FR2798966A1 - Pressure pump for pumping liquids containing solids in suspension incorporates feed agitator fitted to the drive shaft, which drives the charge towards the pumping element and keeps the solids in suspension in the liquid - Google Patents

Abstract

The pump consists of a tubular envelope (3) with an inlet (12) and a discharge (11). Downstream (6) of the pump is the rotary (7,8) pumping element driven by a shaft (9) from a motor (10). Upstream (5) near the inlet (12) is a screw agitator (13) fitted to the drive shaft (9), which drives the charge towards the pumping element, and at the same time keeps the solids in suspension in the liquid. An Independent claim is also included for the plant incorporating this type of pump including control parameters is part of the claims.

Description

The invention relates to a pressure pump for liquid charged with particles, such as pieces of algae or seeds or animals.

It also relates to the installation, in particular extraction, provided with said pump.

By charged liquid, we understand a mixture of water and particles of relatively large size suspended in water.

In certain processes for the continuous production of a Agar-Agar product, extraction of a material contained in the algae, the result quality depends on the regularity of supply of the means of implementation of the raw material.

This raw material consists of algae reduced into small pieces and kept in suspension in water.

This charged liquid feeds a series of devices transforming the raw material.

To do this, a pump is used which delivers the charged liquid which has been introduced into the pump by gravity.

has already used a so-called MOINEAU pump (FR-957) to do this.

This pump comprises - tubular casing with a substantially horizontal axis, in which are fictitiously delimited a first upstream zone and a second downstream zone - housed in the downstream zone, a stator and a rotor forming the active element of the pump, - housed in the upstream area, a rotor drive shaft, which drive shaft is associated by one of its ends with the rotor and, the other end, with a drive motor located outside the casing tubular, a pump outlet located downstream end of the tubular casing and, a pump supply inlet, located at the upstream region of the tubular casing and through which the fluid penetrates by gravity.

As indicated above, the charged liquid contains particles which tend to collect by sedimentation. The pump is supplied by gravity, the charged liquid being contained in a tank fitted with an agitator.

These pumps which are well known for, in many applications, producing a regular flow fail with this type of charged liquid, to achieve this regularity of flow which can be detrimental to the quality of the product obtained.

The invention proposes in particular to solve the problem indicated above.

The subject of the invention is therefore a pump comprising - a tubular casing with a substantially horizontal axis, which fictitiously comprises a first upstream zone and a second downstream zone, - housed in the downstream zone, a stator and a rotor constituting the active element of the pump, - housed in the upstream area, a rotor drive shaft, which drive shaft is associated at one of its ends with the rotor and, at the other end, with a drive motor located at outside the tubular casing, - a pump outlet located downstream end of the tubular casing and, - a supply inlet, situated at the level of the upstream zone of the tubular casing and through which penetrates by fluid gravity, this pump being characterized in that the rotor drive shaft is at least locally constituted by an endless screw whose propeller oriented to move the charged liquid towards the active element which constitutes the assembly rotor / stator.

The invention also relates to the installation provided with said pump. The invention will be better understood with the aid of the description below given by way of nonlimiting example with regard to the attached drawing which schematically represents - FIG. 1: a pump according to the invention, - FIG. 2: a installation including pump.

Referring to the drawing, it can be seen that, in order to supply the means for implementing the process for producing a material extracted from small pieces suspended in water, this installation 1 comprises a pump 2 for supplying the raw material of different means. Conventionally, this pump 2 comprises - a tubular casing 3 with a substantially horizontal axis 4, which fictitiously comprises a first upstream zone 5 and a second downstream zone, - housed in the downstream zone 6, a stator 7 and a rotor 8 forming the active element of the pump 2, - housed in the upstream zone 5, a shaft 9 for driving the rotor 8, which shaft 9 for driving is associated by one of its ends with the rotor and, by the other end, to a drive motor 10 located outside the tubular casing, - pump outlet 11 located at the downstream end of the tubular casing 3 and, - a supply inlet 12, located at the upstream zone of the tubular casing and through which the fluid penetrates by gravity.

According to a characteristic of the invention, the rotor drive shaft 9 is at least locally provided with an endless screw 13 whose propeller oriented to move the charged liquid towards the active element of the pump that constitutes the rotor / stator assembly.

The diameter of the endless screw 13 is, apart from the operating clearance, identical to the internal diameter of the tubular casing.

According to another characteristic, the worm extends over any length of the upstream zone.

This endless screw 13 is, by that of the associated motor ends, guided in rotation in a bearing, its other end being associated with the rotor by an articulation 100.

The endless is removably attached to the drive shaft or less locally constitutes the drive shaft.

In Figure 2, there is shown an example of an installation for the production of Agar-Agar using the pump according to the invention.

The installation comprises the pump 2 continuously supplying a tubular system 14, that is to say a set of heating pipes arranged in parallel and in series, such as by Joule effect, capable of carrying the reaction mixture between 90 ° C. and 145 ° C. and preferably at 135 C for 10 to 40 minutes and preferably for twenty minutes. The choice of pipe diameter must also be optimal, on the one hand, do not create too great a pressure drop and risk blockage and on the other hand, keep a sufficiently high flow speed for the reasons mentioned above -above. For a type of fluid loaded with algae particles according to the preceding characteristics, a diameter of the order of 15 to 40 millimeters can be a good compromise.

Another important problem which must be resolved during treatment is that of the back pressure in the installation; indeed, it is essential to avoid any vaporization of the water and the product, especially when operating at temperatures above 100 C, such as around 120 to 130 C, knowing that to obtain a product temperature of 125 C at the outlet of the installation, the wall temperatures of the heating tubes must be higher, such as 130 to 140 C, depending on the flow conditions.

The pressure in the installation must therefore be sufficient so that there is no risk of vaporization; for this, it is therefore necessary that the overpressure, both at the inlet and at the outlet of the installation, be greater than that of the vaporization pressure, ie for 120 ° C., 0.194 MPa and at 130 ° C., 0.268 MPa.

To therefore have a certain margin of safety, it is necessary to maintain in the installation an always higher pressure and of the order of 3 bars, which can be created naturally by a flow of the fluid in pipes of length and diameter chosen, to obtain a pressure drop equal to 0.3 MPa. For example, for a flow rate of 1000 liters per hour, at a temperature above 100 C and a diameter of 18 millimeters, as mentioned above, a necessary length of pipe of 469 meters is required, or for a diameter of 15 millimeters, a length of 346 meters, or for a diameter of 12 millimeters a length of 267 meters.

Furthermore, another constraint to be observed in the process according to the invention is the residence time of the diluted algae particles in the heated part which must be of the order of approximately 20 minutes, which for a flow rate of 1000 liters per hour, requires a total volume of tubular chamber of 335 liters.

However, a pipe 469 meters in diameter in 18 millimeters represents only 119 liters; it is therefore necessary to have both the sufficient back pressure and the desired volume, to have a first tubular assembly of larger diameter satisfying the requirements of the volume, followed by a tubular assembly of smaller diameter to create the minimum desired pressure drop defined above, such as for example 322 meters from a 36-millimeter tube followed by 267 meters from a 12-millimeter tube or even 166 meters from a 48-millimeter tube, followed by 346 meters d '' a 15 millimeter tube.

It may be noted, however, that another solution for ensuring the compression of the installation consists in placing a second pump 15 in series after the tubular installation 14 to raise the pressure therein above the said desired value of 0, 3 MPa.

At the outlet of the said heating tubular assembly, which can be defined as comprising a first stage which can be described as a Joule effect driver, to raise the product to the optimum temperature desired followed by a second stage, called a chamber large diameter and maintaining the product at the desired temperature for the minimum desired duration, and finally a third stage called restrictor of smaller diameter conduits, ensuring sufficient back pressure, the entire solution then passes through a means of separation of residues in order to recover the juice containing hydrocolloid polymers such as Agar-Agar, such as in a self-cleaning centrifuge 16 centrifugal, dimensioned in proportion to the preceding reactor, precipitated residues having a final mass equal to three times that initial.

If the centrifugal gravity force applied to the particles is sufficient such as that created by a rotation speed of the order of 7000 Tlmn, clarification of the juice is excellent and allows continuous operation, as in the preceding reactor extractor.

The solution obtained, then containing Agar of 1.5 to 2.5% approximately dilution, can be conveyed for example to a tank 19, for agitated storage, to avoid solidification of the total volume and serving as a buffer before the following steps.

Depending on the subsequent uses, filtration 17 on a candle filter may then be recommended after the centrifugal wringer, in particular for uses in biology. Bleaching can also be recommended in particular embodiments, such as on cationic ion exchange resins 18, in the form for example NH4 +, allowing demineralization of the extraction juice and anionic, in the form for example Co3-, allowing the actual discoloration; the said resins being in a weight ratio relative to the volume of the colloid solution, of 116th and the flux being ascending.

The advantage of using ammonium and carbonate ions is that they are vaporizable during drying, the resulting Agar being then desalted.

Other bleaching techniques can be used.

The juice thus obtained can then be concentrated such as in a vacuum evaporator 20, to bring titration which is of the order of 1.5 to 2.5 as indicated above, ie for example 2%, up to at minus 10%, preferably around 20 lo in weight-volume ratio.

Depending on the use that is sought, it may then be necessary to dry the product thus obtained in order to obtain a conditionable powder, such as in an atomization tower 21 or other means making it possible to reduce the humidity level of the powder. obtained up to a rate of the order of 5 to 10%.

The phases of separation of residues and of concentration until the drying possibly necessary according to the application and according to the process of the invention are preferably those indicated above, although other means can be retained; those preferentially described and represented in the attached single figure make it possible to remain in production and in continuous treatment, always in the form of liquid, following the extraction phase proper by dilution then heating for the extraction of the Agar-Agar , from ground algae, even if these process steps have a lower energy balance than in other methods, such as concentration by freezing / thawing but which does not allow a continuous process.

Various tests have been carried out according to the process of the present invention and their results can be cited by way of example to confirm the optimization obtained such that: - Chondrus and Hypnea algae were thus treated to extract carrageenan; whereas these species traditionally treated with hot water between 90 C and 100 C for more than 15 hours only allow to obtain about 3 kilos of carrageenans per 10 kilos of initial algae, each of these species treated in the tubular system according to the method of the invention with a dilution of 5% or 1I20 in weight / volume ratio at 90 C, made it possible to obtain 6.6 kilos and 5.2 kilos of carrageenans respectively.

The process of the present invention can also be applied to algae residues which have already been used during a first extraction according to a known process, in order to further extract therefrom what would remain in said algae, and thus supplement the yield of production; tests according to the method described above have been carried out on Gelidium algae residues which have therefore already been treated for the extraction of Agar in a factory of a European industrial group; 5 kilos of such residues after circulation, then according to the process of the invention in the tubular reactor with a volume of 100 liters of water, after a treatment of 20 minutes at 135 ° C., allowed another 650 grams of Agar to be recovered, or approximately 13% of the dry weight of starting residues.

Given the fact that approximately 20% of Agar had already probably been extracted, excluding loss during treatment, it appears that more than 16.5% of Agar were therefore extractable from the outset, if the operation following the present invention had been realized as well.

 Different experiments and tests could also be carried out according to the present invention at different temperatures, such as 115 C with a dilution ratio of 1122th; the quantity of Agar dissolved was 1.74% and the average yield 37%, taking into account the quantity of algae at the start.

Another experiment carried out at 125 C at a dilution ratio of 1120th gave an even lower titration but with an excellent yield of%. Another experiment at 135 C with a dilution ratio of 1115th gave an excellent titration of 2.4% but with a poor yield of 37%, having regard to the quantity of algae treated.

Another experiment combining the most favorable conditions of titration and yield above, at 135 C with a ratio of 1120th allowed to obtain titrations and maximum yields of 2.34% and 47 respectively.

With regard to the concentration and drying stages, tests were carried out with 300 liters of 2.5% Agar solution kept at 80 ° C. in a thermostatically controlled tank; this solution is pumped to be brought to the top of an evaporation tower installed in a descending circuit.

A vacuum progressively achieves around -0.04 MPa, allows a boiling temperature around the solution, and the temperature of the inlet vapor is limited to 105 C. The rate of condensation recovered at the end of experience is measured at 262.5 liters, ie a final concentration of the initial solution brought to 20 This solution maintained permanently at more than 70 C remains sufficiently fluid to be then injected into an atomizer, by a nozzle spraying the solution with top of the device.

The incoming air is set at 135 C and the outlet temperature is 85 C; a very fine, uncoloured powder, titrating 5% of humidity is collected, weighed at 7.2 kilos and can then be considered as the desired final product according to the desired application after being cooled.

Unlike the process known in the field of alginate extraction (US-A-3773753), the process the invention does not call for a sufficient viscosity of the mixture during treatment, but on the contrary for its fluidity and a tuburlent regime favorable to mass transfers.

It follows that the diameter and the length of the tubes as well as the linear speed and therefore the flow rate are interdependent factors determined to lead to an adequate residence time to avoid sedimentation of the particles of matter and the effects of lagging.

Heating takes place over the entire length of the treatment path, resulting in optimum efficiency.

In an alternative embodiment of the invention, calculation software is provided to regulate the installation.

The back pressure which is obtained makes it possible to avoid vaporizations in the tube.

In another alternative embodiment of the invention, the back pressure pipe is replaced by a pneumatic valve. Preferably, the butterfly valves or the like are to be excluded because they can induce clogging. The outlet temperature is kept below one hundred degrees Celsius which eliminates the risk of vaporization.

In this example, the installation for producing a product, in particular of Agar-Agar extract, therefore comprises: - a source of raw material supply comprising an agitator, - a pump 2 according to the invention, - a tubular system heated and, - a means of separating residue from the juice.

Claims (2)

<B><U>REVENDICATIONS</U> </B> 1. Pressure pump for liquid loaded with particles such as pieces of algae or seeds or animals, comprising - a tubular casing (3) of substantially horizontal axis (4), which fictitiously comprises a first zone (5) upstream and a second downstream area, - housed in the downstream area (6), a stator (7) and a rotor (8) forming the active element of the pump (2), - housed in the upstream area (5), a rotor drive shaft (9) (8), which drive shaft (9) is associated at one end with the rotor and, at the other end, with a drive motor (10) located outside the tubular casing, - a pump outlet (11) located at the downstream end of the tubular casing (3) and, - a supply inlet (12), located at the upstream area of the tubular casing and through which the fluid penetrates by gravity, this pump being CHARACTERIZED in that the shaft (9) for driving the rotor is at least local ment provided with an endless screw (13) whose propeller is oriented to move the charged liquid to the active element of the pump that constitutes the rotor / stator assembly. 2. Pump according to claim 1 <B> characterized </B> in that the diameter of the endless screw 3) is, apart from operating clearance, identical to the internal diameter of the tubular casing. Pump according to claim 1 <B> characterized </B> in that the worm extends over the entire length of the upstream zone. 4. Pump according to claim 1 <B> characterized </B> in that the endless screw 3) is, by that of the ends associated with the motor, guided in rotation in a bearing, its other end being associated with the rotor by a joint. Pump according to claim 1 characterized in that the endless is removably attached to the drive shaft. Pump according to claim 1 <B> characterized </B> in that the worm constitutes at least locally the drive shaft. 7. Installation for producing material extracted from small pieces of a raw product in suspension, characterized in that it comprises pump according to any one of claims 1 to 6. 8. Installation according to claim 7, characterized in that it comprises - a raw material supply source comprising an agitator, - a pump (2), - heated tubular system and, - means for separating residue from the juice. 9. Installation according to claim 8 characterized in that at the outlet of said heating tubular assembly, which can be defined as comprising a first stage which can be described as a heater, with Joule effect, for mounting the product at the optimum temperature desired followed by a second stage, called a chamberer, with a large diameter and maintaining the product at the desired temperature for the minimum time desired, and finally a third stage known as a restrictor for conduits of smaller diameter, ensuring sufficient back pressure.