In addition to the information concerning safety or potential explosion hazard of a certain gas mixture being tested, one can obtain experimental data on the parameters of an explosion (such as pressure, temperature, flame front velocity); gas mixture initiation/ignition conditions (i.e. ignition source energy, ignition source type, etc.); and the external factors affecting the fire and explosion safety (for example, external heating, mixture weakening, initial pressure, the presence of impurities).
The experimental facility is an automated system of hardware and measuring equipment that includes:
- a test facility consisting of test chambers, a receiver tank, a control panel, and gas supply pipelines;
- a gas mixing facility with gas supply pipelines;
- a control system, application-dependent software, and computer-aided data measurement channels for remote automatic measurement of the test chamber medium parameters, as well as the parameters of gas mixture initiation.
The test chamber is a key element of the test facility. It is designed as a demountable vessel where the explosive transformation of gas mixtures takes place. Today, due to the unique design of its bottom part, the test chamber is available in five different design versions as shown in the figure below. Specifications for each version are given in the table.
Chamber design version | RS2181.010 | RS2181.350/ RS2181.310 | RS2181.350-01/ RS2181.310-01 |
|---|---|---|---|
Effective volume, cm3 | 2226 / 10419 | ~5000/~7800 | ~2000/~8500 |
Maximum operating pressure, MPa (kg/cm2) | 1.2 (12) | 6(60)/0.25 (2.5) | 6(60) |
Operating temperature, oС | 20 oС – 80 oС | 20 oС – 200 oС | 20 oС – 200 oС |
Pressure sensors, thermocouples, a humidity sensor, sensors of the ignition system, a water injection system, a gas sampling and analysis system, and a gas mixing device are installed inside the chamber or connected to the chamber.
Temperature measurement channels: | |
|---|---|
Number of channels | 5 |
Temperature measuring range, оС | 0…1000 |
Temperature sensor polling interval, msec | 100 |
Temperature measurement error (95% CI), оС | ≤4 |
Pressure measurement channels: | |
|---|---|
Number of channels | 2 |
Pressure measuring range, MPa | 0.1…2.5 |
Pressure sensor polling interval, msec | 1 |
Pressure measurement error (95% CI) | ≤2% |
Gas medium humidity measurement channel: | |
|---|---|
Number of channels | 1 |
Relative humidity measuring range | 100% |
Temperature range, оС | −40 … +160 оС |
Gas medium pressure range | Up to 250 kPa |
The ignition system includes such initiators as a spark gap based on a car spark plug and a high-power spark initiation source with adjustable gap, as well as heating elements that have different heating surface area and are installed in the bottom part of the test chamber. The electric spark plug and the spark initiation source are used to simulate the parameters of gas medium ignition by a discharge with the energy ranging from 0.1 to 1000 mJ. A heating element, i.e. a NiCr coil, is used to simulate the ignition of gas mixture due to heating. The coil surface temperature can be adjusted in the range from 200 to 1100 °С.
The water injection system includes nozzles, a water tank, a solenoid valve, and a compressor.
The gas mixing device is a pumping station with a system of pipelines that form a loop system with the test chamber.
The MOTODOC diagnostic equipment (Quantex Laboratory) is used to record spark-pulse parameters (such as pulse shape, pulse length, breakdown voltage, and peak ionization current) and the time needed to ignite the mixture after the initiating pulse is fed.
The sampling system used to analyze hydrogen, oxygen, nitrogen, and organic content of a gas medium during the experiment consists of pipelines, valves, a vacuum pump, and a portable gas chromatograph Micro GC 490.
The test chamber version equipped with viewing windows allows shadow videorecording of a gas mixture with the flame front velocity measurement.
During the experiments studying fire and explosion hazards of gas media, remote automatic measurements of parameters of the processes that take place inside the test chamber are made. A converted signal is sent to a computer to neutron processed by PVB_154 software and is subsequently displayed on a screen in a graphical form.
The facility is widely used in the NPP safety analysis to obtain experimental data on the behavior of hydrogen-steam-gas mixtures of different composition under conditions similar to those observed during severe accidents that occur at nuclear power plants, as well as the data on the efficiency of catalysts of different types, which can be used when developing hydrogen recombiners for nuclear power plants.