Flowmeter sewage treatment

 Flowmeter more used in urban water supply aqueducts; thermal power plant water diversion and drainage, sewage treatment and discharge canal inflows; industrial and mining industries as well as water discharge water conservancy and agricultural irrigation channels. Domestic application data to estimate accounting for 1.6% of the overall data flow meter. Flowmeter is open to non-full tubular channels measuring the natural flow of free surface flow meter. Non-full state water pipe called open channel flow, open channel flow measurement called flow flowmeter. Flowmeter except round, there are a variety of shapes U-shaped, trapezoidal, rectangular and so on. Flowmeter with a Parshall flume and weir structure structure two kinds of slots can be selected according to the site to different situations. If the downstream water flow, spacious venue, you can choose Parshall slot structure, otherwise you can use a weir structure. Also with a non-full pipe measurement structure, downstream water level changes will not affect the measurement results. Typically used in flow in the range of 0.5 ~ 20000t / h. Meter in the structure generally consists of two parts, the flowmeter and flow meter converter. Typically, the sensor and converter are two separate elements, the sensor installed in the monitoring process feelings flow signal; converter will flow sent by the sensor signal is amplified and converted into a standard electrical signals for display, recording, calculating and adjusting control. Some also converts meter and sensor mounted on - from the composition - integrated flowmeter may display and remote display and control. Flowmeter mainly by measuring tube assembly, magnetic system, electrodes and interference adjustment mechanism parts. In order to make the sensor work stably and reliably, accurately feel the flow signal, the sensor should meet the following requirements: ① to provide a sufficiently large, and the flow rate is proportional to the potential of the signal; ② interference signals can be suppressed to a minimum signal to noise ratio big enough; ③ can adapt to harsh environmental conditions, reliable work. System control principle of the system 3 parts by a groove (weir), ultrasonic flow sensors and controllers. The ultrasonic sensor is not in contact with water, to keep the sensor from corrosion, but the water floating debris may affect the measured authenticity. Xx as the master controller chip, the complete field data sampling, data processing operations, its serial communication enables remote data transmission and monitoring functions. System block diagram shown in Figure 1. When water flows through the flow channel is formed naturally, the relationship between the flow rate Q and flow tank upstream water level H is: Q = KHn formula: K, n is the flow coefficient, for different specifications of grooves or weirs have different values, is a liquid level height, m. Ultrasonic level sensors under control of the DSP, ultrasonic transmitting and receiving ultrasonic waves by the propagation time to calculate the distance between the sensor and the liquid surface:? H = C T / 2 where: C is an ultrasonic propagation medium in the air speed, m / s, if the sensor to zero level weir flow trough distance hmax, the liquid height H = hmax- h. Units measuring instrument system controller design, the higher sampling accuracy, faster sampling speed, powerful data processing energy is the main chip select the first condition, under normal circumstances because the sewage flow meters are installed outdoors, consider testing and maintenance needs, the controller should have a remote data transfer capabilities, integrated various factors, selecting a data signal processor DSP as the main chip. A master chip TMS320LF2407A sewage in open channel flow meter system, the main advantage TMS320LF2407A high-speed A / D interface and communication interface, you can simplify the hardware design of the system, its operation speed and 3.3V power supply can meet the low-power mode require measuring instruments. 2 analog to digital converter ADC and digital filtering A / D module with built-in sample / hold (S / H), contains two separate select up to eight channels of analog conversion sequencer (SEQ1 and SEQ2), these two sorter can be cascaded into - one can select up to 16 channels of conversion sequencer (SEQ), as shown in Figure 2. Under the given sort, four sorting controller determines the order in which the conversion of analog channels, multiple trigger sources can start A / D conversion, the system A / D sampling is triggered by a timer 1 (EVA) to software, timing control period is 0.125ms, so every 0.125ms sampling time, the A / D interrupt service routine, the memory is stored in register 16 results (RESULT0-RESULT15) sampling results into memory. The system selected type of acid and alkali UTG21-DP-type ultrasonic flowmeter, the meter can be used to continuously monitor open channel flow and cumulative flow of sewage, can be used as non-contact level gauge to use for irrigation, hydropower , environmental protection and other industrial and agricultural open channel flow measurement conditions. It is 4 ~ 20mA output signal is connected to the DSP in Figure 3 to 4 ~ 20mA current signal is converted to 0 ~ 3.3V voltage signal to the DSP sampling conversion circuit. In the fixed-point DSP chip, using fixed-point numerical computation, whose operands generally use integers to represent. Water sampling frequency of 8kHz, each water sample 16-bit integer stored in a file, a low-pass filter cut-off frequency of 800Hz, the filter using finite impulse response (FIR) filter of 19:00. FIR filtering formula is: Let and x (n) is an analog signal 12 quantized value, that is | x (n) | ≤211, the | y (n) | ≤211; according to the sampling frequency and the cutoff frequency, and the filter order to determine the filter coefficients are as follows: static int h [19] = {399, -296, -945, -1555, -1503, -285,2112,5061,7503,8450,7503,5061,2112, -285, -1503, -1555, -945, -296,399}; combining the characteristics of DSP data processing, the use of digital low-pass filter on the sampled signal is processed by high-frequency sampling filter out interference detection signal detection and measurement of system with good results. DSP instruction cycle is 25ns, making it possible to quickly calculate the flow. Control procedures per ultrasonic sensors detect a second level, the calculated flow 1s and further accumulate too flow, daily flow, monthly traffic flow and total cumulative flow, to the host computer by the serial port. 3 Serial Communication Design in order to achieve real-time monitoring system of sewage flow meter, will be transferred to the operating parameters in real time on the LCD display, but also can easily through the keyboard inverter system parameters were modified online. To make the system more intelligent, play the advantages of the computer control, using RS-485 serial communication bus between multiple subsystems and PC, TMS320LF2407A SCI module serial receiver and transmitter are double-buffered, each own separate enable and interrupt flag, through a serial port MAX3082 [2] and an RS-485.485 and RS-232 level converter to communicate with the host computer. RS-485 interface chip is suitable for half-duplex communication. Its ability to balance the drive [3] and the differential receiver [4], with a common mode interference suppression [5] can be used in harsh environments, the maximum communication distance up to 1200m. It has sent enable and receive enable control, when enabled invalid, sending and receiving the output of the high-impedance state. When using the MAX3082 constitute a communication system, the maximum communication rate 0.125Mb / s, the transmission line can be linked up to 128 transceivers. In the PC communication interface, the system uses the Newton -7520 as RS-485 and RS-232 level converter, its interface is a standard RS-485 and RS-232 bus interface. It has 300 ~ 115200b / s adaptive baud rate, while the interior of the RS-232 side plus a 3000V DC isolation. As a result of the non-contact measurement, to avoid corrosion sensors measured media, particularly suitable for measuring water flow. Controller with DSP digital information processing technology, set signal detection, signal conversion, display output, data transmission, remote monitoring and other functions into one, applicable to different slots (weir) and sensors with versatility. www.ziyi188.com/ProductsList_1.html www.517cifanbanyeweiji.com