Ignition and temperature rise mode of copper anode slime roasting rotary kiln based on DCS (Distributed Control System)

Abstract

The invention discloses a DCS (Distributed Control System)-based ignition and temperature rise mode of a copper anode slime roasting rotary kiln, which specifically comprises the following steps of: setting initial control conditions, drawing a temperature rise curve according to a target temperature, a temperature rise period and a temperature rise gradient, and then starting ignition preparation. Before natural gas is introduced into the combustion chamber for combustion, rotary kiln operation and combustion-supporting air purging are carried out, after purging is carried out for a period of time, combustion-supporting air and natural gas are introduced for ignition at the same time, and meanwhile the ignition condition is judged through a monitor. And if ignition fails, under the condition of no abnormity, purging can be repeated, and natural gas is introduced for re-ignition. According to the method, the natural gas flow and the combustion-supporting air volume are automatically controlled by the DCS according to the drawn temperature rise curve. The system has the beneficial effects that multiple ignition conditions can be controlled at the same time, remote automatic ignition is achieved, the ignition condition is fed back in time, the natural gas flow is flexibly controlled, the combustion temperature is controlled, the ignition effect of the rotary kiln is guaranteed, and meanwhile production operation safety of the rotary kiln is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of pyrometallurgical rotary kiln, and specifically relates to an ignition and heating method of a copper anode mud roasting rotary kiln based on DCS. Background Art

[0002] Rotary kilns are widely used in various industrial production processes, playing a crucial role in mining, metallurgy, and even the cement industry. Rotary kilns are primarily used for drying and roasting materials in industrial production. To achieve the required temperatures for roasting and drying, the kiln often requires a large amount of thermal energy. Efficiently providing the energy required for roasting is crucial for improving industrial production efficiency and conserving energy.

[0003] The source of heat energy for rotary kilns primarily relies on fuel combustion. Three fuels are commonly used today: natural gas, coal, and diesel. Due to their form, coal and diesel combustion is incomplete, resulting in a low cost-effectiveness ratio. Furthermore, a large amount of harmful flue gas produced by incomplete combustion requires treatment, resulting in high costs. Natural gas, on the other hand, offers advantages over coal and diesel, such as higher calorific value and higher combustion efficiency. Efficiently using natural gas to provide heat energy for rotary kiln ignition and heating is a good way to save energy, reduce consumption, and protect the environment.

[0004] Among the current rotary kiln ignition methods, most focus on ignition mode and intelligent control direction. Efficient ignition methods are rare, and many challenges remain. To achieve efficient natural gas ignition, advanced electronic technology is required to precisely control natural gas flow, combustion time, and ignition timing, thereby avoiding the instability and uncertainty of manual operation. Furthermore, in addition to excellent electronic technology, a correct set of operating procedures and conditions is also necessary. Within operating conditions, particularly when plotting a heating curve, if the heating rate does not match that of the production equipment, serious consequences can even result in equipment explosion.

[0005] Currently, in the field of pyrometallurgy, a significant portion of intelligent rotary kiln control still relies on PID and PLC control methods. These methods still rely heavily on manual adjustment and generally only control a single parameter. Compared to DCS systems, they lack the ability to control multiple production parameters and an effective feedback mechanism to adjust production conditions. Rotary kilns used for anode mud roasting require stable roasting temperatures to prevent the roasted product from forming large lumps. Furthermore, because the roasting temperatures in each section of a rotary kiln used for copper anode mud roasting vary, a DCS system capable of simultaneously controlling multiple conditions and providing precise feedback is essential to ensure proper kiln ignition and temperature rise.

[0006] Based on the problems currently existing in natural gas ignition, how to find a correct set of process conditions and ignition temperature increase methods while adapting to the DCS system, maintaining a high ignition success rate, maximizing fuel utilization, saving production costs, and improving rotary kiln production efficiency should be an urgent problem to be solved by technical personnel in this field. Summary of the Invention

[0007] In response to the above problems, the present invention provides a DCS-based ignition and heating method for a copper anode mud roasting rotary kiln. This method does not require the use of fuels with low combustion efficiency such as coal and diesel, requires less manual on-site operation, and can greatly save manpower and fuel costs.

[0008] The technical solution adopted by the present invention is: a DCS-based ignition and heating method for a copper anode mud roasting rotary kiln. The ignition and heating method uses the DCS system as the control basis, sets the initial control conditions, and draws a heating curve based on the target temperature, heating cycle, and heating gradient, and then starts ignition preparation. Before natural gas is introduced into the combustion chamber for combustion, the rotary kiln is first operated and the combustion-supporting air is purged. After a period of purging, the combustion-supporting air and natural gas are introduced at the same time for ignition, and the ignition status is judged by a monitor. If the ignition fails, if there is no abnormality, the purging can be repeated and natural gas can be introduced for re-ignition. In the present invention, the natural gas flow rate and the combustion-supporting air volume are automatically controlled by the DCS system according to the equipment operation status.

[0009] Furthermore, the method comprises the following steps:

[0010] Set the initial control conditions of the rotary kiln, draw a heating curve based on the target temperature, heating cycle and heating gradient, and then start ignition preparation;

[0011] Before natural gas is introduced into the combustion chamber for combustion, the rotary kiln is first operated and combustion-supporting air is purged. After a certain period of purging, a certain flow of combustion-supporting air and natural gas are introduced for ignition.

[0012] The flame signal of the combustion chamber after ignition is collected in real time, and the success of ignition is judged based on the flame signal. The purging is repeated and natural gas is introduced to re-ignite. If successful, the remaining combustion chambers are ignited at once and the heating rate is confirmed.

[0013] Furthermore, the rotary kiln is divided into four combustion chambers, corresponding to a natural gas main pipe, four natural gas branch pipes and a combustion-supporting air branch pipe. The target temperature range is set at 600-700°C, and the heating cycle is 3-4 days.

[0014] Furthermore, in the obtained heating curve, the heating gradient is the difference between the target temperature and the initial temperature divided by the heating period, and the specific value is 10-15°C / h.

[0015] Furthermore, the natural gas pressure regulating valve is adjusted to a total natural gas pressure of 10-20 kPa in the rotary kiln, and the total flow rate of the combustion-supporting air into the rotary kiln is 150-300 Nm 3 / h, the combustion air flow rate into each combustion chamber is 50-150Nm 3 / h, purge time is 400-1000s.

[0016] Furthermore, the combustion-supporting air is high-oxygen air with an oxygen concentration of 65%-80%, and the mixing ratio of the combustion-supporting air to natural gas is 10-11:1.

[0017] Furthermore, the total flow rate of natural gas in the rotary kiln is 30-50 Nm 3 / h, the natural gas flow rate into each combustion chamber is 5-20Nm 3 / h.

[0018] Furthermore, the condition for judging whether the ignition is successful is: if a flame appears in the combustion chamber and remains constantly lit, the ignition is successful; if the flame does not appear or disappears after appearing, the ignition fails.

[0019] Furthermore, the ignition success rate in the ignition and heating method can reach 95%.

[0020] Compared with the prior art, the advantages and positive effects of the present invention are:

[0021] (1) Using natural gas as the ignition and heating fuel for the rotary kiln ensures high combustion efficiency while saving production costs and reducing environmental pollution.

[0022] (2) Based on the DCS intelligent control system, the present invention can remotely control the opening of gas valves and simultaneously control multiple production conditions. It has a good feedback mechanism, can monitor temperature and ignition conditions, saves labor costs, and is simple and easy to operate. It is more intelligent than separate PID and PLC systems.

[0023] (3) The present invention adopts an ignition scheme of combustion-supporting air purge and natural gas and combustion-supporting air mixed ignition, which can quantify each ignition step with data. Compared with other ignition schemes, it does not rely too much on experience, and has high ignition efficiency and fuel utilization rate.

[0024] (4) The method of drawing the heating curve adopted in this paper quantitatively considers the factors of the equipment, changes the previous heating method that is completely based on experience, and combines the DCS system to stabilize the temperature control, thereby extending the service life of the rotary kiln and reducing the failure rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of the ignition and heating method of a DCS-based copper anode mud roasting rotary kiln of the present invention. DETAILED DESCRIPTION

[0026] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0029] like Figure 1 As shown, the ignition and heating method of the copper anode mud roasting rotary kiln based on DCS of the present invention is as follows: with the DCS system as the control basis, the initial control conditions are set and the heating curve is drawn according to the target temperature, heating cycle, and heating gradient, and then the ignition preparation is started. Before the natural gas is introduced into the combustion chamber for combustion, the rotary kiln is first operated and the combustion-supporting air is purged. After a period of purging, the combustion-supporting air and natural gas are introduced at the same time for ignition, and the ignition status is judged by a monitor at the same time. If the ignition fails, the purging can be repeated and the natural gas can be introduced for re-ignition if there is no abnormality. In the present invention, the natural gas flow rate and the combustion-supporting air volume are automatically controlled by the DCS system.

[0030] Furthermore, the method comprises the following steps:

[0031] S1) Drawing a heating curve: Drawing a heating curve according to the target temperature, heating cycle, and heating gradient, and setting the target temperature, heating cycle, and heating gradient on the DCS system.

[0032] S2) Operate the rotary kiln and purge with combustion-supporting air: Operate the rotary kiln at a certain speed, then fully open the rotary kiln natural gas main valve and the natural gas sub-valve of the combustion chamber to be ignited, adjust the natural gas pressure regulating valve to the appropriate position, start the DCS system, and then the DCS system will introduce combustion-supporting air to the corresponding combustion chamber at a certain flow rate for a period of time.

[0033] S3) Ignition: After the combustion air is purged, the DCS automatically opens the natural gas inlet electronic valve for the corresponding combustion chamber, introducing a mixture of combustion air and natural gas in a specified ratio. Ignition is initiated using the burner, and the flame signal is detected by the monitor to determine the ignition status. Once ignition is successful, the ignition operation is repeated for each combustion chamber in turn.

[0034] S4) Heating: Heating is performed according to the drawn heating curve.

[0035] The rotary kiln in S1) is divided into four combustion chambers, corresponding to a natural gas main, four natural gas branch pipes, and a combustion air branch pipe. The target temperature range is set at 600-700°C, and the heating cycle is 3-4 days. In the resulting heating curve, the heating gradient is the difference between the target temperature and the initial temperature divided by the heating cycle, specifically 10-15°C / h.

[0036] In said S2), under the constraint of the temperature rise curve drawn in S1), the natural gas pressure regulating valve is controlled by the DCS system to adjust the total natural gas pressure of the rotary kiln to 10-20kPa, and the total flow rate of the combustion-supporting air into the rotary kiln is 150-300Nm 3 / h, the combustion air flow rate into each combustion chamber is 50-150Nm 3 / h, the purge time is 400-1000s. During the purge, if the combustion air velocity and natural gas pressure deviate from the above range, the flow meter and pressure gauge will feedback the signal to the DCS system, thereby controlling the combustion air velocity and natural gas pressure to the set range.

[0037] The combustion-supporting air component in S2) is high-purity high-oxygen air with an oxygen concentration of 65%-80%, and the mixing ratio of the combustion-supporting air to natural gas is 10-11:1.

[0038] In said S3), under the constraint of the heating curve drawn in S1), the total flow rate of natural gas in the rotary kiln is controlled by the DCS system to be 30-50Nm 3 / h, the natural gas flow rate into each combustion chamber is 5-20Nm 3 / h. If the natural gas flow rate deviates from the above range during ignition, the flow meter will feed back a signal to the DCS system, thereby controlling the natural gas flow rate to the set range.

[0039] The ignition status is determined in S3) by the flame signal. During ignition, the monitor detects the flame condition in the combustion chamber and feeds back the flame signal to the DCS. If a flame appears in the combustion chamber and remains lit, the ignition is successful. If the flame does not appear or disappears after appearing, the ignition fails. It is necessary to troubleshoot the problem and ignite again according to the methods in S1), S2), and S3).

[0040] In said S4), when ignition is successfully completed, the DCS system can automatically perform control according to the set target temperature, heating cycle, and heating gradient. Specifically, when the actual parameter value deviates from the set parameter value, the on-site measurement equipment will feed back to the DCS system, and the DCS system will perform remote control.

[0041] In the method, the natural gas ignition success rate can reach 95%, the theoretical and actual temperature rise curves are consistent, and the failure rate during the temperature rise process is low.

[0042] Example 1:

[0043] The rotary kiln is set to run at a speed of 78 seconds / rev. The target temperature of the four-stage combustion chamber is set at 600-700℃ according to production needs. The heating cycle is 3 days. After setting, a heating curve is drawn. The heating curve shows a heating gradient of 14℃ / h. Then the natural gas valve is opened. Under the constraints of the heating curve, the DCS system adjusts the pressure regulating valve to the natural gas pressure of the rotary kiln to 16kPa and 220Nm 3 / h to introduce combustion-supporting air into the rotary kiln at a rate of 58Nm 3 / h to the first section of the natural gas combustion chamber, the combustion air purge time is set to 400s, after the purge is completed, the first section of the natural gas electronic valve automatically opens, the total flow of natural gas is set to 33Nm 3 / h, the natural gas flow rate in the first combustion chamber is 8Nm 3 / h, and the ignition situation was monitored by a monitor. The first combustion chamber was successfully ignited, and then the remaining three combustion chambers were ignited in turn. Finally, all four combustion chambers of the rotary kiln were successfully ignited. The actual temperature rise gradient during heating was 14.6℃ / h.

[0044] Example 2:

[0045] The rotary kiln is set to run at a speed of 78 seconds / rev. The target temperature of the four-stage combustion chamber is set at 600-700℃ according to production needs. The heating cycle is 3 days. After setting, a heating curve is drawn. The heating curve shows a heating gradient of 14℃ / h. Then the natural gas valve is opened. Under the constraints of the heating curve, the DCS system adjusts the pressure regulating valve to the natural gas pressure of the rotary kiln to 14kPa and 250Nm 3 / h to introduce combustion-supporting air into the rotary kiln at a rate of 70Nm 3 / h to the first section of the natural gas combustion chamber, the combustion air purge time is set to 400s, after the purge is completed, the first section of the natural gas electronic valve automatically opens, the total flow rate of natural gas is set to 31Nm 3 / h, the natural gas flow rate in the first combustion chamber is 7Nm 3 / h, the ignition status was monitored by a monitor. The first combustion chamber was successfully ignited, and then the remaining three combustion chambers were ignited in turn. Finally, all four combustion chambers of the rotary kiln were successfully ignited. The actual temperature rise gradient during heating was 14.8℃ / h

[0046] Example 3:

[0047] The rotary kiln is set to run at a speed of 78 seconds / rev. The target temperature of the four-stage combustion chamber is set at 600-700℃ according to production needs. The heating cycle is 3 days. After setting, a heating curve is drawn. The heating curve shows a heating gradient of 14℃ / h. Then the natural gas valve is opened. Under the constraints of the heating curve, the DCS system adjusts the pressure regulating valve to the natural gas pressure of the rotary kiln to 13kPa and 200Nm 3 / h to introduce combustion-supporting air into the rotary kiln at a rate of 55Nm 3 / h to the first section of the natural gas combustion chamber, the combustion air purge time is set to 400s, after the purge is completed, the first section of the natural gas electronic valve automatically opens, the total flow rate of natural gas is set to 30Nm 3 / h, the natural gas flow rate in the first combustion chamber is 6Nm 3 / h, the ignition status was monitored by a monitor. The first combustion chamber was successfully ignited, and then the remaining three combustion chambers were ignited in turn. Finally, all four combustion chambers of the rotary kiln were successfully ignited. The actual temperature rise gradient during heating was 14.2℃ / h

[0048] Example 4:

[0049] The rotary kiln is set to run at a speed of 78 seconds / rev. The target temperature of the four-stage combustion chamber is set at 600-700℃ according to production needs. The heating cycle is 3 days. After setting, a heating curve is drawn. The heating curve shows a heating gradient of 14℃ / h. Then the natural gas valve is opened. Under the constraints of the heating curve, the DCS system adjusts the pressure regulating valve to the natural gas pressure of the rotary kiln to 15kPa and 230Nm 3 / h to introduce combustion-supporting air into the rotary kiln at a rate of 63Nm 3 / h to the first section of the natural gas combustion chamber, the combustion air purge time is set to 400s, after the purge is completed, the first section of the natural gas electronic valve automatically opens, the total flow of natural gas is set to 34Nm 3 / h, the natural gas flow rate in the first combustion chamber is 7Nm 3 / h, the ignition status was monitored by a monitor. The first combustion chamber was successfully ignited, and then the remaining three combustion chambers were ignited in turn. Finally, all four combustion chambers of the rotary kiln were successfully ignited. The actual temperature rise gradient during heating was 13.6℃ / h

[0050] Example 5:

[0051] The rotary kiln is set to run at a speed of 78 seconds / rev. The target temperature of the four-stage combustion chamber is set at 600-700℃ according to production needs. The heating cycle is 3 days. After setting, a heating curve is drawn. The heating curve shows a heating gradient of 14℃ / h. Then the natural gas valve is opened. Under the constraints of the heating curve, the DCS system adjusts the pressure regulating valve to the natural gas pressure of the rotary kiln to 16kPa and 240Nm 3 / h to introduce combustion-supporting air into the rotary kiln at a rate of 69Nm 3 / h to the first section of the natural gas combustion chamber, the combustion air purge time is set to 400s, after the purge is completed, the first section of the natural gas electronic valve automatically opens, the total flow of natural gas is set to 38Nm 3 / h, the natural gas flow rate in the first combustion chamber is 7Nm 3The temperature of the kiln is monitored by the monitor, and the first combustion chamber is successfully ignited. Then the remaining three combustion chambers are sequentially ignited, and finally the fourth combustion chamber of the rotary kiln is successfully ignited. The actual temperature gradient during the heating process is 14.7°C / h.

[0052] The above describes in detail the ignition and heating method of the copper anode slime roasting rotary kiln based on DCS. The above description of the embodiments is only used to help understand the method and its core idea. For those skilled in the art, the specific implementation and application range will be changed according to the idea of the present application. Therefore, the content of the specification should not be understood as a limitation of the present application.

[0053] As some terms are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different names to refer to the same component. The specification and claims of this application do not distinguish components by name, but by the functional difference of the components. As mentioned throughout the specification and claims, "including" and "including" are open-ended terms, which should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problems within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, which is intended to illustrate the general principles of the present application, but not to limit the scope of the present application. The scope of protection of the present application is defined by the appended claims.

[0054] It should also be noted that the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the goods or systems including a series of elements not only include those elements, but also include other elements not explicitly listed, or include elements inherent to such goods or systems. Without more limitations, the element defined by the sentence "including a" does not exclude the existence of other identical elements in the goods or systems including the element.

[0055] It should be understood that the term "and / or" used herein is only a description of the association relationship between the associated objects, which means that there are three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents a "or" relationship between the front and rear associated objects.

[0056] The above description shows and describes several preferred embodiments of the present application. However, as previously mentioned, it should be understood that the present application is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present application can be used in various other combinations, modifications, and environments and can be modified within the scope of the application concept described herein through the above teachings or technology or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present application should be protected by the claims appended hereto.

Claims

1. A DCS-based ignition and heating method for a copper anode mud roasting rotary kiln, characterized in that: The ignition heating method specifically includes the following steps: Set the initial control conditions of the rotary kiln, draw a heating curve based on the target temperature, heating cycle and heating gradient, and then start ignition preparation; Before natural gas is introduced into the combustion chamber for combustion, the rotary kiln is first operated and combustion-supporting air is purged. After a certain period of purging, a certain flow of combustion-supporting air and natural gas are introduced for ignition. The flame signal of the combustion chamber after ignition is collected in real time, and the success of ignition is judged based on the flame signal. The purging is repeated and natural gas is introduced to re-ignite. If successful, the remaining combustion chambers are ignited at once and the heating rate is confirmed.

2. The ignition heating method according to claim 1, characterized in that: The rotary kiln is divided into four combustion chambers, corresponding to a natural gas main pipe, four natural gas branch pipes and a combustion air branch pipe. The target temperature range is set at 600-700°C, and the heating cycle is 3-4 days.

3. The ignition heating method according to claim 1, characterized in that: In the obtained heating curve, the heating gradient is the difference between the target temperature and the initial temperature divided by the heating period, and the specific value is 10-15°C / h.

4. The ignition heating method according to claim 2, characterized in that: The natural gas pressure regulating valve is adjusted to a total natural gas pressure of 10-20kPa for the rotary kiln, and the total flow rate of the combustion-supporting air into the rotary kiln is 150-300Nm 3 / h, the combustion air flow rate into each combustion chamber is 50-150Nm 3 / h, purge time is 400-1000s.

5. The ignition heating method according to claim 1, characterized in that: The combustion-supporting air is high-oxygen air with an oxygen concentration of 65%-80%, and the mixing ratio of the combustion-supporting air to natural gas is 10-11:

1.

6. The ignition heating method according to claim 2, characterized in that: The total natural gas flow rate of the rotary kiln is 30-50Nm 3 / h, the natural gas flow rate into each combustion chamber is 5-20Nm 3 / h.

7. The ignition heating method according to claim 1, characterized in that: The condition for judging whether the ignition is successful is: if a flame appears in the combustion chamber and remains constantly lit, the ignition is successful; if the flame does not appear or disappears after appearing, the ignition fails.

8. The ignition heating method according to claim 1, characterized in that: The ignition success rate in the ignition and heating method can reach 95%.

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