Device and method for thickening a suspension containing fluid substances of different densities

Abstract

The present invention relates to a device (10) for thickening a suspension containing fluid substances of different densities, comprising: a preconditioning apparatus (12) for preconditioning the suspension, by means of which apparatus a conditioning agent can be added to the suspension; a supply unit (14) by means of which the suspension can be transferred to the preconditioning apparatus (12); a metering unit (17) by means of which the conditioning agent can be transferred to the preconditioning apparatus (12); a first measuring apparatus (28) by means of which the transmission (T) of the preconditioned suspension in a free jet (FS) can be determined without contact; a belt filter (32) for gravity-operated draining of the suspension; and a feed unit (30) which is arranged downstream of the preconditioning apparatus (12) and communicates with this apparatus, and by means of which the preconditioned suspension can be fed onto the belt filter (32). The invention also relates to a method by means of which the present device (10) can be operated.

Description

[0001] DEVICE AND METHOD FOR THICKENING A SUSPENSION CONTAINING FLOWABLE SUBSTANCES OF DIFFERENT DENSITY

[0002] The present invention relates to a device and a method for thickening a suspension which comprises flowable substances of different densities.

[0003] These suspensions typically contain solids and liquids, mostly water. One example of such suspensions is sewage sludge, which must be dewatered, particularly to reduce its volume, before being subsequently stored in landfills. In some cases, sewage sludge can be incinerated, and therefore it must be dewatered as much as possible to reduce the associated fuel requirements. Other examples of such suspensions are sludge from the chemical industry, mining, and water treatment, although this list is not exhaustive.

[0004] Such suspensions are typically thickened and dewatered using belt filters. Thickening is the first step in the dewatering process. Thickening involves increasing the dry matter content of the suspension from approximately 1% to a maximum of approximately 5%. For this purpose, the suspension is evenly distributed on a belt filter and dewatered under the influence of gravity, which already achieves a significant reduction in volume. Further dewatering processes can then follow to further increase the dry matter content. For example, a belt filter press can be used for this purpose. The thickened suspension is applied to further belt filters that are guided through rollers, compressing the suspension and releasing liquid. Other dewatering processes can be carried out using screw centrifuges, also called decanters, or vacuum filters.Devices for thickening and dewatering are described, for example, in EP 0 365 165 A2.

[0005] Often, effective separation of liquid from solid is only possible if so-called conditioning agents are added to the incoming suspension. Conditioning agents are often inorganic primary flocculants (metal salts) or organic secondary flocculants (polyelectrolytes). The conditioning agents promote agglomeration or flocculation of the solids contained in the suspension, which supports or even enables thickening using belt filters. Without agglomeration, the suspension would at least partially flow through the openings of the belt filter without achieving any significant thickening.

[0006] The complex optimization task in the separation of flowable materials of different densities using belt filters with regard to the adjustable parameters of conditioning agent quantity and belt speed is to achieve the highest possible dry matter content in the solid phase and the lowest possible dry matter content in the liquid phase while simultaneously using the conditioning agents economically and achieving maximum throughput during the entire dewatering process and especially during thickening.

[0007] Because the residence time of the solids in the device is relatively long, the dry matter content of the emerging solid phase only reflects the conditions in the device with a significant time delay. Furthermore, no reliable, continuously operating dry matter measurements for the solid phase are available. In the device described in EP 0365 165 A2, a portion of the filtrate is removed at various points, and its properties are used as a measurement for optimal operation of the device.

[0008] The escaping filtrate has a strong tendency to form deposits on surfaces that come into contact with the media. Magnesium ammonium phosphate (MAP) is a particularly problematic substance in municipal wastewater treatment. This substance tends to encrustate and can clog entire piping systems over time. The lenses of optical measuring systems that come into contact with the media can become coated within a very short time and require extensive cleaning to ensure reliable, reproducible measurement results.

[0009] Various measuring techniques, in particular for the contactless measurement of various parameters, are disclosed in EP 1241 464 B1, US 3 309 956 A, US 5400 137 A, US 5 489 977 A, EP 0775 907 B1, DE 102015 105 988 B3, DE 102006 050 921 B3, DE 102010 047 046 A1 and DE 3832 901 C2.

[0010] The object of one embodiment of the present invention is to propose a device and a method for thickening a suspension containing flowable materials of different densities, which remedy the situation described above and enable effective thickening of the suspension with a minimal amount of conditioning agent and maximum throughput. This object is achieved with the features specified in claims 1 and 9. Advantageous embodiments are the subject of the dependent claims.

[0011] One embodiment of the invention relates to a device for thickening a suspension which has flowable substances of different densities, comprising

[0012] - a preconditioning device for preconditioning the suspension, with which a conditioning agent can be added to the suspension,

[0013] - a feeding unit with which the suspension can be conveyed to the preconditioning device,

[0014] - a dosing unit with which the conditioning agent can be conveyed to the preconditioning device,

[0015] - wherein the preconditioning device has a first measuring channel with a first free jet section in which the preconditioned suspension forms a free jet,

[0016] - a first measuring device with which the transmission of the preconditioned suspension in the free jet (FS) can be determined without contact,

[0017] - a belt filter for gravity-driven dewatering of the suspension, and

[0018] - a feeding unit arranged downstream of the preconditioning device and communicating with it, with which the preconditioned suspension can be fed onto the belt filter.

[0019] As mentioned at the beginning, in EP 0365 165 A2, for example, the properties of the centrate are measured at various points and used to control or regulate the device shown therein. As also mentioned, the reactions of the properties of the centrate, for example as a result of the change in the amount of conditioning agent, only occur after a comparatively long time. In addition, the composition of the suspension changes relatively quickly in many cases, for example in sewage sludge. In this respect, the devices known from the prior art, for example, cannot be optimally controlled or regulated, which leads in particular to the optimal amount of conditioning agent not being used, but rather to over- or under-dosing.

[0020] Due to the fact that, according to the proposal, the first measuring device is arranged such that the transmission of the preconditioned suspension is measured before the suspension is fed onto the belt filter by means of the feed unit, changes in the composition of the suspension, which are reflected in a change in transmission, can be responded to within a comparatively short time, for example, by changing the amount of conditioning agent. Consequently, the device can be operated at or near the optimum.

[0021] Due to the determination of the transmission on the free jet, the tendency of the preconditioned suspension to form deposits on media-wetted surfaces has no influence on the measurement.

[0022] In a further embodiment, the device

[0023] - a dispensing unit with which the thickened suspension can be removed from the belt filter, and

[0024] - comprise a drive device for driving the belt filter, wherein the belt filter is moved such that the suspension is conveyed from the feed unit to the discharge unit. The drive device can be used to automate the movement of the belt filter. Furthermore, the belt speed and consequently the residence time of the suspension on the belt filter can be changed. The discharge unit can be used to remove the thickened suspension from the belt filter, for example, to feed the thickened suspension to further devices in which further dewatering processes are carried out.

[0025] A further developed embodiment can be characterized in that the device

[0026] - a collecting device in which the belt filter filtrate released from the suspension on the belt filter can be collected,

[0027] - a second measuring channel, which is connected to the

[0028] collecting device and forms a second free jet section, and

[0029] - a second measuring device with which the transmission of the belt filter filtrate can be determined without contact.

[0030] The second measuring device can be used to check whether the optimal conditioning agent quantity determined in the preconditioning unit actually leads to optimal dewatering. If this is not the case, the conditioning agent quantity supplied by the dosing unit can be corrected. Furthermore, the determined transmission of the belt filter filtrate can be used to adjust the belt speed.

[0031] In a further developed embodiment, the device can comprise at least one dewatering device with which the thickened suspension removed from the dispensing unit can be dewatered. In this embodiment, the thickened suspension can be further dewatered after it has left the belt filter. For example, the thickened suspension can be fed to a decanter, a vacuum filter, or a belt filter press to further increase the dry matter content.

[0032] In a further embodiment, the device

[0033] - a further collecting device in which the dewatering filtrate released by the suspension in the dewatering device can be collected,

[0034] - a third measuring channel, which communicates with the further collecting device and forms a third free jet section, and

[0035] - have a third measuring device with which the transmission of the dewatering filtrate can be determined without contact.

[0036] The third measuring device can be used to check whether the optimal conditioning agent quantity determined in the preconditioning unit actually leads to optimal dewatering. If this is not the case, the amount of conditioning agent supplied by the dosing unit can be corrected.

[0037] A further developed embodiment can be characterized in that the first measuring device and / or the second measuring device and / or the third measuring device interact with a control unit with which the feeding unit, the dosing unit, and / or the drive device can be controlled depending on the determined transmission or the change in the determined transmission. Optimization algorithms can be stored on the control unit so that the device can be operated automatically, at least with regard to the amount of conditioning agent and the throughput, optimally or close to the optimum, and thus economically. It should be noted at this point that the term "control unit" should not be understood to mean that the algorithms control the device. Rather, an optimization is performed.

[0038] In a further developed embodiment, the control unit can have at least one signal generator that emits an indication signal when the change in the specific transmission exceeds or falls below a certain value. It is not absolutely necessary for the device to be operated fully automatically. In quite a few cases, the device is monitored by a team of employees of the device operator, who change certain operating parameters depending on the current state of the device. The option of issuing an indication signal to the team of employees when the change in the specific transmission exceeds or falls below a certain value supports the team in initiating appropriate countermeasures in a timely manner in order to be able to operate the device optimally or close to optimally and thus economically.

[0039] In a further developed embodiment, the first measuring device and / or the second measuring device and / or the third measuring device can be configured such that the reflection of the preconditioned suspension, the belt filter concentrate, or the dewatering filtrate can be determined without contact. In addition to the transmission, the reflection determines another property of the preconditioned suspension, the belt filter concentrate, and / or the dewatering filtrate. On the one hand, the reflection measurement can serve as a redundancy in the event that the transmission measurement is disturbed or fails for whatever reason. On the other hand, the determination of the transmission can be checked for plausibility. Overall, the operational reliability of the device is increased.

[0040] One embodiment of the invention relates to a method for thickening a suspension which comprises flowable substances of different densities, with a device according to one of the preceding claims, comprising the following steps:

[0041] - conveying the suspension to the preconditioning device by means of the feeding unit,

[0042] - Promote the conditioning agent to

[0043] Preconditioning device using the dosing unit,

[0044] - Preconditioning the suspension using the preconditioning device,

[0045] - guiding a portion of the preconditioned suspension through the first measuring channel with a first free jet section in which the preconditioned suspension forms a free jet,

[0046] - Contactless determination of the transmission of the preconditioned suspension by means of the measuring device in the first free jet, and

[0047] - Apply the preconditioned suspension to the belt filter.

[0048] The technical effects and advantages that can be achieved with the proposed method correspond to those discussed for the present device. In summary, it should be particularly noted that, by measuring the transmittance of the preconditioned suspension before feeding it onto the belt filter, the amount of conditioning agent can be quickly adjusted to changes in the composition of the suspension, which are expressed in changes in transmittance. This avoids prolonged over- or underdosing, and the device can be operated with the optimal or nearly optimal amount of conditioning agent. By determining the transmittance at the free jet, the tendency of the preconditioned suspension to form deposits on surfaces in contact with the media has no influence on the measurement.

[0049] Advanced training requires that the procedure includes the following steps:

[0050] - Feeding a quantity of conditioning agent (DP) into the preconditioning device with the dosing unit,

[0051] - Changing the conditioning agent quantity (DP) by controlling the dosing unit by means of the control unit depending on the change in the determined transmission (T), and

[0052] - Optimize the amount of conditioning agent (DP) using the relative change in transmittance (T).

[0053] As mentioned at the beginning, the amount of conditioning agent is an essential parameter for the optimal operation of the device. In this embodiment of the method, at least for this parameter, not only can the optimal operating state for the device be found, but in the event of changes, particularly in the composition of the suspension, the device can be returned to the optimal operating state very quickly. The optimal operating state can therefore be continuously monitored. Deviations from the optimal operating state can be promptly detected and corrected. In a further embodiment, the device has

[0054] - a drive device for driving the belt filter,

[0055] - a collecting device in which the belt filter filtrate released from the suspension on the belt filter can be collected,

[0056] - a second measuring channel, which is connected to the

[0057] collecting device and forms a second free jet section, and

[0058] - a second measuring device with which the transmission of the belt filter filtrate can be determined without contact.

[0059] Alternatively or cumulatively, the device

[0060] - a further collecting device in which the dewatering filtrate released from the suspension in the dewatering device can be collected

[0061] - a third measuring channel, which communicates with the further collecting device and forms a third free jet section, and

[0062] - have a third measuring device with which the transmission of the dewatering filtrate can be determined without contact.

[0063] The procedure involves the following steps:

[0064] - Determining the transmission of the belt filter filtrate by means of the second measuring device and / or the transmission of the dewatering filtrate by means of the third measuring device, and

[0065] - Changing the belt speed by controlling the drive device taking into account the specific transmission of the belt filter filtrate and / or the

[0066] Transmission of the dewatering filtrate.

[0067] In addition to the amount of conditioning agent, the belt speed is another important parameter for operating the device at or near optimum performance, as it influences the throughput and the residence time of the suspension on the belt filter. Particularly during subsequent dewatering using belt filter presses, excessive addition of the thickened suspension can lead to it being squeezed out laterally, which can lead to it entering the dewatering filtrate. This can be prevented with an appropriate belt speed.

[0068] Advanced training requires that the procedure includes the following step:

[0069] - Non-contact determination of the reflection of the preconditioned suspension by means of the first measuring device.

[0070] In addition to the transmittance, reflection is used to determine another property of the preconditioned suspension, the belt filter concentrate, and / or the dewatering filtrate. On the one hand, the reflection measurement can serve as a redundancy in the event that the transmittance measurement is disturbed or fails for whatever reason. On the other hand, the determination of the transmittance can be checked for plausibility. Overall, the reliability of the device's operation is increased. In a further embodiment, the method includes the step of evaluating the transmittance of the preconditioned suspension determined by the first measuring device with regard to floc stability. As will be explained in more detail later, a conclusion about the floc stability of the suspension can be drawn based on the transmittance.Where the transmittance of the preconditioned suspension reaches its maximum, the attractive forces within the suspension are at their maximum, which is why floc stability is greatest here. Since the flocs also have the largest diameter at this point, it can be assumed that optimum thickening is also achieved. If further dewatering processes are carried out, these can also be carried out at the optimum with maximum floc stability. Since floc stability is determined on the preconditioned, but not yet thickened suspension, all subsequent processes, especially thickening, can be carried out optimally. In particular, prolonged over- or underdosing of the conditioning agent can be avoided.

[0071] Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawings.

[0072] Figure 1 shows a first embodiment of a device for thickening a suspension based on a basic representation,

[0073] Figure 2A shows a first embodiment of a first measuring device, Figure 2B shows a second embodiment of a first measuring device, and

[0074] Figure 3 shows the course of the transmission, the reflection and the flake stability as a function of the amount of conditioning agent.

[0075] Figure 1 shows a first embodiment of a device 10 according to the invention for thickening a suspension using a schematic representation. The device 10 comprises a preconditioning device 12, with which a suspension to be thickened can be preconditioned by adding a conditioning agent. The suspension is conveyed to the preconditioning device 12 by means of a feed unit 14, which comprises a feed pump 16. Furthermore, the conditioning agent is conveyed to the preconditioning device 12 by means of a metering unit 17, which comprises a metering pump 18. The conditioning agent is added to the suspension in an addition section 19 of the preconditioning device 12.In the illustrated embodiment, the preconditioning device 12 comprises a mixing tube 20 in which the suspension and the conditioning agent can be mixed together. After the suspension and the conditioning agent are mixed together, the suspension is preconditioned. The preconditioning serves to agglomerate or flocculate the solids contained in the suspension.

[0076] The preconditioning device 12 also has a branch 22, from which a first measuring channel 24 extends. The first measuring channel 24 is arranged within the preconditioning device 12 such that a portion of the preconditioned suspension flows through the first measuring channel 24. Consequently, in the first exemplary embodiment, the branch 22 is arranged downstream of the addition section 19 with respect to the flow direction of the suspension through the device 10. The flow direction of the suspension through the device 10 is illustrated by arrows in Figures 1 and 2. Furthermore, the first measuring channel 24 comprises a first free jet section 26, in which the preconditioned suspension forms a free jet FS. In addition, the device 10 is provided with a first measuring device 28, with which the transmission of the preconditioned suspension in the free jet FS can be measured.The design of the first measuring device 28 will be discussed in more detail later.

[0077] Downstream of the preconditioning device 12, a feed unit 30 is arranged, with which the preconditioned suspension can be fed onto a belt filter 32. The belt filter 32, in this case, is designed to be endless around three rollers 34 and can be moved by a drive device 36 at a belt speed. The direction of movement of the belt filter 32 is selected such that the preconditioned suspension is transported away from the feed unit 30 to a discharge unit 38. The belt speed is selected such that, on the one hand, the preconditioned suspension is applied evenly to the belt filter 32 with a small height, covering it as completely as possible.On its way from the feed unit 30 to the discharge unit 38, the preconditioned suspension is subject to the influence of gravity, whereby a portion of the liquid contained in the suspension, typically predominantly water, is extracted from the suspension and flows through the openings of the belt filter 32 (not shown in Figure 1) into a trough-shaped collecting device 40. The liquid collecting in the collecting device 40 is referred to below as the belt filter filtrate. The agglomeration of the solids contained in the suspension prevents the solids from flowing through the openings of the belt filter 32 and entering the belt filter filtrate. A second measuring channel 42 communicates with the collecting device 40 and has a second free jet section 44 in which the belt filter filtrate forms a free jet FS.By means of a second measuring device 46, the transmission of the band filter filtrate in the free jet FS can be determined.

[0078] As mentioned, liquid is removed from the preconditioned suspension on its way to the discharge unit 38, which is why its dry matter content increases. Typically, the dry matter content is approximately 1% when applied to the belt filter 32, whereas it can be up to approximately 5% upon reaching the discharge unit 38. This is then referred to as a thickened suspension. The thickened suspension can be removed from the belt filter 32 by means of the discharge unit 38. In the simplest case, the discharge unit 38 is formed by one of the rollers 34, which deflects the belt filter 32 downwards by at least 90°, but usually significantly more than 90°. In the example shown, the discharge unit 38 also comprises a separator 48, which scrapes the thickened suspension from the belt filter 32 and feeds it into a dewatering device 50, in which the dry matter content of the thickened suspension can be further increased.The dewatering device 50 can be designed, for example, as a decanter, a vacuum filter or as a belt filter press, wherein the provision of the dewatering device 50 is to be regarded as optional.

[0079] A further collecting device 40 is arranged in the dewatering device 50, in which the liquid extracted from the thickened suspension in the dewatering device 50 can be collected. This liquid is referred to below as the dewatering filtrate. A third measuring channel 54 communicates with the further collecting device 52 and has a third free jet section 56, in which the dewatering filtrate forms a free jet FS. The transmission of the dewatering filtrate in the free jet FS can be determined by means of a third measuring device 57.

[0080] Furthermore, the device 10 is equipped with a control unit 58, with which the feeding unit 14, the dosing unit 17, and / or the drive device 36 can be controlled depending on the specific transmission or the change in the specific transmission. Furthermore, the control unit 58 has a signal generator 60, which can output an indication signal, for example, if the change in the transmission exceeds a certain level within a certain time.

[0081] Figures 2A show a first embodiment of a first measuring device 28i, and Figure 2B shows a second embodiment of the first measuring device 28i based on schematic representations. The first measuring device 28i according to the first embodiment has a first light source 661 and a second light source 662 as well as a light receiver 68 (Figure 2A), for example a photodiode, while the second embodiment of the measuring device 282 has a light source 66 and a first light receiver 681 and a second light receiver 682 (see Figure 2B). The beam path of the light is shown in Figures 2A and 2B.Referring to Figure 2A, the portion of the light that emanates from the first light source 661 and passes through the free jet FS of the preconditioned suspension and is received by the light receiver 68 opposite the light source 661 is referred to as transmission T, and the corresponding measurement is referred to as transmitted light measurement. The portion of the light that emanates from the second light source 662 and is reflected from the free jet FS and received by the light receiver 68 arranged on the same side of the free jet FS of the light source 662 is referred to as reflection R, and the corresponding measurement is referred to as incident light measurement. In this respect, the first measuring device 28i, 282 is capable of determining both the transmission and the reflection, both according to the first embodiment and according to the second embodiment. However, the first measuring device 28 can also be designed such that only the transmission is measured.The second measuring device 46 and the third measuring device 57 can be constructed in the same way as the first measuring device 28.

[0082] The device 10 according to the first embodiment is operated as follows: By means of the feed unit 14, a specific volume flow of a suspension to be thickened is conveyed to the preconditioning device 12. In addition, a certain amount of conditioning agent is conveyed to the preconditioning device 12 by means of the dosing unit 17 and mixed there with the suspension. A portion of the thus preconditioned suspension flows through the first measuring channel 24. The transmission in the free jet FS is measured by the first measuring device 28.

[0083] In Figure 3, the transmission T, the reflection R, and the floc stability S of the preconditioned suspension are plotted schematically as a function of the amount of conditioning agent DP. With increasing amount of conditioning agent DP, the transmission T increases due to the increasing clear water spaces between the flocs up to a relative maximum T max In the relative maximum of the transmission T max The preconditioned suspension has the relatively largest proportion of a clear water phase. If the conditioning agent quantity DP is increased, the transmittance T decreases again. This further decrease in the transmittance T is due to the turbidity of the preconditioned suspension caused by excess conditioning agent.

[0084] In contrast to the transmission T, the reflection R measured at the free jet FS of the preconditioned suspension exhibits a fundamentally different curve as a function of the conditioning agent quantity DP. Up to the optimal conditioning agent quantity DP opt the reflection R remains more or less unchanged. Above the optimal amount of conditioning agent DP opt the reflection R increases significantly. This is due to the increasingly milky white color of the preconditioned suspension due to excess conditioning agent.

[0085] As mentioned, Figure 3 also plots the floc stability S of the suspension against the amount of conditioning agent DP. For example, sewage sludge contains bacteria that are similarly charged and therefore repel each other. As the amount of conditioning agent DP increases, these charges are neutralized, resulting in agglomeration forces, which in turn increases the size of the flocs and their floc stability S. However, above a certain amount of conditioning agent DP, all repulsive charges are neutralized. If further conditioning agent is added, these impart a charge to the solids in the suspension, which leads to repulsion and a decrease in agglomeration forces. In addition, shear forces act in the free jet FS, tearing the flocs apart. Where the agglomeration forces and the shear forces are in balance, a stable floc is formed.The greater the agglomeration forces, the greater the floc stability S and the larger the diameter of the flocs. As mentioned, the agglomeration forces pass through a maximum, which coincides with the maximum transmission T. max Assuming that all other variables that influence the agglomeration behavior are kept constant, the floc stability S is greatest at a conditioning agent quantity DP at which the transmission is also greatest, i.e. at T max Since the flakes then also have the largest diameter, it can be assumed that optimum thickening is also achieved.

[0086] The amount of conditioning agent DP which is present at T max is added, represents the most economically advantageous amount of conditioning agent DP optConsequently, the conditioning agent quantity DP is changed with a corresponding control of the dosing unit 17 so that the maximum of the transmission T max can be determined. However, since in many cases the composition of the suspension can change rapidly during operation of the device 10, the maximum of the transmission T max , so that the conditioning agent quantity DP would have to be changed constantly. To counteract this, an optimal range DPB opt the quantity of conditioning agent, which is determined by a maximum permissible deviation of the transmission T from a once determined maximum T maxis limited. As long as the transmission T does not change beyond the maximum permissible deviation, the conditioning agent quantity DP is not changed. The measurement of the reflection R can be used to check the plausibility of the measurement of the transmission T. If a change in the transmission T is registered, the reflection R should also change, and vice versa. If this is not the case, this may be an indication that the first measuring device 28 is not functioning correctly.

[0087] The above statements also apply analogously to the measurement of the transmission T and, if applicable, the reflection R of the belt filter filtrate in the second free jet section 44. However, the following aspect must be taken into account: If the amount of conditioning agent DP added by the dosing unit 17 is in the optimal range, the transmission T of the belt filter filtrate should not change or should change only slightly. If this is the case, the belt speed of the belt filter 32 may be too high or too low. Accordingly, the belt speed can be changed with appropriate control of the drive device 36 until the transmission T remains constant or almost constant. A maximum belt speed is aimed for in order to maximize the throughput of the suspension to be thickened.

[0088] When determining the transmission T of the dewatering filtrate in the third free jet section 56, a change in the transmission T can also be observed when the amount of conditioning agent DPB is in the optimal range. opt This may indicate that some parameters used to operate the dewatering device 50 are not optimal. In a decanter, this may be the differential speed, while in a belt filter press, it may be the belt speeds. If the belt speed is too high, too much of the suspension is passed through the rollers, causing a portion of the suspension to be forced out laterally and fall from the belt filters of the belt filter press directly into the dewatering filtrate, thereby reducing the transmission T.

[0089] List of reference symbols

[0090] 10 Device

[0091] 12 Preconditioning device

[0092] 14 Feeding unit

[0093] 16 Feed pump

[0094] 17 Dosing unit

[0095] 18 Dosing pump

[0096] 19 Encore section

[0097] 20 mixing tube

[0098] 22 Junction

[0099] 24 first measuring channel

[0100] 26 first free jet section

[0101] 28 first measuring device

[0102] 281first measuring device

[0103] 282first measuring device

[0104] 30 task unit

[0105] 32 band filters

[0106] 34 rolls

[0107] 36 Drive device

[0108] 38 dispensing units

[0109] 40 Collection facility

[0110] 42 second measuring channel

[0111] 44 second free jet section

[0112] 46 second measuring device

[0113] 48 separators

[0114] 50 drainage system

[0115] 52 additional reception facilities

[0116] 54 third measuring channel 56 third free jet section

[0117] 57 third measuring device

[0118] 58 Control unit

[0119] 60 signal generators

[0120] 66 light source

[0121] 661 first light source

[0122] 662 second light source

[0123] 68 light receivers

[0124] 681 first light receiver

[0125] 682 second light receiver

[0126] DP Conditioning agent quantity

[0127] DPB opt optimal range of conditioning agent quantity DP opt optimal amount of conditioning agent

[0128] FS free jet

[0129] R Reflection

[0130] S Flake stability

[0131] T Transmission T max maximum transmission

Claims

Patent claims 1. Device (10) for thickening a suspension comprising flowable substances of different densities - a preconditioning device (12) for preconditioning the suspension, with which a conditioning agent can be added to the suspension, - a feeding unit (14) with which the suspension can be conveyed to the preconditioning unit (12), - a dosing unit (17) with which the conditioning agent can be conveyed to the preconditioning unit (12), - wherein the preconditioning device (12) has a first measuring channel (24) with a first free jet section (26) in which the preconditioned suspension forms a free jet (FS), - a first measuring device (28) with which the transmission (T) of the preconditioned suspension in the free jet (FS) can be determined without contact, - a belt filter (32) for gravity-driven dewatering of the suspension, and - one downstream of the preconditioning unit (12) arranged and communicating with the feed unit (30), with which the preconditioned suspension can be fed onto the bandpass filter (32). . Device (10) according to claim 1, characterized in that the device (10) - a dispensing unit (38) with which the thickened suspension can be taken from the belt filter (32), and - a drive device (36) for driving the belt filter (32), wherein the belt filter (32) is moved such that the suspension is conveyed from the feed unit (30) to the discharge unit (38). Device (10) according to one of claims 1 or 2, characterized in that the device (10) - a collection device (40) in which the belt filter filtrate discharged from the suspension located on the belt filter (32) can be collected, - a second measuring channel (42) which communicates with the collection device (40) and forms a second free jet section (44), and - a second measuring device (46) with which the transmission (T) of the belt filter filtrate can be determined without contact. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises at least one dewatering device (50) with which the thickened suspension taken from the dispensing unit (38) can be dewatered. Device (10) according to claim 4, characterized in that the device (10) - a further collection device (52) in which the dewatering filtrate discharged from the suspension located in the dewatering device (50) can be collected, - a third measuring channel (54) which communicates with the further collection device (52) and forms a third free jet section (56), and a third measuring device (57) with which the transmission (T) of the dewatering filtrate can be determined without contact.

6. Device (10) according to one of the preceding claims, characterized in that the first measuring device (28) and / or the second measuring device (46) and / or the third measuring device (57) interacts with a control unit (58) with which the feed unit (14), the metering unit (17) and / or the drive unit (36) can be controlled depending on the specific transmission (T) or the change in the specific transmission (T).

7. Device (10) according to one of the preceding claims, characterized in that the control unit (58) has at least one signal generator (60) which outputs a warning signal when the change in the specified transmission (T) exceeds or falls below a certain value.

8. Device (10) according to one of the preceding claims, characterized in that the first measuring device (28) and / or the second measuring device (46) and / or the third measuring device (57) are arranged such that the reflection (R) of the preconditioned suspension, the belt filter concentrate or the dewatering filtrate can be determined without contact.

9. A method for thickening a suspension comprising flowable substances of different densities, using a device (10) according to any of the preceding claims, comprising the following steps: - Conveying the suspension to the preconditioning unit (12) by means of the feeding unit (14), - Conveying the conditioning agent to the preconditioning unit (12) by means of the dosing unit (17), - Preconditioning the suspension by means of the preconditioning unit (12), - Guiding a portion of the preconditioned suspension through the first measuring channel (24) with a first free jet section (26) in which the preconditioned suspension forms a free jet (FS), - Non-contact determination of the transmission (T) of the preconditioned suspension using the first measuring device (28) in the first free jet (FS), and - Feeding the preconditioned suspension onto the belt filter (32). Method according to claim 9, comprising the following steps: - Conveying a quantity of conditioning agent (DP) into the preconditioning unit (12) with the dosing unit (17), - Changing the amount of conditioning agent (DP) by controlling the dosing unit (17) by means of the control unit (58) depending on the change in the specified transmission (T), and - Optimizing the conditioning agent quantity (DP) using the relative change in transmission (T). Method according to one of claims 9 or 10, wherein the device (10) comprises a drive unit (36) for driving the belt filter (32), - a collection device (40) in which the belt filter filtrate discharged from the suspension located on the belt filter (32) can be collected, - a second measuring channel (42) which communicates with the collection device (40) and forms a second free jet section (26), and - a second measuring device (46) with which the transmission (T) of the bandpass filter filtrate can be determined without contact, - a further collection device (52) in which the dewatering filtrate discharged from the suspension located in the dewatering device (50) can be collected - a third measuring channel (54) which communicates with the further collection device (52) and forms a third free jet section (56), and - a third measuring device (57) with which the transmission (T) of the dewatering filtrate can be determined without contact, and - the procedure includes the following steps: - Determining the transmission (T) of the belt filter filtrate using the second measuring device (46) and / or the transmission of the dewatering filtrate using the third measuring device (57), and - Changing the belt speed by controlling the drive unit (36) taking into account the determined transmission (T) of the belt filter filtrate and / or the dewatering filtrate.

12. A method according to any one of claims 9 to 11, comprising the following step: - Non-contact determination of the reflection (R) of the preconditioned suspension using the first measuring device (28).

13. Method according to any one of claims 9 to 12, comprising the following step: - Evaluating the transmission (T) of the preconditioned suspension determined by the first measuring device (28) with regard to flake stability (S).

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