JPS59206199A - Method and device for controlling sludge dehydrator - Google Patents

Abstract

PURPOSE:To dehydrate sludge with less operating labor and good efficiency by measuring the air permeability of an endless traveling filter cloth either after stripping cake therefrom or after washing the filter cloth and controlling a chemical feed rate, washing water amt., etc. according to the measured value thereof. CONSTITUTION:Sludge 11 generated in a sewage treatment plane, etc. is added with chemicals such as a flocculating agent, etc. in a thickening stage, etc. and thereafter the sludge is introduced to a thickening part A of a roll press dehydrator provided with an endless traveling filter cloth 5. The sludge 11 dewatered by a gravity effect in said part is compressed and dehydrated between the filter cloth 5 and other filter cloth 6 in a compression dehydrating part B. The sludge is then stripped as cake by a scraper 7 from the filter cloth in a cake stripping part C. The cloth 5 is thereafter washed in a filter cloth washer 8 and is returned again to the part A. The air permeability of the cloth 5 after the washing is measured with a detector 1. At least one among the amt. of washing water, chemical feed rate, the rate of the sludge to be supplied, the traveling speed of the filter cloth, the tension on the filter cloth, the agitating speed in the stage for flocculating the sludge, etc. is controlled in accordance with the difference in the air permeability between the measured value and the air permeability of the cloth 5 in the unused state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a compression type dehydrator such as an endless cloth running type roll press or a filter press.

In general, when sludge generated from sewage treatment plants, human waste treatment plants, etc. is treated with a dewatering machine such as a roll press or filter press, a polymer flocculant or chemicals such as slaked lime are added to the sludge as a pretreatment operation to achieve appropriate flocculation. Stirring is applied at a stirring speed to form agglomerated flocs that are easy to dehydrate, and then, for example, a dehydrator such as the one shown in FIG.

By the way, in order to keep such a dehydrator in good operating condition, it is necessary to constantly observe the condition of the P cloth after peeling the cake and the condition of the sawn cloth after washing, and to adjust the amount of chemicals injected and the amount of washing water. It is essential to adjust the amount of water. If this is not done, for example, the moisture content of the cake will increase and the throughput will decrease due to insufficient amount of chemicals or washing water, or conversely, the amount of dehydration may increase due to excessive amount of chemicals, and cleaning This will lead to an increase in the burden on water treatment due to the excessive amount of water.

However, in the past, there was no appropriate method for quantitatively measuring the peeling state of the cake or the cleaning state of the P cloth, so the amount of chemical injection and washing water was determined empirically by visually observing the P cloth. There were problems such as the moisture content of the cake and the amount processed were not constant, and it required a lot of manpower to manage the dehydrator.

Recently, attempts have been made to use a photoelectric device to detect the light reflected from the cloth and control the amount of chemical injection and washing water depending on the magnitude of this reflected light. There were problems with maintenance, such as the need for adjustment each time because the reflectance differs depending on the properties of the sensor, and the need to remove contamination from the detection section.

The present invention aims to solve the problems of the conventional methods and devices described above, and to provide a dehydrator operation control method and device for reducing operating labor and performing efficient sludge dewatering treatment. By measuring the air permeability of the reeds and sawn cloth, the state of the r cloth (clogged state and cleaning state) after cake removal or r cloth washing can be quantitatively and accurately detected, and this detection signal can be used to inject chemicals. It is configured to control the amount of washing water and the amount of washing water.

That is, in the present invention, in a sludge dewatering machine equipped with an R cloth that can run endlessly, the air permeability of the R cloth is measured at least either after the cake is peeled off or after the P cloth is washed, and based on the measured value, chemicals for the sludge are determined. injection amount, sludge supply amount, P cloth running speed, F cloth tension pressure, stirring speed in the sludge coagulation process,
Washing of P Cloth 4- A method and apparatus for controlling a sludge dehydrator, characterized in that at least one of the amounts of water is controlled.

In the present invention, the amount of washing water can be controlled only by measuring the air permeability of the r-cloth after washing, and other controls can be performed by measuring any of the above.

In addition, although it is preferable that these controls be performed automatically,
It may also be done manually.

An embodiment of the apparatus of the present invention will be described below with reference to FIG. 1, taking a roll press as an example.

Sludge 11 generated from sewage treatment plants and human waste treatment plants is concentrated by an appropriate concentration operation and then flows into a chemical mixing tank (not shown), where it is mixed with chemicals such as polymer flocculants (hereinafter referred to as polymers). is added, and then flows into the concentration section A of the roll press dehydrator. In the thickening section A, water is drained by the action of gravity, and the sludge loses its fluidity, is sandwiched between the lower R cloth 5 and the upper R cloth B, and is introduced into the compression dewatering section B. In the press dewatering section B, the sludge is forcibly compressed by press rolls, and the water content in the sludge is reduced. The sludge that has come out of the press-dewatering section B is naturally or forcibly stripped from the surface of the cake stripping section C by a scraper 7, falls onto a cake conveyor (not shown), and is carried out of the system. The r-cloth from which the cake has been removed is washed by the r-cloth washing device 8 provided in the wash cloth washing section, and then returned to the concentrating section A.

On the other hand, the water separated from the sludge flows through the drainage troughs 9 and 10.
The water is returned to the water treatment process or concentration tank along with the Sawafu cleaning wastewater.

By the way, a detector 1 (hereinafter simply referred to as a detector) for measuring the air permeability of the r cloth is installed between the r cloth cleaning device 8 and the concentrating section A, and detects the air permeability of the r cloth by an electrical signal. Alternatively, it is output to the control unit 2 as an air signal. The control unit 2 is equipped with a control/arithmetic device and a power supply, and has the air permeability (r) when the cloth is unused (r) set or stored in advance, and the input signal (r) from the detector 1 (r) ) and the difference (ΔQ
) is calculated. If ΔQ exceeds a preset larger reference value ΔQmaz, a dirt detection signal is output to the outside. In response to this dirt detection signal, the amount of washing water is increased via the washing water amount control mechanism. On the other hand, if ΔQ becomes less than the preset smaller reference value ΔQmLn, the amount of washing water is reduced.

In the figure, 3 is a control valve, and 4 is a feed box.

In the above embodiment, the amount of washing water was increased or decreased based on the detection signal, but depending on the processing situation (for example, when the solid concentration of the sludge to be dewatered varies greatly), the detector may be placed between the cake peeling section and the cloth washing section. The amount of polymer injection may be increased or decreased based on this detection signal, or the amount of washing water and the amount of polymer injection may be increased or decreased by installing detectors on both sides.

Furthermore, in the case of a filter press (not shown), the dehydrator can be controlled with a device that is exactly the same as in the above embodiment, except that the chemicals used are slightly different from those in the roll press embodiment.

FIG. 2 shows an embodiment of the detector, in which the detection end 12 has a trumpet-shaped or cylindrical suction port opened, and is pressed together with the r cloth 5 while being crimped to the f cloth 5 by the running fist attachment/detachment device 16. =
After traveling a certain distance, it returns to its original position while leaving R cloth 5, and repeats the operation of pressing F cloth 5 again and traveling. The detection end 12 is connected to a suction pump 14 through a telescoping conduit 13, and the air flow rate within this conduit 16 is measured to determine the air permeability. The air permeability may be determined by measuring the pressure.

Next, examples of the method of the present invention will be described.

Example 1 Sludge generated from a sewage treatment plant was subjected to a dehydration test under the following conditions using a roll press dehydrator as shown in FIG.

Based on the above results, it was determined that the R cloth was clogged due to insufficient chemical injection amount and washing water amount, and the chemical injection rate was reduced to 1.
．． 0% vs. SS (approximately 20 inch increase) and the amount of washing water is approximately 20%
When the amount was increased, the results shown below were obtained, and the cake moisture content decreased significantly.

Example 2 Sludge generated from a sewage treatment plant was subjected to a dehydration test under the following conditions using a roll press type dehydrator as shown in FIG.

It was determined that there was, and the drug injection rate was reduced to 0.7% vs. SS (approximately 30% reduction)
When the amount of washing water was reduced by about 20 inches, the results shown below were obtained, and the amount of chemicals and washing water was reduced.

As is clear from the above examples, the present invention measures the air permeability of the cloth during the operation of the dehydrator, compares it with a preset reference value, detects the soiled state of the cloth, and based on the detection result. According to the present invention, it is possible to perform stable sludge treatment, and the amount of washing water and the amount of polymer injection can be set. Many benefits can be obtained, including a reduction in water content, a reduction in sludge disposal costs due to a reduction in cake moisture content, and a reduction in the number of personnel monitoring the dehydrator.

[Brief explanation of the drawing]

Figure 1 is a flow sheet showing an embodiment of the device of the present invention;
The figure is a flow sheet of the detector. A... Concentration section, B... Pressure dehydration section, C... Cake peeling section, D... P cloth cleaning section, 1... Detector, 2...
・Control unit, 11- 3rd...control valve, 4...feed box, 5, 6-
...r cloth, 7...scraper, 8...P cloth cleaning device, 9.10...drainage trough, 11...sludge, 12
... detection end, 13 ... conduit, 14 ... suction pump, 15 ... pressure detector, 16 ... travel/attachment device. Patent applicant: Ebara Infilco Corporation, patent attorney 11) Twisting: Takao Maruyama =
12-1 Figure 1 F:1

Claims (1)

[Claims] 1. In a sludge dehydrator equipped with a P cloth that can run endlessly, the air permeability of the R cloth is measured at least either after cake peeling or after washing the P cloth, and the measured value is Amount of chemicals injected into the sludge, sludge supply amount, P cloth running speed,
A method for controlling a sludge dehydrator, comprising controlling at least one of F cloth tension pressure, stirring speed in a sludge coagulation step, and amount of washing water to F cloth. 2. A concentrating section in which an endless r-cloth is installed in a movable manner and performs natural dewatering by the action of gravity, followed by a compression dehydration section in which the sludge is sandwiched and compressed by the r-cloth, and a cake peeling section is provided in the subsequent stage. In a control device for controlling the operation of the dehydrator, the control device is installed in a sludge dehydrator having a P cloth washing section and a P cloth washing section at a subsequent stage, and the f cloth washing section is disposed between the cake peeling section and the r cloth washing section. a measuring mechanism disposed between at least one of the washing section and the thickening section to measure the air permeability of the r cloth, and determining the amount of chemicals to be injected into the sludge and the sludge supply based on the air permeability measured by the measuring mechanism. amount, P cloth running speed. f Cloth tension pressure, stirring speed in the sludge flocculation process. 1. A control device for a sludge dewatering machine, comprising: a control mechanism for controlling at least one of the amounts of washing water to the cloth. 3. The measuring mechanism is disposed between the cake peeling section and the r cloth cleaning section, and the control mechanism is configured to measure the air permeability measured when the f cloth is unused and when the f cloth is in use. 3. The control device according to claim 2, wherein the control device is configured to set the chemical injection amount based on the calculated values of calculations 1 to 1, which are the differences between the measured air permeability and the measured air permeability. 4. The measuring mechanism is disposed between the washing cloth cleaning section and the concentrating section, and the control mechanism is configured to control the air permeability measured when the r cloth is unused and the air permeability measured while the r cloth is in use. 3. The control device according to claim 2, wherein the control device is configured to calculate a difference between air permeability and set the amount of washing water based on the calculated value. 5. The measurement mechanism is a suction nozzle or a suction pump. The suction nozzle includes a telescopic conduit that connects these two and a measuring section that measures the pressure inside the conduit.
It is configured so that it can repeat the operation of coming into close contact with the r cloth at a predetermined position, traveling with the r cloth for a predetermined distance while remaining in close contact, and then separating from the f cloth and returning to the predetermined position. Certain claims 2, 3, or 4
Control device as described in section.