DD283490A7 - METHOD AND ARRANGEMENT FOR REGULATING THE PRESSING CONDITIONS OF SEISER PRESSES - Google Patents

Abstract

The invention is applied to the regulation of the pressing conditions of screw presses having a strainer basket. Such screw presses are mainly used in the extraction of oils from oil-rich crops such as rapeseed, linseed, soybean or sunflower seeds and in the pressing of peanuts or copra, but also in the production of rubber. The aim of the invention is to increase the yield during the pressing and to protect the screws against excessive wear. The object of the invention is to provide a method and an arrangement for controlling the pressing conditions of screw presses, in which the pressure of the press can be adjusted by regulating the supply of compressed material. The object is achieved by determining the pressure of the press in the screw press with pressure sensors arranged on the basket of the screw extruder and processing these signals in a computer unit and by means of automatic control effecting a change in the number of revolutions of the metering screw. Fig. 1 {OEl; Copra; oil-rich seeds; Screw press; strainer basket; pressing; Preszbedingungen; Preszdruck; Regulation of the supply of pressed material; Pressure sensor; dosing screw}

Description

For this 3 pages drawings

Field of application of the invention

The invention relates to a method and an arrangement for controlling the pressing conditions of screw presses which have a strainer basket.

Such screw presses are mainly used in the extraction of oils from oil-rich seeds and in the pressing of peanuts or copra, but also in the production of rubber.

Characteristic of the known state of the art

Methods and apparatus for oil recovery from oily material are known.

The oily seeds are usually preconditioned, flocculated and then heated by means of steam in conditioners. Subsequently, usually a pressing of the goods in screw presses, while the vast majority of the oil to be squeezed (DE-OS 1927705).

Furthermore, methods are known in which a preparation of the seeds before the pressing is generally dispensed with. The uncut seed is fed directly after cleaning the screw press (DE-PS 2335385 and DE-PS 2915538).

In all these methods, a screw press is used, in which a worm shaft in a screen chamber, which is usually formed by Seiherstäben is arranged.

The pressure acting on the material to be pressed pressure is realized as a result of a continuous or sudden decrease in the volume formed between Schneckengangwandung, Schneckenkern and Seiherkorb by a special configuration of the worm shaft. This is known, characterized in that either the diameter of the core of the worm shaft is designed progressively or the pitch angle of the worm gear along the worm shaft is constantly increased (DE-OS 3045138). The geometrical configurations and the dimensioning are essentially based on empirical values. The degree of filling of the screw press and the temporal pressure curve are thus crucial criteria for a consistently high yield.

Separately driven stuffing or metering screws are known, the task of which is to ensure a constant volume flow of the seed feed.

The disadvantage here is that an overfeed leads to an increased turbid content in the squeezed oil and in extreme cases, the main screw overloaded by congestion and stuck, on the other hand leads to a Unterspeisung to low yield levels and at the same time to reduce the throughput of the screw press.

Furthermore, such irregularities, such as in particular the driving over the main screw lead to increased wear of the screw and the Seiherstäbe. For this reason, the screw threads of the screw press were provided with hardened inserts (DE-OS 1927705) or coated with a hardened or armored surface.

Also known are solutions in which the supply of the pressed material is realized by means of stuffer drive. The disadvantage here is that it comes with too large supply amount to the backwater of the pressed material.

To reduce the excessive wear and adjustable throttles or cones were attached to the discharge side of the press, which can be changed to control the back pressure within the compression chamber.

Such an annular throttle part is described for example in DE-OS 1944642. In DE-OS 3207878 an axially displaceable sealing sleeve for closing the outlet opening of the screw press is described. The end sleeve should guarantee the build-up of an adjustable backpressure in the press.

Finally, in DE-OS 3321983 an annular throttle is described, which is arranged between the shell and worm shaft. Even with the help of this throttle is ultimately to be regulated by regulating the free cavity between the flights of the compression pressure.

These solutions also have the disadvantage that the actual cause of the fluctuating pressure, namely the non-optimal and not optimal filling of the screw press with pressed material is not eliminated.

Also fluctuating raw material qualities can not be reacted at all during the pressing.

It is known that in the screw press it comes essentially to the formation of an axial pressure exerted by the screw flanks on the material, and a radial pressure resulting from the compression of the material between the screw and strainer.

Object of the invention

The aim of the invention is to increase the yield during pressing of material by means of screw presses and to protect the screw press against excessive wear, at the same time the operator of Seiherschneckenpressen will be able to make a statement about the wear of Seiherstäbe and the consequent loss of yield to be able to make a replacement of Seiherstäbe the optimal time.

Explanation of the essence of the invention

The object of the invention is to provide a method and an arrangement for controlling the pressing conditions of Seiherschneckenpressen, in which the pressing pressure is adjustable by controlling the Preßgutzufuhr.

According to the invention the object is achieved in that continuously the radial pressure of the material to be pressed is determined on the Seiherstäbe, the determined radial pressure is constantly compared with a predetermined target value of the radial pressure and according to the determined difference between measured and predetermined radial pressure, the rotational speed of Metering screw is regulated.

Another feature of the invention is that arranged in the strainer basket pressure sensors are connected to evaluation with a computer unit and the computer unit with a variable speed motor, which is associated with the metering screw of Seiherschneckenpresse connected.

The solution according to the invention leads to the following positive effects and results.

Possibility of regulating the process to a constant residual oil content,

- reducing energy consumption by about 15-20%,

- high availability of the plant,

- for large systems, operation is possible from a central control room,

- increase plant safety,

- consistent product quality,

- the possibility of reacting to fluctuating raw material qualities,

- fast display of malfunctions and

- Receiving a statement about rod and worm wear.

embodiment

The invention will be explained in more detail below using an exemplary embodiment. Show it:

Fig. 1: schematic representation of the arrangement

Fig. 2: schematic representation of a screw press HSP 26th

Fig. 3: Course of the radial pressure in the pressing of rapeseed with an oil content of 39.8% and a humidity of 6.5% with

an HSP 26 Fig.4: Dependence of the throughput of a screw press HSP 26 on the radial pressure.

In the figure 1, the arrangement for controlling the pressing conditions of a Seiherschneckenpresse is shown schematically.

Dabeisind the pressure sensors with transmitter 7 of Seiherfelder 6III to 6Vl Seiherkorbes 1 connected to a computer unit 2.

The computer unit 2 is furthermore connected via a thyristor control 3 to the motor 4 of the metering screw 5. After feeding of rapeseed with an oil content of 39.8% and a humidity of 6.5% on the metering screw 5 is carried out by the main screw 8 compression and pressure, while the squeezed oil passes through the slots of the seed basket. 1

In the exemplary embodiment, the rapeseed was heated by means of a 7-fold heat pad to an inlet temperature of 85 to 90 ⁰ C. The speed of the main screw 8 was 50 min ^-1 . With the pressure sensors with evaluation electronics 7 in the fields 6 III to 6 V1, the radial pressure acting on the rods by the material to be pressed, in this case the rapeseed, is measured Signals converted are supplied to the computer unit 2. By the computer unit 2 the measured radial pressure values are compared with predetermined desired values and according to the determined difference the speed of the motor 4 of the metering screw 5 is regulated with the aid of the output signal of the computer unit 2 via the thyristor control 3. This then has a corresponding change in the volume flow of rapeseed result, which in turn then enters a change in the radial pressure.

That is, the measured radial pressure is lower than the predetermined target value, the rotational speed of the metering screw 5 is increased, whereby the main screw 8, a larger volume of rapeseed is fed.

In Figure 2, the Seiherschneckenpresse is shown with the Seiherfeldern 6I to 6Vl, with two pressure sensors are arranged with evaluation electronics 7 in the Seiherfeldern 6III to 6Vl. Furthermore, the metering screw 5 and the main screw 8 are designated.

Figure 3 shows the radial pressure curve of the measuring points 1-8, wherein the measuring point designation was made along the flow direction of the pressed material. So it is the measuring points 1 and 2 the Seiherfeld β IM, the measuring points 3 and 4 the Seiherfeld 6IV, the measuring points 5 and 6 the Seiherfeld 6V and the measuring points 7 and 8 assigned to the Seiherfeld 6Vl.

FIG. 4 shows the radial pressure measured at the measuring point 3 in relation to the throughput of the screw press under the described test conditions.

Claims (2)

1. A method for controlling the pressing conditions of Seiherschneckenpressen, characterized in that continuously the radial pressure of the pressed material is determined on the Seiherstäbe, the determined radial pressure is constantly compared with a predetermined target value of the radial pressure and according to the determined difference between measured radial Pressure and predetermined radial pressure, the rotational speed of the metering screw is regulated. 2. Arrangement for controlling the pressing conditions of Seiherschneckenpressen, characterized in that arranged in the Seiherkorb (1) of the screw press pressure sensors with evaluation (7) with a computer unit (2) and the computer unit (2) with a variable speed motor (4), which is associated with the dosing screw (5) of the Seiherschneckenpresse connected.