# US 8,465,603 B2 · Method and device for controlling process gases for heat treatments of metallic materials/workpieces in industrial furnaces > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,465,603 B2 - Document ID: US8465603B2 - Status: Granted - Kind: B2 - Application number: 12/968,375 - Filed: 2010-12-15 - Published: 2011-06-16 - Granted: 2013-06-18 - Earliest claimed: 2009-12-16 - Assignees: Ipsen, Inc. - Applicants: Werner Hendrik Grobler; Thomas Eversmann; Bernd Edenhofer; Jens Bechthold; Dirk Joritz; Nils Bernhagen - Inventors: Werner Hendrik Grobler; Thomas Eversmann; Bernd Edenhofer; Jens Bechthold; Dirk Joritz; Nils Bernhagen - Web page: https://patentgrep.com/patent/US8465603B2 ## CPC - C21D 11/00: Process control or regulation for heat treatments - F27D 19/00: Arrangements of controlling devices - Y10T 137/0396: Involving pressure control - Y10T 137/7837: Direct response valves [i.e., check valve type] - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) - F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract For regulating process gases for heat treatments of metal materials/workpieces in industrial furnaces (1), which have at least one treatment chamber (2), at least one burnoff point (4) having at least one first valve (4.1), and a regulator (5) having pressure meter (5.1), the burnoff point (4) is only to be opened as a function of requirements related to the process gas. For this purpose, in a first step, with open first valve (4.1), a quantity of a flushing gas (6.1) of the gas mixture (6) of the respective process gas is supplied in a controlled manner to the industrial furnace (1) and then burned off, in a second step, the valve (4.1) is closed, the industrial furnace (1) is regulated to a preset furnace pressure and this is permanently detected via the pressure meter (5.1), in a third step, with the target pressure of the industrial furnace achieved, this pressure is detected via the pressure meter (5.1) and maintained, the first valve (4.1) further remaining closed. In a fourth step, the flushing gasification can be activated and adjusted. In the event of large pressure rise, in a fifth step, an overpressure flap (4.3) of the burnoff point (4) can be opened in a controlled manner via a fixed limiting value for pressure dissipation. ## Claims ### Claim 1 A method for controlling the flow of a process gas for the heat treatment of metal materials/workpieces in an industrial furnace (1), which has at least one treatment chamber (2), at least one burnoff point (4) having a first valve (4.1), and a regulator (5) having a pressure meter (5.1), wherein the process gas comprises a gas mixture (6) and is used as a flushing gas (6.1) and as a fresh gas (6.2), the method comprising the following steps: a) in a first step, with first valve (4.1) open, i) supplying a flow of the flushing gas (6.1) through a valve (7) to the industrial furnace (1), such that at least a portion of the flushing gas exits the industrial furnace through the first valve (4.1), and then ii) burning off the portion of the flushing gas that exits the industrial furnace through the first valve (4.1); b) in a second step, performed after said first step, closing the first valve (4.1) when a preset flushing time has elapsed or when a preselected carbon monoxide content is detected in the treatment chamber; and then c) in a third step, detecting a gas pressure in the industrial furnace and when a target gas pressure is detected, adjusting the valve (7) in such a way that a regulated flow of the process gas is provided as the fresh gas in a quantity sufficient to maintain the gas pressure in the furnace at or above the target gas pressure. ### Claim 2 (depends on 1) The method according to claim 1, wherein in the third step the gas pressure in the furnace is detected by the pressure meter (5.1) and the valve (7) is adjusted so that it provides a quantity of the fresh gas (6.2) which is sufficient for replacing a quantity of gas that has leaked from the furnace. ### Claim 3 (depends on 1) The method according to claim 1 wherein the first step is initiated before movement of a batch of the metal materials/workpieces into or from the treatment chamber (2). ### Claim 4 (depends on 1) The method according to claim 1, wherein an overpressure flap valve (4.3) of the burnoff point (4) is opened for pressure dissipation when the gas pressure in the furnace rises above a fixed limiting value. ### Claim 5 (depends on 1) The method according to claim 1 wherein when a carbon level is required for a heat treatment process, the carbon level in the treatment chamber is controlled using at least one carbon potential regulator (3) which operates to modify the gas mixture via a gas and air supply so that the required carbon level is achieved. ### Claim 6 (depends on 1) The method according to claim 1 wherein the heat treatment comprises batch-by-batch heat treatments of the metal materials/workpieces. ### Claim 7 (depends on 1) The method according to claim 1 wherein the method is carried out in a pusher furnace. ### Claim 8 (depends on 3) The method according to claim 3, wherein the first step is initiated before a batch change in the treatment chamber or before charging of a batch into the treatment chamber. ### Claim 9 (depends on 1) The method according to claim 1 wherein the first step is initiated by a furnace controller (9), in order to free the treatment chamber (2) from residues of foreign gases. ### Claim 10 (depends on 1) The method according to claim 1 which is applied in a protective gas recirculation system for a gas carburization process, and wherein components of the gas mixture comprise carbon dioxide, oxygen, and water vapor react with a supplied hydrocarbon to form carbon monoxide and hydrogen again in a recirculating manner. ### Claim 11 (depends on 4) The method according to claim 4 wherein the overpressure flap (4.3) is closed in a gastight manner as long as the gas pressure in the furnace is at or below the fixed limiting value. ### Claim 12 (depends on 1) The method according to claim 1 comprising the step of operating a hand slide (4.2) associated with a shutoff valve (4.4) to adjust the flushing gas flow, whereby the quantity of the flushing gas burned off is limited.