JP4896565B2 - Dry carbonization system - Google Patents

Description

  The present invention relates to a dry carbonization system that thermally decomposes and carbonizes organic waste such as dewatered sludge.

In a system that dries and carbonizes organic waste such as sludge, the organic waste is put into a pyrolysis furnace and heated in a low-oxygen state to produce combustible dry distillation gas and carbide as pyrolysis gas. It is separated into a certain thermal decomposition residue and discharged. In this case, it is well known to combust the dry distillation gas generated in the carbonization step and use it as a heat source for the pyrolysis furnace in the carbonization step (see, for example, Patent Documents 1 and 2).
JP 2003-183665 A JP 2003-340696 A

  In this case, the amount of carbonized gas generated varies depending on the moisture content or property change of organic waste such as sludge. For this reason, the carbonization process may not be maintained only with the generated dry distillation gas. In such a case, additional cooking with auxiliary fuel is required.

  The purpose of the present invention is to perform carbonization efficiently, and even if the moisture content or properties of organic waste such as sludge changes, almost no additional cooking with auxiliary fuel is required, and carbonization is performed by the generated dry distillation gas. An object of the present invention is to provide an energy efficient dry carbonization system capable of maintaining a process.

The dry carbonization system of the present invention includes a pyrolysis furnace that heats and decomposes input organic waste in a low oxygen state, separates it into pyrolysis gas and pyrolysis residue, and the pyrolysis furnace. A pyrolysis gas from the gas and a supplementary fuel as necessary, combusted together with combustion air, and heating the pyrolysis furnace with the combustion heat, and organic waste introduced into the pyrolysis furnace And a heat exchanger for recovering the thermal energy of the combustion exhaust gas discharged from the heating furnace, and supplying the dryer and the pyrolysis furnace as the heat exchanger provided between the parts, characterized by using a preheater for preheating the dried waste by the dryer combustion exhaust gas discharged as a heat source from the heating furnace.

  In the present invention, the measuring means for measuring the moisture content and input amount of the organic waste to be input, the calorific value, the measuring means for measuring the temperature and flow rate of the auxiliary fuel, and the temperature and flow rate of the pyrolysis gas are measured. Measuring means, measuring means for measuring the temperature and flow rate of combustion air, measuring means for measuring the generation amount and temperature of pyrolysis residue, and measuring means for measuring the temperature and flow rate of combustion exhaust gas are provided, respectively. From the measured values, the total amount of heat stored in the organic waste, auxiliary fuel, pyrolysis gas, and combustion air is obtained as heat input to the carbonization furnace comprising the pyrolysis furnace and the heating furnace, and the pyrolysis gas and pyrolysis residue And the total amount of heat stored in the combustion exhaust gas as the heat output from the carbonization furnace. From the heat balance of these input and output heats, organic waste can be obtained simply by combustion of pyrolysis gas generated without using auxiliary fuel. Of pyrolyzing A calculation device for calculating the relationship between the amount of organic waste input and the water content, and using the measured water content of the organic waste, the input of the organic waste determined by the above calculation device Control that controls the amount of input of organic waste to the amount of input that can pyrolyze organic waste only by combustion of pyrolysis gas generated without using auxiliary fuel, based on the relationship between the amount and moisture content A device may be provided.

  Further, in the present invention, the control device uses the measured value of the amount of input of organic waste, and determines the water content of the organic waste from the relationship between the amount of input of organic waste and the water content determined by the arithmetic device. The rate may be controlled to a moisture content that can pyrolyze organic waste only by combustion of pyrolysis gas generated without using auxiliary fuel.

  Further, in the present invention, the arithmetic unit can thermally decompose organic waste by combustion of pyrolysis gas generated without using auxiliary fuel from the heat balance of heat input to and output from the carbonization furnace. The relationship between the input amount of organic waste and the calorific value is calculated, and the control device uses the calorific value measurement value of the organic waste, and the input amount of organic waste and the calorific value obtained by the above arithmetic unit. Therefore, a configuration may be adopted in which the input amount of organic waste is controlled to an input amount capable of thermally decomposing organic waste only by combustion of pyrolysis gas generated without using auxiliary fuel.

  According to the present invention, high energy efficiency can be obtained by recovering the amount of heat of the combustion exhaust gas for heating generated in the carbonization step. In addition, the relationship between the input amount of organic waste and the moisture content, which decomposes organic waste by simply burning the generated pyrolysis gas without using auxiliary fuel, based on the heat balance of input and output heat. Alternatively, a so-called self-burning operation that does not require auxiliary fuel can be performed by obtaining the relationship between the input amount and the heat generation amount.

  Hereinafter, an embodiment of a dry carbonization system according to the present invention will be described in detail with reference to the drawings.

  First, the embodiment shown in FIG. 1 will be described. In FIG. 1, reference numeral 2 denotes a pyrolysis furnace which is a main component of the present system. Organic waste introduced through a dryer 1 described later is heated and pyrolyzed in a low oxygen state to produce pyrolysis gas (combustible gas). (Distilled gas) 23 and pyrolysis residue (carbide) 13 are separated and discharged. Reference numeral 3 denotes a heating furnace, which introduces the pyrolysis gas 23 and the auxiliary fuel 22 from the pyrolysis furnace 2 and burns them together with the combustion air 24, and heats the pyrolysis furnace 2 with the combustion heat. A combination of the pyrolysis furnace 2 and the heating furnace 3 is called a carbonization furnace 8.

  The dryer 1 heats and dries organic waste put into the pyrolysis furnace 2 and reduces its moisture content. For example, when the organic waste is dehydrated sludge, the sludge 11 before drying generally has a moisture content of about 85%, but by reducing the dryer 1, it becomes a dried sludge 12 with a moisture content of about 50%. 4a is a heat exchanger (in this example, a waste heat boiler), and collects the thermal energy of the combustion exhaust gas discharged from the heating furnace 3. The waste heat boiler 4a used as the heat exchanger introduces water 26 to generate steam 27, and supplies the generated steam as a heat source of the dryer 1. In the dryer 1, steam from the waste heat boiler 4a is supplied to a heating jacket (not shown) to heat and dry the sludge. The vapor 21 generated by this drying is discharged to the outside.

  In the above configuration, the dryer 1 dries organic waste (for example, dehydrated sludge) 11 and separates it into dry waste (dried sludge) 12 and steam 21. The dry waste 12 is put into the pyrolysis furnace 2 and is indirectly heated from the outside by the heating furnace 3 in a low oxygen state and pyrolyzed. As a result, it is separated into pyrolysis residue (carbide) 13 and combustible pyrolysis gas (dry distillation gas) 23. As a fuel for the heating furnace 3, a pyrolysis gas 23 generated in the pyrolysis furnace 2 is used. In addition to this, auxiliary fuel 22 is used as necessary, for example, when the pyrolysis gas 23 alone cannot obtain sufficient combustion at the time of starting up the equipment.

  A waste heat boiler 4a is provided as a heat exchanger that recovers thermal energy from the combustion exhaust gas 25 of the heating furnace 3, and water 26 supplied to the waste heat boiler 4a is converted into steam 27 by the heat of the exhaust gas 25, Supplied to the dryer 1.

  In the present embodiment, the moisture in the organic waste 11 is separated and discharged as the vapor 21 by the dryer 1, so the amount of vapor evaporated in the pyrolysis furnace 2 is reduced accordingly. For this reason, the degree to which the pyrolysis gas 23 generated in the pyrolysis furnace 2 is diluted by evaporation is reduced, and the calorific value is improved. Further, the thermal energy of the combustion exhaust gas 25 from the heater 3 is recovered as steam and can be used as a heat source for the dryer 1.

  Thus, since the calorific value of the pyrolysis gas 23 is improved, the auxiliary fuel 22 is almost unnecessary, and its consumption is greatly reduced. Moreover, since the steam conventionally generated by the external fuel can be covered with the energy of its own exhaust gas, the energy efficiency is improved and the running cost of the dryer 1 can be reduced.

  Next, the embodiment shown in FIG. 2 will be described. In addition, the same code | symbol is attached | subjected to the part same as the structure shown in FIG. 1, and the overlapping description is abbreviate | omitted.

  In this embodiment, the air heat exchanger 4b is used as a heat exchanger that recovers energy from the combustion exhaust gas 25 of the heating furnace 3. The air heat exchanger 4b is used as a preheater for the combustion air 24, and the air 28 supplied to the air preheater 4b is converted into high-temperature air 29 by the heat of the exhaust gas 25, and the combustion air for the heating furnace 3 is used. 24 is supplied.

  In this embodiment, the thermal energy of the combustion exhaust gas 25 is recovered as sensible heat, and the heat input to the heating furnace 3 increases. That is, since the amount of sensible heat of high-temperature air and heat input to the heating furnace 3 are increased, the consumption of the pyrolysis gas 23 can be reduced. Therefore, the self-combustible operation range in which only the generated pyrolysis gas 23 is carbonized as fuel without using the auxiliary fuel 22 is expanded.

  Next, the embodiment shown in FIG. 3 will be described. Also here, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted.

  In this embodiment, a preheater 4c for preheating dry waste 12 is used as a heat exchanger for recovering energy from the combustion exhaust gas 25 of the heating furnace 3, and this is provided in the front stage of the pyrolysis furnace 2. That is, the dry waste dried by the dryer 1 is heated by the heat of the exhaust gas 25 by the preheater 4c, and moisture is further reduced.

  In this embodiment, the moisture content of the dried sludge supplied to the pyrolysis furnace 2 is further reduced. As described above, since the moisture content of the dry waste is further reduced, a self-combustible operation range in which only the pyrolysis gas 23 generated without using the auxiliary fuel 22 is carbonized as fuel is expanded.

  Moreover, although not shown in figure, generally the sedimentation process of the organic waste 11 is provided in the front | former stage of the dryer 1. FIG. Therefore, all or part of the combustion exhaust gas discharged from the heating furnace 2 is added as a heating source to the sedimentation process, so that sedimentation is improved by a hydrothermal reaction, and the moisture content of the organic waste 11 is reduced in advance. Also good.

  Also in this case, since the moisture content of the dried sludge supplied to the pyrolysis furnace 2 is reduced, the self-combustion operable region in which only the pyrolysis gas 23 generated without using the auxiliary fuel 22 is carbonized is expanded.

  Next, the embodiment shown in FIGS. 4 to 6 will be described. In addition, the same code | symbol is attached | subjected to the part same as FIG.1, 2,3 here, and the overlapping description is abbreviate | omitted.

  This embodiment relates to the above-described self-combustion operation of the carbonization furnace 8. In FIG. 4, the pyrolysis furnace 2 has a supply device 5 capable of adjusting the input amount of the dry waste 12 at the inlet portion (the left end portion in the drawing). In addition, a residue discharge device 7 that conveys the pyrolysis residue 13 discharged from the pyrolysis furnace 2 is provided on the outlet side (the right side in the figure).

  The heating furnace 3 is provided with a burner 6 for combustion. The burner 6 is configured to be able to supply, as fuel, auxiliary fuel 22 such as pyrolysis gas 23 and propane gas generated in the pyrolysis furnace 2, and further combustion air 24.

  Measuring means 101 for measuring the moisture content, input amount, and calorific value of the dry waste 12 input into the pyrolysis furnace 2 is provided. The pyrolysis furnace 2 is provided with a measuring means 102 for measuring the temperature inside. The heating furnace 3 is also provided with measuring means 103 that measures the temperature inside. Furthermore, the measuring means 106 for measuring the generation amount and temperature of the pyrolysis residue 13, the measuring means 107 for measuring the temperature and flow rate of the pyrolysis gas 23 generated in the pyrolysis furnace 2, and the temperature and flow rate of the auxiliary fuel 22 are measured. Measuring means 108 and measuring means 109 for measuring the temperature and flow rate of the combustion air 24 are provided.

  Reference numeral 104 denotes an arithmetic unit which calculates the energy balance of the plant (carbonization system 8) from the operation data measured and collected by the above-described measuring means. A control device 105 controls the plant based on data from the arithmetic device 104. These calculation and control functions will be described below.

  The heat input to the carbonization furnace 8 shown in FIG. 4 is the sum of the amount of heat held by the dry waste 12, the auxiliary fuel 22, the pyrolysis gas 23, and the combustion air 24, and is collected by the measuring means 101, 107, 108, 109. Calculation is performed by the arithmetic unit 104 based on the data. On the other hand, the heat output from the carbonization furnace 8 is the total amount of heat stored in the pyrolysis gas 23, pyrolysis residue 13, and exhaust gas 25, and is calculated by the arithmetic unit 104 based on data collected by the measuring means 102, 106, and 107. Calculated. Then, from the heat balance of the heat input and output heat, the dry waste 12 that can pyrolyze (self-combust) the dry waste 12 only by burning the pyrolysis gas 23 generated without using the auxiliary fuel 22 is input. The calculation device 104 calculates the relationship between the amount and the moisture content, or the relationship between the amount of the dry waste 12 input and the calorific value.

  FIG. 5 is a diagram showing the relationship between the input amount of the dry waste 12 and the water content within a range where self-combustion is possible. In other words, the illustrated curve is obtained by plotting the minimum input amount that can be combusted under a certain moisture content for the input dry waste 12 by the balance calculation based on the heat balance described above. Therefore, the dry waste 12 can be pyrolyzed by the self-combustion without the auxiliary fuel 22 at the input amount above this curve. As is clear from FIG. 5, if the moisture content of the dry waste 12 put into the pyrolysis furnace 2 is low, it can be self-combusted even if the amount is small, but if the moisture content is high, a lot of drying is performed. This means that if you do not increase the amount of pyrolysis gas generated by adding waste, you cannot burn yourself.

  Therefore, by using the relationship between the input amount and the water content described above, the input amount of the dry waste 12 necessary for self-combustion is calculated by the arithmetic unit 104 from the water content of the dry waste 12 measured by the measuring means 101, and controlled. The supply amount can be adjusted so as to be within the self-combustion range by controlling the supply device 5 with the device 105. Conversely, the input amount of the dry waste 12 is measured by the measuring means 101, and the moisture content of the dry waste 12 necessary for self-combustion is calculated by the arithmetic unit 104 from the input amount of the dry waste 12, and the control device By controlling the operation of the dryer 1 at 105, the moisture content of the dry waste 12 can be adjusted so that it falls within the self-combustion range.

  FIG. 6 is a diagram showing the relationship between the input amount of the dry waste 12 and the calorific value within a range where self-combustion is possible. In other words, by the balance calculation based on the heat balance described above, the minimum input amount capable of self-combustion with respect to the calorific value of the dry waste 12 to be input is obtained, and plotted is the illustrated curve. Therefore, the dry waste 12 can be pyrolyzed by the self-combustion without the auxiliary fuel 22 at the input amount above this curve. As is apparent from FIG. 6, if the amount of heat generated by the dry waste 12 put into the pyrolysis furnace 2 is low, even if a large amount of dry waste 12 is put in, it is difficult to self-combust. However, when the calorific value is high, a large amount of heat is generated even if the input amount of the dry waste 12 is small, so that the dry waste 12 can be pyrolyzed naturally without requiring the auxiliary fuel 22.

  The calorific value of the dry waste 12 can be obtained from the composition of the dry waste 12 or the like, and can be measured online by the measuring means 101. Therefore, using the relationship between the input amount and the calorific value shown in FIG. 6, the input amount of the dry waste 12 necessary for self-combustion is calculated by the arithmetic unit 104 from the calorific value of the dry waste 12 measured by the measuring means 101. Then, the control device 105 can control the supply device 5 to adjust the input amount so as to be within the self-combustion range.

  If each measurement value is calculated and controlled based on this, even if the moisture content, input amount, and calorific value of the dry waste fluctuate, the plant state can be maintained within the self-combustion range following it. , Running costs can be reduced.

  In FIG. 4, when the air supply device 9 is provided in the supply device 5 into the pyrolysis furnace 2 so as to adjust the amount of air introduced into the pyrolysis furnace 2, oxygen in the pyrolysis furnace 2 is obtained. Since the concentration can be controlled, the combustion ratio of combustible materials such as carbon in the dry waste in the pyrolysis furnace 2 can be adjusted, and the properties of the pyrolysis residue 13 can be controlled. Therefore, the carbon and ash content can be adjusted according to the recycling application of the pyrolysis residue (carbide) 13.

It is a block block diagram which shows one Embodiment of the dry carbonization system by this invention. It is a block block diagram which shows other embodiment of the dry carbonization system by this invention. It is a block block diagram which shows other one Embodiment of the dry carbonization system by this invention. It is a block block diagram which shows the calculation and control part in one Embodiment of the dry carbonization system by this invention. It is a characteristic view showing the relationship between the input amount which can be combusted, and the moisture content of the dry waste calculated | required by the system of FIG. FIG. 5 is a characteristic diagram showing the relationship between the amount of heat that can be combusted and the calorific value of dry waste determined by the system of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dryer 2 Pyrolysis furnace 3 Heating furnace 4 Heat exchanger 4a Waste heat boiler 4b Air heat exchanger 4c Preheater 8 Carbonization furnace 12 Dry waste 13 Pyrolysis residue (carbide)
DESCRIPTION OF SYMBOLS 22 Auxiliary fuel 23 Pyrolysis gas 24 Combustion air 25 Combustion exhaust gas 101,102,103,106,107,108,109 Measuring means 104 Arithmetic unit 105 Control apparatus

Claims (4)

A pyrolysis furnace that heats and decomposes the input organic waste in a low oxygen state, separates it into pyrolysis gas and pyrolysis residue, and discharges it,
A heating furnace that introduces pyrolysis gas from the pyrolysis furnace and, if necessary, auxiliary fuel and burns it with combustion air, and heats the pyrolysis furnace with the combustion heat;
A dryer for reducing the water content by heating the organic waste charged into the pyrolysis furnace;
A heat exchanger that recovers the thermal energy of the combustion exhaust gas discharged from the heating furnace ,
As the heat exchanger, a preheater that is provided between the dryer and the input portion of the pyrolysis furnace and preheats the waste dried by the dryer using the combustion exhaust gas discharged from the heating furnace as a heat source is used. Inui燥炭system shall be the feature. Measuring means for measuring moisture content, input amount, calorific value of input organic waste, measuring means for measuring auxiliary fuel temperature and flow rate, measuring means for measuring pyrolysis gas temperature and flow rate, combustion air A measuring means for measuring the temperature and flow rate of the gas, a measuring means for measuring the generation amount and temperature of the pyrolysis residue, and a measuring means for measuring the temperature and flow rate of the combustion exhaust gas,
From the measurement values obtained by these measuring means, the total amount of heat held by the organic waste, auxiliary fuel, pyrolysis gas, and combustion air is obtained as heat input to the carbonization furnace comprising the pyrolysis furnace and the heating furnace, and the pyrolysis gas Then, the total amount of retained heat of the pyrolysis residue and combustion exhaust gas is obtained as the heat output from the carbonization furnace, and from the heat balance of these input heat and output heat, only combustion of the pyrolysis gas generated without using auxiliary fuel An arithmetic unit is provided to calculate the relationship between the amount of organic waste that can be thermally decomposed and the water content,
Further, using the measured value of the moisture content of the organic waste, the input amount of the organic waste is calculated using the auxiliary fuel from the relationship between the amount of the organic waste input and the moisture content obtained by the arithmetic unit. 2. The dry carbonization system according to claim 1, wherein a control device is provided for controlling the input amount so that the organic waste can be pyrolyzed only by combustion of the pyrolysis gas generated without any problem. Measuring means for measuring moisture content, input amount, calorific value of input organic waste, measuring means for measuring auxiliary fuel temperature and flow rate, measuring means for measuring pyrolysis gas temperature and flow rate, combustion air A measuring means for measuring the temperature and flow rate of the gas, a measuring means for measuring the generation amount and temperature of the pyrolysis residue, and a measuring means for measuring the temperature and flow rate of the combustion exhaust gas,
From the measured values obtained by these measuring means, the total amount of heat held by the organic waste, auxiliary fuel, pyrolysis gas, and combustion air is obtained as heat input to a carbonization furnace comprising a pyrolysis furnace and a heating furnace, and the pyrolysis is performed. Only the combustion of pyrolysis gas generated without using auxiliary fuel is obtained from the heat balance of the heat input and output heat from the sum of the retained heat quantity of gas, pyrolysis residue, and combustion exhaust gas as the heat output from the carbonization furnace. An arithmetic unit is provided that calculates the relationship between the amount of organic waste that can be pyrolyzed and the water content,
Further, using the measured value of the amount of input of organic waste, and using the relationship between the amount of input of organic waste and the water content determined by the arithmetic unit, the water content of organic waste is used as auxiliary fuel. 2. The dry carbonization system according to claim 1, further comprising a control device that controls the moisture content so that the organic waste can be pyrolyzed only by combustion of the pyrolysis gas generated without any problem. Measuring means for measuring moisture content, input amount, calorific value of input organic waste, measuring means for measuring auxiliary fuel temperature and flow rate, measuring means for measuring pyrolysis gas temperature and flow rate, combustion air A measuring means for measuring the temperature and flow rate of the gas, a measuring means for measuring the generation amount and temperature of the pyrolysis residue, and a measuring means for measuring the temperature and flow rate of the combustion exhaust gas,
From the measured values obtained by these measuring means, the total amount of heat held by the organic waste, auxiliary fuel, pyrolysis gas, and combustion air is obtained as heat input to a carbonization furnace comprising a pyrolysis furnace and a heating furnace, and the pyrolysis is performed. Only the combustion of pyrolysis gas generated without using auxiliary fuel is obtained from the heat balance of the heat input and output heat from the sum of the retained heat quantity of gas, pyrolysis residue, and combustion exhaust gas as the heat output from the carbonization furnace. An arithmetic unit that calculates the relationship between the amount of organic waste that can be thermally decomposed and the amount of heat generated can be provided.
Furthermore, using the measured value of the calorific value of the organic waste, the input amount of the organic waste is used as auxiliary fuel from the relationship between the calorific value of the organic waste and the calorific value obtained by the arithmetic unit. 2. The dry carbonization system according to claim 1, wherein a control device is provided for controlling the input amount so that the organic waste can be pyrolyzed only by combustion of the pyrolysis gas generated without any problem.

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