Method for pneumatically conveying plastic pellets

Patent metadata

Field	Value
Publication number	US-10647527-B2
Application number	US-201815959599-A
Country	US
Kind code	B2
Filing date	Apr 23, 2018
Priority date	Apr 24, 2017
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

When performing a method for pneumatically conveying plastic pellets, the plastic pellets are conveyed, by means of a carrier gas, through a conveyor line from a feed point to a destination with a liquid being added thereto, wherein the quantity of liquid added to the plastic pellets and/or the carrier gas is such that during conveying, the carrier gas is oversaturated with the liquid at least in sections of the conveyor line in such a way that a Froude number defining the conveying conditions in the conveyor line is smaller than 45 at any point along the conveyor line.

First claim

What is claimed is:

1. A method for pneumatically conveying plastic pellets, the method comprising the method steps:
conveying plastic pellets via a carrier gas from a feed point to a destination through a conveyor line, the plastic pellets having a particle diameter of 2 mm to 5 mm, which is equivalent to that of a sphere having a same volume;
adding a liquid to at least one of the carrier gas and the plastic pellets, wherein a quantity of the liquid added is such that during conveying, the carrier gas is oversaturated with the liquid at least in sections of the conveyor line;
providing a Froude number defining conveying conditions in the conveyor line, the Froude number being less than 45 at any point along the conveyor line, wherein the liquid added evaporates only incompletely when being added, wherein a non-evaporated part of the liquid continues to evaporate when the liquid is conveyed along the conveyor line.

2. The method according to claim 1 , wherein the liquid is water.

3. The method according to claim 2 , wherein the liquid is demineralized water.

4. The method according to claim 1 , wherein a ratio of a product mass flow to a mass flow of dry carrier gas in the conveyor line is greater than 3.

5. The method according to claim 1 , further comprising a feed pressure for pneumatically conveying the plastic pellets along the conveyor line, wherein the feed pressure corresponds to a pressure difference between a feed point pressure and a destination pressure, the pressure difference amounting to at least 0.2 bar.

6. The method according to claim 5 , further comprising a pressure conveying, wherein an overpressure relative to atmospheric pressure of at least 0.2 barg is at the feed point.

7. The method according to claim 5 , further comprising a suction conveying, wherein a negative pressure relative to atmospheric pressure of at least 0.2 barg is at the destination.

8. A method for pneumatically conveying plastic pellets, the method comprising the method steps:
conveying plastic pellets via a carrier gas from a feed point to a destination through a conveyor line;
adding a liquid to at least one of the carrier gas and the plastic pellets, wherein a quantity of the liquid added is such that during conveying, the carrier gas is oversaturated with the liquid at least in sections of the conveyor line;
providing a Froude number defining conveying conditions in the conveyor line, the Froude number being less than 45 at any point along the conveyor line;
providing a humidity content of the plastic pellets of at most 10%, wherein the humidity content is defined as a ratio of a mass of the liquid added in relation to a mass of the plastic pellets.

9. The method according to claim 1 , wherein the carrier gas used is one of air and nitrogen.

10. The method according to claim 1 , wherein a relative humidity of the carrier gas at the destination is between 60% and 200%.

11. The method according to claim 1 , further comprising an addition of liquid via at least one humidification point arranged along the conveyor line between the feed point and the destination.

12. The method according to claim 11 , wherein the at least one humidification point is arranged in a region of a pipe bend.

13. The method according to claim 11 , wherein the at least one humidification point is arranged upstream of the pipe bend.

14. The method according to claim 1 , further comprising:
providing a humidity content of the plastic pellets of at most 10%, wherein the humidity content is defined as a ratio of a mass of the liquid added in relation to a mass of the plastic pellets.

15. The method according to claim 11 , further comprising:
providing a humidifier, wherein the liquid is added to at least one of the carrier gas and the plastic pellets via the humidifier;
providing an additional humidifier, wherein additional liquid is added via the additional 5 humidifier, the additional liquid forming a lubricating film on an inner surface of an outer wall of the conveyor line.

16. The method according to claim 1 , further comprising:
providing a humidifier, wherein the liquid is added to at least one of the carrier gas and the plastic pellets via the humidifier;
providing an additional humidifier, wherein additional liquid is added via the additional 5 humidifier, the additional liquid forming a lubricating film on an inner surface of an outer wall of the conveyor line.

Assignees

• Coperion Gmbh

Inventors

• Stark Bernhard
• Duerr Michael
• Vögele Thomas
• Dikreuter Christian
• Toni Christian

Classifications

• B65G53/526 Primary

  with means for special treatment to facilitate transport · CPC title

• B65G2201/042

  Granular material · CPC title

• B65G53/10

  with pneumatic injection of the materials by the propelling gas · CPC title

• B65G53/04 Primary

  Conveying materials in bulk pneumatically through pipes or tubes; Air slides · CPC title

• B65G53/58

  Devices for accelerating or decelerating flow of the materials; Use of pressure generators (controlling pressure of propelling gas B65G53/66) · CPC title