SU1497432A1 - Method and apparatus for controlling carbon oixide afterburning - Google Patents

Abstract

The invention relates to metallurgical production, in particular to technical regulation solutions associated with processes occurring in furnaces, and is intended to regulate the process of afterburning of carbon monoxide. The aim of the invention is to increase the degree of post-combustion of carbon monoxide. To achieve the goal, the amount of O ₂ required for complete combustion of CO in the air is introduced into the measuring section of the gas duct by acting on the valve actuator of the main air supply pipeline according to the parameter of the difference in gas temperature at the inlet and outlet of the measuring section; % of air from its maximum flow rate, and also maintain the temperature difference between the inlet and outlet of the measuring section equal to zero impact on the actuator, when the temperature is exceeded The на at the outlet of the measuring section above the inlet temperature increases the air flow and vice versa. 2 sp of f-ly, 1 zp f-ly, 1 ill.

Description

The invention relates to metallurgical production, in particular to technical regulation solutions related to the process taking place in furnaces.

The purpose of the invention is to increase the degree of afterburning of carbon monoxide.

The drawing shows a device for carrying out the method.

The device contains a furnace 1, a flue 2 with a nozzle 3, as well as a measuring section 4, thermal sensors 5 and 6, a bypass (past the valve) pipeline 7 providing air flow of 3-7% of the flow rate with the valve open, regulator 8 of proportional action ( the laws of regulation P, PI, PD, PID are allowed, the actuator 9, the valve 10 on the air supply pipe 11 and the measuring section 4.

Sensors 5 and 6 are connected in a differential circuit and their total signal is fed to the input of the linear regulator 8, the output of regulator 8 is connected to the actuator 9 of valve 10. The bypass pipeline 7 is connected to the main air supply pipe 11 to the measuring section 4 of the duct 2 on the inlet and outlet located on the pipeline II valve 10.

The device works as follows.

The parameter used to control is the temperature difference between the input and output of the measuring section 4. The device maintains this difference equal to zero. At the same time, the afterburning process takes place as follows.

In the absence of CO in the gases departing from the furnace, constant flow into the measuring

four; about so

Section 4 of a small amount of cold air through the bypass line ensures that the signal of the thermal sensor 5 exceeds the signal of the thermal sensor 6, which causes the valve 10 to close. When it comes to waste, their CO gases are burned in the air supplied to the measuring section 4, which leads to an increase in the signal of the thermal sensor b and its excess over the signal of the thermal sensor 5. This opens the valve 10, increasing the air supply to the measuring section 4. An increase in the air supply occurs as long as During the combustion of CO, the heat will not completely dissipate the CO, and the temperature of the exhaust gases has not changed, which means that the air is supplied with an excess, i.e., all of the CO is burned, and the excess part (the part of which does not participate in the reaction) of the cold supplied air constant temperature of exhaust gases over the measuring section.

The device is simple and reliable, ensures complete combustion of CO and does not cause a rise in temperature at the site of afterburning of CO, which reduces the special requirements for its design, limits the air supply at quite specific values over the entire range of changes.

It is necessary to heat the supplied air to the air and to the flow of gases from the furnace.

the temperature of the exhaust gases at the outlet of the measuring section 4. In this case, the signals of the temperature sensors 5 and 6 are compared and a further increase in the air supply is stopped.

Guaranteeing a complete combustion of CO is based on the following.

Chemical formula for burning CO 2CO + O2 2CO2-f 135.2 kcal

In accordance with the above formula and taking into account the molecular weights of the reactants, if all the oxygen of the supplied air is involved in the reaction, we can write that 135.2 kcal is released to 32 g of oxygen. Taking into account that CO gas is part of the furnace gases, and therefore, it already reacts with the temperature measured at the inlet of the measuring section 4 to maintain the output temperature equal to the input, the entire heat of the reaction energy must go to heat the air.

Let us calculate the value of the increase in air temperature, all the oxygen of which entered into the reaction, in the case of consumption of the combustion energy of CO only for its heating.

Heat capacity of air, 244 kcal / /% deg.

The content (mass) of oxygen in the air is 23.2%.

Then

The supply of excess air cannot be considered a drawback in this device, since in the used gas exhaust systems of the furnaces it is still necessary to lower the temperature of the exhaust gases before the 20 gas cleaning devices by diluting them with air. However, immediately supplying large amounts of cold air can disrupt the burning of CO due to a sharp decrease in the temperature of the gases.

25

40

AT (, 7T

23.2% -135200 cal

50

32 g-100% -0.244 cal / hr

Since the temperature of the exhaust gases of the furnace lies within 900-2500 ° C, in order to maintain the equality of temperatures at the inlet and outlet of the measurement section when air is fed into it with a temperature of about 20-25 ° C, firstly, it is necessary that CO, and, secondly, that the air was supplied with an excess, which guarantees complete combustion of CO.

If there is a lack of oxygen in the air for complete combustion of CO from the exhaust gases, the released heat energy not only heats the supplied air, but also raises the temperature of the exhaust gases. If the formula of the invention

Claims (3)

1. A method for controlling the afterburning of carbon monoxide, preferably in a gas pipeline connected to the metallurgical unit, comprising supplying air to the main section of the gas duct depending on the temperature difference between the gas inlet and the output of the measuring gas duct, characterized in that In order to reduce the degree of post-combustion of carbon monoxide, in the measuring section of the flue, regardless of the gas temperature, 3-7% of air is continuously supplied from its maximum possible flow rate; ode measuring section above the temperature at its input gaz.a airflow proportionally increased, and if the temperature exceeds 4000 ° C above the inlet of the measuring section the gas temperature at its outlet air flow is proportionally reduced. 2. A device for controlling the afterburning of carbon monoxide, mainly in the duct connected to the metallurgical unit, containing the measuring section of the duct, thermal sensors installed at the inlet and outlet of the measuring section and connected in a differential circuit with a regulator, the main air supply line to the measuring section with the installed on it is a valve with 55 an actuator coupled to the regulator, characterized in that, in order to increase the degree of afterburning of carbon monoxide, it additionally contains the waste and the flow of gases from the furnace. The supply of excess air cannot be considered a drawback in this device, since in the used gas exhaust systems of the furnaces it is all the same to lower the temperature of the exhaust gases before the gas cleaning devices by diluting them with air. However, immediately supplying large amounts of cold air can disrupt the burning of CO due to a sharp decrease in the temperature of the gases. water pipeline, with a bypass pipe connected to the main pipe at the inlet and outlet of the air supply valve. 3. A device according to claim 2, characterized in that a proportional controller is used as a controller.