Management in technical systems
With the growth of aggregate productivity and increasing requirements for metal quality, the role of automatic control and management of metallurgical processes has grown, since subjective errors made by personnel can lead to significant absolute losses of fuel and metal or to a decrease in product quality.
The need for automation and algorithmic control of steelmaking processes is beyond doubt. On their basis, it becomes possible to conduct the process in optimal conditions. At the same time, along with improving working conditions, standardization of the process and the quality of products are more reliably ensured.
With the emergence and development of electric steel melting in arc furnaces, due to the relatively high cost of electricity, it became necessary to reduce its consumption by automatically maintaining a given electrical mode. To date, reliable electric mode regulators have been developed that allow you to maintain a given electric melting mode in accordance with the established directive schedule, which ensures the necessary course of metallurgical processes.
The development of automated control systems (ACS) was a higher step in the automation of metallurgical processes. Preliminary calculations show that the payback period of ACS is less than two years, which is significantly less than the payback period of the main metallurgical units.
The most effective means of controlling technological objects are centralized control systems created on the basis of control theory, using economic and mathematical methods, computational and control equipment. Such control systems are called automated process control systems (ACS TP). ACS TP includes a large area of ??process control systems with varying degrees of release of a person (operator) from control and management functions, and their transfer to automatic devices.
As a result of the use of automation, the productivity of units increases, the cost price decreases, the quality of the finished product increases, the labor of the workers becomes easier, and the general culture of production increases.
The existing automatic control systems for both individual shotcrete installations and the shotcrete process as a whole do not perform all the necessary functions for controlling and controlling the parameters of this control object, taking into account the relationship with ACS and ACS of other processes of an arc steel-smelting furnace. Therefore, the development of a system for automatic control of the process of shotcrete chipboard is relevant.
The purpose of this work is to increase the efficiency of the shotcrete process of an arc steel-smelting furnace by developing an automatic control system that will improve the quality of the shotcrete application, as well as reduce operating costs for the process of gunning the chipboard.
Achieving this goal is possible due to an in-depth analysis of the characteristics of this control object, development and implementation of the necessary control algorithms using modern element base - programmable logic controllers, sensors and actuators.
Analysis of existing solutions in the field of automation of the gunning process of arc steel-smelting furnaces was carried out on the basis of a review of literary sources and information that is presented on the Internet. As a result of the analysis of the automation of the process under consideration, the following features were established.
One of the most feasible ways to improve the quality of the wire is to develop a system for automating the process of powder wire production. This system will ensure the accuracy of backfilling a multicomponent charge into the intermediate ribbon profile of the wire and the tight packing of powder wire, which will greatly improve the quality of the product.
A sufficiently large number of works, projects and ready-made automation systems for the shotcrete process belong to other technological objects – oxygen converters, steel casting and intermediate ladles of continuous casting machines, etc. Despite the general industry of use – metallurgy, the gunning process of the listed objects (converters, buckets) differs both from each other and from the process of gunning the chipboard under consideration.
When automating the gunning process of an arc steel-smelting furnace, attention is often paid to the narrow problem that arose when creating an automatic control system for gunning a chipboard in a particular enterprise with certain technological equipment.
Existing automation systems for chipboard gunning process, as a rule, operate in automated control mode, and more often in remote / manual control mode [7], where the operator makes the main decisions on gunning process control. The majority of auxiliary operations, including the processes of supplying oxygen, water and air to the shotcrete above, are controlled by the operator manually / remotely based on the results of the control of technological parameters.
When automating the main and auxiliary technological processes in metallurgy, individual developments and projects of self-propelled guns, process control systems for a specific process in a specific metallurgical enterprise are used. As the analysis shows, in the existing self-propelled guns gunning of arc steel-smelting furnaces there are no standard, standard, unified automation solutions, including those for torquerts. This feature is associated with the individuality of technological equipment and technological schemes of metallurgical plants.
The technical implementation of self-propelled guns and process control systems by the processes of metallurgical enterprises and their workshops, as follows from the analysis, was made on the basis of various manufacturers.
Thus, existing developments, projects and existing systems for automatic control of the gunning process of an arc steelmaking furnace do not fulfill all the necessary functions for managing and controlling the parameters of the object under consideration. Therefore, the development of a system for the automatic control of the shotcrete process of an arc steel-smelting furnace is currently relevant.
The purpose of the master's thesis is – is to increase the efficiency of the shotcreting process of an arc steel-smelting furnace by developing an automatic control system that will improve the quality of the shotcrete application, as well as reduce operating costs for the process of gunning the chipboard.
To implement the management, control and protection functions, it is necessary to solve the following tasks:
Объект исследования: САУ процесса торкретирования дуговой сталеплавильной печи за счет разработки системы автоматического управления, что позволит повысить качество нанесения торкретмассы, при одновременном снижении эксплуатационных затрат на процесс торкретирования ДСП.
Предмет исследования: Алгоритмы управления с использованием современной элементной базы - программируемых логических контроллеров, датчиков и исполнительных механизмов.
As a rule, the following technological elements [1, 2 ]: the steel-smelting shop itself, consisting of six spans (batch, furnace, casting, continuous casting machine, adjusting, preparation of compositions), oxygen-compressor shop (CCC), bulk materials preparation department (OPSM), pumping and filtering stations, two gas treatment systems and traction substation for individual supply of furnaces.
In the first charge passage there are three electromagnetic cranes with a maximum lifting capacity of 75 and 20 tons. The charge mainly consists of scrap. Scrap is delivered from scrapbook in 20 t-containers by rail. Using the crane, scrap is unloaded from the containers into a 100 t-container, which is weighed on a mechanical 100 t-scale and then sent for unloading into the furnace [1, 2].
In the second furnace span there are two 180 t-bridge cranes. The main place in the span is occupied by two electric arc furnaces with a capacity of one hundred tons of the DSP-100 type with 50 kVA transformers. In furnaces alloyed and high alloy steels are smelted, including bearing ones. The furnaces are powered from a power substation located on the site. There are also two ferroalloy furnaces in the span, which are necessary for drying and heating ferroalloys. Each furnace has fourteen bins and seven dispensers. The mixture with OPSM through a conveyor belt is fed into the hopper and through a metering scale enters the casting machine of the tape type. Filling of additional materials is carried out using a multi-filling machine. The span also has a position-type vacuum cleaner, on which, by creating a deep vacuum, gases (hydrogen, nitrogen, oxygen) are removed from the steel and the steel is also purged with argon or nitrogen. The steam is supplied to the degasser through a steam line from the TPP-PVS through a reduction and cooling device (ROU 1-2). Between the DSP-1 and the degasser the installation ladle furnace
is located. It mainly produces steel refinement after smelting at DSP-1 and preparation for casting. Steel is brought directly to the steel pouring ladle.
In the third casting span, there are two bridge cranes with a lifting capacity of 180 tons. In the span there are two horizontal type installations for heating the lining of steel pouring ladles and two vertical ladle drying installations. Also in the span there are two stations for siphon casting of steel into molds. Steel is poured into ingots weighing 5.6 tons under an ash-graphite insulating mixture.
Next span – Caster. It has a radial six-gun continuous casting machine. Most of the smelted steel is poured on it. Also located in the span is an installation for replacing and repairing the steel lining of a ladle and a plant for drying the lining of ladles. An overhead crane with a lifting capacity of 50 tons [2, 3].
Fifth span – adjustage. It makes the reception, preparation and distribution of bulk materials, preparation of molds and more.
Sixth span – train preparation. Serves for the analysis and collection of compositions, sorting and packaging of ready-to-import blanks with continuous casting machines.
Also, the oxygen-compressor shop (CCC) belongs to the ESPC site. From it oxygen, hydrogen, nitrogen, argon and air are supplied to the site. KCC includes: two compressors of the KTK type - 12.5 / 35; two turbochargers of type K-1500-62-1 with auxiliary equipment, an air separation unit, three nitrogen compressors of the type ZGP-12/35 and two gas blowers.
Water used for cooling chipboard and continuous casting machines and other needs of the workshop is supplied by a pumping station. Before supplying water to the site, it undergoes rough cleaning at the filter station. Water is supplied through groundwater by powerful pumps.
Purification of the combustion products of the furnace before discharge into the atmosphere is carried out at gas purifiers 1 and 2 separately for each furnace. The work of gas purifiers is based on the electrostatic principle of action.
The refueling of the arc furnace lining is carried out mechanically and requires automation of this process [4, 5].