CN111996027A

CN111996027A - Method and device for separating Fischer-Tropsch synthesis heavy oil by using partition tower

Info

Publication number: CN111996027A
Application number: CN202010875445.XA
Authority: CN
Inventors: 李春利; 朱少雄; 王晨希; 段丛; 李�浩
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2020-08-27
Filing date: 2020-08-27
Publication date: 2020-11-27

Abstract

The invention relates to a method and a device for separating Fischer-Tropsch synthetic heavy oil by using a bulkhead tower, wherein the method adopts the bulkhead tower technology to cut the Fischer-Tropsch synthetic heavy oil in sections to respectively obtain C10-C14 fraction products; two partition wall towers and two single towers are adopted, and the specific flow is as follows: feeding the Fischer-Tropsch synthesis heavy oil raw material into a T1 bulkhead tower, extracting a fraction which is less than or equal to C10 from the top of the T1 bulkhead tower, feeding a fraction which is less than or equal to C10 into a T2 separation tower, extracting a fraction which is less than or equal to C9 from the top of a T2 separation tower, and extracting a fraction which is less than or equal to C10 from the bottom of a T2 separation tower; the tower kettle of the T1 bulkhead tower extracts components more than or equal to C14, components more than or equal to C14 enter a T4 separation tower, C14 fraction is extracted from the tower top of the T4 separation tower, and components more than or equal to C15 are extracted from the tower kettle of the T4 separation tower; C11-C13 fraction is taken out from the main column side line of the T1 dividing wall column and enters the T3 dividing wall column; the C11 fraction is taken out from the top of the T3 bulkhead column, the C12 fraction is taken out from the main column side line of the T3 bulkhead column, and the C13 fraction is taken out from the bottom of the T3 bulkhead column. The invention can reduce the equipment investment and energy consumption of the process by utilizing the dividing wall tower technology to obtain the fractions with different carbon numbers of C10-C14.

Description

Method and device for separating Fischer-Tropsch synthesis heavy oil by using partition tower

Technical Field

The invention relates to a method and a device for upgrading heavy oil produced by a Fischer-Tropsch synthesis unit stripping tower by using a partition tower and separating to obtain products of each carbon number fraction section.

Background

Synthesis gas (CO, H) from coal gasification in Fischer-Tropsch synthesis (coal indirect liquefaction)₂) Converted into gasoline, diesel oil and other hydrocarbon products in the catalytic reaction. The crude products of the reaction mainly comprise light oil, heavy oil and heavy wax, can be used as raw materials for producing products such as gasoline, diesel oil, naphtha and the like, and also comprise alpha-olefin components with higher additional values, and are separated and refined after being subjected to hydrotreating. The main products in the Fischer-Tropsch synthesis heavy oil are C7-C26 hydrocarbons and a trace amount of oxygen-containing compounds. The hydrocarbons mainly comprise normal paraffins and also comprise some isoparaffins. If the substances in the Fischer-Tropsch synthesis product can be further divided/separated to be used for producing high value-added products such as solvent oil, the economic benefit can be improved.

Patent CN107325838A proposes a separation process of a Fischer-Tropsch synthesis crude product, which comprises a plurality of process steps of product crude separation, oil hydrogenation, alkane refining, solvent oil refining, wax hydrogenation and wax refining. Removing non-condensable gas and fractions above C18 for producing LPG products, and then carrying out hydrogenation separation to obtain components such as C8, C9-C10, C10-C11, C12, C13, C14-C15, C16-C18 and the like.

Patent CN205556567U proposes a stable light hydrocarbon separation process, which comprises multiple process steps of a light and heavy cutting tower, a light component rectification system, a heavy component rectification system and the like, to obtain high-purity solvent oil and alkane products. Firstly, feeding C5-C11 normal paraffin and isoparaffin raw materials into a light and heavy cutting tower, separating to obtain light components in the light and heavy cutting tower, feeding the light components into 2-7 light component rectifying towers which are connected with each other, and feeding heavy components obtained in a tower kettle into a heavy component rectifying system. The heavy component rectification system comprises 2-4 rectification towers and is used for separating the heavy components into high-purity alkane products and solvent oil. CN105647575A is similar to the flow of the above patent.

Patent CN104910960A proposes a method for producing normal paraffin solvent oil from Fischer-Tropsch synthetic oil, which comprises the process steps of a fractionating tower, a hydrofining tower, a degassing tower, a dividing tower system and the like, wherein low-temperature Fischer-Tropsch synthetic light oil is adopted as a raw material, and the raw material passes through the dividing tower system consisting of 8 rectifying towers to obtain components such as C5, C6, C7, C8, C9, C10, C9-C10, C11-C13, C14-C17, C17 +.

In the above patents, CN107325838A, CN104910960A and CN205556567U all use single-tower separation, which generally has the defects of complex flow, high energy consumption and high equipment cost.

The invention provides a method and a device for efficiently and energy-saving upgrading of heavy oil from a Fischer-Tropsch synthesis unit stripping tower and separation of products in each carbon number fraction section by using a partition tower.

Disclosure of Invention

The invention aims to solve the defects of the prior art, provides a method and a device for separating Fischer-Tropsch synthesis heavy oil by using a dividing wall tower, is a method for producing solvent oil by using Fischer-Tropsch synthesis heavy oil in an efficient and energy-saving manner, and aims to reduce the equipment investment and energy consumption of the process by using the dividing wall tower technology aiming at the Fischer-Tropsch synthesis oil raw material composition in actual production to obtain fractions with different carbon numbers of C10-C14.

The invention relates to a method for separating Fischer-Tropsch synthesis heavy oil by using a bulkhead tower, which comprises the steps of cutting Fischer-Tropsch synthesis heavy oil by sections by adopting a bulkhead tower technology to respectively obtain C10-C14 fraction products;

two partition wall towers and two single towers are adopted, and the specific flow is as follows:

feeding a Fischer-Tropsch synthesis heavy oil raw material (S01) into a T1 dividing wall tower, extracting a fraction (S02) less than or equal to C10 from the top of the T1 dividing wall tower, feeding a fraction (S02) less than or equal to C10 into a T2 separation tower, extracting a fraction (S05) less than or equal to C9 from the top of the T2 separation tower, and extracting a fraction (S06) C10 from the bottom of the T2 separation tower;

more than or equal to C14 components (S04) are extracted from the tower bottom of a T1 bulkhead tower, more than or equal to C14 components (S04) enter a T4 separation tower, C14 fractions (S10) are extracted from the tower top of a T4 separation tower, and more than or equal to C15 components are extracted from the tower bottom of a T4 separation tower (S11);

C11-C13 fraction (S03) was taken from the main side of a T1 divided column and fed into a T3 divided column; a C11 fraction (S07) is taken from the top of the T3 dividing wall column, a C12 fraction (S08) is taken from the main column side line of the T3 dividing wall column, and a C13 fraction (S09) is taken from the bottom of the T3 dividing wall column.

Preferably, the number of theoretical plates of a pre-separation section (a in figure 2) of the T1 dividing wall tower is 10-100, the number of theoretical plates of a main tower section (b in figure 2) is 10-100, the number of theoretical plates of a common rectification section (c in figure 2) is 10-100, the number of theoretical plates of a common stripping section (d in figure 2) is 10-100, the liquid phase distribution ratio (the ratio of the flow of the pre-separation section to the flow of the main tower section) is 0.1-10, the gas phase distribution ratio is 0.1-10, the reflux ratio is 0.1-200, and the operating pressure is 0.05-5 bar;

the theoretical plate number of the T2 separation tower is 10-100, the reflux ratio is 0.1-20, and the operating pressure is 0.05-5 bar;

the number of theoretical plates of a pre-separation section (a in figure 2) of the T3 dividing wall tower is 10-100, the number of theoretical plates of a main tower section (b in figure 2) is 10-100, the number of theoretical plates of a common rectification section (c in figure 2) is 10-100, the number of theoretical plates of a common stripping section (d in figure 2) is 10-100, the liquid phase distribution ratio is 0.1-10, the gas phase distribution ratio is 0.1-10, the reflux ratio is 0.1-200, and the operating pressure is 0.05-5 bar;

the theoretical plate number of the T4 separation tower is 10-100, the reflux ratio is 0.1-20, and the operating pressure is 0.05-5 bar.

In the application, the yield and the mass concentration of each carbon number product of C10-C14 are required to be more than 99% at each stage of material separation; the Fischer-Tropsch synthesis heavy oil raw material is a material containing components of C7-C26. In the application, the carbon section products of C10-C14 are separated independently. Each C_nIncluding n-alkanes NC_nAnd isoparaffin IC_n。

The device for separating the Fischer-Tropsch synthesis heavy oil by utilizing the bulkhead tower mainly comprises two bulkhead rectifying towers and two common rectifying towers, wherein the Fischer-Tropsch synthesis heavy oil raw material enters from a pre-separation section of one bulkhead rectifying tower, the top of the bulkhead rectifying tower, namely a common rectifying section, is connected with a feed inlet of one common rectifying tower, and a tower kettle of the bulkhead rectifying tower, namely a common stripping section, is connected with a feed inlet of the other common rectifying tower; the outlet of the main tower section of the bulkhead rectifying tower is connected with the other bulkhead rectifying tower; the tower top of each tower is provided with a condenser for condensation and reflux, and the tower kettle is provided with a reboiler.

Compared with the prior art, the invention has the beneficial effects that:

the method and the device can realize the production of the solvent oil from the Fischer-Tropsch synthesis heavy oil, apply the bulkhead tower technology to the quality improvement of the heavy oil, reduce the energy consumption by about 30 percent compared with the conventional rectifying tower sequence, reduce the tower body, the reboiler, the condenser and other auxiliary equipment compared with the conventional single tower, and reduce the equipment investment. Therefore, the dividing wall tower rectification technology is applied to the stage, the efficiency and the energy conservation are realized, the equipment investment and the energy consumption can be reduced, the economic benefit can be improved, and the industrial competitiveness can be improved.

The Fischer-Tropsch synthesis heavy oil of a certain plant is selected as the raw material, the raw material composition is C7-C26, all the partition towers are not used, and the separation energy-saving process of the single tower and the partition towers is adopted. The raw materials are firstly primarily divided by a partition wall tower to obtain three streams of material flows including a tower top (less than or equal to C10), a side line (C11-C13) and a tower bottom (more than or equal to C14). After the initial division, the subsequent separation of the material flow at the top (C10 or less) and the bottom (C14) of the tower respectively adopts a single tower to separate the two material flows. And the side stream (C11-C13) is divided by another dividing wall tower, and aiming at the Fischer-Tropsch synthetic oil raw material composition in the actual production, the equipment investment and the energy consumption of the process are reduced by utilizing the dividing wall tower technology, so that the single fractions with different carbon numbers of C10-C14 are obtained.

The application is used for separating heavy oil, and purer intermediate components are obtained by using the dividing wall tower on the basis of ensuring the purity of light and heavy components. The use of a suitable dividing wall column within its scope of application allows to reduce the operating energy consumption and also to reduce the equipment investment, but the energy consumption may increase if not appropriate.

Drawings

FIG. 1 is a schematic diagram of a separation scheme of a dividing wall column and a separation column.

FIG. 2 is a schematic diagram of the structure of a divided wall column.

T1-dividing wall column, T2-separating column, T3-dividing wall column and T4-separating column.

S01-Fischer-Tropsch synthesis heavy oil raw material, S02-C10 fraction (lighter fraction than C11), S03-C11-C13 fraction, S04-C14 fraction (heavier fraction than C13), S05-C9 fraction (lighter fraction than C10), S06-C10 fraction, S07-C11 fraction, S08-C12 fraction, S09-C13 fraction, S10-C14 fraction, S11-C15 component (heavier component than C14).

Detailed Description

The method and apparatus provided by the present invention will be further described with reference to the following embodiments and the accompanying drawings, but the scope of the present invention is not limited to the embodiments.

The Fischer-Tropsch synthesis heavy oil raw material (S01) mainly comprises hydrocarbons with the main products of C7-C26 and a trace amount of oxygen-containing compounds in the Fischer-Tropsch synthesis heavy oil. The hydrocarbons mainly comprise normal paraffins and also comprise some isoparaffins.

Example 1

The invention is used for the cutting process of Fischer-Tropsch synthesis heavy oil, and comprises a dividing wall tower (T1, T3), a separation tower (T2, T4), a condenser, a reboiler, a pump, related feeding pipelines and pipelines for connecting the above devices, as shown in figure 1. The raw material is Fischer-Tropsch synthesis heavy oil, the treatment capacity is 6000kg, the raw material comprises hydrocarbons with the carbon number range of C7-C26 and a trace amount of oxygen-containing compounds, and the Fischer-Tropsch synthesis heavy oil raw material is subjected to hydrogenation pretreatment before entering a dividing wall tower. The hydrocarbons in the treated Fischer-Tropsch synthesis heavy oil mainly comprise normal paraffins and also comprise some isoparaffins. The ingredients are as follows in table 1:

NCn-normal alkanes; ICn-isoparaffin.

TABLE 1 Fischer-Tropsch Synthesis heavy oil composition Table

The theoretical plate number of a pre-separation section (a in figure 2) of a T1 dividing wall tower is 100, the theoretical plate number of a main tower section (b in figure 2) is 100, the theoretical plate number of a public rectification section (c in figure 2) is 10, the theoretical plate number of a public stripping section (d in figure 2) is 10, the liquid phase distribution ratio is 0.1, the gas phase distribution ratio is 0.1, the reflux ratio is 0.1, and the operating pressure is 5 bar;

the theoretical plate number of the T2 separation tower is 10, the reflux ratio is 20, and the operation pressure is 0.05 bar;

the number of theoretical plates of a pre-separation section (a in figure 2) of a T3 dividing wall column is 10, the number of theoretical plates of a main column section (b in figure 2) is 10, the number of theoretical plates of a common rectification section (c in figure 2) is 100, the number of theoretical plates of a common stripping section (d in figure 2) is 100, the liquid phase distribution ratio is 10, the gas phase distribution ratio is 10, the reflux ratio is 200, and the operating pressure is 0.05 bar;

the T4 separation column had a theoretical plate number of 100, a reflux ratio of 0.1 and an operating pressure of 5 bar.

The purity of the product of the C10 fraction (S06) was 99%, the purity of the product of the C11 fraction (S07) was 99.2%, the purity of the product of the C12 fraction (S08) was 99.1%, the purity of the product of the C13 fraction (S09) was 99.1%, and the purity of the product of the C14 fraction (S10) was 99%.

The yield of the product of the C10 fraction (S06) was 99.6%, the yield of the product of the C11 fraction (S07) was 99.6%, the yield of the product of the C12 fraction (S08) was 99.1%, the yield of the product of the C13 fraction (S09) was 99%, and the yield of the product of the C14 fraction (S10) was 99%.

Example 2

The same raw material is 6000kg of Fischer-Tropsch synthesis heavy oil which comprises hydrocarbons with the carbon number range of C7-C26 and a trace amount of oxygen-containing compounds. The hydrocarbons mainly comprise normal paraffins and also comprise some isoparaffins. The preferred parameters are: the theoretical plate number of a pre-separation section (a in figure 2) of a T1 dividing wall tower is 30, the theoretical plate number of a main tower section (b in figure 2) is 30, the theoretical plate number of a common rectification section (c in figure 2) is 20, the theoretical plate number of a common stripping section (d in figure 2) is 20, the liquid phase distribution ratio is 0.56, the gas phase distribution ratio is 1, the reflux ratio is 13.8, and the operating pressure is 0.2 bar; the theoretical plate number of the T2 separation tower is 30, the reflux ratio is 14.7, and the operating pressure is 0.2 bar; the number of theoretical plates of a pre-separation section (a in figure 2) of a T3 dividing wall column is 30, the number of theoretical plates of a main column section (b in figure 2) is 30, the number of theoretical plates of a common rectification section (c in figure 2) is 20, the number of theoretical plates of a common stripping section (d in figure 2) is 20, the liquid phase distribution ratio is 0.49, the gas phase distribution ratio is 1, the reflux ratio is 11.9, and the operating pressure is 0.2 bar; the T4 separation column had a theoretical plate number of 30, a reflux ratio of 14.2 and an operating pressure of 0.2 bar.

The purity of C9 of a product of the C9 fraction (S05) is not more than 81.8 percent, the purity of a product of the C10 fraction (S06) is 99 percent, the purity of a product of the C11 fraction (S07) is 99.1 percent, the purity of a product of the C12 fraction (S08) is 99 percent, the purity of a product of the C13 fraction (S09) is 99.2 percent, the purity of a product of the C14 fraction (S10) is 99 percent, and the purity of C15 of a product of C15 components (S11) is not less than 77.5 percent.

The yield of C9 of a C9 cut (S05) is less than or equal to 95.8 percent, the yield of a C10 cut (S06) product is 99.7 percent, the yield of a C11 cut (S07) product is 99.5 percent, the yield of a C12 cut (S08) product is 99 percent, the yield of a C13 cut (S09) product is 99 percent, the yield of a C14 cut (S10) product is 99 percent, and the yield of a C15 of a C15 cut (S11) product is more than or equal to 98.9 percent.

The conventional single-tower sequence needs 6 single towers to separate products C10-C14, the product yield and the product concentration are all 99%, wherein four single towers are equivalent to two partition towers, and the energy consumption is as follows in the following table 2 when the same separation index is achieved:

TABLE 2 conventional Single column sequence energy consumption

TABLE 3 sequence energy consumption of double dividing wall column

Compared with the traditional single column sequence, when the double-partition-wall column sequence meets the same separation requirement, the heat load of the reboiler is reduced by 22 percent, and the heat load of the condenser is reduced by 14 percent. And the equipment investment of a tower body, a reboiler, a condenser and the like can be reduced. Therefore, the process for treating the Fischer-Tropsch synthesis heavy oil is efficient and energy-saving, and can improve the economic benefit.

Nothing in this specification is said to apply to the prior art.

Claims

1. A method for separating Fischer-Tropsch synthetic heavy oil by using a dividing wall tower is characterized in that the method adopts the dividing wall tower technology to cut Fischer-Tropsch synthetic heavy oil in sections to respectively obtain C10-C14 fraction products;

2. The method as claimed in claim 1, wherein the number of theoretical plates of a pre-separation section of the T1 dividing wall column is 10-100, the number of theoretical plates of a main column section is 10-100, the number of theoretical plates of a common rectification section is 10-100, the number of theoretical plates of a common stripping section is 10-100, the distribution ratio of a liquid phase is 0.1-10, the distribution ratio of a gas phase is 0.1-10, the reflux ratio is 0.1-200, and the operating pressure is 0.05-5 bar;

the number of theoretical plates of a pre-separation section of the T3 dividing wall column is 10-100, the number of theoretical plates of a main column section is 10-100, the number of theoretical plates of a common rectification section is 10-100, the number of theoretical plates of a common stripping section is 10-100, the liquid phase distribution ratio is 0.1-10, the gas phase distribution ratio is 0.1-10, the reflux ratio is 0.1-200, and the operating pressure is 0.05-5 bar;

3. The method of claim 1, wherein the separation of the feedstock requires at least 99% yield and concentration by mass of C10-C14 per C number product.

4. The process of claim 1, wherein the fischer-tropsch synthesis heavy oil feedstock comprises predominantly hydrocarbons having a carbon number in the range of C7-C26, the hydrocarbons comprising predominantly normal paraffins and also some isoparaffins, and minor amounts of oxygenates.

5. The process of claim 1, wherein the fischer-tropsch synthesized heavy oil feedstock is subjected to a hydrotreating pretreatment prior to entering the divided wall column.

6. A device for separating Fischer-Tropsch synthetic heavy oil by utilizing a bulkhead tower is characterized by mainly comprising two bulkhead rectifying towers and two rectifying towers, wherein the Fischer-Tropsch synthetic heavy oil raw material enters from a pre-separation section of one bulkhead rectifying tower, the top of the bulkhead rectifying tower, namely a public rectifying section, is connected with a feed inlet of one rectifying tower, and a kettle of the bulkhead rectifying tower, namely a public stripping section, is connected with a feed inlet of the other rectifying tower; the outlet of the main tower section of the bulkhead rectifying tower is connected with the other bulkhead rectifying tower; the tower top of each tower is provided with a condenser for condensation and reflux, and the tower kettle is provided with a reboiler.