Environmental cupola is still energetic: STATE OF THE U.S. CUPOLA INDUSTRY

In recent years, the requirement of energy saving and emission reduction has been increasing and strictly implemented, so many people believe that the application of cupola is declining day by day, and it is an irreversible trend to be replaced by induction furnace. In reality, a large number of cupolas have been banned, and the wind that cupolas will be completely withdrawn from the field of foundry is also very noisy.

Is the cupola really useless? Where on earth has it been criticized by the public? Faced with a comprehensive ban, who in the world did the cupola provoke?

Environmental cupola 

Cancellation of cupolas in SMEs does not affect their importance

For the potential trend of abolishing cupola completely, Li , a senior consultant of China Foundry Association, does not think so: “If the development of cast iron smelting equipment is analyzed comprehensively, cupola has irreplaceable characteristics of electric furnace, and from the perspective of low-carbon economy, cupola, a traditional smelting equipment, still has strong vitality and broad development space.”

According to Li ‘s analysis, it is very suitable for small and medium-sized foundry enterprises to replace cupola with induction furnace; however, foundry industry is an industry with high energy consumption. In the future, enterprises will develop towards clustering and large-scale, and the output of medium and small foundries will account for a smaller and smaller share of the total output of castings. “At present, in terms of the number of melting furnaces used in the iron industry in various industrial countries, of course, induction furnaces are much more than cupolas,” he said. But most of the cupolas are large-scale, and they are of long furnace life, and have strong production capacity. If the output of iron castings is concerned, the cupola smelting is still the majority. That is to say, cupola and electric furnace will coexist forever in cast iron melting, and the amount of cupola melting is more than that of electric furnace

 

STATE OF THE U.S. CUPOLA INDUSTRY

美国冲天炉行业现状

David Kasun   August 22, 2018

作者:David Kasun    2018年8月22日

Since the advent of time, cupola furnaces have melted the vast majority of cast iron worldwide and in the U.S. While the number of operating cupolas in the U.S. has decreased from about 200 to 42 cupolas since the turn of the century, advances in cupola technologies, increases in cupola efficiency and the metallurgical and cost benefits of cupolas have ensured they remain as a significant, and leading technology for iron production. The 42 cupola foundries in the U.S. produce approximately 53% of all domestic cast iron. Nearly 62% (3.75 million tons per year) of all gray iron production and nearly 38% (2.3 million tons per year) of all ductile iron production is produced by cupola melting.

很长一段时间内,在美国,冲天炉都是熔化多种铸铁的主要设备。虽然在美国国内正在运行的冲天炉从2000年左右的200台降至如今的42台,但是冲天炉技术的升级,冲天炉效率的提高以及冶金和冲天炉本身的成本红利仍然确保了冲天炉在铁的生产过程中的重要以及主要技术地位。在美国国内现今运行的42座冲天炉铸造厂,供应了美国铸铁产量的53%。约62%(375万吨每年)的灰铁生产和38%(230万吨每年)的球墨铸铁生产是由冲天炉提供的。

Projections from AFS Metalcasting Forecast & Trends show that total annual shipments for iron castings is 6.74 million tons per year. By applying typical yield rates for the various SIC codes (ductile pipe, municipal, agricultural, automotive, etc.), estimates show that total tons melted for all iron types total about 11.45 million tons per year. By applying knowledge-based estimates of the cupola industry, it is estimated that of the total iron melted, about 6.07 million tons per year are melted by 23 companies using cupolas.

根据美国铸造协会的‘金属铸造预测和趋势’,每年的铸铁一共有674万吨。通过将典型的收益率应用于各种标准工业分类编码上(球墨铸铁管,市政的,农业的,机动车的等等),预测显示各种铁质类型的年产量为1145万吨。通过应用基于知识的预测,在每年的铁熔化量中,大约有607万吨是由23家使用冲天炉的厂家所提供的。

There are SIC sectors, such as ductile iron pipe and high production automotive/industrial/municipal foundries, where cupolas are the mainstay. In other SIC sectors, demand for a wide variety of metallurgical grades have made the cupola less attractive. Cupolas have, however, remained highly competitive, due to their flexibility, giving them a competitive advantage over electric melting methods.

在标准行业分类中,例如球墨铸铁管和高产量的机动车/工业/市政铸造,冲天炉是支柱。在其他标准行业分类中,对于冶金等级的多种广泛的需求降低了冲天炉的吸引力。冲天炉因为其灵活性仍然在与电熔化方法的比较中保持了竞争性优势。

While cupolas are a big part of the iron melting picture in the U.S., the landscape of the cupola has changed. Stricter environmental regulations in the last three decades, combined with the changing metallurgical demands in foundries, have led many to believe that cupolas are going away. While it is true that there are fewer cupolas, it can be said with certainty they are not going away anytime soon. Cupolas continue to have some advantages, compared to electric melting, but there are six primary myths about cupolas that should be dispelled.

虽然冲天炉在美国仍然在铁的熔化中占有大量份额,但是冲天炉的前景已经改变了。在过去30年中,更加严格的环境政策以及铸造公司不断改变的冶金需求,使得许多人认为冲天炉正在逐渐消失。虽然事实上冲天炉的数量在降低并变得很少,但是它们不会很快消失。相对电炉,冲天炉一直保持着一些优势。但是这里有6个有关冲天炉的误会需要被消除。

Myth 1: Cupolas are going away.
Many old, inefficient, obsolete cupolas have mostly gone away. While some cupolas are challenged by operation at low production rates, the remaining cupolas mostly have increased thermal efficiencies and many have incredibly high efficiency rates. Some technical advances can be made with minimal capital expenditure. The post combustion heat recovery systems are better, and cupola shops are pursuing methods to reclaim waste heat and increase hot blast temperatures (up to 1,150F) to decrease coke rates while many have found ways to beneficially reuse slag. Alternative carbon and fuel sources have been established and chemistry transition practices have been modernized. The bottom line is cupolas now are more efficient with higher productivity per unit. Many cupola shops continue to invest in technical improvements in furnace efficiency and heat recovery systems as part of their long term strategy for sustainability.

误会一:冲天炉在消失

许多老旧,低效以及废弃的冲天炉几乎都消失了。虽然一些冲天炉因为运行时的生产效率低而被批评,但是剩余的冲天炉大多数已经提升了热效率并且许多拥有了令人难以置信的高效率。一些技术上的进步可以通过最小的资本投入而实现。燃烧后的热量回收系统更好,因此冲天炉工厂正寻找可以回收利用废热并且提升热风温度(高达621摄氏度),这样做可以降低焦炭消耗量。同时,许多冲天炉工厂找到了利用矿渣的方式。可交换的碳和燃料来源机制已经建立,化学转变实现了现代化。底线是,冲天炉现在已经变得更加高效(更高的单位产量)。许多冲天炉工厂一直在提升熔化炉的效率和回收机制上进行投资以期达到长期的持续战略。

Myth 2: Cupolas are economically infeasible.
Continuous production rates and flexibility in scrap input gives cupolas an economic advantage. Production rates are steady and predictable. A wide range of scrap input can be handled, such as dirt, high zinc, shredder contaminants, bundles, iron briquettes, high oxide content and self-reducing briquettes. In stream desulfurization for ductile or compacted graphite base iron allows for the melting of low-cost high sulfur scrap. Cupolas can accommodate up to seven iron chemistry changes per day, supplemented with in-spout alloy additions. Cupolas are well known to have lower labor cost per unit of iron, especially for high production cupolas, say above 20-25 tons per hour.

误会2:冲天炉在经济上不合算

持续性的生产率和在废料输入的灵活性给予了冲天炉在经济性上的优势。生产率是稳定与可预测的。可以用于冲天炉的废料包含的种类很广,比如灰尘,高锌,被粉碎的污染物,束装的材料,含煤铁球团,高氧化物和可自我消耗的煤粉。用于延展性或致密性的石墨铁的流体脱硫过程可用于熔化低成本的高硫废料。冲天炉每天可以适应多达7种铁化学过程的变化,并补充了喷口合金添加剂。冲天炉因单位铁产量的低劳动力成本而知名,尤其是那种高产量的冲天炉(比如产量每小时20-25吨)

Myth 3: It is impossible to obtain permits for cupolas.
While regionally designated environmental areas can make permitting difficult for any new foundry, new cupolas can be permitted and meet the strictest requirements. New gas combustion and dust collection technologies can meet MACT particulate matter and hazardous air pollutant and volatile organic compound standards. Gas concentrations like SOx and NOx are generally not of great concern, even in some EPA designated ozone non-attainment areas. State of the art pollution controls for cupolas have been in place in Europe for two decades, where regulations are more strict than in the U.S., proving that properly designed air pollution control systems make cupolas viable. In fact, properly designed control systems provide ultra-low maintenance costs, with extended filter life (bag changes) on the order of 8-10 years.

误会3:不可能拿到冲天炉的许可

虽然区域性的被指定的环境区域对然和新建铸造项目而言都很难拿到许可,但是新的冲天炉可以得到许可并且满足最严格的要求。新的燃气和除尘技术可以达到MACT标准所规定的有关颗粒物和有害气体污染以及挥发性有机化合物的排放标准。气体的浓度(例如SOx和NOx)通常不会得到足够的重视,即使是在一些由美国环境保护部指定的臭氧未达标区域。先进的冲天炉污染控制措施已经在欧洲实施了二十年,其中法规比美国更严格,证明适当设计的空气污染控制系统使得冲天炉的可行性。事实上,被合理设计的冲天炉系统仅仅需要付出超低的维护成本,并且可以延长滤袋的使用寿命接近至8-10年。

Myth 4: Cupolas are energy intensive and inefficient.

误会4:冲天炉是高耗能与低效的
Cupolas are inefficient only if they are following“old” methods and designs. The high efficiency cupola plants of today produce iron that is 15% less energy intensive than iron produced from coal-produced electricity (medium frequency). When methods for waste heat reclamation are installed (cupola flue gases), cupolas are 40-60% more energy effective than electric melting. As electricity prices and natural gas prices increase in the future, the benefits of cupola melting, using coke as a the heat source, will become more attractive. We should remember that only about 85% of the coke charged into a cupola is burned for heat, and that about 15% of the coke is dissolved into the cast iron as metallurgical alloy, a very effective means of carburizing iron, especially for high steel charge mixes.

造成冲天炉低效的唯一情况是使用过时的生产方法与设计。当下高效率的冲天炉车间生产的铁的能耗成本可以比由燃煤发电所生产的铁(中频)要低15%。当安装废热回收方法(冲天炉烟气)时,冲天炉比电熔法的能量效率高40-60%。随着未来电价和天然气价格的上涨,使用焦炭作为热源的冲天炉熔化的优势将变得更加吸引人。我们应该记得被加入冲天炉的焦炭的大约85%被燃烧用于生热,15%的焦炭作为冶金合金溶解在铸铁中,这是一种非常有效的渗碳方法,尤其适用于高钢混合料。

Technology advances extend beyond the furnace, to further to reduce the energy intensity of the entire cupola plant. Approximately 20 U.S. states have now defined industrial process waste heat as a renewable resource, making it, in some cases, not only recognized as a resource for harvest, but also making the capital investment eligible for funding and/or tax credits. The best, most efficient cupola shops have already installed, or are actively pursuing the installation of waste heat capture systems that can harvest and re-use the heat for a variety of processes. These include:

技术的升级延伸到了熔化炉之外(会更进一步的降低整个冲天炉车间的能耗)。美国大约有20个州已经将工业生产过程中的废热定义为可再生资源,这使得它在某些情况下不仅被认为是可以利用的资源,而且还使资本投资有资格获得资金和/或税收抵免。最好的和最高效的冲天炉车间已经安装或者正在积极寻求安装余热补集系统(用于多种生产过程的热量的收集和再利用)。它们包括:

Plant and office makeup air heating.
Cupola blast air dehumidification.
Core oven heating.
Electric power generation.
Domestic water heating.
Other process heating.

车间和办公室的补充空气加热

冲天炉鼓风除湿

砂芯烘炉加热

发电

生活用水加热

其他生产过程的加热

Investment in these technologies will significantly reduce the electric and/or natural gas consumption of the foundry and reduce the overall energy intensity of the final product, iron castings.

在这些技术上的投入将会显著的降低铸所需的电力以及天然气的消耗,并且降低最终产品的整体能耗。

Myth 5: Coke is too expensive.
It is true that coke is somewhat costly, but prices have significantly dropped and stabilized in the last five to eight years. Electricity prices, meanwhile, have increased and been somewhat unpredictable. It appears that high quality European coke and formed coke suppliers have been placing pressure on domestic coke pricing.

误会5:焦炭太贵

焦炭的价格高在某种程度上是对的,但是其价格在过去的5-8年已经显著的降低并且稳定了。与此同时,电价上涨并且一定程度上不可预测。高质量的欧洲焦炭以及规模化的焦炭供应商似乎一直在对美国国内的焦炭定价施加压力。

Myth 6: Coke is not going to be available in the future.

误会6:焦炭在未来将会消耗殆尽
According to David C. Ailor, president, American Coke and Coal Chemicals Institute (ACCCI), the present foundry coke demand is only 38.2% of the four domestic merchant member coke-producers’capacity. Like cupolas, domestic producers are fewer, but they are strategically suited for the long-term supply of the foundry industry. The merchant coke production capacity is 1.78 million tons, while the current domestic demand is about 0.8 million tons. The four merchant members producing foundry coke have taken several steps to continue as sustainable partners for U.S. metalcasters by:

根据David C. Ailor(美国焦料和煤化工研究所的主席),如今铸造用焦料的需求仅占美国国内四大焦料供应商产能的38.2%。虽然冲天炉的制造商很少,但它们在战略上适合铸造行业的长期供应。商品焦料的产能是178万吨,而如今,美国国内的需求是80万吨。生产铸造焦炭的四大供应商已经采取了几个步骤继续作为美国金属铸造厂的可持续合作伙伴:

Tailoring operations to meet the coke requirements/needs.
Organizing to engage regulatory agencies as the need arises.
Using many different coal blends.
Tailoring transportation/delivery infrastructure to meet customer needs.
Maintaining batteries to ensure long-term, reliable battery operation, performance and environmental compliance.

定制操作以满足焦炭要求/需求。

需要时聘请监管机构。

使用许多不同的煤混合物。

调整运输/交付基础设施以满足客户需求。

维护电池以确保长期,可靠的电池操作,性能和环境合规性。

What does the future hold?

未来该何去何从?
Cupolas continue to produce the majority of iron in the U.S., especially gray iron. The benefits of modern cupola melting systems include:

冲天炉将继续提供美国国内大部分的铁,特别是灰铁。现代的冲天炉熔化系统的优势包括:

The ability for in-stream desulfurization for ductile and compacted graphite iron.
Flexibility in alloying (charge or in-stream).
Improvements in heat reclamation and heat recovery.
Low labor cost.
Low scrap cost.
Flexibility in scrap material selection.

对延性和致密石墨铸铁进行流内脱硫的能力。

合金化(充电或插入)的灵活性。

改善热利用和热回收。

劳动力成本低。

废品成本低。

选择废料时的灵活性。

It is clear that“old”cupola technology will not work in the foreseeable future, especially as the U.S. sees continued competition globally. Many U.S. foundries still use methods and equipment that has been surpassed by competitors in Europe, Asia and south America. Without the necessary investment, U.S. cupola foundries could fall behind. But it is also clear, that those foundries who continually advance their cupola technologies and improve energy efficiency, will realize a strong, competitive and sustainable means of cupola melting, well into the future.

“旧”的冲天炉在可以预见的未来是不会行得通的,特别是在注重持续性的国际化竞争的美国。许多美国铸造公司还在使用已经被欧洲,亚洲和南美洲的竞争者所淘汰的设备。在没有必要的投资的前提下,美国的铸造公司可能会落后。但同样清楚的是,那些不断推进冲天炉技术和提高能源效率的铸造厂将实现一种强大,有竞争力和可持续的冲天炉熔化方式,以及未来。

This article is adapted from AFS Melting Methods & Material Division panel (18-122) with presentations by David Kasun and David Ailor, at the 2018 AFS Metalcasting Congress.

这篇文章被美国铸造协会的熔化方法&材料分部(18-122)所采用,并由David Kasun和David Ailor在2018年美国铸造协会的金属铸造大会上公开演讲。

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