JP2015205272A - Reducer supply method in incineration equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reducer supply method capable of supplying a proper amount of a reducer by predicting a nitrogen oxide based on an amount of exhaust gas.SOLUTION: For maintaining density of nitrogen oxide included in an amount of exhaust gas exhausted from an incineration furnace 1, based on the amount of exhaust gas exhausted from an exhaust gas treatment passage part 3, a fluid flow rate supplied to the exhaust gas treatment passage part 3 is subtracted and the amount of exhaust gas on an outlet side of the incineration furnace is determined. Then, using a relationship between the amount of exhaust gas on a position in front of reducer supply position (inlet side of denitration part) which has been measured in advance at the incineration furnace and density of the nitrogen oxide on the outlet side of the incineration furnace, the density of the nitrogen oxide on the inlet side of denitration part is determined based on the determined exhaust gas amount. Then, based on the density of nitrogen oxide, an ammonia supply amount being the reducer which is supplied from a supply nozzle 31 on the inlet side of the denitration part is determined.

Description

  The present invention relates to a reducing agent supply method for supplying a reducing agent such as ammonia that can reduce the concentration of nitrogen oxides (NOx) in exhaust gas from an incinerator.

  In the Air Pollution Control Law, emission standards for nitrogen oxides (NOx) emitted from incinerators (for example, 250 ppm; converted to 12% oxygen) are established, but depending on the location, voluntary regulations are stricter than these emission standards. A value (for example, 100 ppm; oxygen 12% conversion) is set.

By the way, in order to form a low-carbon society or a recycling-oriented society, improvement of power generation amount is regarded as important in the waste treatment field.
As a measure for improving the amount of power generation, there is a method for supplying steam used in an exhaust gas reheater to power generation without adopting a catalyst denitration technology, that is, a waste incineration facility using a non-denitration catalyst technology (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 07-49112

  In the incineration facilities using the above-mentioned non-denitration catalyst technology, it is desired to improve the denitration rate, and in order to improve the non-denitration catalyst technology, if the supply amount of ammonia as a reducing agent is increased, If the leaked ammonia concentration increases, for example, exceeds 10 ppm, white smoke derived from ammonia is generated.

When the combustion state in the incinerator changes, the amount of nitrogen oxide generated also changes, and thus the supply amount of ammonia as a reducing agent also changes.
Therefore, it is necessary to grasp the amount of nitrogen oxides in the exhaust gas and make the supply amount of ammonia appropriate, but there is a problem that it is difficult to accurately measure the amount of nitrogen oxides in the incinerator.

  Then, an object of this invention is to provide the reducing agent supply method which can make the quantity of the reducing agent supplied appropriate by estimating nitrogen oxide from the amount of exhaust gas.

In order to solve the above-mentioned problem, a reducing agent supply method in an incineration facility according to claim 1 of the present invention is an incineration provided with a combustion chamber for burning waste and a flue for guiding exhaust gas generated in the combustion chamber to the outside. Reduction to suppress the generation of nitrogen oxides in the exhaust gas in an incineration facility having an exhaust gas treatment path portion in which an exhaust gas treatment device provided with an exhaust gas treatment device is provided on the way while guiding the exhaust gas discharged from the furnace and the incinerator to the atmosphere side A method of supplying the agent,
By subtracting the flow rate of fluid such as water and air supplied to the exhaust gas treatment path from the amount of exhaust gas discharged from the exhaust gas treatment path, the amount of exhaust gas (F _GAS ) at the incinerator outlet side is obtained.
Using the relationship between the amount of exhaust gas at the position before the supply of the reducing agent and the nitrogen oxide concentration at the incinerator outlet side, which was measured in advance in the incinerator, the amount of exhaust gas (F _GAS ) obtained before the supply of the reducing agent. Determine the nitrogen oxide concentration (C _NOx-in ) (ppm) at the position,
The above-obtained nitrogen oxide concentration (C _NOx-in ) and the nitrogen oxide concentration (C _NOx-out ) (ppm) as the target value are substituted into the following equation (U1) to obtain the denitration rate x,
x = 1- [ _CNOx-out / {CNOx _-in x (21-12) / (21- _CO2 )}] (U1)
(However, _CO2 is the oxygen concentration (%) at the incinerator outlet side)
Based on the data indicating the relationship between the denitration rate x obtained in advance and the equivalent ratio (reducing agent / nitrogen oxide) λ of the reducing agent to achieve the denitration rate x, the above-described equation (U1) is used. The equivalent ratio λ corresponding to the denitration rate x is obtained,
Substituting the equivalent ratio λ into the following equation (U2), the supply amount of reducing agent (F _RED ) based on the amount of exhaust gas is obtained,
F _RED = 10 ⁻⁶ × F _GAS × (1-C _{H 2 O} ) × C _NOx-in × λ (U2)
(However, C _H2O is moisture at the incinerator outlet side (volume ratio))
In this method, the reducing agent is supplied with the supply amount (F _RED ) determined above.

Moreover, the reducing agent supply method in the incineration facility according to claim 2 of the present invention is the reducing agent supply method according to claim 1,
This is a method of using the following equation (U) as a relationship for obtaining the nitrogen oxide concentration (C _NOx-in ) at the position before the supply of the reducing agent.

C _NOx-in = A1 × F _GAS + A2 (U)
(However, A1 and A2 are constants)
Moreover, the reducing agent supply method in the incineration facility according to claim 3 of the present invention is the reducing agent supply method according to claim 1,
This is a method of using the following formula (V) as a relationship for obtaining the nitrogen oxide concentration at the position before the supply of the reducing agent.

C _NOx-in = B1 × F _GAS + B2 × C _O2 + B3 (V)
(However, B1, B2 and B3 are constants, _CO2 is the oxygen concentration at the incinerator outlet side)
Furthermore, the reducing agent supply method in the incineration facility according to claim 4 of the present invention is the reducing agent supply method according to any one of claims 1 to 3,
Supply by measuring the nitrogen oxide concentration (C _NOx-s ) in the exhaust gas on the outlet side of the exhaust gas treatment path and substituting the measured nitrogen oxide concentration (C _NOx-s ) into the following equation (W) together determine the corrected concentration of nitrogen oxides nearby position _{(C NOx-in)} correcting the concentration of nitrogen oxides _{(C NOx-in-M)} , thus determined correction nitrogen oxide concentration _{(C NOx-in-M} ) To correct the denitration rate x.

C _NOx-in-M = (C _NOx-s / C _NOx-out ) × C _NOx-in (W)

  According to the above reducing agent supply method, when the amount of reducing agent supplied into the exhaust gas is determined using the nitrogen oxide concentration in the incinerator at the position before the supply, the nitrogen oxide concentration in the incinerator is incinerated. Since the determination is made based on the amount of exhaust gas discharged from the furnace, the supply amount of the reducing agent can be determined appropriately, that is, accurately.

It is a figure which shows the substantially whole structure of the incineration equipment based on the Example of this invention. It is a block diagram which shows schematic structure of the reducing agent control part of the reducing agent supply apparatus in the incineration equipment. It is a graph which shows the relationship between the equivalent ratio used with the reducing agent supply method in the incinerator, and a denitration rate. It is a graph which shows the nitrogen oxide density | concentration and leak ammonia density | concentration in the driving | running state by the same reducing agent supply apparatus.

Hereinafter, a reducing agent supply method in an incineration facility according to an embodiment of the present invention and a reducing agent supply device for carrying out this reducing agent supply method will be described with reference to FIGS.
First, a schematic overall configuration of an incineration facility provided with a reducing agent supply device will be described.

As shown in FIG. 1, the incinerator is roughly divided into an incinerator 1 for incinerating waste, and an exhaust gas discharged from the incinerator 1 to reduce the temperature of the exhaust gas and to be included in the exhaust gas. An exhaust gas treatment path section 3 having an exhaust gas treatment device 2 for removing dust such as fly ash, and a chimney 4 for releasing the exhaust gas from which dust or the like has been removed in the exhaust gas treatment path section 3 to the atmosphere In addition, ammonia (NH ₃ ), which is a reducing agent, is supplied to the exhaust gas generated in the incinerator 1 (also referred to as “blowing”) to perform denitration to remove nitrogen oxide (NOx), which is a harmful substance. A reducing agent supply device 5 for reducing the concentration is provided. In the following description, when a word including nitrogen oxide is long, and when it is considered easier to express as NOx, nitrogen oxide is represented by NOx. In addition to ammonia, ammonia reducing water or urea diluted water can be used as the reducing agent, but in the following description, it will be described as ammonia. In addition, although the “RED” representing the reducing agent is used for the alphabetic subscripts in the formulas described in the claims of the claims, the description will be made using “NH 3” representing ammonia.

  The incinerator 1 is provided in the lower part of the furnace body 11 and combusts waste, and is disposed above the combustion chamber 12 to guide the exhaust gas generated in the combustion chamber 12 to the outside. The first flue 13, the second flue 14, and the third flue 15 in the vertical direction are configured. In addition, the 1st flue 13 and the 2nd flue 14 which are arrange | positioned above the combustion chamber 12 are the channel | paths of a perpendicular direction, and are made into an inverted U shape, and the boiler part is provided in these flues, respectively. It has been. That is, the lower end of the first flue 13 is opened on the upper surface of the combustion chamber 12, the upper end of the first flue 13 and the upper part of the second flue 14 are connected to each other in a semicircular shape, and the second The lower end of the flue 14 is connected to the lower end inlet side of the third flue 15 provided in the vertical direction.

  In the exhaust gas treatment path section 3, as the exhaust gas treatment device 2, for example, a temperature reducing tower (provided for guiding exhaust gas discharged from the third flue 15 of the incinerator 1 and supplying water to lower the exhaust gas temperature) And a bag filter 22 that guides the exhaust gas whose temperature has been lowered in the temperature-decreasing tower 21 and removes dust, and also provides the temperature reducing tower 21 with the exhaust gas from the incinerator 1. Further, an exhaust gas conduit 23 that leads to the chimney 4 through the bag filter 22 is provided.

Next, the reducing agent supply device 5 will be described. First, an ammonia supply portion that is a NOx reducing agent will be described.
In the vicinity of the upper semicircular connection part of the first flue 13 and the second flue 14 of the furnace body 11, a high denitration performance is obtained in a high temperature range of 800 to 1000 ° C, that is, non-catalytic denitration. Ammonia, which is a reducing agent, is supplied to the exhaust gas in the temperature range. For example, as shown in FIG. 1, supply is made so that ammonia can be supplied at three locations (not limited to three locations, but increased or decreased depending on the waste quality to be incinerated) and within the cross section of the flue Nozzles for spraying (also referred to as jetting nozzles) 31 are arranged. A plurality of supply nozzles 31 are provided along the cross section (a, b, c) and on both the left and right sides so that ammonia can be uniformly supplied to the cross section (a, b, c) of the flue. The first supply nozzle (31A), the second supply nozzle (31B), and the third supply nozzle are representative of the supply nozzles 31 on both the left and right sides corresponding to one cross section. This will be referred to as a nozzle (31C).

  That is, the first supply nozzle 31A is arranged along the horizontal cross section a at the upper position of the central partition wall 11a forming both the flues 13 and 14, and at the upper end of the partition wall 11a, The second supply nozzle 31B is arranged along the transverse section b, and the third supply nozzle 31C is arranged along the transverse section c in the rearward inclined direction at the upper end portion of the partition wall 11a.

  Specifically, in the same installation cross section of the supply nozzle 31, the left and right side wall portions are arranged at a plurality of locations with a distance in the range of 0.2 to 2 m, and in the exhaust gas flow direction, 1 to Arranged at a plurality of places (a plurality of stages) with a distance in the range of 3 m (three places in the present embodiment, but not limited to three places as described above). In addition, each of these supply nozzles 31 is provided such that its injection direction is in the horizontal direction or an angular range of 60 degrees toward the upstream of the exhaust gas flow. This is because ammonia as a reducing agent is uniformly diffused in the exhaust gas by supplying ammonia upstream of the exhaust gas flow.

  And, as will be described later, when controlling the ammonia supply amount from each of the supply nozzles 31, since it is based on the exhaust gas temperature at the supply position, the temperature of each supply portion can be measured. To third thermometer 36 (36A, 36B, 36C) (for example, a thermocouple is used as a thermometer) is provided. Note that only one thermometer may be installed, and other locations may be estimated from the measured temperature by calculation or the like.

  Each of the supply nozzles 31 is connected to a fluid supply pipe 32 that can supply ammonia and steam, and includes a reducing agent control unit 34 that controls the opening degree of the flow control valve 33 provided in the middle thereof. Has been.

  In the following description, a position before supplying ammonia as a reducing agent is referred to as a denitration unit inlet side, and a position after ammonia is supplied is also referred to as a denitration unit outlet side. Moreover, about the denitration part exit side, it can also be called the 3rd flue exit side (it is also a boiler part exit side) or an incinerator exit side.

Next, a measuring instrument necessary for supplying ammonia as a reducing agent in an appropriate amount will be described.
That is, an exhaust gas amount measuring device 41 capable of measuring the exhaust gas amount is provided on the outlet side of the exhaust gas treatment path unit 3, specifically, on the exhaust gas pipe 23 on the outlet side of the bag filter 22. Further, water is sprayed in the temperature reducing tower 21 of the exhaust gas treatment path section 3, and the amount of water supplied and the amount of air for spraying are also measured. Further, air for injecting the exhaust gas treatment chemical is also supplied to the front side of the bag filter 22, and the amount of air is also measured.

  As described above, in the exhaust gas treatment path unit 3, fluids such as water and air are supplied at a plurality of locations. However, in order to simplify the explanation, a water supply pipe connected to the exhaust gas treatment path unit 3 42 and the air supply pipe 43 are illustrated as one (see FIG. 1), and the water supply pipe 42 and the air supply pipe 43 are described as being provided with a water amount measuring device 44 and an air amount measuring device 45, respectively. .

  Further, a NOx concentration meter (nitrogen oxide concentration meter) 46 and an oxygen concentration meter 47 for measuring the NOx concentration and oxygen concentration in the exhaust gas discharged from the exhaust gas treatment path unit 3 are provided.

  Further, a moisture meter 48 for measuring moisture in the exhaust gas at the incinerator outlet is provided on the outlet side of the third flue 15. Instead of using the measured value of the installed moisture meter, a measured value obtained by measuring moisture in the exhaust gas in advance (measured value of moisture in the collected exhaust gas) may be used.

  Incidentally, as described above, the reducing agent supply device 5 includes the reducing agent control unit 34 for supplying the reducing agent according to the combustion state. It will be explained after explanation.

Hereinafter, a method for supplying the reducing agent will be described.
First, from the amount of exhaust gas measured by the exhaust gas amount measuring device 41, the amount of water and the amount of air measured by the water amount measuring device 44 and the air amount measuring device 45 (collectively, it can also be referred to as a fluid flow rate. The amount of exhaust gas (F _GAS ) (m ³ N / h · wet) on the incinerator outlet side is obtained by subtracting the amount, that is, the value as the gas amount.

Next, by substituting this exhaust gas amount (F _GAS ) into the following equation (1), the NOx concentration (C _NOx-in ) (ppm · dry) at the inlet side of the denitration unit, which is the position before the supply of the reducing agent, is obtained. Ask.

C _NOx-in = A1 × F _GAS + A2 (1)
In the above formula, A1 and A2 are constants.
In addition, this equation (1) actually operates the incinerator and actually measures the amount of exhaust gas on the incinerator outlet side (denitration unit outlet side) and the NOx concentration on the denitration unit inlet side, and produces a lot of measurement data. Based on this, a linear expression representing the relationship between the two is obtained using, for example, the least square method. For example, in the case of a certain incinerator, A1 was 0.00311 and A2 was 90.1.

  At this time, the oxygen concentration at the third flue exit side (boiler part exit side), in other words, at the incinerator exit side is required. That is, the total oxygen amount in the exhaust gas from the exhaust gas treatment path unit 3 is obtained from the exhaust gas amount measured by the exhaust gas amount measuring device 41 and the oxygen concentration measured by the oxygen concentration meter 47 and measured by the water amount measuring device 44. The additional oxygen amount contained in these fluids is obtained based on the measured water amount, the air amount measured by the air amount measuring device 45 and the moisture value measured by the moisture meter 48, and the additional oxygen amount is obtained from the total oxygen amount. Is subtracted to obtain the oxygen concentration on the incinerator outlet side.

Next, by substituting the NOx concentration (C _NOx-in ) and the NOx concentration (C _NOx-out ) (ppm · dry) as a target value at the incinerator outlet into the following equation (2), the denitration rate x Calculate The NOx removal rate is obtained by subtracting the NOx concentration ( _CNOx-out ), which is the target value on the incinerator exit side (denitration unit exit side), from the NOx concentration ( _CNOx-in ) on the NOx removal unit inlet side. , Divided by the NOx concentration (C _NOx-in ) at the inlet side of the denitration section, and the following equation (2) takes into account oxygen 12% conversion.

x = 1- [ _CNOx-out / {CNOx _-in x (21-12) / (21- _CO2 )}] (2)
However, in the formula (2), _{CO 2} is the oxygen concentration at the outlet side of the incinerator (the dry value is used) (%).

  Next, a graph (numerical data indicating the relationship between the equivalent ratio of ammonia (ammonia / NOx) λ and the NOx removal rate x with respect to the NOx target value obtained in advance using the obtained NOx removal rate x. The equivalent ratio λ corresponding to the denitration rate x is obtained. The relationship between the equivalent ratio of ammonia to the NOx concentration (ammonia / NOx) λ and the denitration rate x is calculated in advance according to the exhaust gas temperature at the ammonia supply position, for example, as shown in the graph of FIG. It has been. Of course, the temperature at the ammonia supply position is measured by the thermometer 36 every predetermined time. The graph shown in FIG. 3 is obtained, for example, at the position of the second supply nozzle (31B) and according to the temperature, and, of course, differs depending on the ammonia supply position.

Next, the above-obtained equivalent ratio λ is substituted into the following equation (3) to calculate the supply amount of ammonia (F _NH3 ) (m ³ N / h).
F _NH3 = 10 ⁻⁶ × F _GAS × (1-C _{H 2 O} ) × C _NOx-in × λ (3)
However, in the formula (3), _{CH 2 O} is moisture (volume ratio) on the incinerator outlet side, and is measured by a moisture meter 48 arranged on the outlet side of the third flue 15. Instead of using the measured value of the moisture meter 48, a moisture value obtained by measuring moisture in the exhaust gas in advance may be used.

  As described above, when the supply amount of the reducing agent in the exhaust gas is obtained using the nitrogen oxide concentration in the incinerator at the position before the supply, the nitrogen oxide concentration in the incinerator is discharged from the incinerator. Therefore, the supply amount of the reducing agent can be accurately obtained.

Furthermore, the following procedures are performed for white smoke prevention.
That is, in parallel with the calculation of the ammonia supply amount, the ammonia supply concentration (C _NH3 ; 200 to 300 ppm · dry) at the inlet side of the denitration unit corresponding to the regulation value (for example, 10 ppm) for white smoke prevention the supply amount of ammonia is obtained the _{(F 'NH3),} is calculated by the following equation (4).

F ′ _{NH 3} = 10 ⁻⁶ × C _{NH 3} × F _GAS × (1-C _{H 2 O} ) (4)
Next, the obtained ammonia supply amounts (F _NH3 , F ′ _NH3 ) are compared, and usually the ammonia supply amount (F _NH3 ) based on the exhaust gas amount is selected, but the ammonia supply amount (F _NH3 ) based on the exhaust gas amount ( F _NH3) ammonia supply amount _(F based on the regulation value _'if it exceeds _NH3) is ammonia supply amount based on the regulation value _(F' selects _NH3).

That is, ammonia is supplied into the incinerator 1 from the supply nozzle 31 with the selected ammonia supply amount.
Since the NOx concentration (C _NOx-in ) used in the above equation (1) is a calculated value, the NOx concentration (C _NOx-s ) actually measured (measured every predetermined time) is Substituting into the equation (5) for correction, the corrected concentration (C _NOx-in-M ) (ppm · dry) is substituted into the above equation (2) to correct the denitration rate x.

C _NOx-in-M = (C _NOx-s / C _NOx-out ) × C _NOx-in (5)
By the way, as the nozzle 31 for supply arrange | positioned in the incinerator 1, the nozzle used is selected according to combustion load.

  Specifically, when the combustion load is small, the upstream side of the exhaust gas passage is about 850 ° C., so ammonia is supplied from the first supply nozzle 31A, and when the combustion load is medium, the downstream side Since the temperature is about 850 ° C., ammonia is supplied from the second supply nozzle 31B. When the combustion load is large, the downstream side is about 850 ° C., so ammonia is supplied from the third supply nozzle 31C ( For example, it is supplied using steam). That is, according to the combustion load, the supply nozzle 31 to be used is sequentially changed from the upstream side to the downstream side in the exhaust gas flow direction.

  Moreover, about the ammonia supplied in the incinerator 1, ammonia is supplied with a 100% liquid, or it is supplied accompanied by steam or air. When superheated steam or saturated steam is used as the accompanying medium, the supply speed, that is, the injection speed, is set within a range of 1/2 to the speed of sound. In addition, the average particle diameter of the ammonia liquid supplied (injected) from the nozzle is in the range of 10 to 500 μm, and the diameter of the nozzle tip in this case is preferably in the range of 2 to 20 mm. Furthermore, the nozzle to which ammonia is supplied is in the range of 800 to 1000 ° C, preferably in the range of 800 to 950 ° C.

The configuration of the reducing agent control unit 34 will be described based on the above supply method.
That is, as shown in FIG. 2, the reducing agent control unit 34 includes a fluid such as water and air measured by the water amount measuring device 44 and the air amount measuring device 45 from the exhaust gas amount measured by the exhaust gas amount measuring device 41. An outlet side exhaust gas amount calculation unit 51 for subtracting the flow rate to obtain an exhaust gas amount (F _GAS ) on the incinerator outlet side;
By substituting the exhaust gas amount (F _GAS ) obtained by the outlet side exhaust gas amount calculation unit 51 into the following equation (6), the NOx concentration (C _NOx-in ) at the denitration unit inlet side is calculated. A concentration calculator 52;
C _NOx-in = A1 × F _GAS + A2 (6)
[In the formula (6), A1 and A2 are constants]
The exhaust gas amount measured by the exhaust gas amount measuring device 41, the oxygen concentration measured by the oxygen concentration meter 47, the water amount measured by the water amount measuring device 44, the air amount measured by the air amount measuring device 45, and the moisture meter 48 An oxygen concentration calculation unit 53 that inputs the moisture value measured by the above (a moisture value measured in advance may be used) and calculates the oxygen concentration at the incinerator outlet side;
A NOx removal rate calculation unit for obtaining the _NOx removal rate x by substituting the NOx concentration ( _CNOx-in ) and the NOx concentration ( _CNOx-out ) as a target value at the incinerator outlet side into the following equation (7): 54,
x = 1- [ _CNOx-out / {CNOx _-in x (21-12) / (21- _C02 )}] (7)
[In the formula (7), _{CO 2} is the oxygen concentration at the incinerator outlet side]
A graph (for example, shown in FIG. 3) showing the relationship between the equivalent ratio of ammonia to NOx (ammonia / NOx) λ and the denitration rate x using the denitration rate x determined above (in numerical data) Equivalent ratio calculation unit 55 for obtaining an equivalent ratio λ corresponding to the denitration rate x,
A first reducing agent supply amount calculation unit 56 for substituting the obtained equivalent ratio λ into the following equation (8) to obtain an ammonia supply amount (F _NH3 ) based on exhaust gas;
_FNH3 = 10 < ^-6 > * _FGAS * (1- _CH2O ) * _CNOx-in * (lambda) ... (8)
[However, in formula (8), C _H2O is the moisture (volume ratio) at the outlet side of the incinerator (measured value by the moisture meter 48; the moisture value measured in advance may be used)]
Further, in parallel with the calculation of the ammonia supply amount, ammonia at the denitration unit inlet side corresponding to a regulation value (for example, a regulation value such as 10 ppm or an addition regulation value) of the leaked ammonia concentration discharged from the chimney 4 A second reducing agent supply amount calculation unit 57 for substituting the supply concentration (C _NH3 ) into the following equation (9) to obtain an ammonia supply amount (F ′ _NH3 ) based on a regulation value;
F ′ _{NH 3} = 10 ⁻⁶ × C _{NH 3} × F _GAS × (1-C _{H 2 O} ) (9)
The obtained ammonia supply amounts (F _NH3 , F ′ _NH3 ) are compared, and usually the ammonia supply amount (F _NH3 ) based on the exhaust gas amount is selected, but the ammonia supply amount (F _NH3 ) based on the exhaust gas is selected. There 'if it exceeds _(NH3, ammonia supply amount based on regulation value (F ammonia supply amount based on the regulation value _F)' and the reducing agent supply amount selector 58 for selecting _NH3),
The calculated NOx concentration (C _NOx-in ) is corrected by substituting the NOx concentration (C _NOx-s ) in the exhaust gas measured by the NOx concentration meter 46 provided on the processing path outlet side into the following equation (10). And a denitration rate correction unit 59 that corrects the denitration rate x based on the correction concentration (C _NOx-in-M ). Note that a moving average value of 10 seconds to 1 hour may be employed as C _NOx-s .

C _NOx-in-M = (C _NOx-s / C _NOx-out ) × C _NOx-in (10)
Of course, each of the measured values such as temperature, NOx concentration, exhaust gas amount, water amount, water amount, air amount, oxygen concentration, moisture and the like measured by each measuring device is input to the reducing agent control unit 34 and is obtained here. The ammonia supply amount is output to the flow rate control valve 33 that controls the ammonia supply amount.

According to the above reducing agent supply method, when reducing agent concentration is reduced by supplying a reducing agent to exhaust gas discharged from an incinerator, the amount of reducing agent to be supplied is exhausted from the incinerator. Since the determination is based on the amount, that is, the nitrogen oxide concentration in the incinerator can be determined without using a measuring instrument, an appropriate supply amount of the reducing agent can be obtained. Further, when the supply amount of the reducing agent is determined, if the supply amount exceeds the regulation value, the supply amount of the reducing agent based on the regulation value is given priority. It is possible to reliably prevent adverse effects that occur when the regulation value is exceeded, for example, the generation of white smoke when the reducing agent is ammonia. Specific numerical data is shown in FIG. That is, from FIG. 4, the nitrogen oxide concentration (for example, 1 h moving average value) at the incinerator outlet side is stably 40 ppm while the leaked ammonia concentration (NH ₃ leak amount) is kept at a regulated value of 10 ppm or less. It can be seen that the following is maintained.

By the way, in the above embodiment, when obtaining the NOx concentration on the denitration part inlet side, which is the position before the supply of the reducing agent, the formula (1) is used, but particularly when the oxygen concentration on the incinerator outlet side is taken into account. As indicated by the broken line in FIG. 1, a laser oximeter 49 (49 ′) provided on the outlet side of the third flue 15 (or in the second flue 14 or the third flue 15) When the oxygen concentration (wet value) (C _O2 ) is directly measured, the following equation (11) may be used.

C _NOx-in = B1 × F _GAS + B2 × C _O2 + B3 (11)
[However, in the formula (11), B1, B2 and B3 are constants]

DESCRIPTION OF SYMBOLS 1 Incinerator 2 Exhaust gas processing equipment 3 Exhaust gas processing path part 4 Chimney 5 Reducing agent supply apparatus 11 Incinerator 12 Combustion chamber 13 1st flue 14 2nd flue 15 3rd flue 21 Temperature reduction tower 22 Bag filter 31 Supply Nozzle 32 Fluid supply pipe 33 Flow control valve 34 Reducing agent control unit 36 Thermometer 41 Exhaust gas amount measuring device 44 Water amount measuring device 45 Air amount measuring device 46 NOx concentration meter 47 Oxygen concentration meter 48 Moisture meter 49 Laser type oxygen concentration meter 51 Outlet side exhaust gas amount calculation unit 52 Inlet side NOx concentration calculation unit 53 Oxygen concentration calculation unit 54 Denitration rate calculation unit 55 Equivalent ratio calculation unit 56 First reducing agent supply amount calculation unit 57 Second reducing agent supply amount calculation unit 58 Reducing agent supply Volume selection unit 59 Denitration rate correction unit

Claims (4)

An incinerator provided with a combustion chamber for burning waste and a flue for guiding the exhaust gas generated in the combustion chamber to the outside, and an exhaust gas treatment device is provided in the middle of the exhaust gas discharged from the incinerator to the atmosphere side A method of supplying a reducing agent for suppressing the generation of nitrogen oxides in the exhaust gas in an incineration facility having an exhaust gas treatment path portion comprising:
By subtracting the flow rate of fluid such as water and air supplied to the exhaust gas treatment path from the amount of exhaust gas discharged from the exhaust gas treatment path, the amount of exhaust gas (F _GAS ) at the incinerator outlet side is obtained.
Using the relationship between the amount of exhaust gas at the position before the supply of the reducing agent and the nitrogen oxide concentration at the incinerator outlet side, which was measured in advance in the incinerator, the amount of exhaust gas (F _GAS ) obtained before the supply of the reducing agent. Determine the nitrogen oxide concentration (C _NOx-in ) (ppm) at the position,
The above-obtained nitrogen oxide concentration (C _NOx-in ) and the nitrogen oxide concentration (C _NOx-out ) (ppm) as the target value are substituted into the following equation (U1) to obtain the denitration rate x,
x = 1- [ _CNOx-out / {CNOx _-in x (21-12) / (21- _CO2 )}] (U1)
(However, _CO2 is the oxygen concentration (%) at the incinerator outlet side)
Based on the data indicating the relationship between the denitration rate x obtained in advance and the equivalent ratio (reducing agent / nitrogen oxide) λ of the reducing agent to achieve the denitration rate x, the above-described equation (U1) is used. The equivalent ratio λ corresponding to the denitration rate x is obtained,
Substituting the equivalent ratio λ into the following equation (U2), the supply amount of reducing agent (F _RED ) based on the amount of exhaust gas is obtained,
F _RED = 10 ⁻⁶ × F _GAS × (1-C _{H 2 O} ) × C _NOx-in × λ (U2)
(However, C _H2O is moisture at the incinerator outlet side (volume ratio))
A reducing agent supply method in an incineration facility, characterized in that a reducing agent is supplied with the determined supply amount (F _RED ). The method for supplying a reducing agent in an incineration facility according to claim 1, wherein the following equation (U) is used as a relationship for obtaining a nitrogen oxide concentration (C _NOx-in ) at a position before the reducing agent is supplied.
C _NOx-in = A1 × F _GAS + A2 (U)
(However, A1 and A2 are constants) The method for supplying a reducing agent in an incineration facility according to claim 1, wherein the following equation (V) is used as a relationship for obtaining the nitrogen oxide concentration at a position before the reducing agent is supplied.
C _NOx-in = B1 × F _GAS + B2 × C _O2 + B3 (V)
(However, B1, B2 and B3 are constants, _CO2 is the oxygen concentration at the incinerator outlet side) Supply by measuring the nitrogen oxide concentration (C _NOx-s ) in the exhaust gas on the outlet side of the exhaust gas treatment path and substituting the measured nitrogen oxide concentration (C _NOx-s ) into the following equation (W) together determine the corrected concentration of nitrogen oxides nearby position _{(C NOx-in)} correcting the concentration of nitrogen oxides _{(C NOx-in-M)} , thus determined correction nitrogen oxide concentration _{(C NOx-in-M} 4 is used to correct the denitration rate x, the reducing agent supply method in the incineration facility according to any one of claims 1 to 3.
C _NOx-in-M = (C _NOx-s / C _NOx-out ) × C _NOx-in (W)

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