Furnace Applications Research Articles

Enhancement of the conversion efficiency of selective emitter PERC solar cells by post-oxidation

Thermal oxidation has been widely adopted in the fabrication process of silicon solar cells. In this paper, we investigate the effect of thermal oxidation on the performance of passivated emitter and rear cells (PERC) after the diffusion process. It is found that the application of a diffusion furnace for post-oxidation results in the re-doping of phosphorus, which affects the minority carrier lifetime and implied Voc. In comparison, the use of an annealing furnace for post-oxidation brings an improvement of electrical properties of solar cells because of the gettering effect. Furthermore, the increase in thickness of the oxide layer mitigates the laser-induced damage during the laser doping process, which is beneficial for the enhancement of cell efficiency. Batch data shows that post-oxidation using an annealing furnace leads to an absolute efficiency improvement by 0.1%.

Melting Rate Determination of Mold Powders: Continuous Casting Process Versus Laboratory Conditions

In the continuous casting of steel, the melting behavior of mold powders influences the slag pool thickness and slab quality. Various methods have been implemented in laboratories to investigate this property, and in particular, melting rates are of interest. This study aimed to assess the existing methods with respect to their ability to determine melting rates under service-related conditions and to develop criteria for this purpose. These methods are divided into two groups, one of which can provide the necessary heat-transfer coefficient owing to the application of a preheated furnace or steel bath. The second condition is a sufficiently low mold powder layer thickness to allow for the desired mean heating rate. For the case study, the required heating rate is determined, and the maximum limit for this layer thickness is calculated from the conditions for Fourier and Biot numbers of varying test setups. Suitable test arrangements are also identified.

Preparation of infrared high radiation coatings from modified spinel NiFe2O4 and its energy saving applications

The NiFe spinel material itself has good thermal stability and emissivity and can be prepared as an infrared high radiation coating for energy saving applications in industrial high temperature furnace applications. In this study, Cr3+ and Cu2+ doped spinel NiFe2O4 was prepared by solid phase reaction at 1250 °C for 3 h and the microstructure and physicochemical properties of the powder and coating were characterised by XRD, SEM, EDS and IR radiometry. The effect of Cr3+ and Cu2+ doping on the infrared emissivity of spinel NiFe2O4 was investigated and energy saving assessment was carried out in a resistance furnace. The results show that the doping of Cr3+ and Cu2+ can significantly affect the emissivity of spinel powders in the 2.5–10 μm band, and the coatings prepared from the four powders have an emissivity of up to 0.95 in the 2.5–10 μm band. using this high temperature infrared radiation energy saving coating in a resistance furnace resulted in significant energy savings compared to no coating. The furnace was tested for energy saving by holding the furnace for 2 h and 5 h, and the energy saving efficiency reached 20.7% and 17.0% respectively. The coating was subjected to 10 thermal shock tests from room temperature to 700 °C. The coating bonded well and had good thermal shock resistance. Therefore, the coating has wide application prospects for energy saving applications in the field of industrial high temperature furnaces.

THOR®115 pipes in refinery furnaces

Summary Crude fired heater furnaces in refineries are adopting P5 and P9 steel grades, depending on temperature and feed characteristics. Process conditions, however, are characterised by temperatures up to 600°C, well above the conventional creep threshold, which eventually cause a considerable over-tempering of the material. At the same time, crudes being processed have become more‘critical’ in terms of sulphur content and TAN (total acid number). THOR®115 steel grade designed by Tenaris already showed very good corrosion resistance against oxidation and sulphidation. In the present work, THOR®115 and P9 have been analysed and compared, considering their static and creep resistance, together with oxidation and corrosion rate occurring on the external and internal surfaces. The output of the benchmark, resulting in a better performance of THOR®115 rather than P9, has been used to develop an economical comparison between the two materials and quantify the advantage to adopt THOR®115 in furnace applications.

Mechanical Evaluation and Minerals Phases Identification of Fine and Coarse Okelele Block Clay Composites for Furnace Lining Application

The suitability of fine and coarse Okelele clays as refractory raw materials for furnace lining application was investigated. The clay samples were crushed and pounded with a mortar and pestle to a particle size of 20 microns. 230 g each of fine clay was mixed with 50 mls of water inside a bowl and stirred thoroughly to form homogenous plastic paste. 10 g, 15 g, 25 g, 35 g and 45 g of coarse clay were added respectively to the 230 g of homogenous fine clay paste in different container. The fine and coarse clays composites weighing 240 g, 245 g, 255 g, 265 g and 275 g were respectively put in a mold of dimension 3 x 5 x 6 cm and air dried for 7 days. The samples were fired at temperature of 1200 oC for five hours using Carbolite Furnace. After cooling, the fine and coarse clay composites of 240 g and 245g were broken by the heat and composites blocks 255 g, 265g and 275g were hardened and remove for compressive test analysis. The fine and coarse clays were characterized using X-ray Diffractometer PW1830forminerals phases’ identification. The result of XRD shows that the clay was majorly composed of Quartz and Kaolinite with the traces of other minerals such as Smectile, Illite/Mica, Albite, Jarosite, Gypsum and Pyrite. The Kaolinite contains aluminum silicate (Al2O3·2SiO2) and Quartz has the silicon and oxygen atoms. The compressive strength test result judged the 275 g fire block of clays composite the best with the maximum force breaks of 7652 N with deflection of 3.734 mm and Young Modulus of 212 N/mm2 for the time to failure of 22 seconds. The results proved that Okelele clays are suitable as refractory material for furnace lining application.

Analysis of carbon footprint and reduction approach of magnesia production in China

China shares 13.15% and 69.23% of the global magnesite reserves and production respectively. Magnesia is an important connecting link between magnesite and refractory. It is approximately over 80% of magnesite industry that the carbon emitted from magnesia production is directly caused by carbonate decomposition and fossil fuel combustion. Therefore, the study of carbon footprint in magnesia production is valuable for carbon reduction. However, the researches on carbon reduction in magnesia production are rare. In this paper, the carbon footprint method is employed to quantitatively investigate the carbon reduction capacity in magnesia production under the influence of product structure, production process and equipment, and energy source structure. The results show that, for different magnesia, the carbon footprints are 3.937–4.804 kgCO2-eq/kg of fused magnesia, 2.151–3.064 kgCO2-eq/kg of sinter magnesia and 1.440–2.221 kgCO2-eq/kg of light calcinated magnesia at present, respectively. Moreover, for improvement of production process and equipment, the carbon footprint of flash calcinator is 0.489–1.218 kgCO2-eq/kg lower than that of reverberatory furnace for light calcinated magnesia. Similarly, the application of a high-power electricity arc furnace decreases the carbon footprint by 0.763–3.506 kgCO2-eq/kg of fused magnesia. Furthermore, for energy source replacement, the introduction of nuclear power has a carbon reduction capacity of 0.334–2.058 kgCO2-eq/kg-magnesia compared with coal-fired power. It will be 0.473–3.172 kgCO2-eq/kg-magnesia when hydrogen is employed as fuel compared with natural gas and producer gas. Finally, the combination of nuclear power, hydrogen and the carbon capture system will further pull the carbon footprint down to 0.244–0.767 kgCO2-eq/kg-magnesia.

Characteristics and combustion kinetics of fuel pellets composed of waste of polyethylene terephthalate and biomass

BACKGROUND AND OBJECTIVES: The needs of fuel pellets from varied feed stocks have opened up opportunities and challenges for pellets production from non-woody biomass. Wastes of plastic recycling and wood sawing contained a high potential for energy source and suited for pelletizing as a solid fuel. METHODS: The characteristics and combustion kinetics of fuel pellets made using a mixture of waste of polyethylene terephthalate and biomass (Tectona grandis Linn.f) with a polyethylene terephthalate to biomass ratio of 9:1. The investigation covered physico-chemical properties and their functional group analysis, heavy metal concentration and ionic leachability testing, and ash analysis. In this context, thermogravimetric analysis was used in an atmosphere of oxygen gas, over a temperature range of 50-800 °C and at different heating rates. The work ends with discussion of the kinetics study via three comparative evaluations and the feasibility of fuel pellets for energy utilization. FINDINGS: Pelletizing with this ratio (9:1) was present the durability of PET/biomass pellets, a uniform dimension, ease handling, storage, and transportation common as woody pellets. Some technical challenges such as low moisture content and high volatile matter content were feedstock dependent. The major characteristics were a combination of those from both the constituent materials. Functional groups of the pellets were contributed by terephthalate and lignocellulose. The addition of a small amount of biomass in pellets could improve their thermal decomposition behavior. The properties of the polyethylene terephthalate/biomass pellets indicated that were fit for combustion with a high heating value equal to 19.20 MJ/kg. Heavy metals and ionic contaminants were below the maximum limits of the standards because of the cleanliness of the raw materials. However, the minor effects of earth materials and a caustic soda detergent were resulted in the alteration of residue chemicals. The pellets had lower ignition, devolatilization, and burnout temperatures than the original polyethylene terephthalate waste; likewise, the peak and burnout temperatures shifted to a lower zone. The activation energy values obtained using the Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, and Starink models were similar and in the range 142–146 kJ/mol. CONCLUSION: These findings may provide crucial information on fuel pellets from blended polyethylene terephthalate/biomass to assist the design and operation of a co-combustion system with traditional solid fuels. Such modifications of fuel pellets suggest the possibility of operating in large-scale furnace applications and can further be upgraded to other fuels production via modern bioenergy conversion processes.

Technical Focus on DC-arc Furnace Application to Waste Stream Smelting

The application of DC-arc furnaces to the production of commodities such as ferrochrome, ilmenite and smelting of stainless-steel plant waste streams has progressed substantially over the last 30 years. The DC-arc furnace remains a suitable smelting unit for both consumer- & other steel plant waste products and will play a potentially significant role in the development of a circular economy. With increasing environmental legislation requirements and the associated treatment and disposal cost of consumer-, steel plant and smelter waste products, processing of these waste products is increasingly becoming more economically viable, yielding a strong business case and an overall positive environmental impact. The waste products such as spent catalysts, mill scales, steel fines and bag filter dusts often contain valuable elements and various processing routes exist to treat these waste products. The DC-arc furnace is a well-suited furnace application due to its ability to process fine materials and yield products with a higher economical value, without the need of feed-material agglomeration or high-end reductants. Inherently, the process behaviour of these furnaces is dynamic where strict metallurgical process control principles must be applied by the process team to keep the metallurgical condition of the furnace within its operational boundaries. In addition, a number of furnace design aspects further influence the control measures available to the team. This paper will focus on the application of DC-arc furnaces for fine waste stream processing, focussing on a stainless-steel waste sludge case study, with a technical focus on the inherent characteristics and design requirements of these furnaces, required to achieve a stable furnace operation.

Parameter tracking of time-varying Hammerstein-Wiener systems

A two-stage identification algorithm is introduced for tracking the parameters in time-varying Hammerstein-Wiener systems. The Kalman filtering algorithm and parameter separation technique are employed in the proposed algorithm. The convergence analysis of this two-stage algorithm is provided. It is shown that the proposed algorithm can guarantee the boundedness of the parameter estimation error. Four simulation examples, including a practical system application of electric arc furnace, have been employed to validate the effectiveness of the proposed approaches, for a range of simulated time-varying characteristics.

Evaluation on the Microstructure and Durability of High-Strength Concrete Containing Electric Arc Furnace Oxidizing Slag.

The application of electric arc furnace oxidizing slag (EAS) in high strength concrete (HSC) as the cementitious material is investigated in this study. The microstructure and mechanical properties of HSC with four different replacement ratios of EAS were evaluated and HSC with two replacement ratios of ground granulated blast furnace slag (GBS) was used for performance comparison. The results show that the HSC with EAS replacement ratios smaller than 15% undergo similar hydration processes and result in a similar final product when compared with those of NC-NN. Increases in EAS replacement ratio cause a reduction in Ca(OH)2 content; this, in turn, leads to an increase in porosity and a reduction in compressive strength. In terms of shrinkage behavior under free conditions, mixtures with increasing replacement ratios of cementitious materials saw increasing shrinkage, with the HSC containing EAS being similar to the other specimens. The mixtures containing EAS saw a quite gradual decrease in their freezing and thawing resistance properties as the number of freeze–thaw cycles they underwent increased. However, the efficacy of HSC with less than 15% of EAS is similar to GBS; hence, EAS could replace cement in concrete for certain applications, which would lead to more environmental benefits.

Preparation of high-strength biochar composite briquette for blast furnace ironmaking

In this research, using iron-oxide fines (average size: 2.5 μm) and biochar fines (average size: 50.0 μm), the biochar composite briquette (BCB) for blast furnace (BF) application was prepared by cold briquetting followed by heat treatment. The preparing conditions were optimized regarding its cold crushing strength. Anti-pulverization capability, reaction development, and structure evolution of the optimally-designed BCB under simulated BF conditions were then examined. Results of optimizing BCB preparation conditions showed that a heating temperature of 1073 K was optimal for preparing the BCB. The optimally-designed BCB contained 11.10 wt.% carbon, 72.21 wt.% Fe3O4, 11.25 wt.% FeO, and 0.77 wt.% Fe, 6.44 wt.% gangue, and had a cold crushing strength of 1800 N/briquette. Results of BCB behavior under simulated BF conditions showed that the cold crushing strength after partial reaction of the BCB ranged from 1500 N/briquette to 5500 N/briquette and its maximum volume shrinkage degree was 0.45. The high anti-pulverization capability of the BCB was supported by the slag matrix or the iron network. Under the simulated BF conditions, the BCB underwent five stages of reduction by atmosphere, partial self-reduction and reduction by atmosphere, full self-reduction, partial self-reduction and gasification by atmosphere, and gasification by atmosphere. It is inferred from the experimental findings that, by charging the BCB in BF, an increase of top gas utilization efficiency could be realized, and a favorable influence on lowering the temperature level of the thermal reserve zone could be obtained.

SHS Processing of cyclone ferrosilicium dust

This paper offers a review of waste disposal techniques for disposing of dust generated by ferrosilicium industry. The paper examines the possibility of nitriding cyclone ferrosilicium dust through application of a high-pressure infiltration combustion process. The authors describe the key regularities of the ferrosilicium nitride SH-synthesis and demonstrate the potential applicability of the new technique. The findings show that the high-grade dusts resultant from ferrosilicium crushing and screening operations and identified as FeSi65 and FeSi75 consist of iron and silicon disilicides, whereas the dust coming from a 45 % alloy consists of FeSi2 and FeSi. Interaction of the initial alloys with nitrogen in a high-pressure combustion mode results in the generation of high-nitrogen material with the β-phase of silicon nitride at the basis. Such material can be used as unmolded refractory material for application in blast furnaces. Or it can be used to produce nitrogen containing steels, such as transformer steel. Thus, the dust grade PUD-75 would be optimum for application in refractories, and the dust grade PUD-65 — as an alloying component. The paper demonstrates that the composition of the cyclone ferrosilicium dust combustion products can be changed by changing the nitrogen pressure and the dispersity of the burden. Silicon nitride constitutes the main component in the composition of the combustion products (60–85%). It will be iron that will serve as a binder in this composite at the highest nitrogen saturation degree, whereas in the case of a lower nitrogen saturation degree it will iron silicides. It was found that nitrogen is absorbed in two stages during layer-by-layer combustion of ferrosilicium alloys. Passing of the combustion front is followed by the process of bulk post-reaction, during which the share of absorbed nitrogen can increase by 30%. This phenomenon explains why there exists no dependence between the concentration of nitrogen in the combustion products and the applied pressure.

Procedure and installation for processing iron-containing metallurgical waste

The review and the analyses of publications in the domain of recycling crushed iron containing metallurgical waste, including dust, slam, etc., has made it possible to determine the generated tendency of their processing. As this waste contains a significant amount of harmful admixtures, their recycling in the basic manufacture process results in accumulation of harmful substances that negatively affect the operation of metallurgical units. Therefore their processing in insulated installations is strongly recommended nowadays. The first installations had high capital and current expenditures. Creation of rotary-hearth kilns has allowed to lower essentially current expenditures, however capital expenditures remaining high. Besides the rise in prices for heating gas under the conditions of Ukraine made the installations unprofitable. That is why there arises a problem of cardinal reduction of such installations employment as well as current expenditures for their maintenance. The executed investigations have made it possible to develop both the procedure and the installation realizing this procedure. So, the principal differences of the given procedure from the known ones are simultaneous crushing of the charge to micron level, the use of bichofit МgCl2·6Н2О as the connector and the flux, preliminary consolidation of the charge material in the runners and application of a special multizonal induction furnace for metallic coating. The set of the measures realized on the given procedure, raises the degree of metallic coating of iron from 90%, realized according to the known procedure, up to 99,6% and reduces the restoration cycle by 4-8 times, i. e. from 1-2 h. to 0,25 h. It also allows to improve ecological environment and to reduce the total metal loss by 3-5%. The installation has been developed as a mobile variant for which the equipment is arranged as separate units fixed on welded frames. The installation has been developed with regard to the equipment fabricated in Ukraine, and does not depend on the deliveries of the component parts and the connectives from abroad; it considerably reducing its cost

Manufacturing and Mechanical Characterization of Fly-Ash-Reinforced Materials for Furnace Lining Applications

Fly ash is the major wastes generated during the combustion of coal in thermal power plants. More than 110 million tons of fly ash produced in India annually. It leads to a significant disposal problem. An attempt has been made by numerous researchers to integrate the fly ash in the industry sector. The key applications include the manufacturing of bricks, production of cement, soil amelioration, mine backfilling, etc. Nevertheless, the refractory bricks for furnace lining are mainly formed from iron and steel, which are imported and are very expensive. Hence, to tackle this issue, the current study is focused on the synthesis of fly-ash-rich brick for high-temperature applications. In this investigation, fly ash material combined with minor additives such as granite powder, alite cement, and black sand were manufactured. The pellets of these materials with a varying additive percentage from 5 to 30% were prepared using hydraulic pressure. The heat-treated pellets were physically and mechanically characterized to ensure the brick properties suitable for furnace lining applications. Surface morphology of raw materials and particle–particle interaction after palletization were evaluated using scanning electron microscopy. Energy Dispersive x-Ray Analysis and x-ray diffraction technique were conducted to detect elemental analysis and phase evaluation of raw materials and fly-ash-rich brick after heat treatment. Microhardness of the samples was determined using a Vickers hardness tester. It is found that the formation of various complex compounds with respect to constituent composition, and pellet formation temperature has a great influence on the variation in hardness.

Carbonization using an Improved Natural Draft Retort Reactor in India: Comparison between the performance of two woody biomasses, Prosopis juliflora and Casuarina equisetifolia

Charcoal is an impure form of carbon, containing some organic matter and ash. It is derived from wood by removing the volatile organic matter and the moisture, through carbonization. Charcoal is widely used as a fuel for domestic and industrial heating applications in developing and underdeveloped countries. This research article describes the carbonization of two different woody biomass species – Prosopis Juliflora Wood (PJW) and Casuarina Equisetifolia Wood (CEW) – at different final carbonization temperatures, from 400 °C to 700 °C, through an improved natural draft charcoal retort (INDCR) reactor. The maximum yield of charcoal at 400 °C and of fixed carbon content at 700 °C, obtained from Casuarina wood, are 41.15wt% and 87.78wt%, respectively. Further, the combustion reactivity of the produced char samples was measured through thermogravimetric analysis. The results indicate that the char with higher volatile matter has a maximum burnout efficiency and charcoal reactivity. The PJW and CEW char activation energy increased from 68.28 KJ/mol to 79.32 KJ/mol and from 53.97 KJ/mol to 62.03 KJ/mol, respectively with the increment of carbonization temperature from 400 °C to 700 °C. The kinetic study of charcoal combustion concludes that PJW and CEW charcoal can be widely used for blast furnace and barbeque applications.

High temperature air combustion (HiTAC): How it all started for applications in industrial furnaces and future prospects

Over the last three decades, High Temperature Air Combustion (HiTAC) has contributed much to become the leading technology for fossil fuel conversion in industrial furnaces. Since then several other researchers have termed it MILD, Flameless or Distributed combustion and they all show much similarities with the HiTAC. This review underlines that the technology was developed through a cooperation between the Japanese government (NEDO, METI) and Nippon Furnace Kogyo (Japan) as well as the key role played by the University of Maryland (USA) and the International Flame Research Foundation (IFRF – the Netherlands). Tokyo Gas (Japan) also provided an important role, although indirect, in the development. The HiTAC technology development was revolutionary with simultaneous demonstration on significant energy savings (some 25%), reduced equipment size, much reduced pollution (50%, including CO2), and noise in industrial furnaces. The technology is now widely used in many modern industrial furnaces worldwide. Per METI some 39,000 HiTAC burners in 7867 industrial furnaces were installed worldwide that showed fuel savings of 1721 billion liters of crude oil/year. It is estimated that 68 Billion liters/year of fuel oil savings and 180 Billion tons/year of CO2 reduction will be realized by 2030 through the use of HiTAC technology in industrial furnaces. This revolutionary technology continues to be adapted by many countries worldwide. The authors provide a brief review on the HiTAC technology development and give their views on its potential applications on the horizon that will also contribute to cleaner and efficient combustion in many other applications, besides industrial furnaces. These include high intensity gas turbine combustion, portable power, and engines. We do not discuss MILD and Flameless combustion as they have been reviewed previously with proliferation of numerous scientific publications available in the literature on the subject.

Research and Application of the Optimal Furnace and Casting Schedule for Long Steel Products in Iron and Steel Enterprises

This paper designs and implements an automatic grouping method for cascade production planning department and steelmaking plant in organizational production. The original data of group casting in this system is downloaded from SAP system to MES system by production planning department, and then decomposed into batch planning. Production plan data arrives in the database, After automatic calculation, judgment and other processing, the system triggers the next step of furnace group pouring operation. The whole process can timely and accurately form furnace number and pouring number data, and has traceability and data coherence. Triggering the next process execution improves the efficiency of information flow transmission. It solves the problem that the number of stoves and pouring times are not timely, rigorous, traceability and coherence are not enough in the process of organizing production in steelmaking plants.

Application of automatic control furnace for combustion of biomass briquette fuel for tobacco curing

Applying biomass energy for curing flue-cured/Virginia tobacco heating is the best way to realize green tobacco production. Aiming to satisfy the heating demand for flue-cured tobacco curing, a new heating device that uses biomass briquettes as fuel for curing tobacco is adopted the first time, which was developed using modern mature electromechanical and computer technology. The new device consists of automatic feeding, ash cleaning, ventilation, and ignition systems governed by an intelligent tobacco-curing controller designed for specific curing characteristics. The results of experiments conducted with an original direct combustion coal furnace, bulk curing barn, and controlled coal-fired heating indicated that the heat supply of the new device could satisfy the heat demand during the tobacco curing process, with a good performance-controlling difference of ?0.5?C between the actual and target dry-bulb temperature in the barn. With its unattended heating management and use of fully burning fuel, the new device sharply decreased the cost of manual operation and tobacco leaves required per kilogram compared to a coal furnace. Considering the shape of its structure, the new device could be used to heat homes or small-scale boilers if the chip procedure of the controller is altered.

PENINGKATAN MUTU DAN KUANTITAS PRODUKSI GERABAH PADA INDUSTRI PEMBUATAN GERABAH DI MALANG JAWA TIMUR

The aims of this activity is the application of furnace and pottery design training to help improve the quality and quantity pottery products. The methods of implementing this activity is the implementation team analyzes the problems of the partner team (Mr. Suhartoko). The results of the analysis revealed that Mr. Suhartoko’s pottery business still used wood-burning stoves, ability to design pottery motifs (grading techniques) that are underdeveloped and marketing management that has not been managed optimally. Based on the results of discussions and request of partner teams. Then the design is carried out for the manufacture of controlled system furnaces. Training preparation to design pottery motifs (grading techniques) and marketing workshops. At the end of the activity the community partnership program was facilitated and evaluated. The results of the community partnership program activities are an increase in the quality of pottery products after using a controlled furnace system. While still using the manual furnace, the pottery produced is only made of clay after using a controlled furnace system. The pottery produced is capable of producing pottery made of ceramics. In quantity, there was an increase in the production of pottery, which were from 8-10 pottery each time it processed to 22-24 pottery. While, in terms of design, pottery motifs have started to develop and are able to selling high. The indicator is that the selling price of pottery products increases from 10 thousand rupiahs to 15 thousand rupiahs for each pottery product to 100 thousand rupiahs to 150 thousand rupiahs for each pottery product. At this time, Pottery product marketing has also begun to penetrate the gallery, hotel and café.

Evaluating the Risk of Corona Discharge in Superalloy Vacuum Induction Melting Furnace Applications

Corona discharge, or gas breakdown, is undesired in superalloy vacuum induction melting (VIM) applications as it can damage insulation, produce ozone and subsequently oxidize and contaminate the melt. Gas breakdown also introduces uncontrolled variations to the casting process and increases the risk of needing to scrap the end product. To reduce the risk of corona, a rule-of-thumb of 150 to 1000 micron (150 mTorr to 1 Torr) was developed in the past as a No-Go Pressure Zone. Operating within this zone has been observed to create an unwanted, readily ionizable environment. An analytical model is developed within this work to evaluate the historical rule-of-thumb. The analytical model incorporates the following elements: Paschen’s law, gas compressibility, gas and insulation permittivity, and electric field non-uniformity. The model is then applied to a sampling of VIM furnace designs to evaluate the shifts of the No-Go Pressure Zone due to variations in configuration and other operating conditions. In the end, the objective is to improve VIM furnace design and operation to reduce the risk of corona discharge—thereby improving the casting process, practice of alloy melting and quality of the end product.