JP3342519B2 - Screen dewatering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pressurized dewatering means mainly provided with a plunger reciprocating in a cylindrical screen at the lower end of a dewatering screen residue transfer duct having a required diameter and a required head. The present invention relates to a method for dewatering a screen residue by pressing and dewatering the screen residue in combination with swinging of a back pressure plate which is swingably provided in a transfer duct.

[0002]

2. Description of the Related Art Conventionally, the screen residue collected from a sewage treatment plant or the like has a high moisture content, and it is troublesome to put it into a hopper or into an incinerator in a collected state after the treatment. . For this reason, it is necessary to dehydrate the collected screen residue until the water content falls below a predetermined value. Conventionally, the screen residue is dewatered by a dehydrator, and the dewatered screen residue is conveyed to a hopper or an incinerator by an unloader. Japanese Patent Publication No. 46-26285 discloses a method in which screen residue is supplied into a sealed duct, dehydrated under pressure, and then fed under pressure.

[0003]

A method of dewatering a screen residue by a dehydrator and then transporting the screen residue to a predetermined position in a transport duct is excellent. However, since the dewatering of the dewatered screen residue is performed in a state in which the operation time of the plunger and the high / low speed switching point are set in advance regardless of the amount and properties of the screen residue, the amount of screen residue is small. , Driving efficiency is poor.

According to the present invention, there is provided a method for dewatering screen residue by automatically switching the amount of hydraulic oil supplied to a hydraulic cylinder of a plunger and adjusting the dewatering time in accordance with the amount of screen residue to improve dewatering efficiency. The purpose is to provide.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and comprises a plunger reciprocating in a cylindrical screen at a lower end of a dewatering screen residue transport duct having a required diameter and a required head. A method for dewatering a screen residue, comprising a main pressurizing and dewatering means, wherein the screen residue is pressed and dewatered by a combination of forward movement of a plunger and swinging of a back pressure plate slidably provided in a transfer duct. When the pressure of the hydraulic oil to the hydraulic cylinder is low, the discharge amount of the hydraulic pump is increased and the plunger is moved at high speed, and when the pressure is high , the discharge amount of the hydraulic pump is decreased and the plunger is moved at low speed. The screen residue is dehydrated.

[0006]

[Action] dehydration process of the screen residue, when the pressure of the working oil to the plunger of the hydraulic cylinder is low, the discharge amount of the hydraulic pump moves the plunger as a large high speed, when the pressure of the high pressure, the hydraulic pump By dehydrating the screen residue by moving the plunger at a low speed with a small discharge amount, even if the amount of the screen residue to be charged changes
The switching between the high and low speeds of the plunger can be automatically performed by detecting that the screen residue has moved from the movement of the screen residue to the pressurized state, so that the reciprocating time of the plunger is not wasted and the dewatering efficiency is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. The screen residue collected from a sewage treatment plant, a pumping station, or the like is continuously or intermittently conveyed. Hopper 2 is provided. The hopper 2 is protruded from an upper part of a dewatering device 3. The dewatering device 3 includes a cylindrical screen 31 and a pressurized dewatering means 32 mainly including a plunger housed in the screen 31. The dehydrating means 32 uses a hydraulic cylinder 32a, and the plunger 32b
The hopper 2 is disposed above the front end position of the plunger 32b. The outlet at the lower part of the hopper 2 is slightly shorter than the stroke of the plunger 32b, and the transfer duct 5 is provided at the tip of the pressurized dewatering unit at a position slightly forward of the position where the plunger 32b protrudes. The desorbed water generated from the time when the water contained in the screen residue is supplied from the inside of the hopper into the screen 31 after the dehydration under pressure is drained out of the screen 31.

The pressurizing and dewatering section squeezes the screen residue by advancing a plunger 32b driven by a hydraulic cylinder 32a of the pressurizing and dehydrating means 32, and increases the pressing force to a value required for dewatering. The pressurizing and dewatering unit includes a back pressure plate 6 oscillated by a pressurizing cylinder 6S at a bent portion at the lower end of the transfer duct 5, and a cylindrical drainage screen 31.

The back pressure plate 6 is, as shown in FIG.
Is supported on the side wall of the transfer duct 5 so as to be swingable via a shaft S, and the back pressure plate 6 is fitted into a window hole formed in the transfer duct 5 so as to close the hole, and When the back pressure plate 6 is located at the hole position, the back pressure plate 6 has the same shape as the outer wall of the transfer duct 5, whereby the back pressure plate 6 is swung by the hydraulic cylinder 6S to the dashed line position in FIG. Pressurization is performed to dehydrate inside the screen 31 and inside the base end of the duct.

A hydraulic circuit 7 shown in FIG. 2 is disposed in the hydraulic cylinder 32a of the plunger, and hydraulic oil is supplied from the hydraulic pump 8 to the hydraulic cylinder 32a. The hydraulic pump 8 is of a variable speed type, and the discharge amount of the hydraulic pump is changed when it reaches a certain pressure. That is, when the plunger 32b is moved in the direction of the conveying duct by operating the hydraulic cylinder 32a in the step of squeezing the screen residue put into the cylindrical screen 31, when a predetermined pressure (pressing force) is reached, the hydraulic pump is operated. The discharge amount is reduced to a set value. This is set so that the pressure during dehydration under pressure is slightly higher than the movement resistance value of the screen residue. FIG. 3 shows the relationship between the discharge amount and the pressure of the hydraulic pump, that is, the supply amount of the hydraulic oil from the hydraulic pump to the hydraulic cylinder 32a and the pressure.

In FIG. 3, P1 is the pressure required for moving the screen residue in the screen 31, P2 is the maximum pressure during pressurized dehydration, Q1 is the minimum discharge amount of the hydraulic pump, and Q2 is the time when the screen residue is moved (not applied). (When pressure is applied).

Therefore, at the initial stage of the movement of the plunger 32b in the screen 31, the discharge amount of the pump becomes large, so that the plunger 32b moves at high speed and moves the screen residue. Then, when the pressure reaches the set pressure P1, the pump discharge amount becomes Q1 and the movement of the plunger becomes slow, but the pressure increases and reaches the maximum pressure P2. During the period from the pressure P1 to the pressure P2, the screen residue is dehydrated under high pressure by the low-speed movement of the plunger.

[0013]

According to dehydration process of the screen residue of the present invention, when the pressure of the working oil to the plunger of the hydraulic cylinder is low, the discharge amount of the hydraulic pump to move the plunger at high speed as a large, pressure high At this time, since the discharge amount of the hydraulic pump is reduced and the plunger is moved at a low speed to dehydrate the screen residue, even if the amount of the screen residue to be supplied is increased or decreased, the high / low switching of the plunger is performed. Detecting that the screen residue moves to the pressurized state from the movement of the screen residue can be performed automatically. Thereby, even if the amount of the screen residue to be introduced changes, the efficient dehydration can be performed while sufficiently securing the time for the pressure dehydration.

[Brief description of the drawings]

FIG. 1 is a front vertical sectional view showing an example of a dehydrator for performing a method for dewatering screen residue according to the present invention.

FIG. 2 is an explanatory diagram of a hydraulic circuit.

FIG. 3 is a graph showing a relationship between a discharge amount of a hydraulic pump and a pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dehydrator 2 Hopper 3 Dehydration device 31 Cylindrical screen 32a Hydraulic cylinder 32b Plunger 4 Pressure dehydration part 5 Transport duct

Continuation of the front page (72) Inventor Masayuki Ueno 3-3-11-1 Shimosakabe, Amagasaki-shi, Hyogo Nippon Machinery Co., Ltd. (56) References JP-A-4-294899 (JP, A) JP-A-2 −214600 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B30B 9/04 B30B 9/06 B65G 53/30 C02F 11/12

Claims (1)

(57) [Claims] 1. A pressurized dewatering means mainly comprising a plunger reciprocating in a cylindrical screen is provided at the lower end of a dewatering screen residue conveying duct having a required diameter and a required head, and the plunger is advanced and the conveying duct is swung. In the method of dewatering screen residue by pressing the screen residue in combination with the swinging of the back pressure plate movably provided, the discharge amount of the hydraulic pump when the pressure of the hydraulic oil to the hydraulic cylinder of the plunger is low the move the plunger as a large high-speed, high pressure
A method for dewatering a screen residue, wherein the discharge amount of a hydraulic pump is reduced, and the plunger is moved at a low speed to dehydrate the screen residue.