EP0701507B1 - Process for determining and using the quantity of filling press material in solid-liquid separation with a filter press - Google Patents

Abstract

PCT No. PCT/CH95/00062 Sec. 371 Date Nov. 27, 1995 Sec. 102(e) Date Nov. 27, 1995 PCT Filed Mar. 21, 1995 PCT Pub. No. WO95/26874 PCT Pub. Date Oct. 12, 1995A determination of the amounts of fill of material (7) to be pressed in the solid-liquid separation by means of a filter piston press with a pressure element (6) for several successive pressing operations is made with the aid of a consideration in the yield/output diagram. Under a presupposition regarding the position of characteristic curves connecting various operating points in this diagram and by the interposition of an imaginary operating point it is possible to determine the changes in yield and output for each pressing operation and therefore the amounts of refill to be used in such a way that a maximal product of yield and output results for the solid-liquid separation operations when predetermining free process values. The method provides an automatic adaptation of the fill time to the compressibility of the materials. By means of this it is made possible to feed in material (7) of very different compressibility automatically and without having to predetermine reference values in such a way that an optimal behavior is achieved in respect to the yield and the juice extraction behavior of a filter press.

Description

The invention relates to a method for determining and Use of the filling quantities of pressed material in the solid-liquid separation with a filter press comprising one Press room in which liquid under the influence of a press element acted upon by compressive force several successive lifting operations from the pressed material is squeezed, whereby in the course of a filling phase of Separation process in each lifting a quantity in the Press room is introduced.

In such discontinent filter presses is under Exposure to a pressing pressure the liquid portion of the Pressed material is discharged to the outside via a filter. Doing so the pressing pressure directly via a rigid pressure plate or pneumatically or hydraulically via a flexible membrane the pressed material applied. At the beginning of the feed supply the question arises, how much in the press room must be pre-filled so that a first impression there is sufficient press cushion. It should be noted, that with the pressure plate or membrane in front of it Relationship between effective filter area and current one Bale volume is greater than when withdrawn Pressing element.

For the subsequent further filling process, the Question of how much is refilled per stroke of the pressing element should be, so a favorable juicing behavior is achieved. With regard to the to be processed Pressed goods result from organic and inorganic Materials different problems. For organic It is typical that the workability is in materials the press (pressability) from batch to batch changes. A corresponding known continuous Approximate adjustment of the process parameters to achieve optimal pressing processes by hand Operators a lot of experience and largely continuous monitoring of the press during the filling process ahead.

Known attempts, necessary adjustments to the Automating process parameters is unsuccessful remained. A usable model-based recording of the Processes in the pressing process have so far not been successful.

Very high demands on the operator all the stuffing of the food. With a horizontal one Filter presses for fruit material are for example The following setpoint specifications are required:

Total filling quantity. This is strongly dependent on the Pressability of the material to be pressed. Goods that are difficult to press allow only small goods that are easy to press and large ones Allow total fill quantities.

Prefill quantity. The same conditions apply here as with the total filling quantity. Too small or too big The prefill quantity influences the yield / performance behavior very negative.

Filling quantity per piston stroke. At the end of the pre-filling, known pressing process per piston stroke one Filter piston press a defined amount of material to be pressed refilled. This batch-wise filling impulses take place in this way long until the specified total filling quantity as a sum is reached. The right choice of this filling quantity as Process size is strongly dependent on the compressibility of the goods dependent.

Overall, it follows that the press results depend on Skill and experience of the press operator very much turn out differently, because the manual specifications of the Process parameters based on the necessary estimates Yield / performance behavior of the pressing processes rarely let it turn out optimally.

The invention is therefore based on the object specified problems through an optimized procedure for Determination and use of the filling quantities of pressed material at to fix a filter press.

According to the invention, this object is achieved achieved through the following steps: 1) it is under measurement a filling and pressing process of performance and yield executed, which in the yield / performance diagram a first operating point with known performance and Yield leads; 2) for at least one subsequent one second filling and pressing process, which in the yield / performance diagram leads to a second working point at least one process variable for the second operating point set and then using relationships for the changes in performance and yield of solid-liquid separation in the filling and pressing processes under Interposition of a fictitious working point Filling quantity determined and used, which is required so that a maximum product of Yield and performance results, the transition from the first Working point to the fictitious working point by a pure Filling takes place and the transition from fictional Working point to the second working point by a pure one Pressing takes place and it is assumed that the rectilinear connections of those working points which differ by a pure pressing process, differ in Yield / performance diagram in a common Working point with maximum yield and vanishing Cut power or are parallel to each other.

Advantageous embodiments of the method are Find patent claims.

Fig. 1 einen schematischen Schnitt durch eine Filterpresse mit Presskolben nebst einer graphischen Darstellung des zeitlichen Verlaufes von Kolbenhüben und Zuführung des Pressgutes bei unterschiedlichen Regelvorgängen,

Fig. 2 einen schematischen Schnitt durch eine Filterpresse mit Presskolben nebst einer graphischen Darstellung des zeitlichen Verlaufes von Kolbenhüben und Zuführung des Pressgutes bei weiteren Regelvorgängen,

Fig. 3 in einem Ausbeute/ Leistungsdiagramm verschiedene Arbeitspunkte, welche sich bei einer Pressgutzufuhr ergeben,

Fig. 4 in einem Ausbeute/ Leistungsdiagramm verschiedene Presscharakteristiken welche sich bei unterschiedlicher total verarbeiteter Pressgutmenge ergeben,

Fig. 5 in einem Ausbeute/ Leistungsdiagramm verschiedene Regelvorgänge und deren Einfluss auf den Verlauf der Pressvorgänge,

Fig. 6 in einem Ausbeute/ Leistungsdiagramm einen Regelvorgang mit gleichbleibender Leistung als vorgegebener Prozessgrösse,

Fig. 7 in einem Ausbeute/ Leistungsdiagramm einen Regelvorgang mit gleichbleibender Ausbeute als vorgegebener Prozessgrösse,

Fig. 8 in einem Ausbeute/ Leistungsdiagramm verschiedene Arbeitspunkte, welche sich bei einem Füllvorgang ohne gleichzeitige Presswirkung durch eine Presskraft am Presskolben ergeben, und

Fig. 9, in einem Ausbeute/ Leistungsdiagramm verschiedene Arbeitspunkte, welche sich bei erfindungsgemässen Füll- und Pressvorgängen einer Filterkolbenpresse ergeben.

Fig. 10, in einem Ansbeute/ Leistungsdiagramm verschiedene Arbeitspunkte, welche sich bei erfindungsgemässen Füll- und Pressvorgängen einer Filterkolbenpresse mit Vorgabe einer Zielbedingung ergeben.

Embodiments of the invention are explained in more detail in the following description and the figures of the drawing.
Show it:

1 shows a schematic section through a filter press with press plunger, in addition to a graphical representation of the time course of piston strokes and supply of the pressed material in different control processes,

2 shows a schematic section through a filter press with press pistons, in addition to a graphical representation of the chronological course of piston strokes and supply of the press material during further control processes,

3 shows, in a yield / performance diagram, various operating points which result from a supply of pressed material,

4 shows, in a yield / performance diagram, different pressing characteristics which result from different total processed quantities of pressed material,

5 shows in a yield / performance diagram various control processes and their influence on the course of the pressing processes,

6 shows in a yield / performance diagram a control process with constant output as a predetermined process variable,

7 shows a control process with a constant yield as a predetermined process variable in a yield / performance diagram,

Fig. 8 in a yield / performance diagram different operating points, which result in a filling process without simultaneous pressing action by a pressing force on the plunger, and

9, in a yield / performance diagram, various working points which result from the filling and pressing processes of a filter piston press according to the invention.

10, in a heap / performance diagram, various working points which result in the filling and pressing processes according to the invention of a filter piston press with the specification of a target condition.

Fig. 1 shows schematically a horizontal Filter piston press of known type. It comprises one Press cover 11 is located inside the press cover 11 a plunger 6, which is attached to a piston rod 14 is. The piston rod 14 is in a hydraulic Cylinder movably supported and leads over the plunger 6 the pressing operations. In the press jacket 11 is about a closable filling opening by means of a pump 8 the pressed material 7 introduced, which a variety of not penetrates with drainage elements shown.

The drainage elements guide the liquid during the pressing process Phase of the material to be pressed 7 under the pressure of Press plunger 6 into a drain line 10 to the outside. At the pressed material can be fruit and the liquid phase around fruit juice.

The known procedure of pressing is in Usually the following:

Filling process:

• The plunger 6 is withdrawn and at the same time the material to be pressed 7 is filled in through the opening.

Pressing process:

• The whole press unit shown in Fig. 1 is around the Center axis rotates,
• The plunger 6 is advanced under pressure,
• The juice is separated from the pressed material by pressing,
• The pressure is turned off.

Loosening process:

• The plunger 6 is rotated all over Fig. 1 retracted press unit, the leftover pressed material loosened up and torn open becomes.

Another pressing process:

• The process steps of pressing and loosening are called Repetitions per batch of pressed material are repeated several times until a desired final squeezing condition has been reached.

Emptying process:

• The press residues are opened by opening the press jacket 11 emptied.

The procedure for a filter piston press is described with reference to FIG. 1. There are next to that filter piston press scheme already described associated graphical representations shown which the Piston stroke between the positions HM and HS and the Show filling function F over time t. As through the time charts shown next to the press jacket 11 is to Start the material to be pressed 7 continuously by means of the pump 8 fed to the press room via an opening. The Press plunger 6, moving from a position HM and when the HS position is reached, immediately return to his Starting position HM withdrawn. This process will repeated several times. A bar labeled F shows the continuous process running at the same time "Pre-fill".

The "priming" process ends as soon as the Press plunger 6 no longer at position HS reached. Then in a subsequent step only filled in discontinuous phases, each start withdrawing the plunger 6. It is first ensured by a filling control that the Press plunger 6 always the same for each lifting operation HS lying end position reached.

In a further step, the plunger 6 also reaches progressive filling of the press room positions which move further and further away from HS. The Filling control for every lifting and pressing process the yield or the performance of the pressing process constant remains. Reaches the plunger 6 during its advance the position HE, so in a subsequent step then back to the constant end position of the plunger 6 driven until the desired total amount of Press material is filled and the other press strokes only still take place without filling processes F.

Fig. 2 shows in a representation similar to Fig. 1, in which same reference number on same functions indicate separate filling and pressing processes. Before the "pre-filling" recognizable by the bar F begins the plunger 6 to an end position HS. At the subsequent pre-filling, the plunger 6 is not locked, it is reduced to a HM position pushed back without pressing strokes. After At the end of the pre-filling process, a number of strokes are used "Prepress" without filling processes, to which there is another Refill without press strokes as soon as the Press piston 6 exceeds a stroke position HN. Finally, the other press strokes only take place without Filling processes F.

The differently regulated pressing processes described so far as examples can be represented in a yield / performance diagram suitable for basic considerations, as shown in FIG. 3. The agreements apply Output L = (quantity of pressed material supplied) / (working time used) and Yield A = (amount of juice produced) / (amount of pressed material used).

An operating point denoted by 1 in FIG. 3 corresponds a current operating state of the press, like him within a sequence of individual pressings of FIG. 1 and 2 described type immediately after the end of a Lifting process occurs. The plunger 6 is at Working point 1 is still in the pressing position, the working pressure but has already been dismantled. The previous one The lifting process started at operating point 1 '. The working points 1 ', 1 differ only in this lifting process. If you carry out a certain filling quantity in working point 1 Pressed material too, so working point 1 goes into one Working point 3 'above, the power L increases and the yield A decreases. Working points 1, 3 ' differ only in this filling process.

Since in practice, as described for Fig. 1, lifting operations and filling processes are combined, are the transitions 1 ', 1 and 1, 3', and the working point 3 'itself fictitious. Likewise, a lifting operation 3 ', 4' following 3 ', wherein the yield A increases because of the amount of juice produced and the power L because of the working time consumed decreases. It is now assumed that the intersection points A01 and A04 of the elongated linear connections of the Working points 1 ', 1 or 3', 4 'with the A axis, corresponding to a zero power. This enables a process variable for the Specify operating point 4 'and then the required To determine the filling quantity so that there is a maximum Product of yield and performance results.

Although the filling quantities determined in this way are optimal Leading results practically results in a Working point 4 'deviating working point 4 with something lower yield. For the determination of the next the subsequent press stroke process is then combined practically reached point 4 with the previously determined fictitious point 3 ', corresponding to the pair 1, 1' of previous lifting process.

As a summary supplement to FIG. 3, FIG. 4 shows a straight course of the pressing characteristics in the Course of several pure pressing processes. It has Pressed material due to a low total filling quantity Condition a). In comparison, for a state b) the Pressed goods with a larger total filling quantity in the final state another straight line. The extended courses a) and b) run through one under idealized conditions common intersection A0 with the yield axis, corresponding to a performance value of zero. In practice it can this intersection A0 its location during processing change a batch of pressed material.

Fig. 5 shows the power yield comparative Combinations with different regulations of the Press operations can be achieved. Starting from one Pre-filling process R1 with constant power L and increasing Yield A shows the pressing process R2 a regulation with the The goal is constant performance with almost sufficient Refill performance. This is followed by a pressing process R3 without refill. The course b shows a pressing process with insufficient refill performance. The course a finally shows three parts, which one after the other constant end position of the pressing element for everyone Press stroke, with constant yield and finally after End of filling.

6 shows the course in the yield / performance diagram a single pressing process, in which between the Working points 1 at the beginning and 4 at the end the performance is kept constant. You can see an improvement in Products of performance and yield.

Fig. 7 shows the course in the yield / performance diagram a single pressing process, in which between the Working points 1 at the beginning and 4 at the end quantity of pressed material supplied is determined so that the Yield is kept constant. Another one Pressability of the goods can also be a point 4 result in greater power to the right of point 1.

8 shows the course in the yield / performance diagram a pressing process in which during a Pre-fill R1 and several piston strokes comprehensive pre-pressing process is no longer refilled. This process was described in relation to FIG. 2. To the Prepress closes a non-pressing Refill process that leads from point 4 to point 3 '. At the transition from point 3 'to point 4' follow again several pressing processes without refilling. The one for the pressure-free refilling process is used working time through a transition to a virtual working point 1 ' shown.

Fig. 9 shows how in the yield / performance diagram of the Influence of a refill quantity supplied by a theoretical consideration can be captured. Similar to already described for FIG. 3, corresponds to the operating point 1 the current operating status immediately after the end of a single previous press stroke. The plunger 6 (Fig. 1) is still in the pressing position HS, the pressing pressure but already dismantled. Due to the refill quantity Press residues are diluted and the yield is reduced. In a virtually no time consumption through pure filling If you reach point 2, the yield will decrease, while performance remains the same.

If G1 denotes the quantity of pressed material supplied up to point 1, G2 the quantity supplied up to point 2 and A1 and A2 the yields in points 1 and 2, then A2 = A1 (G1 / G2)

In a virtually reached point 3, the performance will increase, while the yield remains the same. If L1 and L3 denote the services in points 1 and 3, then L3 = L1 (G2 / G1)

Since the performance derives from the previously supplied Quantity of pressed material and the amount that has passed up to this point Calculated time, so the performance takes at one Press material feed to. Similar to that described in FIG. 3, point 3, which has been reached virtually, forms the starting point for the theoretical determination of the following, to point 4 leading press step. For this press step is the required consumption Δt of working time by the Press system specified. Since also according to the invention it is assumed that the straight-line extensions the characteristics of the press lifting operations which lead to point 1 and point 4 for zero power lead to the same point A0 on the yield axis by connecting points 3 and A0 the process variables L4 and A4 can be determined for point 4.

If G4 = G3 denotes the quantity fed up to point 4 and Δt the pressing time leading to point 4, then L4 = L3 (G3 / (G3 + L3 * Δt)) and A4 = A0 - ((L4 / L3) * (A0-A3)) L4 = L3 ((A0-A4) / (A0-A3))

From the conditions made and the relationships (1) to (5), the filling quantities to be used per lifting operation can thus be determined according to the invention as differences ΔG of the quantities G4 = G3 or G1 supplied up to points 3 and 1, respectively ΔG = G4 - G1.

For eight successive filling and pressing strokes of a filter piston press as part of a more extensive sequence of such operations for processing a total amount of pressed material of 10,000 kg, with a predetermined approximately constant printing time of 2 minutes per pressing stroke and a constant path (stroke) for all pressing strokes of the press element of 500 mm as the specified process variable, the following table shows the initial values A1, L1, the final values A4, L4, the refill quantities ΔG determined and used according to the invention and the actual strokes achieved: n A1% by weight L1 t / h ΔG kg Stroke mm A4 weight% L4 t / h 1 53.56 17.63 330 499.9 55.65 16.57 2nd 55.65 16.57 220 493.4 57.13 15.78 3rd 57.13 15.78 240 498.7 58.63 15.09 4th 58.63 15.09 210 497.5 59.85 14.51 5 59.85 14.51 210 500.3 61.28 13.90 6 61.28 13.90 190 494.4 62.16 13.50 7 62.16 13.50 220 502.5 63.51 13/01 8th 63.51 13/01 180 494.3 65.19 12.42

Fig. 10 shows similar to Figs. 3 and 9 in a yield / performance diagram the working points that arise if for the second, through a single filling and Lifting process from working point 1 reached working point 4 the condition specifies that the associated values of Yield A4 and power L4 of this operating point 4 one Point 4 on the straight line connecting the first Working point 1 and a working point AF on the Define the yield axis, which is a fixed maximum theoretical yield value for the material to be pressed corresponds.

Specifying such a condition is particularly important then expedient if a pressed material with moderate Pressability is to be processed. For such a thing Material would establish a constant path (Hubes) according to the type of the table example given above deliver a poorer press result.

Claims (9)

1. Process for determining and using the filling quantities of material to be pressed (7) in solid-liquid separation with a filter press including a pressing chamber (11) in which liquid is pressed out of the material to be pressed (7) by means of a plurality of successive strokes by a pressure-operated pressing element (6), a filling quantity being introduced into the pressing chamber (11) in each stroke in the course of a filling phase of the separating operation, characterised by the following steps: 1) a filling and pressing operation is carried out while measuring efficiency (L) and yield (A), leading in the yield/efficiency diagram to a first working point (1) with known efficiency (L1) and yield (A1); 2) for at least one subsequent second filling and pressing operation leading in the yield/efficiency diagram to a second working point (4, 4'), at least one process variable is fixed for the second working point (4, 4') and then a filling quantity (G4) required to give a maximum product of yield (A4) and efficiency (L4) during the separating operation is determined and used using equations for the variations in the efficiency (L) and yield (A) of the solid-liquid separation in the filling and pressing operations, with the interposition of a fictitious working point (3, 3'), wherein the transition from the first working point (1) to the fictitious working point (3, 3') is effected by a pure filling operation and the transition from the fictitious working point (3, 3') to the second working point (4, 4') is effected by a pure pressing operation and it is presupposed that the rectilinear connections of those working points (1', 1; 3', 4') which differ by means of a pure pressing operation intersect in the yield/efficiency diagram in a common working point (AO, AO1, AO4) with maximum yield (A) and decreasing efficiency (L) or are parallel to one another.
2. Process according to claim 1, characterised in that an end position of the pressing element (6) of the filter press is given as the process variable for the second working point (4, 4').
3. Process according to claim 1, characterised in that a yield value of the solid-liquid separation is given as the process variable for the second working point (4, 4').
4. Process according to claim 1, characterised in that an efficiency value of the solid-liquid separation is given as the process variable for the second working point (4, 4').
5. Process according to claim 4, characterised in that the yield value to be expected is determined at the predetermined efficiency value for the second working point (4, 4') and that no filling quantity is supplied when the yield value determined for the second working point (4, 4') is smaller than the known yield value for the first working point (1).
6. Process according to claims 2 and 4, characterised in that the filling quantities required to achieve the predetermined process variables consisting of a constant end position of the pressing element (6) and constant efficiency of the solid-liquid separation with respect to the preceding filling and pressing operation are compared and that the filling quantity required to achieve the predetermined constant efficiency value is used for the filling and pressing operation leading from the first working point to the second working point if this is smaller than the filling quantity required to achieve the predetermined end position.
7. Process according to claims 2 and 3, characterised in that at least two filling and pressing operations are carried out with the filter press, leading in the yield/efficiency diagram to a working point with a predetermined identical constant end position of the pressing element (6) of the filter press and that, for a subsequent working point with an identical constant end position of the pressing element (6), the yield of that filling and pressing operation at which a maximum quantity of liquid is separated off is given as the constant process variable to be achieved.
8. Process according to claims 2, 3, 4, 5, 6 and 7, characterised in that a plurality of filling and pressing operations are carried out with the filter press, leading in the yield/efficiency diagram lead to a plurality of subsequent working points, that at least one process variable to be achieved according to one of claims 2, 3, 4, 5, 6 and 7 is predetermined for a plurality of the subsequent working points and that the filling quantities required in order to achieve the predetermined process variables are determined from the equations for the variations in the efficiency, yield and position of the pressing element (6) in the solid-liquid separation for the filling and pressing operations in order to achieve the subsequent working points and are used for the filling and pressing operations leading to the relevant working points.
9. Process according to claim 1, characterised in that, for the second working point (4, 4'), it is specified that the associated values of yield (A4) and efficiency (L4) result in the yield/efficiency diagram in a working point which is situated on the straight line connecting the first working point (1) and a working point (AF) on the yield axis corresponding to a fixed maximum yield value for the relevant material to be pressed.

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