JPS58119399A - Installation for dehydrating sludge - Google Patents

Abstract

PURPOSE:To adjust the water content of a dehydrated cake to a predetermined value accurately and automatically, by keeping the water content of the dehydrated cake within a range of a predetermined objective value or in the vicinity thereof by predetermined control procedure. CONSTITUTION:A mixing apparatus 10, a sludge supply apparatus 20, a coagulant supply apparatus 30, a dehydrating apparatus 40, a sludge concn. measuring apparatus 50, a moisture measuring apparatus 60 and a control apparatus 70 are provided. This apparatus 70 takes in the moisture signal of a sludge dehydrated cake from the apparatus to compare the same to an objective moisture value and, when the comparison result exceeds a tolerant moisture range, each controls, wherein the mixing ratio of a coagulant to the solid component of sludge obtained based on the flow amount of the sludge or the sludge concn. signal from the apparatus 50, the dehydrating speed of the apparatus 40 and the flow amount of the sludge supplied to the apparatus 40 are respectively adjusted, are carried out according to predetermined preferencial order to keep the aforesaid comparison result within the tolerant range while, when the aforesaid comparison result exceeds the tolerant value even if above described controls are practiced, the comparison result is set to a control state when the moisture content of the cake is nearest to the objective moisture amount during practice.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to sludge dewatering equipment, and particularly to sludge dewatering equipment suitable for setting the water content of a sludge dewatering cake formed by dewatering sludge to a target moisture value.

In a conventional sludge dewatering device of this kind, taking a Pertin 1F type dehydrator as an example, first the water content of the sludge dewatered cake (hereinafter referred to as "dehydrated cake") is manually measured at predetermined intervals using the dry weight method, and then the water content is measured manually. Based on the results, the dewatering speed is adjusted by adjusting the flow rate of sludge supplied to the dehydrator and the mixing ratio of the flocculant, and by varying the belt speed of the dehydrator. However, in general, the water content of the dewatered cake discharged from the dehydrator, the flow rate of sludge supplied to the dewaterer, the mixing ratio of the flocculant, and the dewatering speed of the dewaterer (herein referred to as the belt speed of the dewaterer).

(The same applies hereafter) Although there is a correlation that the moisture content of the dehydrated cake decreases as the mixing ratio of the flocculant increases and the belt speed of the dewatering machine decreases, the relationship is not necessarily constant. However, depending on the state of the sludge, there were cases in which the water content of the dewatered cake did not decrease even if the mixing ratio of the flocculant was increased. For this reason, it may be necessary to change the operating conditions of the dehydrator each time the dehydrator is operated, based on the operator's previous experience. If the moisture content of the cake is unstable, or if the amount of coagulant used is increased more than necessary, or even if the dehydrator belt speed is slowed down to minimize the moisture content of the dehydrated cake from the dehydrator. There were drawbacks such as excessive sludge treatment and a drastic decrease in the amount of sludge treated.

SUMMARY OF THE INVENTION An object of the present invention has been made to overcome the drawbacks of the prior art, and is to accurately and automatically adjust the moisture content of a dehydrated cake to a predetermined value, and to obtain a dehydrated cake with a stable moisture content. To provide sludge dewatering equipment.

In order to achieve the above objects, the present invention provides a mixing device for mixing sludge and a flocculant for flocculating the same, and a predetermined mixing ratio for the solid content of sludge that can supply a predetermined flow rate of sludge to the mixing device. A flocculant supply device capable of supplying a coagulant so that the amount of water is absorbed, a dewatering device capable of adjusting the speed of dehydration that dehydrates the mixture from the mixing device to form a dehydrated cake, and detecting the sludge concentration supplied to the mixing device. The moisture signal from the sludge concentration measuring device and the dewatering device is incorporated, and this moisture 1g is compared with the target moisture value. If the comparison result exceeds the allowable moisture range, the sludge flow rate 11 is changed to sludge concentration measurement. Based on the sludge concentration signal from the device, each control is predetermined to control the mixing ratio of the flocculant to the solid content of the sludge, the dewatering speed of the dewatering device, and the flow rate of the sludge supplied to the dewatering device. If the comparison result exceeds the allowable range even after the above execution, the control state is changed to the one closest to the target moisture value at the time of the execution. This configuration includes a control device for setting.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing an embodiment of sludge dewatering equipment according to the present invention. The embodiment shown in FIG. 1 is equipped with a mixing device 10 that evenly mixes sludge and a flocculant to flocculate the sludge and flocculates the sludge, and a sludge supply device 20 that can supply sludge to the mixing device 10. A flocculant that can supply flocculant to the mixing device 10, which is composed of a receiving tank 21, a sludge pump 22 that transports sludge from the receiving tank 21, and a sludge pump controller 23 that controls the speed of the cough sludge pump 2'2. The supply device 30 is installed at a high place (two locations) to obtain a predetermined head pressure, and a flocculant storage tank 31 that stores the flocculant diluted to a predetermined concentration and a flow rate of the flocculant from the flocculant storage tank 31. A flocculant flow '111g4 which is adjusted according to the opening and closing time of the valve, and a flocculant which controls the opening and closing of the flow rate adjustment valve 32 so as to have a predetermined mixing ratio with respect to the sludge flow rate or the solid content of the sludge. and a flow rate controller 33, and dewatering equipment 4 that dehydrates the mixture supplied from the mixing device 10 to form a dehydrated cake.
0, a belt press type sludge which has an upper belt 41 and a lower belt 42, a belt drive motor 43 for driving the belts 41 and 42, and can adjust the dewatering speed by varying the speed of the belts 41 and 42. It is composed of a dehydrator 44 and a belt speed controller 45 that controls the belt drive motor 43 to a commanded speed, and detects the concentration of sludge supplied to the mixing device 10 from the sludge dewatering device j20. A sludge concentration measuring device 50 is provided, as well as a moisture measuring device 60 for detecting the amount of water contained in the dehydrated cake completely supplied from the dehydrating device 40, a moisture signal is taken in from the moisture measuring device 60, and this moisture signal is set in advance. If the comparison result exceeds the allowable moisture range (for example, within ±2 inches of the target m value), the sludge flow rate or the sludge am degree signal from the sludge concentration measuring device 150 is compared. Each control adjusts the mixing ratio of the flocculant to the solid content of the sludge obtained by the process, the dewatering speed of the dewatering device 40 (that is, the belt speed of the dewatering device 44), and the flow rate of the sludge supplied to the nuclear dewatering device 4°. are executed according to a predetermined priority order so that the comparison result falls within the allowable range, and if the comparison result exceeds the allowable range even after the above execution, the method is executed when the comparison result is closest to the target moisture value at the time of the execution. This configuration includes a control device 7o that instructs each controller 23, 33, and 45 to set the control state INK.

FIG. 2 is a block diagram showing the configuration of the control device 70 in detail. As shown in FIG. 2, the control device 70 includes a data collection section 71, a data processing section 72, and a data storage section 7.
3, the control method storage section 74, and the control method 4IOiI'J! 4
It is configured to include a part 75 and a result output section 76, and each of the sections 71 to 76 are connected by a data bus 77. The data storage section 73 stores the contents shown in FIGS. 3 to 6. The control method storage unit 74 stores a control program for controlling the entire equipment, a control order for control execution, and the following equations (1) to (3).
The formula is stored and saved.

However, v: new dehydrator belt speed (-/-1=)■. :
Previous dehydrator belt speed (-/-1=) K,: Coefficient MW: Measured dehydrated cake moisture (chi) SW: Target dehydrated cake moisture (-) However, Q: Sludge supply amount (expletive/-) KhK,, K: Coefficient ■: Dewatering machine belt speed (expletive/-) D=sludge change -) N-to, Q-D+, ...4...4 songs, 4 songs (3) However, N: Coagulant mixing ratio Q: Sludge supply amount (-/-'=) D==Sludge concentration (-) K,, K: Coefficient Here, Figure 3 shows the belt speed of the dewatering machine 44 and the water content of the dehydrated cake. Figure 4 is a characteristic diagram showing the relationship between sludge supply amount and dehydrated cake water content when the flocculant ratio is used as a parameter. Figure 5 is a characteristic diagram showing the relationship between sludge concentration and the optimal flocculant. FIG. 6 is a characteristic diagram showing the relationship between the mixing ratios, and is a characteristic diagram showing the relationship when the water content of the dewatered cake does not change even if the belt speed of the dehydrator 44 is reduced depending on the properties of the sludge.

The sludge dewatering equipment configured as described above will be explained below.

A predetermined flow rate of sludge is supplied to the mixing device 10 from a sludge supply device 20 . That is, the mixing device 10 is supplied with sludge from the sludge receiving tank 21 by the sludge pump 22, which is controlled by the sludge pump speed controller 33 so that the flow rate is set according to the command output from the control device 70. .

Moreover, the flocculant is similarly supplied to the mixing device 10 from the flocculant supply device 30 so as to achieve a predetermined mixing ratio. That is, the mixing device 10 receives a flow rate set by the control device 70 from the flocculant storage tank 31 diluted to a predetermined concentration to the flocculant flow control valve 32, that is, the flow rate of the sludge or the solid content of the sludge. A controlled flocculant is supplied to a flocculant flow rate controller 42 that controls the flow rate to a predetermined ratio.

At this time, the degree of rockiness of the sludge is continuously measured by the sludge concentration meter 50 and taken into the control device 70.

The sludge and flocculant are mixed uniformly in the mixing device 10,
After being flocculated, the sludge is fed onto belts 41 , 42 in the dehydrator 44 of the dewatering device 40 .

The dewatering device 40 is controlled by a belt speed controller 45 that controls the speed of the bells 41 and 42 of the dehydrator 44 by a belt drive motor 43 to a speed set by a command output from a control device 70. Controlled to adjust dehydration speed.

The control device 70 calculates the target moisture content of the dewatered cake discharged from the dewatering device 40 and its permissible moisture range: sludge treatment target, and control priority through the data collection unit 71 in advance, and converts the data into numbers and formulas optimal for control. When the dewatering device 40 is processed by the processing section 72 and stored in the data storage section 73 or the control method storage section 74,
The water content of the dewatered cake provided at the outlet of the dewatering device 40 is measured at predetermined intervals by a moisture measuring device 60, and the concentration of the sludge supplied to the dewatering device 40 is measured at predetermined intervals by a sludge concentration measuring device 50. The data is taken into the data storage unit 73 through the data collection unit 71 of 70.

The control calculation unit 75 compares the moisture content of the dehydrated cake with the target dehydrated cake moisture stored in the smooth dampness data storage unit 73, and performs calculations according to the control order stored in advance according to this difference. The sludge flow rate, the mixing ratio of the solid content of the sludge and the flocculant, and the belt speed of the dehydrator 44 of the dehydrator 40 are determined, and commands based on these determined data are sent to the sludge pump speed controller 23, flocculant flow rate controller 33, and The belt speed controller 45 is set. Said respective controllers 23.33.45 adjust the speed and flow rate according to the settings.

As an example, the belt speed control of the dehydrator 44 in the dehydrator 40 and the combined ratio are given first priority. First, the target dehydrated cake moisture is 75%, the allowable moisture range is ±2 inches, and the initial belt speed v0 of the dehydrator 44 is 2.0CIII/
m), the minimum speed limit of the dehydrator is 1.0CFK/-11)
shall be.

The control calculation unit 75 of the control device 700 compares the target dehydrated cake moisture 75- stored in the data storage unit 73 with the measured dehydrated cake moisture (for example, 791: arrogance), and calculates the measured dehydrated cake moisture. 79- is the predetermined range ±2
-, exceeds 29b, so first, the first priority control order is
The flocculant ratio is calculated by the control calculation unit 75 so that the dehydrator belt speed is determined by equation (1) and the sludge supply amount is determined by equation (2). Then, this result is outputted from the result output section 76 to the dewatering machine speed controller 45, the sludge pump speed controller 23, and the flocculant flow rate controller 33. respective controllers 45.23 and 3
3 reduces the speed or flow rate in response to the signal.

At this time, data such as dehydrated cake moisture 79 [chi], sludge concentration, dehydrator belt speed, sludge flow rate, etc. are stored in the data storage section 73.
and stored in the control method storage section 74. After a predetermined period of time has elapsed after this control, the moisture content of the dehydrated cake is measured again.
If this value is, for example, 78 [high], the dehydrator belt speed, sludge flow rate, and flocculant flow rate are further calculated and outputted in the same manner as the above-mentioned procedure. If the moisture content of the dehydrated cake does not fall within the range of 75 ± 2 inches even after repeating the above operations, the dehydrator belt speed may exceed the minimum limit speed of 1.
When the speed reaches 0 (m/sm), the speed of the dehydrator is not controlled, and the sludge flow rate and flocculant mixing ratio, which has the second priority control order, are controlled by calculation using the relationship shown in Figure 4. In the above section (
3) Calculate the mixing ratio according to the formula and set the flocculant flow rate controller 33
Output to. The flocculant control valve 32 is adjusted by an adjustment signal corresponding to the signal from the flocculant flow rate controller 33 to change the flocculant flow rate. This control is repeated until the moisture content of the dehydrated cake falls within the target range.

Conversely, if the dehydrated cake moisture is lower than the target moisture value, n
Each of the equations (1) to (3) outputs a calculation result that is the opposite of the above-mentioned operation. Normally, the above operations bring the moisture content of the dehydrated cake within the target range.

However, depending on the properties of the sludge, the relationship between the capacity of the dewatering device 40 and the moisture content of the dehydrated cake, that is, the relationship between the belt speed of the dehydrator 44 and the moisture content of the dehydrated cake, may be as shown in FIG. At this time, depending on the control described above, the dewatering device 4
In other words, the target moisture content of the dehydrated cake cannot be achieved by adjusting the belt speed of the dehydrator 44. Whether or not this state is present can be determined from the past dewatering capacity of the dewatering device 40 stored in the data storage section 73, that is, from the belt speed of the dehydrator 44 and changes in the water content of the dehydrated cake. If it is determined that the moisture content of the past dehydrated cake is the closest to the target, the dewatering capacity of the dehydrator 140 that is closest to the target, the belt speed of the toe 9 dehydrator 44, etc. are output, and the #l of the second control priority is The mixing ratio of the east agent is adjusted in the same manner as the control described above. As a result, the dehydrated cake whose moisture content is closest to the target moisture content is discharged.

Therefore, a dehydrated cake with a desired moisture content can be automatically obtained at all times.

As described above, the present invention uses a predetermined control procedure to maintain the moisture content of the dehydrated cake within or near a predetermined target value, so that the moisture content of the dehydrated cake is stable and reliable. , and has the effect of achieving a labor saving ratio.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a block diagram showing an embodiment of the dehydration equipment according to the present invention, Fig. 2 is a block diagram showing the detailed configuration of a control device used in the dehydration equipment according to the invention, and Fig. 3 The figure is a custom-made diagram showing the relationship between the belt speed of the dehydrator and the moisture content of the dehydrated cake, Figure 4 is a characteristic diagram showing the relationship between the sludge supply amount and the moisture content of the dehydrated cake, and Figure 5 is a diagram showing the relationship between the sludge concentration and the optimum flocculant ratio. FIG. 6 is a characteristic diagram showing an example of the relationship between the belt speed of the dehydrator and the water content of the dehydrated cake in an abnormal situation. 10... Mixing device, 20... Sludge supply device, 21.
...Storage tank, 32...Flocculant control valve, 33...Flocculant control 4I device, 40...Dewatering device, 41 and 42...
Upper and lower belts, 43... Belt drive motor, 44.
...Dehydrator, 45...Dehydrator speed controller, 50...
Sludge concentration measuring device, 60... Moisture measuring device, 70...
-Control device, 71...Data collection unit, 72...Data processing unit, 73...Data storage unit, 74...Control method storage unit, 75...Control calculation unit, 76...Result Output section. Agent Tatsuyuki Unuma (and 2 others)

Claims (1)

[Claims] (1) A mixing device that mixes sludge and a flocculant to flocculate it, a sludge supply device that can supply a predetermined flow rate of sludge to the mixing device, and a flow rate or solid content of the sludge supplied to the mixing device. a flocculant supply device capable of supplying a flocculant at a predetermined mixing ratio, a dewatering device capable of adjusting dewatering speed to dehydrate the mixture from the mixing device to form a sludge-dehydrated cake; A sludge concentration measuring device detects the supplied sludge concentration, a moisture measuring device detects the moisture content of the sludge dewatered cake from the dewatering device, and a moisture signal from the moisture measuring device is taken in, and this moisture signal is set as a target. If the comparison result exceeds the permissible moisture range, the mixing ratio of the flocculant to the solid content of the sludge obtained based on the sludge flow 1 or the sludge freshness signal from the sludge concentration measuring device, Each control that adjusts the dehydration speed of the dehydration device and the flow rate of sludge supplied to the dehydration device is executed according to a predetermined priority order so that the comparison result is within an allowable range, and the comparison result is also adjusted by the above execution. 1. A sludge dewatering facility comprising: a control device that sets a control state closest to the target moisture value during the execution when the permissible range is exceeded.