一、原理

旋流沉砂系统采用强制涡流原理达到砂粒沉降的目的。原水进入平直的进水渠后成直线流动，将进水的紊动减至最低，进水渠的末端为一个斜面，沿池底部周边切线方向进入池中，使之产生附壁效应，从而使原已沉降在渠底的砂粒沿着斜坡流向平底而被捕集。另外，在进水渠的末端有一个入水导流板，其位置可以使进入沉砂池的水流和沉砂池内的原有水流在该导流板的斜表面上交汇，并将水流下折，使之沿沉砂池周边流动。在沉砂池中心处装有一轴向螺旋桨，用来保证池内所有水流的适当转动。螺旋桨、入水导流板和进水水流结合在一起，就会产生环流流态。(水流沿沉砂池周边流动，与此同时，沿平底转向中心，经叶轮向上，到顶部，再折回到池壁，向下到池底。这是一种螺旋环流流态)。在环流流态的作用下，离心力的作用使得砂粒最大限度地与平底碰撞，并被水流捕集，而砂粒一旦在平底上被捕集到，就会藉环流流态所产生的底部速度被推向中央，落入砂斗。平面池底是保证环流流态达到最大除砂效率的因素，因为坡形底面将会减少环流流态的强度，降低砂粒的捕集效率，增加水流所捕集和储存的砂粒中有机物的含量。当砂粒沿平底被推向沉砂池中心时，旋转叶轮将加速水流流动，使得较轻的有机物被提起并返回至沉砂池的出水中去。然后砂粒移向池心，通过螺旋桨驱动轴和钢盖板之间的环形孔口落入底部集砂斗。砂粒从螺旋桨下面通过时，螺旋桨产生的向上水流，将把夹在砂粒之间的有机物带出，完成这一分离过程的砂粒才可以落入集砂斗中。当集砂斗中所储存有的砂粒足够多时，砂粒被池项安装的真空启动泵抽出，并送至脱水装置。一般每隔四小时从集砂斗自动排砂一次。
旋流除砂系统采用360度新型直线式设计，使得进水渠和出水渠呈360度，形成自然流线。该系统结构简单，易于安装，且能有效地提高除砂效率。
综上所述，旋流除砂系统有这样几个特点：
①轴向螺旋桨可以将进水和池内水流带向池心，然后向上，形成环流流态，并将砂粒慢慢水平地推向环形砂斗口，而附在砂粒上的有机物则在平运动过程中脱离砂粒，重新回到废水中，并随水流上升，流向排水渠，这大大减少了沉砂中所含有机物质及异味的出现。
②沉砂提升泵间歇地将砂斗中的沉砂提升至砂水分离器，该泵采用真空启动，其隐藏叶片式叶轮采用含镍硬化处理的铸铁，可抵受砂粒在高速运行下可能产生的撞击和磨损，并容许较大的物体通过。该系统可提供比一般的压缩空气提升系统更高的扬程，且节省了配套的压缩空气系统，其独特的垂直式无堵塞设计令其平稳无阻运作，避免一般水平式安装可能产生的管道阻塞。

二、除砂装置

沉入池底的砂石，由气提除砂泵提升至砂水分离器。本公司研制开发了配套旋流曝气沉砂池的气提除砂泵，安装和操作十分简单，在开泵前先用空气冲动贮砂斗中的砂石，使之松动，具有提升高，不易磨损，故障率低等优点。

三、 技术参数

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