RU2057723C1 - Method of automatic control of air tanks - Google Patents

Abstract

FIELD: environment protection. SUBSTANCE: the mean value of concentration of dissolved oxygen in the system of air tanks operating in parallel is determined, it is compared with the value of concentration of dissolved oxygen in each specific air tank, the difference between these values of concentrations is determined, and air distribution to each specific air tank is determined, depending on the sign of the difference of concentrations of dissolved oxygen. At a decrease of concentration of dissolved oxygen a control signal is generated to increase the air supply to the respective air tank, and at an increase - a control signal to decrease the air supply to the respective air tank. Operation of blowers is controlled with due account made for the mean value of concentration of dissolved oxygen and amount of sewage delivered for purification. EFFECT: facilitated procedure. 1 dwg

Description

 The invention relates to the protection of the environment, mainly water resources, in particular wastewater treatment, and can be used to automate biological treatment processes in the industry and municipal services of cities and towns.

 Numerous methods of automatic control are known, including changes in material and energy flows depending on the composition of the source, treated and purified water.

 Closest to the technical essence of the invention is a method of automatic control of aeration tanks, including measuring the flow rate of wastewater entering the group of parallel aeration tanks, the concentration of dissolved oxygen in each of the aeration tanks, followed by stabilization of the flow of purified water in each aeration tank, depending on the total flow of water and a change in the number of working blowers depending on the total flow of water and measuring the concentration of dissolved oxygen in the aeration tank Oh. This method really allows you to control the biological treatment process, however, it is not without a number of disadvantages, the main of which is the high cost of a unit of purified water due to poor quality control. This is due to the fact that when managing a group of parallel aeration tanks, there is no optimal distribution of air over aeration tanks and the necessary information to implement this distribution. The noted circumstance indicates that when implementing the known method, a large over-consumption of air is inevitable, leading to high additional costs, the irretrievably lost electricity consumed by the operation of the blowers. In other words, the use in the known control method as a control signal of the minimum concentration of dissolved oxygen in any aeration tank can neither practically nor theoretically minimize air consumption for the oxidation of organic contaminants in aeration tanks.

 The aim of the invention is to improve the quality of cleaning by optimal distribution of air between working aeration tanks and reduce its cost.

 Achieving this goal is ensured by the fact that they additionally determine the average value of the concentration of dissolved oxygen in the system of parallel aeration tanks, compare it with the value of the concentration of dissolved oxygen in each specific aeration tank, find the difference between these concentrations and, depending on the difference sign, change the number in proportion to its value air supplied to the appropriate aeration tank, and the operation of the blowers is inversely proportional depending on the value of the average concentration of dissolved oxygen and the amount of wastewater received for treatment.

 The drawing shows a block diagram illustrating the proposed method.

 The circuit includes a wastewater flow meter 1, wastewater flow controllers 2 in each aeration tank, wastewater dispensers 3 in aeration tanks, dissolved oxygen concentration meters 4 in each aeration tank, a computing device 5, a blower station 6, air flow meters 7 in each aeration tank, regulators 8 air flow in each aeration tank, actuators 9 air supply.

KPK_i= KPK₁+KPK₂+.+KPK_n (1) и определяется среднее значение концентрации растворенного кислорода в группе аэротенков KPK_ср=

(2) где n число работающих параллельно аэротенков;
KPK_i концентрация растворенного кислорода в i-том аэротенке.The proposed control method works as follows. According to the signal of the wastewater flow meter 1, supplied to the inputs of the regulators 2, the flow of dispensers 3 is determined, which provide the same aeration tanks loading. The same signal from the wastewater flow meter 1 is fed to the computing device 5, which also receives signals from the dissolved oxygen concentration meters 4 in each aeration tank. The signals from the dissolved oxygen concentration meters are summed up:

KPK _i = KPK ₁ + KPK ₂ +. + KPK _n (1) and the average concentration of dissolved oxygen in the aerotank group KPK _cf =

(2) where n is the number of parallel aeration tanks operating in parallel;
KPK _{i is the} concentration of dissolved oxygen in the i-th aeration tank.

KPK_тi-KPK

≥ ΔKPK (3)
Если условие (3) выполняется и при этом величина (КРК_тi КРК_ср) имеет отрицательный знак, то вырабатывается сигнал управления увеличить подачу воздуха в i-м аэротенке. Этот сигнал поступает на регулятор расхода воздуха 8 сравниваемого аэротенка, связанного с исполнительным механизмом 9 подачи воздуха в i-й аэротенк.Then, the value of the CRC _{cf is} compared with the value of the _{CRC ti} (the current value of the concentration of dissolved oxygen in the ith aerotank) and, based on the obtained difference, a control signal is generated

KPK _ti -KPK

≥ ΔKPK (3)
If condition (3) is fulfilled and at the same time the value ( _{KKK ti KKK av} ) has a negative sign, then a control signal is generated to increase the air supply in the ith aerotank. This signal is fed to the air flow regulator 8 of the compared aeration tank associated with the actuator 9 for supplying air to the i-th aeration tank.

If condition (3) is fulfilled, but the value (KRC _ti KRC _avg ) has a positive sign, then a control signal is generated to reduce the air supply in the ith aerotank, which also enters the regulator 8 of the compared aeration tank. After interrogating all dissolved oxygen concentration meters 4 and comparing their current value with the average, the average dissolved oxygen concentration will change by Δ KRC and the interrogation process will be repeated.

 Thus, the cleaning process is controlled by a computing device 5, which implements the above dependencies (1), (2), (3) according to the described algorithm. In addition, at the output of the computing signal is generated that controls the operation of the blower station 6.

 The supply of blowers is determined depending on the signal of the wastewater flow meter 1 with a correction based on the average value of the dissolved oxygen concentration meters 4. Therefore, the flow rates of the incoming wastewater and the pollution concentration are adjusted so that the amount of dissolved oxygen in the treated water is within acceptable limits.

5,15 мг/л
Результат сравнения величины средней концентрации растворенного кислорода с величинами концентрации растворенного кислорода в каждом из четырех аэротенков, а также знак полученной разности влияет на выработку сигнала управления увеличить или уменьшить подачу воздуха в соответствующий аэротенк по вышеприведенному алгоритму.For example, for a system of four parallel-connected aeration tanks, the concentration of dissolved oxygen in each of them is respectively: KRK ₁ 4 mg / l, KRK ₂ 4.6 mg / l, KRK ₃ 5.5 mg / l, KRK ₄ 6.5 mg / l, the average concentration at the output of the computing device will be equal
KPK _avg =

5.15 mg / l
The result of comparing the average concentration of dissolved oxygen with the values of the concentration of dissolved oxygen in each of the four aeration tanks, as well as the sign of the resulting difference, affects the generation of a control signal to increase or decrease the air supply to the corresponding aeration tank according to the above algorithm.

Claims (1)

 METHOD FOR AUTOMATIC AEROTENE CONTROL, including measuring the flow rate of wastewater entering a group of parallel aeration tanks and the concentration of dissolved oxygen in each aeration tank, followed by stabilization of the flow rate of waste water in each aeration tank depending on the flow rate of the waste water and the number of blowers working depending on waste water consumption and changes in the concentration of dissolved oxygen in each aeration tank, characterized in that it further determines the average the concentration of dissolved oxygen in a group of parallel aeration tanks, compare it with the concentration of dissolved oxygen in each aeration tank, find the difference between these concentrations and, depending on the sign of the difference, change the amount of air supplied to the corresponding aeration tank proportionally to its value, moreover, the operation of blowers is carried out inversely proportional to the average value of the concentration of dissolved oxygen and the flow rate water.

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