JP6685506B2 - Waste incinerator - Google Patents

Description

  The present invention relates to a waste incinerator that measures a moisture content as a property of waste and incinerates the waste according to the measured value.

  In recent years, there has been an increasing interest in recovering the thermal energy generated by the incineration of waste in a waste incinerator, and the number of waste incinerators equipped with a boiler power generation facility driven by this thermal energy has increased and is high. Combustion operation that can achieve efficient heat recovery is required. On the other hand, as the regulation of environmental pollutants released from the waste incinerator into the atmosphere becomes stricter, combustion operation is required to reduce the emission of toxic substances derived from combustion such as dioxins and nitrogen oxides.

  As described above, since advanced combustion operation control is desired for the waste incinerator, operation control that satisfies the above requirements is performed by the automatic combustion control device. In the automatic combustion control device, when the incinerator is, for example, a stoker-type incinerator, the steam generation amount is controlled by controlling the operation amount such as the dust feed rate, the combustion grate feed rate, the combustion air amount, and the cooling air amount. For the purpose of stabilizing, suppressing the concentration of dioxins and nitrogen oxides in the exhaust gas to be low, and reducing the unburned components in the ash, the waste is stably burned. However, such combustion control does not monitor the properties of the waste at the time of inputting the waste, and in any case, the combustion gas temperature, the oxygen concentration in the combustion gas, the carbon monoxide in the combustion gas generated as a result of the combustion are all observed. This is a method of detecting the concentration etc. as a factor to monitor and feeding back to the control value of each manipulated variable, therefore it becomes a follow-up type control, and stable operation control is always required when the property of the waste to be put into the processing furnace changes. May not be achieved.

  A major factor that disturbs the stability of the combustion operation of the waste incinerator is that the heat generation amount of the waste fluctuates because the properties of the input waste are not constant. Since the properties of the waste that is put into the incinerator greatly vary depending on the area where the waste is collected, the time when the waste is collected, the weather, and the season, the calorific value of the waste greatly changes. Therefore, Patent Document 1 proposes a method for controlling a waste incinerator in which the properties of the waste to be input are obtained before the input and combustion control is performed according to the obtained properties of the waste. Among the properties of the waste, the factor that greatly affects the heat generation amount is the moisture content of the waste, and in the technique of Patent Document 1, the waste on the conveyor is supplied to the conveyor that supplies the waste to the waste incinerator. It is equipped with a weight measuring device that measures the weight, a level measuring device that measures the thickness of the waste on the conveyor, and an infrared moisture meter that measures the moisture content of the waste on the conveyor. It is described that the water content as a property is estimated and combustion control is performed according to the property. Further, in Patent Document 2, a capacitance meter is arranged as a moisture content meter at a middle portion in a height direction of a chute that is hung down from a charging port of a waste incinerator toward a combustion chamber, and a capacitance meter is disposed between a pair of electrodes. The moisture content of waste is obtained by measuring the capacitance.

  The infrared moisture meter irradiates infrared rays on an object to be measured and detects the reflection of infrared rays from the object to obtain the moisture content. Moisture has a property of absorbing a specific wavelength of near-infrared light, and when the amount of water contained in the measurement target increases, the amount of infrared energy absorbed increases and the amount of reflected infrared energy decreases. The infrared moisture meter applies such a phenomenon to measure the moisture content of the measurement object.

  The capacitance meter is connected to the moisture content calculator that holds the correspondence relationship between the capacitance value and the moisture content value, and the correspondence value is calculated from the measurement value measured by the capacitance meter. The moisture content can be calculated based on this.

Japanese Patent Laid-Open No. 2000-283444 JP 2010-216990A

  In the technique described in Patent Document 1, the weight and level (height) of the waste on the conveyor and the moisture content are measured to estimate the property of the waste. However, this technique has a problem that only the moisture content of the waste surface layer can be measured because the infrared moisture content is measured using an infrared moisture meter to measure the moisture content of the waste material.

  Further, in Patent Document 2, the pressure density of the waste changes due to the weight of the waste due to the height position of the waste layer in the chute, and thus the moisture content also changes. However, since the moisture content is measured at the middle position in the height direction of the waste layer, there is a problem in that the moisture content immediately before being fed into the combustion chamber is not measured. To be more specific, when wastes are sequentially charged into the chute, a waste layer is formed in the chute, but the wastes in the upper layer of this waste layer are in a state of being roughly and coarsely stacked. Due to the weight of the waste, the waste voids are filled with fine waste and fill the voids as they descend through the chute. Thus, the pressure density changes toward the lower layer. When the pressure density changes, the water content also changes. Therefore, in the case of waste incineration, although it is necessary to perform appropriate operation control based on the moisture content of the waste immediately before incineration, in Patent Document 2, the moisture content in the middle portion is measured, so that it is not always appropriate. It cannot be said that it is a simple measurement.

  In view of such circumstances, the present invention is capable of grasping the moisture content of waste just before it is sent to the combustion chamber, and operating and controlling the waste incinerator under appropriate operating conditions. The challenge is to provide.

  According to the present invention, the above-mentioned problems are solved by a waste incinerator configured as follows.

  In a waste incinerator in which a detection element of the moisture meter for measuring the moisture content of the waste is provided in a chute extending downward from the waste input port of the waste incinerator for incinerating the waste, the detection element of the moisture meter is A waste incinerator characterized by being disposed in a low-rise area having a higher pressure density than a high-rise area forming an upper part of a waste layer formed by throwing waste into a space inside a chute.

  According to the device of the present invention having such a configuration, since the moisture content of the waste is measured in the lower layer region of the waste layer in the chute, the moisture content of the waste is measured immediately before being fed into the combustion chamber. As a result, the operating conditions of the waste incinerator can be optimally controlled.

  In the present invention, the lower layer region in which the moisture meter is arranged is sufficient if it is a region formed below the depth position of 3 m from the upper surface of the waste layer.

  According to the device of the present invention configured as described above, the moisture content of the waste is measured in the lower layer region of the waste layer immediately before being fed into the combustion chamber. It is controlled and operated under the most suitable operating conditions for incineration in the room, and its efficiency is further improved.

It is a schematic block diagram of the apparatus of one embodiment of the present invention.

  FIG. 1 shows the structure of a grate-type waste incinerator 1 as a waste incinerator. The present invention is applicable not only to the grate type but also to other types of waste incinerators.

  The waste incinerator 1 receives combustion air from a plurality of air supply systems 12 provided below the grate 11, and wastes on the grate 11 in a combustion chamber 13 formed above the grate 11. It is designed to incinerate P. The grate 11 is sending the waste P at a feed rate to the right. A dust supply device 14, for example, a pusher, is provided at a position above the left end of the grate 11 so as to send dust to the grate 11. A chute 15 extends upward above the dust supply device 14, and a hopper 16 as an input port is provided at the upper end of the chute 15. A waste pit 17 is arranged outside the waste incinerator 1. A refuse crane 18 is provided above it so that the waste P can be taken out from the refuse pit 17 and dropped into the hopper 16.

  As described above, the layer of the waste P formed in the chute 15 is roughly divided into two layers, that is, a high-rise area A having a low-pressure density and a low-rise area B having a high-pressure density. . In the high-rise area A, the waste is coarsely and randomly piled up and has a low pressure density, but in the low-rise area B, in addition to the dead weight of the waste in the low-rise area B, the waste in the high-rise area A is also added. Since it also receives weight, fine waste enters the voids of the waste and fills the voids, resulting in a high-pressure density. The water content is higher in the low-layer area B of high pressure density than in the high-layer area A of low pressure density.

In many cases, the lower layer area B is an area below the depth position of 3 m from the upper surface of the waste layer. This has been confirmed by the following examination. In general waste such as municipal waste, when pressure of 2.5 kPa or more is applied, the void density of the waste is filled with fine waste and the bulk density becomes high. Under the pressure of 1, the bulk density does not increase and becomes constant. On the other hand, the bulk density of general waste without pressure is 150 to 200 kg / m ³ , and the pressure due to the dead weight of the waste at the bottom of the piled waste having a height of 3 m is 5 kPa. From these, it was confirmed that the region below the depth position of 3 m from the upper surface of the waste layer is the low-layer region of high pressure density.

  The amount of air blown into the air supply system 12, the feed rate of the grate 11, and the feed rate of the dust supply device 14 are variable.

  The waste crane 18 has a crane main body 18A that can travel laterally and a bucket 18C that can hang down from the crane main body 18A with a wire 18B and can move up and down. The bucket 18C can move up and down between a position above the waste pit 17 and a position inside the waste pit 17, grasps the waste P in the waste pit 17 and moves up, and moves laterally to a position above the hopper 16. After that, the waste P is dropped into the hopper 16.

  In this embodiment, a capacitance meter 20 for measuring the capacitance of the waste P in the chute 15 is provided. The capacitance meter 20 has a detection element 20A (for example, an electrode), and the detection element 20A is attached to the inner surface of the side wall of the chute 15 in the lower layer area B. Thus, the capacitance meter 20 detects the capacitance of the waste P having a high pressure density and existing in the vicinity of the detection element 20A in the lower layer area B in the chute 15.

  The capacitance meter 20 is connected to a moisture content calculator 21. In this moisture content calculator 21, the moisture content corresponding to the value of the capacitance measured by the capacitance meter 20 is calculated from the relationship between the value of the capacitance and the value of the moisture content of the dust that is stored in advance. The value of can be calculated. Specifically, the moisture content calculator 21 holds a relational database which is obtained by previously measuring and clarifying the relation between the capacitance of waste and the moisture percentage of waste. The measured moisture content of the waste P is collated with the relationship between the capacitance and the moisture content in the above-mentioned relational database to calculate the measured moisture content of the waste.

  In the present embodiment, the capacitance meter 20 including the detection element 20A and the moisture content calculator 21 constitute a capacitance contact type moisture meter. Further, the moisture meter is not limited to the capacitance contact type moisture meter, and, for example, a capacitance transmission type moisture meter, a microwave contact type moisture meter, a microwave transmission type moisture meter or an infrared moisture meter is adopted. Good.

  The water content calculator 21 is connected to a controller 22, which controls the water content received from the water content calculator 21 with respect to the high-pressure-density waste P in the lower layer area B in the chute 15. From the value, the accurate calorific value of waste is estimated based on the correspondence that is held in advance, and based on the control flow that is held in advance so that stable waste incineration is performed accordingly. A command signal is sent to the air supply system 12, the grate 11, and the dust supply device 14, and each operation amount such as the amount of air blown in the air supply system 12, the feed speed of the grate 11, and the delivery speed of the dust supply device 14 is set. It is designed to be controlled.

  As described above, in the present embodiment, each manipulated variable is controlled based on the moisture content calculated for the waste P in the low-rise area B, that is, the waste P immediately before being sent to the combustion chamber 13. Therefore, the operating conditions of the waste incinerator can be optimally controlled.

  The waste P supplied to the waste incinerator 1 is processed as follows.

  The waste P in the waste pit 17 is thrown into the hopper 16 by the waste crane 18. The waste P is pushed onto the grate 11 by a dust supply device 14 (pusher) installed in the lower part of the chute 15. The waste P on the grate 11 is burned by the combustion air blown from the air supply system 12 below the grate 11.

  The detection element 20A is provided on the inner surface of the side wall of the low-rise area B of the chute 15 that is provided so as to hang down from the hopper 16, and the capacitance of the waste P of high pressure density in the vicinity of the detection element 20A in the low-rise area B It is measured by the capacitance meter 20. The moisture content calculator 21 calculates the moisture content.

  The controller 22 estimates an accurate calorific value of the waste from the value of the moisture content sent from the moisture content calculator 21 based on the correspondence relation held in advance, and holds it in advance accordingly. Based on the control flow, a command signal is issued so that a stable waste incineration process is performed. This command signal adjusts the feed rate of the dust supply device 14, the feed rate of the grate 11, the operation amount such as the amount of combustion air blown from the air supply system 12 below the grate 11, and the like, resulting in the discarding. The combustion state of the object is controlled.

1 Waste incinerator 15 Chute 16 Input port (hopper)
20 Moisture meter (capacitance meter)
20A Detection element A High-rise area B Low-rise area P Waste

Claims (1)

In a waste incinerator in which a detection element of a moisture meter for measuring the moisture content of waste is provided in a chute extending downward from the waste input port of the waste incinerator for incinerating waste,
The detection element of the moisture meter is arranged in a low-rise area having a higher pressure density than the high-rise area forming the upper part of the waste layer formed by throwing the waste into the chute space ,
The waste incinerator is characterized in that the low-rise area is an area formed below the depth position of 3 m from the upper surface of the waste layer .

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