Fluid handling – Systems – Closed circulating system
Reexamination Certificate
2001-02-21
2003-07-08
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Closed circulating system
Reexamination Certificate
active
06588450
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tank for storing a viscous oil containing easily polymerizable compounds. In particular, the invention pertains to a storage tank for bottom liquid which is obtained by distilling a crude liquid to obtain an easily polymerizable compound such as (meth)acrylic acid and/or liquid containing such a compound.
2. Description of the Prior Art
Conventionally, distillation (employing a distillation tower) has been utilized for producing an easily polymerizable compound such as (meth)acrylic acid and/or (meth)acrylic ester from a crude liquid. Distillation is an operation in which a crude liquid composed of two or more liquids in a mixed manner, each having a different boiling point, is heated for vaporization. During distillation, a gas (or vapor) mainly composed of a component having a lower boiling point is condensed and removed from the distillation tower. Also, a liquid mainly composed of a component having a high boiling point is stored at a bottom of the distillation tower. The liquid stored at the bottom may be redistilled for recovering active principles of the liquid and thus condensed liquid, which is also stored at the bottom has high viscosity and is removed continuously or non-continuously form the distillation tower as a waste oil and is fed to a tank for storing thereof. The waste oil stored in the storage tank may be transferred to a waste oil processing unit such as combustion equipment, and the waste oil may be disposed by performing a burning treatment or another treatment.
Since the waste oil has high viscosity, the waste oil in the storage tank is stored at relatively high temperatures to lower its viscosity. Even though storing the waste oil at the high temperatures is effective to lower its viscosity, the high temperatures facilitate polymerization of easily polymerizable compounds contained in the waste oil. In this case, a stabilizer such as a polymerization inhibitor is added to the waste oil to prevent polymerization of the compounds. Even though the stabilizer suppresses polymerization of easily polymerizable compounds, the stabilizer tends to be precipitated easily at high temperatures. Because of these properties of the waste oil, polymerization inevitably would occur in the storage tank. Polymerization products cause problems of clogging a pipe which connects the storage tank and a waste oil processing unit. Also, polymerization products cause clogging of a pipe of an attached unit.
A polymerization product which is adhered to an inside wall of the pipes hampers the ability of transferring the waste oil to the waste oil processing unit, and needs to be removed manually or chemically at regular intervals. These removing operations lower waste oil treatment efficiency and even lower distillation efficiency.
SUMMARY OF THE INVENTION
A storage tank for storing viscous oil containing easily polymerizable compounds, comprises a bottom plate
12
, a side wall
13
, a draw-off pipe
3
and an inlet pipe
2
. The bottom plate
12
slopes downwardly toward the draw-off pipe
3
, and an angle of downward inclination of the bottom plate
12
is a gradient of at least 1/200.
REFERENCES:
patent: 3754734 (1973-08-01), Hoyle et al.
patent: 3874399 (1975-04-01), Ishihara
patent: 6214619 (2001-04-01), Sato et al.
patent: 6414183 (2002-07-01), Sakamoto et al.
Ijiri Yuichi
Matsumoto Yukihiro
Munechika Fumio
Nakahara Sei
Michalsky Gerald A.
Nippon Shokubai Co. , Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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