JPS5929282B2 - Automatic operation method of dehydrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic operation system for a dehydrator that dewaters sludge.

The amount of waste has increased rapidly in recent years, and the development of effective treatment methods has become a socially important issue.
Sludge from industrial wastewater treatment plants such as sewage treatment plants and plating factories is also subject to this system.

These sludges are colloidal suspensions with a water content of 90% or more, and their treatment requires dehydration to reduce the amount of sludge so as not to cause secondary pollution.

Conventionally, sludge dewatering work has been carried out as follows.

First, by manually analyzing the water content of the sludge, an appropriate filtration time is estimated, and a timer attached to the dehydrator is set to perform the dewatering process.

Then, the moisture content of the dehydrated sludge cake taken out from the dehydrator is checked, and if it is found to be an insufficient value, the timer is reset and the dewatering operation is continued.

The dehydrator was operated through repeated trial and error in order to achieve the optimal filtration time.

Therefore, if the properties of the sludge were constant, the experience gained through repeated trial and error would be useful, but if the properties of the sludge were different, trial and error would have to be repeated over and over again, which was extremely tedious.

In addition, the filtration time is determined depending on whether the amount of chemicals injected as a pre-treatment for dehydration is appropriate, making it difficult to manage the dehydration work.

The present invention has been made in view of the above points, and aims to provide an automatic operation system that enables optimal operation of a dehydrator through computer control.

An embodiment of the invention will be described with reference to the drawings.

In the figure, 1 is a sludge supply pipe, 2 is a sludge dehydrator, 3 is a filtrate discharge pipe, 4 is a sludge flow rate detection end, 5 is a sludge flow rate transmitter, 6 is a sludge concentration detection end, 7 is a sludge concentration transmitter, and 8 1 shows a filtrate flow rate detection end, 9 a transmitter or counter, 10 a calculation device, 11 a dehydrator operation control circuit, and 12 a sludge supply pump.

Next, the operation will be explained.

During operation of the dehydrator 2, sludge is transferred from the sludge supply pipe 1 to the dehydrator 2.
When a predetermined amount of sludge is supplied to the tank, a dewatering operation is performed for a predetermined period of time, and then the remaining sludge cake is discharged after dewatering, and the cycle is repeated.

The lachrymal fluid produced during the dehydration process is drained through the drain tube 3.

The dehydrator may be of any suitable type, such as a pressure filtration type or a rotary separation type.

In this method, the sludge flow rate signal obtained from the sludge flow rate detection end 4 via the sludge flow rate transmitter 5 and the sludge concentration detection end 6
a sludge concentration signal obtained from the sludge concentration transmitter 7;
The necessary calculations are performed in the calculation device 10 using the lachrymal fluid drainage amount signal obtained from the P liquid flow rate detection terminal 8 via the transmitter (or counter) 9, and the time required to realize the optimal operation of the dehydrator 2 is determined. A schedule is created, and this time schedule is used to operate the dehydrator 2 via the operation control circuit 11.

An example of the optimal control calculation procedure (cycle time control) performed by the calculation device 10 will be explained with reference to the flowchart of FIG. 2.

In general, if the total amount of lachrymal fluid from the start of dehydration to after a time θ in a dehydrator is represented by ■, then the following equation, known as Ruth's equation, holds true.

θ/V-(V/K)+2Vo/K (1) where K: constant pressure filtration coefficient X filtration area 2 or Vo is given by the following formula.

(2) o-A-Rm/(αC) (2) However, A: filtration area, Rm: resistance of P cloth, α: specific resistance of sludge cake, C: specific gravity of sludge.

First, as shown in the flowchart, K and Vo are determined using the measured values of θ and ■ at two or more points during the dehydration operation process.
The value of is determined from equation (1).

Next, the value of β is artificially set with the goal of keeping the water content β of the sludge cake constant.

Once the value of β is determined, the expected total amount of tear fluid Vs and standard filtration time θ8 are determined using the following equations (3) and (4).

V s' −Q (σ.

-Cs/(1-β))/σ (3)θs -('V2S
+ 2 VoVs ) / K (4) However, Q: Sludge amount C8: Sludge SS concentration σ.

: Sludge density σ: P liquid density Here, Q is measured at the sludge flow rate detection end 4, and Cs is measured at the sludge concentration detection end 6.

σ. and σ are fixed physical property values.

Therefore, the dehydrator is operated according to the standard filtration time θS, and the value of ■ at that time is measured at the F liquid amount detection terminal 9.

As a result, if it is V - Vs, there is no need to change the dehydration time θ, but if it is V\Vs.

The value of K is changed using the following equation (5) from the values of θS and ■.

If the value of K after change is ′, then ′=(■2+2■■o
)/θ5 (5) Next, using this value, change the filtration time using the following equation (6).
This is done by

If the p delay time after change is θ', then θ' = (V% + 2VoVs)/' (6
) The same procedure is then repeated to reach optimal control.

As explained above, when using the automatic operation method according to the present invention, it goes without saying that there is no need to manually analyze the water content of sludge cake as was done in the past. Since it is an optimization control, it is possible to automatically change the time schedule of the dehydrator operation, and even if the ratio of chemical injection performed as pre-treatment for dehydration changes. Since it is possible to find the optimum drainage time corresponding to

The operating method according to the present invention can be effectively applied to control dehydrators in relatively large-scale treatment facilities for treating sludge from sewage treatment plants, sludge from water treatment plants, and sludge from industrial wastewater. be.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a flowchart showing an example of the optimal control calculation procedure (cycle time control) performed within the computing device in the automatic driving system of the present invention. . In the figure, 1 is a sludge supply pipe, 2 is a sludge dehydrator, 3 is a filtrate discharge pipe, 4 is a sludge flow rate detection end, 5 is a sludge flow rate transmitter, 6 is a sludge concentration detection end, T is a sludge concentration transmitter, and 8 1 is a filtrate flow rate detection terminal, 9 is a transmitter or counter, 10 is a calculation device, and 11 is an operation control circuit.

Claims (1)

[Claims] 1. A dehydrator, an operation control circuit that controls the operation of the dehydrator, and means for detecting the concentration and amount of sludge supplied to the dehydrator and the amount of P liquid discharged from the dehydrator,
By inputting the sludge concentration, sludge amount, P liquid amount detected by this detection means, and the water content of the sludge cake set from the outside, the standard filtration time of the dehydrator and the expected P liquid amount based on this standard drying time are calculated. and a calculation device that calculates and provides an operation time schedule to the operation control circuit, and compares the expected filtrate amount given from the calculation device and the actual F liquid amount detected by the detection means in each operation process. . If there is a deviation, the standard filtration time is corrected by the calculation device and the operation is continued to find the optimum filtration time.