Quantitative coal ash blending combustion device of medium-speed coal mill and control method

Abstract

The invention provides a quantitative coal ash blending combustion device of a medium-speed coal mill and a control method, and belongs to the technical field of quantitative control over coal ash conveying. Comprising an electric precipitation ash conveying pipeline, an ash bin and a multi-outlet rotary feeding injection pump which are connected in sequence, the ash bin is used for storing fly ash conveyed by the ash conveying pipeline, and the bottom of the ash bin is communicated with the multi-outlet rotary feeding injection pump; a rotary feeding device is installed at the outlet end of the multi-outlet rotary feeding injection pump and connected with the medium-speed coal mill through a coal mill coal falling pipe. The rotary feeding device comprises a plurality of feeding outlets, each feeding outlet is connected with a medium-speed coal mill through a coal mill coal falling pipe, and a pneumatic control valve is arranged at the joint of each feeding outlet and the coal mill coal falling pipe and used for achieving quantitative blending combustion of coal ash of the medium-speed coal mills. The coal ash can be quantitatively, controllably, accurately and uniformly conveyed into the medium-speed coal mill, and stable blending combustion is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of fly ash conveying quantitative control, and in particular relates to a fly ash quantitative blending and burning device for a medium-speed coal mill and a control method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] At present, in the process of coal blending in thermal power plants, people are looking for an environmentally friendly blending device with strong stability, high safety and high precision. For example, most of the current power plants carry out small-proportion blending by spreading coal, piling coal with forklifts, etc.

[0004] The inventors have found that the current method of coal blending in small proportions by spreading coal, piling coal with shovels, etc. in power plants not only pollutes the environment, but also has many problems that limit the continuity, uniformity and operability of the blending during actual blending, especially in the blending of slag, fly ash or other powdered combustibles, making it impossible to control the blending ratio. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a medium-speed coal mill fly ash quantitative blending combustion device and control method, which can quantitatively, controllably, accurately and evenly transport fly ash to the medium-speed coal mill to achieve stable blending combustion.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of the present invention provides a medium-speed coal mill fly ash quantitative blending device, comprising: an electrostatic precipitator ash conveying pipeline, an ash bin and a multi-outlet rotary feed injection pump connected in sequence;

[0008] The ash bin is used to store fly ash transported from the electrostatic precipitator ash transport pipeline, and the bottom of the ash bin is connected to the inlet end of the multi-outlet rotary feed injection pump;

[0009] A rotary feeding device is installed at the outlet end of the multi-outlet rotary feeding injection pump, and the access point of the rotary feeding device is arranged in the middle of the coal dropping pipe of the coal mill. The rotary feeding device is connected to the medium-speed coal mill through the coal dropping pipe of the coal mill. Specifically: the rotary feeding device includes multiple feeding outlets, each of which is connected to a medium-speed coal mill through a coal dropping pipe of the coal mill, and a pneumatic control valve is provided at the connection between each feeding outlet and the coal dropping pipe of the coal mill, so as to realize the quantitative blending of fly ash of the medium-speed coal mill.

[0010] Furthermore, a set of pneumatic ball valves and manual ball valves are provided at the connection between each coal mill coal drop pipe and the medium-speed coal mill to control the on-off of ash delivery of the medium-speed coal mill.

[0011] Furthermore, the multi-outlet rotary feeding spray pump is composed of two upper and lower series tanks; wherein the upper tank is an air lock tank, the lower tank is a spray tank, and the rotary feeding device is installed at the outlet end below the spray tank.

[0012] Furthermore, a feed valve is provided at the inlet of the upper tank and the lower tank respectively, and the inflow state of fly ash can be changed by controlling the opening and closing of the upper tank feed valve and the lower tank feed valve.

[0013] Furthermore, a first pipeline and a second pipeline are provided between the upper tank and the lower tank; wherein a balancing valve is provided on the first pipeline.

[0014] Furthermore, the quantitative blending device also includes a third pipeline and a compressed air storage tank for providing a source for a multi-outlet rotary feed injection pump;

[0015] The compressed air storage tank is connected to the second pipeline through a third pipeline, and a throttle valve is provided at the connection between the second pipeline and the third pipeline for controlling the flow rate of the air source delivered by the compressed air storage tank.

[0016] Furthermore, a bag filter and an exhaust valve are arranged on the top of the ash bin, and an ash bin outlet valve is arranged on the bottom of the ash bin.

[0017] Furthermore, a high and low material level meter is arranged on the side wall of the ash bin to monitor the height of the fly ash in the multi-outlet rotary feeding injection pump.

[0018] Furthermore, the quantitative blending and combustion device also includes a compressed air purging interface; the compressed air purging interface is arranged on the coal chute of the coal mill, that is, the factory compressed air is connected to the coal chute of the coal mill through the compressed air purging interface to deal with the problem of ash blockage in the pipeline.

[0019] Furthermore, a pressure gauge is provided on each coal chute of the coal mill to detect the ash conveying pressure in the coal chute of the coal mill.

[0020] The second aspect of the present invention provides a method for controlling the quantitative blending and burning of fly ash in a medium-speed coal mill, which is applied to the quantitative blending and burning device as described in the first aspect, comprising:

[0021] When the material in the lower tank is lower than the low material level, the DCS system controls the exhaust valve of the upper tank to open; when the pressure of the upper tank drops to 0.2 Barg, the DCS system controls the feed valve of the upper tank to open, and at the same time opens the fluidizing gas source at the ash bin outlet; when loading, open the fluidizing gas source at the bottom of the upper tank;

[0022] When the upper tank is filled to a high material level, the upper tank feed valve and exhaust valve are closed in sequence; when the upper tank pressure is consistent with the lower tank pressure, the lower tank feed valve and the upper tank top air intake valve are opened; after the first set time, the upper tank air intake valve is closed and the balance valve is opened; after the second set time, the upper tank fluidizing gas source, the intermediate valve and the balance valve are closed in sequence;

[0023] When the material in the lower tank drops below the lower material level, open the exhaust valve of the upper tank again and start a new round of loading in the upper tank.

[0024] One or more of the above technical solutions have the following beneficial effects:

[0025] The present invention is provided with a rotary feeding device at the outlet end of a multi-outlet rotary feeding injection pump, the rotary feeding device comprising a plurality of feeding outlets, each of which is connected to a medium-speed coal mill through a coal mill coal drop pipe, and a pneumatic control valve is provided at the connection between each feeding outlet and the coal mill coal drop pipe. The feeding amount can be controlled by adjusting the pneumatic control valve, so the present invention can realize the quantitative blending and burning of fly ash of the medium-speed coal mill.

[0026] The present invention sets the access point of the rotary feeding device in the middle of the coal drop pipe of the coal mill, and the rotary feeding device is connected to the medium-speed coal mill through the coal drop pipe of the coal mill. The design of the access point is more reasonable, and the fly ash can fall into the grinding disc along with the coal flow and be evenly delivered to the corner burners in each medium-speed coal mill, solving the problem of uneven blending.

[0027] The present invention connects the ash conveying pipeline with the coal chute of the coal mill, can evenly deliver the fly ash to the coal chute at the inlet of the coal mill in a set ratio, and deliver the fly ash to different coal mills in a set ratio according to the needs of boiler combustion.

[0028] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 It is a schematic diagram of the overall structure of a fly ash quantitative blending and burning device for a medium-speed coal mill in an embodiment of the present invention.

[0031] In the figure, 1 electrostatic precipitator ash conveying pipeline; 2 ash bin; 21 bag filter; 22 emptying valve; 23 ash bin outlet valve; 24 high and low material level gauge; 3 multi-outlet rotary feeding injection pump; 31 upper tank; 32 lower tank; 33 upper tank feed valve; 34 lower tank feed valve; 4 rotary feeding device; 5 coal mill coal drop pipe; 6 discharge outlet; 7 medium-speed coal mill; 8 pneumatic control valve; 9 pneumatic ball valve; 10 manual ball valve; 11 first pipeline; 12 second pipeline; 13 third pipeline; 14 balance valve; 15 compressed air storage tank; 16 throttle valve; 17 compressed air spray interface; 18 pressure gauge; 19 plant compressed air system. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0033] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0034] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0035] In the actual production process, the blending of fly ash has great uncertainty, and its impact on boiler combustion is difficult to accurately predict, and it is even more difficult to control the blending ratio; therefore, in the preparation for blending, it is necessary to focus on the uniformity, stability and continuity of the blending to avoid the risk of boiler coking. To this end, this embodiment discloses a medium-speed coal mill fly ash quantitative blending device and control method to solve the problem of poor blending uniformity, stability and continuity and difficulty in controlling the blending ratio during the fly ash blending process.

[0036] Embodiment 1

[0037] like Figure 1 As shown, a medium-speed coal mill fly ash quantitative blending device comprises: an electrostatic precipitator ash conveying pipeline 1, an ash bin 2 and a multi-outlet rotary feed injection pump 3 connected in sequence;

[0038] The ash bin 2 is used to store the fly ash transported from the electrostatic precipitator ash conveying pipeline 1 , and the bottom of the ash bin 2 is connected to the inlet end of the multi-outlet rotary feeding injection pump 3 .

[0039] Specifically, the ash hopper of the electrostatic precipitator is selected as the ash source, and the ash is transported to the ash bin through the electrostatic precipitator ash conveying pipeline. Then the conveying amount is controlled by the rotary feeding device and conveyed to the coal drop pipe of the coal mill through compression control, which solves the problem of discontinuous ash conveying connection. Specifically, the ash bin built outside the electrostatic precipitator has a capacity of 100m3 and has a large enough space to accommodate fly ash. A 60㎡ bag dust collector 21 and an emptying valve 22 are arranged on the top of the ash bin, and an ash bin outlet valve 23 is arranged at the bottom of the ash bin; wherein the bag dust collector is used for collecting and filtering dust, and the emptying valve is used to discharge the gas in the ash bin. At the same time, a high and low level meter 24 is also arranged on the side wall of the ash bin. The high and low level meter includes three level meters: high, medium and low, which are used to monitor the height of the fly ash in the multi-outlet rotary feeding injection pump.

[0040] The outlet end of the multi-outlet rotary feed injection pump 3 is equipped with a rotary feed device 4, and the access point of the rotary feed device 4 is set in the middle of the coal mill coal drop pipe 5. The design of the access point allows the fly ash to fall into the grinding disc along with the coal flow and be evenly delivered to the corner burners in each medium-speed coal mill, thereby effectively solving the problem of uneven blending of fly ash. In addition, the coal mill coal drop pipe adopts a DN80 lined wear-resistant alloy pipe, which can better prevent the pipe from wear or leakage compared to pipes of general materials, thereby ensuring the stability of fly ash during transportation.

[0041] Furthermore, the rotary feeding device is connected to the medium-speed coal mill through the coal chute of the coal mill. Specifically, the rotary feeding device 4 includes a plurality of feeding outlets 6, each of which is connected to a medium-speed coal mill 7 through a coal chute of the coal mill 5, and a pneumatic control valve 8 is provided at the connection between each feeding outlet 6 and the coal chute of the coal mill 5, for realizing the quantitative blending and burning of fly ash of the medium-speed coal mill. In the specific implementation process, the rotary feeding device is controlled by a frequency converter installed in the electrical cabinet. The feeding amount can be controlled by adjusting the rotation speed of the rotary feeding device and the pneumatic control valve, thereby realizing the quantitative blending and burning of fly ash of the medium-speed coal mill.

[0042] Specifically, there are four feed outlets and four medium-speed coal mills, that is, each of the four feed outlets is connected to one of the four medium-speed coal mills through a coal mill drop pipe. It should be noted that the four coal mill drop pipes are independent of each other, and the multi-outlet rotary feed injection pump delivery system allows the delivery volume of the four coal mill drop pipes to be adjusted from 0-4t / h separately to achieve small-proportion quantitative blending; therefore, different air pressure intensities can be adjusted on the pneumatic control valves on each coal mill drop pipe to deliver different feed volumes to the four medium-speed coal mills, and each medium-speed coal mill is supplied with ash separately, and the ash delivery pipeline uses anti-wear carbon steel pipes to ensure the stability of ash supply.

[0043] Furthermore, a set of pneumatic ball valves 9 and manual ball valves 10 are provided at the connection between each coal mill coal drop pipe and the medium-speed coal mill to control the ash supply on and off of the medium-speed coal mill.

[0044] The manual ball valve is normally open during normal operation. When the compressed air system for the entire plant is put into use, it is controlled by a pneumatic ball valve to realize the on and off of the random combination of transportation and blending of multiple coal mills. Taking medium-speed coal mill A as an example, as long as the pneumatic ball valve on the coal drop pipe of the coal mill connected to medium-speed coal mill A meets any one of the following conditions, the pneumatic ball valve will be closed. When the pneumatic ball valve at the inlet of medium-speed coal mill A is interlocked and closed, the ash conveying will be automatically cut off. Specifically, the interlocking closing conditions are: (1) The outlet air pressure of medium-speed coal mill A is less than 1.0 kPa; (2) Medium-speed coal mill A sends a trip signal; (3) Medium-speed coal mill A sends a stop signal; (4) The boiler MFT, that is, the boiler main fuel trips. If any of the conditions are met, the pneumatic ball valve at the inlet of medium-speed coal mill A will be interlocked and closed to realize the ash conveying cut-off.

[0045] Furthermore, the multi-outlet rotary feed injection pump is composed of two upper and lower series tanks; wherein the upper tank is an air lock tank, the lower tank is a spray tank, and the rotary feeder is installed at the outlet end below the spray tank. A feed valve is provided at the inlet of the upper tank and the lower tank respectively, and the inflow state of fly ash can be changed by controlling the opening and closing of the upper tank feed valve and the lower tank feed valve; at the same time, a first pipeline 11 and a second pipeline 12 are also provided between the upper tank and the lower tank, wherein a balancing valve 14 is provided on the first pipeline. Specifically, the balancing valve connects the upper tank and the lower tank, and when it is opened, the upper and lower tanks are connected, so that the pressure in the tank remains consistent, achieving the effect of balancing the pressure.

[0046] The medium-speed coal mill fly ash quantitative blending combustion device provided in this embodiment also includes a third pipeline 13 and a compressed air storage tank 15 with a volume of 5m3 for providing a source for a multi-outlet rotary feed injection pump.

[0047] Specifically, the compressed air storage tank is connected to the plant compressed air system 19 to provide power for the fly ash blending of the medium-speed coal mill; the entire plant compressed air system is controlled by a DCS system (distributed control system), and unmanned automatic control can be achieved by adding logical protection of important valves based on the DCS system. The compressed air storage tank is connected to the second pipeline through a third pipeline, and a throttle valve 16 is provided at the connection between the second pipeline and the third pipeline to control the air source flow delivered by the compressed air storage tank.

[0048] The quantitative blending device also includes a compressed air purging interface 17; the compressed air purging interface is arranged on the coal ditch pipe of the coal mill, that is, the factory compressed air is connected to the coal ditch pipe of the coal mill through the compressed air purging interface to deal with the ash blockage problem of the pipeline. A pressure gauge 18 is arranged on each coal ditch pipe of the coal mill to detect the ash conveying pressure in the coal ditch pipe of the coal mill.

[0049] Embodiment 2

[0050] In this embodiment, the present invention provides a method for controlling the quantitative blending and burning of fly ash in a medium-speed coal mill, which is applied to the quantitative blending and burning device as described in the first embodiment, specifically:

[0051] When the multi-outlet rotary feeder injection pump is spraying normally, the upper tank is empty, the ash bin outlet valve, upper tank feed valve, exhaust valve, lower tank feed valve and balance valve are all in a closed state, the lower tank spray and fluidizing gas source can be supplied uninterruptedly, and the rotary feeder runs at the set speed;

[0052] The quantitative blending device is connected to the DCS system and controlled by the DCS system; two material level signal switches are set in the tank. When the material in the lower tank is lower than the low material level, the material level meter sends a signal. At this time, the DCS system controls the upper tank exhaust valve to open, releasing the residual pressure in the upper tank, and the balance valve and the lower tank feed valve are still in the closed state; when the upper tank pressure shows that the upper tank pressure drops to 0.2Barg, the DCS system controls the upper tank feed valve to open, and at the same time opens the fluidizing gas source at the ash bin outlet (it can be opened manually on the DCS system or through logical connection); at this time, loading begins. During loading, the fluidizing gas source at the bottom of the upper tank is opened, and the compressed air storage tank blows gas into the upper tank from the bottom of the upper tank through the third pipeline and the second pipeline in turn to prevent the upper tank powder from accumulating and agglomerating.

[0053] When the upper tank is loaded to a high level, the level meter sends a signal. After a short delay, the feed valve and exhaust valve of the upper tank are closed in turn, and the loading stops. At this time, the fluidizing gas source at the bottom of the upper tank is still continuously entering the upper tank, and the pressure of the upper tank rises. When the pressure of the upper tank reaches the same level as the pressure of the lower tank, the feed valve of the lower tank opens, and the powder in the upper tank falls into the lower tank by its own gravity; to help with the unloading, the air inlet valve at the top of the upper tank is opened. At this time, the flow rate of the conveying gas source is controlled by the throttle valve to keep the gas volume entering the pump body constant. After the first set time, the air inlet valve of the upper tank is closed and the balance valve is opened; after the second set time, the fluidizing gas source, the intermediate valve (the feed valve of the lower tank) and the balance valve of the upper tank are closed, and the tank inversion is completed. It should be noted that the first set time and the second set time can be set according to actual needs, and this embodiment does not make specific restrictions here.

[0054] When the material in the lower tank drops below the low material level, the exhaust valve of the upper tank is opened again, and a new round of loading of the upper tank is started, thus completing an operation cycle. When the material (fly ash) in the lower tank needs to be put into the coal mill for blending, the multi-outlet rotary feeding injection pump and the rotary feeding device work, and the material is transported to the medium-speed coal mill through the fly ash coal drop pipe. During the transportation process, the pneumatic control valve on each coal mill coal drop pipe cooperates with the pneumatic ball valve and the manual ball valve to transport fly ash to different coal mills at a set ratio according to the air pressure displayed on each coal mill coal drop pipe or according to the needs of boiler combustion. By controlling the three valves on the pipeline, quantitative transportation of each pipeline can be completed to different degrees; at the same time, the compressed air on the coal mill coal drop pipe is continuously sprayed to ensure that there is no ash blockage problem in the pipeline. Therefore, the present application can realize the quantitative, controllable, precise and uniform transportation of fly ash to the medium-speed coal mill to achieve stable blending.

[0055] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0056] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A medium-speed coal mill fly ash quantitative blending device, characterized in that: include: The electrostatic precipitator ash conveying pipeline, ash bin and multi-outlet rotary feed injection pump are connected in sequence; The ash bin is used to store the fly ash transported from the electrostatic precipitator ash transport pipeline, and the bottom of the ash bin is connected to the inlet end of the multi-outlet rotary feed injection pump; A rotary feeding device is installed at the outlet end of the multi-outlet rotary feeding injection pump, and the access point of the rotary feeding device is arranged in the middle of the coal dropping pipe of the coal mill. The rotary feeding device is connected to the medium-speed coal mill through the coal dropping pipe of the coal mill. Specifically: the rotary feeding device includes multiple feeding outlets, each of which is connected to a medium-speed coal mill through a coal dropping pipe of the coal mill, and a pneumatic control valve is provided at the connection between each feeding outlet and the coal dropping pipe of the coal mill, so as to realize the quantitative blending of fly ash of the medium-speed coal mill.

2. A medium-speed coal mill fly ash quantitative blending device as claimed in claim 1, characterized in that: A set of pneumatic ball valves and manual ball valves are installed at the connection between each coal mill coal drop pipe and the medium-speed coal mill to control the ash supply of the medium-speed coal mill.

3. A medium-speed coal mill fly ash quantitative blending and burning device as claimed in claim 1, characterized in that: The multi-outlet rotary feeding spray pump is composed of two upper and lower series tanks; wherein the upper tank is an air lock tank, the lower tank is a spray tank, and the rotary feeding device is installed at the outlet end below the spray tank.

4. A medium-speed coal mill fly ash quantitative blending device as claimed in claim 3, characterized in that: A feed valve is respectively arranged at the inlet of the upper tank and the lower tank, and the inflow state of fly ash can be changed by controlling the opening and closing of the upper tank feed valve and the lower tank feed valve.

5. A medium-speed coal mill fly ash quantitative blending device as claimed in claim 3, characterized in that: A first pipeline and a second pipeline are also arranged between the upper tank and the lower tank; wherein a balancing valve is arranged on the first pipeline.

6. A medium-speed coal mill fly ash quantitative blending and burning device as claimed in claim 5, characterized in that: Also included is a third conduit and a compressed air storage tank for supplying a source to a multi-outlet rotary feed injection pump; The compressed air storage tank is connected to the second pipeline through a third pipeline, and a throttle valve is provided at the connection between the second pipeline and the third pipeline for controlling the flow rate of the air source delivered by the compressed air storage tank.

7. The medium-speed coal mill fly ash quantitative blending and burning device as claimed in claim 1, characterized in that: A bag dust collector and an emptying valve are arranged on the top of the ash bin, and an ash bin outlet valve is arranged at the bottom of the ash bin; a high and low material level meter is arranged on the side wall of the ash bin to monitor the height of the fly ash in the multi-outlet rotary feeding injection pump.

8. The medium-speed coal mill fly ash quantitative blending and burning device as claimed in claim 1, characterized in that: It also includes a compressed air purging interface; the compressed air purging interface is arranged on the coal chute of the coal mill, that is, the factory compressed air is connected to the coal chute of the coal mill through the compressed air purging interface to deal with the problem of ash blockage in the pipeline.

9. The medium-speed coal mill fly ash quantitative blending and burning device as claimed in claim 1, characterized in that: A pressure gauge is provided on each coal hopper of the coal mill to detect the ash conveying pressure in the coal hopper of the coal mill.

10. A method for controlling the quantitative blending and burning of fly ash in a medium-speed coal mill, applied to the quantitative blending and burning device as claimed in any one of claims 1 to 9, characterized in that: include: When the material in the lower tank is lower than the low material level, the DCS system controls the exhaust valve of the upper tank to open; when the pressure of the upper tank drops to 0.2 Barg, the DCS system controls the feed valve of the upper tank to open, and at the same time opens the fluidizing gas source at the ash bin outlet; when loading, open the fluidizing gas source at the bottom of the upper tank; When the upper tank is filled to a high material level, the upper tank feed valve and exhaust valve are closed in sequence; when the upper tank pressure is consistent with the lower tank pressure, the lower tank feed valve and the upper tank top air intake valve are opened; after the first set time, the upper tank air intake valve is closed and the balance valve is opened; after the second set time, the upper tank fluidizing gas source, the intermediate valve and the balance valve are closed in sequence; When the material in the lower tank drops below the lower material level, open the exhaust valve of the upper tank again and start a new round of loading in the upper tank.

Images