Corrosion process, on any oil chemical equipment, determined on the one hand corrosive technological environment, on the other, the chemical stability of the metal of the process equipment, that is, its corrosion resistance.
In the process of primary oil processing in refineries most aggressive to metal vessels and pipelines are the technological environment containing water with dissolved oxygen, mineral salts, hydrogen chloride, hydrogen sulfide, sodium hydroxide.
According to leading Western and Russian experts involved in the study of corrosion deterioration of equipment for primary distillation of crude oil, can identify a number of relevant factors that may be encountered in the future:
increasing sulfur compounds;
not prepared equipment for the processing of sour and heavy crude oils;
increased risks that lead to equipment failure due to corrosion, especially at idle processing units;
the growing influence of corrosive compounds (sulfur, salt, sulfur compounds and organic chlorides).
First, change the working environment corrosivity manifested in unstable operation of the equipment, and the corrosive wear of exposed columns, tanks, heat exchangers and piping corps. In these circumstances, in addition to general corrosion, a problem
integrity equipment are local types of corrosion (pitting, intergranular) and stress corrosion cracking. Prediction and control of the above corrosion damage is now extremely complex and ambiguous. On the process flow of local corrosion and stress corrosion cracking is significantly affected by a number of specific factors of equipment refinery process units.
These specific factors are:
application of chemical-technological methods of protection equipment, including and the use of inhibitors;
the operation of steaming vessels and pipelines prior to the repair work with the formation of corrosive condensates;
downtime during repair work or other reasons, if the equipment corrosive deposits, as well as the presence of atmospheric moisture and oxygen.
Great influence the human factor, and also current methodologies for monitoring and corrosion protection measures during the operation. At present, most corrosion engineers perceive corrosion process as a continuous and stable process, in this case, mainly corrosive wear is determined by periodically measuring the rate of corrosion in service. As a rule - Once a month.
Unfortunately, in the real world, the situation on the effect of corrosive elements on corrosion carry other reasons, primarily related to changes in operating conditions and composition the environment in the process of distillation. Studies have shown that corrosion can occur even after several years of strong corrosive environment during operation. As a rule , Corrosion deal specialists only when the problem becomes critical, but once the problem resolved, everything goes back to "normal" routine ways of working to the next "unexpected" manifestations of corrosion. In most cases, the organization of anti-corrosion measures carried out by means of autonomous measurements based on the methods of weight loss (coupons), ultrasonic thickness (UST), and analytical monitoring of the environment. In this case, the information available on the corrosion of the equipment is the process variables over time, and only the data medium in size, which is not enough to understand the causes and corrosive conditions. Analysis of the effectiveness of corrosion events refineries in Russia at the present time has shown that there is a strong dependence of the efficiency of obtaining data on the corrosivity environments and the timeframe for action on the human factor, which significantly affects obtain effective results on corrosion measures. In the analysis and conclusions of the corrosion process, it is important to have a systematic approach in the evaluation methods applied, and taking into account the potential risks leading to failure of the equipment. No systematic approach itself has an impact on the total efficiency of preventive measures snizhayuscheniyu formation probability of risks and failures. Russian and foreign experts in the field of corrosion, believe that the effectiveness of the corrosion protection can only provide monitoring of corrosion processes real-time, which allows continuous monitoring of at least 90% of the total operating time.
For solutions this task proved to be the most effective corrosion monitoring system for oil extraction equipment and refining. The main goal of real-time - to exclude human error, increase the reliability and informativeness of corrosion processes on the basis of operational efficiency and timely management decisions.
Below in Fig. presented data illustrating the difference between having an analytical laboratory control, with the traditional ways of monitoring and continuous monitoring devices in real time.
Mnemo scheme Corrosion Monitoring at AVT
Scheme systems Corrosion monitoring of real time.
Trend inhibitor supply, depending on the sensor corrosion rate.
Data trends inhibitor supply depending on the evidence of pH on the AVT-6 Volgograd Refinery.
Structural scheme corrosion monitoring of real-time water treatment plant.
General view of the element of the block AT and trends obtained with periodic monitoring of chloride and real-time monitoring in the control zone at the outlet from the separator drain water.
a) Diagram of the installation process with the location of sampling and monitoring of chloride in real time.
b) These chloride concentrations in the work environment by the results of automatic and manual control of the analytical.
Anti - corrosive activities could have the effect only when the increase in the performance of human potential the right decisions. Examples of misuse of measures against corrosion - wrong choice of materials or inhibitors, surface disturbances and technological conditions. Failure and lack of efficiency anticorrosion measures based on the results obtained with the use of corrosion monitoring techniques are not controlled by corrosion during operation in the required amount.
Ineffective use of anti-corrosion measures affecting the impact on the environment, leading to unnecessary loss of expensive chemicals, contamination of the process streams of the corrosion products, lower product quality, performance, and production stop.
Certainly corrosion monitoring system enables real-time Timely obtain corrosion data, as well as to optimize the flow of inhibitors, which lowers the corrosion of equipment and increases the reliability of operation processing units. The resulting database of corrosion process allows you to organize and adjust as the methods and means of control, and receive extensive information on the corrosion processes in the primary distillation.
Corrosion Monitoring real-time, by means of automatic control systems, collecting, processing and visualization of information on the progress of corrosion processes on the process equipment installation during operation. All received data is displayed on the monitor in real time.
"Korsystem" is a leader in Russia's development and implementation of corrosion monitoring systems, real-time. For more than eight years of embedded systems development company "Korsystem" have proven to be effective in protecting equipment from corrosion.
Corrosion Monitoring System developed "Korsystem" provides a measurement parameter signals from sensors monitoring, and then send them through the transmitter to the server Corrosion Monitoring. All incoming information is collected and displayed on the monitor (or printer) as the main parameters affecting the corrosion processes.
Depending on the sensors, automatically, by the feed through automatic regulator inhibitor metering pump or valve. Inhibitor concentration in the work environment, changes in the automatic mode, depending on the sensors control.
Operator is displayed on the monitor process flow diagram, which shows the location of the sensors corrosion and pH, the points of entry of chemicals, control valves, metering pumps and frequency converters.
In real time on the monitor receives indications:
sensors with corrosion, the corrosion rate in real time;
pH sensors with data of pH and temperature of the medium;
with automatic regulators metering pumps (valves) - consumption of reagents fed.
The system has a visual and audible warning steps - anxiety, danger, and the norm in case of deviation from the norm, regardless of the human factor, the works program established acceptable values. In the process, based on a comparison continuously incoming data exclude human error and increases the accuracy of the readings.