A control method for the primary air temperature of a waste incinerator

Abstract

The present invention relates to the technical field of waste incineration, and specifically relates to a method for controlling the temperature of primary air in a waste incinerator, which specifically includes the following steps: (1) Calculate the moisture content M of the waste entering the furnace according to the water vapor content φ of the flue gas at the outlet of the real-time waste heat boiler ar ; (2) Deduce the required primary air temperature T0 according to the moisture content M of the waste entering the furnace ar ; (3) Set an electromagnetic valve and a flow measurement point Q on the steam pipeline entering the air preheater, and set a temperature measurement point T at the primary air outlet of the air preheater; automatically adjust the opening of the electromagnetic valve to adjust the steam volume for heating the primary air air preheater according to the calculated primary air temperature T0; when the temperature measurement point T at the outlet of the air preheater is adjusted within the range of T0±5°C, the electromagnetic valve stops adjusting, and the steam volume for heating the air preheater no longer changes. The method of the present invention controls and adjusts the primary air temperature through the water vapor content of the flue gas at the outlet of the waste heat boiler, so as to ensure good combustion conditions of the waste in the incinerator

Description

Technical Field

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

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

[0003] After domestic waste enters the incinerator, the processes of waste drying and water evaporation start first. This process requires a large amount of heat. At this time, it is relatively difficult to rely solely on the combustion area that is at a certain distance from the waste drying and evaporation area to supply all the heat. Therefore, it is necessary to send in primary air to provide part of the heat. The primary air is heated by the air preheater, and by adjusting the steam amount of the heating air preheater, the primary air is heated to the set temperature and then sent into the incinerator, so as to achieve the rapid evaporation of moisture and maintain the stability of the combustion state in the furnace.

[0004] Currently, in the current field of waste incineration treatment, the control of the primary air temperature is usually set according to experience. The staff controls the primary air temperature based on the empirical characteristics of the currently treated waste and the combustion state in the furnace. However, the moisture content of domestic waste has dynamic characteristics and fluctuates with the changes in sources, types and seasons. When the moisture content of waste fluctuates, it is often impossible to detect and adjust the primary air temperature in a timely manner, resulting in the deterioration of the furnace condition and affecting the stability of the combustion state in the incinerator.

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

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

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

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

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

[0010] (2) Deduce the required primary air temperature T0 based on the moisture content M of the waste entering the furnace ar ;

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

[0012] Among them, the specific steps of step (1) are as follows

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

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

[0015] ; where V g is the actual flue gas volume generated by incinerating unit waste

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

[0017] ; where V 0 is the theoretical air volume required for incinerating unit waste

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

[0019] ; where H ar is the hydrogen element content in the waste

[0020] Among them, the specific steps of step (2) are as follows

[0021] ① Set the primary air temperature to 240°C when the waste moisture content M ar is 60%; set the primary air temperature to 160°C when the waste M ar is 40%

[0022] ② After calculating M ar , interpolate to calculate the primary air temperature T0 ​​

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

[0024] The control method of the primary air temperature of the waste incinerator of the present invention realizes the real-time control and adjustment of the primary air temperature by detecting the water vapor content in the flue gas at the outlet of the waste heat boiler in real time, so as to cope with the incineration conditions required for different waste water 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 a high water content in the waste entering the furnace, and the combustion temperature in the furnace will be on the low side, which is not conducive to the combustion of the waste on the incinerator grate; by automatically adjusting and increasing the steam amount for heating the primary air preheater, the primary air temperature is increased, so that the waste can be fully dried, the combustion temperature in the furnace is increased, and the combustion condition of the waste on the incinerator grate is improved.

[0026] A low water vapor content in the flue gas indicates a low water content in the waste entering the furnace, and the combustion temperature in the furnace will be on the high side, which will damage the grate and shorten its service life; by automatically adjusting and reducing the steam amount for heating the primary air preheater, the primary air temperature is reduced, so that the combustion temperature in the furnace is reduced, the coking tendency of the first pass is reduced, the effective utilization coefficient of the heating surface is increased, the evaporation amount is increased, the best use performance of the incinerator grate is ensured, and at the same time, the real-time steam consumption for heating the preheater is also reduced, saving production consumption.

[0027] The following further describes the control method of the primary air temperature of the waste incinerator of the present invention with reference to the accompanying drawings. Brief Description of the Drawings

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

[0029] Among them, 1 - waste incinerator; 2 - flue gas purification system; 3 - on-line monitoring system; 4 - chimney; 5 - primary air preheater; 6 - secondary air preheater. Detailed Embodiments

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

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

[0032] Waste water content: the mass percentage of water in the waste per unit mass entering the incinerator.

[0033] Such as Figure 1As shown in the figure, the device adopted by the control method of the primary air temperature of the waste incinerator includes a waste incinerator 1, a flue gas purification system 2, an on-line monitoring system 3 and a chimney 4 which are connected in sequence. Among them, a primary air preheater 5 and a secondary air preheater 6 are provided on the primary air pipeline of the waste 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. 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 control method for the primary air temperature of a waste incinerator controls the primary air temperature required for entering the furnace by the real-time water vapor content of the flue gas at the outlet of the waste heat boiler. The specific steps are as follows:

[0035] (1) According to the real-time water vapor content of the flue gas at the outlet of the waste heat boiler , calculate the moisture content M of the waste entering the furnace ar :

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

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

[0038] ; where, V g is the actual flue gas volume generated by the incineration of unit waste;

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

[0040] ; where, V 0 is the theoretical air volume required for the incineration of unit waste;

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

[0042] ; where, H ar is the hydrogen element content in the waste.

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

[0044] ① Set that when the moisture content M ar of the waste is 60%, the primary air temperature is 240 °C; set that when the waste M ar is 40%, the primary air temperature is 160 °C;

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

[0046] (3) An electromagnetic valve and a flow measurement point Q are set on the steam pipeline entering the air preheater, and a temperature measurement 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 in the air preheater; when the temperature measurement point T at the air preheater outlet is adjusted within the range of T0±5°C, the electromagnetic valve stops adjusting, and the steam volume for heating the air preheater no longer changes.

[0047] Application Example

[0048] The above control method for the primary air temperature is adopted to control the primary air temperature of the waste incinerator in a certain waste incineration project, and the operation data is as follows:

[0049] (1) When the waste incinerator is operating, according to experience, the moisture content of the waste entering the furnace in this batch is set to 50%, and the required primary air temperature is set to 200°C. At this time, the steam volume Q for heating the air preheater is 3.50 t / h.

[0050] (2) Detect the real-time water vapor content in the flue gas at the outlet of the waste heat boiler = 18% and the oxygen content = 6%:

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

[0052]

[0053] Among them, the actual flue gas volume generated by the waste is obtained by dividing the actual flue gas volume at the outlet of the waste heat boiler by the waste input volume, and the actual flue gas volume generated by the waste is V g = 4.879 Nm 3 / kg.

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

[0055]

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

[0057] = 0.864 Nm 3 / kg

[0058] Among them, the theoretical combustion air volume of the waste is taken as V 0 = 2.13 Nm 3 / kg. This value is obtained by calculating the values of C, H, O, S, and Cl in the waste through chemical analysis. The calculation process is V 0 = 0.0889(Car +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]

[0061] =(0.864-0.322-0.034) / 0.0124=40.96

[0062] Among them, the real-time hydrogen content percentage H in the waste entering the furnace is obtained through chemical testing. ar =2.90.

[0063] 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℃;

[0064] ⑤Through the difference calculation, the required primary air temperature T0 is obtained:

[0065] M ar =40.96%, the difference calculation requires primary air temperature T0=164℃.

[0066] 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.

[0067] (3) Detect the real-time water vapor content of flue gas at the outlet of the waste heat boiler =22%, oxygen content =6%:

[0068] ① Calculate the real-time volume of water vapor V in the flue gas H2O :

[0069]

[0070] 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.

[0071] ②Calculate the theoretical water vapor volume after waste incineration :

[0072]

[0073] =1.029-0.0161×(21% / (21%-6%)-1)×1.94

[0074] =1.016 Nm 3 / kg

[0075] 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.

[0076] ③ Calculate the real-time moisture content M of the garbage entering the furnace ar :

[0077]

[0078] =(1.016-0.308-0.031) / 0.0124=54.60

[0079] Among them, the real-time hydrogen content percentage H in the waste entering the furnace is obtained through chemical testing. ar =2.77.

[0080] 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℃;

[0081] ⑤Through the difference calculation, the required primary air temperature T0 is obtained: M ar =54.60%, the difference calculation requires primary air temperature T0=218℃.

[0082] ⑥ Automatically adjust the steam volume of the heating air preheater through the electromagnetic valve FM. When the primary air temperature T at the outlet of the air preheater is 218 ± 5 °C, the electromagnetic valve FM stops operating, and the steam volume Q for heating the air preheater no longer changes. At this time, Q = 3.82 t / h.

[0083] As can be seen from the above examples, the method of the present invention can control the primary air temperature by detecting the water vapor content in the flue gas at the outlet of the waste heat boiler of the incinerator in real time.

[0084] The embodiments described above are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A control method for the primary air temperature of a waste incinerator, characterized in that: Control the primary air temperature required for furnace inlet through the real-time flue gas water vapor content at the outlet of the waste heat boiler, specifically including the following steps: (1) Calculate the moisture content M of the waste entering the furnace based on the water vapor content in the flue gas at the outlet of the real-time waste heat boiler , ar ; ①Detect the real-time water vapor content and oxygen content of the flue gas at the outlet of the waste heat boiler and ; ② Calculate the volume V of water vapor in the flue gas H2O :[[-END]] ; wherein, V g is the actual flue gas volume generated by unit waste incineration; ③ Calculate the theoretical volume of water vapor V after waste incineration 0 H2O : ; where V 0 is the theoretical air volume required for unit waste incineration; ④ Calculate the moisture content M of the waste charged into the furnace ar : M ar =(V 0 H2O -0.111H ar -0.0161V 0 ) / 0.0124; where, H ar is the hydrogen element content in the garbage; (2)Based on the moisture content M of the waste fed into the furnace ar , calculate the required primary air temperature T0; ①Set the moisture content M of the garbage ar When it is 60%, the primary air temperature is 240 °C; set the garbage M ar When it is 40%, the primary air temperature is 160 °C; ② Calculate M ar After that, interpolate to calculate the primary air temperature T0; (3) Install an electromagnetic valve and a flow measurement point Q on the steam pipeline entering the air preheater, and set a temperature measurement point T at the primary air outlet of the air preheater; automatically adjust the opening of the electromagnetic valve to adjust the steam volume for heating the primary air in the air preheater according to the calculated primary air temperature T0; when the outlet temperature measurement point T of the air preheater is adjusted within the range of T0±5°C, the electromagnetic valve stops adjusting, and the steam volume for heating the air preheater no longer changes.

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