Studies on the Possibility of Extending Coal Resources for Coke

Subscriber access provided by Gothenburg University Library

Article

Studies on the possibility of extending coal resources for coke production through the application of coal predrying Piotr Zarczynski, and Andrzej Strugala Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b03473 • Publication Date (Web): 28 Dec 2017 Downloaded from http://pubs.acs.org on January 11, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Studies on the possibility of extending coal resources for coke production through the application of coal predrying Piotr Żarczyński a*, Andrzej Strugała b a

ArcelorMittal Poland S.A. Zdzieszowice Unit, Powstańców Śląskich 1, PL-47300

Zdzieszowice, Poland b

AGH University of Science and Technology, Faculty of Energy and Fuels, Mickiewicza 30,

PL-30059 Krakow, Poland * Corresponding author: ArcelorMittal Poland S.A. Zdzieszowice Unit, Powstańców Śląskich 1, PL-47300 Zdzieszowice, Poland; T: +48 445 19 88, M: +48 66 20 10 560, e-mail address: [email protected], KEYWORDS: Cokemaking, coal predrying, coal base for coke production

ABSTRACT

Bituminous coals with very good coking properties are basic components of the coal blends utilized for the production of the high quality blast furnace coke. In industrial practice and on international market, these coals are known as hard type coals. Their appropriately high share in the coal blends ensures coke quality complying with the requirements of coke consumers. The deficit of hard coals on the market as well as their high price are the reasons that make the coke producers decrease their share in coal blends and replace them with coals of the semi-soft type, featured by worse coking properties but, at the same time, lower price and wider availability on

ACS Paragon Plus Environment

1

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 30

the market. Unfortunately, such an action causes a decrease in the quality parameters of the coke, which is unacceptable for coke consumers due to the fact that their expectations are increasing. A solution for this situation could be the implementation of the coal predrying process which involves a partial moisture removal from the blend down to 5%. The benefit of implementing the predrying process with this boundary moisture content is a coke quality improvement which still poses no technological problems connected with high coal dustiness. The goal of the research was to determine if the application of the coal predrying process could enable an increase in the share of semi-soft coals in coal blends (as a replacement of hard coals) without a coke quality decrease. The objects of study were two sets of commercial coal blends with a varying share of semi-soft coals. The first set of blends was composed exclusively of Polish coals and the second set was composed of Polish and foreign coals. Both sets of coal blends were applied for coke production in a test Movable Wall Oven (capacity: 400 kg) either in the wet state or in the predried state. Taking into consideration the basic quality parameters of the produced coke, such as coke strength and abrasion, (assessed by the Micum and Irsid drum tests) as well as coke reactivity and its strength after reaction (assessed by the NSC test), the possibility of the partial substitution (ca. 10 – 20%) of the hard coals by semi-soft coals in the coal blend utilized to produce the high quality blast furnace coke has been proven. Studies have confirmed the positive impact of coal predrying on the coke quality. Additionally, there was a fear of the wall pressure dangerous increasing for the tested blends in the case of the coal predrying process implementation but fortunately such situations had not occurred. Based on the results, it can be concluded that the application of coal predrying allows for increasing ca. 2 – 3 times the demand for coals of the semi-soft type and, as a consequence, it allows for changing the structure of coal resources for coke production. Additionally, the implementation of the coal predrying process


2

Page 3 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

allows for decreasing the unit energy consumption in the coke production process by ca. 7.5 – 8.5%, which means significant environmental benefits.

1.

Introduction

The cokemaking process requires the application of coal blends with a correctly matched composition allowing for obtaining coke with the quality complying with the customers’ requirements. Individual components of the coal blend have different coking properties and they play a specific role in the process of the coke porous structure formation which determines coke functional properties. The basic component which determines coke quality is the coal with very good coking properties: vitrinite reflectance = 1.13 – 1.55 %, volatile matter content (dry, ashfree basis = 25 – 30%, Free Swelling Index = 5 – 9; as well as high sinterability, good plasticity and low shrinkage after carbonization. Coke produced exclusively from this coal has a high quality – Coke Strength after Reaction exceeds 55. In industrial practice and international trade, this coal is known as a hard type coal. Apart from the hard type coal, a semi-soft coal is utilized to prepare the coal blends for coke production. In comparison to the hard coal, the semi-soft coal has a higher volatile matter content (Vdaf =27 – 34%), lower vitrinite reflectance (0.7 – 1.15), lower Free Swelling Index (4 – 6) and also: lower sinterability, worse plasticity and higher shrinkage. Semi-soft coal alone is not suitable for coke production and its presence in coal blends is justifiable because of a lower price than that of hard coal. The semi-soft coal share in a coke coal blend is limited by the required coke quality. The last group may consist of so-called leaning components characterized by the volatile matter content from a few to several percent (for instance: anthracite and other highly metamorphosed coals, coke dust, finely ground coke breeze). These coals are added to coal blends in relatively small amounts to reduce the expansion of plasticized coal grains (decreasing porosity of the resulting coke) and to reduce coke


3

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 30

shrinkage and thus decrease the mechanical stress in the forming of the coke cake. Their presence in the coal blend results in a coke yield increase generally, and particularly in an increase of the most required coarse fraction of coke, as well as an improvement of its mechanical strength [Krzesińska 2010], [Karcz A. 1995], [Strugała A. 2006].

In recent decades the main coke consumer, i.e. the metallurgical industry, increases continuously its expectations regarding coke quality. It results from the fact that inter alia the PCI technology (Pulverized Coal Injection) is more intensively used in the blast furnace process, which allows for replacing the expensive coke by the cheaper pulverized coal. Even though the PCI technology allows for reducing the role of coke as a fuel and a reducing agent in blast furnace, the coke still serves as a grate in the blast furnace which is responsible for the gas permeability of the charge. Therefore, the lower consumption of coke in the blast furnace is accompanied by increased requirements for its quality, especially regarding its strength [Pusz 2010]. Table 1 presents current requirements for coke utilized in iron metallurgy in comparison with the quality of the coke produced in Poland [Warzecha A. 2012].

Table 1. Average quality parameters of the coke currently produced in Poland in comparison with the customer requirements [Warzecha A. 2012] Parameter [%] Coke Reactivity Index (CRI) Coke Strength after Reaction (CSR) Coke abrasion (M10) Coke strength (M40) Ash content Total sulfur content

The required quality of coke produced in a blast furnace with a capacity of: Medium Large 65 6–7 5–6 78 – 82 82 – 90 12.5 ± 0.5 11.5 ± 0.5 0.7 ± 0.1 0.6 ± 0.1

The quality of coke produced in Poland 28 – 35 57 – 62 6–7 75 – 82 8.5 – 10.0 0.5 – 0.7

The increase in requirements for the quality of coke results in an increased consumption of hard type coal [Pusz S. 2009]. In such a situation, in a number of countries (including Poland), the


4

Page 5 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

deficit of hard coals has appeared simultaneously with the oversupply of semi-soft coals. Therefore, the import of relatively expensive hard coals from overseas has become necessary [Karcz A. 2008], [Latocha W. 2011], [Żarczyński P. 2012], [Czornik G. 2011], [GanderskaWojtaczka K. 2011]. This resulted in a significant increase in the cost of coke production exacerbating the economy of its production [Ozga-Blaschke U. 2008], [Ozga-Blaschke U. 2010]. Such a situation encourages the search for technological solutions enabling the substitution of hard coals by semi-soft ones, at least partially, and keeping the high quality of coke simultaneously [Hereźniak W. 2011]. Among different possible solutions complying with both of the conditions, the operation of coal predrying before the coking process deserves special attention [Karcz A. 2006], [Karcz A. 2007], [Karcz A. 2009], [Poultney W. 2000], [Latocha W. 2010], [Sikorski C. 2009]. This process can be performed in different ways in industrial conditions. In the extreme case, called coal preheating, almost the whole moisture is removed from the charge but the application of this technology may lead to many technological problems such as intensive dustiness during transportation, charging of coke chamber and also during the first period of the coking process. Moreover, a significant wall pressure can occur, which is dangerous to the coke oven battery refractory. For these reasons, a better solution is partial coal predrying which involves removing the moisture down to the level of ca. 5%. The idea of this technology called Coal Moisture Control (CMC) was born in the 80's of the 20th century in Japan and has been used in other countries in the region. The main reason for its industrial application is the need to stabilize moisture content in the coal blend which is very variable due to the climate variability in this region. Advantages of CMC technology constitute an acceptable compromise between benefits (such as coke oven battery capacity increase, coke quality improvement or energy effectiveness increase) and technological problems mentioned above


5

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 30

[Czaplicki A. 2007], [Poultney W. 2000], [Wakuri S. 1985], [Nomura S. 2005]. Table 2 presents examples of an industrial application of the CMC technology. It has to be emphasized that the coal predrying technology has not been applied beyond coking plants in Far East countries.

Table 2. Commercial applications of the pre-drying technology CMC [unpublished data of Nippon Steel Engineering 2011] Year of construction 1983 1991 1995 1996 1996 2011

Plant, country Oita, Japan Kimitsu, Japan Yawata, Japan Chong Qing, Japan Muroran, Japan Maanshan, China

Type of dryer st

1 generation dryer – Steam Tube Dryer (indirect heat exchange) 2nd generation dryer – Coal In Tube (indirect heat exchange) 2nd generation dryer – Coal In Tube (indirect heat exchange) 1st generation dryer – Steam Tube Dryer (indirect heat exchange) 3rd generation dryer – Fluidized Bed (direct heat exchange) 3rd generation dryer – Fluidized Bed (direct heat exchange)

In previous studies on coal blend predrying, the investigations were oriented towards coke quality improvement – inter alia [Tramer A. 2001] [Czaplicki A. 2007]. The goal of the studies conducted by Nippon Steel Co. was, inter alia, finding the relation and explanation for the impact of coal predrying (down to 3% moisture content) on the maximal wall pressure generated by the carbonized coal cake. As a result, it was determined that the dangerous wall pressure did not occur for a coke coal blend including 35% of semi-soft coals [Nomura S. 2005]. In contemporary literature there is a lack of information about research results confirming the possibilities of application of the coal predrying in order to partially substitute hard coals by semi-soft coals. Therefore, such studies are provided in the research project entitled "Smart coke plant complying with the requirements of “Best Available Techniques”, financed by The National Centre for Research and Development. 2.

Experimental and analytical procedures


6

Page 7 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

The goal of the presented research was to prove the possibility of semi-soft coals share increase in the coal blend by applying the predrying process without decreasing the quality of the produced coke. The boundary value for moisture content of 5% was determined because existing experiences prove that a further decrease of the moisture content leads to the escalation of the undesirable side effects described earlier (coal dustiness). The research program included coking tests of coal blends in the wet state (total moisture content ca. 9%) and after the predrying process (total moisture content decreased to ca. 5%). Objects of the study were two sets of coal blends composed of a few kinds of hard and semi-soft coals having different shares of the latter (10%, 20% and 30%). The first set of coal blends was composed of Polish coals only and the second set was composed of Polish and foreign coals. The compositions of the coal blends obtained in that way are given in Tables 3 and 4. Tables 5 and 6 present the characteristics of individual coals – the components of coal blends. Tables 7 and 8 present the characteristics of all the examined coal blends. Table 3. Composition of the examined blends consisting of Polish coals only [%] Coal components Symbol of coal

Type of coal

HDC 1 HDC 2 HDC 3 HDC 4 SDC 5

hard hard hard hard semi-soft

D10 10 20 40 20 10

Share of coal [%] Symbol of coal blend D20 10 10 40 20 20

D30 10 40 20 30


7

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 30

Table 4. Composition of the examined blends consisting of Polish and foreign coals [%] Coal components Symbol of coal

Type of coal

HMC 1 HMC 2 HMC 3 HMC 4 HMC 5 SMC 6

hard hard hard hard hard semi-soft

Share of coal [%] Symbol of coal blend M20 20 20 15 10 15 20

M10 30 20 15 10 15 10

M30 10 20 15 10 15 30

Table 5. Characteristics of coals applied for composing the examined blends consisting of Polish coals only Parameter A (dry base) [%] VM (dry and ash free base) [%] FSI Dilation – contraction Dilation – expansion

HDC 1 6.6 24.35 8.0 -20 106

Coal HDC 3 7 28.35 8.5 -21 190

HDC 2 8.5 24.05 7.5 -18 75

HDC 4 7.3 21.5 7.5 -18 37

SDC 5 7.5 32.9 7.5 -19 87

Table 6. Characteristics of coals applied for composing the examined blends consisting of Polish and foreign coals Parameter A (dry base) [%] VM (dry and ash free base) [%] FSI Dilation – contraction Dilation – expansion

HMC 1 6.7 23.0 8.0 -20 47

HMC 2 7.5 28.1 8,5 -26 112

HMC 3 8.4 25.4 7,5 -20 108

Coal HMC 4 10.8 30.0 8.0 -20 184

HMC 5 8.7 29.95 9.0 -21 230

SMC 6 8.1 33.5 7,5 -20 28

Table 7. Characteristics of coal blends composed of Polish coals only Characteristics of tested coal blend Coal blend symbol Semi-soft coals share [%] A (dry base) [%] VM (dry and ash free base) [%] FSI Dilation – contraction Dilation – expansion Total moisture [%]

D10 10 7.4 25.2 8 -20 118

D20 20 7.3 26.0 8 -20 119

D30 30 7.2 26.9 8 -20 120

9,1

4,9

8,8

4,8

8,8

4,9

Bulk density (dry base) [kg/m3]

740

781

744

772

741

767


8

Page 9 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 8. Characteristics of coal blends composed of Polish and foreign coals Characteristics of tested coal blend Coal blend symbol Semi-soft coals share [%] A (dry base) [%] VM (dry and ash free base) [%] FSI Dilation – contraction Dilation – expansion Total moisture content [%] Bulk density (dry base) [kg/m3]

M10 10 8.0 26.0 8 -19 104 9,0 743

M20 20 8.1 27.0 8 -22 98 5,0 792

9,2 739

M30 30 8.2 28.0 8 -23 99 5,2 785

9,2 747

4,9 790

Due to the lack of technical possibilities to perform a coking test of the examined blends in the commercial-scale plant, the test Movable Wall Oven (400 kg capacity) located in Centre de Pyrolyse de Marienau (France) has been used – see the Figure 1. This test plant includes the equipment for: − coal blend preparation (devices for crushing, dosing and drying of coal), − coking of the examined blend (the test Movable Wall Oven with 400 kg capacity, equipped with: coal tower, devices for top or stamp charging), − coke pushing reception and wet quenching, − mechanical stabilization and coke screening. The test Movable Wall Oven includes a chamber with dimensions 0.4 – 0.7 m x 1.0 m x 1.2 m (width x length x height). The electric heating enables reaching a temperature of walls in the range from 1000 to 1300oC. The test oven is equipped with an automatic control of the wall temperature. The mass of coal charge can be between 350 and 600 kg, depending on the chamber width and the applied system for coke chamber charging (filling).


9

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 30

During the coking tests the following parameters can be measured and recorded: − temperature of the heating walls and the temperature in the middle of the coke cake, − wall pressure (the pressure exerted by the coal charge on the test Movable Wall Oven), − internal coking pressure (gas pressure inside the plastic layer of the coal cake), − shrinkage of the carbonized coke cake, − energy consumption.

7 1

6

2 4 3

8

5

Figure 1. The test Movable Wall Oven in CPM 1 – fixed wall, 2 – movable wall, 3 – extensometer, 4 – internal gas pressure measurement, 5 – counterweight (calibration), 6 – measurement of coke shrinkage, 7 – heating elements, 8 – movable car on rails The bulk density of the coal charge is determined based on the charge weight and its volume in the test chamber. The produced coke is subjected to tests including the proximate and ultimate analyses as well as a reactivity and mechanical properties evaluation (the Micum, Irsid and NSC tests). Moreover, the coke yield and its grain size distribution are also determined.


10

Page 11 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

The coking tests described in this paper were conducted in conditions equivalent to the top charging of a coke chamber. The rate of coking is the basic parameter maintained at the level equivalent to that in the commercial coke oven battery and tracked during the coking tests. The examined coal blends were composed of individual coal components with the moisture content and grain size distribution corresponding to those applied in the industrial practice at Zdzieszowice Coking Plant. The required moisture content in the pre-dried coal blends was achieved by air drying in the ambient temperature. Table 9 presents the basic parameters of coking processes. Table 9. Basic parameters of coking processes Parameter

Coke Oven Battery of the PWR-63 type 410 13.2 15:30

Chamber width [mm] Coking rate [mm/h] Coking time [h:min] Bulk density (dry base) of coal charge [kg/m3]: – for wet blends 740 – for pre-dried blends * 775 * - value calculated according to the procedure presented in [Strugała 2006]

Test Movable Wall Oven in CPM 475 13.2 18:00 740 775

The quality of the produced coke was evaluated with the application of the proximate analysis as well as the Micum, Irsid and Nippon Steel Co. tests. The mechanical properties of the produced coke were evaluated by the Micum and Irsid drum tests (ISO 556:1980). These methods consist of a drumming procedure designed especially to imitate the mechanical stress for coke during its transportation and charging into the blast furnace. There are two important indices characterizing the examined coke. The first one is a content of coke grains below 10 mm after a drumming test of a specially prepared coke sample. This index is called coke abrasion and is a measure of the abrasion resistance of coke grains and


11

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 30

their corners. The second one is a content of coke grains above 40 mm and reflects the resistance of coke grains against degradation by crushing. This index is called coke strength. Table 10 presents a short comparison of the Micum and Irsid drum methods with the required values of those indices. Table 10. Basic parameters of the Micum and Irsid drum tests and required values of those indices [Karcz A. 1995] No.

Item

1

Characteristics of coke sample

2

Drum measurements

3

Test parameters

4

Determined indices

5

Value of indices required for blast furnace coke

Parameter

Unit

mass grain size fraction length diameter speed of rotation time of rotation total number of rotations coke abrasion coke strength coke abrasion coke strength

[kg] [mm] [m] [m] [rpm] [min] [-] [-] [-] [%] [%]

Method Micum Irsid 50 50 > 40 > 40 1 1 1 1 25 25 4 20 100 500 M10 I10 M40 I40 5–7 50

The coke obtained in the test oven was also evaluated by the method developed by Nippon Steel Corporation (ISO 18894:2006) and two characteristic indices were determined: CRI (Coke Reactivity Index) and CSR (Coke Strength after Reaction). In contrast to the previously described methods of assessing the mechanical properties of coke, this method takes into account the destructive impact of coke gasification with carbon dioxide. It is necessary to emphasize that even though the absolute values of indices of the coke obtained in the test oven in CPM differ from the values of these indices for the coke produced in commercial ovens, the results of the presented tests reflect the impact of coal predrying on the quality of the produced coke. Taking as a starting point the quality of the coke produced of a wet blend in industrial conditions, it is possible to determine the coal blend composition ensuring a


12

Page 13 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

similar quality of coke to that produced in commercial plants with the implementation of the coal predrying process. 3.

Results and discussion

The evaluation of the impact of coal predrying on the quality parameters of the produced coke and, consequently, the possibilities of changing the semi-soft coal share in the coal blend was made, taking into account the following parameters: − efficiency of the coking process including: bulk density of coal charge inside the coke chamber, coke yield in reference to the unit mass of the coal charge and coke yield in reference to the unit volume of the coke chamber space, − quality of the main product i.e. coke, including indices of the Micum and Irsid drum tests as well as the Nippon Steel Co. test (mechanical properties and reactivity of coke) − maximum value of the wall pressure generated by the coal cake during a coking test. Table 11 presents the uncertainty characteristic for CPM conditions or in accordance with ISO regulations [ISO 556-1980(E), ISO 18894: 2006] of these considered parameters were taken into account (when possible) during this evaluation and presented on following figures. Table 11. Uncertainty of the process, coal blend and obtained coke parameters considered in this chapter No.

Parameters

1 2 3 4 5 6 7 8 9 10

Bulk density of coal charge Coke yield (in reference to the unit mass of the coal charge Coke yield (in reference to the unit volume of the coke chamber space) Drum tests: Coke strength: the M40 index Drum tests: Coke strength: the I40 index Drum tests: Coke abrasion: the M10 index Drum tests: Coke abrasion: the I10 index The NSC-Test: the CRI-index The NSC-Test: the CSR-index Maximum wall pressure

Uncertainty Unit [kg/m3] [%] [%] [-] [-] [-] [-] [-] [-] [%]

Value ± 15 ± 0.25 ±2 ± 1.5 ± 2.5 ± 0.5 ±1 ± 2.5 ± 2.5 ± 15


13

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 30

The required effect is to obtain the same or better values of examined parameters after predrying operation implementation in relation to the appropriate values for wet coal blends including 10% of semi-soft coals.

Efficiency of coking process An increase of the total coke yield as an effect of coal predrying is caused by two factors: the bulk density increase and the increase of the unit coke yield (in reference to the unit mass of coal charge). The first one is a result of an increased mobility of coal grains resulting from the weakened impact of water meniscus between the coal grains [Strugała A. 2006]. The second one is a result of a more intensive conversion of the liquid and gas products of pyrolysis to solid products (coke and semi-coke) which is a characteristic phenomenon for a denser packing of carbonized coal grains [Griaznow N.S. 1976]. Figure 2 presents the impact of the coal predrying on the bulk density of coal charge inside the chamber. The positive effects were observed for both sets of the examined coal blends. The bulk density in the chamber increased by ca. 6.2% for the coal blend composed of Polish coal only (the first set of blends) and by ca. 4.3% for the coal blend composed of Polish and foreign coal (the second set of blends). Slight differences of the bulk density for the two sets of blends are caused by a different grain distribution of hard and semi-soft coals used as components of these blends.


14

Page 15 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 2. Impact of coal predrying on the bulk density of coal charge - results for both sets of the examined coal blends (measurement uncertainty: ± 15 kg/m3 for the confidence interval 95%)

The coke oven battery capacity is determined by the coke yield in reference to the unit volume of the coke chamber space (occupied by coal charge). This parameter, calculated as a product of the bulk density of the coal charge inside the chamber and the coke yield in reference to the unit mass of coal charge is presented in Figure 3 for both sets of the examined coal blends. For both sets of blends, a positive impact of coal predrying on the coke yield in reference to the unit volume of the coke chamber space was observed. In the case of the first set of coal blends, the average coke yield increase is 5.7% and in the case of the second set of coal blends, the average coke yield increase is 6.2%. Apart from the increase of semi-soft coal share with the higher volatile matter content, the implementation of coal predrying causes a significant increase of the coke yield of the unit coke oven volume due to the increase of the charge bulk density. This effect is clearly beneficial and improves the efficiency of the cokemaking process.


15

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 30

Figure. 3. Impact of coal predrying on the coke yield in reference to the unit coke oven volume results for both sets of the examined coal blends (measurement uncertainty: ± 0.2% for the confidence interval 95%) Comprising base coal blends (10% share of semi-soft coals without predrying) to the predried coal blend with higher content of semi-soft coal it observed that predrying operation increases the bulk density with statistical significance. The coke yield of the unit chamber volume do not increase significantly in case of blends composed of Polish coals only and significantly increases in case of blends composed of Polish and foreign coals. Coke quality The impact of coal predrying and the semi-soft coal share in the blend on the coke strength (expressed by the M40 and I40 indices) shows some differences in the case of both sets of the examined coal blends – see Figures 4 and 5. For blends composed exclusively of Polish coals, the implementation of coal predrying has a positive but very strong influence. For blends composed of Polish and foreign coals such an influence is not observed. Furthermore, in the case of this set of blends, there is a visible deterioration of the M40 and I40 indices for blends containing 30% of semi-soft coal.


16

Page 17 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 4. Impact of coal predrying on the M40-index of the obtained coke (results for both sets of the examined coal blends; measurement uncertainty: ± 1.5 for the confidence interval 95%)

Figure 5. Impact of coal predrying on the I40-index of the obtained coke (results for both sets of the examined coal blends; measurement uncertainty: ± 2.5 for the confidence interval 95%)

The impact of coal predrying on the coke abrasion (expressed by the M10 and I10 – indices) is clearly positive for both sets of the examined coal blends – see Figures 6 and 7. But, simultaneously, the semi-soft coals share increase has a negative influence on the two indices. Within the range of the analyzed changes, the decrease in the coal blend moisture content as well as the increase in the semi-soft coal share have a relatively low impact on the reactivity of the


17

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 30

produced coke (expressed by the CRI-index) – Figure 8. Such an observation is consistent with the results presented inter alia by [Tramer A. 2001], [Czaplicki A. 2007].

Figure 6. Impact of coal predrying on the M10-index of the obtained coke (results for both sets of the examined coal blends; measurement uncertainty: ± 0.5 for the confidence interval 95%)

Figure 7. Impact of coal predrying on the I10 –index of the obtained coke (results for both sets of the examined coal blends; measurement uncertainty: ± 1.0 for the confidence interval 95%)


18

Page 19 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 8. Impact of coal predrying on the CRI-index of the obtained coke (results for both sets of the examined coal blends; measurement uncertainty: ± 2.5 for the confidence interval 95%) The last analyzed parameter, i.e. coke strength after reaction (the CSR-index) is a key quality parameter characterizing the behavior of coke in the blast furnace [Pusz S. 2012], [Sakurovs R. 2012]. Its value is determined by baseline mechanical coke properties as well as the influence of the high-temperature coke gasification with carbon dioxide. For both sets of the examined coal blends, coal predrying impacts positively on the CSR-index – Figure 9. Simultaneously, the increase in semi-soft coals share has a negative influence on the CSR-index, especially for blends composed of Polish coals only.

Figure 9. Impact of coal predrying on the CSR-index of the obtained coke (results for both sets of the examined coal blends; measurement uncertainty: ± 2.5 for the confidence interval 95%)


19

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 30

Comprising the quality parameters of coke produced of base coal blends (10% share of semi-soft coals without predrying) to the coke produced of pre-dried coal blend with higher content of semi-soft there is no significant difference in the coke quality for blends containing 20 and 30% of semi-soft coals composed of Polish coals only. In case of blends composed of Polish and foreign coals there is no difference in obtained coke quality, when the semi-soft share increases to 20%. For this type of coal blends containing 30% of semi-soft coals the coke quality is significantly worse only for one parameter i.e. I40.

Maximal wall pressure generated during the coking tests An increase of the maximal wall pressure exerted by the carbonized coal cake was observed as a consequence of the coal predrying for both sets of the examined coal blends – Figure 10. It has to be emphasized that during only one coking test of the pre-dried coal blend (a coal blend composed exclusively of Polish coal with the semi-soft coal share of 10%), the wall pressure above 7 kPa was observed, and this value is treated as a warning [Karcz, A. 2001], [Nomura S. 2005].

Figure 10. Impact of coal predrying on the maximal wall pressure during coking tests (results for both sets of the examined coal blends; measurement uncertainty: ± 15% for the confidence interval 95%)


20

Page 21 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Comprising the important coking process parameter like maximum wall pressure for coking process of base coal blends (10% share of semi-soft coals without predrying) to the coking process of pre-dried coal there is no significant increase of this parameter in case of coking process composed of Polish coals only. The maximum wall pressure increases significantly in case of coking process of blends composed of Polish and foreign coals. The wall pressure represents the internal coking pressure and the increase of this parameters positively effects on coke quality. On the other side the possibility of maximum wall pressure increase is limited because of the possibility of damage to the coking oven walls. The maximum value of wall pressure considered to be safety equals 7 kPa and this value was not exceeded during the tests of pre-dried coal blends containing 20 or 30% of semi-soft coals.

Energy consumption during coking process The improvement of the energy efficiency of the cokemaking process is a key expected result of implementing the predrying operation [Żarczyński P. et al. 2013]. The higher energy efficiency facilitates a lower unit CO2 emission to the atmosphere as well as an increase in the economic efficiency of the coke production process. During the coking process, the electricity consumption was determined for both sets of the examined coal blends in the wet and the predried condition. The predrying operation allows for decreasing the unit energy consumption by ca. 7.5 – 8.5% depending on the analyzed coal blend – Figure 11.


21

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 30

Figure 11. Impact of coal predrying on the unit energy consumption during coking tests (results for both sets of the examined coal blends; measurement uncertainty: ± 2% for the confidence interval 95%) 4.

Evaluation of the possibility of increasing semi-soft coal share in the blend as a

result of implementation of the coal predrying process An analysis of the test results (Table 12) authorizes the conclusion that the implementation of coal predrying allows for increasing the share of semi-soft coal in the blend without adversely affecting the quality of the coke produced and without generating a dangerous wall pressure by the carbonized coal cake. In the case of the examined blends composed only of Polish coals, it is possible to increase the semi-soft coal share from 10% to 30% at the expense of the hard coal share in the blend, and in the case of the examined blends composed of Polish and foreign coals from 10% to 20%. Additional benefits include an increase of the coke oven battery capacity by ca. 3 – 5% and a decrease in the unit energy consumption by ca. 7.5 – 8.5%.


22

Page 23 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 12. Comparison of basic parameters characterizing efficiency and quality of the produced coke as well as the wall pressure generated during coking tests of coal blends Coke produced from blends composed of coals: Polish only Polish and foreign D10 D20 D30 M10 M20 M30 10 20 30 10 20 30 9 5 5 9 5 5 Wet PrePreWet PrePredried dried dried dried

Coal blend symbol Semi-soft coal share [%] Moisture content [%] Condition of coal blend Efficiency of coking process: – bulk density of coal charge [kg/m3] – coke yield (in ref. to unit mass of charge) [%] – coke yield (in ref. to unit volume of coke chamber space) [kg/m3] Drum tests: Coke strength: the M40 index the I40 index Coke abrasion: the M10 index the I10 index The NSC – Test: the CRI – index the CSR – index Maximum wall pressure [kPa]

740 75.5 559

772 75.0 579

767 74.8 574

743 76.3 566

785 75.6 593

790 75.5 596

66.3 37.5 8.8 24.5 29.9 52.2 4.8

69.1 42.5 8.1 23.4 29.5 54.5 6.5

68.2 40.1 8.5 24.1 30.2 51.8 5.6

72.0 43.5 6,8 22.1 27.1 55.5 2.9

73.6 44.3 6.9 21.6 27.8 56.6 5.7

69.6 38.1 7.0 21.9 27.8 57.5 5.7

The comparison of the statistical significance of changes of the quality parameters of coal blends, coking process and produced coke quality parameters (Table 13) shows that it is possible to produce the same quality coke after implementation the predrying operation and increasing the share of semi-soft coals in relation to coke produced of the base blend in wet condition. The predrying operation implementation allows for obtaining the same quality coke after increasing the share of semi-soft coals from 10 to 30% in case blends composed of Polish coals only and from 10 to 20% in case blends composed of Polish and foreign coals. For the second blends type the coke produced of the blend including 30% of semi-soft coals the coke strength I40 index is the only one coke quality parameter which is deteriorated with statistically significance.


23

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 30

Table 13. Statistical evaluation of the significance of changes of the quality parameters of coke produced of pre-dried blends in comparison to the base blend without drying process – legend: I – significant improvement, D – significant deterioration, 0 – no significant change

Characteristics of compered coal blends Kinds and condition of coal blends used in compared D20 (preD30 (precoking process dried) vs. dried) vs. D10 (wet) D10 (wet) Characteristic of the coal blend Coal components Polish only Polish only

M20 (predried) vs. M10 (wet)

M30 (predried) vs. M10 (wet)

Polish & Polish & foreign foreign coals coals Semi-soft coal share [%] 10 30 10 20 Moisture content [%] 5 5 5 5 Statistical evaluation of differences in the quality parameters of coal blend, coke and coking process Bulk density of coal charge [kg/m3] I 0 I I Coke yield (in ref. to unit mass of charge) [%]* D D D D Coke yield (in ref. to unit volume of coke 0 0 I I chamber space) [kg/m3] Drum tests: Coke strength: the M40 index 0 0 0 0 the I40 index I 0 0 D Coke abrasion: the M10 index 0 0 0 0 the I10 index 0 0 0 0 The NSC – Test: the CRI – index 0 0 0 0 the CSR – index 0 0 0 0 Maximum wall pressure I 0 I I Maximum wall pressure in comparison to critical lower lower lower Lower value Possibility of production the same coke quality from Yes Yes Yes No cheaper coal blend after pre-drying operation implementation assessment * no impact on the coke quality

5.

Conclusions

The coal predrying process allows for a reduction of the moisture content from 9 to 5% and, as a consequence, it affects positively the coke oven battery capacity and also the quality of the main product, i.e. coke. The implementation of such an operation yields also important environmental benefits because it allows for decreasing the unit energy consumption in the cokemaking process by ca. 7.5 – 8.5%. In the present market situation featured by a deficit of the best coking coals (hard coals), the implementation of the coal predrying enables their partial substitution in coal blends by more widely available and cheaper semi-soft coals without decreasing the quality of


24

Page 25 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

the produced coke and without the occurrence of the dangerous wall pressure (risky for coke oven batteries). It was shown that, for the examined commercial coal blends, it is possible to increase the share of semi-soft coals 2 to 3 times. Such a level of substitution of hard coals being in short supply, and also much more expensive, according to [Kwasniewski K. 2008], can guarantee the economic efficiency of the construction of a commercial scale coal predrying plant. It has to be emphasized that the optimization of the substitution ratio and the technological parameters of the coal predrying and coking processes requires commercial scale studies [Żarczyński P. 2011]. Nevertheless, the results of the study presented in this paper justify the desirability of the commercial implementation of the coal predrying process. This kind of investment could significantly enlarge the coal resources for coke production as well as positively affect the coke production efficiency. Acknowledgements This study was carried out within a framework of “Smart coking plant meeting the requirements of the Best Available Techniques” contract no. 01.01.02-24-017/08 project financed by Innovative Economy Operational Program funding by the European Regional Development Fund.

Thanks The authors wish to thank the team in Centre de Pyrolyse de Marienau in France for enabling the realization of the coking tests in test Movable Wall Oven.


25

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 30

References [1] Czaplicki A.: Predrying of coal charge for cokemaking, Karbo 2007, vol. 52 (Special Issue), p. 47 – 57, (in Polish), [2] Czornik G., Ziomber S., Strzelec H.: Development of JSW SA coal resources, The Mineral and Energy Economy Research Institute of the Polish Academy of Sciences Publishing House, Zakopane 2011, Conference Materials, p. 43 – 54, (in Polish), [3] Technical documentation of Nippon Steel Engineering 2011 – unpublished data, [4] Furosawa A., Nakagawa T., Meano Y., Komaki I.: Influence of Coal Moisture Control on Carbon Deposition in the Coke Oven Chamber, The Iron and Steel Institute of Japan, vol. 38, No. 12, 1998, [5] Ganderska-Wojtaczka K.: Coking coal resources of mines belonging to KW S.A., The Mineral and Energy Economy Research Institute of the Polish Academy of Sciences Publishing House, Zakopane 2011, Conference materials, p. 55 – 67, (in Polish), [6] Griaznow N.S.: Fundamentals of cokemaking process, Izd. Mietałurgija, Moscow 1976, (in Russian), [7] Hereźniak W., Warzecha A., Jarno M.: Prospects of market development for coke produced in Poland, Karbo 2011, vol 1, p. 6 – 18, (in Polish), [8] Karcz A., Cokemaking, AGH University of Science and Technology Press, Kraków 1995, (in Polish), [9] Karcz A.: Coking pressure - Part 1: Methods of the measurement of coking pressure and internal gas pressure, Karbo 2001, vol. 5, s. 163 – 168, (in Polish), [10] Karcz A.: Coking pressure – Part 3: The effect of coking pressure on coke oven walls, Karbo 2001, vol. 7 – 8 s. 261 – 264, (in Polish),


26

Page 27 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

[11] Karcz A., Kwaśniewski K., Strugała A.: Analysis of influence of selected macro- and microeconomic factors on valuation of cokemaking industry development strategy, Energy Policy Journal 2006, vol. 9 (Special Issue), s. 107 – 117, (in Polish), [12] Karcz A., Kwaśniewski K., Strugała A.: Risk assessment of innovative undertakings in cokemaking industry, Karbo 2007, vol. 52 (Special Issue), s. 14 – 21, (in Polish), [13] Karcz A., Sikorski C.: Selected technological conditions of coke production in Poland, Karbo 2009, Special Issue p. 37 – 46, (in Polish) [14] Karcz A., Strugała A.: Coking pressure – Part 4: The mechanism of coking pressure phenomenon, Karbo 2001, vol. 7 – 8 s. 265 – 273, (in Polish), [15] Karcz A., Winnicka G.: Coking pressure. Part 2: The impact of technological factors on the coking pressure, Karbo 2001, vol. 6 s. 204 – 208, (in Polish), [16] Karcz A., Strugała A.: Increasing chances of utilizing the domestic coking coal resources through technological operations in coal blend preparation, Mineral Resources Management vol. 24, Kraków 2008, p. 5 – 18, (in Polish), [17] Krzesińska M., Szeluga U., Smędowski Ł., Majewska J., Pusz S., Czajkowska S., Kwiecińska B., TGA and DMA studies of blends from very good Zofiówka coking coal and various carbon additives: Weakly coking coals, industrial coke and carbonized plants, International Journal of Coal Geology, 2010, no 81, p. 293 – 300, [18] Kwaśniewski K. Strugała A., Żarczyński P.: Possibilities of application of the real options method in finance evaluation of the investment projects in coke industry, Monographs of Technical University of Ostrava 2008, (in Polish), [19] Latocha W., Kaczmarek W., Strugała A., Żarczyński P.: Extending the coal base of the Polish cokemaking industry through the implementation of the coal charge pre-drying and


27

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 30

through the use of the overseas coals, Energy Policy Journal 2011 vol. 14 book. 2 p. 215 – 229, (in Polish), [20] Latocha W., Sikorski C., Strugała A.: Technological evaluation of the possibility of diversifying the supply of coals to domestic coking plants, The Mineral and Energy Economy Research Institute of the Polish Academy of Sciences Publishing House, Kraków 2010, The Bulletin of the Mineral and Energy Economy Research Institute of the Polish Academy of Sciences, vol. 78, p. 127 – 145, (in Polish), [21] Nomura S., Arima T, Kato K.: Coal Blending Theory for Dry Coal Charging Process, Fuel no 83, p. 1773 – 1776, 2005, [22] Ozga-Blaschke U.: The relationships between prices of coking coal and metallurgical coke in the international markets, Energy Policy Journal vol. 11, Book 1, p. 335 – 349, Kraków 2008, (in Polish), [23] Ozga-Blaschke U.: Economy of coking coal, The Mineral and Energy Economy Research Institute of the Polish Academy of Sciences Publishing House, Kraków 2010, (in Polish), [24] Poultney R. M., Willmers R. R.: Assessment of coal pre-treatment systems, The Coke Oven Managers’ Year-Book 2000, [25] Pusz S., Buszko R.: Reflectance parameters of cokes in relation to their reactivity index (CRI) and the strength after reaction (CSR), from coals of the Upper Silesian Coal Basin, Poland, International Journal of Coal Geology, 2012, no 90 – 91, p. 43 – 49, [26] Pusz S., Kwiecińska B., Koszorek A., Krzesińska M., Pilawa B.: Relationships between the optical reflectance of coal blends and the microscopic characteristics of their cokes, International Journal of Coal Geology, 2009, no 77, p. 356 – 362, [27] Pusz S., Krzesińska M., Smętowski Ł. Majewska J. Piława B., Kwiecińska B.: Changes in a


28

Page 29 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

coke structure due to reaction with carbon dioxide, International Journal of Coal Geology, 2010, no 81, p. 287 – 292, [28] Sakurovs R., French D., Grigore M.: Effect of the NSC reactivity test on coke mineralogy, International Journal of Coal Geology, 2012, no 94, p. 201 – 205, [29] Sikorski C.: Heat recovery Coke Plant versus By-Product Coke Plant, Karbo 2009 vol. 4, p. 231 – 239, (in Polish) [30] Strugała A.: The role of material and technological factors in the formation process of coke porous structure, AGH University of Science and Technology Press, Kraków 2006, (in Polish), [31] Tramer A., Kosewska M., Wróblewska K., Sobolewski A.: Possibilities of the coke quality improvement by pre-drying of coal charge, Ostrava 2001, Proceedings of Polish-Czech Conference, p. 41, (in Polish), [32] Wakuri S., Hosokawa K., Ohno M., Nakagawa K., Takanohashi Y., Ohnishi T., Kushioka K., Konno Y.: New Moisture Control System of Coal for Coking, Chiba Institute of Technology in Narashino, The Iron and Steel Institute of Japan 1985, [33] Warzecha A., Jarno M.: World trade of coking coal and coke, Conference of Polish Association of Metallurgical Engineers and Technicians, Karpacz 2012, unpublished, [34] Żarczyński P.: Efficiency evaluation of coal predrying for coke production, Proceedings of Young Scientists Conference in Cracow, AGH University of Science and Technology in Cracow, Pro Futuro Research Group, Cracow 2011, ISBN 978-83-88519-12-3, (in Polish), [35] Żarczyński P., Sikorski C., Strugała A.: Determination of strategic directions for the technological development of coke plants in Poland based on the coal base forecast and coke customer requirements, Energy Policy Journal 2012 vol. 15 part. 4 pp. 269 – 283, (in Polish), [36] ISO 556-1980(E). Coke (greater than 20 mm in size). Determination of mechanical


29

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 30

strength, [37] ISO 18894: 2006. Coke. Determination of coke reactivity index (CRI) and coke strength after reaction (CSR),


30

Studies on the Possibility of Extending Coal Resources for Coke

Recommend Documents