Working gas pressure control method and device for uranium concentration production line

Abstract

The invention relates to the field of uranium concentration, in particular to a uranium concentration production line working gas pressure control method and device. The control method comprises the following steps: mounting a regulating valve on a heavy fraction pipeline of N separation stages, mounting a first absolute pressure transmitter required by control on the heavy fraction pipeline in front of the regulating valve, and mounting a second absolute pressure transmitter on a feeding pipeline; monitoring the deviation between a control process measurement value Pv and a PID adjustment set value Sv, if the deviation is greater than a deviation alarm set value, controlling a manual and automatic selection switch of a PID module to be in a manual control mode by a DS function block according to a deviation alarm instruction, so that an output value of the PID module can only be manually adjusted on a control panel of the PID module; if the deviation is smaller than the deviation alarm set value, the DS function block controls a manual and automatic selection switch of the PID module to be in an automatic control mode, and PID automatic control over the pipeline gas pressure is implemented. According to the invention, efficient, safe, continuous and stable operation of the cascade production line is ensured.

Description

Technical Field

[0001] The present invention relates to the field of uranium enrichment, and in particular to a method and device for controlling the working gas pressure of a uranium enrichment production line. Background Art

[0002] Natural uranium elements mainly include 238 U. 235 U. 234 U has three isotopes, 235 The abundance of U is only 0.711% ( 235 The abundance of U refers to the amount of natural uranium 235 U accounts for 3.3% of the total), and the rest are mainly 238 U, 238 The abundance of U is 99.28%. 235 U is the only naturally occurring stable fissile nuclide, and is usually required for reactor nuclear fuel. 235 The abundance of U is between 3% and 5%. Therefore, uranium enrichment plants use UF6 with a mass concentration of more than 99.5% as the working gas to enrich UF6 through the mass effect of the substance. 235 U and 238 U were enriched and obtained 235 Light fractions with higher U abundance and 238 U is a heavy fraction material with higher abundance.

[0003] The structure of a uranium enrichment production line consists of racks, units, and sections. A section is composed of a certain number of mainframes connected in parallel. The flow rate of a section is proportional to the number of mainframes connected in parallel; the more mainframes connected in parallel, the greater the flow rate. A unit is composed of several sections connected in parallel or in series. A separation stage is a general term for mainframes that can complete a separation and have equal enrichment across all mainframes in the stage. A unit can be a single separation stage; when connected in series, it can be divided into two or more separation stages. A rack is the general term for the number of mainframes connected in series by several separation stages. A cascade can consist of a single rack or multiple racks connected in a complex combination of series and parallel connections.

[0004] Currently, most uranium enrichment production lines are cascaded, consisting of multiple layers. The pressure of the heavy fraction pipeline at each separation stage is a key parameter that requires control throughout the entire cascade. Therefore, adjusting and maintaining the heavy fraction pressure at each separation stage is a crucial control method for the entire cascade process.

[0005] Currently, cascade production lines mostly use electric regulators to control the heavy fraction pipeline gas pressure. However, electric regulators are complex and difficult to maintain. Furthermore, this control method creates significant fluctuations in pipeline gas pressure. Furthermore, electric regulators are unable to respond to false signals from faulty absolute pressure transmitters, often leading to cascade shutdowns due to these transmitter failures. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and device for controlling the working gas pressure of a uranium enrichment production line, which combines a PID control algorithm with a regulating valve to avoid large pressure fluctuations caused by cascade failures such as power disconnection and output jump of an absolute pressure transmitter, thereby ensuring the efficient, safe, continuous and stable operation of the cascade production line.

[0007] The present invention provides a working gas pressure control device for a uranium enrichment production line, comprising: A regulating valve is installed on the heavy fraction pipeline of the N separation stage, a first absolute pressure transmitter required for control is installed on the heavy fraction pipeline before the regulating valve, and a second absolute pressure transmitter is installed on the feed pipeline; DCS system, including PID module and DS function block, The DS function block is used to perform deviation limit control logic operations and control the PID module to enter manual control mode or automatic control mode; The PID module is used to control the output pipeline gas pressure control signal, and control and monitor the opening of the regulating valve.

[0008] In a specific embodiment of the present invention, in the PID module, the PID algorithm only uses the proportional term and the integral term.

[0009] The present invention provides a method for controlling the working gas pressure of a uranium enrichment production line using the working gas pressure control device of the uranium enrichment production line described in the above technical solution, comprising the following steps: Step 1: Install a regulating valve on the heavy fraction pipeline of the N separation stage, install the first absolute pressure transmitter required for control on the heavy fraction pipeline before the regulating valve, and install the second absolute pressure transmitter on the feed pipeline; Step 2: Monitor the deviation between the control process measurement value Pv and the PID adjustment set value Sv. If the deviation is greater than the deviation alarm set value, the DS function block controls the manual and automatic selection switch of the PID module to the manual control mode according to the deviation alarm indication, so that the output value of the PID module can only be manually adjusted on the PID module control panel; If the deviation is less than the deviation alarm setting value, the DS function block controls the manual and automatic selection switch of the PID module to be in the automatic control mode, and implements the PID automatic control of the pipeline gas pressure; The PID module controls and monitors the opening of the regulating valve.

[0010] In a specific embodiment of the present invention, the deviation includes positive deviation and negative deviation. The positive deviation is the value of the control process measurement value Pv minus the PID adjustment setting value Sv, and the negative deviation is the value of the PID adjustment setting value Sv minus the control process measurement value Pv.

[0011] In a specific embodiment of the present invention, the DS function block controls the manual and automatic selection switches of the PID module to be in manual control mode according to the deviation alarm indication, specifically: Receive deviation alarm indication, The selection switch of the DS function block is turned on and the second input mode is selected. At this time, the input value is a constant, and this constant is used as the output value. The manual and automatic selection switch of the PID module is in manual control mode.

[0012] In a specific embodiment of the present invention, the DS function block controls the manual-automatic selection switch of the PID module to be in the automatic control mode specifically as follows: When there is no deviation alarm indication, the selection switch of the DS function block is closed, the first input mode is selected, and the manual and automatic selection switch of the control PID module is in automatic control mode.

[0013] In a specific embodiment of the present invention, after the manual and automatic selection switches of the PID modules are controlled by the DS function block to be in the automatic control mode, The DCS system calculates the feedback value output and feedback status output, and sends the results to the PID module to determine whether the feedback value output is equal to the actual output value. If they are equal, the actual output value status is normal, and PID automatic control of the pipeline gas pressure is implemented; If the feedback value output is not equal to the actual output value, the actual output value state is abnormal and the PID module does not work.

[0014] In a specific embodiment of the present invention, the PID automatic control of the pipeline gas pressure specifically includes: After the deviation between the control process measurement value Pv and the PID adjustment set value Sv is combined with the proportionality and the value of the integral time for PID calculation, the PID adjustment output value Mv is output to control the opening of the regulating valve to achieve stable control of the gas pressure in the heavy fraction pipeline.

[0015] In a specific embodiment of the present invention, the control process measurement value Pv is the difference between the gas pressure of the heavy fraction pipeline and the gas pressure of the feed pipeline.

[0016] In a specific embodiment of the present invention, the deviation alarm set value is set in a PID module.

[0017] Compared with the prior art, the uranium enrichment production line working gas pressure control method and device of the present invention has the following beneficial effects; (1) By limiting the absolute deviation between the set value and the actual value of the PID control algorithm, when the absolute deviation exceeds the limit range, the automatic control mode is automatically switched to the manual control mode to lock the opening of the regulating valve. At this time, the operator manually intervenes in the regulating valve opening to adjust the pressure; when the absolute deviation returns to the limit range, the manual control mode is automatically switched to the automatic control mode to perform PID adjustment on the pipeline gas pressure. This avoids pipeline gas pressure fluctuations caused by false signal output fluctuations due to power outages, power supply fluctuations, or self-failures of the corresponding signal acquisition absolute pressure transmitter; at the same time, when the pipeline gas pressure does fluctuate significantly, manual intervention is taken to ensure continuous and stable operation of the system.

[0018] (2) By using the PID control algorithm combined with the regulating valve as the actuator, the difference between the gas pressure of each stage of the heavy fraction pipeline and the gas pressure of the feed pipeline is controlled, and the gas pressure of each stage of the heavy fraction pipeline is adjusted and maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It represents the schematic diagram of the cascade process; 1: N-1 separation stage; 2: N separation stage; 3: N+1 separation stage; 4: regulating valve; 5: heavy fraction pipeline; 6: feed pipeline; 7: light fraction pipeline. DETAILED DESCRIPTION

[0020] In order to further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than for limiting the present invention.

[0021] An embodiment of the present invention discloses a method for controlling the working gas pressure of a uranium enrichment production line, comprising the following steps: Step 1: Install a regulating valve 4 on the heavy fraction pipeline of the N separation stage 2, install a first absolute pressure transmitter required for control on the heavy fraction pipeline 5 before the regulating valve 4, and install a second absolute pressure transmitter on the feed pipeline 6; like Figure 1 As shown, the heavy fraction gas from N separation stage 2 flows through heavy fraction pipeline 5 to N-1 separation stage 1 as feed, and the light fraction gas from N separation stage 2 flows through light fraction pipeline 7 to N+1 separation stage 3 as feed. The feed to N separation stage 2 is composed of the light fraction from N-1 separation stage 1 and the heavy fraction from N+1 separation stage 3. A regulating valve 4 is installed on the heavy fraction pipeline 5 in each separation stage to control the gas pressure in the heavy fraction pipeline.

[0022] Absolute pressure transmitters are used to convert pipeline gas pressure values ​​into electrical signals.

[0023] Since the control method stabilizes the gas pressure of the heavy fraction pipeline of the separation stage before the regulating valve 4 by adjusting the opening of the regulating valve 4 , the first absolute pressure transmitter is installed on the heavy fraction pipeline 5 before the regulating valve 4 .

[0024] Since the heavy fraction gas from N separation stage 2 is fed to N-1 separation stage 1, and the heavy fraction gas from N+1 separation stage 3 is fed to N separation stage 2, to stably control the gas pressure in the heavy fraction pipeline of N separation stage 2, it is not enough to control the heavy fraction gas alone. Instead, the difference between the heavy fraction pipeline gas pressure and the feed pipeline gas pressure should be controlled, i.e., Pv = (heavy fraction pipeline gas pressure) - (feed pipeline gas pressure).

[0025] The opening of the regulating valve 4 is controlled and monitored by a PID module. The output value of the PID module is the input signal of the regulating valve 4, which controls the opening of the regulating valve 4. The output signal of the regulating valve 4 is the input value of the PID module, and the PID module monitors the opening of the regulating valve 4 according to the input value.

[0026] The regulating valve 4 supports 4~20mA.DC input signal and 4~20mA.DC output signal. The regulating valve 4 is preferably a DTF-III regulating valve with two working modes: local and remote control. In local mode, the opening of the regulating valve 4 can only be manually changed and controlled on the control panel of the regulating valve 4 itself; in remote control mode, the opening of the regulating valve 4 is changed and controlled according to the input signal, thereby controlling the pipeline gas pressure within the set range; Step 2: Monitor the deviation between the control process measurement value Pv and the PID adjustment set value Sv. If the deviation is greater than the deviation alarm set value, the DS function block controls the manual and automatic selection switch of the PID module to the manual control mode according to the deviation alarm indication, so that the output value of the PID module can only be manually adjusted on the PID module control panel; If the deviation is less than the deviation alarm set value, the DS function block controls the manual and automatic selection switch of the PID module to be in automatic control mode, and implements PID automatic control of the pipeline gas pressure.

[0027] The DS function block is a digital switch function block in the DCS system.

[0028] The deviation includes a positive deviation and a negative deviation. The positive deviation is a value obtained by subtracting a PID adjustment setting value Sv from a control process measurement value Pv, and the negative deviation is a value obtained by subtracting a control process measurement value Pv from a PID adjustment setting value Sv.

[0029] The specific value of the deviation alarm set value is set in the PID module.

[0030] When the deviation between the control process measurement value Pv and the PID adjustment set value Sv is greater than the deviation alarm set value, an alarm signal is triggered, including positive deviation alarm indication and negative deviation alarm indication; After the positive deviation alarm indication or negative deviation alarm indication appears, the selection switch of the DS function block is turned on and the second input mode is selected. At this time, the input value is a constant, and this constant is used as the output value. Then the manual and automatic selection switch of the PID module is in manual control mode; at this time, the output value of the PID module can only be manually adjusted on the PID module control panel; When there is no positive deviation alarm indication or negative deviation alarm indication, the selection switch of the DS function block is closed, the first input mode is selected, and the manual and automatic selection switch of the control PID module is in automatic control mode; The manual / automatic selector switch is in automatic control mode. The DCS system calculates the feedback value output and feedback status output, and sends the results to the PID module to determine whether the feedback value output is equal to the actual output value. If they are equal, the actual output value status is normal, and the PID automatic control of the pipeline gas pressure is implemented. The specific PID automatic control method of pipeline gas pressure is: After the deviation between the control process measurement value Pv and the PID adjustment set value Sv is combined with the proportionality and the value of the integral time for PID calculation, the PID adjustment output value Mv is output to control the opening of the regulating valve 4 to achieve stable control of the gas pressure in the heavy fraction pipeline.

[0031] The control process measurement value Pv is the difference between the gas pressure in the heavy fraction pipeline and the gas pressure in the feed pipeline.

[0032] If the feedback value output is not equal to the actual output value, the actual output value state is abnormal and the PID module does not work; When the actual output value status is normal, the actual output value feedback status signal is OFF; when the actual output status is abnormal, the actual output value feedback status signal is ON. The PID module works normally only when the actual output value feedback status signal is OFF.

[0033] When the corresponding signal acquisition absolute pressure transmitter experiences false signal output fluctuations due to power outage, power supply fluctuations, or its own failure, the positive and negative deviations of Sv and Pv will exceed the deviation alarm set value. At this time, the DS function block puts the PID module in manual mode, and the opening of the control valve 4 remains unchanged. The gas pressure in the heavy fraction pipeline will not experience large fluctuations, which will cause damage to the current operating process status.

[0034] When the actual pressure deviation of the pipeline is large, the positive or negative deviation between the control process measurement value Pv and the PID adjustment set value Sv will exceed the deviation alarm set value. At this time, the DS function block puts the PID module in manual mode and manually intervenes in the process state.

[0035] At the same time, when the absolute pressure transmitter returns to normal after a failure or the pressure is processed by human intervention, the positive and negative deviations between the control process measurement value Pv and the PID adjustment set value Sv do not exceed the deviation alarm set value, and the PID module returns to automatic mode to continue continuous PID adjustment, thereby realizing continuous automatic control of pipeline gas pressure.

[0036] An embodiment of the present invention further discloses a working gas pressure control device for a uranium enrichment production line, comprising: A regulating valve 4 is provided on the heavy fraction pipeline of the N separation stage 2. A first absolute pressure transmitter required for control is provided on the heavy fraction pipeline 5 before the regulating valve 4, and a second absolute pressure transmitter is installed on the feed pipeline 6. The regulating valve 4 is used to receive the pipeline gas pressure control signal output by the PID module to adjust the opening degree and thus control the pipeline gas pressure. DCS system, including PID module and DS function block, The DS function block is used to perform deviation limit control logic operations and control the PID module to enter manual control mode or automatic control mode; The PID module is used to output a pipeline gas pressure control signal; In the PID module, the PID algorithm only uses the proportional term and the integral term.

[0037] However, this is not a limitation. Depending on the control medium and actual operating conditions, different parameter settings can be made for the proportional, integral, and differential terms. However, in this specific operating condition, only the proportional and integral terms are used based on the actual control effect.

[0038] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0039] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A working gas pressure control device for a uranium enrichment production line, characterized in that: include: A regulating valve is installed on the heavy fraction pipeline of the N separation stage, a first absolute pressure transmitter required for control is installed on the heavy fraction pipeline before the regulating valve, and a second absolute pressure transmitter is installed on the feed pipeline; DCS system, including PID module and DS function block, The DS function block is used to perform deviation limit control logic operations and control the PID module to enter manual control mode or automatic control mode; The PID module is used to control the gas pressure control signal of the output pipeline, and control and monitor the opening of the regulating valve.

2. The working gas pressure control device for a uranium enrichment production line according to claim 1, characterized in that: In the PID module, the PID algorithm only uses the proportional term and the integral term.

3. A method for controlling the working gas pressure of a uranium enrichment production line using the working gas pressure control device of claim 1 or 2, characterized in that: The following steps are involved: Step 1: Install a regulating valve on the heavy fraction pipeline of the N separation stage, install the first absolute pressure transmitter required for control on the heavy fraction pipeline before the regulating valve, and install the second absolute pressure transmitter on the feed pipeline; Step 2: Monitor the deviation between the control process measurement value Pv and the PID adjustment set value Sv. If the deviation is greater than the deviation alarm set value, the DS function block controls the manual and automatic selection switch of the PID module to the manual control mode according to the deviation alarm indication, so that the output value of the PID module can only be manually adjusted on the PID module control panel; If the deviation is less than the deviation alarm setting value, the DS function block controls the manual and automatic selection switch of the PID module to be in the automatic control mode, and implements the PID automatic control of the pipeline gas pressure; The PID module controls and monitors the opening of the regulating valve.

4. The method for controlling working gas pressure in a uranium enrichment production line according to claim 3, characterized in that: The deviation includes a positive deviation and a negative deviation. The positive deviation is a value obtained by subtracting a PID adjustment setting value Sv from a control process measurement value Pv, and the negative deviation is a value obtained by subtracting a control process measurement value Pv from a PID adjustment setting value Sv.

5. The method for controlling working gas pressure in a uranium enrichment production line according to claim 3, characterized in that: The DS function block controls the manual and automatic selection switches of the PID module to be in manual control mode according to the deviation alarm indication. Specifically: Receive deviation alarm indication, The selection switch of the DS function block is turned on and the second input mode is selected. At this time, the input value is a constant, and this constant is used as the output value. The manual and automatic selection switch of the PID module is in manual control mode.

6. The method for controlling working gas pressure in a uranium enrichment production line according to claim 3, characterized in that: The DS function block controls the manual and automatic selection switches of the PID module to be in automatic control mode specifically as follows: When there is no deviation alarm indication, the selection switch of the DS function block is closed, the first input mode is selected, and the manual and automatic selection switch of the PID module is in automatic control mode.

7. The method for controlling working gas pressure in a uranium enrichment production line according to claim 3, characterized in that: After the DS function block controls the manual-automatic selection switch of the PID module to be in the automatic control mode, The DCS system calculates the feedback value output and feedback status output, and sends the results to the PID module to determine whether the feedback value output is equal to the actual output value. If they are equal, the actual output value status is normal, and PID automatic control of the pipeline gas pressure is implemented; If the feedback value output is not equal to the actual output value, the actual output value state is abnormal and the PID module does not work.

8. The method for controlling working gas pressure in a uranium enrichment production line according to claim 7, characterized in that: The PID automatic control of the pipeline gas pressure specifically includes: After the deviation between the control process measurement value Pv and the PID adjustment set value Sv is combined with the proportionality and the value of the integral time for PID calculation, the PID adjustment output value Mv is output to control the opening of the regulating valve to achieve stable control of the gas pressure in the heavy fraction pipeline.

9. The method for controlling working gas pressure in a uranium enrichment production line according to claim 3, characterized in that: The control process measurement value Pv is the difference between the gas pressure of the heavy fraction pipeline and the gas pressure of the feed pipeline.

10. The method for controlling working gas pressure in a uranium enrichment production line according to claim 3, characterized in that: The deviation alarm set value is set in the PID module.

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