A METHOD FOR FORMULATING PARTICLES

PROCEDE DE FORMULATION DE PARTICULES

English Abstract

Method for formulating particles from solutions, wherein cooling the solution
down to the initial freezing point, to mix the solution
under pressure with an inert medium, to expand the solution to solid,
fluidable frozen particles comprising the insert medium and the
solution in a frozen shape.

French Abstract

L'invention concerne un procédé de formulation de particules à partir de solutions, lequel procédé consiste à refroidir la solution jusqu'au point de congélation initial, à mélanger la solution sous pression avec un milieu inerte, en vue de dilater la solution de manière à obtenir des particules congelées solides fluidisables renfermant le milieu inerte et la solution sous forme congelée.

Claims

The embodiments of the invention in which an exclusive privilege or
property is claimed are defined as follows:


1. A method for formulating particles from a solution, CHARACTERIZED
IN cooling the solution down to the initial freezing point, mixing the
solution under
pressure with an inert medium to form a mixture, expanding the mixture to
produce
fluidizable frozen particles comprised of the inert medium and the solution in
a frozen
shape.


2. A method for formulating particles from a solution, CHARACTERIZED
IN producing fluidizable frozen particles of an inert medium and covering the
frozen
particles with the solution.


3. The method according to claim 2, CHARACTERIZED IN covering the
frozen particles with the solution in such a way that the frozen particles do
not melt.


4. The method according to claim 1, 2 or 3, CHARACTERIZED IN
producing frozen particles in a range of 0.5 to 5 mm.


5. The method according to claim 1, 2 or 3, CHARACTERIZED IN that the
inert medium is chosen from the group consisting of N2 and CO2 which sublimes
during
drying or by expansion.


6. The method according to claim 4, CHARACTERIZED IN that the inert
medium is chosen from the group consisting of N2 and CO2 which sublimes during

drying or by expansion.


7. The method according to claim 1 CHARACTERIZED IN expanding the
mixture through a valve to produce the fluidizable frozen particles.


8. The method according to claim 2 or 3 CHARACTERIZED IN that the
producing step is comprised of expanding the inert medium to produce the
fluidizable
frozen particles comprised of the inert medium.



4




9. The method according to claim 8 CHARACTERIZED IN expanding the
mixture through a valve to produce the fluidizable frozen particles.


10. The method according to claim 2, 3 or 9 CHARACTERIZED IN cooling
the solution to the initial freezing point prior to covering the frozen
particles.

Description

CA 02333995 2007-11-14

A METHOD FOR FORMULATING PARTICLES

The present invention is related to a method for formulating particles from
solutions for processing in a fluid bed.

For drying known methods are utilizing among others mixture of solutions
where the dried end product is mixed with a return flow with the product. Such
a
method, however, includes very different resting times for the product which
is
recirculated in relation to products not being recirculated. Additionally the
flow of
products is substantially increased through the drying chamber.

The solution is spread out or in another way laid on inert particles having a
layer which thereafter is dried. The layer is peeled in the drying chamber
thereafter to be
taken out as dried powder in a cyclone, or the particles are taken out of the
chamber for
peeling. Such a method easily pollutes the dried product from the inert
particles.
Furthermore, the inert particles which substantially do not pollute, are
relatively heavy
particles needing very large amounts of energy supplied to the fans to
maintain the
particles in fluidized condition.
With the method according to the present invention substantial advantages
are achieved in relation to known methods, whereby the advantages with the
known
methods are substantially maintained and the disadvantages avoided. In this
way a
strongly reduced residence time is achieved, strongly reduced flow of products
through
the dryer, no pollution of the product from the inert particles, reduced claim
for energy
for the fans and furthermore also a possibility of controlling the density and
porosity of
the end product.

The above mentioned advantages are achieved with the method according
to the invention as defined with features stated in the claims.

The method according to the invention may be utilized to produce frozen
fluidizable particles of solutions thereby using an inert medium in such a way
that the
1


CA 02333995 2007-11-14

solutions may be dried in a fluidized drying chamber. The inert medium as such
is
disappearing by sublimation during drying or already during the formulation of
the
particles. The method also may be utilized for particle formation if the need
for further
processing is not drying, but may be performed in a fluidized bed.
According to the invention the solution to be dried, is cooled down to the
initial freezing point. Thereafter the solution is mixed with the inert medium
under
pressure, thereafter to be expanded to compact, fluidizable frozen particles
comprising
the inert medium as well as the solution in a frozen state. Alternatively, the
fluidizable
particles may be produced from the inert medium which thereafter is covered by
the
solution. This certainly must be made in such a way that the particles as such
do not
melt. The particles normally are produced in a size of 0.5 to 5 mm. The inert
medium to
be sublimated during drying or expansion can be, for example, N2, COz or such.

Equipment necessary for performing the method may be constructed for
batch or continuous operation where two components are mixed in a pressurized
container. The pressurized container should have a valve for expansion of the
mixture to
particle shape. This is performed in a cold room in such a way that the
particles do not
melt.
The mixing relation as well as the pressure in the container and thereby
also the temperature of the expanded particles, are adjusted in such a way
that the desired
density is achieved for the particles. The desired density is determined
partly based on
the desired fluidizing properties of the particles in the subsequent drying
chambers and
the desired properties for the dried end product.

In the production of inert particles to be covered with the solution, the
clean inert particles initially are produced in an equipment corresponding
with the
equipment described above, or in another way, for example by granulation. The
particles
are covered with the solution which already is cooled down to the initial
freezing point.
The thickness and the initial temperature of the layer for the clean inert
particles have to
be adjusted to ensure that melting is avoided. Addition of the layer may be
performed in
ordinary industrial equipment for this purpose in a batch or continuous
production
2


CA 02333995 2007-11-14

process. Preferably the equipment is arranged in a cold room. The subsequent
drying is
performed in a normal fluidized drying chamber having a lower temperature than
the
lowest melting temperature of the particles.

By drying the particle formulation in a closed circuit having a low
temperature, substantial quality advantages are achieved in relation to known
drying
processes, especially because volatile components such as aromatic components
are
preserved.

3