Potential in utilising furnace off-gas at a ferrochrome smelter with gas engines

Murray, Ruan; Kock, J.A. de

doi:10.1109/icue.2015.7280265

Cited by 2 publications

(5 citation statements)

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“…Murray and De Kock [51] conducted a techno-economic evaluation for utilising furnace by-product gases as fuel for cogeneration at a South African ferrochrome smelter. The purpose was to determine the amount of electricity that could potentially be produced from the furnace by-product gases.…”

Section: Murray and De Kock [51] [52]mentioning

confidence: 99%

“…The purpose was to determine the amount of electricity that could potentially be produced from the furnace by-product gases. The total off-gas produced volume and its CV were used to determine the energy available for electricity generation [51].…”

Section: Murray and De Kock [51] [52]mentioning

confidence: 99%

“…A CV of 9,1 MJ/Nm 3 was indicated. With a 28 % overall plant efficiency, the potential generation was determined as 88 GWh per annum [51]. This translates into a 12 -14 % potential reduction in Eskom purchased electricity [52].…”

Section: Murray and De Kock [51] [52]mentioning

confidence: 99%

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Improving By-product Gas Utilisation in Steel Milling Operations

Mampuru

2019

SSRN Journal

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Iron and steel manufacturing are energy-intensive processes. Rising energy and operational costs have placed South African steel manufacturers under financial strain, while they struggle to remain afloat within an extremely competitive global market. Declining production and export figures, as well as increasing imports, have adversely affected the sustainability and profitability of the local market. It is, therefore, imperative for local manufacturers to implement operational change strategies without additional capital investment requirements in order to save energy and reduce costs.Hot-rolling processes of steel milling operations use reheating furnaces to elevate the temperature of the steel to a state of plastic deformation prior to rolling. The reheating furnaces combust fuel gases such as by-product gases or natural gas for thermal energy. They consume 70 % of the energy of the hot-rolling processes. By-product gases are combustible carriers of energy. Coke oven gas (COG) carries 18 % of the energy input of the coke production process. The energy content of COG was found to be competitive with natural gas and compatible for high-energy requirement applications, such as in reheating furnaces.The challenge arises in that the calorific value (CV) of COG fluctuates over time. These fluctuations prove problematic during the control of COG combustion processes as the air-fuel ratio needs to be adjusted accordingly. Furnace operators typically rely on a trial-and-error method for air-fuel ratio adjustments in response to the fluctuating calorific value of coke oven gas (CV of COG). This causes furnace temperature instabilities, energy inefficiencies and production losses. Additionally, COG has a high impurity content inherent from the coal. These impurities clog CV of COG analysing equipment.Several alternative tools are available to estimate the unavailable CV of COG; however, these tools do not account for the fluctuating nature of COG and only provide static estimated values.Based on these challenges, a need was identified to facilitate more stable operations of the furnace. The aim of this study entails the development of a new methodology to adjust the Improving by-product gas utilisation in steel milling operations ii air-fuel ratio according to the incoming CV of COG and the current furnace operating conditions. The historic behaviour of the furnace is used in the control strategy.To address the recurring events where CV of COG data is unavailable, a novel methodology is developed for a time-continuous estimation of CV of COG for stable process applications.A seven-step methodology was developed whereby an appropriate method can be selected for the determination of CV of COG, based on the available data and measuring equipment.Three methods are presented, with varying accuracy and consistency.Pilot studies were undertaken on a billet mill reheating furnace in order to validate the air-fuel ratio adjustment methodology. The results verified that the air-fuel adjustments were within 94 % -98 % accurate, res...

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Section: Murray and De Kock [51] [52]mentioning

confidence: 99%

Section: Murray and De Kock [51] [52]mentioning

confidence: 99%

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Improving By-product Gas Utilisation in Steel Milling Operations

Mampuru

2019

SSRN Journal

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“…1, if day i is a Weekday; 2, if day i is a Saturday; 3, if day i is a Sunday. (13) With the optimization variables and TOU periods defined, the overall system costs for the plant can be determined. The relevant costs under the MEGAFLEX tariff structure [52,53] are discussed in the following subsections.…”

Section: Epd Model Developmentmentioning

confidence: 99%

“…A similar study on the recovery of multiple waste heat streams in a refinery was done by [12], in which the procedures for designing the heat recovery network were presented in detail. Only preliminary studies on the application cogeneration systems utilizing furnace off-gasses in FeCr smelting plants have been reported [13]. According to the literature, a waste heat recovery system is most suitable for implementation in a FeCr smelting industry that rejects heat from the furnaces at medium to high temperatures via the off-gas extraction system [14,15,16].…”

Section: Introductionmentioning

confidence: 99%