Method for controlling primary air temperature of garbage incinerator

Abstract

The invention relates to the technical field of waste incineration, in particular to a method for controlling the primary air temperature of a waste incinerator, which specifically comprises the following steps of: (1) calculating the water content Mar of garbage entering the incinerator according to the real-time water vapor content phi of flue gas at an outlet of a waste heat boiler; (2) calculating the required primary air temperature T0 according to the water content Mar of the garbage fed into the furnace; (3) arranging an electromagnetic valve and a flow measuring point Q on a steam pipeline entering the air pre-heater, and arranging a temperature measuring point T at a primary air outlet of the air pre-heater; according to the calculated primary air temperature T0, the opening degree of an electromagnetic valve is automatically adjusted to adjust the steam amount for heating the primary air pre-heater; and when the outlet temperature measuring point T of the air pre-heater is adjusted to be within the range of T0 + / -5 DEG C, the electromagnetic valve stops adjusting, and the steam quantity for heating the air pre-heater does not change any more. According to the method, the primary air temperature is controlled and adjusted through the steam content of the exhaust gas at the outlet of the waste heat boiler, and therefore the good combustion condition of garbage in the incinerator is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of waste incineration, and in particular to a method for controlling the primary air temperature of a waste incinerator. Background Art

[0002] With the acceleration of urbanization, the treatment of domestic waste has become an important part of urban management. Waste incineration is widely used as an efficient, volume-reducing and harmless treatment method. However, during the incineration process, the moisture content of domestic waste has dynamic characteristics. It varies greatly with factors such as the source, type and season of the waste. At the same time, the moisture content of domestic waste is also in the process of transfer during the disposal, collection, transportation, treatment and disposal of domestic waste. The above situations will pose a serious threat to the stable operation of waste incinerators and their supporting equipment.

[0003] After domestic garbage enters the incinerator, the process of garbage drying and water evaporation begins first. This process requires a lot of heat. At this time, it is difficult to fully heat only by relying on the combustion area that is a certain distance away from the garbage drying and evaporation area. Therefore, the primary air needs to provide part of the heat. The primary air is heated by the air preheater. By adjusting the steam volume of the heating air preheater, the primary air is heated to the set temperature and then sent to the incinerator, thereby achieving rapid evaporation of water and maintaining the stability of the combustion state in the furnace.

[0004] At present, in the current waste incineration treatment field, the control of primary air temperature is usually set based on experience. The staff controls the primary air temperature based on the current experience of waste treatment and the combustion state in the furnace. However, the moisture content of domestic waste has dynamic characteristics and fluctuates with the source, type and season. When the moisture content of waste fluctuates, it is often impossible to detect and adjust the primary air temperature in time, which leads to the deterioration of the furnace condition and affects the stability of the combustion state in the incinerator.

[0005] Therefore, there is an urgent need in the art to develop a method for controlling the temperature of primary air to ensure stable combustion of garbage in an incinerator. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a method for controlling the primary air temperature of a waste incinerator, which controls and adjusts the primary air temperature by adjusting the water vapor content of the flue gas at the outlet of the waste heat boiler, thereby ensuring good combustion conditions of the waste in the incinerator.

[0007] In order to solve the above technical problems, this application provides the following technical solutions:

[0008] A method for controlling the primary air temperature of a waste incinerator, which controls the primary air temperature required for entering the furnace by using the real-time water vapor content of flue gas at the outlet of a waste heat boiler, specifically comprises the following steps:

[0009] (1) Calculate the moisture content M of the waste entering the boiler based on the real-time water vapor content φ of the flue gas at the waste heat boiler outlet ar ;

[0010] (2) According to the moisture content M of the waste entering the furnace ar , calculate the required primary air temperature T0;

[0011] (3) An electromagnetic valve and a flow measuring point Q are set on the steam pipeline entering the air preheater, and a temperature measuring point T is set at the primary air outlet of the air preheater; according to the calculated primary air temperature T0, the opening of the electromagnetic valve is automatically adjusted to adjust the steam volume for heating the primary air air preheater; when the air preheater outlet temperature measuring point T is adjusted to within the range of T0±5℃, the electromagnetic valve stops adjusting and the steam volume for heating the air preheater no longer changes.

[0012] Wherein, the step (1) specifically comprises:

[0013] ① Detect the real-time flue gas water vapor content φ and oxygen content φ at the outlet of the waste heat boiler O2 ;

[0014] ②Calculate the volume of water vapor V in the flue gas H2O :

[0015] V H2O =V g ×φ; where V g The actual amount of flue gas generated by the incineration of a unit of garbage;

[0016] ③Calculate the theoretical water vapor volume V after waste incineration 0 H2O :

[0017] V 0 H2O =V H2O -0.0161×(21 / (21-φ O2 )-1)×V 0 ; Among them, V 0 The theoretical amount of air required for unit waste incineration;

[0018] ④ Calculate the moisture content M of the waste entering the furnace ar :

[0019] M ar =(V 0 H2O -0.111H ar -0.0161V 0 ) / 0.0124; where H ar It is the hydrogen content in the garbage.

[0020] Wherein, the step (2) is specifically:

[0021] ①Set the garbage moisture content M ar When it is 60%, the primary air temperature is 240℃; set the garbage M ar When it is 40%, the primary air temperature is 160℃;

[0022] ② Calculate M ar Then, the primary air temperature T0 is calculated by interpolation.

[0023] Compared with the prior art, the method for controlling the primary air temperature of a garbage incinerator of the present invention has at least the following beneficial effects:

[0024] The method for controlling the primary air temperature of a waste incinerator of the present invention detects the water vapor content of the flue gas at the outlet of the waste heat boiler in real time, thereby achieving real-time control and adjustment of the primary air temperature to cope with the incineration conditions required for different waste moisture contents and keep the combustion state in the incinerator always in a good state.

[0025] A high water vapor content in the flue gas indicates that the moisture content of the garbage entering the furnace is high, and the combustion temperature in the furnace will be low, which is not conducive to the combustion of the garbage on the incineration grate. By automatically adjusting the amount of steam used to heat the primary air preheater and increase the primary air temperature, the garbage can be fully dried, the combustion temperature in the furnace can be increased, and the combustion condition of the garbage on the incineration grate can be improved.

[0026] Low water vapor content in flue gas means that the moisture content of the garbage entering the furnace is low, the combustion temperature in the furnace will be relatively high, which will damage the grate and shorten its service life; by automatically adjusting the amount of steam used to heat the primary air preheater, the primary air temperature is reduced, thereby reducing the combustion temperature in the furnace, reducing the coking tendency of one channel, improving the effective utilization coefficient of the heating surface, increasing the evaporation amount, ensuring the optimal performance of the incineration grate, and also reducing the real-time steam consumption for heating the air preheater, saving production consumption.

[0027] The method for controlling the primary air temperature of a waste incinerator of the present invention will be further described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a schematic diagram of the device layout of the method for controlling the primary air temperature of a waste incinerator.

[0029] Among them, 1-waste incinerator; 2-flue gas purification system; 3-online monitoring system; 4-chimney; 5-primary air preheater; 6-secondary air preheater. DETAILED DESCRIPTION

[0030] The professional terms and nouns involved in the present invention are explained as follows:

[0031] Flue gas water vapor content: the volume percentage of water vapor in unit volume of flue gas.

[0032] Garbage moisture content: the mass percentage of water in unit mass of garbage entering the incinerator.

[0033] like Figure 1 As shown, the device used in the method for controlling the primary air temperature of a garbage incinerator includes a garbage incinerator 1, a flue gas purification system 2, an online monitoring system 3 and a chimney 4 connected in sequence. Among them, a primary air preheater 5 and a secondary air preheater 6 are provided on the primary air duct of the garbage incinerator. A temperature measuring point T is provided on the pipeline behind the outlet of the secondary air preheater 6. An electromagnetic valve FM and a flow measuring point Q are provided on the main pipeline of the steam pipeline, and the end of the steam pipeline is divided into two branches, which are respectively connected to the primary air preheater 5 and the secondary air preheater 6.

[0034] A method for controlling the primary air temperature of a waste incinerator, which controls the primary air temperature required for entering the furnace by using the real-time water vapor content of flue gas at the outlet of a waste heat boiler, and the specific steps are as follows:

[0035] (1) Calculate the moisture content M of the waste entering the boiler based on the real-time water vapor content φ of the flue gas at the waste heat boiler outlet ar :

[0036] ① Detect the real-time flue gas water vapor content φ and oxygen content φ at the outlet of the waste heat boiler O2 ;

[0037] ②Calculate the volume of water vapor V in the flue gas H2O :

[0038] V H2O =V g ×φ; where V g The actual amount of flue gas generated by the incineration of a unit of garbage;

[0039] ③Calculate the theoretical water vapor volume V after waste incineration 0 H2O :

[0040] V 0 H2O =V H2O -0.0161×(21 / (21-φ O2 )-1)×V 0 ; Among them, V 0 The theoretical amount of air required for unit waste incineration;

[0041] ④ Calculate the moisture content M of the waste entering the furnace ar :

[0042] M ar =(V 0 H2O -0.111H ar -0.0161V 0 ) / 0.0124; where Har It is the hydrogen content in the garbage.

[0043] (2) According to the moisture content M of the waste entering the furnace ar , calculate the required primary air temperature T0:

[0044] ①Set the garbage moisture content M ar When it is 60%, the primary air temperature is 240℃; set the garbage M ar When it is 40%, the primary air temperature is 160℃;

[0045] ② Calculate M ar Then, the primary air temperature T0 is calculated by interpolation.

[0046] (3) An electromagnetic valve and a flow measuring point Q are set on the steam pipeline entering the air preheater, and a temperature measuring point T is set at the primary air outlet of the air preheater; according to the calculated primary air temperature T0, the opening of the electromagnetic valve is automatically adjusted to adjust the steam volume for heating the primary air air preheater; when the air preheater outlet temperature measuring point T is adjusted to within the range of T0±5℃, the electromagnetic valve stops adjusting and the steam volume for heating the air preheater no longer changes.

[0047] Application Examples

[0048] The above primary air temperature control method is used to control the primary air temperature of a waste incinerator in a waste incineration project. The operating data are as follows:

[0049] (1) When the incinerator is running, the moisture content of the garbage entering the incinerator is set to 50% based on experience, and the required primary air temperature is set to 200°C. At this time, the steam volume for heating the air preheater is Q = 3.50 t / h.

[0050] (2) Detect the real-time flue gas water vapor content φ = 18% and oxygen content φ O2 =6%:

[0051] ① Calculate the real-time volume of water vapor V in the flue gas H2O :

[0052] V H2O =V g ×φ=4.879×18%=0.878Nm 3 / kg

[0053] The actual flue gas volume V generated by the waste heat boiler is obtained by dividing the actual flue gas volume at the waste heat boiler outlet by the amount of waste entering the boiler. g =4.879Nm 3 / kg.

[0054] ② Calculate the theoretical water vapor volume V after waste incineration 0 H2O :

[0055] V 0 H2O =V H2O -0.0161×(21 / (21-φ O2 )-1)×V 0

[0056] =0.878-0.0161×(21 / (21-6)-1)×2.13

[0057] =0.864Nm 3 / kg

[0058] Among them, the theoretical combustion air volume of garbage is taken as V 0 =2.13Nm 3 / kg. This value is calculated by analyzing the values ​​of C, H, O, S, and Cl in the garbage. The calculation process is: 0 =0.0889(C ar +0.375S ar )+0.265H ar -0.0333O ar +0.0301Cl. Among them, C ar , S ar , H ar , O ar and Cl are the percentages of C, S, H, O, and Cl elements, respectively.

[0059] ③ Calculate the real-time moisture content M of the garbage entering the furnace ar :

[0060] M ar =(V 0 H2O -0.111H ar -0.0161V 0 ) / 0.0124

[0061] =(0.864-0.322-0.034) / 0.0124

[0062] =40.96

[0063] Among them, the real-time hydrogen content percentage H in the waste entering the furnace is obtained through chemical testing. ar =2.90.

[0064] ④ Set the moisture content of the garbage entering the furnace M ar When the moisture content of the waste entering the furnace is M ar When it is 40%, the primary air temperature is 160℃;

[0065] ⑤Through the difference calculation, the required primary air temperature T0 is obtained:

[0066] M ar =40.96%, the difference calculation requires primary air temperature T0 = 164℃.

[0067] ⑥ The steam quantity for heating the air preheater is automatically adjusted by the electromagnetic valve FM. When the primary air temperature T at the outlet of the air preheater is 164±5℃, the electromagnetic valve FM will no longer operate and the steam quantity Q for heating the air preheater will no longer change. At this time, Q=2.87t / h.

[0068] (3) Detect the real-time flue gas water vapor content φ = 22% and oxygen content φ O2 =6%:

[0069] ① Calculate the real-time volume of water vapor V in the flue gas H2O :

[0070] V H2O =V g ×φ=4.676×22%=1.029Nm 3 / kg

[0071] The actual flue gas volume V generated by the waste heat boiler is obtained by dividing the actual flue gas volume at the waste heat boiler outlet by the amount of waste entering the boiler. g =4.676Nm 3 / kg.

[0072] ② Calculate the theoretical water vapor volume V after waste incineration 0 H2O :

[0073] V 0 H2O =V H2O -0.0161×(21 / (21-φ O2 )-1)×V 0

[0074] =1.029-0.0161×(21 / (21-6)-1)×1.94

[0075] =1.016Nm 3 / kg

[0076] Among them, the theoretical combustion air volume of garbage is taken as V 0 =1.94Nm 3 / kg. This value is calculated by analyzing the values ​​of C, H, O, S, and Cl in the garbage. The calculation process is: 0 =0.0889(C ar +0.375S ar )+0.265H ar-0.0333O ar +0.0301Cl. Among them, C ar , S ar , H ar , O ar and Cl are the percentages of C, S, H, O, and Cl elements, respectively.

[0077] ③ Calculate the real-time moisture content M of the garbage entering the furnace ar :

[0078] M ar =(V 0 H2O -0.111H ar -0.0161V 0 ) / 0.0124

[0079] =(1.016-0.308-0.031) / 0.0124

[0080] =54.60

[0081] Among them, the real-time hydrogen content percentage H in the waste entering the furnace is obtained through chemical testing. ar =2.77.

[0082] ④ Set the moisture content of the garbage entering the furnace M ar When the moisture content of the waste entering the furnace is M ar When it is 40%, the primary air temperature is 160℃;

[0083] ⑤Through the difference calculation, the required primary air temperature T0 is obtained: M ar When =54.60%, the difference calculation requires primary air temperature T0=218℃.

[0084] ⑥ The steam quantity for heating the air preheater is automatically adjusted by the electromagnetic valve FM. When the primary air temperature T at the outlet of the air preheater is 218±5℃, the electromagnetic valve FM will no longer operate and the steam quantity Q for heating the air preheater will no longer change. At this time, Q=3.82t / h.

[0085] It can be seen from the above examples that the method of the present invention can control the primary air temperature by real-time detection of the water vapor content in the flue gas at the outlet of the waste heat boiler of the incinerator.

[0086] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for controlling the primary air temperature of a garbage incinerator, characterized in that: The primary air temperature required for entering the furnace is controlled by the real-time water vapor content of the flue gas at the waste heat boiler outlet, which specifically includes the following steps: (1) Calculate the moisture content M of the waste entering the boiler based on the real-time water vapor content φ of the flue gas at the waste heat boiler outlet ar ; (2) According to the moisture content M of the waste entering the furnace ar , calculate the required primary air temperature T0; (3) An electromagnetic valve and a flow measuring point Q are set on the steam pipeline entering the air preheater, and a temperature measuring point T is set at the primary air outlet of the air preheater; according to the calculated primary air temperature T0, the opening of the electromagnetic valve is automatically adjusted to adjust the steam volume for heating the primary air air preheater; when the air preheater outlet temperature measuring point T is adjusted to within the range of T0±5℃, the electromagnetic valve stops adjusting and the steam volume for heating the air preheater no longer changes.

2. The method for controlling the primary air temperature of a waste incinerator according to claim 1, characterized in that: The step (1) specifically comprises: ① Detect the real-time flue gas water vapor content φ and oxygen content φ at the outlet of the waste heat boiler O2 ; ②Calculate the volume of water vapor V in the flue gas H2O : V H2O =V g ×φ; where V g The actual amount of flue gas generated by the incineration of a unit of garbage; ③Calculate the theoretical water vapor volume V after waste incineration 0 H2O : V 0 H2O =V H2O -0.0161×(21 / (21-φ O2 )-1)×V 0 ; Among them, V 0 The theoretical amount of air required for unit waste incineration; ④ Calculate the moisture content M of the waste entering the furnace ar : M ar =(V 0 H2O -0.111H ar -0.0161V 0 ) / 0.0124; where H ar It is the hydrogen content in the garbage.

3. The method for controlling the primary air temperature of a waste incinerator according to claim 2, characterized in that: The step (2) is specifically: ①Set the garbage moisture content M ar When it is 60%, the primary air temperature is 240℃; set the garbage M ar When it is 40%, the primary air temperature is 160℃; ② Calculate M ar Then, the primary air temperature T0 is calculated by interpolation.

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