Abstract: A method for determining the concentration of sulfide in a process stream. The method comprises the steps of adding to a process stream a sulfide scavenger (probe) that changes electronic properties when it reacts with sulfide. One can then monitor the electronic properties of the sulfide scavenger in the process stream to determine the concentration of sulfide present. In a preferred embodiment, the sulfide scavenger is either fluorescent and when it reacts with sulfide becomes inactive or is inactive and when it reacts with sulfide becomes fluorescent.

Abstract: A method and apparatus for automatically measuring the acidity of overhead water in an oil refinery, and dispensing a neutralizing agent into the refinery system at a rate responsive to that measurement. A sample of overhead water is collected and passed through a filter and cation exchange resin. The acid concentration of the sample is then automatically measured and a signal generated based on the concentration. The signal goes to a controller which controls the dispensation rate of neutralizing agent into the refinery system, thus reducing the acidity of the overhead water and limiting the corrosive effects of such acidity.

Abstract: A method for monitoring automatically, on-line chloride content in a fluid stream in an oil refinery. Additionally, the present invention provides a method for neutralizing the acids resulting from the chloride in a fluid stream. Pursuant to the method, a fluid sample is collected. To the sample is added a sulfide scavenger that will react with the sulfide that is present to create a reaction product. The fluid is then passed to a reaction or measurement cell including a chloride specific electrode. Prior to contacting the chloride specific electrode, the fluid must pass through a membrane that prevents the reaction product from flowing therethrough. The fluid that flows through the membrane is allowed to contact the chloride specific electrode. This allows the chloride content to be monitored in the fluid. The concentration of chloride can then be used to generate a signal to control the addition of a neutralizing agent to the fluid stream.

Abstract: A method and apparatus for automatically measuring the acidity of overhead water in an oil refinery, and dispensing a neutralizing agent into the refinery system at a rate responsive to that measurement. A sample of overhead water is collected and passed through a filter and cation exchange resin. The acid concentration of the sample is then automatically measured and a signal generated based on the concentration. The signal goes to a controller which controls the dispensation rate of neutralizing agent into the refinery system, thus reducing the acidity of the overhead water and limiting the corrosive effects of such acidity.