ID fan control method applied to 3500 t aluminum oxide suspension roaster

Abstract

The invention discloses an ID fan control method applied to a 3500t aluminum oxide suspension roaster, which adopts a control system consisting of a roasting DCS (Distributed Control System), an intelligent Venturi differential pressure module, an intelligent oxygen content control module, a Venturi differential pressure gauge, an oxygen content gauge, a data acquisition unit and a priority selection unit. The intelligent oxygen content control module and the intelligent venturi differential pressure control module are added on the basis of an original roasting DCS (Distributed Control System) to carry out multi-parameter model control, so that the problem that the oxygen content and the venturi differential pressure are both lost is solved, and ID fan multivariable simultaneous automatic frequency control is realized, so that the production stability of an aluminum oxide roasting furnace is improved, and the production cost is reduced. The quality of the final aluminum oxide product is improved, and the purposes of energy conservation and efficiency improvement are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of fan optimization, and in particular to an ID fan control method applied to a 3500t alumina suspension roasting furnace. Background Art

[0002] The Bayer process for producing alumina typically uses a gaseous suspension roaster. The main process is as follows: aluminum hydroxide undergoes a preheating treatment before entering the gaseous suspension roaster. Fuel combustion generates high-temperature flue gas, which causes the aluminum hydroxide to calcine in a suspended state. The roasting temperature is generally controlled between 950°C and 1100°C. Under this high temperature, the aluminum hydroxide decomposes, removing its water of crystallization, and producing the final, qualified alumina product.

[0003] In current gas suspension roasting furnace technology, a quantitative feeder is used to continuously add aluminum hydroxide raw material to the system. A regulating valve is used on the gas pipeline to control the amount of gas added, and instruments such as calorific value, flow rate, and pressure are used for precise metering. An induced draft fan creates negative pressure to maintain gas circulation within the roaster, while simultaneously removing waste gases such as carbon dioxide and water vapor. The operating frequency of the induced draft fan is controlled to regulate the oxygen content within the furnace, ensuring full contact between the material and the gas for the roasting reaction.

[0004] The relevant equipment and instruments described above have all been connected to a distributed control system. A common method for controlling the operating frequency of the ID fan is to design a control loop that links the ID fan's operating frequency to oxygen content, inputting a set oxygen content value into the DCS control system, and automatically adjusting the ID fan's operating frequency. Due to the numerous interference factors in the roasting production system, which are easily affected by upstream material characteristics (such as water content in the incoming material and aluminum hydroxide particle size), and the fact that traditional control methods only consider oxygen content as a single factor, this often results in insufficient wind power due to unilaterally lowering oxygen content to reduce ID fan operating costs. This increases the Venturi differential pressure, causing material blockage, which in turn leads to unstable furnace conditions and reduced finished product indicators. Furthermore, this results in increased fuel waste during the process of achieving stable furnace conditions. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides an ID fan control method applied to a 3500t alumina suspension roasting furnace, which can solve the problem of oxygen content control and Venturi differential pressure control being out of sync with each other in production, improve control accuracy, and enhance the overall production stability of the roasting furnace.

[0006] To achieve the above object, the present invention adopts the following technical solution: a method for controlling an ID fan in a 3500t alumina suspension roasting furnace, which adopts a control system consisting of a roasting DCS distributed control system, an intelligent Venturi pressure difference module, an intelligent oxygen content control module, a Venturi pressure difference meter, an oxygen content meter, a data acquisition unit, and a priority selection unit. The specific method includes the following steps:

[0007] S1, limiting the oxygen content setting range and the Venturi pressure difference setting range in the intelligent oxygen content control module and the intelligent Venturi pressure difference control module respectively;

[0008] S2: If the Venturi pressure difference does not exceed the set range, the priority selection unit selects the ID fan frequency value given by the intelligent oxygen content control module; if the Venturi pressure difference exceeds the set range, the priority selection unit selects the ID fan frequency value given by the intelligent Venturi differential pressure control module;

[0009] S3, the data acquisition unit transmits the given ID fan frequency value to the roasting DCS distributed control system, which is received by the ID fan control program in the roasting DCS distributed control system and acts on the ID fan.

[0010] Furthermore, the setting range of the oxygen content in S1 is 1.5% to 4%, and the setting range of the Venturi pressure difference is 0.8 kPa to 1.6 kPa.

[0011] Furthermore, in step S2, the intelligent oxygen content control module uses the real-time oxygen content fed back by the oxygen meter to adjust the ID fan frequency value upward or downward based on the positive linear correlation between the oxygen content and the ID fan frequency when the oxygen content does not meet or exceeds the set range.

[0012] Furthermore, in step S2, the intelligent Venturi differential pressure control module uses the real-time value of the Venturi pressure difference fed back by the Venturi differential pressure gauge to adjust the ID fan frequency value upward or downward based on the negative linear correlation between the Venturi pressure difference and the ID fan frequency when the Venturi pressure difference does not meet or exceeds its set range.

[0013] Furthermore, in step S2, the intelligent venturi differential pressure control module also receives the real-time value of the discharge amount to determine whether a material blockage occurs, and when the venturi pressure difference exceeds its set range, the discharge amount is reduced.

[0014] Compared with the prior art, the present invention has the following beneficial effects: the present invention adds an intelligent oxygen content control module and an intelligent Venturi pressure difference control module to the original roasting DCS distributed control system to perform multi-parameter model control, thereby solving the problem of neglecting one of the oxygen content and the Venturi pressure difference, and realizing multi-variable automatic frequency control of the ID fan at the same time, thereby improving the production stability of the alumina roasting furnace, improving the quality of the final alumina product, and achieving the goal of energy saving and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a control flow diagram of the present invention;

[0016] Figure 2 The characteristic curve diagram of the relationship between oxygen content and ID fan frequency of the present invention;

[0017] Figure 3 This is a characteristic curve diagram of the relationship between the Venturi pressure difference and the ID fan frequency of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0019] The following specific embodiments are used to describe the technical solution of the present invention in detail. The following specific embodiments can be combined or replaced with each other according to actual conditions, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0020] Example 1

[0021] like Figures 1 to 3 As shown, the present invention provides an ID fan control method applied to a 3500t alumina suspension roasting furnace, which adopts a control system composed of a roasting DCS distributed control system, an intelligent Venturi pressure difference module, an intelligent oxygen content control module, a Venturi pressure difference meter, an oxygen content meter, a data acquisition unit and a priority selection unit. The specific method includes the following steps:

[0022] S1, limiting the oxygen content setting range and the Venturi pressure difference setting range in the intelligent oxygen content control module and the intelligent Venturi pressure difference control module respectively;

[0023] S2: If the Venturi pressure difference does not exceed the set range, the priority selection unit selects the ID fan frequency value given by the intelligent oxygen content control module; if the Venturi pressure difference exceeds the set range, the priority selection unit selects the ID fan frequency value given by the intelligent Venturi differential pressure control module;

[0024] S3, the data acquisition unit transmits the given ID fan frequency value to the roasting DCS distributed control system, which is received by the ID fan control program in the roasting DCS distributed control system and acts on the ID fan.

[0025] By adding an intelligent oxygen content control module and an intelligent Venturi pressure differential control module to the roasting DCS distributed control system, multi-parameter model control is implemented to solve the problem of neglecting oxygen content and Venturi pressure differential, and to achieve multi-variable automatic frequency control of the ID fan, thereby improving the stability of alumina roasting furnace production, improving the quality of the final alumina product, and achieving the goal of energy saving and efficiency improvement. The purpose of using a priority selection unit is that the Venturi pressure differential usually occurs when it exceeds the specified upper limit and rarely falls below the specified lower limit. When the Venturi pressure differential increases abnormally, it indicates that the Venturi is blocked, resulting in obstruction of material transportation, which can easily cause increased equipment wear, uneven roasting, and increased impurity content. Therefore, the Venturi pressure differential control module has a higher priority than the oxygen content control module.

[0026] Specifically, the oxygen content in S1 is set within a range of 1.5% to 4%, and the Venturi pressure difference is set within a range of 0.8 kPa to 1.6 kPa. This oxygen content ensures that the fuel and oxygen are fully mixed and burned, releasing sufficient heat to meet roasting requirements. This Venturi pressure difference also ensures smooth powder transportation throughout the furnace.

[0027] Specifically, in step S2, the intelligent oxygen content control module uses the real-time oxygen content feedback from the oxygen meter to, when the oxygen content does not meet or exceeds its set range, adjust the ID fan frequency upward or downward based on the positive linear correlation between oxygen content and ID fan frequency. Based on the real-time oxygen content feedback and the positive linear correlation between oxygen content and ID fan frequency, a data model is established. Reasoning is performed based on the data model to determine a given output value for the ID fan operating frequency to ensure that the oxygen content falls within the set oxygen content range.

[0028] Specifically, in step S2, the intelligent Venturi differential pressure control module uses the real-time Venturi differential pressure value fed back by the Venturi differential pressure gauge to adjust the ID fan frequency upward or downward based on the negative linear correlation between the Venturi differential pressure and the ID fan frequency when the Venturi differential pressure does not meet or exceeds its set range. Based on the real-time Venturi differential pressure feedback, a data model is established based on the negative linear correlation between the Venturi differential pressure and the ID fan frequency. Inference is performed based on the data model to determine an output value given by the ID fan operating frequency to bring the Venturi differential pressure within the set Venturi differential pressure range.

[0029] Specifically, in step S2, the intelligent Venturi differential pressure control module also receives the real-time value of the feed rate to determine whether a blockage has occurred. When the Venturi differential pressure exceeds its set range, the feed rate is adjusted downward. The Venturi differential pressure is also related to the real-time value of the feed rate. Due to excessive water content in the incoming aluminum hydroxide, the powdered aluminum hydroxide agglomerates and becomes more viscous, which may cause a blockage. This causes an abnormal increase in the Venturi differential pressure, affecting production. Therefore, when adjusting the ID fan frequency value, it is also necessary to reduce the feed rate to stabilize the furnace condition as quickly as possible.

[0030] In addition to the above-mentioned preferred embodiments, the present invention has other implementation modes. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection requested by the present invention.

Claims

1. A method for controlling an ID fan in a 3500t alumina suspension roasting furnace, characterized in that: A control system consisting of a roasting DCS distributed control system, an intelligent Venturi pressure difference module, an intelligent oxygen content control module, a Venturi pressure difference meter, an oxygen content meter, a data acquisition unit, and a priority selection unit is adopted. The specific method includes the following steps: S1, limiting the oxygen content setting range and the Venturi pressure difference setting range in the intelligent oxygen content control module and the intelligent Venturi pressure difference control module respectively; S2: If the Venturi pressure difference does not exceed the set range, the priority selection unit selects the ID fan frequency value given by the intelligent oxygen content control module; if the Venturi pressure difference exceeds the set range, the priority selection unit selects the ID fan frequency value given by the intelligent Venturi differential pressure control module; S3, the data acquisition unit transmits the given ID fan frequency value to the roasting DCS distributed control system, which is received by the ID fan control program in the roasting DCS distributed control system and acts on the ID fan.

2. The ID fan control method applied to a 3500t alumina suspension roasting furnace according to claim 1 is characterized in that: The setting range of the oxygen content in S1 is 1.5% to 4%, and the setting range of the Venturi pressure difference is 0.8 kPa to 1.6 kPa.

3. The ID fan control method for a 3500t alumina suspension roasting furnace according to claim 1, characterized in that: In step S2, the intelligent oxygen content control module uses the real-time oxygen content fed back by the oxygen meter to adjust the ID fan frequency value upward or downward based on the positive linear correlation between oxygen content and ID fan frequency when the oxygen content does not meet or exceeds the set range.

4. The ID fan control method for a 3500t alumina suspension roasting furnace according to claim 1, characterized in that: In step S2, the intelligent Venturi differential pressure control module uses the real-time value of the Venturi differential pressure fed back by the Venturi differential pressure gauge to adjust the ID fan frequency value upward or downward based on the negative linear correlation between the Venturi differential pressure and the ID fan frequency when the Venturi differential pressure does not meet or exceeds the set range.

5. The ID fan control method for a 3500t alumina suspension roasting furnace according to claim 1, characterized in that: In step S2, the intelligent venturi differential pressure control module also receives the real-time value of the discharge amount to determine whether a material blockage occurs, and when the venturi pressure difference exceeds its set range, the discharge amount is reduced.

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