TW530121B - Methods for sealing a butadiene gas compressor and a two-stage compressor, and a sealing system of a butadiene gas compressor - Google Patents

Abstract

Disclosed is a method for sealing a butadiene gas compressor. The method for sealing a butadiene gas compressor, comprises the following steps of: (a) supplying a sealing oil to a plurality of sealing faces formed by a rotary ring and a stationary ring mounted at a suction portion and a discharge portion in the butadiene gas compressor; (b) injecting nitrogen gas as a buffer gas into an inlet in the suction portion and C1-3 hydrocarbon gas as a buffer gas into an inlet in the discharge portion among the plurality of the inlets, or injecting only C1-3 hydrocarbon gas as the buffer gas to the both inlets, each of the inlets being positioned inward of each of the mechanical sealing assemblies mounted at the suction portion and the discharge portion, so as to prevent the butadiene gas from flowing into the mechanical sealing assembly; (c) discharging a mixed gas of the butadiene gas and the buffer gas through the vents installed in each of the suction portion and the discharge portion; and (d) recovering the sealing oil passing the sealing faces through the recovery lines, wherein the pressure of the buffer gas on injecting is maintained higher than that of the mixed gas in the vents.

Description

530121 V. Description of the invention (Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economics Background of the invention 1. Field of invention = In terms of the invention, the invention is related to a sealed diluent gas deletion system, especially a secret coin—a sealed dipole service Compression system ... One of the buffer gas is injected into the compression system for petrochemical waste feed = diene extraction treatment, so that the sealing function of "" is prevented from being lost due to the butadiene gas foaming and polymerization. 2 · Previous technical description 1 Butadiene is usually expressed as u 夂 butadiene has a ch2 chch-ch2 conjugated double bond, which is the simplest form of dihydrocarbon. H Butadiene is colorless and odorless. Flammable gas is non-aqueous. Used as p-benzene Moulds prepared by copolymerization of ethylene, acrylonitrile, vinyl chloride, and other copolymerizable monomers impart flexible raw materials. Among the various butadiene diluting methods, especially the butadiene extraction method is used, which is transferred from the ethylene process and The high-purity butadiene is extracted from the incoming C4 hydrocarbon feed stream, and dimethylformamide (DMF) is used as an extraction solvent. This succinic acid purification method includes 4 steps, Including the first extraction_distillation, second extraction_distillation, butadiene purification and solvent purification steps. The C4 fuel is continuously processed from the first step to the third step. In the first extraction_refining step, the Q feed stream is divided into Two groups, one is composed of butene and butane, which is less soluble in solvents than butadiene, and the other is composed of butadiene and acetylene dissolved in solvents. The transfer machine is transferred to the second extraction_steaming hall step, and then separated into butadiene and acetylene which are not treated with the solvent. The untreated butadiene is then transferred to the butadiene purification step, and then is passed through the distillation element Dimensions of this paper are in accordance with China National Standard (CNS) A4 (210 X ^ 97 Public Love «0121 A7")

530121

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the invention (3) Butadiene gas between the rotating surface and the fixed surface, so the hydrocarbon gas is introduced into the sealing oil to increase the viscosity of the sealing oil, so the oil is blocked for a long time. Enter the gap of the fixed surface. The frictional heat between the rotating surface and the fixed surface forces the penetrating sealing oil to remain outside the gap, causing a hollow port such as a crater of the moon to form on the surface of the fixed surface. This widens the gap between the rotating surface and the fixed surface. Increase the leakage of sealing oil. This phenomenon is called foaming. In addition, the O-ring erected on the fixed surface inside the mechanical seal assembly hardens when it comes into contact with butadiene gas, thus losing the dynamic sealing function. The blocking force that blocks the inflow of butadiene gas in this way is reduced, so that butadiene polymerized by frictional heat accumulates between the two surfaces to create an opening on the sealing surface. When a butadiene gas compressor (as shown) is made of a two-stage compressor, the effects of butadiene exposure on compressor components are shown in Table 1 below. Table 1 Stage classification Rotating surface Fixing surface 0-ring carbon packing i The first male good foaming and hardening is good ~~~ The female good foaming and hardening is good S ~ The second male good foaming and hardening is good ---- It usually takes 3 days to repair the sealing system of the butadiene gas compressor, so the purification of butadiene cannot be performed during the repair. During the normal operation of the compressor, polymer builds up between the trays, causing blockage of the reboiler. It is difficult to operate normally. In this way, the trays and reboilers must be cleaned, and it takes 7 days. --------- ------- Line 4P (Please read the notes on the back before filling this page)

530121 V. Description of the invention (4 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs To improve the aforementioned problems, a method was used in which the buffer emulsion was injected into the compression system, so the butadiene gas did not contact the mechanical seal assembly. Buffer gas Represents a gas that is fed to the sealed spindle of a centrifugal compressor to prevent the working fluid from leaking to the outside along the spindle. The concept of buffer gas is cited in sealed compressors. Please refer to U.S. Patent No. 4,495, 〇35, which discloses a method for preventing The lubricant contacts the working fluid of the compressor, and the sealing gas is fed before the working fluid to improve the purification effect. In addition, U.S. Patent No. 3,795,460 describes a sealing device for a gas compressor in which a buffer gas is introduced to prevent part of the working fluid from flowing into the seal. In this way, the working fluid will not contaminate the process. US Patent No. 5,619,850 discloses that the buffer gas is used to prevent the compressed gas or working fluid containing corrosive or toxic components from leaking into the compressor. Sexual and non-toxic ingredients Used as a buffer gas. By using the aforementioned principle, a technique has been applied to a butadiene compression system. In a sealed system, a buffer gas including BBR (butane · butene residue) or nitrogen is injected into a carbon-filled ring to prevent butadiene Diene gas flow inside the mechanical seal assembly. But BBR is a C4 type compound with similar properties to butadiene, so it reacts with the sealing oil to form a polymer. Taking nitrogen as a radon gas, for example, nitrogen is an inert gas. It will not react with the sealing oil at the time. However, the used nitrogen cannot be recovered, and an external > main input system must be used to reduce its economic benefits. Specially known technologies have a weak buffer effect, so a considerable amount of Ding may be lost In this way, understand that there is an urgent need to select a more suitable buffer gas line to enter the 'ene amount micro to this paper standard applicable to China Standard (CNS) A4 specifications (21Q χ 297 public love)-7 530121 A7 B7

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs

The inventors conducted intensive and thorough research on the method of sealing a butadiene gas compressor, aiming to prevent the problems encountered in the prior art, and found that nitrogen and Cm hydrocarbon compounds such as methane (CH4), ethane (C2h6), propaneation), and Propylene (c # 6), or a single Cw hydrocarbon compound, is injected into the extraction section and discharge section of the butadiene gas compressor as a buffer gas through the air inlets and vents blocked by multiple carbon seal rings, and the buffered The gas mixture is discharged, in which nitrogen is recovered as a low-pressure outreach purge gas, and ci 3 hydrocarbon compounds are recovered as a fuel gas, thereby obtaining a maximum sealing effect and thus greatly extending the butadiene purification process. The length of time, and at the same time can effectively recycle the used buffer gas. Thus, an object of the present invention is to provide a method for effectively preventing foaming and opening of a sealing surface by injecting a Cw hydrocarbon compound into a sealing system of a butadiene shrinker as a buffer gas. Another object of the present invention is to provide a method for recycling the buffer gas discharged from the butadiene compressor or reusing it for other purposes. Another purpose of the present invention is to provide a method for reducing the cost of cleaning tower trays and reboilers to cause shutdown of the butadiene compressor. Thus, in order to achieve the purpose of the invention, the present invention provides a method for sealing a butadiene gas compressor, which is used to improve the succinic gas content of the butadiene gas discharged from the stripper pipe string of the butadiene purification process. This method includes the following steps: a) Supplying sealing oil to a plurality of rotating rings and fixed rings formed by setting up the extraction and discharge parts of the compressor

The size of this paper is ® National Standard (CNS) A4 (210 X 2 ^ 17 530121) 5. Description of the invention (6 or only C〗 · 3 ^ gas is injected into the two inlets as buffer gas, each of which is installed in the The direction of the mouth of each of the mechanical seal assembly of the extraction part and the reduction part thus prevents butadiene gas from flowing into the mechanical seal assembly; C) The distillate gas is discharged through the vents erected at each of the extraction part and the discharge part The mixed gas with the buffer gas; and d) The sealing oil passing through the sealing surface is recovered through the recovery line. The pressure of the buffer gas at the time of injection is maintained at a pressure that is lower than the pressure of the mixed gas at the vent. A brief description of the drawings, the foregoing, and other objects, features, and other advantages of the present invention will be apparent from the following detailed description together with the accompanying drawings. In the drawings, FIG. 1 is a cross-sectional view showing the conventional knowledge.配 The matching surface of the gas system; b) Nitrogen as the buffer gas is injected into the inlet of the extraction section, and Cl_3 hydrocarbon gas as the buffer gas is injected into one of the inlets of the discharge section. The second figure is a sectional view showing this The third embodiment of the dilute gas compression system of the invention is shown in FIG. 3, which is a process diagram showing a specific embodiment of the manufacturing process of the consumer cooperatives of the intellectual property bureau of the dilute gas pressure economy department of the present invention. Fig. 4 is a line chart showing the tendency of increasing the amount of gold and 丄 * ___ 于 in the first time, according to the actual " comparative and comparative method of compressors. The method of sealing the butadiene gas compressor is characterized by slowing the gap between the two sides of the ring, and then letting the butadiene material flow into the inside of the mechanical seal assembly at the end of the machine, so that the buffer gas contacts 530121 A7

10 530121 A7 B7 V. Description of the invention (8 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs = Lean gas cannot be filled by carbon to circulate inside the mechanical seal assembly. The gas emitted from the vent (15) after the L is issued is called After the '=', the coexisting state exists in the buffer gas_1 gas, and it is again used as the purge gas of the low-pressure outreaching method or the plutonium as the fuel gas. Similarly, based on the foregoing principle, it is at the diene gas extraction point. It also has an effect. As for the buffer gas, the present invention uses nitrogen gas and k hydrocarbon gas. The c " hydrocarbons such as methyl alcohol, ethyl alcohol, ethyl alcohol, acrylic acid, acrylic acid, etc. have the advantage that the nitrogen gas is f " It cannot penetrate into the mechanical seal assembly like Ci_3 hydrocarbon gas. It is particularly preferable to use formazan because it cannot generate polymer by frictional heat. Taking the -stage compression system as an example, a useful buffer gas is preferably nitrogen. Extraction of butadiene gas and hydrocarbon gas for discharge. Then, because the extraction pressure of butadiene gas is low, nitrogen is used as a buffer gas in the extraction section. Two-stage compression commonly used in butadiene purification process Take the system as an example, the gas system is used as the buffer gas of the first stage extraction section, and the Cw hydrocarbon gas can be used as the first stage discharge section. Similarly, the Cl 3 hydrocarbon gas is preferably used as the second stage extraction section and the first stage discharge section. Buffer gas. The discharged gas mixture containing nitrogen is used again as a purge gas for the low-pressure outreach section, and the exhaust gas mixture containing C · 3: gas is recovered as a fuel gas. In the present invention, the 'buffer gas is The pressurized stage is fed through 4 positions (two male rotor positions and two female rotor positions). So in the two-stage compression system, the flushing gas feeds through eight positions, and flow indicators are set at each position to monitor the feed. Now refer to Figure 3, and show a process diagram illustrating the use of two-stage nitrogen in the retarder pressure ------- P order ------- line * (Please read the note on the back? Refill this page} This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 11 530121

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs

A specific embodiment of a sealing process for a butadiene gas compression system of a compressor. In this regard, a compression system is provided, in which the two compressors (201, 2102) are connected in series, and the compression pressure in the second stage is about 2-3 times higher than the compression pressure in the first stage. The butadiene gas being pumped into the first stage compressor (20m) is preferably brought into contact with the nitrogen gas flowing through the first stage air inlet (23, 27) before reaching the mechanical seal assembly (21, 25) ( 101). The resulting large gas mixture (about 90% by weight or more) is then composed of nitrogen, and a small amount of butadiene gas flows out through the first-stage vents (24, 28). Mixed gas combination Nitrogen transferred from the port of rancidity oil is re-converted into the feed gas processed by the low-pressure outreach unit). The feed pressure of the buffer gas is then controlled to be approximately ⑴ times higher than the pressure of the butadiene gas circulating to the vent through the carbon plug. If slow = the gas feed pressure is low, the buffering effect becomes weaker, resulting in shallow leakage of seal oil. On the other hand, if the pressure is high, the process is contaminated by nitrogen. Similarly, the Ch hydrocarbon gas as a buffer gas is injected into the discharge part of the butadiene gas compressor through the first stage air inlet (32, 36) to prevent the butadiene gas from leaking into the mechanical seal assembly (30, 34). internal. As a result of the buffering, the discharged gas mixture contains 75% by weight or more of c " hydrocarbon gas and succinic gas, and a small amount of nitrogen (by weight or less) is used as a buffer gas in the first stage extraction section. The mixed gas is discharged through the first-stage vent, 37), and then recovered by the fuel gas blower and reused as the feed gas. In the fourth stage compressor, the sealing oil is fed to the sealing surface between the rotating ring and the fixed ring. Then the sealing oil in the state of rancidity oil, together with the buffer gas and a very small amount of butadiene, flows through the oil recovery pipeline (104,104), called the ---------- order ------- line · (Please read the precautions on the back before filling out this page) The paper size_ National Standard (CNS) A4 (210 X 297 mm) 12 530121 A7

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Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 530121 A7 B7___ V. Description of the Invention (11) Whether butadiene gas actually flows into the mechanical seal assembly cannot be detected externally by any means. Gas from sealed ports can only be analyzed by sampling. It can be seen that when the butadiene gas content of the rancidity oil is 0.1% by weight or less, the optimal buffer gas injection amount can be obtained. Whereas the following examples provide a more complete understanding of the invention, these examples are provided for illustrative purposes only and are not to be considered as limiting the scope of the invention. Example 1 The sealing performance of a butadiene gas compressor including a two-stage compressor according to the present invention was measured according to the process shown in FIG. The processing conditions for the first stage compressor and the second stage compressor are shown in Table 2 below. Table 2 Performance data Extraction pressure in the second compression stage (kg / cm2) 1.057 2.624 Extraction temperature (° c) 40 40 Discharge pressure (kg / cm2) 2.84 7.049 Discharge temperature (° c) 80 80 Pressure ratio 2.686 2.686 Air inlet volume flow rate (m3 / h) at compressor flange 7027 2474 Mass flow rate (kg / h) 13271.6 13271.6 Drive unit power (kW) 753 Compressor speed (RPM) 3570 7474 Pressure between two stages Reduction (kg / cm2) 0.216 Quantitative and qualitative analysis of gas by gas chromatography at each compression stage. The results are shown in Table 3 below. This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 14 Clothing ------- l · ^-l · ------- line (please read the precautions on the back first) (Fill in this page again)

530121 V. Description of the invention (12 Table 3 Molecular weight of process gas First compression stage (% by weight) Second compression stage (% by weight) T2-butene__56.1 0.02 0.03 C2-butene__56.1 1.50 1.53 1,3-butadiene ~~~ 54.1 85.03 86.4 Methylacetylene 1,2-butadiene — 40.1 — ~~~~ _ 0.27 0.28 54.1 * —-— 4.65 4.70 Ethylacetylene ~ ———___ 4.1 1.40 1.39 vinyl acetylene C5 compound or above butadiene dimer ~ 52.1 — ~~ —_____ 4.72 4.52 70.1 • ——— 0.95 0.97 108.2 0.14 0.03 Water 18.0 0.04 0.02 Monomethylformimine 73.1 1.28 0.13 ο 1 kg / cm2 of nitrogen and 0.1 kg / cm2 of methane are introduced into the buffer gas inlets, which are located at the extraction and discharge sections of the first stage compressor respectively. The nitrogen and methane flow rates are 15 cubic meters. M / h and 10 m3 / h. When the butadiene gas is discharged from the first stage compressor and is pumped into the second compressor, 0.00 kg / cm² of methane is introduced into the second stage compressor for pumping.枭% 枭 口 '' burning flow ' 6 cubic meters / hour. The sealed oil is supplied to the compressor at a pressure of 5 · kg / cm2. In the first compression stage, the gas separated by the rancidity oil at the port of the rancidity oil is sampled and analyzed. The separated gas It is expressed on a weight basis using gas chromatography. Its composition is 53.26% nitrogen, 0.05% butadiene, 41.26% methane, and 4.83% hydrogen. In this way, the butadiene gas system is at a weight ratio of 0.1% or based on paper. Standards are applicable to China National Standard (CNS) A4 specifications (210 X 297 mm) -------- ^ Order 1, ------------ (Please read the precautions on the back before filling this page) Printed by the Employees' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 15 530121 A7 V. Description of the Invention Emissions printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. The discharge volume of used sealing oil is maintained at 640 to the cubed at the adjustment time. Cm / two hours, and then maintained at a rate of cubic centimeters per hour when the system is stable. In addition, continuous operation is possible without downtime due to mechanical seal assembly failure, even at the beginning of 26 months. 'Can be expected to be continuous Turn to 3 to 5 years. Comparative Example 1 This comparative example was performed using the same butadiene gas compressor of Example 1 and then evaluated the performance of the tritium, but the buffer gas of the present invention was used in the first compression stage in the sealing oil. After port σ_gas, composition analysis was performed using a gas chromatography analysis device. It can be seen that the separated body of rancidity oil port σ contains 90% by volume or more of butadiene gas. The leak rate of the used sealing oil is as high as 60, _cm3 / 2 hours. The shutdown time for the purification of butadiene is 9 months. -Comparative Example 1 The results obtained by comparing the shallow leakage of sealing oil with the comparative example are not shown in Figure 4. Taking the sealing treatment of the gas compressor according to Example i, as an example, the used sealing oil is reduced. It has also been found that the downtime of the succinic acid purification process can be extended by about 5 times or more. The advantage of such a method of bifurcating a butadiene gas compressor according to the present invention is that 'CV3 hydrocarbon gas is used as a buffer gas for a τ dilute compressor㈣ system to provide effective buffering, thereby significantly preventing foaming and opening of the sealing surface. , The system is simple to configure and easy to operate, the installation cost is reduced, and the useful body can be recycled. In addition, economic benefits were obtained due to the reduction in the cost of the distillate compressor and the cost of the tray and reboiler. I have described the present invention by way of example, you must understand the technique of using Qi Xie fruit ------- l · ------- (Please read the note on the back? Matters before filling out this page) μ Zhang's ruler

Description of the Invention The 04 language family is provided for illustration, not limitation. In view of the foregoing teachings, many modifications and changes can be made to the present invention. Therefore, it should be understood that within the scope of the patent claims, the present invention may be implemented in ways other than those specifically described. ------------------- P Order ------- line (please read the precautions on the back before filling this page) Staff Consumer Cooperatives of Intellectual Property Bureau of the Ministry of Economic Affairs The printed paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 17 530121 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the invention (15) Component label comparison 1 ... Machinery Sealing assembly 2 ... rotating ring 3 ... fixing ring 4,4 ', 4 "... carbon stuffing ring 5 ... o-ring 11 ... rotating ring 12 ... fixing ring 14 ... in Port 15 ... vent port 16,16 ', 16 "... carbon packing ring 21 ... mechanical seal assembly 23 ... intake port 24. " vent port 25 ... mechanical seal assembly 27 ... air inlet 29 ... rancid oil port 30 ... mechanical seal assembly 32. " air inlet 33 ... venture port 34 ... mechanical seal assembly 36 ... air inlet 37 ... venting port 38 ... mechanical seal assembly 40 " inlet port 41. .. Vent port 42 ... Mechanical seal assembly 44. "Inlet port 45 .... Vent port 48." Inlet port 49. "Vent port 52 ... Inlet port 53 ... Ventilation Port 54 ... rancidity oil port 101 ... gas 103 ... purge gas 104,104, ... oil recovery line 107-8 ... CV3 hydrocarbon gas 109-111 ... flow path 113,113 ', 115, 117 ... recovery line 116 ... flow path 118 ... flow path 120 ... extraction flow path 122 ... low pressure outreach process 123 ... flow 125 ... low pressure outreach process 126-7 ... Extraction flow path 201-2 ... Compressor (please read the precautions on the back before filling out this page) This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 18

Claims (1)

530121 6. Application scope 1. A method for sealing a butadiene gas compressor to increase the pressure of the butadiene gas after stripping from the stripper tube string purified and purified by the butyrene, the method It includes the following steps: a) supplying sealing oil to a plurality of sealing surfaces formed by the rotating ring and the fixed ring erected on the extraction part and the discharge part of the butadiene gas compressor; b) injecting nitrogen gas as a buffer gas into the inlet of the extraction part, And injecting Cl · 3 hydrocarbon gas as a buffer gas into one of the multiple inlets of the discharge section, or injecting only Ci-3 hydrocarbon gas into the two inlets as the buffer gas, each of which is installed in the extraction section and discharged The inward direction of each of the mechanical seal assemblies is prevented from flowing into the inside of the mechanical seal assembly; 〇 The butadiene gas and the buffer gas are discharged through the vents erected at each of the extraction section and the discharge section. The mixed gas; and d) recovering the sealing oil passing through the sealing surface through the recovery line, wherein the pressure of the buffer gas at the time of injection is maintained higher than the pressure of the mixed gas at the vent. 2. The oldest method as claimed in the patent application, wherein the Ci3 hydrocarbon gas is selected from the group consisting of methane, ethane, ethylene, propane and propylene. 3. The method according to the first scope of the patent application, wherein the air inlet and the air vent are composed of three obstructing rings, and the three carbon stuffing rings are spaced inward from the mechanical seal assembly at a fixed interval. It is formed by the space between the first carbon stuffing ring and the second carbon stuffing ring, and the vent: is formed by the space between the two carbon stuffing ring and the third carbon stuffing ring. 4 · If the method of applying for the scope W of the patent application, further includes—a kind of supply of nitrogen paper and paper standard (CNS) A4 specification 19 530121 6. The patent application scope of the mixture of gas and butadiene gas as low pressure Steps to remove gas from outreach department. 5. The method of claim 1 in the scope of the patent, further comprising a step of recovering the supply of the mixed gas of the c1-3 hydrocarbon gas and the butadiene gas as a fuel gas. 6. A method for benefiting a one-stage and two-stage compressor for increasing the pressure of the butadiene gas after stripping, which is discharged from the stripper column of the butene purification process, the method comprising the following steps: > hook Supply sealing oil to a plurality of sealing surfaces, which are formed by a rotating ring and a fixed ring mounted on each of the extraction section and the discharge section of the first compressor and the second compressor; i, ,, and e nitrogen as The buffer gas passes through the air inlet of the extraction section, and the Cl · 3 hydrocarbon gas is supplied as the buffer gas through the air inlet of the discharge section. In the first stage, a plurality of air intake sigma wipers are provided on each of the air inlets. The extraction portion of the first stage compressor and the discharge portion of each of the mechanical seal assemblies are directed inward, thereby preventing butadiene gas from flowing into the mechanical seal assembly; C) via each of the extraction portions installed in the first stage compressor And the first-stage vent of the exhaust port P to discharge a mixed gas of butadiene gas and buffer gas; d) supply Cm hydrocarbon gas as a buffer gas through the second-stage intake port; each of the intake ports is located at Second stage The gas extraction and discharge parts of the mechanical seal assembly are oriented inward, so that butadiene gas is prevented from flowing into the mechanical seal assembly; This paper is suitable for the financial and domestic (CNS) A4 secret (2Ϊ07 ^ 7 ^ " 20 VI. Where the scope of application for patents is released), the work is made by the second stage vent of the second stage compressor and the second stage vent of the compressor to discharge dilute dilute gas and buffer gas Gas; and f) 'recover the sealing oil through the sealing surface through the recovery line of each of the first-stage compressor and the second-stage retraction machine, wherein the buffer gas pressure at the time of injection is maintained above the vent gas pressure. 8. 7. The method according to item 6 of the scope of patent application, wherein the air inlet and the air vent are composed of three carbon stuffing rings, and the three carbon stuffing rings are spaced at a fixed interval, and the seal assembly is spaced inwardly. 'The air inlet is formed by the space between the first carbon stuffing ring and the second carbon stuffing ring, and the air vent is formed by the space between the first and second carbon stuffing ring. -A sealing system for a butadiene gas compressor, including: line ▲ A mechanical seal assembly, which is installed in a butadiene gas shrinking machine, the assembly includes a fixed ring, a rotating ring, and a zero ring. The fixed ring contacts the rotating ring to form a sealing surface, and the o-ring system forms a seal between the mechanical parts of the compressor; a sealing oil feeding device is used to feed the sealing oil to the sealing surface, so Yu Ding Lubrication and cooling of the sealing surface during the sealing of a two-lean gas compressor;-the first carbon packing ring, the second carbon packing ring and a third carbon packing ring, which are spaced at regular intervals to form a buffer gas inlet. Gas port and a vent for discharging a mixed gas of butadiene gas and buffer gas after buffering. These carbon stuffing rings are set at the machine's Zhang Weiwei Shiguan Jiaxian (CNS) A4 secret coffee 530121 The scope of the patent application is for the mechanical seal assembly to the butcher & ▲ 丄 direction to prevent butadiene gas from flowing into the machine only ^ the assembly; and for the weapon seal a sealing oil treatment option. ^, In the heart, including a The oil recovery line passes through the seal surface of the seal surface to recover the mountain seal oil with μ and a rancid oil port, where the sealing system is a cylinder extracting section of an I and M shrinking machine and Emissions Department. Side draw -------- tli " * ------- line (please read the precautions on the back before filling this page) Printed by the Intellectual Property Bureau of the Ministry of Economic Affairs Employee Cooperatives Paper size applicable to China Standard (CNS) A4 size (210 X 297 mm) 22