RU2015128C1 - Cement clinker firing process regulation method - Google Patents

Abstract

FIELD: construction. SUBSTANCE: method of regulation of cement clinker firing provides for: measurements of chemical composition of the mixture, of raw materials and fuel consumption, of kiln input raw materials temperature and cindering zones temperature; assignment of normal chemical exergy of the raw mixture; determination on the base of measured parameters of normal chemical exergy of initial raw mixture, determination of quantity of correcting addition in initial raw mixture and the last determination is made depending on difference of assigned normal chemical exergy and determined one. EFFECT: method is used in cement clinker firing. 2 tbl

Description

 The invention relates to the field of firing of cement clinker in a rotary kiln. It can be used in the construction industry, as well as in the mining and metallurgical industries.

 A known method of regulating the process of firing cement clinker, including grinding fine grinding and mixing of raw materials, firing the raw material charge and the introduction of the mineralizer, and the amount of introduced mineralizer is changed [1].

 The disadvantage of this method is the wide range of possible ratios of the mineralizer with the components of the raw material mixture without taking into account the chemical nature of the mineralizer itself, which negatively affects the efficiency of the process associated with the non-optimal organization of the process in the sintering zone.

 The closest in technical essence is a method for controlling the process of firing cement clinker, including measuring the chemical composition of the mixture, consumption of raw materials, fuel consumption, temperature of raw materials at the inlet to the furnace and the temperature of the sintering zone [2].

 The disadvantage of this method is that when regulating the firing process, the effect on the exergy efficiency of the process of changing the chemical properties and composition of the cement raw mix itself is not taken into account.

 The aim of the invention is the intensification of the process of mineral formation and the reduction of specific energy consumption for firing.

 The goal is achieved in that in a method for controlling the process of firing cement clinker, including measuring the chemical composition of the mixture, raw material consumption, fuel consumption, temperature of raw materials at the furnace inlet and sintering zone temperature, setting the normal chemical exergy of the raw mix, calculating normal chemical parameters based on the measured parameters exergy of the initial raw material mixture and determining the amount of corrective additives in the original raw mix, and the amount of corrective additives is determined depending on different the specified normal chemical energy and calculated normal chemical exergy.

 Table 1 shows the calculated values of the enthalpy of devaluation, the entropy of devaluation, and normal chemical exergy of the substances that make up the starting materials supplied for firing. The concept of a normalized reaction was introduced into chemical thermodynamics, so that algebraic actions could be performed on the thermodynamic effects of chemical reactions. The decrease in enthalpy occurring in the normalized devaluation reaction has been called the devaluation enthalpy. The decrease in entropy that occurs in the normalized devaluation reaction has been termed the entropy of devaluation. Normal chemical exergy of a substance is determined by a standard method based on the calculated values of the enthalpy and entropy of devaluation.

Table 2 shows the dependence of the exergy cost of the process calculated on the least squares method on the change in the temperature regime of the firing process. Obviously, the optimal value of normal chemical exergy in the sintering zone at a temperature of 1400-1450 ^o C is the value of 50-55 thousand kJ / kmol.

 If the normal chemical exergy of the current feed mixture differs from the optimal value of normal chemical exergy, the required amount of additionally introduced mineralizer is calculated taking into account its chemical nature (according to Table 1) to achieve the optimal value of normal chemical exergy of the current feed mixture.

 After entering the required amount of mineralizer into the process, the coefficient of exergy losses in the sintering zone is calculated and the necessary fuel consumption is corrected by it. Then, using the infrared indicator, optimally narrow limits of the thermal state of the sintering zone of the furnace are selected, which correspond to the optimal specific fuel consumption and, accordingly, the minimum value of the exergy loss coefficient in the sintering zone, maintain the heat engineering mode within the established limits. These limits are periodically monitored by checking the chemical composition of the current feed mixture and calculating the normal chemical exergy of the current feed mixture by the above method.

 PRI me R. Firing is carried out in a rotary kiln of a dry production method with cyclone heat exchangers (5x75 m).

The composition of the raw mix is given in table. 2 and includes: CaCl ₂ mineralizer; specific fuel consumption of 124.45 kg / t cl; specific consumption of raw materials (G _cheese.sm = 1.49 kg / kg cells); temperature the starting material is 5 ^{° C;} temperature in the sintering zone 1450 ^about C.

 Using the IWM RS-AT type IWM, a complete exergy analysis of the firing process is carried out on the basis of the measured parameters.

The optimal value of the normal chemical exergy of the cement raw material mixture in the sintering zone is set to 52000 kJ / kmol, the normal chemical exergy of the cement raw material mixture E _{cm is} calculated (for this we use the data in Tables 1 and 2).

E _cm = X ₁ E _cf + X ₂ E _hl + X ₃ E _og , where E _cm , E _hl , E _og - normal chemical exergy of 1 kmol of limestone, clay and pyrite cinder, respectively;
X ₁ , X ₂ , X ₃ - the percentage in the mixture of limestone, clay and pyrite cinder, respectively.

E _cm = 12430x0.78 + 171224x0.2 +
+ 3389.14 × 0.02 = 50718.48 kJ / kmol.

Next, the calculated value is compared with the optimal normal chemical value (E _opt ) and their difference (Δ E) is determined:
ΔE = E _opt - E _cm = 52000 - 50718.48 =
= 1281.52 kJ / kmol
Now, based on the difference in the values of normal chemical exergy, the required amount of additional mineralizer flow (G _min ) is determined, given that the normal chemical exergy of CaCl ₂ (E _min ) is 98700 kJ / kmol or 889.63 kJ / kg
G _min = (G _{raw cm} (Δ E / E _min )) / (100 -
- (Δ E / E _min ) = 1.49 x 1.4 / 98.6 = 18 kg / t cl.

 In connection with the introduction of an additional amount of a substance having normal chemical exergy, the coefficient of exergy loss of the sintering zone changes, i.e.

η = E _o + E _int / (E _t + E _s ),
get η = E _o + E _vn / (E _t + E _c + E _min ), where E _o , E _t , E _c and E _min are the exergy of exhaust gases, fuel, raw materials and mineralizer, respectively, and the exergy of fuel is defined as the product fuel consumption (G _t ) for the exergy of one kilogram of standard fuel (e). The exergy of 1 kg of standard fuel averages 10,000 kJ / kg.

E _int - internal exergetic losses of the firing process, taking into account exergetic losses from the finite temperature difference, losses during adiabatic combustion and losses due to mineral formation reactions.

Therefore, the required fuel consumption is defined as: G _t = (E _t - E _min ) / e = (124.45 x 10000 - 18 x 889.63) / 10000 - 122.84 kg / t cell.

 Thus, this method of regulating the firing process will reduce the specific energy consumption for firing cement clinker.

Claims (1)

 METHOD FOR REGULATING THE CEMENT CLINKER FIRING PROCESS, including measuring the chemical composition of the mixture, raw material consumption, fuel consumption, temperature of the raw material at the inlet of the furnace and temperature of the sintering zone, characterized in that the normal chemical exergy of the raw material mixture is set, and the normal chemical exergy of the starting material is calculated based on the measured parameters the raw mix and determine the amount of corrective additives in the original raw mix, and the amount of corrective additives is determined depending on the difference given th normal chemical exergy and calculated normal chemical exergy.