RU2120825C1 - Taper centrifuge - Google Patents

Abstract

FIELD: farming; chemical and food-processing industries. SUBSTANCE: taper centrifuge includes housing, loading device and two-stage taper rotor secured on shaft. Angles of inclination of generatrices of first and second stage may be different. Spherical insert mounted before each stage is used for creating required rate of supply of product to be separated to filtering surface. Second stage of taper rotor may be provided with curvilinear guide members in form of spiral strips twisted towards rotation of rotor to increase the time of separation. EFFECT: enhanced efficiency. 2 dwg

Description

The invention relates to a device for dewatering suspensions, namely, filter conical centrifuges with inertial discharge of sludge, and can be used in agriculture, chemical, medical, food and other industries. The known centrifuge [1] consists of a housing, a loading device mounted on the shaft of a conical rotor and a spherical insert designed to provide a high speed of dehydrated product to the filter screen of the rotor. The disadvantage of this centrifuge is that in case of dehydration of products forming sediments with high values of friction coefficients, the feed rate from the spherical insert to the rotor should be very high so that the sediment does not become (jammed) during its movement along the rotor. The separation time in this case is significantly reduced, which leads to increased humidity obtained on the scheme from the sediment rotor. For example, with the linear nature of the velocity diagram along the rotor (Fig. 1a), the product separation (dehydration) time is determined by the formula
t _p = S / U _ocp = S / 0.5 • (V _o + V _k ),
where S is the length of the forming surface of the rotor at its height (Hh _b ) and the angle of inclination of the cone α;
V _ocp is the averaged speed of the product (sediment) along the rotor;
V _o - the rate of receipt of the product on the rotor;
V _to - sediment velocity at the exit from the rotor.

To ensure the maximum possible separation time, the velocity V _k at the exit from the rotor should be zero, in this case
t _p.max = S / 0.5 • V _o .

As can be seen from formula (2), the separation time decreases with increasing speed V _o and, in addition, for its creation, the installation of a spherical insert of large height h _in , which leads to an increase in the overall dimensions of the centrifuge.

 The purpose of the invention is to increase the residence time of the product on the centrifuge rotor and thereby provide conditions for deeper dewatering of the resulting sludge.

This goal is achieved by the fact that the rotor of the conical centrifuge is made two-stage, while a spherical insert is installed in front of each stage. The inclination angles of the generators of the first and second stages (α ₁ , α ₂ ) to the axis of rotation of the rotor can be the same or different depending on the properties of the dehydrated product. In addition, to increase the filtering path of the product to be separated and, therefore, the degree of its dehydration, the second rotor stage can be equipped with curved guide elements rigidly fixed on it, made in the form of spiral strips twisted in the direction of rotation of the rotor.

 The invention is illustrated by drawings.

 The centrifuge consists of a housing 4 (Fig. 2), a loading device 1, the first 2 and second 6 stages of the filtering rotor, as well as the first 7 and second 5 spherical inserts rotating with the rotor. The dehydrated product from the loading device enters the bottom 8 of the rotor connected to the shaft 9, the first spherical insert 7 and then, under the action of the centrifugal force component, moves to the wide base of the rotor, i.e. to the vanishing radius, from where the precipitate obtained is discharged into the annular space between the body and the centrifuge rotor.

Since the length of the generatrix of the first stage or cone S _{1 is} less than S (Fig. 1b), the flow rate V _{01 of the} product to be separated from the first spherical insert of height h in ₁ to the filter surface is significantly lower than V _o . If we take into account the rate of descent of the product from the first cone V _k1 = 0, then the separation time at this stage will be equal to
t _p1 = S ₁ / 0.5 • V ⁰¹ = S ₁ / V _{ocp. 1}
The product converging from the first stage of the rotor enters the second (intermediate) spherical insert, where it accelerates to a speed of V ₀₂ . Since the rate of descent of the product (sediment) from the second cone V _{k2 is} also equal to zero, the separation time on it
t _p2 = S ₂ / 0.5 • V ₀₂ = S ₂ / V _ocp.2 ,
Where
C ₂ - the length of the generatrix of the second stage of the rotor.

With the same total height of the single-stage and two-stage rotors (taking into account the height of the spherical inserts), the sum of the lengths of the generators of the first and second steps S ₁ + S ₂ will be not less than the length S of the generatrix of the single-stage rotor. This is because, for example, to create a speed V ₀₁ ≈0.5 • V _0, it is necessary to install a spherical insert (pos. ₇ , Fig. 2), the height of which (h _in1 ) does not exceed half the height h _{in the} inserts on a single-stage rotor . The second (intermediate) insert (item 5, figure 2) is located on a larger radius, and to accelerate the product to a speed of V ₀₂ ≈V ₀₁ it is enough to have an even lower height than h _in1 . Thus, it can be argued that h + h _{c1 c2} ≤h _in, and therefore S ₁ + S ₂ ≥S with the same total height H of the two rotors (1).

Given that each of the averaged speeds V _ocp.1 and V _ocp.2 for the first and second stages of the rotor is less than in a single-stage rotor, the total product separation time t _p1 + t _p2 will be longer than the time t _p determined by formula (1). When using at the second stage of the rotor of the guide elements (item 3, figure 2), the sediment, moving along them, lengthens its path along the filter surface. The time t _p2 and the degree of sludge dewatering increase.

 Using the proposed conical centrifuge allows to increase the time of separation of the product and the amount of filtered liquid, as well as to achieve a deeper degree of dehydration of the resulting sludge.

Sources of information
V. I. Asner, V.S. Kaminsky et al. Design and calculations of filtering centrifuges. M .: Nedra, 1976, p. 23 ... 24.

Claims (2)

 1. A conical centrifuge containing a housing, a loading device, a spherical insert and a conical rotor, characterized in that the rotor is made two-stage, while an additional spherical insert is installed between the first and second steps, and the angles of inclination of the generators of these steps to the axis of rotation of the rotor can be different depending on the properties of the dehydrated product.  2. The centrifuge according to claim 1, characterized in that the second stage of the rotor is equipped with curvilinear elements rigidly fixed to it, made in the form of spiral strips twisted in the direction of rotation of the rotor.

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