APPARATUS FOR PREPARING AND DISPENSING A FLOCCULANT SOLUTION TO DEWATERING AN AQUEOUS PROCESS STREAM

Abstract

The present invention relates to an apparatus (1), suitable for preparing and dispensing a flocculant solution to dewatering an aqueous process stream (4), wherein the apparatus (1) comprises a mixing pump (5) that mixes the flocculant solution and builds up a pressure onto the flocculant solution, and a maturing pressure tank (2), whereby the maturing pressure tank (2) is fluidly connected with the mixing pump (5), so that the pressurized diluted flocculant solution (3) is led from the mixing pump (5) into the maturing pressure tank (2) and matured therein under pressure that is above atmosphere pressure.

Claims

1. An apparatus, suitable for preparing and dispensing a flocculant solution to dewatering an aqueous process stream, the apparatus comprising a mixing pump that mixes the flocculant solution and builds up a pressure onto the flocculant solution, and a maturing pressure tank, whereby the maturing pressure tank is fluidly connected with the mixing pump, so that the pressurized diluted flocculant solution is led from the mixing pump into the maturing pressure tank and matured therein under pressure that is above atmosphere pressure.

2. The apparatus of claim 1, wherein the mixing pump is a centrifugal pump.

3. The apparatus of claim 1, wherein the fluid flow of the pressurized diluted flocculant solution is driven by the pressure of the pressurized diluted flocculant solution so that in a fluid flow direction, after the mixing pump, the fluid flow is driven by the pressure of the pressurized diluted flocculant solution and no additional pump is arranged in fluid flow direction, after the mixing pump.

4. The apparatus according to claim 1, further comprising: a mixer with a motor unit connected with the maturing pressure tank for feeding a diluted flocculant solution into the aqueous process stream, wherein the mixing pump mixes a concentrated flocculant solution with a solvent to obtain the diluted flocculant solution, and the maturing pressure tank receives the pressurized diluted flocculant solution from the mixing pump via a diluted flocculant line.

5. The apparatus according to claim 4, wherein the diluted flocculant solution in the maturing pressure tank is pressurized at a pressure of at least about ≧15 N/cm.sup.2 to about ≦100 N/cm.sup.2.

6. The apparatus according to claim 1, wherein the mixing pump comprises a mixing point.

7. The apparatus according to claim 4, further comprising: a calibration vessel, a first supply line comprising at least one conveyance pump that pumps the concentrated flocculant solution from the calibration vessel to a mixing point, and a second solution supply line connected with a solvent source at one end and to the mixing point at the other end, whereby at the mixing point the concentrated flocculant stock solution is mixed with the solvent.

8. The apparatus according to claim 4, further comprising a feeding unit with an inline mixer, wherein the inline mixer is integrated in the aqueous process stream so that the diluted flocculant solution can be fed to and mixed in the process stream whereby a feeding line connects the maturing pressure tank to the inline mixer.

9. The apparatus according to claim 4, further comprising a controller that controls and regulates the fluid flow of the concentrated flocculant solution by means of the mixer.

10. The apparatus according to claim 7, wherein the first supply line is connected with one end to the calibration vessel and with the other end to the mixing pump, whereby the first supply line further comprises two multi-way-valves to which a supply line circuit is connected.

11. The apparatus according to claim 7, whereby the conveyance pump is connected to the supply line and an overpressure valve is connected after an outlet port of the conveyance pump.

12. The apparatus according to claim 1, which comprises a pressure sensor that is arranged to a first supply line.

13. The apparatus according to claim 7, whereby the second diluting solution supply line is connected with a solution source whereby the second solution supply line comprises a water filter and a pressure relief valve.

14. The apparatus according to claim 1, whereby an outlet port of the mixing pump (5) is connected to one end of a diluted mixed flocculant line which connects at another end to the at least one maturing pressure tank, whereby the mixed flocculant line comprises a multi-way valve to which a recirculation line is connected at one end thereof and with the other end thereof to an inlet port of the mixing pump.

15. The apparatus according to claim 8, whereby the feeding line that connects the maturing pressure tank to the mixer comprises at least one dosing regulator unit that regulates and controls the amount of flocculant solution that is fed by the feeding unit into the aqueous process stream.

16. The apparatus according to claim 7, wherein the calibration vessel is connected with the conveyance pump and configured to calibrate concentrated flocculant solution to the mixing point.

17. A method for preparing and dispensing a flocculant solution, the method comprising the steps of: mixing the flocculant solution with a mixing pump; pressurizing the flocculant solution during the mixing; directing the pressurized flocculant solution from the mixing pump to a maturing pressure tank; and holding the pressurized fluid in the maturing pressure tank at a pressure that is above atmospheric pressure.

18. (canceled)

19. (canceled)

20. (canceled)

21. The method of claim 17, further comprising mixing the flocculant with a solvent to obtain a diluted flocculant solution.

22. The method according to claim 21, wherein the diluted flocculant solution is matured in the maturing pressure tank and dispensed into an aqueous process stream.

23. The method according to claim 17, wherein the pressurized flocculant solution is directed to the maturing pressure tank by the pressure of the pressurized flocculant solution generated from the mixing pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Now the invention will be explained by way of examples with reference to the accompanying drawings in which:

[0092] FIG. 1 is a view of an apparatus for preparing and dispensing a flocculant solution to dewatering an aqueous process stream with a mixing pump and a pressurized processing tank;

[0093] FIG. 2 is a more detailed schematic view of an apparatus for preparing and dispensing a flocculant solution to improve dewatering of an aqueous process stream with a pressurized processing tank;

[0094] FIG. 3 is a detailed schematic view of an apparatus for preparing and dispensing a flocculant solution to improve dewatering of an aqueous process stream with a pressurized processing tank;

[0095] FIG. 4 is a first perspective view of an apparatus for preparing and dispensing a flocculant solution to improve dewatering of an aqueous process stream with a pressurized processing tank;

[0096] FIG. 5 is a graph of the viscosity of an aqueous polymer solution at different concentrations;

[0097] FIG. 6 is a graph of the conductivity of 3 wt.-% aqueous polymer solution at different stirring speed over time.

[0098] FIG. 1 shows an apparatus 1, suitable for preparing and dispensing a flocculant solution to dewatering an aqueous process stream 4, wherein the apparatus 1 comprises at least one mixing pump 5 for pressurizing and mixing a diluted flocculant solution 3, whereby due to the mixing of the mixing pump 5 the conductivity of the flocculant solution is increased, and at least one maturing pressure tank 2 in which a diluted flocculant solution 3 is stored and/or matured under pressure that is above atmosphere pressure.

[0099] FIG. 2 shows an apparatus 1 which comprises at least one maturing pressure tank 2 in which a diluted flocculant solution 3 is stored and/or matured under pressure that is above atmosphere pressure. The apparatus 1 comprises further a mixing pump 5 for mixing a concentrated flocculant solution with a solvent, preferably water, obtaining a diluted flocculant solution 3, whereby due to the mixing of the mixing pump 5 the conductivity of the flocculant solution is increased, and a maturing pressure tank 2 in which the pressurized diluted flocculant solution 3 received from the mixing pump 5 is lead into via a diluted flocculant line 3b and stored under pressure that is above atmosphere pressure. An inline mixer 15 with a motor unit 8 is connected with the maturing pressure tank 2, for feeding diluted flocculant solution 3 into the aqueous process stream 4.

[0100] FIG. 3 shows an apparatus, 1 which comprises at least one maturing pressure tank 2 in which in a mixing pump circuit 3a a diluted flocculant solution 3 is stored and/or matured under pressure that is above atmosphere pressure. The apparatus 1 comprises further a mixing pump 5 with a fluid pump inlet port 5a and a fluid pump outlet port 5b for mixing a concentrated flocculant solution with a solvent, preferably water, obtaining a diluted flocculant solution 3, and a maturing pressure tank 2 in which the pressurized diluted flocculant solution 3 received from the mixing pump 5 is lead via a diluted flocculant line 3b into and stored under pressure that is above atmosphere pressure.

[0101] A line 22 connects the mixing pump 5 with the maturing pressure tank 2 and an inline mixer 15 with a motor unit 8 is connected with the maturing pressure tank 2, for feeding diluted flocculant solution 3 into the aqueous process stream 4, whereby a feeding line 16 connects the maturing pressure tank 2 with the inline mixer 15 with a motor unit 8 that mixes the diluted flocculant solution into the aqueous process stream. A pressure relief valve 25b can be arranged between the maturing pressure tank 2 and the mixing unit 15 with a motor 8, or the pressure relief valve 25b is arranged downstream the pressurized vessel, to avoid overpressure in the vessel. The feeding line 16 that connects the maturing pressure tank 2 to the mixer 15 with a motor unit 8, which is connected to the inline mixer 15 comprises a dosing regulator unit 29 that regulates and/or controls the amount of diluted flocculant solution 3 that is fed by the mixer 15 with a motor unit 8 into the aqueous process stream 4.

[0102] Further the mixing pump 5 is connected with a mixing point 9 and a calibration vessel 10 is connected with a first supply line 11 comprising a conveyance pump 12 that pumps the concentrated flocculant solution 6 from the calibration vessel 10 to the concentrated flocculant solution feeding port 6a of the mixing point 9. An outlet port 5b of the mixing pump 5 is connected to one end of the diluted mixed flocculant line 22 which connects with the other end to the at least one maturing pressure tank 2, whereby the flocculant line 22 comprises a three-way valve 27, to which a recirculation line 28 is connected at one end and with the other end the recirculation line 28 is connected with the mixing point 9 which is connected to an inlet port 5a of the mixing pump 5. This circuit allows that the diluted flocculant solution can be recirculated and mixed with the mixing pump 5. Further a flow meter 21 is arranged between the three-way valve 27 and the maturing pressure tank 2 to control the fluid flow of the concentrated flocculant solution to the maturing pressure tank 2.

[0103] A second solution supply line 13 is connected with a solvent source 14—not shown—at one end and to the solution feeding port 7a of the mixing point 9 at the other end, whereby at the mixing point 9 the concentrated flocculant stock solution is mixed with the solvent 7, preferably water.

[0104] The apparatus has further a mixer 15 with a motor unit 8, which is not a pump, that means the dosing of the diluted flocculant solution is driven by the pressure of the pressurized diluted flocculant solution, wherein the mixing elements of the inline mixer 15 is integrated in the aqueous process stream 4 so that the diluted flocculant solution 3 can be fed to and mixed in the process stream 4, preferably within the slurry, to be treated, whereby a feeding line 16 connects the maturing pressure tank 2 to the mixer 15 with the motor unit 8.

[0105] A controller 23 controls and regulates the fluid flow of the concentrated flocculant solution 6, the fluid flow of the diluted flocculant solution 3, and/or the dosing of diluted flocculant solution 3 by means of a mixer 15 preferably an inline mixer 15, to the aqueous process stream 4. Further the controller 23 may control and regulate the speed of the mixer 15.

[0106] The first supply line 11 is connected with one end to the calibration vessel 10 and with the other end to the mixing point 9 or the mixing pump 5, whereby the first supply line 11 comprises two multi-way-valves 17a/17b and a supply line circuit 11a. The valves 17a/17b are for calibration of the pump.

[0107] A conveyance pump 12 is connected to the supply line 11a and an overpressure valve 19 is connected before an inlet port and after an outlet port of the conveyance pump 12 that opens if the pressure in the supply line 11/11a is higher than a given value to protect the apparatus against overpressure.

[0108] A pressure sensor 18, such as a manometer, is arranged at the maturing pressure tank 2 to indicate the pressure of the maturing pressure tank 2. At the supply line 11/11a a dry run sensor 20 is arranged to control the filling level of the concentrated flocculant solution 6 in order to give a signal or stop the apparatus if there is the danger that the device is running dry of concentrated flocculant solution 6.

[0109] The second diluting solution supply line 13 is connected with a solution source 14 not shown, preferably to a water delivery system, whereby the second solution supply line 13 comprises a water filter 24, a pressure relief valve 25a and a solenoid valve 26. The apparatus 1 may comprise at least one check valve to avoid water/polymer contact arranged before the mixing point not shown.

[0110] FIG. 4 shows an apparatus 1 for preparing and dispensing a flocculant solution to dewatering an aqueous process stream placed on a pallet which also has a function of a dripping tray 30. A conveyance pump 12 is connected to a first end of the first supply line 11 and with the second end the first supply line 11 is connected with the mixing point 9 so that concentrated flocculant solution is pumped to the mixing point 9. Further a calibration vessel 10, preferably having a cylinder design, is connected with the conveyance pump 12 to calibrate concentrated flocculant solution that is pumped to the mixing point 9.

[0111] A second solution supply line 13 that transports a solvent, preferably water, is connected to the mixing point 9 too. At the mixing point 9 a concentrated flocculant solution and a solvent, preferably water, are combined. The mixing point 9 is part of the mixing pump 5 at which the concentrated flocculant solution and the solvent, preferably water, are combined. A recirculation line 28 that can be connected with the mixing pump 5 or the mixing point 9 at one end and at the other end with the mixing pump outlet 5b of the mixing pump 5 for mixing and circulating the flocculant solution.

[0112] A diluted flocculant solution line 3b transports mixed and diluted flocculant solution from the mixing pump 5 to the maturing pressure tank 2. From the maturing pressure tank 2 matured diluted flocculant solution flows through a feeding line 16 to the inline mixer 15 with a motor 8. A dosing regulator unit 29 for dosing the amount of diluted matured flocculant solution and a pressure relief valve 25b for reducing the pressure of the diluted matured flocculant solution in case of an overpressure can be connected to the feeding line 16. The arrangement of the dosing regulator unit 29 and the pressure relief valve 25b can be placed vice versa. For example, the pressure relief valve 25b can be arranged in the outlet of the maturing pressure tank 2 or directly at the outlet of the maturing pressure tank 2. The fluid transport of the solvent, concentrated flocculant solution, diluted flocculant solution and matured flocculant solution is controlled and regulated by a controller 23. Valves and sensors for operating the fluid flow of the solvent, concentrated flocculant solution, diluted flocculant solution and matured flocculant solution are not shown in FIG. 4.

[0113] FIG. 5 shows that an increase of the polymer flocculant concentration increases the viscosity of the aqueous polymer flocculant solution. The polymer flocculant is an Acrylamide-based polymer, Nalco Core Shell® 71038. It can be seen from the graph of FIG. 6 that the viscosity of a 1 wt.-% aqueous polymer flocculant solution has a viscosity of about 3.8 Pa.Math.s (3800 cP). When increasing the viscosity to a 4 wt.-% aqueous polymer flocculant solution, it can be taken from the graph of FIG. 5 that the increase of the viscosity tends to have an exponential increase to a viscosity of about 17 Pa.Math.s (17000 cP). The viscosity was measured with a Brookfield DV-E viscometer at a temperature of 21.4° C., with a S64V-1 spindle at a rotation speed of 20 rpm.

[0114] Conductivity is a good parameter for defining the degree of activation of a polymer depending on the rotation speed.

[0115] FIG. 6 shows the conductivity of a diluted aqueous polymer flocculant solution at a 3 wt.-% concentration stirred at a rotation speed of 405 rpm, 800 rpm and 1345 rpm over time measured in a 250 ml beaker filled with 180 ml of the aqueous polymer flocculant solution. An IKA RW16 overhead stirrer motor with a Philips hand kitchen mixer blade was used for stirring the diluted aqueous polymer flocculant solution. The graph of FIG. 6 clearly shows that the increase of rotation speed increases the conductivity and shortens the time to achieve the maximum conductivity. The conductivity was measured with an EC Testr 11™ available from the company Eutech Instruments.

[0116] Increasing the rotation speed from 405 rpm to 800 rpm and 1345 rpm demonstrate that the conductivity as well as the activation time improves significantly. The conductivity was measured with a SevenGo™ conductivity meter available from the company Mettler Toledo.

[0117] The polymer activation, also named the activity of the mixed diluted polymer solution, is defined as follows:

% Polymer Activation=(Condt−Condw)/(Condf−Condw)×100

wherein: [0118] Condt=Conductivity of the dilute polymer solution at time t [0119] Condw=Conductivity of the make-down water*.sup.1 [0120] Condf=Conductivity of the dilute polymer solution after complete activation and aging *.sup.1=make-down water means the water used for dissolving the neat polymer product. Neat polymer means the undiluted polymer that is the concentrated flocculant polymer solution before reaching the mixing point and before it is diluted with additional solvent, preferably water. The make down water is tap water with a conductivity of 560 μS/cm and a water hardness of 140 mg/l of CaCO.sub.3.

[0121] Another object is directed to a method for preparing and dispensing a flocculant solution to dewater an aqueous process stream with an apparatus as described before, wherein a diluted flocculant solution is obtained with an increase of conductivity. The conductivity increased diluted flocculant solution can be stored and/or matured under pressure in a processing tank, whereby the pressure of the pressurized diluted flocculant solution is uphold when stored in the processing tank.

[0122] According to one aspect of the method the diluted flocculant solution in order to increase the conductivity thereof can be mixed with a mixing pump at about ≧100 rpm (rotation per minute) to about ≦5000 rpm, preferably about ≧200 rpm to about ≦4800 rpm, further preferred about ≧400 rpm to about ≦4600 rpm, more preferred about ≧600 rpm to about ≦4200 rpm and even more preferred about ≧800 rpm to about ≦4000 rpm and most preferred about ≧1000 rpm to about ≦4000 rpm or about ≧2000 rpm to about ≦3000 rpm.

[0123] The increased conductivity of the matured diluted flocculant solution can be upheld, if stored under pressure in the maturing pressure tank.

[0124] The matured flocculant solution may be stored in the maturing pressure tank, for example with an increase of the conductivity, at pressure of at least about ≧15 N/cm.sup.2 to about ≦100 N/cm.sup.2, preferably of at least about ≧20 N/cm.sup.2 to about ≦80 N/cm.sup.2, more preferred of at least about ≧25 N/cm.sup.2 to about ≦60 N/cm.sup.2, further more preferred of at least about ≧30 N/cm.sup.2 to about ≦50 N/cm.sup.2 or about ≧45 N/cm.sup.2 to about ≦75 N/cm.sup.2 for a time period of ≧1 minute to about ≦60 minutes, more preferably a period of about of ≧5 minutes to about ≦20 minutes.

[0125] According to one aspect a diluted flocculant solution is obtained, whereby a concentrated flocculant solution comprises of about ≧10 wt.-% to about ≦60 wt.-%, preferably ≧10 wt.-% to about ≦30 wt.-%, or about ≧40 wt.-% to about ≦50 wt.-% of a flocculant, preferably a polymeric flocculant, is diluted and mixed with a solvent, preferably water, providing a diluted flocculant solution comprising of about ≧0.05 wt.-% to about ≦4 wt.-%, preferably about ≧1 wt.-% to about ≦2 wt.-% flocculant, preferably polymeric flocculant, whereby the wt.-% is based on the total weight of the flocculant solution.

[0126] The concentrated flocculant solution may comprise an organic solvent, preferably a liquid hydrocarbon.

[0127] For example, the activity as well as the conductivity of the matured polymeric flocculant solution can be increased, if stored under pressure for a about ≧1 minute to ≦10 hours, preferably about ≧3 minutes to about ≦5 hours, further preferred about ≧5 minutes to about ≦1 hours, more preferred about ≧5 minutes to about ≦30 minutes or about ≧10 minutes to about ≦20 minutes or about ≧5 minutes to about ≦20 minutes.

[0128] According to one embodiment the pressurized diluted flocculant solution can be stored and/or matured in the maturing pressure tank at a pressure of at least about ≧15 N/cm.sup.2 to about ≦100 N/cm.sup.2, preferably of at least about ≧20 N/cm.sup.2 to about ≦80 N/cm.sup.2, more preferred of at least about ≧25 N/cm.sup.2 to about ≦60 N/cm.sup.2, further more preferred of at least about ≧30 N/cm.sup.2 to about ≦50 N/cm.sup.2 or of at least about ≧45 N/cm.sup.2 to about ≦75 N/cm.sup.2.

[0129] The method comprises further that the diluted flocculant solution that was stored in the pressurized processing tank, also named matured diluted flocculant solution, is dispensed into an aqueous process stream, preferably sludge.

[0130] Another aspect is a method for preparing and dispensing a flocculant solution to dewatering an aqueous process stream with an apparatus as mentioned before, wherein the fluid flow of the pressurized diluted flocculant solution into the process stream is driven by the pressure of the pressurized diluted flocculant solution generated from the mixing pump.

[0131] All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this invention pertains. The invention has been described to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.

LIST OF REFERENCE NUMERALS

[0132] 1 apparatus [0133] 2 maturing pressure tank [0134] 3a mixing pump circuit [0135] 3b diluted flocculant line [0136] 3 diluted flocculant solution [0137] 4 aqueous process stream [0138] 5 mixing pump [0139] 5a mixing pump inlet port [0140] 5b mixing pump outlet port [0141] 6 concentrated flocculant solution [0142] 6a concentrated flocculant solution feeding port [0143] 7 solvent [0144] 7a solvent feeding port [0145] 8 feeding unit [0146] 9 mixing point [0147] 10 calibration vessel [0148] 11 first supply line [0149] 11a supply line circuit [0150] 12 conveyance pump [0151] 13 second solution supply line [0152] 14 solvent source (not shown) [0153] 15 inline mixer [0154] 16 feeding line [0155] 17 multi-way valves (17a/17b) [0156] 18 pressure sensor [0157] 19 overpressure valve [0158] 20 dry run sensor [0159] 21 flow meter [0160] 22 flocculant line [0161] 23 controller [0162] 24 water filter [0163] 25a/b pressure relief valve [0164] 26 solenoid valve [0165] 27 three-way valve [0166] 28 recirculation line [0167] 29 dosing regulator unit [0168] 30 dripping tray