THE DESIGN ANALYSIS OF BLAST - FURNACE SMELTING CHARACTERISTICS AND PROCESSES
I.G. Tovarovskiy
Iron and Steel Institute of National Academy of Science of Ukraine.
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For increase of efficiency, depth and reliability of the analysis, establishment of interrelations of parameters and the revealing of opportunities of perfection of blast - furnace technology, are developed a technique and algorithm of the system analysis of the current characteristics of the work of blast furnaces. Feature of the technique is the opportunity of "mitigation" of influence of errors of the technological account on smelting characteristics at the expense of shaping the corrections in the initial data on a base of analysis of the disparitys of iron, slag-forming and gasified elements balances.
INTRODUCTION
The design methods of the analysis are the formalized tool of a understanding of processes in the quantitative form basing on the blanket laws of the nature. The perfection of this tool is determined by a level of knowledge of the blanket laws and correctness of their use for the analysis of specificity of investigated processes. The base laws for the closed systems are the laws of preservation of weight and energy, which use at the design analysis of blast furnace smelting assumes a solution of two base tasks: 1) study of interrelations of parameters and characteristics of real blast - furnace smelting; 2) forecasts of expected characteristics of blast - furnace smelting on preset parameters of work.
The realization of each of the specified tasks is based on a solution of specific problems. In case of the forecast these problems are connected to a correctness of initial assumptions and expedient degree of detailed elaboration of the description of processes [1]. In case of the analysis of real technology major value have completeness, accuracy, reliability of the initial information and way of its treatment. The specified aspects of the analysis of real technology are a subject of consideration of the present work.
PROBLEMS OF REAL TECHNOLOGY ANALYSIS
The effectiveness of real blast - furnace smelting analysis depends to a great extent on reliability of the initial data, on which he bases. However the last, as a rule, have errors, which sizes are unknown. This not only complicates the analysis, but sometimes deforms its results. Use of design complex parameters and balances including sizes gauged with errors of a different nature and size is especially complicated.
For the first time these questions studied A.N. Ramm [2], who in reference to gasified elements (C,O,N,H) has shown an opportunity of a choice best on size of a minimum of an error of variants of the analysis. Further A.B. Shoor [3], by making the equation of compatibility of the initial data, has received expression for the corrections, which it is necessary to bring to these data in, that the results of account were consistent. Later author of present article in a course of analysis of the characteristics of branch blast - furnaces working has shown [4], that the revealing of disparitys of iron, slag-forming and gasified elements balances is a major component of the analysis and has developed a technique of definition of equivalent rejections of parameters at entering the corrections into the initial data and appropriate computer system of the analysis. The main role of duration and repeatability accepted for the analysis of the individual periods of work of the furnace is shown and also method of treatment of results on a ground that the principles of selection and data processing are formulated [4,5].
The developed system of analysis includes, alongside with gauged initial parameters of processes, also design smelting characteristics: complex parameters of blast regime; iron, slag-forming and gasified elements balances; a heat balance; reducing-thermal and gas dynamics characteristics. The important component of the analysis is the estimation of influence of errors of the initial data on the design characteristics of processes. Without this component the analysis has not that definiteness, which is necessary for reliable conclusions. So, by not estimating an error of definition of any complex parameter in two compared periods of a blast-furnace operation it is impossible to estimate importance of difference of its values in these periods. For such estimation the balances of iron, slag-forming and gasified elements are used. The disparitys of this balances are the integrated characteristics of errors of the initial data. The analysis by computer of ponderability of various errors of the account in total value disparitys of balances allows to estimate the most probable variants of errors and close to "true" value of design parameters. At comparison of "true" values of parameters in the various periods the "zone of an error ", allowing is taken into account and to judge importance of difference of "true" values. So, if at difference of "true" values of a parameter in two periods or for two furnaces " the zones of errors " do not coincide or impose against each other in a small measure, it is possible to consider the specified difference essential. If the imposing of "zones of an error " is large, difference is insignificant. In a number of cases it is necessary to ascertain impossibility to make the certain conclusions of the analysis. Such conclusion is not less valuable, than determined, since allows to avoid erroneous judgements.
The further work in this direction has revealed opportunities of perfection of a technique of use disparitys of balances for an estimation of influence of errors of the initial data on "validity" of design smelting characteristics. The considered below new methodical developments differ from known. On a base of a resulted below analytical solution of a task it is possible to replace used earlier iterative procedure of disparitys separation by a more simple and evident way of an estimation of influence of possible account errors on smelting characteristics and to give a solution more suitable kind for the substantial analysis. Besides in considered statement a task of overlapping of balances of iron and slag-forming constituents of burden for the first time is decided.
ESTIMATION OF DESIGN CHARACTERISTICS WITH ACCOUNT OF THE DISPARITYS OF BALANCES
Disparitys of iron and slag-forming elements balances
The equation of compatibility of balance of iron and slag-forming elements is forming as equality of quantities of slag designed on the contents in burden constituents of iron - ШFe and base slag-forming components (CaO, SiO2, Al2O3) – Шш, Disparity of balances gives ш = Шш - ШFeor:
ш=100-[Ri-1,42850,01RiFei +0,112670,01RiFeОi+(Rм-RмFeм0,01)+Ио+Ид+((0,5S+Z)К-
-(ИоСО2ио+ИдСО2ид))0,01+УZу-(21,4Si+12,9Mn+16,6Ti+
+14,7V+14,6Cr+13,2As)(1-0,01(FeO)), (1)
where is designated: the consumption of burden constituents – Ri - ironcontaining, RM - metallized, K - coke, Ио ,Ид- limestone customary and dolomitized, У - consumption of coal injection, kg / t of pig-iron; the contents of the appropriate components in burden materials - without brackets (Z-coke ash, Zу-- coal ash), in slag - in parentheses, in pig-iron - in square brackets, % .
For definition of sizes of the corrections necessary for convergence of balances, we shall take private derivative from ш on the base measured parameters (contents of components): Fei, FeOi, FeM, CaOi, SiO2i, Al2O3i, (CaO), (SiO2), (Al2O3), (kg / %):
1)=1,42850,01Ri; 2)=-0,112670,01Ri;
3)=Rм0,01;
4)=;
5)=;
6)=;
7)=;
8)=100;
9)=100;
10)==. (2)
The size of an error Fei (%), appropriate to a rejection ш makes:
Fei = (%). At a toolhouse error of the contents Fe 0,3 % the specified size expressed in quantity of toolhouse errors, makes:
NFei==233,3. (3)
Similarly for other sizes of errors at size of a toolhouse error 0,3 % (abs.):
FeOi = (%); NFeOi =-2958,5; (4)
Feм= (%); NFeм =100; (5)
CaOi=(%);
NCaOi=3,333((CaO)+(SiO2)+(A2O3)); (6)
SiO2i=((CaO)+(SiO2)+(A2O3));
NSiO2i=3,333((CaO)+(SiO2)+(A2O3)); (7)
A2O3i=CaOi=SiO2i; NA2O3i=NCaOi=NSiO2i; (8)
Z=(%);
NZ=3,333((CaO)+(SiO2)+(A2O3)); (9)
(A2O3)=(CaO)=(SiO2)=-
=(%);
N(СaO)=-=
=N(SiO2)= N(A2O3). (10)
For an illustration: at the blanket consumption of burden Ri=1700 kg/t and average contents of iron 55 %, CaO-12 %; SiO2–10 %; Al2O3 –1%, coke 500 kg/t and Z = 10 %, Al2O3Z - 20% and at (CaO) = 42 %, (SiO2)=35%, (Al2O3)=7% – the disparity of slag quantity ш=10 kg/t is in accord with the following sizes possible toolhouse (0,3 % abs.) errors:
NFe=1,37; NFeO=-17,4; NFeм=0,59; NA2O3i=NCaOi=NSiO2i=1,65;
N(СaO)=N(SiO2)= N(A2O3)=-5,88; NZ=5,6.
Probability of presence of errors close to toolhouse is much above, than errors, which sizes exceed toolhouse. Therefore separation of the total size of disparity between measured sizes it is expedient to fabricate in inverse ratio to quantity of toolhouse errors (N), appropriate by this total disparity for each measured parameter. It gives the following two equations for separation the total disparity in fractions () for each parameter:
I. NFeiFei=NFeOiFeOi=NFeмFeм=NCaOiCaOi=NSiO2iSiO2i=
=NA2O3iA2O3i=N(СaO)(СaO)=N(SiO2)(SiO2)=
=N(A2O3)(A2O3)=NZZ. (11)
II.Fei+FeOi+Feм+CaOi+SiO2i+A2O3i+(СaO)+(SiO2)+
+(A2O3)+Z=1. (12)
Solution rather (СaO):
(СaO)+(СaO)+(СaO)+(СaO)+
+(СaO)+(СaO)+(СaO)+
+(СaO)+(СaO)+(СaO)=1; from which:
(СaO)=(SiO2)=(A2О3)=
=;
CaOi=SiO2i=A2O3i=(СaO);
Fei=(СaO); FeOi=(СaO);
Feм=(СaO); Z=(СaO).
Parameter correction for disparity separation:
(СaO)скор=(СaO)-(СaO)(СaO); (13)
(SiO2)скор=(SiO2)-(СaO)(СaO); (14)
(A2О3)скор=(A2О3)-(СaO)(СaO); (15)
CaOiскор=CaOi-СaOiСaOi; (16)
SiO2iскор=SiO2i-СaOiСaOi; (17)
A2O3iскор=A2O3i-СaOiСaOi; (18)
Feiскор=Fei+FeiFei; (19)
FeOiскор=FeOi-FeOiFeOi; (20)
Feмскор=Feм+FeмFeм; (21)
Zскор=Z+ZZ ; (22)
After updating the account under the formulas of parameters and balances with definition the disparity of iron-balance Fe is carried out, then all residual disparity Fe concerns on the consumption of components by multiplication
Ri(1-)=Riскор.
Then the account of updating of makeup of components Fei, FeOi, …(СaO)… repeats at first with the subsequent account on those to the formulas and reception of final results.
Disparitys of gasified elements balances
After direct account of the base parameters and characteristics of the blast- furnace smelting the check of convergence of balance of gasified elements С-О-N-Н is performing on a base known of makeup of a top gas (СО2,СО, Н2, N2, , м3/м3), quantity of burden oxygen Ошand coal Оу, coke rates K, oil M and coal У (kg/t), natural gas ПГ, coking gas КГ (м3/t)and their makeups, blast moisture (g/м3) and contents in him of oxygen (%) is fabricated. For this purpose the consumption of gasified carbon on balance of the specified elements is defined:
Сг=0,5357(СО2+СО)(А/Б); where: (23)
А = 0,7(УОу+Ош) - 0,025К - 0,5(0,93НпгПГ+0,93НкгКГ) –
- 5,1(МНм+УНу) -(0,003К+0,8УNу+0,93ПГNпг+0,93КГNкг);
Б=СО2+0,5(СО-Н2)-N2; =;
N2=1-СО2-СО-Н2.
Then is defined the unbalance of gasified elements referred to carbon:
С=С-Сг, kg/t, or in % 100. (24)
Degree of conformity of makeup of a blow (consumption VД) makeup of a top gas (consumption Vг) on balance of oxygen and nitrogen 0-N further is checked:
VгN2=VД(1-0,01)+0,93ПГNпг+0,93КГNкг+0,8( МNм+УNу+NкК); whence:
=, .
On the other hand, the runout of a dry top gas on unit of a blow makes:
()=1+0,01+0,8(Nк+ДуNу)+ДкгNкг+
+++Н2, м3/м3;
Where СО2фл=0,004[Ио(СаОио-SiО2ио)+Ид(СаОид+1,4MgOид-SiО2ид)]; Сd+CL- the consumption of carbon on direct reduction of iron and of difficult reduction elements.
After transformation:
()=[1+0,01+0,8(Nк+ДуNу)+ДкгNкг++]: : (1-H2), м3/м3;
The difference Vк= -() is the unbalance of gas in м3/м3of a blow, and ratio =v- that in % to quantity of gas. (25)
The total size of an error referred to carbon:
с=С-Сг(kg); the metrological error makes 0,005×K (kg).
The total size of an error in metrological units:
nс=с/0,005К (relative).
Dimensions:
CO2, СО, Н2, N2, – %; N2=100-CO2-СО-Н2; Нк, Nк, Ну, Nу, Оу, Нм, Nм - кг/кг; Нпг, Nпг, Нкг, Nкг - м3/м3..
For definition of sizes of the corrections necessary for convergence of balances, we shall take private derivative from Сг on the base measured parameters:
1)=; =, kg;
=(rel.);
2) =; =, %;
=(rel);
3) =; со=, %;
=(rel.);
4) =; =, %; =(rel.);
5)=;
=,%
n=(rel.);
6) =;
пг=, (м3);
nпг=,(rel.); [when ПГ0]. If ПГ0, then nпг=0;
7) =;
кг=, (м3);
nкг=,(rel.); [when КГ0]. If КГ0, then nкг=0;
8) =;
м=, (м3);
nм=,(rel.);
9) =;
у=, (kg);
nу=,(rel.). (26)
Probability of presence of errors close to toolhouse is much above, than errors, which sizes exceed toolhouse. Therefore separation of the total size of disparity between measured sizes it is expedient to fabricate in inverse ratio to quantity of toolhouse errors (N), appropriate by this total disparity for each measured parameter. It gives the following two equations for separation the total disparity in fractions () for each parameter.
I equations. The sum of a fraction = 100 %; с++…+пг = 1. (27)
II equations. Equality of products of a fraction on quantity(amount) of toolhouse errors of each parameter: сnс==….= (all with the unzero charges ПГ, КГ, М, У). (28)
Solution rather с:
с+с+с+…+с=1
с(1+++…+)=1
с=.
Solution concerning other fractions:
=с; со =с…
Updating of parameters:
(К)=К-сс; (29)
(Ош)=Ош+; (30)
(СО2)=СО2+; (31)
(СО)=СО+сосо; (32)
(Н2)=Н2+; (33)
(ПГ)=ПГ+пгпг; (34)
(КГ)=КГ+ кгкг; (35)
(М)=М+ мм; (36)
(У)=У+ уу; (37)
()=+. (38)
Algorithm of disparity separation
1. The initial data for accounts are formed by two ways:
- By entering is direct in the tables on the display of initial parameters from an extraneous source.
- Extraction from a database.
2. Definition of characteristics on the base design expressions and preservation to forming the final tables. Design expressions are notorious and not cites here.
3. Updating of burden and smelting products components.
3.1. The updating of each parameter on all size of the disparity on expressions is carried out:
Feiскор=Fei+Fei; FeOiскор=FeOi-FeOi; Feмскор=Feм+Feм; Zскор=Z+Z.CaOiскор=CaOi-СaOi; SiO2iскор=SiO2i-СaOi; A2O3iскор=A2O3i-СaOi;
(СaO)скор=(СaO)-(СaO); (SiO2)скор=(SiO2)-(СaO);
(A2О3)скор=(A2О3)-(СaO). (39)
For each variant of updating the account on the base design expressions with definition of the disparity of iron-balance Fe, is carried out, then all residual disparity Fe concerns on the consumptions of components by multiplication
Ri(1-)=Riскор. (40)
Then the account of updating of a burden constituent or slag repeats with the subsequent account on the base design expressions and reception of results. The specified variants of accounts are carried out partially or completely on inquiry of the user for the informal analysis of results and choice of the most plausible variants of updatings. By results if necessary of the analysis the not formalized corrections to the initial data are deposited, and the account on the base design expressions is carried out.
3.2. The updating of all parameters for total disparity ш separation is carried out. In case of absence of the not formalized updating (see is higher) this size is the reference value ш, in case of performance of the not formalized updating this size ш is the residual value after the specified updating. The updating for total disparity separation is carried out under the formulas (13) - (22).
4. Updating of gasified elements.
4.1. The updating of each parameter on all size of the disparity on expressions is carried out:
(К)=К-с; (Ош)=Ош+; (СО2)=СО2+; (СО)=СО+со;
(Н2)=Н2+; (ПГ)=ПГ+пг; (КГ)=КГ+кг; (М)=М+м;
(У)=У+у; ()=+. (41)
For each variant of updating on inquiry of the user the account on the base design expressions (partially or completely) is carried out with the purpose of the not formalized analysis of results and choice of the most plausible variants of entering of the corrections in the initial data. On a base of the analysis and entering of the corrections the account on the base design expressions is carried out.
4.2. The updating for total disparity с separation under the formulas (29) - (38) is carried out. At absence of the not formalized updating total disparity the reference value сis, at presence - residual value сafter updating. The size of discrepancy of makeup of a blow to makeup of a top gas (v in % to quantity of gas) is on expression (25) calculated. Its value after updating should decrease.
The value of sizes of the attitude of degrees of use of reducing gases (н/со) and fractions of the residual member of a heat balance from a total heat release rate (Qост/Q) should not leave from breaking points:
1,1 (н/со)0,9; 0,20 (Qост/Q) 0,05.
The cases of increase V after updating and runout (н/со) and (Qост/Q) from the specified breaking points are considered at the not formalized analysis with acceptance of the appropriate solutions about updating.
5. Shaping the target data. The target data are formed in the tabular form, in three subsections: actual parameters; design parameters; the corrected parameters. From a complete set of parameters shaping any sample under the indication of the user is provided.
COMPUTER SYSTEM OF REAL TECHNOLOGY ANALYSIS
The system includes the following components:
– Base of primary technological parameters of blast - furnace work (daily allowance, monthly, annual, separate periods), characteristics of units and ingoing materials;
– Program of layout and homogenization of the primary information (on furnaces, departments, periods);
– Program of account of complex parameters and material - heat balances with the analysis of balance disparitys and errors of the account;
– Program of shaping of various kinds of representation of results of treatment, their accumulation and transfer to other programs.
The order of representation of results of treatment of the information provides the various forms of printing them. Primary from them are: the average parameters for the period, design parameters, corrected parameters (with the account of balance disparitys).
The results of treatment of the primary information are formed in massifs, which can be used in other programs intended for the analysis of interrelations of parameters (for example, correlation-regression, cartographical etc.), observation long-term trends, estimation of power, ecological and economic activities, and also optimization of directions of development of blast furnace technology. The system is open and can be easily complemented by other programs on available information base, which also can extend.
At sufficient completeness of the initial information the continuous analysis of linkages of the base smelting characteristics and design characteristics is possible with the purpose of revealing the tendencies and laws of their change on separate furnaces, groups of furnaces and in branch with the subsequent shaping of the recommendations on perfection of technical politics in the field of a blast-furnace practice. Thus, the retrospective analysis of parameters of a blast-furnace practice is a semantic base of forecasting and planning of prospects of its development.
Use of the developed system in practice of the analysis of blast-furnace smelting is based on a combination of the formalized methods of treatment and comparison of parameters with informal receptions of the analysis which is taking into account insufficient completeness and ambiguity of the initial information. Such combination is the integral element of the system analysis. The specified analysis should be carried out continuously by virtue of specific features of blast-furnace smelting as large system containing unchecked elements. These elements cause unguided drift of parameters, which is necessary for tracing for acceptance of correct solutions on running blast-furnace melting. The essence of a problem consists in the following.
Known from blast-furnace practice drift of smelting characteristics at the same mode, and also maintenance of preset parameters at periodic change of a mode and return to it do not contradict laws of functioning the blast-furnace smelting as large system. They are explained to that by virtue of irregularity of distribution of environment and its properties in volume of the unit each mode contains components which are not appropriate to its average parameters and deform with current of time average parameters and smelting characteristics by accumulation of new properties, condition, stimulating spontaneous shear of processes in other area and requiring updating of a mode for achievement of preset attributes.
The high-frequency shakings of parameters, which period on the order is less than time of transients, practically are not passed by the blast furnace and do not influence target parameters. The shakings, commensurable with the time of transients, should be traced for use at operative running. The long-term changes, which duration considerably exceeds time of transients, do not influence the current condition of smelting, but result in slow shear of processes to a new mode, for which shaping the tracking of drift of processes is necessary by special treatment of parameters and attributes. In process of an abatement spatial - temporary heterogeneity of parameters (at the expense of stabilization of makeup both properties of burden and blow, uniformity of their distribution at submission in the furnace, perfection of constructions of units and equipment) there is an increase of duration of drift up to sizes, in a number of cases commensurable to the between-repairs period of work of the unit.
The observation of drift for shaping parameters of a new mode requires use of the automated monitoring system and analysis of processes.
CONCLUSION
For increase of efficiency, depth and reliability of the analysis, establishment of interrelation of parameters, the revealings of opportunities of perfection of technology are developed a technique and algorithm of the system analysis of the current blast-furnace characteristics.In a course of mining with use before created the ideologies and technical solutions are received the following new results: