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Y. Xu et al.
30.2 Structural Characteristics of Common Double-Wall
Cryogenic Vertical Storage Tanks
A double-wall cryogenic vertical storage tank consists of an inner tank and an outer
tank. A thick rigid insulating plate is usually used between the inner bottom plate and
the outer bottom plate. The space between the inner and outer cylinders is usually
filled with pearlite sand and inert gas. In this way, the inner tank can be kept at a
certain deep cold temperature. The foundation of this kind of tank is usually overhead.
Because it is very difficult to open and repair this kind of tank, stainless steel is usually
chosen as the material of the inner tank to facilitate long-term operation. For the online AE detection of such tanks without opening tanks, the key technical problem to
be solved is how to transmit AE signals from the inner tank. Therefore, it is necessary
to adopt some effective acoustic wave transmission method according to the different
actual structure characteristics of storage tanks.
30.3 Waveguide Methods for Three Double-Wall Tanks
with Different Infrastructures
In recent years, according to the foundation structure characteristics of several
common double-wall cryogenic tanks, we have adopted different acoustic conduction
methods to effectively realize AE on-line monitoring of these tanks.
30.3.1 Method One: Probe Waveguide Rods
A 15,500 m
3 double-wall cryogenic ethylene storage tank (T7001) of a large petrochemical enterprise in Jiangsu Province is based on an overhead structure. By
consulting the drawings and field observation, no exposed metal components welded
with the inner tank wall can be used for acoustic wave transmission of the inner tank.
However, we found that a certain number of instrumentation nozzles were distributed
along the outer tank wall circumference about 1 m from the bottom plate of the
outer tank. We specially designed the carbon steel probe waveguide rod as shown in
Fig. 30.1, so that the acoustic signals from the internal storage tank can be received
by the sensors mounted on the probe waveguide rods. The photo of a waveguide rod
is shown in Fig. 30.2.
The total length of the waveguide rod is determined by the distance between the
inner and outer tank walls, the thickness of the outer wall and the length of the
instrumentation nozzle. In order to maintain close coupling between the waveguide
rod and the inner tank wall, the waveguide rod is threaded to the center hole of the
outer flange. Before the implementation of AE testing, we temporarily remove the
instrumentation device, insert the waveguide rod into the nozzle and make it close
Y. Xu et al.
30.2 Structural Characteristics of Common Double-Wall
Cryogenic Vertical Storage Tanks
A double-wall cryogenic vertical storage tank consists of an inner tank and an outer
tank. A thick rigid insulating plate is usually used between the inner bottom plate and
the outer bottom plate. The space between the inner and outer cylinders is usually
filled with pearlite sand and inert gas. In this way, the inner tank can be kept at a
certain deep cold temperature. The foundation of this kind of tank is usually overhead.
Because it is very difficult to open and repair this kind of tank, stainless steel is usually
chosen as the material of the inner tank to facilitate long-term operation. For the online AE detection of such tanks without opening tanks, the key technical problem to
be solved is how to transmit AE signals from the inner tank. Therefore, it is necessary
to adopt some effective acoustic wave transmission method according to the different
actual structure characteristics of storage tanks.
30.3 Waveguide Methods for Three Double-Wall Tanks
with Different Infrastructures
In recent years, according to the foundation structure characteristics of several
common double-wall cryogenic tanks, we have adopted different acoustic conduction
methods to effectively realize AE on-line monitoring of these tanks.
30.3.1 Method One: Probe Waveguide Rods
A 15,500 m
3 double-wall cryogenic ethylene storage tank (T7001) of a large petrochemical enterprise in Jiangsu Province is based on an overhead structure. By
consulting the drawings and field observation, no exposed metal components welded
with the inner tank wall can be used for acoustic wave transmission of the inner tank.
However, we found that a certain number of instrumentation nozzles were distributed
along the outer tank wall circumference about 1 m from the bottom plate of the
outer tank. We specially designed the carbon steel probe waveguide rod as shown in
Fig. 30.1, so that the acoustic signals from the internal storage tank can be received
by the sensors mounted on the probe waveguide rods. The photo of a waveguide rod
is shown in Fig. 30.2.
The total length of the waveguide rod is determined by the distance between the
inner and outer tank walls, the thickness of the outer wall and the length of the
instrumentation nozzle. In order to maintain close coupling between the waveguide
rod and the inner tank wall, the waveguide rod is threaded to the center hole of the
outer flange. Before the implementation of AE testing, we temporarily remove the
instrumentation device, insert the waveguide rod into the nozzle and make it close