PAC automatic dosing control method and system applied to sewage treatment process

Abstract

The present invention provides a PAC automatic dosing control method and system applied to sewage treatment process, comprising the following steps: step 1, data input; step 2, calculating the reagent treatment capacity; step 3, calculating the recommended total dosing flow rate; step 4, calculating the pump frequency to flow rate coefficient; step 5, calculating the recommended dosing pump frequency value; step 6, judging the pump frequency output, continuously calculating the recommended dosing pump frequency value according to step 2 to step 5, and sending the recommended dosing pump frequency value to the on-site PLC substation to control the dosing pump frequency. The PAC automatic dosing control method and system realize PAC intelligent regulation without considering the complex process parameters of the biochemical process section.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and in particular to a PAC automatic dosing control method and system applied to sewage treatment technology. Background Art

[0002] In the sewage treatment industry, PAC agents have the functions of flocculation, adsorption, precipitation, and enhancement in the tertiary deep treatment of water purification plants, and can effectively remove SS, TP, etc. in water.

[0003] During the daily operation of the plant, the PAC dosing process often relies on operators to manually monitor the plant's inlet water quality, inlet flow, outlet water quality, outlet flow and water quality indicators of each intermediate process section, and then subjectively judge whether the dosing pump frequency needs to be adjusted and the specific adjustment value based on manual experience.

[0004] The traditional dosing method requires operators to pay attention to the above indicators at all times, and the dosing pump is adjusted frequently, which requires a large workload for operators; it is easy to cause untimely response speed when facing emergencies such as abnormal water inflow, resulting in substandard effluent water quality; it is highly dependent on the personal experience of on-site operators, resulting in poor replaceability of plant operators; relying on human experience to adjust the frequency of the dosing pump is prone to waste of drugs and electricity, and is not conducive to the stable operation of the plant's sewage treatment process.

[0005] In response to the above problems, general water purification plants use automation technology, combined with online monitoring data such as the operating parameters of dosing and dispensing equipment, to calculate according to a certain program algorithm, and then the PLC substation controls the flow of PAC addition, ignoring the impact of inlet and outlet water quality and flow on the calculation results.

[0006] The existing algorithm technology research in the industry is generally based on the perception layer of multi-link and multi-index parameters in the sewage treatment process. The large number and variety of input parameter requirements simultaneously bring about problems such as high construction cost, high maintenance cost, and poor program algorithm stability. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a PAC automatic dosing control method and system applied to sewage treatment process, which realizes PAC intelligent regulation without considering the complex process parameters of the biochemical process section.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a PAC automatic dosing control method applied to sewage treatment process, comprising the following steps:

[0009] Step 1: Data input;

[0010] Step 2: Calculate the pharmaceutical processing capacity;

[0011] Step 3: Calculate the recommended total flow rate for dosing;

[0012] Step 4: Calculate the pump frequency flow coefficient;

[0013] Step 5: Calculate the recommended frequency value of the dosing pump;

[0014] Step 6: Determine the pump frequency output, and continuously calculate the recommended frequency value of the dosing pump according to steps 2 to 5, and send the recommended frequency value of the dosing pump to the on-site PLC substation to control the frequency of the dosing pump.

[0015] In a preferred solution, in step 1, the input data include the inlet flow rate CF, the outlet flow rate OF, the inlet phosphorus concentration CTP, the outlet phosphorus concentration OTP, the flow rate of each dosing pump and the frequency of the dosing pump.

[0016] In the preferred solution, in step 2, the calculation formula of the drug processing capacity D_a is as follows:

[0017] TCTP=CF×CTP

[0018] TOTP=OF×OTP

[0019] KTP=TCTP-TOTP

[0020] D_a=KTP÷TDF

[0021] In the above formula: CF represents the inlet flow rate, CTP represents the inlet phosphorus concentration, TCTP represents the total inlet phosphorus, OF represents the outlet flow rate, OTP represents the outlet phosphorus concentration, TOTP represents the total outlet phosphorus, KTP represents the total phosphorus removal, D_a represents the chemical treatment capacity, TDF is the total dosing flow, which is the sum of the dosing flow rates of each dosing pump.

[0022] In the preferred solution, in step 3, the calculation formula for the recommended value of the total dosing flow rate is as follows:

[0023] su_TDF=(TCTP-OF×Q_OTP)÷D_a

[0024] In the above formula: su_TDF represents the recommended total dosing flow rate, and Q_OTP is the expected effluent phosphorus concentration.

[0025] In the preferred solution, in step 4, the calculation formula of the pump frequency flow coefficient is as follows:

[0026] F_DF=F÷TDF

[0027] In the above formula: F_DF represents the pump frequency flow coefficient, F is the sum of the frequencies of the dosing pumps, and is the sum of the frequencies of each dosing pump.

[0028] In the preferred solution, in step 5, the calculation formula for the recommended value of the dosing pump frequency is as follows:

[0029] su_F=su_TDF×F_DF÷n

[0030] In the above formula: su_F represents the recommended value of dosing pump frequency, su_TDF represents the recommended value of total dosing flow, F_DF represents the pump frequency to flow coefficient, and n is the number of dosing pumps put into use in daily mode.

[0031] In the preferred solution, in step 6, judging the pump frequency output is divided into the following two situations:

[0032] Case 1: When the effluent phosphorus concentration is abnormal or the dosing pump frequency is abnormal, that is, the effluent phosphorus concentration does not belong to the safe range of effluent phosphorus concentration or the dosing pump frequency does not belong to the adjustable range of the dosing pump frequency Q:

[0033] When the recommended value of the dosing pump frequency belongs to the adjustable range Q of the dosing pump frequency, the recommended value of the dosing pump frequency will be sent to the corresponding dosing pump according to the input of the dosing pump; when the recommended value of the dosing pump frequency is less than the minimum value Q of the adjustable range of the dosing pump frequency min , then according to the input of the dosing pump, Q min Send it to the corresponding dosing pump; when the recommended value of the dosing pump frequency is greater than the maximum value Q of the adjustable range of the dosing pump frequency max , then according to the input of the dosing pump, Q max Send it to the corresponding dosing pump;

[0034] Case 2: When the cumulative time since the last command is issued reaches T:

[0035] When the absolute value of the difference between the recommended value of the dosing pump frequency and the dosing pump frequency is less than the dosing pump frequency adjustment dead zone C, the recommended value of the dosing pump frequency will not be issued;

[0036] When the absolute value of the difference between the recommended value of the dosing pump frequency and the dosing pump frequency is greater than or equal to the dosing pump frequency adjustment dead zone C: When the recommended value of the dosing pump frequency belongs to the adjustable range of the dosing pump frequency interval Q, the recommended value of the dosing pump frequency will be sent to the corresponding dosing pump according to the input of the dosing pump; When the recommended value of the dosing pump frequency is less than the minimum value of the adjustable range of the dosing pump frequency interval Q min , then according to the input of the dosing pump, Q min Send it to the corresponding dosing pump; when the recommended value of the dosing pump frequency is greater than the maximum value Q of the adjustable range of the dosing pump frequency max , then the input of the dosing pump will be Q max Send it to the corresponding dosing pump.

[0037] The present invention also provides a PAC automatic dosing system applied to a sewage treatment process, including a data acquisition unit, which collects various types of data information on site and summarizes them to an on-site PLC substation and a host computer server; including an intelligent control calculation unit, which is a built-in unit of the host computer, and a dosing control program is stored in the intelligent control calculation unit to implement the steps of a PAC automatic dosing control method applied to a sewage treatment process as described above; including a reagent input unit, which includes a PAC dosing pump, and the host computer server sends a recommended frequency value of the dosing pump to the on-site PLC substation to control the frequency of the dosing pump.

[0038] The present invention provides a PAC automatic dosing control method and system applied to a sewage treatment process, which has the following beneficial effects:

[0039] 1. In the sewage treatment process of a water purification plant, the main function of adding PAC reagents is to remove phosphorus, that is, the current reagent treatment capacity can be calculated based on the total phosphorus content of the influent, the total phosphorus content of the effluent, and the total flow rate of the reagent. PAC liquid reagents are often made by mixing solid powder and water. In theory, the phosphorus removal capacity of PAC liquid reagents will change slightly accordingly. The algorithm of the present invention calculates the latest value of the phosphorus removal capacity of the reagent in real time, which can effectively avoid the influence of this error.

[0040] 2. In the sewage treatment process of the water purification plant, the main function of adding PAC reagents is to remove phosphorus. That is, the recommended value of the current total dosing flow rate can be calculated based on the total phosphorus content in the influent, the expected total phosphorus content in the effluent, and the current reagent treatment capacity.

[0041] 3. With the continuous operation and wear of the dosing pump, the pump frequency flow coefficient will theoretically also undergo slight changes. The algorithm of the present invention calculates the latest value of the pump frequency flow coefficient in real time, which can effectively avoid the influence of this error.

[0042] 4. In actual operation, in order to prevent the adjustment action from causing too much impact on the dosing pump and biochemical process, the factory dosing pump usually limits the frequency adjustment range; in order to prevent the program from frequently issuing adjustment commands to the dosing pump frequency, which is not conducive to the stable operation of the dosing pump, it is necessary to introduce the concept of dosing pump frequency adjustment dead zone. The algorithm of the present invention effectively considers and avoids the occurrence of the above problems, and classifies and considers the pump frequency output adjustment under abnormal water outlet TP or abnormal dosing pump frequency and normal operation.

[0043] 5. The present invention effectively considers various influencing factors in the addition of PAC reagents in the sewage treatment process of the water purification plant. The algorithm logic is clear and complete, close to the actual situation on site, and has been successfully applied to a water purification plant in the south with good results.

[0044] 6. Compared with traditional algorithms, this patent realizes PAC intelligent control without considering the complex process parameters of the biochemical process section, reduces construction costs, and has strong popularization potential.

[0045] 7. The system of the present invention has friendly human-computer interaction and is easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0047] Figure 1 is a control flow chart of the present invention;

[0048] Figure 2 This is a diagram of the actual operation interface of the present invention. DETAILED DESCRIPTION

[0049] This embodiment is implemented based on a water purification plant in the south. The dosing system includes three PAC dosing pumps. The daily use mode is two for use and one for backup. There are two PAC mixed liquid output pipelines, both of which are equipped with flow meters.

[0050] like Figure 1 As shown, a PAC automatic dosing control method applied to a sewage treatment process comprises the following steps:

[0051] Step 1: Data input.

[0052] The data acquisition unit collects various data information on site, aggregates them to the on-site PLC substation, and transmits the data to the host server, which has a built-in intelligent control computing unit.

[0053] The input data, i.e. the input of the program algorithm, includes the inlet flow rate CF, the outlet flow rate OF, the inlet phosphorus concentration CTP, the outlet phosphorus concentration OTP, the flow rate of each dosing pump and the frequency of the dosing pump.

[0054] Inlet flow: CF, unit: m 3 / h; Outflow rate: OF, unit: m 3 / h.

[0055] Influent phosphorus concentration: CTP, unit: mg / L; effluent phosphorus concentration: OTP, unit: mg / L.

[0056] The dosing flow rate of pump No. 1 is: 1DF, unit L / h; the dosing flow rate of pump No. 2 is: 2DF, unit L / h; the dosing flow rate of pump No. 3 is: 3DF, unit L / h.

[0057] The frequency of pump No. 1 is 1F, in Hz; the frequency of pump No. 2 is 2F, in Hz; the frequency of pump No. 3 is 3F, in Hz.

[0058] Expected effluent phosphorus concentration: Q_OTP, unit: mg / L. This indicator is an adjustable parameter of the host server.

[0059] Outlet phosphorus concentration safety range: OTP_Q, this indicator is an adjustable parameter of the host server.

[0060] The adjustable range of the dosing pump frequency is: Q = [Qmin, Qmax], which is an adjustable parameter of the host computer server.

[0061] Dosing pump frequency adjustment dead zone: C, this indicator is an adjustable parameter of the host computer server.

[0062] Automatic dosing system start and end status: TT, this indicator is an adjustable parameter of the upper computer. When the automatic dosing mode is activated, TT=1, and when the automatic dosing mode is exited, TT=0.

[0063] Adjustment cycle: T, this indicator is an adjustable parameter of the host computer.

[0064] Pump selection plan: CASE. This indicator is an adjustable parameter of the host computer server. When pumps 1 and 2 are selected, CASE=3; when pumps 1 and 3 are selected, CASE=4; when pumps 2 and 3 are selected, CASE=5.

[0065] Step 2: Calculate the drug processing capacity through the intelligent control computing unit.

[0066] The calculation formula of the drug processing capacity D_a is as follows:

[0067] TCTP=CF×CTP

[0068] TOTP=OF×OTP

[0069] KTP=TCTP-TOTP

[0070] D_a=KTP÷TDF

[0071] In the above formula: CF represents the inlet flow rate, CTP represents the inlet phosphorus concentration, TCTP represents the total inlet phosphorus, OF represents the outlet flow rate, OTP represents the outlet phosphorus concentration, TOTP represents the total outlet phosphorus, KTP represents the total phosphorus removal, D_a represents the chemical treatment capacity, TDF is the total dosing flow, which is the sum of the dosing flow rates of each dosing pump.

[0072] In this embodiment, the total dosing flow rate = the dosing flow rate of pump No. 1 + the dosing flow rate of pump No. 2 + the dosing flow rate of pump No. 3, that is, TDF = 1DF + 2DF + 3DF.

[0073] Step 3: Calculate the recommended total dosing flow rate.

[0074] The calculation formula for the recommended total dosing flow rate is as follows:

[0075] su_TDF=(TCTP-OF×Q_OTP)÷D_a

[0076] In the above formula: su_TDF represents the recommended total dosing flow rate, and Q_OTP is the expected effluent phosphorus concentration.

[0077] Step 4: Calculate the pump frequency flow coefficient.

[0078] The calculation formula of pump frequency flow coefficient is as follows:

[0079] F_DF=F÷TDF

[0080] In the above formula: F_DF represents the pump frequency flow coefficient, F is the sum of the frequencies of the dosing pumps, and is the sum of the frequencies of each dosing pump.

[0081] In this embodiment, the sum of the frequencies of the dosing pumps = the frequency of pump No. 1 + the frequency of pump No. 2 + the frequency of pump No. 3, that is, F = 1F + 2F + 3F.

[0082] Step 5: Calculate the recommended frequency of the dosing pump.

[0083] The calculation formula for the recommended value of the dosing pump frequency is as follows:

[0084] su_F=su_TDF×F_DF÷n

[0085] In the above formula: su_F represents the recommended value of the dosing pump frequency, su_TDF represents the recommended value of the total dosing flow rate, F_DF represents the pump frequency-to-flow coefficient, and n is the number of dosing pumps put into use in the daily mode. In this embodiment, n is 2.

[0086] Step 6: Determine the pump frequency output, and continuously calculate the recommended frequency value of the dosing pump according to steps 2 to 5. When TT=1, send the recommended frequency value of the dosing pump to the on-site PLC substation to control the frequency of the dosing pump. The operating interface of PAC dosing control using this method is as follows Figure 2 shown.

[0087] There are two situations to judge the pump frequency output:

[0088] Case 1: When the effluent phosphorus concentration is abnormal or the dosing pump frequency is abnormal, that is, the effluent phosphorus concentration does not belong to the safe range of effluent phosphorus concentration or the dosing pump frequency does not belong to the adjustable range of the dosing pump frequency Q:

[0089] When the recommended value of the dosing pump frequency belongs to the adjustable range Q of the dosing pump frequency, the recommended value of the dosing pump frequency is sent to the corresponding dosing pump according to the current value of CASE; when the recommended value of the dosing pump frequency is less than the minimum value Q of the adjustable range of the dosing pump frequency min , then according to the current value of CASE, Qmin Send it to the corresponding dosing pump; when the recommended value of the dosing pump frequency is greater than the maximum value Q of the adjustable range of the dosing pump frequency max , then according to the current value of CASE, Q max Send it to the corresponding dosing pump.

[0090] Case 2: When TT = 1 and the cumulative time since the last command is issued reaches T:

[0091] When the absolute value of the difference between the recommended value of the dosing pump frequency and the dosing pump frequency is less than the dosing pump frequency adjustment dead zone C, the recommended value of the dosing pump frequency will not be issued;

[0092] When the absolute value of the difference between the recommended value of the dosing pump frequency and the dosing pump frequency is greater than or equal to the dosing pump frequency adjustment dead zone C: When the recommended value of the dosing pump frequency belongs to the adjustable range of the dosing pump frequency interval Q, the recommended value of the dosing pump frequency is sent to the corresponding dosing pump according to the current value of CASE; When the recommended value of the dosing pump frequency is less than the minimum value of the adjustable range of the dosing pump frequency interval Q min , then according to the current value of CASE, Q min Send it to the corresponding dosing pump; when the recommended value of the dosing pump frequency is greater than the maximum value Q of the adjustable range of the dosing pump frequency max , then the input of the dosing pump will be Q max Send it to the corresponding dosing pump.

[0093] The working principle of the PAC automatic dosing control method and dosing system is as follows:

[0094] In the sewage treatment process of a water purification plant, the main function of adding PAC reagents is to remove phosphorus, that is, the current reagent treatment capacity can be calculated based on the total phosphorus content of the influent, the total phosphorus content of the effluent, and the total flow rate of the reagent. It is worth noting that PAC liquid reagents are often mixed and stirred with solid powder and water. In theory, the phosphorus removal capacity of PAC liquid reagents will change slightly accordingly. The algorithm of the present invention calculates the latest value of the reagent's phosphorus removal capacity in real time, which can effectively avoid the influence of this error.

[0095] In the sewage treatment process of the water purification plant, the main function of adding PAC reagents is to remove phosphorus. That is, the recommended value of the current total dosing flow rate can be calculated based on the total phosphorus content in the influent, the expected total phosphorus content in the effluent, and the current reagent treatment capacity.

[0096] As the dosing pump continues to wear out during operation, the pump frequency flow coefficient will theoretically also undergo slight changes. The algorithm of the present invention calculates the latest value of the pump frequency flow coefficient in real time, which can effectively avoid the influence of this error.

[0097] In actual operation, in order to prevent the adjustment action from causing too much impact on the dosing pump and biochemical process, the dosing pump in the factory usually limits the frequency adjustment range; in order to prevent the program from frequently issuing adjustment commands to the dosing pump frequency, which is not conducive to the stable operation of the dosing pump, it is necessary to introduce the concept of dosing pump frequency adjustment dead zone. The algorithm of the present invention effectively considers and avoids the occurrence of the above problems, and classifies and considers the pump frequency output adjustment situation under abnormal water outlet TP or abnormal dosing pump frequency and normal operation.

Claims

1. A PAC automatic dosing control method applied to sewage treatment process, characterized in that: The steps include: Step 1: Data input, the input data includes the inlet flow rate CF, the outlet flow rate OF, the inlet phosphorus concentration CTP, the outlet phosphorus concentration OTP, the flow rate of each dosing pump and the frequency of the dosing pump; Step 2: Calculate the drug processing capacity: The calculation formula for the drug processing capacity D_a is as follows: D_a=KTP÷TDF; In the above formula: KTP represents the total amount of phosphorus removal, D_a represents the agent treatment capacity, TDF is the total dosing flow, which is the sum of the dosing flow of each dosing pump; The calculation formula for the total phosphorus removal is as follows: TCTP=CF×CTP; TOTP=OF×OTP; KTP=TCTP-TOTP; In the above formula: KTP represents the total amount of phosphorus removal, CF represents the inlet flow rate, CTP represents the inlet phosphorus concentration, TCTP represents the total amount of inlet phosphorus, OF represents the outlet flow rate, OTP represents the outlet phosphorus concentration, and TOTP represents the total amount of outlet phosphorus; Step 3: Calculate the recommended total flow rate for dosing: The calculation formula for the recommended total dosing flow rate is as follows: su_TDF=(TCTP-OF×Q_OTP)÷D_a; In the above formula: su_TDF represents the recommended total dosing flow rate, Q_OTP is the expected effluent phosphorus concentration; Step 4: Calculate the pump frequency flow coefficient: The calculation formula of pump frequency flow coefficient is as follows: F_DF=F÷TDF; In the above formula: F_DF represents the pump frequency-to-flow coefficient, F is the sum of the frequencies of the dosing pumps, and is the sum of the frequencies of the individual dosing pumps; Step 5: Calculate the recommended frequency of the dosing pump: The calculation formula for the recommended value of the dosing pump frequency is as follows: su_F=su_TDF×F_DF÷n; In the above formula: su_F represents the recommended value of dosing pump frequency, su_TDF represents the recommended value of total dosing flow, F_DF represents the pump frequency to flow coefficient, and n is the number of dosing pumps put into use in daily mode; Step 6: Determine the pump frequency output, and continuously calculate the recommended frequency value of the dosing pump according to steps 2 to 5, and send the recommended frequency value of the dosing pump to the on-site PLC substation to control the frequency of the dosing pump; There are two situations for judging the pump frequency output: Situation 1: when the effluent phosphorus concentration is abnormal or the dosing pump frequency is abnormal, that is, the effluent phosphorus concentration does not belong to the safe range of the effluent phosphorus concentration or the dosing pump frequency does not belong to the adjustable range Q of the dosing pump frequency; Situation 2: when the cumulative time from the last command is T; In case 1: When the recommended value of the dosing pump frequency belongs to the adjustable range Q of the dosing pump frequency, the recommended value of the dosing pump frequency will be sent to the corresponding dosing pump according to the input of the dosing pump; when the recommended value of the dosing pump frequency is less than the minimum value Q of the adjustable range of the dosing pump frequency min , then according to the input of the dosing pump, Q min Send it to the corresponding dosing pump; when the recommended value of the dosing pump frequency is greater than the maximum value Q of the adjustable range of the dosing pump frequency max , then according to the input of the dosing pump, Q max Send it to the corresponding dosing pump; In case 2: when the absolute value of the difference between the recommended value of the dosing pump frequency and the dosing pump frequency is less than the dosing pump frequency adjustment dead zone C, the recommended value of the dosing pump frequency will not be issued; When the absolute value of the difference between the recommended value of the dosing pump frequency and the dosing pump frequency is greater than or equal to the dosing pump frequency adjustment dead zone C: When the recommended value of the dosing pump frequency belongs to the adjustable range of the dosing pump frequency interval Q, the recommended value of the dosing pump frequency will be sent to the corresponding dosing pump according to the input of the dosing pump; When the recommended value of the dosing pump frequency is less than the minimum value of the adjustable range of the dosing pump frequency interval Q min , then according to the input of the dosing pump, Q min Send it to the corresponding dosing pump; when the recommended value of the dosing pump frequency is greater than the maximum value Q of the adjustable range of the dosing pump frequency max , then the input of the dosing pump will be Q max Send it to the corresponding dosing pump.

2. A PAC automatic dosing system applied to sewage treatment process, characterized in that: It includes a data acquisition unit, which collects various data information on site and summarizes them to the on-site PLC substation and the host server; it includes an intelligent control calculation unit, which is a built-in unit of the host server, and the intelligent control calculation unit stores a dosing control program to implement the steps of a PAC automatic dosing control method applied to a sewage treatment process as claimed in claim 1; it includes a drug input unit, which includes a PAC dosing pump, and the host server sends the recommended frequency value of the dosing pump to the on-site PLC substation to control the frequency of the dosing pump.

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