according to claim 9, wherein the at least one doctor blade-like separating device (64) engaging on the discharge-side surface of the perforated plate (42) is connected to a hub part (68), which is in driving connection with the driving shaft (36).

11. Process plant according to claim 10, wherein a cylindrical hub element (59) of a rotor (35) carrying feed elements (51, 51, 52) and the hub part (68) of the separating device (64) are axially displaceable on the driving shaft (36) counter to the pressure of a spring mechanism (56) surrounding the same, so that the feed element (50, 51, 52) and the separating device (64) engage on both sides of the perforated plate (42) under the pressure of said spring mechanisms (56).

12. Process plant according to claim 11, wherein the cylindrical hub element (59) of the rotor (35) and the hub part (68) of the separating device (64) are supported by a common tension sleeve (49) and are clamped between an end flange (69) of the tension sleeve (49) and the spring mechanism (56).

13. Process plant according to claim 10, wherein the cutting edge of the doctor blade-like, engaging separating device (64) is displaced in trailing manner relative to the trailing edge (53, 54, 55) of the feed element (50, 51, 52), so that the length of cut of the particles formed by cutting off is determined by the magnitude of the trailing distance.

14. Process plant according to claim 8, wherein the trailing distance corresponds to a length of cut of less than 5 mm.

15. Process plant according to claim 8, wherein the holes (62) of the perforated plate (42) have a uniform width of less than 5 mm.

16. Process plant according to claim 8, wherein the holes (62) of the perforated plate (42) have a uniform width of 3 mm.