"8" Energy-saving magic of change "3" - a journey of time concept and methodology between TISCO and Siemens SINAMICS PERFECT HARMONY GH180 Drives

Q: How does 8 become 3? Answer: Cut in half vertically. This is the answer to the brain teaser, but it is not the answer of Taigang, because the daring Taigang people obviously want to create a bigger magic on the energy-saving digital change. Through the cooperation of TISCO and Siemens, the inverter has become a "magician" and successfully "changed" the power consumption of a single motor in the sintering fan from 8,000 kWh to 3,000 kWh.

Taigang No. 4 sintering machine with an area of more than 600m2 uses two sets of Siemens Robicon Perfect Harmony MV Drive and high-voltage motors. In this large stainless steel enterprise, the concept of time is interpreted as: energy saving and production are all a race against time. The feeling that time and energy efficiency can be replaced by "magic" is particularly strong. One large inverter can save 5,000 kWh in one hour, and two large inverters can save 240,000 kWh in one day. For example, based on the self-supply price of 0.4 yuan/kWh, more than 30 million yuan in electricity costs can be saved in one year, and the equipment cost can be recovered within 18 months, and the energy saving rate can reach 40%, making the initial equipment investment into a successful strategic technological innovation.

Exterior view of Taigang No. 4 sintering fan system

Stainless steel giant partner with energy saving partner

From Shenzhou-1 to Shenzhou-10, every time the spacecraft lifts off, TISCO stainless steel products help it. From a dime to a rocket satellite, from the dining table of the common people to the Three Gorges Dam, the stainless steel produced by TISCO has occupied nearly half of the domestic stainless steel market with its absolute advantage. As the initial process of stainless steel melting, the sintering process is the key. Which variable frequency drive scheme to use is a major directional choice.

At that time, the No. 4 sintering machine of Taiyuan Iron and Steel Co., Ltd. was about to be put into operation, and its scale was undoubtedly the largest in the world. The larger the sintering area, the higher the output and the higher the requirements for the fan, so the energy consumption is huge. According to the actual working conditions of Taigang No. 3 450m2 sintering machine, Taigang plans to

Two large frequency conversion units are used in the 600m2 large-scale sintering fan to control the speed of the high-voltage motor. Although the use of variable frequency drive fans can greatly save energy, and it is the general trend. However, there is no precedent for such a large-scale application, the technical difficulty is high, the return on investment is unknown, and no one dares to act rashly.

Since the idea of designing the largest variable frequency speed regulating fan in China, Zhao Hong, director of the electrical department of Taigang Iron Works, has always paid attention to all kinds of knowledge and information. One day, while communicating with foreign experts, Minister Zhao learned that the performance curve of the fan could be calculated by using the temperature, pressure and flow rate of the main air flow. "That's exactly the curve that TISCO needs. With this curve, the fan control is more precise." Minister Zhao immediately organized a team to start technical research.

After day and night calculations and evaluations, in 2008, Minister Zhao's team submitted a ten-page project feasibility report and decided to adopt the frequency conversion speed regulation technology. The initial investment of this program is large, but with a long-term perspective, the entire investment can be recovered within two years. After research on advanced technology and rigorous reasoning, in April 2009, TISCO officially opened the road of frequency conversion and energy saving.

At the same time, TISCO also gained a reliable energy-saving partner. The sintering workshop dared to try new things and adopted the most advanced frequency conversion energy-saving technology. The Siemens expert team played an indispensable role in this process. Since there are no domestic projects that can be referenced, the overall technical solution must rely on the joint efforts of TISCO and Siemens to explore together. Recalling the scene at that time, Minister Zhao said frankly: "In the few days of the final calculation, I couldn't sleep at night. This is related to the investment of more than 50 million yuan. If the error is too large, how can I explain it to the factory!"

10,760kW Siemens high-voltage motor used in Taigang No. 4 sintering machine

15,000kVA Siemens Robicon Perfect Harmony MV Drive Cabinet

Before adopting variable frequency speed regulation, Taiyuan Iron and Steel used the damper baffle to adjust the air volume

Three steps to management, a big step to save energy

Siemens' energy management methodology is based on three steps, identification, evaluation and realization. The previous time view mainly solved the problem of "how to calculate" energy efficiency, while the methodology here mainly solved the problem of "how to do" energy saving. With the support of methodology, TISCO and Siemens have made great strides in energy-saving cooperation.

The first step is to fully identify and tap the hidden energy-saving potential of TISCO. How to identify energy flow? First of all, take an "X-ray" of the energy consumption of all equipment, which equipment can

The consumption is large, which energy consumption is small, which energy consumption is useful, and which is useless, you can see clearly. only

Only by mastering the consumption data of electric energy, water energy and heat energy in a long period of time can further transformation and optimization be possible.

The Siemens expert team first took the No. 3 450m2 sintering machine without variable frequency speed regulation as a sample to record the energy consumption in the workshop and system. After analysis, the power consumption of the sintering main exhaust fan generally accounts for 50% of the entire production line, and the accuracy of the air volume control directly determines the quality and output of the finished product.

In the second step, the cost of the plant and system over the entire life cycle is assessed, the energy saving potential of the specific application and the cost-effectiveness of possible measures are calculated.

The energy flow is transparent, and after identifying the largest energy-consuming equipment, the sintered main exhaust fan, the “assessment” phase begins with calculating the specific energy saving potential and considering the economics of the potential measures, which is a key step in making a decision. This step is like the process of a general practitioner taking X-rays and various laboratory reports, carrying out pathological analysis, and giving a diagnosis.

The faster the fan rotates, the more air is supplied, but the energy consumption also increases exponentially. If the speed is reduced, the energy consumption is also doubled. After repeated demonstrations, under the conditions of the same product and the same output

The frequency conversion speed regulation is equal to saving energy all the time. Even in the case of full-load production of the entire sintering plant, the conservative estimate of the energy saving rate will be above 35%.

The third step is to take targeted measures to turn the energy saving potential into reality. About 2/3 of the industrial energy is consumed by the drive system, and it is very practical to reduce the energy consumption of the entire drive system by 40-50%. . With the doctor's diagnosis report, the next step is to prescribe the right medicine. The medicine is reliable and durable, and the pain can be swept away. After examining various frequency conversion schemes, Taigang finally decided to choose two Siemens SINAMICS PERFECT HARMONY GH180 Drives.

The output voltage is 10KV. The inverter adopts water cooling process, which adopts deionized water circulation cooling inside, and uses industrial cooling water for secondary cooling outside. Compared with air-cooled inverters, no additional cooling equipment such as air conditioners is required, and the inverters have low noise and are affected by the surrounding environment.

The impact on the environment is small, and the frequency conversion room is neat and clean. In addition, the Siemens Robincon high-voltage inverter also has a "flying start" function, which shortens the waiting time of nearly 50 minutes for each start and stop of the fan, thereby greatly saving energy consumption and time costs.

Equating energy efficiency with timeliness

When the fan was successfully started under the variable frequency condition, the active power on site was only 3000KW, which was far lower than the 8000KW without the use of the frequency converter. The hanging heart of Minister Zhao's team was really at ease. Data verification The preliminary calculation is very accurate. Working under variable frequency conditions, the motor has small starting current, low speed, small vibration, and stable air volume adjustment. The potential additional economic benefits are limitless.

Cheng Haifeng is an inspector in the electrical operation area of Taigang Iron and Steel Plant. He is also the only engineer who is engaged in inspection work in No. 4 sintering machine. Usually, the electrical room is unattended, and only another colleague monitors it in the central control room. At 9:00 every morning, he went to the 4-burning frequency conversion room on time to make a round to check whether there was any abnormal situation. It has been nearly 4 years.

Inspector Cheng Haifeng is introducing the working status of the inverter to the returning Siemens service engineer

Stepping into the door of the frequency conversion room, it is more quiet and refreshing than expected. The joy of Chenggong is beyond words: "The use of water-cooled large frequency conversion, low noise, and no air-cooled dust pollution. The workload of colleagues has been reduced, and the working environment has also been improved, and there is no need to operate the damper baffle as frequently as 3 burners. 90 % of the field data can be visually displayed in the central control room, with less maintenance and stable operation.”

"Water-cooled frequency conversion, as the system drive of large-scale sintering fans, is the first application in large-scale steel mills, attracting many companies to come to TISCO. Seeing our active power and inverter water-cooling temperature, colleagues are very impressed." Minister Zhao Pointing to the human-machine interface in the frequency conversion room, he said, "Energy efficiency is essentially the same as aging, but few people realize it."

The energy saving story of sintering machine No. 4 is only a microcosm of energy management. The significance of this is that there are expensive and cheap solutions to almost everything, but economic facts are often obscured by "fog". The right decision can only be made by evaluating the energy efficiency of the entire product life cycle.

Energy is a huge cost factor for heavy industry. According to data from the German Federal Statistics Office in 2008, energy consumption accounts for a high proportion of the cost of the entire life cycle of various industries in Germany. For example, aluminum industry accounts for 57% of energy consumption and cement accounts for

47%, iron and steel 36%, pulp and paper 29%, and basic chemicals 27%. For electric drive systems, energy consumption accounts for at least 80% of the life cycle cost.

In the process of building a resource-saving enterprise, TISCO uses Siemens variable frequency drive solutions, total integrated automation, and advanced steel technology from voestalpine to ensure that the output increases year by year, but the energy consumption decreases year by year. Mr. Gao Xiangming, general manager of TISCO, said: "Compared with 2005, TISCO's comprehensive energy consumption per ton of steel decreased by 22.9%; fresh water consumption per ton of steel decreased by 91%; annual secondary energy recovery accounted for 45% of the total energy consumption. % or more, reaching the industry-leading level.”

This is the magic that TISCO and Siemens jointly created. Behind a series of figures, what is really perceptible is the reduction of energy consumption and the improvement of the environment. The molten iron is flowing, and the situation is calm. In the current Taigang factory area, the metal-textured factory room is dotted with green trees and green grass, making it a veritable modern garden-like factory.

Siemens is working hard to help thousands of companies like TISCO to practice green industry. Dr. Wu Hele, President of Siemens Northeast Asia Industrial Business Area, said: "In addition to the need for energy saving at the equipment level, such as high-efficiency motors, frequency converters, etc., it is necessary to look far beyond product design, production planning, production engineering, production implementation and The whole life cycle of the service can realize energy saving." Siemens' energy-saving products and solutions, energy management consulting, energy-saving renovation services, contract energy management and financial leasing services have turned industrial enterprises' energy-saving dreams into reality.

Modern garden-like factory - TISCO

The change from 8 to 3 is a beginning and a declaration. Standing on the stage of innovative technology, TISCO and Siemens will work together to stand against the wind, continue to perform the magic of transforming energy efficiency figures from decay into magic, and create a technologically sensitive era for the future of steel!