CN112028732A - Method for reducing non-aromatic hydrocarbon at side line of benzene tower - Google Patents

Abstract

The invention relates to a method for reducing non-aromatic hydrocarbon at the side line of a benzene tower, which comprises the following steps: a. piping to the rough separation tower on a pipeline behind a gas-phase bypass adjusting valve at the top of the benzene tower, closing the gas-phase bypass to a benzene tower reflux tank, and adjusting the gas-phase bypass to be sent to the rough separation tower through the adjusting valve; b. piping to a crude toluene tank on an outlet pipeline of a reflux pump of the crude separation tower, sending benzene carrying non-aromatic hydrocarbon to the crude toluene tank through the reflux pump, and regulating the reflux amount of the crude separation tower down to be controlled at 16-20 t/h; c. the crude toluene tank is pumped to an aromatic hydrocarbon unit for recycling, non-aromatic hydrocarbons are removed, benzene is recycled to a benzene tank and is returned to the device for continuous use as fresh benzene; by adopting the process, the amount of non-aromatic hydrocarbon (total carbon five) extracted to the crude toluene tank can be adjusted at any time according to the content of the non-aromatic hydrocarbon in the catalytic dry gas sample analysis, so that the stable operation of the benzene tower is always ensured, and the flexibility and the variability of the device are reflected; the non-aromatic content of the benzene tower side line is reduced to be within 1.5wt% from 2.5wt%, the ethylbenzene content is reduced to be within 2.0wt% from 8.0wt%, and the loss of ethylbenzene is reduced by about 4 t/h.

Description

A kind of method for reducing benzene tower side line non-aromatic

technical field

The invention relates to the field of petrochemical production, in particular to a method for reducing the non-aromatic sideline of a benzene tower.

Background technique

Ethylbenzene is an aromatic organic compound, mainly used as an intermediate in the production of styrene in the petrochemical industry. The styrene produced is generally used to prepare polystyrene, a commonly used plastic product. Although small amounts of ethylbenzene are present in crude oil, large-scale production still relies on the acid-catalyzed reaction of benzene with ethylene. Ethylbenzene undergoes catalytic dehydrogenation to generate hydrogen and styrene. Ethylbenzene is also present in some pigments. The main problems of the currently operating catalytic dry gas to ethylbenzene system are that, on the one hand, the quality of the catalytic dry gas is poor, and the content of propylene and non-aromatic (total carbon 5) in the dry gas is relatively high. On the other hand, due to the limitations of the process , the catalytic dry gas is only washed with water, and directly enters the reactor without purification by the absorption device, so that the non-aromatic content in the reaction product is sent to the benzene tower, resulting in abnormal operation of the benzene tower. scope. The non-aromatic content and ethylbenzene content in the circulating benzene in the side line of the benzene tower greatly exceed the indicators, which increases the energy and material consumption of the device. At the same time, the circulating benzene enters the alkylation reaction system and the transalkylation reaction system, which affects the conversion rate and selection of the reaction. and the by-products increase, especially xylene, which directly affects the quality of ethylbenzene.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for reducing the non-aromatic side of the benzene tower in order to solve the defects existing in the prior art.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A kind of method that reduces benzene tower side line non-aromatic, comprises the steps:

a. Carry out piping to the coarse fractionation tower on the pipeline behind the gas-phase bypass regulating valve at the top of the benzene tower, close the gas-phase bypass to the reflux tank of the benzene tower, and adjust the gas-phase bypass to the coarse fractionating tower through the regulating valve;

b. Carry out piping to the crude toluene tank on the outlet pipeline of the reflux pump of the crude fractionation tower, and send the non-aromatic benzene to the crude toluene tank by the reflux pump, and the reflux volume of the crude fractionation tower is lowered;

c. The crude toluene tank is pumped to the aromatic hydrocarbon unit for re-refining, non-aromatic is removed, benzene is recovered to the benzene tank, and is returned to the device as fresh benzene for continued use.

Further, in the step a, the valve position of the regulating valve on the gas-phase bypass sent to the coarse fractionation tower is controlled to be no more than 15.

Further, in the step b, the reflux volume of the coarse fractionation tower is controlled at 16-20t/h.

Further, in described step c, in the process of back refining, remove non-aromatic, separate out benzene, and then reclaim benzene to benzene tank.

The beneficial effects of the invention are as follows: (1) According to the content of non-aromatic (total carbon five) in the catalytic dry gas sample analysis, the amount of non-aromatic extracted to the crude toluene tank can be adjusted at any time, and the stable operation of the benzene tower is always ensured. The flexibility of the device. ②The non-aromatic content in the side line of the benzene tower decreased from 2.5wt% to within 1.5wt%, and the ethylbenzene content decreased from 8.0wt% to within 2.0wt%, reducing the loss of ethylbenzene by about 4t/h.

Description of drawings

FIG. 1 is a schematic structural diagram of the present invention.

Detailed ways

As shown in Figure 1, a kind of method that reduces benzene tower side line non-aromatic, comprises the steps:

a. Carry out piping to the coarse fractionation tower on the pipeline behind the gas-phase bypass regulating valve at the top of the benzene tower, close the gas-phase bypass to the reflux tank of the benzene tower, and adjust the gas-phase bypass to the coarse fractionating tower through the regulating valve;

b. Carry out piping to the crude toluene tank on the outlet line of the reflux pump of the crude fractionation tower, and send the non-aromatic benzene to the crude toluene tank by the reflux pump, and the reflux volume of the crude fractionation tower is lowered;

c. The crude toluene tank is pumped to the aromatic hydrocarbon unit for re-refining, non-aromatic is removed, benzene is recovered to the benzene tank, and is returned to the device as fresh benzene for continued use.

Further, in step a, the valve position of the regulating valve on the gas-phase bypass sent to the coarse fractionation tower is controlled to be no more than 15; in step b, the return flow of the coarse fractionation tower is controlled at 16-20t/h; In the process, non-aromatics are removed, benzene is separated, and benzene is recovered to the benzene tank.

Using this process, the amount of non-aromatic extracted to the crude toluene tank can be adjusted at any time according to the content of non-aromatic (total carbon 5) in the catalytic dry gas sample analysis, and the stable operation of the benzene tower can always be ensured, reflecting the flexibility of the device. . The non-aromatic content in the side line of the benzene tower decreased from 2.5wt% to within 1.5wt%, and the ethylbenzene content decreased from 8.0wt% to within 2.0wt%, reducing the loss of ethylbenzene by about 4t/h.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions describe only the principles of the present invention. Without departing from the spirit and scope of the present invention, there will be various Variations and improvements are intended to fall within the scope of the claimed invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims (4)

1. A method for reducing non-aromatic hydrocarbon in a benzene tower side line is characterized by comprising the following steps:

a. piping to a rough separation tower on a pipeline behind a gas-phase bypass adjusting valve at the top of the benzene tower, closing the gas-phase bypass to a benzene tower reflux tank, and adjusting the gas-phase bypass to be sent to the rough separation tower through the adjusting valve;

b. piping to a crude toluene tank on an outlet pipeline of a reflux pump of the crude separation tower, sending benzene carrying non-aromatic hydrocarbon to the crude toluene tank through a reflux pump, and reducing the reflux amount of the crude separation tower;

c. and the crude toluene tank is pumped to an aromatic hydrocarbon unit for recycling, non-aromatic hydrocarbons are removed, benzene is recovered to a benzene tank and is returned to the device as fresh benzene for continuous use.

2. The method for reducing the non-aromatic hydrocarbon in the side stream of the benzene tower as claimed in claim 1, wherein in the step a, the valve positions of the adjusting valves on the gas phase side stream sent to the rough separation tower are controlled to be not more than 15.

3. The method for reducing the non-aromatic hydrocarbon in the benzene tower side line is characterized in that the reflux quantity of the rough separation tower in the step b is controlled to be 16-20 t/h.

4. The method for reducing non-aromatics in the side line of the benzene tower as claimed in claim 1, wherein in the step c, non-aromatics are removed in the remill process, benzene is separated, and then the benzene is recycled to the benzene tank.

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