In-situ cleaning method based on conductivity signal and time hybrid control

Abstract

The present invention relates to an in-situ cleaning method based on conductivity signal and time mixing control, which comprises the following steps: step 1: flushing the pipeline with clean water for the first time; step 2: flushing the pipeline with alkaline cleaning liquid; step 3: judging whether the conductivity signal at the outlet reaches a threshold value when the alkaline cleaning liquid is introduced; step 4: continuously introducing alkaline cleaning liquid to flush the pipeline; step 5: flushing the pipeline with clean water for the second time to discharge the alkaline cleaning liquid; step 6: flushing the pipeline with acidic cleaning liquid; step 7: judging whether the conductivity signal at the outlet reaches a threshold value when the acidic cleaning liquid is introduced; step 8: continuously introducing acidic cleaning liquid; step 9: flushing with clean water for the third time until there is no residual cleaning liquid in the pipeline, and the final flushing is completed. The present invention sets the process of cleaning with different cleaning agents and flushing with clean water as a mixing zone, and proposes a method for selecting the time parameter of the time control of the mixing zone; and adopts the method of conductivity signal control to ensure that the cleaning agent concentration meets the standard to obtain a good cleaning effect.

Description

Technical Field

[0001] The present application relates to the field of cleaning method control, and in particular to an in-situ cleaning method based on conductivity signal and time mixed control. Background Art

[0002] Cleaning in place is usually abbreviated as cleaning in place. Cleaning in place technology refers to cleaning in a closed loop without disassembling or opening the equipment. It can be used in food and beverage production enterprises with a high degree of mechanization, such as beverages, dairy products, and alcoholic beverages. The system cleaning process is achieved through the configuration of acid, alkali, hot water, circulating pumps, and pipeline systems. The main factors affecting cleaning in place are the cleaning time, flow rate, temperature, and detergent concentration of the cleaning fluid.

[0003] In-situ cleaning adopts a multi-step cleaning process based on factors such as environmental hygiene and product properties. The general five-step in-situ cleaning process is: pre-rinse → alkaline solution cleaning → clean water rinse → acid solution cleaning → clean water rinse → hot water final rinse → end. Whether each step of the cleaning process meets the standards determines whether the in-situ cleaning system enters the next cleaning step.

[0004] The control procedure of in-situ cleaning is a typical time sequence control, and the switching between the cleaning steps usually has two control methods:

[0005] 1. Conductivity signal control: The in-situ cleaning program in the central control system uses the conductivity reaching the corresponding threshold as the switching mark for different cleaning steps.

[0006] 2. Cleaning time control: The in-situ cleaning program in the central control system sets a clear execution time for each step, and switches to the next cleaning step when the running time of the cleaning step ends.

[0007] Patent 200710030802.7 discloses an in-situ cleaning method, including the following steps: cleaning with water; cleaning with a cleaning agent or a diluent of the cleaning agent; cleaning with water; disinfection and sterilization; cleaning with sterile water. Although it can ensure that the cleaning agent concentration reaches the standard and then continue to clean for the necessary time, it relies on a single feedback signal, resulting in a rigid control decision for the in-situ cleaning system to execute each step. Patent 201910616990.4 discloses an in-situ cleaning method, which relates to the field of in-situ cleaning technology, and includes the following steps: step one, introducing circulating water as the first cleaning liquid for cleaning in the equipment, and then discharging; step two, introducing alkaline cleaning liquid as the second cleaning liquid, and continuously cleaning in the equipment for a specified time at a specified flow rate and pressure, and then discharging, and then cleaning with clean water; step three, introducing acidic cleaning liquid as the third cleaning liquid, and continuously cleaning in the equipment for a specified time at a specified flow rate and pressure, and then discharging, and then cleaning with water; step four, passing circulating hot air into the tank pipe of the equipment, and making the temperature of the hot air 60-85℃, and the wind speed 30-40km / h, and completing the cleaning after 5-10min. In order to avoid the mixing of two different cleaning agents in the circuit, clean water must be introduced into the cleaning circuit between the operations of introducing the two cleaning agent solutions as isolation. The process of introducing clean water is called the mixing zone. From the alkaline washing stage to the mixing zone stage and then to the acid washing stage, the conductivity signal shows a trend from high to low and then to high due to the change in the concentration of the cleaning agent at the circuit outlet. The in-situ cleaning process controlled by the conductivity signal is to judge whether the conductivity signal reaches the corresponding threshold as a sign of whether to introduce alkaline solution, clean water, and acid solution into the circuit. In actual applications, it is found that due to the limitation of equipment hardware, the arrangement of sensors can only collect the conductivity signal at the outlet of the cleaning circuit, and cannot reflect the cleaning liquid concentration information of the entire circuit. Therefore, the in-situ cleaning process controlled only by the conductivity signal generally needs to pass the entire circuit through clean water in the mixing zone before starting the next step. When the pipeline is long, the amount of clean water introduced is sufficient to isolate different cleaning liquids, but the in-situ cleaning system cannot perceive the signal in time, resulting in the delay of switching to the next step of in-situ cleaning. That is, the in-situ cleaning procedure based only on conductivity signal control leaves too large a safety margin for the cleaning time, which reduces the execution efficiency of the entire in-situ cleaning process and causes unnecessary waste of water resources.

[0008] The cleaning time control method specifies the execution time of each step in the in-situ cleaning program in advance, which belongs to open-loop timing control. In practical applications, it is necessary to verify the rationality of the execution time setting of each in-situ cleaning step, and take samples and check the cleaning effect after each in-situ cleaning step is executed. Although the in-situ cleaning program with fewer steps adopts this method, which has the advantages of fewer sensors and simple control, if the in-situ cleaning program with more steps relies on time control for each step, it is difficult to ensure the cleaning effect of each step due to the lack of feedback on the concentration of the cleaning agent, which is easy to cause food safety accidents caused by incomplete cleaning.

[0009] In order to face multi-step in-situ cleaning, the in-situ cleaning program is mixedly controlled by conductivity signal and time to achieve a significant increase in the reliability of the in-situ cleaning method and a significant reduction in cost. The present invention provides an in-situ cleaning method with mixed control of conductivity signal and cleaning time. This in-situ cleaning method is mainly aimed at improving the in-situ cleaning process controlled by conductivity signals using two cleaning agents, acidic and alkaline. The process of passing clean water between the two steps of alkaline cleaning and acid cleaning to avoid mixing the two cleaning agents is defined as a mixing zone. The main improvement is to change the control of the execution process of the mixing zone from conductivity signal control to time control. Summary of the invention

[0010] In order to overcome the shortcomings of the prior art, the present invention sets the process of flushing with clean water between cleaning steps with different cleaning agents as a mixing zone; proposes a method for selecting the time parameters of the mixing zone time control process in the mixing zone clean water flushing process; and adopts the conductivity signal control method to ensure that the cleaning agent concentration meets the standard to obtain a good cleaning effect.

[0011] To achieve the above purpose, the solution adopted by the present invention is:

[0012] An in-situ cleaning method based on conductivity signal and time mixing control comprises the following steps:

[0013] Step 1: Flush the pipe with clean water for the first time;

[0014] According to the pipeline length l, the number of internal tanks n and the volume v i , liquid flow rate r and flow rate q are used to calculate the time required for pre-flushing:

[0015]

[0016] Where: T represents the pre-flushing time of the closed pipeline; l represents the length of the pipeline in the closed pipeline; v i represents the volume of the i-th tank; i represents the number of the tank; n represents the total number of tanks; r represents the flow rate of liquid flushing; q represents the flow rate of liquid flushing;

[0017] The first flushing of the pipeline with clean water is carried out using a time control method according to the calculated time parameters, which is called pre-flushing.

[0018] Step 2: flush the pipeline with alkaline cleaning solution;

[0019] An alkaline cleaning solution is introduced into the pipeline inlet to flush the pipeline, and the conductivity signal value at the outlet of the cleaning pipeline is obtained through the conductivity signal sensor at the outlet of the system;

[0020] Step 3: Determine whether the conductivity signal at the outlet reaches a threshold when the alkaline cleaning solution is introduced;

[0021] The conductivity signal of the liquid in the pipeline reflects the concentration of the cleaning liquid. In the manner of conductivity signal control, it is judged whether the conductivity signal at the outlet reaches the threshold set by the cleaning standard TACT. If the conductivity signal reaches the threshold after the alkaline cleaning liquid is flushed into the pipeline, step 4 is performed. If the conductivity signal does not reach the threshold after the alkaline cleaning liquid is flushed into the pipeline, the alkaline cleaning liquid is continuously introduced to flush the pipeline and the conductivity signal at the outlet of the cleaning pipeline is continuously monitored until the conductivity signal reaches the threshold after the pipeline is flushed, and step 4 is performed.

[0022] Step 4: Continue to introduce alkaline cleaning solution to flush the pipeline;

[0023] At the inlet of the cleaning pipeline, an alkaline cleaning liquid is continuously introduced at a constant flow rate and flow rate to flush the pipeline, so that the pressure, flow rate and cleaning time of the cleaning liquid in the pipeline meet the cleaning standard TACT. After the alkaline cleaning step is completed, step 5 is performed;

[0024] Step 5: Rinse the pipe with clean water for the second time to drain the alkaline cleaning solution;

[0025] Introduce clean water into the inlet of the cleaned pipe to discharge the alkaline cleaning liquid in the pipe to prevent the subsequent acidic cleaning agent from contacting the alkaline cleaning agent. After completing this step, proceed to step 6;

[0026] The second clean water flushing operation is time controlled. After the control system continuously introduces clean water according to the time control parameters, the acid-base isolation process under time control is set as the mixing zone, and the time H when the conductivity at the pipeline outlet is zero is used as the characteristic to characterize the isolation effect; the longer the clean water is introduced into the mixing zone, the greater the H; other parameters in the in-situ cleaning mixing zone process include the liquid flow rate V and flow rate Q in the pipeline, and the pressure P in the pipeline, which will affect the relationship between H-T1 by affecting the diffusion of the cleaning liquid. H-T1 is a nonlinear process affected by multiple variables; the expression of the mixing zone time control parameter T1 is:

[0027] T1=f(V,Q,P,T0);

[0028] Where: T1 represents the time control parameter of the mixing zone; f represents the operation of the entire network; V represents the flow rate of the liquid in the pipeline; Q represents the flow rate of the liquid in the pipeline; P represents the pressure in the pipeline; T0 represents the duration of the conductivity signal of the mixing zone being zero;

[0029] Step 6: Flush the pipeline with acid cleaning solution;

[0030] Acid cleaning liquid is introduced into the pipeline inlet to flush the pipeline, and the conductivity signal value at the outlet of the cleaning pipeline is obtained through the conductivity signal sensor at the outlet of the system;

[0031] Step 7: Determine whether the conductivity signal at the outlet reaches a threshold value when the acid cleaning solution is introduced;

[0032] The conductivity signal of the liquid in the pipeline reflects the concentration of the cleaning liquid. In the manner of conductivity signal control, it is judged whether the conductivity signal at the outlet reaches the threshold set by the cleaning standard TACT. If the conductivity signal reaches the threshold after the pipeline is flushed with the acidic cleaning liquid, step 8 is performed. If the conductivity signal does not reach the threshold after the pipeline is flushed with the alkaline cleaning liquid, the alkaline cleaning liquid is continuously introduced to flush the pipeline and the conductivity signal at the outlet of the cleaning pipeline is continuously monitored until the conductivity signal reaches the threshold after the pipeline is flushed, and step 8 is performed.

[0033] Step 8: Continue to introduce acid cleaning solution;

[0034] The acid cleaning liquid is continuously introduced into the cleaning pipeline entrance at a constant flow rate and velocity, so that the pressure, flow rate and cleaning time of the cleaning liquid in the pipeline meet the preset values, and step 9 is performed after the pickling process is completed;

[0035] Step 9: Rinse with clean water for the third time until there is no residual cleaning liquid in the pipeline, completing the final flushing;

[0036] Preferably, the calculation formula for the time parameter in the pre-rinsing time control in step 1 can ensure that the clean water pre-rinsing time of different in-situ cleaning systems can be calculated without adding sensors.

[0037] Preferably, the control mode of the mixing zone in step 5 is time control, and the time when the outlet conductivity is zero is used as a variable to characterize the isolation effect of different cleaning liquids under time control, specifically:

[0038] The in-situ cleaning system relies on the signal that the conductivity at the outlet drops to zero as the control signal to stop this step. The acid-base isolation step will not be completed until the clean water fills the entire pipeline. The clean water introduction time of the acid-base isolation step under the control of the conductivity signal is too long. Reducing the time for introducing clean water can also ensure an effective isolation effect on the acid and alkali cleaning liquids. Changing this step from conductivity signal control to time control has better practical application effects.

[0039] Preferably, the isolation state of the mixed zone in step 5 is divided into an effective isolation state and an invalid isolation state, specifically:

[0040] The effective isolation state is: alkaline cleaning liquid section, diffusion section where alkaline cleaning liquid and clean water are mixed, clean water section, diffusion section where acidic cleaning liquid and clean water are mixed, and acidic cleaning liquid section;

[0041] The invalid isolation state includes: the alkaline cleaning liquid section, the failed section where the acid and alkaline cleaning agents undergo neutralization reaction due to invalid isolation, and the acid cleaning liquid section.

[0042] Preferably, the mixing zone time control parameter T1 in step 5 needs to be obtained through an orthogonal experiment, and the pipeline is cleaned N times under different flow velocities V, flow rates Q, pressures P and mixing zone time parameters T1, and the conductivity data at the outlet is collected to obtain the time H when the conductivity is zero; a data set is constructed with V, Q, H, and P as features and T1 as a label, and an accurate prediction model from H, V, Q, P to T1 is obtained based on deep learning.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The present invention is aimed at an in-situ cleaning system with multiple steps, and the process of flushing with clean water between cleaning steps with different cleaning agents to achieve the TACT standard is calculated as the mixing zone; a method for selecting the time parameters for controlling the mixing zone time is proposed during the flushing process with clean water in the mixing zone.

[0045] (2) The present invention uses conductivity signal control in the cleaning step to ensure that the cleaning agent concentration meets the standard to obtain a good cleaning effect; the proposed in-situ cleaning method can improve the in-situ cleaning efficiency and improve the actual cleaning quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a control block diagram of an in-situ cleaning method based on hybrid control of conductivity signal and time according to an embodiment of the present invention;

[0047] Figure 2 This is a diagram showing the changes of the cleaning liquid in the pipeline in the acid-base isolation step under signal control in an embodiment of the present invention;

[0048] Figure 3 This is a diagram showing the change of the cleaning liquid in the pipeline under time control according to an embodiment of the present invention;

[0049] Figure 4 This is a diagram showing the change of the conductivity signal as the cleaning process progresses according to an embodiment of the present invention;

[0050] Figure 5 A schematic diagram of a one-dimensional residual neural network structure according to an embodiment of the present invention;

[0051] Figure 6 This is a flow chart of model training and model application in an embodiment of the present invention;

[0052] Figure 7 It is an overall flow chart of the in-situ cleaning system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0054] The embodiment of the present invention calculates the process of flushing with clean water between different cleaning agent cleaning steps to achieve the TACT standard as a mixed zone; in the process of flushing with clean water in the mixed zone, a method for selecting a time parameter for controlling the time of a given mixing zone is proposed based on deep learning, and in the cleaning step of the cleaning agent, a conductivity signal control method is used to ensure that the cleaning agent concentration meets the standard to obtain a good cleaning effect, thereby improving the cleaning efficiency of in-situ cleaning. In actual applications, compared with the original method, a single-loop cleaning time and water consumption are significantly reduced. Figure 1 Shown is a control block diagram of an in-situ cleaning method based on hybrid control of conductivity signal and time according to an embodiment of the present invention.

[0055] The embodiment of the present invention provides an in-situ cleaning method based on conductivity signal and time mixing control. In order to prove the applicability of the present invention, it is applied to an example, which specifically includes the following steps:

[0056] S1: First flushing of the pipeline with clean water;

[0057] According to the pipeline length l, the number of internal tanks n and the volume v i , liquid flow rate r and flow rate q to calculate the time required for pre-flushing as follows:

[0058]

[0059] Where: T represents the pre-flushing time of the closed pipeline; l represents the length of the pipeline in the closed pipeline; v i represents the volume of the i-th tank; i represents the number of the tank; n represents the total number of tanks; r represents the flow rate of liquid flushing; q represents the flow rate of liquid flushing;

[0060] The first flushing of the pipeline with clean water is carried out using a time control method based on the calculated time parameters, which is called pre-flushing.

[0061] S2: flush the pipeline with alkaline cleaning solution;

[0062] Alkaline cleaning liquid is introduced into the pipeline inlet to flush the pipeline, and the conductivity signal value at the outlet of the cleaning pipeline is obtained through the conductivity signal sensor at the outlet of the system.

[0063] S3: Determine whether the conductivity signal at the outlet reaches a threshold value when the alkaline cleaning solution is introduced;

[0064] The conductivity signal of the liquid in the pipeline reflects the concentration of the cleaning liquid. The conductivity signal is controlled to determine whether the conductivity signal at the outlet reaches the threshold set by the cleaning standard TACT. If the conductivity signal reaches the threshold after the pipeline is flushed with alkaline cleaning liquid, S4 is performed. If the conductivity signal cannot reach the threshold after the pipeline is flushed with alkaline cleaning liquid, the alkaline cleaning liquid is continuously introduced to flush the pipeline and the conductivity signal at the outlet of the cleaning pipeline is continuously monitored, and S3 is repeated.

[0065] S4: continuously introduce alkaline cleaning solution to flush the pipeline;

[0066] At the inlet of the cleaning pipeline, alkaline cleaning liquid is continuously introduced at a constant flow rate and flow rate to flush the pipeline, so that the pressure, flow rate and cleaning time of the cleaning liquid in the pipeline meet the TACT standard of the cleaning industry. After the alkaline cleaning step is completed, S5 is performed.

[0067] S5: flush the pipe with clean water for the second time to discharge the alkaline cleaning solution;

[0068] Clean water is introduced into the inlet of the cleaned pipeline to discharge the alkaline cleaning liquid in the pipeline to avoid the subsequent contact between the acidic cleaning agent and the alkaline cleaning agent. After completing this step, enter S8; the purpose of setting the mixing zone is to reduce the time of introducing clean water and to isolate the acid and alkaline cleaning liquids well. The time parameter selection of time control directly affects the isolation effect, and then directly affects the cleaning effect. The control method of the mixing zone is time control. The existing in-situ cleaning system relies on the signal of the conductivity at the outlet dropping to zero as the control signal to stop this step. Therefore, this acid-base isolation step will not be terminated until the clean water fills the entire pipeline. The clean water introduction time of the acid-base isolation step under the control of the conductivity signal is too long. Reducing the time of introducing clean water can also ensure that the acid and alkaline cleaning liquids have an effective isolation effect. Therefore, changing this step from conductivity signal control to time control can better meet actual needs.

[0069] The isolation status of the mixed zone is divided into effective isolation status and invalid isolation status.

[0070] The effective isolation states are: alkaline cleaning liquid section, diffusion section where alkaline cleaning liquid and clean water are mixed, clean water section, diffusion section where acidic cleaning liquid and clean water are mixed, and acidic cleaning liquid section.

[0071] The invalid isolation state is: the alkaline cleaning liquid section, the failed section where the acid and alkaline cleaning agents undergo neutralization reaction due to invalid isolation, and the acid cleaning liquid section.

[0072] The second clean water flushing operation is time-controlled. After the control system continuously introduces clean water according to the time control parameters, the acid-base isolation process under time control is defined as the mixing zone. The purpose is to reduce the time for introducing clean water and to isolate the acid and alkali cleaning liquids well. Therefore, the time H when the conductivity at the pipeline outlet is zero is used as a feature to characterize the isolation effect; the longer the clean water is introduced into the mixing zone, the greater H; in addition, other parameters in the in-situ cleaning mixing zone process, including the liquid flow rate V and flow rate Q in the pipeline, and the pressure P in the pipeline, will affect the relationship between H-T1 by affecting the diffusion of the cleaning liquid. Therefore, H-T1 is a nonlinear process affected by multiple variables; therefore, the selection of the time control parameter T1 in the mixing zone is a multivariate nonlinear regression problem, and the specific mathematical model is shown in the following formula:

[0073] T1=f(V,Q,P,T0);

[0074] Where: T1 represents the time control parameter of the mixing zone; f represents the operation of the entire network; V represents the flow rate of the liquid in the pipeline; Q represents the flow rate of the liquid in the pipeline; P represents the pressure in the pipeline; T0 represents the duration of the conductivity signal of the mixing zone being zero;

[0075] The main reason why the in-situ cleaning method that combines conductivity signal and time control can reduce costs and increase efficiency compared to the in-situ cleaning method that relies solely on conductivity control is that it reduces the mixing zone time and the amount of clean water used in the mixing zone. During the in-situ cleaning process under the two control methods, the cleaning liquid in the equipment circuit in the mixing zone is as follows: Figure 2 and Figure 3 As shown, Figure 2 It is reflected in the mixing zone step of the original method that the acid solution is introduced only when there is no alkali solution in the entire circuit and it is completely filled with clean water, which causes unnecessary waste of cleaning time and water resources when the equipment capacity is large; Figure 3 The figure reflects the liquid condition in the circuit when the time for which clean water is introduced into the mixing zone is controlled by time. The clean water in the circuit plays the role of isolating the cleaning liquids in the upper and lower steps. The conductivity signal at the outlet of the equipment circuit changes as the cleaning process progresses. Figure 4 As shown in the figure, considering that the loop contains curved pipes, tanks, valves and a total length of 200m, as well as the diffusion effect of the cleaning liquid, the change of the conductivity signal at the outlet is a nonlinear process over time. The oblique line in the figure only represents the change trend of conductivity. Therefore, it is difficult to directly determine the appropriate time parameter. It is necessary to introduce the deep learning model in the third step to predict the time for the introduction of clean water into the mixing zone. Figure 2 , Figure 3 and Figure 4 The changes in outlet conductivity and their principles during the in-situ cleaning process under two control modes are revealed, as well as the cost-reduction and efficiency-enhancing principle of the in-situ cleaning method under the mixed control of conductivity signal and time. Figure 5Shown is a schematic diagram of a one-dimensional residual neural network structure according to an embodiment of the present invention.

[0076] S6: flush the pipeline with acid cleaning solution;

[0077] Acid cleaning fluid is introduced into the pipeline inlet to flush the pipeline, and the conductivity signal value at the outlet of the cleaning pipeline is obtained through the conductivity signal sensor at the outlet of the system.

[0078] S7: Determine whether the conductivity signal at the outlet reaches a threshold value when the acid cleaning solution is introduced;

[0079] The conductivity signal of the liquid in the pipeline reflects the concentration of the cleaning liquid. The conductivity signal is controlled to determine whether the conductivity signal at the outlet reaches the threshold set by the cleaning standard TACT. If the conductivity signal reaches the threshold after the pipeline is flushed with the acidic cleaning liquid, S8 is performed. If the conductivity signal cannot reach the threshold after the pipeline is flushed with the alkaline cleaning liquid, the alkaline cleaning liquid is continuously introduced to flush the pipeline and the conductivity signal at the outlet of the cleaning pipeline is continuously monitored, and S7 is repeated.

[0080] S8: continuously introducing acid cleaning solution;

[0081] Acidic cleaning liquid is continuously introduced into the inlet of the cleaning pipeline at a constant flow rate and velocity, so that the pressure, flow rate and cleaning time of the cleaning liquid in the pipeline meet the TACT standard of the cleaning industry. After the pickling process is completed, S9 is carried out.

[0082] S9: The third flushing with clean water is completed until there is no residual cleaning liquid in the pipeline, and the final flushing is completed;

[0083] Finally, the method of applying the model in the actual in-situ cleaning process is that after the in-situ cleaning reaches the mixing zone step, the inlet flow value, inlet velocity value, pressure value in the pipeline, and the desired safety margin obtained by the in-situ cleaning control system, that is, the duration of zero conductivity at the outlet of the mixing zone, are input into the model to obtain the corresponding water flushing time of the mixing zone, which is the final duration parameter of the mixing zone time control. The entire process of data set construction, model training and application is as follows: Figure 6 Shown is a flow chart of model training and model application according to an embodiment of the present invention.

[0084] The overall flow chart of the in-situ cleaning system of the embodiment of the present invention is as follows: Figure 7As shown in the figure, the proposed in-situ cleaning method was run by an in-situ cleaning system of a certain company, and the switching of the clean water flushing step between each cleaning agent cleaning step was changed from conductivity signal control to time control. The original in-situ cleaning system contained three clean water flushing steps. The mixing zone time of each water filling section was calculated as follows: the first clean water flushing pipeline time was 6 minutes, the second clean water flushing time was 10 minutes, and the third clean water flushing time was 6 minutes. The above clean water flushing time accounted for 38% of the entire in-situ cleaning time. After the technical improvement of this method, the time of the three mixing zones was reduced by 3 minutes in total, which was 5.2% less than the original cleaning time, saving 1.25 tons of water per time, and the estimated annual water saving for a single loop was 140 tons.

[0085] In summary, the prediction results of this case prove to be very effective.

[0086] (1) The embodiment of the present invention is aimed at an in-situ cleaning system with multiple steps. The process of flushing with clean water between cleaning steps with different cleaning agents to achieve the TACT standard is calculated as the mixing zone. In the process of flushing with clean water in the mixing zone, a method for selecting time parameters for controlling the time of a given mixing zone is proposed based on deep learning, and is introduced in detail in the implementation case, including: the construction process of a dataset for predicting the time of the mixing zone in a multi-step in-situ cleaning loop, the training method of the mapping model, and the method of using the model.

[0087] (2) In the cleaning step of the cleaning agent, the embodiment of the present invention adopts the conductivity signal control method to ensure that the cleaning agent concentration meets the standard to obtain a good cleaning effect.

[0088] (3) The in-situ cleaning method proposed in the embodiment of the present invention can improve the cleaning efficiency of in-situ cleaning. In practical applications, compared with the original method, it can significantly reduce the cleaning time and water consumption of a single-loop cleaning.

[0089] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An in-situ cleaning method based on conductivity signal and time mixed control, characterized in that: It includes the following steps: Step 1: Flush the pipe with clean water for the first time; According to the pipeline length l, the number of internal tanks n and the volume v i , liquid flow rate r and flow rate q are used to calculate the time required for pre-flushing: Where: T represents the pre-flushing time of the closed pipeline; l represents the length of the pipeline in the closed pipeline; v i represents the volume of the i-th tank; i represents the number of the tank; n represents the total number of tanks; r represents the flow rate of liquid flushing; q represents the flow rate of liquid flushing; The first flushing of the pipeline with clean water is carried out using a time control method according to the calculated time parameters, which is called pre-flushing. Step 2: flush the pipeline with alkaline cleaning solution; An alkaline cleaning solution is introduced into the pipeline inlet to flush the pipeline, and the conductivity signal value at the outlet of the cleaning pipeline is obtained through the conductivity signal sensor at the outlet of the system; Step 3: Determine whether the conductivity signal at the outlet reaches a threshold when the alkaline cleaning solution is introduced; The conductivity signal of the liquid in the pipeline reflects the concentration of the cleaning liquid. In the manner of conductivity signal control, it is judged whether the conductivity signal at the outlet reaches the threshold set by the cleaning standard TACT. If the conductivity signal reaches the threshold after the alkaline cleaning liquid is flushed into the pipeline, step 4 is performed. If the conductivity signal does not reach the threshold after the alkaline cleaning liquid is flushed into the pipeline, the alkaline cleaning liquid is continuously introduced to flush the pipeline and the conductivity signal at the outlet of the cleaning pipeline is continuously monitored until the conductivity signal reaches the threshold after the pipeline is flushed, and step 4 is performed. Step 4: Continue to pass alkaline cleaning solution to flush the pipeline; At the inlet of the cleaning pipeline, an alkaline cleaning liquid is continuously introduced at a constant flow rate and flow rate to flush the pipeline, so that the pressure, flow rate and cleaning time of the cleaning liquid in the pipeline meet the cleaning standard TACT. After the alkaline cleaning step is completed, step 5 is performed; Step 5: Rinse the pipe with clean water for the second time to drain the alkaline cleaning solution; Introduce clean water into the inlet of the cleaned pipe to discharge the alkaline cleaning liquid in the pipe to prevent the subsequent acidic cleaning agent from contacting the alkaline cleaning agent. After completing this step, proceed to step 6; The second clean water flushing operation is time controlled. After the control system continuously introduces clean water according to the time control parameters, the acid-base isolation process under time control is set as the mixing zone, and the time H when the conductivity at the pipeline outlet is zero is used as the characteristic to characterize the isolation effect; The longer the time T1 of water entering the mixing zone is, the greater the H is. Other parameters in the process of in-situ cleaning of the mixing zone include the liquid velocity V and flow rate Q in the pipeline, and the pressure P in the pipeline, which will affect the relationship between H and T1 by affecting the diffusion of the cleaning liquid. H and T1 is a nonlinear process affected by multiple variables. The expression of the mixing zone time control parameter T1 is: T1=f(V,Q,P,T0); Where: T1 represents the time control parameter of the mixing zone; f represents the operation of the entire network; V represents the liquid flow rate in the pipeline; Q represents the liquid flow rate in the pipeline; P represents the pressure in the pipeline; T0 represents the duration of the conductivity signal of the mixing zone being zero; Step 6: Flush the pipeline with acid cleaning solution; Acid cleaning liquid is introduced into the pipeline inlet to flush the pipeline, and the conductivity signal value at the outlet of the cleaning pipeline is obtained through the conductivity signal sensor at the outlet of the system; Step 7: Determine whether the conductivity signal at the outlet reaches a threshold value when the acid cleaning solution is introduced; The conductivity signal of the liquid in the pipeline reflects the concentration of the cleaning liquid. In the manner of conductivity signal control, it is judged whether the conductivity signal at the outlet reaches the threshold set by the cleaning standard TACT. If the conductivity signal reaches the threshold after the pipeline is flushed with the acidic cleaning liquid, step 8 is performed. If the conductivity signal does not reach the threshold after the pipeline is flushed with the alkaline cleaning liquid, the alkaline cleaning liquid is continuously introduced to flush the pipeline and the conductivity signal at the outlet of the cleaning pipeline is continuously monitored until the conductivity signal reaches the threshold after the pipeline is flushed, and step 8 is performed. Step 8: Continue to introduce acid cleaning solution; The acid cleaning liquid is continuously introduced into the cleaning pipeline entrance at a constant flow rate and velocity, so that the pressure, flow rate and cleaning time of the cleaning liquid in the pipeline meet the preset values, and step 9 is performed after the pickling process is completed; Step 9: Rinse with clean water for the third time until there is no residual cleaning liquid in the pipeline, completing the final rinse.

2. The in-situ cleaning method based on conductivity signal and time mixed control according to claim 1, characterized in that: The calculation formula for the time parameter in the pre-rinsing time control in step 1 can ensure that the clean water pre-rinsing time of different in-situ cleaning systems can be calculated without adding sensors.

3. The in-situ cleaning method based on conductivity signal and time mixed control according to claim 1, characterized in that: The control method of the mixing zone in step 5 is time control, and the time when the outlet conductivity is zero is used as a variable to characterize the isolation effect of different cleaning liquids under time control, specifically: The in-situ cleaning system relies on the signal that the conductivity at the outlet drops to zero as the control signal to stop this step. The acid-base isolation step will not be completed until the clean water fills the entire pipeline. The clean water introduction time of the acid-base isolation step under the control of the conductivity signal is too long. Reducing the time for introducing clean water can also ensure an effective isolation effect on the acid and alkali cleaning liquids. Changing this step from conductivity signal control to time control has better practical application effects.

4. The in-situ cleaning method based on conductivity signal and time mixed control according to claim 1, characterized in that: The isolation state of the mixed zone in step 5 is divided into a valid isolation state and an invalid isolation state, specifically: The effective isolation state is: alkaline cleaning liquid section, diffusion section where alkaline cleaning liquid and clean water are mixed, clean water section, diffusion section where acidic cleaning liquid and clean water are mixed, and acidic cleaning liquid section; The invalid isolation state includes: the alkaline cleaning liquid section, the failed section where the acid and alkaline cleaning agents undergo neutralization reaction due to invalid isolation, and the acid cleaning liquid section.

5. The in-situ cleaning method based on conductivity signal and time mixed control according to claim 1, characterized in that: The mixing zone time control parameter T1 in step 5 needs to be obtained through orthogonal experiments. Under different flow velocities V, flow rates Q, pressures P and mixing zone time parameters T1, the pipeline is cleaned N times, and the conductivity data at the outlet is collected to obtain the time H when the conductivity is zero; A data set is constructed with V, Q, H, and P as features and T1 as the label, and an accurate prediction model from H, V, Q, P to T1 is obtained based on deep learning.

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