JP4917532B2 - Method for suspending and dispensing solid substances in a high pressure process - Google Patents

Abstract

The invention relates to a method for suspending and introducing solid matter in a high-pressure process, for example colorant pigments in a high-pressure process, in which a supercritical fluid is used as the process medium and a pressure in excess of 150 bar prevails. According to the invention, the suspension of the solid matter takes place at a low-pressure in a completely separate suspension method. In the latter, the solid matter is suspended or partially dissolved in a non-critical, liquid gas. The pressure in said suspension method is less than 90% of the critical pressure of the liquid gas. The suspension is introduced into the high-pressure process by means of a pump.

Description

  The invention relates to a method for suspending and metering colored pigments in a high-pressure process, for example in a high-pressure process in which a supercritical liquid is used as the process medium and the pressure is above 150 bar. In this case, the suspension of the solid material is carried out at a low pressure by a completely different suspension method. In this suspension method, the solid is suspended or partially dissolved in non-critical and liquefied gases. In this case, the pressure in this suspension method is less than 90% of the critical pressure of the liquefied gas. The suspension is introduced into the high-pressure process by a pump.

  Various methods and devices are known in the prior art that can supply solids to a high pressure process. Generally, the solid is introduced into a feed hopper, feed tank or similar device, which is then flushed with the process medium, and then the solid material is introduced together into the high pressure process.

  German Offenlegungsschrift 19,928,405 relates to a method for coloring fiber substrates in at least one supercritical fluid. The amount of powdered dye required for coloring is then divided into a number of partial amounts and each dye partial amount is brought into contact with the supercritical liquid until it dissolves or disperses. The disclosed apparatus is equipped with an oscillating kinetic piston with sliding material on both sides that moves across the flow and through a process line containing a critical liquid. This piston contains the solid material in the first perforation at the end position and the first perforation is present in the main flow of critical liquid at the other end position, so that the solid material is washed out of the perforation. . Parallel to this, the second bore is filled or emptied in the reverse order at another piston end.

  The disadvantages of the method presented in DE 19,928,405 and the device disclosed here are that the device for the same pressure is designed and dimensioned in the same way as the main process . In addition, supercritical gas is trapped in the evacuated perforations and the perforations present in the main flow and moves to the filling position. As a result, this area must be at the same or higher pressure, or a pressure relief must be applied each time that impedes the rapid filling process. Furthermore, it is practically very important to traverse a high-pressure gasket having a bore through which the piston travels. Here, after a short period of operation, the gasket material can be damaged and the associated leakage problems can be expected.

  WO 97/013915 discloses a very general method for metering solids in a supercritical manner. In the case of this method, the dye is prepared in a dye preparation vessel which is arranged in a bypass with respect to the main process stream. Corresponding valves are opened for the discharge of the solid and the solid is carried by a partial stream of the main process liquid. Therefore, uniform metering or deliberate control of the dye supply cannot be carried out because the liquid-solid-mixture is diluted by the subsequent flowing process liquid. In addition, all components of this method deployed in the bypass must meet the main process pressure and temperature requirements.

A method optimized compared to the suspension method known from WO 97/013915 is disclosed in US Pat. No. 6,261,326. In this method, a stirrer is provided in a dye preparation container for dissolving or suspending the dye, or a partial flow is circulated by a pump. As disclosed in the above document, there is a critical liquid state or near critical liquid state in this preparation method, and therefore this preparation method is supplied with supercritical liquid from the main process. As in the case of the above method, this preparation method has the disadvantage of having to satisfy the high pressure conditions of the main process (herein referred to as processing method). In addition, solid metering that is not described in US Pat. No. 6,261,326 must be done by a very expensive hopper or the solid feed vessel must be adapted to the high pressure of this process. .
German Patent Application No. 19,928,405 International Patent Application Publication No. 97/013915 US Pat. No. 6,261,326

  The object of the present invention was therefore to provide a suspension and solids metering process which does not depend on the circulation system of the main pressurization process and which is operated more economically than prior art processes.

  The present invention has solved this problem by a method of suspending and dispensing granular, granular or powdered solid substances in a high pressure process in which supercritical gas is substantially present as a process medium. This method is the suspension stage of the high pressure process and consists of a suspension vessel and a liquid mixing device and supply and discharge conduits.

  In carrying out this method, a solid substance and a liquid are supplied to the suspension container in the first stage, and a liquefied gas in a non-critical state is used as the liquid.

  In the second stage, the solid material is suspended in the liquid by the liquid mixing device and the suspension is maintained. In this case, the liquid mixing device is ideally connected as a stirrer or outside the suspension vessel to the suspension vessel via suction and press-fit conduits and continuously circulates a part of the suspension. It is configured as a pump.

  In this case, the pressure in the suspension stage is preferably below 90% of the critical pressure of the gas used and ideally below 60 bar. At that time, the temperature is adjusted so that the gas phase exists above the liquid phase.

  In the last stage, the suspension is pumped to the high pressure process. Therefore, only the pump and the pump conduit connected to the main process must meet the requirements of the high pressure process. All process equipment attached to the suction side of the pump is clearly required to have low requirements.

  In one advantageous embodiment of the method according to the invention, the liquid used for suspending is chemically substantially consistent with the process medium of the high pressure process.

One optimal method involves adding other substances to the liquid. These materials include, for example, cyclic and acyclic short chain hydrocarbons or short chain alcohols, aldehydes or ketones and H ₂ O and mixtures of these materials.

  In the case of the process according to the invention, it is advantageous to keep the pressure in the suspension vessel constant during the introduction of the suspension into the high-pressure process by supplying the gas in gaseous form.

  The ideal variant therefore allows the suspension to enter the high-pressure process continuously while emptying the vessel, in which case the volumetric flow of the solid substance in the liquid and hence its concentration is reduced. It can be adjusted to a uniform level or to a value that varies by pumping. While the concentration in the suspension container is emptied, the gas supplied later is not liquid but is in a gaseous state, so that it is substantially constant.

  The solid is advantageously a substance that can be dissolved in a high-pressure process, such as dye particles, adhesion promoters, bleaches, perfumes, odorous substances or mixtures thereof. In the context of the present invention, contrary to the prior art, solids are not dissolved but only suspended, and the inherent solubility of the individual feed materials does not have to be strictly observed in the suspension stage. Of course, when these materials are introduced into the large volume flow of the main process, these materials dissolve directly because of the high concentration rate.

  Therefore, one advantageous embodiment of the present invention provides that the suspension stream upon introduction into the high pressure process has a volume flow ratio of suspension to high pressure process medium of less than 1:50, ideally 1 : It is adjusting so that it may be 100 or less.

  Suspension streams with a very small ratio to main process volume flow generally have a negative physical impact on the main process.

  The method of the present invention will be described in detail below with reference to two drawings.

  FIG. 1 shows a suspension method using a pump as a liquid circulation device, and FIG. 2 shows a method using a stirrer without an external circulation system.

  According to FIG. 1, the suspension process (1) connected to the high pressure process (4) through the conduit (6) consists essentially of a suspension vessel (2) and a pump (3). Suspension vessel (2) is charged with liquefied gas through conduit (7) and solid material through conduit (8). As can be seen in FIG. 1, a liquid volume part (2a) and a gas volume part (2b) are formed in the suspension container (2). A partial flow is drawn through the conduit (10) by the suspension pump (9) into the vessel and recirculated through the conduit (11).

  As the suspension vessel (2) is emptied, the suspension is sent by the pump (3) through the conduit (5) to the conduit (6) to the high pressure process (4). Obviously, only the pump (3) and the pump side piping, i.e. the conduit (6), must be at the same pressure as the high pressure process (4). For the remaining components of the suspension process, pressure conditions up to about 60 bar are sufficient.

  FIG. 2 shows another embodiment in which a stirrer (13) is placed in the suspension vessel (2), thereby producing a suspension and keeping it stable.

Shows one embodiment of the invention using a pump as the liquid circulation device. Shows one embodiment of the present invention using a stirrer without an external circulation system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Suspension process 2 ... Suspension container 3 ... Pump 4 ... High-pressure process 13 ... Stirrer

Claims (15)

A method of suspending and dispensing granular, granular or powdered solid material in a high pressure process in which a supercritical fluid is present as a process medium, wherein the method is a suspension stage of the high pressure process and a suspension vessel and Consisting of a liquid mixing device and supply and discharge conduits, in which the solid substance and liquid are supplied to the suspension vessel in the first stage, where the liquid is a liquefied gas,
-Suspending and maintaining the solid substance in the liquid by means of a liquid stirrer;
In the above method,
The pressure applied in the suspension stage is lower than 90% of the supercritical pressure of the process medium, in which the gas phase is present above the liquid phase in the suspension vessel;
And-the method as described above, characterized in that in the last stage the suspension is pumped to a high pressure process. The process according to claim 1, wherein the pressure applied in the suspension stage is lower than 60 bar. The method according to claim 1 or 2, wherein the pressure in the suspension vessel is stably maintained by introducing a solid-free gas when supplying the suspension to the high-pressure process. The method according to any one of claims 1 to 3, wherein the liquid mixing device is a stirrer installed in a container. The liquid mixing device is a pump connected to a suspension vessel via suction and press-fit conduits, and a part of the suspension is continuously pumped into the circulation system by this pump. The method according to any one of the above. 6. A process as claimed in any one of the preceding claims, wherein the suspension stage liquid is chemically the same as the process medium of the high pressure process. The method according to claim 1, wherein another substance that is not solid is mixed into the liquid. 8. A process according to claim 7, wherein the further substance is water or cyclic and acyclic short chain hydrocarbons or short chain alcohols, aldehydes or ketones and mixtures thereof. 4. A method according to claim 3, wherein the gas subsequently supplied to maintain the pressure in the suspension vessel during the introduction of the suspension into the high pressure process is gaseous. 10. The method according to any one of claims 1 to 9, wherein the suspension is kept continuously stable by means of a liquid mixing device when the suspension is conveyed to a high pressure process. The method according to claim 1, wherein the supplied solid is a substance to be dissolved in a high pressure process. 12. A method according to claim 11, wherein the substance to be dissolved in the high pressure process is dye particles, adhesion promoters, bleaches, perfumes, odorous substances or mixtures thereof. The suspension supply to the high pressure process can be made continuously while the container is emptied, at which time the volumetric feed flow can be adjusted to be kept constant or changed. The method according to claim 1, wherein the concentration in the suspension container is constant . 14. A process according to any one of the preceding claims, wherein the volume flow ratio of suspension to high pressure process medium is less than 1:50 upon introduction of the suspension into the high pressure process. 15. The method of claim 14, wherein the volume flow ratio of the suspension to the high pressure process medium is 1: 100 or less.

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