The Design And Research Of Automatic Control System Of Daily Sewage Processing Unit On Ship

Along with most countries attaching much value to the ocean environment protection, pollution prevention on ship is more and more important. The purpose of this thesis is to design a reliable and wellappointed automatic control system of daily sewage processing unit on ship. The system can reduce the working intention of marine engineer and raise the efficiency of process by improving the automatic degree of control system and optimizing the processing.The thesis compares the technology of current daily sewage processing unit and analyses the advantage and disadvantage of every unit. Among these units, the technology of activated sludge is simpler, more efficient and doesn't cost a lot. Thus this technology is very fit for the actual condition of ship. On basis of the technology of activated sludge, the thesis researches how to accomplish the automatic control system of daily sewage processing unit on ship. The thesis discusses the control of the sludge of first deposit pool, DO of aeration pool, the refluent sludge, the waste sludge, the amount of medicament and the allocation of flow in detail. Because the aeration pool is very important in the system, the thesis discusses it at length including the control of air-blower and so on. The whole system is made up with upper computer, PLC, field instruments, sensors and execution units. The automatic control system of daily sewage processing unit on ship can be accomplished well by the powerful function in data acquisition, communication and control of PLC.In conclusion, the thesis confirms the system is feasible through introducing an automatic control system of sewage processing unit on land which is working well now.