Intermediate purge mixing plant and associated control method

Abstract

Intermediate purge mixing plant and associated control method The invention relates to a mixing plant (10) for forming a multi-component product. The mixing plant (10) comprises a material flow line (12) provided with a first injection inlet (14), a second injection inlet (16) and a third injection inlet (18). The third injection inlet (18) is arranged downstream of the first injection inlet (14) and the second injection inlet (16). The flow line (12) is provided with a purge (40) upstream of the third injection inlet (18) and downstream of the first injection inlet (14) and the second injection inlet (16), the purge (40) being movable between an active state of purging an upstream portion of the flow line and a passive state in which the purge (40) allows material to flow into the flow line (12). The invention further relates to an associated control method.Figure for abstract: Fig 1.

Description

Title of the invention: Intermediate purge mixing installation and associated control method

[0001] The present invention relates to a mixing installation for forming a multi-component product, the mixing installation comprising a material flow line, the flow line being provided with a first injection inlet for a first component material, a second injection inlet for a second component material and a third injection inlet for a third component material, the second injection inlet being arranged downstream or parallel to the first injection inlet, the third injection inlet being arranged downstream of the first injection inlet and the second injection inlet.

[0002] The invention further relates to an associated control method.

[0003] Such a mixing installation is known for producing a multi-component product.

[0004] Document EP 3 460 242 B1 describes, for example, a pump system for discharging multi-component material under pressure using a spray gun. The system comprises three pumps for each pumping a component material and a control device comprising a control device for regulating a mixing ratio of the component materials.

[0005] However, it may be observed at the output of the system that the multi-component material does not meet the desired criteria.

[0006] It is then necessary to purge the system, which results in a significant quantity of waste that must then be treated. This therefore represents both an economic loss linked to the loss of material, but also to the treatment of the waste.

[0007] In addition, material loss and waste treatment are ecological problems.

[0008] One aim of the invention is therefore to reduce the ecological and financial impact of such a mixing installation.

[0009] To this end, the invention relates to a mixing installation of the aforementioned type, in which the flow line is provided with a purge upstream of the third injection inlet and downstream of the first injection inlet and the second injection inlet, the purge being movable between an active state of purging an upstream part of the flow line and a passive state in which the purge allows the material to flow into the flow line.

[0010] Purging thus offers the possibility of purging only part of the installation, in particular upstream of the third injection inlet. This is advantageous when material upstream of the purge has a defect, not the one downstream.

[0011] According to particular embodiments, the installation comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0012] - the third injection inlet is arranged in an injection block, the purge being arranged upstream of the injection block and adjacent to said injection block;

[0013] - the purge comprises at least one purge valve;

[0014] - the purge comprises a plurality of purge valves, each purge valve being de- placeable between a purge state, in which said purge valve purges material passing into said purge valve, and a flow state, in which said purge valve allows material to flow into the flow line opposite said purge valve;

[0015] - the installation comprises at least one waste container, the purge discharging di directly the material upstream in the flow line into the at least one waste container;

[0016] - the installation comprises at least one purge pipe, the purge pipe being connected to the purge, the purge discharging the material upstream into the flow line in the at least one purge pipe; and / or

[0017] - the installation comprises a rinsing valve arranged and adapted to inject flushing fluid between the purge and the purge pipe.

[0018] The invention further relates to a method for controlling a mixing plant, comprising the following steps:

[0019] - provision of a mixing installation as described above, the purge being in a passive state,

[0020] - injection of a first component material at the first injection inlet,

[0021] - injection of a second component material at the second injection inlet,

[0022] - injection of a third component material at the third injection inlet,

[0023] - tracking the material in the flow line opposite the purge, and

[0024] - moving the purge to the active state based on tracking.

[0025] According to a particular embodiment, the method comprises the following characteristics:

[0026] - the monitoring step includes a step of analyzing the product in the line flow rate with respect to the purge and / or a step of monitoring the time spent between the injection of the second component material and its flow with respect to the at least one purge; and / or

[0027] - the first component material is continuously injected into the flow line, the second component material and the third component material each being selectively injected.

[0028] The invention further relates to a treatment installation for producing a deposit of coating material on a part, comprising a mixing installation according to the invention and an application device, or a sprayer.

[0029] The invention will be better understood on reading the following description, given solely by way of example and with reference to the attached drawing, in which:

[0030] [Fig-1] [Fig. 1] is a schematic view of a first example of a mixing installation according to an embodiment of the invention,

[0031] [Fig.2] [Fig.2] is a schematic view of a second example of installation of mixture according to one embodiment of the invention, and

[0032] [Fig.3] [Fig.3] is a schematic view of a third example of installation of mixture according to one embodiment of the invention.

[0033] The terms “upstream” and “downstream” are hereinafter understood in the usual sense for fluid flow.

[0034] An example of a mixing installation 10 for forming a multi-component product according to the invention is shown in [Fig.l].

[0035] Such an installation makes it possible to produce a mixture of products intended to be sprayed or extruded, for example a paint or a paint base, mastics, lacquers, glues.

[0036] The installation comprises a material flow line 12, in practice supplying an applicator or a spraying device (not shown).

[0037] The flow line 12 is provided with a first injection inlet 14 of a first component material, a second injection inlet 16 of a second component material and a third injection inlet 18 of a third component material.

[0038] The second injection inlet 16 is arranged downstream or parallel to the first injection inlet 14, here in the example shown downstream of the first injection inlet 14.

[0039] The third injection inlet 18 is arranged downstream of the first injection inlet 14 and the second injection inlet 16.

[0040] Thus, the flow line comprises a first portion 20, between the second injection inlet 16 and the third injection inlet 18, and a second portion 22, downstream of the third injection inlet 18.

[0041] The first portion 20 of the flow line 12 is provided for the flow of a material comprising the first component material and the second component material, without the third component material.

[0042] The second portion 22 of the flow line 12 is provided for the flow of a material comprising the first component material, the second component material, and the third component material.

[0043] Each component product is a fluid product.

[0044] The first injection inlet 14 is supplied by a supply 24 of first component material.

[0045] The first component material is, for example, a basic product, here a paint base.

[0046] The supply of first component material to the first injection inlet 14 is, for example, controlled by a first injection valve 26.

[0047] Alternatively, the first injection inlet 14 is supplied continuously without possible interruption by a valve.

[0048] The second injection inlet 16 is adapted to inject the second component material into the first component material circulating in the flow line 12 at the second injection inlet 16, for example at an injection block 28.

[0049] The second injection inlet 16 is supplied by a supply 30 of second component material.

[0050] The second component material is, for example, a catalyst or a hardener.

[0051] The supply of second component material to the second injection inlet 16 is, for example, controlled by a second injection valve 32.

[0052] Alternatively, the second injection inlet 16 is supplied continuously, without interruption by a valve.

[0053] The installation is adapted to dose the first injected component material and the second injected component material according to a first desired ratio of first component material to second component material.

[0054] The first component material and the second component material are then in contact in the first portion 20 of the flow line.

[0055] In one embodiment, the flow line 12 has a mixer, which may comprise a static mixer and / or a dynamic mixer, arranged in the first portion 20 of the flow line 12.

[0056] The mixer is adapted to improve the mixing of the first component material and the second component material.

[0057] The mixing of the first component material and the second component material, called first mixture, causes the start of a reaction between the first component material and the second component material, in the first portion 20 of the flow line 12.

[0058] The reaction comprises, for example, curing and / or drying the first mixture.

[0059] This first mixture has a first lifespan.

[0060] Lifetime is understood to mean the duration during which this first mixture is usable.

[0061] The first lifetime depends in particular on the nature of the first component material and the second component material, and also for example on the ratio of the quantity of first component material to that of the second component material.

[0062] The first lifetime is, for example, less than one hour.

[0063] The third injection inlet 18 is adapted to inject the third component material into the flow line 12 at the third injection inlet 18, more particularly into the first mixture.

[0064] The third injection inlet 18 is arranged in an injection block 34.

[0065] The third injection inlet 18 is supplied by a supply 36 in third component material.

[0066] The third component material is, for example, a diluent, which may comprise water or a solvent.

[0067] The supply of third component material to the third injection inlet 18 is, for example, controlled by a third injection valve 38.

[0068] Alternatively, the third injection inlet 18 is supplied continuously, without interruption by a valve.

[0069] In the present embodiment, the installation is adapted to dose the third component material injected according to a second desired ratio of quantity of third component material to the quantity of first and / or second component material.

[0070] The third component material here dilutes the first mixture in the second portion 22 of the flow line 12.

[0071] In one embodiment, the flow line 12 has a mixer, which may comprise a static and / or dynamic mixer, arranged in the second portion 22 of the flow line 12.

[0072] The mixer is adapted to improve the mixing of the first mixture and the third component material.

[0073] The mixture of the first mixture and the third component material is herein referred to as the second mixture.

[0074] The addition of the third material here results in the dilution of the first mixture.

[0075] This makes it possible in particular to obtain a mixture with the desired viscosity, in particular for optimal subsequent application of the multi-component product.

[0076] The reaction of the first mixture is then, for example, slowed down or stopped, at the time of dilution.

[0077] For example, diluting the first mixture with the third component material makes it possible to delay the hardening of the multi-component product, before it is considered unapplicable.

[0078] This second mixture has a second lifespan.

[0079] The second lifetime is strictly greater than the first lifetime.

[0080] The second lifetime is, for example, greater than two hours.

[0081] The flow line 12 is provided with a purge 40.

[0082] The purge 40 is arranged upstream of the third injection inlet 18 and downstream of the first injection inlet 14 and the second injection inlet 16.

[0083] The purge 40 is here placed as close as possible to the third injection inlet 18.

[0084] In the example shown, the purge 40 is arranged upstream of the injection block 34 comprising the third injection inlet 18 and adjacent to said injection block 34.

[0085] The distance between the purge 40 and the third injection inlet 18 is less than or equal to 5 centimeters.

[0086] The purge 40 is movable between an active purge state and a passive state.

[0087] In the active state, the purge 40 is adapted to purge the part of the line flow line 12 upstream of said purge 40, that is to say here substantially the first portion 20 of the flow line 12.

[0088] In the passive state, the purge 40 allows the material to flow into the flow line 12, i.e. from the first portion 20 to the second portion 22 of the flow line 12.

[0089] In the example shown, the purge 40 comprises a purge valve 42.

[0090] The purge 40 is controllable by a controller 44.

[0091] The purge valve 42 is here a three-way valve comprising an inlet 46 and two exits 48, 50.

[0092] The inlet 46 is connected to the flow line 12 upstream of the purge 40.

[0093] A first outlet 48 is connected to the flow line 12 downstream of the purge 40.

[0094] The input is selectively connected to one of the two outputs.

[0095] More particularly, in the active state of the purge, the input is connected to the second output 50, and, in the passive state, the input is connected to the first output 48.

[0096] The purge 40, more particularly the second outlet 50 of the purge valve 42, is, for example, connected to a purge pipe 52. Thus, the purge 40, in the active purge state, rejects the material upstream in the flow line in the purge pipe 52.

[0097] Several variants can make it possible to achieve this function. In one mode of operation, the sprayer or applicator, at the end of the second portion 22 of flow line 12, is closed, which blocks the flow of material in the second portion 22 of the flow line 12, and then causes, when injecting material into the first portion 20 of flow line 12, a flow of the material in the first portion 20 towards the purge pipe 52. In one variant, the purge valve 42 is able to open the second outlet 50 and to close the first outlet 48 when it goes into the active purge state, which directs the flow of product injected into the first portion 20 towards the purge pipe 52.

[0098] The purge pipe 52 is, for example, connected to a waste container, the material discharged into the purge pipe 52 being discharged into the waste container.

[0099] Advantageously, the installation comprises, for example, a rinsing valve 54 arranged and adapted to inject rinsing liquid between the purge 40 and the purge pipe 52, more particularly between the second outlet 50 and the purge pipe 52.

[0100] The rinsing valve 54 allows the rinsing of the purge pipe 52.

[0101] Alternatively, the installation does not include a purge pipe, but includes a waste container, the purge 40 directly discharging the material upstream in the flow line 12 into the waste container. By “directly” is meant that there is no pipe between the purge 40, more particularly the second outlet 50 of the purge valve 42, and the waste container.

[0102] The controller 44 is able to move the purge 40 between the active state and the passive state.

[0103] The controller 44 is, for example, a tap intended to be moved manually. by a user.

[0104] Alternatively, the controller 44 is an automatic control module.

[0105] The control module is, for example, produced in the form of software, or a software brick, executable by a processor.

[0106] Alternatively, the control module is produced in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or in the form of a dedicated integrated circuit, such as an ASIC (Application Specific Integrated Circuit).

[0107] When the control module is produced in the form of one or more software programs, i.e. in the form of a computer program, it is also capable of being recorded on a medium, not shown, that is readable by a computer. The computer-readable medium is, for example, a medium capable of storing electronic instructions and of being coupled to a bus of a computer system. By way of example, the readable medium is an optical disk, a magneto-optical disk, a ROM memory, a RAM memory, any type of non-volatile memory (for example EPROM, EEPROM, FLASH, NVRAM), a magnetic card or an optical card. A computer program comprising software instructions is then stored on the readable medium.

[0108] The purge 40 is capable of selectively purging the flow line 12 upstream of the purge 40.

[0109] This makes it possible in particular to purge only a portion of the flow line, and not to have to purge the entire flow line, including when the reason for purging is arranged in the first portion of the flow line.

[0110] In the example mentioned, it is, for example, particularly advantageous to be able to purge the flow line at the purge point when at least a part of the first mixture in the first portion was made, by mixing the first component material and the second component material, for a period longer than the first lifetime, whereas the second mixture in the second portion was made for a period shorter than the second lifetime.

[0111] In a first mode of use, the first portion 20 of the flow line 12 is emptied via the purge 40 when it is necessary to drain the product present in the first portion 20.

[0112] For example, if an incorrect dosage ratio between the first product and the second product has been produced and injected into the flow line 12, it is possible to purge the first portion 20 while retaining the mixture present in the second portion 22.

[0113] In another example, during an interruption in use of the installation, it may be necessary to drain the first mixture before it begins to react in the pipe, while retaining the second mixture which has a longer lifespan in the second portion 22.

[0114] Thus, it is possible to purge only the first mixture in the portion of the flow line upstream of the purge, which corresponds substantially to the first portion.

[0115] The entire second mixture in the second portion can therefore be retained in the second portion 22 if there is no need to purge this mixture.

[0116] This results in a significant reduction in the purged material, which is wasted, and in the waste to be treated. In practice, this makes it possible to save the product contained in the pipe between the purge 40 and the device for spraying or applying treatment material. The rate of material thus saved represents a ratio between the volume of product contained in the second portion 22 relative to the volume contained in the flow line 12. In practice, the volume contained in the second portion 22 may represent ten to twenty times the volume contained in the first portion 20. In this hypothesis, it is possible to achieve a product saving of around 90% on a purge compared to a structure in which the product present in the second portion 22 would necessarily be purged at each purge of the first portion 20.In other words, such a structure would make it possible to achieve a reduction of around 90% of the waste produced during a purge of the flow line 12.

[0117] In a variant, it is also possible to inject a rinsing product from the supply of third component material 36 to purge the second portion 22 without purging the first portion 20. For example, the first portion 20 can be cleaned with a first product, for example solvent, and the second portion 22 can be cleaned with a second product, for example water, or a second solvent. This saves the use of polluting solvents.

[0118] In this variant, the valve 42 can be configured to close the first outlet 48, and thus prevent the product injected from the supply of third component material 36 from rising into the first portion 20. This also makes it possible to simultaneously rinse the first portion 20 and the second portion 22 with two different rinsing products, which makes it possible to reduce the time required for rinsing.

[0119] This also makes it possible to carry out a rise of second mixture in the first portion 20 independently of the second portion 22, for example during the rinsing of the second portion 22, which makes it possible to reduce the cycle time.

[0120] In another variant shown in [Fig.2], a valve 60 is located downstream of the third injection point 18.

[0121] The valve 42 of the purge 40 is then, for example, configured to be able to close the inlet 46 and put the first outlet 48 and the second outlet 50 into communication.

[0122] It is then possible to clean the purge pipe 52 from the supply of third component material 36 by closing the inlet 46 with the purge valve 42 and closing the valve 60, for example by injecting third component material 36, this being a diluent, at the third injection point, for example via an injection valve.

[0123] Alternatively, the third injection point is further connected to a cleaning fluid supply, for example via an injection valve.

[0124] Alternatively, the flow line 12 comprises a cleaning injection point arranged between the purge 40 and the valve 60, the cleaning injection point being connected to a supply of cleaning fluid, for example via an injection valve.

[0125] Thus, the inlet 46 of the valve 42 being closed, the third component material or the cleaning material flows to the second outlet 50, in the purge pipe 52.

[0126] It is then no longer necessary to provide a flushing valve for cleaning the purge pipe 52. This reduces the production cost, and increases reliability.

[0127] In another variant shown in [Fig. 3], the purge 140 comprises a plurality of valves 142, 144, each being for example intended to evacuate the mixture towards different waste tanks 146, 148.

[0128] More particularly, the plurality 142, 144 of valves are similar to that described previously and arranged in series and successively along the flow line 112.

[0129] Thus, the first output of each valve 142 apart from the last one is connected to the input of the next valve 144.

[0130] Each valve 142, 144 is, for example, connected at its respective second outlet 150, 152 to a purge pipe 154, 156 or directly to a respective waste container.

[0131] Each purge pipe 154, 156 is, for example, arranged with a waste container 146, 148 and / or a rinsing system 158, 160 as described previously with regard to the case where the purge comprises a valve.

[0132] Alternatively, a valve is located downstream of the purge 140 similarly to what was previously described with regard to [Fig.2].

[0133] Each valve 142, 144 is capable of being moved between a purge state and a passage state. In the purge state, the inlet 162, 164 of the corresponding valve 142, 144 is connected to its second outlet 150, 152, whereas, in the passage state, the inlet 162, 164 of the corresponding valve 142, 144 is connected to its first outlet 166, 168.

[0134] When at least one of the valves 142, 144 is in its respective purge state, the purge 140 is in the active state.

[0135] When all the valves 142, 144 are in their respective passing state, the purge 140 is in a passive state, that is to say that the material entering the purge at the level of the inlet 162 of the first of the valves 142 flows, from valve to valve, until the outlet 168 of the last of the valves 144.

[0136] This allows sorting of purged products for better recycling of the products.

[0137] A method of controlling a mixing plant will now be described.

[0138] A mixing installation as previously described is provided.

[0139] The purge is in the passive state.

[0140] The method comprises injecting a first component material at the first injection inlet 14, injecting a second component material at the second injection inlet 16, and injecting a third component material at the third injection inlet 18.

[0141] In one embodiment, the first component material is continuously injected into the flow line 12, 112, the second component material and the third component material each being selectively injected, more particularly so as to obtain the first desired ratio and the second desired ratio.

[0142] The injection of the second component material is, for example, carried out continuously, the volume flow of second component material being adjusted to obtain the first desired ratio.

[0143] Alternatively, the injection of the second component material is carried out sequentially, so as to obtain the first desired ratio.

[0144] Similarly, the injection of the third component material is, for example, carried out continuously, the volume flow of third component material being adjusted to obtain the second desired ratio.

[0145] Alternatively, the injection of the third component material is carried out sequentially, so as to obtain the second desired ratio.

[0146] Materials flow into the flow line.

[0147] The method comprises a step of tracking the material in the flow line opposite the purge 40, 140 and a step of moving the purge 40, 140 into the active state as a function of the tracking.

[0148] In one embodiment, the step of tracking the material comprises a step of tracking the time spent between the injection of the second component material at the second injection inlet and its flow opposite the purge 40, 140.

[0149] If said time spent is greater than the first lifetime, then the purge is moved, for example automatically by the controller 44, into the active purge state to evacuate the first mixture whose time within the first portion 20 has exceeded the first lifetime.

[0150] The first lifetime is, for example, determined beforehand.

[0151] Once said first mixture, the time within the first portion 20 of which has exceeded the first lifetime, has been evacuated, the purge is then moved back into the passive state.

[0152] Additionally or alternatively, the step of tracking the material comprises a step of analyzing the product in the flow line 12, 112 opposite the purge 40, 140, for example by optical means.

[0153] The optical means are, for example, capable of observing the material passing opposite the purge 40, 140, more particularly the inlet 46, 162 of the purge valve 42 or the first purge valve 142 of the purge 140 according to the flow direction, to detect the state of the first mixture, in particular the level of hardening of the first mixture.

[0154] Alternatively, the viscosity of the second mixture within the first portion 20 is analyzed by means of a viscometer, or two pressure sensors located one downstream of the other at the level of the first portion 20. It is thus possible to deduce the viscosity of the mixture from the flow rate data and the pressure drop in the pipe.

[0155] If the appearance of the first analyzed mixture is not satisfactory, then the purge is moved, for example automatically by the controller 44, into the active purge state to evacuate the first mixture until the appearance is again satisfactory.

[0156] Once said first mixture with an unsatisfactory appearance has been evacuated, the purge is then moved back into the passive state.

[0157] The first mixture discharged is, for example, discharged via the purge pipe 52, 154, 156.

[0158] If necessary, after the purge has passed into the passive state, the rinsing valve 54, 158, 160 is activated, so as to rinse the purge pipe 52, 154, 156.

[0159] Alternatively, the purge pipe 52, 154, 156 is rinsed by closing the valve 60 and the inlet 46, 162 of the purge valve 42 or the first purge valve 142. of the purge 140 according to the flow direction, and injection of the third component material or a cleaning fluid.

[0160] This makes it possible in particular to avoid hardening of the first mixture in the purge pipe.

[0161] Alternatively, the first discharged mixture is, for example, discharged directly into the waste container.

[0162] Thus, the purge 40 makes it possible, firstly, to easily evacuate the first mixture which does not satisfy the criteria, in particular before it hardens and is likely to require cleaning of the installation, or even damage the installation.

[0163] The purge 40 also makes it possible to evacuate only the first mixture which does not satisfy the criteria which then make it possible to obtain a satisfactory multi-component product, and therefore to limit waste on the one hand and the waste to be treated on the other hand.

[0164] In the embodiment of [Fig.3], the method further comprises determining the purge valve 142, 144 to move from its passage state to its purge state to move the purge 40 to the active position.

[0165] The determination is, for example, carried out as a function of the nature of the first mixture passing opposite the purge 40, i.e. to be evacuated.

[0166] For example, if the first mixture is a mixture of a product A and a product B, a first valve is moved from its passing state to its purging state, to purge the first mixture; whereas if the first mixture is a mixture of a product A and a product C, with product C requiring a different treatment than product B for waste treatment, then it will be a second, different valve that is moved from its passing state to its purging state, to purge the first mixture.

[0167] This allows for sorting of purged products with a view to better recycling of the products.

[0168] In a particular embodiment, the multi-component product is composed of strictly more than three component materials.

[0169] The mixing installation comprises strictly more than three component material injection inlets, as described previously, placed successively along the flow line.

[0170] The mixing installation then comprises, for example, upstream of each injection inlet from the third injection inlet, a respective purge as described previously.

[0171] Each purge is capable of being controlled independently, so as to evacuate the material at the level of said purge.

[0172] The control method is then adapted accordingly by tracking the material in the flow line opposite each purge and possibly moving the corresponding purge in active state based on tracking.

[0173] Similarly, this installation makes it possible to purge the flow line in sections and thus limit the quantity of product evacuated.

Claims

Claims

1. Mixing installation (10) for forming a multi-component product, the mixing installation (10) comprising a flow line (12; 112) of material, the flow line (12; 112) being provided with a first injection inlet (14) of a first component material, a second injection inlet (16) of a second component material and a third injection inlet (18) of a third component material, the second injection inlet (16) being arranged downstream or parallel to the first injection inlet (14), the third injection inlet (18) being arranged downstream of the first injection inlet (14) and the second injection inlet (16), characterized in that the flow line (12; 112) is provided with a purge (40; 140) upstream of the third injection inlet (18) and downstream of the first injection inlet (14) and the second injection inlet (16), the purge (40;140) being movable between an active state of purging an upstream portion of the flow line and a passive state in which the purge (40; 140) allows the material to flow into the flow line (12; 112), wherein the third injection inlet (18) is arranged in an injection block (34), the purge (40; 140) being arranged upstream of the injection block (34) and adjacent to said injection block (34).;

2. Mixing installation according to claim 1, in which the purge (40; 140) comprises at least one purge valve (42; 142, 144).

3. A mixing installation according to claim 2, wherein the purge (140) comprises a plurality of purge valves (142, 144), each purge valve (142, 144) being movable between a purge state, in which said purge valve (142, 144) purges material passing into said purge valve (142, 144), and a flow state, in which said purge valve (142, 144) allows material to flow into the flow line (12; 112) opposite said purge valve (142, 144).

4. A mixing plant according to any one of claims 1 to 3, comprising at least one waste container, the purge directly discharging the material upstream in the flow line (12; 112) into the at least one waste container.

5. A mixing installation according to any one of claims 1 to 3, comprising at least one purge pipe (52; 154, 156), the purge pipe (52; 154, 156) being connected to the purge (40; 140), the purge (40; 140) discharging the material upstream into the flow line (12) in the at least one purge pipe (52; 154, 156).

6. Mixing installation according to claim 5, comprising a rinsing valve (54; 158, 160) arranged and adapted to inject rinsing liquid between the purge (40; 140) and the purge pipe (52; 154, 156).

7. A method of controlling a mixing installation (10), comprising the following steps: - providing a mixing installation (10) according to any one of claims 1 to 6, the purge being in a passive state, - injecting a first component material at the first injection inlet (14), - injecting a second component material at the second injection inlet (16), - injecting a third component material at the third injection inlet (18), - tracking the material in the flow line (12; 112) opposite the purge (40; 140), and - moving the purge (40; 140) into the active state as a function of the tracking.

8. Control method according to claim 7, in which the monitoring step comprises a step of analyzing the product in the flow line (12; 112) opposite the purge (40; 140) and / or a step of monitoring the time spent between the injection of the second component material and its flow opposite the at least one purge (40; 140).

9. A control method according to claim 7 or 8, wherein the first component material is continuously injected into the flow line (12; 112), the second component material and the third component material each being selectively injected.

Images