【Major Chemical Equipment in a Major Country】063 – The First Domestic N08810 (nickel-based alloy) Cold Hydrogenation Reactor
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The past decade has been a period of rapid development in China’s chemical industry, marked by the emergence of many new processes, products, and equipment. There has also been significant progress in China’s chemical processing equipment, which has contributed to the swift advancement of the petrochemical sector. Here, we have compiled some of the achievements and breakthroughs made by Chinese equipment manufacturers in terms of larger-scale production and greater use of domestic equipment. We invite everyone to share their insights and discuss these topics together; let’s cheer for Made in China and support the development of chemical processing equipment! *********************************** On the afternoon of September 9, 2021, the first domestically produced N08810 (nickel-based alloy) cold hydrogenation reactor for Qinghai Asia Silicon’s polycrystalline silicon production project with an annual capacity of 30,000 tons, which was manufactured by Lansi, was completed, shipped, and put into use. This cold hydrogenation reactor is a core equipment for the first phase of the Qinghai polysilicon project, and it represents the first set of domestically produced thick-walled NO8810 nickel-based alloy equipment of its kind. The completion of this project has broken foreign companies’ monopoly on the materials for such devices, further enhanced Lansi’s capabilities and standards in specialized manufacturing, and led to new breakthroughs in China’s new energy sectors such as polysilicon. It is understood that relying on its strong technical foundation, advanced manufacturing processes, and comprehensive quality assurance system, Lansi Group collaborated with Qinghai Asia Silicon Industry to develop the first domestically produced N08810 material cold hydrogenation reactor, thereby contributing to the achievement of domestic substitution. By scientifically formulating process plans, strictly controlling quality during production, and carefully organizing manufacturing processes, Lansi has successfully overcome more than 10 technical challenges, including the special properties of thick-walled NO8810 nickel-based materials, the need to control the levels of carbon, aluminum, and titanium elements, the tendency for heat cracks during welding, the high precision required for assembling internal components, and the difficulties associated with overall heat treatment. After 4 months of intensive production, the first product was successfully completed, and Lanshi was awarded a plaque by Asia Silicon Industry stating \"Craftsmanship creates vital national assets; let’s work together to promote domestic substitution.\"
More people are welcome to participate in the relevant discussions. Click on the blue link to access it: The 【Haichuan Equipment Guessing Game】 series is being updated continuously in 2022; all Haichuan community members are invited to join actively! https://bbs.hcbbs.com/thread-2079686-1-1.html (Source: Huahai Chuanliu – Haichuan Chemical Industry Forum) Summary post on the series 【Major Equipment in the Chemical Equipment Industry】 https://bbs.hcbbs.com/thread-3312079-1-1.html (Source: Huahai Chuanliu – Haichuan Chemical Industry Forum) Summary post discussing the components of cracking furnace equipment for 【Ethylene Cracking】 https://bbs.hcbbs.com/thread-3308724-1-1.html (Source: Huahai Chuanliu – Haichuan Chemical Industry Forum)
The final stabilization heat treatment was successful in one attempt; the main welds passed the RT and PT re-inspections, and all performance parameters met the design specifications. This demonstrates that Lanshi Group has mastered the welding techniques as well as the overall stabilization heat treatment processes for large-scale equipment made of thick-walled N08810 nickel-based material.
【Major Chemical Equipment】076 – Domestic N08810 nickel-based alloy heat exchangers https://bbs.hcbbs.com/thread-3319319-1-1.html (Source: Huahai Chuanliu – Haichuan Chemical Forum Website)
Contributing to the \"dual carbon\" goals! Taigang launches key materials for the photovoltaic industry in China. On September 9, the delivery ceremony for the first domestic N08810-grade cold hydrogenation reactor produced by Asia Silicon Industry was held at Lanzhou Lanshi Heavy Equipment Co., Ltd. The core material of this device – the extra-thick N08810 nickel-based alloy steel plate – is supplied by Taiyuan Iron and Steel Company. This supply marks Taigang’s first domestic success in replacing imported materials that are crucial in the photovoltaic polysilicon industry, thereby using these materials to support the development of a green economy and advance the goals related to carbon reduction. Against the backdrop of advancing the \"dual carbon\" strategic goals, clean and low-carbon new energy sources, represented by photovoltaic power, have become the driving force behind the transformation of the energy industry. With **policy support, China’s photovoltaic industry has maintained a leading position globally for many years in terms of technical capabilities, power generation volume, and installed capacity, offering broad market prospects. Polysilicon is the main raw material for solar panels in the photovoltaic industry, and the core equipment used in its production – the cold hydrogenation reactor – is typically manufactured from thick plates of N08810 nickel-based alloy. This material requires high performance in terms of resistance to high temperatures and pressures, high wear, and severe corrosion; it has thus had to be imported, becoming a critical bottleneck in polysilicon production. In 2018, after identifying this need during market visits, the marketing staff at Taiyuan Iron and Steel Company actively collaborated with the production and technical departments to conduct repeated discussions with key players in the polysilicon industry, as well as design institutes and equipment manufacturers, in order to work together on solving the related problems through experimentation. Leveraging Taiyuan Iron and Steel’s strong technical R&D capabilities, the order for the extra-thick N08810 nickel-based alloy plates required for China’s first domestic cold hydrogenation reactor was successfully placed, and the delivery of this order was completed on schedule and to high quality. Taigang will continue to make active efforts in the development and improvement of nickel-based alloy thick plates, striving to achieve a complete replacement of imported materials, and contribute to the development of China’s new energy industry as well as the achievement of the \"dual carbon\" goals.
The cold hydrogenation technology transformation involves converting silicon tetrachloride, a by-product generated during polysilicon production, into trichlorosilane, an intermediate material required for polysilicon production, thereby achieving a closed-loop circulation of materials. This process not only completely solves the problem of environmental pollution caused by exhaust gases from polysilicon production but also enables the recycling of by-products such as silicon tetrachloride, **reducing production costs. A cold hydrogenation reactor is the core equipment for the cold hydrogenation stage of a 5,000-ton/year polysilicon project at a photovoltaic materials company in Sichuan. There are two units of this equipment, with a vertical fixed structure. The equipment specifications are DN2000×75×18055 mm, and the main material used for the equipment is UNS No 8810. The total weight of the equipment is 71,880 kg, and it requires overall heat treatment after being manufactured.
When UNS No. 8810 is welded, impurities such as S and Si segregate in the weld metal; S and Ni form a low-melting-point eutectic of Ni-NiS. During the solidification of the weld metal, this low-melting-point eutectic forms a liquid film between the grain boundaries, which leads to intergranular cracks under the effect of welding stresses. During the welding process, elements such as Si and O form a brittle silicate film at the grain boundaries, which leads to the formation of high-temperature, low-plasticity cracks during or after the solidification of the weld metal in high-temperature areas. Therefore, S and Si are the most harmful elements in No8810. No8810 has poor thermal conductivity, especially when welding thick-walled materials. The welding heat does not dissipate easily, which can lead to overheating. This results in larger grain sizes, an increase in the thickness of intergranular layers, and a reduction in the intergranular bonding strength. It also prolongs the time during which the weld metal is in a liquid-solid state, thereby facilitating the formation of thermal cracks.
The Ni content ranges from 30.0% to 35.0%; the high-Ni matrix enables the dissolution of various corrosion-resistant elements. As a result, during welding, the fluidity of the molten metal is poor, and a refractory oxide film (NiO) tends to form on the surface, leading to poor penetration and the formation of impurities in the weld. Therefore, during the selection of welding materials and the welding process, it is necessary to strictly control the levels of impurities such as C, S, and P, and to ensure that the surfaces of the welding materials and weld grooves are clean. Selection of welding method. Since all the equipment heads in this project are made from plates with a thickness of 48 mm, and the cylinders are made from plates with a thickness of 75 mm, these constitute thick-walled structural components. Additionally, taking into account the welding characteristics of alloy No. 8810, the TIG welding process is used during welding. Welding materials determined. Based on the chemical composition of the material and the operating environment of the equipment, the welding wire ERNiCr-3φ2.4mm produced by the company is selected as the welding material. 1.3 Design of groove shape. Due to the poor fluidity of the liquid metal in this alloy, if the groove shape is not appropriate, lack of fusion will occur. Therefore, to ensure good weld fusion at the joint, the bevel angle should be increased appropriately, and the thickness of the root margin should be reduced; especially for materials with a thickness of 48 mm, a double U-bevel should be used.