Working principle and operation instructions of tank type non negative pressure water supply equipment
The tank type non negative pressure water supply equipment is put into use. The water from the tap water pipeline enters the water supply tank, and the air inside the tank is discharged from the vacuum eliminator. After the water is filled, the vacuum eliminator automatically shuts off. When the pressure of the tap water network can meet the water requirements, the system will supply water directly to the water network through a bypass check valve; When the pressure of the tap water network cannot meet the water demand, the system pressure signal is fed back to the variable frequency controller through a remote pressure gauge. The water pump runs and automatically adjusts the speed and constant pressure water supply according to the amount of water used. If the running water pump reaches the power frequency speed, another water pump will start variable frequency operation. When the water pump is supplying water, if the water volume in the tap water network is greater than the flow rate of the water pump, the system will maintain normal water supply; During peak water usage, if the water volume in the tap water network is less than the flow rate of the water pump, the water in the supply tank can still be supplied normally as a supplementary water source. At this time, air enters the supply tank through a vacuum eliminator, and the vacuum inside the tank is destroyed, ensuring that the tap water network does not generate negative pressure. After the peak water usage, the system returns to normal water supply. When the water supply network is shut down, causing the liquid level in the water supply tank to continuously decrease, the liquid level detector will feedback the signal to the variable frequency controller, and the water pump will automatically stop to protect the water pump unit. The water supply tank can store and release energy, avoiding frequent starting of the water pump.
Overview of Tank type Non negative Pressure Water Supply Equipment
With the development and progress of socio-economic technology, the water quality standards of municipal water supply systems are gradually improving, and the water supply capacity is constantly increasing. In order to meet the requirements of social development, automatic water supply equipment will inevitably develop towards certain goals, which are high efficiency, energy saving, no water source pollution, low noise, easy operation, and reliable operation. The equipment fully utilizes the pressure and heat energy of the municipal water source itself, making up for the difference as much as possible, effectively and maximally exerting the energy-saving effect of variable frequency speed regulation.
Product characteristics of tank type non negative pressure water supply equipment
(1) Energy saving: The stacked water supply equipment in the pipeline network fully utilizes the pressure and heat energy inherent in the municipal water source, making up for the difference and effectively maximizing the energy-saving effect of variable frequency speed regulation.
(2) Clean and hygienic: It constitutes a continuous and enclosed pressurized water supply method, fully maintaining the national water quality and hygiene standards of municipal water sources, fundamentally avoiding the water quality standard reduction and various water source pollution problems caused by the pressurized system.
(3) Eliminating waste: The pipeline stacked water supply equipment not only eliminates high-level water tanks, but also completely eliminates ground (underground) water tank water tanks, completely eliminating water tank overflow and water source waste caused by regular cleaning.
(4) Low operating noise: When using the full frequency conversion adjustment scheme for the pipeline network pressure water supply equipment series products, they are mostly in low-noise operating conditions, especially at night.
(5) A fully enclosed water source tank with buffering and dynamic compensation functions has been designed, which is more practical and simplifies the control system compared to the so-called non negative pressure tank in the current market.
(6) The control system of this series of products fully summarizes the design and manufacturing experience of our company and domestic and foreign variable frequency water supply equipment. It adopts standardized and universal control system technology solutions, and can be replaced with any manufacturer's frequency converter, regulator, PLC and other components. Debugging and maintenance are particularly convenient, laying a good foundation for the lifelong after-sales service of the products, and will not cause after-sales service problems due to technological progress.
(7) The control system of this series of tank type non negative pressure water supply equipment has high intelligence, and the design fully considers the coordination and cooperation of machines, electricity, and instruments. It has detection and monitoring functions that can be achieved quickly but not quickly, as well as simple and convenient human-machine interaction functions. It has comprehensive fault protection functions and countermeasures. When the frequency converter fails to protect, it automatically operates in a degraded state (becoming a power frequency automatic water supply equipment). When the automatic system fails, it can also be manually operated as an emergency backup to win maintenance time.
(8) Various communication interfaces and protocols can be selected according to requirements, so as to connect various human-machine interfaces and monitoring computers, and can be connected to various control networks and communication networks, suitable for special and complex operation control and network monitoring requirements. We can develop supporting monitoring software for users.
Operating principle of tank type non negative pressure water supply equipment
The application of tank type non negative pressure water supply equipment is to use the municipal pipeline network as the water source to form a closed continuous relay pressure boosting water supply method. Its application is significantly different from the usual secondary pressure boosting water supply equipment through water tanks.
In order to reduce the impact of direct suction on municipal water supply, a pressurized water storage container should generally be connected in series on the inlet pipeline of the equipment. The water tank that mainly serves as a buffer (dynamic compensation) is called a buffer tank; A water tank that only serves as a backup water source when there is no water pressure in the municipal pipeline and has no dynamic buffering effect is called a water source tank. A large volume pressurized water tank is also a form of water source tank (usually constructed on-site using reinforced concrete).
The operating principles of the relay boosting equipment for the supporting buffer tank and the relay boosting equipment for the supporting water source tank are somewhat different, which will be explained separately below.
1. Equipment for supporting buffer tanks
Equipment Instructions
The non negative pressure and non suction pipe network stacked water supply equipment generally consists of a buffer tank, a water pump unit, a pressure tank control cabinet, and control instruments. The description of each part is as follows
a、 Buffer tank: It is a pressure tank connected to the inlet of the equipment, abbreviated as a buffer tank. During water supply operation, the volume inside the tank is partially compressed air. With the energy stored in compressed air, it has a good buffering and eliminating effect on various sudden impacts, and also has a certain dynamic compensation effect on municipal water supply
There are two different structures of buffer tanks. The diaphragm buffer tank uses natural rubber diaphragm material, which is more conducive to maintaining water quality standards due to complete sealing. The inner wall of ordinary steel buffer tanks is coated with anti-corrosion paint that meets hygiene standards, but it will come into contact with the outside air when refilling.
Buffer tanks can be used in series or in parallel (with the same inlet and outlet water pipeline as a branch connected to the municipal pipeline)
b、 Water pump unit: Choose our company's water pump with non overload characteristics, which can adapt to pressure changes in a large range of water sources without causing overload.
c、 Pressure tank: Its function is the same as that of the pressure tank in typical two-stage pressurized water supply equipment. The diaphragm type miniature pressure tank used in this series of standard products mainly utilizes its pressure holding function, which is conducive to the intelligent automatic energy-saving control of the equipment.
d、 Variable frequency control cabinet: A full frequency control system can be used, which means that all water pumps are driven by variable frequency speed regulation, or a partial frequency control system can be used (only one pump in the sample standard product is driven by variable frequency speed regulation).
e、 Bypass pipeline: If the municipal water supply can meet the water pressure requirements during normal times and only has insufficient pressure during peak water supply periods, a bypass pipeline can be installed to automatically switch between municipal pull-down water supply and pressurized water supply.
(1) When the municipal pipeline network is under high pressure, the equipment is in a shutdown state, and the municipal water source supplies water directly to the user pipeline network through the buffer tank and bypass pipeline.
(2) When the municipal pipeline network is under pressure, the equipment automatically starts, and on the basis of the original non water pressure, variable frequency speed regulation is used to increase the pressure (constant pressure) for water supply. Since the pressure is increased according to the principle of "adding as much as the difference", it meets the user's demand for constant pressure water supply in the full flow range while achieving efficient and energy-saving operation. During operation, the sealed buffer tank is equivalent to a section of pipeline, and fresh and hygienic water continuously flows through the water source tank without being contaminated by external factors.
(3) During the operation of the equipment, the buffer tank has a volume of compressed air (with the same pressure as the municipal water pressure), which stores a certain amount of pressure potential energy. With this energy storage, various impacts on the municipal water source can be greatly reduced, and it also has a dynamic peak shaving compensation effect on the municipal water supply. When the municipal service pressure drops from P2 to P1, the relationship between the maximum compensation water provided by the buffer tank and the total volume of the buffer tank is:
V #=(1-P1/P2) V Total=KV Total
V # - Compensation water volume provided by the water source tank during the period when the municipal pressure drops from P2 to P1 during the peak water supply period (m3)
P1- Minimum pressure during peak period of municipal water supply (absolute pressure)
P2- Pressure before peak period of municipal water supply (absolute pressure)
V total - total volume of water source tank (m3)
Example: During the peak period of water supply, if the pressure of the municipal water source drops from 20mH2O to mH2O, the compensation water amount given by the water source tank during this period is
V #=(1-15/30) V total=0.5V total (m3), accounting for 50% of the total volume. Obviously, this is a practical and effective dynamic compensation effect. If all users' boosting equipment has this compensation effect, it can have a certain peak shaving and valley filling effect on municipal water supply as a whole, and the service pressure of the pipeline network during peak hours will not drop too low.
(4) The buffer tank is equipped with control instruments, which can automatically shut down (prohibit operation) when the pressure of the municipal pipeline network is below the set lower limit, to prevent excessive pumping of municipal water sources and to prevent pumping operation.
Operation instructions for tank type non negative pressure water supply equipment
(1) When the municipal pipeline network is under high pressure, the equipment is in a shutdown state, and the municipal water source directly supplies water to the user pipeline network through the water source tank and bypass pipeline.
(2) When the municipal pipeline network is under pressure, the equipment automatically starts, and on the basis of the original water pressure, variable frequency speed regulation is used to increase the pressure (constant pressure) for water supply. Due to the principle of "increasing the pressure according to the difference", the constant pressure water supply needs of users are met within the full flow range, while achieving efficient and energy-saving operation. During operation, a sealed ocean tank is only equivalent to a section of pipeline, and fresh and hygienic tap water continuously flows through the water source tank (or pressurized water tank) without being contaminated by external factors.
(3) When the pressure of the municipal water source is too low and the inflow of tap water is less than the water supply of the equipment (outflow from the water source tank), the insufficient municipal water source is compensated by the storage capacity of the water source tank. The maximum compensation water provided by the water source tank is the same as the total volume of the water source tank, V compensation=V total.
During the compensation water supply period provided by the water source tank, vacuum suppression (automatic inlet and outlet valves) is used to automatically allow air to enter the tank, which can avoid negative suction effects on the municipal pipeline network (i.e. no negative pressure and no suction stroke), and ensure that the entire volume of the water source tank is effectively utilized.
(4) To further reduce the impact of direct suction on municipal water sources, a water source isolation valve and control instrument can be selected, so that the minimum pressure allowed for suction can be set arbitrarily. When the inlet pressure of the municipal water source drops to the minimum pressure allowed for suction, the water source isolation device will automatically start, and the equipment will switch to using a compensation tank as the water source for automatic water supply. You can also consider purchasing inexpensive throttling devices instead of isolation valves to limit the inflow of tap water, and compensate for the insufficient water supply by relying on water source tanks.
(5) If the municipal water source is shut down due to unforeseen circumstances and the water storage tank has been depleted, the equipment will automatically shut down (prohibit operation). Automatically resume operation after the water source returns to normal
Main functions of tank type non negative pressure water supply equipment
1. Fully automatic completion of the entire operation process of soft start, frequency conversion to power frequency operation, and stop for multiple water pump units.
2. According to changes in water usage, it becomes the start and stop of multiple pump units.
3. LED display function with pressure setting value and actual pressure value.
4. There is LED frequency indication, frequency conversion abnormal indication, and motor fault condition display.
5. Protection function: It has functions such as undervoltage protection, overvoltage protection, overload protection, short circuit protection, stall prevention, and burn prevention.
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