Wind powder temperature control method

Abstract

The invention provides an air and powder temperature control method, the air and powder temperature is the air and powder temperature of an outlet of a coal mill, and the control method comprises the steps that the target air and powder temperature of the outlet of the coal mill and the current actual air and powder temperature of the air outlet of the coal mill are obtained; the opening and closing state of a cold primary air door at an inlet of the coal mill is obtained; whether an adjusting valve of a hot primary air side flue is adjusted or not is determined according to the opening and closing state of a cold primary air door and the difference value between the target air powder temperature and the current actual air powder temperature; when the adjusting valve of the hot primary air side flue is adjusted, the first opening degree of the adjusting valve of the hot primary air side flue is obtained; and an adjusting valve of the hot primary air side flue is adjusted according to the first opening degree. According to the air powder temperature control method, the opening degree of the adjusting valve of the hot primary air side flue is adjusted and controlled, the temperature of hot air introduced into the coal mill is directly adjusted, the amount of cold air introduced into the hot air is eliminated, the heat loss of a temperature control system is reduced, and the air powder temperature control effect is improved.

Description

Technical Field

[0001] The invention relates to a coal mill control method, and in particular to an air-powder temperature control method. Background Art

[0002] In the prior art, hot air desiccant needs to be introduced into the coal mill body to dry and transfer the coal pulverized product.

[0003] When the boiler load and coal quality of the unit remain basically unchanged, the total primary air volume required by the boiler remains basically unchanged. The flue gas at the flue gas inlet on the hot primary air side comes from the flue gas discharged by the air preheater. The flue gas temperature at the flue gas inlet on the hot primary air side is also basically constant. However, since the hot air temperature is often higher than the temperature required by the coal mill desiccant, a certain amount of cold air needs to be added to the hot air desiccant entering the coal mill to adjust the temperature of the hot air.

[0004] At the same time, the moisture content of raw coal varies with different coal qualities. For coal with low moisture content, the temperature of the hot air desiccant required is relatively low while ensuring that the air powder temperature at the pulverizer outlet remains unchanged, so the amount of cold air entering the mill needs to be increased accordingly; for coal with high moisture content, higher temperature hot air is required for drying, and even when the cold air volume is zero, the air powder temperature at the pulverizer outlet may still not meet the actual requirements.

[0005] However, the control method of air-powder temperature in the prior art will increase the heat loss of the temperature control system. When the hot air temperature is higher than the temperature required for coal mill drying, adding cold air to the hot air to adjust the hot air temperature will cause the flue gas used for heat exchange discharged by the air preheater to produce a part of the heat loss. At the same time, when the required drying hot air temperature is high, even if cold air is not added, the hot air temperature will not meet the temperature requirements, resulting in unsatisfactory drying effect. Summary of the invention

[0006] The invention provides an air-powder temperature control method, so as to reduce the heat loss of the temperature control system and improve the air-powder temperature control effect.

[0007] The embodiment of the present invention provides a method for controlling air-powder temperature, wherein the air-powder temperature is the air-powder temperature at a coal mill outlet, and the method comprises:

[0008] Obtaining the target air-powder temperature at the coal mill outlet and the current actual air-powder temperature at the coal mill outlet;

[0009] Obtaining the open / closed state of the cold primary air door at the coal mill inlet;

[0010] Determining whether to adjust the regulating valve of the hot primary air side flue according to the opening and closing state of the cold primary air door and the difference between the target air powder temperature and the current actual air powder temperature;

[0011] When adjusting the regulating valve of the hot primary air side flue, obtaining the first opening degree of the regulating valve of the hot primary air side flue;

[0012] The regulating valve of the hot primary air side flue is adjusted according to the first opening.

[0013] Optionally, obtaining the target air-powder temperature at the coal mill outlet includes:

[0014] When the coal quality in the coal mill changes, the target air-powder temperature is determined according to the coal quality; the coal quality includes dry ash-free volatile matter of the coal;

[0015] Wherein, when the coal mill is a medium-speed coal mill, the dry ash-free volatile matter V daf <40%, then the target air powder temperature T1=[(82-V daf )×5 / 3]±5℃; Dry ash-free volatile matter V of coal daf ≥40%, the target air powder temperature T1: 60≤T1≤70℃; where V daf It is the dry ash-free volatile matter of coal;

[0016] When the coal mill is a low-speed coal mill, the dry ash-free volatile matter of the coal is 10%<V daf ≤20%, then the target air-powder temperature T1: 100≤T1≤130℃; dry ash-free volatile matter of coal 20%<V daf <40%, then the target air-powder temperature T1: 70≤T1≤90℃; the dry ash-free volatile matter V daf ≥40%, then the target air powder temperature T1: 60≤T1≤70℃;

[0017] The obtaining of the current actual air-powder temperature includes:

[0018] The temperature monitored by the temperature sensor arranged on the primary air and powder pipeline at the outlet of the coal mill is obtained.

[0019] Optionally, determining whether to adjust the regulating valve of the hot primary air side flue according to the opening and closing state of the cold primary air door and the difference between the target air powder temperature and the current actual air powder temperature includes:

[0020] When the difference between the target air powder temperature and the current actual air powder temperature is greater than 0, and the opening and closing state of the cold primary air door is open, close the cold primary air door and adjust the regulating valve of the hot primary air side flue;

[0021] When the difference between the target air powder temperature and the current actual air powder temperature is greater than 0, and the opening and closing state of the cold primary air door is closed, the regulating valve of the hot primary air side flue is adjusted;

[0022] When the difference between the target air-powder temperature and the actual air-powder temperature is equal to 0, and the opening and closing state of the cold primary air door is open, the cold primary air door is closed, and the regulating valve of the hot primary air side flue is adjusted.

[0023] Optionally, the regulating valve of the hot primary air side flue is adjusted, including:

[0024] After determining that the cold primary air door is in a closed state, obtaining the target hot air temperature at the coal mill inlet and the flue gas flow rate on the hot primary air side;

[0025] The opening of the regulating valve of the flue on the hot primary air side is obtained according to the target hot air temperature at the coal mill inlet and the flue gas flow rate on the hot primary air side.

[0026] Optionally, obtaining the target temperature of hot air at the coal mill inlet includes:

[0027] Obtain the first heat absorbed or released when the temperature of the raw coal at the coal mill inlet changes from a first temperature value to a second temperature value in unit time; the first temperature value is the temperature value of the target air-powder temperature at the coal mill outlet; the second temperature value is the temperature value of the raw coal at the coal mill inlet;

[0028] Obtaining a second amount of heat absorbed or released when the temperature of the total sealed air at the coal mill inlet changes from a first temperature value to a third temperature value in a unit time; wherein the third temperature value is the temperature value of the total sealed air at the coal mill inlet;

[0029] Obtaining a first average constant-pressure specific heat of the hot air at the inlet of the coal mill when the temperature of the hot air at the inlet ranges from a fourth temperature value to a first temperature value and obtaining a mass flow rate of the hot air at the inlet of the coal mill; the fourth temperature value is a temperature value of a target temperature of the hot air at the inlet of the coal mill;

[0030] The temperature value of the target temperature of the hot air at the coal mill inlet is obtained according to the first heat, the second heat, the first average constant-pressure specific heat and the mass flow rate of the hot air at the inlet.

[0031] Optionally, obtaining the target temperature of hot air at the coal mill inlet includes:

[0032] The target temperature of hot air at the coal mill inlet is T 11 =T 11 =[C 12 ×M 12 ×(T1-T 12 )+C 13 ×M 13 ×(T1-T 13 )] / (C 11 ×M 11 )+T1;

[0033] Among them, C 12 The temperature of raw coal at the inlet of coal mill is T 12 Average constant pressure specific heat to T1, kJ / (kg·K); M 12 is the mass flow rate of raw coal at the coal mill inlet, kg / s; T1 is the target air-powder temperature at the coal mill outlet, °C; T 12 is the temperature of raw coal at the inlet of coal mill, ℃; 13 The temperature of the total sealing air at the coal mill inlet is given by T 13 Average constant pressure specific heat to T1, kJ / (kg·K); M 13 is the mass flow rate of the total sealing air at the coal mill inlet, kg / s; T 13 is the temperature of the total sealing air at the coal mill inlet, ℃; 11 The temperature of the hot air at the coal mill inlet is T 11 Average constant pressure specific heat to T1, kJ / (kg·K); M 11 is the mass flow rate of hot air at the coal mill inlet, kg / s.

[0034] Optionally, obtaining the flue gas flow rate on the hot primary air side includes:

[0035] Obtain the third amount of heat absorbed or released when the temperature of the hot air at the coal mill inlet changes from the fourth temperature value to the fifth temperature value within a unit time; the fourth temperature value is the temperature value of the cold air temperature of the hot primary air duct at the coal mill inlet; the fifth temperature value is the temperature value of the target temperature of the hot air at the coal mill inlet;

[0036] Obtaining a second average constant-pressure specific heat of the flue gas temperature at the hot primary air side of the coal mill inlet from a sixth temperature value to a seventh temperature value and a first temperature difference between the sixth temperature value and the seventh temperature value; wherein the sixth temperature value is the temperature value of the flue gas inlet temperature at the hot primary air side of the coal mill inlet, and the seventh temperature value is the temperature value of the flue gas outlet temperature at the hot primary air side of the coal mill inlet;

[0037] The flue gas flow rate on the hot primary air side is obtained according to the third heat, the second average constant-pressure specific heat and the first temperature difference.

[0038] Optionally, obtaining the flue gas flow rate on the hot primary air side includes:

[0039] The flue gas flow rate M on the hot primary air side fg For: M fg =[C 14 ×M 11 ×(T 11 -T 14 )] / [C fg ×(T fg,en -T fg,lv )];

[0040] Among them, C 14 The temperature of the hot air at the coal mill inlet is T 14 To T 11 Average constant pressure specific heat, kJ / (kg·K); M 11 is the mass flow rate of hot air at the coal mill inlet, kg / s; T 11 is the target temperature of hot air at the coal mill inlet, °C; T 14 is the cold air temperature of the hot primary air duct at the coal mill inlet, ℃; C fg The flue gas temperature at the hot primary air side of the coal mill inlet is T fg,en To T fg,lv Average specific heat at constant pressure, kJ / (kg·K); T fg,en T is the flue gas temperature at the hot primary air side of the coal mill inlet, °C; fg,lv is the flue gas temperature at the flue gas outlet on the hot primary air side of the coal mill inlet, ℃.

[0041] Optionally, obtaining the opening of the regulating valve of the hot primary air side flue includes:

[0042] Obtaining a second flue gas flow rate, where the second flue gas flow rate is a designed total flue gas flow rate corresponding to a 100% opening of a flue gas regulating valve on the hot primary air side of a coal mill inlet;

[0043] The opening degree of the regulating valve of the flue on the hot primary air side is obtained according to the flue gas flow rate on the hot primary air side, the second flue gas flow rate and the correction coefficient.

[0044] Optionally, obtaining the opening of the regulating valve of the hot primary air side flue includes:

[0045] The opening degree η of the regulating valve of the hot primary air side flue is: η=k×M fg / M fg,all ;

[0046] Wherein, k is the correction coefficient; fg,all It is the total designed flue gas flow rate corresponding to the opening of the flue gas regulating valve on the hot primary air side of the coal mill inlet is 100%, kg / s.

[0047] The air-powder temperature control method provided in the embodiment of the present invention regulates the opening of the regulating valve of the hot primary air side flue, directly regulates the temperature of the hot air introduced into the coal mill, eliminates the amount of cold air introduced into the hot air, reduces the heat loss of the temperature control system, and improves the air-powder temperature control effect.

[0048] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0050] Figure 1 It is a structural schematic diagram of a coal mill air-powder temperature control system provided by an embodiment of the present invention;

[0051] Figure 2 It is a flow chart of a method for controlling air-powder temperature provided by an embodiment of the present invention;

[0052] Figure 3 It is a flow chart of a method for controlling air-powder temperature provided by an embodiment of the present invention;

[0053] Figure 4 It is a flow chart of a method for obtaining a target temperature of hot air at a coal mill inlet provided by an embodiment of the present invention;

[0054] Figure 5 It is a flow chart of a method for obtaining the flue gas flow rate on the hot primary air side provided by an embodiment of the present invention;

[0055] Figure 6 It is a flow chart of a method for obtaining the opening degree of a regulating valve of a hot primary air side flue provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0057] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0058] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0059] Figure 1 Schematic diagram of the structure of a coal mill air and powder temperature control system provided by an embodiment of the present invention. Figure 1 As shown, the system includes: coal mill body 01, hot primary air duct 02, cold primary air duct 03 and hot primary air side flue 04. The arrows are the directions of flow of hot primary air side flue gas, cold air or hot air.

[0060] like Figure 1As shown, the cold air flows into the hot primary air duct 02 through the cold air inlet 021, and is converted into hot air by heat exchange with the flue gas of the hot primary air side flue 04 in the heat exchanger 042 of the hot primary air side flue at the intersection of the hot primary air duct 02 and the hot primary air side flue 04, and is then sent into the coal mill body 01 through the coal mill inlet 011. The hot primary air side flue 04 has a regulating valve 041 of the hot primary air side flue for adjusting the flue gas volume in the hot primary air side flue 04 to control the hot air temperature flowing into the coal mill inlet 011. The hot primary air side flue 04 has a hot primary air side flue flue flue gas inlet 043 for flowing into the hot primary air side flue flue for heat exchange with the cold air in the hot primary air duct 02. The hot primary air side flue 04 also has a hot primary air side flue flue gas outlet 044 for discharging the hot primary air side flue gas after heat exchange with the cold air in the hot primary air duct 02 in the hot primary air side flue.

[0061] A cold primary air door 031 is provided in the cold primary air duct 03 , and the cold primary air door 031 is used to adjust the amount of cold air flowing from the cold primary air duct 03 into the coal mill inlet 011 .

[0062] In the coal mill body 01 , the raw coal is ground, and the ground coal product and the hot air flowing in from the coal mill inlet 011 form an air-powder mixture, which is then discharged from the coal mill body 01 through the coal mill outlet 012 .

[0063] Figure 2 is a flow chart of a method for controlling air-powder temperature provided by an embodiment of the present invention. Figure 1 and Figure 2 As shown, the air-powder temperature is the air-powder temperature at the coal mill outlet 012. The air-powder temperature control method includes:

[0064] S101, obtaining the target air-powder temperature at the coal mill outlet and the current actual air-powder temperature at the coal mill outlet.

[0065] For example, the target air-powder temperature at the outlet of the coal mill is related to the equipment and coal quality: for a direct-blowing pulverizing system using a medium-speed coal mill, the control requirements for the target air-powder temperature (T) at the outlet of the coal mill are as follows: when the dry ash-free volatile matter Vdaf of the coal entering the mill is <40%, T = [(82-Vdaf)×5 / 3]±5°C; when Vdaf≥40%, T = 60~70°C.

[0066] The current actual air and powder temperature at the coal mill outlet is the current actual air and powder temperature collected by the temperature sensor set at the coal mill outlet 012. Due to the difference in coal quality or coal mill system type, the target air and powder temperature at the coal mill outlet will be different, and the current actual air and powder temperature at the coal mill outlet will also be different from the target air and powder temperature. Therefore, the current actual air and powder temperature value at the coal mill outlet is adjusted so that the current actual air and powder temperature value is equal to the target air and powder temperature value to ensure that the air and powder temperature at the coal mill outlet meets the actual demand.

[0067] S102, obtaining the opening and closing state of the cold primary air damper at the coal mill inlet; determining whether to adjust the regulating valve of the hot primary air side flue according to the opening and closing state of the cold primary air damper and the difference between the target air powder temperature and the current actual air powder temperature.

[0068] Specifically, when the difference between the target air-powder temperature and the current actual air-powder temperature is greater than 0, it means that the hot air currently introduced into the coal mill coal grinding products does not meet the actual demand. Therefore, it is necessary to adjust the hot air temperature input to the coal mill body 01 to dry and transfer the coal grinding products more efficiently.

[0069] At the same time, the opening and closing state of the cold primary air door 031 is also obtained to determine whether to adjust the hot air temperature. When the cold primary air door 031 is in the open state, it means that cold air is mixed in the air powder temperature control system at this time. Even if the target air powder temperature is equal to the current actual air powder temperature at this time, that is, the hot air has met the actual needs of the coal mill, but because cold air is mixed in the air powder temperature control system to control the hot air temperature, the cold air is heat exchanged with the heat exchanger 042 of the hot primary air side flue to heat up, and then mixed with the cold air input by the cold primary air duct 03 to cool down. In this process, there is a part of heat loss in the temperature control of the hot air. At this time, close the cold primary air door 031 to stop the mixing of cold air, then the hot air temperature input to the coal mill inlet 011 will increase, and the current actual air powder temperature will also increase, and the current actual air powder temperature will continue to be temperature regulated. Therefore, when the opening and closing state of the cold primary air door 031 is obtained to be open, it is determined that the regulating valve of the hot primary air side flue needs to be adjusted.

[0070] When the current open / close state of the cold primary air door 031 is closed, and the difference between the target air-powder temperature and the current actual air-powder temperature is equal to 0, it means that the hot air temperature used to dry and transfer the pulverized coal products meets the actual demand, and there is no cold air mixed in the air-powder temperature control system. There is no large amount of heat loss in the hot air temperature control process in the hot primary air duct 02. At this time, the air-powder temperature control system does not need to control the air-powder temperature.

[0071] The hot flue gas enters the hot primary air flue 04 through the flue gas inlet 043 of the hot primary air flue, and after the flue gas flow is adjusted by the regulating valve 041 of the hot primary air flue, it flows into the heat exchanger 042 of the hot primary air flue. The heat exchanger 042 of the hot primary air flue is located at the intersection of the hot primary air flue 04 and the hot primary air duct 02. The cold air flows into the cold air inlet 021 of the hot primary air duct 02, and the cold air exchanges heat with the flue gas in the hot primary air flue 04 at the heat exchanger 042 of the hot primary air flue. The temperature of the cold air in the hot primary air duct 02 rises after passing through the heat exchanger 042 of the hot primary air flue, and the heated hot air flows into the coal mill through the coal mill inlet 011.

[0072] If the air-powder temperature needs to be regulated, in the hot primary air flue 04, the flue gas flow in the hot primary air flue 04 is regulated by adjusting the valve opening and closing size of the regulating valve 041 of the hot primary air flue. The smaller the flue gas flow in the hot primary air flue 04, the smaller the flue gas flow for heat exchange with the cold air of the hot primary air duct 02 in the heat exchanger 042 of the hot primary air flue. In this way, the temperature of the hot air input into the coal mill body in the hot primary air duct 02 is regulated so that the current actual air-powder temperature at the coal mill outlet is equal to the target air-powder temperature.

[0073] Optionally, the hot primary air side flue gas inlet 043 receives hot flue gas generated by the air preheater.

[0074] Optionally, the hot primary air side flue heat exchanger 042 can provide heat sources for heat exchange through hot water and hot air at the same time, and finely adjust the flue gas temperature of the hot primary air side flue by adjusting the flue gas flow rate of the hot air. The specific heat source form of the hot primary air side flue heat exchanger 042 is not limited here.

[0075] S103, when adjusting the regulating valve of the hot primary air side flue, obtaining the first opening of the regulating valve of the hot primary air side flue; and adjusting the regulating valve of the hot primary air side flue according to the first opening.

[0076] Specifically, when it is determined that the regulating valve of the hot primary air side flue needs to be adjusted, the first opening is obtained. When the current actual air and powder temperature at the outlet of the coal mill is adjusted to be equal to the target air and powder temperature, the current actual air and powder temperature is related to the hot air temperature of the hot primary air duct 02. Therefore, adjusting the opening of the regulating valve 041 of the hot primary air side flue to control the size of the flue gas flow in the hot primary air side flue 04 for heat exchange with the hot primary air duct 02 can adjust the current actual air and powder temperature at the outlet of the coal mill.

[0077] Optionally, the first opening degree is obtained by establishing an equivalent relationship between the heat absorption or heat release of each part of the system. In the coal mill body, the target temperature T of the hot air at the coal mill inlet when the cold air is mixed in the full closure is calculated according to the law of conservation of heat. 11 At the heat exchanger 042 of the hot primary air flue, the flue gas flow M on the hot primary air side is calculated according to the law of conservation of heat. fg According to the flue gas flow M on the hot primary air side fg Calculate the first opening of the regulating valve of the flue on the hot primary air side.

[0078] The embodiment of the present invention provides an air-powder temperature control method, which determines whether it is necessary to adjust the regulating valve of the hot primary air side flue according to the air-powder temperature at the coal mill outlet and the opening and closing state of the cold primary air door, so as to adjust the current actual air-powder temperature at the coal mill outlet to the target air-powder temperature. When adjusting the current actual air-powder temperature at the coal mill outlet, the cold primary air door is closed, so that in the air-powder temperature control method, the hot air temperature is only adjusted according to the opening of the regulating valve of the hot primary air side flue. The air-powder temperature control method provided by the present invention regulates the opening of the regulating valve of the hot primary air side flue, directly adjusts the temperature of the hot air entering the coal mill, eliminates the amount of cold air entering the hot air, reduces the heat loss of the temperature control system, and improves the air-powder temperature control effect.

[0079] In combination with the above embodiment, obtaining the target air-powder temperature at the coal mill outlet includes: when the coal quality in the coal mill changes, determining the target air-powder temperature according to the coal quality; the coal quality includes the dry ash-free volatile matter of the coal quality; wherein, when the coal mill is a medium-speed coal mill, the dry ash-free volatile matter V daf <40%, then the target air powder temperature T1=[(82-V daf )×5 / 3]±5℃; Dry ash-free volatile matter V of coal daf ≥40%, the target air powder temperature T1: 60≤T1≤70℃; where V daf V is the dry ash-free volatile matter of coal; when the coal mill is a low-speed coal mill, the dry ash-free volatile matter of coal is 10% < V daf ≤20%, then the target air powder temperature T1: 100≤T1≤130℃; dry ash-free volatile matter of coal quality 20%<V daf <40%, then the target air-powder temperature T1: 70≤T1≤90℃; the dry ash-free volatile matter V daf ≥40%, the target air powder temperature T1: 60≤T1≤70℃.

[0080] Specifically, the target air-powder temperature at the coal mill outlet is related to the coal quality in the coal mill and the type of coal mill.

[0081] Among them, coal quality parameters include dry ash-free volatile matter (V daf ), has a significant impact on the outlet temperature of the coal mill. Volatile matter is the sum of gaseous and liquid products released by coal during the heating process, which reflects the combustion performance and explosiveness of coal. Coal with high volatile matter is easy to burn, but too high volatile matter may cause coal powder to spontaneously combust or explode at a lower temperature. Therefore, for coal with high volatile matter, it is necessary to appropriately reduce the outlet temperature of the coal mill to prevent spontaneous combustion and explosion. The explosiveness of coal powder is related to factors such as its particle size, volatile matter and moisture. For explosive coal types, strictly controlling the outlet temperature of the coal mill is one of the important measures to prevent explosions.

[0082] In addition, different types of coal mills differ in their working principles, structures, and performances, and these differences will affect the setting of the coal mill outlet temperature. Medium-speed coal mills are usually used to grind medium-hard coals such as bituminous coal and anthracite. The setting of its outlet temperature needs to take into account factors such as the dryness, combustion performance, and explosiveness of the coal powder. For coals with low volatility, the outlet temperature can be appropriately increased to promote the drying and combustion of the coal powder; while for coals with high volatility, the outlet temperature needs to be lowered to prevent spontaneous combustion and explosion. Slow-speed coal mills are mainly used to grind low-hardness and high-moisture coals such as lignite. For low-volatile coal quality in low-speed coal mills, a separate control gradient needs to be set to ensure that the raw coal can be accurately dried.

[0083] Therefore, in the air-powder temperature control method provided in the embodiment of the present invention, the target air-powder temperature is determined according to different types of coal mills and different volatile matters of coal quality.

[0084] Specifically, when the coal mill type is a medium-speed coal mill, two interval thresholds can be set for the dry ash-free volatile matter of the coal quality. daf <40%, then the target air powder temperature T1=[(82-V daf )×5 / 3]±5℃. When the dry ash-free volatile matter is large, the target air-powder temperature needs to be reduced accordingly, and the target air-powder temperature T1 is set to 60≤T1≤70℃.

[0085] When the coal mill is a low-speed coal mill, three target air-powder temperature intervals are set according to the dry ash-free volatile matter of the coal quality to achieve precise adjustment of the target air-powder temperature to ensure the combustion performance and safety of the coal.

[0086] Combining the above embodiments and Figure 1 As shown, obtaining the current actual air-powder temperature includes: obtaining the temperature monitored by a temperature sensor set in the primary air-powder pipeline at the outlet of the coal mill.

[0087] For example, a temperature sensor is installed in the primary air-powder duct at the coal mill outlet 012. The temperature signal collected by the temperature sensor is input into the temperature controller for processing and judgment using a pre-set advanced and reasonable temperature control algorithm (proportional control or PID control).

[0088] Optionally, a feedback control method is provided to continuously monitor the current actual air-powder temperature change of the air-powder at the coal mill outlet 012 through a temperature sensor, compare it with the target air-powder temperature calculated according to the coal quality of the coal mill, and adjust the regulating valve 041 of the flue on the hot primary air side according to the comparison result to adjust the hot air temperature, so as to achieve dynamic consistency between the current actual air-powder temperature and the target air-powder temperature.

[0089] Figure 3 is a flow chart of a method for controlling air-powder temperature provided by an embodiment of the present invention, such as Figure 3 In combination with the above embodiment, whether to adjust the regulating valve of the hot primary air side flue is determined according to the opening and closing state of the cold primary air door and the difference between the target air powder temperature and the current actual air powder temperature, including:

[0090] When the difference between the target air powder temperature and the current actual air powder temperature is greater than 0, and the opening and closing state of the cold primary air damper is open, close the cold primary air damper and adjust the regulating valve of the flue on the hot primary air side; when the difference between the target air powder temperature and the current actual air powder temperature is greater than 0, and the opening and closing state of the cold primary air damper is closed, adjust the regulating valve of the flue on the hot primary air side; when the difference between the target air powder temperature and the actual air powder temperature is equal to 0, and the opening and closing state of the cold primary air damper is open, close the cold primary air damper and adjust the regulating valve of the flue on the hot primary air side.

[0091] Specifically, determine the difference between the target air-powder temperature and the current actual air-powder temperature. When the difference is greater than 0, the current actual air-powder temperature needs to be adjusted, indicating that the currently input hot air does not meet the raw coal drying requirements in the coal mill. Further determine the open and closed state of the cold primary air door 031: when the cold primary air door 031 is in an open state, it means that cold air is mixed into the coal mill body at this time, then first close the cold primary air door 031 and then adjust the regulating valve of the hot primary air side flue; if the cold primary air door 031 is in a closed state, it means that no cold air is mixed into the coal mill body at this time, and the regulating valve of the hot primary air side flue can be directly adjusted.

[0092] When it is determined that the difference between the target air-powder temperature and the current actual air-powder temperature is equal to 0, it means that the hot air temperature input into the coal mill body at this time has met the requirements for raw coal drying. However, if the cold primary air door 031 is in an open state at this time, it means that cold air is mixed into the coal mill body, which will cause a part of the heat loss of the air-powder temperature control system. Therefore, the opening and closing state of the cold primary air door 031 is further determined: when the cold primary air door 031 is in an open state, it means that cold air is mixed into the coal mill body at this time, and the cold primary air door 031 is closed first. At this time, the hot air temperature may rise, so that the current actual air-powder temperature is inconsistent with the target air-powder temperature, and the regulating valve of the hot primary air side flue is adjusted. When the cold primary air door 031 is in a closed state, it means that the air-powder temperature control effect without cold air mixing has been achieved at this time, and no further adjustment is required.

[0093] The air-powder temperature control method provided by the embodiment of the present invention determines whether to adjust the regulating valve of the flue on the hot primary air side, and determines the measures to be adopted in the process of adjusting the valve opening, by comprehensively judging the difference between the target air-powder temperature and the actual temperature and the opening and closing state of the cold primary air door. The air-powder temperature control method provided by the embodiment of the present invention eliminates the amount of cold air introduced into the hot air and reduces the heat loss of the temperature control system.

[0094] In combination with the above embodiment, the regulating valve of the hot primary air side flue is adjusted, including:

[0095] After determining that the cold primary air door is in the closed state, obtain the target hot air temperature at the coal mill inlet and the flue gas flow on the hot primary air side; obtain the opening of the regulating valve of the hot primary air side flue according to the target hot air temperature at the coal mill inlet and the flue gas flow on the hot primary air side.

[0096] Specifically, in the air-powder temperature control method provided by the embodiment of the present invention, when adjusting the current actual air-powder temperature, the cold primary air door 031 is closed, that is, there is no cold air in the temperature control method. Therefore, the flue gas flow in the hot primary air flue 04 is adjusted by adjusting the opening of the regulating valve 041 of the hot primary air flue. When the flue gas flow in the hot primary air flue 04 is large, the higher the degree of heat exchange with the cold air input in the hot primary air duct 02, the higher the hot air temperature input to the coal mill body 01 by the hot primary air duct 02, and thus the current actual air-powder temperature is also higher; when the flue gas flow in the hot primary air flue 04 is small, the lower the degree of heat exchange with the cold air input in the hot primary air duct 02, the lower the hot air temperature input to the coal mill body 01 by the hot primary air duct 02, and thus the current actual air-powder temperature is also lower. In this way, the current actual air-powder temperature is adjusted. After obtaining the target air and powder temperature at the coal mill outlet, obtain the target hot air temperature at the coal mill inlet according to the target air and powder temperature, and the flue gas flow rate on the hot primary air side required for heat exchange when the hot air reaches the target temperature. Obtain the opening of the regulating valve on the hot primary air side flue according to the target hot air temperature at the coal mill inlet and the flue gas flow rate on the hot primary air side.

[0097] Figure 4 is a flow chart of a method for obtaining a target temperature of hot air at a coal mill inlet provided by an embodiment of the present invention. Figure 4 As shown, the target temperature of hot air at the coal mill inlet is obtained, including:

[0098] S201, obtaining a first amount of heat absorbed or released when the temperature of raw coal at an inlet of a coal mill changes from a first temperature value to a second temperature value within a unit time.

[0099] Among them, the first temperature value is the temperature value of the target air-powder temperature at the outlet of the coal mill; the second temperature value is the temperature value of the raw coal at the inlet of the coal mill.

[0100] S202, obtaining a second amount of heat absorbed or released when the temperature of the total sealing air at the coal mill inlet changes from a first temperature value to a third temperature value within a unit time.

[0101] Among them, the third temperature value is the temperature value of the total sealing air at the coal mill inlet;

[0102] S203, obtaining a first average constant-pressure specific heat of the hot air at the inlet of the coal mill when the temperature of the hot air is from the fourth temperature value to the first temperature value and obtaining a mass flow rate of the hot air at the inlet of the coal mill.

[0103] The fourth temperature value is the target temperature of the hot air at the coal mill inlet;

[0104] S204, obtaining a temperature value of a target temperature of the hot air at an inlet of the coal mill according to the first heat amount, the second heat amount, the first average constant-pressure specific heat, and the mass flow rate of the inlet hot air.

[0105] For example, the target temperature of hot air at the coal mill inlet is T 11 =T 11 =[C 12 ×M 12 ×(T1-T 12 )+C 13 ×M 13 ×(T1-T 13 )] / (C 11 ×M 11 )+T1;

[0106] Among them, C 12 The temperature of raw coal at the inlet of coal mill is T 12 Average constant pressure specific heat to T1, kJ / (kg·K); M 12 is the mass flow rate of raw coal at the coal mill inlet, kg / s; T1 is the target air-powder temperature at the coal mill outlet, °C; T 12 is the temperature of raw coal at the inlet of coal mill, ℃; C13 is the temperature of total sealing air at the inlet of coal mill, which is T 13 Average constant pressure specific heat to T1, kJ / (kg·K); M 13 is the mass flow rate of the total sealing air at the coal mill inlet, kg / s; T 13 is the temperature of the total sealing air at the coal mill inlet, ℃; C 11 The temperature of the hot air at the coal mill inlet is T 11 Average constant pressure specific heat to T1, kJ / (kg·K); M 11 is the mass flow rate of hot air at the coal mill inlet, kg / s.

[0107] Specifically, in the air-powder temperature control method provided in the embodiment of the present invention, an equivalent relationship can be obtained according to heat balance and material working medium balance: C 11 ×M 11 ×(T 11 -T1)=[C 12 ×M 12 ×(T1-T 12 )+C 13 ×M 13 ×(T1-T 13 )]. That is: [The hot air from the coal mill inlet is from T 11 to T1] = [the temperature of raw coal at the inlet of the pulverizer is T 12 to T1] + [the temperature of the total sealing air at the coal mill inlet is T 13 to T1].

[0108] In the coal mill, hot air carries heat into the coal mill to dry and heat the raw coal. The raw coal is ground into coal powder in the coal mill and absorbs heat to increase the temperature. At the same time, the sealing air also absorbs a certain amount of heat. Finally, the air-powder mixture at the coal mill outlet reaches a target temperature T1. Hot air enters the coal mill inlet (temperature T 11 ) enters, and after heat energy exchange with raw coal and sealing air, the temperature drops to the outlet temperature T1. In this process, the hot air releases heat. 12 Entering the coal mill, it absorbs the heat of the hot air during the grinding process, and the temperature rises to the outlet temperature T1. In this process, the raw coal absorbs heat. The sealing air is at a temperature of T 13 When it enters the coal mill, it also absorbs the heat of the hot air and its temperature rises to the outlet temperature T1. Therefore, according to the above equivalent relationship, the target temperature of the hot air at the coal mill inlet can be obtained when the current real-time air-powder temperature meets the target air-powder temperature at the coal mill outlet.

[0109] Figure 5 is a flow chart of a method for obtaining the flue gas flow rate on the hot primary air side provided by an embodiment of the present invention, such as Figure 5 As shown, the flue gas flow rate on the hot primary air side is obtained, including:

[0110] S301, obtaining a third amount of heat absorbed or released when the temperature of the hot air at the coal mill inlet changes from a fourth temperature value to a fifth temperature value within a unit time.

[0111] Among them, the fourth temperature value is the temperature value of the cold air temperature of the hot primary air duct at the coal mill inlet; the fifth temperature value is the temperature value of the hot air target temperature at the coal mill inlet.

[0112] S302, obtaining a second average constant-pressure specific heat of the flue gas temperature at the hot primary air side of the coal mill inlet from a sixth temperature value to a seventh temperature value and a first temperature difference between the sixth temperature value and the seventh temperature value.

[0113] The sixth temperature value is the temperature value of the flue gas inlet temperature on the hot primary air side of the coal mill inlet, and the seventh temperature value is the temperature value of the flue gas outlet temperature on the hot primary air side of the coal mill inlet.

[0114] S303, obtaining the flue gas flow rate on the hot primary air side according to the third heat, the second average constant-pressure specific heat and the first temperature difference.

[0115] For example, the flue gas flow rate M on the hot primary air side is fg For: M fg =[C 14 ×M 11 ×(T 11 -T 14 )] / [C fg ×(T fg,en -Tfg,lv )];

[0116] Among them, C 14 The temperature of the hot air at the coal mill inlet is T 14 To T 11 Average constant pressure specific heat, kJ / (kg·K); M 11 is the mass flow rate of hot air at the coal mill inlet, kg / s; T 11 is the target temperature of hot air at the coal mill inlet, °C; T 14 is the cold air temperature of the hot primary air duct at the coal mill inlet, ℃; C fg The flue gas temperature at the hot primary air side of the coal mill inlet is T fg,en To T fg,lv Average specific heat at constant pressure, kJ / (kg·K); T fg,en T is the flue gas temperature at the hot primary air side of the coal mill inlet, °C; fg,lv is the flue gas temperature at the flue gas outlet on the hot primary air side of the coal mill inlet, ℃.

[0117] Specifically, in the air-powder temperature control method provided in the embodiment of the present invention, the following equivalent relationship can be obtained: C fg ×M fg ×(T fg,en -T fg,lv )=C 14 ×M 11 ×(T 11 -T 14 ). That is: [The hot air in the hot air duct at the coal mill inlet changes from temperature T 14 Heating to T 11 The heat required to be absorbed in the process] = [the heat of the flue gas in the heat exchanger in the flue on the hot primary air side M fg From T fg,en To T fg,lv In the air-powder temperature control method provided in the embodiment of the present invention, the hot air exchanges heat with the flue gas through a heat exchanger, thereby being heated to the required temperature. In this process, the heat absorbed by the hot air is equal to the heat released by the flue gas. On the hot air side: the hot air is heated from the temperature T 14 (cold air temperature of hot primary air duct at coal mill inlet) heated to T 11 (target temperature of hot air at coal mill inlet) needs to absorb a certain amount of heat. This heat can be obtained by the average constant pressure specific heat C of the hot air. 14 and mass flow rate M 11 and the temperature difference (T 11 -T 14 ) is used for calculation. On the flue gas side: the flue gas releases heat in the heat exchanger and the temperature rises from T fg,en (The flue gas temperature at the hot primary air side of the coal mill inlet flue gas inlet) is reduced to Tfg,lv (The flue gas temperature at the flue gas outlet on the hot primary air side of the coal mill inlet). In this process, the heat released by the flue gas can also be measured by the average constant pressure specific heat of the flue gas C fg and mass flow rate M fg and the temperature difference (T fg,en -T fg,lv ) is calculated. Based on the relationship that the heat absorbed by the hot air is equal to the heat released by the flue gas, the flue gas flow rate M on the hot primary air side in the hot primary air side flue 04 can be obtained to meet the target temperature of the hot air at the coal mill inlet. fg For how much.

[0118] Figure 6 : is a flow chart of a method for obtaining the opening degree of a regulating valve of a hot primary air side flue provided by an embodiment of the present invention, such as Figure 6 As shown, the opening of the regulating valve of the hot primary air side flue is obtained, including:

[0119] S401, obtaining a second flue gas flow rate.

[0120] The second flue gas flow rate is the total designed flue gas flow rate corresponding to when the opening of the flue gas regulating valve on the hot primary air side of the coal mill inlet is 100%.

[0121] S402, obtaining the opening of the regulating valve of the flue on the hot primary air side according to the flue gas flow rate on the hot primary air side, the second flue gas flow rate and the correction coefficient.

[0122] For example, the opening degree η of the regulating valve of the hot primary air side flue is: η=k×M fg / M fg,all ;

[0123] Where k is the correction factor; M fg,all It is the total designed flue gas flow rate corresponding to the opening of the flue gas regulating valve on the hot primary air side of the coal mill inlet is 100%, kg / s.

[0124] Specifically, the flue gas flow rate M on the hot primary air side fg After the value of is obtained, the opening of the regulating valve 041 of the hot primary air flue is calculated according to the flue gas flow rate on the hot primary air side. Where k is the correction coefficient, which is related to the characteristics of the flue gas regulating valve on the hot primary air side of the coal mill inlet. The value range is generally 0 to 1, which needs to be determined by the actual situation of the equipment and is not limited here. fg,all It is determined based on the design parameters and performance requirements of the coal mill and is not limited here.

[0125] In the air-powder temperature control method provided in the embodiment of the present invention, the hot air target temperature at the coal mill inlet is obtained according to the target air-powder temperature at the coal mill outlet, and then the flue gas flow rate of the hot primary air side in the hot primary air side flue corresponding to the hot air target temperature is obtained. The air-powder temperature is controlled by calculating the valve opening corresponding to the flue gas flow rate. The air-powder temperature is controlled without cold air mixing, and the heat loss of the temperature control system is reduced.

[0126] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling air-powder temperature, wherein the air-powder temperature is the air-powder temperature at the outlet of a coal mill, characterized in that: The method comprises: Obtaining the target air-powder temperature at the coal mill outlet and the current actual air-powder temperature at the coal mill outlet; Obtaining the open / closed state of the cold primary air door at the coal mill inlet; Determining whether to adjust the regulating valve of the hot primary air side flue according to the opening and closing state of the cold primary air door and the difference between the target air powder temperature and the current actual air powder temperature; When adjusting the regulating valve of the hot primary air side flue, obtaining a first opening degree of the regulating valve of the hot primary air side flue; The regulating valve of the hot primary air side flue is adjusted according to the first opening.

2. The air-powder temperature control method according to claim 1, characterized in that: The step of obtaining the target air-powder temperature at the coal mill outlet comprises: When the coal quality in the coal mill changes, the target air-powder temperature is determined according to the coal quality; the coal quality includes dry ash-free volatile matter of the coal; Wherein, when the coal mill is a medium-speed coal mill, the dry ash-free volatile matter V daf <40%, then the target air powder temperature T1=[(82-V daf )×5 / 3]±5℃; Dry ash-free volatile matter V of coal daf ≥40%, the target air powder temperature T1: 60≤T1≤70℃; where V daf It is the dry ash-free volatile matter of coal; When the coal mill is a low-speed coal mill, the dry ash-free volatile matter of the coal is 10%<V daf ≤20%, then the target air powder temperature T1: 100≤T1≤130℃; dry ash-free volatile matter of coal quality 20%<V daf <40%, then the target air-powder temperature T1: 70≤T1≤90℃; the dry ash-free volatile matter V daf ≥40%, then the target air powder temperature T1: 60≤T1≤70℃; The obtaining of the current actual air-powder temperature includes: The temperature monitored by the temperature sensor arranged on the primary air and powder pipeline at the outlet of the coal mill is obtained.

3. The air-powder temperature control method according to claim 1, characterized in that: The determining whether to adjust the regulating valve of the hot primary air side flue according to the opening and closing state of the cold primary air door and the difference between the target air powder temperature and the current actual air powder temperature includes: When the difference between the target air powder temperature and the current actual air powder temperature is greater than 0, and the opening and closing state of the cold primary air door is open, close the cold primary air door and adjust the regulating valve of the hot primary air side flue; When the difference between the target air powder temperature and the current actual air powder temperature is greater than 0, and the opening and closing state of the cold primary air door is closed, the regulating valve of the hot primary air side flue is adjusted; When the difference between the target air-powder temperature and the actual air-powder temperature is equal to 0, and the opening and closing state of the cold primary air door is open, the cold primary air door is closed, and the regulating valve of the hot primary air side flue is adjusted.

4. The air-powder temperature control method according to claim 3, characterized in that: The regulating valve of the hot primary air side flue is adjusted, including: After determining that the cold primary air door is in a closed state, obtaining the target hot air temperature at the coal mill inlet and the flue gas flow rate on the hot primary air side; The opening of the regulating valve of the flue on the hot primary air side is obtained according to the target hot air temperature at the coal mill inlet and the flue gas flow rate on the hot primary air side.

5. The air-powder temperature control method according to claim 4, characterized in that: The step of obtaining the target hot air temperature at the coal mill inlet comprises: Obtain the first heat absorbed or released when the temperature of the raw coal at the coal mill inlet changes from a first temperature value to a second temperature value in unit time; the first temperature value is the temperature value of the target air-powder temperature at the coal mill outlet; the second temperature value is the temperature value of the raw coal at the coal mill inlet; Obtaining a second amount of heat absorbed or released when the temperature of the total sealed air at the coal mill inlet changes from a first temperature value to a third temperature value in a unit time; wherein the third temperature value is the temperature value of the total sealed air at the coal mill inlet; Obtaining a first average constant-pressure specific heat of the hot air at the inlet of the coal mill when the temperature of the hot air at the inlet ranges from a fourth temperature value to a first temperature value and obtaining a mass flow rate of the hot air at the inlet of the coal mill; the fourth temperature value is a temperature value of a target temperature of the hot air at the inlet of the coal mill; The temperature value of the target temperature of the hot air at the coal mill inlet is obtained according to the first heat, the second heat, the first average constant-pressure specific heat and the mass flow rate of the hot air at the inlet.

6. The air-powder temperature control method according to claim 5, characterized in that: The step of obtaining the target hot air temperature at the coal mill inlet comprises: The target temperature of hot air at the coal mill inlet is T 11 =T 11 =[C 12 ×M 12 ×(T1-T 12 )+C 13 ×M 13 ×(T1-T 13 )] / (C 11 ×M 11 )+T1; Among them, C 12 The temperature of raw coal at the inlet of coal mill is T 12 Average constant pressure specific heat to T1, kJ / (kg·K); M 12 is the mass flow rate of raw coal at the coal mill inlet, kg / s; T1 is the target air-powder temperature at the coal mill outlet, °C; T 12 is the temperature of raw coal at the inlet of coal mill, ℃; 13 The temperature of the total sealing air at the coal mill inlet is given by T 13 Average constant pressure specific heat to T1, kJ / (kg·K); M 13 is the mass flow rate of the total sealing air at the coal mill inlet, kg / s; T 13 is the temperature of the total sealing air at the coal mill inlet, ℃; C 11 The temperature of the hot air at the coal mill inlet is T 11 Average constant pressure specific heat to T1, kJ / (kg·K); M 11 is the mass flow rate of hot air at the coal mill inlet, kg / s.

7. The air-powder temperature control method according to claim 4, characterized in that: The obtaining of the flue gas flow rate on the hot primary air side includes: Obtain the third amount of heat absorbed or released when the temperature of the hot air at the coal mill inlet changes from the fourth temperature value to the fifth temperature value within a unit time; the fourth temperature value is the temperature value of the cold air temperature of the hot primary air duct at the coal mill inlet; the fifth temperature value is the temperature value of the target temperature of the hot air at the coal mill inlet; Obtaining a second average constant-pressure specific heat of the flue gas temperature at the hot primary air side of the coal mill inlet from a sixth temperature value to a seventh temperature value and a first temperature difference between the sixth temperature value and the seventh temperature value; wherein the sixth temperature value is the temperature value of the flue gas inlet temperature at the hot primary air side of the coal mill inlet, and the seventh temperature value is the temperature value of the flue gas outlet temperature at the hot primary air side of the coal mill inlet; The flue gas flow rate on the hot primary air side is obtained according to the third heat, the second average constant-pressure specific heat and the first temperature difference.

8. The air-powder temperature control method according to claim 7, characterized in that: The obtaining of the flue gas flow rate on the hot primary air side includes: The flue gas flow rate M on the hot primary air side fg For: M fg =[C 14 ×M 11 ×(T 11 -T 14 )] / [C fg ×(T fg,en -T fg,lv )]; Among them, C 14 The temperature of the hot air at the coal mill inlet is T 14 To T 11 Average constant pressure specific heat, kJ / (kg·K); M 11 is the mass flow rate of hot air at the coal mill inlet, kg / s; T 11 is the target temperature of hot air at the coal mill inlet, °C; T 14 is the cold air temperature of the hot primary air duct at the coal mill inlet, ℃; C fg The flue gas temperature at the hot primary air side of the coal mill inlet is T fg,en To T fg,lv Average specific heat at constant pressure, kJ / (kg·K); T fg,en T is the flue gas temperature at the hot primary air side of the coal mill inlet, °C; fg,lv is the flue gas temperature at the flue gas outlet on the hot primary air side of the coal mill inlet, ℃.

9. The air-powder temperature control method according to claim 4, characterized in that: The obtaining of the opening of the regulating valve of the hot primary air side flue comprises: Obtaining a second flue gas flow rate, where the second flue gas flow rate is a designed total flue gas flow rate corresponding to a 100% opening of a flue gas regulating valve on the hot primary air side of a coal mill inlet; The opening degree of the regulating valve of the flue on the hot primary air side is obtained according to the flue gas flow rate on the hot primary air side, the second flue gas flow rate and the correction coefficient.

10. The air-powder temperature control method according to claim 9, characterized in that: The obtaining of the opening of the regulating valve of the hot primary air side flue comprises: The opening degree η of the regulating valve of the hot primary air side flue is: η=k×M fg / M fg,all ; Wherein, k is the correction coefficient; fg,all It is the total designed flue gas flow rate corresponding to the opening of the flue gas regulating valve on the hot primary air side of the coal mill inlet is 100%, kg / s.

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