CN111996027A - A kind of method and device for separating Fischer-Tropsch synthetic heavy oil by using next-door tower - Google Patents

Abstract

The invention relates to a method and a device for separating Fischer-Tropsch synthetic heavy oil by using a dividing wall column. The method adopts the dividing wall column technology to cut the Fischer-Tropsch synthetic heavy oil in sections to obtain C10-C14 fraction products respectively; tower and two single towers, the specific process is: the Fischer-Tropsch synthesis heavy oil feedstock enters the T1 dividing wall column, the ≤C10 fraction is produced at the top of the T1 dividing wall column, the ≤C10 fraction enters the T2 separation column, and the T2 separation column top is produced ≤ C9 fraction, T2 separation tower still produces C10 fraction; T1 dividing wall tower still produces ≥C14 components, ≥C14 components enter T4 separation tower, T4 separation tower top produces C14 fraction, T4 separation tower still produces ≥C15 components; C11~C13 fractions are extracted from the side line of the main tower of the T1 dividing wall column and enter the T3 dividing wall column; The C13 fraction is produced from the tower kettle of the next wall. The invention can utilize the dividing wall column technology to reduce the equipment investment and energy consumption of the process, and obtain C10-C14 fractions with different carbon numbers.

Description

A kind of method and device for separating Fischer-Tropsch synthetic heavy oil by using next-door tower

technical field

The invention relates to a method and a device for upgrading and processing heavy oil produced by a stripping tower of a Fischer-Tropsch synthesis unit by using a partition tower, and separating and obtaining fractional products of various carbon numbers.

Background technique

In Fischer-Tropsch synthesis (indirect coal liquefaction), the synthesis gas (CO, H ₂ ) produced by coal gasification is converted into gasoline, diesel and other hydrocarbon products under catalytic reaction. The crude products of the reaction are mainly light oil, heavy oil and heavy wax, which can be used as raw materials for the production of gasoline, diesel oil, naphtha and other products. There are also α-olefin components with higher added value, which need to be added. Separation and purification after hydrogen treatment. The main products in Fischer-Tropsch synthetic heavy oil are C7-C26 hydrocarbons and trace oxygenates. Among them, the hydrocarbons mainly include n-alkanes and some iso-alkanes. If the substances in the Fischer-Tropsch synthesis products can be further divided/separated and used to produce high value-added products such as solvent oil, the economic benefits will be improved.

Patent CN107325838A proposes a separation process of crude Fischer-Tropsch synthesis products, which includes multiple process steps of crude product separation, oil hydrogenation, alkane refining, solvent oil refining, wax hydrogenation, and wax refining. The non-condensable gas and the fraction above C18 used to produce LPG products are removed, and then separated by hydrogenation to obtain C8, C9-C10, C10-C11, C12, C13, C14-C15, C16-C18 and other components.

Patent CN205556567U proposes a stable light hydrocarbon separation process, which includes multiple process steps such as a light and heavy cutting tower, a light fraction rectification system, and a heavy fraction rectification system to obtain high-purity solvent oil and alkane products. First, the C5-C11 n-paraffin and isoparaffin raw materials are sent to the light and heavy cutting tower, after separation, the light and heavy components are obtained in the light and heavy cutting tower, and then enter 2 to 7 interconnected light components rectification towers, and the tower still obtains the heavy components Enter the heavy fraction rectification system. The heavy fraction rectification system includes 2 to 4 rectification towers to separate the heavy fraction into high-purity alkane products and solvent oil. CN105647575A is similar to the process of the above-mentioned patent.

Patent CN104910960A proposes a method for producing n-paraffin solvent oil from Fischer-Tropsch synthetic oil, including process steps such as fractionating tower, hydrorefining, degassing tower, and splitting tower system, using low-temperature Fischer-Tropsch synthetic light oil as raw material, After the split tower system composed of 8 rectification towers, components such as C5, C6, C7, C8, C9, C10, C9~C10, C11~C13, C14~C17, C17+ are obtained.

Among the above-mentioned patents, CN107325838A, CN104910960A, and CN205556567U all use single-column separation, which generally has the defects of complicated process, high energy consumption and equipment cost.

The invention provides an efficient and energy-saving method and device for upgrading and processing the heavy oil from a stripper of a Fischer-Tropsch synthesis unit, and using a partition column to separate and obtain segmented products of various carbon numbers.

SUMMARY OF THE INVENTION

The object of the present invention is to solve the above-mentioned defects of the prior art, and propose a method and device for separating Fischer-Tropsch synthetic heavy oil by utilizing a partition tower, which is a method for producing solvent oil by utilizing Fischer-Tropsch synthetic heavy oil with high efficiency and energy saving. In the actual production of the Fischer-Tropsch synthetic oil raw material composition, the use of the dividing wall column technology reduces the equipment investment and energy consumption of the process, and obtains C10-C14 fractions with different carbon numbers.

The present invention utilizes the method for separating the Fischer-Tropsch synthetic heavy oil by using the dividing wall column, adopts the dividing wall column technology to carry out segmental cutting of the Fischer-Tropsch synthetic heavy oil, and obtains C10-C14 fraction products respectively;

Using two partition towers and two single towers, the specific process is:

The Fischer-Tropsch synthesis heavy oil raw material (S01) enters the T1 partition tower, and the ≤C10 fraction (S02) is extracted from the top of the T1 partition tower, and the ≤C10 fraction (S02) enters the T2 separation tower, and the ≤C9 fraction is extracted from the top of the T2 separation tower. (S05), T2 separation tower tower still produces C10 cut (S06);

The ≥C14 component (S04) is produced from the T1 partition wall tower kettle, the ≥C14 component (S04) enters the T4 separation tower, the C14 fraction (S10) is produced from the top of the T4 separation tower, and the ≥C15 group is produced from the T4 separation tower tower kettle. points (S11);

The C11-C13 fractions (S03) are extracted from the main column side line of the T1 bulkhead tower and enter the T3 bulkhead tower; the C11 fraction (S07) is produced from the top of the T3 bulkhead tower, and the C12 fraction is produced from the main column side line of the T3 bulkhead tower (S08 ), the C13 fraction is extracted from the T3 next-wall tower still (S09).

Preferably, the number of theoretical plates in the pre-separation section (a in Figure 2) of the T1 dividing wall column is 10 to 100, the number of theoretical plates in the main column (b in Figure 2) is 10 to 100, and the number of theoretical plates in the common distillation section (in Figure 2) is 10 to 100. c) The number of theoretical plates is 10 to 100, the number of theoretical plates in the common stripping section (d in Figure 2) is 10 to 100, and the distribution ratio of the liquid phase (the ratio of the flow of the pre-separation section to the flow of the main column) is 0.1 to 100. 10. The gas phase distribution ratio is 0.1 to 10, the reflux ratio is 0.1 to 200, and the operating pressure is 0.05 to 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 theoretical plate number of the pre-separation section (a in Figure 2) of the T3 dividing wall column is 10 to 100, the theoretical plate number of the main column section (b in Figure 2) is 10 to 100, and the common rectification section (c in Figure 2) Theoretical plate number The number of plates is 10-100, the number of theoretical plates in the common stripping section (d in Figure 2) is 10-100, the distribution ratio of liquid phase is 0.1-10, the distribution ratio of gas phase is 0.1-10, and the reflux ratio is 0.1-200 , the operating pressure is 0.05 ~ 5bar;

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 this application, each stage of the separation of the materials requires that the yield and mass concentration of each carbon number product of the products C10-C14 are above 99%; the Fischer-Tropsch synthetic heavy oil raw material is a material containing C7-C26 components . In this application, each carbon segment product of C10 to C14 is separated separately. Included in each C _n are normal paraffins NC _n and isoparaffins IC _n .

The device for separating the Fischer-Tropsch synthetic heavy oil by using the next-wall column in the present invention mainly includes two bulkhead rectification columns and two common rectification columns. The tower top of the next-wall rectifying column is also the feed port of a common rectifying tower connected to the common rectifying section, and the tower still of the next-wall rectifying tower is also the feed port that the common stripping section is connected to another common rectifying tower; The outlet of the main column section of the bulkhead rectification column is connected to another bulkhead rectification column; each of the above-mentioned columns is provided with a condenser at the top of the column for condensing and reflux, and the column stills are all provided with a reboiler.

Compared with the prior art, the beneficial effects of the present invention are:

The method and device of the present invention can realize the production of solvent oil from Fischer-Tropsch synthetic heavy oil, apply the partition column technology to the upgrading of heavy oil, and can reduce energy consumption by about 30% compared with the traditional conventional distillation column sequence, Compared with the conventional single column, it can reduce the column body, reboiler, condenser and other auxiliary equipment, which can reduce the equipment investment. Therefore, applying the next-wall column rectification technology to this stage is highly efficient and energy-saving, which can reduce equipment investment and energy consumption, improve economic benefits, and improve industrial competitiveness.

This application selects the Fischer-Tropsch synthetic heavy oil from a certain factory as the raw material, the raw material composition is C7-C26, and does not use all the partition towers, but adopts the separation and energy-saving process of single tower + partition tower. These raw materials are initially divided through a dividing wall column to obtain three streams of column top (≤C10), side stream (C11-C13) and column bottom (≥C14). After the initial division, the subsequent separation of the top (≤C10) and column bottom (≥C14) streams uses a single column to separate the two streams. For the side-line (C11-C13) stream, another dividing wall column is used for splitting. According to the composition of Fischer-Tropsch synthetic oil raw materials in actual production, the dividing wall column technology is used to reduce the equipment investment and energy consumption of the process, and a single different carbon of C10-C14 can be obtained. number of fractions.

The present application is used to separate heavy oil, and the use of a dividing wall column is to obtain purer intermediate components on the basis of ensuring the purity of light and heavy components. The use of suitable partition towers within the scope of application can reduce operating energy consumption and equipment investment, but if it is not suitable, energy consumption may increase instead.

Description of drawings

Figure 1 is a schematic diagram of the separation flow of the dividing wall column and the separation column.

Figure 2 is a schematic diagram of the structure of the partition tower.

T1-the next wall column, T2-the separation column, T3-the next wall column, T4-the separation column.

S01-Fischer-Tropsch synthetic heavy oil feedstock, S02-≤C10 fraction (fraction lighter than C11), S03-C11～C13 fraction, S04-≥C14 fraction (fraction heavier than C13), S05-≤ C9 fractions (fractions lighter than C10), S06-C10 fractions, S07-C11 fractions, S08-C12 fractions, S09-C13 fractions, S10-C14 fractions, S11-≥C15 fractions (groups heavier than C14 Minute).

Detailed ways

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

The Fischer-Tropsch synthetic heavy oil raw material (S01) adopted in the present invention mainly comprises hydrocarbons of C7-C26 and trace oxygen-containing compounds, which are the main products in the Fischer-Tropsch synthetic heavy oil. Among them, the hydrocarbons mainly include n-alkanes and some iso-alkanes.

Example 1

The present invention is used for the cutting process of Fischer-Tropsch synthetic heavy oil, as shown in Fig. 1, including dividing wall column (T1, T3), separation column (T2, T4), condenser, reboiler, pump and related feeds. feed lines and lines connecting the above equipment. The raw material is Fischer-Tropsch synthetic heavy oil with a processing capacity of 6000kg, including hydrocarbons with carbon numbers ranging from C7 to C26 and trace oxygenates. The hydrocarbons in the treated Fischer-Tropsch synthetic heavy oil mainly include n-paraffins and some isoparaffins. The ingredients are as follows in Table 1:

NCn-n-paraffin; ICn-isoparaffin.

Table 1. Fischer-Tropsch synthetic heavy oil composition table

The number of theoretical plates in the pre-separation section (a in Figure 2) of the T1 dividing wall column is 100, the number of theoretical plates in the main column section (b in Figure 2) is 100, and the number of theoretical plates in the common rectifying section (c in Figure 2) is 10. The number of theoretical plates in the common 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 5bar;

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

The number of theoretical plates in the pre-separation section (a in Figure 2) of the T3 dividing wall column is 10, the number of theoretical plates in the main column section (b in Figure 2) is 10, and the number of theoretical plates in the common rectifying section (c in Figure 2) is 100, the number of theoretical plates in the 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 0.05bar;

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

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

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

Example 2

The same raw material treated is 6000kg Fischer-Tropsch synthetic heavy oil, which contains hydrocarbons with carbon numbers ranging from C7 to C26 and trace oxygenates. Among them, the hydrocarbons mainly include n-alkanes and some iso-alkanes. Among them, the optimal parameters are selected as follows: the number of theoretical plates in the pre-separation section (a in Figure 2) of the T1 dividing wall column is 30, the number of theoretical plates in the main column section (b in Figure 2) is 30, and the number of theoretical plates in the common rectifying section (Figure 2) is 30. In the middle c) the number of theoretical plates is 20, the number of theoretical plates in the common stripping section (d in Figure 2) is 20, the distribution ratio of liquid phase is 0.56, the distribution ratio of gas phase 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 is 30, the number of theoretical plates in the public rectification section (c in Figure 2) is 20, the number of theoretical plates in the common stripping section (d in Figure 2) is 20, the distribution ratio of the liquid phase is 0.49, and the distribution of the gas phase is 0.49. The ratio is 1, the reflux ratio is 11.9, and the operating pressure is 0.2 bar; the theoretical plate number of the T4 separation column is 30, the reflux ratio is 14.2, and the operating pressure is 0.2 bar.

≤C9 fraction (S05) product has a purity of 81.8% C9, a C10 fraction (S06) product has a purity of 99%, a C11 fraction (S07) product has a purity of 99.1%, and a C12 fraction (S08) product has a purity of 99%, The purity of the C13 fraction (S09) product is 99.2%, the purity of the C14 fraction (S10) product is 99%, and the C15 purity of the ≥C15 fraction (S11) product is 77.5%.

The yield of ≤C9 fraction (S05) product is 95.8%, the yield of C10 fraction (S06) product is 99.7%, the yield of C11 fraction (S07) product is 99.5%, and the yield of C12 fraction (S08) product is 99.5%. is 99%, the yield of C13 fraction (S09) product is 99%, the yield of C14 fraction (S10) product is 99%, and the C15 yield of ≥C15 fraction (S11) product is 98.9%.

The conventional single tower sequence requires 6 single towers to separate C10 to C14 products, and the product yield and concentration are both 99%. Among them, four single towers are equivalent to two partition towers. When the same separation index is achieved, the energy consumption is as shown in Table 2:

Table 2. Conventional Single Tower Sequence Energy Consumption

Table 3. Energy Consumption of Double Wall Column Sequence

Compared with the traditional single-column sequence, the double-partition-wall column sequence reduces the heat load of the reboiler by 22% and the heat load of the condenser by 14% when the same separation requirement is achieved. It can also reduce the investment in equipment such as tower body, reboiler and condenser. Therefore, the process of treating Fischer-Tropsch synthetic heavy oil is efficient and energy-saving, and can improve economic benefits.

What is not described in the present invention applies to the prior art.

Claims (6)

1. a method for separating the Fischer-Tropsch synthetic heavy oil utilizing the bulkhead tower, is characterized in that, the method adopts the bulkhead tower technology to carry out segmental cutting to the Fischer-Tropsch synthetic heavy oil, obtains C10～C14 cut product respectively; Using two partition towers and two single towers, the specific process is: The Fischer-Tropsch synthesis heavy oil raw material (S01) enters the T1 partition tower, and the ≤C10 fraction (S02) is extracted from the top of the T1 partition tower, and the ≤C10 fraction (S02) enters the T2 separation tower, and the ≤C9 fraction is extracted from the top of the T2 separation tower. (S05), T2 separation tower tower still produces C10 cut (S06); The ≥C14 component (S04) is produced from the T1 partition wall tower kettle, the ≥C14 component (S04) enters the T4 separation tower, the C14 fraction (S10) is produced from the top of the T4 separation tower, and the ≥C15 group is produced from the T4 separation tower tower kettle. points (S11); The C11-C13 fractions (S03) are extracted from the main column side line of the T1 bulkhead tower and enter the T3 bulkhead tower; the C11 fraction (S07) is produced from the top of the T3 bulkhead tower, and the C12 fraction is produced from the main column side line of the T3 bulkhead tower (S08 ), the C13 fraction is extracted from the T3 next-wall tower still (S09). 2. method according to claim 1 is characterized in that, the theoretical plate number of the pre-separation section of T1 partition wall column is 10～100, the theoretical column number of main tower section is 10～100, and the theoretical plate number of public rectifying section is 10～100. is 10-100, the theoretical plate number of the 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 0.05-5bar; 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 theoretical plate number of the pre-separation section of the T3 dividing wall column is 10-100, the theoretical plate number of the main column section is 10-100, the theoretical plate number of the common rectifying section is 10-100, and the theoretical plate number of the 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 0.05~5bar; 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. 3 . The method according to claim 1 , wherein each stage of material separation requires that the yield and mass concentration of each carbon number product of C10 to C14 be at least 99%. 4 . 4. The method according to claim 1, wherein the Fischer-Tropsch synthetic heavy oil feedstock mainly comprises hydrocarbons with a carbon number range of C7～C26 and a trace amount of oxygen-containing compounds, and the hydrocarbons mainly include n-paraffins, Also includes some isoparaffins. 5 . The method according to claim 1 , wherein the Fischer-Tropsch synthetic heavy oil feedstock is subjected to hydrogenation pretreatment before entering the partition wall column. 6 . 6. a device for separating Fischer-Tropsch synthetic heavy oil utilizing next-wall column, is characterized in that, this device mainly comprises two bulkhead rectifying towers and two rectifying columns, and Fischer-Tropsch synthetic heavy oil raw material is rectified by a bulkhead The pre-separation section of the tower enters, the top of the next-wall rectifying column is the common rectifying section connected to the feed port of a rectifying column, and the tower still of the next-wall rectifying column is the common stripping section connected to another rectifying section. The feed port of the tower; the outlet of the main column section of the next-wall rectification tower is connected to another next-to-wall rectification tower; each of the above-mentioned towers is provided with a condenser at the top of the tower for condensation and reflux, and the tower stills are all provided with a reboiler.

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