Method for combined recovery of ethylene raw material and hydrogen in dry gas

Abstract

The invention discloses a method for combined recovery of an ethylene raw material and hydrogen in dry gas, which comprises the following steps: step 1, an ethane PSA process: dry gas rich in ethane components and hydrogen PSA process desorbed gas enter an adsorber, effective components above C2 are selectively adsorbed by an adsorbent, and impurity components are discharged through an adsorber bed layer and sent to a fuel gas pipe network; step 2, hydrogen PSA (Pressure Swing Adsorption) process; the invention provides a production process for combined recovery of multiple gas components and comprehensive utilization of gas resources in the whole technological process, and the comprehensive utilization level of the resources is improved; according to the method, dry gases from different sources are classified, and dry gases rich in ethane components and dry gases rich in hydrogen components are concentrated and recovered respectively, so that respective recovery efficiency is improved; tail gas obtained after hydrogen recovery is used as a raw material for ethane recovery, so that the comprehensive utilization level of dry gas is improved; and the cracked crude hydrogen and the hydrogen-rich component dry gas co-construct a hydrogen recovery system, so that device resources are integrated, and the utilization rate of equipment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical recycling, in particular to a method for jointly recovering ethylene raw materials and hydrogen in dry gas. Background Art

[0002] Refinery dry gas refers to non-condensable gas produced and recovered during the refining process of an oil refinery. Its main components are ethylene, propylene, methane, ethane, propane, butane, etc. These gases are separated through distillation, cracking and other processes during the refining process. They have the characteristics of low smoke point, low oxygen intensity and low flame melting point, which can greatly reduce environmental pollution. Since they do not contain sulfur and nitrogen, they can produce more mass energy during combustion, which is beneficial to improving fuel combustion efficiency. The recovery and utilization of refinery dry gas is one of the important measures for energy conservation and emission reduction in refineries. Common recovery technologies include absorption, compression, cooling and other processes. These technologies can effectively recover refining dry gas and use it for the production of fuel and chemical raw materials. In addition, shallow cold separation and purification technology has also been developed to separate and recover carbon dioxide and carbon three components in refinery dry gas. This technology has reached the international advanced level, which helps to reduce the carbon dioxide produced by dry gas combustion and assist refining enterprises.

[0003] However, traditional refinery dry gas recovery has the following disadvantages:

[0004] For the recovery of refinery dry gas, there are existing gas recovery technologies such as pressure swing adsorption to recover ethylene resources in refinery dry gas, shallow cold oil absorption to recover refinery dry gas, deep cold separation, membrane separation, etc. However, these technologies are limited to special research on recovery methods of specific gases and optimization of specific recovery methods. There has been no research on the combined recovery of multiple gas types or comprehensive recovery research of the entire process, which cannot meet people's demand for gas recovery. Summary of the invention

[0005] The purpose of the present invention is to provide a method for the joint recovery of ethylene raw materials and hydrogen in dry gas, so as to solve the problem of the recovery of refinery dry gas proposed in the above-mentioned background technology. The existing gas recovery technologies such as pressure swing adsorption recovery technology of ethylene resources in refinery dry gas, shallow cold oil absorption method recovery technology of refinery dry gas, deep cold separation method, membrane separation method, etc. are limited to special research on the recovery method of specific gases and the optimization of specific recovery methods. There is no research on the joint recovery of multiple gas types and the comprehensive recovery research of the whole process, which cannot meet people's demand for gas recovery.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for jointly recovering ethylene raw material and hydrogen in dry gas, comprising the following steps:

[0007] Step 1, ethane PSA process: ethane-rich dry gas and hydrogen PSA process desorbed gas enter the adsorber, the effective components above C2 are selectively adsorbed by the adsorbent, and the impurity components are discharged through the adsorber bed and sent to the fuel gas pipeline network for use as fuel gas;

[0008] Step 2, hydrogen PSA process: using dry gas rich in hydrogen components and cold separation tail gas of ethylene unit as raw materials, the impurity components are selectively adsorbed by the adsorbent in the adsorber, and the hydrogen components are discharged through the bed to obtain product hydrogen;

[0009] Step 3, ethylene production: The ethylene production raw materials including the ethane-rich gas obtained from ethane PSA are subjected to cracking, rapid cooling, compression, alkali washing, drying, deethane removal and cold separation processes to obtain ethylene products.

[0010] As a preferred technical solution of the present invention, the effective components above C2 adsorbed in the step 1 are reversed and vacuumed to release ethane-rich gas, which is compressed and pressurized and sent to the ethylene raw material cracking furnace.

[0011] As a preferred technical solution of the present invention, the desorbed gas obtained by inverting the adsorbed component in step 2 is sent to the ethane PSA process to continue to recover the ethylene raw material.

[0012] As a preferred technical solution of the present invention, the cold-separated tail gas in step three is rich in hydrogen components and is sent to the hydrogen PSA process to recover hydrogen.

[0013] As a preferred technical solution of the present invention, the specific process of the ethane PSA process in step one is: the dry gas rich in ethane component is transported to the ethane PSA adsorption tower, the waste gas generated by the ethane PSA adsorption tower is discharged from the top of the ethane PSA adsorption tower, the vacuum air at the bottom of the ethane PSA adsorption tower is transported to the ethane-rich product compressor through a vacuum pump, and the ethane PSA adsorption tower is reversely discharged and transported to the ethane-rich product compressor.

[0014] As a preferred technical solution of the present invention, the specific process of the hydrogen PSA process in step 2 is: dry gas rich in hydrogen components is transported to the hydrogen PSA adsorption tower, the hydrogen PSA adsorption tower discharges hydrogen and fuel gas from the top, the hydrogen PSA desorption gas discharged from the hydrogen PSA adsorption tower is transported to the PSA2 adsorption waste gas compressor, and the gas generated by the PSA2 adsorption waste gas compressor is refluxed to the ethane PSA adsorption tower.

[0015] As a preferred technical solution of the present invention, the specific process of ethylene production in step three is as follows: the ethylene cracking raw material, the ethylene-rich product gas produced in the ethylene-rich product compressor is transported to the ethylene tower to separate ethylene after being subjected to cracking, rapid cooling, compression, construction, drying, deethaneization and cold separation treatment, and the cold separation product is transported to the PSA2 adsorption waste gas compressor, the deethaned product is subjected to thermal separation to produce propylene and C4, and the ethylene and propylene produced by the thermal separation are circulated for cracking.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The dry gas comprehensive utilization production process for recovering ethylene raw materials and hydrogen proposed in the present invention is combined with the main process of ethylene production, and the dry gas rich in hydrogen components and the cold separation tail gas of the ethylene device are combined to recover hydrogen, which saves investment and reduces land occupation compared with building two sets of recovery devices separately; the hydrogen PSA desorption waste gas is used as the ethane PSA raw material to improve the ethylene resource recovery rate;

[0018] 2. Provide a production process for the joint recovery of multiple gas components and comprehensive utilization of gas resources in the entire process to improve the level of comprehensive resource utilization; classify dry gas from different sources, and separately concentrate and recover ethane-rich dry gas and hydrogen-rich dry gas to improve their respective recovery efficiencies; use hydrogen-recovered tail gas as a raw material for ethane recovery to improve the level of comprehensive dry gas utilization; build a hydrogen recovery system with cracked crude hydrogen and hydrogen-rich dry gas to integrate device resources and improve equipment utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] See also Figure 1-2 The present invention provides a method for combined recovery of ethylene raw material and hydrogen in dry gas, comprising the following steps:

[0023] Step 1, ethane PSA process: ethane-rich dry gas and hydrogen PSA process desorbed gas enter the adsorber, the effective components above C2 are selectively adsorbed by the adsorbent, and the impurity components are discharged through the adsorber bed and sent to the fuel gas pipeline network for use as fuel gas;

[0024] Step 2, hydrogen PSA process: using dry gas rich in hydrogen components and cold separation tail gas of ethylene unit as raw materials, the impurity components are selectively adsorbed by the adsorbent in the adsorber, and the hydrogen components are discharged through the bed to obtain product hydrogen;

[0025] Step 3, ethylene production: The ethylene production raw materials including the ethane-rich gas obtained from ethane PSA are subjected to cracking, rapid cooling, compression, alkali washing, drying, deethane removal and cold separation processes to obtain ethylene products.

[0026] The effective components above C2 adsorbed in step 1 are desorbed and released into ethane-rich gas through inversion and vacuum operation, and then compressed and pressurized to be sent to the ethylene raw material cracking furnace.

[0027] The desorbed gas obtained by reversely releasing the adsorbed component in step 2 is sent to the ethane PSA process to continue to recover the ethylene raw material.

[0028] The tail gas separated by cold treatment in step 3 is rich in hydrogen components and is sent to the hydrogen PSA process to recover hydrogen.

[0029] The specific process of the ethane PSA step in step one is: the dry gas rich in ethane components is transported to the ethane PSA adsorption tower, the waste gas generated by the ethane PSA adsorption tower is discharged from the top of the ethane PSA adsorption tower, the vacuum air at the bottom of the ethane PSA adsorption tower is transported to the ethane-rich product compressor through a vacuum pump, and the ethane PSA adsorption tower is reversely discharged and transported to the ethane-rich product compressor.

[0030] The specific process of the hydrogen PSA process in step 2 is: the dry gas rich in hydrogen components is transported to the hydrogen PSA adsorption tower, the hydrogen PSA adsorption tower discharges hydrogen and fuel gas from the top, the hydrogen PSA desorption gas discharged from the hydrogen PSA adsorption tower is transported to the PSA2 adsorption waste gas compressor, and the gas generated by the PSA2 adsorption waste gas compressor is refluxed to the ethane PSA adsorption tower.

[0031] The specific process of ethylene production in step three is as follows: the ethylene cracking raw material, the ethylene-rich product gas produced in the ethylene-rich product compressor is transported to the ethylene tower to separate ethylene after being cracked, quenched, compressed, built up, dried, deethaned and cold separated, and the cold separated product is transported to the PSA2 adsorption waste gas compressor, the deethaned product is subjected to thermal separation to produce propylene and C4, and the ethylene and propylene produced by the thermal separation are circulated for cracking.

[0032] In the present invention, ethane-rich dry gas and hydrogen PSA process desorbed gas enter the adsorber, effective components above C2 are selectively adsorbed by the adsorbent, and impurity components are discharged through the adsorber bed and sent to the fuel gas pipeline network for use as fuel gas; hydrogen-rich dry gas and ethylene device cold separation tail gas are used as raw materials, impurity components are selectively adsorbed by the adsorbent in the adsorber, and hydrogen components are discharged through the bed to obtain product hydrogen; ethylene production raw materials including ethane-rich gas obtained by ethane PSA are cracked, quenched, compressed, alkali washed, dried, de-ethanized, and cold separated to obtain ethylene products. There are two refinery dry gas raw materials, ethane-rich dry gas 19919.22Nm 3 / h, hydrogen-rich dry gas 34626.23Nm 3 / h, composed of the following table:

[0033]

[0034] Hydrogen PSA process mixed raw material 69144.10Nm 3 / h, and obtain hydrogen product 49745.26Nm 3 / h, analytical gas 19395.37Nm 3 / h, composed of the following table:

[0035]

[0036]

[0037] Ethane PSA process mixed raw material 39314.59Nm 3 / h, obtaining ethane-rich product gas 10736.00Nm 3 / h, adsorption of waste gas (fuel gas) 28578.59Nm 3 / h, composed of the following table:

[0038]

[0039] The material balance of the whole device is as follows:

[0040]

[0041]

[0042] Compared with separately building a refinery dry gas hydrogen recovery unit and an ethylene cold separation tail gas hydrogen recovery unit, the hydrogen-rich dry gas and the ethylene unit cold separation tail gas are combined to recover hydrogen, and the total land area is reduced to 40%; compared with separately setting up an ethane recovery unit and a hydrogen recovery unit, the hydrogen PSA desorption gas from the hydrogen recovered tail gas is incorporated into the raw material for ethane recovery, and 3.20% more C2 and above components are recovered.

[0043] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for the combined recovery of ethylene feedstock and hydrogen in dry gas, characterized in that: The following steps are involved: Step 1, ethane PSA process: ethane-rich dry gas and hydrogen PSA process desorbed gas enter the adsorber, the effective components above C2 are selectively adsorbed by the adsorbent, and the impurity components are discharged through the adsorber bed and sent to the fuel gas pipeline network for use as fuel gas; Step 2, hydrogen PSA process: using dry gas rich in hydrogen components and cold separation tail gas of ethylene unit as raw materials, the impurity components are selectively adsorbed by the adsorbent in the adsorber, and the hydrogen components are discharged through the bed to obtain product hydrogen; Step 3, ethylene production: The ethylene production raw materials including the ethane-rich gas obtained from ethane PSA are subjected to cracking, rapid cooling, compression, alkali washing, drying, deethane removal and cold separation processes to obtain ethylene products.

2. The method for combined recovery of ethylene raw material and hydrogen in dry gas according to claim 1, characterized in that: The effective components above C2 adsorbed in the step 1 are desorbed and released into ethane-rich gas through inversion and vacuum operation, and then compressed and pressurized to be sent to the ethylene raw material cracking furnace.

3. The method for combined recovery of ethylene raw material and hydrogen in dry gas according to claim 1, characterized in that: The desorbed gas obtained by inverting the adsorbed component in step 2 is sent to the ethane PSA process to continue to recover the ethylene raw material.

4. The method for combined recovery of ethylene raw material and hydrogen in dry gas according to claim 1, characterized in that: The cold-separated tail gas in step 3 is rich in hydrogen components and is sent to the hydrogen PSA process to recover hydrogen.

5. The method for combined recovery of ethylene raw material and hydrogen in dry gas according to claim 1, characterized in that: The specific process of the ethane PSA step in step 1 is as follows: dry gas rich in ethane components is transported to an ethane PSA adsorption tower, waste gas generated by the ethane PSA adsorption tower is discharged from the top of the ethane PSA adsorption tower, vacuum air from the bottom of the ethane PSA adsorption tower is transported to an ethane-rich product compressor through a vacuum pump, and reverse venting from the ethane PSA adsorption tower is transported to the ethane-rich product compressor.

6. The method for combined recovery of ethylene raw material and hydrogen in dry gas according to claim 1, characterized in that: The specific process of the hydrogen PSA process in step 2 is: the dry gas rich in hydrogen components is transported to the hydrogen PSA adsorption tower, the hydrogen PSA adsorption tower discharges hydrogen and fuel gas from the top, the hydrogen PSA desorption gas discharged from the hydrogen PSA adsorption tower is transported to the PSA2 adsorption waste gas compressor, and the gas generated by the PSA2 adsorption waste gas compressor is refluxed to the ethane PSA adsorption tower.

7. The method for combined recovery of ethylene raw material and hydrogen in dry gas according to claim 1, characterized in that: The specific process of ethylene production in step 3 is as follows: the ethylene cracking raw material and the ethylene-rich product gas produced in the ethylene-rich product compressor are transported to the ethylene tower to separate ethylene after being cracked, quenched, compressed, built up, dried, de-ethanized and cold-separated, and the cold-separated product is transported to the PSA2 adsorption waste gas compressor, the de-ethanized product is subjected to thermal separation to produce propylene and C4, and the ethylene and propylene produced by the thermal separation are circulated for cracking.

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