JPS5952322B2 - How to control the speed of a stoker in a garbage incinerator - Google Patents

Description

[Detailed Description of the Invention] This invention relates to speed control of a waste supply stoker in a waste incinerator, and more specifically, it is concerned with speed control of a waste supply stoker in a waste incinerator, and more specifically, it is designed to always cut out a stable weight of waste even when the quality of waste changes. It is something.

In conventional garbage incinerator work, when the garbage in the garbage input chute has fallen to a certain level, new garbage is added, but at this time, workers take into account the combustion status of the garbage and use their experience to set up a stoker. − is adjusting the speed.

However, according to this method, it is extremely difficult to adjust the stoker speed to suit the combustion rate of the garbage or the combustion conditions.

About an hour after the adjustment, or after adding garbage several times, the furnace status will indicate whether or not the adjustment was correct.
That won't be of any use in the festival later on.

In addition to this difficulty in adjustment, it is extremely difficult to adjust the speed of the stoker because the quality and moisture content of the waste that is thrown in changes each time.

The stoker referred to here refers to the first-stage stoker or feeder located directly below the input hopper, and the amount of garbage supplied or cut out relates to the weight of the garbage to be fed, not the volume of the garbage to be fed.

This first stage stoker is also called a drying stoker, and is designed to dry the waste as much as possible, but when the bulk density of the waste is high, the weight of the feed to the furnace is large, and when the moisture content is low, the bulk density of the waste is high. If the bulk specific gravity is small, the supplied weight is small;
Therefore, since the amount of heat generated in the furnace is different, this waste quality must also be taken into consideration when selecting the stoker speed.

Due to the structure of the machine, the amount sent by the stoker is based on volume, and due to the nature of the furnace, in order to incinerate waste based on weight, it is necessary to clarify the relationship between volume and weight.

Below, these relationships will be clarified with reference to drawings and charts, and a method of controlling the stoker speed for complete combustion will be explained.

FIG. 1 shows a cross-sectional view of the vicinity of the garbage input hopper of the garbage incinerator.

Garbage is transferred to input hopper 2 by grab 1 of garbage crane.
The upper surface level of the garbage is measured by an ultrasonic level meter 3, and the garbage is supplied to the next grate (not shown) by a stoker 4.

When the top level of the garbage drops to the garbage loading preparation level shown in Figure 5, the crane moves to the garbage pit (not shown).
When the ultrasonic level meter 3 detects that the top surface level of the garbage has reached the garbage input instruction level shown in figure 6, the garbage in grab 1 of the crane is immediately input. and becomes level 7.

In the following, according to this, therefore, with respect to time as shown in Figure 2,
The top level position of the trash changes.

Regarding the period from the end of the first garbage input to the start of the second garbage input, T1 = G1/g where T... Estimated time during the above... minutes G1...
First garbage input weight kgg... Garbage cutting setting value 1 (g/m1n (or target incineration weight) Standard descent speed of the top level of garbage VS1 h... Garbage input instruction from ultrasonic level meter Fixed distance to the level m hOl...Distance to completion of input (m) 2nd time G2...2nd garbage input amount kg T1'...2nd actual garbage input completion time ln Nth time now, g = If we set 209 kg/min h = 8 m, the result will be as above.

This can be illustrated graphically as shown in Figure 3.

Therefore, by adjusting the stoker speed so as to reach the calculated value VSn, large fluctuations in the weight of the garbage cut out can be suppressed and preferable combustion can be obtained.

The above is about the measured values (actual values) and calculated values (target values) regarding the rate of descent of the top level of the garbage to be incinerated.
It is necessary to adjust the speed of the stoker so that the VSn calculated when the garbage input is completed.

To do this, it is necessary to consider adjustments during the process from the above-mentioned input to the next input.

Regarding this, the adjustment of the speed of the first stage stoker will be considered as follows.

Let v5 be the standard rate of descent of the top surface level of the garbage from the garbage input upper limit ho point to the lower limit point in Figure 4 for one cycle, and divide the scheduled time T minutes into i (
In this case, the measurement is divided into three parts) and the upper surface level position during continuous measurement of dust at each division time is checked.

Considering that the quality of waste changes rapidly and is highly variable, adjustments will be made when the value exceeds ±5% of the set value.

Taking column 1 of table 1 on the previous page as an example, T = 14.8 minutes Vs = 0.155 m /m1
nt=17iT=approx. 5 minutes VR=VSX U±5/100) =0.155±0.
008m/miVR is the allowable descending speed of the top surface of the garbage,
, the level at each point in time according to the reference value 5 of , hs, the level at each point in time according to the upper limit value VH of VR, hH, and the level at each point in time according to the lower limit value 2 of VR, as shown in FIG.

The horizontal axis indicates the elapsed time from the garbage input completion time as a reference, and in particular, the permissible positions of the upper surface of the garbage are numerically shown for 5, 10, 14, and 8 minutes.

The corresponding numerical values are shown in Table 2 below.

Note: 14. If level h is reached before 8 minutes have elapsed, immediately throw the garbage.

As in the example above, the top surface level position of the garbage is checked at predetermined intervals, and if there is a deviation greater than the allowable amount, the speed of the subsequent stoker is changed and adjusted, and the next garbage input is started as soon as possible. Normal supply should be achieved by the time the

To do this, the level of the upper surface of the garbage is checked with the ultrasonic level meter 3 at predetermined time intervals, and the necessity of changing the stoker speed and the extent of the change are examined each time.

i If the top level of trash is within the permissible range.

The stalker's speed does not change. ii When the level of the top surface of the garbage exceeds the permissible range.

See Figures 5 and 6.

If the corrected setting speed is VSI, then So: Nostalker speed m/m1 in case of VS(7)
n81': Stalker speed in case of VS1 m 7m1
In the case of nti-L, the stalking speed is adjusted in the same manner as above.

iii When the top surface level of garbage has not reached the specified level at the scheduled input time T.

See Figure 7.

Switch to VS3-vS and wait until the top of the garbage falls to the drop command level.

iv If the top surface level of garbage falls to the input instruction level before the scheduled input time T.

Immediately throw away the garbage.

If the above work procedure is shown as a process chart, it will be as shown in FIG.

In the figure, in the seventh position from the top, the number of level checks can be fixed, for example, every five minutes, instead of being divided.

In this way, the garbage is incinerated.

The equipment structure controls the amount of waste to be supplied based on volume, but by adjusting the speed of the stoker, the weight can be brought as close to the standard as possible, the amount of heat source supplied to the furnace can be averaged, and the amount of heat source supplied to the furnace can be further refined. This made it possible to adjust the supply amount without any guideline, which was conventional, and as a result, it became possible to improve the efficiency of waste incinerators.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the vicinity of the waste incinerator's waste input hopper.
FIG. 2 is a diagram showing the relationship between the passage of time and the level of the top surface of the trash, and is shown in conjunction with FIG. 1 for ease of understanding. FIG. 3 is a garbage input schedule diagram corresponding to Table 1. Figure 4 shows the top surface of standard garbage, level transition diagram, Figures 5 and 6.
The figure shows a method of adjusting the stoker speed during garbage input and disposal, Figure 7 shows a countermeasure diagram for an example of maladjustment, and Figure 8 shows a process chart. 1...garbage crane grab, 2...
Input hopper, 3... Ultrasonic level meter, 4...
...Garbage supply stalker-15... Garbage input preparation level, 6... Garbage input instruction level, 7.
...Trash upper limit level.

Claims (1)

[Claims] 1. Speed control of the waste incinerator's stoker, which detects when the top level of the garbage thrown into the waste incinerator's waste input hopper has reached the garbage input instruction level and repeats the operation for next time garbage input. In the method, for the period from the end of garbage input into the garbage input hopper to the start of the next garbage input, the standard descent rate of the top level of garbage is calculated from the scheduled time of the above period and the difference between the garbage input instruction level and the input end level. Continuously measure the top level of the garbage in the garbage hopper, divide the scheduled time, find the deviation between the rate of descent of the top level of garbage at each divided time and the standard rate of descent, and calculate this deviation. A method for controlling the speed of a stoker in a waste incinerator, characterized in that the speed of the stoker is corrected at each division time when the speed exceeds a preset allowable value.