Low-pressure drop ethylbenzene evaporator and energy-saving process for ethylbenzene vaporization in styrene dehydrogenation reaction system

An energy-saving process for ethylbenzene vaporization in a styrene dehydrogenation reaction system, comprising:

• a) setting up a main cooler, an aftercooler, and an oil-water separation tank;
• allowing styrene dehydrogenation reaction material as a raw material and boiler feed water to enter a shell side and a tube side of the main cooler respectively for heat exchange, controlling an outlet pressure on the tube side at 6-32 kpaA, and pressurizing the unevaporated water on the tube side by a water circulation pump before returning to the tube side with the raw material boiler feed water;
• after cooling the styrene dehydrogenation reaction material, a liquid phase formed by gas-liquid separation enters to the oil-water separation tank, then cooling a formed gas phase again by the aftercooler, and a separated secondary liquid phase enters the oil-water separation tank, and a separated tail gas enters a subsequent treatment unit;
• and
• b) setting up a steam compressor and a low-pressure drop type ethylbenzene evaporator, steam of 6-32 kpaA generated on the tube side of the main cooler is compressed into saturated steam of 0.04 MpaG by the steam compressor as steam distribution to enter the shell side together with raw material ethylbenzene through a low-pressure steam feed tube and a liquid stream inlet of the low-pressure drop type ethylbenzene evaporator respectively, and heating and evaporating by introducing a hot steam into the heat exchange tube to form a mixture of ethylbenzene and water steam, which enters a superheater;
• wherein the low-pressure drop type ethylbenzene evaporator comprises a heat exchange unit,
• wherein, the low-pressure drop type ethylbenzene evaporator further comprises a gas-liquid separation unit that separates an inflowing vaporized mixture and forms a double-layer structure with the heat exchange unit;
• the gas-liquid separation unit on an upper layer is connected with the heat exchange unit on a lower layer through an intermediate tube;
• a top of the gas-liquid separation unit is equipped with an exhaust tube, and a bottom of the gas-liquid separation unit is equipped with a separation liquid return tube;
• the heat exchange unit is a horizontal shell-and-tube type heat exchange unit, which comprises a shell side, a tube box located at one end of the shell side, and a heat exchange tube placed horizontally in the middle of plates of the tube box;
• the tube box is equipped with a heat medium inlet and a heat medium outlet, and a bottom of the shell side is equipped with a liquid stream inlet;
• a side wall of the shell side is also equipped with low-pressure steam feed tubes located below and close to the heat exchange tube.