JP2016190238A - Method for preventing clogging of incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for effectively preventing clogging of an incinerator, based on an evaluation result which effectively evaluates the risk of clogging of the incinerator when incinerating sewage sludges.SOLUTION: A method for preventing clogging of an incinerator prevents clogging of the incinerator for incinerating sewage sludges. The method for preventing clogging of the incinerator includes: a reference color specifying step of specifying an incineration ash color corresponding to a clogging inhibition indication which determines that there is needed the addition of an adhesion preventing agent containing prescribed metallic elements for preventing ash adhesion to the incinerator; an incineration ash color specifying step of detecting the color of incineration ash discharged from the incinerator with a color sensor; an addition determining step of determining whether a color notified from the color sensor is higher in phosphorus concentration or lower in an indication value than the reference color or not, by comparing the previously specified reference color in the reference color specifying step to the color of incineration ash notified from the color sensor; and an addition step of adding an adhesion preventing agent to sewage sludges according to the determination result in the addition determining step.SELECTED DRAWING: None

Description

  The present invention relates to an incinerator blockage prevention method for preventing blockage of an incinerator based on evaluation by an incinerator blockage risk evaluation method for evaluating the risk of blockage in an incinerator for incinerating sewage sludge.

  Conventionally, sewage sludge generated when purifying sewage at a sewage treatment plant is dehydrated and then incinerated in an incinerator. In incinerators that incinerate sewage sludge, incineration ash adheres to the exhaust gas ducts, fluidized sand, heat exchangers, etc. of the incinerators, and in some cases clogs the exhaust gas ducts, which may hinder the operation of the incinerator. There is a risk of coming.

As a method for predicting the adhesion of ash in such an incinerator, for example, Fe ₂ O ₃ , CaO, Na ₂ O, K ₂ O, MgO, and SiO ₂ in incinerated ash obtained by incineration in an oxidizing atmosphere are used. , Al ₂ O ₃ , TiO ₂ , and P ₂ O ₅ , the content of each component is specified, and based on the composition of each specified incineration ash component, a technique for calculating an index by a specific formula is disclosed (See Patent Document 1).

JP 2010-12425 A

  The technique of Patent Document 1 is an index used for one of the methods for predicting ash adhesion, but the mechanism of ash adhesion and incinerator blockage is not fully understood, and ash adhesion and incineration are not known. There is a need to find additional indicators that can assess the risk of furnace blockage.

  The present invention has been made in view of the above problems, and its purpose is to effectively block the incinerator based on the evaluation result for effectively evaluating the risk of the incinerator clogging when incinerating sewage sludge. Provide technology that can be prevented.

  In order to achieve the above object, the present invention investigates and analyzes the relationship between the concentration and adhesion of phosphorus and the effect of adhesion to the incinerator when incinerating sewage sludge in an incinerator to determine the concentration of phosphorus in sewage sludge. Among the metal elements contained in sewage sludge, the relationship between the melting point of the compound with phosphorus and the metal element concentration higher than the combustion temperature of the incinerator is found to be strongly related to the blockage of the incinerator. It was made paying attention to.

  An incinerator clogging prevention method according to one aspect of the present invention is an incinerator clogging prevention method for preventing clogging of an incinerator that incinerates sewage sludge, and is a predetermined metal element for preventing ash adhesion to the incinerator. A reference color specifying step for specifying the color of the incineration ash corresponding to the blockage suppression index determined to require the addition of an anti-adhesion agent containing the color, and the color sensor detects the color of the incineration ash discharged from the incinerator The incineration gray specifying step, the reference color specified in advance by the reference color specifying step, and the color of the incineration ash notified from the color sensor are compared, and the color notified from the color sensor has a phosphorous concentration higher than the reference color. The addition determination step for determining whether the color is high or the index value is low, and the addition step for adding the anti-adhesion agent to the sewage sludge according to the determination result of the addition determination step And have .

  An incinerator blockage prevention method according to an aspect of the present invention is an incinerator blockage prevention method for preventing blockage of an incinerator that incinerates sewage sludge, which is included in the sewage sludge and is higher than the combustion temperature of the incinerator. A bindable amount identification step for identifying a bindable amount, which is the amount of phosphorus that can be bound by a high melting point metal element that is capable of forming a high melting point phosphorus compound, and an amount of phosphorus contained in sewage sludge. An inclusion amount identification step for identifying a certain inclusion amount, an evaluation indicator calculation step for calculating an evaluation indicator that is a ratio of the inclusion amount and the inclusion amount, and ash adhesion to the incinerator are prevented based on the evaluation indicator. In accordance with an addition determination step for determining whether or not to add an anti-adhesion agent containing a predetermined metal element to the sewage sludge and the determination result of the addition determination step, the anti-adhesion agent is added to the sewage sludge Addition step and Having. Here, in the bindable amount specifying step, the mass ratio of a predetermined compound containing a refractory metal element contained in the incineration ash incinerated sewage sludge by an incinerator is analyzed, and the bondable amount is determined based on the mass ratio. In the inclusion amount specifying step, the mass ratio of the phosphorus compound contained in the incinerated ash incinerated sewage sludge by the incinerator is analyzed, and the inclusion amount is specified based on the mass ratio.

  In the incinerator blockage prevention method according to another aspect of the present invention, the sewage treatment plant that has discharged sewage sludge includes a first sedimentation basin that performs sewage precipitation treatment, and a living organism that treats water that has passed through the first sedimentation basin. A reaction tank and a second sedimentation basin that performs a precipitation treatment on the water that has passed through the biological reaction tank, and a total phosphorus amount contained in the water flowing into the first sedimentation basin in the above-described inclusion amount specifying step; The amount of inclusion is specified based on the total amount of phosphorus contained in the water flowing out of the settling basin.

  An incinerator clogging risk evaluation method according to another aspect is an incinerator clogging risk evaluation method for evaluating clogging risk of an incinerator that incinerates sewage sludge, and is included in the sewage sludge, and the combustion temperature of the incinerator A bindable amount specifying step for specifying a bondable amount, which is an amount of phosphorus that can be bound by a high melting point metal element that is a plurality of metal elements capable of forming a phosphorus compound having a higher melting point, and a step of determining the amount of phosphorus contained in sewage sludge You may have the inclusion amount specific step which specifies the inclusion amount which is quantity, and the evaluation parameter | index calculation step which calculates the evaluation parameter | index which is a ratio of the amount that can be combined and the inclusion amount. In the incinerator blockage risk evaluation method according to another aspect, the plurality of refractory metal elements may include Al, Fe, Ca, and Mg.

  In the incinerator blockage risk evaluation method according to another aspect, in the bindable amount specifying step, the mass ratio of a predetermined compound containing a refractory metal element contained in the incineration ash incinerated sewage sludge by the incinerator is calculated. Analyze and identify the amount that can be combined based on the mass proportion, and in the inclusion amount identification step, analyze the mass proportion of the phosphorus compound contained in the incineration ash incinerated sewage sludge in the incinerator, and calculate the mass proportion. Based on this, the inclusion amount may be specified.

  The incinerator blockage prevention method according to another aspect specifies the color of the incineration ash of each sewage sludge discharged from the sewage treatment plant at a plurality of time points by a predetermined incinerator, and the sewage sludge for each sewage sludge. Bindable amount that is the amount of phosphorus that can be combined with high melting point metal elements, which are multiple metal elements that can form phosphorus compounds with melting points higher than the combustion temperature of the incinerator, and contained in sewage sludge A color evaluation index specifying step that calculates an evaluation index that is the ratio of the inclusion amount that is the amount of phosphorus, and a reference color that is the color of the incinerated ash corresponding to the evaluation index that is used as a standard for preventing the incinerator from being blocked To the incinerator based on the reference color specifying step, the incineration gray specifying step for specifying the color of the incineration ash incinerated in the incinerator, the incineration ash color specified in the incineration gray specifying step, and the reference color. Ash adhesion In accordance with an addition determination step for determining whether or not to add an anti-adhesion agent containing a predetermined metal element for stopping to the sewage sludge, and the determination result of the addition determination step, the anti-adhesion agent is added to the sewage sludge. And an addition step to be added.

  According to the present invention, it is possible to effectively evaluate the risk of blockage of an incinerator when incinerating sewage sludge. Moreover, according to this invention, obstruction | occlusion of an incinerator can be prevented effectively.

FIG. 1 is a configuration diagram of an example of a sewage treatment system for a treatment plant according to the first embodiment of the present invention. FIG. 2 is a diagram showing component analysis results of incineration ash and flue deposits at each treatment plant according to the first embodiment of the present invention. FIG. 3 is a diagram showing a blockage suppression index calculated based on incineration ash and flue deposits in each treatment plant according to the first embodiment of the present invention. FIG. 4 is a configuration diagram of an example of a sewage treatment system according to the second embodiment of the present invention. FIG. 5 is a configuration diagram of an example of a sewage treatment system according to the third embodiment of the present invention. FIG. 6 is a configuration diagram of an example of a sewage treatment system according to the fourth embodiment of the present invention.

  Embodiments of the present invention will be described with reference to the drawings. The embodiments described below do not limit the invention according to the claims, and all the elements and combinations described in the embodiments are essential for the solution of the invention. Is not limited.

<First Embodiment>

  First, a sewage treatment system for a treatment plant according to the first embodiment of the present invention will be described.

  FIG. 1 is a configuration diagram of an example of a sewage treatment system for a treatment plant according to the first embodiment of the present invention.

  The sewage treatment system 1 includes a first sedimentation basin (equivalent to the first sedimentation basin in the “Sewerage Facility Planning and Design Guidelines and Explanation (Part 2) 2009 Edition” (Japan Sewerage Association)), a biological reaction tank 12, 2 Sedimentation basin (corresponding to the final sedimentation basin in “Sewerage Facility Planning / Design Guidelines and Explanation (Part 2) 2009 Edition” (Japan Sewerage Association)), Concentration Tank 14, Concentrator 15, Dehydrator 16 And an incinerator 17.

  The 1st sedimentation basin 11 performs the process which precipitates the suspended solid etc. with large specific gravity contained in the inflowing inflow water, and flows the water after a process into the biological reaction tank 12 of a back | latter stage. The sludge precipitated in the first settling basin 11 is discharged to the concentration tank 14. The biological reaction tank 12 performs organic substance removal, phosphorus removal, nitrogen removal, and the like on the water flowing in from the first sedimentation basin 11 using microorganisms, and flows the treated water to the second sedimentation basin 13 in the subsequent stage. .

  The second sedimentation basin 13 performs a process of precipitating activated sludge (sludge containing microorganisms) contained in the water flowing in from the biological reaction tank 12, and discharges the treated water from the sewage treatment system 1. Of the activated sludge precipitated in the second sedimentation basin 13, the amount necessary for the biological reaction tank 12 is returned to the biological reaction tank 12, and the remainder is discharged to the concentrator 15 as surplus sludge.

  The concentration tank 14 receives the sludge precipitated in the first settling tank 11 and performs a process of concentrating the sludge. The sludge concentrated in the concentration tank 14 is sent to the dehydrator 16. On the other hand, the water generated when the sludge is concentrated in the concentration tank 14 is returned to the upstream of the first sedimentation tank 11. The concentrator 15 performs a process of concentrating excess sludge discharged from the second sedimentation tank 13. The sludge concentrated by the concentrator 15 is sent to the dehydrator 16. On the other hand, the water generated when the sludge is concentrated by the concentrator 15 is returned to the upstream side of the first sedimentation tank 11. The dehydrator 16 dehydrates the sludge sent from the concentration tank 14 and the sludge sent from the concentrator 15. Sludge dehydrated by the dehydrator 16 (dehydrated sludge) is sent to the incinerator 17. On the other hand, moisture generated in the dehydration process by the dehydrator 16 is returned to the upstream of the first sedimentation tank 11. The incinerator 17 incinerates dehydrated sludge. The combustion temperature in the incinerator 17 is, for example, 850 degrees or more, for example, 850 degrees or more and 900 degrees or less.

  Next, an incinerator blockage risk evaluation method for evaluating the risk of blockage in an incinerator that incinerates sewage sludge (dehydrated sludge in the present embodiment) will be described.

First, the amount of a plurality of predetermined metal elements in a predetermined amount of sewage sludge (for example, the mass ratio of the compound containing the metal element) is specified, and the amount of phosphorus in the predetermined amount of sewage sludge (for example, of phosphorus compounds) Mass ratio). As a metal element (target metal element) whose amount is to be specified, a metal that does not liquefy when incinerated in the incinerator 17, that is, a metal that can form a phosphorus compound having a melting point higher than the combustion temperature of the incinerator 17. Element (refractory metal element). In the present embodiment, among the refractory metal elements having a high proportion of sewage sludge, for example, aluminum (Al), iron (Fe), calcium (Ca), magnesium, which are the fourth metal elements. (Mg) is the target of processing. Note that more refractory metal elements may be targeted. Examples of phosphorus compounds produced by combining these metal elements and phosphorus include FePO ₄ , AlPO ₄ , Ca ₃ (PO ₄ ) ₂ , and Mg ₃ (PO ₄ ) ₂ . The melting point of FePO ₄ is not measurable, but is assumed not to be liquefied in the incinerator 17. The melting point of AlPO ₄ is 1800 degrees, the melting point of Ca ₃ (PO ₄ ) ₂ is 1670 degrees, and the melting point of Mg (PO ₄ ) ₂ is 1184 degrees. These phosphorus compounds are not liquefied at the combustion temperature of the incinerator 17 and do not adhere to the incinerator 17.

  Here, phosphorus binds to Al and Fe in the soil when the pH is low, and binds to Ca and Mg when the pH is high. It has been known. Since the pH of the dewatered sludge before incineration is acidic, phosphorus is considered to be in a state where it is easily combined with Al and Fe. However, in the dewatered sludge, there may be a place where the acid is locally consumed and becomes alkaline, and there is a possibility that it binds to Ca and Mg. Therefore, as metal elements that bind to phosphorus, Ca and Mg are included in addition to Al and Fe.

Here, when component analysis was performed on sewage sludge and incineration ash when sewage sludge was burned in the incinerator 17, the amount of each element of Fe, Ti, Ca, Si, Al, Mg, and P before and after incineration was measured. There is almost no decline. For this reason, it turned out that it is not necessary to consider the aeration of these elements in the incineration process in the incinerator 17. Therefore, the amount of these elements obtained by analyzing the components of the incineration ash in the incinerator 17 can be said to be the amount of the corresponding element contained in the sewage sludge. In this embodiment, the element amount contained in the sewage sludge is specified by performing a component analysis of the incinerated ash. Specifically, Fe ₂ O ₃ (ferric oxide), Al ₂ O ₃ (aluminum oxide), CaO (calcium oxide), MgO (magnesium oxide), P ₂ O ₅ (5 The amount of Fe, Al, Ca, Mg, and P is specified by determining the mass ratio (mass%) of diphosphorus oxide). As the component analysis of incineration ash, for example, a component analysis method by fluorescent X-ray analysis can be used. In the following description, processing using the result of analyzing incinerated ash will be described, but processing using the result of component analysis for sewage sludge may be performed. In addition, in terms of storing the analysis sample, since the components are stable, incineration ash is easier to handle.

  Next, based on the amount of the specified metal element (here, the mass ratio of the compound containing the metal element), the amount of phosphorus that can be bound to these metal elements (the amount that can be bound, for example, when the entire incineration ash is a predetermined amount) (Number of moles of) is specified (bondable amount specifying step). Next, the amount of phosphorus contained in the sewage sludge (inclusion amount, for example, the number of moles when the entire incineration ash is defined as a predetermined amount) is specified (inclusion amount specifying step). Thereafter, an evaluation index (occlusion suppression index) that is a ratio of the connectable amount to the inclusion amount is calculated (evaluation index calculation step). Any of the inclusion amount specifying step and the connectable amount specifying step may be executed first.

  Specifically, the formula shown in (1) can be used as a formula for calculating the occlusion suppression index.

Here, X is blockage inhibition index [-] is, _Fe 2 _{O 3} is the mass ratio of _Fe 2 _{O 3} of incineration ash, _Al 2 _{O 3} is the mass ratio of _Al 2 _{O 3} of ash and a, CaO is the mass ratio of CaO in the ash, MgO is the mass ratio of MgO of _ash, P 2 _{O 5} is the weight ratio of _P 2 _{O 5} of ash. M _(i) is the molecular weight [g / mol] of the compound or element i.

The molecule of the formula (1) indicates the amount of phosphorus that can be bound to a plurality of specified metal elements (the amount that can be bound). In Formula (1), the bondable amount indicates the number of moles of phosphorus that can be bonded when the incineration ash is 100 [g]. Here, each term obtained by dividing the mass ratio of the compound in the molecule by the molecular weight of the compound indicates the number of moles of each compound when the entire incineration ash is 100 [g], and is a coefficient multiplied by these terms. Indicates the number of mols of phosphorus required when the metal element contained in 1 mol of the compound corresponding to each term binds to phosphorus. For example, for the term corresponding to _Fe 2 _{O 3,} is in 1mol of _Fe 2 _{O 3,} when 2mol of Fe is present, to produce a phosphorus compound are envisaged (FePO ₄₎ it is, 2mol Noringa Since it is necessary, the coefficient is set to 2. Similarly, for a term corresponding to CaO, 1 mol of Ca is present in 1 mol of CaO, and when the expected phosphorus compound (Ca ₃ (PO ₄ ) ₂ ) is produced, 2/3 mol of CaO is generated. Since phosphorus is necessary, the coefficient is 2/3.

  The denominator of the formula (1) indicates the amount of phosphorus (inclusion amount) included in the sewage sludge. In the formula (1), the inclusion amount indicates the number of moles of phosphorus when the incineration ash is 100 [g].

  Here, the larger the occlusion suppression index, the greater the amount that can be bound than the inclusion amount, and the higher the possibility that phosphorus will bind to a refractory metal element and the lower the possibility of forming a phosphorus compound with a low melting point. Is meant to be. This means that when sewage sludge is incinerated in the incinerator 17, the phosphorus compound having a low melting point becomes liquid and is less likely to adhere to each part of the incinerator 17. Therefore, the blockage suppression index can be used to evaluate the blockage risk of the incinerator 17.

  A clogging suppression index for sewage sludge to be treated by incinerators at a plurality of treatment plants, and ash adhesion and clogging states in the incinerators will be described.

  FIG. 2 is a diagram showing component analysis results of incineration ash and flue deposits at each treatment plant according to the first embodiment of the present invention. FIG. 3 is a diagram showing a blockage prediction index calculated based on incineration ash and flue deposits in each treatment plant according to the first embodiment of the present invention.

  Fig. 2 shows the results of component analysis of incineration ash at different treatment plants (AK) and component analysis of clinker (flue deposits) adhering to the furnace wall of the incinerator at treatment plants (J, H). Results are shown. In FIG. 3, the blockage | suction suppression parameter | index calculated based on the component analysis result of the incineration ash of each processing plant (AK) shown in FIG. 2 and the clinker of a processing plant (J, K) is shown.

As shown in FIG. 2, the incineration ash of the treatment plant has a high mass ratio of P ₂ O ₅ and SiO ₂ , and from the next higher mass ratio, Al ₂ O ₃ , CaO, Fe ₂ O ₃ , In most cases, the order is MgO and TiO ₂ . Further, the clinker tends to weight ratio of P ₂ O ₅ becomes remarkably high.

  As shown in FIG. 3, in the treatment plant J, the blockage suppression index was a value close to 0.9 when the component analysis of the incinerated ash was performed. In this treatment plant J, after analyzing the components of incineration ash, the incinerator was stopped for inspection, and then the incinerator was operated, but incinerator twice in a relatively short period (within 2 months). An occlusion occurred. In addition, the clinker collected from the treatment plant J had an occlusion suppression index close to 0.9. From this, it can be said that a value close to 0.9 for the clogging suppression index can be evaluated as having a high risk of clogging of the incinerator.

  In the treatment plant H, when the component analysis of the incineration ash was performed, the blockage suppression index was a value of about 1.2. In this treatment plant H, the incinerator was continuously used from the time when the component analysis of the incineration ash was performed, but thereafter, the incinerator was blocked in a relatively short period (within 2 months). The clogging suppression index for incineration ash when clogging occurred was about 0.9. In addition, the clinker collected at the treatment plant H had a blockage suppression index value close to 0.9. From this, it can be said that a value close to 0.9 for the clogging suppression index can be evaluated as having a high risk of clogging of the incinerator.

  In the treatment plant G, the blockage suppression index was a value close to 0.9 when the component analysis of the incinerated ash was performed. In the treatment plant G, the incinerator was not blocked, but a lot of clinker was adhered to each part of the incinerator, and therefore, the operation of removing the clinker was performed. From this, it can be said that the risk of blockage of the incinerator is high when the blockage suppression index is close to 0.9.

  On the other hand, in the treatment plants C, D, and E where the blockage suppression index is relatively high (for example, 1.5 or more), the incinerator is not blocked. From this, it can be said that when the blockage suppression index is high, it can be evaluated that the risk of blockage of the incinerator is low.

  Considering the blockage suppression index shown in FIG. 3 and the state of the incinerator in the treatment plant, the value of the blockage suppression index can be used to predict the blockage risk in the incinerator. The occlusion suppression index is compared with a predetermined reference value (for example, a value of 0.9 or 0.9 to 1.0), and it is determined that the risk of occlusion is high when the occlusion suppression index is less than or equal to the reference value. Anyway. In addition, the situation in which blockage occurs may vary depending on the configuration of the incinerator and the state of the target sewage sludge.For example, the standard value to be used is different for each treatment plant or each incinerator at the treatment plant. You may make it.

  In the first embodiment, the blockage suppression index is obtained and the blockage risk of the incinerator is evaluated. However, in the following embodiments, the blockage suppression index is directly or indirectly used in the incinerator. An incinerator blockage prevention method for preventing the generated blockage will be described.

Second Embodiment

  Next, a sewage treatment system according to a second embodiment of the present invention will be described.

  FIG. 4 is a configuration diagram of a sewage treatment system according to the second embodiment of the present invention. In addition, about the structure similar to the sewage treatment system shown in FIG. 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The sewage treatment system 1 in the sewage treatment system 1 according to the first embodiment further includes a blockage suppression index calculation system 30 and a chemical injection unit 25.

  The blockage suppression index calculation system 30 is configured by a computer having an input device such as a mouse and a keyboard, an output device such as a display, a processor, and a memory, for example. The blockage suppression index calculation system 30 calculates the blockage suppression index according to a given condition 31 that is input via the input device, for example. Specifically, the blockage suppression index calculation system 30 includes, for example, a mass ratio (metal concentration) of a compound containing a refractory metal element to be included in the given condition 31 in Formula (1) and a mass ratio of phosphorus. By substituting (phosphorus concentration), a clogging suppression index is calculated and notified to the chemical injection unit 25. The given condition 31 may be set to a mass ratio of a compound containing a refractory metal element that is a target in the incineration ash that has recently occurred in the incinerator 17 and is subjected to component analysis, and a mass ratio of a phosphorus compound. . In addition, component analysis of the yearly incineration ash in the incinerator 17 is performed, and among the component analysis results, the condition that the clogging suppression index is the lowest, that is, the mass ratio of the phosphorus compound is the largest, The condition 31 may be set such that the sum of the mass ratios of the compounds containing the melting point metal element is the smallest. The given condition 31 may be stored in advance in a memory of the blockage suppression index calculation system 30 or the like.

  The medicine injection unit 25 determines whether or not the occlusion suppression index notified from the occlusion suppression index calculation system 30 is lower than a preset reference value (addition determination step), and if lower than the reference value, In order to increase the clogging suppression index, a chemical (adhesion prevention chemical) containing a metal element that becomes a phosphorus compound having a melting point higher than the combustion temperature of the incinerator is added to the sludge and mixed (addition step). As the anti-adhesion agent to be used, an iron-containing agent, for example, polyferric sulfate (polyiron) can be used from the viewpoint of cost and easy handling. The sludge to which the anti-adhesion agent is added may be sludge before being put into the dehydrator 16 or dehydrated sludge dehydrated by the dehydrator 16. In addition, when mixing polyiron with sludge, in order to be able to reprocess a sulfur component, it is preferable before throwing into the dehydrator 16. Thus, by adding a chemical | medical agent to sludge, the high melting-point metal element in sewage sludge can be increased, the possibility that phosphorus will become a compound with a low melting point can be lowered, and as a result, the phosphorus compound becomes liquid. The possibility of adhering to each part of the incinerator 17 can be reduced, and the blockage of the incinerator can be effectively prevented.

  The amount of the anti-adhesion agent added to the sludge may be an amount that allows the clogging suppression index for sewage sludge in a state including the metal element contained in the anti-adhesion agent to exceed a certain reference value. Also, adding anti-adhesion chemicals throughout the year increases costs, so add anti-adhesion chemicals only when the blockage suppression index is low, taking into account seasonal variations in the state of incinerated ash. Anyway. For example, in Japan, since the mass ratio of phosphorus tends to increase in winter, the anti-adhesion agent may be added only in winter.

<Third Embodiment>

  Next, a sewage treatment system according to a third embodiment of the present invention will be described.

  FIG. 5 is a configuration diagram of an example of a sewage treatment system according to the third embodiment of the present invention. In addition, about the structure similar to the sewage treatment system shown in FIG. 4, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The sewage treatment system 1 includes a blockage suppression index calculation system 40 in place of the blockage suppression index calculation system 30 in the sewage treatment system 1 according to the second embodiment. Furthermore, the sewage treatment system 1 includes a flow meter 21, a TP meter 22, a TP meter 23, and a moisture content meter 24.

The flow meter 21 is, for example, an electromagnetic flow meter, measures the amount of inflow water (inflow water amount Q _in [m ³ / d]) flowing into the first settling basin 11 from the outside, and calculates the measurement result as a blockage suppression index. Notify system 40. The TP meter 22 measures the concentration of total phosphorus in the inflow water to the first settling basin 11 (inflow water phosphorus concentration P _in [g / m ³ ]) and notifies the clogging suppression index calculation system 40 of the measurement result. To do. The TP meter 23 measures the concentration of total phosphorus in the effluent flowing out of the second sedimentation basin 11 (the effluent phosphorus concentration P _eff [g / m ³ ]), and the measurement result is sent to the clogging suppression index calculation system 40. Notice. The moisture content meter 24 measures the moisture content H ₂ O [%] in the dewatered sludge and notifies the blockage suppression index calculation system 40.

The obstruction suppression index calculation system 40 receives a given condition 41, a phosphorus recovery rate (α) 42, and a dewatered sludge generation amount (Q _D ) 43.

  The given condition 41 includes a mass ratio of a compound including a plurality of high-melting-point metal elements to be incinerated ash and an ash content A. The mass ratio of the compound containing the refractory metal element of interest in the incineration ash may be the mass ratio of the compound containing the refractory metal element in the incineration ash that has recently occurred in the incinerator 17 and has been subjected to component analysis. A component analysis of the incinerated ash for a period (for example, one year) is performed, and the condition that the clogging suppression index is the lowest among the component analysis results, that is, the total mass ratio of the compounds containing each refractory metal element of interest May be the smallest.

  The ash content A is an analysis value according to an analysis method stipulated in JIS M8812, for example, and when the dewatered sludge is ashed by heating to 815 degrees in air, the mass fraction (% ). The ash content A may be determined according to the target treatment plant for which the blockage suppression index is calculated.

  The phosphorus recovery rate (α) 42 indicates the ratio [%] of phosphorus remaining in the dewatered sludge (solid matter) when the concentration tank 14, the concentrator 15, and the dehydrator 16 perform the concentration and dehydration treatment. Here, depending on the concentration method (gravity concentration, centrifugal concentration, flotation concentration, etc.) or dehydration method (belt press dehydration, centrifugal dehydration, etc.), the proportion of phosphorus remaining in the dewatered sludge varies, so we measured each treatment site, It is preferable to determine the phosphorus recovery rate at each treatment plant.

The dehydrated sludge generation amount (Q _D ) 43 is the amount [kg / d] of dehydrated sludge generated by the dehydrator 16. Dewatered sludge generation amount Q _D, for example, can be measured by an industrial instrument.

  The blockage suppression index calculation system 40 is configured by a computer having an input device such as a mouse and a keyboard, an output device such as a display, a processor, and a memory, for example. The blockage suppression index calculation system 40 calculates the blockage suppression index according to various values input from an input device or another device, for example. Specifically, the occlusion suppression index calculation system 40 calculates an occlusion suppression index by, for example, substituting various values into Equation (2), and notifies the medicine injection unit 25 of the calculated value.

Here, X is blockage inhibition index [-] is, _Fe 2 _{O 3} is the mass ratio of _Fe 2 _{O 3} of incineration ash, _Al 2 _{O 3} is the mass ratio of _Al 2 _{O 3} of ash and a, CaO is the mass ratio of CaO in the ash, MgO is the mass ratio of MgO of _ash, P 2 _{O 5} is the weight ratio of _P 2 _{O 5} of ash. M _(i) is the molecular weight [g / mol] of the compound or element i.

Q _in is the inflow water amount [m ³ / d], Q _D is the dewatered sludge generation amount [kg / d], and _Pin is the inflow water phosphorus concentration [g / m ³ ], P _eff is the effluent phosphorus concentration [g / m ³ ], H ₂ O is the moisture content [%], α is the phosphorus recovery [%], and A is the ash content [%]. is there.

The numerator of the formula (2) is the same as that of the formula (1), and indicates the amount of phosphorus that can be bound to the target refractory metal element in the incinerated ash (amount capable of binding). The bondable amount indicates the number of moles of phosphorus that can be combined when the incineration ash is 100 [g]. The denominator of Equation (2) shows the influent phosphorus concentration P _in, phosphorus in an amount in the incineration ash is calculated based on the effluent phosphorus concentration P _eff (the inclusion amount). The inclusion amount indicates the number of moles of phosphorus when the incineration ash is 100 [g].

  According to the sewage treatment system according to the third embodiment of the present invention, the phosphorus concentration contained in the actual sewage sludge to be combusted in the incinerator 17 is identified with high accuracy and immediately without performing component analysis. Can do. For this reason, before making it burn in the incinerator 17, the clogging suppression index | corresponding appropriately with the sludge can be calculated, and the adhesion preventing chemical can be appropriately added to the sludge. For this reason, while being able to optimize the quantity of the adhesion prevention chemical | medical agent to be used, adhesion of the ash in the incinerator 17 and generation | occurrence | production of the obstruction | occlusion of the incinerator 17 can be prevented appropriately.

<Fourth embodiment>

  Next, a sewage treatment system according to a fourth embodiment of the present invention will be described.

  FIG. 6 is a configuration diagram of an example of a sewage treatment system according to the fourth embodiment of the present invention. In addition, about the structure similar to the sewage treatment system shown in FIG. 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The appearance of the incinerated ash discharged from the incinerator 17 differs depending on the treatment plant, but this is due to the difference in the ash component of the sludge targeted at the treatment plant. Incineration ash is generally reddish brown when there is a lot of iron, and gray to black when there are many other metals. Incineration ash is white when the phosphorus concentration is relatively high with respect to metals. The sewage treatment system according to the fourth embodiment is made by paying attention to the color of incinerated ash having such characteristics, and adheres to sludge based on the color of the incinerated ash discharged from the incinerator 17. Control the addition of preventive drugs.

  In order to control the addition of the anti-adhesion agent based on the color of the incinerated ash, first, in this embodiment, the color of the incinerated ash at a plurality of time points is observed over a long period for each target treatment site. The component of the incinerated ash is analyzed, and the blockage suppression index at that time is calculated according to the equation (1) (color evaluation index specifying step). Then, based on those clogging suppression indexes, it is determined whether or not the addition of the adhesion preventing chemical is necessary, and the color of the incineration ash corresponding to the clogging suppression index determined to be necessary to add the adhesion preventing chemical is determined. Identify (reference color identification step). The color of the incineration ash specified in this way is used as a reference color for controlling the addition of the anti-adhesion agent to the sludge as will be described later. In addition, using the reference color determined based on the blockage suppression index in this way can be said to be indirectly using the blockage suppression index.

  The sewage treatment system 1 further includes a color sensor 26 and a chemical injection unit 27 in the sewage treatment system 1 according to the first embodiment.

  The color sensor 26 detects the color of the incineration ash discharged from the incinerator 17 (incineration gray specifying step), and notifies the chemical injection unit 27 of the color information. The color sensor 26 may be a sensor that measures the hue, saturation, and brightness of the incineration ash.

  The chemical injection unit 27 compares the color notified from the color sensor 26 with a reference color specified in advance, and the notified color has a higher phosphorus concentration than the reference color, that is, has a whiter color. If it is determined that the color has a high phosphorus concentration, an anti-adhesion agent is added to the sludge, while if the color has not been determined to have a high phosphorus concentration, The addition of the anti-adhesion agent is not performed (addition determination step).

  As described above, according to the sewage treatment system 1 according to the fourth embodiment, after the reference color is determined, the incineration ash at that time point is not required to perform the component analysis on the incineration ash discharged from the incinerator 17. It is possible to appropriately evaluate the risk of the incinerator 17 adhering to the incinerator 17 or the clogging of the incinerator 17 due to the incineration ash, and the risk of clogging the incinerator 17 can be reduced.

<Other embodiments>

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not restricted to embodiment mentioned above, It can apply to other various aspects.

  For example, in the second to fourth embodiments, the chemical injection parts 25 and 27 perform the process of adding the anti-adhesion agent to the sludge without manual intervention. However, the present invention is not limited to this, and for example, at least one Human resources may be involved in the department.

  The present invention can be used to evaluate the risk of incinerator blockage. Moreover, this invention can be utilized in order to prevent obstruction | occlusion of an incinerator.

DESCRIPTION OF SYMBOLS 1 Water treatment system 11 1st sedimentation tank 12 Biological reaction tank 13 2nd sedimentation tank 14 Concentration tank 15 Concentrator 16 Dehydrator 17 Incinerator 25, 27 Chemical injection part 26 Color sensor 30, 40 Blocking suppression index calculation system

Claims (1)

An incinerator blockage prevention method for preventing blockage of an incinerator that incinerates sewage sludge,
A reference color specifying step for specifying the color of the incineration ash corresponding to the blockage suppression index determined to require the addition of an anti-adhesion agent containing a predetermined metal element for preventing ash adhesion to the incinerator;
Incineration gray specific step of detecting the color of the incinerated ash discharged from the incinerator by a color sensor;
The reference color specified in advance by the reference color specifying step is compared with the color of the incinerated ash notified from the color sensor, and the color notified from the color sensor has a phosphorous concentration than the reference color. An addition determination step for determining whether the color is high or the index value is low;
According to the determination result of the addition determination step, an addition step of adding the anti-adhesion agent to the sewage sludge;
An incinerator blockage prevention method comprising:

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