EIRV suction dredger for secondary radial-flow sedimentation tanks

One of the main elements of the suction dredger is a rotary bridge, which is a three-dimensional truss. The truss rods have a curved profile shape. Such a constructive solution provided the bridge simultaneously with low sail and high strength.

The profile material is a deformable aluminum alloy AMg3M or stainless steel AISI 304 (optionally AISI 316). The truss bridge made of the aluminum deformable alloy AMg3M, which is characterized by high strength and corrosion resistance, is assembled with rivets of 10 mm in diameter made of the same aluminum alloy - this allowed providing such a bridge with high strength with guaranteed corrosion resistance in comparison with the welded aluminum structure, and as a result, an extended service life. A stainless steel frame is assembled by welding with the subsequent etching of welded seams, however, this results in a harder and more expensive bridge.

The flooring of the bridge is slotted, with an anti-slip surface, assembled from original unified elements made of modern polymeric material resistant to ultraviolet radiation and low temperatures. This ensures "dry" surface of the flooring in any weather conditions and improves its maintainability.

The rotary bridge rests with its peripheral part on the drive cart, and with the central part through the swing capstan – on the central support.

The central support is installed in a level with the bottom of the sedimentation tank above the supply channel. For this purpose, the delivery package includes a reducing flange, which is welded directly to the metal structures of the supply channel, and then the central support is fixed thereto by means of bolted connections. This design allows installation in standard sedimentation tanks, without modifying its load-bearing building structures. The material of the central support is stainless steel.

A two-wheel drive cart with direct drive from the gear motor to the front wheel is shown in Figure 1. The speed of the gear motor is regulated by a frequency converter. The choice of the front wheel of the cart as a drive is determined by the vector of loads that arise during the operation of the sludge exhauster due to its design features. A snowplow unit is installed on the cart and consists of a snow blower and a rotating brush.

The wheels of the cart are equipped with solid tires. The load-bearing structure of the cart is made of stainless steel.

Figure 1. EIRV suction dredger cart

A swig device is a knuckle joint connected to a large-diameter bearing for load-lifting mechanisms. The upper part of the knuckle joint is fixed to the bridge, and the lower base surface of the bearing is attached to the capstan.

The capstan and the knuckle joint are made of stainless steel.

The sludge receivers, each with its sludge pipe and sludge manifold, are suspended on the bridge using the brackets. The sludge receivers are equipped with an irregular bottom compensator in the form of an elastic skirt. Each sludge pipe that connects the sludge manifold and the sludge tank has its own telescopic flow controller. 

Sludge manifolds, sludge pipes and a sludge tank are made of stainless steel. The compensators of sludge receivers are made of fiber-reinforced rubber. The upper cylinder of the controller is made of a NPVC pipe.

The sludge settled to the tank bottom enters the sludge tank under the influence of hydrostatic pressure through the sludge manifolds and sludge pipes. The flow of sludge from each sludge receiver is regulated by changing the level difference between the water table in the sedimentation tank and the end face of the upper cylinder of the controller.