PC based SCADA system and additional safety measures for small desalination plants

In this work the structure and the installation of a flexible and low cost SCADA system is presented. An ordinary PC with the appropriate interface and software operates the system. The system was installed to an old desalination plant in parallel with the existing old type conventional automation system, which is using relays, timers, etc. The automation system allows remote control and supervision of the plant at reasonable low cost. On the other hand, the system can be used for additional safety measures for the RO plant. The analysis of the data which are collected could be used for the prediction of possible breakdowns of the RO plant. The design and installation of the automation system, which includes the software and hardware, is simple and easily accessible. The system’s architecture and logic are presented in this paper in detail. The hardware which has been used is the Adam 4000 modules and the software is the VisiDaq 3.1. The operation of the system is simple and user-friendly and can be altered with very little knowledge in programming. The installation of the system has been proved quite useful in preventive maintenance, taking into account the peculiarity of this particular reverse osmosis (RO) plant. The system has reduced the labor cost, and has increased the labor productivity of the operation due to the remote supervision of the process.

A flexible and low cost SCADA system for RO desalination plants is presented in this work. The system is easily programmable according to the customer needs, it can supervise different Fig. 7. Control diagram and measurements for the RO plant and seawater pumping station. 2.3 2.3 2.3 2.3 2.3 2.3 2.4 1.6 2.4 2.3 2.3 2.2 2.2 2.3 2.3 2.3 2.3 2.3 28.7 27.8 27.8 28.3 29.1 30.3 30.5 29.8 31.1 32.4 32.7 32.9 33.3 33.1 33.3 32.7 31.8 Sat Sep 01 05:50:00 01 Sat Sep 01 06:50:00 01 Sat Sep 01 07:50:00 01 Sat Sep 01 08:50:00 01 Sat Sep 01 09:50:00 01 Sat Sep 01 10:50:00 01 Sat Sep 01 11:48:17 01 Sat Sep 01 11:58:54 01 Sat Sep 01 12:22:12 01 Sat Sep 01 13:22:12 01 Sat Sep 01 14:22:12 01 Sat Sep 01 15:22:12 01 Sat Sep 01 16:22:12 01 Sat Sep 01 17:22:12 01 Sat Sep 01 18:22:12 01 Sat Sep 01 18:35:11 01 Sat Sep 01 19:35:11 01 Sat Sep 01 20:35:11 01 43.6 43.2 43.7 44.1 44.8 46.1 54.1 45.8 46.9 47.6 47.6 46.3 43.9 Sea temp., HP motor Low °C temp, pressure, °C bar Date/Time Table 2 Performance data of the RO plant, Unit 1 64.7. 64.5 64.4 64.3 64.3 64.3 64.5 4.4 64.4 64.2 64.2 64.3 64.3 64.4 64.4 64.3 64.5 64.4 High pressure, bar 0.6 0.6 0.6 0.6 0.5 0.6 0.9 0.0 0.9 0.6 0.6 0.6 0.6 .0.6 0.6 0.6 0.6 0.6 Pure water pressure, bar 44.6 44.5 43.6 44.3 44.2 44.3 44.1 1.1 44.0 45.3 45.4 45.4 45.4 46.5 45.4 44.4 45.3 45.6 Seawater flow rate, m3/h 12.1 12.3 12.5 12.0 12.0 12.1 12.6 0.0 11.6 12.4 12.4 12.1 12.4 12.1 12.5 12.2 12.3 12.4 Permeate flow rate, m3/h 778.3 776.5 780.0 785.0 789.0 791.0 795.3 20.3 847.8 840.3 839.0 837.5 837.5 818.5 805.5 804.5 798.5 792.0 Water quality, µS/cm Started Error installations at a long distance from each other and can be remotely controlled. The system is: • Modular • Simple • Flexible • Easily programmable • With low cost • User-friendly and adjustable to customer needs • Simulator of the in-plant real time flow characteristics • Quick fault finder • Reliable The system was applied to the Oia RO plant with a great reduction in labor cost. On the other hand, a detailed analysis of the data collected can give information for possible future breakdown and preventive maintenance can be applied.