Optimize the design of the factory Zhou Yulei Shougang International Engineering Co., Ltd., and the good economic benefits that can be achieved.
Compressed air is the most widely used power source in the industrial field. Due to its advantages of safe and pollution-free regulation and good transportation, it is widely used in metallurgy. However, ordinary compressed air contains pollutants such as oil, water and dust. When these contaminants enter the compressed air piping system, they will rust the piping and cause the pneumatic tools of the instrument to malfunction. Therefore, the compressed air for the instrument must be purified.
In the design of metallurgy, the compressed air used is divided into ordinary compressed air and purified compressed air. In the conventional design, the classification statistics are used and then purified as needed. Therefore, the compressed air pipelines in the plant are divided into two types of common compressed air pipelines and purified compressed air pipelines. The air supply mode of the compressed air may also be a centralized air supply and a distributed air supply, or a combination of the two methods. In some old enterprises, as the scale of the enterprise is gradually developed, the compressed air facilities are mostly relatively concentrated or dispersed, while the newly built steel mills use more concentrated plans, and the whole plant is built in two to one concentration. The air compressor station is standing on the planning and plan formulation of the compressed air system of Shougang Jingtang Iron and Steel Plant. In order to achieve the goal of advanced energy saving and high efficiency, various optimization measures and advanced technologies have been adopted. The following main measures are briefly 1.1 air pressure. The relatively centralized setting of the compressor station uses centralized air supply, which can reduce the installed capacity of the equipment and the number of spare machines, and at the same time reduce the maintenance and repair personnel and costs of the equipment. In addition, large equipment can be used after concentration, and the efficiency of the equipment can be increased accordingly, thereby reducing operating costs. The shortcoming is that the pipeline network has been increased, which is not flexible enough in the transformation and expansion. However, for a large steel plant, such as Shougang Jingtang Iron and Steel Plant, it covers an area of ​​about 10 square kilometers. Not only does it require a large pipe diameter, but the average conveying distance will be far away, which will inevitably increase the investment in the pipe network. At the same time, it is difficult for the remote users to guarantee the gas pressure and gas quality. Therefore, the relatively concentrated method should be adopted. It is more reasonable. In the Jingtang Iron and Steel Plant, according to the distribution of the compressed air load of the whole plant, a centralized air compressor station was built in the steelmaking area of ​​the iron-making area and the milk-steel area to supply gas to the whole plant. A total of 13 sets of 250,1 were allocated. Centrifugal oil-free air compressor. That is to say, the advantages of centralized and large-scale equipment are satisfied, and the pipe diameter and the conveying distance of the pipe network are relatively reduced.
1.2 The pressure level of gas supply is 0.40.63 due to the pressure of the user of compressed air in the metallurgical enterprise. Considering the resistance loss of the pipe network, the design pressure of the air compressor is 0.8MPa. However, there are some users with lower pressure. For example, the gas for cooling the aerosol in the continuous casting workshop is 0.
3 or so, but the gas consumption is very large, especially in the slab workshop. For example, the continuous cooling machine for the continuous casting machine of the Jingtang Iron and Steel Plant has an average gas consumption of 1380 and the maximum gas consumption is 1690. According to the conventional design, it adopts 8%, 3 The air compressor is supplied with air, and the unit 40 is calculated at an outlet pressure of 0.8 MPa. The power of a single motor is about 2560 kW.
In the design of this project, an air compressor with an outlet pressure of 0.45 MPa is used, and its motor power is 1940. According to 8000 hours per year, 0.5 yuan is also calculated, which can save electricity costs of 2.48 million yuan per year. With a 0.8 MPa compressed air network as a backup and supplement, the progress has reduced the number of spare units and reduced investment.
1.3 Selection and characteristics of purification methods For the purification method, the dispersion of gas supply can only be decentralized purification. However, for centralized gas supply, it can be sent to various users after centralized purification. This method is adopted by Qinhuangdao Shouqin Company. In addition, it can also be used in the vicinity of the user. Shougang Qian’an Steel Plant adopts this method. A variety of gas supply and purification methods.
According to the conventional design, if centralized gas supply is used, and then partial purification is carried out according to the required amount of purified compressed air, it is sent to the whole plant in two ways. For pipelines that have not been cleaned, it is necessary to consider the discharge of water from the pipeline, and in the northern region, the antifreeze measures of the pipeline should also be considered.
In the field of compressed air drying and purification, a refrigerating compressed air dryer and an adsorption type compressed air drying device are often used for water removal and drying. The refrigerated compressed air dryer has the characteristics of low energy consumption, small size, light weight, simple installation and stable operation. However, due to the limitation of its water removal principle, the most economical and stable pressure dew point temperature that can be achieved by the refrigerated compressed air dryer is 2 Therefore, it is often used in applications where the quality of the compressed air is not high, and sometimes it is used as a pretreatment for the adsorption type compressed air drying device.
According to 08,132,779, the compressed air quality grade and the compressed air quality grade international standard 508573.1, the air quality rating of the pneumatic instrument is 233, the corresponding maximum dust content is 3, the maximum water vapor content is the pressure dew point 20, the maximum The oil content is 1 lb. 13. The metallurgical enterprise purifies the compressed air and treats it according to this standard.
In the previous design, in order to achieve the above-mentioned standard of compressed air, an adsorption drying device is generally used, and in particular, there is a self-consumption gas of 1215 for the thermal regeneration adsorption attachment drying device, and the micro heat regeneration power is converted. The air consumption is also around 15. The energy consumption of electric heating regeneration is not lower than this number. Therefore, if all the compressed air is purified, it will increase the consumption of gas and electricity. According to the calculation of ordinary compressed air and purified compressed air, if only 50 compressed air is purified, its self-consumption gas is about 7.5 of the total gas consumption, and all the purifying gas is about 5 of the total gas consumption. The operating energy consumption of the compressed air system will increase by 7.5, so the total purification treatment is rarely used. With the development of compressed air purification technology and the emphasis on waste heat utilization, in recent years, the technology of using residual heat and drying has been developed in China. And devices, and gradually got promoted and applied. This technology uses the non-stage compression heat of the centrifugal compressor to dry the adsorbent, which can reduce the energy consumption to less than 2. Therefore, in order to simplify the type of compressed air pipe network in the whole plant and improve the quality of compressed air throughout the plant, it is decided to use all compressed air. The waste heat regeneration drying device is used for centralized treatment and is supplied to all users of the whole plant.
The main working principle of the waste heat regeneration drying device is to use the heat generated when the gas is compressed to heat the adsorbent in the drying tower to desorb it. We know that both the piston compressor and the centrifugal compressor have the same exhaust temperature. According to the conventional air compressor design specification, the compressed air must be cooled to below 40, and then sent to the downstream equipment for drying, and a large amount of heat is wasted. The innovation of the waste heat regenerative drying device is that the energy is utilized to achieve the temperature rise and desorption of the adsorbent, and the regeneration process greatly reduces the operating cost of the drying device and solves the difficulty of high energy consumption.
The waste heat regeneration drying device and the micro heat regeneration drying device are simply optimized for a pressure of 0.7! Xian 3, the annual working day is 365 days, running 24 hours a day. The electricity price is priced at 5 yuan, the air compressor motor power is 1400, the air compressor exhaust temperature is 彡0, the self-heating electric auxiliary heating time is about, and the micro thermoelectric heating time is divided.
The use of the waste heat regeneration drying device has the following advantages as compared with the self-heating regeneration drying device to save cooling water. Since the desiccant regeneration absorbs a large amount of heat from the compressor exhaust, the temperature of the gas is greatly reduced when passing through the cooler of the drying device itself, and the cooling water consumption can be significantly reduced.
Improve the service life of the valve. As the switching cycle is extended to 4 hours, the number of actions of the corresponding valve is also reduced, and the service life of the valve can be extended by several tens of times.
Increase the life of the adsorbent. Also, due to the extension of the switching cycle and the reduction in the number of times, the impact on the adsorbent is also reduced, and the adsorbent is not easily broken.
Since the rice waste heat drying device can meet the requirements of the pressure dew 200 when the exhaust temperature of the compressor is 00, the pressure dew 200 can be basically satisfied. If the compression dew point is lowered, it needs to be realized by electric heating, so it meets the requirements of most users. Under the premise, no further progress is made.
For individual users, if the requirement is higher than this standard, the progress can be processed separately, and it is not necessary to raise all user levels.
Due to the drying method of waste heat regeneration, the total self-consumption gas of all the compressed air is only about 26,1 more than the self-consumption gas of the treatment 5, but the contribution to the whole system is not huge.
First of all, due to the use of a fully cleaned treatment, the entire gas supply network of the plant is simplified from the conventional two types of pipes, thus simplifying the system.
For the whole plant backbone network, due to the large flow, the whole compressed air main pipe network requires two DN500 seamless steel pipes. After using a single gas source, the two pipes can have a certain mutual complementability. The investment of the factory owner's thousand pipe network can save at least 30.
Secondly, in the conventional design, in the northern region, ordinary compressed air pipes need to be insulated to prevent freezing, and sometimes even heat tracing measures are required, and a large number of drainage points are required. Thanks to the use of fully dry compressed air, the pipeline does not require antifreeze measures and reduces many hydrophobic points, thus saving a lot of investment. Take the main thousand pipe network of Jingtang Plant as an example. According to the conventional design, the main thousand pipe network is divided into ordinary compressed air and purified compressed air. The average pipe diameter is DN400, the pipeline length is 7000m, and the common compressed air pipe insulation thickness is 50mm. The material is rock wool, and every 100 meters of water is used to drain the water point. Only the heat preservation and hydrophobic items can save about 500,000 yuan.
In addition, since the entire plant uses purified compressed air, it can reduce the wear and corrosion of gas equipment for users of compressed air, prolong the service life of equipment and reduce the maintenance of equipment. Unpredictable. Therefore, the planning and design of this system is advanced and reasonable.
The compressed air supply system of Shougang Jingtang Iron and Steel Plant adopts advanced technologies and optimization measures such as relatively centralized gas supply and grading gas supply waste heat regeneration drying system to purify the gas supply, so that the gas supply system of the whole plant has reached safety. Reliable, energy-efficient and efficient technology with advanced goals.
Zhou Yulei 197, male, Han nationality, professor-level senior engineer, master of engineering, member of the thermal engineering design committee of China Petroleum and Chemical Exploration and Design Association, member, mainly engaged in the design and research work of metallurgical thermal power engineering.
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