Ansteel equipment maintenance and coordination center of steelmaking work area of the north operation operation area
Abstract: for the Ansteel two steelmaking plant industrial water consumption and the process characteristics within the system, the proposed energy saving and environmental protection with the re-cycling, increase cooling facilities, filtering again is feasible. Actual production has proved that after the improvement than before the improvement of water saving 40%, is conducive to Anshan Iron and Steel internal industrial water to achieve energy saving and emission reduction.
Keywords: zero discharge system, multi-set cooling tower, shaft sealing device, sealing performance, new drug pump
0. Foreword
Under the guidance of Anshan Iron and Steel's scientific concept of development, Anshan Iron and Steel has been moving towards the construction of a harmonious society, the construction of resource-saving and environmentally friendly enterprises, to the minimum possible consumption of resources and costs to obtain the maximum economic and social benefits, that is. "less input, more output", to realize the harmonious unity of economic, social and environmental benefits. Scientific and technical personnel and field operators conduct on-site technical data collection to create new water-saving processes and measures to save water resources and reduce industrial water discharges.
Trial operation of zero-discharge system
The water treatment pumping station of the No. 1 continuous casting machine of the second steel plant, which was built in the 1980s, and the water treatment pumping station of the No. 2 continuous casting machine, which was built in 1997, use their own two sets of filtration systems. This single process not only makes the industrial water consumption is large, overflow water pollution of the environment. In order to realize the zero discharge of sewage, new water with little or no input, less pollution to the environment, in 2007 the second steel mill invested in a new pumping station, called "zero discharge pumping station". The pumping station introduced two sets of domestic advanced vacuum pumps and a filter, transformed the first water treatment and the second water treatment pumping station of the indirect, direct two major systems, the overflow of these two systems to collect a mixture of water sent to the zero-discharge system, and then filtered and utilized, re-entering the production of ring water system, to achieve the total recycling and reuse of industrial wastewater. Daily record data show that the original water treatment pumping station an indirect water tank daily replenishment reached 18 to 24 times, water consumption of about 1,000 to 1,200 cubic meters, accounting for half of the water consumption of the entire system. After the operation of the zero-discharge system, the indirect water tank does not need to be replenished daily, which greatly reduces the cost. In the zero-discharge system, scientists and technicians have adopted a closed-loop circulation system and an automatic return valve device, which completely controls the switch of the return valve by the water level and reduces the labor intensity of workers. This five systems combined "small area cycle", that is, in an area of water recycling approach, making full use of water resources, to achieve a water multiple use, significantly reducing water consumption, the original total daily water consumption of 4,000 cubic meters per hour, is now 2,400 cubic meters per hour. But this system can not run continuously, intermittent operation to ensure the quality of cooling water. Specific process flow diagram in Figure 1.
More cooling towers
According to the Iron and Steel Federation statistics, the degree of water consumption in the production process, in order of ironmaking, steelmaking, rolling coking, sintering. The most water-consuming part of the steel mill is the billet cooling water. Billet cooling water treatment process cooling is the largest water consumption. With the intensification of the greenhouse effect and the continuous improvement of production, the original cooling equipment of the continuous casting operation of the second steelmaking plant has gradually failed to meet the production indexes, especially the water temperature of the crystallizer cooling water, in the summer, it mainly relies on the workers to monitor the temperature of the cooling water to manually open and close the valves to make up the water to the two sinks and the two tanks to cool down the temperature, which not only increases the amount of labor of workers but also wastes the cost of medicines, new water, and spares and other related costs. Through the daily cooling water indicators monitoring and recording, in the original four cooling towers on the side of the open space on a new cooling tower, the new cooling tower and the old cooling tower control the same way to set up.
The new construction of the cooling tower allows the water temperature of the indirect cooling water to be effectively controlled within the production targets. If you do not build a new cooling tower, the only way to rely on make-up water to cool down, the waste is not only new water, but also a waste of medicine. What's more serious is that the replenishment water will overflow to a certain water level, and the industrial water containing a large amount of pharmaceuticals will seriously pollute the groundwater and the environment. First of all, from the perspective of long-term sustainable development, the construction of cooling towers is a one-time investment, a long time to benefit; Secondly, Anshan is a city with a serious lack of water resources, with millions of people in the industrial city, including Anshan Iron and Steel water consumption accounted for more than 2/3 of the city's total water consumption, a large number of discharged industrial water is a threat to the valuable and limited groundwater resources. 80% of the world's diseases and 50% of children's diseases are related to contaminated drinking water. For the sake of our living environment, the development of industry would rather sacrifice money, but also do not sacrifice the source of life of future generations - water.
3. Improve the production of the main pump shaft sealing device sealing performance.
Most of the water treatment pumping stations for horizontal centrifugal pumps, the shaft sealing device using packing seal. Before 2007, the use of full soft packing seal water leakage, maintenance can not be controlled. 2007, soft packing and new sealing packing combination, greatly improving the sealing performance of the shaft sealing device, due to the new sealing packing (mud mixed packing) sealing no leakage, only the soft packing leakage, the amount of shaft sealing drip has been controlled in the standard range of 20-30 drops. Muddy mixed packing sealing structure as shown in Figure 2, packing cavity at both ends of the soft packing ring, as the middle packing fixed with two soft packing ring filled with mud mixed packing (CMS2000). Mud mixed packing is a new type of sealing packing, which consists of synthetic fibers, high purity graphite or polymer silicone, PTFE, organic sealant for mixing, forming a mud-like material without specification restrictions. The packing and shaft synchronous rotation into one, reducing the shaft and packing between the water leakage, sealing and reliable: after the improvement of this packing at the need for flushing and cooling, but also reduces the consumption of industrial water. As shown in Figure 2.
4. Change to a new type of drug pump.
From the 80's to 2005, the vertical drug pump has been the main equipment of the water treatment pumping station. 24 hours a day at regular intervals by manually adding drugs into the drug tank, and then manually turn the drug pump, drugs along the pipeline into the corresponding sink or tank, the drawbacks of this drug pump is that the drug is not uniform, the water in the drug concentration is not stable; in operation for a period of time after the pipeline is prone to clogging, the overhaul rate is high, once the pump malfunctions, it is necessary to rely on manually timed to the tank or tank to add the drug to the cooling water, so that the dose of the drug in the water is high and low, not uniform. Sometimes the water tank or water tank running water, the drug dose even reached zero. In order to restore the concentration of the drug sometimes must be manually cleaned tanks and overflow work, a large amount of industrial water is wasted. Since 2006, the drug pump all use shell for corrosion-resistant plastic injection plug-type drug pump, this pump maintenance failure rate is very low, good sealing performance, drug injection uniformity, lasting.
In the actual production, the above four aspects of the equipment is only a part of water conservation and environmental protection transformation, after my personal research, in addition to the zero discharge system has a great defect, the other aspects have been fully in line with the production requirements. So I concluded that the zero discharge system needs to be improved, now put forward three suggestions:
Can be added to the pipeline before the filter double filter, or install a filter of the same type. After the laboratory technician test, zero discharge filtered water turbidity is high, mainly suspended solids, indicating that the existing one filter can not meet the filtration requirements, must increase one for re-filtering.
Zero discharge system should be introduced to the dosing system, in order to ensure water quality. Zero-discharge system of water mainly from indirect sinks and direct sinks of the overflow water, the collection process is inevitable impurities into the water quality must be improved by means of dosing.
Increase the number of filter backwash. Now the site due to a variety of reasons can only be three backwash, should increase the number of backwash, so that the water filtration more clarified.
References:
(1) Seal Design Manual, Fu Ping, Chang Degong, editors, Beijing, Chemical Industry Publishing House, 2009.4
(2) Pump Maintenance Manual, Wei Long, edited by Tao Linjie, deputy editor, Beijing, Chemical Industry Publishing House, 2009.7
(3) Practical Handbook of Water Treatment Equipment, Song Yelin, Song Xiangling, editors, China Petrochemical Publishing House, 2008.7