JP3835938B2 - Sludge sample supply control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling the amount of sludge sample supplied when measuring the moisture content and loss on ignition of sludge.
[0002]
[Prior art]
The properties of sludge carried into sludge treatment plants such as a sewage sludge wide-area treatment plant are subject to fluctuations and affect the stable operation of incineration and melting plants. Therefore, the theoretical air volume required for combustion is calculated in advance and incinerated. In order to stabilize the melting, the moisture content of the sludge and the loss on ignition are measured.
[0003]
In the sewage test method generally used for this type of measurement (manual analysis method based on the test method defined by the Japan Sewerage Association), the moisture content is measured by weighing a certain amount of sewage sludge and 105-110 ° C. The weight loss after ignition is calculated by measuring the moisture content by ashing at 600 ± 25 ° C for 1 hour, and measuring the weight after cooling. Is calculated by
[0004]
[Problems to be solved by the invention]
When collecting a certain amount of sewage sludge, the metering pump is usually operated for a certain period of time, but if the operation time of the metering pump is fixed, it will be supplied due to fluctuations in sludge properties (water, viscosity, etc.) There was a problem in that the weight of the sludge varies and the accuracy of the measured moisture content and loss on ignition is low, which affects the stabilization of incineration and melting.
[0005]
The present invention solves the above problems, and an object of the present invention is to provide a sludge sample supply amount control method capable of supplying a sludge sample having a constant weight even if the sludge properties fluctuate.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a method for determining the amount of sludge sample that is sequentially supplied to the sludge weight measuring means when measuring the moisture content and loss on ignition of sludge. A method for controlling a sludge sample supply amount controlled by a pump, and in each measurement cycle, a measured value of a sludge weight W (g) and a set target sludge weight W _r (g) at a set operation time T (s) of the metering pump. And the following formula T _N = T− (W−W _r ) × C (C is a correction coefficient)
In accordance with the present invention, a sludge sample supply amount control method is provided in which the set operation time _TN of the metering pump in the next measurement cycle is calculated.
[0007]
According to the above configuration, the set operation time of the metering pump is adjusted each time based on the deviation between the measured value of the sludge weight and the set target sludge weight, so that the sludge sample follows the change in the properties of the sludge that is sequentially carried in. Thus, the sludge sample can be supplied at a constant weight.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
The dewatered sludge moisture content / ignition loss automatic measuring device shown in FIG. 1 is attached to a sludge conveyance path (not shown) to a sludge incineration and melting treatment plant, and includes a measuring device main body 1 and a control panel 2. It consists of and.
[0009]
The control panel 2 includes a PLC (Programmable Logic Controller) 3 and a heating lamp controller 3a. The control panel 2 operates a continuous automatic measurement program to operate the sludge sample supply pump 4 for supplying sludge to the measuring device body 1 and the measuring device. The main body 1 performs control of the hand 5 that transports sludge, temperature control that automatically sets the heating temperature pattern, and the like.
[0010]
Hereinafter, procedures for measuring the moisture content and ignition loss will be described.
A fixed amount of dewatered sludge conveyed through the sludge conveyance path is collected by a sludge sample supply pump 4 rotating at a constant speed, and is pumped to the sludge collection chamber 7 and supplied to the sample tray 8. The dewatered sludge on the sample pan 8 is conveyed to the heating and weighing chamber 9 by the hand 5 and is weighed by the electronic balance 10 and then dried by the halogen lamp 11 and the thermocouple 12 based on a preset heating temperature pattern. In addition, the ash is ignited and the weight is measured by the electronic balance 10 after each step. Then, the moisture content and ignition loss are calculated from each measured value. The exhaust gas generated in each process is discharged outside the system through the exhaust gas treatment device 13, and the ignition residue after the weight measurement is transported again to the sludge collection chamber 7 by the hand 5 and collected in the disposal chamber 14.
[0011]
The procedure for supplying the above dewatered sludge will be described in detail.
As shown in the enlarged view of the main part of FIG. 2, the sludge sample supply pipe 6 communicates with the sludge reservoir 15 of the sludge conveyance path at one end, and the sludge supply nozzle opened above the sample dish 8 at the other end. The sludge sample supply pump 4 is interposed in the sludge sample supply pipe 6. A controller 3 is connected to the sludge sample supply pump 4 and the electronic balance 10. The controller 3 supplies the target sludge weight W _r (g) and the dewatered sludge in the sludge reservoir 15 into the sludge sample supply pipe 6. The operation time T _{0 of the} fixed sludge sample supply pump 4 to be taken in and filled, and the operation time T of the sludge sample supply pump 4 capable of supplying dehydrated sludge substantially corresponding to the target sludge weight W _r (g) to the sample dish 8 s).
[0012]
With the above-described configuration, in the first measurement cycle, the sludge sample supply pump 4 is operated for a certain operation time T ₀ , and the dewatered sludge 19 in the sludge reservoir 15 is filled in the sludge sample supply pipe 6. Next, the sludge sample supply pump 4 is operated for the operation time T (s), and an amount of dewatered sludge 19 substantially corresponding to the target weight is taken into the sludge sample supply pipe 6 from the sludge reservoir 15, and the same amount of dewatered sludge is obtained. 19 is fed out of the tube and supplied to the sample pan 8 through the nozzle 16. The dewatered sludge 19 is measured by the electronic balance 10, and the measured value of the sludge weight W (g) is stored in the controller 3.
[0013]
In the controller 3, the following formula T _N = T is calculated from the operation time T (s) of the sludge sample supply pump 4, the sludge weight W (g) of the dewatered sludge 19, and the target sludge weight W _r (g). − (W−W _r ) × C (C is a correction coefficient)
Based on this, the operating time _TN of the sludge sample supply pump 4 in the next measurement cycle is calculated.
[0014]
In the next measurement cycle, the sludge sample supply pump 4 is operated for a certain operation time T ₀ , the dewatered sludge 19 in the sludge reservoir 15 is taken in, and all the dewatered sludge inside the sludge sample supply pipe 6 is replaced. The sludge sample supply pump 4 is operated for the operation time T _N (s) calculated as described above.
[0015]
In this way, the operation time T _N of the sludge sample supply pump 4 in the next measurement cycle is sequentially calculated from the operation time T (s), the sludge weight W (g), and the target sludge weight W _r (g). In the next measurement cycle, since the sludge sample supply pump 4 is driven for the calculated operation time T _N , the dewatered sludge 19 is supplied at a substantially constant weight regardless of the property change.
[0016]
The sludge collection minimum amount W _l (g) and the sludge collection maximum amount W _H (g) centered on the target sludge weight W _r (g) are determined in advance, and when the sludge weight W <W _l sludge sample supply pump 4 is further operating time _{(W-W r) × C} (s) only being operated dewatered sludge 19 is added harvested, dehydrated sludge 19 which is supplied at the time of the sludge weight W> W _H is forced Immediately after ashing and discarding, move to the next measurement cycle. In this way, when the property variation of the dewatered sludge 19 is very large, measures such as re-collecting the sludge are taken.
[0017]
From both sides of shortening the measurement time and ensuring measurement accuracy when measuring sludge ignition loss, it is appropriate to set the target sludge weight _Wr to about 5 g. The correction coefficient C is determined in advance according to the supply characteristics of the pump, but about 0.2 is appropriate.
[0018]
【The invention's effect】
As described above, according to the present invention, the weight of the sludge sample that is sequentially supplied is evaluated, and the operation time of the sludge sample supply pump is adjusted each time. It can be supplied at a constant weight, and the measurement accuracy of moisture content and ignition loss can be improved, and incineration and melting can be stabilized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic overall configuration of a dewatered sludge moisture content / ignition loss automatic measuring device in which a sludge sample supply amount control method according to an embodiment of the present invention is performed.
2 is an enlarged view of a main part of the dewatered sludge moisture content / ignition loss automatic measuring device shown in FIG. 1. FIG.
[Explanation of symbols]
4 Sludge sample supply pump 6 Sludge sample supply pipe
10 Electronic balance
19 Dewatered sludge

Claims (1)

When measuring the sludge moisture content and loss on ignition, a sludge sample supply control method is used to control the amount of sludge sample supplied to the sludge weight measuring means by means of a metering pump installed in the sludge sample supply pipe. In each measurement cycle, the measured value of the sludge weight W (g) at the set operation time T (s) of the metering pump is compared with the set target sludge weight W _r (g), and the following formula T _N = T− (W−W _r ) × C (C is a correction coefficient)
A method for controlling the amount of sludge sample supply, characterized in that the set operation time _TN of the metering pump in the next measurement cycle is calculated based on the above.

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