CN214781051U - Dissolved oxygen control device for sewage treatment system - Google Patents
Dissolved oxygen control device for sewage treatment system Download PDFInfo
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- CN214781051U CN214781051U CN202120624947.5U CN202120624947U CN214781051U CN 214781051 U CN214781051 U CN 214781051U CN 202120624947 U CN202120624947 U CN 202120624947U CN 214781051 U CN214781051 U CN 214781051U
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
The utility model discloses a dissolved oxygen controlling means for sewage treatment system relates to sewage treatment technical field, include: the liquid flowmeter is arranged in the non-aeration tank; the air blower is respectively connected with the first aeration tank, the second aeration tank and the third aeration tank through a first pipeline, a second pipeline and a third pipeline, and a first regulating valve, a second regulating valve and a third regulating valve are respectively arranged on the first pipeline, the second pipeline and the third pipeline; the first gas flowmeter, the second gas flowmeter and the third gas flowmeter are respectively arranged on the first pipeline, the second pipeline and the third pipeline; the control unit is connected with the air blower, the second regulating valve, the third regulating valve, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter; the device can carry out timing accurate control to the dissolved oxygen of sewage treatment system aeration tank, can guarantee that sewage treatment process moves steadily high-efficiently.
Description
Technical Field
The utility model belongs to the technical field of sewage treatment, more specifically relates to a dissolved oxygen controlling means for sewage treatment system.
Background
A sewage treatment plant usually adopts a control system to realize the standard operation of a sewage nitrogen and phosphorus removal process system, wherein dissolved oxygen is an important index for the operation control of the sewage nitrogen and phosphorus removal process. The control system of the existing sewage treatment plant completely depends on the reliability of the monitoring instrument, the price of the existing online instrument is higher, and the maintenance and management are more complex, so that the investment cost and the daily maintenance cost for directly utilizing the online instrument to control the dissolved oxygen are obviously increased; moreover, once the dissolved oxygen meters in the control systems cannot be maintained in time, the dissolved oxygen control systems of the corresponding units cannot work normally, and the stability of other units is influenced; along with the increasingly strict requirements on the quality of the discharged water, the quality of the discharged water is required to be monitored and fed back in time in order to achieve the real-time standard reaching of the quality of the discharged water, and the popularization and application of the dissolved oxygen control system are greatly influenced due to the high investment and operation cost and the unstable system operation of the existing control system.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a dissolved oxygen controlling means for sewage treatment system to the not enough that exists among the prior art, the device can realize carrying out regularly accurate control to the dissolved oxygen of sewage treatment system aeration tank, can guarantee that sewage treatment process moves steadily high-efficiently.
In order to achieve the above object, the present invention provides a dissolved oxygen control device for a sewage treatment system, the sewage treatment system comprising a non-aeration tank, a first aeration tank, a second aeration tank, a third aeration tank and a secondary sedimentation tank which are sequentially arranged from front to back, the device comprising:
a liquid flow meter disposed in the non-aeration tank;
the air blower is respectively connected with the first aeration tank, the second aeration tank and the third aeration tank through a first pipeline, a second pipeline and a third pipeline, and a first regulating valve, a second regulating valve and a third regulating valve are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
a first gas flow meter, a second gas flow meter and a third gas flow meter respectively arranged on the first pipeline, the second pipeline and the third pipeline;
a control unit connected with the blower, the second regulating valve, the third regulating valve, the first gas flow meter, the second gas flow meter, and the third gas flow meter.
Optionally, an ammonia nitrogen monitor is arranged in the secondary sedimentation tank.
Optionally, the system further comprises a first dissolved oxygen instrument and a second dissolved oxygen instrument, wherein the first dissolved oxygen instrument and the second dissolved oxygen instrument are respectively arranged in the second aeration tank and the third aeration tank.
Optionally, the control unit includes a PLC, an upper computer, and a blower controller.
Optionally, the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flowmeter, the second gas flowmeter and the output end of the third gas flowmeter pass through signal transmission lines and are connected with the PLC, the PLC and the upper computer are connected, the upper computer pass through control transmission lines and the blower controller, the second regulating valve and the third regulating valve are connected, and the blower controller is connected with the blower.
Optionally, the first regulating valve is a manual air volume regulating valve, and the second regulating valve and the third regulating valve are electric air volume regulating valves.
Optionally, the opening degree adjusting ranges of the second adjusting valve and the third adjusting valve are 40% -90%.
The utility model provides a dissolved oxygen controlling means for sewage treatment system, its beneficial effect lies in:
1. the device can perform timing and accurate control on the dissolved oxygen in the aeration tank of the sewage treatment system, and can ensure that the sewage treatment process stably and efficiently operates;
2. the controller of the device can accurately calculate the required aeration amount of the three aeration tanks through the liquid flow meter, the three gas flow meters and a formula, and can correct the required aeration amount, so that the calculation accuracy is improved, and the control accuracy is further improved;
3. the device realizes the control of the dissolved oxygen of the aeration tank by adjusting the opening of the adjusting valve according to the difference value between the actual air supply amount measured by the three flowmeters and the required aeration amount, improves the reliability of the dissolved oxygen control, also enables the control method to mainly depend on a liquid flowmeter and an ammonia nitrogen monitor with higher reliability, has lower dependence degree on a dissolved oxygen instrument with lower reliability, and improves the reliability of the control device and the control method;
4. the device can also utilize the aperture of adjusting the governing valve to adjust the dissolved oxygen that realizes aeration tank according to the dissolved oxygen volume that the dissolved oxygen appearance measured in ammonia nitrogen content and the aeration tank in the secondary sedimentation pond and control, has further ensured the stability of dissolved oxygen in the aeration tank, improves control effect.
Other features and advantages of the present invention will be described in detail in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout the exemplary embodiments of the present invention.
Fig. 1 is a schematic structural diagram of a dissolved oxygen control device for a sewage treatment system according to an embodiment of the present invention.
Description of reference numerals:
1. a non-aeration tank; 2. a first aeration tank; 3. a second aeration tank; 4. a third aeration tank; 5. a secondary sedimentation tank; 6. a liquid flow meter; 7. a first dissolved oxygen meter; 8. a second dissolved oxygen meter; 9. an ammonia nitrogen monitor; 10. a signal transmission line; 11. a PLC; 12. an upper computer; 13. a control transmission line; 14. a blower controller; 15. a blower; 16. a first gas flow meter; 17. a first regulating valve; 18. a second gas flow meter; 19. a second regulating valve; 20. a third gas flow meter; 21. and a third regulating valve.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The utility model provides a dissolved oxygen controlling means for sewage treatment system, sewage treatment system include by preceding non-aeration tank, first aeration tank, second aeration tank, third aeration tank and the two heavy ponds that set gradually after to, its characterized in that, the device includes:
the liquid flowmeter is arranged in the non-aeration tank;
the air blower is respectively connected with the first aeration tank, the second aeration tank and the third aeration tank through a first pipeline, a second pipeline and a third pipeline, and a first regulating valve, a second regulating valve and a third regulating valve are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
the first gas flowmeter, the second gas flowmeter and the third gas flowmeter are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
and the control unit is connected with the air blower, the second regulating valve, the third regulating valve, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter.
Specifically, the liquid flow meter is used for measuring the sewage flow of the sewage treatment system, the blower can respectively supply air to the first aeration tank, the second aeration tank and the third aeration tank through the first pipeline, the second pipeline and the third pipeline, the first regulating valve, the second regulating valve and the third regulating valve respectively control the air supply flow in the first pipeline, the second pipeline and the third pipeline, and the first gas flow meter, the second gas flow meter and the third gas flow meter are respectively used for measuring the air supply flow in the first pipeline, the second pipeline and the third pipeline; the control unit can control the air blower, the second regulating valve and the third regulating valve according to parameters measured by the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flow meter, the second gas flow meter and the third gas flow meter through the following using method of the device, and further control the dissolved oxygen of the sewage treatment system.
The use method of the device comprises the following steps:
measuring the sewage flow by using a liquid flowmeter, and calculating the water quantity lag time according to the sewage flow within a set time;
respectively acquiring a second required aeration amount and a third required aeration amount of the second aeration tank and the third aeration tank within a set time length;
acquiring the total required aeration quantity of a sewage treatment system after a set time length and a water quantity lag time length;
acquiring a second actual air supply amount in the second aeration tank and a third actual air supply amount in the third aeration tank after the water amount lag time is passed every time the acquisition of the second required aeration amount and the third required aeration amount is completed;
and controlling the opening degrees of the second regulating valve and the third regulating valve according to the difference values of the second actual air supply quantity and the third actual air supply quantity and the second required aeration quantity and the third required aeration quantity respectively.
Specifically, the second and third gas flow meters can measure gas supply flow rates in the second and third pipelines respectively, and the second and third actual gas supply rates are collected once every time when the second and third pipelines finish acquiring the second and third required aeration rates and the water amount lag time is passed; the method finds the difference between the actual air supply quantity and the required air supply quantity by using the difference between the actual air supply quantity and the required air supply quantity, adjusts the opening degrees of the second adjusting valve and the third adjusting valve according to the positive and negative sum of the difference, further adjusts the air supply quantity and adjusts the dissolved oxygen quantity, not only can improve the accuracy and timeliness of control, but also can ensure that the control method mainly depends on a liquid flowmeter and a gas flowmeter with higher reliability, and improves the reliability of the control device and the control method.
Furthermore, the set time can be set according to the sewage flow, and the method adjusts the second regulating valve and the third regulating valve once after each set time and after the water quantity lag time, so as to realize the timing control of the dissolved oxygen; the total required aeration quantity is used as the basis for controlling the output power of the air blower by the air blower controller, so that the control of the air blower is facilitated, and the energy consumption of the air blower is reduced on the premise of meeting the air supply requirement.
Optionally, the formula for calculating the water quantity lag time according to the sewage flow is as follows:
wherein T1 is water quantity lag time, m is volume coefficient, n is number of primary sedimentation tanks, p is number of biological tanks, VCCIs the volume of the primary sedimentation tank, V is the volume of the biological tank, qFIs the average value of sewage flow within a set time length, VINFIs the flow coefficient, qRIs the external reflux amount, qrIs the internal reflux amount.
Specifically, the parameters can be obtained from the existing sewage treatment system, the specification of the existing sewage treatment system and the actual treatment capacity parameters.
Optionally, the obtaining the total required aeration amount of the sewage treatment system after the set time period and the water amount lag time period comprises:
acquiring a first required aeration rate in the first aeration tank, wherein the first required aeration rate is the value of a first gas flow meter after the second required aeration rate and the third required aeration rate are acquired and the water amount lag time elapses, and the first required aeration rate is G1;
the formulas for calculating the second required aeration rate in the second aeration tank and the third required aeration rate in the third aeration tank are as follows:
wherein SSF: influent concentration, SOF: dissolved oxygen concentration of influent water, SO,sat: saturated dissolved oxygen concentration, SS: concentration of aeration tank substrate, SO: concentration of dissolved oxygen, S, in aeration tankExpectation of: setting the dissolved oxygen concentration of the aeration tank, KOH: coefficient of oxygen saturation, KS: saturation factor of the substrate, YH: yield coefficient, XH: concentration of heterotrophic bacteria, X, in the aeration tankHF: concentration of heterotrophic bacteria in the influent water, bH: heterotrophic bacteria decay coefficient, fP: inert component qW: excess sludge discharge amount, a: oxygen diffusion coefficient of air at the time of maximum aeration amount, b: attenuation coefficient, μ in Monod modelH: maximum growth rate of heterotrophic bacteria; c is a correction coefficient;
when S isSF、SOF、SO,sat、SS、SO、SExpectation of、KOH、KS、YH、XH、XHF、bH、fP、qW、a、b、μHAnd when c is a parameter of the second aeration tank, q isAThe second required aeration amount;
when S isSF、SOF、SO,sat、SS、SO、SExpectation of、KOH、KS、YH、XH、XHF、bH、fP、qW、a、b、μHAnd when c is the parameter of the third aeration tank, q isAThe third required aeration amount;
the sum of the first required aeration amount, the second required aeration amount, and the third required aeration amount is taken as the total required aeration amount.
Specifically, the parameters can be obtained from the existing sewage treatment system, the specification of the existing sewage treatment system and the actual treatment capacity parameters; the required aeration amounts of the second aeration tank and the third aeration tank can be respectively calculated by using the formula.
Optionally, the calculating the second required aeration amount in the second aeration tank and the calculating the third required aeration amount in the third aeration tank further comprise correcting the second required aeration amount and the third required aeration amount, obtaining a second required aeration amount correction value and a third required aeration amount correction value, and taking the sum of the first required aeration amount, the second required aeration amount correction value and the third required aeration amount correction value as the total required aeration amount.
Specifically, the correction method comprises the following steps:
it is noted that the state variable is,
the controlled variable is qAIn combination with each other
Representing the dynamic relational expression in the aeration quantity calculation formula, the right-end term in the equation set can be obtained
The objective function in the optimization control is set as:
the method comprises the following steps of determining the DO concentration of a gas, determining the DO concentration of the gas, and determining the DO concentration of the gas, wherein T is set duration, the objective function comprises two integrals, the first term measures the magnitude of the deviation of the actual DO concentration from the expected value, the second term is gas supply flow, on one hand, the DO concentration is ensured to fluctuate only in the range near the expected value through minimizing the objective function, on the other hand, the aeration quantity can be reduced, and therefore the purpose of saving energy is achieved, and alpha belongs to R + as a weight value, and the weight value is used for adjusting the relative proportion of the first term and the second term in the objective function.
Alternatively, the controlling the opening degrees of the second and third adjusting valves according to the difference values of the second and third actual air supply amounts and the second and third required aeration amounts, respectively, includes:
acquiring a first difference value between the second actual air supply amount and the second required aeration amount and a second difference value between the third actual air supply amount and the third required aeration amount;
setting a first threshold value of the first difference value and a second threshold value of the second difference value;
comparing the first difference value with a first threshold value, comparing the second difference value with a second threshold value, and keeping the opening degree of the second regulating valve unchanged when the absolute value of the first difference value is within the range of the first threshold value;
when the absolute value of the first difference is not in the range of the first threshold value, adjusting the opening degree of the second adjusting valve until the absolute value of the first difference is in the range of the first threshold value;
when the absolute value of the second difference is within the range of the second threshold value, the opening degree of the third regulating valve is unchanged;
when the absolute value of the second difference is not within the range of the second threshold value, the opening degree of the third regulating valve is regulated until the absolute value of the second difference is within the range of the second threshold value.
Specifically, the second required aeration amount is defined as G2, the first difference is Δ G2, Δ G2 is defined as the second actual air supply amount-G2, the third required aeration amount is defined as G3, the second difference is Δ G3, Δ G3 is defined as the third actual air supply amount-G3, the first threshold is defined as the interval from-n% G2 to n% G2, if | Δ G2| < n% G2, the second adjustment valve opening is kept unchanged, and similarly, if | Δ G3| < n% G3, the third adjustment valve opening is kept unchanged; if the delta G2 is greater than n% G2, the opening degree of the second regulating valve is started to be reduced, the air supply quantity of the second aeration tank is regulated in real time, and the | delta G2| < n% G2; if the delta G2< -n% G2, starting to adjust the opening degree of the second adjusting valve, and adjusting the air supply quantity of the second aeration tank in real time to enable the | delta G2| to be less than n% G2; the dissolved oxygen control step for the third aeration tank is the same as the dissolved oxygen control step for the second aeration tank described above.
Furthermore, the control principle of the first regulating valve, the second regulating valve and the third regulating valve is that the second regulating valve is regulated first, the third regulating valve is regulated after the opening degree of the second regulating valve meets the requirement, and the opening degrees of the rest regulating valves are kept unchanged when any regulating valve is regulated; the opening degree of the first regulating valve is kept to be maximum; and the opening degrees of the second regulating valve and the third regulating valve are ensured to be 40-90% in the regulating process.
Optionally, an ammonia nitrogen monitor is arranged in the secondary sedimentation tank.
Specifically, the ammonia nitrogen monitor is used for measuring the ammonia nitrogen content of the sewage in the secondary sedimentation tank, and the ammonia nitrogen content feedback control is carried out on the sewage treatment system according to the ammonia nitrogen content, and the control method comprises the following steps:
measuring the ammonia nitrogen content of the sewage in the secondary sedimentation tank by using an ammonia nitrogen monitor;
setting an ammonia nitrogen content threshold;
comparing the ammonia nitrogen content with an ammonia nitrogen content threshold, correcting a second required aeration amount and a third required aeration amount when the ammonia nitrogen content is not in the ammonia nitrogen content threshold range, and controlling the opening degree of a second regulating valve and a third regulating valve according to the difference between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively;
and when the ammonia nitrogen content is in the ammonia nitrogen content threshold range, the opening degree of the second regulating valve and the opening degree of the third regulating valve are not regulated.
Specifically, the method compares the ammonia nitrogen content with the ammonia nitrogen content threshold value to realize DONH4Feedback controlThe control logic is as follows: and when the ammonia nitrogen content is not in the range of the ammonia nitrogen content threshold value, correcting the second required aeration amount and the third required aeration amount to change the first difference value and the second difference value, further repeatedly comparing the first difference value with the first threshold value, the second difference value with the second threshold value, and then adjusting the opening degrees of the second adjusting valve and the third adjusting valve.
In one example, the above step is DONH4Feedback control: firstly checking the effluent NH displayed by the ammonia nitrogen monitor4Value when NH4>n1mg/L, increase G2 and G3 by Δ G when NH4<n2mg/L, G2 and G3 are respectively reduced by delta G; otherwise, go directly to DO feedback step described below.
Optionally, when the ammonia nitrogen content is smaller than the minimum value of the ammonia nitrogen content threshold value, increasing the opening degree of a second regulating valve and a third regulating valve;
when the ammonia nitrogen oxygen content is larger than the maximum value of the ammonia nitrogen content threshold value, reducing the opening degree of the second regulating valve and the third regulating valve;
and when the ammonia nitrogen content is in the ammonia nitrogen content threshold range, the opening degree of the second regulating valve and the opening degree of the third regulating valve are not regulated.
Specifically, the control of the opening degrees of the second regulating valve and the third regulating valve can be realized according to the logic, so that the control of the dissolved oxygen is realized.
Optionally, the aeration device further comprises a first dissolved oxygen instrument and a second dissolved oxygen instrument, and the first dissolved oxygen instrument and the second dissolved oxygen instrument are respectively arranged in the second aeration tank and the third aeration tank.
Specifically, first dissolved oxygen appearance and second dissolved oxygen appearance are used for measuring first dissolved oxygen volume and second dissolved oxygen volume in second, third aeration tank respectively, carry out dissolved oxygen feedback control to sewage treatment system according to first dissolved oxygen volume and second dissolved oxygen volume, and this control method is:
respectively measuring a first dissolved oxygen amount and a second dissolved oxygen amount in the second aeration tank and the third aeration tank by using a first dissolved oxygen meter and a second dissolved oxygen meter;
setting a first dissolved oxygen standard value of a second aeration tank and a second dissolved oxygen standard value of a third aeration tank;
acquiring a third difference value between the first dissolved oxygen amount and the standard value of the first dissolved oxygen amount and a fourth difference value between the second dissolved oxygen amount and the standard value of the second dissolved oxygen amount;
setting a third threshold value of the third difference value and a fourth threshold value of the fourth difference value;
comparing the third difference value and the fourth difference value with a third threshold value and a fourth threshold value respectively, correcting a second required aeration quantity when the third difference value is not in the range of the third threshold value, and controlling the opening degree of a second regulating valve according to the difference value of a second actual air supply quantity and the second required aeration quantity;
when the fourth difference is not within the range of the fourth threshold value, correcting the third required aeration quantity, and controlling the opening degree of the third regulating valve again according to the difference between the third actual air supply quantity and the third required aeration quantity;
when the third difference value is within the range of the third threshold value, the opening degree of the second regulating valve is not regulated;
when the fourth difference is within the range of the fourth threshold, the opening degree of the third regulating valve is not regulated.
Specifically, the method compares the third difference value and the fourth difference value with the third threshold value and the fourth threshold value respectively to realize the DO feedback control, and the control logic is as follows: when the third difference is not within the range of the third threshold, correcting the second required aeration amount to change the first difference, further repeatedly comparing the first difference with the first threshold, and then adjusting the opening of the second adjusting valve; and when the fourth difference is not in the range of the fourth threshold, correcting the third required aeration amount to change the second difference, repeatedly comparing the second difference with the second threshold, and then adjusting the opening of the third adjusting valve.
In one example, the above steps are DO feedback control: firstly, comparing the first dissolved oxygen amount and the second dissolved oxygen amount measured by a first dissolved oxygen meter with a first dissolved oxygen amount standard value and a second dissolved oxygen amount standard value set in a controller respectively, defining a third difference value as delta DO2, wherein delta DO2 is the first dissolved oxygen amount-first dissolved oxygen amount standard value, and when delta DO2>d1At mg/L, G2 is reduced by a certain amount, when Δ DO2<-d1mg/L, increase G2 by a certain amountOtherwise, maintaining G2 unchanged; then, regulating a third regulating valve by the same method to regulate G3; and finally, repeating the step of comparing the first difference value with the first threshold value and the second difference value with the second threshold value respectively, and repeating the steps in such a way, so as to control the dissolved oxygen of the sewage treatment system in real time and improve the sewage treatment effect.
Optionally, when the absolute value of the third difference is within the range of the third threshold, the opening degree of the second regulating valve is unchanged, and the second required aeration amount is kept unchanged;
when the absolute value of the third difference is not within the range of the third threshold, adjusting the opening of the second adjusting valve so as to increase or decrease the second required aeration amount until the absolute value of the third difference is within the range of the third threshold;
when the absolute value of the fourth difference is within the range of the fourth threshold value, the opening degree of the third regulating valve is unchanged, and the third required aeration amount is kept unchanged;
when the absolute value of the fourth difference is not within the range of the fourth threshold, the opening of the third regulating valve is regulated, so that the third required aeration amount is increased or decreased until the absolute value of the fourth difference is within the range of the fourth threshold.
Specifically, the control of the opening degrees of the second regulating valve and the third regulating valve can be realized according to the logic, so that the control of the dissolved oxygen is realized.
Optionally, the control unit comprises a PLC, an upper computer and a blower controller.
Specifically, the change of the air demand of the three aeration tanks and the change of the opening of the three regulating valves cause the change of the pressure of the pipeline and the back pressure of the blower, and the blower controller can make corresponding adjustment.
Optionally, the output ends of the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flow meter, the second gas flow meter and the third gas flow meter are connected with the PLC through signal transmission lines, the PLC is connected with the upper computer, the upper computer is connected with the blower controller, the second regulating valve and the third regulating valve through control transmission lines, and the blower controller is connected with the blower.
In other examples, the control unit may also implement the transmission of signals and the transmission of control instructions in a communication manner through the communication module.
Optionally, the first regulating valve is a manual air volume regulating valve, and the second regulating valve and the third regulating valve are electric air volume regulating valves.
Specifically, the opening degree of the first regulating valve is regulated to be maximum in use.
Optionally, the opening degree adjusting ranges of the second adjusting valve and the third adjusting valve are 40% -90%.
Specifically, the opening adjusting ranges of the second adjusting valve and the third adjusting valve are set, so that the normal and safe operation of each aeration tank is ensured, and a certain adjustable space is kept.
Examples
As shown in fig. 1, the utility model provides a dissolved oxygen controlling means for sewage treatment system, sewage treatment system include by preceding non-aeration tank 1, first aeration tank 2, second aeration tank 3, third aeration tank 4 and the heavy pond 5 of two that sets gradually after to, its characterized in that, the device includes:
a liquid flow meter 6 arranged in the non-aeration tank 1;
the air blower 15 is respectively connected with the first aeration tank 2, the second aeration tank 3 and the third aeration tank 4 through a first pipeline, a second pipeline and a third pipeline, and a first regulating valve 17, a second regulating valve 19 and a third regulating valve 21 are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
a first gas flow meter 16, a second gas flow meter 18 and a third gas flow meter 20, respectively arranged on the first pipeline, the second pipeline and the third pipeline;
and a control unit connected with the blower 15, the second regulating valve 19, the third regulating valve 21, the first gas flow meter 16, the second gas flow meter 18 and the third gas flow meter 20.
In this embodiment, an ammonia nitrogen monitor 9 is arranged in the secondary sedimentation tank 5.
In the embodiment, a first dissolved oxygen instrument 7 and a second dissolved oxygen instrument 8 are further included, and the first dissolved oxygen instrument 7 and the second dissolved oxygen instrument 8 are respectively arranged in the second aeration tank 3 and the third aeration tank 4.
In this embodiment, the control unit includes a PLC11, an upper computer 12, and a blower controller 14.
In this embodiment, the output ends of the first dissolved oxygen meter 7, the second dissolved oxygen meter 8, the ammonia nitrogen monitor 9, the first gas flow meter 16, the second gas flow meter 18 and the third gas flow meter 20 are connected with a PLC11 through a signal transmission line 10, a PLC11 is connected with an upper computer 12, the upper computer 12 is connected with an air blower controller 14, a second regulating valve 19 and a third regulating valve 21 through a control transmission line 13, and the air blower controller 14 is connected with an air blower 15.
In the present embodiment, the first regulating valve 17 is a manual air amount regulating valve, and the second regulating valve 19 and the third regulating valve 21 are electric air amount regulating valves.
In the present embodiment, the opening degree adjustment ranges of the second and third adjusting valves 19 and 21 are 40% to 90%.
The use method of the device comprises the following steps:
measuring the sewage flow by using the liquid flowmeter 6, and calculating the water quantity lag time according to the sewage flow within a set time;
respectively acquiring a second required aeration amount and a third required aeration amount of the second aeration tank 3 and the third aeration tank 4 within a set time length;
acquiring the total required aeration quantity of a sewage treatment system after a set time length and a water quantity lag time length;
acquiring a second actual air supply amount in the second aeration tank 3 and a third actual air supply amount in the third aeration tank 4 every time the acquisition of the second required aeration amount and the third required aeration amount is completed and after a water amount lag time elapses;
the opening degrees of the second and third adjusting valves 19 and 21 are controlled according to the difference between the second and third actual air supply amounts and the second and third required aeration amounts, respectively.
In this embodiment, the formula for calculating the water amount delay time according to the sewage flow is as follows:
wherein T1 is water quantity lag time, m is volume coefficient, n is number of primary sedimentation tanks, p is number of biological tanks, VCCIs the volume of the primary sedimentation tank, V is the volume of the biological tank, qFIs the average value of sewage flow within a set time length, VINFIs the flow coefficient, qRIs the external reflux amount, qrIs the internal reflux amount.
In the present embodiment, it is preferred that,
obtaining a total required aeration rate of the sewage treatment system after a set time duration and a water quantity lag time duration comprises:
acquiring a first required aeration rate in the first aeration tank 3, wherein the first required aeration rate is the value of a first gas flow meter after the second required aeration rate and the third required aeration rate are acquired and the water amount lag time elapses, and the first required aeration rate is G1;
the formulas for calculating the second required aeration amount in the second aeration tank 3 and the third required aeration amount in the third aeration tank 4 are as follows:
wherein SSF: influent concentration, SOF: dissolved oxygen concentration of influent water, SO,sat: saturated dissolved oxygen concentration, SS: concentration of aeration tank substrate, SO: concentration of dissolved oxygen, S, in aeration tankExpectation of: setting the dissolved oxygen concentration of the aeration tank, KOH: coefficient of oxygen saturation, KS: saturation factor of the substrate, YH: yield coefficient, XH: concentration of heterotrophic bacteria, X, in the aeration tankHF: heterotrophic bacteria for water intakeConcentration bH: heterotrophic bacteria decay coefficient, fP: inert component qW: excess sludge discharge amount, a: oxygen diffusion coefficient of air at the time of maximum aeration amount, b: attenuation coefficient, μ in Monod modelH: maximum growth rate of heterotrophic bacteria; c is a correction coefficient;
when S isSF、SOF、SO,sat、SS、SO、SExpectation of、KOH、KS、YH、XH、XHF、bH、fP、qW、a、b、μHAnd c is a parameter of the second aeration tank 3, q isAThe second required aeration amount;
when S isSF、SOF、SO,sat、SS、SO、SExpectation of、KOH、KS、YH、XH、XHF、bH、fP、qW、a、b、μHAnd c is the parameter of the third aeration tank 4, q isAThe third required aeration amount;
the sum of the first required aeration amount, the second required aeration amount, and the third required aeration amount is taken as the total required aeration amount.
In this embodiment, the calculating the second required aeration amount in the second aeration tank 3 and the calculating the third required aeration amount in the third aeration tank 4 further includes correcting the second required aeration amount and the third required aeration amount, obtaining a second required aeration amount correction value and a third required aeration amount correction value, and taking the sum of the first required aeration amount, the second required aeration amount correction value and the third required aeration amount correction value as the total required aeration amount.
In the present embodiment, controlling the opening degrees of the second and third adjusting valves 19 and 21 according to the difference values of the second and third actual air supply amounts and the second and third required aeration amounts, respectively, includes:
acquiring a first difference value between the second actual air supply amount and the second required aeration amount and a second difference value between the third actual air supply amount and the third required aeration amount;
setting a first threshold value of the first difference value and a second threshold value of the second difference value;
comparing the first difference with a first threshold value, comparing the second difference with a second threshold value, and when the absolute value of the first difference is within the range of the first threshold value, the opening degree of the second regulating valve 19 is not changed;
when the absolute value of the first difference is not within the range of the first threshold value, the opening degree of the second regulating valve 19 is adjusted until the absolute value of the first difference is within the range of the first threshold value;
when the absolute value of the second difference is within the range of the second threshold value, the opening degree of the third regulating valve 21 is unchanged;
when the absolute value of the second difference is not within the range of the second threshold value, the opening degree of the third regulating valve 21 is adjusted until the absolute value of the second difference is within the range of the second threshold value.
In this embodiment, the method further includes:
measuring the ammonia nitrogen content of the sewage in the secondary sedimentation tank 5 by using an ammonia nitrogen monitor 9;
setting an ammonia nitrogen content threshold;
comparing the ammonia nitrogen content with an ammonia nitrogen content threshold, correcting a second required aeration amount and a third required aeration amount when the ammonia nitrogen content is not in the ammonia nitrogen content threshold range, and controlling the opening degrees of a second adjusting valve 19 and a third adjusting valve 21 according to the difference between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively;
and when the ammonia nitrogen content is in the ammonia nitrogen content threshold range, the opening degree of the second regulating valve 19 and the opening degree of the third regulating valve 21 are not regulated.
In this embodiment, the method further includes:
measuring a first dissolved oxygen amount and a second dissolved oxygen amount in the second aeration tank 3 and the third aeration tank 4 by using a first dissolved oxygen meter 7 and a second dissolved oxygen meter 8 respectively;
setting a first dissolved oxygen standard value of the second aeration tank 3 and a second dissolved oxygen standard value of the third aeration tank 4;
acquiring a third difference value between the first dissolved oxygen amount and the standard value of the first dissolved oxygen amount and a fourth difference value between the second dissolved oxygen amount and the standard value of the second dissolved oxygen amount;
setting a third threshold value of the third difference value and a fourth threshold value of the fourth difference value;
comparing the third difference and the fourth difference with a third threshold and a fourth threshold, respectively, correcting a second required aeration amount when the third difference is not within the range of the third threshold, and controlling the opening of the second regulating valve 19 again according to the difference between the second actual air supply amount and the second required aeration amount;
when the fourth difference is not within the range of the fourth threshold, correcting the third required aeration amount, and controlling the opening degree of the third adjusting valve 21 again according to the difference between the third actual air supply amount and the third required aeration amount;
when the third difference is within the range of the third threshold value, the opening degree of the second regulating valve 19 is not regulated;
when the fourth difference is within the range of the fourth threshold value, the opening degree of the third regulating valve 21 is not regulated.
To sum up, the utility model provides a dissolved oxygen controlling means and method for sewage treatment system when using, the aperture control range who sets for second governing valve 19 and third governing valve 21 in the controller is 40% -90%, and the change threshold value of first dissolved oxygen appearance 7 is 0.5mg/L, the change threshold value of second dissolved oxygen appearance 8 is 0.12mg/L, the change threshold value of second gas flowmeter 18 is 300m3The third gas flow meter 20 has a variation threshold of 200m3/s。
Collecting sewage flow once every 5 minutes by using a liquid flowmeter 6, and taking the average value of the sewage flow within 1 hour of a set time as qFCalculating a required water amount lag time period T1 according to a formula, and calculating a second required aeration amount C1 and a third required aeration amount C2 of the second aeration tank 3 and the third aeration tank 4 in 1 hour by using the formula; and then C1 and C2 are corrected to obtain a second required aeration correction value G2 and a third required aeration correction value G3, the value of the first gas flowmeter after the set time length and the water quantity lag time length T1 is taken as a first required aeration G1, and the total required aeration G is G1+ G2+ G3.
The control unit transmits the calculated total required aeration amount to the blower controller 14, and the blower controller 14 controls the blower 15 to operate; after the water amount delay time period T1 is obtained, first, defining a first difference Δ G2 as a second actual air supply amount-G2, a second difference Δ G3 as a third actual air supply amount-G3, a first threshold value being an interval from-3% G2 to 3% G2, a second threshold value being ± 3% G3, if | Δ G2| < 3% G2, keeping the opening degree of the second regulating valve 19 unchanged, and similarly, if | Δ G3| < 3% G3, keeping the opening degree of the third regulating valve 21 unchanged; if Δ G2 is greater than 3% G2, the opening degree of the second regulating valve 19 is adjusted to be small, and the air supply amount of the second aeration tank 3 is adjusted in real time so that | Δ G2| < 3% G2; if the delta G2< -3% G2, the opening degree of the second regulating valve 19 is started to be increased, and the air supply quantity of the second aeration tank 3 is regulated in real time, so that the | delta G2| < 3% G2; the method for regulating the dissolved oxygen in the third aeration tank 4 is the same as the method for regulating the dissolved oxygen in the second aeration tank 3; after the control step is finished, the following step of controlling the ammonia nitrogen content feedback is carried out.
Controlling the ammonia nitrogen content feedback: firstly, measuring the discharged water NH by using an ammonia nitrogen monitor 94Content of NH4Content (wt.)>1mg/L, increase G2 and G3 by 800m3H, when NH4Content (wt.)<At 0.1mg/L, G2 and G3 were reduced by 800m, respectively3H; the opening degrees of the second regulating valve 19 and the third regulating valve 21 are regulated again according to the comparison between the first difference value and the first threshold value and the comparison between the second difference value and the second threshold value; otherwise, directly entering the following dissolved oxygen feedback control link.
Dissolved oxygen feedback control: the opening degree of the second regulating valve 19 is first controlled, the third difference value in the second aeration tank 3 is defined as Δ DO2, Δ DO2 is the first dissolved oxygen amount-the first dissolved oxygen amount standard value, the third threshold value is defined as the interval from-1 mg/L to 1mg/L, and when Δ DO2 is>At 1mg/L, G2 was reduced by 500m3The opening degree of the second regulating valve 19 is regulated again according to the comparison between the third difference value and the third threshold value; when Δ DO2<Increase G2 by 500m at-1 mg/L3The opening degree of the second regulating valve 19 is regulated again according to the comparison between the third difference value and the third threshold value; otherwise, keeping G2 unchanged; the opening degree of the third regulating valve 21 is controlled to define a fourth difference Δ DO3 in the third aeration tank 4, where Δ DO3 is the second dissolutionOxygen-second dissolved oxygen standard value, defining fourth threshold value as the interval of-1 mg/L to 1mg/L when delta DO3>At 1mg/L, G3 was reduced by 500m3The opening degree of the third regulating valve 21 is regulated again according to the comparison between the fourth difference value and the fourth threshold value; when Δ DO3<Increase G3 by 500m at-1 mg/L3The opening degree of the third regulating valve 21 is regulated again according to the comparison between the fourth difference value and the fourth threshold value; otherwise, G3 is maintained.
In this embodiment, the control principle of the regulating valve is: the opening degree of the first regulating valve 17 is regulated to the maximum; the second regulating valve 19 is regulated first, and the third regulating valve 21 is regulated after the requirements are met, so that the opening degrees of the rest regulating valves are kept unchanged no matter which electric regulating valve is in operation.
In addition, the change of the air demand of the three aeration tanks and the change of the opening degree of the three regulating valves cause the pressure of the air pipeline and the back pressure of the blower 15 to change, and the blower controller 14 can make corresponding adjustment.
After the embodiment is tried, the dissolved oxygen control effect is obvious, the aeration energy consumption is reduced, and the stable standard-reaching rate of the effluent quality is improved.
While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (7)
1. A dissolved oxygen controlling means for sewage treatment system, sewage treatment system include by preceding to the non-aeration tank that sets gradually after to, first aeration tank, second aeration tank, third aeration tank and two sink the pond, its characterized in that, the device includes:
a liquid flow meter disposed in the non-aeration tank;
the air blower is respectively connected with the first aeration tank, the second aeration tank and the third aeration tank through a first pipeline, a second pipeline and a third pipeline, and a first regulating valve, a second regulating valve and a third regulating valve are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
a first gas flow meter, a second gas flow meter and a third gas flow meter respectively arranged on the first pipeline, the second pipeline and the third pipeline;
a control unit connected with the blower, the second regulating valve, the third regulating valve, the first gas flow meter, the second gas flow meter, and the third gas flow meter.
2. The dissolved oxygen control device for a wastewater treatment system according to claim 1, wherein an ammonia nitrogen monitor is disposed in the secondary sedimentation tank.
3. The dissolved oxygen control apparatus for a wastewater treatment system according to claim 2, further comprising a first dissolved oxygen meter and a second dissolved oxygen meter, the first dissolved oxygen meter and the second dissolved oxygen meter being disposed in the second aeration tank and the third aeration tank, respectively.
4. The dissolved oxygen control device for a wastewater treatment system according to claim 3, wherein the control unit comprises a PLC, an upper computer and a blower controller.
5. The dissolved oxygen control device of claim 4, wherein the output ends of the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flow meter, the second gas flow meter and the third gas flow meter are connected to the PLC through signal transmission lines, the PLC is connected to the upper computer, the upper computer is connected to the blower controller, the second regulating valve and the third regulating valve through control transmission lines, and the blower controller is connected to the blower.
6. The dissolved oxygen control device for a wastewater treatment system according to claim 1, wherein the first regulating valve is a manual air volume regulating valve, and the second regulating valve and the third regulating valve are electric air volume regulating valves.
7. The dissolved oxygen control device for a sewage treatment system according to claim 1, wherein the opening degree adjustment range of the second adjusting valve and the third adjusting valve is 40% to 90%.
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