Title of Invention

AN EQUIPMENT FOR MEASUREMENT OF COKE REACTIVITY INDEX (CRI) AND COKE STRENGTH AFTER REACTION (CSR) VALUES OF COKE SAMPLE AND A METHOD THEREOF

Abstract

The present invention relates to an equipment for measurement of Coke reactivity Index (CRI) and Coke Strength after Reaction (CSR) values of coke sample comprising of: a reaction vessel; a coke container cage; a gas pre-heater pipe for heating the gas quickly before entering reaction vessel; a gas distributor for uniform flow control of gas to avoid peripheral gas flow; a gradient less heating system including furnace with cage type groove (I) on refractory walls to facilitate less heat absorption by refractory lining; and an electronic flow controller connected with the gas distributor for uniform and consistent flow during the entire period of reaction time.

Full Text

BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates to an equipment for carrying out CRI-CSR test to Blast Furnace coke sample for repeatable and consistent results and a method thereof. And more precisely the present invention relates to the design and development of the equipment for measurement of CRI and CSR indices of coke and the method based on typical design of a reaction vessel and furnace in particular to achieve uniform reaction conditions and other process parameters. The CRI-CSR test on coke is performed all over the world for the measurements of hot properties like Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR). The methodology of testing is already defined worldwide and followed by our country as well. 2. DESCRIPTION OF THE PRIOR ART Metallurgical coke traditionally is used in the blast furnace as a fuel to provide heat to meet the exothermic requirements of chemical reactions and melting of the slag and metal, a producer and regenerator of reducing gases for the reduction of iron oxides, and an agent to provide permeability for gas flow and support for furnace burden. Because of the many requirements placed on coke, it must meet stringent requirements of strength, size, and composition. The carbon content should be maximized. As a regenerator of reducing gas the coke should have minimum reactivity to carbon dioxide and water vapor. The purpose of the CRI test is to give insight into the ability of CO2 to react with the carbon in the coke, a necessary reaction in the blast furnace but which must be controlled to prevent carbon from being consumed prematurely in the indirect reduction zone of BF. The CSR test provides information about two different issues; 1) the strength of coke after reacting with CO2, and 2) the amount of dust produced by CO2- Fine dust can be detrimental in the blast furnace since it can decrease the permeability of the bed requiring increased blast pressure to force the air up through the bed. CRI-CSR test on coke is performed all over the world for the measurements of hot properties like Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR). The methodology of testing is already defined, which is followed in our country as well. However the philosophy behind this test is not available in the literature. This is indeed a matter of further investigation and research work to correctly establish the basis of the experimental procedure for evolution of CRI and CSR values of coke. Moreover the design of reaction furnace and other accessories are also not available and widely vary in design and dimensions. Coke is essentially a high carbon content, high calorific value, clean burning fuel used primarily in iron-making blast furnaces and other industrial applications. It is made from metallurgical grade coal, which is heated in the absence of air in large slotted ovens. Volatile matter is driven off, leaving fixed carbon. Repeatable experiments employing the testing equipment are very difficult to perform with representative coke samples to evaluate coke CRI and CSR values. Focus has been given on the reaction conditions like accuracy of the temperature for maintaining isothermal temperature regime, constant flow of gas all through the coke samples, hermetically sealed reaction vessel, coke packing inside the furnace etc, during design and development of the equipment. ITAGAKI SHOZO and others of NIPPON KOKAN KK in a Japanese specification JP61110057 discloses an automatic measuring apparatus for strength of coke after hot reaction to enable automatic measurement, by arranging equipments three- dimensionally in a sample adjuster so that, samples automatically flow in the order of process with an automatic control mechanism interlocking a sensor or the like while robots are set in a hot CO2 reaction unit to handle a series of works. Standard testing procedures for cokes to qualify them for use in blast furnaces have been developed over the years, as the science and art of blast furnace operation and the requirements of coke have become better understood. Prior to 1993, standard coke tests included proximate analysis to determine chemical composition, drop shatter and tumbler tests to determine strength, and specific gravity and porosity tests to measure structural characteristics. None of these tests were performed under conditions that the coke might encounter in the blast furnace, such as a harsh chemical environment, high pressure, and high temperature. In recent years, the Japanese steel industry developed a procedure that tests coke strength and breakdown to CO2 attack under blast furnace conditions. In 1993, this test was adopted as an ASTM standard test for coke as ASTM D 5341-93 entitled Standard Test Method for Measuring Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR). The joint CSR/CRI test heats a bed of coke in a nitrogen atmosphere to 1100 degree Celsius in 30 minutes, reacts the coke sample in a flow of CO2 for 120 minutes with the bed temperature constant at 1100 degree Celsius, cools the sample to 100 degree Celsius, transfers the sample to a tumbler, and tumbles the sample for 600 revolutions in 30 minutes. The sample is then sieved in a [3/8] inch sieve. The CSR is calculated as the remaining portion in the sieve compared to the amount removed from the furnace. BRIEF SUMMARY AND OBJECTS OF THE PRESENT INVENTION In brief summary, the present invention overcomes or substantially alleviates the problems of the prior art. Methods are provided for carrying out CRI-CSR test. The present invention further relates to design and development of equipment for measurement of CRI (Coke Reactivity Index) and CSR (Coke Strength after Reaction) values for Blast Furnace coke sample. With the foregoing in mind, it is a primary object of the present invention to overcome or substantially alleviate problems of the past associated with CRI- CSR tests. The primary objective of the invention is to carry out CRI-CSR test to BF skip coke for repeatable and consistent results. The present invention disclose equipment for measurement of Coke reactivity Index (CRI) and CSR Coke Strength after Reaction (CSR) values of coke sample comprising of; a reaction vessel; a special designed coke container cage; a gas pre-heater pipe for heating the gas quickly before entering the reaction zone; a gas distributor for uniform flow control of gas to avoid peripheral gas flow; a specially designed heating system with cage type groove (I) on the refractory walls to facilitate less heat absorption by the refractory lining; a electronic flow controller connected with a distributor for uniform and consistent flow during the entire period of reaction time; and a specially designed heating system for this furnace. Similarly, the invention also discloses a method for measurement of Coke reactivity Index (CRI) and CSR Coke Strength after Reaction (CSR) values of coke sample comprising the steps of; carrying out the gas solid reaction in batch process; sampling of the coke used in the reaction is 200 grams having -21+19 mm size; gasification of coke in the reaction vessel by elevation of temperature to 1100 degree Celsius under the flow of CO2 gas passed at the rate of 5 liters per minute for a duration of 2 hours; weighing of the reacted coke sample for calculating the weight loss of coke and the percent weight loss, which is termed as coke reactivity index; subjecting the reacted coke sample to l-type drum for measuring abrasions resistance of coke after reaction wherein the drum rotates at 20 rpm for 30 minutes (600 revolutions); sieving of the reacted coke through 10 mm sieve which is taken out from the said drum; calculating the percentage of +10 mm fraction of coke remained, which is termed as coke strength after reaction. Another paramount object of the present invention is to achieve a novel design of the test equipment and unique processes for achieving the consistent results. The following objectives are the key factors for the design and development of the equipment under consideration. a) Hermetically sealed reaction vessel. b) Optimum length to diameter ratio of the reaction vessel. c) Cooling of the reacting gas inside the reaction vessel from 1100 deg Celsius to 400 deg Celsius at the gas outlet of the reaction vessel. d) Section wise heating of the furnace for uniform heat at the zone where coke is placed inside the cage. e) Gradient-less reaction zone inside the reactor at 1100 deg Celsius for the coke samples. f) Cage heating system of the furnace with solid heating elements for quick and efficient heating due to better heat transfer. g) Four-sided furnace wall heating all along the furnace diameter. h) Coke container cage for uniform gas-solid reaction with each coke particles to avoid gas^channel effect leading towards improved permeability for the entire coke bed cross-section. i) Uniform flow control through gas distributor to avoid peripheral gas flow, j) Gas pre-heater pipe for heating the gas quickly before entering the reaction zone. k) Electronic flow controller for consistent flow of gas at the desired level. I) PID control through microprocessor based temperature controller for consistent temperature at the desired level, m) Stochiometric requirement of input and output as flow of reactant and product gases for confirming the extent of reaction. Repeatable experiments employing the testing equipment are very difficult to perform with representative coke samples to evaluate coke CRI and CSR values. Focus has been given on reaction conditions like accuracy of the temperature for maintaining isothermal temperature regime, constant flow of gas all through the coke samples, hermetically sealed reaction vessel, coke packing inside the furnace etc, during design and development of the equipment. These together with other objects of the invention, along with the various features of novelty, which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIG. 1 is a schematic drawing of the equipment for measurement of CRI and CSR values of BF coke sample. DETAILED DESCRIPTION The equipment for measurement of CRI and CSR values of blast furnace coke sample as disclosed in the present invention as illustrated in FIGS. 1 includes CO2 cylinder (A), N2 cylinder (B), a gas drier (C), electronic controlled flow meter (D) and a gas burner (K). The reaction unit includes a hermetically sealed vessel with top (H), a coke container cage (G), a cage heating system (I), a gas pre- heater / distributor (E), a furnace (F) and a thermocouple (J). The different units and their functionalities are described in detail hereinafter. The CRI / CSR equipment has been designed, fabricated and installed in Coal Carbonization Laboratory Group of Coke and Coal Division in RDCIS. During the initial design stage, there were various problems associated with the measurement of CRI and CSR values of the coke samples. The data generated that of CRI and CSR values were very inconsistent. In view of above, stochiometric calculations, for the material balance has been done to ensure the main process parameter like quantitative requirement of gas flow, contact time, void fraction, tortuosity factor, and Reynolds criteria. The reaction vessel in which the reaction of coke carbon with CO2 is taking place has also been modified and designed to ensure proper coke - carbon dioxide (C - CO2) interaction in the stipulated time frame of two hours. The design of the reaction vessel has been done incorporating the voids (tortuosity factor) generated by the coke of +19 -21 mm size. The design of the reaction vessel like diameter, length, heating zone, gas outlet zone, gas heating zone, gas pre-heater pipe, gas distributor etc. have been calculated to ensure consistent coke carbon reaction in the presence of CO2, to generate CRI and CSR values of coke. Special cage (G) has been designed to keep 200 grams of coke keeping in view the effective gas utilization with respect to CO2. No channel effect of gas is possible with the specially designed cage for 200 grams of coke mass (+19 - 21 mm size) since the coke particles are placed inside the cage in a uniform manner prior to the charging of reaction vessel (H). The cage is subjected to a reaction vessel at 1100 degree Celsius under the flow of CO2 gas passed at the rate of 5 liters per minute for a duration of 2 hours. The CO2 gas pre-heater (E) has also been designed to incorporate maximum heat transfer from the furnace to the gaseous medium at the rate of 5 liters per minute. During the reaction, the heat is rapidly transferred from bottom to the top zone of the coke bed because of the upwardly flow of heated CO2 gas. This may result in an inverse temperature gradient, where the bottom coke temperature becomes lower than the top coke particles and thus may affect the reaction kinetics drastically. This may eventually cause the bottom most coke particles to react less than that at the top. So as to avoid and minimize this effect to the extent possible, the furnace has been divided into two zones in a fashion to control the lower and upper portion of the coke bed separately through PID heating control. Heat transfer during the reaction at 1100 degree Celsius (at the coke bed) from the furnace (F), (at higher temperature than 1100 Degree Celsius) to the heating wall of the reaction vessel (H) is taking place maximum by radiation followed by convection and conduction. The rate of heat transfer from the silicon carbide heating element in the furnace has been found maximum with the specially designed heating system with cage type groove (I) on the refractory walls of the furnace. Cage type groove will facilitate less heat absorption by the refractory lining, while more heat transfer would take place towards the wall of the reaction vessel. In this way, the life of the heating elements is prolonged extensively and the heating of the reaction vessel is ensured to the maximum efficiency for obtaining consistent and uniform gas-solid reaction between coke carbon and carbon dioxide at 1100 degree Celsius. The gas flow meter fluctuations, which were taking place during the reactions is also eliminated through a specially designed electronic flow controller / meter (D) connected with a distributor for ensuring uniform and consistent flow during the entire period of the reaction time of preferably two hours. The weight loss of the coke during the reaction can be verified by the gas output stochiometry with the help of quantitative determination of the total gas evolved during reaction. This will ensure uniform reaction rate of carbon reaction during entire span of the test period.The reacted coke sample is weighed for calculating the weight loss of coke and the percent weight loss is termed as coke reactivity index. In addition, the furnace performance can be judged by means of indicator of the temperature located at three point, out of which one is placed in the vicinity of the coke charge inside the cage in the reaction vessel i.e. (thermocouple (J) and two numbers are connected to the furnace at the upper and the lower part of the coke bed heating zone. Thereafter the reacted coke sample is further subjected to l-type drum for measuring abrasions resistance of coke after reaction. The drum rotates at 20 rpm for 30 minutes (total 600 revolutions). Coke is taken out from the drum and passed through 10 mm sieve. The percentage of +10 mm fraction of coke remained is termed as coke strength after reaction. Several experiments have been carried out with coke samples using the aforesaid equipment at SAIL premises. Repeatability has been established with three consecutive test with the same coke samples A B and C. Table 1 shows the summary of the conducted with the equipment designed for the sake of evaluating values of Blast Furnace coke. The following Example is intended solely to illustration purposes not limiting the scope of present invention. The above-described embodiments of the invention are intended to be examples of the present invention. Numerous modifications changes and improvements within the scope of the invention will occur to the reader. Those of skill in the art may effect alterations and modifications thereto, without departing from the scope of the invention, which is defined solely by the claims appended hereto. We claim; 1. An equipment for measurement of Coke reactivity Index (CRI) and Coke Strength after Reaction (CSR) values of coke sample comprising of: a reaction vessel; a coke container cage; a gas pre-heater pipe for heating the gas quickly before entering reaction vessel; a gas distributor for uniform flow control of gas to avoid peripheral gas flow; a gradient less heating system including furnace with cage type groove (I) on refractory walls to facilitate less heat absorption by refractory lining; and an electronic flow controller connected with the gas distributor for uniform and consistent flow during the entire period of reaction time. 2. The equipment as claimed in claim 1, wherein the reaction vessel is hermetically sealed having an optimum length to diameter ratio and the reacting gas is cooled from 1100 degree Celsius to 400 degree Celsius at the gas outlet of the vessel. 3. The equipment as claimed in claim 1, wherein the furnace is equipped with section wise heating for uniform heat at zone where the coke is placed. 4. The equipment as claimed in claim 2, wherein the reaction zone inside the reactor is Gradient-less at 1100 degree Celsius for the coke samples. 5. . The equipment as claimed in claim 1, wherein the furnace is heated along the walls for uniform heating all along the furnace diameter. 6. The equipment as claimed in claim 1, wherein the coke container cage is provided for uniform gas solid reaction with each coke particles to avoid gas-channel effect leading towards improved permeability for the entire coke bed cross-section. 7. The equipment as claimed in claim 1, wherein the reaction time is preferably 2 hours. 8. The equipment as claimed in claim 1, wherein the furnace is also provided with a microprocessor based temperature controller for consistent temperature at the desired level through PID control. 9. The equipment as claimed in claim 1, wherein the weight loss during the reaction . is verified by a gas output stochiometry with the help of quantitative determination of the total gas evolved during reaction. 10. The equipment as claimed in claim 1, wherein the furnace performance is judged by means of indicators of the temperature located at three points, out of which one is placed in the vicinity of the coke charge inside the cage in the reaction vessel and two numbers are connected to the furnace at the upper and the lower part of the coke bed heating zone. 11. A method for measurement of Coke reactivity Index (CRI) and Coke Strength after Reaction (CSR) values of coke sample comprising the steps of: carrying out the gas solid reaction in batch process; sampling of the coke used in the reaction is 200 grams having -21+19 mm size; gasification of coke in the reaction vessel by elevation of temperature to 1100 degree Celsius under the flow of CO2 gas passed at the rate of 5 liters per minute for a duration of 2 hours; weighing of the reacted coke sample for calculating the weight loss of coke and the percent weight loss, which is termed as coke reactivity index; subjecting of the reacted coke sample to a drum for measuring abrasion resistance of coke after reaction wherein the drum rotates at 20 rpm for 30 minutes (600 revolutions); sieving of the reacted coke through 10 mm round sieve which is taken out from the said drum; and calculating the percentage of +10 mm fraction of coke remained, which is termed as coke strength after reaction. ABSTRACT AN EQUIPMENT FOR MEASUREMENT OF COKE REACTIVITY INDEX (CRI) AND COKE STRENGTH AFTER REACTION (CSR) VALUES OF COKE SAMPLE AND A METHOD THEREOF The present invention relates to an equipment for measurement of Coke reactivity Index (CRI) and Coke Strength after Reaction (CSR) values of coke sample comprising of: a reaction vessel; a coke container cage; a gas pre-heater pipe for heating the gas quickly before entering reaction vessel; a gas distributor for uniform flow control of gas to avoid peripheral gas flow; a gradient less heating system including furnace with cage type groove (I) on refractory walls to facilitate less heat absorption by refractory lining; and an electronic flow controller connected with the gas distributor for uniform and consistent flow during the entire period of reaction time.

Documents:

00140-kol-2005 abstract.pdf

00140-kol-2005 claims.pdf

00140-kol-2005 correspondence-1.1.pdf

00140-kol-2005 correspondence.pdf

00140-kol-2005 description(complete).pdf

00140-kol-2005 drawings.pdf

00140-kol-2005 form-1.pdf

00140-kol-2005 form-2.pdf

00140-kol-2005 form-26.pdf

00140-kol-2005 form-3.pdf

140-KOL-2005-(04-07-2014)-CORRESPONDENCE.pdf

140-KOL-2005-(04-07-2014)-DESCRIPTION (COMPLETE).pdf

140-KOL-2005-(04-07-2014)-DRAWINGS.pdf

140-KOL-2005-(04-07-2014)-FORM-1.pdf

140-KOL-2005-(04-07-2014)-FORM-2.pdf

140-KOL-2005-(04-07-2014)-OTHERS.pdf

140-KOL-2005-(12-12-2013)-ABSTRACT.pdf

140-KOL-2005-(12-12-2013)-CLAIMS.pdf

140-KOL-2005-(12-12-2013)-CORRESPONDENCE.pdf

140-KOL-2005-(12-12-2013)-DESCRIPTION (COMPLETE).pdf

140-KOL-2005-(12-12-2013)-DRAWINGS.pdf

140-KOL-2005-(12-12-2013)-FORM-1.pdf

140-KOL-2005-(12-12-2013)-FORM-2.pdf

140-KOL-2005-(12-12-2013)-OTHERS.pdf

140-KOL-2005-(18-01-2013)-CORRESPONDENCE.pdf

140-KOL-2005-(18-01-2013)-OTHERS.pdf

140-KOL-2005-CANCELLED PAGES.pdf

140-KOL-2005-CORRESPONDENCE.pdf

140-KOL-2005-EXAMINATION REPORT.pdf

140-KOL-2005-FORM 18.pdf

140-KOL-2005-FORM 26.pdf

140-KOL-2005-GRANTED-ABSTRACT.pdf

140-KOL-2005-GRANTED-CLAIMS.pdf

140-KOL-2005-GRANTED-DESCRIPTION (COMPLETE).pdf

140-KOL-2005-GRANTED-DRAWINGS.pdf

140-KOL-2005-GRANTED-FORM 1.pdf

140-KOL-2005-GRANTED-FORM 2.pdf

140-KOL-2005-GRANTED-FORM 3.pdf

140-KOL-2005-GRANTED-SPECIFICATION-COMPLETE.pdf

140-KOL-2005-REPLY TO EXAMINATION REPORT.pdf