JP2005139338A - Method for measuring temperature in combustion zone of moving bed gasifier and waste gasifier - Google Patents

Abstract

[PROBLEMS] To stabilize gasification of waste.
SOLUTION: A waste is put into a vertical gasification furnace 1 to form a packed bed, and an oxidant gas is supplied from below the packed bed to form a combustion zone 31 and a thermal decomposition zone 33 by partial combustion. The maximum temperature in the combustion zone can be detected by sequentially forming and changing the extraction amount of the combustion residue extracted from the bottom of the furnace and measuring the temperature change at a predetermined furnace height position (20 to 23).
[Selection] Figure 1

Description

  The present invention relates to a temperature measurement method for a combustion zone in a moving bed gasification furnace for waste and a waste gasification apparatus to which the method is applied.

  As a method for treating waste, the waste is put into a gasification furnace to form a packed bed, and an oxidant gas is supplied from the bottom to cause partial combustion, and the combustion zone, pyrolysis zone, and drying zone in the furnace height direction. There has been proposed a moving bed type gasification furnace that gasifies waste by forming (see, for example, Patent Document 1). According to this, the waste in the drying zone can be dried by the heat of the pyrolysis gas generated in the pyrolysis zone. In addition, since the fly ash contained in the pyrolysis gas is removed in the process in which the pyrolysis gas rises in the drying zone, a relatively clean pyrolysis gas can be obtained.

Special Table 2000-517409

  However, the above technique does not give consideration to the temperature measurement method of the combustion zone that can move in the furnace height direction, and there is a problem that the combustion zone temperature cannot be accurately measured.

  Here, regarding the combustion zone temperature of the waste, in the moving bed type gasification furnace, the pyrolysis zone is heated by the combustion heat of the combustion zone and generates pyrolysis gas. In consideration, for example, the temperature is controlled in a high temperature range of about 1000 ° C. or higher. In this case, in particular, it is necessary to control the temperature by detecting the maximum temperature of the combustion zone.

  Therefore, as a method of measuring the maximum temperature of the combustion zone, a method of directly or indirectly detecting the temperature by arranging a plurality of temperature sensors in the height direction of the gasification furnace is conceivable. However, since the thickness of the combustion zone is generally thinner than the total thickness of the packed bed, for example, if the highest temperature position of the combustion zone exists between the temperature sensors, there is a problem that the temperature cannot be measured accurately. Moreover, the installation quantity of a temperature sensor increases and becomes uneconomical.

  This invention makes it a subject to detect the maximum temperature of a combustion zone.

  In order to solve the above-mentioned problems, the present invention is to introduce waste into a vertical gasification furnace to form a packed bed, and to supply an oxidant gas from below the packed bed to generate a combustion zone and heat generated by partial combustion. The decomposition zone is formed in sequence, the amount of combustion residue extracted from the bottom of the furnace is changed, the temperature change at a predetermined furnace height position is measured, and the maximum temperature of the combustion zone is detected.

  That is, the present invention is characterized in that the maximum temperature of the combustion zone is detected by utilizing the fact that the combustion zone moves upward when extraction of the combustion residue is stopped and the combustion zone moves downward when extraction is performed. To do. That is, the maximum temperature of the combustion zone can be detected by measuring the temperature change at the furnace height position through which the combustion zone passes and detecting the peak of the temperature change.

  In this way, by repeatedly extracting and stopping combustion residue from the packed bed from the bottom, the combustion zone repeatedly passes through the predetermined furnace height position where the temperature sensor is provided, so the maximum temperature of the combustion zone is continuously detected. can do. Further, by adjusting the supply amount of the oxidant gas based on the detected maximum temperature, fluctuations in the combustion zone temperature can be reduced, and gasification efficiency can be stabilized.

  The waste gasifier of the present invention supplies an oxidant gas from below to a vertical gasifier having an inlet at the top of the furnace and a packed bed of waste in the gasifier. Thus, an oxidizing agent supply means for sequentially forming a combustion zone and a thermal decomposition zone by partial combustion, a discharge port for a product gas provided above the gasification furnace, and a temperature for detecting a temperature change at a predetermined furnace height position of the packed bed A sensor, an extractor for extracting combustion residue from the bottom of the gasification furnace, and a temperature measuring means for determining the maximum temperature of the combustion zone by controlling the extraction amount of the extractor based on the temperature detected by the temperature sensor To achieve.

  In this case, the oxidant supply means preferably controls the supply amount of the oxidant gas based on the maximum temperature of the combustion zone obtained by the temperature measurement means. Further, the temperature measuring means starts or stops extracting the combustion residue after detecting the peak of the change in the detected temperature.

  ADVANTAGE OF THE INVENTION According to this invention, the combustion zone maximum temperature of a moving bed type gasifier can be detected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a main part of a moving bed type waste gasification apparatus to which the waste gasification method of the present invention is applied. Here, although the waste gasification apparatus of this embodiment is used suitably for gasification of a general waste, an industrial waste, biomass, etc., it is not limited to this.

  As shown in the figure, the waste gasifier of this embodiment (hereinafter simply referred to as a gasifier) is configured to put waste on the top of a container 3 of a gasification furnace 1 formed in a cylindrical vertical shape. A hopper 5 for storage is provided, and waste material cut out from the hopper 5 is conveyed by, for example, a screw conveyor 7 and is supplied into the container 3 from an inlet 9.

  The gasification furnace 1 has a discharge port 11 for discharging a generated gas (pyrolysis gas) on the top side wall, and a combustion oxidant gas (such as air or oxygen) and a water gasifying agent (such as water vapor) at the bottom. The gasifying agent supply port 13 is provided. The gasifying agent supply port 13 is formed, for example, at the tip of the rotary shaft 17 of the rotary extractor 15 that forms the bottom of the gasification furnace 1, and is supplied from the gas supply line through the rotary shaft 17. Oxidant gas and water vapor are supplied into the gasification furnace 1, for example, radially. The rotary shaft 17 of the rotary extractor 15 is connected to a motor 18, and when the rotary shaft 17 rotates, the rotary blades of the rotary extractor 15 extract the combustion residue etc. of waste in the radial direction and discharge it from the discharge port 19. It is supposed to be. The gasifying agent supply port 13 is not limited to the present embodiment as long as the oxidizing agent gas and the water vapor are uniformly supplied in the cross-sectional direction of the gasification furnace 1.

  Further, on the side wall of the vessel 3, temperature sensors 20 to 23 are arranged in four stages at equal intervals in the furnace height direction, for example. That is, by arranging a plurality of temperature sensors in a predetermined range in the furnace height direction and measuring the temperature over time, a time change in temperature is detected in each temperature sensor, and the peak temperature from the change point of the temperature gradient, That is, the maximum temperature of the packed bed can be read. In the present embodiment, the peak temperature is calculated from the detected temperature by a control device (not shown). A plurality of temperature sensors may be arranged in the circumferential direction at the same height position of the gasification furnace 1.

  Further, based on the maximum temperature of the packed bed, the amounts of the oxidant gas and the water gasifying agent supplied into the furnace from the gasifying agent supply port 13 are adjusted, and the rotary type is adjusted based on the highest temperature furnace height position. The rotation speed of the motor 18 of the extractor 15 is controlled.

  Next, operation | movement of the gasification apparatus of this embodiment is demonstrated. First, the crushed waste is appropriately dried and continuously fed into the gasifier 1 from the inlet 9. Waste introduced into the gasification furnace 1 is filled into the furnace from the bottom to form a packed bed. The amount of waste input is adjusted so that a space is formed at the top of the gasification furnace 1 at least.

  In this way, the oxidant gas is supplied from the gasification agent supply port 13 to the gasification furnace 1 filled with waste, and high-temperature air (for example, 400 ° C. or higher) is supplied from a hot air generator for ignition (not shown). Ignite by blowing. Then, the supply amount of the oxidant gas is adjusted, and a combustion zone is formed mainly by partially burning only the waste at the bottom of the furnace. The upper-layer waste is pyrolyzed by the combustion heat in the combustion zone, and the generated pyrolysis gas rises in the furnace through the gap between the filled waste and is discharged from the discharge port 11.

In a steady state where the partial combustion and thermal decomposition of the waste are stable, a stable combustion zone 31 is formed in the vicinity of the bottom of the furnace, a thermal decomposition zone 33 is formed on the upper portion, and a waste drying zone 35 is further formed on the upper portion. Is formed. For example, when the waste reaches about 300 ° C. or more, it is thermally decomposed, so that the region of the waste packed layer that exceeds the temperature region becomes the thermal decomposition zone 33. In the pyrolysis zone 33, the waste is pyrolyzed to generate combustible pyrolysis gas and carbon (char) and non-flammable pyrolysis residue. The char generated here flows down to the combustion zone 31 and burns, and the temperature of the combustion zone 31 becomes about 1000 ° C. or higher. Further, a part of the char generated in the thermal decomposition zone 33 reacts with the water gasifying agent supplied from the gasifying agent supply port 13 to generate CO and H ₂ .

  The product gas obtained by mixing the pyrolysis gas and the water gas generated in this way forms a drying zone 35 for drying the waste while flowing through the gap between the upper wastes, thereby reducing the temperature. (For example, about 200 ° C.) and discharged from the discharge port 11 at the top of the gasification furnace 1. Further, even if fly ash generated in the combustion zone 31 is accompanied by the product gas, the waste layer filled in the dry zone 35 is collected as a filter and the fly ash flowing out from the discharge port 11 is collected. The amount can be reduced.

  On the other hand, the waste dried in the drying zone 35 gradually moves to the thermal decomposition zone 33 and undergoes thermal decomposition treatment, and then moves to the combustion zone 31 to be pyrolyzed and burned to become ash. These flow down the cooling zone 37 formed in the lower layer of the combustion zone 31, and are sent to the discharge port 19 by the rotary extractor 15 and discharged outside the furnace. In addition, ash, incombustibles, incombustible pellets, etc. discharged outside the furnace are separated.

  By the way, since waste contains various combustibles, the calorific value fluctuates and the temperature of the combustion zone 31 may fluctuate. Since this combustion zone 31 is set in a temperature range that takes into account waste gasification depending on the supply amount of the oxidant gas, etc., for example, if the heat generation amount decreases and the combustion temperature decreases, the gasification efficiency decreases. On the contrary, if the calorific value increases and the combustion temperature increases, the ash may be melted. That is, if the combustion zone temperature is outside the set temperature range, the waste gasification efficiency becomes unstable.

  Therefore, during the operation of the gasification furnace 1, it is desirable to measure the maximum temperature of the combustion zone 31 as continuously as possible, and to respond early when an abnormal temperature is detected. However, for example, when the extraction from the bottom of the furnace is stopped, the combustion zone 31 moves upward while forming the combustion residue in the lower layer together with the combustion of the waste, so the amount of extraction is adjusted and the furnace height of the combustion zone 31 is adjusted. When the temperature of the combustion zone 31 is constantly measured while maintaining the position, there is a problem that the control becomes complicated. In addition, since the thickness of the combustion zone 31 is generally smaller than the total thickness of the packed bed, even if a plurality of temperature sensors are provided in the furnace height direction, the maximum temperature position may be sandwiched between the temperature sensors. It becomes difficult to determine whether or not the detected temperature is the maximum temperature.

  Therefore, in the present embodiment, the temperature sensors 20 to 23 are arranged in a plurality of stages in a predetermined range in the furnace height direction, and the operation of the rotary extractor 15 is controlled to move the combustion zone 31 within the range. The maximum temperature and its position are specified.

  FIG. 2 is a diagram showing the results of each temperature sensor 20-23 measuring the temperature change of the packed bed. In the figure, the horizontal axis represents time, the vertical axis represents temperature, and T1 to T4 correspond to the temperature sensors 20 to 23, respectively. As shown in the figure, each time change of the temperature detected by each temperature sensor shows a mountain-shaped curve, and the maximum temperature can be detected from the changing point of the temperature gradient. Moreover, when the peak positions of the temperature sensors 20 to 23 arranged at equal intervals in the furnace height direction are compared, it can be seen that the maximum temperature position is gradually moved upward with time. Incidentally, since the peaks of the temperature sensors are connected by a substantially straight line (dotted line in the figure), it can be seen that the combustion zone 31 moves upward at a constant speed.

  According to the present embodiment, the plurality of temperature sensors 20 to 23 each measure a change in temperature over a predetermined range in the furnace height direction, and the control device performs arithmetic processing based on the obtained result. A peak is detected and the maximum temperature and its furnace height location are identified. In this case, by appropriately adjusting the sampling interval in consideration of variations in the detected temperature, the peak position that becomes the changing point of the temperature gradient can be accurately read.

  In the present embodiment, the amount of combustion residue extracted from the bottom is controlled in order to maintain the maximum temperature position within a predetermined furnace height range. Specifically, first, the combustion zone 31 is moved upward in a state where the rotary extractor 15 is stopped, and after the temperature detected by the uppermost temperature sensor 23 increases, the temperature starts to decrease, and after a predetermined time has elapsed. Then, the rotary extractor 15 is operated. Then, the combustion zone 31 moves downward, starts decreasing after the temperature detected by the lowest temperature sensor 20 increases, and after a predetermined time has elapsed, the rotary extractor 15 is stopped. In this case, the peak detection accuracy is improved by operating the rotary extractor 15 after waiting for a predetermined time after detecting a change in temperature gradient.

  By repeatedly performing such control and intermittently operating the rotary extractor 15 so that the combustion zone 31 repeatedly passes through the furnace height range of the temperature sensors 20 to 23, the maximum temperature of the combustion zone 31 is continuously measured. can do. Here, the furnace height range in which the temperature sensors 20 to 23 are arranged is determined based on the height of the packed bed, gasification efficiency, and the like.

  As described above, according to the present embodiment, the extraction amount of the combustion residue is changed to move the furnace height position of the combustion zone 31, and the temperature at the furnace height position through which the combustion zone 31 passes is measured over time. Thus, the maximum temperature of the combustion zone 31 can be detected. Then, if necessary, the temperature of the combustion zone 31 is stabilized by adjusting the oxidant supply amount and the like based on the detected temperature, and the gasification efficiency can be improved and stabilized. Moreover, the maximum temperature can be continuously detected by detecting the maximum temperature position and controlling the position within a predetermined furnace height range.

  In this embodiment, an example in which a plurality of temperature sensors are provided in the furnace height direction has been described. However, in order to detect the maximum temperature, basically only one temperature sensor is required. In this case, when one temperature sensor detects a peak, it is possible to perform continuous temperature management by controlling to start or stop extracting combustion residues.

It is a block diagram which shows a part of moving bed type waste gasification apparatus which applies the waste gasification method of this invention. It is a diagram which shows the result of which each temperature sensor arrange | positioned in the furnace height direction measured the temperature change of a packed bed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification furnace 9 Input port 13 Gasifying agent supply port 15 Rotary extraction machine 18 Motor 19 Discharge port 20, 21, 22, 23 Temperature sensor 31 Combustion zone 33 Pyrolysis zone

Claims (5)

Waste is put into a vertical gasification furnace to form a packed bed, and an oxidant gas is supplied from below the packed bed to sequentially form a combustion zone and a pyrolysis zone by partial combustion. A method for measuring a temperature in a combustion zone of a moving bed type gasification furnace, wherein a temperature change at a predetermined furnace height is measured by changing an amount of extraction of a combustion residue extracted from a combustion chamber to detect a maximum temperature of the combustion zone . A vertical gasification furnace having an inlet into which waste is introduced at the top of the furnace, a combustion zone by partial combustion by supplying an oxidant gas from below into the waste packed bed in the gasification furnace, and Oxidant supply means for sequentially forming a pyrolysis zone, a product gas outlet provided above the gasification furnace, a temperature sensor for detecting a temperature change at a predetermined furnace height of the packed bed, and the gasification Disposal comprising an extractor for extracting combustion residues from the bottom of the furnace, and a temperature measuring means for determining the maximum temperature of the combustion zone by controlling the extraction amount of the extractor based on the temperature detected by the temperature sensor Product gasifier. 3. The waste gasifier according to claim 2, wherein the oxidant supply means controls the supply amount of the oxidant gas based on the maximum temperature of the combustion zone obtained by the temperature measurement means. . 4. The waste gasification apparatus according to claim 2, wherein the temperature measuring unit starts or stops extracting the combustion residue when detecting the peak of the detected temperature. 5. A plurality of the temperature sensors are arranged in the furnace height direction of the packed bed, and the temperature measuring means starts extracting the combustion residue when the detected temperature of the temperature sensor at a high position detects a peak, and the combustion residue 4. The waste gasification apparatus according to claim 2, wherein when the detected temperature of the temperature sensor at a low position is detected during the extraction of the fuel, the extraction of the combustion residue is stopped. 5.

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