RU2210580C1 - Method of monitoring productivity of soot reactor - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: proposed method includes measurement of consumption of raw materials, air and fuel and signals are furnished to computer input. Density of raw material is measured by means of mass flowmeter- density meter and signal is furnished to computer input. Stoichiometric coefficients of complete combustion of fuel and incomplete combustion of carbon are additionally introduced into computer input. Productivity of reactor is determined by the following formula:

where Q_react is productivity of reactor, kg/h; G_r.mat,G_air,G_fuel- consumption of raw materials, kg/h; consumption of air, n cu m/h; consumption of fuel, n cu m/h or kg/h for liquid fuel; f_f,f_st are stoichiometric coefficients of complete combustion of fuel, n cu m of air/n cu m of natural gas or kg of liquid fuel and incomplete combustion of carbon, n cu m of oxygen/ kg of carbon; 0.46 and 0.40 cu cm/g are coefficients; ρ₂₀ is density of raw material at 20 C, g/cu cm; 0.21 is content of oxygen in air. EFFECT: enhanced efficiency of control of process+ADs- enhanced stability of product. 1 dwg, 1 tbl, 1 ex

Description

 The invention relates to the automation of carbon black production and can be used to automatically control the performance of reactors in the resulting product.

 The process of producing soot in the reactor consists of a series of successively proceeding stages: complete combustion of fuel under conditions of excess oxygen, dispersion of liquid hydrocarbon feedstock in the combustion gas stream, its evaporation and incomplete combustion in the absence of oxygen remaining after fuel combustion, heating of the feed vapor to its temperature decomposition and the formation of dispersed carbon (soot). Thus, the carbon of the feed does not completely turn into a dispersed carbon product (soot), and part of it undergoes incomplete combustion (to CO) and leaves with the reaction gases. For the purpose of process control and timely adjustment of the technological regime, it is important to have timely information on the productivity of the reactor by product at the current consumption of raw materials (or the yield of the product on skipped raw materials, which is equivalent). Naturally, the technological mode is optimal, providing maximum output under the conditions of restrictions on the quality indicators of the product. Since up to now there are no instrumental control methods, the productivity of soot reactors is determined by calculation methods for various measured process parameters.

 A known method of monitoring the performance of the reactor (soot output), based on measuring the composition of the exhaust gas and data on the input process parameters. Soot yield is determined by the equation of carbon balance as the difference between the intake of carbon with fuel and raw materials and the consumption of carbon with flue gases [1]. However, this method is not operational, since the selection and analysis of a sample of exhaust gas takes a considerable period of time. In addition, even insignificant errors in determining the composition of the gas lead to a significant distortion of the final result.

 The closest in technical essence to the proposed is the method according to [2], which we have chosen as a prototype. In this method, the performance of a carbon black reactor is determined using a computing device from the measured values of the flow rates of raw materials, gas, air, specific surface area of soot and periodically entered values of the carbon content in the feedstock and fuel.

 The main disadvantages of this method are low accuracy and lack of efficiency in determining the performance of the reactor. Low accuracy is associated with the fact that the experimental expression for determining the function of the composition of the exhaust gas by the specific surface area of soot is preserved only for a narrow range of its values and a strictly constant quality of raw materials. When these parameters change, which is unavoidable in an industrial environment, the accuracy of determining the reactor productivity becomes unsatisfactory. In addition, there are currently no reliable sensors for monitoring the specific surface area of soot in the stream. The measurement of this indicator by sampling and analysis of a soot sample leads to a loss of efficiency. Another reason for the low efficiency of control is the need to find new coefficients for determining the function of the composition of the exhaust gas during the transition to the production of another brand of soot or when changing the composition of the raw material. Low accuracy and the inability to continuously determine the performance lead to the inefficiency of using the method for controlling a carbon black reactor.

 The aim of the invention is to ensure continuity and improve the accuracy of monitoring the performance of the reactor.

где Q_р - производительность реактора, кг/ч;
G_с - расход сырья, кг/ч;
0,21 - содержание кислорода в воздухе, в долях;
ρ₂₀ - плотность сырья при 20^oС, г/см³;
G_в - расход воздуха, нм³/ч;
G_т - расход топлива, нм³/ч (кг/ч для жидкого топлива);
f_т - стехиометрический коэффициент полного горения топлива, нм³ воздуха/нм³ (кг) топлива;
f_с - стехиометрический коэффициент неполного горения углерода, нм³ кислорода/кг углерода;
А, В - экспериментально определяемые коэффициенты.This goal is achieved by the fact that in a method for controlling the productivity of a carbon black reactor, including measuring the consumption of raw materials, air, fuel, they additionally measure the density of the raw materials, introduce stoichiometric coefficients for the complete combustion of the fuel and the incomplete combustion of the raw material carbon, using which the reactor productivity is determined by the expression

where Q _p - reactor productivity, kg / h;
G _with - consumption of raw materials, kg / h;
0.21 - oxygen content in air, in fractions;
ρ ₂₀ - density of raw materials at 20 ^o C, g / cm ³ ;
G _in - air flow, nm ³ / h;
G _t - fuel consumption, nm ³ / h (kg / h for liquid fuel);
f _t - stoichiometric coefficient of complete fuel combustion, nm ³ air / nm ³ (kg) of fuel;
f _with - stoichiometric coefficient of incomplete combustion of carbon, nm ³ oxygen / kg of carbon;
A, B are experimentally determined coefficients.

 The essence of the method is as follows.

Reactor productivity is defined as the difference between the amount of carbon entering the reactor with the feed and the amount of carbon transferred to the gas phase as a result of incomplete combustion of the feed (to CO)
Q _P = G _C α _C -Q $\genfrac{}{}{0ex}{}{\text{SG}}{\text{C}}$ , (1)
where α _C is the weight content of carbon, in fractions;
Q _s ^cr - the amount of carbon burned, kg / h

 The authors found that the amount of carbon burned can be determined not according to the composition of the reaction gases, but based on the use of stoichiometric coefficients of complete fuel combustion and incomplete combustion of carbon.

где G_в - расход воздуха, нм³/ч;
G_т - расход топлива, нм³/ч;
f_т - стехиометрический коэффициент полного горения топлива, нм³ воздуха/нм³ природного газа (или на кг жидкого топлива);
0,21 - содержание кислорода в воздухе, в долях;
f_с - стехиометрический коэффициент неполного горения углерода, нм³ кислорода/кг углерода.

where G _in - air flow, nm ³ / h;
G _t - fuel consumption, nm ³ / h;
f _t - stoichiometric coefficient of complete combustion of the fuel, nm ³ air / nm ³ natural gas (or per kg of liquid fuel);
0.21 - oxygen content in air, in fractions;
f _with - stoichiometric coefficient of incomplete combustion of carbon, nm ³ oxygen / kg of carbon.

The product f _t G _t is the amount of fuel used in the process of complete combustion of air, and in general, the numerator of formula (2) determines the amount of free oxygen remaining after complete combustion of the fuel. The quotient of dividing the amount of free oxygen by the amount of oxygen required for incomplete combustion of one kg of carbon (f _s ) gives the total amount of carbon burned in the process.

Известно [3] , что плотность сырья взаимосвязана с содержанием в нем углерода. Обработкой известных литературных данных по свойствам и составу различных типов используемого для производства сажи углеводородного сырья [4] и своих данных авторами методами корреляционного анализа найдено экспериментальное выражение
α_C = 0,46+0,40ρ₂₀, (4)
где 0,46 - свободный член уравнения, в долях;
0,40 - коэффициент, см³/г;
ρ₂₀ - плотность сырья при 20^oС, г/см³.Combining formulas (1) and (2), we obtain an expression for determining the performance of the reactor

It is known [3] that the density of raw materials is interconnected with its carbon content. By processing known literature data on the properties and composition of various types of hydrocarbon raw materials used for the production of soot [4] and their data, the authors found an experimental expression by the methods of correlation analysis
α _C = 0.46 + 0.40ρ ₂₀ , (4)
where 0,46 - a free term of the equation, in shares;
0.40 - coefficient, cm ³ / g;
ρ ₂₀ - density of raw materials at 20 ^o C, g / cm ³ .

В данном выражении расходы сырья, воздуха, топлива и плотность сырья - непрерывно измеряемые параметры процесса, коэффициенты f_т и f_с - постоянные величины для любых условий процесса.In view of (4), we finally obtain

In this expression, the costs of raw materials, air, fuel and the density of raw materials are continuously measured process parameters, the coefficients f _t and f _c are constant values for any process conditions.

 Thus, the proposed method provides a continuous measurement of the performance of the reactor.

In production practice, for the purpose of operational control of reactors, such an indicator is used as the percentage of soot on the missed raw material in percent
B = Q _p / G _c • 100, (6)
where B is the carbon black yield,%.

The proposed method allows to determine the yield of soot - In parallel with the performance of the reactor - Q _p , because the same input information is used.

 The drawing shows a schematic diagram that implements this control method.

The device contains a computing unit 1, sensors 2 - 4 of fuel, air and raw materials, respectively, a sensor 5 of the density of raw materials. The signals from the sensors 2 to 5 are continuously fed to the input of the computing device 1, and the values of the stoichiometric coefficients of complete fuel combustion f _t and incomplete combustion of raw carbon f _s are introduced, which are constant and are not further corrected. The computing unit according to equation (5) calculates the performance of the reactor.

 Example.

The control method was tested under industrial conditions of Yaroslavl Technical Carbon OJSC as part of an automated process control system (ACS TP). The density of the raw materials was measured by a mass flow meter - a KRONE densitometer installed on a common line for supplying raw materials to production. As a computing device, the Remicont 130 control controller was used, connected by a network to an industrial computer, on the monitor of which performance and output information was displayed in the form of numbers and continuous graphs. The value of the stoichiometric coefficient of incomplete combustion of carbon is adopted according to [5] and is equal to 0.93 nm ³ oxygen per kg of carbon. The stoichiometric coefficient of complete combustion of natural gas, which is used as fuel, is 9.52 nm ³ air / nm ³ natural gas. The values of the coefficients are adopted 0.46 and 0.40, respectively, as defined previously.

 In order to determine the accuracy of the method, special balance tests were carried out by accumulating soot in the finished product bin for a fixed period of time with further unloading and weighing. For the same period of time, the total consumption of raw materials was recorded. This is the true value of reactor productivity and product yield from raw materials. The results are tabulated.

 As can be seen from the test results, the relative calculation error does not exceed 1.5%, which is quite acceptable for operational management purposes. Using this method provides continuous monitoring of reactor performance at a pace with the process, which allows you to quickly adjust the technological mode and, ultimately, increase the efficiency of the reactor and the stability of the quality of the product.

Literature:
1. Production and properties of carbon black. Proceedings of VNIISP, Omsk, Zap.-Sib. Prince ed., 1972, p.223 and 224 - analogue.

 2. Copyright certificate of the USSR 899609, cl. C 09 C 1/52, 1982 - prototype.

 3. Austin O. Production of soot. On Sat Reinforcement of elastomers. Edited by Kraus D. - M .: Chemistry, 1968, p. 249.

 4. Gulmisaryan T.G., Gilyazetdinov L.P. Raw materials for the production of carbon furnace soot. - M .: Chemistry, 1975, 160 p.

 5. Zuev V.P., Mikhailov V.V. Soot production. - M., 1970, p. 22.

Claims (1)

A method for controlling the productivity of a carbon black reactor, including measuring the consumption of raw materials, air, fuel, characterized in that the density of the raw materials is additionally measured, stoichiometric coefficients of complete fuel combustion and incomplete combustion of raw carbon are introduced, using which the reactor productivity is determined by the expression

where Q _P - reactor productivity, kg / h;
G _with - consumption of raw materials, kg / h;
ρ ₂₀ - density of raw materials at 20 ^o C, g / cm ³ ;
G _In - air flow, nm ³ / h;
G _T - fuel consumption, nm ³ / h (kg / h for liquid fuel);
f _Т - stoichiometric coefficient of complete fuel combustion, nm ³ air / nm ³ natural gas (or per 1 kg of liquid fuel);
f _C - stoichiometric coefficient of incomplete combustion of carbon, nm ³ oxygen / kg carbon.

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