CN108998093A - A kind of pyrolysis oil gas tar lighting recovery system and process - Google Patents

Abstract

The invention discloses a pyrolysis oil gas tar light recovery system and a process method. The system includes a catalytic thermal cracking unit and an oil gas separation unit; the inlet of the catalytic thermal cracking unit is connected with the outlet of the pyrolysis unit, and the outlet of the catalytic thermal cracking unit is separated from oil and gas The inlet of the unit is connected; the catalytic thermal cracking unit is used for high-temperature catalytic thermal cracking reaction of pyrolysis oil gas, and the oil-gas separation unit is used for separating cracked gas, light component oil and heavy component oil. The pyrolysis oil gas is subjected to high-temperature catalytic thermal cracking reaction, so that the heavy tar is catalytically cracked into light component oil and hydrocarbon small molecule gas, and a mixture of cracked gas, light component oil and heavy component oil is obtained; then Cracked gas, light component oil and heavy component oil are separated and recovered. In the present invention, the pyrolysis oil gas is lightened by catalytic thermal cracking at high temperature to obtain high value-added light coal tar, the effective components of the pyrolysis gas are greatly increased, no condensation is used to cool down, and no waste water and waste residues are generated. The product processing is relatively easy and the added value is high. .

Description

A pyrolysis oil and gas tar light recovery system and process method

technical field

The invention belongs to the field of energy and chemical industry, and relates to a pyrolysis oil gas tar light recovery system and a process method.

Background technique

Pyrolysis oil gas is one of the main products in the pyrolysis process, especially in medium and low temperature pyrolysis, the output of pyrolysis oil gas accounts for about 20% to 40% of the dry base pyrolysis raw materials. Reasonable separation and processing of pyrolysis oil and gas can not only improve recycling efficiency and product quality, enable high-value utilization, but also reduce subsequent processing difficulties.

At present, the existing pyrolysis oil gas recovery and utilization process is to condense the tar through circulating spray cooling (water washing, solvent washing), then separate the condensed tar, and then carry out catalytic cracking or hydrogenation catalysis Cracking, thereby improving oil quality. Due to the high content of heavy components (asphaltene) in pyrolysis tar, even as high as 50%, it is very easy to condense during the purification and recovery process of pyrolysis oil and gas, causing pipeline blockage, and the heavy components in the condensed tar Catalytic cracking is more difficult, and the pyrolysis gas after tar recovery is low in active ingredient content, so the processing and utilization effect is poor. In this way, not only the complexity of operation and the difficulty of subsequent processing are increased, but the added value of the product is low, and in the process of gas purification, it causes a large waste of energy and produces difficult-to-treat wastewater, which brings environmental problems.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a pyrolysis oil and gas tar lightening recovery system and process method, in the oil and gas recovery process, realizes the separation of different components of tar, while improving the tar recovery rate, significantly The added value of tar and gas products is improved, and the difficulty of product processing and energy waste are effectively reduced.

The present invention is achieved through the following technical solutions:

A pyrolysis oil and gas tar light recovery system, including a catalytic thermal cracking unit and an oil-gas separation unit; the inlet of the catalytic thermal cracking unit is connected with the outlet of the pyrolysis unit, and the outlet of the catalytic thermal cracking unit is connected with the inlet of the oil-gas separation unit; The cracking unit is used for high-temperature catalytic thermal cracking reaction of pyrolysis oil and gas, and the oil-gas separation unit is used for separating cracked gas, light component oil and heavy component oil.

Preferably, a waste heat recovery unit is also included, the inlet of the waste heat recovery unit is connected to the outlet of the catalytic cracking unit, and the outlet of the waste heat recovery unit is connected to the inlet of the oil-gas separation unit.

Preferably, a PSA hydrogen production unit is also included; the inlet of the PSA hydrogen production unit is connected with the top outlet of the oil-gas separation unit.

Further, it also includes a demethanization LNG unit, the inlet of the demethanization LNG unit is connected with the outlet of the PSA hydrogen production unit.

Further, it also includes a cryogenic separation and olefin extraction unit, the inlet of the cryogenic separation and olefin extraction unit is connected with the outlet of the demethanization LNG unit.

Preferably, it also includes a light oil high value-added product separation unit, the inlet of the light oil high value-added product separation unit is connected with the upper outlet of the oil-gas separation unit, and the light oil high-value-added product separation unit is used to separate the oil and gas separated from the oil-gas separation unit Separation and purification of light component oils to prepare high value-added products.

Preferably, it also includes a unit for preparing high-performance materials from asphaltene, and the inlet of the unit for preparing high-performance materials from asphaltene is connected with the outlet at the bottom of the oil-gas separation unit.

A pyrolysis oil gas tar light recovery process method, based on the system, the pyrolysis oil gas is subjected to high-temperature catalytic thermal cracking reaction, so that the heavy tar is catalytically cracked into light component oil and hydrocarbon small molecule gas to obtain A mixture of cracked gas, light component oil and heavy component oil; then the cracked gas, light component oil and heavy component oil are separated and recovered.

Preferably, the high-temperature catalytic thermal cracking reaction is carried out at 450-550° C. under the action of a catalyst, and the catalyst is one or both of ZCM-7 catalyst and USY molecular sieve.

Preferably, when recovering waste heat, the outlet temperature of the catalytic cracking unit is reduced to 300-350°C.

Compared with the prior art, the present invention has the following beneficial technical effects:

(1) In the traditional tar condensation recovery process, tar is prone to carbonization and coking, etc., which will block the pipeline and affect the long-term operation of the device, and the heavy components of the tar product are high. The invention lightens high-temperature oil and gas by catalytic thermal cracking at high temperature, obtains light coal tar with high added value, and simultaneously increases the effective components of the pyrolysis gas.

(2) Compared with traditional tar recovery processes such as water washing and lipophilic solvents, the high-temperature oil and gas of the present invention directly enter catalytic thermal cracking without condensation and cooling, and produce no waste water and waste residue, which greatly reduces the pressure on environmental protection;

(3) It is difficult to effectively recover the heat in the decoking process by adopting the tar condensation recovery process. The present invention maximizes the utilization of sensible heat of oil products through waste heat recovery, and the energy saving effect is obvious;

(4) The pyrolysis gas after detarring in the traditional tar condensation recovery process is poor in processing and utilization due to the low content of active ingredients; the process of the present invention is easy to obtain high calorific value gases such as H ₂ , liquefied natural gas (LNG), and low-carbon olefins.

(5) The present invention reduces the weight of the tar, which is relatively easy to process and has high added value.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present invention.

In the figure: 1-dust removal unit, 2-catalytic thermal cracking unit, 3-waste heat recovery unit, 4-oil and gas separation unit, 5-PSA hydrogen production unit, 6-demethanization to LNG unit, 7-cryogenic separation and olefin extraction unit , 8-light oil high value-added product separation unit, 9-asphaltene preparation high-performance material unit.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

The system for lightening and recovering tar from pyrolysis oil and gas according to the present invention is used for recovering and lightening tar in pyrolysis oil and gas, separating recovered oil and gas products, and rationally utilizing them.

As shown in Figure 1, the system of the present invention includes a dust removal unit 1, a catalytic thermal cracking unit 2, a waste heat recovery unit 3, an oil and gas separation unit 4, a PSA hydrogen production unit 5, a demethanization LNG unit 6, and a cryogenic separation and olefin extraction unit 7 , light oil high value-added product separation unit 8 and asphaltene preparation high-performance material unit 9.

The inlet of the dedusting unit 1 is connected with the outlet of the pyrolysis unit, and is used for dedusting the pyrolysis oil gas; the inlet of the catalytic cracking unit 2 is connected with the outlet of the dedusting unit, and at least one section of catalyst bed is arranged inside, used for dedusting the dedusted heat Decompose the heavy components of tar in oil and gas for high-temperature catalytic cracking reaction, most of the heavy tars will be lightened, some will generate light component oil, and some will generate low-carbon hydrocarbons; the catalyst is ZCM-7 catalyst and USY molecular sieve one or both. Specifically, the catalytic thermal cracking unit 2 is equipped with one or more catalyst beds, and under the action of the catalyst at 450-550 ° C, the high-temperature oil and gas after dedusting are subjected to catalytic thermal cracking, and most of the heavy tar components are lightened. Part of it produces light component oil, and part of it produces light olefins.

The inlet of waste heat recovery unit 3 is connected to the outlet of catalytic cracking unit 2, which is used to recover part of the sensible heat of thermally cracked oil and gas. Through waste heat recovery, the temperature of the cracked oil and gas outlet is reduced to 300-350°C, and superheated steam is produced, as well as steam.

The inlet of the oil-gas separation unit 4 is connected to the outlet of the waste heat recovery unit 3, and the upper part is equipped with light component oil backflow to absorb the oil in the cracked oil and gas, which is used to separate the oil and gas after waste heat recovery, and remove the remaining small part of heavy components. Oil separation and light component oil separation. The oil-gas separation unit 4 is equipped with multiple stages of trays to separate the cracked oil and cracked gas. The cracked oil of different fractions is drawn from the upper and lower side lines of the tower respectively, and the cracked gas is drawn from the top of the tower.

The top outlet of the oil-gas separation unit 4 is connected with the inlet of the PSA hydrogen production unit 5, which is used for pressure swing adsorption hydrogen production; the inlet of the demethanization LNG unit 6 is connected with the outlet of the PSA hydrogen production unit 5, and is used for pyrolysis The methane in the gas is recovered to produce LNG; the inlet of the cryogenic separation and olefin extraction unit 7 is connected with the outlet of the demethanization LNG unit 6, which is used to produce low-carbon olefins, and the remaining CO, CO ₂ and other gases to synthesize urea or food industries . Connect the cracked gas outlet to the PSA hydrogen production unit 5, the demethanization LNG unit 6, and the cryogenic separation and olefin extraction unit 7 to separate and purify the cracked gas to obtain high-purity hydrogen, LNG products and C ₂ -C ₆ low The main products such as carbon olefins, and the remaining gas are utilized according to different needs.

The upper outlet of the oil-gas separation unit 4 is connected to the inlet of the light oil high value-added product separation unit 8. The light oil high value-added product separation unit 8 is used to recover light component oil, and separate and purify it to prepare high value-added products such as phenols product.

The outlet at the bottom of the oil-gas separation unit 4 is connected to the inlet of the asphaltene preparation high-performance material unit 9. The asphaltene preparation high-performance material unit 9 is used to recover heavy component oil to prepare high-performance materials such as needle coke and carbon fiber.

The pyrolysis oil gas tar lightening recovery process method of the present invention comprises the following steps:

The pyrolysis oil gas at 550-700°C from the pyrolysis unit enters the dedusting unit 1 for separation of high temperature oil gas and dust, and the dedusted pyrolysis oil gas enters the catalytic thermal cracking unit 2.

Catalytic thermal cracking unit 2 carries out catalytic thermal cracking reaction at 450-550°C under the catalysis of one or both of the catalyst ZCM-7 and USY molecular sieve catalyst, and cracks the heavy component oil with high molecular weight in the pyrolysis oil gas, Generate low molecular weight light component oil and hydrocarbon gas, and then enter the waste heat recovery unit 3.

The waste heat recovery unit 3 uses industrial circulating water as the heat exchange medium to recover the sensible heat of the thermally cracked oil and gas at 450-500°C, and the temperature of the thermally cracked oil and gas at the outlet of the waste heat recovery unit 3 drops to 300-350°C. The temperature of the recovered oil and gas is controlled above 300°C, the circulating water absorbing sensible heat generates superheated steam, and the thermally cracked oil and gas enters the oil and gas separation unit 4 .

The oil-gas separation unit 4 utilizes the light component oil reflux process to absorb the oil in the cracked gas, and separates the thermally cracked oil and gas that recovers part of the sensible heat for oil-gas separation, and the light component oil below 300°C is separated from the upper side line of the oil-gas separation unit 4, 300 The heavy component oil above ℃ is separated from the lower part of the oil-gas separation unit 4, and the pyrolysis gas is discharged from the top of the oil-gas separation unit 4.

The outlet of the oil and gas separation unit 4 is sequentially connected to the PSA hydrogen production unit, the demethanization LNG unit 6, and the cryogenic separation and olefin extraction unit 7 to separate and purify thermal cracking oil and gas to obtain high-purity hydrogen, LNG products and C ₂ ~ C ₆ low carbon The main products such as olefins, and the remaining gas are sent to the downstream process according to different needs.

The light oil high value-added product separation unit 8 separates and purifies the light component oil separated from the oil-gas separation unit 4 to prepare high value-added products such as phenols.

The asphaltene preparation high-performance material unit 9 recovers the heavy component oil separated by the oil-gas separation unit 4 to prepare high-performance materials such as needle coke and carbon fiber.

The present invention has been further described above with the help of specific embodiments, but it should be understood that the specific description herein should not be construed as limiting the spirit and scope of the present invention. Various modifications made in the embodiments all belong to the protection scope of the present invention.

Claims (10)

1. a pyrolysis oil and gas tar lightening recovery system, is characterized in that, comprises catalytic thermal cracking unit (2) and oil-gas separation unit (4); Catalytic thermal cracking unit (2) inlet is connected with pyrolysis unit outlet, The outlet of the catalytic thermal cracking unit (2) is connected with the inlet of the oil-gas separation unit (4); , Light component oil and heavy component oil are separated. 2. The pyrolysis oil and gas tar lightening recovery system according to claim 1, characterized in that, it also includes a waste heat recovery unit (3), and the waste heat recovery unit (3) inlet is connected with the catalytic cracking unit (2) outlet, The outlet of the waste heat recovery unit (3) communicates with the inlet of the oil-gas separation unit (4). 3. The pyrolysis oil and gas tar lightening recovery system according to claim 1, characterized in that, it also includes a PSA hydrogen production unit (5); the PSA hydrogen production unit (5) inlet and the oil and gas separation unit (4) top outlet connected. 4. the pyrolysis oil gas tar lightening recovery system according to claim 3, is characterized in that, also comprises demethanization LNG unit (6), demethanization LNG unit (6) import and PSA hydrogen production unit (5) ) exits are connected. 5. The pyrolysis oil and gas tar lightening recovery system according to claim 4, characterized in that it also includes a cryogenic separation and olefin extraction unit (7), and the cryogenic separation and olefin extraction unit (7) imports and demethanizes LNG Unit (6) outlets are connected. 6. The pyrolysis oil and gas tar lightening recovery system according to claim 1, characterized in that, it also includes a light oil high value-added product separation unit (8), and the light oil high value-added product separation unit (8) inlet and The upper outlet of the oil-gas separation unit (4) is connected, and the light oil high value-added product separation unit (8) is used to separate and purify the light component oil separated from the oil-gas separation unit (4) to prepare high value-added products. 7. The pyrolysis oil and gas tar lightening recovery system according to claim 1, characterized in that it also includes a high-performance material unit (9) for asphaltene preparation, and the entrance of the high-performance material unit (9) for asphaltene preparation is separated from oil and gas The outlets at the bottom of the unit (4) are connected. 8. A pyrolysis oil gas tar lightening recovery process, characterized in that, based on the system described in any one of claims 1-7, the pyrolysis oil gas is subjected to high temperature catalytic thermal cracking reaction, so that the heavy tar is catalytically cracked For light component oil and hydrocarbon small molecule gas, a mixture of cracked gas, light component oil and heavy component oil is obtained; then the cracked gas, light component oil and heavy component oil are separated and recovered. 9. The pyrolysis oil gas tar lightening recovery process according to claim 8, characterized in that the high-temperature catalytic thermal cracking reaction is carried out at 450-550°C under the action of a catalyst, and the catalyst is ZCM-7 catalyst and USY molecular sieve one or both. 10. The pyrolysis oil and gas tar lightening recovery process according to claim 8, characterized in that, when recovering waste heat, the outlet temperature of the catalytic cracking unit (2) is reduced to 300-350°C.