Spray dryer with improved exhaust gas filtration system

Patent metadata

Field	Value
Publication number	US-10279359-B2
Application number	US-201615342726-A
Country	US
Kind code	B2
Filing date	Nov 3, 2016
Priority date	Nov 3, 2015
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

A spray dryer for drying liquid into powder including an elongated drying chamber, a spray nozzle assembly at an upper end of the drying chamber and a filter element housing and powder collection chamber at a lower end of the drying chamber. The filter element housing comprises a plurality of cylindrical filter elements supported from a wall of an exhaust chamber that communicates with an exhaust gas outlet of the filter element housing. In one embodiment, the filter element housing includes an inner downwardly opening cylindrical shroud surrounding the filter elements which defines an outer annular powder and drying gas passageway communicating with the powder collection chamber, and the exhaust chamber is defined by a downwardly opening conical plenum having an outer conical surface for directing drying gas and powder about the shroud into the powder collection chamber. Filter elements each have a respective reverse gas pulse cleaning device.

First claim

The invention claimed is:

1. A spray dryer for drying liquid into powder comprising:
an elongated body supported in upright position;
an upper end closure arrangement and a lower end closure arrangement at opposite upper and lower ends of the elongated body, respectively for forming a drying chamber within said elongated body;
a spray nozzle assembly supported in said upper end closure arrangement;
said spray nozzle assembly including a nozzle body having a liquid inlet for coupling to a supply of liquid and a discharge spray tip assembly at a downstream end for directing liquid to be dried into said drying chamber;
said upper end closure arrangement having a drying gas inlet for introducing drying gas into said drying chamber for drying liquid directed into the drying chamber into powder;
said lower end closure arrangement including a filter element housing communicating with a bottom powder collection chamber disposed below said filter element housing that collects dried powder from said drying chamber;
a dried powder directing plenum for directing powder from said drying chamber to said powder collection chamber;
an exhaust gas chamber disposed between said drying chamber and said filter element housing having an exhaust gas outlet;
a plurality of cylindrical filter elements supported in depending position from a bottom wall of said exhaust chamber;
said cylindrical filter elements each being closed at a bottom end and having an opposite open upper end communicating with said exhaust chamber such that drying gas exiting the powder collection chamber passes through a cylindrical side of the filter element which restrains gas borne powder with drying gas which then proceeds out the open upper end into and through said exhaust chamber and exhaust gas outlet; and
said filter elements each have a respective reverse gas pulse directing device cyclically operable for directing pulses of pressurized gas into an interior of the cylindrical filter element for removing the buildup of powder on an outside cylindrical surface thereof.

2. The spray dryer of claim 1 including a recirculation conduit coupled between said exhaust gas outlet and the drying gas inlet for reintroducing drying gas into the drying chamber.

3. The spray dryer of claim 1 in which said filter elements each are part of a respective filter cartridge comprising a sealing plate closing a lower end of the filter element and an support plate at an upper end, a connecting member coupled between the sealing plate and support plate, and said support plate having a central opening communicating between the upper open axial end of the cylindrical filter element and the exhaust chamber.

4. The spray drying system of claim 1 in which said filter element housing includes an outer cylindrical housing wall, and said powder directing plenum including an inner cylindrical shroud surrounding said filter elements, said inner cylindrical shroud and outer filter element cylindrical housing wall defining an annular drying gas passageway communicating between said drying chamber and said powder collection chamber.

5. The spray dryer of claim 4 in which said filter element shroud has an open lower end overlying a central area of the powder collection chamber.

6. The spray dryer of claim 1 in which said powder directing plenum includes a downwardly and outwardly opening conical exhaust plenum supported above said inner cylindrical shroud, and an outer surface of said conical exhaust plenum guides drying gas and powder from said drying chamber into the annular passageway between said cylindrical shroud and outer housing wall of the filter element housing.

7. The spray dryer of claim 1 in which the said bottom wall of said exhaust chamber is a circular plate formed with a plurality of circular openings from which said filter elements are supported in depending relation.

8. The spray dryer of claim 1 in which said powder directing plenum includes a downwardly and outwardly opening conical gas direction plenum between an underside of said drying chamber and said filter element housing, said filter element housing having an outer cylindrical housing wall and an inner cylindrical shroud surrounding said filter elements, and said outer cylindrical wall and inner cylindrical shroud defining an annular drying gas and powder passage communicating between said downwardly and outwardly opening conical gas direction plenum and said powder collection chamber.

9. The spray dryer of claim 8 in which said exhaust gas outlet communicates through a side of said downwardly and outwardly opening conical gas directing plenum, and an upper outer side of said downwardly and outwardly opening conical gas directing plenum being effective for directing drying gas and powder from said drying chamber into said annular passage for direction into the powder collection chamber.

10. The spray dryer of claim 1 in which powder directing plenum includes a powder direction cone between an underside of said filter element housing and said powder collection chamber for directing powder from said filter housing into the powder collection chamber.

11. The spray dryer of claim 1 in which said powder collection chamber includes a valve that is operable between an open position for permitting the direction of powder from said filter element housing into said powder collection chamber and a closed position which interrupts the flow of powder into the collection chamber for enabling removal of powder from the collection chamber.

12. The spray dryer of claim 1 in which said spray nozzle assembly is an electrostatic spray nozzle assembly having an electrode for coupling to an electrical source for electrically charging liquid passing through the spray nozzle assembly for discharge from said discharge spray assembly into said drying zone, and said nozzle body has an atomizing gas inlet for coupling to a pressurized gas supply for directing pressurized atomizing air through said nozzle body for atomizing electrostatically charged liquid discharging from the discharge spray tip assembly.

13. The spray dryer of claim 1 in which each said reverse gas pulse directing device includes an gas directing tube having a discharge end centered above the upper open axial end of the cylindrical filter element, and said gas direction tube of each gas pulse directing device having an upstream end coupled to a respective pressurized control valve.

14. The spray dryer of claim 13 in which said control valve of each reverse gas pulse directing device has a respective gas pressure supply line coupled between the respective control valve and a common pressurized gas manifold chamber which in turn is coupleable to a pressurized gas supply.

15. The spray dryer of claim 1 in which the discharge end of each reverse gas pulse directing tube is disposed a distance of at least about two inches above the upper open axial end of the respective filter element.

16. The spray dryer of claim 1 in which each said reverse gas pulse filter cleaning device having a selectively operable reverse gas pulse nozzle coupled to a pressurized gas source for directing pressurized gas into the cylindrical filter element for dislodging powder accumulated on an outside surface of the cylindrical filter element, has a plunger mounted for movement between an open position that permits the flow of drying gas through said cylindrical filter element and axially through the open axial end communicating with said exhaust chamber and a closing position that interrupts and prevents the flow of drying gas from within the collection chamber to said exhaust cham

Assignees

• Spraying Systems Co

Inventors

• Ackerman Thomas E
• Barnes Christopher W
• Bright Adam C
• Huffman David C
• Kocsis Scott J
• Roskos Kristopher E
• St Peter Glenn R
• Smith Brian K
• Szczap Joseph P

Classifications

• B05B5/03 Primary

  characterised by the use of gas {, e.g. electrostatically assisted pneumatic spraying (B05B5/04, B05B5/043, B05B5/047 take precedence)} · CPC title

• B05B7/067

  the liquid outlet being annular · CPC title

• B05B7/066

  with an inner liquid outlet surrounded by at least one annular gas outlet · CPC title

• B05B5/043

  using induction-charging · CPC title

• F26B21/333

  by condensing the moisture in the drying medium, which may be recycled, e.g. using a heat pump cycle · CPC title