Method of transporting a viscous fluid through a heat exchanger line

Abstract

A method for transporting a viscous fluid through a heat exchanger line that includes transporting a viscous fluid through a connecting piece with an excess pressure release component, where the excess pressure relief component separates an interior of the connecting piece from a discharge line in the connecting piece, and is fixed to an edge of the discharge line, mixing a fluid flow in a region of the excess pressure relief component using a mixing element disposed in the interior of the connecting piece and causing the excess pressure release component to release at least a portion of the fluid through the discharge line when the pressure of the fluid is equal to or greater than a preset excess pressure.

Claims

1. A method for transporting a viscous fluid through a heat exchanger line, the method comprising: transporting a viscous fluid through a connecting piece with an excess pressure release component, wherein the connecting piece defines a discharge line in communication with the heat exchanger line, and said excess pressure relief component is fixed within the discharge line, said excess pressure relief component has an axial inner end and is spaced a distance from an axial inner end of the discharge line; mixing a fluid flow in a region of the excess pressure relief component using a single mixing component including at least six mixing elements disposed in an interior of the connecting piece, wherein at least two of said six mixing elements cross each other; and causing the excess pressure release component to release at least a portion of the fluid through the discharge line when the pressure of the fluid is equal to or greater than a preset excess pressure.

2. The method of claim 1, wherein a zero shear viscosity of the fluid is 100 to 15,000 Pas.

3. The method according to claim 1, wherein the viscous fluid is thermally unstable.

4. The method according to claim 1, wherein the viscous fluid is a cellulose solution.

5. The method according to claim 1, further comprising positioning said single mixing component adjacent to an opening to said connecting piece.

6. A method for transporting a viscous fluid through a heat exchanger line, the method comprising: transporting a viscous fluid through a connecting piece with an excess pressure release component and defining a discharge line in communication with the heat exchanger line, wherein the excess pressure relief component separates the discharge line in the connecting piece, and is fixed within the discharge line, said excess pressure relief component has an axial inner end that is spaced a distance from an axial inner end of the discharge line; mixing a fluid flow in a region of the excess pressure relief component using a single mixing component including a plurality of criss-crossing mixing elements disposed in the interior of the connecting piece; and causing the excess pressure release component to release at least a portion of the fluid through the discharge line when the pressure of the fluid is equal to or greater than a preset excess pressure.

7. The method of claim 6, wherein a zero shear viscosity of the fluid is 100 to 15,000 Pas.

8. The method according to claim 6, wherein the viscous fluid is thermally unstable.

9. The method according to claim 6, wherein the viscous fluid is a cellulose solution.

10. The method according to claim 6, further comprising positioning said single mixing component adjacent to an opening to said connecting piece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 and 2 show cross-sections through connecting pieces 1 according to the invention with a bursting element in the form of a bursting disc 2 with assigned fluid line 3 leading past, which here is provided curved leading out of the plane of representation, a discharge line 4, to the edge 5 of which the bursting disc is fixed, a bore 6, a bursting spike 7 and a heating line 8.

(2) FIG. 3 shows various bursting elements, i.e. a bursting disc (a) turned by drilling from a wall block, a concave bursting disc, which bursts with increased forced bulging (b), and a bursting disc with a rupture blade (b). Bursting discs b) and c) are fixed to the edge by clamping in.

(3) FIG. 4 shows two cross-sections a) and b), with a connecting piece 1 according to the invention which connects two heat exchangers 9, also with mixing elements 10, according to WO 2009/000642.

(4) FIGS. 5 to 7 show cross-sections through connecting pieces 1 according to the invention with different valves with blocking discs 2 in a closed (FIG. 5a, 6a, 7a) and opened (FIG. 5a, 6a, 7a) position. Fluid line 3 and discharge line 4 and discharge lines 8 are also represented. Blocking disc 2 is connected to a linkage 9, which is fixed by means of a shear ring 10 (FIG. 5) or a spring 11 (FIG. 6) or a holding fixture 12 (FIG. 7), the latter in the buckling rod embodiment, wherein a displacement occurs under the effect of excess pressure.

DETAILED DESCRIPTION

(5) Example 1

(6) A connecting piece, as represented in FIG. 4, is used according to this example.

(7) In this form, two heat exchanger lines (each 3 m long) are connected by the connecting piece. A discharge line 4 is provided leading away from the connecting piece, said discharge line not lying in the regular flow path of the fluid conveyed through the heat exchanger lines, but being in contact therewith. A bursting disc 2 prevents the discharge during normal operation. In the presence of a critical excess pressure, it is pressed against cutting blade cross 7 and thereby bursts, as a result of which the discharge line is released for the discharge of the fluid. At regular intervals, the pressure and the temperature are checked by sensors before the bursting disc and samples of the fluid are taken through relief bore 6. A mixing element brings about a temperature, viscosity and pressure equalisation of the fluid. The inner diameter of the heat exchangers and of the connecting piece amounts to 108 mm.

(8) During operation, this element was tested with a cellulose-NMMO-water solution (cellulose: 12.9%, NMMO 76.3%, water 10.8%, all % in wt.-%) at a temperature of 90° C. and a pressure of 30 bar. The solution was introduced under pressure into the first heat exchanger by means of a pump. A filter was located at the end of the second heat exchanger in order to maintain the pressure in the line.

(9) No irregular temperatures and pressures were able to be ascertained on temperature and pressure sensors 6 during the trial operation. The bursting disc burst at a simulated excess pressure of 100 bar, as a result of which the pressure fell below the normal working pressure.

(10) Fluid samples were taken at regular intervals at relief bore 6, examined with regard to their thermal stability by means of DSC analysis and compared with the stability of “fresh” cellulose-NMMO-water solution. Even after a running time of several days, a reduction of the thermal stability of the cellulose-NMMO-water solution in the region of the bursting disc could not be ascertained compared to “fresh” solution.

(11) Example 2

(12) A polymer solution for use as a spinning solution with the following composition was transferred through a heat exchanger line system, comprising heat exchangers and connecting pieces according to the invention as distribution pieces, from spinning solution production to processing of the latter in a spinning machine.

(13) The spinning compound comprising a mixture of celluloses of the type MoDo Crown Dissolving-DP 510-550 and Sappi Saiccor DP 560-580 was continuously produced in the following composition: cellulose 12.9%; amine oxide (NMMO—N-methyl-morpholine-N-oxide) 76.3%; water 10.8%.

(14) The preparation of the solution took place, after an aqueous enzymatic pre-treatment and preparation of a suspension had been carried out, by evaporation of excess water under vacuum in a reaction vessel at a temperature of 97 to 103° C., through which a continuous flow was passed. Known stabilisers were added to stabilise the solvent NMMO/water. The stabilisation of the cellulose solution took place in a known manner with gallic acid propylester. For the safety-orientated preparation of the solution, the heavy metal ion content was controlled and a value of 10 ppm as a sum parameter (of metal ions and nonferrous metal ions) was not exceeded.

(15) The density of the prepared solution amounts to 1200 kg/m.sup.3 at room temperature. The zero shear viscosity of the spinning compound adjusted by the cellulose material mixing components can, measured at 75° C., amount to up to 15,000 Pas. Depending on the processing temperature selected in the spinning process, the zero shear viscosity can vary in the range from 500 to 15,000 Pas. Due to the structurally viscous behaviour of the spinning solution, the viscosity falls at spinning shear rates, depending on the selected processing temperature, to a range of below 100 Pas and is also very dependent on the cellulose concentration in the spinning solution.

(16) For the purpose of temperature measurement and viscosity measurement, polymer material was sampled on the connecting pieces at the sampling openings during the passage, the bursting disc provided in the connecting piece being dimensioned for a specific throughput per mm.sup.2 of bursting area.

(17) TABLE-US-00001 Spec. bursting disc Viscosity dimensioning Temp. Viscosity deviation Sampling opening via kg polymer material/ Temp. deviation ± ço in Pas ço in Pas distribution piece mm2 bursting disc area ° C. in ° C. at 90° C. at 90° C. ± Reactor 0.11 101.5 2.4 1270 98 After heat exchanger 0.08 96.5 0.8 2080 85 After filter 0.05 97.3 1.3 1550 73 After pump - 0.15 95.8 0.9 2200 67 distribution Distribution - 0.04 91.5 1.1 3650 54 spinning machine

(18) Deviations in respect of temperature and viscosity were ascertained by 10 individual measurements and by taking the average value.

(19) While particular embodiments of the present method are shown and described, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.