A method for producing saturated liquefied petroleum gas from naphtha through reforming and pre-hydrogenation.

Abstract

This invention relates to a method for producing saturated liquefied petroleum gas (LPG) from naphtha using reforming and pre-hydrogenation, comprising the following steps: Step 1: Naphtha containing LPG components undergoes an olefin saturation reaction under conditions of 1.6–3.5 MPa pressure, 270–340 °C temperature, and a catalyst containing a W-Mo-Ni system; Step 2: The naphtha after the olefin saturation reaction is fractionated to obtain sulfur-containing saturated LPG; Step 3: The sulfur-containing saturated LPG is cooled and then desulfurized under a liquid-phase desulfurizing agent at 0.8–1.2 MPa and room temperature to obtain saturated LPG that meets the quality requirements. This invention separates sulfur-containing saturated LPG from olefin-rich LPG, solving the problems of load occupancy in LPG processing equipment and repeated processing of saturated LPG components caused by sulfur-containing saturated LPG entering the olefin-rich LPG processing flow in the prior art.

Description

Technical Field

[0001] This invention relates to the field of liquefied petroleum gas (LPG) production technology, and in particular to a method for producing saturated LPG from naphtha using reforming and pre-hydrogenation. Background Technology

[0002] Reforming units are one of the important means of secondary refining. The raw materials processed are generally naphtha containing liquefied petroleum gas (LPG) components. After the naphtha containing LPG components undergoes reaction in the reforming pre-hydrogenation reaction system, the product enters the stripping tower for fractionation. The top of the stripping tower is divided into sulfur-containing saturated LPG and sulfur-containing dry gas. The sulfur-containing saturated LPG enters the olefin-rich LPG processing process, which results in the load occupation of the LPG processing unit and the repeated processing of saturated LPG components.

[0003] Therefore, we have implemented a method for producing saturated liquefied petroleum gas from naphtha through reforming and pre-hydrogenation. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention discloses a method for producing saturated liquefied petroleum gas from naphtha by reforming and pre-hydrogenation.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A method for producing saturated liquefied petroleum gas from naphtha through reforming and pre-hydrogenation includes the following steps:

[0007] Step 1: Naphtha containing liquefied petroleum gas components is subjected to olefin saturation reaction under the conditions of pressure 1.6-3.5 MPa, temperature 270-340℃ and catalyst containing W-Mo-Ni system.

[0008] Step 2: The naphtha after the olefin saturation reaction is fractionally distilled to obtain sulfur-containing saturated liquefied petroleum gas;

[0009] Step 3: After cooling the sulfur-containing saturated liquefied petroleum gas, desulfurize it in an environment with a liquid phase desulfurizing agent at a pressure of 0.8~1.2MPa and room temperature to obtain saturated liquefied petroleum gas that meets the quality requirements.

[0010] Preferably, in step two, the naphtha after the olefin saturation reaction is fractionated using a stripping tower at a pressure of 1.15-1.25 MPa and a temperature of 30-35 °C.

[0011] Preferably, in step three, the sulfur-containing saturated liquefied gas and liquid amine liquid are desulfurized by counter-current swirling through a desulfurization tower.

[0012] Preferably, the desulfurization tower is provided with a liquid phase inlet and a gas phase outlet at the top and a gas phase inlet and a liquid phase outlet at the bottom. The desulfurization tower is provided with multiple baffles at intervals from top to bottom, and the baffles are evenly provided with multiple through-flow swirling elements that enable the sulfur-containing saturated liquefied gas to come into counter-current swirling contact with the liquid amine liquid.

[0013] Preferably, the swirl element has a circular cross-section shell, and the shell is provided with multiple tangential inlets evenly arranged around its circumference at positions above and below the partition plate. The upper and lower end faces of the shell are provided with necks that communicate with them, and the necks are open at one end away from the shell.

[0014] Preferably, the open end of the neck of the cyclone element is located below the liquid surface of the liquid amine liquid in the inner cavity of the desulfurization tower.

[0015] Preferably, the tangential inlet at the upper end of the outer shell is in the opposite direction to the tangential inlet at the lower end.

[0016] Preferably, the upper and lower swirl elements are arranged alternately.

[0017] Preferably, in step one, naphtha containing liquefied gas components is subjected to an olefin saturation reaction under conditions of pressure 2.2–3.0 MPa, temperature 290–330 °C, and a catalyst.

[0018] By employing the technical solution described above, the present invention has the following beneficial effects:

[0019] 1. This invention separates sulfur-containing saturated liquefied petroleum gas (LPG) from olefin-rich LPG, solving the problems of load occupancy of LPG processing equipment and repeated processing of saturated LPG components caused by sulfur-containing saturated LPG entering the olefin-rich LPG processing flow in the prior art.

[0020] 2. Due to the design of the cyclone element, the liquid amine liquid and the sulfur-containing saturated liquefied gas can enter from the corresponding cyclone element inlet respectively, forming a gas-liquid relative swirling flow. With the neck setting, the liquid amine liquid and the sulfur-containing saturated liquefied gas must move to the corresponding neck. The liquid amine liquid in the lower section of the inner cavity of the cyclone element and the saturated liquefied gas in the upper section of the inner cavity of the cyclone element will be mixed, so that the two will come into contact and thus improve the sulfur removal function of the sulfur-containing saturated liquefied gas. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the desulfurization tower in this invention;

[0022] Figure 2 This is a schematic diagram of the swirl element in the present invention;

[0023] Figure 3 This is a front view of the swirl element in this invention. Detailed Implementation

[0024] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "rear", "left", "right" indicating the orientation or positional relationship, they are only corresponding to the drawings of this application for the convenience of describing the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation.

[0025] A method for producing saturated liquefied petroleum gas from naphtha through reforming and pre-hydrogenation includes the following steps:

[0026] Step 1: Naphtha containing liquefied petroleum gas components is subjected to olefin saturation reaction under the conditions of pressure 1.6-3.5 MPa, temperature 270-340℃ and catalyst containing W-Mo-Ni system.

[0027] Preferably, the pressure can be 2.2 to 3.0 MPa and the temperature can be 290 to 330°C.

[0028] Step 2: The naphtha after the olefin saturation reaction is fractionally distilled to obtain sulfur-containing saturated liquefied petroleum gas;

[0029] As needed, naphtha after olefin saturation reaction is fractionated using a stripping tower at a pressure of 1.15-1.25 MPa and a temperature of 30-35℃.

[0030] Step 3: After cooling the sulfur-containing saturated liquefied petroleum gas (LPG), desulfurize it in an environment of 0.8~1.2 MPa and room temperature with a liquid-phase desulfurizing agent to obtain saturated LPG that meets the quality requirements; preferably, naphtha after olefin saturation reaction is stripped in an environment of 0.8, 1.0 or 1.2 MPa and room temperature with a liquid-phase desulfurizing agent using a stripping tower.

[0031] Furthermore, the sulfur-containing saturated liquefied gas and the liquid amine liquid come into contact in the inner cavity of the desulfurization tower 1 through a counter-swirling flow, so as to facilitate the contact between the sulfur-containing saturated liquefied gas and the liquid amine liquid.

[0032] Specifically, the desulfurization tower 1 is provided with a liquid phase inlet and a gas phase outlet at the top and a gas phase inlet and a liquid phase outlet at the bottom. The desulfurization tower 1 is provided with multiple baffles 11 at intervals from top to bottom, and the baffles are evenly provided with multiple through-flow swirl elements 12 that can make the sulfur-containing saturated liquefied gas and the liquid phase amine liquid come into counter-swirling contact.

[0033] The cyclone element 12 has a circular outer shell 121. Multiple tangential inlets 122 are evenly arranged around the circumference of the outer shell 121, located above and below the partition plate 11. The upper and lower end faces of the outer shell 121 are provided with necks 123 that communicate with them. The necks 123 are open at one end away from the outer shell 121. Due to the arrangement of the cyclone element 12, the liquid amine liquid and the sulfur-containing saturated liquefied gas can enter from the corresponding inlets of the cyclone element 12, forming a gas-liquid relative swirling flow. With the necks 123, the liquid amine liquid and the sulfur-containing saturated liquefied gas must move to the corresponding necks 123. The liquid amine liquid is mixed in the lower section of the inner cavity of the cyclone element 12, and the saturated liquefied gas is mixed in the upper section of the inner cavity of the cyclone element 12, so that the two come into contact, thereby improving the function of removing sulfur from the sulfur-containing saturated liquefied gas.

[0034] Depending on the requirements, the outer shell 121 can be cylindrical or have a shape with a larger diameter in the middle section and smaller diameter at both ends.

[0035] As needed, the tangential inlet at the upper end of the outer shell is oriented in the opposite direction to the tangential inlet at the lower end. This arrangement allows the sulfur-containing saturated liquefied gas swirling upwards within the swirling element 12 to flow relative to the liquid amine liquid swirling downwards within the swirling element 12, achieving collision contact, and subsequently the two flow together.

[0036] As needed, the lower open end of the neck 123 in the cyclone element 12 is located below the liquid surface of the liquid amine liquid in the inner cavity of the desulfurization tower 1.

[0037] As needed, the upper swirl element 12 and the lower swirl element 12 are arranged alternately.

[0038] In the example, naphtha containing liquefied petroleum gas (LPG) components was subjected to olefin saturation reaction under pressures of 1.6 MPa, 2.0 MPa, 2.2 MPa, 2.8 MPa, 3.2 MPa, or 3.5 MPa, and temperatures of 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, or 340℃. The actual analytical data of the saturated LPG obtained after the statistical analysis are as follows:

[0039] (Propane + n-Butane) (volume fraction) % > 70%; Test method is SH / T 0230 c ;

[0040] (Total olefin hydrocarbon components) (volume fraction) % < 1%; Test method is SH / T 0230 c ;

[0041] (C5 and above hydrocarbon components) (volume fraction) % < 3%; test method is SH / T 0230 c ;

[0042] Hydrogen sulfide concentration (mg / m3) not greater than 1; test method is SH / T 0231. f ;

[0043] Evaporation residue (mL / 100mL) not greater than 0.05; Test method is SY / T 7509;

[0044] Copper strip corrosion (40°C, 1h) / grade not greater than 1; test method is SH / T 0232;

[0045] Oxygen compounds c (Volume fraction) / % not greater than 0.005; the test method is SH / T 1547.

[0046] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and are intended to encompass all changes falling within the meaning and scope of equivalents within this invention.

Claims

1. A method for producing saturated liquefied petroleum gas from naphtha through reforming and pre-hydrogenation, characterized in that: Includes the following steps: Step 1: Naphtha containing liquefied petroleum gas components is subjected to olefin saturation reaction under the conditions of pressure 2.2-3.0 MPa, temperature 290-330℃ and catalyst containing W-Mo-Ni system. Step 2: The naphtha after the olefin saturation reaction is fractionated using a stripping tower at a pressure of 1.15-1.25 MPa and a temperature of 30-35℃ to obtain sulfur-containing saturated liquefied petroleum gas. Step 3: After cooling the sulfur-containing saturated liquefied gas, it is subjected to counter-current swirling contact desulfurization treatment with liquid amine liquid at a pressure of 0.8-1.2 MPa and room temperature through a desulfurization tower (1) to obtain saturated liquefied gas that meets the quality requirements of saturated liquefied gas; The desulfurization tower (1) is provided with a liquid phase inlet for introducing the liquid amine liquid and a gas phase outlet for discharging the desulfurized saturated liquefied gas at the top, and a gas phase inlet for introducing the sulfur-containing saturated liquefied gas and a liquid phase outlet for discharging the amine-rich liquid at the bottom. The desulfurization tower (1) is provided with multiple baffles (11) spaced from top to bottom. Each baffle (11) is provided with multiple through-flow swirl elements (12) that enable the sulfur-containing saturated liquefied gas to come into counter-current swirling contact with the liquid amine liquid. The swirl element (12) has a circular outer shell (121) with multiple tangential inlets (122) evenly arranged around the upper and lower positions of the partition (11). The upper and lower end faces of the outer shell (121) are provided with necks (123) that communicate with them, and the neck (123) is open at one end away from the outer shell (121).

2. The method according to claim 1, characterized in that, The open end of the neck (123) in the cyclone element (12) is located below the liquid surface of the liquid amine liquid in the inner cavity of the desulfurization tower (1).

3. The method according to claim 1, characterized in that, The tangential direction of the upper tangential inlet of the outer shell (121) is opposite to the tangential direction of the lower tangential inlet.

4. The method according to claim 1, characterized in that, The upper swirl element (12) and the lower swirl element (12) are arranged alternately.

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