Role of Cyclic Thermal Shocks on the Physical and Mechanical Responses of White Marble

Marble is a common rock used in many buildings for structural or ornamental purposes and is widely distributed in underground engineering projects. The rocks are exposed to high temperatures when a tunnel fire occurs, and they will be rapidly cooled during the rescue process, which has a great impact on the rock performance and the underground engineering stability. Therefore, the role of cyclic thermal shocks on the physical and mechanical properties of marble specimens was systematically investigated. Different cyclic thermal shock treatments (T = 25, 200, 400, 600, 800 °C; N = 1, 3, 5, 7, 9) were applied to marble specimens and the changes in mass, volume, density and P-wave velocity were recorded in turn. Then, the thermal conductivity, optical microscopy and uniaxial compression tests were carried out. The results showed that both the cyclic thermal shock numbers (N) and the temperature level (T) weaken the rock properties. When the temperature of a thermal shock exceeds 600 °C, the mass loss coefficient and porosity of the marble will increase significantly. The most noticeable change in P-wave velocity occurs between 200 and 400 °C, with a 52.98% attenuation. After three thermal shocks, the cyclic thermal shock numbers have little influence on the uniaxial compressive strength and Young’s modulus of marble specimens. Shear failure is the principal failure mode in marble specimens that have experienced severe thermal damage (high N or T). The optical microscopic pictures are beneficial for illustrating the thermal cracking mechanism of marble specimens after cyclic thermal shocks.

MODELING OF HOT OIL LEAKAGE AT REGENERATION GAS HEATER ON DEHYDRATION PROCESS OF NATURAL GAS LIQUIFIED EXTRACTION (NGLE) GAS PLANT

The regeneration process in saturated dehydrator after working to drying the gas in the dehydration unit in the Natural Gas Liquified Extraction (NGLE) plant. This process is through the heating dehydrator process by flowing the regeneration gas into the dehydrator slowly (rump up temperature) until it reaches the heating temperature,and then holding the condition. Its condition is in accordance with the engineering design and followed by a rump down temperature which the dehydrator will be cooled down and ready for the dehydration process. This regeneration process works automatically in accordance with the engineering design which runs following the logic control that has been implemented into the Distributed Control System (DCS) in the Control Room. All order in DCS to obtain gas that has been moisture limited value which is allowed to be extracted. Regeneration gas was taken from the heat exchange between hot oil and regeneration gas in the regeneration gas heater package. This operation happend when the rump up temperature leaks the hot oil in the flange fitting of the regeneration gas heater package, its causes oil spillage (engineering design standart operation procedur). Its analysis case assumed the leakage is caused by thermal shock in the fittings of regeneration gas heater package in 2 % hot oil supply. To eliminate the thermal shock, a simulation of new models engineering design is initial by opening of the hot oil supply to the regeneration gas heater was changes with increasing its opening during stand-by conditions from 2% with a temperature at 45.72°C to 5% with a temperature at 51.61C in the Distributed Control System (DCS) logic control. The results goals with this implementation are no more hot oil leaks occur in the regeneration gas heater package. New models engineering design is stopping hot oil spillage, and maintaining operational continuity without having to spend money on repairing the regeneration gas heater package. process run in new models of engineering design, and this model becomes the new standard operating in start-up and commissioning plant process.