RU44980U1 - DEVICE FOR GAS START MANAGEMENT FOR NITROGEN - Google Patents

Abstract

The utility model relates to equipment for gas nitriding, and in particular to gas inlet control devices, and can be used to conduct controlled nitriding processes at engineering plants. The installation allows to obtain controlled atmospheres used in the thermal and chemical-thermal treatment of metals.

The objective of the utility model is to ensure environmental cleanliness due to the removal of exhaust gases to the afterburner with their preliminary decomposition in an additional chamber of the dissociator.

The problem is solved in that in a device for controlling a gas inlet for nitriding, containing a gas preparation system with an input for supplying ammonia and an output for connecting to the input of a nitriding furnace, through a mixing system including a dissociator made in the form of a furnace with a working chamber for decomposition ammonia, according to the proposed solution, a device for dissociation of exhaust gases leaving the furnace was introduced. For this, the dissociator has an additional chamber, the output of which is connected to the input of the afterburner, and the input is designed to connect to the output of the nitriding furnace.

The device may have an additional input for connecting to the diluent gas supply channel.

Description

The utility model relates to equipment for gas nitriding, and in particular to gas inlet control devices, and can be used to conduct controlled nitriding processes at engineering plants. The installation allows to obtain controlled atmospheres used in the thermal and chemical-thermal treatment of metals.

A known installation for nitriding containing a gas supply system, including a rotameter, dissociometer, pressure gauge and a water seal (see Yu.M. Lakhtin, Ya.D. Kogan, G.I.Shpis, 3.Bemer, Theory and technique of nitriding, ed. Metallurgy ”, Moscow, 1991, p. 10).

However, it does not allow for the utilization of waste gases and does not allow to solve environmental problems associated with ammonia entering the atmosphere.

A known installation for gas nitriding, including cylinders with shutoff valves, a supply pipe for supplying nitrogen-containing gas, a gas supply control system with a gas distribution device, as well as a furnace muffle which has a lid with a channel for the exit of exhaust gases and its afterburning. The installation is additionally equipped with a drying and purification unit for nitrogen-containing gas; a fixture with parts is placed in the cavity of the muffle of the nitriding furnace (see RF patent No. 2208659, IPC С 23 С 8/24).

However, with such an exhaust gas afterburning system, afterburning at the moment of heating and cooling the processed products cannot occur. In this case, the afterburning of undecomposed ammonia either does not occur at all, or leads to incomplete combustion and the formation of nitrogen oxides. In addition, when purging the muffle before unloading parts, an ammonia-air mixture can be created, which is explosive.

Closest to the proposed solution is a control system for the nitriding process SPR-901, including a discrete gas metering device to control the ratio of ammonia and dissociated ammonia in the atmosphere fed to the furnace. The system contains gas cylinders connected to a gas preparation system, which is connected through a discrete gas metering device to a dissociator and a nitriding furnace (ibid., P. 53, 36).

However, the nitriding process in this case also does not meet the environmental requirements, as it does not provide for the utilization of exhaust gases.

The objective of the utility model is to ensure environmental cleanliness due to the removal of exhaust gases to the afterburner with their preliminary decomposition in an additional chamber of the dissociator.

The problem is solved in that in a device for controlling a gas inlet for nitriding, containing a gas preparation system with an input for supplying ammonia and an output for connecting to the input of a nitriding furnace, through a mixing system including a dissociator made in the form of a furnace with a working chamber for decomposition ammonia, according to the proposed solution, a device for dissociation of exhaust gases leaving the furnace was introduced. For this, the dissociator has an additional chamber, the output of which is connected to the input of the afterburner, and the input is designed to connect to the output of the nitriding furnace.

The device may have an additional input for connecting to the diluent gas supply channel.

The gas inlet control device for nitriding comprises a gas supply control unit configured to change the composition of the gas to be supplied, a control device and temperature control of the dissociator, heating switches of the dissociator and afterburner, as well as gas supply modes, and the gas block contains a block of electromagnetic valves for regulating the flow gases and - a two-section water separator with valves for condensate drainage, pressure regulating devices for supplied gases, pressure gauges and rotameter.

The device contains a dissociometer for monitoring the concentration of ammonia in the exhaust gases.

The utility model is illustrated in the drawing, which shows the installation diagram for nitriding processes. The positions in the drawing indicate:

1. - a device for controlling gas inlet;

2. - input for connecting to the gas supply channel (ammonia);

3. - input for connecting to the diluent gas supply channel;

4. - inlet for exhaust gas;

5. - the output of the device for controlling the gas inlet;

6. - dissociator;

7. - the working chamber of the dissociator;

8. - input of the working chamber of the dissociator;

9. - output of the working chamber of the dissociator;

10. - a chamber of a dissociator for exhaust gases;

11. - input of the chamber of the dissociator for exhaust gases;

12. - the output of the chamber of the dissociator for exhaust gases;

13. - afterburner;

14. - input of the afterburner;

15. - furnace for nitriding;

16. - input of the nitriding furnace;

17. - exit of the nitriding furnace;

18. - gas supply control unit;

19. - gas block;

20. - solenoid valves of the gas block;

21. - a dissociometer;

22. - rotameter;

23. - gas bottle cabinet;

24. - compressed air supply unit (diluent gas);

25. - gearboxes;

26. - moisture separators;

27. - stopcocks;

28. - chokes.

The proposed device 1 for controlling the gas inlet contains a gas supply control unit 18 controlling electromagnetic valves 20, heating the dissociator 6, heating the spiral of the afterburner 13. The input 2 of the gas inlet control device 1 is connected to the gas cylinder cabinet 23, and the input 3 to the output of the diluent gas supply unit 24, for example compressed air. The output 5 of the device is designed to be connected to the input of the nitriding furnace 16. The gas supply control unit 18 and the gas unit 19 form a gas preparation system.

The gas block 19 consists of a front panel and an electromagnetic valve block located inside the frame, designed to open or close the gas channels for supplying ammonia or air. On the front panel are located a pressure reducing device (a reducer or a throttle 28) of ammonia for regulating the pressure of the supplied ammonia and a pressure reducing device (a reducer or a throttle 28) of diluent gas for regulating the pressure of the supplied diluent gas; manometers for monitoring the pressure of the gas supplied to the valve block 19; rotameter 22 for regulating the flow of gases supplied to the furnace.

The dissociometer 21 controls the concentration of ammonia in the atmosphere leaving the bed, the principle of operation is based on the ability of ammonia to dissolve in water. Consists of a water tank for accumulating water for subsequent measurements of the degree of dissociation,

tap to open or close the channel filling the water of the water tank and the measuring tube (not shown).

The dissociator 6 consists of a working chamber 7 and a chamber for dissociating (decomposing) the exhaust gases 10 with a heater, which is necessary to heat the chambers to a temperature at which the ammonia supplied to it decomposes on the surface of the metal placed inside the chambers to N ₂ and Н ₂ ; a cooled case and two covers for holding heat-insulating material and fixing the chambers; inlet and outlet water pipes, respectively, for supplying and discharging water cooling the outlet gas pipes; inlet and outlet gas pipes for supplying and discharging gases intended for decomposition. The cavity between the cameras and the housing is filled with insulating material. The dissociator is equipped with a temperature sensor (thermocouple) to control the temperature of its heater. The heater leads above and below are covered with protective covers.

The afterburner 13 is a cylindrical casing with an incandescent spiral inside, designed to ignite the utilized gas, as well as a nozzle with a flame extinguishing device that prevents gas ignition in the supply gas pipelines. In front of the afterburner there is a two-section moisture separator 26, designed to separate moisture from the gas mixture supplied for disposal. It is a two-chamber cylindrical tank with inlet and outlet fittings and valves for draining condensate

The gas supply control unit 18 is connected with the main functional blocks as follows: forms the time intervals of the operation of the electromagnetic valves 20 of the gas unit 19 (gas ratio setting board and power supply + 24V, + 5V); has a device for controlling the temperature of the dissociator 6 (for example, the IRT-5920 device); taking a signal from a temperature sensor, it gives a signal to turn on or off the dissociator heater or turns on an audible alarm when it overheats (a dissociator overheat signaling device powered by a + 24V + 5V power supply); feeds the spirals of the afterburner 13; feeds backlight bulbs measuring tube of the dissociometer 21.

The dissociator 6 is associated with the device afterburning gas line utilization of spent furnace atmosphere.

A device for controlling a gas inlet operates as follows. Technological gases (ammonia and diluent gas) are supplied to the inputs 2 and 3 of device 1. Gases through the throttles enter the solenoid valves 20 of the gas block 19, through which

is fed into the working zone of the furnace for nitriding 15 atmosphere of a given composition. The operation of the valves is provided by the gas supply control unit 18.

Control and regulation of the flow rate of the supplied gas is carried out by the rotameter 22 of the gas block.

The dissociometer 21 controls the concentration of ammonia in the atmosphere leaving the furnace 15.

The exhaust gas atmosphere is utilized by thermal decomposition in the chamber for dissociation of exhaust gases 10 and is fed through one of the sections of the two-section moisture separator 26 to the afterburner 13.

The working chamber 7 of the dissociator is designed to produce dissociated ammonia, which is then fed to the rotameter 22 in the working space of the furnace 15.

The task and control of the temperature inside the dissociator chambers is carried out by the IRT5920 "Dissociator temperature" thermal control device located in the gas supply control unit 18. The "Heating" switch activates the dissociator heating.

The “Afterburning spirals” switch activates the afterburning device spirals. The operation of the spirals is controlled visually and by the corresponding indicator of the gas supply control unit.

Claims (3)

1. A device for controlling a gas inlet for nitriding, having an inlet for supplying gas passing through a gas preparation system, including a dissociator made in the form of a furnace with a working chamber for decomposing ammonia, and an output for connecting to a nitriding furnace, characterized in that an exhaust gas afterburner was introduced to it, and the dissociator has an additional exhaust gas decomposition chamber connected to the outlet of the nitriding furnace and the entrance to the afterburner. 2. The device according to claim 1, characterized in that the additional chamber for the decomposition of exhaust gases is placed in a separate furnace. 3. The device according to claim 1, characterized in that the gas preparation system comprises a gas supply control unit configured to change the composition of the supplied gas, and the gas unit contains a pressure and flow control device for the supplied gases, electrically connected to the block of electromagnetic valves for regulating the gas supply .