Corrosion Control and Decreased Operational Costs with Memosens for Overhead Condenser pH
When crude oil leaves the desalter it moves into the distillation tower. Inside the tower, steam heats the crude, converting it into vapor. There are a series of trays that allow the condensation of the vapor into different cuts of hydrocarbons. The light hydrocarbon fractions and steam exit the top of the tower through a pipe and into the overhead condenser for cooling. The unit creates condensate and collects the hydrocarbon liquids. Operators route the remaining gases to a compressor for further processing.
After the overhead system condenses the hydrocarbon vapor and steam, the resulting liquid is acidic. Ammonia and amine injections neutralize the pH. Depending on the temperature of the overhead, too much ammonia can cause salts to form, leading to more corrosion. Therefore, having an accurate and repeatable overhead condenser pH measurement allows for even more control of ammonia addition to prevent overdosing the system.
The Solution
The overhead condenser is challenging for pH electrodes. Consequently, sulfides often poison sensor reference systems. This can cause sensors to drift or fail. The SE 555 Memosens pH sensor is ideal for use in this application. The sensor’s ceramic junction and pressurized reference system resist damage from sulfides. In addition, the glass encapsulated design prevents poisoning of the Silamid® reference electrode, greatly extending sensor life.
A microprocessor in the head of the pH sensor allows for offline calibration and sensor health analysis. When using a Portavo portable analyzer, technicians can calibrate and troubleshoot in the shop or lab instead of inside the processing unit. Controlling the pH buffer solutions allows for more precise calibrations. After calibration, the technician simply carries it out to the installation, disconnects the Memosens inductive cable, and does a “hot-swap” with no additional calibration or configuration.
The Stratos Pro is a two-wire loop-powered Class 1 Div 1 FM/CSA rated transmitter. It provides a 4…20 mA output, superimposed with HART process and diagnostic data. This provides the added benefit of predictive maintenance reducing the potential for unscheduled process interruptions. As a result, technicians can install a newly calibrated Memosens pH probe in a matter of minutes, resulting in almost no interruption to the measurement.
What was this Customer’s Return on Investment?
Reduced operational cost: Reliable pH monitoring helps reduce chemical usage by eliminating overdosing ammonia and amines in the overhead system.
Improved corrosion control in the overhead condenser: Accurate overhead condenser pH monitoring minimizes the amount of corrosive liquid in the overhead piping reducing costly downtime and process equipment replacement.
Decreased sensor replacement: The SE 555’s ceramic diaphragm and patented reference system provide extended life in the high sulfide environment found in the overhead condenser.
