Fluidized bed granulation

Patent metadata

Field	Value
Publication number	US-12330131-B2
Application number	US-202318850232-A
Country	US
Kind code	B2
Filing date	Aug 29, 2023
Priority date	Aug 29, 2022
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

The disclosure pertains to a fluidized bed granulation process, for instance for urea melt. An embodiment of the process comprises providing a fluidized bed of the particles in a granulation compartment of the fluidized bed granulator; forming a film of the granulation liquid in the form of a hollow conical frustum projecting into the granulation compartment by supplying the granulation liquid through a first channel of a granulation nozzle; supplying secondary gas stream through a secondary gas channel of the granulation nozzle into the granulation compartment, wherein the secondary gas channel is provided as an annulus around the first channel, wherein the exit of the secondary gas channel is directly exposed to the fluidized bed in the granulation compartment, wherein particles from the fluidized bed are entrained in said secondary gas stream.

First claim

The invention claimed is:

1. A fluidized bed granulator comprising a granulation compartment comprising a perforated fluidization plate at a lower part of the compartment and at least one nozzle, wherein the nozzle comprises a first channel for granulation liquid and a secondary gas channel, wherein the secondary gas channel is provided as an annulus around the first channel, wherein the exit of the first channel comprises a diffuser that is sloped and outwardly curved to provide a convex surface in a vertical cross-section for the granulation liquid exiting the first channel, and wherein the nozzle extends through the fluidization plate with the exit of the first channel projecting upward into the granulation compartment.

2. A fluidized bed granulator according to claim 1 , wherein the nozzle has a sloped shoulder from an exit of the secondary gas channel upward towards the first channel.

3. A fluidized bed granulator according to claim 1 or 2 , wherein the granulator comprises a plurality of granulation compartments in series, wherein the fluidization gas is introduced into each of the granulation compartments through perforations in a perforated fluidization plate provided at the bottom of the granulation compartments, which each of the plurality of granulation compartments contains a plurality of the nozzles that are operated with the specified ratio of secondary gas to granulation liquid and wherein the granulation compartments are separated from each other by vertical dividing plates which provide for passageways for particles at a bottom part from one granulation compartment to an adjacent granulation compartment.

4. A urea plant comprising a urea melt plant and a fluidized bed granulator according to claim 1 .

5. A fluidized bed granulation process carried out in a fluidized bed granulator according to claim 1 , the process comprising:
a. providing a fluidized bed of particles in the granulation compartment of the fluidized bed granulator;
b. forming a film of the granulation liquid in the form of a hollow conical frustum projecting into the granulation compartment by supplying the granulation liquid through the first channel of the granulation nozzle; the granulation nozzle having the diffuser that is sloped and outwardly curved to provide a convex surface in a vertical cross-section for the granulation liquid exiting the first channel;
c. supplying secondary gas stream through the secondary gas channel of the granulation nozzle into the granulation compartment, wherein the secondary gas channel is provided as an annulus around the first channel, wherein the exit of the secondary gas channel is directly exposed to the fluidized bed in the granulation compartment, wherein particles from the fluidized bed are entrained in said secondary gas stream; and
d. supplying entrained particles to said film by directing the secondary gas stream comprising entrained particles towards the film, causing the deposition of the granulation liquid on the surface of the particles and solidification of said deposited liquid resulting in growth of the particles.

6. A fluidized bed granulator according to claim 1 , wherein the radius of curvature of the diffuser part is 50-150% of the radius of the first channel.

7. A fluidized bed granulator according to claim 1 , wherein surface at the upper end of the diffuser is inclined at 20° to 60° to vertical.

8. The fluidized bed granulator according to claim 1 , wherein the diameter of the first channel at the exit is at least 3.0 mm.

9. A urea plant according to claim 4 , wherein the urea melt plant comprises a high pressure synthesis section for forming urea, a recovery section, and an evaporation section having an outlet for urea melt,
wherein the high pressure synthesis section comprises a reactor and has an inlet for NH 3 feed and CO 2 feed,
wherein the recovery section comprises a dissociator and a condenser for condensing gas from the dissociator and has a recycle line for carbamate from the condenser to the synthesis section, and
wherein an outlet for the urea melt of the urea melt plant is connected to an inlet for granulation liquid of the fluidized bed granulator.

10. The process of claim 5 , wherein the granulation liquid is a urea melt comprising at least 70 wt. % urea.

11. The process of claim 10 , wherein the granulation liquid is a urea melt comprising at least 90 wt. % urea and less than 5 wt. % water.

12. The process of claim 5 , carried out with urea melt as the granulation liquid and with a throughput of at least 300 kg/hr urea melt per nozzle.

13. The process of claim 5 , wherein the product particles are spherical and have a diameter of at least 2.0 mm.

14. The process of claim 5 , wherein the fluidized bed of particles has a height of 50 to 150 cm.

15. The process of claim 5 , wherein the conical film is formed by giving the granulation liquid a rotational movement in the first channel, with the rotation of the granulation liquid about a vertical axis.

Assignees

• Stamicarbon

Inventors

• Cucchiella Barbara
• Gonzalez Coloma Juan

Classifications

• B01J19/26

  Nozzle-type reactors, i.e. the distribution of the initial reactants within the reactor is effected by their introduction or injection through nozzles · CPC title

• B01J2/16 Primary

  by suspending the powder material in a gas, e.g. in fluidised beds or as a falling curtain · CPC title