General transformation gravity-free valve filter gravity-free valve filter with no large valves, positive head filtration, washing automation, low cost and ease of operation management, etc., which have been in the rail or water in small and medium towns wide range of applications. But the existence of gravity-free valve filter following questions: water system complexity, high construction requirements; water gas process easy clip, affecting the normal filtration and backwash; using single quartz sand filter, filter water production is low, can not water supply to meet the increasing demands. Shangrao Railway East Gate of the water supply water supply expansion project is the size of the original supply 12 000m3 / d expansion to 20 000m3 / d, which adds 320m3 / h of gravity-free valve filter 1. On the national standard figure 240m3 / h of gravity-free valve filter technological transformation after transformation, gravity-free valve filter water production increased to 320m3 / h, more successful solution to the above problem aspects. Figure valveless construction works construction and transformation after transformation after 1. Work filtration: The muddy water flowing into the water after a water mains distribution box 22, by two water distribution weir into drains into the shaft 3, after the energy dissipation of energy dissipation plate 4, evenly distributed in the filter layer 5 By supporting layer 6, 7 small resistance into the bottom of the water distribution system of water distribution space 8. Filtered water from the bottom of the water distribution space through the communication area 9 rose to flush tank 10. When the tank water level reaches the top of the weir 11 drains, overflows into the canal, and finally into the clear pool. After transformation, the gravity-free valve filter structure a water distribution weir water mains 2 3 4 shaft into drains energy dissipation plate 5 supporting layer filter layer 6 7 8 little resistance to water distribution system of water distribution space 10 9 COMPONENTS flush tank 11 21 22 seal bucket drains out water distribution box 12 siphon tube 13 auxiliary exhaust pipe 14 declined siphon siphon tube riser pipe 15 16 17 backwash drain siphon bucket regulator 18 19 20 siphon tube umbrella cover when backwash The work: filter operation, the filter layer resistance is increased, the siphon tube 14 rising water level gradually increased accordingly. When the water level reaches the auxiliary tube 12 siphon mouth of the water from the drop tube, and the exhaust pipe 13 through the siphon will continue to fall away air tube 15, so that a vacuum is formed in the siphon. When the siphon tube in the water rises over the top and siphon siphon tube drop of water in the rising phase exchange, two shares of water mingled, dropped out of the siphon tube mouth to siphon away all remnants of the air, forming a continuous siphon flow. At this time, water in the tank bottom-right filter backwash. During rinsing, the water level inside the tank is gradually decreased. When the water level drops to siphon 18:00 bucket, siphon tube 19 small bucket of water sucking. Nozzle to atmosphere, siphon, flushing end, filtered restarted. 2 transformation Points and Analysis (1) changes in muddy water way, cancel the original valveless filter influent U-trap and water links, increasing the shaft into the drains 3. Shaft into the drains in the internal connection pool filter influent distribution box and umbrella cover. Filter influent distribution box in the muddy water drains directly into the shaft into the cone cover inside the body. The water supply in the original 160m3 / h of gravity-free valve filter is constructed according to the national standard map, filter the water process gas into a folder, a portion on the Plaza and through the pool drain siphon outlet end, the part of the enter and accumulate in the filter cap and compressed under the umbrella. In the filter stage filtration, compressed gas will intermittently swell and siphon the water out of the top of the outer tank, affecting the normal filtration; the backwash stage, the compressed gas will not drain siphon siphon completely, resulting in a continuous backwash filter. These two phenomena have occurred in the original gravity-free valve filter operation, affecting the normal production of water supply. Measures currently taken to address this phenomenon are: U-shaped water trap set on the inlet or at the place setting gas-water separator. The former (national standards adopted in the figure) is more convenient, but not complete solutions, which require additional equipment. In order to ensure the water system does not produce air entrainment run phenomenon, consider the following aspects: ① prevent air filter folder run. Raw water system into the water flow rate in the larger (specification of the design flow rate of 0.5 ~ 0.7m / s), air is easily separated from the water; after the transformation of water into the canal system in the shaft velocity is small (design flow rate 0.1m / s or so), the flow of air entrainment effect weakened. ② exclude accumulate in mushroom cap below the compressed gas. In the initial filtration, gas and water systems siphon water into the process gas to accumulate in the folder umbrella roof below, due to the speed of the shaft into the ditch in the water less easily separated after the gas is compressed from the shaft into the canals. (2) changes in water distribution box. It has been reported [1]: Standard figure valveless major causes of air entrainment is assigned to run the water in the tank with filter inlet and outlet weir twice caused by poor water fall, when muddy water into the filter inlet When the water pipes, the nozzle and the formation of a "drop of water funnel" shaped seal, the seal inside the air into the intake pipe and hinder separated from the inner tube out of the air discharge. After transformation valveless water system, due to the small shaft into the canal water flow rate, pipe saliva seal weakened, so authors believe that only when the water distribution tank designed to meet the hydraulic conditions. (3) use single homogeneous layer of quartz sand, quartz sand particle layer is 0.8 ~ 1.0mm, thickness of 1 100mm. According to the design specification, design expansion to take 30% of the filter layer, backwashing strength to take 15L / (s.m2), designed to take the filtration rate 13m / h (in order to ensure safety, design filtration rate is low, the actual operation by author think filtration rate can also increase some). Supporting the same standard grading and thickness of the layer. (4) the rise in the siphon tube installed seal bucket mouth 21. Its main role is to: ① to increase security after the height of the filter layer between the mouth and the siphon up tube expansion. ② prevent backwash process running sand. ③ easy to filter debugging and running, to prevent the loss of the debugging process media. 3 Run the water supply situation in Shangrao Railway Eastgate take confidence river water. Raw water turbidity between 10 ~ 700NTU, water circulation clarifier effluent turbidity 8NTU below, valveless filter effluent turbidity 3NTU following after the transformation. During operation, after the transformation of non-valve filter with the original water supply valveless comparison shows: modified filter after running stable, has never been run phenomenon of air entrainment, duty cycle than the original valveless Filter relatively extended. 4 Conclusion The renovation project design is completed in June 1995, the following year, according to the design requirements of all project successfully completed and put into operation in December 1998 by the Nanchang Railway Bureau acceptance. After transformation, no valve filter, a single pool of water production from 240m3 / h up to 320m3 / h, invested 150,000 yuan, more than the construction of a 320m3 / h of the pond to save investment of 500 million yuan. So far, the valveless filter has stable operation for nearly three years, fully meet the design requirements. Gravity-free valve filter (a) non-valve filter main features: non-valve filter is a no valve, run entirely by the hydraulic automatic control filter. It is divided into two kinds of gravity and pressure, gravity and more generally supporting the use of clarifiers, pressure does not exceed 150 degrees for the use of raw water turbidity for small, decentralized nature of the water supply project, but the same principle work principle of its work is the same, the plane circular or square shape but the line; (b) non-valve filter structure: valveless filter consists of five main parts, namely the flush tank top, the middle filter chamber, the bottom of the chamber and the water catchment system and flushing siphon devices. (C) non-valve filter working process: running, runoff from the inlet into the filter, the filter layer filtration, water flows into the upper part of the connecting pipe from the wash tank, the tank is full, the inflow from the outlet pipe clean water tank . With the filtering operation, the filter layer after intercepting resistance increases, the water level rises siphon tube rising, when the water level reaches the nozzle assisted siphon tube, a sharp drop of water from that tube, through continuous pumping under the , the air in the tube removed, generating a negative pressure within the siphon, so that siphon tube rising and falling water level in the tube are quickly rise, they formed a confluent communication siphon form automatic backwash. Thus, when the flush tank water level gradually decreased, the current drops below the mouth siphon tube, air enters the siphon, siphon action will be destroyed, that is the end of the washing process, so complex and filter the water, start the cycle to run a new cycle . Business Line: 18839788973