RU2236436C1 - Method for dry quenching of coke - Google Patents

Abstract

FIELD: metallurgy, in particular, production of coke in coke furnaces and dry quenching thereof.

SUBSTANCE: method involves producing coke in coke furnaces; charging coke into dry quenching chambers and blowing-through dry quenching chambers with cooling gas. Purified coke gas resulted from coking process is used as cooling gas, said gas being utilized for heating of coke batteries and transported to outer consumers for heating purposes.

EFFECT: reduced reactive capacity of resultant coke, reduced or eliminated carbon content in coke, reduced consumption of coke for melting of cast iron, provision for blowing-in of powdered charcoal fuel into blast furnace.

2 cl, 1 dwg, 1 ex

Description

The invention relates to the field of ferrous metallurgy, in particular to the production of metallurgical coke, specifically to dry quenching of coke.

Known methods and installation of dry quenching of coke [Installation of dry quenching of coke (CTC) at the factory of August Thyssen / B. Busman, K. Nogfer, Y. A. Filipp and others // Ferrous metals, No. 3, 1985, p. 3], which provide for periodic loading of hot coke into the quenching chamber and purging of the loaded portion of coke with cooling circulating gas obtained by initially passing air through the quenching chamber and burning part of coke carbon due to oxygen of this air (the rate of coke carbon burnout is 0.5% abs., in fact - up to 1.5%) [Coke fumes during its transportation and dry quenching / Stepanov Yu.V., Berkutov N.A., Vorsina D.V. et al. // Coke and Chemistry. 1999, No. 10, p. 11-16].

Dry coke quenching installation (CTC) consists of several chambers that are sequentially loaded with hot coke and pass circulating cooling gas, which transfer heat to recovery boilers or heat the coal charge [Using CCP waste heat to heat coal / H. Baer, X. Berthling // Ferrous metals, 1984, No. 12, p. 22].

The closest in technical essence to the claimed method is a known method of dry quenching of coke [Wizard of dry quenching of coke / Davidzon R.I. // Moscow: Metallurgy, 1980, 124 pp.], Which provides for blowing products into the CCUT chambers as cooling gas interactions of atmospheric air with carbon of cooled coke.

The disadvantage of this method is that for the process using the products of the interaction of atmospheric air with carbon of the cooled coke, which leads to significant losses of carbon in the cooled coke.

The technical result of the present invention is to reduce the reactivity of the obtained coke, reduce or eliminate carbon coke fumes during fire extinguishing, increase the carbon content of coke, reduce the consumption of coke for smelting pig iron and create conditions for the injection of pulverized coal (PFC) into a blast furnace by using as the cooling gas of coke oven gas obtained in the coking process.

The specified technical effect is achieved by the fact that the method of dry quenching of coke includes the production of coke in coke ovens, loading it into the quenching chambers, purging the dry quenching chambers with cooling gas, which is coke oven gas obtained in the coking process, and from coke oven gas obtained in the coking process Before feeding it to the dry quenching chambers, tar, benzene hydrocarbons, naphthalene, ammonia and other substances are recovered.

Coke oven gas supplied to dry coke quenching chambers contains hydrocarbons (mainly methane), hydrogen, carbon monoxide and carbon dioxide, oxygen and nitrogen. When such a gas enters a quenching chamber filled with hot (temperature of the order of 1000-1200 ° C) coke, thermal decomposition of CH ₄ and other hydrocarbons into hydrogen gas and solid soot carbon occurs by reaction (for methane) on the surface of the latter.

with a consumption of 3530 kJ / m ³ CH ₄ , moreover, from 1 m ³ CH ₄ 2 m ³ H ₂ and 0.5357 kg of carbon are formed. Given the fact that the temperature of the quenched coke [Calculation of coke ovens and coking processes using a computer: a training manual / Virozub IV, Ivnitskaya NS, Leibovich R.E. et al. // Kiev. Vyshka shkola, 1989, 303 pp.] Is 250 ° C, the gas temperature at the inlet to the recovery boiler is 850 ° C, and at the entrance to the extinguishing chamber - 20 ° C, then every 1 m ^{3 of} CH ₄ undergoes thermal decomposition, takes away heat

q = 3530 + 2 · 1.314- (850-20) + 0.5357 · 1.68 · 250 = 5936 kJ / m ³ CH ₄ ,

where 1,314 is the heat capacity of hydrogen, kJ (m ³ deg);

1.68 is the specific heat of carbon, kJ / (kg · deg).

Carbon dioxide present in coke oven gas also carries away heat by reaction

Then 1 m ³ CO ₂ will take away heat

q _CO2 = 11053 + (2 · 1.314 + 2 · 1.385) · (850-20) = 15533 kJ / m ³ СО ₂ ,

where 1.385 is the specific heat of CO, kJ / m ³ · deg). Oxygen present in the composition of coke oven gas when interacting with carbon of coke and soot will generate heat by reaction

Given that the resulting 2 volumes of CO will carry away the following amount of heat

q _CO = 2 · 1.385 · (850-30) = 2299 kJ / m ³ ,

total heat

q _O2 = 10500-2299 = 8201 kJ / m ³ ,

and each 1 m ^{3 of} coke oven gas, consisting of the following components,%:

after its interaction with the hot surface of the coke will take away heat:

q _{coke g} = 5.936 · (0.25-0.02) + 0.02 · 15533+ (0.075 · 1.399 + 0.07 · 1.385 + 0.57 · 1.324 + 0.005 · 2.131) · (850-20) -0.01 · 8201 = 2390.2 kJ / m ³ · kg,

where 1,369 is the heat capacity of nitrogen, kJ / (m ³ · deg),

2.131 - heat capacity of H ₂ S, kJ / (m ₃ · deg).

Since the heat content of 1 kg of hot coke is

q _coke = 1.68 · (1050-250) = 1344 kJ / kg coke,

then it is necessary to apply for its cooling, the following amount of gas:

V = 1344 / 2390.2 = 0.562 m ³ / kg of coke.

The method of dry quenching of coke is implemented as follows. Coke is produced in coke ovens in the usual way, it is also loaded into the chambers of the dry quenching unit in the usual way, and coke oven gas obtained in the coking process is used to cool the coke in the CCP, from which resins, benzene hydrocarbons, naphthalene are extracted before being fed to the dry quenching chambers, ammonia and other substances. Then, coke oven gas after dust deposition in a cyclone is cooled in a heat exchanger of the recovery boiler, and after dust removal in a fine filter, it is used to heat its coke oven batteries or transferred to a third-party consumer for energy needs.

The implementation of the proposed method of dry quenching of coke is illustrated by the scheme, where: 1 - chamber dry quenching of coke; 2 - cyclone; 3 - heat exchanger of the recovery boiler; 4 - fine filter; 5 - heater; 6 - gas pipeline commercial coke oven gas.

Coke cooled in this way retains all its carbon and, in addition, is saturated with soot deposits in the amount of

With _{carbon black} = 0.5357 · (0.25-0.02) · 0.562 = 0.069 kg / kg of coke,

where 0.02 is the proportion of CH ₄ spent on interaction with CO ₂ coke oven gas.

Due to the deposition of soot, the carbon content in the coke, initially containing, for example, 87% C, increases to C _c = (0.87 + 0.069) / (1 + 0.069) · 100 = 88.31%, i.e. almost 1.3%, and taking into account the elimination of fumes of 0.5-1.5%, the total carbon increase in commodity metallurgical coke will be at least 1.8%, while the ash content in coke will decrease by 0.6%, therefore , due to this measure, coke consumption in blast-furnace smelting will decrease by

Δ K = 1.8 / 0.87 + 1.3 · 0.6 = 2.85%,

where 0.87 is the proportion of carbon in coke, units;

1.3 - coefficient of influence on coke consumption to reduce the ash content in it by 1%,%. [Blast furnaces. Coke consumption standards. Guiding document, MFM USSR, HMI, 1987, Dnepropetrovsk, 14 pp.]

Saturation of pores of coke with carbon black will significantly reduce its reactivity [Experience of furnaces with injection of a gas-oxygen mixture in a furnace / Yu.V. Lipukhin, I.F. Kurunov, V.K. Kornev et al. // Steel, 1998, No. 2, p. 8, Cracking reactions in coke ovens and their importance for coke quality / P. Arendt, H. Kuhl, F. Huhn et al. // Cocemaking international. 2001, 13, No. 1, p. 61-64], which will reduce its grinding in the working space of the blast furnace on the way from the level of the mound, will increase the degree of use of reducing agents by at least 1% due to the indirect reduction of iron oxides with carbon coke, which will also reduce the consumption of coke.

An example implementation of the method

The dry coke quenching installation chamber (CTC) cools 56 tons of coke per hour. The temperature of the quenched coke is 250 ° C; to extinguish it, it is necessary to pass the following amount of coke oven gas through the chamber:

V _g = 56000 · 0.562 = 31489 m ³ / hour.

After all reactions in the quenching chamber proceed, the gas volume increases and amounts to

V _{cooling g} = 1 + CH ₄ + CO ₂ + O ₂ = 1 + 0.25 + 0.02 + 0.01 = 1.28 m ³ / m ^{3 of} coke oven gas,

and its composition and calorific value will be as follows:

Comparing the calorific value of 1 m ^{3 of} coke oven gas equal to 16642 kJ and the converted gas from 1 m ^{3 of} coke oven gas 1.28 · 10270 = 13146 kJ, we see that the latter value is 3496 kJ or 21% lower than that of coke oven gas. This value is equivalent: 3496/33403 = 0.105 kg of coke / m ^{3 of} oxide gas, where 33403 is the calorific value of coke, kJ / kg.

When the coke consumption is 400 kg / t of pig iron, it is consumed in the CCP for cooling it: 0.562 · 400 = 224.8 m ^{3 of} coke oven gas / t of pig iron, as when methane is decomposed, 0.5357 kg of C is emitted from 1 m ^{3 of} coke oven gas, then taking into account the compensation for the loss of calorific value in the process of gas conversion, soot will be released

_Soot = 224.8 · (0.5357 · (0.25-0.02) -0.105) = 4.09 kg / t of pig iron, which is equivalent in carbon to the following amount of coke: 4.09 / 0.87 = 4 , 7 kg.

Reducing the reactivity of coke will increase the utilization of the reducing ability of gases by at least 1%, which is equivalent to 4 kg / coke per 1 ton of cast iron.

Thus, the total reduction in coke consumption will be

Δ KΣ = 4.7 + 4.0 + 400 × (0.6 × 1.3) / 100 = 11.8 kg / t of cast iron.

Claims (1)

A method of dry quenching of coke, including the production of coke in coke ovens, loading it into dry quenching chambers and purging dry quenching chambers with cooling gas, characterized in that the purified coke oven gas generated during coking is used as cooling gas.