New washing oil adding system for crude benzene recovery process

Abstract

The utility model discloses a new wash oil adding system for a crude benzene recovery process. The new wash oil adding system comprises a benzene washing tower, a benzene removal tower, a wash oil storage tank, a rich oil storage tank, a lean oil cooler, a lean and rich oil heat exchanger, a lean oil tank, a rich oil pump and a lean oil pump, a rich oil outlet of the benzene washing tower is communicated with a rich oil inlet of the rich oil storage tank through a pipeline, a rich oil outlet of the rich oil storage tank is communicated with an inlet of one flow path of the lean and rich oil heat exchanger through a pipeline and a rich oil pump, and an outlet of the flow path is communicated with a rich oil inlet of the benzene removal tower through a pipeline; a lean oil outlet of the debenzolization tower is communicated with a lean oil inlet of the lean oil tank through a pipeline, a lean oil outlet of the lean oil tank is communicated with an inlet of the other flow path of the lean-rich oil heat exchanger through a pipeline and the lean oil pump, and an outlet of the flow path is communicated with a lean oil inlet of the lean oil cooler through a pipeline. A lean oil outlet of the lean oil cooler is communicated with a lean oil inlet of the benzene washing tower through a pipeline. The system can stabilize the pressure and temperature of the top of the debenzolization tower, improve the debenzolization efficiency, save the steam consumption and reduce the production cost.

Description

Technical Field

[0001] The utility model relates to the technical field of crude benzene recovery, in particular to a new wash oil adding system for a crude benzene recovery process. Background Art

[0002] In the crude benzene recovery process using the wash oil absorption method, wash oil is the main medium for eluting benzene. The existing crude benzene new wash oil adding system is as follows: one new wash oil adding method is that the new wash oil sent from the oil washing storage tank in the oil depot area is added to the rich oil storage tank by a wash oil metering pump, the new wash oil is pumped out with the rich oil by a rich oil pump, and sent to the lean-rich oil heat exchanger for heat exchange and temperature increase with the hot lean oil, and enters from the upper part of the debenzene tower after temperature increase. In the debenzene tower, the rich oil is stripped and distilled by direct steam, and the rich oil with benzene removed becomes lean oil and enters the lean oil tank. The hot lean oil in the lean oil tank is pumped out by a lean oil pump, and sent to the lean-rich oil heat exchanger for heat exchange and temperature reduction with the rich oil, and then passes through the lean oil cooler and the temperature drops to the wash oil absorption temperature range, the lean oil enters from the upper part of the benzene washing tower, absorbs the benzene in the coal gas to become rich oil, and finally flows into the rich oil storage tank by gravity; another new wash oil adding method is that the new wash oil sent from the oil washing storage tank in the oil depot area is directly added to the upper part of the benzene washing tower by a wash oil metering pump to spray the coal gas.

[0003] However, the existing system for adding new wash oil to crude benzene has defects and cannot meet the requirements of the crude benzene recovery process of the wash oil absorption method. If the new wash oil is added to the rich oil storage tank, on the one hand, the new wash oil is directly sent to the upper part of the debenzene tower for stripping and distillation without absorbing benzene in the coal gas, which wastes steam consumption and increases production costs; on the other hand, the water content in the new wash oil is relatively high. If it is sent to the upper part of the debenzene tower without dehydration, the water in the new wash oil is easily cavitated under the action of direct steam in the negative pressure environment of the debenzene tower, making the negative pressure at the top of the debenzene tower unstable, thereby causing the temperature at the top of the debenzene tower to fluctuate greatly, reducing the debenzene efficiency. If the new wash oil is directly added to the upper part of the benzene washing tower, there is a deviation between the temperature of the new wash oil and the temperature requirement range for the wash oil to absorb benzene, resulting in a high benzene content in the coal gas after the benzene washing tower, reducing the efficiency of washing oil and benzene removal, and failing to meet the process technology requirements. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a new washing oil adding system for a crude benzene recovery process with high debenzene efficiency.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is: it includes a benzene washing tower, a debenzene tower, a wash oil storage tank, a rich oil storage tank, a lean oil cooler, a lean-rich oil heat exchanger, a lean oil tank, a rich oil pump and a lean oil pump; the rich oil outlet of the benzene washing tower is connected to the rich oil inlet of the rich oil storage tank through a pipeline, the rich oil outlet of the rich oil storage tank is connected to the inlet of one flow path of the lean-rich oil heat exchanger through a pipeline and the rich oil pump, and the outlet of this flow path is connected to the rich oil inlet of the debenzene tower through a pipeline; the lean oil outlet of the debenzene tower is connected to the lean oil inlet of the lean oil tank through a pipeline, the lean oil outlet of the lean oil tank is connected to the inlet of another flow path of the lean-rich oil heat exchanger through a pipeline and the lean oil pump, the outlet of this flow path is connected to the lean oil inlet of the lean oil cooler through a pipeline, and the lean oil outlet of the lean oil cooler is connected to the lean oil inlet of the benzene washing tower through a pipeline; the wash oil outlet of the wash oil storage tank is connected to the wash oil inlet of the lean oil tank through a pipeline.

[0006] Furthermore, the rich oil inlet of the rich oil storage tank is lower than the rich oil outlet of the benzene washing tower, and the lean oil inlet of the lean oil tank is lower than the lean oil outlet of the benzene removal tower.

[0007] Furthermore, the rich oil storage tank is arranged at the lower part of the benzene washing tower, and the lean oil tank is arranged at the lower part of the benzene desorption tower.

[0008] Furthermore, a wash oil metering pump is provided; the wash oil metering pump is provided on the pipeline between the wash oil storage tank and the lean oil tank.

[0009] The beneficial effects of adopting the above technical solution are as follows: the utility model heats and dehydrates the new wash oil through the hot lean oil in the lean oil tank, thereby avoiding large fluctuations in the top temperature of the tower when the new wash oil enters the upper part of the debenzene tower for debenzene distillation, thereby improving the debenzene efficiency; the lean oil temperature is lowered and the rich oil temperature is increased through the lean-rich oil heat exchanger; the lean oil cooler reduces the lean oil temperature to the wash oil absorption temperature range required by the process. The utility model controls the temperature of the new wash oil entering the debenzene tower within the wash oil absorption temperature range required by the process, thereby improving the wash oil and benzene removal efficiency; the new wash oil is heated and dehydrated before entering the debenzene tower, thereby avoiding cavitation of the new wash oil in the negative pressure environment of the debenzene tower, stabilizing the pressure and temperature at the top of the debenzene tower, and improving the debenzene efficiency; the new wash oil is heated and dehydrated with the help of the heat of the hot lean oil, thereby saving steam consumption and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0011] Figure 1 It is a structural diagram of the present utility model. DETAILED DESCRIPTION

[0012] Figure 1As shown, the new wash oil addition system of the crude benzene recovery process includes a benzene washing tower, a benzene removal tower, a wash oil storage tank, a rich oil storage tank, a lean oil cooler, a lean-rich oil heat exchanger, a lean oil tank, a rich oil pump and a lean oil pump. The rich oil inlet of the rich oil storage tank is lower than the rich oil outlet of the benzene washing tower, and it is best if the rich oil storage tank is arranged at the lower part of the benzene washing tower; the lean oil inlet of the lean oil tank is lower than the lean oil outlet of the debenzene tower, and it is best if the lean oil tank is arranged at the lower part of the debenzene tower. The rich oil outlet of the benzene washing tower is connected to the rich oil inlet of the rich oil storage tank through a pipeline, and the rich oil outlet of the rich oil storage tank is connected to the inlet of a flow path of the lean-rich oil heat exchanger through a pipeline and a rich oil pump, and the outlet of this flow path is connected to the rich oil inlet of the debenzene tower through a pipeline. The lean oil outlet of the debenzene tower is connected to the lean oil inlet of the lean oil tank via a pipeline. The lean oil outlet of the lean oil tank is connected to the inlet of another flow path of the lean-rich oil heat exchanger via a pipeline and a lean oil pump. The outlet of this flow path is connected to the lean oil inlet of the lean oil cooler via a pipeline. The lean oil outlet of the lean oil cooler is connected to the lean oil inlet of the benzene scrubbing tower via a pipeline. The wash oil storage tank is used to store new wash oil and has a heat preservation function to prevent the wash oil from decreasing in temperature and reducing its fluidity. The wash oil outlet of the wash oil storage tank is connected to the wash oil inlet of the lean oil tank via a pipeline and a wash oil metering pump.

[0013] The lean-rich oil heat exchangers in the new wash oil adding system of the crude benzene recovery process are preferably two sets in series, and the lean oil coolers are preferably two sets in series.

[0014] The process of using the new wash oil addition system in this crude benzene recovery process is as follows:

[0015] (1) The new wash oil in the wash oil storage tank is fed into the lean oil tank through the wash oil metering pump, and the hot lean oil in the lean oil tank is used for heating and dehydration. Since the proportion of the new wash oil added is small, the temperature of the hot lean oil in the lean oil tank is less affected.

[0016] (2) The new washing oil from the lean oil tank is pumped out along with the lean oil by the lean oil pump and sent to the lean-rich oil heat exchanger for heat exchange with the rich oil, which not only reduces the lean oil temperature but also transfers heat to the rich oil, thereby increasing the rich oil temperature and achieving the effect of energy saving and consumption reduction. The lean oil with reduced temperature is then cooled by the lean oil cooler to the washing oil absorption temperature range required by the process, so as to meet the optimal temperature for the washing oil to absorb benzene in the coal gas in the benzene washing tower, thereby improving the washing oil and benzene washing efficiency.

[0017] (3) The lean oil is sent to the upper part of the benzene washing tower to spray the coal gas, absorbing the benzene in the coal gas and becoming rich oil. The rich oil enters the rich oil storage tank under the action of gravity.

[0018] (4) The rich oil in the rich oil storage tank is pumped out by a rich oil pump, and is heat exchanged with the hot lean oil sent out from the lean oil tank through a lean-rich oil heat exchanger. The rich oil temperature is raised to the required temperature for debenzenization distillation and then enters the upper part of the debenzenization tower.

[0019] (5) In the debenzenization tower, the rich oil is stripped and distilled with direct steam. After the benzene is removed from the rich oil, it becomes lean oil and enters the lean oil tank under the action of gravity.

Claims

1. A new wash oil addition system for a crude benzene recovery process, characterized by: It includes a benzene washing tower, a benzene desorbing tower, a wash oil storage tank, a rich oil storage tank, a lean oil cooler, a lean-rich oil heat exchanger, a lean oil tank, a rich oil pump and a lean oil pump; the rich oil outlet of the benzene washing tower is connected to the rich oil inlet of the rich oil storage tank through a pipeline, the rich oil outlet of the rich oil storage tank is connected to the inlet of one flow path of the lean-rich oil heat exchanger through a pipeline and the rich oil pump, and the outlet of the flow path is connected to the rich oil inlet of the debenzene tower through a pipeline; the lean oil outlet of the debenzene tower is connected to the lean oil inlet of the lean oil tank through a pipeline, the lean oil outlet of the lean oil tank is connected to the inlet of another flow path of the lean-rich oil heat exchanger through a pipeline and the lean oil pump, the outlet of the flow path is connected to the lean oil inlet of the lean oil cooler through a pipeline, and the lean oil outlet of the lean oil cooler is connected to the lean oil inlet of the benzene washing tower through a pipeline; the wash oil outlet of the wash oil storage tank is connected to the wash oil inlet of the lean oil tank through a pipeline.

2. The new wash oil adding system of a crude benzene recovery process according to claim 1, characterized in that: The rich oil inlet of the rich oil storage tank is lower than the rich oil outlet of the benzene washing tower, and the lean oil inlet of the lean oil tank is lower than the lean oil outlet of the benzene removal tower.

3. The new wash oil adding system of a crude benzene recovery process according to claim 2, characterized in that: The rich oil storage tank is arranged at the lower part of the benzene washing tower, and the lean oil tank is arranged at the lower part of the benzene desorption tower.

4. The new wash oil adding system of a crude benzene recovery process according to claim 1, 2 or 3, characterized in that: A wash oil metering pump is also provided; the wash oil metering pump is arranged on the pipeline between the wash oil storage tank and the lean oil tank.

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