A system for increasing the primary air temperature at the outlet of a medium speed coal mill

Abstract

The present application relates to the field of coal-fired boiler energy-saving technology, in particular to a system for improving the primary air temperature at the outlet of a medium-speed coal mill, comprising an air preheater, a medium-speed coal mill and a furnace, the hot air at the outlet of the air preheater is divided into two parts, i.e. hot air for grinding and bypass hot air, and the powder-containing air at the outlet of the medium-speed coal mill is mixed with the bypass hot air and then sent to the furnace. The design of the bypass hot air can greatly increase the primary air temperature entering the boiler, thereby ensuring the stability of the boiler combustion and the burnout of the coal powder, and further improving the combustion efficiency of the boiler, reducing the exhaust gas temperature, improving the efficiency of the boiler and the economy of the boiler.

Description

Technical Field

[0001] The invention relates to the technical field of energy-saving of coal-fired boilers, and in particular to a system for increasing the temperature of primary air at the outlet of a medium-speed coal mill. Background Art

[0002] In order to reduce coal consumption of coal-fired power units and improve economic efficiency, it is necessary to reduce the power consumption rate of the entire plant as much as possible. The coal mill is a high-energy-consuming equipment in the entire coal-fired power plant. Reducing the power consumption of the coal mill can effectively improve the economic efficiency of the entire plant.

[0003] In addition, the higher the temperature of the primary air entering the boiler, the more stable the combustion in the boiler and the better the burnout of the pulverized coal, which is beneficial to improving the combustion efficiency of the boiler, while reducing the exhaust gas temperature, improving the boiler efficiency and improving the economy;

[0004] Taking all the above-mentioned problems into consideration, the present invention invents a system for increasing the temperature of primary air at the outlet of a medium-speed coal mill, so as to improve boiler efficiency and enhance economy. Summary of the Invention

[0005] The present invention provides a system for increasing the temperature of primary air at the outlet of a medium-speed coal mill, so as to solve the technical problems raised by the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention discloses a system for improving the temperature of primary air at the outlet of a medium-speed coal mill, comprising an air preheater, a medium-speed coal mill and a furnace. The hot air at the outlet of the air preheater is divided into two parts: over-grinding hot air and bypass hot air. The powder-laden air at the outlet of the medium-speed coal mill is mixed with the bypass hot air to form high-temperature primary air and sent to the furnace.

[0007] Preferably, an emergency supply pipeline is further included, and the emergency supply pipeline includes:

[0008] A powder inlet pipeline, an air inlet pipeline and an output pipeline, wherein the powder inlet pipeline is installed at the powder inlet end of the powder collector, the air inlet pipeline is installed at the air inlet end of the powder collector, and the output pipeline is installed at the output end of the powder collector;

[0009] The powder inlet pipeline is provided with a powder inlet switch valve, and the air inlet pipeline is provided with an air inlet switch valve;

[0010] The pulverized coal collected and loaded air at the outlet of the medium-speed coal mill flows into the pulverized coal collector's pulverized coal inlet end through the pulverized coal inlet pipe, and the pulverized coal driven hot air at the outlet of the air preheater flows into the pulverized coal collector's pulverized coal inlet end through the pulverized coal inlet pipe.

[0011] The powder collector is used to separate the collected powder-laden air into air and coal powder. The separated air is sent to the furnace through the output pipeline. The separated coal powder accumulates in the powder collector. During emergency supply, the coal powder drives the hot air to mix with the coal powder in the powder collector to form emergency supply high-temperature primary air and send it to the furnace.

[0012] Preferably, the powder collector comprises:

[0013] A powder collector housing, wherein a wind-powder separation chamber and a air supply chamber are arranged, the powder inlet end and the output end are communicated with the wind-powder separation chamber, and the air inlet end is communicated with the air supply chamber;

[0014] A powder collecting cylinder, which is fixedly connected to the bottom of the wind-powder separation chamber, the coal powder inlet of the powder collecting cylinder is in a horn shape, and a plurality of annular powder collecting grooves are arranged on the powder collecting cylinder in a circumferential direction;

[0015] A powder collecting shaft, which is rotatably connected in the air supply chamber, a shaft driving element is arranged on the powder collecting shaft, the shaft driving element is used to drive the powder collecting shaft to rotate, and a plurality of uniformly arranged powder collecting screens are fixedly connected to the powder collecting shaft, the installation height of the plurality of powder collecting screens and the opening height of the plurality of annular powder collecting grooves are in the same horizontal plane and correspond one by one;

[0016] The air inlet end is in a horn shape structure, and a uniform flow net is arranged in the air inlet end;

[0017] A filter screen, which is fixedly connected to the inner wall of the wind-powder separation chamber, and an air pump is arranged on the inner wall of the wind-powder separation chamber and above the filter screen;

[0018] A humidifier is arranged on the powder collector housing, and the spray outlet of the humidifier is below the filter screen;

[0019] The air supply chamber is communicated with the output end through an arc-shaped pipeline.

[0020] Preferably, the bypass hot air is transported through a pipeline, a combustion-supporting gas adding box is arranged on the pipeline where the bypass hot air is located, and the combustion-supporting gas adding box is used to transport combustion-supporting gas to the pipeline where the bypass hot air is located.

[0021] Preferably, a ground-overheated hot air pressure feedback adjustment system is arranged on the medium-speed coal mill, the ground-overheated hot air pressure feedback adjustment system is used to monitor the actual dust carrying capacity of the ground-overheated hot air when the ground-overheated hot air passes through the medium-speed coal mill, and the flow of the ground-overheated hot air is adjusted when the dust carrying capacity of the ground-overheated hot air is insufficient, the ground-overheated hot air pressure feedback adjustment system comprises a coal mill actual powder output calculation unit, an air pressure compensation calculation unit and a ground-overheated hot air flow adjustment valve, the coal mill actual powder output calculation unit is electrically connected with the air pressure compensation calculation unit, and the air pressure compensation calculation unit is electrically connected with the ground-overheated hot air flow adjustment valve;

[0022] A coal mill actual powder output calculation unit, which is used to calculate the actual powder output of the medium-speed coal mill;

[0023] A gas pressure compensation calculation unit is configured to calculate a current over-grinding hot air pressure value to be compensated according to an actual pulverized coal output of the medium-speed coal mill;

[0024] An over-grinding hot air flow adjusting valve is arranged at an over-grinding hot air inlet end of the medium-speed coal mill, and is configured to adjust a flow of the over-grinding hot air based on the current over-grinding hot air pressure value to be compensated, so as to adjust and control the current over-grinding hot air pressure value to be compensated to a preset range.

[0025] Preferably, the actual pulverized coal output calculation unit of the medium-speed coal mill comprises:

[0026] A weight sensor is arranged at a coal inlet of the medium-speed coal mill, and is configured to detect a total weight of coal blocks filled into the medium-speed coal mill;

[0027] A rotating speed sensor is arranged at a roller of the medium-speed coal mill, and is configured to detect a rotating speed of the roller of the medium-speed coal mill;

[0028] A timer is arranged at the medium-speed coal mill, and is configured to detect a total grinding time of the medium-speed coal mill;

[0029] Based on the weight sensor, the rotating speed sensor and the timer, the actual pulverized coal output of the medium-speed coal mill (2) is calculated as follows:

[0030]

[0031] Wherein, Δ is the actual pulverized coal output of the medium-speed coal mill, η is a reference grinding efficiency of the medium-speed coal mill, is a filling amount of the coal blocks in the medium-speed coal mill, ln is a logarithm with e as a base, e is a natural number and takes a value of 2.72, Z is a number of steel balls in the roller of the medium-speed coal mill, G is a weight of a single steel ball in the medium-speed coal mill, G0 is a detection value of the weight sensor, π is a circular constant and takes a value of 3.14, n is the rotating speed of the roller of the medium-speed coal mill, D is a diameter of the roller of the medium-speed coal mill, t is a detection value of the timer, L is a length of the roller of the medium-speed coal mill, λ is a volume proportion of the steel balls and the coal blocks in the roller, and Λ is a volume of the roller.

[0032] Preferably, the gas pressure compensation calculation unit comprises:

[0033] A first gas pressure sensor is arranged at an over-grinding hot air inlet end of the medium-speed coal mill, and is configured to detect a gas pressure value at the over-grinding hot air inlet end of the medium-speed coal mill;

[0034] A second air pressure sensor is arranged at the pulverized coal air outlet end of the medium-speed coal mill, and is used to detect the air pressure value at the pulverized coal air outlet end of the medium-speed coal mill.

[0035] A pulverized coal density sensor is arranged at the pulverized coal air outlet end of the medium-speed coal mill, and is used to detect the pulverized coal density at the pulverized coal air outlet end of the medium-speed coal mill.

[0036] A pulverized coal air flow rate sensor is arranged at the pulverized coal air outlet end of the medium-speed coal mill, and is used to detect the air flow rate at the pulverized coal air outlet end of the medium-speed coal mill.

[0037] A pulverized coal air mass flow sensor is arranged at the pulverized coal air outlet end of the medium-speed coal mill, and is used to detect the mass flow of the pulverized coal air at the pulverized coal air outlet end of the medium-speed coal mill.

[0038] The current over-milling hot air pressure value to be compensated is calculated based on the first air pressure sensor, the second air pressure sensor, the pulverized coal density sensor, the pulverized coal air flow rate sensor and the pulverized coal air mass flow sensor as follows:

[0039]

[0040] Wherein, P ε is the current over-milling hot air pressure value to be compensated, if P ε is greater than 0, the air pressure value of the over-milling hot air needs to be increased, if P ε is less than 0, the air pressure value of the over-milling hot air needs to be reduced, P i is the detection value of the first air pressure sensor, e is a natural number, and the value is 2.72, Δ0 is the reference pulverized coal output of the medium-speed coal mill, P o is the detection value of the second air pressure sensor, ξ is the air flow friction resistance coefficient in the medium-speed coal mill, L is the length of the medium-speed coal mill roller, D is the diameter of the medium-speed coal mill roller, δ1 is the detection value of the pulverized coal density sensor, υ χ is the detection value of the pulverized coal air flow rate sensor, g is the acceleration of gravity, and the value is 9.81, T is the detection value of the pulverized coal air mass flow sensor, and σ is the volume ratio of the pulverized coal to the hot air in the pulverized coal air.

[0041] Preferably, the system further comprises a pulverized coal collector fault monitoring system arranged on the pulverized coal collector, and used to monitor the working state of the pulverized coal collector, wherein the pulverized coal collector fault monitoring system comprises:

[0042] A first flow rate sensor is arranged at the pulverized coal inlet end of the pulverized coal collector, and is used to detect the flow rate of the pulverized coal at the pulverized coal inlet end of the pulverized coal collector.

[0043] a density sensor, the density sensor being disposed in the air-powder separation chamber and being used to detect the density of the coal powder in the air-powder separation chamber;

[0044] a second flow velocity sensor, the second flow velocity sensor being disposed at the spray outlet and configured to detect a flow velocity of the water mist sprayed from the spray outlet;

[0045] a pressure sensor, the pressure sensor being disposed in the air-powder separation chamber and being used to detect the pressure in the air-powder separation chamber;

[0046] a temperature sensor, the temperature sensor being disposed in the air-powder separation chamber and being used to detect the temperature in the air-powder separation chamber;

[0047] A controller, a fault alarm, wherein the controller is electrically connected to the first flow rate sensor, the density sensor, the second flow rate sensor, the pressure sensor, the temperature sensor and the fault alarm, and the controller controls the fault alarm to alarm based on the first flow rate sensor, the density sensor, the second flow rate sensor, the temperature sensor and the pressure sensor.

[0048] Preferably, the controller controls the fault alarm to alarm based on the first flow rate sensor, the density sensor, the second flow rate sensor and the pressure sensor, comprising the following steps:

[0049] Step 1: Based on the first flow velocity sensor, the temperature sensor and formula (1), calculate the natural settling efficiency of the pulverized coal:

[0050]

[0051] Among them, β1 is the natural settling efficiency of coal powder, d max is the maximum preset coal powder diameter, d min is the minimum preset coal powder diameter, V is the volume of the air-powder separation chamber, g is the acceleration of gravity, which is 9.81, and ε α is the dynamic viscosity of air, θ o is the detection value of the first flow velocity sensor, θ is the preset flow velocity of the pulverized coal, m0 is the preset mass of the pulverized coal, e is a natural number, and its value is 2.72, T1 is the detection value of the temperature sensor, and T0 is the preset temperature of the air-powder separation chamber;

[0052] Step 2: Based on the first flow rate sensor, the density sensor, the second flow rate sensor, the pressure sensor and formula (2), calculate the actual comprehensive powder collection efficiency of the powder collector:

[0053]

[0054] Among them, β2 is the actual comprehensive powder collection efficiency of the powder collector, ρ is the detection value of the density sensor, θ m is the detection value of the second flow velocity sensor, M q is the preset mass of the water mist, p st is the detection value of the pressure sensor, p is the preset air pressure, and d is the preset diameter of the water mist;

[0055] Step three: the controller compares the actual comprehensive powder collection efficiency of the powder collector with the preset comprehensive powder collection efficiency of the powder collector. If the actual comprehensive powder collection efficiency of the powder collector is less than the preset comprehensive powder collection efficiency of the powder collector, the controller controls the fault alarm to alarm.

[0056] Preferably, the combustion-supporting gas includes any one or more of oxygen, ozone, fluorine, and carbon dioxide.

[0057] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0059] Figure 1 This is a block diagram of the overall system of the present invention.

[0060] Figure 2 This is a connection diagram of the emergency supply pipeline of the present invention.

[0061] Figure 3 This is a block diagram of the emergency supply pipeline of the present invention.

[0062] Figure 4 It is a schematic structural diagram of the powder collecting machine of the present invention.

[0063] In the figure: 1. Air preheater; 2. Coal mill; 3. Boiler; 4. Hot air; 5. Bypass hot air; 6. Over-grinding hot air; 7. Powder-carrying air; 8. High-temperature primary air; 9. Powder collector; 900. Powder collector housing; 9000. Air-powder separation chamber; 9001. Air supply chamber; 9002. Powder collecting cylinder; 9003. Annular powder collecting trough; 9004. Powder collecting shaft; 9005. Powder collecting sieve; 9006. Flow-uniform net; 9007. Powder filter net; 9008. Vacuum pump; 9009. Humidifier; 901. Air inlet end; 9010. Spray outlet; 9011. Arc pipe; 902. Output end; 903. Combustion-supporting gas adding box; 10. Powder-carrying air for powder collection; 11. Powder inlet switch valve; 12. Emergency supply of high-temperature primary air; 13. Coal powder drives hot air. DETAILED DESCRIPTION

[0064] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0065] In addition, in the present invention, descriptions such as "first" and "second" are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present invention. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions and technical features between the various embodiments can be combined with each other, but this must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0066] The present invention provides the following embodiments:

[0067] Example 1

[0068] The embodiment of the present invention provides a system for increasing the primary air temperature at the outlet of a medium-speed coal mill. Figure 1-4 As shown, it includes an air preheater 1, a medium-speed coal mill 2 and a furnace 3. The hot air 4 at the outlet of the air preheater 1 is divided into two parts: over-grinding hot air 6 and bypass hot air 5. The powder-laden air 7 at the outlet of the medium-speed coal mill 2 is mixed with the bypass hot air 5 and then sent to the furnace 3.

[0069] Preferably, the bypass hot air 5 is transported through a pipeline, and a combustion-supporting gas adding box 903 is provided on the pipeline where the bypass hot air 5 is located. The combustion-supporting gas adding box 903 is used to transport the combustion-supporting gas to the pipeline where the bypass hot air 5 is located;

[0070] The combustion-supporting gas includes any one or more of oxygen, ozone, fluorine, and carbon dioxide.

[0071] The working principle and beneficial effects of the above technical solution are as follows: the hot air 4 at the outlet of the air preheater 1 is divided into two parts: the over-grinded hot air 6 and the bypass hot air 5. The over-grinded hot air 6 enters the coal mill 2 to dry the raw coal. The bypass hot air 5 is mixed with the pulverized air 7 at the outlet of the coal mill 2 to become high-temperature primary air 8. The high-temperature primary air 8 is sent to the boiler 3 for combustion. The design of the bypass hot air 5 can greatly increase the temperature of the primary air entering the boiler, thereby ensuring the stability of boiler combustion and the burnout of pulverized coal, which is beneficial to improving the combustion efficiency of the boiler, while reducing the exhaust gas temperature, improving the efficiency of the boiler, and improving the economy of the boiler.

[0072] In addition, the combustion-supporting gas can be delivered to the pipeline where the bypass hot air 5 is located through the combustion-supporting gas adding box 903, thereby ensuring the stability of boiler combustion and the burnout of coal powder.

[0073] Example 2

[0074] On the basis of the above embodiment 1, Figure 2 and 3 As shown, an emergency supply line is also included, and the emergency supply line includes:

[0075] A powder inlet pipeline, an air inlet pipeline, and an output pipeline. The powder inlet pipeline is installed at the powder inlet end 900 of the powder collector 9, the air inlet pipeline is installed at the air inlet end 901 of the powder collector 9, and the output pipeline is installed at the output end 902 of the powder collector 9;

[0076] The powder inlet pipeline is provided with a powder inlet switch valve 11, and the air inlet pipeline is provided with an air inlet switch valve 14;

[0077] The pulverized coal-carrying air 10 at the outlet of the medium-speed coal mill 2 flows into the pulverized coal collector 9 via the pulverized coal inlet pipe 900, and the pulverized coal-driven hot air 13 at the outlet of the air preheater 1 flows into the pulverized coal collector 9 via the air inlet pipe 901.

[0078] The powder collector 9 is used to separate the powder-laden air 10 into air and coal powder. The separated air is sent to the furnace 3 through the output pipeline. The separated coal powder accumulates in the powder collector 9. During emergency supply, the coal powder drives the hot air 13 to mix with the coal powder in the powder collector 9 to form the emergency supply high-temperature primary air 12 and send it to the furnace 3.

[0079] The working principle and beneficial effects of the above technical solution are as follows: when the medium-speed coal mill 2 is damaged, or the coal grinding efficiency of the medium-speed coal mill 2 cannot enable the boiler to operate under normal load, shutting down the medium-speed coal mill 2 can save energy and improve the economy of the boiler system. When the coal grinding efficiency of the medium-speed coal mill 2 is high, the pulverized coal inlet switch valve 11 is opened, and the dust-collecting air 10 at the outlet of the medium-speed coal mill 2 flows into the dust inlet end of the dust collector 9 through the dust inlet pipeline. The dust collector 9 separates the dust-collecting air 10 into air and coal powder. The separated air is sent to the furnace 3 through the output pipeline, and the separated coal powder accumulates in the dust collector 9.

[0080] When the medium-speed pulverizer 2 is closed, the air inlet switch valve 14 is opened, and the coal powder drives the hot air 13 at the outlet of the air preheater 1 to flow into the air inlet end of the pulverizer 9 through the air inlet pipe. Then, the coal powder drives the hot air 13 to mix with the coal powder in the pulverizer 9 to form the emergency supply high-temperature primary air 12 and send it to the furnace 3, thereby ensuring the normal supply of coal powder to the boiler. At the same time, compared with the coal powder supplied through the medium-speed pulverizer 2, the temperature of the emergency supply high-temperature primary air 12 is higher, the combustion in the boiler is more stable, the burnout of coal powder is better, and it is more conducive to improving the combustion efficiency of the boiler, while reducing the exhaust gas temperature, improving the boiler efficiency, and improving the economy.

[0081] Example 3

[0082] On the basis of Example 1, Figure 4 As shown, the powder collecting machine 9 includes:

[0083] A powder collector housing 900 is provided with an air-powder separation chamber 9000 and an air supply chamber 9001 therein. The powder inlet end 900 and the output end 902 are both in communication with the air-powder separation chamber 9000, and the air inlet end 901 is in communication with the air supply chamber 9001.

[0084] A powder collecting cylinder 9002 is fixedly connected to the bottom of the air-powder separation chamber 9000. The coal powder inlet of the powder collecting cylinder 9002 is trumpet-shaped. The powder collecting cylinder 9002 is provided with a plurality of annular powder collecting grooves 9003 along its circumference.

[0085] A powder collecting shaft 9004 is rotatably connected to the air supply chamber 9001. A shaft driving member is provided on the powder collecting shaft 9004 for driving the powder collecting shaft 9004 to rotate. A plurality of evenly arranged powder collecting sieves 9005 are fixedly connected to the powder collecting shaft 9004. The installation heights of the plurality of powder collecting sieves 9005 and the opening heights of the plurality of annular powder collecting grooves 9003 are in the same horizontal plane and correspond one to one.

[0086] The air inlet end 901 is a trumpet-shaped structure, and a uniform flow net 9006 is provided inside the air inlet end 901;

[0087] A powder filter screen 9007 is fixedly connected to the inner wall of the air-powder separation chamber 9000. An air pump 9008 is provided on the inner wall of the air-powder separation chamber 9000 and above the powder filter screen 9007.

[0088] The powder collector housing 900 is provided with a humidifier 9009 , and the spray outlet 9010 of the humidifier 9009 is located below the powder filter 9007 ;

[0089] The air supply cavity 9001 is connected to the output end 902 through an arc-shaped pipe 9011 .

[0090] The working principle and beneficial effects of the above technical solution are as follows: when working, the powder-collecting wind 10 with powder enters the air-powder separation chamber 9000 through the powder inlet pipeline and the powder inlet end 900, and at the same time, the humidifier 9009 sprays water mist outward through the spray outlet 9010, so that the coal powder in the powder-collecting wind 10 with powder combines with the water mist in the air-powder separation chamber 9000 and falls into the powder collecting barrel 9002 under the action of gravity, thereby gradually accumulating. The wind in the powder-collecting wind 10 with powder is sent out through the output end 902 under the action of the vacuum pump 9008. Towards the furnace 3, when coal powder needs to be urgently supplied, the shaft driving member drives the powder collecting shaft 9004 to rotate, thereby driving the powder collecting screen 9005 to rotate. During the rotation process, the powder collecting screen 9005 is inserted into the powder collecting tube 9002 through the annular powder collecting groove 9003 to collect powder and then rotates to the air supply chamber 9001 for powder supply. Under the action of the hot air 13 driven by the coal powder at the air inlet end 901, the coal powder on the powder collecting screen 9005 is brought into the arc pipe 9011 and sent to the furnace 3 through the arc pipe 9011 and the output end 902.

[0091] Example 4

[0092] On the basis of Example 1, the medium-speed coal mill 2 is provided with an over-grinding hot air pressure feedback regulation system, which is used to monitor the actual powder carrying capacity of the over-grinding hot air 6 when passing through the medium-speed coal mill 2, and to regulate the flow of the over-grinding hot air 6 when the powder carrying capacity of the over-grinding hot air 6 is insufficient. The over-grinding hot air pressure feedback regulation system includes a coal mill actual powder output calculation unit, an air pressure compensation calculation unit and an over-grinding hot air flow control valve. The coal mill actual powder output calculation unit is electrically connected to the air pressure compensation calculation unit, and the air pressure compensation calculation unit is electrically connected to the over-grinding hot air flow control valve.

[0093] A coal mill actual pulverized coal output calculation unit, which is used to calculate the actual pulverized coal output of the medium-speed coal mill 2;

[0094] An air pressure compensation calculation unit, which is used to calculate the current air pressure value of the over-grinding hot air 6 that needs to be compensated according to the actual powder output of the medium-speed coal mill 2;

[0095] The over-grinded hot air flow regulating valve is arranged at the inlet end of the over-grinded hot air 6 of the medium-speed coal mill 2. The over-grinded hot air flow regulating valve is used to adjust the flow of the over-grinded hot air 6 based on the current pressure value of the over-grinded hot air 6 to be compensated, thereby adjusting and controlling the current pressure value of the over-grinded hot air 6 to be compensated to be within a preset range;

[0096] The coal mill actual pulverized coal output calculation unit includes:

[0097] A weight sensor is provided at the coal inlet of the medium-speed coal mill 2 and is used to detect the total weight of the coal blocks filled into the medium-speed coal mill 2;

[0098] A rotation speed sensor, which is provided on the drum of the medium-speed coal mill 2 and is used to detect the rotation speed of the drum of the medium-speed coal mill 2;

[0099] a timer, the timer being provided on the medium-speed coal mill 2 and being used to detect the total coal grinding time of the medium-speed coal mill 2;

[0100] Based on the weight sensor, the rotation speed sensor and the timer, the actual pulverized coal output of the medium-speed coal mill 2 is calculated as follows:

[0101]

[0102] Wherein, Δ is the actual pulverized coal output of the medium-speed coal mill 2, η is the benchmark coal grinding efficiency of the medium-speed coal mill 2, is the filling amount of coal blocks in the medium-speed coal mill 2, ln is the logarithm with base e, e is a natural number, and its value is 2.72, Z is the number of steel balls in the drum of the medium-speed coal mill 2, G is the weight of a single steel ball in the medium-speed coal mill 2, G0 is the detection value of the weight sensor, π is the pi, and its value is 3.14, n is the rotation speed of the drum of the medium-speed coal mill 2, D is the diameter of the drum of the medium-speed coal mill 2, t is the detection value of the timer, L is the length of the drum of the medium-speed coal mill 2, λ is the volume ratio of the steel balls and coal blocks in the drum, and Λ is the volume of the drum;

[0103] The air pressure compensation calculation unit includes:

[0104] a first air pressure sensor, which is provided at an air inlet end of the over-ground hot air 6 of the medium-speed coal mill 2 and is used to detect an air pressure value at the air inlet end of the over-ground hot air 6 of the medium-speed coal mill 2;

[0105] a second air pressure sensor, which is provided at an outlet end of the powdered air 7 of the medium-speed coal mill 2 and is used to detect an air pressure value at the outlet end of the powdered air 7 of the medium-speed coal mill 2;

[0106] a pulverized coal density sensor, the pulverized coal density sensor being arranged at an outlet end of the pulverized air 7 of the medium-speed coal mill 2 and being used to detect the pulverized coal density at the outlet end of the pulverized air 7 of the medium-speed coal mill 2;

[0107] a dust-laden air flow velocity sensor, the dust-laden air flow velocity sensor being arranged at the dust-laden air 7 outlet end of the medium-speed coal mill 2 and being used to detect the wind velocity at the dust-laden air 7 outlet end of the medium-speed coal mill 2;

[0108] a dust-laden air mass flow sensor, the dust-laden air mass flow sensor being arranged at the dust-laden air 7 outlet end of the medium-speed coal mill 2 and being used to detect the mass flow of the dust-laden air at the dust-laden air 7 outlet end of the medium-speed coal mill 2;

[0109] Based on the first air pressure sensor, the second air pressure sensor, the pulverized coal density sensor, the pulverized coal air velocity sensor, and the pulverized coal air mass flow sensor, the current pressure value of the over-grinded hot air 6 that needs to be compensated is calculated as follows:

[0110]

[0111] Among them, P ε is the current pressure value of the over-grinding hot air 6 that needs to be compensated. If P ε If it is greater than 0, the pressure of the hot air 6 should be increased. ε If it is less than 0, the pressure of the hot air 6 needs to be reduced. i is the detection value of the first air pressure sensor, e is a natural number, the value is 2.72, Δ0 is the reference pulverized coal output of the medium-speed coal mill 2, P o is the detection value of the second air pressure sensor, ξ is the air flow friction resistance coefficient in the medium-speed coal mill 2, L is the length of the drum of the medium-speed coal mill 2, D is the diameter of the drum of the medium-speed coal mill 2, δ1 is the detection value of the coal powder density sensor, υ χ is the detection value of the dust-carrying air velocity sensor, g is the acceleration of gravity, which is 9.81, T is the detection value of the dust-carrying air mass flow sensor, and σ is the volume ratio of the dust-carrying air 7 to the hot air.

[0112] The working principle and beneficial effects of the above technical solution are as follows: the over-ground hot air pressure feedback regulation system monitors the actual pulverized dust carrying capacity of the over-ground hot air 6 when it passes through the medium-speed coal mill 2, and adjusts the flow rate of the over-ground hot air 6 when the pulverized dust carrying capacity of the over-ground hot air 6 is insufficient, thereby calculating the current pressure value of the over-ground hot air 6 that needs to be compensated according to the actual pulverized dust output of the medium-speed coal mill 2, and then adaptively adjusting the over-ground hot air flow regulating valve according to the current pressure value of the over-ground hot air 6 that needs to be compensated, so that the current pressure value of the over-ground hot air 6 that needs to be compensated is regulated and controlled within a preset range, thereby achieving the economic efficiency of the use of the medium-speed coal mill 2 and improving the burnout of the boiler coal powder;

[0113] When calculating the actual pulverized coal output Δ of the medium-speed coal mill 2, the parameters of the medium-speed coal mill 2 structure itself, the diameter D of the medium-speed coal mill 2 drum and the length L of the medium-speed coal mill 2 drum are introduced to make the calculation result more accurate. The number Z of steel balls in the drum of the medium-speed coal mill 2, the weight G of a single steel ball in the drum of the medium-speed coal mill 2, the speed n of the drum of the medium-speed coal mill 2, the filling amount of coal blocks in the medium-speed coal mill 2 The greater the reference grinding efficiency η of the medium-speed coal mill 2 is, the greater the actual powder output of the medium-speed coal mill 2 is;

[0114] When calculating the current over-grinding hot air 6 pressure value to be compensated, the airflow friction resistance coefficient in the medium-speed coal mill 2 is introduced to improve the accuracy of the calculation result. If P ε is greater than 0, the pressure value of the over-grinding hot air 6 needs to be increased. If P ε is less than 0, the pressure value of the over-grinding hot air 6 needs to be reduced. The flow of the over-grinding hot air 6 can be changed by the over-grinding hot air flow regulating valve to change the pressure value of the over-grinding hot air 6.

[0115] Embodiment 5

[0116] On the basis of embodiment 3, further comprising: a powder collector fault monitoring system, the powder collector fault monitoring system is arranged on the powder collector 9, and is used for monitoring the working state of the powder collector 9, and the powder collector fault monitoring system comprises:

[0117] A first flow rate sensor, the first flow rate sensor is arranged at the powder inlet end 900 of the powder collector 9, and is used for detecting the flow rate of the pulverized coal at the powder inlet end 900 of the powder collector 9;

[0118] A density sensor, the density sensor is arranged in the wind-powder separation chamber 9000, and is used for detecting the density of the pulverized coal in the wind-powder separation chamber 9000;

[0119] A second flow rate sensor, the second flow rate sensor is arranged at the spray outlet 9010, and is used for detecting the flow rate of the water mist sprayed by the spray outlet 9010;

[0120] A pressure sensor, the pressure sensor is arranged in the wind-powder separation chamber 9000, and is used for detecting the pressure in the wind-powder separation chamber 9000;

[0121] A temperature sensor, the temperature sensor is arranged in the wind-powder separation chamber 9000, and is used for detecting the temperature in the wind-powder separation chamber 9000;

[0122] A controller and a fault alarm, the controller is electrically connected with the first flow rate sensor, the density sensor, the second flow rate sensor, the pressure sensor, the temperature sensor and the fault alarm, and the controller controls the fault alarm to alarm based on the first flow rate sensor, the density sensor, the second flow rate sensor, the temperature sensor and the pressure sensor;

[0123] The controller controls the fault alarm to alarm based on the first flow rate sensor, the density sensor, the second flow rate sensor and the pressure sensor, and the method comprises the following steps:

[0124] Step 1: Based on the first flow velocity sensor, the temperature sensor and formula (1), calculate the natural settling efficiency of the pulverized coal:

[0125]

[0126] Among them, β1 is the natural settling efficiency of coal powder, d max is the maximum preset coal powder diameter, d min is the minimum preset coal powder diameter, V is the volume of the air-powder separation chamber 9000, g is the acceleration of gravity, which is 9.81, ε α is the dynamic viscosity of air, θ o is the detection value of the first flow velocity sensor, θ is the preset flow velocity of the pulverized coal, m0 is the preset mass of the pulverized coal, e is a natural number, and its value is 2.72, T1 is the detection value of the temperature sensor, and T0 is the preset temperature of the air-powder separation chamber 9000;

[0127] Step 2: Based on the first flow rate sensor, the density sensor, the second flow rate sensor, the pressure sensor and formula (2), calculate the actual comprehensive powder collection efficiency of the powder collector 9:

[0128]

[0129] Wherein, β2 is the actual comprehensive powder collection efficiency of the powder collector 9, ρ is the detection value of the density sensor, θ m is the detection value of the second flow velocity sensor, M q is the preset mass of the water mist, p st is the detection value of the pressure sensor, p is the preset air pressure, and d is the preset diameter of the water mist;

[0130] Step three: The controller compares the actual comprehensive powder collection efficiency of the powder collector 9 with the preset comprehensive powder collection efficiency of the powder collector 9. If the actual comprehensive powder collection efficiency of the powder collector 9 is less than the preset comprehensive powder collection efficiency of the powder collector 9, the controller controls the fault alarm to alarm.

[0131] The working principle and beneficial effects of the above technical solution are as follows: when calculating the actual comprehensive powder collection efficiency of the powder collector 9, in addition to introducing the natural sedimentation efficiency of the coal powder, the effect of the water mist of the humidifier 9009 is also combined, so that the calculation result is more accurate. If the actual comprehensive powder collection efficiency of the powder collector 9 is less than the preset comprehensive powder collection efficiency of the powder collector 9, the controller controls the fault alarm to alarm, which proves that the powder collector 9 is blocked or there is a problem with the powder feeding. In order to ensure the normal use of the powder collector 9 in a timely manner, the fault alarm needs to be used to sound an alarm to remind the staff to repair it in time.

[0132] Maximum preset coal powder diameter d max , minimum preset coal powder diameter d min The larger the pulverized coal, the greater the natural settling efficiency. The greater the preset flow rate of the pulverized coal, the smaller the natural settling efficiency of the pulverized coal. The temperature inside the air-powder separation chamber 9000 is also introduced when calculating the natural settling efficiency of the pulverized coal, so that the calculation result is more accurate.

[0133] The greater the density of the coal powder in the air-powder separation chamber 9000, the greater the preset diameter d of the water mist and the preset mass M of the water mist. q The larger the value, the smaller the pressure in the air-powder separation chamber 9000, and the greater the actual comprehensive powder collecting efficiency of the powder collector 9.

[0134] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A system for increasing the primary air temperature at the outlet of a medium-speed coal mill, characterized in that: The invention comprises an air preheater (1), a medium-speed coal mill (2) and a furnace (3); the hot air (4) at the outlet of the air preheater (1) is divided into two parts: over-grinding hot air (6) and bypass hot air (5); the powder-laden air (7) at the outlet of the medium-speed coal mill (2) is mixed with the bypass hot air (5) to form high-temperature primary air (8) and sent to the furnace (3); Also included is an emergency supply line, the emergency supply line comprising: A powder inlet pipeline, an air inlet pipeline, and an output pipeline, wherein the powder inlet pipeline is installed at the powder inlet end (900) of the powder collector (9), the air inlet pipeline is installed at the air inlet end (901) of the powder collector (9), and the output pipeline is installed at the output end (902) of the powder collector (9); The powder inlet pipeline is provided with a powder inlet switch valve (11), and the air inlet pipeline is provided with an air inlet switch valve (14); The powder collecting and carrying air (10) at the outlet of the medium-speed coal mill (2) flows into the powder inlet end (900) of the powder collector (9) through the powder inlet pipeline, and the coal powder driving hot air (13) at the outlet of the air preheater (1) flows into the air inlet end (901) of the powder collector (9) through the air inlet pipeline; The powder collector (9) is used to separate the powder-laden air (10) into air and coal powder. The separated air is sent to the furnace (3) through an output pipeline. The separated coal powder is accumulated in the powder collector (9). During emergency supply, the coal powder drives the hot air (13) to mix with the coal powder in the powder collector (9) to form emergency supply high-temperature primary air (12) and send it to the furnace (3). The powder collecting machine (9) comprises: A powder collector housing (900), wherein an air-powder separation chamber (9000) and an air supply chamber (9001) are provided in the powder collector housing (900), the powder inlet end (900) and the output end (902) are both in communication with the air-powder separation chamber (9000), and the air inlet end (901) is in communication with the air supply chamber (9001); A powder collecting cylinder (9002) is fixedly connected to the bottom of the air-powder separation chamber (9000). The coal powder inlet of the powder collecting cylinder (9002) is trumpet-shaped. The powder collecting cylinder (9002) is provided with a plurality of annular powder collecting grooves (9003) along its circumference. A powder collecting shaft (9004) is rotatably connected to the air supply chamber (9001). A shaft driving member is provided on the powder collecting shaft (9004), and the shaft driving member is used to drive the powder collecting shaft (9004) to rotate. A plurality of evenly arranged powder collecting sieves (9005) are fixedly connected to the powder collecting shaft (9004). The installation height of the plurality of powder collecting sieves (9005) is in the same horizontal plane as the opening height of the plurality of annular powder collecting grooves (9003) and corresponds one to one. The air inlet end (901) is a trumpet-shaped structure, and a flow-uniform net (9006) is provided inside the air inlet end (901); a powder filter screen (9007), the powder filter screen (9007) being fixedly connected to the inner wall of the air-powder separation chamber (9000), and an air pump (9008) being provided on the inner wall of the air-powder separation chamber (9000) and located above the powder filter screen (9007); A humidifier (9009) is provided on the powder collector housing (900), and a spray outlet (9010) of the humidifier (9009) is located below the powder filter (9007); The air supply chamber (9001) is connected to the output end (902) via an arc-shaped pipe (9011).

2. A system for increasing the primary air temperature at the outlet of a medium-speed coal mill according to claim 1, characterized in that: The bypass hot air (5) is transported through a pipeline. A combustion-supporting gas adding box (903) is provided on the pipeline where the bypass hot air (5) is located. The combustion-supporting gas adding box (903) is used to transport the combustion-supporting gas to the pipeline where the bypass hot air (5) is located.

3. The system for increasing the primary air temperature at the outlet of a medium-speed coal mill according to claim 1, characterized in that: The medium-speed coal mill (2) is provided with an over-grinding hot air pressure feedback regulation system, the over-grinding hot air pressure feedback regulation system is used to monitor the actual powder carrying capacity of the over-grinding hot air (6) when passing through the medium-speed coal mill (2), and to regulate the flow of the over-grinding hot air (6) when the powder carrying capacity of the over-grinding hot air (6) is insufficient, the over-grinding hot air pressure feedback regulation system includes a coal mill actual powder output calculation unit, a pressure compensation calculation unit and an over-grinding hot air flow control valve, the coal mill actual powder output calculation unit is electrically connected to the pressure compensation calculation unit, and the pressure compensation calculation unit is electrically connected to the over-grinding hot air flow control valve; A coal mill actual pulverized coal output calculation unit, the coal mill actual pulverized coal output calculation unit being used to calculate the actual pulverized coal output of the medium-speed coal mill (2); An air pressure compensation calculation unit, the air pressure compensation calculation unit being used to calculate the air pressure value of the over-grinding hot air (6) that needs to be compensated according to the actual powder output of the medium-speed coal mill (2); An over-grinded hot air flow regulating valve is provided at an inlet end of the over-grinded hot air (6) of the medium-speed coal mill (2). The over-grinded hot air flow regulating valve is used to regulate the flow of the over-grinded hot air (6) based on a current pressure value of the over-grinded hot air (6) to be compensated, thereby regulating and controlling the current pressure value of the over-grinded hot air (6) to be compensated to be within a preset range.

4. The system for increasing the primary air temperature at the outlet of a medium-speed coal mill according to claim 3, characterized in that: The coal mill actual pulverized coal output calculation unit includes: a weight sensor, the weight sensor being arranged at the coal inlet of the medium-speed coal mill (2) and being used to detect the total weight of the coal blocks filled into the medium-speed coal mill (2); A rotation speed sensor, the rotation speed sensor being arranged on the drum of the medium-speed coal mill (2) and being used to detect the rotation speed of the drum of the medium-speed coal mill (2); a timer, the timer being arranged on the medium-speed coal mill (2) and being used for detecting the total coal grinding time of the medium-speed coal mill (2); Based on the weight sensor, the rotation speed sensor and the timer, the actual pulverized coal output of the medium-speed coal mill (2) is calculated as follows: Wherein, Δ is the actual pulverized coal output of the medium-speed coal mill (2), η is the benchmark coal grinding efficiency of the medium-speed coal mill (2), is the filling amount of coal blocks in the medium-speed coal mill (2), ln is the logarithm with base e, e is a natural number, and its value is 2.72, Z is the number of steel balls in the drum of the medium-speed coal mill (2), G is the weight of a single steel ball in the medium-speed coal mill (2), G0 is the detection value of the weight sensor, π is the pi, and its value is 3.14, n is the rotation speed of the drum of the medium-speed coal mill (2), D is the diameter of the drum of the medium-speed coal mill (2), t is the detection value of the timer, L is the length of the drum of the medium-speed coal mill (2), λ is the volume ratio of the steel balls and coal blocks in the drum, and Λ is the volume of the drum.

5. The system for increasing the primary air temperature at the outlet of a medium-speed coal mill according to claim 4, characterized in that: The air pressure compensation calculation unit includes: a first air pressure sensor, the first air pressure sensor being arranged at an air inlet end of the over-ground hot air (6) of the medium-speed coal mill (2) and being used to detect an air pressure value at the air inlet end of the over-ground hot air (6) of the medium-speed coal mill (2); a second air pressure sensor, the second air pressure sensor being arranged at an outlet end of the powdered air (7) of the medium-speed coal mill (2) and being used to detect an air pressure value at the outlet end of the powdered air (7) of the medium-speed coal mill (2); a pulverized coal density sensor, the pulverized coal density sensor being arranged at an outlet end of the pulverized air (7) of the medium-speed coal mill (2) and being used to detect the pulverized coal density at the outlet end of the pulverized air (7) of the medium-speed coal mill (2); a dust-laden air velocity sensor, the dust-laden air velocity sensor being arranged at an outlet end of the dust-laden air (7) of the medium-speed coal mill (2) and being used to detect the wind velocity at the outlet end of the dust-laden air (7) of the medium-speed coal mill (2); a dust-laden air mass flow sensor, the dust-laden air mass flow sensor being arranged at an outlet end of the dust-laden air (7) of the medium-speed coal mill (2) and being used to detect the mass flow of the dust-laden air at the outlet end of the dust-laden air (7) of the medium-speed coal mill (2); Based on the first air pressure sensor, the second air pressure sensor, the pulverized coal density sensor, the pulverized air velocity sensor, and the pulverized air mass flow sensor, the current pressure value of the over-grinded hot air (6) to be compensated is calculated as follows: Among them, P ε is the current pressure value of the over-grinding hot air (6) that needs to be compensated. If P ε If P is greater than 0, the pressure of the hot air (6) should be increased. ε If it is less than 0, the pressure of the hot air (6) should be reduced. i is the detection value of the first air pressure sensor, e is a natural number, the value is 2.72, Δ0 is the reference pulverized coal output of the medium-speed coal mill (2), P o is the detection value of the second air pressure sensor, ξ is the air flow friction resistance coefficient in the medium-speed coal mill (2), L is the length of the drum of the medium-speed coal mill (2), D is the diameter of the drum of the medium-speed coal mill (2), δ1 is the detection value of the coal powder density sensor, υ χ is the detection value of the dust-carrying air velocity sensor, g is the acceleration of gravity, which is 9.81, Τ is the detection value of the dust-carrying air mass flow sensor, and σ is the volume ratio of the coal powder and hot air in the dust-carrying air (7).

6. The system for increasing the primary air temperature at the outlet of a medium-speed coal mill according to claim 1, characterized in that: Also includes: A powder collecting machine fault monitoring system, the powder collecting machine fault monitoring system is arranged on the powder collecting machine (9) and is used to monitor the working state of the powder collecting machine (9), the powder collecting machine fault monitoring system comprises: a first flow velocity sensor, the first flow velocity sensor being arranged at a powder inlet end (900) of the powder collector (9) and being used to detect the flow velocity of the pulverized coal at the powder inlet end (900) of the powder collector (9); a density sensor, the density sensor being arranged in the air-powder separation chamber (9000) and being used to detect the density of the coal powder in the air-powder separation chamber (9000); a second flow rate sensor, the second flow rate sensor being arranged at the spray outlet (9010) and being used to detect the flow rate of the water mist sprayed from the spray outlet (9010); a pressure sensor, the pressure sensor being arranged in the air-powder separation chamber (9000) and being used to detect the pressure in the air-powder separation chamber (9000); a temperature sensor, the temperature sensor being arranged in the air-powder separation chamber (9000) and being used for detecting the temperature in the air-powder separation chamber (9000); A controller, a fault alarm, wherein the controller is electrically connected to the first flow rate sensor, the density sensor, the second flow rate sensor, the pressure sensor, the temperature sensor and the fault alarm, and the controller controls the fault alarm to alarm based on the first flow rate sensor, the density sensor, the second flow rate sensor, the temperature sensor and the pressure sensor.

7. The system for increasing the primary air temperature at the outlet of a medium-speed coal mill according to claim 6, characterized in that: The controller controls the fault alarm to alarm based on the first flow rate sensor, the density sensor, the second flow rate sensor, and the pressure sensor, including the following steps: Step 1: Based on the first flow velocity sensor, the temperature sensor and formula (1), calculate the natural settling efficiency of the pulverized coal: Among them, β1 is the natural settling efficiency of coal powder, d max is the maximum preset coal powder diameter, d min is the minimum preset coal powder diameter, V is the volume of the air-powder separation chamber (9000), g is the acceleration of gravity, which is 9.81, ε α is the dynamic viscosity of air, θ o is the detection value of the first flow velocity sensor, θ is the preset flow velocity of the pulverized coal, m0 is the preset mass of the pulverized coal, e is a natural number, and its value is 2.72, T1 is the detection value of the temperature sensor, and T0 is the preset temperature of the air-powder separation chamber (9000); Step 2: Based on the first flow rate sensor, the density sensor, the second flow rate sensor, the pressure sensor and formula (2), the actual comprehensive powder collection efficiency of the powder collector (9) is calculated: Wherein, β2 is the actual comprehensive powder collection efficiency of the powder collector (9), ρ is the detection value of the density sensor, θ m is the detection value of the second flow velocity sensor, M q is the preset mass of the water mist, p st is the detection value of the pressure sensor, p is the preset air pressure, and d is the preset diameter of the water mist; Step three: the controller compares the actual comprehensive powder collection efficiency of the powder collector (9) with the preset comprehensive powder collection efficiency of the powder collector (9); if the actual comprehensive powder collection efficiency of the powder collector (9) is less than the preset comprehensive powder collection efficiency of the powder collector (9), the controller controls the fault alarm to sound an alarm.

8. The system for increasing the primary air temperature at the outlet of a medium-speed coal mill according to claim 2, characterized in that: The combustion-supporting gas includes any one or more of oxygen, ozone, fluorine, and carbon dioxide.

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