阅读说明：本技术 一种不锈钢管热处理炉的氧化还原保护装置 (Oxidation-reduction protection device of stainless steel tube heat treatment furnace ) 是由 曹丽琴 张红升 周艳萍 陈端 梁鸿 赵元 于 2019-11-08 设计创作，主要内容包括：本发明公开了一种不锈钢管热处理炉的氧化还原保护装置,属于热处理炉装置的气体保护技术领域,包括热处理炉、氢气储罐、氦气储罐、氢气管道、氦气管道及控制回路；氢气储罐通过氢气管道连接于三通阀的A进口；氦气储罐通过氦气管道连接于三通阀的B进口；三通阀的出口端与热处理炉连通；三通阀和氢气储罐之间的氢气管道上依次设置有电动闸阀A和电动调节阀；氦气管道上设置有电动闸阀B；控制回路包括控制炉内氧气含量的反馈控制系统、控制氢气管道内氢气流量的前馈控制系统和分程控制系统,通过三个控制系统的综合调控,本发明可以保证不锈钢管热处理时不被氧化,保证根据炉内氧气含量使用氢气的经济性,杜绝了氢气爆炸的可能性。(The invention discloses an oxidation-reduction protection device of a stainless steel tube heat treatment furnace, belonging to the technical field of gas protection of heat treatment furnace devices, and comprising a heat treatment furnace, a hydrogen storage tank, a helium storage tank, a hydrogen pipeline, a helium pipeline and a control loop; the hydrogen storage tank is connected with an inlet A of the three-way valve through a hydrogen pipeline; the helium storage tank is connected to the inlet B of the three-way valve through a helium pipeline; the outlet end of the three-way valve is communicated with the heat treatment furnace; an electric gate valve A and an electric regulating valve are sequentially arranged on a hydrogen pipeline between the three-way valve and the hydrogen storage tank; an electric gate valve B is arranged on the helium pipeline; the control loop comprises a feedback control system for controlling the oxygen content in the furnace, a feedforward control system for controlling the hydrogen flow in the hydrogen pipeline and a branch control system, and the invention can ensure that the stainless steel pipe is not oxidized during heat treatment through the comprehensive regulation and control of the three control systems, ensure the economy of using hydrogen according to the oxygen content in the furnace and stop the possibility of hydrogen explosion.)

1. The utility model provides a nonrust steel pipe heat treatment furnace's redox protection device, includes heat treatment furnace (1), hydrogen storage tank (2), helium storage tank (3), hydrogen pipeline (16), helium pipeline (17) and control circuit, its characterized in that: the hydrogen storage tank (2) is connected to an inlet A of the three-way valve (12) through a hydrogen pipeline (16), and the helium storage tank (3) is connected to an inlet B of the three-way valve (12) through a helium pipeline (17); the outlet end of the three-way valve (12) is communicated with the heat treatment furnace (1); an electric gate valve A (13) and an electric regulating valve (14) are sequentially arranged on a hydrogen pipeline (16) between the three-way valve (12) and the hydrogen storage tank (2); an electric gate valve B (15) is arranged on the helium pipeline (17); the control loop comprises a feedback control system for controlling the oxygen content in the heat treatment furnace (1), a feedforward control system for controlling the hydrogen flow and a branch control system.

2. The oxidation-reduction protection device for a stainless steel pipe heat treatment furnace according to claim 1, characterized in that: the feedback control system comprises an oxygen measuring sensor (4) which is arranged at the upper end of the heat treatment furnace (1) and is used for measuring the oxygen content in the heat treatment furnace (1); the oxygen measuring transmitter (5) is connected with the oxygen measuring sensor (4) and the flow controller (6), receives a measuring signal sent by the oxygen measuring sensor (4), and converts the measuring signal into a standard signal which can be recognized by the flow controller (6); and a flow controller (6) connected to the electric control valve (14) and controlling the opening of the electric control valve (14).

3. The oxidation-reduction protection device for a stainless steel pipe heat treatment furnace according to claim 1, characterized in that: the feedforward control system comprises a flow measurement sensor (8) which is installed on a hydrogen pipeline (16) between a hydrogen storage tank (2) and an electric regulating valve (14) and measures the hydrogen flow in the hydrogen pipeline (16); and the flow measuring transmitter (7) is connected with the flow measuring sensor (8) and the flow controller (6) and receives a measuring signal sent by the flow measuring sensor (8) and converts the measuring signal into a standard signal which can be recognized by the flow controller (6).

4. The oxidation-reduction protection device for a stainless steel pipe heat treatment furnace according to claim 1, characterized in that: the range control system comprises a pressure measuring sensor (9) which is arranged at the lower end of the heat treatment furnace (1) and is used for measuring the pressure in the heat treatment furnace (1); the pressure measurement transmitter (10) is connected with the pressure measurement sensor (9) and the pressure controller (11), receives a measurement signal sent by the pressure measurement sensor (9), and converts the measurement signal into a standard signal which can be recognized by the pressure controller (11); and a pressure controller (11) connected in parallel to the electric gate valve A (13) and the electric gate valve B (15) and controlling the electric gate valve A (13) and the electric gate valve B (15).

5. The oxidation-reduction protection device for a stainless steel pipe heat treatment furnace according to claim 2, characterized in that: the oxygen measuring transducer (5) converts the measuring signal into a standard signal of 4-20 mA.

6. The oxidation-reduction protection device for a stainless steel pipe heat treatment furnace according to claim 3, characterized in that: the flow measurement transmitter (7) converts the measurement signal into a standard signal of 4-20 mA.

7. The oxidation-reduction protection device for a stainless steel pipe heat treatment furnace according to claim 4, characterized in that: the pressure measuring transducer (10) converts the measurement signal into a 4-20mA standard signal.

Technical Field

The invention relates to the technical field of gas protection of heat treatment furnace devices, in particular to an oxidation-reduction protection device of a stainless steel tube heat treatment furnace.

Background

Austenitic stainless steel is a special steel containing many alloying elements, and the original uniform austenitic structure is changed whether the steel pipe is manufactured by hot extrusion or cold drawing. In order to restore the original grain structure, the formed stainless steel pipe needs to be heat-treated to restore the austenitic structure. During the heating and heat preservation of the stainless steel pipe, if oxygen in air enters the surface, black oxide scales appear. In order to make the workpiece brighter and silvery white and improve the smoothness of the substrate, the steel pipe is ideally heat-treated in a vacuum furnace, and the greatest advantage of vacuum heat treatment is that a good bright surface can be obtained. However, since the chromium removal phenomenon occurs during the vacuum heat treatment of stainless steel, the corrosion resistance is remarkably reduced, and the continuous heat treatment of stainless steel pipes is not easily performed in a vacuum furnace, it is difficult to use the vacuum furnace in industrial production. In order to realize continuous heat treatment, particularly for steel pipes requiring high performance such as nuclear power plants, heat treatment can be carried out using high-purity hydrogen gas having a purity of 99.99% as a shielding gas. In the hydrogen-protected continuous heat treatment furnace, hydrogen can be combusted by oxygen in the air in the furnace to exhaust oxygen in a hearth. Meanwhile, the surface of the stainless steel inevitably produces slight oxides during continuous heat treatment, and because hydrogen is reducing gas, the hydrogen can react with the oxides at high temperature, so that the effect of removing the oxides on the surface of the stainless steel pipe is achieved.

The hydrogen gas has explosive property besides consuming oxygen in the furnace according to flammable property. When the hydrogen amount in the heat treatment furnace is excessively accumulated, the combustion speed reaches the level of detonation, explosion occurs, and if the hydrogen amount is excessively small, the protection and reduction effects on the surface of the stainless steel are weakened, and the product quality is reduced. In addition, the prior art method cannot fundamentally avoid the explosion danger, and the explosion event of the heat treatment furnace is larger or smaller from time to time.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a gas protection device for controlling the oxygen content in a heat treatment furnace and keeping the hydrogen content in the heat treatment furnace stable and adjusting in real time, and the oxidation reduction protection device of the stainless steel tube heat treatment furnace is provided with a safe standby loop.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

the utility model provides a nonrust steel pipe heat treatment furnace's redox protection device, includes heat treatment furnace, hydrogen storage tank, helium storage tank, hydrogen pipeline, helium pipeline and control circuit, its characterized in that: the hydrogen storage tank is connected to the inlet A of the three-way valve through a hydrogen pipeline, and the helium storage tank is connected to the inlet B of the three-way valve through a helium pipeline; the outlet end of the three-way valve is communicated with the heat treatment furnace; an electric gate valve A and an electric regulating valve are sequentially arranged on a hydrogen pipeline between the three-way valve and the hydrogen storage tank; an electric gate valve B is arranged on the helium pipeline; the control loop comprises a feedback control system for controlling the oxygen content in the heat treatment furnace, a feedforward control system for controlling the hydrogen flow and a branch control system.

The technical scheme of the invention is further improved as follows: the feedback control system comprises an oxygen measuring sensor which is arranged at the upper end of the heat treatment furnace and is used for measuring the oxygen content in the heat treatment furnace; the oxygen measuring transducer is connected with the oxygen measuring sensor and the flow controller, receives the measuring signal sent by the oxygen measuring sensor and converts the measuring signal into a standard signal which can be identified by the flow controller; and the flow controller is connected with the electric regulating valve and controls the opening of the electric regulating valve.

The technical scheme of the invention is further improved as follows: the feed-forward control system comprises a flow measurement sensor which is arranged on a hydrogen pipeline between the hydrogen storage tank and the electric regulating valve and measures the hydrogen flow in the hydrogen pipeline; and the flow measuring transmitter is connected with the flow measuring sensor and the flow controller, receives a measuring signal sent by the flow measuring sensor, and converts the measuring signal into a standard signal which can be identified by the flow controller.

The technical scheme of the invention is further improved as follows: the range control system comprises a pressure measuring sensor which is arranged at the lower end of the heat treatment furnace and is used for measuring the pressure in the heat treatment furnace; the pressure measuring transmitter is connected with the pressure measuring sensor and the pressure controller, receives a measuring signal sent by the pressure measuring sensor, and converts the measuring signal into a standard signal which can be recognized by the pressure controller; and a pressure controller connected in parallel to the electric gate valve A and the electric gate valve B and controlling the electric gate valve A and the electric gate valve B.

The technical scheme of the invention is further improved as follows: the oxygen measurement transducer converts the measurement signal to a 4-20mA standard signal.

The technical scheme of the invention is further improved as follows: the flow measuring transducer converts the measurement signal into a standard signal of 4-20 mA.

The technical scheme of the invention is further improved as follows: the pressure measuring transducer converts the measuring signal into a standard signal of 4-20 mA.

Due to the adoption of the technical scheme, the invention has the technical progress that:

1. the invention adopts the feedback control system, when the oxygen content in the hearth of the heat treatment furnace is too high, the opening of the electric regulating valve is increased according to the Proportional Integral (PI) rule in the PID control rule, so that the amount of hydrogen entering the hearth of the heat treatment furnace can quickly balance the increase of oxygen, and the residual difference can be eliminated due to the integral condition, thereby realizing the real-time and accurate control of the oxygen in the heat treatment furnace and avoiding the oxidation of a stainless steel pipe; similarly, when the oxygen content in the hearth of the heat treatment furnace is reduced and the given hydrogen cannot be completely combusted, the opening of the electric regulating valve is reduced by adopting the same method to reduce the introduced hydrogen amount so as to prevent the danger caused by excessive accumulation of the hydrogen in the furnace.

2. The invention adopts a feedforward control system, and when the pressure in the hydrogen storage tank fluctuates due to temperature change or storage quantity change of the hydrogen storage tank, so that the hydrogen flow in the hydrogen pipeline fluctuates, the opening of the electric regulating valve can be quickly adjusted, so that the stability of the hydrogen pipeline flow is ensured.

3. The invention adopts a split-range control system, a hydrogen loop is set as a main loop, and a helium loop is set as a standby loop for ensuring safety; in a normal working state, the hydrogen pipeline of the main loop is in an open state, and the helium standby loop is in a closed state; when the pressure in the furnace is too low, the loop is switched to close the main loop and open the standby loop, and a large amount of protective inert gas helium is rapidly introduced into the hearth to prevent explosion hazard.

4. The invention can ensure that the stainless steel pipe is not oxidized during heat treatment, can ensure that hydrogen is used in a proper amount according to the oxygen content in the furnace, has high economy, simultaneously ensures that hydrogen aggregation does not occur in the furnace, stops the possibility of hydrogen explosion, and has great popularization prospect and social requirements.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a control block diagram of the feedback control loop of the present invention;

FIG. 3 is a control block diagram of the feedforward control loop of the present invention;

FIG. 4 is a control block diagram of the split-range control loop of the present invention.

The system comprises a heat treatment furnace 1, a hydrogen storage tank 2, a helium storage tank 3, an oxygen measurement sensor 4, an oxygen measurement transmitter 5, an oxygen measurement transmitter 6, a flow controller 7, a flow measurement transmitter 8, a flow measurement sensor 9, a pressure measurement sensor 10, a pressure measurement transmitter 11, a pressure controller 12, a three-way valve 13, an electric gate valve A, 14, an electric regulating valve 15, an electric gate valve B, 16, a hydrogen pipeline 17 and a helium pipeline.

Detailed Description

The invention is described in further detail below with reference to the following figures and examples:

an oxidation-reduction protection device of a stainless steel tube heat treatment furnace comprises a heat treatment furnace 1, a hydrogen storage tank 2, a helium storage tank 3, a hydrogen pipeline 16, a helium pipeline 17 and a control loop; the hydrogen storage tank 2 is connected to an inlet A of the three-way valve 12 through a hydrogen pipeline 16, and the helium storage tank 3 is connected to an inlet B of the three-way valve 12 through a helium pipeline 17; the outlet end of the three-way valve 12 is communicated with the heat treatment furnace 1; an electric gate valve A13 and an electric regulating valve 14 are sequentially arranged on a hydrogen pipeline 16 between the three-way valve 12 and the hydrogen storage tank 2; an electric gate valve B15 is arranged on the helium pipeline 17; the control loop comprises a feedback control system for controlling the oxygen content in the heat treatment furnace 1, a feedforward control system for controlling the hydrogen flow and a branch control system.

The feedback control system comprises an oxygen measuring sensor 4 which is arranged at the upper end of the heat treatment furnace 1 and is used for measuring the oxygen content in the heat treatment furnace 1; an oxygen measuring transmitter 5 which is connected with the oxygen measuring sensor 4 and the flow controller 6, receives the measuring signal sent by the oxygen measuring sensor 4, and converts the measuring signal into a 4-20mA standard signal which can be identified by the flow controller 6; and a flow rate controller 6 connected to the electric control valve 14 and controlling the opening of the electric control valve 14.

The feed forward control system includes a flow measurement sensor 8 that is installed on a hydrogen pipe 16 between the hydrogen tank 2 and the electric regulator valve 14 and measures the hydrogen flow rate in the hydrogen pipe 16; and the flow measuring transmitter 7 is connected with the flow measuring sensor 8 and the flow controller 6, receives the measuring signal sent by the flow measuring sensor 8, and converts the measuring signal into a standard signal of 4-20mA which can be identified by the flow controller 6.

The range control system comprises a pressure measuring sensor 9 which is arranged at the lower end of the heat treatment furnace 1 and is used for measuring the pressure in the heat treatment furnace 1; the pressure measurement transmitter 10 is connected with the pressure measurement sensor 9 and the pressure controller 11, receives the measurement signal sent by the pressure measurement sensor 9, and converts the measurement signal into a standard signal of 4-20mA which can be identified by the pressure controller 11; and a pressure controller 11 connected in parallel to the electric gate valve a13 and the electric gate valve B15 and controlling the electric gate valve a13 and the electric gate valve B15.

Specifically, as shown in fig. 1, the oxidation-reduction protection device for the stainless steel tube heat treatment furnace comprises a heat treatment furnace 1, a hydrogen storage tank 2, a helium storage tank 3, an oxygen measurement sensor 4, an oxygen measurement transmitter 5, a flow controller 6, a flow measurement transmitter 7, a flow measurement sensor 8, a pressure measurement sensor 9, a pressure measurement transmitter 10, a pressure controller 11, a three-way valve 12, an electric gate valve a13, an electric control valve 14, an electric gate valve B15, a hydrogen pipeline 16 and a helium pipeline 17; the lines with directional arrows in the figure, the solid line part is the actual gas pipeline, and the dashed line part is the control loop.

The gas pipeline is mainly divided into a hydrogen loop and a helium loop, the flowing direction of the hydrogen loop and the helium loop is fixed, wherein the internal pressure of the storage tank is used as a power source, and the hydrogen loop is used for transmitting hydrogen from the hydrogen storage tank 2 to the heat treatment furnace 1 in a normal working state; and (3) starting a standby loop to transmit helium gas from the helium gas storage tank 3 to the heat treatment furnace 1 under the abnormal working condition of over-low pressure in the furnace.

The whole system adopts a feedforward, feedback and split-range control system, wherein the feedback control loop can realize the inhibition of the oxygen content in the heat treatment furnace 1 by adjusting the hydrogen amount input into the heat treatment furnace 1; the feedforward control loop restrains the fluctuation of the hydrogen flow in the hydrogen pipeline 16 by adjusting the opening of the electric regulating valve 14 so as to ensure that the hydrogen input into the heat treatment furnace 1 is matched with the oxygen content in the furnace; on the basis of feed-forward and feedback control, a split-range control loop is added to ensure explosion danger caused by too low pressure in the heat treatment furnace 1.

Specifically, the oxygen measuring sensor 4 measures the oxygen content in the heat treatment furnace 1, then transmits a measuring signal to the oxygen measuring transmitter 5, and converts the measuring signal into a 4-20mA standard signal which can be identified by the flow controller 6; the flow measurement sensor 8 measures the hydrogen flow in the hydrogen pipeline 16, then transmits a measurement signal to the flow measurement transmitter 7 and converts the measurement signal into a standard signal of 4-20mA, which can be identified by the flow controller 6; the flow controller 6 takes the comprehensive result as the input value of the flow controller 6 according to the input value transmitted by the oxygen measuring transmitter 5 and referring to the fluctuation condition of the flow in the pipeline provided by the flow measuring transmitter 7, and then the flow controller 6 calculates the output value according to a given control rule to determine the opening change of the electric regulating valve 14 so as to ensure that the hydrogen input into the heat treatment furnace 1 can exhaust oxygen and reduce the oxide on the surface of the stainless steel pipe, and excessive residual hydrogen is not generated.

The oxygen measuring transducer 5 converts the measuring signal of the oxygen content into a standard electric signal, compares the standard electric signal with a set value in the flow controller 6, obtains a difference value as an input value of the flow controller 6, and then the flow controller 6 calculates an output value according to the input value, wherein the output value is used for controlling the opening of the electric regulating valve 14 so as to ensure that the hydrogen amount entering the heat treatment furnace is matched with the oxygen content in the heat treatment furnace 1.

The flow measurement transmitter 7 converts the measurement signal of the hydrogen flow into a standard electrical signal, compares the standard electrical signal with a set value in the flow controller 6, and uses the obtained difference value as an input value of the flow controller 6, and then the flow controller 6 calculates an output value according to the input value, wherein the output value is used for controlling the opening of the electric control valve 14 so as to ensure the stability of the hydrogen flow.

The pressure measuring sensor 9 measures the pressure change in the heat treatment furnace 1, then transmits a measuring signal to the pressure measuring transmitter 10 and converts the measuring signal into a standard signal of 4-20mA, which can be identified by the pressure controller 11; the pressure controller 11 compares the input value transmitted by the pressure measurement transmitter 10 with a set value, the difference value is used as the input value of the pressure controller 11, then the pressure controller 11 determines whether the furnace has the explosion risk according to the deviation, when the explosion risk exists, the process loop is switched to a standby loop, helium is rapidly introduced into the heat treatment furnace 1, and the safety in the furnace is ensured.

The pressure measurement transmitter 10 converts the pressure measurement signal in the furnace into a standard electrical signal, compares the standard electrical signal with a set value in the pressure controller 11, and uses the obtained difference value as an input value of the pressure controller 11, and then the pressure controller 11 calculates an output value according to the input value, wherein the output value is used for determining whether the electric gate valve a is fully opened and the electric gate valve B is fully closed, or whether the electric gate valve a is fully closed and the electric gate valve B is fully opened, so as to determine whether hydrogen gas or inert gas helium gas flows into the furnace.

The control scheme of the system is as follows:

in order to prevent the stainless steel pipe from being oxidized in the heat treatment furnace 1, the supply amount of the hydrogen gas can be adjusted according to the change of the oxygen content in the heat treatment furnace 1, so that the effects that the oxygen in the heat treatment furnace 1 is consumed by light and excessive hydrogen is not accumulated are realized; in order to control the hydrogen flow rate fluctuation, the opening degree of the electrical control valve 14 may be adjusted according to the flow rate change of the hydrogen gas in the hydrogen pipe 16; in order to prevent the explosion danger caused by the over-low pressure caused by the instant drop of the pressure in the heat treatment furnace 1, whether to switch the standby loop or not can be determined according to the change of the pressure in the heat treatment furnace 1, and the inert gas helium is introduced into the heat treatment furnace 1, thereby avoiding the possibility of explosion.

According to hardware conditions, instrument control can be upgraded to a computer direct control DDC system, namely the system is controlled by a computer, and advanced algorithms such as fuzzy control and neuron control can be adopted to replace a PID (proportion integration differentiation) method of instrument control.

A PID controller (proportional-integral-derivative controller) is a common feedback loop component in industrial control applications, consisting of a proportional unit P, an integral unit I and a derivative unit D.

The following examples employ the instrument controlled PID method:

the whole system is connected according to the figure 1, under the normal operation state, a large number of stainless steel pipes are subjected to heat treatment in the heat treatment furnace 1, the oxygen content in the heat treatment furnace 1 is monitored in real time through the oxygen measuring sensor 4, a measuring signal is converted into a standard signal through the oxygen measuring transmitter 5 and then transmitted to the flow controller 6 in real time, and the flow controller 6 controls the opening of the electric regulating valve 14, so that the hydrogen filled into the heat treatment furnace 1 can completely consume the oxygen in the furnace without excessive accumulation.

As shown in fig. 2, when the oxygen content in the heat treatment furnace 1 increases, the measured data transmitted by the oxygen measuring sensor 4 to the oxygen measuring transducer 5 is converted into a 4-20mA standard electric signal recognizable by the flow controller 6, and then the flow controller 6 compares the measured value with a set value, and the difference is called a deviation, which is used as an input of the flow controller 6, and since the oxygen content increases and the deviation is larger than the set value, the flow controller 6 increases the opening degree of the electric control valve 14 according to a proportional-integral control method, so that the flow rate of hydrogen input from the high-pressure hydrogen storage tank 2 into the furnace of the heat treatment furnace 1 increases enough to balance the increase of the oxygen content. In the process, the oxygen measuring sensor 4 continuously measures the oxygen content in the heat treatment furnace 1, and the flow controller 6 adjusts the opening of the electric regulating valve 14 according to the change value, so that a complete feedback closed-loop control system is formed. Vice versa, when the oxygen content in the heat treatment furnace 1 is decreased, the flow controller 6 decreases the amount of hydrogen gas to be fed into the heat treatment furnace 1 to prevent excessive accumulation of hydrogen gas.

As shown in fig. 3, the power source for hydrogen gas to be supplied from the hydrogen gas storage tank 2 to the heat treatment furnace 1 is a relatively high pressure in the hydrogen gas storage tank 2, and when the temperature changes or the storage amount in the storage tank changes, the power intensity changes, causing fluctuations in the hydrogen gas flow rate. When the internal pressure of the hydrogen storage tank 2 rises due to the rise of the temperature, firstly, the flow measurement sensor 8 measures the increase of the hydrogen flow in the hydrogen pipeline 16, the measured value is transmitted to the flow measurement transmitter 7, the flow measurement transmitter 7 converts the hydrogen flow into a 4-20mA standard electric signal and transmits the electric signal to the flow controller 6, and the flow controller 6 reduces the opening degree of the electric regulating valve 14 according to a proportional-integral control method so as to ensure the stability of the hydrogen transmission quantity. Vice versa, when the temperature is reduced, the same control principle is adopted, the opening degree of the electric control valve 14 is increased, and the stability of the hydrogen conveying quantity is ensured.

In fig. 3, the disturbance f is a fluctuation of the hydrogen flow rate in the pipeline, and there are two transfer channels between the disturbance and the hydrogen flow rate: one is to influence the hydrogen flow rate as the controlled variable from the disturbance channel Gf, and the other is to influence the hydrogen flow rate as the controlled variable from f via the compensation regulation effect produced by the measuring device and the electric regulating valve 14 via the control channel GP. The effects of the conditioning and disturbance effects on the hydrogen flow are reversed so that, under appropriate control parameters, the effect of the control channel can cancel the effect of f on the hydrogen flow, thus forming a feed forward control system.

As shown in fig. 4, after the system control by the feedback control system and the feedforward control system, the oxygen content and the hydrogen content in the heat treatment furnace 1 are in a relatively stable state, but when some special conditions, such as the combustion speed in the heat treatment furnace 1 is too fast at a moment, the pressure in the heat treatment furnace 1 is suddenly reduced, the external air is rapidly supplemented, that is, the oxygen content is suddenly increased, and the hydrogen content for balance is also suddenly increased, so that the explosion risk is very high, which is an abnormal condition of an abnormal condition. The pressure in the hearth of the heat treatment furnace 1 is continuously measured in real time by adopting the pressure measuring sensor 9, the measured value is transmitted to the pressure controller 11 through the pressure measuring transmitter 10, when the measured value is greater than the set value, the pressure controller 11 judges that no explosion hazard exists in the heat treatment furnace 1, so that the electric gate valve B15 is closed to cut off the helium from entering the passage of the heat treatment furnace 1, and the electric gate valve A13 is set to be in a full-open state, so that the smoothness of a hydrogen passage is ensured. Once the pressure measuring sensor 9 detects that the pressure in the hearth of the heat treatment furnace 1 is instantly reduced to be lower than a set value, the pressure controller 11 closes the electric gate valve a13 to prevent hydrogen from entering the heat treatment furnace 1, simultaneously switches the process loop to a standby safety loop, namely a helium loop, and fully opens the electric gate valve B15 to enable a large amount of helium to rapidly enter the hearth of the heat treatment furnace 1, so that the danger of explosion is eliminated, and the helium is used as protective gas to prevent a stainless steel pipe from being oxidized (namely, the helium has no reduction function, which is the reason that hydrogen is selected instead of helium as the reduction gas). When the pressure in the heat treatment furnace 1 is recovered to a normal state, the control loop is switched to a normal operation state again, the hydrogen loop is opened, and the helium loop is closed, so that a complete range control system is formed, abnormal working conditions which possibly cause explosion hazards are passed under the state that the heat treatment operation is not stopped, and the automatic switching of the process loop and the standby safety loop is realized.

In conclusion, the invention provides an oxidation-reduction protection device of a stainless steel tube heat treatment furnace, which mainly divides a gas pipeline into a hydrogen loop and a helium loop, wherein the control loop adopts a control system combining feed-forward, feedback and split, and the inhibition of the oxygen content in the furnace is realized by adjusting the amount of hydrogen input into the heat treatment furnace; the fluctuation of the hydrogen flow in the hydrogen pipeline is inhibited by adjusting the opening of the electric regulating valve, and the matching of the hydrogen input into the heat treatment furnace and the oxygen content in the furnace is ensured; the explosion danger caused by the over-low pressure in the heat treatment furnace is ensured through a split control loop; the stainless steel tube is not oxidized during heat treatment, the economy of using hydrogen according to the oxygen content in the furnace can be ensured, the hydrogen aggregation in the furnace is ensured, the possibility of hydrogen explosion is avoided, and the stainless steel tube can be widely applied to the technical field of gas protection of heat treatment furnace devices.