◎Water supply plant and sewage treatment plant
Reflux sludge, primary sedimentation tank, secondary sedimentation tank, thickening tank, sludge dewatering and so on.
◎Coal washing plant, mining, paper making, electric power
Mineral slurry concentration, coal slurry concentration, gray slurry concentration, pulp concentration, etc..
Ultrasonic concentration meter in the slurry concentration measurement Introduction
Common concentration meter:
Ray concentration meter, ultrasonic concentration meter, photoelectricity type concentration meter, differential pressure method concentration meter, weighing method and so on. Types Principle Disadvantages Advantages Ray Concentrometer When a certain intensity of ray passes through the material to be measured, its intensity should be weakened, and the degree of weakening depends on the concentration in the measuring channel as well as the material to be measured, if the measuring channel has been set, the concentration of the material to be measured can be obtained by measuring the degree of attenuation of the rays by the material to be measured There are environmental and safety risks associated with the radiation source. High measurement accuracy, large range, low maintenance Ultrasonic slurry concentration meter Ultrasonic waves are absorbed and attenuated after passing through the object to be measured, and the degree of attenuation is related to the concentration of the object to be measured. Ultrasound will be affected by air bubbles, excessive air bubbles will affect the accuracy of the measurement results. No radiation, the best alternative to radiometric meters Photoelectric meter Light is absorbed and attenuated when it passes through the measured substance, and the degree of attenuation is related to the concentration of the measured substance Measurement range is small, and is affected by chromaticity. High precision, no pollution Differential pressure concentration meter Through a fixed distance pressure difference, the density of the mixture, through the known density of the measured object to calculate the concentration of the media density and water density must have a difference; in the concentration of small time can not be measured;
Pressure measurements are susceptible to flow and other impacts; only in the media and the solvent density is a large difference between the application of the method Weighing method Directly weighing, through the density of a known object to convert the concentration of the same; as above, the same as above, the same as above, the same as above, the same as above, the same as above, the same as above. Conversion of concentration Ditto; Ditto, discontinuous, high maintenance slurry concentration meter applications
Yangquan eight mine coal washing plant, Nanshan Steel, Bensteel, Anshan Steel, Rizhao Iron and Steel Group, Jinxi Steel Plant, Russian gold ore dressing, Laiwu Iron Works, Fujian tungsten mine, Anshan Dagushan Iron Ore Mine, Yellow Science and Technology Commission, and other industrial and mining sites have applications. According to different industrial and mining sites we will do corresponding improvements to the instrument and sensor, such as multi-point calibration to improve accuracy, sensor spraying wear-resistant materials to adapt to the abrasive occasions.
Ultrasonic concentration meter application case 1:
Sedimentation tank discharge automatic control system
Sedimentation tanks in municipal wastewater treatment plants are mainly used to remove sinkable solids in SS, and the removal efficiency can reach more than 90%. The primary sedimentation tank can be divided into flat-flow sedimentation tank, vertical-flow sedimentation tank and spoke-flow sedimentation tank in terms of its flow pattern and structural form. Generally, the mud scraper will scrape the mud into the hopper, and then use the sludge pump to discharge the mud from the hopper.
Discharge of mud is the most important and most difficult to control the operation of the sedimentation tank operation, there are continuous discharge and intermittent discharge of mud in two ways. Advection type primary sedimentation tank with traveling type mud scraper, can only be used intermittent sludge discharge, because in a sludge scraping cycle only when the sludge is scraped to the mud hopper later, can be discharged, otherwise discharged will be sewage. At this time, the sludge discharge cycle and scraping cycle must be the same, scraping and sludge discharge synergistic operation. How long each discharge time lasts depends on the amount of sludge, the capacity of the sludge pump and the concentration of sludge feed required by the thickener.
Both the sludge cleanly and thoroughly discharged, but also to get a high solids content, the operation is very difficult.
Small sewage treatment plants generally use manual control of mud pumps on and off, can only be operated by experience, the accuracy is very poor. Large sewage plants generally use automatic control, commonly used time program control, that is, timed to discharge mud, timed to stop the pump, but this way can not adapt to the changes in the amount of mud, may make the concentration of mud discharge is too low or not thoroughly discharged mud.
The more advanced control method is concentration control sludge discharge, that is, in the sedimentation tank or sludge discharge pipeline installed on the sludge concentration meter on-line monitoring of sludge concentration changes, by the controller according to the changes in sludge concentration control sludge pump on or off. This way can automatically adjust the sludge discharge time according to the change of sludge volume, neither reduce the sludge concentration, but also can discharge sludge thoroughly, not only saves power consumption, but also reduces the pressure of the subsequent treatment, can obviously improve the operation efficiency of the primary sedimentation tank.
This control mode is the joint control of time and concentration. According to the experience of the time set to start sludge discharging regularly, stop the pump by the sludge concentration meter installed in the sludge discharge pipeline control. After starting the sludge discharge, the sludge concentration in the sludge discharge pipe will gradually become smaller, and when the sludge concentration drops to the set value, the sludge pump will stop automatically.
This kind of control method is that both sludge discharge and pump stopping are controlled by the sludge concentration meter. When the sludge concentration monitored by the sludge concentration meter in the pool exceeds the set value, the sludge pump is controlled to start discharging sludge; when the concentration monitored by the sludge concentration meter installed on the discharging pipeline drops to the set value, the sludge pump is controlled to stop discharging sludge automatically.
Specific application cases of ultrasonic slurry concentration meter 2:
Inclined tube sedimentation tank automatic sludge discharge control
Inclined tube sedimentation tank is a special equipment for industrial wastewater treatment, and its mechanism is mainly based on the Boycott phenomenon, shallow precipitation theory and shallow sedimentation theory, etc., which has the advantages of high sedimentation efficiency, small floor space, unique arrangement (can be flexibly installed according to the characteristics of terrain), low investment and low operating costs. It has the superior characteristics of high sedimentation efficiency, small footprint, unique arrangement (flexible installation according to the terrain characteristics), low investment, low operation cost and long maintenance cycle. It can be widely used in metallurgy, papermaking, chemical industry, and domestic sewage and other fields of sedimentation treatment.
The inclined tube sedimentation tank is mainly composed of sewage entry pipe and valve, slurry discharge pipe and valve, emptying pipe and valve, clean water pipe, bracket, sedimentation tank and clean water collection tank. Due to the limited capacity of a single unit, generally by more than one tank to form a group or more groups of treatment units *** enjoy the inlet pipe and outlet water and sludge treatment unit.
Currently in the inclined tube sedimentation tank sludge discharge unit is mainly used in the following ways:
Manual sludge discharge: that is, the manual can be randomly operated according to need. The main advantage is flexible, but the number of tanks is more, it is very inconvenient to operate, have to have someone on duty at any time, sludge discharge is completely dependent on experience, randomness is greater. Unreasonable sludge discharge not only affects the index of water reuse, but also affects the subsequent sludge treatment process unit. In fact, each tank is operated in groups, and the water inlet, outlet and sludge discharge all need to be controlled in a linked manner. Purely manual control is already difficult to fully meet the normal production operation. Timed sludge discharge: According to the specific conditions of water intake concentration and water quantity, the necessary sludge discharge cycle and sludge discharge time are set through calculation (for example, the sludge discharge cycle is once every 6 hours, and the sludge discharge time is about 8-10 minutes each time). This kind of timed sludge discharge has been greatly improved compared with the manual sludge discharge, and it basically can satisfy the requirements of automatic operation in the case of little change in the quality of water and the quantity of water. But when the concentration of feed water or the amount of feed water has a big change, the defects of the timed sludge discharge itself will appear. Either in order to ensure that the effluent (reuse water) meets the standard, to the worst water quality and maximum water intake design sludge discharge cycle and sludge discharge time, so that in the concentration of water intake is small or small water will undoubtedly result in more rows or even empty rows, increase the cost of sludge treatment; either to the normal quality of water and water as a standard for the discharge of sludge, the quality of water becomes worse or water quality caused by a large number of substandard. In short, it can not flexibly adapt to the change of water quality and quantity. Concentration control sludge discharge: in the sludge discharge system to install ray concentration meter, it can real-time detection of the concentration of slurry in the tank changes that the slurry water content changes, PLC system according to the concentration of slurry control sludge valve opening and closing to realize the automatic sludge discharge. The advantages of this method are obvious. However, since this control method directly takes the sludge concentration as feedback, the accuracy and reliability of sludge concentration measurement will have higher requirements. Ray concentration measurement accuracy and reliability is also high, in mining measurement and other demanding occasions are widely used, but the ray there are safety hazards, more and more strict control, a lot of occasions are not necessary to avoid the application of ray. Ultrasonic sludge concentration meter as a good alternative for many occasions, inclined tube sedimentation tank discharge control is a good example. We carefully analyze the user's actual sludge discharge process requirements combined with the instrument's application experience to the user proposed timing + concentration of sludge discharge control program. Timing + concentration control: not only absorbed the advantages of timing control and concentration control (reliability and flexibility), but also effectively avoid their obvious shortcomings. The specific idea is: according to the experience to determine the sludge discharge cycle (which is the same as the timed sludge discharge) in each sludge discharge time control combined with concentration control, set a concentration threshold, when the concentration is lower than the value to stop discharging sludge, or stop discharging sludge when the sludge discharge time is up. In this way, even if the instrument maintenance will not affect the system work, enhance the reliability of the whole system, and realize the flexibility of the system to adapt to different water quality and flow. Ps: the use of timing + concentration control program has been in the steel mill wastewater reuse treatment has been a good application, the actual operation of the program proved practical and feasible, to achieve the design objectives.