Scadapack 334 programming for a cooling tower.

Planet Paints is a small paint and petrochemical recycling business in Toowoomba, Australia. Recently we acquired several Scadapack 334 units from decommissioned RTU panels and would like to incorporate them into a new plant we are planning to build. The plant is a solvent distillation unit heated with thermal oil which is, in turn, heated by a package diesel burner located outside the hazardous area. Cooling of solvent vapours is achieved in a shell and tube condenser. Water is cooled by a radiator style heat exchanger which is also situated outside the hazardous area. This plant is controlled electromechanically with a rudimentary control panel. The new plant we hope to control via the Scadapack 334 units we have. The systems we want to control are as follows. Thermal oil system. Monitor temperature and pressure, control temperature, safety shutdown for abnormal pressure. Cooling system. Monitor cooling water temperatures, control cooling water pump motor and fan motors to react to differing operating conditions. Burner system. Monitor combustion conditions, control fuel and air addition rates to react to combustion conditions. Distillation system. Monitor plant temperatures. Currently the distillation process is monitored with analogue instruments to avoid the use of any electrical system inside the hazardous area. Here is an initial inputs and outputs list I have compiled. Digital/Analogue-Inputs/Outputs Digital inputs. 1. Oil pump on/off status. 2. Condenser water on/off status. Flow switch. 3. Burner status. On/off 4. Boil over protection. Photo electric detector mounted at base of distillation column. 5. High/low pressure switches (as an alternative to a pressure transducer). Digital outputs. 1. Burner on/off command. 2. Oil valve open/close commands. Maybe as many as 6 required. 3. Oil pump on/off 4. Burner on/off 5. Alarm of some sort. Analogue inputs-Temperature 1. Oil supply 2. Oil return 3. Oil temperature between secondary and primary heat exchangers. 4. Condenser water supply. 5. Condenser water return. 6. Distillation unit vapour temperature. 7. Condensed solvent temperature. 8. Ambient temperature. Analogue inputs-Other 1. Thermal oil pressure 2. Fuel level (note pressure switch option). Analogue outputs. 1. VFD for condenser water pump ( optional). 2. VFD for condenser fans. The various systems can be programmed one by one, for example we are planning to instal a cooling tower to replace the current radiator style unit in the near future. Other parts of the project are subject to government approvals and can be delayed. So for a start I’d like to focus on the cooling tower control system and see how things go with that.