Management process for an open anode furnace

Abstract

A device and method for measuring the operating condition of an open anode furnace, includes at least one sensor for measuring the temperature and/or determining the fuel quantity or the burner capacity of the burners allocated to the anode furnace, or for determining the opacity of the air, and for the independent and automatic control of the process management of the anode furnace. This is achieved by at least one measuring device for measuring the throughput of air flowing through the anode furnace provided in an air duct of the anode furnace through which air flows. The measured values are evaluated by an electronic control unit, and the electronic control unit sets the operating condition of the anode furnace according to the particular measured values.

Description

The present invention relates to a management process for an open anode furnace in accordance with the pre-characterizing part of Clause 1 as well as to a device for measuring the operating status of an open anode furnace and for managing its process in accordance with the pre-characterizing part of Clause 5.

To date, an open or covered anode furnace has been operated in such a way that the specialist personnel operating the anode furnace have to rely on many years of professional experience to enable the workers to control the anode furnace. This means that the specialist personnel responsible for operation regulate the burner power, for example, in order to increase or reduce the temperature in the burner zones. The temperature is measured at various points in the anode furnace for this purpose.

However, an anode furnace control method of this type has the disadvantage that the specialist personnel are often unable to achieve the optimum operating setting of the anode furnace because information is lacking. This is because the parameters that are decisive in terms of optimum energy utilization can only be inadequately assessed and estimated by the specialists. For example, it is conceivable that an obstacle could occur within the air duct that could under certain circumstances cause a local reduction in the volume of air passing through this area of the anode furnace, leading to a rise in temperature whereas there may be a drop in temperature at another point. Even increasing the burner power has no effect in the event of a reduction in the throughput of air in the area of the burner, because the lower amount of heating air available does not transport the additionally input burner energy to the anodes immediately with the effect that the burner energy is applied to the walls of the anode furnace. This, however, leads to significant damage to the anode furnace because the walls of the anode furnace are not designed to withstand such an elevated level of heat stress.

Furthermore, it is disadvantageous that the personnel operating the anode furnace cannot reliably estimate at what moment a section of the anode furnace has become unusable and therefore must be renewed. Instead, such decisions have in the past been based on statistical observations and values drawn from experience, which in some cases has led to a section being renewed too soon or even too late. This causes unnecessary operating costs because the energy consumption increases.

Furthermore, it is highly costly to operate a faulty section or a section which is not being used optimally in terms of energy because the anode furnace requires additional energy in order to burn the anodes it contains.

To date, no device for automatic control of an anode furnace has been disclosed.

It is therefore the task of the present invention to provide a management process for an anode furnace of the aforementioned type, by means of which the anode furnace can be operated automatically over a relatively long period. This process is intended to provide measuring parameters by means of which an electronic control unit automatically undertakes the process management of the anode furnace. Also, the service life of the anode furnace should be extended because the process management remains within an optimum energy band. Furthermore, it is the task of the present invention to provide a device by means of which the process management of the anode furnace can be undertaken.

The task in accordance with the present invention for managing the process of the anode furnace is accomplished by the features of the characterizing parts of patent claims 1 and 5, and the task for automatic process management of the anode furnace is accomplished by the device in accordance with the characterizing part of patent claim 6.

Further advantageous embodiments of the invention are apparent from the subordinate claims.

By means of the device and process in accordance with the present invention, it is possible to measure a heating duct index that is permanently adjusted to the actual operating situation in the anode furnace. In this case, an electronic control unit allocated to the device evaluates the measurement results and compares these with a predefined or mathematically calculated actual operating condition, and adapts the actual operating status to the optimum actual value of the anode furnace. This provides an advantageous way of obviating the need for specialist personnel in order to monitor and conduct the process management of the anode furnace. Rather, the process management of the anode furnace can be based on precisely predefined values so as to make it possible to operate the anode furnace with optimum use of energy.

Also, the relevant parameters are determined in each section of the anode furnace so that it is possible to verify clearly in which section which actions have to be taken.

For example, the electronic control unit increases or reduces the air throughput through the anode furnace in accordance with the volume of air actually needed in the individual zones. If necessary, it is also possible to increase or reduce the quantity of fuel in order to control the output of the burners so as to achieve the optimum energetic temperature required for combustion of the anodes.

Consequently, the process management of the anode furnace takes place fully automatically and requires only minor manual checks, for example to see whether the measuring instruments used are in need of repair and that they are delivering correct measurement values. As a result, a fully automatic furnace process management of this kind only requires a small number of personnel which allows considerable personnel cost savings. In addition, process management is adapted to achieve an optimum energy profile and therefore the energy consumption can be reduced to the magnitude required for optimum operation of the anode furnace.

The drawing shows a sample embodiment configured in accordance with the present invention, the details of which are explained below. In the drawing,

FIG. 1 shows an anode furnace consisting of three fires divided into three zones, within which a plurality of anodes are placed, with a schematic process management diagram for managing the process of the anode furnace, as a plan view,

FIG. 2 shows the anode furnace in accordance with FIG. 1, as a side view, together with a temperature/time curve configured for the process management of the anode furnace,

FIG. 3 shows two adjacent sections of the anode furnace in accordance with FIG. 1, as a magnified plan view, and

FIG. 4 shows a cut-out of the anode furnace in accordance with FIG. 1 and its sections, to which certain actual operation conditions are allocated.

FIGS. 1 to 4 show an anode furnace 2 to which a device 1 for process management is allocated. The device 1 is intended to allow the anode furnace 2 to be controlled automatically without the need for extensive monitoring activity by the operating personnel.

The anode furnace 2 shown in FIG. 1 consists of three individual fires with an identical structure. The structure and the mode of function of the anode furnace 2 is explained in more detail using the first fire. Each fire can be divided into three zones 3, 4 and 5 within which different operating conditions obtain. A plurality of anodes 7 that are to be burned are placed in one section 6 each in zone 3. In zone 4, the positioned anodes 7 should be burned by three burners 10 and the burned anodes should cool 7 in zone 5.

This means it is necessary for air to be channeled through the anode furnace 2 and through the three zones 3, 4 and 5. An air duct 9 is provided in the anode furnace 2 for this purpose and it connects the individual sections 6 and therefore also the zones 3, 4 and 5 with one another. Furthermore, one damper flap 13 each is provided at the output and input of the air duct 9 in order to allow the quantity of air sucked into the air duct 9 to be controlled. A ventilator 14 is allocated to zone 3 and to the air duct 9 emerging there, by means of which the air is drawn through zones 3, 4 and 5 so that negative pressure exists in the anode furnace 2. Consequently, air enters zone 5 of the anode furnace 2 with the normal room temperature of the surrounding area and cools down the heated anodes 7. Nevertheless, there is a heat exchange between the anodes 7 and the sucked-in air, with the result that the air flowing into zone 4 is heated up. The three burners 10 further heat the air in zone 4, so that the anodes 7 placed there are exposed to the operating temperature required for combustion.

The air flowing onwards into zone 3 therefore has a further elevated temperature, resulting in the anodes 7 placed in zone 3 being preheated.

Once the anodes in zone 4 have been burned up, the burners 10 are moved and transferred to zone 3 in order to burn the anodes 7 placed there. In this way, the anode furnace in its entirety represents a closed control loop in which the following procedures occur in a recurring sequence: the three fires burn the positioned anodes 7, the anodes 7 cool down and the anodes 7 are preheated; in a further three zones, meanwhile, the anodes 7 can be placed for burning or the burned anodes 7 can be removed from the anode furnace 2.

In order for the furnace management process to be performed automatically, an electronic control unit 12 is allocated to each individual fire in the anode furnace 2. Furthermore, each of the sections 6 that form zones 3, 4 and 5 contains temperature sensors 16, sensors 17 for measuring the air throughput and sensors 20 for measuring the opacity of the air, by which is meant the obtaining soot particle concentration in the air. Temperature sensors 16 and sensors 17 and 20 record measurement values for each of the sections 6 and pass these on to the electronic control unit 12.

The values measured in this way are used by the electronic control unit 12 for creating a heating duct index that is made up of the measured temperature and/or the measured volumetric flow of air and/or the quantity of fuel supplied and the combustion capacity of the burners 10 and/or the opacity of the fire generated by the burners 10 and/or the level of negative pressure obtaining in the zone 3, 4, 5 and/or the resulting temperature gradient of the fire generated by the burners 10. This heating duct index is now compared with an actual operating value of the anode furnace 2 that has an optimum energy level. The electronic control unit 12 makes appropriate adjustments in case there are discrepancies. Following this, the heating duct index is once more compared with the actual operating value.

The heating duct index is adjusted to the actual operating value by the damper flap 13 at the entrance to the air duct 9 being opened or closed further, for example, with the effect that either more or less air enters the anode furnace 2. If necessary, the burner power of the burners 10 can also be adjusted by reducing or increasing the quantity of fuel. Controlling the ventilator 14 is also another way of increasing or reducing the air throughput. There are also individual dampers 13 in the inside of the anode furnace 2 inside the air duct 9, which means that, in principle, each section 6 can be individually supplied with air.

FIG. 4 in particular shows that the individual sections 6 are monitored with the effect that it is possible to measure precisely which of the sections 6 are running with optimum energy utilization, or which of the sections 6 may be damaged as a result of the permanent stress caused by fluctuations in temperature and will have to be renewed. These sections 6 are shown as a black field in FIG. 4, which means the operating personnel can easily find out which of the sections 6 will have to be completely renewed in the next cooling-down phase in order to achieve an optimum use of energy during operation.

Claims

1. A management process for an open anode furnace (2) comprising a plurality of zones (3, 4, 5) connected together by an air duct (9), these zones (3, 4, 5) being composed of several sections (6) in which anodes (7) to be combusted are placed and within which, to at least a partial extent, different operating conditions obtain, in which one or more of the zones (3, 4, 5) have one or more burners (10) therein by means of which the corresponding zone (3, 4, 5) and air flowing through the zone is heated, and in which the air can be supplied through the air duct (9) into the individual zones (3, 4, 5) by means of negative pressure,

characterized by the following steps:

creating a heating duct index for each of the one or more zones (3, 4, 5) the index being made up of at least one of measured temperature, measured volumetric flow of air, the quantity of fuel supplied, the combustion capacity of the burners (10), the opacity of a fire generated by the burners (10), the level of negative pressure obtaining in the zone (3, 4, 5), and the resulting temperature gradient of the fire generated by the burners (10); and

making a comparison between the heating duct index and an actual operating value for the anode furnace (2), and undertaking a selected one of

(1) changing the throughput volume of air flow, and setting at least one of the quantity of fuel supplied and the combustion capacity of the burners (10), depending on a difference between the heating duct index and the actual operating value of the anode furnace (2), and

(2) exchanging at least one or more of the sections (6) forming the zones (3, 4, 5) as soon as a tolerance limit between the heating duct index and the actual operating value is exceeded.

2. The process in accordance with claim 1,

characterized in that,

mathematical methods comprising one of linear multiple regression and statistical calculation, are used for creating the heating duct index.

3. The process in accordance with claim 1,

characterized in that,

the management of the anode furnace (2) is dynamically adapted by means of the heating duct index in accordance with the operating condition measured in the sections (6).

4. The process in accordance with claim 1,

characterized in that,

the volumetric flow of air is controlled by a damper flap (13) arranged in the air duct (9).

5. A process for identifying a condition of a heating duct in open and covered anode furnaces,

characterized in that,

the condition of all heating ducts is continuously identified by means of a “heating duct index” that is formed by calculating together available measurement values using mathematical methods comprising linear multiple regression, statistical calculation methods and fuzzy logic algorithms, the index being calculated from at least one of correlation of measurement data and position of exhaust damper flaps on an exhaust ramp, the correlation of measurement data and the measurement of opacity at a relevant fire in a furnace, the correlation of measurement data and the measurement of negative pressure at the relevant fire in the furnace, the correlation of measurement data and measurement of at least one of quantity of fuel supplied and burner combustion capacity at the relevant fire in the furnace, the correlation of measurement data and measurement of temperatures in heating ducts of the relevant fire, the correlation of measurement data and measurement of temperature gradient of the relevant fire in the heating ducts, the correlation of measurement data and measurement of the pressure ahead of the fire at the relevant fire in the furnace system, the correlation of measurement data and the measurement of at least one of cooling air volume and ventilator capacity of flap position at the relevant fire in the furnace system, and from an optical assessment using eyepieces disposed at the fire in the furnace.

6. A device for measuring operating conditions of an open anode furnace (2), the device comprising at least one sensor (16) for at least one of measuring temperature and determining at least one of the quantity of fuel supplied and the combustion capacity of the burners (10) disposed in the anode furnace (2), and determining opacity of fire generated by the burners,

characterized in that,

at least one measuring device (17) for measuring the throughput of air flowing through the anode furnace (2) is provided in an air duct (9) of the anode furnace (2) through which air flows, the measured values are evaluated by an electronic control unit (12), and the electronic control unit (12) is adapted to set the operating condition of the anode furnace (2) in accordance with the measured values.

7. The device in accordance with claim 6,

characterized in that,

at least one damper flap (13) is arranged in the air duct (9) of the anode furnace (2) and in that an opening angle of the damper flap (13) is adjusted by the electronic control unit (12).

8. The device in accordance with claim 7,

characterized in that,

each of the damper flaps (13) attached at a selected one of an input and output of the air duct (9).

9. The device in accordance with claim 6,

characterized in that,

at least one ventilator (14) is allocated to the air duct (9) of the anode furnace (2), and negative pressure generated by the ventilator (14) in the air duct (9) is adjusted by the electronic control unit (12).

10. The device in accordance with claim 6,

characterized in that,

the burner capacity of the individual burners (10) attached to the anode furnace (2) is controlled by the electronic control unit (12).