Recovery of Ammonia during Production of Coke from Coking Coal Jan26

Recovery of Ammonia during Production of Coke from Coking Coal...

Recovery of Ammonia during Production of Coke from Coking Coal Ammonia (NH3) is a by-product produced during the production of coke from coking coal in the by-product coke ovens. It is a constituent of the coke oven gas (COG) leaving the coke ovens, with a typical concentration in raw COG of 6 grams per normal cubic meters (g/N cum). The solubility of NH3 in water leads to its presence in the flushing liquor of coke oven battery (COB) with a typical concentration of 5 grams per litre (g/l) to 6 g/l of total NH3. Therefore, due to the net production of flushing liquor in the COB, also sometimes being referred to as excess flushing liquor, there arises a liquid stream as well as a gas stream from which NH3 is required to be removed. The quantity of excess liquor is around 12 % of the dry coal throughput, which depends on the coal moisture content. Removal of NH3 from the gas stream is a universal feature of a coke oven and by-product plant. This is because NH3, in the presence of the other COG contaminants hydrogen cyanide (HCN), hydrogen sulphide (H2S), oxygen (O2), and water, is extremely corrosive to pipelines made of carbon steel. Also, when ammonia is uncontrollably burnt in any combustion chamber, it forms nitrogen oxides (NOx) which causes air pollution. Hence, removal of NH3 from COG and liquid stream is required to be also done due to environmental reasons. The primary NH3 handling process in the coke oven and by-product plant deals with the removal and disposal of the NH3 present in the COG. However, NH3 recovery systems often include facilities to handle the NH3 arising in the excess flushing liquor. For proper understanding of how these facilities are incorporated into...

Coal Tar and its Distillation Processes Dec26

Coal Tar and its Distillation Processes...

Coal Tar and its Distillation Processes Coal tar, also known as crude tar, is the by-product generated during the high temperature carbonizing of coking coal for the production of the metallurgical coke in the by-product coke ovens. It is a black, viscous, sometimes semi-solid, fluid of peculiar smell, which is condensed together with aqueous ‘gas-liquor’ (ammoniacal liquor), when the volatile products of the carbonization of coking coal are cooled down. It is acidic in nature and is water insoluble. It is composed primarily of a complex mixture of condensed-ring aromatic hydrocarbons. It can contain phenolic compounds, aromatic nitrogen (N2) bases and their alkyl derivatives, and paraffinic and olefinic hydrocarbons. In the process of coal carbonization the constituents of the tar escape from the coke ovens in the form of vapour, with a little solid free carbon (C) in an extremely finely divided state. The tar is precipitated in the hydraulic main, in the condensers, and scrubbers etc., in a liquid state, at the same time as the ammoniacal liquor is formed. The tar formed in the hydraulic main is, of course, poorer in the more volatile products than that formed in the condensers and scrubbers, and is consequently much thicker than the latter. The normal yield of coal tar during the coal carbonizing process is around 4 %. Coal tar has a specific gravity normally in the range of 1.12 to 1.20, but exceptionally it can go upto 1.25. It depends on the temperature of carbonization. The lower specific gravity tars are generally produced when low carbonization temperatures are used. Viscosity of tar affected similarly. The heavier tars contain lesser benzol than the lighter tars, and more fixed carbon. The nature of the raw material and the temperature of carbonization affect the chemical composition,...

Understanding Coke Making in Byproduct Coke Oven Battery Mar09

Understanding Coke Making in Byproduct Coke Oven Battery...

Understanding Coke Making in Byproduct Coke Oven Battery  Coke is one of the basic materials used in blast furnaces for the conversion of iron ore into hot metal (liquid iron), most of which is subsequently processed into steel. The major portion of coke produced is used for the production of hot metal. Coke is also used by a number of other industries, namely iron foundries, nonferrous smelters, and chemical plants. It is also used in steel making as a carburizing material. Coke and coke by-products, including coke oven gas, are produced by the pyrolysis (heating in the absence of air) of suitable grades of coal. The process also includes the processing of coke oven gas to remove tar,  ammonia (usually recovered as ammonium sulphate), phenol, naphthalene, light oil, and sulphl, and sulfs under links n of coal)  period.e doorg nitrogen gas is used for the production of steam and then power.ur before the gas is used as fuel for heating the ovens. The coke making industry consists of two sectors, integrated plants and merchant plants. Integrated plants are owned by or affiliated with iron-and steel producing plants who produce blast furnace coke primarily for consumption in their own blast furnaces. Independent merchant plants produce furnace and/or foundry coke for sale in the open market. These plants sell most of their products to other plants engaged in blast furnace, foundry, and nonferrous smelting operations. A good quality coke is generally made from carbonization of good quality coking coal. Coking coals are defined as those coals that on carbonization pass through softening, swelling, and re-solidification to coke. One important consideration in selecting a coal blend is that it should not exert a high coke oven wall pressure and should contract sufficiently to allow the coke to...

Coke Oven By-Product Plant Jan17

Coke Oven By-Product Plant...

Coke Oven By-Product Plant The coke oven by-product plant is an integral part of the by-product coke making process. During the production of coke by coal carburization in a coke oven battery a large amount gas is generated due to the vaporization of volatile matter in the coal. The gas is generated over most of the coking period, the composition and the rate of evolution changing during this period and being normally complete by the time coal charge temperature reaches 700 deg C. This gas is known as raw coke oven gas and is processed in the by-product plant. The functions of the by-product plant are to process the raw gas to recover valuable coal chemicals and to condition the gas so that it can be used as a clean, environmentally friendly fuel gas. After leaving the coke oven chambers, the raw coke oven gas is sprayed with flushing liquor so as to reduce its temperature to a reasonably low level and to condense the most easily condensable (high boiling point) components. The raw gas is cooled by adiabatic evaporation of some of the spray liquor to around 80 deg C and is water saturated. The temperature of the gas becomes sufficiently low so that it can be handled in the gas collecting mains. 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 flushing liquor which is not evaporated provides a liquid stream in the gas collecting main. At this stage there are two streams namely a liquid condensate stream and a gas stream. The two streams pass through a butterfly control valve...