Analysis method for judging flue gas denitration condition and consumption reduction potential of waste incineration plant

Abstract

The invention provides an analysis method for judging the flue gas denitration condition and consumption reduction potential of a waste incineration plant. The analysis method comprises the steps that S1, the NOx emission amount of a test incineration plant is obtained; s2, denitration is conducted on NOx in the waste incineration process according to the denitration technology and denitration spray gun distribution of the test incineration plant, the NOx emission amount after denitration is obtained, the NOx emission amount after denitration is compared with the original NOx emission amount, and the denitration efficiency of the test incineration plant is obtained; and S3, optimizing the denitration efficiency by adjusting the denitration process technology and the distribution of the denitration spray guns. The invention provides a systematic analysis method and thought for an incineration plant which does not intend to add a denitration process technology, and the current situation of the incineration plant can be combed, concluded and analyzed, so that main reasons influencing the efficiency of a denitration system and the consumption of a reducing agent can be found out.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion pollutant control analysis research, and particularly relates to an analysis method for judging the denitrification situation and energy consumption reduction potential of the flue gas in a waste incineration plant. Background Art

[0003] To meet the emission standards, a large number of incinerators need to take measures to control the emission of NO x Currently, there are mainly four types of control technologies applied to NO x control in incineration plants: Selective Non-Catalytic Reduction Flue Gas Denitrification Technology (SNCR), Selective Catalytic Reduction Flue Gas Denitrification Technology (SCR), Flue Gas Recirculation (FGR), and Polymer Dry Denitrification Technology (PNCR).

[0004] Among them, Selective Non-Catalytic Reduction Flue Gas Denitrification Technology (SNCR) is a denitrification technology that uses a reducing agent (usually ammonia water or urea solution) to reduce nitrogen oxides in the flue gas to harmless nitrogen and water. The main advantages of this technology are relatively low investment costs and relatively low operating costs. However, there are also problems such as relatively low denitrification efficiency, high requirements for the injection control of the reducing agent, and the need for the spray gun to be in a relatively suitable temperature range to achieve better denitrification efficiency and lower chemical consumption.

[0005] Selective Catalytic Reduction Flue Gas Denitrification Technology (SCR) is a denitrification technology that uses a reducing agent (such as ammonia water or urea) to reduce nitrogen oxides (NO x ) in the flue gas to harmless nitrogen and water. This technology has the advantage of efficiently reducing the NO x emission concentration, but there are also problems such as the need to occupy a certain site, high equipment investment and operating costs, and the life and replacement costs of the catalyst.

[0006] Flue Gas Recirculation (FGR) is a denitrification technology that reintroduces the flue gas generated by combustion into the combustion area, uses the heat absorption of inert gas and the reduction of oxygen concentration to reduce the combustion flame temperature and inhibit the combustion speed, thereby reducing the generation of NO x during the waste combustion process. This technology has the advantages of relatively simple operation, the ability to reduce the air excess coefficient, reduce the exhaust gas loss, and reduce the power consumption of the induced draft fan; however, there is also a problem that when the recirculated flue gas flows back from the outlet flue of the bag filter to the incinerator, the flue gas temperature may drop to the acid dew point due to reasons such as long transportation distance and heat dissipation of the flue, resulting in corrosion of the fan, flue, etc.

[0007] The polymer dry denitration technology (PNCR) uses PNCR agents with polymer compounds and urea as the main reducing agent active ingredients to react with nitrogen oxides to produce harmless nitrogen and water. This technology has the advantages of fast reaction speed and high denitration efficiency, and at the same time does not produce secondary pollution. However, there is also a problem of relatively high preparation and use costs of PNCR agents.

[0008] However, at present, for each waste incineration plant, there is no relatively practical systematic evaluation and analysis method for how to improve the denitration efficiency of a single system, how to analyze the current situation of the existing system, find out the problems of low denitration efficiency and high reagent consumption in the existing system, what transformation path to take, and what technical principles to follow. Blind transformation without the guidance of a methodology may lead to a situation where there is no effect after transformation, or even the effect is worse after transformation. Therefore, it has limitations. Summary of the Invention

[0009] The present invention is made to solve the above problems, and aims to provide an analysis method for judging the flue gas denitration situation and energy consumption reduction potential of waste incineration plants.

[0010] The present invention provides an analysis method for judging the flue gas denitration situation and energy consumption reduction potential of waste incineration plants, which has the following characteristics and includes the following steps:

[0011] S1: Obtain the emission amount of NO x in the test incineration plant,

[0012] The calculation formula for the emission amount of the NO x is as follows:

[0013] NO x = a×(N / fuel)×(O2 / fuel) b ×exp(-E / RT)

[0014] wherein, NO x represents the emission amount of nitrogen oxides, with the unit of mg / Nm 3 ; N / fuel represents the mass fraction of nitrogen element in the incinerated waste; O2 / fuel represents the mass ratio of oxygen to the incinerated waste during the combustion process; exp represents the exponential function of the base e of the natural logarithm; E is the activation energy, indicating the ease of occurrence of the reaction, with the unit of J / mol; R represents the gas constant, with a value of 8.341 J / (mol·K); T represents the combustion temperature, with the unit of K; a and b represent the empirical coefficients fitted by measuring the incinerator temperature and the emission NO x concentration. Among them, the value range of a is 10000 - 50000, and the value range of b is -10 - -110;

[0015] S11: Determine the reasons for the high or low NO emissions based on the waste composition incinerated in the test incineration plant, the backspray situation of the concentrated liquid in the incinerator, and the mechanical load of the test incineration plant. The high or low NO emissions are directly proportional to the high or low temperature of the incinerator furnace. x The content of C, H, S, and O in the waste composition determines the calorific value of the waste entering the furnace, and the high or low calorific value of the waste entering the furnace determines the high or low temperature of the incinerator furnace. The formula for the calorific value of the waste entering the furnace is: x The high or low NO emissions are directly proportional to the high or low temperature of the incinerator furnace.

[0016] The content of C, H, S, and O in the waste composition determines the calorific value of the waste entering the furnace, and the high or low calorific value of the waste entering the furnace determines the high or low temperature of the incinerator furnace. The formula for the calorific value of the waste entering the furnace is:

[0017] Qar == 81×C×100 + 291×H×100 + 25×S×100 - 30×O×100 - 6×H2O×100

[0018] Among them, C, H, S, and O represent the percentage content of carbon, hydrogen, sulfur, and oxygen in the waste composition; Qar represents the calorific value of the waste entering the furnace, with the unit of kcal / kg; H2O represents the percentage of moisture content in the waste composition.

[0019] The formula for the calorific value of the waste entering the furnace can also be expressed as:

[0020] Qar = Qad×(1 - W)

[0021] Among them, Qar represents the calorific value of the waste entering the furnace; Qad represents the dry basis calorific value of the incinerated waste; W represents the moisture content in the incinerator furnace during waste incineration.

[0022] The backspray amount of the concentrated liquid determines the moisture content W in the incinerator furnace. The relationship formula between the concentrated liquid backspray and the moisture content W is:

[0023] W 回喷后 = (Q 垃圾 ×W 回喷前 + Q 浓液 ) / (Q 垃圾 + Q 浓液 )

[0024] Among them, W 回喷前 represents the moisture content in the incinerator furnace before concentrated liquid backspray; W 回喷后 represents the moisture content in the incinerator furnace after concentrated liquid backspray; Q 垃圾 represents the waste incineration amount, with the unit of t / h; Q 浓液 represents the concentrated liquid backspray amount, with the unit of t / h.

[0025] The relationship formula between the mechanical load and the incinerator furnace temperature is:

[0026] T = Qar×A×B

[0027] Among them, T represents the temperature of the incinerator; Qar represents the calorific value entering the furnace; A represents the calorific value correction coefficient, with a value range of 0.5 - 0.6; B represents the mechanical load coefficient, with a value range of 0.9 - 1.2;

[0028] S2: During the waste incineration process, according to the denitrification process technology and the distribution of denitrification spray guns in the test incineration plant, denitrification is carried out on NO x to obtain the NO emissions after denitrification, and the NO emissions after denitrification are compared with the original NO emissions to obtain the denitrification efficiency of the test incineration plant. x Among them, the denitrification process technology affects the denitrification effect of NO and is the main factor determining the denitrification efficiency. The distribution of denitrification spray guns affects the contact area between the denitrification reducing agent and NO x and affects the coverage range of the denitrification reducing agent, which is the secondary factor determining the denitrification efficiency. x

[0029] x x

[0030] S3: Optimize the denitrification efficiency by adjusting the denitrification process technology and the distribution of denitrification spray guns.

[0031] Among them, the denitrification process technology includes FGR, SCR, SNCR, and PNCR. One or more combinations of denitrification process technologies can be selected according to different NO x emission standards to optimize the denitrification efficiency.

[0032] The distribution of denitrification spray guns is affected by the temperature distribution of the incinerator and the scale of the incinerator. According to the temperature distribution of the incinerator, the arrangement position of the denitrification spray gun is determined by formula calculation, and the arrangement quantity of the denitrification spray gun is determined according to the scale of the incinerator, so as to optimize the denitrification efficiency.

[0033] In the analysis method for judging the flue gas denitrification situation and energy consumption reduction potential provided by the present invention, it can also have the following characteristics: when the NO x emission standard is 250 mg / Nm 3 , SNCR is selected as the denitrification process technology; when the NO x emission standard is 200 mg / Nm 3 , the combination of SNCR and FGR is selected as the denitrification process technology; when the NO x emission standard is between 80 - 120 mg / Nm 3 , the combination of SNCR, FGR, and PNCR is selected as the denitrification process technology; when the NO x emission standard is lower than 80 mg / Nm 3 , the combination of SNCR, FGR, and SCR is selected as the denitrification process technology.

[0034] ​​​​In the analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant provided by the present invention, it can also have the following characteristics: Through the historical data of temperature measurement points at different heights of the incinerator, calculate the average temperature value at each height, determine the temperature distribution of the incinerator, and then through the interpolation method, calculate the temperature value at the position of the denitrification spray gun. The calculation formula is as follows:

[0035] T3 = T1 - (T1 - T2) × (H3 - H1) / (H2 - H1) (1)

[0036] T3 = T2 - (T1 - T2) × (H3 - H2) / (H2 - H1) (2)

[0037] T3 = T1 + (T1 - T2) × (H1 - H3) / (H2 - H1) (3)

[0038] Among them, H3 represents the layer where the denitrification spray gun is located, H1 represents the lower layer of H3, H2 represents the upper layer of H3, and T1, T2, and T3 respectively represent the average temperature values of H1, H2, and H3; Formula (1) is applicable to the situation where H3 is between H1 and H2, Formula (2) is applicable to the situation where H3 is above H2, and Formula (3) is applicable to the situation where H3 is below H1.

[0039] In the analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant provided by the present invention, it can also have the following characteristics: When the scale of the incinerator is 250 - 350 tons / day, the number of single-layer arrangements of the denitrification spray gun is 3 - 4; when the scale of the incinerator is 450 - 550 tons / day, the number of single-layer arrangements of the denitrification spray gun is 5 - 6; when the scale of the incinerator is 600 - 750 tons / day, the number of single-layer arrangements of the denitrification spray gun is 7 - 8, and generally one or two layers are put into use according to the situation.

[0040] In the analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant provided by the present invention, it can also have the following characteristics: On the premise of ensuring that the incinerator temperature is not lower than 850 °C, the level of the concentrated liquid backspray consumption is inversely proportional to the incinerator temperature.

[0041] In the analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant provided by the present invention, it can also have the following characteristics: The level of the mechanical load is directly proportional to the incinerator temperature.

[0042] Functions and effects of the invention

[0043] An analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant according to the present invention provides a simple systematic analysis method and idea for an incineration plant that does not plan to add a denitrification process technology. By referring to this method, the current situation of the incineration plant can be sorted out and inductively analyzed one by one, so as to help find out the main reasons affecting the efficiency of the denitrification system and the consumption of reducing agent, and then it is convenient to take corresponding improvement measures according to the symptoms. For an incineration plant that plans to add a denitrification process technology, a global thinking method is provided, that is, simply superimposing a new denitrification process technology cannot achieve a more economical operation effect. Instead, overall consideration should be given, taking into account various main influencing factors and analyzing their correlations, and then comparing the improvement paths of each main factor to improve the efficiency of each individual denitrification process technology, so as to further improve the overall denitrification efficiency and reduce the overall chemical consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic flow chart of an analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the following embodiments will specifically describe the present invention in conjunction with the accompanying drawings.

[0046] Embodiment

[0047] This embodiment provides an analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant, including the following steps:

[0048] The present invention provides an analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant, having the following characteristics, including the following steps:

[0049] The formula for the emission of NO x is as follows:

[0050] NO x = a × (N / fuel) × (O2 / fuel) b × exp(-E / RT)

[0051] where NO x represents the emission of nitrogen oxides, with the unit of mg / Nm 3; N / fuel represents the mass fraction of nitrogen element in the waste to be incinerated; O2 / fuel represents the mass ratio of oxygen to the waste to be incinerated during the combustion process; exp represents the exponential function of the base e of the natural logarithm; E is the activation energy, indicating the ease of the reaction to occur, with the unit of J / mol; R represents the gas constant, with a value of 8.341 J / (mol·K); T represents the combustion temperature, with the unit of K; a and b are empirical coefficients fitted by measuring the incinerator temperature and the NO x emission concentration, where the value range of a is 10000 - 50000, and the value range of b is -10 - -110.

[0052] In this embodiment, NO x includes fuel - type NO x and thermal - type NO x ,

[0053] The calculation formula for fuel - type NO x is:

[0054] Fuel - type NO x = a × N × (C / O2)

[0055] Wherein, fuel - type NO x represents the emission of fuel - type nitrogen oxides, with the unit of mg / Nm 3 ; a represents the empirical coefficient, with a positive value, and the value range is 10000 - 50000; N represents the nitrogen content in the waste to be incinerated, C represents the carbon content in the waste to be incinerated, and O2 represents the oxygen concentration during the combustion process;

[0056] The calculation formula for thermal - type NO x is:

[0057] Thermal - type NO x = 6×10 16 ×[N2]×[O2] 0.5 ×exp(-542000 / RT)

[0058] Where: Thermal - type NO x represents the emission of thermal - type nitrogen oxides; [N2] and [O2] respectively represent the concentrations of nitrogen and oxygen; R represents the gas constant; T represents the temperature, with the unit of K; exp represents the exponential function of the base e of the natural logarithm.

[0059] S11: Judge the reason for the high or low NO x emission according to the waste composition incinerated in the test incineration plant, the situation of concentrated liquid back - spraying in the incinerator, and the mechanical load of the test incineration plant. The high or low NO x emission is directly proportional to the high or low temperature of the incinerator furnace;

[0060] The contents of C, H, S, and O in the garbage composition determine the calorific value of the garbage entering the furnace, and the level of the calorific value entering the furnace determines the temperature of the incinerator furnace. The formula for the calorific value of the garbage entering the furnace is:

[0061] Qar == 81×C×100 + 291×H×100 + 25×S×100 - 30×O×100 - 6×H2O×100

[0062] Among them, C, H, S, and O represent the percentage contents of carbon, hydrogen, sulfur, and oxygen in the garbage composition; Qar represents the calorific value entering the furnace, with the unit of kcal / kg; H2O represents the percentage of the water content in the garbage composition;

[0063] The formula for the calorific value entering the furnace can also be expressed as:

[0064] Qar = Qad×(1 - W)

[0065] Among them, Qar represents the calorific value entering the furnace; Qad represents the dry - basis calorific value of the incinerated garbage; W represents the water content in the incinerator furnace during garbage incineration;

[0066] The spray - back amount of the concentrated liquid determines the water content W in the incinerator furnace. The relationship formula between the concentrated liquid spray - back and the water content W is:

[0067] W 回喷后 =(Q 垃圾 ×W 回喷前 +Q 浓液 ) / (Q 垃圾 +Q 浓液 )

[0068] Among them, W 回喷前 represents the water content in the incinerator furnace before the concentrated liquid spray - back; W 回喷后 represents the water content in the incinerator furnace after the concentrated liquid spray - back; Q 垃圾 represents the garbage incineration amount, with the unit of t / h; Q 浓液 represents the concentrated liquid spray - back amount, with the unit of t / h;

[0069] The relationship formula between the mechanical load and the incinerator furnace temperature is:

[0070] T = Qar×A×B

[0071] Among them, T represents the incinerator furnace temperature; Qar represents the calorific value entering the furnace; A represents the calorific value correction coefficient, and the value range is 0.5 - 0.6; B represents the mechanical load coefficient, and the value range is 0.9 - 1.2

[0072] In this embodiment, the garbage composition determines the calorific value level, and the calorific value level determines the incinerator furnace temperature level. Among them, the common garbage types and their composition are shown in the following table:

[0073]

[0074]

[0075] In this embodiment, the recirculation of concentrated solution mainly has a direct impact on the furnace temperature. Spraying an appropriate amount plays a role in adjusting the furnace temperature. On the premise of ensuring that the incinerator temperature is not lower than 850 °C, the amount of concentrated solution recirculation is inversely proportional to the incinerator temperature. Generally, during normal operation, it is necessary to adjust and spray appropriately according to the furnace temperature fluctuation. When the furnace temperature becomes lower, it is necessary to reduce the amount or stop spraying.

[0076] In this embodiment, the mechanical load is directly proportional to the incinerator temperature. For example: If the incinerator runs at a long-term overload mechanical load, it is easy to cause the incinerator furnace to overheat.

[0077] S2: During the waste incineration process, denitrification is carried out on NO according to the denitrification process technology and the distribution of denitrification spray guns in the test incineration plant x to obtain the NO emissions after denitrification, and compare the NO emissions after denitrification with the original NO emissions to obtain the denitrification efficiency of the test incineration plant. x emissions, and compare the NO emissions after denitrification with the original NO x emissions to obtain the denitrification efficiency of the test incineration plant. x emissions, and compare the NO emissions after denitrification with the original NO emissions to obtain the denitrification efficiency of the test incineration plant.

[0078] Among them, the denitrification process technology affects the denitrification effect of NO and is the main factor determining the denitrification efficiency. The distribution of denitrification spray guns affects the contact area between the denitrification reducing agent and NO x and affects the coverage range of the denitrification reducing agent, which is the secondary factor determining the denitrification efficiency. x and affects the coverage range of the denitrification reducing agent, which is the secondary factor determining the denitrification efficiency.

[0079] In this embodiment, the relationship formula between the total contact area of the agent (simplified calculation according to a two-dimensional plane) and the spray gun distribution is:

[0080] S=(n / 360)×π×R 2 ×N

[0081] Wherein, S represents the total contact area; n represents the central angle degree of the arc, the unit is °, which is related to the nozzle model of the denitrification spray gun; R represents the spraying depth of the denitrification spray gun, which is related to the spraying pressure and flow rate; N represents the number of denitrification spray guns in use.

[0082] S3: Optimize the denitrification efficiency by adjusting the denitrification process technology and the distribution of denitrification spray guns;

[0083] Among them, the denitrification process technology includes FGR, SCR, SNCR, and PNCR. One or more denitrification process technology combinations can be selected according to different NO x emission standards to optimize the denitrification efficiency.

[0084] In this embodiment, when the NO x emission standard is 250 mg / Nm 3 , SNCR is selected as the denitration process technology; when the NO x emission standard is 200 mg / Nm 3 , the combination of SNCR and FGR is selected as the denitration process technology; when the NO x emission standard is between 80 and 120 mg / Nm 3 , the combination of SNCR, FGR and PNCR is selected as the denitration process technology; when the NO x emission standard is lower than 80 mg / Nm 3 , the combination of SNCR, FGR and SCR is selected as the denitration process technology.

[0085]

[0086]

[0087] The distribution of denitration spray guns is affected by the temperature distribution in the incinerator and the scale of the incinerator. According to the temperature distribution in the incinerator, the arrangement position of the denitration spray guns is determined by formula calculation, and the arrangement quantity of the denitration spray guns is determined according to the scale of the incinerator, so as to optimize the denitration efficiency. Among them, the position of the denitration spray gun arrangement is preferably located in the area where the temperature in the incinerator is about 900°C - 950°C, which will make the denitration efficiency higher.

[0088] In this embodiment, through the historical data of the temperature measurement points at different heights of the incinerator, the average temperature value of each height is calculated to determine the temperature distribution in the incinerator, and then through the interpolation method, the temperature value at the position where the denitration spray gun is located is calculated. The calculation formula is as follows:

[0089] T3 = T1 - (T1 - T2) × (H3 - H1) / (H2 - H1) (1)

[0090] T3 = T2 - (T1 - T2) × (H3 - H2) / (H2 - H1) (2)

[0091] T3 = T1 + (T1 - T2) × (H1 - H3) / (H2 - H1) (3)

[0092] Among them, H3 represents the layer where the denitration spray gun is located, H1 represents the lower layer of H3, H2 represents the upper layer of H3, and T1, T2, and T3 respectively represent the average temperature values of H1, H2, and H3; formula (1) is applicable to the case where H3 is between H1 and H2, formula (2) is applicable to the case where H3 is above H2, and formula (3) is applicable to the case where H3 is below H1.

[0093] In this embodiment, when the scale of the incinerator is 250 - 350 tons per day, the number of single-layer arranged denitration spray guns is 3 - 4; when the scale of the incinerator is 450 - 550 tons per day, the number of single-layer arranged denitration spray guns is 5 - 6; when the scale of the incinerator is 600 - 750 tons per day, the number of single-layer arranged denitration spray guns is 7 - 8. Generally, one or two layers are put into use according to the situation.

[0094] In this embodiment, the temperature distribution in the incinerator can directly affect the denitration efficiency. Because when the denitration reducing agent contacts the high-temperature flue gas pollutants, corresponding reduction reactions will occur to remove nitrogen oxides. Therefore, within the appropriate reaction temperature window, the denitration reaction efficiency will increase, thereby reducing the consumption of the denitration reducing agent.

[0095] In this embodiment, it further includes step S4 and step S5, as follows:

[0096] S4: Obtain the reagent consumption of the test incineration plant according to the denitration process technology and the distribution of denitration spray guns used in the test incineration plant;

[0097] Among them, the denitration process technology and the distribution of denitration spray guns are determined by the NO x emission standard and the NO x emission average value. Therefore, by analyzing the reagent consumption through the NO x emission standard and the NO x emission average value, the NO x emission standard and the NO x emission average value are inversely proportional to the reagent consumption.

[0098] In this embodiment, the NO x emission standard basically determines the configuration type of the denitration process technology. Due to the improvement of the NO x emission standard in various places and without adding new denitration process technologies, it is necessary to increase the injection amount of the denitration reducing agent to achieve emission reduction.

[0099] S5: Optimize the reagent consumption of the test incineration plant by adjusting the reagent types and comparing with the reagent consumption of the control incineration plant.

[0100] In this embodiment, two cases are used to further illustrate an analysis method for judging the flue gas denitration situation and the potential for consumption reduction in a waste incineration plant according to the present invention. The cases are as follows:

[0101] Case 1

[0102] Project situation: Incinerator A is equipped with a 500-ton-per-day mechanical grate furnace of a certain brand. The denitration process is only SNCR, and the NO x emission limit is 200 mg / Nm 3, the average mechanical load in 2023 was about 100%. Only about 50% of the incoming garbage was domestic waste, and there was more industrial waste mixed in. There was no concentrated liquid backspray. One layer of SNCR spray guns was set, with 2 spray guns in a single layer. The temperature range corresponding to the spray gun area was about 1050°C. The factory usually controlled nitrogen oxides at 160 mg / Nm 3 or so, and the urea consumption per ton of garbage was about 1.2 kg / t.

[0103] Analysis strategy: According to an analysis method for judging the flue gas denitrification situation and energy consumption reduction potential of a waste incineration plant according to the present invention, first analyze the source strength data from the aspects of garbage composition, concentrated liquid backspray, incinerator shape, and mechanical load. Factory A reached the rated mechanical load, there was no concentrated liquid backspray, there was industrial waste with high calorific value in the incoming garbage, and an incineration boiler with a small configuration size was configured. The combination of multiple factors indicated that the overall furnace temperature of the factory was high, which would lead to a high source strength concentration of nitrogen oxides.

[0104] Then judge the denitrification efficiency from the denitrification process technology and the distribution of denitrification spray guns. Factory A only had SNCR. The overall furnace temperature was high, and the temperature range corresponding to the SNCR spray gun area reached 1050°C, and there were only 2 spray guns. The above situations all affected the SNCR denitrification efficiency. For a grate furnace with a daily disposal scale of 500 tons / day, the front wall and side wall sizes were relatively wide, and 2 spray guns were set on each, with a total of 6 spray guns in a single layer being reasonable. In addition, the furnace temperature corresponding to the spray gun position was too high and needed to be adjusted up to a position around 900°C - 950°C to be appropriate.

[0105] Then analyze the reagent consumption from the NO x emission standard, NO x emission average value, and reagent type. Factory A followed the EU 2010 emission standard, and the nitrogen oxide control value was 200 mg / Nm 3 , and urea was selected as the reducing agent, while the nitrogen oxides were actually controlled at 160 mg / Nm 3 , and finally the urea consumption per ton of garbage was about 1.2 kg / t. The consumption was high, and there was a certain space for energy consumption reduction. For example, through manual intervention and adjustment, the nitrogen oxides would be controlled at around 190 mg / Nm 3 or so in the follow-up, and the reagent consumption could be reduced.

[0106] In summary, the main problems of Factory A were the high furnace temperature caused by high garbage calorific value, the inappropriate distribution position and quantity of SNCR spray guns, and the large difference between the actual controlled nitrogen oxide concentration value and the standard limit value. These factors led to a large urea consumption.

[0107] The countermeasures are as follows: First, consider setting up a concentrated liquid recirculation spraying system or slightly reducing the mechanical load to adjust the furnace temperature. Second, consider adding FGR in the process configuration. The operation cost is low, but it has a certain effect on removing nitrogen oxides, and can further reduce the source strength concentration of nitrogen oxides. In addition, according to the furnace temperature distribution, readjust the position of the SNCR spray gun and appropriately increase the number of single-layer spray guns. Third, according to the NO x actual emission value, try to be as close as possible to the emission standard limit. Through the above adjustment strategies, the consumption of chemicals can be further reduced, achieving the effect of cost reduction and efficiency improvement.

[0108] Case 2

[0109] Project situation: Incinerator B is equipped with a mechanical grate furnace of a certain brand with a daily treatment capacity of 600 tons. The denitration process is SNCR + flue gas recirculation + SCR. The NOx emission limit is 80 mg / Nm 3 , the average mechanical load in 2023 is about 90%, the recirculation system is always open, about 70% of the incoming garbage is domestic waste, and the rest is aged garbage, with concentrated liquid recirculation spraying. The SNCR spray guns are set in two layers, with 8 spray guns in each layer. The temperature range corresponding to the spray gun area is about 900°C - 950°C. When the plant controls nitrogen oxides at about 72 mg / Nm3 daily, the consumption of concentrated ammonia water per ton of garbage is about 4 kg / t.

[0110] Analysis strategy: According to an analysis method for judging the denitration situation and consumption reduction potential of the flue gas of a waste incineration plant of the present invention, first analyze the source strength data from the aspects of garbage composition, concentrated liquid recirculation spraying, incinerator shape, and mechanical load. The mechanical load of Incinerator B is about 90%, there is concentrated liquid recirculation spraying, the incoming garbage contains aged garbage with low calorific value, and it is equipped with an incineration boiler with a wide configuration size. The combination of multiple factors indicates that the overall furnace temperature of the plant is moderate, and the source strength concentration of nitrogen oxides is also moderate.

[0111] Then judge the denitration efficiency from the denitration process technology and the distribution of denitration spray guns. Incinerator B is equipped with SNCR + FGR + SCR, and the temperature range corresponding to the SNCR spray gun area is also within a suitable range, but the number of spray guns put into use is large, with a total of 16 in two layers. For a grate furnace with a daily treatment scale of 600 tons, the front wall and side wall sizes are relatively wide, and 2 are set on each, and about 6 in a single layer is reasonable. Setting too many may cause the area covered by the chemicals sprayed by a single spray gun to overlap with the flue gas, resulting in waste of chemicals and high ammonia escape.

[0112] Then analyze the chemical consumption from the NO x emission standard, NO x emission average value, and chemical types. Incinerator A has a high emission standard, and the nitrogen oxide control value is 80 mg / Nm 3 , so SCR is designed, and ammonia water is selected as the reducing agent, while the actual nitrogen oxides are controlled at 72 mg / Nm 3The left - right situation is also appropriate. The ammonia water consumption per ton of garbage is finally 4 kg / t, and the consumption is relatively high. There is still room for reduction. The potential for reduction can be further explored from the flue gas recirculation and SCR systems.

[0113] In summary, the furnace temperature of Factory B is controlled appropriately. The main problems are that the number of SNCR spray guns is too large, and there may still be room for improvement in the recirculation system and SCR system. These factors lead to a large ammonia water consumption.

[0114] The corresponding measures are as follows: First, conduct a potential - tapping analysis on the recirculation system and SCR system, such as the recirculated flue gas volume / flue gas temperature / injection method, the flue gas temperature at the SCR tower inlet / whether the catalyst is deactivated / whether the injection volume is too large, etc. Second, adjust the number of single - layer SNCR spray guns again according to the furnace temperature distribution.

[0115] Functions and effects of the embodiments

[0116] According to an analysis method for judging the flue gas denitrification situation and reduction potential of a waste incineration plant involved in the present invention, for waste incineration plants that do not plan to add denitrification process technologies, a simple systematic analysis method and idea are provided. By referring to this method, the current situation of the waste incineration plant can be sorted out and analyzed item by item, so as to help find out the main reasons affecting the efficiency of the denitrification system and the consumption of reducing agents, and then it is convenient to take corresponding improvement measures according to the symptoms. For waste incineration plants that plan to add denitrification process technologies, a global thinking method is provided, that is, simply adding new denitrification process technologies does not necessarily achieve a more economical operation effect. Instead, overall consideration should be given, taking into account all the main influencing factors and analyzing their correlations, and then referring to the improvement paths of each main factor to improve the efficiency of each individual denitrification process technology, so as to further improve the overall denitrification efficiency and reduce the overall chemical consumption.

[0117] The above - mentioned embodiments are preferred cases of the present invention and do not limit the protection scope of the present invention.

Claims

1. An analysis method for judging the denitrification situation and energy consumption reduction potential of the flue gas in a waste incineration plant, characterized in that, It includes the following steps: S1: Obtain the emissions of NO x from the test incineration plant, The NO x emission calculation formula is as follows: NO x = a × (N / fuel) × (O2 / fuel) b × exp(-E / RT) Among them, NO x represents the emission of nitrogen oxides, with the unit of mg / Nm 3 ; N / fuel represents the mass fraction of nitrogen element in the incinerated garbage; O2 / fuel represents the mass ratio of oxygen to the incinerated garbage during the combustion process; exp represents the exponential function of the base e of the natural logarithm; E is the activation energy, indicating the ease of the reaction to occur, with the unit of J / mol; R represents the gas constant, with a value of 8.341 J / (mol·K); T represents the combustion temperature, with the unit of K; a and b represent the empirical coefficients fitted by measuring the incinerator temperature and the emission NO x concentration. Among them, the value range of a is 10000 to 50000, and the value range of b is -10 to -110; S11: Determine the reason for the high or low NO x emission based on the composition of the garbage incinerated in the test incineration plant, the backspray situation of the concentrated liquid in the incinerator, and the mechanical load of the test incineration plant. The high or low x NO emission is directly proportional to the high or low temperature of the incinerator furnace; The contents of C, H, S, and O in the garbage components determine the calorific value of the garbage entering the furnace, and the level of the calorific value of the garbage entering the furnace determines the temperature of the incinerator furnace. The formula for the calorific value of the garbage entering the furnace is: Qar == 81×C×100 + 291×H×100 + 25×S×100 - 30×O×100 - 6×W×100 Among them, C, H, S, and O represent the percentage contents of carbon, hydrogen, sulfur, and oxygen in the garbage components; Qar represents the calorific value of the garbage entering the furnace, with the unit of kcal / kg; W represents the moisture content in the incinerator when burning the garbage; The formula for the calorific value of the garbage entering the furnace can also be expressed as: Qar = Qad×(1 - W) Among them, Qar represents the calorific value of the garbage entering the furnace; Qad represents the dry-base calorific value of the garbage when burning; W represents the moisture content in the incinerator when burning the garbage; The spraying amount of the concentrated liquid for back spraying determines the moisture content W in the incinerator. The relationship formula between the concentrated liquid back spraying and the moisture content W is: W 回喷后 =(Q 垃圾 ×W 回喷前 +Q 浓液 ) / (Q 垃圾 +Q 浓液 ) Among them, W 回喷前 represents the moisture content in the incinerator before the concentrated liquid is sprayed back; W 回喷后 represents the moisture content in the incinerator after the concentrated liquid is sprayed back; Q 垃圾 represents the incineration amount of garbage, with the unit of t / h; Q 浓液 represents the spraying-back amount of the concentrated liquid, with the unit of t / h; The relationship formula between the mechanical load and the temperature of the incinerator furnace is: T = Qar×A×B Among them, T represents the temperature of the incinerator furnace; Qar represents the calorific value of the garbage entering the furnace; A represents the calorific value correction coefficient, and the value range is 0.5 - 0.6; B represents the mechanical load coefficient, and the value range is 0.9 - 1.2; S2: During the waste incineration process, denitration is carried out on NO according to the denitration process technology and the distribution of denitration spray guns in the test incineration plant x to obtain the NO emissions after denitration, and compare the NO emissions after denitration with the original NO x emissions to obtain the denitration efficiency of the test incineration plant. x emissions for comparison to obtain the denitration efficiency of the test incineration plant x emissions, and compare the NO emissions after denitration with the original NO Among them, the denitration process technology affects the denitration effect of NO x and is the main factor determining the denitration efficiency. The distribution of the denitration spray guns affects the contact area between the denitration reducing agent and NO x and affects the coverage range of the denitration reducing agent, which is the secondary factor determining the denitration efficiency; S3: Optimize the denitrification efficiency by adjusting the denitrification process technology and the distribution of the denitrification spray guns; Among them, the denitration process technology includes FGR, SCR, SNCR, and PNCR, and one or more denitration process technologies can be selected according to different NO x emission standards to optimize the denitration efficiency by combining them The distribution of the denitrification spray guns is affected by the temperature distribution of the incinerator furnace and the scale of the incinerator. Determine the arrangement position of the denitrification spray guns according to the temperature distribution of the incinerator furnace and through formula calculation, and determine the arrangement quantity of the denitrification spray guns according to the scale of the incinerator, so as to optimize the denitrification efficiency.

2. The analysis method for judging the denitrification situation and energy consumption reduction potential of the flue gas of a waste incineration plant according to claim 1, wherein: Among them, When NO x emission standard is 250 mg / Nm 3 , select SNCR as the denitration process technology; when NO x emission standard is 200 mg / Nm 3 , select the combination of SNCR and FGR as the denitration process technology; when NO x emission standard is between 80 - 120 mg / Nm 3 , select the combination of SNCR, FGR and PNCR as the denitration process technology; when NO x emission standard is lower than 80 mg / Nm 3 , select the combination of SNCR, FGR and SCR as the denitration process technology.

3. The analysis method for judging the denitrification situation and energy consumption reduction potential of the flue gas of a waste incineration plant according to claim 1, wherein: Calculate the average temperature value of each height through the historical data of the temperature measurement points at different heights of the incinerator furnace, determine the temperature distribution of the incinerator furnace, and then calculate the temperature value at the position where the denitrification spray gun is located through the interpolation method. The calculation formula is as follows: T3 = T1 - (T1 - T2)×(H3 - H1) / (H2 - H1) (1) T3 = T2 - (T1 - T2)×(H3 - H2) / (H2 - H1) (2) T3 = T1 + (T1 - T2)×(H1 - H3) / (H2 - H1) (3) Among them, H3 represents the layer where the denitrification spray gun is located, H1 represents the lower layer of H3, H2 represents the upper layer of H3, and T1, T2, and T3 respectively represent the average temperature values of H1, H2, and H3; formula (1) is applicable to the situation where H3 is between H1 and H2, formula (2) is applicable to the situation where H3 is above H2, and formula (3) is applicable to the situation where H3 is below H1.

4. The analysis method for judging the denitrification situation and energy consumption reduction potential of the flue gas of a waste incineration plant according to claim 1, wherein: Among them, When the scale of the incinerator is 250 - 350 tons per day, the number of single - layer arranged denitration spray guns is 3 - 4; when the scale of the incinerator is 450 - 550 tons per day, the number of single - layer arranged denitration spray guns is 5 - 6; when the scale of the incinerator is 600 - 750 tons per day, the number of single - layer arranged denitration spray guns is 7 - 8.

5. The analysis method for judging the flue gas denitration situation and energy - saving potential of a waste incineration plant according to claim 1, characterized in that: Among them, On the premise of ensuring that the incinerator temperature is not lower than 850 °C, the level of the consumption of concentrated liquid back - spraying is inversely proportional to the incinerator temperature.

6. The analysis method for judging the flue gas denitration situation and energy - saving potential of a waste incineration plant according to claim 1, characterized in that: Among them, The level of the mechanical load is directly proportional to the incinerator temperature.

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