Active hydrogen measurement system with pressure difference

Abstract

Kn controlled gas nitriding process is a thermo-chemical surface treatment applied to many steel materials in industry (automotive, machinery, mold industry, aerospace, etc). In the gas nitration process, Kn constant is used for repetitive processes. The gas flow rate to be fed to the furnace is adjusted according to the Kn constant. In order to calculate the Kn constant, it is necessary to measure the 0 % hydrogen (H2) value in the gas atmosphere. The present invention relates to an active hydrogen measurement system with pressure difference for measuring the variability of hydrogen (H2) gas % in the continuously cycling gas atmosphere of gas nitration furnaces where the process is applied and for process control.

Description

[0001] ACTIVE HYDROGEN MEASUREMENT SYSTEM WITH PRESSURE DIFFERENCE

[0002] TECHNICAL FIELD

[0003] Kn controlled gas nitration process is a thermo-chemical surface treatment applied to many steel materials in industry (automotive, machinery, mold industry, aerospace, etc.). In the gas nitration process, Kn constant is used for repetitive processes. The gas flow rate to be fed to the furnace is adjusted according to the Kn constant. In order to calculate the Kn constant, it is necessary to measure the % hydrogen (H2) value in the gas atmosphere. The present invention relates to an active hydrogen measurement system with pressure difference for measuring the variability of hydrogen (H2) gas % in the continuously cycling gas atmosphere of gas nitration furnaces where the process is applied and for process control.

[0004] BACKGROUND ART

[0005] In the state of the art, Kn-controlled gas nitration furnaces use ammonia gas (NH3) as the active process gas. Ammonia (NH3) gas decomposes into nitrogen (N2) and hydrogen (H2) on the metal surface with temperature. Atomic nitrogen (N2) released as a result of decomposition diffuses into the steel, while hydrogen (H2) and some undegraded ammonia (NH3) are discharged through the exhaust. The released hydrogen (H2) is measured with the help of a sensor and used to calculate the process constant Kn. Ammonia (NHS) gas is fed to the system manually or automatically at variable flow rates intermittently and / or continuously by on / off valve and / or flow control device according to the Kn set value required by the process.

[0006] The known state of the art includes the following technical problems:

[0007] During the process, the internal pressure cannot be managed due to the variable gas input fed to the system to manage the active Kn set.

[0008] Increase of surface area depending on variable process demand and / or the increase of ammonia (NH3) demand as a requirement of the process causes the ammonia (NH3) gas entering the furnace to be continuously discharged from the exhaust without contacting the metal surface (without decomposing on the surface). This makes active furnace internal pressure management, active hydrogen (H2) reading and process control difficult and increases ammonia (NH3) consumption.

[0009] The problems mentioned above have made it necessary to make a new improvement.

[0010] DESCRIPTION OF THE INVENTION

[0011] The present invention relates to an active hydrogen measurement system with pressure difference for measuring the variability of hydrogen (H2) gas % in the continuously cycling gas atmosphere of gas nitration furnaces where the process is applied and for process control, in order to eliminate the disadvantages mentioned above and to bring new advantages to the relevant technical field.

[0012] In order to manage the Kn set in Kn-controlled gas nitration furnaces and to measure the active hydrogen value, a system was developed that passes the furnace atmosphere, which changes with the pressure difference method, in front of the hydrogen sensor and allows the gas decomposed on the surface to exit the exhaust in a controlled manner. The circulation fan and hydrogen measurement collector create differential pressure (P1 >P2) and the active hydrogen (H2) value is read very quickly. The required variable flow rate of ammonia (NH3) gas is controlled by the MFC (flow control device) at the inlet and the valve in the exhaust line at the outlet depending on the internal pressure and software algorithm.

[0013] According to the software algorithm, ammonia (NH3) gas is completely decomposed on the surface by holding at pressure without exhausting at variable flow rates. Hydrogen (H2) measurement is actively performed with the differential pressure created in the furnace after complete decomposition. Active hydrogen (H2) measurement with differential pressure and software control provides excellent Kn control in variable processes and efficient gas utilization / consumption.

[0014] The advantages of the invention are listed below:

[0015] In the variable atmosphere, fast and active % hydrogen (H2) measurement can be performed and only the ammonia gas required by the process is sufficient. With % hydrogen (H2) measurement, variable flow rate, internal pressure and software management, the active calculation of the nitration constant Kn value and thus the gas supply response time has accelerated. Stable and repetitive processes are created by actively calculating and managing Kn. Precise results were obtained for the variable processes required by different sectors.

[0016] The active hydrogen measurement system with pressure difference according to the invention can be manufactured in different sizes, larger and smaller, and in different dimensions.

[0017] Brief Description of Drawings

[0018] The embodiments of the present disclosure which are summarized above and discussed in more detail below can be better understood by referring to exemplary embodiments of the present disclosure illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings only describe the typical embodiments of the present disclosure, and thus, are not to be considered as limiting the scope of the present disclosure such that other effective embodiments may also be within the scope of the present disclosure.

[0019] Figure-1 : The view of the furnace in which the invention is used.

[0020] Figure-2: The view of an active hydrogen measurement system with pressure difference.

[0021] Figure-3: A close-up view of the Hydrogen measurement collector in the invention. For ease of understanding, identical reference numerals are used where possible to indicate identical elements in the figures. Figures are not drawn to scale and can be simplified for clarity. It is contemplated that elements and features of an embodiment can be usefully incorporated into other embodiments without the need for further explanation.

[0022] Description of Details in Drawings

[0023] Described herein are the reference numbers shown in the figures.

[0024] 10. Circulation Fan

[0025] 20. Crucible

[0026] 30. Inner crucible

[0027] 40. Hydrogen measurement collector

[0028] 50. Hydrogen sensor

[0029] 61 . Pressure transmitter

[0030] 62. Pressure Limit switch

[0031] 70. Exhaust valve

[0032] 80. Safety vent

[0033] 90. Exhaust system

[0034] 100. Pilot burner

[0035] DETAILED DESCRIPTION OF THE INVENTION

[0036] The preferred alternatives of the embodiment of the active hydrogen measurement system with pressure difference of invention, which are mentioned in this detailed description, are only intended for providing a better understanding of the subject-matter, and should not be construed in any restrictive sense.

[0037] The invention relates to an active hydrogen measurement system with pressure difference and includes a hydrogen measurement collector (40), hydrogen sensor (50), pressure transmitter (61 ), pressure limit switch (62), exhaust valve (70), safety vent (80) as shown in Figure 1-3. Circulation Fan (10) provides gas and heat flow in the closed loop crucible. During operation, it creates a pressure difference at the inlet and outlet of the hydrogen measurement collector (40).

[0038] The crucible (20) is a closed vessel made of stainless steel in which the materials to be charged are placed, the gas atmosphere is provided, and the process gases are fed into it.

[0039] The inner crucible (30) is the structure through which the flow in the crucible (20) is directed. Temperature homogeneity is the necessary structure for healthy gas circulation and differential pressure. Inner pot (30) is also called a shirt.

[0040] Hydrogen measurement collector (40) is the structure to which the hydrogen sensor (50) and pressure transmitters (61 ), which act as pressure sensors, are connected and which is designed in accordance with the system. Differential pressure is created at the inlet and outlet, allowing the gas to flow through it. As the gas passes through this hydrogen measurement collector (40), it is measured with the help of the hydrogen sensor (50) located on it. The hydrogen measurement collector (40) includes hydrogen sensor (50), pressure transmitter (61 ) and pressure limit switches (62).

[0041] The hydrogen sensor (50) is the sensor that measures the % hydrogen in the atmosphere. Olgulen hidrojen verisine gore de Kn kontrol edilmektedir.

[0042] The pressure transmitter (61 ) is a device that instantaneously measures the pressure change in the crucible (20).

[0043] Pressure Limit Switch (62) is the device where safety pressure maximum and minimum limits are set. It is used to cut off the gas completely in case of exceeding the limit. The word "switch" in the pressure limit switch (62) means "switch," i.e. "interrupter" in English. The exhaust valve (70), which is the valve that allows the gas to be held in the crucible (20) or discharged from the exhaust system (90) depending on the pressure, according to the software algorithm.

[0044] Safety vent (80) is a safety valve used for relief with preset mechanical spring pressure in case of excessive internal pressure.

[0045] Exhaust system (90) is the system that allows the combustion of the fractionated gas.

[0046] Pilot burner (100) is exhaust burner.

[0047] This measurement system was developed to actively and rapidly measure the variability of the gas atmosphere inside the furnace or structures where a closed- cycle gas atmosphere is created by means of a forced circulation with the help of a circulation fan (10).

[0048] The % hydrogen gas (H2) in the furnace crucible (20), whose temperature is managed (in the range 480 - 595°C), determines the value of Kn, which is considered the nitration constant for the nitration process. Therefore, in order to keep the %hydrogen gas (H2) constant in the recirculating atmosphere according to the Kn set value defined in the furnace recipe, the ammonia gas (NH3) flow rate is managed by the software algorithm with the flow control device (MFC) at the inlet and the exhaust valve (70) in the exhaust line at the outlet depending on the variable internal pressure. According to the software algorithm, it is ensured that the ammonia gas (NH3) is removed from the exhaust system (90) by holding at pressure without exhausting at variable flow rates and by complete decomposition thereof on the surface.

[0049] The internal pressure of the crucible (20) is limited by pressure limit switches (62) and measured throughout the process by pressure transmitters (61 ). In case of overpressure, the exhaust valve (70) and safety vent (80) are activated. The exhaust gases are combusted by the pilot burner (100) in the exhaust system (90).

[0050] As a result of the operation of the circulation fan (10) positioned inside the crucible (20) and inner crucible (30) structure throughout the process, a continuous pressure difference is created between the inlet and outlet of the hydrogen measurement collector (40). This pressure difference allows the circulating hydrogen (H2) atmosphere to be actively measured by the hydrogen sensor (50) connected to the hydrogen measurement collector (40).

[0051] As a result, the nitration process constant Kn is actively calculated and managed.

Claims

CLAIMS1- An active hydrogen measurement system with pressure difference for measuring the variability of hydrogen (H2) gas and for process control, characterized in that it includes:- Circulation fan (10), which provides gas and heat flow in the closed loop crucible and creates a pressure difference at the inlet and outlet of the hydrogen measurement collector (40) as long as it operates,- Hydrogen measurement collector (40) to which the hydrogen sensor (50) and pressure transmitters (61 ), which act as pressure sensors, are connected and through which the gas flows by creating differential pressure at the inlet and outlet,- The exhaust valve (70), which is the valve that allows the gas to be held in the crucible (20) or discharged from the exhaust system (90) depending on the pressure, according to the software algorithm,- Safety vent (80), i.e. safety valve used for relief with preset mechanical spring pressure in case of excessive internal pressure.2- The hydrogen measurement collector (40) according to claim 1 , characterized in that it includes hydrogen sensor (50), which is a sensor that measures hydrogen in the atmosphere in %, where the Kn value is controlled according to the measured hydrogen data, pressure transmitter (61 ), which is a device that instantly measures the change in pressure in the crucible (20), pressure limit switch (62), which is a device that determines the maximum and minimum limits of the safety pressure and provides pressure cut-off in case of exceeding the limit.

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