CN114479904B - Combined conversion reaction flow of methanol and light hydrocarbon components - Google Patents

Abstract

The invention relates to a combined conversion reaction process of methanol and light hydrocarbon components, which mainly solves the side effects caused by the reaction of methanol and light hydrocarbon components in the prior art under the same catalyst, the same reactor and the same operating conditions, such as the catalyst group Distribution issues, active center competition issues, catalyst hydrothermal deactivation issues, and uneven temperature distribution in the reaction bed can easily lead to low reaction efficiency. By using two parallel sets of tubular fixed-bed reactors, the invention feeds methanol and light hydrocarbon components separately, reacts independently, and performs countercurrent heat exchange. It can not only realize coupled utilization of heat, save energy, but also maintain the catalyst bed layer. The temperature is uniform, the catalyst is configured individually, and the respective reaction performance is improved, which solves the above problems well.

Description

A combined conversion reaction process of methanol and light hydrocarbon components

Technical field

The invention relates to the technical field of petrochemical production, and in particular to a combined conversion reaction process of methanol and light hydrocarbon components.

Background technique

The aromatic hydrocarbon raffinate, reformed top oil, hydrogenated light naphtha and other light hydrocarbon components (mainly C5-C7 saturated hydrocarbon components) produced by petrochemical enterprises have light components, high vapor pressure, and also It is rich in n-alkanes with low octane number. Its research method octane number is low and cannot be used to blend automotive gasoline. For enterprises without ethylene equipment, these light hydrocarbon components have no better outlet and can only be sold as cheap fuel. If these low-value light hydrocarbon components are processed and converted into higher-value isoparaffins and aromatic hydrocarbons, And it has become a high-octane vehicle oil blending component, which not only solves the problem of utilizing light hydrocarbon components, but also opens up a new way for the production of vehicle gasoline.

On the other hand, except for synthetic ammonia, methanol is the only chemical synthesized on a large scale by coal gasification and natural gas reforming. It has become the main product of coal chemical industry and natural gas chemical industry and the main route for clean utilization of coal. Methanol-to-olefins, methanol-to-gasoline, methanol-to-aromatics and methanol-to-dimethylether can effectively digest the excess production capacity of methanol and extend the industrial chain to the petrochemical industry. However, the investment in the construction of separate units is high and the risks are high, especially when crude oil prices When it continues to decline, its economics and competitiveness will be greatly constrained by the market prices of methanol and oil products.

Relying on existing refining equipment and public works, the company co-converts methanol and light hydrocarbon components to produce high-octane gasoline through a series of complex chemical reactions (cracking, polymerization, dehydrogenation, cyclization, aromatization, etc.) Components or aromatic chemical components can broaden the raw materials for the production of aromatic chemicals, improve gasoline quality, and achieve rational utilization of resources; in the existing co-conversion technology of methanol and light hydrocarbon components, the light hydrocarbon components and methanol utilize the same The acidic molecular sieve catalyst performs chemical reactions. On the one hand, the co-reaction of methanol and light hydrocarbon components provides the heat released by the conversion of methanol to the conversion of light hydrocarbon components, achieving heat coupling, which can reduce the total thermal effect of the system and save energy; on the other hand, The co-reaction of methanol and light hydrocarbon components can realize the organic combination of coal chemical industry, natural gas chemical industry and petrochemical industry. The reaction product can be used as a high-octane gasoline blending component or aromatic chemical raw material. However, in the existing conversion technology, methanol and light hydrocarbons When the components are mixed and fed in the same reactor, the same catalyst, and the same operating conditions (reaction temperature, reaction pressure, reaction space velocity), there are at least the following problems:

(1) Methanol conversion is a strongly exothermic reaction, and heat needs to be removed in time to maintain the reaction temperature, while light hydrocarbon component conversion is an endothermic reaction, and heat needs to be continuously added to maintain the reaction temperature. The methanol conversion amount and the light hydrocarbon conversion amount are inevitably Affected by the thermal balance, they restrict each other, making it difficult to achieve reasonable control of the feed ratio of the two components;

(2) The chemical reaction mechanisms and reaction processes of methanol conversion and light hydrocarbon component conversion are not exactly the same. In order to maintain their respective high reactivity and selectivity, both require active components and functional modification components in the catalyst. will be different, so there is a problem of catalyst compatibility;

(3) The chemical conversion of methanol at high temperatures will produce a large amount of water. The catalyst involves high temperature, high water vapor partial pressure and other environments, and there is a problem of hydrothermal deactivation. This requires the catalyst to have strong resistance to hydrothermal deactivation. The chemical transformation of light hydrocarbon components is a strong endothermic reaction, and no water is produced during the reaction;

(4) The reaction conditions for methanol conversion and light hydrocarbon component conversion are different due to different reaction mechanisms and reaction processes. It is obviously inappropriate to use the same operating conditions, and there is a problem of synergy of reaction conditions;

(5) When methanol and light hydrocarbon components are mixed into the same reactor and share the same type of active center, there will inevitably be competition issues that affect the reaction efficiency.

Contents of the invention

The technical problems to be solved by this invention are the negative effects caused by the same catalyst, the same reactor and the same operating conditions in the prior art, such as catalyst component compatibility problems, active center competition problems, catalyst hydrothermal deactivation problems and Uneven temperature distribution in the reaction bed can easily cause low reaction efficiency. A new joint conversion reaction process of methanol and light hydrocarbon components is provided. This process is used for the joint conversion of high methanol and light components to produce high-octane gasoline components or chemical aromatics components. It has the advantages of realizing thermal energy coupling, energy saving and consumption reduction, high selectivity of target products, and personalized configuration of catalysts. The advantages of extending catalyst life and uniform reaction bed temperature.

In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a combined conversion reaction process of methanol and light hydrocarbon components. The light hydrocarbon components (mainly referring to C5-C7 saturated hydrocarbons) and methanol are fed separately in two ways. The hydrocarbon component enters the light hydrocarbon buffer tank 2 from the light hydrocarbon feed line 1. The light hydrocarbon pump 3 pumps it out from the bottom of the light hydrocarbon buffer tank 2 and boosts the pressure. It undergoes heat exchange through the light hydrocarbon preheater 4 tube side and enters the light hydrocarbon. After the heating furnace 5 is heated to the required temperature, it enters from one end of the tube side of the light hydrocarbon converter 7. After a chemical reaction occurs, it exits from the other end of the tube side of the light hydrocarbon converter 7. The light hydrocarbon reaction product exits from one end of the shell of the methanol converter 6. Enter, and after heat exchange, exit from the other end of the methanol converter 6 shell; methanol enters the methanol buffer tank 10 from the methanol feed line 9, and is pumped out from the bottom of the methanol buffer tank 10 by the methanol pump 11 and boosted, and passes through the methanol preheater 12 tube passes are used for heat exchange. After entering the methanol heating furnace 13 and being heated to the required temperature, it enters from one end of the methanol converter 6 tube passes. After a chemical reaction occurs, it exits from the other end of the methanol converter 6 tube passes. The methanol reaction product is light It enters from one end of the shell of the hydrocarbon converter 7, and after heat exchange, comes out from the other end of the shell of the light hydrocarbon converter 7. It is mixed with the light hydrocarbon reaction products from the shell side of the methanol converter 6 and then divided into two paths. One path enters the light hydrocarbons. The light hydrocarbon component in the preheater 4 shell heats the tube side, and the other channel enters the methanol preheater 12 shell to heat the methanol in the tube side. After heat exchange, the two channels are mixed and enter the subsequent dehydration and product separation processes.

In the above technical solution, preferably, the methanol converter 6 is a tubular fixed-bed reactor, and the methanol conversion catalyst is filled in the tube, and the light hydrocarbon reaction product is taken out of the tube; the light hydrocarbon converter 7 is a tubular fixed-bed reactor, and the methanol conversion catalyst is filled in the tube. The light hydrocarbon conversion catalyst is loaded, and the methanol reaction product is taken out of the tube.

In the above technical solution, preferably, two sets of methanol converter 6 and light hydrocarbon converter 7 are arranged in parallel, one on and one on standby. If the catalyst is coked and deactivated, regeneration can be switched and the operation can be switched between each other.

In the above technical solution, preferably, both the methanol converter 6 and the light hydrocarbon converter 7 use counter-current heat exchange.

In the above technical solution, preferably, the bed reaction temperature of the methanol converter is 350-450°C, and the bed reaction temperature of the light hydrocarbon converter is 350-450°C.

In the present invention, since methanol reacts in the methanol converter and light hydrocarbon components react in the light hydrocarbon converter, the reactions can be carried out separately and independently. According to the differences in the respective reaction mechanisms and reaction atmospheres, a more personalized catalyst configuration can be achieved, so that each It exerts high reactivity and high reaction selectivity to extend the catalyst life. At the same time, it adopts a tubular fixed-bed reactor. The reactor takes countercurrent heat. The heat generated by the reaction is coupled and utilized. The heat generated by methanol conversion can be taken away in time. It is used to supplement the heat required for the conversion of light hydrocarbon components, thereby keeping the temperature of the catalyst bed in each reactor relatively uniform from the inlet to the outlet, which is conducive to controlling the reaction to proceed at the optimal reaction temperature and avoiding excessive local temperature of the catalyst bed. High or local temperatures that are too low have achieved good technical results in improving the reaction activity of the catalyst and the yield of the target product.

Description of the drawings

Figure 1 is a schematic structural diagram of the process of the present invention.

In Figure 1: 1 is the light hydrocarbon feed line; 2 is the light hydrocarbon buffer tank; 3 is the light hydrocarbon pump; 4 is the light hydrocarbon preheater; 5 is the light hydrocarbon heating furnace; 6 is the methanol converter; 7 is the light hydrocarbon Converter; 8 is the reaction product discharge pipeline; 9 is the methanol feed line; 10 is the methanol buffer tank; 11 is the methanol pump; 12 is the methanol preheater; 13 is the methanol heating furnace; 141 is the outlet temperature of the light hydrocarbon heating furnace Display; 142 is the methanol heating furnace outlet temperature display; 143 is the methanol converter outlet temperature display; 144 is the light hydrocarbon converter outlet temperature display.

The present invention will be further described below through examples, but it is not limited to this example.

Detailed ways

【Example 1】

As shown in Figure 1, a joint conversion reaction process of methanol and light hydrocarbon components, methanol and light hydrocarbon components are fed separately, and the light hydrocarbon components from outside the boundary area (mainly referring to C5-C7 saturated hydrocarbons) are converted from light hydrocarbons The feed line 1 enters the light hydrocarbon buffer tank 2, and is boosted to 1.6MPa by the light hydrocarbon pump 3 before being sent out, together with the reaction products (mixed ) Heat the light hydrocarbon component through the light hydrocarbon preheater 4 (the light hydrocarbon component goes to the light hydrocarbon preheater 4 tube side), heat the light hydrocarbon component to about 200°C, and then enter the light hydrocarbon heating furnace 5 to be heated to 380-410°C left and right (observed through the light hydrocarbon heating furnace outlet temperature display 141), enters the light hydrocarbon converter 7 to perform a series of complex chemical reactions, and produces the light hydrocarbon reaction product (about 380°C) of the light hydrocarbon converter 7 through the light hydrocarbon converter outlet Temperature display 144 observes) The methanol reactants entering the shell side and tube side of the methanol converter 6 reverse heat exchange to maintain a uniform temperature along the axial direction of the methanol converter 6, and will not cause the catalyst in the methanol converter 6 to be damaged due to the strong exothermic effect of methanol conversion. Excessive temperature difference or local overheating occurs along the axial direction of the bed, and the reaction product after heat exchange is divided into two paths for further heat recovery.

Methanol (purity 95%) from outside the boundary area enters the methanol buffer tank 10 from the methanol feed line 9, is boosted to about 1.6MPa by the methanol pump 11, and is sent out, together with the other channels from the methanol converter 6 and the light hydrocarbon converter 7 The reaction product (mixed) with a temperature of about 400°C is preheated by the methanol preheater 12 (the methanol raw material goes through the methanol preheater 12 tube pass), the methanol is heated to about 200°C, and then enters the methanol heating furnace 13 for heating When the temperature reaches about 380-410°C (observed through the methanol heating furnace outlet temperature display 142), it enters the methanol converter 6 to perform a series of complex chemical reactions, and the methanol reaction product of the methanol converter 6 (about 380°C, through the outlet of the methanol converter Temperature display 143 (observation) The light hydrocarbon reactants entering the shell side and tube side of the light hydrocarbon converter 7 reversely exchange heat to maintain uniform temperature along the axial direction of the light hydrocarbon converter 7 without strong endothermic effects due to the conversion of light hydrocarbon components. As a result, the catalyst bed in the light hydrocarbon converter 7 has an excessively high temperature difference along the axial direction or is locally too low. The heat-exchanged methanol reaction product and the light hydrocarbon reaction product are mixed and divided into two paths, one of which is mixed with the light hydrocarbon component. The other channel exchanges heat with the methanol feed to achieve further heat recovery; after the two channels heat exchange, it is mixed and entered into subsequent processes for processing.

The methanol converter 6 is a tubular fixed-bed reactor, with methanol conversion catalysts filled in the tubes, and light hydrocarbon reaction products taken out of the tubes; the light hydrocarbon converter 7 is a tubular fixed-bed reactor, with light hydrocarbon conversion catalysts filled in the tubes. The methanol reaction product is removed from the tube.

The methanol converter 6 and the light hydrocarbon converter 7 are arranged in two groups in parallel, one is on and the other is on standby. If the catalyst is coked and deactivated, the regeneration can be switched and the operation can be switched between each other.

The methanol converter 6 and the light hydrocarbon converter 7 are both counter-current heat exchangers.

Obviously, by adopting the process of the present invention, two sets of parallel tubular fixed-bed reactors are used, methanol and light hydrocarbon components are fed separately, the reactions are carried out independently, and heat is exchanged in reverse direction, which can not only achieve coupled utilization of heat, save energy, but also It can maintain uniform temperature of the catalyst bed, implement personalized configuration of catalysts, and improve respective reaction performance.

Claims (3)

1. A combined conversion reaction process of methanol and light hydrocarbon components, used for the joint conversion of methanol and light hydrocarbon components to produce high-octane gasoline components or chemical aromatic hydrocarbon components. The light hydrocarbon components and methanol are separated into two separate paths. Feed, the light hydrocarbon component enters the light hydrocarbon buffer tank from the light hydrocarbon feed line, and is pumped out from the bottom of the light hydrocarbon buffer tank by a light hydrocarbon pump and boosted. It undergoes heat exchange through the tube side of the light hydrocarbon preheater and enters the light hydrocarbon for heating. After the furnace is heated to the required temperature, it enters from one end of the light hydrocarbon converter tube. After a chemical reaction occurs, it exits from the other end of the light hydrocarbon converter tube. The light hydrocarbon reaction product enters from one end of the methanol converter shell for heat exchange. Then it comes out from the other end of the methanol converter shell; methanol enters the methanol buffer tank from the methanol feed line, is extracted from the bottom of the methanol buffer tank by a methanol pump and boosted, undergoes heat exchange through the methanol preheater tube, and enters the methanol heating furnace After being heated to the required temperature, it enters from one end of the methanol converter tube, and after a chemical reaction occurs, it exits from the other end of the methanol converter tube. The methanol reaction product enters from one end of the light hydrocarbon converter shell, and after heat exchange, it exits from the light hydrocarbon converter. It comes out from the other end of the shell of the hydrocarbon converter and is mixed with the light hydrocarbon reaction products from the shell side of the methanol converter and then divided into two channels. One channel goes into the light hydrocarbon preheater shell to heat the light hydrocarbon components in the tube side, and the other channel goes into The shell of the methanol preheater heats the methanol in the tube side. After the heat exchange, the two paths are mixed and enter the subsequent dehydration and product separation processes; The methanol converter is a tubular fixed-bed reactor. The methanol conversion catalyst is filled in the tube, and the light hydrocarbon reaction products are taken out of the tube. The light hydrocarbon converter is a tubular fixed-bed reactor. The light hydrocarbon conversion catalyst is filled in the tube, and methanol is taken out of the tube. reaction product; Both the methanol converter and the light hydrocarbon converter use counter-current heat exchange; Among them, the light hydrocarbon components are C5-C7 saturated hydrocarbons. 2. The combined conversion reaction process of methanol and light hydrocarbon components according to claim 1, characterized in that two groups of methanol converters and light hydrocarbon converters are arranged in parallel, one is on and the other is on standby, and each other operates in switching mode. 3. The combined conversion reaction process of methanol and light hydrocarbon components according to claim 1, characterized in that the methanol converter bed reaction temperature is 350-450°C, and the light hydrocarbon converter bed reaction temperature is 350-450°C.