Heating furnace fuel gas supply system and method

Abstract

The invention relates to a heating furnace gas supply system and method, and belongs to the technical field of metallurgical non-blast furnace ironmaking equipment and methods. According to the technical scheme, an outer net gas pipeline is connected with the input end of a mixed dehydration tank through an outer net gas pressure regulating valve, and an inner net tail gas pipeline is connected with the input end of the mixed dehydration tank through an inner net tail gas stop valve; the output end of the mixing dehydration tank is connected with a main gas pipeline through a main gas flow adjusting valve, and a main gas pressure adjusting valve is arranged on the upstream of the main gas pipeline and connected with the main gas flow adjusting valve in parallel. The device has the beneficial effects that mixing and deep dehydration of two kinds of fuel gas are achieved, and the cleanliness of the fuel gas going to the heating furnace burner is guaranteed; the intensity of the burning furnace is regulated and controlled through one valve, the delay problem of regulating and controlling the inner net tail gas and the outer net gas is eliminated, the inner net tail gas of the direct reduction system is used and extracted to the maximum degree in the normal production state, diffusion waste is avoided, and the operation cost of a direct reduction plant is reduced.

Description

Technical Field

[0001] The invention relates to a heating furnace gas supply system and method, belonging to the technical field of metallurgical non-blast furnace ironmaking equipment and methods. Background Art

[0003] The heating furnace is one of the core equipment that must be configured in a gas-based direct reduction plant. Its function is to provide the process circulating gas with the heat energy required for the reduction process. At present, all gas-based direct reduction plants in the world use the "external network supply + internal network extraction" mode for the gas supply of the heating furnace. This is because in the early stage of the factory's production, only the gas supplied by the "external network" can be used, and in the normal production mode, part of the process circulating gas (i.e., "internal network tail gas") from the "internal network" needs to be extracted to achieve the purpose of regulating the system pressure. For the simultaneous use of "internal network" and "external network" gas to burn the furnace, the existing solution is: set flow control valves on the two gas pipelines respectively, according to the furnace burning demand of the heating furnace and the available amount of "internal network tail gas", the appropriate amount of the two gas is calculated through the automatic program, and then the gas supply is regulated through the flow control valve. This solution requires real-time detection of the components of the "external network gas" and "internal network tail gas" respectively to provide the basis for the calculation of the automatic program. In the production process, when the available amount of "inner network tail gas" is relatively stable and the fluctuation range is small, the existing solution can meet the production demand; however, when the available amount of "inner network tail gas" fluctuates greatly, the existing solution relies on the automation program to calculate and adjust the flow of the two types of gas separately, and there is a certain "hysteresis" (the specific lag depends on the accuracy of the instrument feedback, the speed of the control valve and the matching degree of the automation control program, etc.). This "hysteresis" is likely to bring the following disadvantages: when the available tail gas volume increases significantly in a short period of time, it is impossible to quickly implement the operation of "reducing external network gas and increasing internal network tail gas", which may lead to the inability to absorb excessive tail gas and forced flare discharge, resulting in waste; when the available tail gas volume decreases significantly in a short period of time, it is impossible to quickly implement the operation of "increasing external network gas and reducing internal network tail gas", which may lead to the heating furnace being short of gas and the heating end temperature being reduced in a short period of time, causing process fluctuations in the direct reduction system. Summary of the invention

[0004] The object of the present invention is to provide a heating furnace gas supply system and method. Through the design of a double dehydration tank of an internal network tail gas dehydration tank and a mixed dehydration tank, the mixing and deep dehydration of the two gases are realized, thereby ensuring the cleanliness of the gas going to the burner of the heating furnace; parallel pressure and flow control valves are set on the main gas pipeline to achieve one valve to control the furnace burning intensity, thereby eliminating the hysteresis problem of separately controlling the internal network tail gas and the external network gas, and at the same time can effectively cope with different furnace burning conditions; the external network gas pipeline is provided with a pressure regulating valve, while the internal network tail gas pipeline is only provided with a stop valve, which can maximize the use of the internal network tail gas extracted from the direct reduction system under normal production conditions, avoid causing waste of dispersion, and is beneficial to reducing the operating cost of the direct reduction plant, effectively solving the above-mentioned problems existing in the background technology.

[0005] The technical solution of the present invention is: a heating furnace gas supply system, comprising a gas-based direct reduction vertical furnace top pressure regulating valve, an internal network tail gas stop valve, an external network gas pressure regulating valve, a main gas flow regulating valve, a main gas pressure regulating valve, an internal network tail gas dehydration tank and a mixed dehydration tank, wherein the external network gas pipeline is connected to the input end of the mixed dehydration tank through the external network gas pressure regulating valve, and the internal network tail gas pipeline is connected to the input end of the mixed dehydration tank through the internal network tail gas dehydration tank, the gas-based direct reduction vertical furnace top pressure regulating valve and the internal network tail gas stop valve in sequence; the output end of the mixed dehydration tank is connected to the main gas pipeline through the main gas flow regulating valve, the main gas pressure regulating valve is arranged upstream of the main gas pipeline, and is connected in parallel with the main gas flow regulating valve, and the main gas pipeline leads to the heating furnace for burning.

[0006] The mixing and dehydration tank is provided with a baffle, and the output end of the baffle is connected to the water treatment plant through a pipeline.

[0007] It also includes a bypass pipeline, which is arranged at the bypass of the internal network tail gas pipeline at the output end of the internal network tail gas dehydration tank. The bypass pipeline is provided with an internal network tail gas release valve, and the bypass pipeline is connected to the flare through the internal network tail gas release valve.

[0008] The bottom of the internal network tail gas dehydration tank is connected to a water treatment plant through a pipeline.

[0009] A method for supplying gas to a heating furnace comprises the following steps: (1) A main gas flow regulating valve is installed on the main gas pipeline leading to the heating furnace, and the gas flow control method during the heating furnace burning process is changed from simultaneously adjusting the flow regulating valves of the two gas pipelines to adjusting the main gas flow regulating valve; (2) A main gas pressure regulating valve connected in parallel with the main gas flow regulating valve is installed upstream of the main gas pipeline leading to the heating furnace for burning. This valve is used to control the gas volume during the start-up and shutdown stages of the heating furnace to ensure stable burning during the start-up and shutdown stages. (3) No flow regulating valve is installed on the external network gas pipeline, but an external network gas pressure regulating valve is installed, and its opening adjustment matches the stability of the main gas pipeline pressure; (4) No flow regulating valve is set on the internal network exhaust gas pipeline, only an internal network exhaust gas stop valve is set. When the internal network exhaust gas is available, the operator opens the internal network exhaust gas stop valve to introduce the internal network exhaust gas into the main gas pipeline. The pressure of the main gas pipeline rises, and the external network gas pressure regulating valve is automatically closed step by step under the PID control logic, reducing the external network gas supply and realizing automatic switching; (5) A bypass pipeline connected to the flare is set on the internal network tail gas pipeline, and an internal network tail gas release valve is set on the bypass pipeline to achieve automatic release when the tail gas volume exceeds the gas volume required for heating furnace burning, and directly restore the process gas replacement function during the factory startup stage; (6) A mixing and dehydration tank is installed at the intersection of the internal network exhaust gas and the external network gas to promote the mixing of the two gas streams.

[0010] In the step (1), the heating furnace can be burned automatically or manually; a chemical composition detection sampling point of the mixed gas is added upstream of the main gas pipeline flow control valve of the main gas pipeline, and the mixed gas composition feedback is used as the basis for the air-fuel ratio control of the furnace.

[0011] In the step (6), a baffle is provided in the mixing and dehydration tank to further remove condensed water droplets carried in the fuel gas and promote mixing of the two fuel gases.

[0012] In the step (4), an internal network tail gas pipeline is provided with an internal network tail gas dehydration tank, and the internal network tail gas pipeline is connected to the input end of the mixed dehydration tank through the internal network tail gas dehydration tank, the gas-based direct reduction vertical furnace top pressure regulating valve and the internal network tail gas stop valve in sequence, and the bottom of the internal network tail gas dehydration tank is connected to the water treatment plant through a pipeline.

[0013] The beneficial effects of the present invention are as follows: through the design of the double dehydration tank of the internal network tail gas dehydration tank and the mixed dehydration tank, the mixing and deep dehydration of the two kinds of fuel gas are achieved, thereby ensuring the cleanliness of the fuel gas going to the burner of the heating furnace; parallel pressure and flow control valves are set on the main gas pipeline to achieve one valve to control the furnace burning intensity, thereby eliminating the hysteresis problem of separately controlling the internal network tail gas and the external network gas, and at the same time can effectively cope with different furnace burning conditions; the external network gas pipeline is provided with a pressure regulating valve, while the internal network tail gas pipeline is only provided with a stop valve, which can maximize the use of the internal network tail gas extracted from the direct reduction system under normal production conditions, avoid waste of emission, and help reduce the operating cost of the direct reduction plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of the present invention; In the figure: gas-based direct reduction vertical furnace top pressure regulating valve V1, internal network tail gas release valve V2, internal network tail gas stop valve V3, external network fuel gas pressure regulating valve V4, main fuel gas flow regulating valve V5, main fuel gas pressure regulating valve V6, internal network tail gas dehydration tank A, mixed dehydration tank B. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the invention implementation cases clearer, the technical solutions in the implementation cases of the present invention will be clearly and completely described below in conjunction with the drawings in the implementation cases. Obviously, the implementation cases described are only a small part of the implementation cases of the present invention, rather than all the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] A heating furnace gas supply system comprises a gas-based direct reduction vertical furnace top pressure regulating valve V1, an internal network tail gas stop valve V3, an external network gas pressure regulating valve V4, a main gas flow regulating valve V5, a main gas pressure regulating valve V6, an internal network tail gas dehydration tank A and a mixed dehydration tank B, wherein the external network gas pipeline is connected to the input end of the mixed dehydration tank B through the external network gas pressure regulating valve V4, and the internal network tail gas pipeline is connected to the input end of the mixed dehydration tank B through the internal network tail gas dehydration tank A, the gas-based direct reduction vertical furnace top pressure regulating valve V1 and the internal network tail gas stop valve V3 in sequence; the output end of the mixed dehydration tank B is connected to the main gas pipeline through the main gas flow regulating valve V5, the main gas pressure regulating valve V6 is arranged upstream of the main gas pipeline and is connected in parallel with the main gas flow regulating valve V5, and the main gas pipeline leads to the heating furnace for burning.

[0017] The mixing and dehydration tank B is provided with a baffle, and the output end of the baffle is connected to the water treatment plant through a pipeline.

[0018] It also includes a bypass pipeline, which is arranged at the bypass of the internal network tail gas pipeline at the output end of the internal network tail gas dehydration tank A. The bypass pipeline is provided with an internal network tail gas release valve V2, and the bypass pipeline is connected to the flare through the internal network tail gas release valve V2.

[0019] The bottom of the internal network tail gas dehydration tank A is connected to the water treatment plant through a pipeline.

[0020] A method for supplying gas to a heating furnace comprises the following steps: (1) A main gas flow regulating valve is installed on the main gas pipeline leading to the heating furnace, and the gas flow control method during the heating furnace burning process is changed from simultaneously adjusting the flow regulating valves of the two gas pipelines to adjusting the main gas flow regulating valve; (2) A main gas pressure regulating valve connected in parallel with the main gas flow regulating valve is installed upstream of the main gas pipeline leading to the heating furnace for burning. This valve is used to control the gas volume during the start-up and shutdown stages of the heating furnace to ensure stable burning during the start-up and shutdown stages. (3) No flow regulating valve is installed on the external network gas pipeline, but an external network gas pressure regulating valve is installed, and its opening adjustment matches the stability of the main gas pipeline pressure; (4) No flow regulating valve is set on the internal network exhaust gas pipeline, only an internal network exhaust gas stop valve is set. When the internal network exhaust gas is available, the operator opens the internal network exhaust gas stop valve to introduce the internal network exhaust gas into the main gas pipeline. The pressure of the main gas pipeline rises, and the external network gas pressure regulating valve is automatically closed step by step under the PID control logic, reducing the external network gas supply and realizing automatic switching; (5) A bypass pipeline connected to the flare is set on the internal network tail gas pipeline, and an internal network tail gas release valve is set on the bypass pipeline to achieve automatic release when the tail gas volume exceeds the gas volume required for heating furnace burning, and directly restore the process gas replacement function during the factory startup stage; (6) A mixing and dehydration tank is installed at the intersection of the internal network exhaust gas and the external network gas to promote the mixing of the two gas streams.

[0021] In the step (1), the heating furnace can be burned automatically or manually; a chemical composition detection sampling point of the mixed gas is added upstream of the main gas pipeline flow control valve of the main gas pipeline, and the mixed gas composition feedback is used as the basis for the air-fuel ratio control of the furnace.

[0022] In the step (6), a baffle is provided in the mixing and dehydration tank to further remove condensed water droplets carried in the fuel gas and promote mixing of the two fuel gases.

[0023] In the step (4), an internal network tail gas pipeline is provided with an internal network tail gas dehydration tank, and the internal network tail gas pipeline is connected to the input end of the mixed dehydration tank through the internal network tail gas dehydration tank, the gas-based direct reduction vertical furnace top pressure regulating valve and the internal network tail gas stop valve in sequence, and the bottom of the internal network tail gas dehydration tank is connected to the water treatment plant through a pipeline.

[0024] The present invention sets a mixing dehydration tank at the intersection of the internal network tail gas and the external network gas supply line to achieve mixing and deep dehydration of the two gases; sets a gas analysis sampling on the mixed gas pipeline for reference of air-fuel ratio control of furnace burning; sets a parallel pressure / flow control valve on the main gas pipeline to achieve the function of regulating the intensity of furnace burning, instead of the traditional scheme of setting regulating valves on the two gas pipelines of the internal network and the external network respectively, to solve the problem of regulation hysteresis; sets a pressure regulating valve on the external network gas pipeline, and only sets a stop valve on the internal network tail gas pipeline, so as to maximize the use of the internal network tail gas extracted from the direct reduction system under normal production conditions, avoid waste of emission, and help reduce the operating cost of the direct reduction plant. Specific implementation methods

[0025] During the startup phase of the direct reduction plant, there is no internal network exhaust gas available, and only external network gas can be used. The working mode of the gas supply system is as follows: (1) The external network gas from the boundary area passes through the external network gas pipeline to the external network gas pressure regulating valve V4. The external network gas pressure regulating valve V4 adjusts the opening based on the pressure feedback on the main gas pipeline. Under the control logic of the stable pressure of the main gas pipeline, the required external network gas is supplemented to the pipeline between the external network gas pressure regulating valve and the mixed dehydration tank; (2) The external network gas enters the mixed dehydration tank B to remove the condensed water it carries. When the condensed water accumulates to a certain level, the condensed water is discharged into the pipeline through the regulating valve and then enters the water treatment plant for recycling; (3) External network gas enters the main gas pipeline. Since the gas demand is small at the initial startup, the main gas flow regulating valve V5 is used. The operator sets the pressure of the downstream main gas pipeline. The main gas pressure regulating valve V4 adjusts the opening based on the pressure feedback on the main gas pipeline to the burner of the heating furnace of the gas-based direct reduction plant, and delivers the required external network gas to this section of the main gas pipeline. (4) The external network gas enters the main gas pipeline to the burner of the heating furnace of the gas-based direct reduction plant, directly passes through the burner, and an automatic or manual shut-off valve is set near the burner. When the corresponding burner needs to be ignited, it can be opened to ignite the burner; (5) On the main fuel gas pipeline to the burner of the heating furnace in the gas-based direct reduction plant, the sample analysis gas is sent to the online gas analyzer, and the analysis data is used as the basis for adjusting the air-fuel ratio.

[0026] When the direct reduction process loop is injected with make-up gas, and the gas replacement is completed, and the tail gas is available, it will switch to the working mode of two gas streams burning the furnace together. At this time, the working mode of the gas supply system is: (1) The internal network tail gas from the gas-based direct reduction process loop enters the internal network tail gas dehydration tank A, removes the carried droplets, and then enters the tail gas pipeline; (2) The internal network tail gas from the tail gas pipeline reaches the top pressure regulating valve V1 of the gas-based direct reduction vertical furnace. The top pressure regulating valve V1 of the gas-based direct reduction vertical furnace adjusts the opening in time according to the set top pressure, and releases part of the internal network tail gas to maintain a stable top pressure of the vertical furnace; (3) After the internal network exhaust gas is activated, the internal network exhaust gas cut-off valve V3 is fully opened; (4) The internal network tail gas passes through the internal network tail gas stop valve V3 and enters the mixing and dehydration tank B, where it is mixed with the external network gas, and then leaves the mixing and dehydration tank B and enters the main gas pipeline 9; (5) The direct reduction plant is in normal production, so the gas demand is large. At this time, the main gas pressure regulating valve V6 will be in a closed state, and the main gas flow regulating valve V5 will be in an open working state, so the mixed gas reaches the main gas flow regulating valve V5; (6) The main gas flow regulating valve V5 adjusts the opening according to the gas volume required for burning the furnace, and releases the main gas into the downstream main gas pipeline at the required flow rate, and finally reaches the burner for combustion; (7) Due to the introduction of internal network tail gas, the pressure of the main gas pipeline will inevitably increase. This is because the pressure of the direct reduction system (upstream of the gas-based direct reduction vertical furnace top pressure regulating valve V1) is much higher than the pressure of the main gas pipeline. At this time, under the fixed pressure operation mode, the external network gas pressure regulating valve V4 will automatically and gradually reduce the opening according to the feedback of the main gas pressure instrument, adjust the flow rate of the external network gas, maintain the stability of the main gas pressure, and realize the smooth switching between the external network gas and the internal network tail gas; (8) When the external network gas pressure regulating valve V4 is completely closed, the pressure of the main gas pipeline still exceeds the set value, indicating that the internal network exhaust gas is used entirely to burn the furnace, and the internal network exhaust gas is still in excess. The pressure of the internal network exhaust gas pipeline before the internal network exhaust gas stop valve will also rise accordingly. When the rise exceeds the warning set value, the internal network exhaust gas release valve V2 on the bypass pipeline will automatically open, appropriately release part of the internal network exhaust gas, and finally go to the torch for combustion, so as to achieve safety protection of the pipeline and equipment.

[0027] In summary, the gas supply system for a heating furnace in a gas-based direct reduction plant provided by the embodiment of the present invention has the following technical effects: (1) The design of double dehydration tank can fully and effectively remove the water droplets carried by the internal network exhaust gas, ensuring the cleanliness of the gas going to the burner of the heating furnace; (2) The idea of ​​setting a pressure / flow regulating valve on the main gas pipeline after gas mixing to control the combustion intensity can achieve one-valve control, thereby eliminating the hysteresis problem of separately controlling the internal network exhaust gas and the external network gas, and can effectively cope with different furnace burning conditions; (3) The external network gas pipeline is equipped with a pressure regulating valve, which can timely and effectively realize the automatic gas compensation under the condition that the internal network tail gas participates in the furnace burning, and effectively deal with the fluctuation of the available amount of internal network tail gas in the actual production process; (4) When the direct reduction plant is in production, as long as the flow rate of the process circulating gas is reasonably controlled, this heating furnace gas supply system can 100% ensure that the exhaust gas in the internal network will not be released, which can effectively avoid waste and minimize the energy consumption cost of the plant.

Claims

1. A heating furnace gas supply system, characterized in that: The invention comprises a gas-based direct reduction vertical furnace top pressure regulating valve (V1), an internal network tail gas stop valve (V3), an external network gas pressure regulating valve (V4), a main gas flow regulating valve (V5), a main gas pressure regulating valve (V6), an internal network tail gas dehydration tank (A) and a mixed dehydration tank (B), wherein the external network gas pipeline is connected to the input end of the mixed dehydration tank (B) through the external network gas pressure regulating valve (V4), and the internal network tail gas pipeline is connected to the input end of the mixed dehydration tank (B) through the internal network tail gas dehydration tank (A), the gas-based direct reduction vertical furnace top pressure regulating valve (V1) and the internal network tail gas stop valve (V3) in sequence; the output end of the mixed dehydration tank (B) is connected to the main gas pipeline through the main gas flow regulating valve (V5), the main gas pressure regulating valve (V6) is arranged upstream of the main gas pipeline and is connected in parallel with the main gas flow regulating valve (V5), and the main gas pipeline leads to the heating furnace for burning.

2. A heating furnace gas supply system according to claim 1, characterized in that: The mixing and dehydration tank (B) is provided with a baffle, and the output end of the baffle is connected to the water treatment plant through a pipeline.

3. A heating furnace gas supply system according to claim 1, characterized in that: It also includes a bypass pipeline, which is arranged at the output end of the internal network tail gas dehydration tank (A) to bypass the internal network tail gas pipeline. The bypass pipeline is provided with an internal network tail gas release valve (V2), and the bypass pipeline is connected to the flare through the internal network tail gas release valve (V2).

4. A heating furnace gas supply system according to claim 1, characterized in that: The bottom of the internal network tail gas dehydration tank (A) is connected to the water treatment plant through a pipeline.

5. A method for supplying gas to a heating furnace, characterized in that The following steps are involved: (1) A main gas flow regulating valve is installed on the main gas pipeline leading to the heating furnace, and the gas flow control method during the heating furnace burning process is changed from simultaneously adjusting the flow regulating valves of the two gas pipelines to adjusting the main gas flow regulating valve; (2) A main gas pressure regulating valve connected in parallel with the main gas flow regulating valve is installed upstream of the main gas pipeline leading to the heating furnace for burning. This valve is used to control the gas volume during the start-up and shutdown stages of the heating furnace to ensure stable burning during the start-up and shutdown stages. (3) No flow regulating valve is installed on the external network gas pipeline, but an external network gas pressure regulating valve is installed, and its opening adjustment matches the stability of the main gas pipeline pressure; (4) No flow regulating valve is set on the internal network exhaust gas pipeline, only an internal network exhaust gas stop valve is set. When the internal network exhaust gas is available, the operator opens the internal network exhaust gas stop valve to introduce the internal network exhaust gas into the main gas pipeline. The pressure of the main gas pipeline rises, and the external network gas pressure regulating valve is automatically closed step by step under the PID control logic, reducing the external network gas supply and realizing automatic switching; (5) A bypass pipeline connected to the flare is set on the internal network tail gas pipeline, and an internal network tail gas release valve is set on the bypass pipeline to achieve automatic release when the tail gas volume exceeds the gas volume required for heating furnace burning, and directly restore the process gas replacement function during the factory startup stage; (6) A mixing and dehydration tank is installed at the intersection of the internal network exhaust gas and the external network gas to promote the mixing of the two gas streams.

6. A heating furnace gas supply method according to claim 5, characterized in that: In the step (1), the heating furnace can be burned automatically or manually; a chemical composition detection sampling point of the mixed gas is added upstream of the main gas pipeline flow control valve of the main gas pipeline, and the mixed gas composition feedback is used as the basis for the air-fuel ratio control of the furnace.

7. A heating furnace gas supply method according to claim 5, characterized in that: In the step (6), a baffle is provided in the mixing and dehydration tank to further remove condensed water droplets carried in the fuel gas and promote mixing of the two fuel gases.

8. A heating furnace gas supply method according to claim 5, characterized in that: In the step (4), an internal network tail gas pipeline is provided with an internal network tail gas dehydration tank, and the internal network tail gas pipeline is connected to the input end of the mixed dehydration tank through the internal network tail gas dehydration tank, the gas-based direct reduction vertical furnace top pressure regulating valve and the internal network tail gas stop valve in sequence, and the bottom of the internal network tail gas dehydration tank is connected to the water treatment plant through a pipeline.

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