SU1271911A1 - Method of checking process of chemical heat treatment of metals in gas-circulation furnaces and device for effecting same - Google Patents

Abstract

The invention relates to the field of processes of diffusion saturation of the surface layer of metal products with elements that occur during thermal dissociation of gas, in particular, to gas nitriding processes. The purpose of the invention is to increase the reliability of the device. The method consists in that, at the operating temperature of the process, the value of

Description

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dynamic pressure of the circulating gas flow and calculate the density of the gas, reduced to a normal temperature, according to the formula p KTPa, while K is determined by the formula K 2 / T (jW2, where the density of the gas is at a normal temperature; T is the normal temperature; T is the operating temperature ; PQ is the dynamic pressure of the gas at the operating temperature; W is the gas flow rate. Ammonia is used as the dissociating gas, and the degree of dissociation is determined by the formula (100

  -Ro NH °. “- a degree of dissociation; p is the density of non-OH -1

co-produced ammonia under normal conditions. The invention relates to the diffusion treatment of the surface of metal products, specifically to controlling the processes of chemical heat treatment of metals with gases in furnaces equipped with fans with blades for the forced circulation of gas. The purpose of the invention is to simplify control at the process operating temperature and increase the reliability of the device for its implementation. The drawing shows a schematic diagram implementing the proposed control method. The control method consists in measuring the value of the dynamic pressure P „of the flow circulating in the furnace gas around the fan blades with an electric motor at the operating temperature of the process and calculates the gas density p (kg / m) reduced to the normal temperature T, K by the formula I KTP, De K --W - gas flow rate, m / s T - working temperature, K. The degree of dissociation of gas Y (%) is determined from the obtained density value. If ammonia is used as dissociating gas, then

71911

Claims (3)

Noah temperature. The control device consists of a unit for measuring the dynamic pressure of the gas flow at the fan blades, a signal supply unit 7 and a secondary measuring device, the dynamic pressure measuring unit being in the form of pneumometric tubes installed near the fan blades 8 of the torus 10 and a pressure sensor 6 connected to pneumometric tubes t, and the outputs of the pressure sensor and measuring transducer of a thermoelectric thermometer are connected (5 to the inputs of the signal multiplication unit, the output of which 1 ill. 00 V. (2) where I mts the density of undissociated ammonia at normal temperature, kg / m, the control device contains fan 1, as well as a thermoelectric thermometer (thermocouple) 2, thermometer measuring transducer 3 , pneumometric tubes 4 and 5, pressure sensor 6 and signal multiplication unit 7. Pneumatic tubes installed near fan blades 8 of fan 1, tube 4 perceives the total pressure of the circulating gas flow in the furnace 9, and tube 5 static pressure. A pressure sensor is differentially connected to the tubes and measures the magnitude of the dynamic gas pressure. The pneumometric tubes and the pressure sensor form a unit for measuring the dynamic pressure of the gas. The output of the pressure transducer of the thermoelectric thermometer measuring transducer is connected to the input of the signal multiplying unit, which acts in accordance with formula (1). A secondary device (not shown) is attached to the output of the signal multiplication unit, the scale of which is graduated according to formula (2). 3 Thus, the unit for measuring the dynamic gas pressure at the fan blades in combination with a thermoelectric thermometer measuring transducer, a signal multiplication unit and a secondary device develops a gas dissociation analyzer to monitor the process of chemical co-processing of metals. Claim 1. Method of controlling the process of chemical-thermal treatment of metals in gas-circulating furnaces, including temperature measurement and determination of the degree of gas dissociation in the furnace, which, in order to simplify control at the process working temperature, measure the dynamic pressure of the circulating gas flow and calculate the gas density, reduced to normal temperature, using the formula. RO KTR. , At the same time, k is determined by the formula t / - t W2 where P is the gas density at normal temperature; T is the working temperature of the process; R. — dynamic gas pressure at the working temperature; TQ is normal temperature. TO; W is the gas flow rate, 191 14 and the degree of gas dissociation is determined by the obtained density value, 2. Method POP.1, characterized in that ammonia is used as a dissociating gas, and the degree of dissociation is determined by the formula, NH3 where ot. - degree of dissociation,%; p is the density of undissociated ammonia at normal temperature. 3. A device for controlling the process of chemical heat treatment of metals in gas-circulating furnaces, which contains a fan and a thermoelectric thermometer, a measuring transducer for a thermoelectric thermometer, and a gas dissociation analyzer, characterized in that, to simplify the device and increase its reliability, the analyzer consists from the unit for measuring the dynamic pressure of the gas flow at the fan blades, the unit for multiplying the signals and the secondary measuring device, the unit for measuring the dynamic pressure The sensors are made in the form of pneumometric tubes installed near the fan blades and a pressure sensor connected to the pneumometric tubes, and the outputs of the pressure sensor and measuring transducer of a thermoelectric thermometer are connected to the inputs of the signal multiplying unit whose output is connected to the secondary measuring device.