JPS628958Y2 - - Google Patents

Description

[Detailed description of the invention] 1. Technical field of the invention This invention is based on sludge generated during the clarification of water, wastewater, and other liquids, or by adding an organic polymer flocculant or other flocculant to this sludge. This invention relates to an improvement in a screw press type dehydrator having an outer cylinder made of a cylindrical material, which can produce a dehydrated cake with a significantly low water content by continuously compressing and dewatering the flocculated sludge with a screw blade to squeeze out the liquid. It is something.

2. Description of the Prior Art As shown in FIG. 1, a conventional screw press type dehydrator has an outer cylinder 3 of a cylindrical shape provided between a sludge supply port 1' and a cake discharge port 6' of a sludge hopper 2'. ' (hereinafter simply referred to as outer cylinder 3') and a screw shaft 5' having screw blades 4' on the outer periphery, and an annular gap formed by the outer cylinder 3', screw shaft 5', and screw blade 4'. Steam was provided in the screw shaft 5' while the volume was gradually reduced as appropriate and the sludge introduced into the sludge supply port 1' was pushed out in the axial direction, that is, in the direction of the cake discharge port 6' by the rotation of the screw shaft 5'. The steam flows in from the inlet 9' and is supplied into the screw shaft 5' to transfer heat to the sludge, and the sludge is sequentially squeezed while increasing the sludge temperature. It has a structure and function such that the cake can be taken out from the cake discharge port 6'. In addition,
7' is a screw shaft drive shaft, 8' is a screw shaft drive device, and 10' is a drain outlet.

Generally, when dewatering sludge while heating it, the higher the sludge temperature, the lower the viscosity of the water contained in the sludge, making dewatering easier, and the shorter the dewatering time (the faster the dewatering speed). ), or if the dehydration time is constant, the moisture content of the dehydrated cake produced tends to be lower, and since the viscosity of the liquid that passes through the cake during press dehydration is low, the amount of solids flowing out with the liquid is reduced. There is a tendency. The screw press type dehydrator is also similar to this example, and as shown in Figure 1, steam is passed through the internal space of the screw shaft 5' and heat is transferred to the sludge from the surface of the screw shaft 5', increasing the temperature of the sludge while compressing and dewatering it. ing.

Additionally, in general, when compressing and dewatering sludge with a high solids concentration, all of the compressing pressure applied is supported by the sludge particles from the material surface, so it does not affect the water contained in the sludge near the material. It is being said. It is said that dewatering of sludge in such a state progresses more if vacuum pressure is applied from the surface of the material.

In a screw press type dehydrator, the sludge near the sludge supply port 1' has a low solids concentration, so all of the pressure applied to the sludge is supported by the water contained in the sludge, resulting in dewatering. The sludge in the vicinity of 6' has progressed to a high concentration of solids, and all of the pressure applied to the sludge is due to dewatering by compression supported by the sludge particles. Therefore, high squeezing pressure is applied to the sludge near the cake discharge port 6', but dewatering is not progressing despite the high pressure.

When the solid concentration of sludge increases and dehydration changes from excessive dehydration to compression, the compression pressure is no longer applied to the water contained in the sludge, so if vacuum pressure is applied to the water contained in the sludge from the outside of the material, dehydration will proceed. A dehydrated cake with a low moisture content can be obtained.

In the conventional device shown in Fig. 1, the screw shaft 5'
Steam flows into the internal space of the screw shaft 5' from the steam inlet 9', heats the surface of the screw shaft 5', and transfers the heat to the annular shape formed by the outer cylinder 3', the screw shaft 5', and the screw blades 4'. The temperature of the sludge is increased to reduce the viscosity of the water contained in the sludge, and the sludge is dehydrated by squeezing and squeezing, but there is no vacuum pressure from the outer surface of the outer cylinder 3' and the cake discharge port If the solid concentration of the sludge increases near 6' and dewatering progresses through compression, the amount of liquid discharged will be larger than when the sludge is not heated and the viscosity of the water in the sludge is high; Since almost no pressure is applied, the amount of liquid discharged from the outer cylinder 3' is small and a dehydrated cake with a high moisture content is produced.

3. Purpose of the invention The object of the invention is to economically provide a sludge dehydrator that can effectively eliminate the above-mentioned drawbacks of conventional screw press type dehydrators.

4. Structure of the invention The present invention has a screw shaft rotatably disposed inside a cylindrical outer cylinder having a sludge supply port and a cake discharge port, which has screw blades on the outer periphery and can be heated with steam inside. A screw press that sequentially reduces the annular gap volume formed by the outer cylinder, the screw shaft, and the screw blade toward the cake discharge port, and discharges the sludge from the cake discharge port while compressing and dewatering the sludge by rotation of the screw shaft. In the type dehydrator, a cylinder body is provided concentrically in the rear half of the outside of the outer cylinder to form an annular chamber, a steam evacuator is attached to the steam inflow part to the screw shaft, and a suction port of the steam evacuator and The screw press type dehydrator is configured to communicate with the annular chamber via an exhaust pipe and to reduce the pressure in the annular chamber with the steam evacuator.

5. Embodiments of the invention Hereinafter, embodiments of the invention will be described with reference to FIGS. 2 and 3.

This dehydrator is equipped with sludge supply port 1 of sludge hopper 2.
and a cylindrical outer cylinder 3 provided with a cake discharge port 6.
(hereinafter simply referred to as the outer cylinder 3), a screw shaft 5 having a screw blade 4 protruding from the outer periphery and a steam inlet 9 and a drain outlet 10 is rotated by a screw shaft drive shaft 7 and a screw shaft drive device 8. The cylindrical body 11 is placed in the rear half of the outer tube 3 so as to surround the outer tube 3.
A steam ejector 12 is installed concentrically with the steam inflow port 9 to the screw shaft 5, and a suction port 12a of the steam ejector 12 is installed.
and a hollow annular chamber 11a formed by the outer cylinder 3 and the cylinder body 11 are communicated via an exhaust pipe 13 having a liquid tank 15 in the middle, and the inside of the annular chamber 11a is evacuated by a steam evacuator 12 to reduce the pressure. It has a unique structure. Note that 14 is a rotary joint.

Therefore, the sludge hopper 2 with the sludge supply port 1
The sludge introduced into the tube flows into the annular gap formed by the outer cylinder 3, the screw blade 4, and the screw shaft 5, and the liquid is discharged from the outer cylinder 3 and transported to the cake discharge port 6 by the rotation of the screw shaft 5. In addition, the steam inflow port 9 to the screw shaft 5
Steam is blown into the space of the screw shaft 5 through the steam ejector 12 and the rotary joint 14, and the drain generated here is discharged from the drain outlet 10, thereby heating the surface of the screw shaft 5. This heat is transferred to the sludge, raising the temperature of the sludge, and sequentially over-squeezing the sludge by reducing the volume of the annular gap, and the outer cylinder 3 and The inside of the annular chamber 11a formed by the cylinder 11 is evacuated and depressurized, vacuum pressure is applied from the outer surface of the outer cylinder 3 to dehydrate the sludge in the annular gap, and the liquid discharged from the material surface of the outer cylinder 3 is transferred to a liquid tank. 15 and takes out the dehydrated cake from the dehydrated cake outlet 6.

That is, in the dehydrator of the present invention, the rear half of the outer cylinder 3 is covered with the cylinder body 11 and has a sealed annular chamber 1.
1a, and the inside of this annular chamber 11a is evacuated and depressurized by the steam evacuator 12, so that the sludge with a low solids concentration fed into the sludge supply port 1 fills the volume of the annular gap. As the sludge is reduced, it is sequentially over-pressed and dewatered, increasing the solids concentration.Moreover, the steam that has flowed into the space of the screw shaft 5 transfers heat, and when the sludge is sent to this area, it is in a high temperature state and is absorbed into the gap. Since the squeezing pressure due to volume reduction and the vacuum pressure from the outer surface of the material of the outer cylinder 3 are applied at the same time, it is possible to easily dehydrate the water in the sludge that cannot be easily dehydrated by simply squeezing pressure at room temperature, resulting in dewatering with a low water content. The cake can be discharged from the cake discharge port 6.

Further, only the rear half of the outer cylinder 3 is covered with the cylinder 11 and has a structure of a sealed annular chamber 11a, and the front half of the outer cylinder 3 is not covered with the cylinder 11. For this reason, the steam ejector 12 is applied to the front half of the outer cylinder 3 where the concentration of solids is low and dehydration proceeds easily with low overpressure without applying vacuum pressure from the outer surface of the outer cylinder 3, and a large amount of liquid is discharged. Vacuum pressure is not applied, and the vacuum pressure from the steam ejector 12 is applied only to the rear half of the outer cylinder 3, where the solid concentration of the sludge is high to a certain extent and the amount of liquid discharged is small, so the amount of displacement is small. The inside of the annular chamber 11a can be maintained in a reduced pressure state. In other words, the load on the steam evacuator 12 can be reduced.

Furthermore, the device of the present invention has a steam ejector 12 that uses steam for heating the screw shaft 5.
generates vacuum pressure. For this reason, the steam ejector 12 has the advantage that it is less likely to break down compared to a vacuum pump, and also has the advantage that it uses the steam for heating the screw shaft 5 as its power source and does not require a special power source to generate vacuum pressure. have.

In the screw press of the present invention, the mounting position of the cylinder 11 to the outer cylinder 3 is the rear half of the outer cylinder 3,
In terms of numerical values, the latter half of 1/2 to 1/3 of the total length of the outer cylinder 3 is preferable.

That is, the sludge introduced into the sludge supply port 1 flows into the annular gap formed by the outer cylinder 3, the screw blades 4, and the screw shaft 5, and as the volume decreases, overpressure is gradually applied. Since the solid concentration is low, the liquid is easily discharged from the sludge, so the rate of increase in overpressure is small.
As the solids concentration gradually increases, the overresistance increases when the liquid is separated from the sludge, and as a result, the overpressure increases, and the rate of increase in pressure suddenly increases compared to the first half. The point where the rate of increase in pressure suddenly increases varies depending on the properties of the input sludge or the concentration of solids, but it is generally in the latter half of the outer cylinder 3, from 1/2 to 1/3 of the total length, and therefore It is better to attach the cylindrical body 11.

The shape of the cylinder 11 is not particularly limited as long as the annular chamber 11a formed by the outer cylinder 3 and the cylinder 11 has a sealed structure, but it may be similar to the outer cylinder 3 due to the materials normally used and ease of installation. It is a type of thing.

The material of the cylindrical body 11 must be air-impermeable, and it is usually preferable to use a plastic plate made of vinyl chloride resin, acrylic resin, or the like, or an iron plate.

6 Functions and Effects of the Invention As described above, the screw press type dehydrator of the present invention has a cylindrical body provided to surround the outer rear half of the outer cylinder of the cylindrical member to form an annular chamber, and furthermore, the screw press type dehydrator of the present invention has a cylindrical body that surrounds the outer rear half of the outer cylinder of the cylindrical member to form an annular chamber. A steam ejector is attached to the steam inlet, the steam ejector suction port and the annular chamber are connected with an exhaust pipe, and the annular chamber is arranged to be evacuated and depressurized by the vacuum pressure generated by the steam ejector, As a result, the sludge put into the sludge hopper is heated by the steam blown into the screw shaft from the screw shaft steam inlet, and the volume of the annular gap formed by the outer cylinder, screw shaft, and screw blades is increased. By reducing the size of the cylinder, squeezing pressure is applied, and at the same time vacuum pressure generated by the steam ejector is applied from the outer surface of the outer cylinder to drain the liquid from the outer cylinder, dewatering with a lower water content compared to conventional screw press type dehydrators is achieved. This method offers many benefits, such as being able to stably obtain a cake, having a simple device structure, manufacturing at low cost, and being easy to maintain and manage.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of the conventional example, FIG. 2 is a vertical sectional view of the embodiment of the present invention, and FIG. 3 is an enlarged view of the steam ejector portion of FIG. 2. 1...Sludge supply port, 2...Sludge hopper, 3...
... Outer cylinder, 4 ... Screw blade, 5 ... Screw shaft, 6 ... Cake discharge port, 7 ... Screw shaft drive shaft, 8 ... Screw shaft drive device, 9 ... Steam inlet, 10 ... Drain Discharge port, 11...
... Cylindrical body, 11a ... Annular chamber, 12 ... Steam ejector, 12a ... Suction port, 13 ... Exhaust pipe, 14 ... Rotary joint, 15 ...
liquid tank.

Claims (1)

[Scope of utility model registration request] A screw shaft having screw blades on the outer periphery and the inside of which can be heated with steam is rotatably provided in an outer cylinder of a cylindrical material having a sludge supply port and a cake discharge port, and the outer cylinder, screw shaft, and screw The volume of the annular gap formed by the blades is gradually reduced toward the cake discharge port,
In a screw press type dewatering machine that compresses and dehydrates sludge by rotating the screw shaft and discharges it from the cake discharge port, a cylinder is provided concentrically in the rear half of the outside of the outer cylinder to form an annular chamber; A steam ejector is attached to the steam inflow part to the screw shaft, a suction port of the steam ejector and the annular chamber are communicated through an exhaust pipe, and the steam ejector is configured to reduce the pressure in the annular chamber. Screw press type dehydrator.