CN104232151A - Catalytic reforming method of naphtha - Google Patents

Abstract

The invention discloses a catalytic reforming method of naphtha. Naphtha is introduced into three or four reforming reactors which are connected with one another in series and are filled with a reforming catalyst; and reforming circulating hydrogen is introduced into the second reactor, or is divided into a plurality of strands, and is respectively introduced into the second reactor and various reactors on the downstream. According to the method, the reforming circulating hydrogen is not introduced into the first reactor, so that the total amount of carbon deposit of the catalyst can be reduced, the service life of the catalyst is prolonged, and the yield of a C5<+> liquid product is increased.

Description

A kind of naphtha catalytic reforming method

technical field

The invention is a hydrocarbon conversion method, in particular, a naphtha catalytic reforming method.

Background technique

The continuous catalytic reforming of naphtha has the characteristics of high liquid yield, high hydrogen production and high yield of aromatics. It has received great attention in the production of high-octane gasoline and aromatics, and will be used in the reforming process development process in the future. play a leading role in.

The continuous reformer includes a reaction unit and a catalyst regeneration unit. Different types of continuous reforming processes employ different types of catalyst regeneration units. At present, most continuous reforming units in the world use four reactors, and a small number of reforming units use three reactors. The process of the reaction unit of the conventional continuous reforming unit is generally as follows: after the refined naphtha from the reforming pre-hydrogenation unit enters the reforming unit, it is mixed with the reforming cycle hydrogen, and then enters the mixed feed heat exchanger to be mixed with the reaction product heat exchange. The material after heat exchange is heated to the reaction temperature by the first heating furnace and then enters the first reactor, and then passes through the second heating furnace, the second reactor, the third heating furnace, the third reactor, the fourth heating furnace, and the third heating furnace in sequence. Four reactors. The reaction product from the last reforming reactor exchanges heat with the feed in the mixed feed heat exchanger, then is cooled by the cooler and the oil in it is condensed and then enters the reformed product separation tank. The hydrogen-containing gas is separated from the top of the tank, part of which is used as circulating hydrogen, compressed by a compressor and mixed with raw materials, and then returned to the first reactor, and the other part is sent out to the device directly or after enrichment as a hydrogen product.

CN101921610A discloses a method for catalytic reforming of gasoline, comprising a moving bed catalytic reforming unit and a catalyst regeneration section using three or four reactors connected in series. When three reactors are used, the effluent from the catalyst reduction zone of the regeneration unit is recycled to the top of the third reactor; when four reactors are used for the catalytic reforming unit, the hydrogen at the outlet of the reduction zone is recycled to the top of the third reactor and/or the top of the fourth reactor.

CN102277190A discloses a new catalytic reforming process. The method is used in a moving bed continuous reforming unit comprising four series moving bed reactors and a catalyst regeneration reduction zone. The gaseous effluent from the catalyst reduction step is partly recycled directly to the top of the first reactor, and the rest is recycled to the inlet of the mixed feed exchanger before the first reactor, and the gas from the reformate is recycled by a recycle hydrogen compressor. The hydrogen-containing gas from the liquid separator is fully or partially recycled to the top of the third and/or fourth reactor to increase the hydrogen/hydrocarbon ratio in subsequent reactors.

From the perspective of reforming reaction chemistry, the main reaction in the first reforming reactor is the dehydrogenation reaction of naphthenes, and most of the naphthenes complete the dehydrogenation reaction in it. Therefore, the temperature drop of the first reactor is large, and the average bed layer The temperature is low, the amount of self-produced hydrogen is large, and the carbon deposition of the catalyst is very low, generally below 2%. However, due to the small scale of the first reactor, the capacity expansion of old devices is often limited by the adhesion of the catalyst to the wall of the first reactor.

Contents of the invention

The purpose of the present invention is to provide a method for catalytic reforming of naphtha, which does not feed external hydrogen into the first reforming reactor, thereby reducing the total carbon deposition of the catalyst, prolonging the service life of the catalyst, and increasing the C5+ liquid product yield.

The method for catalytic reforming of naphtha provided by the present invention comprises feeding naphtha into three or four reforming reactors connected in series loaded with reforming catalysts, and feeding reforming reactors into the second reactor. Circulating hydrogen, or dividing the reformed and circulating hydrogen into multiple strands and passing them into the second reactor and downstream reactors respectively.

The method of the present invention does not introduce external hydrogen into the first reforming reactor, but introduces the reforming recycled hydrogen into the second reactor or respectively into each reactor downstream of the first reactor, which can increase the yield of reforming C ₅ ⁺ liquid rate, reduce the total carbon deposition of the catalyst, prolong the service life of the catalyst, increase the operating flexibility of the device, solve the problem of the first reactor catalyst sticking to the wall when the device expands, and at the same time reduce the pressure difference between the inlet and outlet of the reforming cycle hydrogen compressor The operating energy consumption is reduced.

Description of drawings

Fig. 1 is a schematic flow chart of the reforming method of the present invention.

Detailed ways

The process of the reaction unit of the conventional continuous reforming unit is usually: the hydrogen-containing gas separated from the top of the reformed product separator, part of it is used as circulating hydrogen, compressed by a compressor and mixed with the raw material, and then passed through the mixed feed heat exchanger, the first The heating furnace and the first reactor enter the reforming reaction system, and the other part is sent out to the device directly or after enrichment as a hydrogen product.

Due to the characteristics of the reforming reaction, from the first reactor to the subsequent reactor, the catalyst loading increases sequentially, the catalyst carbon deposit also increases during the reaction, and the average bed temperature increases. The method of the present invention improves the supply mode of the reforming cycle hydrogen, divides the reforming cycle hydrogen into one or more strands and enters the reforming reaction system from the second reactor or the second reactor and its downstream reactor respectively, even if the first The reactor operates without the introduction of external hydrogen and produces hydrogen by itself, which can also effectively reduce the total carbon deposition of the catalyst and help prolong the service life of the catalyst. In addition, the introduction of recycled hydrogen into the second reactor and its subsequent reactors can also reduce the gas flow into the first reactor, which can effectively solve the problem of the catalyst in the first reactor when the capacity expansion of the reformer needs to increase the feed amount. Sticking problem.

The reforming cycle hydrogen mentioned in the present invention refers to the hydrogen-containing gas that comes from the reforming gas-liquid separator and is compressed by the reforming cycle hydrogen compressor. The circulating hydrogen is heated by a heating furnace before being passed into the reactor, and is preferably mixed with the raw materials and then passed into the reactor.

In the present invention, the circulating hydrogen is not passed into the first reactor, but passed into the second reactor and subsequent reactors. Said circulating hydrogen can be divided into one or more strands.

When the circulating hydrogen is one stream, all the circulating hydrogen is passed into the second reactor.

When the circulating hydrogen is divided into multiple strands, they are passed into the second reactor and subsequent reactors respectively, and when entering the subsequent reactors, the circulating hydrogen can be respectively passed into the second reactor and each subsequent reactor, or the The recycled hydrogen is passed to the second reactor and to one of the subsequent reactors. The volume ratio of the circulating hydrogen entering the second reactor to the total circulating hydrogen entering the reactor is 0.4-0.9, preferably 0.5-0.8.

In the present invention, when the reformer adopts four reactors, and the circulating hydrogen is divided into multiple streams, it is preferable to feed the circulating hydrogen into the second reactor and the fourth reactor. The volume ratio of the circulating hydrogen entering the third and/or fourth reactor to the total circulating hydrogen entering the reactor is 0.1-0.6, preferably 0.2-0.5.

The reaction unit of the continuous reformer may have multiple reactors connected in series, preferably including three to four moving bed radial reactors connected in series. The arrangement of the plurality of reactors can be stacked one above the other or placed side by side. When four reactors are used, preferably two reactors are stacked up and down to form a group, and then two groups of reactors are placed side by side, and catalyst lifters are arranged between each group.

The catalytic reforming in the present invention is preferably a continuous reforming method, applicable to various types of continuous reforming devices using alumina or zeolite-containing alumina as a carrier and halogen-containing platinum-tin series catalysts.

The catalyst for continuous reforming includes a carrier and 0.01 to 2.0% by mass, preferably 0.1 to 1.0% by mass of platinum group metals, 0.01 to 5.0% by mass, preferably 0.1 to 2.0% by mass of tin and 0.1 to 5% by mass, preferably 0.1 to 3.0% by mass of halogen. In addition, the third and/or fourth metal component may also be contained, and the third and/or fourth metal component is preferably one or more of europium, cerium and titanium. The content of the third and/or fourth metal component in the catalyst is 0.01-5.0% by mass, preferably 0.1-2.0% by mass.

The platinum group metal in the catalyst is preferably platinum, the halogen is preferably chlorine, and the carrier is preferably alumina, more preferably γ-alumina.

The present invention will be described below in conjunction with the accompanying drawings. For the convenience of expression, the detailed flow of the regeneration system is not involved in the drawings.

In Figure 1, the refined naphtha from pipeline 1 enters the first reforming reactor 6 through the mixed feed heat exchanger 2, pipeline 3, reforming first heating furnace 4 and pipeline 5, and contacts with the reforming catalyst for reaction, the reaction product of the first reactor is discharged through the pipeline 7, mixed with the reforming cycle hydrogen from the pipeline 32, enters the reforming second heating furnace 8, enters the reforming second reactor 10 through the pipeline 9, and the second reaction After the reaction product of the reactor is discharged through the pipeline 11, it enters the third reforming heating furnace 12, and enters the third reforming reactor 14 through the pipeline 13, and the reaction product of the third reactor enters the reforming fourth heating furnace after being discharged through the pipeline 15. The furnace 33 enters the fourth reforming reactor 17 through the pipeline 16, and the reformed product from the fourth reactor enters the mixed feed heat exchanger 2 through the pipeline 18, and after exchanging heat with the refined naphtha from the pipeline 1, Enter the reforming gas-liquid separator 27 through the pipeline 22, the air cooler 23, the pipeline 24, the water cooler 25, and the pipeline 26. The gas-liquid phase is separated in the reforming gas-liquid separator 27, and part of the separated hydrogen-containing gas is sent to the downstream hydrogen recovery processing unit through the pipeline 28, and the other part enters the reforming cycle hydrogen compressor 20 through the pipeline 21 and is compressed. 19 into the reforming reactor. The liquid phase product separated by the reforming gas-liquid separator 27 is discharged through the pipeline 29 .

If the reforming cycle hydrogen enters the reactor in one stream, it will enter the second reforming furnace 8 through the pipeline 32 and then enter the second reforming reactor 10 . If the reforming circulating hydrogen is divided into multiple strands, the circulating hydrogen from the pipeline 19 can be divided into three strands, the first strand enters the reforming second heating furnace 8 through the pipeline 32, and then enters the reforming second reactor 10, and the second strand passes through the pipeline 30 enters the third reforming furnace 12, then enters the third reforming reactor 14, and the third strand enters the reforming fourth heating furnace 33 through the pipeline 31, and then enters the reforming fourth reactor 17.

The present invention is further illustrated by examples below, but the present invention is not limited thereto.

Example 1

When the method of the invention is adopted to carry out the continuous reforming reaction of naphtha, the circulating hydrogen from the outlet of the compressor of the continuous reforming device does not enter the first reactor, but all enters the second reactor. The continuous reforming catalyst RC011 produced by Hunan Jianchang Catalyst Co., Ltd. was used, which contained 0.28% by mass of Pt and 0.41% by mass of Sn, and the carrier was γ-alumina. The properties of the refined naphtha used are shown in Table 1, and the reaction conditions and results are shown in Table 2.

Example 2

Adopt the method of the present invention to carry out the naphtha continuous reforming reaction, the circulating hydrogen from the compressor outlet of the continuous reforming unit does not enter the first reactor, and is divided into two streams and enters the second reactor and the fourth reactor respectively, wherein 80% by volume The circulating hydrogen of 20% by volume enters the second reactor, and the circulating hydrogen of 20% by volume enters the fourth reactor. Catalyst used and naphtha are all the same as example 1, and reaction conditions and results are shown in Table 2.

Comparative example 1

The conventional continuous reforming process flow is adopted, that is, all the circulating hydrogen enters the reforming unit from the first reactor. Catalyst used and naphtha are all the same as example 1, and reaction conditions and results are shown in Table 2.

Comparative example 2

Adopting the process of the patent CN101921610A, the hydrogen gas at the outlet of the reduction zone (the flow rate is 3800Nm ³ /h) enters the fourth reactor after passing through the reforming mixed feed heat exchanger, and all the circulating hydrogen gas from the reforming circulating hydrogen compressor goes to the first reaction Device, catalyst used and naphtha are all the same as example 1, and reaction conditions and results are shown in Table 2.

Comparative example 3

Adopting the process of the patent CN102277190A, the hydrogen gas at the outlet of the reduction zone (the flow rate is 3800Nm ³ /h) enters the first reactor after passing through the reforming mixed feed heat exchanger, and all the circulating hydrogen gas from the reforming circulating hydrogen compressor goes to the fourth reaction Device, catalyst used and naphtha are all the same as example 1, and reaction conditions and results are shown in Table 2. Table 1

Table 2

*The hydrogen/hydrocarbon molar ratio is the ratio of the mass of hydrogen gas to the mass of reformed feed entering the reactor.

Claims (9)

1. a Benzin naphtha catalytic reforming method, comprise and pass into petroleum naphtha in contact each other three or four reforming reactors of filling reforming catalyst, reforming cycle hydrogen is passed in second reactor, or reforming cycle hydrogen is divided into multiply, pass into each reactor in the second reactor and downstream respectively.

2. in accordance with the method for claim 1, it is characterized in that described circulating hydrogen is from reformate gas-liquid separator.

3. in accordance with the method for claim 1, it is characterized in that described circulating hydrogen heats through process furnace before passing into reactor.

4., in accordance with the method for claim 1, when it is characterized in that described circulating hydrogen is divided into multiply, the circulating hydrogen entering the second reactor is 0.4 ~ 0.9 with the volume ratio of the whole recycle hydrogens entering reactor.

5. in accordance with the method for claim 1, it is characterized in that when employing four reactors, and when described circulating hydrogen is divided into multiply, the circulating hydrogen entering the 3rd and/or the 4th reactor is 0.1 ~ 0.6 with the volume ratio of the whole recycle hydrogens entering reactor.

6. in accordance with the method for claim 1, it is characterized in that, when employing four reactors, two reactor mounted on top being become one group, then two group reaction devices being placed side by side.

7. in accordance with the method for claim 1, it is characterized in that described catalytic reforming is continuous catalytic reforming method.

8. in accordance with the method for claim 7, it is characterized in that the catalyzer of CONTINUOUS REFORMER comprise carrier and the platinum metals of 0.01 ~ 2.0 quality % that is benchmark with butt carrier, the tin of 0.01 ~ 5.0 quality % and 0.1 ~ 5 quality % halogen.

9. in accordance with the method for claim 8, it is characterized in that described platinum metals is platinum, halogen is chlorine.