A method for controlling the flow of gas from a gas boiler to maintain the residual volume of a gas holder at a steel plant

Abstract

The application discloses a kind of gas boiler gas flow control methods for keeping steel plant gas holder residual capacity, including setting the residual volume range of each gas holder, determining the net increase flow of current gas holder capacity, retrieving the gas storage capacity of gas holder, calculating gas storage ratio;If the net increase flow of capacity is positive, then determine the lower limit y1 of flow increase and the upper limit y2 of flow increase of gas holder connected to gas boiler;Control each gas holder according to the input total amount calculated to execute the corresponding valve actuator for gas boiler input gas.The application introduces the relevant data of gas holder into the control system of gas boiler generator set through communication line, and after communication, it can automatically judge and reasonably distribute the net increase flow of three gas holders, and realize automatic combustion management.

Description

Technical Field

[0001] This invention relates to the field of gas usage management technology in steel plants, specifically to a method for controlling the flow of gas from a gas-fired boiler to maintain the reserve capacity of the gas holder in a steel plant. Background Technology

[0002] Currently, the gas sources for gas-fired boilers in steel enterprises are generally blast furnace gas, converter gas, and coke oven gas, all housed in gas holders. These gas holders have multiple users, meaning each holder is used by several devices within the enterprise. These users can be categorized into main process equipment and gas-fired boilers. Main process equipment refers to the essential equipment used in the steel enterprise's production process and constitutes the primary group of equipment utilizing gas. Gas-fired boilers are used in conjunction with gas-fired boiler generator sets to utilize excess gas.

[0003] Gas usage by users is highly unpredictable, and as end-users of gas, steel plant gas-fired boiler generator sets are often constrained by other users' gas consumption. Currently, many steel plant gas dispatch centers primarily notify generator set operators via telephone or group messages to maintain a fixed gas flow rate in the gas holders to ensure sufficient gas capacity for steel production processes. When the gas holder capacity exceeds the allowable range, if the dispatch center fails to notify in a timely manner or the generator set operators do not manually adjust the gas consumption promptly, the gas holder capacity will exceed the allowable range, impacting the main production processes.

[0004] Meanwhile, the automatic combustion system of a gas-fired boiler often needs to coordinate the usage of various gases to maintain the boiler load. When the flow of one or two gases is limited and cannot be actively adjusted, the automatic combustion system has poor adjustment performance and may not be able to be put into operation at low loads.

[0005] In summary, in existing technologies, to maintain gas supply for the main steel production processes, the gas holder's reserve capacity needs to be kept within a suitable range—neither too high nor too low. Furthermore, current technologies largely rely on manual adjustments to the gas consumption of gas-fired boilers, resulting in low automation and inconvenient communication. Therefore, to maintain gas supply for the main production processes and ensure the self-regulation of gas-fired boilers, the gas holder should be maintained within a good reserve capacity range as much as possible; when there is excess gas, it should be utilized by the gas-fired boiler, and when there is insufficient gas, the boiler's flow rate should be reduced.

[0006] Meanwhile, the remaining amount in the gas holder is constantly changing. As the amount of gas in the gas holder gradually increases, the remaining amount in each gas holder should be adjusted to keep the storage remaining amount in each gas holder as stable as possible. Summary of the Invention

[0007] The purpose of this invention is to provide a method for controlling the flow of gas from a gas-fired boiler while maintaining the reserve capacity of the gas holder in a steel plant.

[0008] The present invention aims to solve the following technical problems:

[0009] 1. Existing scheduling methods are inefficient, prone to errors when performed manually, and have poor automation.

[0010] 2. When there is an increase in gas consumption, it can coordinate the gas consumption of the three gas holders to keep the remaining amount in the gas holders stable.

[0011] To achieve the above objectives, one embodiment of the present invention provides a method for controlling the gas flow of a gas-fired boiler to maintain the reserve capacity of a gas holder in a steel plant. The gas holder includes three types of gas holders, which are respectively connected to a gas-fired boiler and main process equipment for gas supply. The three types of gas holders are a blast furnace gas holder, a converter gas holder, and a coke oven gas holder. The blast furnace gas holder is connected to the blast furnace gas pipeline network, the converter gas holder is connected to the converter gas pipeline network, and the coke oven gas holder is connected to the coke oven gas pipeline network.

[0012] The gas flow control methods for gas holders include:

[0013] (1) Set the capacity range for each gas holder and determine the upper limit Vmax and lower limit Vmin of gas storage capacity;

[0014] (2) Obtain the inflow and outflow data of the gas holder. The output flow of the gas holder includes the initial flow of the gas-fired boiler currently input. Determine the net increase in storage capacity of the current gas holder, Qin. The net increase in storage capacity, Qin, is the difference between the inflow and outflow data of the gas holder. Retrieve the gas storage capacity Vnow of the gas holder and calculate the gas storage ratio.

[0015] The gas storage ratio E is calculated as follows:

[0016]

[0017] (3) Determine whether the net increase in storage capacity, Qin, is positive;

[0018] If the net increase in storage capacity is positive, then the lower limit y1 and upper limit y2 of the increase in flow when the gas holder is connected to the gas boiler are determined by combining the gas storage ratio of the gas holder; the input increment Qn of the gas holder connected to the gas boiler is limited to the range of y1 to y2, and the total input of the gas holder to the gas boiler is the sum of the input increment and the initial flow of the boiler.

[0019] The lower limit for increasing current is:

[0020]

[0021] The maximum flow increase is:

[0022]

[0023] (4) Control each gas holder to control the corresponding valve actuator to input gas into the gas boiler according to the total input calculated by each gas holder.

[0024] Preferably, in this invention, the gas boiler is a supporting device for a generator set. The gas boiler generator set is equipped with a control system. The flow data and storage capacity data of the gas holder are connected to the control system through a communication line or a wireless communication module. The control system is used to control the valve actuators between the gas holder and the gas boiler.

[0025] Preferably, the remaining capacity range, upper limit Vmax and lower limit Vmin of each gas holder, the inflow and outflow data of the gas holder, the net increase in the gas holder's capacity Qin, and the input flow range of the gas holder connected to the gas boiler are all uploaded to the control system for collection, storage and calculation.

[0026] Preferably, step (3) of this invention further includes a process for determining the specific input increment for each gas holder, the specific method of which is as follows:

[0027] Determine the lower limit y1 and upper limit y2 of the gas holder's flow increase, determine the current gas storage ratio E of the gas holder, and calculate the input increment Qn from the gas holder to the gas-fired boiler according to the following formula;

[0028]

[0029] The input increments from the blast furnace gas holder, converter gas holder, and coke oven gas holder to the gas-fired boiler are obtained using the methods described above.

[0030] Preferably, the present invention sets a detection cycle, and the initial flow rate of the boiler is the total amount of gas from the gas holder to the gas boiler after the end of the previous detection cycle.

[0031] Preferably, if the net increase in storage capacity is negative, it is determined whether the current gas storage ratio is greater than a threshold. If it is greater than the threshold, the input from the gas holder to the gas boiler is kept constant. If the current gas storage ratio is less than the threshold, the input is reduced by the amount of the net increase in storage capacity.

[0032] In summary, the present invention has the following advantages:

[0033] 1. This invention introduces relevant data from the gas holders into the control system of the gas boiler generator set via a communication line. After communication is established, the system can automatically judge and rationally allocate the net increase in flow rate of the three gas holders, thereby achieving automated combustion management.

[0034] 2. When there is a net increase in storage capacity, the present invention can reasonably allocate the net increase in storage capacity according to the gas storage status and steady-state requirements of the gas holder, and balance the gas charging and discharging of the gas holder and the combustion of the gas boiler, so that the gas in the gas holder tends to be in the middle position during operation and maintains a good gas buffer margin. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the control method in one embodiment of the present invention;

[0036] Figure 2 This is a graph showing the relationship between the lower flow limit y1 and the upper flow increase limit y2 and the gas storage ratio in one embodiment of the present invention. Detailed Implementation

[0037] This invention provides a method for controlling the flow of gas from a gas-fired boiler to maintain the reserve capacity of a gas holder in a steel plant. The gas holder comprises three types: a blast furnace gas holder, a converter gas holder, and a coke oven gas holder. The blast furnace gas holder is connected to the blast furnace gas pipeline network, the converter gas holder is connected to the converter gas pipeline network, and the coke oven gas holder is connected to the coke oven gas pipeline network. During operation, gas is continuously injected into the gas holders from the gas pipeline network, and the gas in the gas holders is also continuously supplied to the combustion boiler and the main process equipment.

[0038] The gas flow control methods for gas holders include:

[0039] (1) Set the capacity range for each gas holder and determine the upper limit Vmax and lower limit Vmin of gas storage capacity.

[0040] The upper limit of the remaining capacity in this invention is not the maximum storage capacity of the gas holder, nor is the lower limit zero; it is generally set according to the equipment parameters of the gas holder and the requirements for production stability in the process. For example, the upper limit of the remaining capacity can be 80% of the maximum storage capacity of the gas holder, and the lower limit of the remaining capacity can be 20% of the maximum gas storage capacity. Other upper and lower limit values ​​can also be set according to the actual situation.

[0041] (2) Obtain the inflow and outflow data of the gas holder. The output flow of the gas holder includes the initial flow of the gas-fired boiler currently input. Determine the net increase in storage capacity of the gas holder, Qin. The net increase in storage capacity, Qin, is the difference between the inflow and outflow data of the gas holder. Retrieve the gas storage capacity Vnow of the gas holder and calculate the gas storage ratio.

[0042] The output of a gas holder can be divided into the main process equipment and the combustion boiler. The inflow rate to the gas holder is the flow rate of the pipeline network, and the outflow rate is the sum of the inflow rate to the main process equipment and the combustion boiler. The net increase in storage capacity, Qin, refers to the difference between the current inflow rate to the gas holder and the outflow rate, that is, the net increase in flow rate of the gas holder.

[0043] The gas storage ratio E is calculated as follows:

[0044]

[0045] (3) Determine whether the net increase in storage capacity, Qin, is positive;

[0046] If the net increase in gas storage capacity is positive, it indicates that the amount of gas in the gas holder is increasing. Based on the gas storage ratio of the gas holder, the lower limit y1 and upper limit y2 for the gas holder's connection to the gas-fired boiler are determined. The input increment Qn of the gas holder connecting to the gas-fired boiler is limited to the range of y1 to y2. The total input from the gas holder to the gas-fired boiler is the sum of the input increment and the initial flow rate of the boiler.

[0047] This invention first sets a lower limit and an upper limit for current increase, which are determined based on actual conditions or experience.

[0048] The lower limit for increasing current is:

[0049]

[0050] The maximum flow increase is:

[0051]

[0052] (4) Control each gas holder to control the corresponding valve actuator to input gas into the gas boiler according to the total input calculated by each gas holder.

[0053] Based on the lower and upper limits of the flow increase determined in step (3), since the input increment is limited to between the upper and lower limits, the total input can be calculated based on the detected initial flow of the boiler. Once the total input is determined, the control system can control the valve to operate.

[0054] In an optimized embodiment of the present invention, the gas boiler is a supporting device for the generator set. The gas boiler generator set is equipped with a control system. The flow data and storage capacity data of the gas holder are connected to the control system through a communication line or a wireless communication module. The control system is used to control the valve actuators between the gas holder and the gas boiler.

[0055] In the prior art, the control system of a gas-fired boiler generator set cannot directly communicate with the data source of the gas holder. Therefore, in order to enable the control system of the generator set to directly obtain the data of the gas holder, the present invention enables the two to transmit data directly through a line or wireless communication module.

[0056] In the optimized embodiment of the present invention, the capacity range, upper limit Vmax and lower limit Vmin of each gas holder; the inflow and outflow data of the gas holder; the net increase in capacity Qin of the gas holder; and the input flow range of the gas holder connected to the gas boiler are all uploaded to the control system for collection, storage and calculation.

[0057] In the optimized embodiment of the present invention, step (3) further includes the process of determining the specific input increment for each gas holder, the specific method being:

[0058] Determine the lower limit y1 and upper limit y2 of the gas holder's flow increase, determine the current gas storage ratio E of the gas holder, and calculate the input increment Qn from the gas holder to the gas-fired boiler according to the following formula;

[0059]

[0060] The lower limit for increasing current is:

[0061]

[0062] The maximum flow increase is:

[0063]

[0064] The input increments from the blast furnace gas holder, converter gas holder, and coke oven gas holder to the gas-fired boiler are obtained using the methods described above.

[0065] In step (3) of this invention, the upper and lower limits of the input increment are disclosed, but the specific parameters are not determined. Therefore, this embodiment will supplement them.

[0066] The relationship between the upper and lower limits and the gas storage ratio E Figure 2 As can be seen, when the gas storage ratio approaches 0, it indicates that the gas storage capacity in the gas holder is low. At this time, the gas holder tends to absorb gas, i.e., store more gas. If there is a net increase in storage capacity, more of this net increase should be used to store gas in the gas holder, causing the gas storage ratio to approach 50. Simultaneously, when the gas storage ratio approaches 100, it indicates that the gas storage capacity in the gas holder is close to its limit. At this time, the gas holder tends to release gas, i.e., release more gas through the gas boiler. The net increase in storage capacity obtained at this time will be completely output to the gas boiler, and the output value should tend to be greater than the net increase in storage capacity. This allows the total reserve capacity of the gas holder to tend to decrease, preventing the gas storage ratio from increasing. All three gas holders of this invention can use the above method to optimize the allocation of net increase in storage capacity.

[0067] For example, select Figure 2 With different E values, the values ​​of Qn when Qin is set to 1 are as follows:

[0068] Serial Number E y1 y2 Exponential coefficient 0.5(y2-y1) Qn 1 0 0.5 1 1.65 0.25 0.588 2 0.1 0.5 1.1 1.49 0.3 0.653 3 0.2 0.5 1.2 1.35 0.35 0.728 4 0.3 0.5 1.3 1.22 0.4 0.812 5 0.4 0.5 1.4 1.11 0.45 0.900 6 0.5 0.5 1.5 1.00 0.5 1.000 7 0.6 0.6 1.5 1.11 0.45 1.099 8 0.7 0.7 1.5 1.22 0.4 1.188 9 0.8 0.8 1.5 1.35 0.35 1.273 10 0.9 0.9 1.5 1.49 0.30 1.347 11 1.0 1.0 1.5 1.65 0.25 1.412

[0069] If Qin is any other value other than 1, then the value of Qn in the table above needs to be multiplied by the specific value of Qin to obtain the Qn calculated under the current Qin value.

[0070] During gas holder storage, to ensure good buffering capacity, the gas storage ratio E should ideally be around 50, as this median value better handles complex combustion processes. This invention first sets upper and lower limits, then calculates Qn based on the gas storage ratio E, and subsequently determines the specific parameters for the current input increment. As shown in the table above, the ratio of Qn to the net increase in storage capacity, Qin, ranges from 0.588 to 1.412; that is, when Qn is less than Qin, a portion of the gas from the net increase in storage capacity is used to add to the gas-fired boiler, and a portion is used to increase the gas holder's inventory. Furthermore, a larger gas storage ratio E indicates a larger amount of gas stored in the gas holder. In this case, more gas can be allocated to the gas-fired boiler, and the portion used to increase the gas holder's inventory can be relatively reduced. However, since it is actually less than Qin, the gas holder's storage capacity still increases. When Qn is greater than Qin, it means that the amount of gas input to the gas-fired boiler is greater than the net increase in storage capacity Qin. This indicates that the stored gas in the gas holder will be consumed during the input process to bring it as close to the median as possible. A larger gas-storage ratio E indicates a larger amount of gas stored, far exceeding the median of 50. In this case, more gas is input to the gas-fired boiler, and the stored gas in the gas holder decreases faster, allowing it to approach the median of 50 more quickly. Therefore, the method of this invention can control the amount of gas stored in the gas holder to gradually approach the median region of the gas-storage ratio, achieving the optimal buffer zone. This is one of the technical problems solved and beneficial effects of this invention.

[0071] In an optimized embodiment of the present invention, a detection cycle is set, and the initial flow rate of the boiler is the total amount of gas from the gas holder to the gas-fired boiler after the end of the previous detection cycle.

[0072] In an optimized embodiment of the present invention, if the net increase in storage capacity is negative, it is determined whether the current gas storage ratio is greater than a threshold. If it is greater than the threshold, the input from the gas holder to the gas boiler is kept constant. If the current gas storage ratio is less than the threshold, the input is reduced by the value of the net increase in storage capacity.

[0073] Although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A method for controlling the flow rate of gas from a gas-fired boiler while maintaining the reserve capacity of a gas holder in a steel plant, characterized in that: The gas holders include three types of gas holders, which are respectively connected to the gas boiler and the main process equipment for gas supply. The three types of gas holders are blast furnace gas holder, converter gas holder and coke oven gas holder. The blast furnace gas holder is connected to the blast furnace gas pipeline network, the converter gas holder is connected to the converter gas pipeline network, and the coke oven gas holder is connected to the coke oven gas pipeline network. The gas flow control method for the gas holder includes the following steps: (1) Set the capacity range for each gas holder and determine the upper limit Vmax and lower limit Vmin of gas storage capacity; (2) Obtain the inflow and outflow data of the gas holder. The output flow of the gas holder includes the initial flow of the gas-fired boiler currently input. Determine the net increase in storage capacity of the current gas holder, Qin. The net increase in storage capacity, Qin, is the difference between the inflow and outflow data of the gas holder. Retrieve the gas storage capacity Vnow of the gas holder and calculate the gas storage ratio. The gas storage ratio E is calculated as follows: (3) Determine whether the net increase in storage capacity, Qin, is positive; If the net increase in storage capacity is positive, then the lower limit y1 and upper limit y2 of the increase in flow when the gas holder is connected to the gas boiler are determined by combining the gas storage ratio of the gas holder; the input increment Qn of the gas holder connected to the gas boiler is limited to the range of y1 to y2, and the total input of the gas holder to the gas boiler is the sum of the input increment and the initial flow of the boiler. The lower limit for increasing current is: The upper limit for the flow increase is: (4) Control each gas holder to control the corresponding valve actuator to input gas into the gas boiler according to the total input calculated by itself; Step (3) also includes the process of determining the specific input increment for each gas holder, the specific method of which is as follows: Determine the lower limit y1 and upper limit y2 of the gas holder's flow increase, determine the current gas storage ratio E of the gas holder, and calculate the input increment Qn from the gas holder to the gas-fired boiler according to the following formula; The input increments from the blast furnace gas holder, converter gas holder, and coke oven gas holder to the gas-fired boiler are obtained using the methods described above.

2. The method for controlling the flow rate of gas-fired boilers to maintain the residual capacity of the gas holder in a steel plant as described in claim 1, characterized in that: The gas boiler is a supporting device for the generator set. The gas boiler generator set is equipped with a control system. The flow data and storage capacity data of the gas holder are connected to the control system through communication lines or wireless communication modules. The control system is used to control the valve actuators between the gas holder and the gas boiler.

3. The method for controlling the flow rate of gas-fired boilers to maintain the residual capacity of the gas holder in a steel plant as described in claim 1, characterized in that: The capacity range, upper limit Vmax and lower limit Vmin of each gas holder; the inflow and outflow data of the gas holder; the net increase in the gas holder's capacity Qin; and the input flow range of the gas holder connected to the gas boiler are all uploaded to the control system for collection, storage and calculation.

4. The method for controlling the flow rate of gas-fired boilers to maintain the residual capacity of the gas holder in a steel plant as described in claim 1, characterized in that: Set the detection cycle, and the initial boiler flow rate is the total amount of gas that was input into the gas boiler from the gas holder after the end of the previous detection cycle.

5. The method for controlling the flow rate of gas-fired boilers to maintain the residual capacity of the gas holder in a steel plant as described in claim 1, characterized in that: If the net increase in storage capacity is negative, it is determined whether the current gas storage ratio is greater than the threshold. If it is greater than the threshold, the input from the gas holder to the gas boiler is kept constant. If the current gas storage ratio is less than the threshold, the input is reduced by the amount of net increase in storage capacity.

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