Author: ekor_user

The system for monitoring of sulfuric acid concentration in the synthesis of hydroxylamine sulphate (for a single channel measurement of concentration) consists of:

• concentration sensor;;
• spark protection block;;
• potentiostatic device;
• industrial PC with I / O board.

The operation of the system is based on the relationship between redox currents on the polarized electrode in potentiodynamic mode and the of sulfuric acid concentration.

How the system works:

• At a signal from the computer potentiostatic device served potential difference across the concentration sensor; Current signal from the concentration sensor through the spark protection block is measured by potentiostatic device is converted into a voltage and fed to the ADC board computer;
• The computer calculates the magnitude of the signal on the concentration of sulfuric acid. On the basis of the monitoring system the system of regulation of the maintenance of sulfuric acid can be realized. The computer compares the measured value of the concentration of sulfuric acid with a given, calculates the control action, which comes with a DAC board to the valve through a conversion device.

Software and hardware complex (SHC) is designed for a wide range of scientific research in various fields of chemistry and physics. In particular, for the study of electrochemical processes occurring in the electrode-electrolyte interface. SHC is assembled on modern element base, which ensures high accuracy, reliability, performance and stability of its operation. The work of SHC is managed by a modern, leading in research, software that enables management of SHC and performs collection and processing of data in real time.

Distinctive features of SHC are:

1. Ability to work on grounded objects (including those in industrial conditions, in environments that are directly within the operating units).

2. The possibility of simultaneous independent study of the two electrode systems on two channels in a single solution (allows simultaneous study of different materials in the same solution in exactly the same conditions).

3. The possibility of forming of the polarization signal of complex form.

4. The possibility of forming of the currents up to 5 amps.

SHC allows you to:

1. Maintain a given potential of the working electrode.

2. Change the potential of the working electrode according to the given function (linear, step, sinusoidal, etc.) with different rates.

3. Maintain a given polarization current of the working electrode.

4. Change the polarization current of the working electrode linear and stepwise with different rates.

5. Measure and record the polarization current of the working electrode.

6. Measure and record the potentials of the working and supporting electrodes with respect to the reference electrode.

7. Work in the measure mode for electrode potentials (potentiometer).

8. Perform corrosion-electrochemical measurements.

9. Measure the concentration of substances by the potentiometric method.

10. Measure the concentration of substances by the voltammetric method.

11. Generate the recorded data for further computer processing.

Currently, the control (monitoring) of corrosion condition and control of corrosion speed of devices and pipelines in contact with aggressive environment, get the same value in order of importance as the control and regulation of the basic parameters of technological processes.

The active form of corrosion control provides for anticorrosive and technological measures that reduce the corrosion rate to acceptable values on the basis of received information. With the help of corrosion control systems can be efficiently solved the problems of control and corrosion protection of industrial equipment in sulfuric acid, phosphoric acid, hydrochloric acid, chloride, ammonia environments, as well as the circulating water, fertilizer solutions and solutions of gas purification from CO2. It was found that in aggregates of ammonia synthesis gas cleaning environment from CO2 are highly corrosive in relation to the carbon steel. To reduce the corrosion rate of the equipment in hot Benfield solutions is used as an inhibitor of vanadium pentoxide. However, the inhibitory (critical) concentration of V+5 – ions depends on several conditions – both process (temperature, CO2, etc.) and corrosion (steel surface condition, its potential). Currently, control of the content of the inhibitor and corrosion of equipment in the Benfield solution carry on the results of laboratory analyzes of vanadium ions and iron ions.

The main disadvantages of a laboratory method for the determination of vanadium ions and iron are the frequency analysis (once daily), as well as its complexity and subjectivity. The disadvantage of determining the corrosion rate by the corrosionelectrochemical methods in the laboratory is the complexity of modeling the conditions of the industrial apparatus (pressure up to 28 atm and temperatures above 100 °C, surface irrigation, the saturation of CO2, etc.).

Research has shown that the most effective way to determine and maintain the passive state of equipment is control of corrosion state by the potential. There is a clear dependence between the rate of corrosion of carbon steel in Benfield solutions and the value of the corrosion potential. Therefore, the surface potential of the equipment reflects its state of corrosion most objectively. The sharp increase of the rate of corrosion of equipment is the result of a violation of the passive state.

At the same time to reduce the rate of corrosion of equipment to acceptable values you need an increased concentration of pentavalent vanadium, and to maintain a passive state concentration of V+5 – ions can be reduced in several times

The system for monitoring of the water mass fraction in the urea melt(for a single channel measurement of concentration) consists of:

• concentration sensor;
• spark protection unit;
• unit of signal normalization;
• valve of refrigerant supply;
industrial PC with input-output boards.

Principle of the system:

• supplying of refrigerant to the concentration sensor and measuring the temperature inside the sensor during cooling and melt crystallization;
• analysis of the measured dependence “temperature – time” in the “sliding window”, crystallization temperature definition;
• calculation of the water mass fraction in the urea melt.

After determining of the crystallization temperature supply of the refrigerant stops, the environment inside the concentration sensor renews and the cycle repeats.

Time of cycle is about 10 min

The system for continuous monitoring of the water mass fraction in the ammonium nitrate melts (for one channel of concentration measuring) consists of:

• concentration sensor;
• spark protection unit;
• unit of signal normalization;
• valve of refrigerant supply;
industrial PC with input-output boards.

Principle of the system:

• supplying of refrigerant to the concentration sensor and measuring the temperature inside the sensor during cooling and melt crystallization;
• analysis of the measured dependence “temperature – time” in the “sliding window”, crystallization temperature definition;
• calculation of the water mass fraction in the ammonium nitrate melt.

After determining of the crystallization temperature supply of the refrigerant stops, the environment inside the concentration sensor renews and the cycle repeats.

Time of cycle is about 10 min