Method for producing ethylene and / or propylene and device for producing the same

Abstract

To provide high-quality ethylene and propylene stably and inexpensively, while accommodating a broad range of raw oils, especially those containing oxygenated compounds.SOLUTION: A method for producing ethylene and / or propylene includes at least the following steps in order: a raw oil pyrolysis step, a quenching step; a compression step; and an acidic component removal step. The acidic component removal step includes: an absorption step that allows the acidic component to be absorbed onto a removal solution; and a regeneration step that removes the acidic component from the removal solution having absorbed the acidic component to regenerate it. The raw oil used here is one with an oxygenated compound content of more than 50 mass ppm. At least a part of the removal solution is discarded so that the removal solution having absorbed the acidic component shows a methanol concentration of 300 mg / L or less, and a new removal solution is supplied.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing ethylene and / or propylene. [Background technology]

[0002] In ethylene production equipment, hydrocarbon oil such as naphtha is generally used as a raw material. The hydrocarbon oil is thermally decomposed to produce cracked gases such as methane, ethane, ethylene, and propylene. Ethylene and propylene are then produced through a quenching process in which the cracked gas is cooled, a compression process in which the cooled cracked gas is pressurized, and an acidic component removal process in which acidic components (e.g., carbon dioxide, hydrogen sulfide, etc.) contained in the cracked gas (see, for example, Patent Document 1, Non-Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-172887 A [Non-patent literature]

[0004] [Non-Patent Document 1] Proceedings of the 25th Fuzzy System Symposium, Japan Society for Fuzzy Theory and Intelligent Informatics, 25.0.125.0, 2009 Summary of the Invention [Problem to be solved by the invention]

[0005] The feedstock oil such as naphtha may contain oxygen-containing compounds such as alcohols, ethers, and ketones, for example, methanol, ethanol, acetone, butanol, methyl ethyl ketone, and methyl-tert-butyl ether. When a feedstock oil containing a large amount of oxygen-containing compounds, for example, 50 mass ppm or more, is used, the decomposition gas contains methanol if the oxygen-containing compounds are methanol, and methanol produced by the reaction in the pyrolysis furnace if the oxygen-containing compounds are compounds other than methanol. The methanol contained in the decomposition gas significantly increases the methanol concentration in propylene, leading to a decrease in quality. Therefore, it is important to use a feedstock oil with a low concentration of oxygen-containing compounds for the production of ethylene.

[0006] Thus, feedstock oils containing high concentrations of oxygen-containing compounds should basically be prohibited from use, since they lead to a deterioration in the quality of propylene in particular. However, in recent years, there has been a tendency for feedstock oils containing high concentrations of oxygen-containing compounds exceeding 50 ppm by mass to be increasingly supplied, and there are concerns that prohibiting their use would lead to an increase in procurement costs and further to problems in the stable procurement of feedstock oils. Therefore, it is an urgent task to develop a method for producing high-quality ethylene and propylene without causing a deterioration in the quality of propylene, even when feedstock oils containing high concentrations of oxygen-containing compounds are used.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide high-quality ethylene and propylene stably and inexpensively while being adaptable to a wide range of feedstock oils, particularly feedstock oils containing oxygen-containing compounds. [Means for solving the problem]

[0008] The present inventors have conducted intensive research in view of the above problems and have found that the above problems can be solved by the following invention. That is, the present invention provides a method and an apparatus for producing ethylene and / or propylene having the following configurations.

[0009] [1] At least, a feedstock oil thermal cracking process, a quenching process, a compression process, and an acidic component removal process are included in this order; the acidic component removal step includes an absorption step of absorbing the acidic components into a removal solution and a regeneration step of removing the acidic components from the removal solution having absorbed the acidic components, and regenerating the acidic components, A feed oil having an oxygen-containing compound content of more than 50 ppm by mass is used as the feed oil, discarding at least a part of the removing solution and supplying a new removing solution so that the methanol concentration in the removing solution having absorbed the acidic component becomes 300 mg / L or less; A method for producing ethylene and / or propylene. [2] The method for producing ethylene and / or propylene according to the above item [1], wherein when a methanol concentration in the removal solution having absorbed the acidic component exceeds 300 mg / L, at least a part of the removal solution is discarded and fresh removal solution is supplied so that the methanol concentration becomes 300 mg / L. [3] The method for producing ethylene and / or propylene according to the above [1] or [2], wherein in the quenching step, at least a part of the quench water used for quenching the cracked gas supplied from the thermal decomposition step is discarded and fresh quench water is supplied so that the methanol concentration in the quench water is 90 mg / L or less. [4] The method for producing ethylene and / or propylene according to any one of the above [1] to [3], wherein in the quenching step, at least a part of the quench water used for quenching the cracked gas supplied from the thermal cracking step is discarded and fresh steam is supplied to the thermal cracking step of the feedstock oil so that the methanol concentration contained in the quench water is 90 mg / L or less. [5] The method for producing ethylene and / or propylene according to any one of the above [1] to [4], wherein the feedstock oil contains naphtha having an oxygen-containing compound content of 50 ppm by mass or more. [6] The method for producing ethylene and / or propylene according to the above [5], wherein the feedstock oil further contains bio-oil. [7] The method for producing ethylene and / or propylene according to any one of the above [1] to [6], wherein the acidic component comprises at least one selected from carbon dioxide and hydrogen sulfide. [8] The method for producing ethylene and / or propylene according to any one of the above [1] to [7], wherein the removing solution is an aqueous amine solution.

[0010] [9] At least one facility for thermal cracking of raw oil, quenching, compression and acid component removal, the acidic component removal equipment includes an absorption equipment for absorbing the acidic components into a removal solution, and a regeneration equipment for removing the acidic components from the removal solution having absorbed the acidic components and regenerating the solution, and also includes a removal solution adjustment equipment for discarding at least a part of the removal solution and supplying a new removal solution so that the methanol concentration in the removal solution having absorbed the acidic components is 300 mg / L or less. Ethylene and / or propylene production equipment.

[10] The ethylene and / or propylene production apparatus according to the above item [9], further comprising a quench water adjusting unit which discards at least a portion of the quench water used for quenching the cracked gas supplied from the thermal decomposition unit and supplies fresh quench water so that the methanol concentration in the quench water is 90 mg / L or less.

[11] The method for producing ethylene and / or propylene according to the above item [9] or

[10] , wherein the thermal cracking facility for the feedstock oil has a steam regulating facility for supplying steam so that the methanol concentration in quench water used for quenching the cracked gas supplied from the thermal cracking facility is 90 mg / L or less.

[12] The apparatus for producing ethylene and / or propylene according to any one of the above [9] to

[11] , wherein the removing solution is an amine solution. Effect of the Invention

[0011] According to the present invention, it is possible to stably provide high-quality ethylene and propylene at low cost while dealing with a wide range of feedstock oils, particularly feedstock oils containing oxygen-containing compounds. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a flow diagram showing a preferred embodiment of an acidic component removal facility in the production facility of the present embodiment. [Diagram 2] FIG. 2 is a flow diagram showing a preferred embodiment of a quench facility in the production facility of the present embodiment. [Diagram 3] 1 is a graph showing the relationship between the methanol concentration in a rich amine solution and the methanol removal rate in a reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a method and an apparatus for producing ethylene and / or propylene according to an embodiment of the present invention (hereinafter, sometimes simply referred to as "the present embodiment") will be specifically described. In this specification, the values ​​of "less than", "more than", and "to" in describing a numerical range are values ​​that can be arbitrarily combined. For example, when a certain numerical range is described as "A to B" and "C to D", the numerical ranges "A to D" and "C to B" are also included. The numerical values ​​in the examples are values ​​that can be used as upper or lower limits.

[0014] [Method for producing ethylene and / or propylene] The method for producing ethylene and / or propylene of the present embodiment includes at least a thermal cracking step of a feedstock oil, a quenching step, a compression step, and a step of removing an acidic component, in this order. the acidic component removal step includes an absorption step of absorbing the acidic components into a removal solution and a regeneration step of removing the acidic components from the removal solution having absorbed the acidic components, and regenerating the acidic components, A feed oil having an oxygen-containing compound content of more than 50 ppm by mass is used as the feed oil, At least a part of the removing solution is discarded and a new removing solution is supplied so that the methanol concentration in the removing solution that has absorbed the acidic component becomes 300 mg / L or less.

[0015] In the past, when a feedstock oil containing oxygen-containing compounds at a high concentration was used, the oxygen-containing compounds were mixed into propylene as methanol, and the methanol concentration in propylene was significantly increased, leading to a decrease in the quality of propylene. In the production method of the present embodiment, attention was focused on methanol among the oxygen-containing compounds contained in the feedstock oil. Methanol is a compound that is generated by the reaction of other oxygen-containing compounds in a pyrolysis furnace not only when methanol is contained in the feedstock oil, but also when it is not contained. Furthermore, since it has a property of being easily dissolved in water, it is particularly easily concentrated in each step of the production method of ethylene and / or propylene of the present embodiment (hereinafter, sometimes simply referred to as the "production method of the present embodiment"), and as a result, it is a compound that can be mixed into propylene.

[0016] The inventors thought that by controlling the methanol in any one of the steps, it would be possible to suppress the mixing of methanol into propylene, and thus to produce high-quality ethylene and propylene. Further research was conducted, and it was found that there is a correlation between the methanol concentration in the acidic component removal step and the methanol concentration contained in propylene. Therefore, the methanol concentration in the acidic component removal step was controlled to be a certain concentration, and when it exceeded this concentration, at least a part of the removal solution used in the acidic component removal step was discarded and a new removal solution was supplied, which led to the suppression of the increase in the methanol concentration in propylene. The control of the methanol concentration in the removal solution in the acidic component removal step is relatively easy, and the operation of discarding and replenishing a part of the removal solution when the methanol concentration exceeds a certain concentration is also relatively easy. Nevertheless, it is a surprising effect that the increase in the methanol concentration in propylene can be suppressed. Thus, the method for producing ethylene and / or propylene of the present embodiment is a method that can stably provide high-quality ethylene and propylene at low cost while being compatible with a wide range of feedstock oils, particularly feedstock oils containing oxygen-containing compounds.

[0017] According to the production method of this embodiment, ethylene, propylene, or ethylene and propylene can be produced. In addition, when naphtha, which will be described later, is used as a feedstock oil, other than ethylene and propylene, for example, propylene, butane, butene, butadiene, and aromatic hydrocarbons such as benzene, toluene, and xylene can also be obtained by carrying out reactions and purification as necessary.

[0018] (About each process) The production method of this embodiment includes at least a feedstock oil thermal cracking step, a quenching step, a compression step, and an acidic component removal step, in that order. In the thermal cracking process of the feedstock oil, thermal cracking is carried out with the feedstock oil and steam in a thermal cracking furnace heated to 700 to 900°C, preferably 750 to 850°C, by a burner, and a thermal cracking gas containing mainly paraffins such as methane, ethane, propane, butane, and pentane, and olefins such as ethylene and propylene is obtained. The thermal cracking gas also contains aromatic compounds such as benzene, toluene, and xylene.

[0019] The high-temperature pyrolysis gas obtained in the above pyrolysis step is cooled using quench water in a quench tower in the quench step. Depending on whether or not a cracked gas fractionator (described later) is used, the gas fraction is separated into water and a gasoline fraction (about C5 to C9) in the quench tower. The water is recycled to the pyrolysis furnace as necessary, and the gasoline fraction is used as cracked gasoline. The quenching step may further include a quencher for quenching the mixture by mixing with heavy oil or the like before cooling with quench water, and a cracked gas fractionator for fractionating the heavy fraction.

[0020] The gas obtained in the quenching step is compressed in a compression step so as to be pumped to various purification steps such as an acidic component removal step.

[0021] The acidic component removal process is a process for removing acidic components, particularly carbon dioxide and hydrogen sulfide, contained in the gas fraction. The gas fraction obtained in the quenching process contains carbon dioxide and hydrogen sulfide as acidic components, and these acidic components lead to the poisoning and deactivation of catalysts used in downstream purification equipment. The acidic component removal process is a process employed to remove the acidic components in advance. Other details regarding the acidic component removing step will be described later.

[0022] The thermal cracking step, the quenching step, and the compression step are steps that have been conventionally employed in ethylene production methods, and there are no particular limitations on the amount of steam supplied to the feed oil, the configuration of each device used in each step, and the temperature and pressure conditions in each step (each device), and these conditions may be appropriately adopted based on the conventional technology. The acidic component removal step is also a step that has been conventionally employed in ethylene production methods. As described above, the step differs in that at least a part of the removal solution is discarded and a new removal solution is supplied, but there are no particular limitations on the configuration of each device, the temperature and pressure conditions, and these conditions may be appropriately adopted based on the conventional technology.

[0023] (raw oil) The feedstock oil used in the production method of this embodiment is an oil having an oxygen-containing compound content of more than 50 ppm by mass. The oxygen-containing compound may be any compound that contains an oxygen atom, and representative examples include alcohols such as methanol, ethanol, butanol, etc.; ethers such as methyl tert-butyl ether, etc.; ketones such as acetone, methyl ethyl ketone, etc. These compounds are merely examples, and any compound that is contained in the feedstock and contains an oxygen atom may be included.

[0024] The content of oxygen-containing compounds contained in the feedstock oil is more than 50 ppm by mass. According to the production method of this embodiment, even feedstock oil containing such a large amount of oxygen-containing compounds can be used. The content of oxygen-containing compounds contained in the feedstock oil used in the production method of this embodiment may be, for example, 55 ppm by mass or more, 65 ppm by mass or more, 80 ppm by mass or more, or 100 ppm by mass or more, and although there is no particular upper limit, it is usually 300 ppm by mass or less.

[0025] The feedstock oil is not particularly limited, and various fractions obtained by distilling crude oil, generally called naphtha fraction, kerosene fraction, light oil fraction, heavy oil fraction, etc., can be used, among which naphtha is preferably used. Naphtha and other fractions may be obtained by refining crude oil in an oil refining apparatus, and those refined at other oil refineries can also be used.

[0026] As the feedstock oil, in addition to the above-mentioned crude oil-derived feedstock oil, it is preferable to use a biomass-derived feedstock oil, such as bio-oil, and in particular, a bio-derived naphtha called bio-naphtha. It can be used as a substitute for crude oil-derived naphtha and can greatly contribute to reducing the environmental load. In addition, as the feedstock oil, the above-mentioned crude oil-derived feedstock oil may be used alone or in combination of multiple types, the above-mentioned bio-derived bio-oil may be used alone or in combination of multiple types, and these crude oil-derived feedstock oils and bio-derived bio-oils may be used in combination.

[0027] The biomass as a raw material for the biomass-derived raw material oil such as the bio-oil is not particularly limited, and may be any organic resource derived from animals and plants, excluding fossil fuels, and representative preferred examples include herbaceous biomass, woody biomass, microbial biomass, algae biomass, organic waste biomass, etc. In the production method of this embodiment, among these biomasses, bio-oil derived from biomass may be used alone, or multiple types of bio-oils may be used in combination.

[0028] (Acidic component removal process) The manufacturing method of this embodiment includes an acidic component removal process, which includes an absorption process in which the acidic components contained in the gas component pumped from the compression process are absorbed in a removal solution, and a regeneration process in which the acidic components are removed from the removal solution that has absorbed the acidic components, thereby regenerating the gas.

[0029] The gas component pumped out from the compression step contains acidic components. As described above, typical examples of the acidic components include carbon dioxide and hydrogen sulfide, and these may be contained alone or in combination. When the gas component contains carbon dioxide and hydrogen sulfide, the carbon dioxide content is usually 20 to 100 mol ppm, and the hydrogen sulfide content is usually 350 to 500 mol ppm, although it cannot be generalized because it varies depending on the raw oil used and the conditions in the thermal cracking process and quenching process. These acidic components lead to poisoning of the catalyst used in the downstream refining device, so they need to be removed in advance. In the acidic component removal process, the concentrations of carbon dioxide and hydrogen sulfide, which are acidic components, are preferably 5 mol ppm or less, more preferably 3 mol ppm or less, from the viewpoint of more efficiently extending the catalyst life.

[0030] The removal solution used to remove the acidic components is preferably an amine aqueous solution containing an amine compound. The amine compound can be used without any problem as long as it is a compound that dissolves in water and can absorb acidic components such as carbon dioxide and hydrogen sulfide by reacting with the acidic components, and can recover and regenerate the absorbed acidic components by heating. For example, alkanolamine compounds such as monoethanolamine, ethylmonoethanolamine, aminomethylpropanol, methyldiethanolamine, and triethanolamine; alicyclic amine compounds such as 2-methylimidazoline, etc. are preferably used. Among them, alkanolamine compounds that are versatile and easily absorb low-concentration acidic components are preferred, and monoethanolamine is more preferred.

[0031] For example, when monoethanolamine is used as the amine compound, an absorption reaction for absorbing an acidic component, as shown in the following reaction formula, and a regeneration reaction for recovering the acidic component from the amine compound that has absorbed the acidic component and regenerating the amine compound occur. (Absorption reaction) (C2H4OH)NH2+CO2+H2O→(C2H4HNH3)HCO3(1-1) (C2H4OH)NH2+H2S→(C2H4HNH3)HS (2-1) (Regeneration reaction) (C2H4HNH3)HCO3→(C2H4OH)NH2+CO2+H2O (1-2) (C2H4HNH3)HS→(C2H4OH)NH2+H2S (2-2)

[0032] As shown in the above reaction formulas (1-1) and (1-2), and (2-1) and (2-2), monoethanolamine absorbs acidic components by reacting with them, and the acidic components are removed by the forward reaction, and the original monoethanolamine is regenerated. The absorption reaction is usually carried out at 20 to 50°C, and the regeneration reaction is an endothermic reaction and is therefore carried out at 110 to 120°C. In addition, the removal solution that has absorbed the acidic components is called a rich solution (or "rich amine" in the case of an amine compound), and the regenerated removal solution is called a lean solution (or "lean amine" in the case of an amine compound).

[0033] As the acidic component removal equipment for performing the acidic component removal step, any equipment having a configuration capable of performing the above absorption step and regeneration step can be used without any particular limitation. Figure 1 is a flow diagram showing a preferred embodiment of the acidic component removal equipment.

[0034] FIG. 1 shows that the acidic component removal equipment includes an absorption tower that absorbs the acidic components contained in the gas pumped from the compression process with a removal solution, and a regeneration tower that removes the acidic components from the removal solution that has absorbed the acidic components in the absorption tower and regenerates the acidic components.

[0035] FIG. 1 shows that the absorption tower and regeneration tower are provided with a circulation device associated with them, which circulates the removal solution between the absorption tower and the regeneration tower, and that the removal solution (rich solution) that has absorbed the acidic components extracted from the bottom of the absorption tower is supplied to the regeneration tower, and that the removal solution (lean solution) regenerated in the regeneration tower is supplied to the absorption tower.

[0036] It is also shown that the regeneration tower has a reboiler that supplies heat necessary for removing the acidic components. Since the reaction for removing the acidic components from the removal solution that has absorbed the acidic components is an endothermic reaction as described above, the endothermic reaction is advanced by supplying heat from the reboiler, thereby regenerating the removal solution. Moreover, since the acidic components removed from the removing solution are accompanied by water vapor, they are cooled to remove the moisture and then recovered.

[0037] (Measurement of methanol concentration in the acidic component removal process, disposal and supply of removal solution) In the manufacturing method of this embodiment, in the acidic component removal step, at least a portion of the removal solution is discarded and a new removal solution is supplied so that the methanol concentration in the removal solution that has absorbed the acidic components is 300 mg / L or less.

[0038] As a method of discarding at least a part of the removal solution and supplying a new removal solution so that the methanol concentration in the removal solution that has absorbed the acidic component becomes 300 mg / L or less, for example, (i) A method in which, when the methanol concentration exceeds 300 mg / L, at least a part of the removal solution is discarded and a new removal solution is supplied (hereinafter, the discarding of at least a part of the removal solution and the supply of a new removal solution may be simply referred to as "discarding and supplying the removal solution") to reduce the methanol concentration to a predetermined concentration of 300 mg / L or less; (ii) A method of disposing of and supplying a removal solution before the methanol concentration exceeds 300 mg / L, thereby reducing the concentration to a specified level of 300 mg / L or less; (iii) A method of disposing of and supplying a removal solution so as to maintain the methanol concentration at a predetermined concentration of 300 mg / L or less (e.g., 300 mg / L, 200 mg / L, 100 mg / L, etc.); etc. are preferably mentioned.

[0039] In the production method of this embodiment, any of the above methods (i) to (iii) may be adopted, and any of the methods can stably and inexpensively produce high-quality ethylene and propylene while dealing with a wide range of feedstock oils, particularly feedstock oils containing oxygen-containing compounds. From the viewpoint of more efficiently producing high-quality ethylene and propylene, the above method (i) is preferred. In particular, in consideration of improving quality, the above methods (ii) and (iii) are preferred, and in consideration of efficiency, (ii) is more preferred.

[0040] Considering the stability of the composition of the removal solution (particularly the stability of the methanol concentration in the solution) and ease of measurement, it is preferable to measure the methanol concentration using the removal solution passing through a portion where only the removal solution is present, that is, the removal solution passing through the removal solution piping circulating between the absorption tower and the regeneration tower. Also, considering that there is a good correlation with the methanol concentration mixed in propylene and it is easy to grasp the increase or decrease in the methanol concentration, it is more preferable to measure using the removal solution (rich solution) extracted from the bottom of the absorption tower, as shown in Figure 1.

[0041] The methanol concentration may be measured on a sampled specimen, or may be continuously measured using an online analyzer. In the above methods (i) and (ii), it is sufficient to measure a sampled specimen, but in the above method (iii), when the methanol concentration is to be maintained, it is preferable to continuously measure the methanol concentration using an online analyzer. When measuring sampled specimens, the measurement may be performed once every day or every few days, such as once a day, once every three days, or once every five days, or once or multiple times a day.

[0042] Considering the ease of disposal, it is preferable to discard the removal solution at a location where only the removal solution exists, that is, the removal solution passing through the removal solution piping circulating between the absorption tower and the regeneration tower. In other words, it is preferable to discard either the removal solution (rich solution) extracted from the bottom of the absorption tower or the removal solution (lean solution) regenerated in the regeneration tower. Considering more efficient disposal of methanol, it is more preferable to discard the removal solution (rich solution) extracted from the bottom of the absorption tower, which has a relatively high methanol concentration.

[0043] In the above case (i), the time during which the methanol concentration exceeds 300 mg / L is preferably as short as possible, in consideration of the improvement in the quality of ethylene and propylene, and it is preferable to discard and supply the removing solution promptly after it is determined that the concentration exceeds 300 mg / L. More specifically, the discard and supply of the removing solution is started preferably within 2 hours, more preferably within 1 hour, even more preferably within 30 minutes, and even more preferably within 15 minutes after it is determined that the concentration exceeds the limit.

[0044] In the above case of (i), the amount of the removal solution to be discarded is not particularly limited as long as the methanol concentration after the removal solution is discarded and newly supplied is 300 mg / L or less. From the viewpoint of reducing the amount of methanol mixed into propylene with a greater margin, the amount of the removal solution to be discarded is preferably an amount that makes the methanol concentration 200 mg / L or less, more preferably an amount that makes 150 mg / L or less, even more preferably an amount that makes 100 mg / L or less, and still more preferably an amount that makes 90 mg / L or less.

[0045] In the case of (ii) above, the control value of the methanol concentration at which the removal solution is discarded and supplied is not particularly limited as long as it is 300 mg / L or less. However, from the viewpoint of more reliably preventing the concentration from exceeding 300 mg / L, target values ​​such as 10 mg / L, 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, and 250 mg / L can be set. In the above case of (ii), the time during which the methanol concentration exceeds the control value, during which the removal solution is discarded and supplied, may be the same as in the above case of (i).

[0046] In the above case of (ii), the amount of removal solution to be discarded is not particularly limited as long as the methanol concentration after the removal solution has been discarded and newly supplied is lower than the above-mentioned control value, and cannot be generally determined since it can vary depending on the above-mentioned control value; however, from the viewpoint of reducing the amount of methanol mixed into propylene with a greater margin, the amount is preferably an amount that makes the methanol concentration 80% or less of the control value, more preferably an amount that makes 70% or less of the control value, even more preferably an amount that makes 50% or less of the control value, and even more preferably an amount that makes 25% or less of the control value.

[0047] When maintaining the methanol concentration as in (iii) above, it is sufficient to discard an amount as needed from time to time, and the amount of waste may be, for example, such that the methanol concentration is about 5 to 10 mg / L lower than the methanol concentration to be maintained. In this way, maintaining the methanol concentration as in (iii) above does not only maintain the methanol concentration at the exact same concentration, but also allows for fluctuations of, for example, ±1 mg / L, ±3 mg / L, 5 mg / L, and up to ±10 mg / L. In the case of (iii) above, the target value for maintaining the methanol concentration is not particularly limited as long as it is 300 mg / L or less. However, from the viewpoint of more reliably preventing the concentration from exceeding 300 mg / L, the target value can be set to, for example, 10 mg / L, 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, or 250 mg / L.

[0048] In the above cases (i) to (iii), a more specific amount of the removal solution to be discarded cannot be generalized because it varies depending on the circulating amount of the removal solution; however, when the circulating amount of the removal solvent is taken as 100, the amount is preferably 0.4 or more, more preferably 1 or more, and even more preferably 2 or more, and the upper limit is preferably 15 or less, more preferably 10 or less, and even more preferably 7 or less. The removal solution may be discarded in one go, or in multiple goes, such as discarding a second time depending on the result of measuring the methanol concentration after discarding once.

[0049] Regarding the supply of the removing solution, the point at which the removing solution is supplied may be, for example, a supply line from the absorption tower to the regeneration tower, as shown in FIG. The supply amount of the removal solution may be determined according to the amount of waste, and specifically, may be set to the same amount as the amount of waste in order to maintain the circulation amount of the removal solution. In the manufacturing method of this embodiment, "the same amount as the amount of waste" means that it is not only strictly the same, but also allows for an error of ±5%.

[0050] The disposal and supply of the removal solution may be performed, for example, by disposing of the removal solution first and then supplying it, or by supplying the removal solution first and then disposing of it, or by disposing of the removal solution and supplying it simultaneously. From the viewpoint of more efficient disposal and supply, it is preferable to first dispose of the used removal solution and then supply a new removal solution.

[0051] (Measurement of methanol concentration in the quench process, disposal and supply of quench water) In the manufacturing method of this embodiment, in the quenching step, it is preferable to discard at least a portion of the quenching water used to quench the decomposed gas supplied from the pyrolysis step and supply new quenching water so that the methanol concentration in the quenching water is 90 mg / L or less.

[0052] As described above, when the feedstock oil contains methanol as an oxygen-containing compound, the decomposition gas contains the methanol, and when the feedstock oil contains a compound other than methanol as an oxygen-containing compound, the decomposition gas contains methanol generated by the reaction in the pyrolysis furnace. Since methanol has a property of being easily dissolved in water, methanol in the decomposition gas dissolves in the quench water used to quench the decomposition gas in the quench step. Since the quench water used in the quench step is usually recycled to the pyrolysis furnace in the pyrolysis step, methanol may be concentrated from the pyrolysis step to the quench step. Therefore, by controlling the methanol concentration contained in the quench water, the amount of methanol mixed into propylene can be reduced, and the increase in the methanol concentration in propylene can be further suppressed.

[0053] The control of the methanol concentration of the quench water in the quench step will be described with reference to Fig. 2. Fig. 2 is a flow diagram showing a preferred embodiment of the quench facility. FIG. 2 shows that the cracked gas supplied from the above-mentioned thermal cracking process is cooled by contact with quench water in a quench tower and then supplied to the compression process, that the quench water is extracted from the bottom of the quench tower and supplied from the top of the quench tower, and that the quench water extracted from the bottom of the quench tower is recycled to the thermal cracking process.

[0054] The methanol concentration in the quench water is preferably measured using quench water passing through a quench water pipe, taking into consideration the stability of the quench water composition (particularly the stability of the methanol concentration in the quench water), ease of measurement, etc. For example, as shown in Fig. 2, it is more preferable to measure using quench water extracted from the bottom of the quench tower.

[0055] The methanol concentration may be measured on a sampled sample, or may be continuously measured using an online analyzer. When measuring on a sampled sample, the concentration may be measured once every day or several days, such as once a day, once every three days, or once every five days, or once or several times a day.

[0056] Considering ease of disposal, it is preferable to discard the quench water from a location where only quench water is present, that is, the quench water passing through the piping from when it is extracted from the bottom of the quench tower until it is supplied from the top of the quench tower, and also through the piping from which it is extracted for recycling to the pyrolysis step downstream of the circulation pump shown in Fig. 2. Also, as shown in Fig. 2, if there is a waste line to a drainage facility in the system from which it is extracted for recycling to the pyrolysis step downstream of the circulation pump, this may be utilized.

[0057] The amount of quench water to be discarded is an amount that makes the methanol concentration after the quench water is discarded and freshly supplied preferably 90 mg / L or less, more preferably 80 mg / L or less, even more preferably 70 mg / L or less, and still more preferably 50 mg / L or less.

[0058] A more specific amount of the quench water to be discarded cannot be generalized because it varies depending on the amount of circulating quench water. However, when the amount of circulating quench water is taken as 100, the amount is preferably 0.2 or more, more preferably 0.3 or more, and the upper limit is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less. The quench water may be discarded once, or multiple times, for example, by discarding the water a second time depending on the result of the measurement of the methanol concentration after the first discard.

[0059] Regarding the supply of quench water, the point at which quench water is supplied may be, for example, as shown in FIG. 2, a line from which quench water is extracted from the bottom of the quench tower to be supplied from the top of the quench tower. The amount of quench water to be supplied may be determined according to the amount of waste, and specifically, may be set to the same amount as the amount of waste in order to maintain the amount of quench water circulated. In the manufacturing method of this embodiment, "the same amount as the amount of waste" means that, as with the removal solution, it is not limited to the case where the amount is strictly the same, but also allows for an error of ±5%.

[0060] (Supply of water vapor in the pyrolysis process) In the production method of this embodiment, in the quenching step, it is preferable to discard at least a part of the quench water used for quenching the decomposed gas supplied from the pyrolysis step and to newly supply steam in the pyrolysis step so that the methanol concentration contained in the quench water is 90 mg / L or less. That is, new steam is supplied instead of newly supplying the quench water, or the quench water is newly supplied.

[0061] The measurement of the methanol concentration in the quenching step and the disposal of the quenching water are the same as in the case where fresh quenching water is supplied.

[0062] The newly supplied steam may be supplied in addition to the steam supplied to the feed oil. The supply amount of water vapor may be determined according to the amount of waste quench water, and specifically, may be set to the same amount as the waste amount in order to maintain the circulation amount of quench water. In the production method of this embodiment, "the same amount as the waste amount" means that, as with the above-mentioned removing solution and quench water, it is not only strictly the same, but also allows for an error of ±5%.

[0063] (Other processes) The method for producing ethylene and / or propylene of the present embodiment may include, as a step other than the above-mentioned steps, a purification step for purifying the cracked gas obtained through the acidic component removal step to obtain high-purity ethylene and / or propylene. Representative and preferred examples of the purification step include impurity removal steps using distillation columns such as a demethanization step, an ethane removal step, a propanization step, etc., and rectification columns such as an ethylene rectification column and a propylene rectification column; and reaction steps using a catalyst such as an acetylene hydrogenation column in which acetylene contained in the cracked gas is hydrogenated to produce ethylene, and a MAPD hydrogenation column in which methylacetylene and propadiene (MAPD) ​​are hydrogenated to produce ethylene.

[0064] The refining process may be appropriately selected depending on the properties of the feedstock oil, the required performance of the products ethylene and propylene, and the like. Typically, after the acidic component removal process, the cracked gas is passed through a demethanizer, a deethanerizer, an acetylene hydrogenator, and an ethylene fractionator to obtain ethylene; and the bottom product of the deethanerizer is passed through a MAPD hydrogenator and a propylene fractionator to obtain propylene, thereby producing ethylene and propylene.

[0065] [Ethylene and / or propylene production apparatus] The ethylene and / or propylene production apparatus of this embodiment includes at least a feedstock oil thermal cracking facility, a quenching facility, a compression facility, and an acidic component removal facility, the acidic component removal equipment includes an absorption equipment for absorbing the acidic components into a removal solution, and a regeneration equipment for removing the acidic components from the removal solution having absorbed the acidic components and regenerating the solution, and also includes a removal solution adjustment equipment for discarding at least a part of the removal solution and supplying a new removal solution so that the methanol concentration in the removal solution having absorbed the acidic components does not exceed 300 mg / L; That is it. According to the ethylene and / or propylene production apparatus of the present embodiment, the ethylene and / or propylene production method of the present embodiment can be easily carried out.

[0066] The thermal decomposition equipment, the quenching equipment, the compression equipment and the acidic component removal equipment are as described above in the ethylene and / or propylene production method of this embodiment. The removal solution adjustment equipment of the acidic component removal equipment is also as described above in the ethylene and / or propylene production method of this embodiment.

[0067] The quench water adjusting equipment and the steam adjusting equipment used for controlling the methanol concentration in the quench water to 90 mg / L or less are also as described in the above-mentioned method for producing ethylene and / or propylene of this embodiment.

[0068] The ethylene and / or propylene production apparatus of the present embodiment may also be equipped with the above-mentioned various distillation towers, rectification towers, and reaction towers such as hydrogenation towers for carrying out other steps described above as steps that can be adopted in the ethylene and / or propylene production method of the present embodiment, i.e., the above-mentioned impurity removal step and reaction step. EXAMPLES

[0069] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0070] [Reference example] Ethylene and propylene were produced using an ethylene and / or propylene production apparatus equipped with a feedstock thermal cracking facility, a quenching facility, a compression facility, an acidic component removal facility, and a refining facility, the quenching facility having a quench tower shown in Figure 2, and the acidic component removal facility having the configuration shown in Figure 1. Naphtha having the following properties was used as the feedstock, and a monoethanolamine (MEA) solution was used as the removal solution in the acidic component removal facility. In the acidic component removal equipment, the operation was continued without discharging or supplying the removal solution (amine solution), and the methanol concentration contained in the inlet and outlet gas of the acidic component removal equipment and the methanol concentration in propylene were measured when the methanol concentration in the rich amine solution at the measurement points of the methanol concentration shown in Figure 1 became 14.5 mg / L, 450 mg / L, and 810 mg / L. In addition, the methanol removal rate in the acidic component removal equipment was calculated from the measured values ​​of the methanol concentration contained in the inlet and outlet gas. The above measurement results and calculation results are shown in Table 1. In addition, a graph showing the relationship between the methanol concentration in the rich amine solution and the methanol removal rate is shown in Figure 3. (raw oil) Product naphtha: Properties (density (15℃): 0.70g / cm 3 , vapor pressure (37.8℃): 60kPa, distillation test 90% point: 118℃), oxygen-containing compounds (methyl tertiary butyl ether 50-60 mass ppm *1 , ethyl tertiary butyl ether 40 mass ppm) *1: During the operation of the reference example, the concentration of methyl tertiary butyl ether contained as an oxygen-containing compound in the product naphtha fluctuated between 50 and 60 ppm by mass.

[0071] [Table 1]

[0072] From the above reference examples, it can be seen that the methanol removal rate is 95% or more when the methanol concentration in the rich amine solution is up to 450 mg / L, the methanol concentration in the product propylene is 0 mol ppm, and high quality propylene is obtained. Furthermore, since methanol is not mixed into ethylene, high quality ethylene is obtained regardless of the methanol concentration in the rich amine solution. From these results and the results of Figure 3, it is considered that there is a correlation between the methanol removal rate and the methanol concentration in propylene, and by setting the methanol concentration in the rich amine solution to 300 mg / L or less, the methanol removal rate becomes about 97%, and high quality ethylene and propylene are obtained.

[0073] Example 1 In the above-mentioned reference example, when the methanol concentration in the rich amine solution reaches 300 mg / L, a part of the rich amine solution is discarded and fresh amine solution is fed to reduce the methanol concentration to 150 mg / L. (The amount of the rich amine solution discarded and the amount of the fresh amine solution fed at this time are 24,000 L (24 m 3 The operation was continued by repeating the above procedure to produce ethylene and propylene. The methanol concentration in the obtained propylene was 0 mol ppm.

[0074] Example 2 In the above-mentioned reference example, when the methanol concentration in the rich amine solution reaches 150 mg / L, a part of the rich amine solution is discarded and fresh amine solution is fed to reduce the methanol concentration to 75 mg / L. (The amount of the rich amine solution discarded and the amount of the fresh amine solution fed at this time are 24,000 L (24 m 3 The operation was continued by repeating the above procedure to produce ethylene and propylene. The methanol concentration in the obtained propylene was 0 mol ppm.

[0075] Comparative Example 1 Ethylene and propylene were produced in the same manner as in Example 1, except that the rich amine solution was not partially removed and a new amine solution was not supplied. The methanol concentration in the rich amine solution after 3 days was measured to be 450 mg / L, and the methanol concentration in propylene was 4 mol ppm.

[0076] Comparative Example 2 Ethylene and propylene were produced in the same manner as in Example 1, except that the rich amine solution was not partially removed and a new amine solution was not supplied. The methanol concentration in the rich amine solution after 3 days was measured to be 800 mg / L, and the methanol removal rate in the acidic component removal equipment was 78%. The methanol concentration in propylene was 8 mol ppm.

[0077] From the results of the above examples, it was confirmed that by disposing of and supplying the removal solution so that the methanol concentration of the removal solution does not exceed 300 mg / L, it is possible to remove methanol in the acidic component removal equipment, and as a result, it is possible to reduce the methanol concentration in the propylene obtained as a product, and it is possible to produce high-quality propylene. It was also confirmed that by controlling the methanol concentration of the removal solution to be lower, it is possible to produce higher-quality propylene. On the other hand, from the results of the Comparative Examples, it was confirmed that unless the removal solution is discharged and supplied so that the methanol concentration in the removal solution does not exceed 300 mg / L, it is not possible to remove methanol in the acidic component removal equipment, and as a result, it is not possible to reduce the methanol concentration in the propylene obtained as a product, and high-quality propylene cannot be produced. [Industrial Applicability]

[0078] The ethylene and / or propylene production method and production apparatus of the present embodiment can stably provide high-quality ethylene and propylene at low cost while dealing with a wide range of feedstock oils, particularly feedstock oils containing oxygen-containing compounds, and are therefore suitable for use as an industrial production method and production apparatus for ethylene and / or propylene.

Claims

1. The process comprises at least a feedstock thermal cracking step, a quenching step, a compression step, and an acidic component removal step, in that order; the acidic component removal step includes an absorbing step of absorbing the acidic component into a removal solution and a regenerating step of removing the acidic component from the removal solution having absorbed the acidic component, As the feedstock oil, a feedstock oil having an oxygen-containing compound content of more than 50 ppm by mass is used, discarding at least a portion of the removing solution and supplying a new removing solution so that the methanol concentration in the removing solution that has absorbed the acidic component becomes 300 mg / L or less; A method for producing ethylene and / or propylene.

2. 2. The method for producing ethylene and / or propylene according to claim 1, wherein, when a methanol concentration in the removal solution that has absorbed the acidic component exceeds 300 mg / L, at least a part of the removal solution is discarded and a new removal solution is supplied so that the methanol concentration becomes 300 mg / L.

3. 3. The method for producing ethylene and / or propylene according to claim 1 or 2, wherein in the quenching step, at least a part of the quench water used for quenching the cracked gas supplied from the thermal decomposition step is discarded and fresh quench water is supplied so that the methanol concentration in the quench water is 90 mg / L or less.

4. 3. The method for producing ethylene and / or propylene according to claim 1 or 2, wherein in the quenching step, at least a part of the quench water used for quenching the cracked gas supplied from the thermal cracking step is discarded and fresh steam is supplied to the thermal cracking step of the feedstock oil so that the methanol concentration contained in the quench water is 90 mg / L or less.

5. 3. The method for producing ethylene and / or propylene according to claim 1 or 2, wherein the feedstock oil contains naphtha having an oxygen-containing compound content of 50 ppm by mass or more.

6. The method for producing ethylene and / or propylene according to claim 5 , wherein the feedstock further contains bio-oil.

7. 3. The method for producing ethylene and / or propylene according to claim 1, wherein the acidic component comprises at least one selected from carbon dioxide and hydrogen sulfide.

8. 3. The method for producing ethylene and / or propylene according to claim 1, wherein the removing solution is an aqueous amine solution.

9. At least a feedstock thermal cracking facility, a quenching facility, a compression facility, and an acidic component removal facility are provided; the acidic component removal equipment includes an absorption equipment for absorbing the acidic components into a removal solution and a regeneration equipment for removing the acidic components from the removal solution having absorbed the acidic components and regenerating the removal solution, and also includes a removal solution adjustment equipment for discarding at least a part of the removal solution and supplying a new removal solution so that the methanol concentration in the removal solution having absorbed the acidic components is 300 mg / L or less. Ethylene and / or propylene production equipment.

10. 10. The ethylene and / or propylene production apparatus according to claim 9, further comprising a quench water adjusting unit configured to discard at least a portion of the quench water used to quench the cracked gas supplied from the thermal cracking unit and to supply new quench water so that the methanol concentration in the quench water is 90 mg / L or less.

11. 11. The ethylene and / or propylene production apparatus according to claim 9 or 10, wherein the thermal cracking facility for the feedstock oil comprises a steam regulating facility for supplying steam so that a methanol concentration contained in quench water used to quench the cracked gas supplied from the thermal cracking facility is 90 mg / L or less.

12. The ethylene and / or propylene production apparatus according to claim 9 or 10, wherein the removing solution is an amine solution.

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