JPS63502584A - Selective treatment of olefin-containing gas by Meler method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Selective treatment of olefin-containing gas by solar method recovery of olefins from, especially by adsorption using selective physical solvents. It relates to the recovery of olefins from cracked hydrocarbon gases.

Olefins have a variety of petrochemical uses. Ethylene is a mainstay in the petrochemical industry Department. One major use of ethylene is packaging, communications, construction, automobiles, and household use. Low-density and high-density polyethylene used in various fields including product manufacturing It is a transformation of Other major uses include oxidation to ethylene oxide and ethylene dichloride. chlorination.

Generally, olefins are produced by thermal or catalytic cracking of gaseous or liquid hydrocarbons. It is produced by decomposing gas to produce cracked gas. For many years, cracked gas In order to recover medium and high purity ethylene by separating or concentrating the components of Broadly speaking, three methods have been used. In one method, charcoal or silica Use a solid adsorbent such as The other two methods utilize two types of fractional distillation. . That is, the first method is a straight low-temperature fractionation method, and the second method is a steam distillation method. Absorption into a low-pressure liquid, thereby avoiding extremely low temperatures in a fractionation system It is.

A, 11. Co-authored by PraLL and N.L., FoskeLL - Low Temp eratureFracLionation or Light Hydroc arbons@, Transactions of the American 1nsiLuLuLe or Chea+1cal Engineers.

During the 1960s, as described in Vol. 42.1946, page 149. At this point in time, the majority of ethylene plants in operation were using low temperature fractionation methods, i.e. An improved method of gradual liquefaction was applied.

Current typical olefin plastics that use cryogenic fractionation for ethylene recovery As shown in Figure 1, the main raw materials used in this project are ethane, propane, butanes, and naphtha. , gas oil, synthetics and other hydrocarbons derived from petroleum cracking. These originals The material is previously treated and decomposed using a conventional steam cracker. Decomposition gas is 81 Leave the decomposition furnace at 5-1,200°C. These gases have a temperature of less than 210 Kpa. Rapidly cool to 27-49°C. Steam feedstocks can also undergo catalytic cracking if operating conditions are suitable. You can also do that.

Depending on the feedstock and the severity and selectivity of the cracking, the cracked gas may be hydrogen, ethane, or oxidized carbon. element, carbon dioxide, acetylene, ethylene, ethane, methylacetylene, propadiene Ene, butanes, C2s, CTCs non-aromatics, benzene, toluene, xylene , ethylbenzene, ethylene, C.

~200°C gasoline, 200+”C fuel oil, and water.

These gases are compressed to a pressure of about 2.800 to 4,200 Kpa using a multi-stage compression device. do. During compression, some heavy hydrocarbons and water separate. Separation, depending on composition Once stabilized, hydrocarbons can be used as part of the feedstock for the fractionation series. can. After compression, the uncondensed gas is further passed through molecular sieves or activated alumina. and dry to a water dew point of less than -100°C. The cracked gas is processed using a multi-stage cracked gas compression device. Drying may be carried out at an intermediate pressure level corresponding to the intermediate pressure of .

Second, complex systems that utilize large-scale heat exchange and ethylene-propylene refrigeration systems A combination of systems cools the drying gas to a cryogenic temperature of -129°C. child The purpose of cooling is to convert the methane and hydrogen present in the cracked gas into ethylene and heavy hydrocarbons. It is separation of elementary classes. The remaining methane/hydrogen flow is further separated and sent to a cryogenic cooling system. Separation occurs within the column into a hydrogen-rich stream and a methane-rich stream. Preferably , before hydrogenating the acetylene to the desired product. A portion of the separated hydrogen stream is further purified using an adsorption method. On the other hand, for methane The enriched stream is used as fuel gas for the steam cracking stream.

Separated liquid streams containing ethylene and heavy hydrocarbons are processed into low to high pressure demethanizers! ! Further fractional distillation is performed at (1,100 to 3,200 Kpa). Low pressure demethanization equipment Ethylene refrigerant is used for the top condenser, while the high pressure demethanizer is For condensation, low-temperature propylene refrigerant is used, sometimes in conjunction with a pressure reduction device. do.

Methane becomes an impurity when present with ethylene products, so demethanization equipment The standards imposed on methane at the bottom are extremely strict. Similarly, to the demethanizer Recover most of the ethylene present in the feedstock, reducing losses and The top product of the demethanizer is recycled to the cracked gas compressor to further increase this demand. Minimizes the need to recover desired product.

As is well known, olefin plants are energy intensive. 50/ 5G hard 64 per year using currently available methods for condensate and ethane/propane feedstocks. 0. In the case of an ethylene plant that can produce ethylene, the charging gas The conditions for the compressor are 37. Goo~40. Can be changed between Goo horsepower (PS) , whereas for polypropylene refrigeration system it is 1 g, Goo ~ 22 ,0OOPS. And the place of ethylene refrigeration system If so, 4. G.

It can be changed in the range of 0 to B, 0OOPS. Therefore, how and where to apply Depending on the desired product slate, the total compression energy is between 60,000 and 70,000 OO Since it is within the range of PS, the amount of invested capital is large, and it is The operating costs will be significantly higher. That is, desired product slate, available raw materials , the severity and selectivity of the cracking process, and the separation technology used, but the Specific energy consumption is 3,10tl-7,500Kc per 1kg of ethylene product It is al. This is the total heat of ethylene 4 m 12,017 Kcal ~ 25.4 $ It is 62.45.

Here, the cracking system for olefin production has already been improved and improved to a high operational efficiency. It is important to know that For example, a steam cracker requires a considerable amount of fuel. Even if it is necessary, decomposition occurs at extremely high temperatures, so it is difficult to Most of the energy consumed can be recovered by skillfully using waste heat recovery equipment. Wear. For example, only 3 to 5% of the energy released by pyrolysis of high-temperature gas is It just loses its charm. This loss also occurs in the exhaust stack. in this way Most of the energy recovered is used to compress the cracked gas and It is used to give frozen food. Therefore, the majority of olefin plants minutes of energy associated with the cooling and fractionation series that separates each component of the cracked gas stream. consumed.

According to a recent article, 23 companies operate 32 olefin plants in the United States. are doing. This article was originally published on September 2, 1985. On page 39 of the group magazine, Teamelt says “New Capacity Force” es Ethylene Producers to Aim ror Lowe r　Co5ts, FlexibiliLy''. 1985 Currently, the total ethylene production capacity of these 32 plants is approximately 1,700,000)7 It was 7 years. If the standard were extended worldwide, the total ethylene production capacity of 37 countries would be It was approximately 4,900,000 tons. The raw materials used in these plants are Tan, propane, butane, refinery gas, naphtha, gas oil, natural gas liquids (NGL) ), liquefied petroleum gas (LPG), etc.

Europe's newest ethylene cracker, an example of the newest ethylene plant began production around October 1985 at a plant in Mossmorran, Scotland. It started. The plant will use raw materials in the form of a $16 billion joint venture. It operates six cracking furnaces that use ethane as feedstock. As is well known, this minute The plant uses gas turbines to drive process gas compressors. It is the first of its kind, and also uses turbine exhaust gas as preheating combustion air for the plant. This is the first plant to be used. This plant increases ethylene production capacity However, due to the lack of competitiveness, the UK and West Germany produced approximately 600,000 tons/ A cracking plant with a production capacity of 2018 has been forced to shut down.

For many years, the problem of imbalance between production capacity and demand has affected the olefin production industry. has been eroding. Despite this, it has definitely become larger and more complex. New plants incorporating the latest technology are being built. However, most In this case, the reason for the existence of a new plant is that raw material resources are cheap and that the latest technology potential to compete well with other plants and penetrate the existing market. and/or the potential for market expansion. As the newest plant begins operation, the old plants may be forced to shut down, reduce production, or reduce production costs. Ru.

Measures that can be taken to reduce costs include processing a wide variety of raw materials depending on market conditions. The decomposition equipment may be made versatile so that it can be used for various purposes. Second cost reduction measure supply and energy, including systems that can be used in conjunction with various equipment. It involves modifying existing plants to optimize the energy conditions. Third means makes full use of computer controls to maximize plant operating efficiency. That's true. The fourth method is to take advantage of advanced technology to eliminate obsolete equipment within factory facilities. The idea is to replace the plant with a more efficient one.

The next step in improving olefin production efficiency is to extract olefins from cracked gas. This involves replacing the low-temperature plant that collects and separates refins. Solvents such as Kniel method After giving up on absorption systems, I became accustomed to low-temperature fractionation for many years. The price paid for this was relatively high. This is because low-temperature fractionation requires extreme dehydration. , and to achieve this, energy-intensive ethylene propylene refrigeration is required. This is because the system is used.

1, L, Ne1sonlF-PeLroleua Refinery Eng ineering-1 3rd edition, McGrav-Hill Book Compa ny+ Inc., New York.

According to page 651, around 1948, alcohol, ethyl ether, In the production of many chemicals such as glycol and tetraacetyl lead, basically heavy What was needed was ethylene. Production capacity was 1,500 tons per day in 1948. A plant with However, alcohol for hydration It does not include plants that produce tonne. These plants mainly contain ethane and A pyrolysis-type absorber station that produces fuel gas using a pan. Figure 2 shows a typical example of the conventional absorption method in which cracked gas is sent to a ripper column. , as illustrated in FIG. 1 of U.S. Pat. No. 2,573,341. The solvent was being sent to the first member of the series, the deethanization column.

The absorption method for absorption type recovery plants is “PeLroleu+5Refiner”. y Figure 2 given on page 652 of Engineering-1 and the US patent Using the same method as shown in Figure 1 of Publication No. 2,573.341, , Ludvig Kniel and 111°Slagerh<”Che+5ica "Engineering Progress", Vol. 43, No. 7. Discussed in the article published on pages 335-342.

Mon5anLo Chemical Co. located in Texas City, Texas.

This ethylene plant is mainly used to produce ethylene, and mainly It was operated using ethane and propane. A typical example of the final ethylene yield is , 75% by weight from ethane, 48% by weight from propane, and 2% by weight from gas oil. It was 5 to 32% by weight. When decomposing propane, if the conversion rate is about 45%, The yield was approximately 16.7% by weight of ethylene and 15.8% by weight of propylene. low temperature Absorption separates ethylene along with ethane and heavy components, and in the process aromatic A distillate was formed, containing more than 50% by weight benzene/toluene and Lopencune and cyclohexane contained significant amounts of naphthenes identified.

This paper contains representative analytical values for ethylene-containing streams. (a) Typical coke oven gas, (b) refinery exhaust gas, and (c) propane as raw materials. , the effluent gas from the pyrolysis unit that produces the largest amount of ethylene. For these raw materials, The ethylene concentration is 4-27 mol%, and the dilute fraction lighter than ethylene is 94-17 mol%. mol%, so it is a large amount that can economically recover ethylene or ethylene + propylene. Half of the industrial gases were not considered.

Ludwig Kniel “+Petroleum Reriner”, Vo lume 27°No, 11, in a paper published in November 1948, A fractionating absorber that is essentially the same as the absorber stripper listed in the text. For the design of ethylene in the pyrolysis gas obtained from the decomposition of propane The explanation is given using the separation of methane. In plant operation, this The performance of such a fractionating absorber, both in terms of recovery and purity, is determined at design time. It was clear that the conditions had been exceeded. The reason is that the diluted oil used is quite The fact that it contains a proportion of aromatics, especially benzene, or the provision of an intercooler This is thought to be the result of overlapping recirculation between the plates. Ta.

Joe J, 1fcaLherby Hydrocarbon Process sing & Pet-roleum Ref'1ner-, April 1962, Volume 41. 295,0OON+s for the paper published in No. 4 A low-temperature absorption plant that recovered 401 units of propane from wet natural gas per day is described. has been done. This plant has a beam boiler but no intercooler. A fractional distillation absorber was used.

This column not only absorbs hydrocarbons from the gas stream, but also absorbs methane and ethane. was fractionally distilled to give the deethanized product. Regarding a part of C7+ fraction This was then pumped to the top of the column as absorbent oil. Echire For glycol, use the upstream side of the gas exchanger and the ethyl alcohol using ammonia as a refrigerant. This is injected upstream of the feed gas cooler that cools the Renplant to -7°C. was. Gas exchangers and feed gas coolers absorb approx. / 2, which lowers the average effective absorber temperature and causes it to exit the top of the column. The oil content of the residual gas reaches equilibrium with the oil at a minimum temperature of 17°C, and this causes This minimized oil loss.

Olefins are extracted from cracked gas, refinery gas and syngas containing these unsaturated compounds. A number of methods are known in the art of solvent absorption technology to recover carbon. some The method involves using the solvent as a solvent in an absorber stripper column equipped with a reboiler. Aromatic absorption oil is used as a solvent. Such a method is described in the following U.S. patents: It is stated in the official gazette.

2.187,631.2,282,549.2,308,856°2.325, 379.2, 357, 028.2, 433.286: 2.455, 803.2, 570,066, 2,573,341; 2.588,323.2,708,58 0.2,849,371°3.055,183.3,082.171.3,34 9.145:3.686.344.4,072,604.4,479,812° Based on U.S. Patent Application No. 717.264, filed December 7, 1946. U.S. Patent No. 2.573.341 to Ludwig Kniel, issued: Feedstock for rectifiers and absorbers, also known as absorber strippers. coke with ethylene content of 4.0%, 5°0% and 27.0%, respectively. Olefinic hydrocarbons, especially high purity, are extracted from furnace gas, refinery exhaust gas, and pyrolysis gas. This article concerns the method for recovering ethylene. The column or tower has a reboiler at its bottom. It is also equipped with an intercooler to remove the heat of extraction. Tower gas is fuel gas The bottom gas has a reboiler at its bottom, and a condensate for the top gas. deethanizer (a portion of this condensate is returned to the deethanizer column as reflux) supply to the chemical column. The lean oil proportions are as follows: feedstock 1:4.2: below, that is, below the amount that ensures retention of 99 mol% of the ethylene entering the rectification/absorption tower. Ru.

Nelson, on page 651 of his book, states that U.S. Pat. The absorption system illustrated in Figure 1 was mainly used for ethylene recovery around 1948. He said that this was the method he had been using. In the mid-1950s, propane and butane A large number of absorption plants that utilize frozen diluted oils such as oils and light aromatic fractions are in operation. It was there.

Published by PeLroleua+ Publishing Co. in 1970. T, S, B, Zdonik, E, D, Green, P, Halee According to "Manuractur-ing ELhylene", page 85, Some plants were still in operation, but their numbers were decreasing.

On the other hand, all newly constructed plants separate ethylene from light hydrocarbons. Some form of low-temperature fractional distillation was used to achieve this. Ethylene production capacity per hand In the case of approximately 450,000 million yen), it is economical to consider a refrigerated absorption plant as an alternative to low-temperature distillation. It was comparable to a harvesting plant.

As ethylene plants become larger, even if low-temperature fractionation plants are Even with the use of more complex refrigeration systems, the effects on solvents in absorption plants are Due to the large heating and cooling loads involved, absorption plants have lower operating costs and plant costs. It has become uneconomical from a strike point of view.

In this way, the 20 years from the end of World War II until approximately 1965 were a classic period. It appears to have been a competitive stage. The winner was the low-temperature fractionation plant, which As a result, solvent adsorption plants disappeared. The reasons why the market made this decision are summarized below. Watch.

No. 2,573,341 as the dominant adsorption method by Nclson. If we refer to Figure 1, we will recover and separate olefins from pyrolyzed hydrocarbon gas. As the dominant adsorption method by Nelson, U.S. Pat. No. 2.573.34 Referring to Figure 1 of No. 1, the recovery and recovery of olefins from pyrolyzed hydrocarbon gas There are few reasons why plants using the Kniel process lost the competition for separation. There are seven of them. First, the Kniel method is not applicable for separating methane from hydrogen. Although this separation is not possible, this separation is necessary for the hydrogenation of acetylene to ethylene. It should be noted that it was important. For this reason, hydrogen was used as a fuel. However, from an economic point of view, this was a wasteful method.

Second, the Kniel process allows continuous production of aromatic fractions and supply of absorber oil. The focus was on retaining the fraction in the aromatic system to the extent necessary to maintain the It seems like that. This is due to the fact that the loss of lean absorbing oil is significant and this loss This means that fuel had to be used for In fact, the decomposition furnace designed to produce aromatic absorber oils rather than It is thought that

Third, the above-mentioned U.S. Pat. No. 2,573,341 discloses an absorber stripper. – Methane is removed by this column without loss of ethylene in the column top stream. and a larger than expected amount of methane was removed from the absorber stripper column. methane from entering the bottom material of the system (because such amounts of methane Adjust the concentration of the top gas from each of the ethanization tower and ethylene fractionation tower to the desired concentration. making it impossible to condense the reflux in these columns at the temperatures required for (because it tended to interfere with the operation of these towers) was stated to be essential. has been done. January 8, 1951, during the prosecution of U.S. Patent Application No. 717,264. According to the amendment submitted to Loss of ethylene in the line neck or methane at the bottom of the absorber. It has been found that this tends to accumulate and contaminate the ethylene product. child As adopted and claimed in U.S. Pat. No. 2,573,341, The solution was to install a demethanization column. However, the absorber If the stripper column is properly designed, this demethanization column is superfluous. It is.

Fourth, about 96% of the methane was rejected, which means that 4% of the methane contained was This indicates that it existed together with Ren products. This figure is 97%. certified by purity. However, the requirements for purity are definitely higher. It's coming. and satisfies the conditions that the Knie 1 type absorption method could not satisfy. The economic burden for this is also increasing.

Fifth, absorber/stripper columns are used to decompose, collect and separate gases. In contrast, by removing hydrogen and methane from refinery exhaust gas feedstock in advance, This seems to have been installed to ease the conditions necessary for decomposition. moreover, The dilute oil fraction used in the absorber stripper column was 54.0%. of benzene, toluene, and 17.6% pentanes and ordinary dilute oil. The carbon dioxide was also composed of fairly light hydrocarbons.

Sixth, the above publication indicates that the method limits the product to ethylene; Propylene is sent to a heating machine and decomposed, and acetylene is completely ignored and recycled. It was not versatile enough to produce desirable by-products such as tyrene. Furthermore, at that time Even though there was a market for ropyrene and undoubtedly for butadiene as well. In order to use the aromatic distillate as an absorber oil, it is possible to The olefin fraction, which is heavier than ethylene, was recycled to the cracking furnace.

This is another economically wasteful aspect of this method.

Seventh, the 1neil method uses only temperature and lean oil flow rate. It restricted the freedom of driving. However, pressure can also be used as a control factor It was something. Neglecting this application caused several problems.

Ludwig Kni filed in prosecution of U.S. Patent Application No. 717,264 According to el's affidavit, as of February 1, 1950, Lum5ui+ Three Neil method absorber plants were constructed by the Company. was. One of these absorber plants suffers from loss of absorber oil. If it had been large, the designer should have taken some measures.

One such measure is shown in Figure 1 of U.S. Pat. No. 2,573,341. The heavy final fraction obtained in the oil and gas separator, which is The first step was to use oils with high molecular weight, such as heavy final distillates that could not be It should be. However, at that time, there were few absorber molecules available for absorption, and It is known that performance is reduced. Reduced loading capacity is caused by large solvent stocks, large It meant a shaped pump, a large amount of reflux, etc. This measure was clearly not adopted. It was.

Another measure is to produce absorber oil in-plant, thereby regulating losses. It should have been done. For example, low partial pressure and high steam ratio high partial pressures, low vapor ratios plus long residence times maximize aromatics production. It is known to grow in size. Therefore, by adjusting the operation of the cracking furnace, Producing the desired amount of aromatics to replenish oil is a relatively simple matter. There should have been. Therefore, this measure was adopted. However, in later years As this method became fixed in the production of aromatics, it was accompanied by production has declined and clearly lost its competitiveness to cryogenic fractionation methods.

The Kniel adsorption method therefore appears to have the following problems.

A. Wasteful combustion of hydrogen, propylene and acetylene.

B. Excessive loss of aromatic absorber oil and distillate obtained from the absorption process Replenishment by. This reduces ethylene production.

C. Separate methane from ethylene to produce ethylene of sufficiently high purity. It is said that a separate column (demethanizer) must be installed to An obvious need.

D. Unable to meet growing demands for ethylene purity and ethylene recovery. thing.

Parent patents and applications related to solar processes identify two modes of implementation, namely an extraction flash operation. Gaseous and liquid hydrocarbons are extracted from natural gas streams through extraction and extraction strip operations. Selective physical solvents were used for recovery.

U.S. Patent No. 4,421,535, U.S. Patent No. 4,511,381, U.S. Patent No. 4.526 ．． No. 594 and No. 4,578,094, and U.S. Patent Application No. 758. No. 351 and No. 759,327, the solar method Extractive flash operations extract a natural gas stream with a selective physical solvent and remove the extraction solvent. Flash processing, and then compressing, cooling and condensing the target C2 hydrocarbons. It will be. Next, the condensed hydrocarbons are selectively demethanized to give a predetermined C, 10, C5 10 or C4+ hydrocarbons and excluded C3, C++C* or C8 The 10 Ct+C3 hydrocarbons are recycled to the extraction process. This extraction flush operation “Gas Processors Re” published on October 14, 1985 porji magazine (P, O, Box 33002. Tulsa.

0k74153. US), pages 7-8.

U.S. Patent Application No. 784,566, U.S. Patent Application No. 808.463, U.S. Patent Application No. 828,988 No. 828.996, the solar extraction process The tripping operation consists of an upper extraction zone and a lower stripping zone. It consists of contacting a feed gas stream with a selective physical solvent in a column. gas is It flows into the column below the extraction zone and rises to contact the dilute selective physical solvent. child After the solvent enters the extraction zone at the top of the column, it flows countercurrently to the rising gas flow. to descend. Contact occurs at a mass transfer surface such as a filling tray or distillation tray. extraction The solvent leaving the bottom of the zone is rich in 01 heavy hydrocarbons.

This 0.1 minute rich solvent enters the stripping zone of the column and descends to the bottom of the column. Contact with stripped steam rising from the glue boiler. Stoli Depending on the purpose of recovery, the steam used for the process is used when the purpose is to recover ethane and heavy hydrocarbons. In the case of oxidation, the main component is undesirable components such as methane. Also, If the purpose is to recover propane and heavy hydrocarbons, methane and ethane It is the main ingredient.

Regarding the potential for cost reduction in olefin recovery plants, this is possible. The location is a cryogenic cooling train that separates hydrogen, methane, and ethylene fractions. workman Many systems are capable of performing such separation using less energy-intensive means. Effective in existing olefin plants. In other words, the demethanation column has extremely low Low-temperature fractionation plants are particularly energy-intensive as they require high temperatures. It is. Therefore, there is a need for an improved method that eliminates the need for demethanization columns. .

The third area in need of improvement is reducing energy consumption at a reasonable cost. By doing so, we achieved an ethylene recovery level of over 98% and an ethylene recovery level of over 99.9%. This is an area where high purity ethylene is produced.

It is therefore an object of the present invention to extract from a gaseous stream containing olefins to a predetermined extent. The objective is to provide a method for separating and recovering hydrogen.

It also separates and recovers methane to a certain extent from gaseous streams containing olefins. It is also an object of the present invention to provide a method for accommodating.

Another object of the invention is to convert olefin-containing gases into hydrogen, methane and C The object of the present invention is to provide a method for separating into hydrogen acetate products.

A further object of the present invention is to reduce solvent losses and energy consumption over conventional methods. while hydrogen, methane and C2=deca hydrocarbon gases are extracted from the olefin-containing gas stream. The purpose is to provide a method for separating and recovering.

Yet another object of the present invention is to extract hydrogen, methane and C1=deca hydrocarbon gas from pyrolysis gas. can be separated and recovered, and can be retrofitted and incorporated into existing olefin production equipment. The objective is to provide an extraction plant that can.

Yet another object of the invention is that it can be used as part of a novel olefins manufacturing facility. , to provide the above-mentioned extraction plant and method.

According to the above objects and principles of the present invention, surprisingly, hydrogen-rich streams, methane Highly pure methane and high purity ethylene. When separating and recovering Cx = decahydrocarbons, a considerable proportion of unsaturated Continuously arranged stream of sweet, compressed dry hydrocarbon gas containing Japanese hydrocarbons A dilute selective physical solvent is sent in countercurrent through two extraction columns with at least one rich solvent bottom stream by regenerating the rich solvent to produce a lean solvent. and at least one distillation group producing at least one of the above three products. When sent to a column, the above three products can be separated and recovered from the above hydrocarbon stream. Found. At least one extraction column is an extraction strip column.

Each extraction/strip column has a strip sexidine with heat input means, and It has extractor sexidine on its top. One side of extraction/strip column Both are located above the extraction section and receive flow from the top of the column. The purifier consists of a partial condenser, an accumulator, and a reflux path leading to the top of the column. A retaining section can be attached. Each extraction/stripping column forms part of a solvent circuit do. The same solvent can be used for both circuits.

Two extraction columns and one or two distillation columns can be arranged in any of three ways. They can be arranged according to the following aspects.

In two of these three configurations, the three products are placed in three of the four columns. It can be recovered as or from the top stream of the column. In either aspect, The compressed and dried hydrocarbon gas subjected to the sweetening treatment is transferred to an ethylene extraction column (EE). C) to the center of the first extraction column.

The configuration of these embodiments, the main components of the top and bottom streams, the column designations, the solvent flow rates and and one or two circuits as shown in Table 1. Abstracts in these embodiments The configuration of the output column is EEC/MEC, EEC/MPC and EEC/MEC/FV. can be displayed.

EEC/MEC! In case 3, the top ES stream is partly refluxed and partly methane extracted. The output column (MEC) sends it to a certain MEC column. And the bottom flow is the raw material force, ram (RPC) to the first distillation column. The first distillation column is the first solvent circuit. The dilute solvent is regenerated and a C8=deca hydrocarbon product stream is produced. 2nd extraction The ram produces a hydrogen-rich gaseous product stream as its top stream and methane production. The process produces a concentrated solvent bottoms stream that is sent to the second distillation column, which is the organic solvent column (MPC). Ru. The second distillation column produces a methane-rich gas stream as an overhead stream, and As the bottom stream, the solvent for the second solvent refill is regenerated.

EEC/MPCM3-like TEHA, ethylene extraction column (EEC) is a concentrated solvent stream Most of the methane, as well as ethylene and other C20 hydrocarbons, are extracted and A hydrogen-rich gaseous product stream is produced as the top stream. This concentrated solvent stream A second extraction column that regenerates the dilute solvent for the first solvent circuit and is a methane product column. a first distillation producing C1+ hydrocarbons as its top stream to the central part of the Send to column. This column has a methane-rich gaseous product stream as its top stream. and a concentrated solvent stream containing C20 hydrocarbons. This dark The thick solvent stream is sent to the second distillation column, which is the feed column (RPC). This distilled color The system generates a third product stream of C-oxygenated hydrogen and provides a dilute solution for the second solvent circuit. regenerate the agent.

In the EEC/MEC/FV embodiment, the ethylene extraction column is an extraction stripper column. ram (EEC) extracts ethylene and heavy hydrocarbons and produces a concentrated solvent bottoms stream. to be accomplished. This stream is sent to the distillation column, or feed column, where the dilute solvent is regenerated. and Ct=decahydrocarbon product is formed as its top stream. generally strip Sections are not provided, but may be included if required according to methane and hydrogen standards. A dilute solvent stream is sent to the top of a second extraction column (MBC) which may be provided with Then, the top EEC stream is sent to its bottom. The second extraction column (MBC) is EEC. Although the operating pressure of the MBC is higher than that of the gas-liquid mixture in the MBC, Must be below critical pressure. The MBC top stream is a hydrogen-rich gas product. Ru. The bottom stream is flashed and the methane is sent to an ethylene extraction column. A gas product stream rich in gas and a dilute solvent are produced.

In the EEC/MBC embodiment, one product from the extraction column and the distillation A product with two columns is obtained. In addition, in the EEC/MPC mode, the extraction Two products are obtained from the ram and one product from the distillation column. Ru. In the EEC/MBC/FV embodiment, one product from the extraction column , and two products are obtained from the distillation column.

Although it is not necessary to compress the cracked gas to the typical pressure of 3.600 Kpa, for extracting ethylene and heavy hydrocarbons from cracked gas or refinery gas. needs to be compressed to a pressure of about 2,200 to 3.200 Kpa.

The method of the present invention utilizes a selective physical solvent to scrub the gas stream. By using it as a fuel and preferentially separating specific hydrocarbons from it, The components of the compressed and dehydrated cracked gas that has been sweetened at the olefin plant are Apply the solar method technical idea of separation. For other points regarding solvents, See US Patent Application No. 808,463.

For purposes of the present invention and to explain its advantages over the prior art, the following Detailed explanation of the invention from the low pressure inlet to the cracked gas compressor representing one confluence point. Start explaining. This is because the production, or decomposition, of ethylene is outside the scope of the present invention. This is because that. The ethyl alcohol that enters the deethanization column as the main product stream of the present invention The ren-containing component stream is the second confluence point. This is because it is separated into individual products downstream. This is because it is also outside the scope of the present invention. Other products of the invention are hydrogen-rich a methane-rich gas stream, and a methane-rich gas stream. These three products, namely The tyrene-containing streams, methane-rich streams and hydrogen-rich streams are now conventional It should be handled in the same way as the law.

Thus, the method of the present invention can be applied to cracked gas in olefin plants, refinery flue gas streams, etc. , methane and hydrogen gases present in a coke oven gas stream or a syngas stream. Relates to the separation of hydrocarbons and heavy hydrocarbons.

The technical concept of the solar method is to generate any olefin-containing gas derived from any feedstock oil. Because it can be applied to current energy-intensive separation methods, -Ra method has an annual production capacity of 49,000 tons of ethylene, and is currently in operation. Potentially suitable method for retrofitting ethylene plants around the world in Ru.

In the schematic diagrams of olefin separation in Figures 1 and 3, three steps are typical of olefin separation. common and identical to the implant plant, and the method of the present invention includes decomposition, waste heat recovery, and and deethanization, as well as subsequent processes downstream e.g. ethylene/ethane fractionator. , depropanization equipment, propylene/propane fractionator, debutanization equipment, etc. Ru.

The waste gas required to compress the charge gas is replaced by a solar process in the low-temperature fractionation plant. It can be suppressed by increasing the amount of energy. This is because the solar extraction method separates the components. This is because high pressure is not required for this purpose. Similarly, acid gas treatment and dehydration are also performed at low pressure. can. The need for dehydration can also be significantly reduced. This is because in the solar method, the decomposition gas requires cryogenic temperatures to separate the desired ethylene and heavy hydrocarbons from the gas stream. That's because there isn't. Therefore, in the application of the solar method technical concept, simply glycol Dehydration is sufficient.

Solar extraction equipment does not require extremely low temperatures, so it There is no need for low-temperature level refrigeration, which is required in conventional refrigeration systems. Additionally, extract The device separates hydrogen from methane, thereby producing two separate gas streams as products. It can be manufactured by The Ct=10 product from the solar process equipment is the light component of the ethylene product, In other words, since it meets the standards for methane and hydrogen, downstream processing in conventional deethanization equipment is not possible. It is suitable for the reason.

The cracked gas leaving the waste heat recovery device is processed in a multi-stage compressor at 1,100-3, Compress to desired pressure in the range of 200 Kpa. Prior to extraction, apply compressed gas as appropriate. Cool to a temperature below -29°C. The cracked gases are transferred to the extraction section and then to the side The only component shall be a stripping section with a bottom reboiler. into an ethylene extraction column (EEC) that produces Depending on the feedstock and the severity of cracking. If an excess amount of methane is present in the cracked gas, the ethylene present in the cracked gas is For extremely high recovery rates, e.g. 98-99%, this color A partial condenser can be installed at the top of the system to generate reflux for the rectification section. Ru. This minimizes the loss of useful ethylene in the top stream. You can get it.

Therefore, the EEC consists of a rectification section with a condenser at the top, a selective physical solvent a central section for extracting ethylene and heavier hydrocarbons, and a side/bottom section for extracting ethylene and heavier hydrocarbons. Can consist of a bottom stripping section with a boiler. deer stripper with a top extraction section and suitable side and bottom reboilers. An extraction column with a reboiler consisting solely of a gas section is equally useful. Needless to say, this is a good option for recovery in terms of capital and energy consumption. They can be used depending on the optimization of economic parameters.

The purpose of the extraction section is to allow the cracked gas flow to flow into the bottom of the extraction section and 0.1 to 70 m' per 1100 ON'' of gas flow, depending on the composition and flow rate of A descending selectivity physical feed supplied to the EEC with a solvent flow rate selectively adjusted within the range of In contact with the solvent, fill trays or fractionation trays or HIGEEE ( TM)) from the cracked gas stream rising in a mass transfer medium such as The goal is to recover quality hydrocarbons. HIGEE is Imperial Chmi It is a trademark of Cal Industries. Contained in cracked gas during extraction A portion of the methane present is simultaneously recovered by physical solvents.

Efficient use of moving media from the solvent stream exiting the bottom of the extraction section of the EEC Stripping undesired methane by Stripping steam is on the side Preferably, it is generated by heating the concentrated solvent stream in the top and/or bottom reboilers. However, the combustible gas stream may also be obtained from an external gas source. Thermal energy source is external or waste heat recovered via a lean solvent circuit. . Essentially, the ethylene that exits the bottom of the EEC stripping section Hydrocarbon-containing solvents are undesirable, such as methane, according to standards for ethylene products Do not exceed the allowable amount of ingredients.

Strips undesirable components from concentrated solvents and transfers them to the extraction section. In the process of extracting the stripped vapor associated with the cracked gas, It is desirable to recover the vapor leaving the top of the extraction section with a recovery rate of 98-99%. However, some of the desirable constituents such as ethylene are entrained. Meta in the cracked gas stream The composition of the gas and hydrogen components and the flow rate of the solvent sent to the extraction section of the EEC were changed. Depending on the economics of recovering ethylene below the desired level by A rectification section is provided, which effectively performs the desired rectification and reduces the cracked gas flow. It is preferred to improve the recovery of the ethylene component.

In this way, a portion of the top vapor can be condensed to provide a sufficient amount of return for the rectification section. generate a flow. Furthermore, in rectified sexitane, methane and hydrogen are transported along with the Physical solvents that may be released are also recovered.

Solvents containing only the desired components of ethylene and heavy hydrocarbons are economically desirable. If not, it may be further heated before processing in the raw material column (RPC). child column, the hydrocarbons extracted from the cracked gas stream are separated from the physical solvent. Ru. Rectified sexidine minimizes solvent loss and removes it from the top of the column. Operate in such a way that hydrocarbon products can be obtained. The operating conditions at the top of the column are , allowing the top product to be condensed by an easily available condensing medium such as air or cooling water. It is preferable that the At the operating pressure at the bottom of the feedstock column, the bottom The temperature of the substance is lower than the boiling point of the pure component solvent. In general, keep RPC at an economical scale. In order to maintain the You can leave it.

The overhead product from the RPC is further processed into a deethanizer and downstream equipment as in conventional processes. Process at the site. Although not limited to the configuration shown in Figure 4, similar thermal After the dilute solvent is cooled by the recovery circuit and dilute solvent cooling device, the The stripped solvent is recycled to the extraction section of the EEC.

All liquids produced and separated at the intermediate pressure level of the cracked gas compressor are safe. If it is processed in the fractionation series of a typical olefin plant after good. However, depending on the composition and amount of the separated flow, it may be better to stabilize it through EEC. It may be advantageous. Therefore, this flow is directed to the appropriate position of the stribping section. , preferably between the stribbing section and the extraction section. flows into.

The make method does not require high pressure to extract ethylene and each component, so A common solvent circuit with the first column, and the desired intermediate pressure of the cracked gas compressor. A secondary but parallel extraction column operated at an intermediate pressure level corresponding to It is economically advantageous to provide a The obvious advantage of this is that the cracked gas C3+ or C4+ hydrocarbons can be selectively extracted from the cracked gas compressor. The advantage is that the conditions necessary for compression of data can be further relaxed. of the above secondary parallel extraction column. It is possible to make the operating pressure level slightly higher than the operating pressure of the raw material column (RPC). Although preferred, it is not necessary. Concentrated solvent flow from the bottom of the parallel extraction column The same requirements regarding undesirable components such as methane can be applied to the EEC. The concentrated solvent stream from the EE-C and the Can be matched.

Alternatively, in some cases, a small stream of steam may be introduced from the top of the RPC accumulator. EE by recycling it to a suitable intermediate stage of the cracked gas compressor. It would be more economical to relax the strict standards for methane in the C bottom. How The objective must always be economic viability and versatility, even in situations where .

The uncondensed vapor from the top of the EEC is mainly composed of hydrogen and methane. The two disclosed In embodiments, this stream is then sent to a methane extraction column (MBC) where the solvent Methane is selected from a hydrogen-methane stream using a selective physical solvent in circuit no. Extract selectively. Criteria for the hydrogen content of the methane stream coming out of the bottom of the MBC The column was operated under strict conditions and the stream fed to the MBC was The methane produced is recovered along with the bottom product. Similarly, the operational purpose of MBC is to The aim is to maintain a low methane content in the hydrogen stream leaving the top. Hydrogen-rich gas Depending on the criteria for the gas flow, it may be advantageous to use a rectifying section at the top of the MBC. It may be advantageous. In an olefin plant, for example, converting acetylene to ethylene with hydrogen The hydrogen product leaving the MBC can be further processed before being used for oxidation. Wear.

Concentrated solvents containing methane and leaving a certain amount of unrecovered ethylene are Solvent circuit No. 2 by fractional distillation of methane in a carbon product column (MPC) Separate from solvent. Apply the stripped solvent to the top of the MBC. Recycle and extract more methane. The solvent in solvent circuit No. 2 is a solvent circuit. In the same manner as with solvent No. 1, heat recovery and cooling are performed to reach the desired temperature, and MBC extraction is performed. Used for export.

Note that two different types of selective physical solvents are used in two different solvent circulation circuits. can be done. In this way, compared to the solvent used in solvent circuit No. 1, In this case, the selectivity of the solvent used in solvent circuit No. 2 to methane to hydrogen is The selectivity can be somewhat higher. Also, the two solvent circuits have the same physical Satisfactory results are also obtained using solvents. But the important thing is that the flow, The operating conditions regarding temperature and pressure may be varied as necessary.

Another advantage of the method of the invention is that it increases the versatility of the olefin plant to various feedstocks. It is at this point. A great concern during design is always to make the plant the most economical possible. The question is how much versatility should be provided in order to maintain the same level of versatility. refrigeration system and the limitations of the cryogenic series pose considerable constraints. When applying the mailer method, Increasing the versatility of feedstocks is relatively easy. Furthermore, in the separation series Energy consumption can be reduced, making it possible to reduce costs in existing plants and and/or existing plants can be expanded at nominal cost.

Under normal operating conditions of a hydrocarbon distillation system, α, the ratio of methane to ethylene, is Relative volatility is approximately 5.0. However, the event was held from March 17th to 19th, 1980. 59th Annual Gas Processors As5ocia John 5veny's paper submitted to tion con-vention -High Cot-11ighHas Re＋＊oval with 5EL In EXOL 5olven, the relative volatility of methane to ethylene is 7.3 It is. Therefore, dimethyl ether of polyethylene glycol (DMPEG) In its presence, the relative volatility of methane to ethylene is Compared to the stem, this is a considerable improvement (46%). This means that DMPEG is Selective for ethylene recovery from streams containing methane and ethylene It suggests that. The relative behavior of methane and ethylene is determined by selective substances such as DMPBG. The contact process between migas flow and physical solvent is selected because it changes depending on the presence of physical solvent. It is a targeted absorption. Or perhaps it would be better to define it as extraction rather than absorption. Not possible.

For purposes of this invention, a selective physical solvent is defined as the lowest phase of methane relative to ethylene. has a volatility of at least 5.5 (i.e., a preference for ethylene over methane). defined as having high selectivity). , in addition, gaseous hydrocarbon per m3 of solvent At least 7. Those with a solubility (representing hydrocarbon carrying capacity) of ONm' is also defined. Alternatively, it is also defined as having a selection factor of at least 38. It will be done. The selection coefficient of the physical solvent for applying the technical idea of the Meler method to the present invention is Relative volatility of ethylene to ethylene and solubility of ethylene in physical solvents (Nm’/ m'). However, the ideal selective physical solvent is ethylene exhibiting a selectivity of at least 10°0 for It should have a hydrocarbon supporting capacity of Nrn"/ffl".

Especially when ethylene purity of 99.5% or more and ethylene recovery of 99% are required. A preferable selection coefficient is 49 or more. Also, at least 99.95% ethylene A particularly preferred selection coefficient is 70 to obtain purity and 99.5% ethylene recovery. It is.

Additionally, selective physical solvents include polyalkylene glycol, N-methylpyrrolidone, , dimethylformamide, propylene carbonate, sulfolane, glycolt Dialkyl ethers of lyacetates and methyl, ethyl or propyl aliphatic The group is particularly mesitylene, n-propylbenzene, n-butylbenzene, 0-xylene. C, ~C8° aromatic compounds constituting subgroups of xylene, m-xylene, and p-xylene, mixtures of these, mixed xylene-rich aromatic streams, and other C8-C1° aromatics. Select from the group consisting of families.

However, two different types of solvents can be used in the method of the invention. different solvents In some cases, it is particularly desirable to provide the first extraction column with a rectification section.

According to the method of the present invention, a high purity ethylene product can be obtained at a high recovery level. It is also possible to obtain product streams of useful purity of hydrogen and methane. Method of the invention Additionally, extremely low solvent losses, relaxed maintenance requirements, and simple equipment requirements , low capital costs, no freezing, long operating times, high versatility, and the ability to use a variety of feedstocks. Its characteristic lies in its availability. In addition, the method according to the invention has the same features and advantages. It is equally applicable to the production of propylene.

Figure 1 shows a typical olefin that recovers cracked gas using a low-temperature fractionation method and is partially functional. FIG. 2 is a schematic diagram showing an implant; Figure 2 shows U.S. Patent No. 2,573, which recovers and separates cracked gases by solvent absorption. , No. 341 is a schematic diagram showing an old olefin plant showing the Kniel process of No. 341. .

Figure 3 shows the make method applied instead of the cryogenic cooling series and demethanization equipment in Figure 1. Fig. 1 shows the recovery and separation of cracked gas and/or refinery gas using solvent extraction. FIG. 2 is a schematic diagram illustrating the method.

Figure 4 shows the flow of hydrogen-rich gas and methane gas recovered by the make method. Schematic flow sheet of the method for separating the demethanizer-enriched gas stream into a demethanizer feed stream It is. This diagram corresponds to the part shown as “Solar method extraction” in Figure 3. do. Therefore, all of the Ct-10 product is sent to the deethanizer.

FIG. 5 is a schematic flow sheet showing another embodiment of the makeup method. This embodiment In this case, an ethylene extraction column (EEC) extracts all the hydrocarbons and Producing a concentrated solvent stream: 1. This results in a hydrogen-rich gas as the first product. A methane product column (MPC) removes ethylene and heavy hydrocarbons. to produce a solvent stream enriched with these as a second product. Produces a methane-rich gas stream and feedstock power column (RPC) part product is received to produce a C2-hydrogenide product as a third product.

FIG. 6 is a schematic flow sheet showing a third embodiment of the makeup method. This embodiment In a company, an ethylene extraction column (EEC) contains ethylene and heavy hydrocarbons. Separates hydrogen and methane from concentrated solvents. H at the top! /CH, dilute the flow again with solvent to recover the H2-rich gas stream and the methane-rich bottom stream. generate. This bottom stream is flashed to recover a CH, rich gas stream. Ru.

In Figures 3.4.5 and 6, conduits are shown in order to direct flow.

The stream is also a product stream. Also, flow control valves, temperature control devices, pumps, etc. The main equipment shown is also installed and will be described below in connection with the continuous operation method of the present invention. It operates in conventional relation to the members. These valves, devices, pumps and heat exchangers Converters, accumulators, condensers, etc. are all collectively included in the term “auxiliary equipment”. Melt. Traditionally, the term "absorber" is used for gas/solvent absorption devices; When used in the process of the invention with selective physical solvents, "extractor" is indicated. I want to be thought of.

In addition, when writing "C3 = 10 hydrocarbons", this term includes ethylene and saturated/unsaturated Refers to heavy hydrocarbons, including both alkyl and aromatic hydrocarbons. Similarly, “C1+” refers to heavy hydrocarbons including methane and both saturated/unsaturated and alkyl/aromatics. vinegar.

The equipment shown schematically in the flow sheet of Figure 4 is an ethylene extraction column (EEC). ) 20, the raw material column in the first solvent circuit ( RPC) 30, and methane extraction column (MEC) 60 in the second solvent circuit. Product column (MPC), consisting of 70.

The cracked gas or refinery gas stream 11 is used in a post-cooler and for sweetening and dewatering the gas. The gas flows into the gas compressor 12, which is equipped with a system that includes: Heavy distillates and acids from thermal decomposition products Actual recovery of ethylene and propylene is carried out after removing the chemical impurities and water. can. Incorporating such pretreatment into the compression cycle improves the final product separation system. The selection and design of the system can be done quite easily.

Appropriate gas cooler selectively compresses, cools, sweetens, and dehydrates gas. 15 to the central part of the EEC 20. After this, the gas is extracted ascending section 23 and contacting the descending dilute solvent from line 49, It enters the sump section 25 and contacts the descending reflux from line 35 and finally the top flow. and exits the column through line 24.

The combined reflux and solvent pass through extraction section 23 to stripping section 2. 1 and is heated by recycling into line 26 and reboiler 27. by recycling the bottom liquid and into line 28 and side reboiler 29. contact with rising vapor generated from the heated intermediate liquid. Some of the rising steam Extracted by reflux/solvent liquid. The remaining steam rises to the extraction section and It mixes with the gas stream entering from line 13. The hot bottom liquid is piped from the column. 22a and diluted/! Passing through the thick solvent cloth exchanger 33, the pipe line 22 It is sent to the center of the RPC 30 via b.

Column 30 consists of a stripping section 31 and a rectifying section 35. Up The ascending gas passes through rectification section 35 and contacts descending lean solvent from reflux line 54. , and exits the system as a top stream through line 34.

This flow is condensed in a top condenser 51 and passed through line 52 to an accumulator 53. enter. Here, a part of the water is passed through the pipe 54 to the top of the RPC 30 by the reflux pump 55. and the remaining portion is recycled through line 56 by product pump 57. It is pumped through to produce ethylene and heavy hydrocarbons. These are de-ethanized is sent to the converter and other downstream equipment. The other part of the uncondensed gas is And if it is economical, the cracked gas compressor via line 59! selectively recycled into 2 do.

The refluxing hydrocarbons in the pipe 54 of solvent circuit No. 1, which contains trace amounts of solvent, are descending rectification section 35 in countercurrent relation to the ascending gas flow from passage 22; It enters the stripping section 31 and carries the bottom liquid to the recycling line 36 and It comes into contact with the rising steam generated by passing it through the heater 37. Rectification section 3 The purpose of No. 5 is to suppress the loss of solvent to Ct=decahydrocarbons. RPC The heated bottom liquid at the bottom of No. 30 is passed through the conduit 32 of the return section of Solvent circuit No. and take out, dilute/concentrated solvent cross exchanger 33, pipe line 41, reboiler 27, Side reboiler 29, lean solvent cooler 43, line 45, line 41, lean solvent pump 47 and feed line 49 to the top of the extraction section 23 of the EEC 20. .

Top stream 24 enters accumulator 34 through top condenser 31 and line 32. From there, the liquid is passed through a pipe 35 by a reflux pump 36 to undergo rectification of EEC20. It is recycled to the top of section 25. The above is the first melting subcircuit and its column. and a description of auxiliary equipment.

The uncondensed gas in the accumulator 34 is stripped via the supply line 33. A methane extraction column (MBC) located between section 61 and extraction section 65 ) Send to the center of 60. Gas from line 33 contacts dilute solvent from line 89 while ascending extraction section 65 as a hydrogen-rich gaseous product stream 64. Exit the column. The descending dilute solvent from line 89 is connected to the incoming gas stream from line 33. the extraction section 65 while effectively absorbing material from the Enters the 2-pin section 61, contacts the rising steam, and adsorbs methane from it. while hydrogen is transferred to the vapor. The bottom liquid in the column is routed through line 66 and the reboiler. It is heated by recycling it to the lar 67. The bottom liquid in the column is 62a and 62b, and the dilute/rich solvent cross column 70 stripping It consists of a section 71 and a rectification section 75. Gas heated by exchanger 73 is raised up rectification section 75 while contacting descending reflux liquid from line 94. Ru. The top stream from this column passes through line 74, top condenser 91 and line 92. and enters the accumulator 93. Liquid from this accumulator is routed to line 94 and returned. Recycle via flow pump 95 to the top of rectification section 75 of MPC 70 . Steam from accumulator 93 is coupled to a methane-rich gas stream via line 99. and take it out.

While passing through rectification section 75, the descending reflux liquid collects methane and C1 While delivering hydrogen, the solvent is adsorbed in solvent circuit No. 2 and then stripped. Enter section 71. Here it comes into contact with the rising vapor from the bottom liquid of the column. . Heating this liquid means recycling it into line 76 and reboiler 77. done by. The heated bottom liquid, i.e. dilute solvent, is removed via line 72. , lean/rich solvent cross exchanger 73, line 81, reboiler 67, lean solvent cooling MBC 60 via vessel 83, line 85, dilute solvent pump 87, and supply line 89. to the top of the extraction section 65. The above describes the column and supplement of the second solvent circuit. This is an explanation of auxiliary equipment.

That is, the purpose of EEC20 is to have a selective physical solvent selectivity in stream 49. selectively extracting all the hydrocarbon components of the feed gas stream 13. There are many things. The purpose of RPC 30 is to remove the feed gas stream present in concentrated solvent stream 22b. All hydrocarbons are removed and a dilute solvent stream is added to line 32, plus a top stream. The objective is to produce a Cf=decahydrocarbon component stream present in 34.

The purpose of MEC 60 is to separate the majority of the hydrogen in line 64 as its top stream; and separating the majority of the methane as part of the concentrated solvent stream in line 62a. It is in. The purpose of MPC70 is to produce meth containing small amounts of C2 and C3 hydrocarbons. substantially all of the methane remaining in ion-rich gas stream 99 and The objective is to regenerate the dilute solvent present in 2.

FIG. 4 shows a system in which completely different selective physical solvents can be used. First solvent In the circuit or primary solvent circuit, C1 = 10 hydrocarbons in the concentrated solvent stream are Hl and CH, are separated in the top stream of the regenerate the agent. In the second or secondary solvent circuit, a hydrogen-rich gas stream and recover the methane-rich gas stream while regenerating the solvent. child These two circuits are the top flow from the first solvent circuit, which is the gas flow of the second solvent circuit. Connect by.

If two different selective physical solvents are used in the two solvent circulation circuits, the solvent circuit Compared to the solvent used in circuit No. 1, the solvent used in circuit No. 2 is more resistant to hydrogen. Selectivity for methane is higher than that for methane. Such a second solvent is preferably mesitylene or having at least one side chain and e.g. polyethylene glycol Dimethyl ether (DMPEG) in the second solvent circuit should be used. It is a C8-C1 degree monocyclic aromatic distillate with a low point and a high selectivity coefficient.

If the same selective physical solvent is used in both solvent circuits, monocyclic C8-C1 o Aromatic solvents are preferred. However, it is important to note that the flow, temperature and pressure This means changing operating conditions as necessary.

Each circuit passes through two columns: an extraction stripping column and a distillation column. . Each extraction stripping column has at least a stripping section and/or is equipped with a rectification section and/or an extraction section.

Each of the four columns is equipped with a boiler to heat its bottom liquid. each time The first column in the column is an extraction stripping column, and its performance control is partly This is done by controlling the temperature and flow rate of the dilute solvent stream sent to the top of the column. Like Alternatively, the first column of the first section should be spaced directly above the feed of the dilute solvent stream. With a reflux sent to the column at the set feed point, there is a precision flow between the two. Form the retaining section. On the other hand, preferably a second extraction stripping column No reflux is provided. However, if fairly high purity hydrogen is desired, may be set. The second column of each circuit is the product column and the first column is the product column. The raw material Cm''+hydrocarbons is separated as a partial stream, and the second column is the top stream. The purpose is to separate methane containing impurities.

Figure 5 shows, for example, a double column extraction strip of a gas stream containing olefins. FIG. 3 is a diagram illustrating a mapping method. Here, all hydrocarbon components in the first column are Hydrogen is first separated from the In this method, an ethylene extraction column (EEC) 120 , solvent regeneration column (SRC) 130, methane product column (MPC) 140 and Raw material column (RPC) +50 is used.

The compressed, sweetened, cooled, and dehydrated gas passes through line 121. It flows into the column 120 slightly below the central part. The liquid at the bottom of the column is transferred to pipe 12. 5 and reboiler 126, and is heated thereby. Column 120 top A hydrogen-rich gaseous product exits via line 124.

The heated concentrated solvent of exchanger 127 passes through line 131 to the center of column 130. It falls slightly below. The liquid at the bottom of column 130 is transferred to conduit 135 and reboiler 130. is circulated and heated by this. Liquid is piped from the bottom of column 130! 27th and through pump 137 to heat exchanger 127 and to line 128 and reboiler. - 126 and solvent cooler 129 to the top of column 120 as dilute solvent. enter.

Top flow through line 134 column! Sent from 30, reflux condenser! 34 It is cooled in To separate. The condensed hydrocarbons pass through line 139a and are pumped by reflux pump 139. After increasing the pressure to column 130, it enters the top of column 130 as reflux. Uncured The condensed hydrocarbons pass through the pipe 141 from the accumulator 138 to the column! 40 center It is located slightly below the section. column! 40 bottom liquid line 145 and reboiler 145 is circulated and heated by this. The top of the CI gas product passes through line 144. Flow is pumped out the top of column 140.

The heated solvent passes through the pipe 151 from the exchanger 147 to the central part of the column 150. or below. The liquid at the bottom of column 150 is circulated through line 155 and reboiler 156. It is heated by the ring. Bottoms liquid exits column 150 through line 148 is cooled in exchanger 147 and passes through line 14B and reboiler 146 to column Before entering the top of 140, it is further cooled in a solvent cooler 149. Conduit 154 The top flow exiting the top of column 150 through the reflux accumulator! At 62 Before entering, it is partially condensed in a condenser 161. The condensed liquid in the accumulator 162 is through line 163 and to the top of column 150 by reflux pump 167. Ru. The uncondensed hydrocarbons in the reflux accumulator 162 are transferred from the pipe 164 to C Onisenari. It is sent off as a hydrohydride product.

Figure 6 shows compressed, cooled, sweetened and dehydrated oil. FIG. 3 is a diagram showing a method for separating and recovering a refin-containing gas. This method uses separate colors. Two extracts that can be arranged as a column or stacked as one tall column Use out column. That is, the first, bottom ethylene extraction column (EEC) 170 ．． and a second, top column (MEC) 190. In this method, the source of conduit 171 The feed gas flow enters slightly below the center of EEC 170 and rises to conduit 178. contact with descending dilute solvent from. The liquid at the bottom of column 170 is transferred to pipe 175, The column 170 Return to The bottom liquid of column 170 passes through line 173 to a rich/lean solvent exchanger. 181 and is heated. The top flow in line 179 exiting the top of column 170 is , through an appropriate compressor 185 and conduit 191, and enters near the bottom of the MEC 190. .

However, the stripping section is located below the feed position, which is slightly below the center of the column. A reboiler can be used first to install the section.

Bottom liquid enters flash unit R200 from column 190 through line 193. , where the bottom liquid is methane-rich gas exiting the device 200 via top line 209. The raw acid is passed from the device 200 through the pipe 203 and the solvent pump 205. , into a bottom liquid stream that enters the top of column 170 via line 178. top The partial flow passes from the top of column 190 through line 199 and then to a suitable power recovery tank. through bin 187 and into line 197 as a hydrogen-rich gaseous product stream. Ru.

The heated concentrated solvent passes from exchanger 181 through line 211 to the center of EEC 210. It is located slightly below the section. The liquid at the bottom of this flows through line 215, reboiler 216 and be piped. Bottom liquid exiting column 210 through line 213 is transferred to exchanger 181. cooled down. Lean solvent beam boiler 17 exits exchanger 181 through line 182 6, and after passing through the pipe 183, it is further cooled by the solvent cooler 184, and the pipe passes through the pipe 183. The top of MEC 190 is entered via path 198. The top flow leaving EEC210 is a pipe. It passes through line 219, is condensed by condenser 221, and passes through line 222 as a reflux liquid. The liquid enters a humulator 223 where it is separated into a liquid portion and the above portion. The liquid part through line 225 and into column 210 via line 218 by reflux pump 226. sent to the top of the The vapor portion is advantageously condensed via line 224. Ct=delivered as hydrogen chloride product.

H3 and CH for ethylene and heavy hydrocarbon components.

Depending on the relative concentrations of It can be considerably relaxed compared to that. Therefore, economically, the conduit 178 It is desirable to bypass a significant portion of the solvent in the dilute solvent line 183.

This allows the size of the device relative to the EEC and the device 176, 181, 210 . 216.221.223.226 and associated piping. can be reduced.

Kanogaoka Replace the cooling train and demethanization column with the make method extraction system shown in Figure 3. This will improve existing olefin plants as shown in Figure 1. P The Lopylene refrigeration system section is reserved for use with the make method extraction device. . The propylene refrigeration system can be removed by shutting down the ethylene refrigeration system. The load on the system can be further reduced. Based on cost efficiency, Molecule in Figure 1 I think it would be better to replace the Larsieve or dehydrator with the glycol dehydrator shown in Figure 3. However, for the purpose of this example, the molecular sieve device is left in place.

The make method extraction system uses 0-xylene as one of the selective physical solvents. , as shown in FIG.

By applying reliable, industrially available computer designs. The method shown in Fig. 6 was simulated. Although only a small part of the operating conditions have been optimized. Therefore, it does not reflect the final design. In this simulation, the compression ・The flow of the cooled, sweetened, and dehydrated pyrolyzed olefin-containing gas is 3. Line 17 at a flow rate of 8,608.82 kg-mol/hour at 2°C and 2°758 Kpa. It was assumed that the EEC170 flows through the EEC170. In addition, the flow of dilute solvent is 78 into EEC 170 and at -13.2°C and 3,103 Kpa. A flow rate of 15,548.00 kg-mol/hr was assumed. Three types of generation It was assumed that the items could be recovered. That is, 1,949.03 kg in conduit 199 moles/hour of hydrogen-rich gas product in line 209: 41,734. OOk g-mol/hour of methane-rich gas product and 4,93 in line 224. 2.30 kg-mol/hour of ethylene and heavy hydrocarbon products.

Table 1I shows the composition, other flow rates, temperatures and pressures. According to the liquid capacity standard, the tube The composition of the cracked feedstock oil in route 171 is a pyrolysis 70/30 tane/propane mixture. This is a representative example of something.

substance purity The composition of the hydrogen-rich gas product in line 199 should be noted. That's what I mean This is because its hydrogen content is 93.4% on a kg-mol basis. moreover, Its solvent content is only 0.0017% on a kg-mole basis, and its ethylene content is essentially zero.

Considering that the methane content is 89.5% on a kg-mol basis, Also noteworthy is the composition of the methane-rich gaseous products in the gas. In addition, the melt The agent content is 0.04% on a kg-mol basis, and the ethylene content is on a kg-mol basis. The standard is 0.043%.

The composition of the ethylene and heavy hydrocarbons stream in line 224 is on a kg-mole basis. So, ethylene is 56.3%, ethane is 22.3%, and methane is 0.030%. . Further, its 0-xylene content is 0.0032% on a kg-mol basis.

recycling ratio All compounds except hydrogen, methane, ethylene, benzene and toluene can be processed using the solar system. is recycled from the system and returned to the heating equipment for further decomposition. The Kniel method according to U.S. Pat. No. 2,573.341 is 1.0. When compared to the recycling ratio, the recycling ratio is 1.8. This preferred resource The cycle ratio favors aromatics, which was clearly required in the Kniel process. This is thought to be the result of selecting reaction conditions that are advantageous to ethylene, rather than the reaction conditions.

Significance of calculation results The significance of the results shown in Table 1I is considerable. This is because this example The industrially available simulation equipment used in the This is because they can be used in order.

1st! The results shown in the table show that the solar method has far exceeded what conventional technology has achieved and still can achieve. It is clear that you have not achieved what you have achieved. This could not be achieved before The results show that this embodiment of the solar process is a first-class discovery in ethylene production technology. proves that.

For example, if we compare the Kniel method solvent loss with the solvent loss shown in Table 1I, good. For streams 199, 209 and 224, all of the streams exiting the system. For example, the total loss m of 0-xylene is 0.894 kg-mol/h. style In +98. - total amount of xylene is 15.427.96 kg-mol/h be. total. - This amount of loss, expressed in % of the xylene flow rate, is on a kg-mole basis and is negligible. 0.006%, which is a surprising achievement in solvent absorption technology. Same as this example When using mesitylene as the selective physical solvent, the solvent loss rate is: − It is expected to be significantly lower than for xylene.

Another possible comparison can also be made for methane rejection criteria. Chemical E The article by Progressi (1947) states that fat The methane retained in the oil is transferred to the cracking gas where the methane and ethylene capacities are almost equal. It is stated that the amount of ethylene in the water was 4%. In contrast, The methane in streams 173 and 224 is equal to 1°50 - mol/hour; ethylene in stream 171, where the methane volume is 2/3 of the ethylene volume. This corresponds to 0.05% of the total amount.

Jade top > i bottom 9 purity The feed hydrocarbon product is further fractionated downstream into ethylene and ethane. Top part To do this while maintaining sufficient purity in the ethylene stream, the ethylene content must be The performance of the distillate column must be at a sufficient level.

As can be seen from Table 11, similar to stream 224, the ethylene fractionation column If the ethylene content of a feed stream containing only ethylene and ethane is sent to a For 72 mol%, the 99.95 mol% pure ethylene product is converted to 99.94% pure ethylene product. We were able to obtain a good recovery rate. This performance is similar to that of the Kniel method when using a demethanization column. , and such columns cannot be achieved using the mailer method. It's not necessary at all.

end international search report INTERNATIONAL APP (JCATrON No, PCT/US F16101674 (SA 14343)

Claims (20)

[Claims] 1. Compressed and sweetened dry gas containing olefins A stream of gas is extracted with a dilute selective physical solvent stream at a given solvent flow rate. a hydrogen-rich product stream, a methane-rich product stream, and an A method of producing a stream of tyrene and heavy hydrocarbons (C2=+). 2. The above-mentioned olefin-containing gas may be pyrolyzed hydrocarbon gas or catalytically cracked hydrocarbon gas. selected from the group consisting of gas, refinery exhaust gas, coke oven gas, and synthesis gas. A method according to claim 1, characterized in that: 3. the relative volatility of methane to ethylene is at least 5.5; The solubility of ethane in physical solvents is lower than that of ethylene per m3 of external solvent. so that both are 7.0 Nm3 or the selection coefficient is at least 39. The selective physical solvent is selective for ethylene and heavy hydrocarbons of the C2=+ hydrocarbons. 3. A method according to claim 2, characterized in that it is selective for . 4. Claim 3, characterized in that the selection coefficient is at least 49. The method described in. 5. Claim 4, characterized in that the selection coefficient is at least 70. The method described in. 6. The selective physical solvent is polyalkylene glycol, N-methylpyrrolidone. , dimethylformamide, propylene carbonate, sulfolane, glycol The dialkyl ether, methyl, ethyl or propyl aliphatic group of acetate is particularly preferred. cytylene, n-propylbenzene, n-butylbenzene, o-xylene, m-xylene C■ to C10 aromatic compounds constituting the subfamily of silene and p-xylene, and mixtures thereof. A group consisting of compounds, mixed xylene-rich aromatic streams, and other C■ to C10 compounds 4. A method according to claim 3, characterized in that the method is selected from: 7. A. Depending on the composition and flow rate of the gas flow, the gas flow is 1.000 Nm3. The flow rate of the predetermined solvent should be within the flow rate range of 0.1 to 70 m3. B. a heat input means and fed with a stream of said dilute selective physical solvent; , said olefin-containing gas stream to at least one extraction stripping column. and flowing the gas and the solvent in a countercurrent relationship such that at least one top stream and a small generating at least one bottom flow, and C. sending said at least one bottoms stream to at least one distillation column; regenerating the dilute solvent stream; A method according to claim 6, characterized in that: 8. A. In the first column of two extraction stripping columns arranged in series, An olefin-containing gas stream is sent to each column of the dilute selective physical solvent. flowing the gas stream in countercurrent relation to the flow, thereby forming a first top stream, a first bottom stream, and a first bottom stream. a second top stream and a second bottom stream; and one of the above products, and B. The first and second bottom streams are sent to two distillation columns to remove the dilute selective physical solution. regenerating said stream of agent and producing at least one of said products; 8. The method of claim 7. 9. said extraction column comprises a stripping section with heat input means, and Claim 8, characterized in that an extraction section is provided above this. The method described in. 10. The heat input means comprises a bottom reboiler and a side reboiler. The method according to claim 9. 11. at least one of said extraction stripping columns to which a reflux stream is sent; and further comprising a rectification section provided above the extraction section. 11. The method according to claim 10, characterized in that: 12. Each of said dilute solvent streams flows through a solvent circuit and said first extraction stream. a tripping column comprising part of the first solvent circuit and said second extraction strip; Claim 8, characterized in that the ping column includes a part of the second solvent circuit. The method described in section. 13. the solvents of the first and second solvent circuits are the same selective physical solvent; 13. The method according to claim 12, characterized in that: 14. the solvents of the first and second solvent circuits are different physical solvents; 13. A method according to claim 12, characterized in that: 15. A. The first neck stream from the first extraction column is subjected to a second extraction stripper. a hydrogen-enriched product stream to produce the hydrogen-rich product stream; B. The first bottom stream is sent to a first column of the distillation columns to recycle the solvent. producing said streams of ethylene and heavy hydrocarbons; and C. Said A second bottoms stream is sent to a second column of said distillation column to produce said methane-enriched product. Generates a product flow as a nuchal flow, 9. The method according to claim 8, characterized in that: 16. A. the first top stream is the hydrogen-rich stream; B. The first bottoms stream is sent to a first column of the distillation columns to perform the dilute selection. Regenerating the first stream of selective physical solvent and the top stream of methane and heavy hydrocarbons. and sending this top stream to said second extraction stripping column; C. said methane-rich product stream by said second extractive stripping column. and generating the second bottom flow, and D. This second bottoms stream is sent to the second distillation column to regenerate the solvent stream. and producing said stream of ethylene and heavy hydrocarbons. A method according to claim 8. 17. said top stream to an extraction column where a second stream of dilute selective physical solvent is sent. to produce the hydrogen-rich stream and a bottom stream, and reduce the pressure of the bottom stream to , said methane-enriched product stream, and said first extractive stripping column. producing a second stream of said dilute selective physical solvent that is sent. The method according to claim 7. 18. The first extraction stripping column has a partial top stream for the top stream. a condenser and a feed point set above the selective physical solvent feed point; reflux means for returning the condensed liquid to the extraction section, thereby directing the rectification above the extraction section. A special rectification, extraction and stripping column designed to form sections. Improvement method according to claim 17. 19. Countercurrent contact in the rectification/extraction/stripping column was carried out at 3.200K. Improvement method according to claim 18, carried out at less than pa. 20. a lean system in which the bottom stream cross-exchanges with the stream of a lean selective physical solvent; / a concentrated solvent stream heated by a concentrated solvent. improvement method.