JPS596911A - Method for controlling operation of press dehydrator - Google Patents

Abstract

PURPOSE:To automatically set an optimum press time corresponding to sludge properties, by utilizing such a fact that the pressure in a filter chamber or a sludge supply flowline and the cake water content in the filter chamber are in almost constant relation. CONSTITUTION:The sludge in a coagulative mixing tank 3 is supplied to a press dehydrator 17 for a predetermined time under predetermined pressure by a sludge injection pump 16 and, when the sludge injection pump 16 is stopped by the indication from a control apparatus 6 to close a sludge injection valve 18, a compression pump 19 is simultaneously started to open a compressed water stop valve 20 while compressed water is supplied to the press dehydrator 17 from a compressed water tank 21 to carry out the press dehydration of sludge. At this time, when the measured valve of a pressure gauge 22 arranged between the sludge injection valve 18 of the sudge supply flowline and the press dehydrator 17 is lowered to predetermined pressure, the control apparatus 6 stops the compression pump 19 by the signal from the pressure gauge 22 and the compressed water stop valve 20 is closed to finish the compression of the sludge.

Description

[Detailed description of the invention] The present invention relates to a method for controlling the operation of a pressure dehydrator.

As a dehydrator for dewatering sludge and the like, there is a pressure dehydrator configured to supply sludge to a filter cloth in a filter chamber and dewater the sludge by pressurizing the sludge. In such a pressure dehydrator, it is necessary for the dewatered sludge (hereinafter referred to as cake) to be naturally peeled off from the filter cloth at the end of the dewatering process, and for this reason conventionally, it takes time to squeeze the sludge. It was set much longer than the time. For example, as shown in Fig. 1, the required compression time is 110 minutes while the required L1 is 5 minutes. In the 1st IA, the solid line C1 indicates the accumulated sludge tank, and the broken line indicates the cake water content in the filter chamber. This is a pressing process in which the pressing force is 5kq/ad and the pressing pressure is 15#/aj. Therefore, the cycle time became long and the performance of the pressure dehydrator could not be fully utilized, which was extremely wasteful.

In addition, since the settings for the above-mentioned compression time, etc. were made appropriately based on the operator's experience, the compression time may become shorter than the optimal value due to a significant change in the properties of the soil. The cake naturally peels off from the filter cloth, and the operation of the processing dehydrator must be stopped and the undehydrated cake adhering to the filter cloth must be manually removed, which is very troublesome.

In view of the above points, the present invention aims to provide a method for controlling the operation of a pressurized dehydrator that can be operated efficiently with an optimum compression time depending on the sludge properties.

That is, the method for controlling the operation of a pressurized dehydrator according to the present invention is as follows:
A method for controlling the operation of a processing dehydrator configured to dewater the sludge by supplying sludge between filters r'11 and pressurizing the sludge in a greenhouse, the method comprising: It is characterized by detecting that the pressure in the sludge supply flow path that communicates with the greenhouse has decreased to a predetermined pressure, and thereby ending pressurization. Utilizing the fact that the moisture content of the inner cake has a substantially constant relationship, the moisture content of the cake inside the cocoon is estimated based on the pressure, and when the pressure falls to a predetermined value, the moisture content of the cake inside the greenhouse also falls to the desired value. Since the pressurization is thus terminated, the optimal compression time can be automatically set according to the sludge properties, and operation can be performed with extremely high efficiency and without insufficient dewatering.

An embodiment of the present invention will be described below based on the drawings. Second
In the figure, (1) is a sludge storage tank in a treatment facility for sewage, water, various industrial wastewater, etc., and this sludge storage tank (
The sludge in the tank is sent to the flocculation mixing tank (3) by the sludge transfer pump (2). This sludge transfer channel is equipped with an electromagnetic flow meter (4) and an age change needle (5), and the measured values of these electromagnetic flow meters (4) and temperature change needle (5) are converted into electrical signals. °C is input to the controller (6). (7) is a slaked lime silo, and the slaked lime in this slaked lime silo (7) is
It is supplied to the slaked lime dissolving tank 00 by a constant storm feeder (9) equipped with an I'iJi speed motor (8), and is stirred by an agitator @ together with the liquid supplied to the slaked lime dissolving tank oO via the travel control valve θυ. , dissolve in liquid. This solution is injected into the coagulation mixing tank (3) together with the salt iron sent from the salt iron storage tank C141 by the salt iron injection pump (2), and stirred by the stirrer (g). In this way, the sludge in the flocculation mixing tank (3) coagulates to produce a large number of frogs, which are lost to dewatering. The control device (6) is configured to control the tortoise current meter (4).
) and the concentration meter (5), the flocculation mixing tank (3
), the variable speed motor (8) and the salt iron injection pump are controlled to collect slaked lime and salt iron according to the amount of solid components in the sludge. Mixing tank (will be supplied in March).

The sludge in the flocculation mixing tank (3) is supplied to the pressurizing dehydrator αη at a predetermined pressure for a predetermined time by the sludge inlet pump α, and then the sludge inlet pump D is supplied to the pressurized dehydrator αη for a predetermined time by the sludge inlet pump α.

stops and at the same time the sludge injection chamber (to) closes, the press pump α Enoki starts and the press water stop valve ■ opens °C1
Pressed water is supplied from the press water tank (2) to the pressurized dehydrator ση, and pressurized dewatering of the sludge is performed. At this time, if the measured value of pressure 1 (a) installed between the sludge supply valve (g) and the pressurized dewatering machine aη falls to a constant pressure of )9■, the pressure gauge indicates) In response to a signal from the control device, the press pump CAI is stopped and the press water stop valve is closed, and the pressurization of the sludge is completed.

That is, as shown in detail in FIG. 8, the pressurized dehydrator αη has a large number of movable members (2) equipped with a diaphragm and constituting a continuous room (2), and each greenhouse (C) has a filter. cloth(
b) is passing through twice. Sludge is shown in Figure 8 (5)
The double filter cloth shown in the figure! − is supplied to

For example, as shown in FIG. 4, the driving process is completed when driving is performed for 5 minutes at a driving pressure of 5 #/cd. The inside of the hidden "C" chamber is filled with sludge as shown in Figure 8 (03). At this point, approximately 1.5rn' of filtrate flows out through the drain pipe (not shown) due to the charging pressure.
There is C. [At the same time as the completion of the filling process, compressed water from the compressed water tank 2v is supplied to the rear side of the diaphragm (E), and the die and aphram solenoid are pressed forward as shown in Figure 8 (C), and the filter cloth is closed. (e) The sludge in between is dehydrated under pressure. At this time,
The pressure of sludge in the sludge supply channel is measured by a pressure gauge (2), and when this pressure falls to a predetermined value, the control device (
6) automatically ends the squeezing process. The squeezing pressure at this time is, for example, 15 to 9/dl as shown in Figure 4.
1, about 1.5 d of M liquid was extracted by the 5-minute squeezing process, and the moisture content of the cake in the greenhouse was within the range of about 50 to 60%. After the completion of the L. comb and compression process, No. 81J (D)
(7) Dark Cake
C) naturally peels off from the filter cloth (E) and falls. This completes one cycle of operation of the pressure dehydrator avrl, and the same cycle is repeated thereafter. Furthermore, the fourth
In the figure, the solid line °c1 indicates the accumulated filtrate, and the broken line indicates the moisture content of the cake in the greenhouse.

In addition, the measurement using the pressure gauge (2) may be performed every cycle, but if the properties of the sludge are relatively unlikely to change suddenly, the squeezing time at the time of measurement may be measured by the control device (6). The pressure gauge (2) is memorized for one to several hours or once every 10, and each time the control device (6) is
) to refresh the compression time stored in °C.

In this way, since the optimal compression time is automatically set to H'NJ based on the measured value of the pressure gauge (2), wasteful compression time can be omitted and there is no possibility of incomplete dehydration. Therefore, the time required for dewatering can be shortened, the performance of the pressure dehydrator αη can be fully utilized, and the natural peeling of the cake (b) after dehydration can be reliably realized, reducing the trouble in processing the cake@. There's nothing necessary. In addition, the value indicated by the pressure gauge (2) is 1.0 to 1.5 kg from the squeezing pressure of 15 kg/I.
When the temperature drops to about 5ky/-, the moisture content of the cake in the greenhouse drops to a range of 50 to 6096, and it has been confirmed through experiments that natural peeling of the °C cake@ is reliably performed when the wall plate is placed. It was done.

In addition, in the above embodiment, the pressure of the supplied sludge was explained in the sludge supply channel shown in Figure 1, or the greenhouse (
(c) may be established within.

As explained above, according to the method for controlling the operation of a pressurized dewatering machine according to the present invention, sludge can be pressurized with the optimum pressing time depending on the sludge properties, so there is no waste during pressing. The performance of the pressure dehydrator can be fully utilized, the operating efficiency can be greatly improved, and the natural peeling of the cake during drying can be reliably achieved without causing insufficient dehydration.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the water content of accumulated recirculation liquid and cake in the greenhouse in the conventional operation method, Fig. 2 is a control system diagram showing an embodiment of the present invention, and Figs. 8 (A) to (D) ) is an explanatory diagram of the filtration operation of the pressurized dehydrator in one embodiment of the present invention, and the fourth factor is an explanatory diagram of the accumulated filtrate storm and the moisture content of the cake in the greenhouse in one embodiment of the present invention. Oη...pressure dehydrator, ni)-...pressure gauge, (c)...
- Storeroom, (e)...filter cloth. Agent Yoshihiro Morimoto (A) 2A (C) 6 Figure 3 (6), 6 (S)

Claims (1)

[Claims] 1. A method for controlling the operation of a pressurized dehydrator configured to dewater the sludge by supplying sludge to a filter cloth in a filter chamber and pressurizing the sludge, the method comprising: A method for controlling the operation of a pressurized dewatering machine, comprising detecting that the pressure in a sludge supply channel communicating with the sludge supply channel has decreased to a predetermined pressure, and thereby terminating pressurization.