A method and device for online optimization of rotary air preheater speed

Abstract

The present invention discloses a method and device for online optimizing the rotation speed of a rotary air preheater, which is applied to a rotary air preheater. The method includes, when the load of a generator set is at a fixed value, adding a rotation speed increment on the basis of the initial rotation speed of the rotary air preheater, and adjusting the rotation speed increment according to the first outlet flue gas temperature change; in the process of adjusting the rotation speed increment, adjusting the rotation speed of the rotary air preheater based on the second outlet flue gas temperature change. Determine the optimal rotation speed according to the outlet flue gas temperature change of the air preheater, so that the heat exchange capacity of the air preheater is greatly improved. Reduce the exhaust temperature, reduce the exhaust heat loss of the boiler, and increase the boiler efficiency. Improve the heat exchange capacity of the air preheater, increase the temperature of the hot primary air and secondary air, and improve the ignition performance and combustion performance of the boiler.

Description

Technical Field

[0001] The present application relates to the field of thermal power generation technology, and more specifically, to a method and device for online optimizing the rotation speed of a rotary air preheater. Background Art

[0002] Air preheater (air preheater) is a heat exchanger located in the tail flue of the boiler. It cools down the flue gas in the tail flue to heat the air before entering the boiler. It can be used to reduce the boiler exhaust temperature to improve boiler efficiency, improve the ignition conditions and combustion process, and the hot air can also be used as a desiccant and conveying medium for coal powder. Commonly used are tubular air preheaters and rotary air preheaters. Among them, rotary air preheaters are widely used in large-capacity units due to their high heat transfer coefficient and steel saving.

[0003] The speed is an important parameter of the rotary air preheater, which is generally determined by the rotor rotation diameter and directly affects the heat exchange performance of the air preheater. Most units will set the optimal speed according to the unit conditions at the initial stage of commissioning or overhaul. However, in the actual operation of the unit, the operating conditions of the rotary air preheater vary greatly due to changes in unit load, boiler heat load, boiler coal type and ash accumulation on the heat storage surface. The fixed speed operation can no longer guarantee that the heat exchange capacity of the air preheater can be fully utilized.

[0004] Therefore, how to optimize the speed adaptability of the air preheater is a technical problem that needs to be solved. Summary of the invention

[0005] The present invention provides a method for online optimizing the rotation speed of a rotary air preheater, which is used to solve the technical problem in the prior art that the rotation speed of the air preheater is fixed and thus the heat exchange capacity cannot be guaranteed. The method is applied to a rotary air preheater, and the method comprises:

[0006] When the load of the generator set is at a fixed value, a speed increment is added to the initial speed of the rotary air preheater, and the speed increment is adjusted according to the change of the first outlet flue gas temperature;

[0007] In the process of adjusting the rotation speed increment, the rotation speed of the rotary air preheater is adjusted based on the second change in the outlet flue gas temperature.

[0008] In some embodiments of the present application, the method further includes:

[0009] The rotation speed increment is obtained based on the accuracy of the rotation speed adjustment.

[0010] In some embodiments of the present application, the rotation speed increment is adjusted according to the change in the first outlet flue gas temperature, specifically:

[0011] If the first outlet flue gas temperature decreases, the initial rotation speed increases by the rotation speed increment, and the rotation speed increment is increased;

[0012] If the first outlet flue gas temperature increases, the initial rotation speed is subtracted from the rotation speed increment and increased by the rotation speed increment.

[0013] In some embodiments of the present application, in the process of adjusting the speed increment, the speed of the rotary air preheater is adjusted based on the second change in the outlet flue gas temperature, specifically:

[0014] When the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to be the sum of the initial speed and the critical speed increment;

[0015] Or, when the outlet flue gas temperature rises for the first time, the speed increment is increased until the outlet flue gas temperature rises for the second time, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment.

[0016] Correspondingly, the present application also provides an online rotary air preheater speed optimization device, which is applied to a rotary air preheater, and the device includes:

[0017] The first adjustment module is used to add a speed increment based on the initial speed of the rotary air preheater when the load of the generator set is at a fixed value, and adjust the speed increment according to the first change in the outlet flue gas temperature;

[0018] The second adjustment module is used to adjust the speed of the rotary air preheater based on the second outlet flue gas temperature change during the process of adjusting the speed increment.

[0019] In some embodiments of the present application, the device further includes an acquisition module for:

[0020] The rotation speed increment is obtained based on the accuracy of the rotation speed adjustment.

[0021] In some embodiments of the present application, the first adjustment module is specifically used to:

[0022] If the first outlet flue gas temperature decreases, the initial rotation speed increases by the rotation speed increment, and the rotation speed increment is increased;

[0023] If the first outlet flue gas temperature increases, the initial rotation speed is subtracted from the rotation speed increment and increased by the rotation speed increment.

[0024] In some embodiments of the present application, the second adjustment module is specifically used to:

[0025] When the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to be the sum of the initial speed and the critical speed increment;

[0026] Or, when the outlet flue gas temperature rises for the first time, the speed increment is increased until the outlet flue gas temperature rises for the second time, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment.

[0027] By applying the above technical solution, the method includes: when the load of the generator set is at a fixed value, adding a speed increment to the initial speed of the rotary air preheater, and adjusting the speed increment according to the change of the first outlet flue gas temperature; in the process of adjusting the speed increment, adjusting the speed of the rotary air preheater based on the change of the second outlet flue gas temperature. The speed increment is obtained based on the accuracy of the speed adjustment. If the first outlet flue gas temperature decreases, the initial speed increases the speed increment and increases the speed increment; if the first outlet flue gas temperature increases, the initial speed is subtracted from the speed increment and increases the speed increment. When the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the sum of the initial speed and the critical speed increment; or, when the first outlet flue gas temperature increases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment. The optimal speed is determined according to the change of flue gas temperature at the air preheater outlet, which greatly improves the heat exchange capacity of the air preheater. The exhaust gas temperature is reduced, the heat loss of boiler exhaust gas is reduced, and the boiler efficiency is increased. The heat exchange capacity of the air preheater is improved, the temperature of the hot primary air and secondary air is increased, and the ignition performance and combustion performance of the boiler are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic flow chart of an online method for optimizing the rotation speed of a rotary air preheater according to an embodiment of the present invention is shown;

[0030] Figure 2 A schematic structural diagram of an online rotating speed optimization device for a rotary air preheater according to an embodiment of the present invention is shown;

[0031] Figure 3 A diagram showing the analytical relationship between the outlet flue gas temperature and the air preheater speed in another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] The present application embodiment provides a method for online optimizing the rotation speed of a rotary air preheater, which is applied to a rotary air preheater, such as Figure 1 As shown, the method comprises the following steps:

[0034] Step S101, when the load of the generator set is at a fixed value, a speed increment is added to the initial speed of the rotary air preheater, and the speed increment is adjusted according to the first change in the outlet flue gas temperature;

[0035] Step S102, in the process of adjusting the rotation speed increment, adjusting the rotation speed of the rotary air preheater based on the second change in the outlet flue gas temperature.

[0036] In step S101, when the load of the generator set is at a fixed value, a speed increment is added to the initial speed of the rotary air preheater, and the speed increment is adjusted according to the first change in the outlet flue gas temperature.

[0037] In this embodiment, the premise of the present application scheme is that the power generation boiler unit remains unchanged under a certain load, and a speed increment ε is added to the given air preheater initial speed n0. n , that is, the air preheater speed is now n = n0 + ε n After the speed increases, the speed increment is adjusted according to the change in the first outlet flue gas temperature. n It is determined according to the air preheater speed adjustment accuracy.

[0038] In order to ensure the reliability of air preheater speed optimization, in some embodiments of the present application, the speed increment is adjusted according to the change of the first outlet flue gas temperature, specifically: if the first outlet flue gas temperature decreases, the initial speed is increased by the speed increment, and the speed increment is increased; if the first outlet flue gas temperature increases, the initial speed is subtracted from the speed increment, and the speed increment is increased.

[0039] In this embodiment, when the air preheater speed increases to n = n0 + ε n , detect the change of flue gas temperature at the air preheater outlet (either increase or decrease). When the flue gas temperature at the air preheater outlet decreases, it indicates that the increase in speed has caused the flue gas temperature at the air preheater outlet to decrease. At this time, it is necessary to continue to increase the speed increment ε n , so that the outlet flue gas temperature continues to decrease. When the outlet flue gas temperature of the air preheater increases, it indicates that the increase in speed has increased the outlet flue gas temperature of the air preheater. At this time, the air preheater speed needs to be reduced, n = n0-ε n , increase the speed increment, thereby reducing the air preheater speed n to reduce the outlet flue gas temperature.

[0040] It can be understood that the technical effect ultimately achieved by the present application is reflected in reducing the flue gas temperature at the air preheater outlet, thereby improving the heat exchange capacity of the air preheater.

[0041] In step S102, in the process of adjusting the rotation speed increment, the rotation speed of the rotary air preheater is adjusted based on the second change in the outlet flue gas temperature.

[0042] In this embodiment, the initial speed increases or decreases the speed increment, and when increasing the speed increment ε n During the process, detect whether the flue gas temperature at the air preheater outlet changes, and adjust the air preheater speed according to the change of the flue gas temperature at the air preheater outlet, that is, to obtain the optimal critical speed increment ε n , thus obtaining the optimal air preheater speed n = n + ε n Or n=n-ε n .

[0043] In order to ensure the reliability of air preheater speed optimization, in some embodiments of the present application, when the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is the critical speed increment, and the speed of the rotary air preheater is adjusted to the sum of the initial speed and the critical speed increment; or, when the first outlet flue gas temperature increases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is the critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment.

[0044] In this embodiment, when the outlet flue gas temperature decreases for the first time, the air preheater speed is adjusted to the initial speed and the speed increment is n=n0+ε n , increase the speed increment ε n Until the outlet flue gas temperature rises, the speed increment ε corresponding to the moment when the outlet flue gas temperature rises is n is the critical speed increment, indicating that the speed increment ε at this time n Optimal, adjust the speed to the optimal air preheater speed n = n0 + ε n (Critical speed increment). Alternatively, when the outlet flue gas temperature rises for the first time, adjust the air preheater speed to the initial speed minus the speed increment n = n0-ε n , increase the speed increment ε n Until the outlet flue gas temperature rises, it indicates that the speed increment ε at this time n Optimum, adjust the speed to the optimal air preheater speed n = n0-ε n (Critical speed increment).

[0045] By applying the above technical solution, the method includes: when the load of the generator set is at a fixed value, adding a speed increment to the initial speed of the rotary air preheater, and adjusting the speed increment according to the change of the first outlet flue gas temperature; in the process of adjusting the speed increment, adjusting the speed of the rotary air preheater based on the change of the second outlet flue gas temperature. The speed increment is obtained based on the accuracy of the speed adjustment. If the first outlet flue gas temperature decreases, the initial speed increases the speed increment and increases the speed increment; if the first outlet flue gas temperature increases, the initial speed is subtracted from the speed increment and increases the speed increment. When the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the sum of the initial speed and the critical speed increment; or, when the first outlet flue gas temperature increases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment. The optimal speed is determined according to the change of flue gas temperature at the air preheater outlet, which greatly improves the heat exchange capacity of the air preheater. The exhaust gas temperature is reduced, the heat loss of boiler exhaust gas is reduced, and the boiler efficiency is increased. The heat exchange capacity of the air preheater is improved, the temperature of the hot primary air and secondary air is increased, and the ignition performance and combustion performance of the boiler are improved.

[0046] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present invention can be implemented by hardware, or by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each implementation scenario of the present invention.

[0047] In order to further explain the technical idea of ​​the present invention, the technical solution of the present invention is now described in combination with specific application scenarios.

[0048] This application method includes the following situations:

[0049] (1) The rotary air preheater operates at a given speed n0 and a given speed increment ε n , that is, the running speed at this time is n = n0 + ε n If the flue gas temperature at the air preheater outlet decreases, the air preheater speed increment ε is further increased. n , until the outlet flue gas temperature rises, then the optimal air preheater speed is n=n0+ε n , where ε n It is the speed increment corresponding to the critical rise of outlet flue gas temperature.

[0050] (2) The rotary air preheater operates at a given speed n0 and a given speed increment ε n , that is, the running speed at this time is n = n0 + ε n If the flue gas temperature at the air preheater outlet increases, the air preheater speed increment ε n , that is, the running speed at this time is n = n0-ε n , the air preheater speed decreases until the outlet flue gas temperature rises. At this time, the optimal air preheater speed is n = n0-ε n , where ε n It is the speed increment corresponding to the critical rise of outlet flue gas temperature.

[0051] The premise of the rotary air preheater speed optimization in this application is to keep the unit unchanged under a certain load. If the load changes, the method of this application is also applicable. Step amount of air preheater speed adjustment (speed increment) ε n It is determined according to the accuracy of speed adjustment.

[0052] Theoretical analysis: Figure 3As shown in the figure, considering the two extreme cases of the air preheater speed of 0 and +∞ under a certain load, when the air preheater speed is 0r / min, the heat exchange performance of flue gas and cold air is the worst, and the outlet flue gas temperature is the highest, that is, T max When the air preheater speed is +∞, the air leakage of the rotary air preheater is infinitely enlarged, the outlet flue gas temperature tends to the mixed temperature of flue gas and cold air, and the heat exchange performance is moderate, that is, T m Based on this, theoretical analysis shows that there is an optimal air preheater speed that makes the flue gas temperature at the air preheater outlet the lowest, that is, T min , the corresponding speed is the optimal speed n opt .

[0053] The air preheater speed is affected by unit load, flue gas specific heat capacity, flue gas cooling air mass ratio and heat storage area ash coefficient.

[0054] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present invention can be implemented by hardware, or by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each implementation scenario of the present invention.

[0055] Correspondingly, the present application also provides an online device for optimizing the speed of a rotary air preheater, such as Figure 2 As shown, the device is applied to a rotary air preheater, and the device comprises:

[0056] The first adjustment module 201 is used to add a speed increment based on the initial speed of the rotary air preheater when the load of the generator set is at a fixed value, and adjust the speed increment according to the first change in the outlet flue gas temperature;

[0057] The second adjustment module 202 is used to adjust the speed of the rotary air preheater based on the second outlet flue gas temperature change during the process of adjusting the speed increment.

[0058] In some embodiments of the present application, the device further includes an acquisition module for:

[0059] The rotation speed increment is obtained based on the accuracy of the rotation speed adjustment.

[0060] In some embodiments of the present application, the first adjustment module 201 is specifically used to:

[0061] If the first outlet flue gas temperature decreases, the initial rotation speed increases by the rotation speed increment, and the rotation speed increment is increased;

[0062] If the first outlet flue gas temperature increases, the initial rotation speed is subtracted from the rotation speed increment and increased by the rotation speed increment.

[0063] In some embodiments of the present application, the second adjustment module 202 is specifically used to:

[0064] When the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to be the sum of the initial speed and the critical speed increment;

[0065] Or, when the outlet flue gas temperature rises for the first time, the speed increment is increased until the outlet flue gas temperature rises for the second time, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment.

[0066] Those skilled in the art will appreciate that the modules in the device in the implementation scenario can be distributed in the device in the implementation scenario according to the implementation scenario description, or can be changed accordingly and located in one or more devices different from the implementation scenario. The modules in the above implementation scenario can be combined into one module, or can be further split into multiple sub-modules.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for online optimization of rotary air preheater speed, characterized in that: Applied to a rotary air preheater, the method comprises: When the load of the generator set is at a fixed value, a speed increment is added to the initial speed of the rotary air preheater, and the speed increment is adjusted according to the change of the first outlet flue gas temperature; If the first outlet flue gas temperature decreases, the initial rotation speed increases by the rotation speed increment, and the rotation speed increment is increased; If the first outlet flue gas temperature increases, the initial speed is reduced by the speed increment and increased by the speed increment; In the process of adjusting the speed increment, adjusting the speed of the rotary air preheater based on the change in the second outlet flue gas temperature; When the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to be the sum of the initial speed and the critical speed increment; Or, when the outlet flue gas temperature rises for the first time, the speed increment is increased until the outlet flue gas temperature rises for the second time, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment.

2. The method according to claim 1, characterized in that The method further comprises: The rotation speed increment is obtained based on the accuracy of the rotation speed adjustment.

3. An online device for optimizing the rotation speed of a rotary air preheater, characterized in that: Applied to a rotary air preheater, the device comprises: The first adjustment module is used to add a speed increment based on the initial speed of the rotary air preheater when the load of the generator set is at a fixed value, and adjust the speed increment according to the first change in the outlet flue gas temperature; If the first outlet flue gas temperature decreases, the initial rotation speed increases by the rotation speed increment, and the rotation speed increment is increased; If the first outlet flue gas temperature increases, the initial speed is reduced by the speed increment and increased by the speed increment; A second adjustment module is used to adjust the speed of the rotary air preheater based on the second outlet flue gas temperature change during the process of adjusting the speed increment; When the first outlet flue gas temperature decreases, the speed increment is increased until the second outlet flue gas temperature increases, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to be the sum of the initial speed and the critical speed increment; Or, when the outlet flue gas temperature rises for the first time, the speed increment is increased until the outlet flue gas temperature rises for the second time, at which time the speed increment is a critical speed increment, and the speed of the rotary air preheater is adjusted to the difference between the initial speed and the critical speed increment.

4. The device according to claim 3, characterized in that The device also includes an acquisition module, which is used to: The rotation speed increment is obtained based on the accuracy of the rotation speed adjustment.

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