一、原理
旋流沉砂系統(tǒng)采用強制渦流原理達到砂粒沉降的目的。原水進入平直的進水渠后成直線流動，將進水的紊動減至最低，進水渠的末端為一個斜面，沿池底部周邊切線方向進入池中，使之產(chǎn)生附壁效應(yīng)，從而使原已沉降在渠底的砂粒沿著斜坡流向平底而被捕集。另外，在進水渠的末端有一個入水導(dǎo)流板，其位置可以使進入沉砂池的水流和沉砂池內(nèi)的原有水流在該導(dǎo)流板的斜表面上交匯，并將水流下折，使之沿沉砂池周邊流動。在沉砂池中心處裝有一軸向螺旋槳，用來保證池內(nèi)所有水流的適當(dāng)轉(zhuǎn)動。螺旋槳、入水導(dǎo)流板和進水水流結(jié)合在一起，就會產(chǎn)生環(huán)流流態(tài)。(水流沿沉砂池周邊流動，與此同時，沿平底轉(zhuǎn)向中心，經(jīng)葉輪向上，到頂部，再折回到池壁，向下到池底。這是一種螺旋環(huán)流流態(tài))。在環(huán)流流態(tài)的作用下，離心力的作用使得砂粒****限度地與平底碰撞，并被水流捕集，而砂粒一旦在平底上被捕集到，就會藉環(huán)流流態(tài)所產(chǎn)生的底部速度被推向中央，落入砂斗。平面池底是保證環(huán)流流態(tài)達到****除砂效率的因素，因為坡形底面將會減少環(huán)流流態(tài)的強度，降低砂粒的捕集效率，增加水流所捕集和儲存的砂粒中有機物的含量。當(dāng)砂粒沿平底被推向沉砂池中心時，旋轉(zhuǎn)葉輪將加速水流流動，使得較輕的有機物被提起并返回至沉砂池的出水中去。然后砂粒移向池心，通過螺旋槳驅(qū)動軸和鋼蓋板之間的環(huán)形孔口落入底部集砂斗。砂粒從螺旋槳下面通過時，螺旋槳產(chǎn)生的向上水流，將把夾在砂粒之間的有機物帶出，完成這一分離過程的砂粒才可以落入集砂斗中。當(dāng)集砂斗中所儲存有的砂粒足夠多時，砂粒被池項安裝的真空啟動泵抽出，并送至脫水裝置。一般每隔四小時從集砂斗自動排砂一次。
旋流除砂系統(tǒng)采用360度新型直線式設(shè)計，使得進水渠和出水渠呈360度，形成自然流線。該系統(tǒng)結(jié)構(gòu)簡單，易于安裝，且能有效地提高除砂效率。
綜上所述，旋流除砂系統(tǒng)有這樣幾個特點：
①軸向螺旋槳可以將進水和池內(nèi)水流帶向池心，然后向上，形成環(huán)流流態(tài)，并將砂粒慢慢水平地推向環(huán)形砂斗口，而附在砂粒上的有機物則在平運動過程中脫離砂粒，重新回到廢水中，并隨水流上升，流向排水渠，這大大減少了沉砂中所含有機物質(zhì)及異味的出現(xiàn)。
②沉砂提升泵間歇地將砂斗中的沉砂提升至砂水分離器，該泵采用真空啟動，其隱藏葉片式葉輪采用含鎳硬化處理的鑄鐵，可抵受砂粒在高速運行下可能產(chǎn)生的撞擊和磨損，并容許較大的物體通過。該系統(tǒng)可提供比一般的壓縮空氣提升系統(tǒng)更高的揚程，且節(jié)省了配套的壓縮空氣系統(tǒng)，其獨特的垂直式無堵塞設(shè)計令其平穩(wěn)無阻運作，避免一般水平式安裝可能產(chǎn)生的管道阻塞。
二、除砂裝置
沉入池底的砂石，由氣提除砂泵提升至砂水分離器。本公司研制開發(fā)了配套旋流曝氣沉砂池的氣提除砂泵，安裝和操作十分簡單，在開泵前先用空氣沖動貯砂斗中的砂石，使之松動，具有提升高，不易磨損，故障率低等優(yōu)點。
三、 技術(shù)參數(shù)
Swirling grit chamber
Principle
The swirling grit settling system adopts the principle of forced eddy current to achieve the purpose of sand settling. The raw water flows in a straight line after entering the flat inlet channels, minimizing the flow of the inlet turbulence. The end of the channel is an inclined plane, and the raw water enters the pool along the tangential direction of the bottom of the pool, causing wall attachment effect. Sand deposited at the bottom of the channel flows down the slope to the flat bottom and is trapped. In addition, there is an inlet guide plate at the end of the inlet channel. The water guide plate can make the water flow into the sand sink and the original water flow in the sand sink converge on the inclined surface of the guide plate and fold the water flow down to make it flow along the periphery of the sand sink. An axial propeller is installed at the center of the sink to ensure the proper rotation of all water flows in the sink. When the propeller, the water inlet baffle and the influent water flow are combined, a circulation flow pattern is produced. (The water flows along the periphery of the grit chamber. At the same time, it turns to the center along the flat bottom, through the impeller up, to the top, and then back to the pool wall, down to the bottom of the pool. This is a spiral circulation flow state). Under the action of the circulating flow state, the centrifugal force causes the sand to collide with the flat bottom to the maximum extent and is captured by the water flow. Once the sand is trapped at the bottom, it is pushed to the center by the bottom velocity generated by the circulation flow and falls into the sand hopper. The flat bottom of the pool is an important factor to ensure the maximum sand removal efficiency of the circulation pattern. Because the sloped bottom surface will reduce the intensity of the circulation flow, reduce the collection efficiency of the sand, and increase the content of organic matter in the sand collected and stored by the water flow. When the sand is pushed along the flat bottom towards the center of the grit chamber, the rotating impeller will accelerate the flow of water, causing the lighter organic matter to be lifted back to the effluent of the grit chamber. The sand then moves to the center of the tank and falls into the bottom sand hopper through the annular orifice between the propeller drive shaft and the steel cover plate. When the sand passes under the propeller, the upward flow generated by the propeller will bring out the organic matter sandwiched between the sand particles. The sand that completes this separation process can fall into the sand collecting hopper. When there are enough sand grains stored in the sand trap, the sand is pumped out by the vacuum start pump installed in the tank and sent to the dewatering device. Generally, sand is automatically discharged from the sand collecting hopper every four hours.
A 360° new straight line design is adopted in the swirling grit settling system, which makes the inlet and outlet channels 360°, forming a natural flow line. The system is simple in structure, easy to install and can effectively improve the efficiency of sand removal.
In summary, the cyclone sand removal system has the following characteristics:
The axial propeller can bring the water inlet and the water in the sink to the center of the sink, and then upward, forming a circulating flow regime. The sand grains are slowly pushed horizontally towards the annular sand hopper, and the organic matter attached to the sand grains is detached from the sand during the flat movement. Organic matter returns to the wastewater and rises with the flow to the drain, which greatly reduces the appearance of organic matter and odors in the sediment.
Sand in sand hopper is intermittently lifted to sand water separator by sand lifting pump. The pump is vacuum started, and its hidden blade impeller is made of cast iron with nickel hardening treatment, which can withstand the impact and wear that may be caused by sand particles at high speed, and allow larger objects to pass through. The system provides a higher lift than a typical compressed air lift system and saves the associated compressed air system. Its unique vertical, non-blocking design allows for smooth and unobstructed operation, avoiding possible pipe blockages in normal horizontal installations.
Sand removal device
The gravel that sinks into the bottom of the sink is lifted to the sand water separator by a gas lift and sand removal pump. Our company developed the air lift sand removal pump to support the use of swirl aeration sand sink. Its installation and operation is very simple. Before starting the pump, first use the air to impinge the sand in the sand storage hopper to make it loose. It has the advantages of high lifting, low wear and low failure rate.
Technical Parameters
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