Transportation and flow characteristics of sludge

     In the process of treatment, disposal and utilization of sludge, sludge transportation is a problem that must be solved first. The transport mode of sludge mainly depends on the moisture content of sludge, and the utilization of sludge should be considered. Generally, there are pipeline transportation, automobile transportation and barge transportation. Experience shows that it is economical and hygienic to transport the same amount of sludge by pressure pipeline when the transportation distance is less than 10km. Generally, the solid content of sludge transported should be 5%. When the sludge is transported for a long distance, it should be considered to reduce the sludge volume through dehydration and drying process before transportation.

When the sludge is transported by pipeline, it is necessary to master the characteristics of sludge flow, mainly velocity and moisture content of sludge.

(1) Velocity of flow

     When the sludge flows in the pipeline, when the flow slows down to the laminar flow state, the sludge viscosity is large, the suspended solids are easy to settle in the pipeline, and the flow resistance of the sludge is greater than that of the water flow; when the flow velocity increases to turbulent flow, the viscosity of the sludge eliminates the vortex in the boundary layer of the pipeline, which reduces the roughness of the pipe wall, and the negative side of the sludge flow resistance is smaller than that of the water flow. Therefore, a larger flow rate should be adopted to make the sludge flow in the pipe in a turbulent state.

(2) Moisture content

      The lower the moisture content, the greater the viscosity of sludge, the higher the water content, the smaller the viscosity and resistance of sludge, and the closer the flow state to water. In the sewage (waste) water treatment plant, the gravity conveying sludge pipe generally adopts the gradient of 0.01 ~ 0.02; the pressure conveying of 5% of the total solid content is realized by means of the liquid level difference of sludge or centrifugal pump and pressure conveying pipe, and the diameter of the pressure pipe is not less than 150 mm. For liquid sludge with solid content up to 20%, the pump capacity is up to 300m3 / min and the head h is 64M. On the removal of sludge blockage in the pipe, for different types of sludge, different types of pumps are required. The pumps for conveying sludge include plunger pump, multi cavity screw pump, centrifugal pump and swirl pump. Diaphragm pump can be used to lift scum.

     The non clogging, low speed, low head centrifugal pump is used to pump the return activated sludge, because the sludge is thin and contains only fine solids. At the same time, the flocculation solid of the sludge can not be seriously sheared by the pump. Piston pump is more suitable for pumping sludge. It overcomes the high friction pressure drop in the discharge pipe, but the particle size of sludge should be reduced. The screw lift pump is used for variable capacity operation, and the effect is good. Since the sludge discharge is controlled by the liquid level at the screw inlet, the variable speed drive device is not required.

     Generally speaking, centrifugal pump and screw lift pump are used to pump a large amount of sludge with low solid content, and they are used in situations where accurate control of sludge flow is not required.In addition, there is a pneumatic lift pump, which is simple in structure and not easy to block, but difficult to throttle and control, and requires a lot of money.

     Doyen specializes in providing belt press equipment for the Southeast Asian market. Welcome to visit our workshop, according to the actual situation of your company, develop a more scientific dehydration program.Welcome to joyce@doyenchina.com or visit https://www.doyenchina.com.