JPH03131399A - Process for concentrating sludge at low flow rate - Google Patents

Abstract

PURPOSE:To make feed-sludge flow rates to a centrifugal concentrating machine constant and to stabilize concentration performances of said machine by absorbing fluctuations in feed rates of sludge in a sludge storage tank and maintaining the quantity of sludge in the tank always in a predetermined range by returning separated liquids. CONSTITUTION:Concentrations of sludge in a sludge storage tank 1 are detected by a sludge concentration meter 15, while a flowmeter 4 detects flow rates of sludge flowing into the tank 1 via a sludge feed pipe 3, whereby the detected concentrations and flow rates of the sludge are transmitted to a control device 16. And the total sum of the flow rates of sludge fed into the tank 1 via the pipe 3 and the flow rates of separated liquid which is returned to the tank 1 from a separated liquid tank 11 via a circulation pipe 13 is maintained constant. As a result, fluctuations in the feed rates of sludge from the pipe 3 are absorbed by the tank 1, while, by returning the separated liquids, the quantity of the sludge in the tank 1 is maintained within a predetermined range, so that sludge can be supplied to a centrifugal concentrating machine 7 always at a constant rate.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for concentrating sludge at low flow rates in sludge treatment equipment when the inflow of sludge is extremely smaller than the planned flow rate.

BACKGROUND OF THE INVENTION Conventionally, in sludge treatment facilities, sludge has been concentrated using a centrifugal thickener, and the thickened sludge and separated liquid have been separated and discharged. Conventionally, the concentration characteristics change with an extreme decrease in the amount of sludge supplied to the centrifugal thickener, so in order to cope with this change, the diameter of the centrifugal thickener's thickened sludge discharge pipe was adjusted to increase the pressure loss. Either the sludge thickening rate had to be controlled by the sludge tank, or the centrifugal thickener had to be operated intermittently depending on the water level in the sludge storage tank.

Problems to be Solved by the Invention However, in the conventional configuration, when the amount of sludge supplied to the centrifugal thickener becomes low flow rate of 50% or less of the standard treatment flow rate in continuous operation, the concentration performance becomes unstable, and the diameter of the thickened sludge discharge pipe becomes unstable. There was a problem of complicating maintenance and management. Alternatively, in order to ensure a standard throughput in the centrifugal concentrator at low flow rates, the centrifugal concentrator must be operated intermittently, resulting in problems such as increased waste time and increased power consumption.

The present invention solves the above problems, and aims to provide a method for concentrating sludge at low flow rates, which can maintain stable concentration performance even when the sludge supply amount is low.

Means for Solving the Problems In order to solve the above problems, the present invention provides a method for concentrating sludge using a centrifugal thickener, and discharging the concentrated thickened sludge and separated liquid separately through a sludge storage tank. In addition to supplying sludge to the centrifugal thickener, a portion of the separated liquid is returned to the sludge storage tank, and the sludge amount detection means detects changes in the amount of sludge in the sludge storage tank, and the sludge is separated according to the detected changes in the amount of sludge. The amount of liquid returned is controlled by the control means, and the amount of sludge in the sludge storage tank is maintained within a certain range, so that the flow rate of sludge fed to the centrifugal thickener is always at an appropriate amount.

In addition, in the concentration equipment that thickens sludge with a centrifugal thickener and separates and discharges the thickened sludge and separated liquid, the sludge is supplied to the centrifugal thickener through the sludge pipe, and a portion of the separated liquid is also discharged together with the sludge. A sludge amount detection means detects fluctuations in the flow rate of sludge that is returned to the centrifugal thickener and is supplied from the sludge feed pipe to the centrifugal thickener, and the means controls the amount of separated liquid to be returned in accordance with the detected fluctuation in the flow rate of sludge feed. By controlling the flow rate of sludge fed to the centrifugal thickener, the flow rate of sludge fed to the centrifugal thickener is always kept at an appropriate amount.

Effect With the above configuration, when the amount of sludge supplied to the sludge storage tank decreases and the amount of sludge stored in the sludge storage tank decreases, the separation to the sludge storage tank is performed according to the fluctuation of the amount of sludge in this sludge storage tank. Increase the amount of liquid returned. In addition, when the amount of sludge supplied to the sludge storage tank increases and the amount of sludge stored in the sludge storage tank increases, the amount of separated liquid returned to the sludge storage tank will be adjusted according to the change in the amount of sludge in the sludge storage tank. reduce

As a result, fluctuations in the amount of sludge fed are absorbed in the sludge storage tank, and by returning the separated liquid, the amount of sludge in the sludge storage tank is always maintained within a certain range, making the flow rate of sludge supplied to the centrifugal thickener constant. , the concentration performance of the centrifugal concentrator is stabilized.

In addition, in the second configuration, when the flow rate of sludge supplied from the sludge pipe to the centrifugal thickener decreases, the amount of separated liquid returned to the centrifugal thickener is increased in accordance with fluctuations in the flow rate of sludge feed. let Furthermore, when the flow rate of fed mud supplied to the centrifugal thickener increases, the amount of separated liquid returned to the centrifugal thickener is reduced in accordance with the variation in the flow rate of fed mud. Due to this,
Fluctuations in the flow rate of mud supplied to the centrifugal thickener from the mud feed pipe 5- are absorbed by adjusting the return flow rate of the separated liquid, and the flow rate of mud fed to the centrifugal thickener is fixed, thereby stabilizing the concentration performance in the centrifugal thickener. is planned.

EXAMPLE An example of the present invention will be described below based on the drawings. 1st
In the figure, a sludge pipe 3 is connected to a sludge storage tank 1 via a sludge pump 2, and a flow meter 4 as a sludge amount detection means is interposed in the middle of the sludge pipe 3. The sludge storage tank 1 also communicates with a centrifugal thickener 7 via a sludge feed pipe 6 in which a sludge feed pump 5 is interposed, and the centrifugal thickener 7 has a thickened sludge discharge pipe 8 for discharging the thickened sludge. and a separated liquid discharge pipe 9 for discharging the separated liquid. Further, the concentrated sludge discharge pipe 8 communicates with the concentrated sludge tank IO, and the separated liquid discharge pipe 9 communicates with the separated wave tank 11. And separation liquid tank 1
A discharge pipe 12 and a circulation pipe 13 are open to the sludge storage tank 1 , and the circulation pipe 13 communicates with the sludge storage tank 1 via a circulation pump 14 . In addition, a sludge concentration meter 15 is arranged by immersing the sensor part in the sludge storage tank 1, and the sludge concentration meter 5 is connected to the control device I via a signal line.
6. Further, a flow meter 4 and a circulation pump I4 are connected to the control device I6 via a signal line, and the control device 16 and the circulation pump 14 constitute a control means for controlling the amount of returned separated liquid. Also,
A stirring device I7 is provided inside the sludge storage tank 1.

Hereinafter, the effects of the above configuration will be explained.

The sludge sent out by the sludge pump 2 flows into the sludge storage tank 1 through the sludge feed pipe 3, and the separated liquid sent out by the circulation pump 14 flows into the sludge storage tank 1 through the circulation pipe 13. Furthermore, the sludge and the separated liquid are stirred and mixed in the sludge storage tank 1, and the sludge mixed with the separated liquid is fed to the centrifugal thickener 7 through the sludge feeding pipe 6 by the sludge pump 5.

Then, the sludge is concentrated in the centrifugal thickener 7, the concentrated sludge is divided into thickened sludge and separated liquid, the thickened sludge is discharged through the thickened sludge discharge pipe 8 to the thickened sludge tank IO, and the separated liquid is The separated liquid tank 11 passes through the separated liquid discharge pipe 9
is discharged. Further, the separated liquid is returned to the sludge storage tank 1 through the circulation pipe 13, and a portion is sent to the next treatment system through the discharge pipe 12.

At this time, the amount of returned separation liquid is controlled by the following procedure. That is, the sludge concentration in the sludge storage tank 1 is detected by the sludge concentration meter 15, and the flow rate of sludge flowing into the sludge storage tank 1 through the sludge pipe 3 is detected by the flowmeter 4, and the detected sludge concentration value and Send the sludge flow rate value to the control device 16. Since the amount of sludge supplied from the sludge storage tank 1 to the centrifugal thickener 7 by the sludge pump 5 through the sludge supply pipe 6 is fixed, the sludge is supplied from the sludge pipe 3 to the sludge storage tank 1. The control device 1B calculates the fluctuation value of the sludge flow rate value as the fluctuation value of the sludge amount in the sludge storage tank 1, controls the discharge amount of the circulation pump 14 according to the calculated fluctuation value, and removes the sludge from the sludge pipe 3. The total amount of the sludge flow rate supplied to the storage tank 1 and the return amount of the separated liquid returned to the sludge storage tank 1 through the circulation pipe 13 is maintained constant. In other words, when the amount of sludge supplied to the sludge storage tank 1 decreases, the amount of separated liquid returned to the sludge storage tank 1 is increased, and when the amount of sludge supplied to the sludge storage tank 1 increases, the amount of separated liquid returned to the sludge storage tank 1 is increased. reduce

As a result, fluctuations in the amount of sludge supplied from the sludge pipe 3 are absorbed by the sludge storage tank 1, and the amount of sludge in the sludge storage tank 1 is always maintained within a certain range by returning the separated liquid for centrifugal concentration. A fixed amount of sludge can always be supplied to the machine 7, and the concentration performance of the centrifugal thickener 7 can be stabilized and the centrifugal thickener 7 can be operated continuously. In addition, by appropriately adjusting the mixing ratio of sludge and separated liquid, the sludge concentration at the inlet of the centrifugal thickener 7 can be adjusted to an arbitrary range. This is an effective means of adjusting the concentration when the concentration of the sludge being sent is high.

FIG. 2 shows another embodiment of the present invention, and members that perform the same functions as those in the previous embodiment are given the same reference numerals and their explanations will be omitted. In FIG. 2, a water level gauge 21 is provided with a sensor section immersed in the sludge storage tank 1, and is connected to a control device 9-16 via a signal line.

In this configuration, the water level gauge 21 acts as a sludge amount detection means. That is, the amount of sludge stored in the sludge storage tank 1 is detected by the water level gauge 21, the value of the detected sludge storage amount is transmitted to the control device 1B, and the fluctuation value of the amount of sludge stored is detected as the fluctuation in the amount of sludge in the sludge storage tank 1. The flow rate of sludge supplied from the sludge pipe 3 to the sludge storage tank 1 by controlling the discharge amount of the circulation pump 14 according to the calculated fluctuation value and the circulation pipe! 3 and the total amount of the separated liquid returned to the sludge storage tank 1 is maintained constant. Other effects are the same as in the previous embodiment.

FIG. 3 shows still another embodiment of the present invention,
Components that perform the same functions as those in the previous embodiment are given the same reference numerals and descriptions thereof will be omitted. In FIG. 3, the circulation pipe 13
is connected to the mud supply pipe 6 at a position downstream of the mud supply pump 5, and the mud supply pump 5 is connected to the control device 16 via a signal line.
are communicating.

In this configuration, the discharge amount 10- of the sludge pump 5 is controlled by the controller I6 according to the sludge flow rate of the sludge feed pipe 3 detected by the flow meter 4, and the sludge is supplied from the sludge feed pipe 3 to the sludge storage tank 1. The sludge flow rate supplied from the sludge supply pipe 6 to the centrifugal thickener 7 is synchronized. Then, the control device I6 calculates the fluctuation value of the sludge flow rate of the sludge feed pipe 3 detected by the flow meter 4 as the fluctuation value of the sludge feed flow rate supplied from the sludge feed pipe 6 to the centrifugal thickener 7. The control device 16 adjusts the discharge amount of the circulation pump 14 in accordance with fluctuations in the mud supply flow rate. That is, when the flow rate of sludge from the sludge pipe 3 to the sludge storage tank 1 and the flow rate of sludge supplied from the sludge pipe 6 to the centrifugal thickener 7 decrease, the flow rate of sludge from the sludge pipe 3 to the centrifugal thickener 7 decreases. The amount of separated liquid to be returned to the centrifugal concentrator 7 is increased in accordance with fluctuations in the feed flow rate. In addition, when the flow rate of mud supplied from the mud supply pipe 6 to the centrifugal thickener 7 increases, the amount of separated liquid returned to the centrifugal thickener 7 is reduced in accordance with the fluctuation of the flow rate of mud feed.

As a result, fluctuations in the flow rate of the sludge supplied from the sludge pipe 3 to the centrifugal thickener 7 via the sludge storage tank 1 and the sludge feed pipe 6 can be absorbed by adjusting the return amount of separated liquid, and The concentration performance of the centrifugal thickener 7 can be stabilized by making the flow rate of mud supply constant.

FIG. 4 shows still another embodiment of the present invention,
Components that perform the same functions as those in the previous embodiment are given the same reference numerals and descriptions thereof will be omitted. In Figure 4, water level gauge 21
constitutes a sludge amount detection means and detects the amount of sludge stored in the sludge storage tank 1.

In this configuration, the discharge amount of the sludge pump 5 is controlled by the controller 1G according to the value of the amount of sludge stored in the sludge storage tank 1 detected by the water level gauge 21, and the sludge is supplied from the sludge pipe 3 to the sludge storage tank 1. The sludge flow rate supplied from the sludge supply pipe 6 to the centrifugal thickener 7 is synchronized.

Then, the control device 1B calculates the fluctuation value of the sludge storage amount in the sludge storage tank 1 detected by the water level gauge 21 as the fluctuation value of the sludge supply flow rate supplied from the sludge supply pipe 6 to the centrifugal thickener 7. The control device 16 adjusts the discharge amount of the circulation pump 14 in accordance with the variation in the mud supply flow rate. In other words, sludge storage! When the amount of sludge stored in 1 and the flow rate of sludge supplied from the sludge supply pipe 6 to the centrifugal thickener 7 decrease, the sludge is returned to the centrifugal thickener 7 through the circulation pipe I3 and the sludge supply pipe 6. The amount of separated liquid to be returned is increased according to the fluctuation of the mud supply flow rate. In addition, when the flow rate of mud supplied from the mud supply pipe 6 to the centrifugal thickener 7 increases, the amount of separated liquid returned to the centrifugal thickener 7 is reduced in accordance with the fluctuation of the flow rate of mud feed.

As a result, fluctuations in the flow rate of the sludge supplied from the sludge pipe 3 to the centrifugal thickener 7 via the sludge storage tank 1 and the sludge feed pipe 6 can be absorbed by adjusting the return amount of separated liquid, and The concentration performance of the centrifugal thickener 7 can be stabilized by making the flow rate of mud supply constant.

FIG. 5 shows still another embodiment of the present invention,
The sludge pipe 3 is directly connected to a centrifugal thickener 7, and a flow meter 4 interposed in the middle of the sludge pipe 3 is used as a sludge amount detection means.

According to this configuration, the flow rate of mud supplied from the mud feeding pipe 3 to the centrifugal thickener 7 is detected by the flow meter 4, and the detected mud feeding flow rate is transmitted to the control device 16 to determine the fluctuation value of the mud feeding flow rate. Calculate. Then, the discharge amount of the slurry pump 14 is controlled by the control bag 13-1G according to the calculated fluctuation value of the slurry supply flow rate, and the fluctuation of the slurry supply flow rate supplied from the slurry supply pipe 3 to the centrifugal thickener 7 is separated. The concentration performance of the centrifugal thickener 7 can be stabilized by absorbing the liquid by adjusting the amount of liquid returned, and by making the flow rate of slurry supplied to the centrifugal thickener 7 fixed.

Effects of the Invention As described above, according to the present invention, fluctuations in the amount of sludge sent are absorbed in the sludge storage tank, and the amount of sludge in the sludge storage tank is always maintained within a certain range by returning the separated liquid. , the flow rate of sludge supplied to the centrifugal thickener can be fixed, and the concentration performance of the centrifugal thickener can be stabilized.

In addition, by absorbing fluctuations in the flow rate of mud supplied from the mud pipe to the centrifugal thickener by adjusting the amount of separated liquid returned,
By making the flow rate of sludge supplied to the centrifugal thickener fixed, it is possible to stabilize the concentration performance of the centrifugal thickener.

[Brief explanation of the drawing]

Figure 1 is an overall configuration diagram showing one embodiment of the present invention, Figure 2 is an overall configuration diagram showing another embodiment of the invention, and Figures 14-3 are overall diagrams showing still another embodiment of the invention. Diagram,
FIG. 4 is an overall configuration diagram showing still another embodiment of the present invention,
FIG. 5 is an overall configuration diagram showing still another embodiment of the present invention. 1...Sludge storage tank, 4...Flow meter, 7...Centrifugal thickener, 13...Circulation pipe, 14...Circulation pump, IG
...Control device, 21...Water level gauge.

Claims (1)

[Claims] 1. In a concentration facility that thickens sludge with a centrifugal thickener and separates and discharges the thickened sludge and separated liquid, the sludge is supplied to the centrifugal thickener via a sludge storage tank, and A portion of the separated liquid is returned to the sludge storage tank, a sludge amount detection means detects a change in the amount of sludge in the sludge storage tank, and a control means controls the amount of separated liquid returned according to the detected change in the sludge amount. A sludge thickening method at low flow rates, characterized in that the flow rate of sludge fed to a centrifugal thickener is always at an appropriate level by maintaining the amount of sludge in a sludge storage tank within a certain range. 2. In the concentration equipment that thickens sludge with a centrifugal thickener and separates and discharges the thickened thickened sludge and separated liquid, the sludge is supplied to the centrifugal thickener through the sludge pipe, and a part of the separated liquid is also discharged together with the sludge. A sludge amount detection means detects fluctuations in the flow rate of sludge that is returned to the centrifugal thickener and is supplied from the sludge feed pipe to the centrifugal thickener, and the means controls the amount of separated liquid to be returned in accordance with the detected fluctuation in the flow rate of sludge feed. A sludge thickening method at low flow rates, characterized in that the flow rate of sludge supplied to a centrifugal thickener is always maintained at an appropriate amount by controlling the flow rate.