DE102012101992A1 - Device useful for reducing water content of starch paste, comprises concentration tank comprising stirrer, inlet and outlet for starch paste and vacuum port for generating vacuum, and heat exchanger having heating element - Google Patents

Abstract

Device for reducing the water content of starch paste, comprises a concentration tank (1) with a stirrer (2) and at least one inlet (5) and outlet for the starch paste, and a heat exchanger (10) having at least one heating element and inlet and outlet for the starch paste, where the concentration tank comprises a vacuum port (3) for generating a vacuum in the concentration tank and for the vacuum evaporation of a water content in the starch paste and the inlet for spray distribution of the starch paste in the concentration tank comprises a nozzle. An independent claim is also included for reducing the water content of starch paste comprising feeding of a starch paste via a nozzle into a concentration tank, reducing the water content of the starch paste in the concentration tank by vacuum evaporation, transferring the starch paste with a reduced water content from concentration tank into a heat exchanger, and heating the starch paste with a reduced water content in the heat exchanger.

Description

The present invention relates to an apparatus and a method for reducing the water content of starch pastes. Furthermore, the invention also relates to the use of the device for the production of highly concentrated starch pastes in particular for use in the field of food and starch industry, as well as the paper, board and / or cardboard industry.

Starch pastes are known in the art. Starch pastes are also referred to as starch solutions and consist essentially of colloidally dissolved starch molecules in water. For this purpose, starch granules contained in a starch suspension are prepared by a boiling process, an enzymatic digestion or oxidative digestion and a so-called starch solution is formed.

Starch is insoluble in cold water. By supplying heat or by alkali, the starch granules can be dissolved. One speaks then of a colloidal solution or a starch paste. For technological and economic reasons, it is advantageous to produce starch pastes which have higher concentrations (solids contents). These are in the prior art at about 42% dry matter.

For example, higher solids coating colors dry faster, thereby saving drying energy, running papermaking machine coater at faster machine speeds, and enabling larger production volumes. Common coating colors contain a high proportion of starch. Thus, higher concentrations of a starch paste, for example, allow higher solids contents of coating colors.

Against this background, it is an object of the present invention to provide an apparatus and a method which at least partially overcome the disadvantages known in the prior art and, in particular, provide highly concentrated starch pastes which may also have improved rheological properties.

The above object is achieved by a device as claimed in claim 1. The method for producing the starch paste according to claim 9 solves the above object, wherein preferred embodiments of the invention are the subject of the respective subclaims.

According to claim 1, the apparatus according to the invention for reducing the water content of starch paste on a Aufkonzentrationsbehälter with a stirrer and at least one inflow and outflow for the starch paste and a heat exchanger with at least one heating element and an inlet and outlet for the starch paste, wherein the Aufkonzentrationsbehälter a Vacuum port for generating a vacuum in the Aufkonzentrationsbehälter and thus for the vacuum evaporation of a water content in the starch paste and the inflow to the spray distribution of the starch pasteurizer in the Aufkonzentrationsbehälter a nozzle.

By reducing the water content of starch pastes in the context of the present invention, the increase in the dry or solid content of the starch paste is understood, which is synonymous with a concentration of the starch paste or the starch solution.

For the purposes of the present invention, a concentration container is understood to mean a container in which the starch paste undergoes an increase in concentration, in particular a reduction in the water content of the starch paste. A reduction of the water content can be carried out in particular by vacuum evaporation. The influencing parameters here are the temperature of the starch paste and the negative pressure acting on the starch paste.

An agitator in the context of the present invention is understood to mean an agitator for mixing, homogenizing the starch paste. This may in particular be an axial, a radial agitator with stirring blades, stirring propellers, stirring fins, paddle mixers, stirring tools.

In the context of the present invention, a heating element is understood to mean energy sources which heat a medium by means of a heat exchanger. This can, for example, electrical heating elements which convert electrical current into heat and / or heating elements which are operated with heat carriers, such as. With hot oil, hot water, steam, etc ..

For the purposes of the present invention, vacuum evaporation means thermal reactors in which a liquid phase, such as e.g. a water content of the starch paste is evaporated at a lower pressure than the environment. Thus, the starch paste can be concentrated by removing a proportion of water to higher concentrations, without simultaneously increasing the temperature disproportionately, thus in particular a gentle concentration can be achieved.

Spray distribution in the sense of the present invention is understood to mean a separation and distribution of starch paste components, whereby the surface of the starch paste, which is accessible in particular for vacuum evaporation, is increased and the accessibility to the starch paste components is improved. This has an advantageous effect on the effectiveness of the vacuum evaporation of the water content in the starch paste.

Under a nozzle according to the present invention is meant a device for the dosage of starch pastes. This can be, for example, an injector, a tapered tube, an outlet slot, an outlet opening, etc.

According to a further, particularly preferred embodiment, the device has at least one storage container and / or collecting container. Alternatively, the device or a plurality of these devices can be operated online, i. be used in particular without storage tank and / or sump.

In the context of the present invention, the term "storage container" and / or "collecting container" is understood to mean a container in which starch paste can be collected or stored buffered. If the storage container and / or storage container of the device upstream so starch paste is collected with low concentration. If the storage tank and / or storage tank downstream of the device so starch paste is collected with high concentration.

A buffer option for previous or subsequent process processes is advantageous here. As a result, for example, fluctuations in the concentration process of the starch pasteurizer can be compensated and any production bottlenecks or production losses can be bridged for a short time.

According to a further, particularly preferred embodiment, the concentration container has at least one level-measuring device and / or one inflow-regulating device.

For the purposes of the present invention, a level measuring device is understood as meaning all possible measuring elements for determining the starch paste level or filling level in the concentration container, such as, for example, measuring probes, ultrasonic measuring devices and floating switches.

Under an inflow control device in the context of the present invention are all possible control elements such as control valves and control slide with which the device can be controlled and in particular also controlled.

It is advantageous in addition to the control and / or regulation a possibility of automation of the device according to the invention.

According to a further, particularly preferred embodiment, the device has at least one annular piping system between the concentration vessel and the heat exchanger, in particular for the circulation mode of operation.

For the purposes of the present invention, a circulation mode of operation is understood as meaning a circulation of the starch paste from the concentration container via the heat exchanger and back into the concentration container. When operating the vacuum evaporation takes place with each pass, a concentration of the starch paste, for example, in the range between 2-5%.

Advantage of this procedure is that the starch paste until the achievement of the concentration to be achieved or if subsequent processes the concentrated starch paste can not decrease, the starch paste can be circulated and partial withdrawals of the starch paste are possible.

According to a further, particularly preferred embodiment, the ring piping system has at least one concentration meter for determining the concentration of the starch pasteurizer and at least one pump and at least one valve for a controllable and / or controllable cycle mode of operation.

The advantage of this embodiment is that depending on the concentration measured with the concentration meter, starch pastes can either be further circulated or driven, for example, into a subsequent feed container and / or collecting container. Thus, with regard to the starch pasteurizer, there is the possibility of partial removal from the circulation and partial supply into the circulation.

According to a further, particularly preferred embodiment, the ring piping system has at least one sampling device.

In the sense of the present invention, a sampling device is understood to mean a device with which a sample can be taken from the tube power system. This may be, for example, a sampling tap, a sampling slide, a sampling nozzle, a sampling tube, a sampling flange, a sampling adapter. The taken sample can be further examined and evaluated and information about parameters and Condition, such as the viscosity, concentration of the starch paste to be determined.

The advantage of this embodiment is that at any time information about parameters and the state of the starch pasteurizer can be obtained and also conclusions can be drawn on the device.

According to a further, particularly preferred embodiment, the device has a separate line system for new starch paste inflow and starch paste guided in the ring pipeline system.

Under a separate conduit system for new starch paste inflow or guided in the ring-piping starch pastes in the context of the present invention is understood that fed via a first line system of new starch paste with low concentration, for example in the range between 25-42% TS of the device, in particular the Aufkonzentrationsbehälter can be supplied via a second line system, in particular a ring-pipe system, driven in the cycle mode and already concentrated starch glue, for example, in the range between 70-80% TS of the device in particular the Aufkonzentrationsbehälter.

Advantage of this device is that the supply of new and recycled starch paste can be done independently and thus desired mixing ratios can be adjusted specifically.

According to a further, particularly preferred embodiment, a multiplicity of devices are arranged in parallel connection or series connection, in particular cascade connection or forward connection.

For the purposes of the present invention, cascade switching means a variant of the reverse switching, so that the passage of a subsequent process stage is returned before the preceding process stage. Thus, in a multi-stage evaporator, the run of the following process stage is returned before the previous process stage.

The object of the present invention is also achieved by a process for reducing the water content of starch pastes comprising at least the following steps of feeding a starch paste into a concentration container by means of a nozzle, reducing the water content of the starch paste in the concentration container by vacuum evaporation, transferring the starch paste with reduced water content from the concentration vessel into a heat exchanger, and the heating of the reduced water content starch paste in the heat exchanger.

Transfer within the meaning of the present invention is understood to mean the transfer, transfer, in particular the pumping of starch pastes through a line into a heat exchanger.

According to a further, particularly preferred embodiment of the method according to the invention, removal of the starch paste with a reduced water content takes place continuously or discontinuously. In this case, the removal into a collection container or online, i. take place directly in another process step or in a further processing stage.

Under continuous in the context of the present invention, the driving is understood that the starch paste driven in the circuit and concentrated by vacuum evaporation, wherein upon reaching the final concentration of the concentrated starch paste continuously discharged from the circulation and the discharged amount of concentrated starch paste by new, still aufkonzentrierenden starch paste is replaced continuously. Alternatively, the circuit mode of operation can also be replaced by a series connection, in particular forward and / or cascade connection. In contrast to a discontinuous procedure, the concentration container does not become empty.

Batchwise in the context of the present invention is understood to mean a batch procedure. Here, the starch paste is circulated so long and concentrated by vacuum evaporation until the final concentration of the concentrated starch paste is reached. In contrast to a continuous mode of operation, the concentration container is now emptied, in particular into a storage container / collecting container, and the process for reducing the water content of starch paste begins anew.

According to a further, particularly preferred embodiment of the method according to the invention, the supply of the starch paste into the concentration container by means of a plurality of nozzles, in particular from 1 to 20, preferably from 5 to 18, particularly preferably made with 10 to 15 nozzles. For example, the nozzles may be evenly distributed, annular, circular, latticed, reticulated, etc. over the liquid surface of the concentration container.

According to a further, particularly preferred embodiment of the method according to the invention, the supply of the starch paste is carried out in the concentration vessel with a metering pressure in the range of 1 to 15 bar, preferably from 2 to 12 bar, more preferably from 3 to 10 bar.

According to a further, particularly preferred embodiment of the method according to the invention, the water content of the starch paste from a starting concentration of the "fresh starch paste" in the range of 55 to 85%, preferably from 58 to 75% to a final concentration in the range of 10 to 50%, preferably be set from 20 to 30%.

For the purposes of the present invention, the water content of the starch paste is determined by determining the moisture content of starch, in particular by the heat-barrier method (US Pat. ISO 1666: 1996 ); German version EN ISO 1666 Understood.

According to a further, particularly preferred embodiment of the method according to the invention, the vacuum evaporation takes place at a reduced pressure in the range from 0.1 to 2 bar, preferably from 0.2 to 1.8 bar, more preferably from 0.3 to 1.6 bar.

In the context of the present invention, negative pressure is understood as meaning the underpressure arising in the concentration vessel by vacuum evaporation.

According to a further, particularly preferred embodiment of the process according to the invention, the residence time of the starch paste in the concentration container is in the range of 1 to 60 minutes, preferably 5 to 50 minutes, more preferably 15 to 40 minutes.

According to a further, particularly preferred embodiment of the method according to the invention, the starch paste fed into the concentration container has a temperature in the range from 60 to 150.degree. C., preferably from 65 to 140.degree. C., particularly preferably from 70 to 135.degree.

According to a further, particularly preferred embodiment of the method according to the invention, the reduction of the water content in the starch paste by means of devices which are arranged in a series circuit, in particular a forward and / or cascade circuit.

For the purposes of the present invention, countercurrent processes are understood to mean that the vapors from first heat exchanger process stages are used to heat up the starch pasteurizer to be concentrated in second heat exchanger process stages. The same applies to other heat exchanger process stages.

According to a further, particularly preferred embodiment of the device according to the invention, the device is used for the method according to the invention.

According to a further, particularly preferred embodiment of the device according to the invention, the device is used for the production of a highly concentrated starch paste, in particular for use in the field of food and starch industry, preferably in the paper, cardboard and / or cardboard industry.

Further aspects of the invention will become apparent from the following detailed description of a possible embodiment of the invention in conjunction with the drawings and the claims. It should be noted that by this example modifications or additions as they are immediately apparent to the skilled person are included. Moreover, the preferred embodiment does not limit the invention to the fact that modifications and additions are within the scope of the present invention. It shows:

1 the viscosity development of a starch suspension with increasing dry content (TS);

2 a schematic representation of the device according to the invention and the inventive method for reducing the water content of starch pastes.

1 shows the viscosity development of a starch suspension with increasing dry content. Shown is the dry content in percent on the x-axis versus the viscosity in mPas on the y-axis. From a dry content of greater than 40% dry matter (TS), a steep increase in the viscosity curve can be observed. The 1 shows that in the prior art, an up-concentration of starch pastes to about 42% DM (solids content) is not yet possible. This limitation is due to the starch suspension, which has a dilatant rheological behavior from a concentration range of about 45-47% TS. The strong increase in viscosity of the starch paste leads to the fact that further added starch powder can no longer be wetted with water and thus the concentration of the starch paste can not be increased further. Usually, the starch is boiled up to about 120 ° C in technical systems. The heat is generally supplied with directly introduced steam in the starch suspension and immediate condensation of the vapor in the suspension. The released heat of condensation results in the temperature rise. The resulting condensate lowers the concentration of the starch paste, for example by about 3% TS, so that the Paste concentration is limited to approx. 42% DM (solids content).

2 shows a schematic representation of the device according to the invention and the inventive method for reducing the water content of starch pastes. The concentration tank 1 the device, with a stirrer 2 and a vacuum connection 3 equipped with low-viscosity starch paste by means of a pump 4 over a tributary 5 filled. The vacuum for vacuum evaporation is with a vacuum pump 6 generated. The level in the concentration tank 1 comes with a level gauge 7 captured and with the pump 4 regulated. From the concentration tank 1 becomes starch paste with a pump 8th withdrawn and into a loop 9 Promoted (cycle). In a subsequent heat exchanger 10 The starch paste is heated near the evaporation temperature of water. The required heat energy is achieved for example via regulated steam or hot water. In the ring line 9 is the concentration of the glue with a concentration meter 11 detected. Concentrated starch is released from the loop 9 over the line 12 taken and in the reservoir 13 Promoted starch paste high concentration. The amount of concentrated starch paste is with a fitting 14 regulated. A return from the cycle takes place via the loop 9 back into the concentration tank 1 over a tributary 15 which has nozzles for spraying the starch paste.

With the device according to the invention or the method according to the invention it is possible to raise the paste concentration from 42 to 80% TS. This is achieved by partially evaporating the water in the starch paste.

The proportionate dehydration takes place by a vacuum evaporation of the water in the paste. This is a concentration tank 1 used in which at a negative pressure of 0.5 to 0.9 bar and a Kleistertemperatur of about 95 ° C, the resulting water vapor is withdrawn.

The feeding of the glue into the concentration tank 1 is done with nozzles, at a pressure of about 2-10 bar, to create a large surface for the product to be evaporated.

The heating of the paste at 90 ° C to 100 ° C takes place in a heat exchanger 10 Instead, using indirect steam or hot water, the paste is brought close to the evaporation temperature of water. As steam process steam is used at about 3 bar, as it is also available on the paper machine. With heating of the glue increases the efficiency of evaporation in the concentration tank 1 at.

To further increase the effectiveness of the method, in particular a circuit-driving, starting from the concentration container 1 via a pump 8th in the heat exchanger 10 and back to the concentration tank 1 , The cyclic cycling amount may be 2-50 times the production of concentrated paste.

The process can be operated continuously or discontinuously:

1. Discontinuous driving style (batch process)

In the discontinuous mode of operation, the concentration container 1 filled with low concentrated starch, started the cycle, heated up the paste and applied the vacuum. Then the concentration of the paste begins until the desired concentration is reached.

Then a product valve opens to the reservoir 13 and the concentration tank 1 is emptied. When the concentration tank 1 When empty, the process starts again.

2. Continuous driving style

In continuous driving, the system starts as under point 1 the discontinuous procedure (batch process). Once the desired concentration is reached, a product valve opens and concentrated starch is continuously added to the reservoir 13 hazards. The desired starch concentration is constantly detected with a concentration meter (eg, mass flow meter) installed in the loop (cyclic process). This device also controls the amount of highly concentrated starch.

Opening the product valve starts the pump as well 4 at the reservoir 16 Starch paste and promotes low concentration starch pastes into the concentration tank 1 , The following quantity balance applies:

F1 = F2 + F3

F1

= Flow rate of low concentrated starch paste

F2

= Flow rate of highly concentrated starch paste

F3

= Amount of water that is evaporated.

After the start-up phase, a stationary state occurs in the system, ie it becomes Constantly fed low concentrated starch and dissipated highly concentrated starch. The difference is the vapor that accumulates as condensate.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• ISO 1666: 1996 [0043]
• EN ISO 1666 [0043]

Claims (20)

Device for reducing the water content of starch pastes containing a concentration container ( 1 ) with a stirrer ( 2 ) and at least one inflow ( 5 . 15 ) and drain for the starch paste, and a heat exchanger ( 10 ) having at least one heating element and an inlet and outlet for the starch paste, characterized in that the concentration container ( 1 ) a vacuum connection ( 3 ) for generating a vacuum in the concentration vessel ( 1 ) and thus for the vacuum evaporation of a water content in the starch paste and the inflow ( 5 . 15 ) for spraying the starch paste into the concentration container ( 1 ) has a nozzle. Device for reducing the water content of starch pastes according to claim 1, characterized in that the device comprises at least one storage container ( 13 . 16 ) and / or collecting containers ( 13 . 16 ) having. Device for reducing the water content of starch pastes according to one of the preceding claims, characterized in that the concentration container ( 1 ) at least one level measuring device ( 7 ) and / or an inflow control device ( 7 ) having. Device for reducing the water content of starch pastes according to one of the preceding claims, characterized in that the device comprises at least one ring piping system ( 9 ) between the concentration vessel ( 1 ) and the heat exchanger ( 10 ) in particular for circulatory driving. Device for reducing the water content of starch pastes according to claim 4, characterized in that the ring piping system ( 9 ) at least one concentration meter ( 14 ) for determining the concentration of the starch paste and at least one pump ( 8th ) and at least one valve for a controllable and / or controllable circulation mode of operation. Device for reducing the water content of starch pastes according to one of claims 4 and 5, characterized in that the ring piping system ( 9 ) has at least one sampling device. Device for reducing the water content of starch pastes according to one of claims 4 to 6, characterized in that the device has a separate line system for new starch paste inflow ( 5 ) and in the ring piping system ( 9 ) guided starch paste ( 15 ) having. A device for reducing the water content of starch pastes according to one of the preceding claims, characterized in that a plurality of devices according to one of claims 1 to 7 are arranged in cascade connection. Process for reducing the water content of starch pastes comprising the steps of: - feeding ( 15 ) of a starch paste by means of a nozzle in a Aufkonzentrationsbehälter ( 1 ); Reduction of the water content of the starch paste in the concentration container ( 1 by vacuum evaporation; Transfer of starch paste with reduced water content from the concentration tank ( 1 ) in a heat exchanger ( 10 ); Heating of the reduced-starch starch paste in the heat exchanger ( 10 ). Process for reducing the water content of starch pastes according to claim 9, characterized in that a removal of the starch paste with reduced water content takes place continuously or discontinuously. Process for reducing the water content of starch pastes according to one of Claims 9 and 10, characterized in that the feed ( 5 . 15 ) of the starch paste into the concentration tank ( 1 ) by means of a plurality of nozzles. Method for reducing the water content of starch pastes according to one of Claims 9 to 11, characterized in that the feed ( 15 ) of the starch paste into the concentration tank ( 1 ) with a metering pressure in the range of 1 to 15 bar, preferably from 2 to 12 bar, more preferably from 3 to 10 bar. Method for reducing the water content of starch pastes according to one of Claims 9 to 12, characterized in that the water content of the starch paste is adjusted to a final concentration in the range from 10 to 50%, preferably from 20 to 30%. Process for reducing the water content of starch pastes according to one of claims 9 to 13, characterized in that the vacuum evaporation at a negative pressure in the range of 0.1 to 2 bar, preferably from 0.2 to 1.8 bar, particularly preferably from 0.3 to 1.6 bar. Method for reducing the water content of starch pastes according to one of Claims 9 to 14, characterized in that the residence time of the starch paste in the concentration container ( 1 ) in the range of 1 to 60 minutes, preferably 5 to 50 minutes, more preferably 15 to 40 minutes. Process for reducing the water content of starch pastes according to one of Claims 9 to 15, characterized in that the product which is introduced into the concentration vessel ( 1 ) has a temperature in the range from 60 to 150 ° C, preferably from 65 to 140 ° C, particularly preferably from 70 to 135 ° C. Process for reducing the water content of starch pastes according to one of claims 9 to 16, characterized in that the reduction of the water content in the starch paste by devices according to one of claims 1 to 8 takes place, which are arranged in a parallel connection or series connection, in particular a cascade connection or forward circuit. Process for reducing the water content of starch pastes according to one of Claims 9 to 17, characterized in that at least one heat exchanger ( 10 ) is operated in countercurrent process. Use of a device according to one of claims 1 to 8 for a method according to one of claims 9 to 18. Use of a device for reducing the water content of starch pastes according to one of claims 1 to 8 for the production of a highly concentrated starch paste especially for use in the field of food and starch industry preferably in the paper, board and / or cardboard industry.

Images