CN108644803A - A kind of wind powder real-time leveling device and leveling method - Google Patents

Abstract

The invention discloses a kind of wind powder real-time leveling device and leveling methods, including：Separator for coal mill, boiler and multiple pulverized coal channels, separator for coal mill and boiler are connected by multiple pulverized coal channels；Multiple pulverized coal channels are inverted u-shaped, including two vertical sections and horizontal segment, and each pulverized coal channel is mounted on pressure tap in the vertical section of separator for coal mill one end, and the position height of pressure tap installation is identical；It is respectively connected with pressure difference transmitter between per adjacent pressure tap；Dragulator is mounted on horizontal segment；Further include control module, control module is electrically connected with pressure difference transmitter and dragulator.Wind powder real-time leveling device provided by the invention, can adjust coal pulverizer between boiler in pulverized coal channel coal dust and wind flow, reduce the deviation of the coal dust amount and wind that convey in each pulverized coal channel, form closed loop, it is automatic to carry out wind powder control, improve the combustibility of boiler.

Description

An air powder real-time leveling device and leveling method

technical field

The invention relates to the technical field of boiler combustion in a coal-fired power plant, and more specifically relates to an air powder real-time leveling device and a leveling method.

Background technique

At present, coal-fired power plants mostly use positive pressure direct-blowing pulverization system. Since the pulverized coal pulverized by the coal mill is directly blown into the boiler for combustion, in order to ensure the combustion stability and combustion rate of the boiler, it is required that each pulverized coal pipe pulverized coal The concentration, flow rate, and fineness of pulverized coal should be kept as balanced as possible. The concentration of pulverized coal in the coal mill separator is relatively uniform, but the pulverized coal pipeline from the coal mill to the boiler is nearly 100 meters long and 20-30 meters short. The length of the pipelines is quite different, and the direction of different pipelines is also very different, resulting in a large difference in the resistance loss along the pipeline and the local resistance loss. The primary wind speed in the pipeline with small total resistance is high, and the amount of coal powder carried It is also large, and the primary wind speed in the pipeline with large total resistance is low, and the amount of pulverized coal carried is small, resulting in uneven wind powder in the pulverized coal pipeline.

Air powder is a mixture of coal powder and conveying medium air; the main reason for the uneven air powder is the unbalanced resistance loss in the pulverized coal pipeline. The current air powder leveling methods are as follows:

1. Cold leveling method: In the absence of pulverized coal, use the shrinkage control valve to adjust the resistance in the pipeline, and measure the wind speed in the pipeline to judge whether the air volume is balanced, and usually adjust the air volume to a deviation of less than 5%;

2. Balance valve thermal state adjustment method: Install a balance valve with adjustable opening in the pulverized coal pipeline, and install a sensor for measuring the concentration and flow rate of pulverized coal at the same time, compare the measured data of different pulverized coal pipelines, and according to the comparison The results are used as the basis for adjusting the opening of the balance valve, and the air powder is adjusted through closed-loop control.

The above pulverized coal leveling method has the following problems:

①. The air volume is balanced in the cold state, but in the hot state, the air volume and powder volume are uneven; ②. The adjustment method is backward and cannot be adjusted in real time, which cannot meet the actual needs; ③. The measurement method does not match the environment in the pipeline. It is impossible to provide the correct basis for adjusting the environment; ④, the reliability of the measuring element is poor, easy to wear and short in life.

Therefore, how to provide a wind powder real-time leveling device and leveling method is a problem urgently needed to be solved by those skilled in the art.

Contents of the invention

In view of this, the present invention provides a real-time air powder leveling device and leveling method, which can adjust the flow rate of pulverized coal and conveying medium in the pulverized coal pipeline between the coal mill and the boiler, and reduce the transportation of pulverized coal in each pulverized coal pipeline. The deviation of the amount of pulverized coal and the conveying medium improves the combustion performance of the boiler.

In order to achieve the above object, the present invention adopts the following technical solutions:

A wind powder real-time leveling device, comprising: a coal mill separator, a boiler and a plurality of pulverized coal pipelines, the coal pulverizer separator and the boiler are connected through a plurality of pulverized coal pipelines; a plurality of the pulverized coal The pipelines are all inverted U-shaped, including two vertical sections and a horizontal section, each of the pulverized coal pipelines is equipped with a pressure measuring point on the vertical section near the end of the pulverizer separator, and multiple The positions where the pressure measuring points are installed are at the same height, and a differential pressure transmitter is connected between each adjacent pressure measuring point; resistance regulators are installed on the horizontal sections; a control module is also included, and the The control module is electrically connected with the differential pressure transmitter and the resistance regulator.

Preferably, the multiple resistance adjusters are installed at the same position.

Preferably, the control module is preset with a differential pressure setting value that can balance the primary air flow in the pulverized coal pipeline.

The invention also discloses a real-time leveling method for air powder, which includes the following steps:

S1. Set the opening of the resistance regulator at 80% of the maximum opening; preset the pressure difference setting value of the primary air flow balance in the pulverized coal pipeline in the control module;

S2. Start the coal mill separator, and use the differential pressure transmitter to measure the pressure difference at the corresponding two adjacent pressure measurement points;

S3. The control module sends an adjustment command to the resistance regulator according to the pressure difference measured in step S2 to adjust the opening until the pressure difference is less than the set value of the pressure difference.

Preferably, when the load of the coal pulverizer separator changes, the air powder flow rate and flow in the pulverized coal pipeline are unbalanced, and when the measured value of the differential pressure transmitter exceeds the set value of the differential pressure, the The control module sends an adjustment command to the resistance regulator until the air powder in the plurality of pulverized coal pipelines reaches a balance.

It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a real-time air powder leveling device and leveling method, the pressure measurement point is at the vertical section of the pulverized coal pipeline above the coal mill separator and At the same high position, using a differential pressure transmitter to measure the pressure difference between adjacent pulverized coal pipelines not only eliminates the measurement system error, but also has high measurement accuracy, and the differential pressure transmitter is not inserted into the pulverized coal pipeline as a measuring element Internally, it will not interfere with the fluid in the pulverized coal pipeline, nor will it cause wear of the measuring element.

At the same time, the resistance regulator is installed on the pulverized coal pipeline in the horizontal section after the pressure measurement point, which will reduce the kinetic energy loss before and after the resistance regulator and improve the accuracy of resistance adjustment; moreover, the control module will compare the measured pressure difference with the pressure difference Compared with the set value, when the differential pressure value is greater than the differential pressure set value, an adjustment command is sent to the resistance regulator to adjust the internal resistance of the pulverized coal pipeline until the differential pressure value is less than the differential pressure set value to ensure that the air powder reaches Dynamic balance for real-time control.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

The accompanying drawing of Fig. 1 is a structural schematic diagram of the air powder real-time leveling device provided by the present invention.

Figure 2 is a schematic flow chart of the real-time leveling method for air powder provided by the present invention.

Figure 3 is a schematic diagram of the reference section parameters provided by the present invention.

Reference numerals are: 1 is a coal mill separator, 2 is a pressure measuring point, 3 is a pressure transmitter, 4 is a pulverized coal pipeline, 5 is a resistance regulator, 6 is a boiler, and 7 is a control module.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

With reference to accompanying drawing 1, the embodiment of the present invention discloses a real-time air powder leveling device, a pressure measuring point 2 is installed on the vertical section of the pulverized coal pipeline above the coal mill separator 1, and pressure is measured on a plurality of pulverized coal pipelines 4 The position of point 2 is at the same height to ensure that the pressure loss from the coal mill separator 1 to the pressure measurement point 2 is consistent, and a differential pressure transmitter 3 is installed between two adjacent pressure measurement points 2 for measuring phase The pressure difference at the pressure measuring point 2 of two adjacent pulverized coal pipelines 4; resistance regulators 5 are installed on the horizontal sections of the pulverized coal pipelines 4.

Fluid wind powder, that is, the mixture of pulverized coal and conveying medium wind, will produce energy loss when passing through the resistance regulator, including kinetic energy loss along the direction of pulverized coal pipeline and kinetic energy loss caused by gravity in the vertical direction: when installed in the horizontal section, the coal The diameter of the powder pipeline is small (generally about 0.4m), and the vertical loss caused by gravity is small. During the horizontal forward movement of the fluid, the kinetic energy loss before and after passing through the resistance regulator is small, and has little effect on the moving speed of the fluid. ; When installed in the vertical section, when the fluid rises in the vertical direction, due to the long vertical pulverized coal pipeline (generally above 3m), the energy loss caused by gravity is very large, and the kinetic energy before and after passing through the resistance regulator The loss is large and has a great influence on the rising speed of the fluid. Therefore, the resistance regulator is installed on the horizontal section, which can reduce the kinetic energy loss of the fluid and make the resistance adjustment more accurate.

Referring to accompanying drawing 2, the present invention also discloses a real-time leveling method for air powder, comprising the following steps:

S1, the opening of the resistance regulator 5 is set at 80% of the maximum opening; the pressure difference setting value of the primary air flow balance in the pulverized coal pipeline 4 is preset in the control module 7;

S2. Start the coal mill separator 1, and measure the pressure difference at two adjacent pressure measuring points 2 through the differential pressure transmitter 3;

S3. The control module 7 sends an adjustment command to the resistance regulator according to the pressure difference measured in step S2 to adjust the opening until the pressure difference is less than the set value of the pressure difference.

Moreover, when the load of the coal pulverizer separator 1 changes, the air powder flow velocity and flow rate in the pulverized coal pipeline 4 are unbalanced, and when the measured value of the differential pressure transmitter 3 exceeds the set value of the differential pressure, the control module 7 sends a signal to the resistance regulator. 5. Issue an adjustment command until the air powder in the plurality of pulverized coal pipelines 4 reaches a balance.

The fluid equation applied in the present invention is derived as follows:

First, in order to facilitate formula derivation and calculation, without affecting the calculation results, the following two assumptions are made:

1. Ignoring the influence of pulverized coal on the primary wind, the air-powder mixture is regarded as a single viscous fluid;

The true density of pulverized coal is about 1000kg/m ³ , and the air-to-coal mass ratio in the pulverized-coal pipeline 4 is about 2:1. According to this calculation, the pulverized coal occupies 0.05% of the volume in the pulverized-air mixture. Since the proportion of the volume is very small, So ignore the influence of pulverized coal.

2. The wind powder mixture is an incompressible fluid;

Air is a compressible gas, but the pressure change value at the pressure measuring point 2 relative to the primary air pressure in the coal mill separator 1 is only 300-400pa, which is only 0.3%-0.4% of the absolute pressure of the primary air, so the volume change is ignored , considering the air-powder mixture as an incompressible fluid.

Referring to Fig. 3, the present embodiment is provided with two pulverized coal pipelines 4, pulverized coal pipeline A and pulverized coal pipeline B, correspondingly, on the horizontal section of pulverized coal pipeline A, resistance regulator 5 of pulverized coal pipeline and Pulverized coal pipeline B resistance regulator 5; set the contact surface of coal mill separator 1 and pulverized coal pipeline 4 as reference section 0, set the plane where pressure measuring point 2 is located as reference section 1, and set pulverized coal pipeline 4 The contact surface with the boiler 6 is set as the reference section 2;

in,

The meaning of each parameter symbol is:

Z is the potential energy, V is the fluid velocity, P is the static strength at the reference section, △P is the resistance loss from the reference section to the cross section of the coal mill separator, ρ is the fluid density, and g is the acceleration of gravity;

Meaning of subscript symbols:

A is pulverized coal pipeline A, B is pulverized coal pipeline B, M is the cross section of coal mill separator, 0 is 0 section, 1 is 1 section;

Parameter symbols and subscript symbols are used in combination, for example, P _A0 is the static pressure at the reference section 0 in the pulverized coal pipeline A, Z _m is the potential energy at the separator of the coal mill, and _PM is the static strength of the separator section of the coal mill , V _m is the fluid velocity at the section of the pulverizer separator, V _A is the fluid velocity in the pulverized coal pipeline A, ΔP _A0 is the resistance loss from the reference section 0 in the pulverized coal pipeline A to the section of the pulverizer separator, and ΔP _A1 is The resistance loss from reference section 1 to the pulverizer separator section in pulverized coal pipeline A; similarly, the lower corner marked as B represents the corresponding value in pulverized coal pipeline B.

According to the viscous fluid Bernoulli equation, the following equations are established for pulverized coal pipelines A and B:

The pulverized coal pipeline is evenly and symmetrically arranged on the separator, and the size of the pulverized coal pipeline is the same, so the resistance loss at section 0 is △P _A0 = △P _B0 , the same reason is due to the size and layout of the pipeline between section 0 and section 1 Similarly, the resistance loss at section 1 ΔP _A1 = ΔP _B1 . Therefore, through formula 1 and formula 2, we can get

It can be seen from formula 3 that as long as the static pressure value P _A1 =P _B1 at section 1 is referred to, it proves that the flow velocity V _A =V _B in pulverized coal pipeline A and pulverized coal pipeline B; The diameters are the same, so the primary air flow in each pulverized coal pipeline 4 is equal; the pulverized coal concentration in the pulverizer separator 1 is uniform, so the amount of pulverized coal entering the pulverized coal pipeline 4 is also uniform at this time.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the related information, please refer to the description of the method part.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (5)

1. A wind powder real-time leveling device is characterized in that, comprising: a coal mill separator (1), a boiler (6) and a plurality of pulverized coal pipelines (4), and the coal mill separator (1) It is connected with the boiler (6) through a plurality of pulverized coal pipelines (4); A plurality of the pulverized coal pipelines (4) are in an inverted U shape, including: two vertical sections and a horizontal section, each of the pulverized coal pipelines (4) is close to one end of the pulverizer separator (1) Pressure measuring points (2) are installed on the vertical sections, and a plurality of pressure measuring points (4) are installed at the same height; each adjacent pressure measuring point (2) is connected with a pressure difference Transmitter (3); resistance regulators (5) are installed on the horizontal sections; It also includes a control module (7), and the control module (7) is electrically connected with the pressure difference transmitter (3) and the resistance regulator (5). 2. A wind powder real-time leveling device according to claim 1, characterized in that the installation positions of a plurality of said resistance regulators (5) are the same. 3. A real-time air powder leveling device according to claim 1, characterized in that, the control module (7) is preset with a pressure that can balance the primary air flow in the pulverized coal pipeline (4). difference setting. 4. A real-time leveling method for wind powder, characterized in that, using the wind powder real-time leveling device described in any one of claims 1-3, comprising the following steps: S1, the opening of the resistance regulator (5) is set at 80% of the maximum opening; the pressure difference setting value of the primary air flow balance in the control module (7) is preset in the pulverized coal pipeline (4); S2, start the coal mill separator (1), and use the differential pressure transmitter (3) to measure the pressure difference corresponding to two adjacent pressure measuring points (2); S3. The control module (7) sends an adjustment command to the resistance regulator (5) according to the pressure difference measured in step S2 to adjust the opening until the pressure difference is less than the set value of the pressure difference. 5. A real-time air powder leveling method according to claim 4, characterized in that, when the load of the pulverizer separator (1) changes, the air powder flow velocity in the pulverized coal pipeline (4) and flow unbalanced, and when the measured value of the differential pressure transmitter (3) exceeds the set value of the differential pressure, the control module (7) sends an adjustment command to the resistance regulator (5), until multiple The air powder in the pulverized coal pipeline (4) reaches equilibrium.