炉真空处理领域多采用蒸汽喷射泵抽真空技术,运行成本、能源和蒸汽消耗较高;干式真空泵抽真空技术多用于小吨位VD炉真空处理系统。 In the metallurgical industry , the RH furnace vacuum processing field mostly uses the steam jet pump vacuum technology , which has higher operating costs, energy and steam consumption ; the dry vacuum pump vacuum technology is mostly used in the small tonnage VD furnace vacuum processing system. 启动和运行更灵活、可靠,节能环保效果十分明显。 Compared with the traditional steam pump vacuum system , the dry vacuum pump system technology is more flexible and reliable in starting and running, and the energy saving and environmental protection effects are very obvious. 可以取消传统的蒸汽供应系统、蓄热系统和相关的水处理系统,但设备本身一次性投资较大。 The application of dry vacuum pump system can eliminate the traditional steam supply system, heat storage system and related water treatment system , but the equipment itself has a large one-time investment. 炉上采用了干式真空泵抽真空技术,建成了当时世界上处理能力最大的RH干式真空泵系统。 Baotou Steel used the dry vacuum pumping technology on the newly built 240tRH furnace , and built the RH dry vacuum pump system with the largest processing capacity in the world at that time. 干式真空泵系统最大的特点是运行成本、能源消耗极低。 The biggest feature of RH dry vacuum pump system is the extremely low running cost and energy consumption. 炉工艺要求,运行稳定,取得了突出的节能效果。 At present, the dry vacuum pump system can meet the requirements of the RH furnace process , stable operation , and achieved outstanding energy-saving effects. 泵系统能将被抽的气体通过真空管道排放到大气中,实现RH真空处理冶金功能。 Dry vacuum pump system means that the pump starts to evacuate from atmospheric pressure, and the pump system can discharge the pumped gas to the atmosphere through the vacuum pipe to achieve the RH vacuum processing metallurgy function. 炉的主要功能是通过在高真空度下对钢水进行脱氧、脱氢、脱碳处理, 真空泵系统根据RH工艺处理各阶段的真空度要求进行设计,不同的真空度通过真空泵系统的自动控制实现。 The main function of the RH furnace is to perform deoxidation, dehydrogenation, and decarburization of molten steel under high vacuum.The vacuum pump system is designed according to the vacuum requirements of each stage of the RH process.Different vacuum levels are achieved by automatic control of the vacuum pump system. . 在RH炉干式真空系统取得了一定的经验。 In recent years, through continuous exploration and research , certain experience has been obtained in the RH furnace dry vacuum system.
、 RH炉主要设备参数 1. Main equipment parameters of RH furnace
炉本体系统是由中冶京城和西门子奥钢联联合设计完成,干式真空泵系统是由ADREM公司设计安装完成。 The RH furnace body system was jointly designed by MCC Beijing and Siemens VAI , and the dry vacuum pump system was designed and installed by ADREM . The dry vacuum pump system can meet the requirements of the process. 炉主要工艺参数如表1所示。 The main process parameters of RH furnace are shown in Table 1 .
、干式真空泵系统 2. Dry vacuum pump system
真空泵参数 2.1 Vacuum pump parameters
干式真空泵系统由4级并联的螺杆泵和罗茨泵组成,包括10台超高流量的罗茨泵,10台高流量的罗茨泵,7台高流量高压差的罗茨泵,7台干式真空螺杆泵,并带有自动氮气吹扫功能和自动排除粉尘功能的过滤器。 The RH dry vacuum pump system consists of a 4 -stage parallel-screw pump and a roots pump , including 10 ultra-high-flow roots pumps , 10 high-flow roots pumps , 7 high-flow high-pressure differential roots pumps , 7 Dry-type vacuum screw pump , with a filter with automatic nitrogen purging function and automatic dust removal function. The suction capacity of the dry vacuum pump system is determined according to the process requirements and the system gas flow. 的压力范围运行工作,排气口与大气相连,能连续的向大气中排气。 The dry vacuum pump system can work in a pressure range of 20 ~ 105Pa . The exhaust port is connected to the atmosphere and can continuously exhaust to the atmosphere. 计算得出每级泵的抽气量以及能够承受的压差,然后对泵进行选型组合。 According to the metallurgical effect to be achieved , the pumping volume of each stage pump and the pressure difference that can be withstood are calculated , and then the pumps are selected and combined. 具体如表2 。 The pumping capacity and installed capacity of each pump are different , as shown in Table 2 . 达到设计要求的抽气能力。 Through the combination of different levels of pumps , the required suction capacity is achieved.
抽气能力 2.2 Pumping capacity
精炼装置的主要组成部分,其抽气能力、抽气速率等工艺参数直接影响RH炉的冶金效果,设计抽气能力在真空度67Pa时达到1100kg/h,真空度3min能够达到67Pa以下,完全满足工艺要求。 The dry vacuum pump system is the main component of the RH refining device , and its process parameters such as extraction capacity and extraction rate directly affect the metallurgical effect of the RH furnace . The designed extraction capacity can reach 1100 kg / h at a vacuum of 67 Pa and a vacuum of 3 min. It reaches below 67Pa , which fully meets the process requirements. 所示,真空度3min达到了67Pa,满足工艺要求。 The vacuum degree of vacuum processing at different times in the actual production process is shown in Figure 1. The vacuum degree reached 67 Pa in 3 minutes , which meets the process requirements.
过滤器系统 2.3 filter system
干式真空泵过滤器系统可以减少钢水处理时的烟尘,减少了烟尘对环境的污染。 RH dry vacuum pump filter system can reduce soot during molten steel treatment, and reduce the pollution of soot to the environment. 由粉尘颗粒引发的干式泵机械卡阻,结合干式泵的运行机理,设计中加装在线检测系统,优化干式真空泵系统停泵吹扫程序,解决了粉尘颗粒在密闭的环境下的检测和真空泵卡阻问题。 In the production process, the dust concentration of exhaust gas is difficult to check and find in a vacuum environment. The dry pump mechanical jam caused by dust particles is combined with the operation mechanism of the dry pump. An online detection system is added to the design to optimize the dry vacuum pump system. The pump purge procedure solves the problems of dust particles detection and vacuum pump jamming in a closed environment. 干式真空泵系统采用袋式过滤器,干式真空泵加工制造非常精确、而且内部公差非常小。 The RH dry vacuum pump system uses a bag filter . The dry vacuum pump is very accurate in manufacturing and has very small internal tolerances. 完全清除掉灰尘。 The exhaust gas entering the vacuum pump must be cooled to completely remove dust. Otherwise, dust entering the pump system will seriously damage the pump body. Therefore, the filtration and dust removal system is an essential key link for the dry vacuum pump system. 炉本体管道上安装了气体冷却器降低从真空槽抽出的废气温度。 The plant installed a gas cooler on the RH furnace body pipe to reduce the temperature of the exhaust gas drawn from the vacuum tank. 它把排气流中的粉尘颗粒沉降在下面的卸灰溜管内,然后废气进入真空条件下工作的袋式过滤器,降低了废气温度,去除了部分粉尘颗粒。 At the same time, the air cooler is also an inertial dust collector.It settles the dust particles in the exhaust stream in the ash discharge tube below , and then the exhaust gas enters the bag filter working under vacuum conditions , which reduces the temperature of the exhaust gas and removes some of the dust. Particles. Bag filters require certain precautions to work under vacuum. 完全密封,以防止空气泄漏进入真空系统。 The design of the filter needs to be able to meet the rapid change in pressure from vacuum to atmospheric pressure and be completely sealed to prevent air from leaking into the vacuum system. 钢水中的气体在低真空度下从钢水熔池中逃逸,同时逃逸的还有少量的气化金属,主要为在炼钢温度下具有高蒸汽压的金属锌、镁和锰。 During the process of vacuum refining of molten steel, the gas in the molten steel escapes from the molten steel pool under a low vacuum , and a small amount of gasified metals are escaped at the same time , mainly the metal zinc and magnesium with high vapor pressure at the steelmaking temperature. And manganese. 这些金属在真空系统内的冷却部件上升华,形成一层附着层,在真空脱气处理后打开真空脱气装置,它们暴露在空气下就立即着火燃烧。 On the way to the vacuum pump , the cooling components of these metals sublimate in the vacuum system to form an adhesion layer . After the vacuum degassing process, the vacuum degassing device is opened , and they are immediately exposed to fire and burn. 在每一脱气周期过程中,过滤器袋就覆盖一层自燃氧化物层。 The filter bag is then covered with a layer of spontaneous combustion oxide during each degassing cycle. 过滤器袋必须清除氧化物层,氮气吹扫系统在真空状态下会对布袋进行吹扫,以避免在下一脱气周期开始时,空气进入而发生着火。 After the degassing operation is completed , the filter bag must be cleared of the oxide layer . The nitrogen purging system will purge the cloth bag under a vacuum state to avoid air entering and fires at the beginning of the next degassing cycle. The filter is automatically cleaned at the end of each vacuum treatment. 向脉冲式射流清洗阀供应氮气,开启脉冲式射流作业程序,从而避免从一组过滤袋冲洗下来的灰尘又附着在邻近一组袋内。 When the vacuum pump is maintained at a low pressure or the vacuum main valve is closed , nitrogen gas is supplied to the pulsed jet cleaning valve , and the pulsed jet operation procedure is started , thereby avoiding the dust washed down from a group of filter bags from adhering to the adjacent group of bags. 而是从第一组开始,按交替方式清洗,这样可使灰尘沉淀下来,而不会被相邻组内的气流吹得到处都是。 The filter bags are not cleaned in order , but starting from the first group and cleaning in an alternating manner , so that the dust can settle down without being blown everywhere by the air flow in the adjacent group. 实施3次清洗周期。 Usually , three cleaning cycles are performed. 切断氮气供应,干式真空泵系统可继续进行真空处理作业。 After the cleaning is completed , the nitrogen supply is cut off , and the dry vacuum pump system can continue the vacuum processing operation. 可根本上避免过滤袋清洗后灰尘沉积。 The vibrator is installed on the hammer-shaped bottom of the filter , which can basically avoid dust deposition after the filter bag is cleaned. 则在随后的抽真空中,自燃性灰尘在可能清洁的过滤袋间旋流,容易引起过滤器着火燃烧。 If dust deposits occur , spontaneous combustible dust swirls between filter bags that may be cleaned during subsequent evacuation , easily causing the filter to catch fire. 必须调整抽真空管路旁路阀开启,以使真空槽和预抽真空过滤器之间有足够长的压力平衡时间,使过滤器支持笼不会变形,过滤袋不会被突然涌入的气流损坏。 When starting a new degassing cycle , the vacuum valve bypass valve must be adjusted to open so that there is a sufficient pressure equalization time between the vacuum tank and the pre-evacuation filter , so that the filter support cage will not deform and filter. The bag is not damaged by the sudden influx of air.
、干式真空泵系统工艺性能 3. Process performance of dry vacuum pump system
Dry vacuum pump system is mainly used for vacuum degassing, decarburization and deoxidation of molten steel, and regulating the temperature of molten steel composition. The number of pump sets, the types of pumps, and the size and number of pumps in each stage are determined based on the pumping capacity required for the specific process and system gas flow.
钢水循环速率RH炉环流气体的设计最大240m3/h,但由于处理量及真空槽设计不同,在满足各自工艺处理要求的条件下,不同真度下实际钢水的循环速率不同,206tRH真空槽浸渍管直径0.72m,真空处理过程中环流气体控制在150m3/h,循环量计算如表3 。 3.1 The circulating gas design of the molten steel circulation rate RH furnace is up to 240m3 / h, but due to the different processing capacity and the design of the vacuum tank , under the conditions that meet the requirements of the respective process treatment, the actual molten steel circulation rate is different under different degrees of truth. The diameter of the tube is 0.72m, and the circulation gas is controlled at 150m3 / h during vacuum processing. The calculation of the circulation volume is shown in Table 3 .
脱氢效果 3.2 Dehydrogenation effect
钢液中[H]含量随着炉内压力的降低而降低;在一定的压力下,[H]含量随温度的升高而增大,但在二次精炼中,压力对[H]含量影响远超过温度 。 At a certain temperature , the [H] content in the molten steel decreases as the pressure in the furnace decreases ; under a certain pressure , the [H] content increases with increasing temperature , but in the secondary refining , the pressure on The effect of [H] content far exceeds the temperature  . 时钢中w[H] ≤ 1.5 × 10-6,即低于氢在α -Fe中的溶解极限,从而可完全消除“白点”缺陷。 When the gas-phase pressure reaches 300Pa , w [H] ≤ 1.5 × 10-6, which is lower than the limit of hydrogen dissolution in α- Fe , which can completely eliminate the "white point" defect. 脱氢的真空度控制一般为200Pa以下。 Therefore, in actual production , the vacuum control of dehydrogenation is generally below 200Pa . 对干式真空泵系统进行不同时间氢含量的试验,图2是对真空处理不同时间的氢含量的影响,10min氢质量分数达到2 × 10-6左右,15min氢质量分数达到1.5 × 10-6以下,20min氢质量分数达到1 × 10-6以下。 The dry vacuum pump system has a faster dehydrogenation rate.The dry vacuum pump system was tested for hydrogen content at different times.Figure 2 shows the effect on the hydrogen content of the vacuum treatment at different times.The hydrogen mass fraction in 10min reached about 2 × 10-6 , 15min. The mass fraction of hydrogen reaches below 1.5 × 10-6 , and the mass fraction of hydrogen reaches below 1 × 10-6 in 20 minutes .
脱碳效果 3.3 Decarbonization effect
所有利于提高脱碳速率的各项因素都可以加快脱碳反应。 Due to the high temperature and strong agitation during vacuum processing , all factors that are conducive to increasing the decarburization rate can speed up the decarburization reaction. 随着提升气体流量增加,循环流量、容积系数增加,提高了脱碳速率,加快了脱碳反应的进行。 During the rapid decrease of the pressure in the vacuum chamber , with the increase of the increase of the gas flow , the circulation flow and the volume coefficient increase , which increases the decarburization rate and accelerates the decarbonization reaction. 炉不同时间碳含量的试验,图3是260tRH炉的脱碳情况研究,初始w(C)=(250~400) × 10-6,脱碳5minw(C)=(50~100) × 10-6;脱碳10minw(C)=(10~50) × 10-6;脱碳15min碳质量分数稳定在10 × 10-6以下。 The dry vacuum pump system was tested for the carbon content of the 7 furnaces at different times. Figure 3 is a study of the decarburization of the 260 tRH furnace . The initial w (C) = (250 ~ 400) × 10-6, and the decarburization 5minw (C) = (50 ~ 100) × 10-6; decarburization 10minw (C) = (10 ~ 50) × 10-6; 15 minutes after decarburization, the carbon mass fraction is stable below 10 × 10-6 .
能源消耗 3.4 Energy consumption
炉本体一样,运行时需要消耗氮气和冷却水。 The mechanical pump system is the same as the RH furnace, and requires nitrogen and cooling water during operation. 能耗为蒸汽泵系统的10%,运行成本和总消耗减少,节能效果十分显著,成本回收和获利速度快。 The dry vacuum pump system does not require steam and cooling water , the energy consumption is 10% of the steam pump system , the operating cost and total consumption are reduced , the energy saving effect is very significant , and the cost recovery and profitability are fast. 精炼年处理能力230万t钢水计算,干式真空泵系统与蒸汽喷射泵系统相比,虽然一次性投资成本较大,但系统运行稳定,生产成本极低(如表4),吨钢可节约成本6.4元,每年节约成本1472万元。 Based on the calculation of 2.3 million tons of molten steel with 240tRH annual refining capacity , compared with the steam jet pump system , although the dry vacuum pump system has a large one-time investment cost , the system operates stably and the production cost is extremely low ( see Table 4). Cost savings of 6.4 yuan , annual cost savings of 14.72 million yuan.
每次真空处理结束用氮气自动清洗过滤器系统,保证了干式真空泵系统的稳定运行。 The dry vacuum pump system uses a bag filter, and the filter system is automatically cleaned with nitrogen at the end of each vacuum treatment to ensure the stable operation of the dry vacuum pump system. 炉冶金工艺性能,使用干式真空泵系统脱氢和脱碳速率较高,20min氢质量分数达到1 × 10-6以下,脱碳15min碳质量分数稳定在10 × 10-6以下,取得了良好的工艺效果。 The dry vacuum pump system can meet the metallurgical process performance of the RH furnace . The dry vacuum pump system has a high dehydrogenation and decarburization rate . The hydrogen mass fraction in 20min reaches 1 × 10-6 and the carbon mass fraction in decarburization 15min is stable at 10 × 10- Below 6 , a good process effect has been achieved. 可降低RH炉吨钢生产成本约5.7元,极大的降低RH真空精炼的工艺成本。 The application of dry vacuum pump system can reduce the production cost of RH furnace ton steel by about 5.7 yuan , and greatly reduce the process cost of RH vacuum refining.
干式真空泵系设计抽气能力在真空度67Pa时达到1100kg/h,真空度3min达到能够达到67Pa以下,完全满足工艺要求。 1) The 260tRH dry vacuum pump system is designed to have a pumping capacity of 1100kg / h at a vacuum of 67Pa and a vacuum of 3pa below 67Pa , which fully meets the process requirements. 炉,运行稳定,能够满足RH炉工艺性能要求,钢水处理后钢中的[C] 、 [H]等气体元素满足了工艺要求。 The dry vacuum pump system is applied to the RH furnace , and it runs stably and can meet the process performance requirements of the RH furnace. The gas elements [C] , [H] in the steel after the molten steel treatment meet the process requirements.
采用干式真空泵系统,钢水中的[C]质量分数真空处理15min后达到了10 × 10-6以下,钢水中的[H]质量分数真空处理20min后达到了1 × 10-6以下。 2) With the dry vacuum pump system , the [C] mass fraction in molten steel reached 10 × 10-6 or less after 15 minutes of vacuum treatment , and the [H] mass fraction in molten steel reached 1 × 10-6 or less after 20 minutes of vacuum treatment. 极大的降低RH工艺成产成本,为的品种钢生产提供了保障。 The dry vacuum pump system runs stably, saves energy and protects the environment , greatly reduces the production cost of the RH process , and provides a guarantee for the production of various types of steel.