Coke Oven Gas, its Characteristics and Safety Requirements...

Coke Oven Gas, its Characteristics and Safety Requirements Coke oven gas (CO gas)  is a byproduct gas produced during the production of metallurgical coke in a byproduct coke oven battery, where metallurgical coal is carbonized by heating it in absence of air. During carbonization the volatile matter in the coal is vaporized and driven off. This volatile matter leaves the coke oven chambers as hot, raw coke oven gas. After leaving the coke oven chambers, the raw coke oven gas is cooled which results in a liquid condensate stream and a gas stream. These two streams are processed  in the byproduct plant to recover byproduct coal chemicals and to condition the raw coke oven gas so that it can be used as a fuel gas. The main emphasis of a modern  byproduct plant is to treat the raw coke oven gas sufficiently so that it can be used as a clean, environmentally friendly fuel. Raw coke oven gas after treatment in the byproduct plant is called clean coke oven gas or simply coke oven gas. The evolved coke oven gas leaves the coke oven chambers at high temperatures approaching 1100 deg C. This hot gas is immediately quenched by direct contact with a spray of aqueous liquor (flushing liquor). The resulting cooled gas is water saturated and has a temperature of around 80 deg C. This gas is collected in the coke oven battery gas collecting main. From the gas collecting main the raw coke oven gas flows into the suction main. The amount of flushing liquor sprayed into the hot gas leaving the oven chambers is far more than is required for cooling, and the remaining unevaporated flushing liquor provides a liquid stream in the gas collecting main that serves to flush away...

Hazard, Hazid, Hazan and Hazop – part of Safety and Risk Management...

Hazard, Hazid, Hazan and Hazop – part of Safety and Risk Management Hazard, Hazid (hazard identification), Hazan (hazard analysis), and Hazop (hazard and operability studies) are important safety and risk management techniques in the steel industry (Fig 1).  Fig 1 Safety and risk management techniques Hazards Hazard is defined as ‘a condition, an event, or a circumstance that can lead to or contribute to an unplanned or undesirable event’. Hazard is a potential cause to generate a disaster. It has got the potential to cause (i) serious harm to the individual or the environment, (ii) harm, the severity of which depends on the extent and frequency of exposure to the hazard, and (iii) harm that does not usually occur, or is not usually detectable until a significant time (years) after exposure to the known hazard. Any activity, procedure, plant, process, substance, situation or other circumstance that has the potential to cause harm constitutes a hazard. Hazards are logically classified in the same way as the disaster events are classified.  Since a hazard exists because it may result into a disaster, it is usually viewed as natural based, human systems based, or conflict based.  Not every hazard results into a disaster, but every disaster is the result of a hazardous condition, whether or not that condition was recognized in advance of the event. Hazards are normally not identical, not uniform, not exclusive, and not transposable. They are not uniform in their range of occurrence, impacts, or timelines. They have got non identical pattern of development. Hence each hazard is to be understood in the context of its time and place. One hazard generally does not substitute for another, at least at the higher level of classification.  Since hazards are not the same, each hazard is to...

The Process of Blowing-in of a Blast Furnace Apr29

The Process of Blowing-in of a Blast Furnace...

The Process of Blowing-in of a Blast Furnace  The process of starting a blast furnace after its construction or after its relining is called blowing-in. The blowing-in process is carried out in several steps (Fig 1) which consist of (i) drying out the lining, (ii) filling of the blast furnace with a specially arranged high coke blow-in furnace charge, (iii) igniting of the coke or lighting of the blast furnace, and (iv) gradually increasing the hot blast (wind rate) with frequent castings to ensure the raising of temperature of the blast furnace hearth. During the period of blow-in, the burden ratio (ratio of the ore to coke) is adjusted according to a predetermined schedule until the normal operation of the blast furnace is achieved and the blast furnace starts producing the normal  quality of the hot metal. Fig 1 Steps in the blowing-in process of a blast furnace  Newly constructed or relined blast furnace is to be carefully dried before the coke is ignited. It is  because the large amount of water contained in the slurry used for refractory brick laying and the water absorbed by the refractory brick work is to be driven off as much as possible for avoiding  extreme thermal shock. There is sufficient data available that blowing-in of a blast furnace can cause damage to the refractory lining even when it has been properly dried. Furthermore, if the water from these sources is not removed from the blast furnace before it is put into operation, it absorbs heat more than that provided for the blow-in charge and hence prevents the hearth from reaching the desired temperature. In such cases, hot metal and liquid slag entering the hearth can freeze there and in such case it becomes impossible to remove them...

Blast Furnace Gas, its Characteristics and Safety Requirements...

Blast Furnace Gas, its Characteristics and Safety Requirements Blast furnace gas (BF gas)  is a byproduct gas produced during the production of hot metal (liquid iron) in a blast furnace, where iron ore is reduced with coke to produce hot metal. The blast furnace gas which comes out from the top of the blast furnace is at a high pressure (usually 1.5 atm to 2.5 atm in modern blast furnaces) and normally at a temperature of around 100 deg C to 150 deg C. When there are abnormalities in the burden descent then this temperature can be higher. A typical blast furnace produces 1200 – 2000 N cum of BF gas per ton of hot metal. The energy content of this gas may equal to an energy export of around 1.2 M cal/ton (5GJ/ton) of hot metal, or approximately 30 % of the gross energy consumption in the blast furnace. This energy content can be utilized by recovering, cleaning, and storing the BF gas and using it as a fuel gas in the steel plant or in the boilers for the production of steam for the electricity generation. The calorific value of the BF gas varies but is usually low (between 650 kcal/N cum to 900 kcal/N cum and depends on the CO concentration). Therefore, BF gas is often enriched by coke oven gas or natural gas prior to use. In cases where the blast furnace is fitted with a two bell charging system, approximately 1.5 % of the BF gas is lost every time the furnace is charged. Most of this gas can be recovered by discharging the high pressure gas between the two bells into the low pressure side of the gas collection system just prior to opening the top bell for charging....

Safety Inspections and Safety Audits...

Safety Inspections and Safety Audits A sound organization must check its safety practices very carefully. The debits of possible loss or injury situations should balance against the credits of adequate safeguards. Safety audits and safety inspections are the tools which an organization use for its preparedness towards safety (Fig 1). Safety audit involves systematically going through the workplace to evaluate safety programs and practices within the organization while safety inspection involves systematically going through the workplace to look for safety hazards or lapses in safety practices. Both are important components of a workplace safety plan. They are frequently used interchangeably though they are not the same. Fig 1 Safety tools A safety audit is a structured evaluation of the application and efficiency of the safety policy, safety programs,  and safety systems of the organization. It is also a control of the compliance with the regulatory regulations and a clear standard, which may be a national standard or organizational internal standard. An audit is a widely used instrument and an important tool to improve safety. It is the process of verification that the safety programs are working. Broadly defined, an audit is a systematic review of operations and practices to ensure that relevant requirements are met.  Safety audit apply many methodologies to mitigate safety risks within the organization. Safety audits evaluate all aspects of the safety programs with special emphasis on the quality as well as the quantity of safety activities at every level. Safety audits are a managerial or a corporate activity. Safety inspection, on the other hand, is defined as that monitoring function which is conducted in an organization to identify, locate and report existing and potential hazards that could cause accidents in the work place. Safety inspections frequently reveal potential causes of...