Sulfuric acid method alkylation reactor sealing and flushing system and method

Abstract

The invention relates to the technical field of alkylation device transformation in petroleum refining, in particular to a sulfuric acid method alkylation reactor sealing and flushing system and a sulfuric acid method alkylation reactor sealing and flushing method. The shaft sleeve is sequentially connected in series with a protective sleeve, an auxiliary shaft sleeve, a first-stage seal, a self-aligning roller bearing, a second-stage seal, a throttling ring and a wedge-shaped shaft sticking device from a medium side to an atmosphere side; the end face outer diameters, the end face inner diameters and the balance diameters of the connecting ends of the movable rings and the static rings in the first-stage seal and the second-stage seal and the materials of the movable rings and the static rings are technically improved creatively, so that the end face temperature rise is reduced, a liquid film between the movable rings and the static rings is formed more stably, and the end face closing performance and the large torque mutability resistance of the seal are improved; medium leakage caused by mutational rub-impact or edge breakage of the movable and static rings is effectively prevented, and the purpose of long-period operation of a core equipment reactor of an alkylation device is achieved. The problem of high sealing leakage rate of an alkylation device reactor in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of transformation of alkylation devices in petroleum refining, in particular to a sealing and flushing system and method for a sulfuric acid alkylation reactor. Background Art

[0002] The alkylation unit is a device that reacts isobutane and C4 olefins to produce high-octane alkylate oil. The product features are: zero aromatics, zero benzene, zero olefins, high octane, low sulfur, low vapor pressure, and good stability, low toxicity, no corrosion, and easy to store and transport. As a gasoline blending component, it can improve the starting performance of the car, make the gasoline burn completely, reduce the CO content in the car exhaust, and reduce hydrocarbons. It is an ideal blending component for high-octane gasoline and will play a key role in the production of high-octane gasoline, with great economic value.

[0003] The key core equipment in the alkylation unit is two horizontal stirred reactors, which contain seals and matching seal flushing oil stations, stirring paddles, internal circulation sleeves and U-shaped heat exchange tube bundles for removing reaction heat. In the prior art, according to the mechanical seal standard API682, the PLAN32+PLAN54+PLAN61 flushing method is adopted to provide circulating flushing sealing liquid for the seal, remove the heat of the seal cavity, and ensure the normal operation of the seal. Figures 1 to 3 The PLAN32 flushing method in the API682 standard mainly uses external flushing media to enter the sealing cavity through the flushing interface to lubricate and remove heat from the dynamic and static rings on the medium side of the sealing cavity. The PLAN54 flushing method in the API682 standard mainly uses an external pressurized isolation tank to provide clean sealing flushing liquid to the sealing cavity. The sealing flushing liquid circulates to remove the heat of the dynamic and static rings on the atmospheric side of the sealing cavity. What is different from the PLAN32 method is that the PLAN54 flushing liquid enters the circulation from the isolation liquid inlet and flows out from the isolation liquid outlet. The PLAN61 flushing method in the API682 standard is basically the same as the PLAN54 scheme. It also lubricates and removes heat from the dynamic and static rings on the medium side of the sealing cavity. It is mainly to assist the PLAN54 flushing method. This method is not used in daily operation. The inlet and outlet are sealed with plugs to prevent contamination in the sealing cavity.

[0004] However, the existing reactor seal has an unreasonable seal design, resulting in high heat generation on the seal end face, easy friction and collapse of the dynamic and static rings, and easy corrosion of auxiliary seals and other components by the medium. This leads to a high leakage rate and high maintenance cost, and cannot meet the goal of long-term operation of the core equipment of the alkylation unit. Summary of the invention

[0005] In view of the problem of high reactor seal leakage rate in the prior art, the present invention provides a sulfuric acid alkylation reactor sealing and flushing system and method.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a seal for a sulfuric acid alkylation reactor, comprising a shaft sleeve sleeved on the outer side of a shaft, wherein the shaft sleeve is serially connected with a protective sleeve, an auxiliary shaft sleeve, a primary seal, a spherical roller bearing, a secondary seal, a throttling ring and a wedge-shaped shaft clamp in sequence from the medium side to the atmosphere side;

[0008] The primary seal includes a sealing medium side dynamic ring, which is connected to a sealing medium side static ring; the auxiliary sleeve is arranged between the protective sleeve and the sealing medium side dynamic ring, and is used to adjust the balance diameter of the sealing medium side dynamic ring; the difference between the inner diameter of the end surface of the connection end between the sealing medium side dynamic ring and the sealing medium side static ring and the outer diameter of the sleeve is 6mm±0.5mm; the difference between the outer diameter of the end surface of the connection end between the sealing medium side dynamic ring and the sealing medium side static ring and the outer diameter of the sleeve is 16mm±0.5mm; the difference between the balance diameter of the sealing medium side dynamic ring and the outer diameter of the sleeve is 8mm±0.5mm;

[0009] The secondary seal includes a dynamic ring on the sealing atmosphere side, which is connected to a static ring on the sealing atmosphere side; a groove is provided on the sleeve at the corresponding position of the secondary seal, which is used to adjust the balance diameter of the dynamic ring on the sealing atmosphere side; the difference between the outer diameter of the end surface of the connection end between the dynamic ring on the sealing atmosphere side and the static ring on the sealing atmosphere side and the outer diameter of the sleeve is 8mm±0.5mm; the difference between the inner diameter of the end surface of the connection end between the dynamic ring on the sealing atmosphere side and the static ring on the sealing atmosphere side and the outer diameter of the sleeve is -3mm±0.5mm; the difference between the balance diameter of the dynamic ring on the sealing atmosphere side and the outer diameter of the sleeve is 0mm.

[0010] Preferably, the material of the atmosphere-sealing dynamic ring is graphite.

[0011] Preferably, the spherical roller bearing is limited by a round nut.

[0012] Preferably, a stop washer is provided between the spherical roller bearing and the round nut.

[0013] Preferably, the materials of the sealing medium side dynamic ring and the sealing medium side static ring are both pressureless sintered silicon carbide.

[0014] The present invention also provides a flushing system for the seal of the sulfuric acid alkylation reactor, comprising an oil tank, an oil pump is arranged inside the oil tank, the oil pump outlet is connected to the atmospheric side flushing medium inlet of the reactor seal, the atmospheric side flushing medium outlet of the reactor seal is connected to the inlet of the oil tank; the oil pump outlet is also connected to an energy storage tank; the reactor seal medium side flushing inlet is connected to the reactor.

[0015] Preferably, a filter is connected to the inlet of the oil pump.

[0016] Preferably, a regulating valve is provided between the sealed atmospheric-side flushing medium outlet of the reactor and the inlet of the oil tank.

[0017] Preferably, a pressure gauge and a second ball valve are provided between the regulating valve and the sealed atmospheric flushing medium outlet of the reactor.

[0018] A flushing method using the above flushing system comprises the following steps:

[0019] Make the pressure of the air bag inside the energy storage tank 0.05MPa~0.1MPa higher than the target pressure of the flushing fluid on the atmospheric side;

[0020] Make the liquid level of the flushing medium on the atmosphere side of the oil tank account for 65% to 85% of the volume of the oil tank;

[0021] Turn on the oil pump and adjust the oil pump pressure so that the flushing pressure on the atmosphere side is 0.14MPa to 0.41MPa higher than the flushing liquid pressure on the medium side;

[0022] Start the medium side flushing, so that the pressure of the medium side flushing liquid before entering the reactor seal is 0.15MPa to 0.35MPa higher than the pressure inside the reactor;

[0023] After the oil pump pressure and the medium-side flushing liquid pressure are adjusted, feed the reactor until the internal pressure of the reactor reaches the normal production pressure;

[0024] After the internal pressure of the reactor reaches the normal production pressure, the pressure of the oil pump is adjusted to the target pressure of the atmospheric side flushing liquid, so that the atmospheric side flushing liquid enters the sealing cavity and forms a liquid film between the sealing atmospheric side dynamic ring and the sealing atmospheric side static ring before returning to the oil tank; the pressure of the medium side flushing liquid is adjusted to the target pressure of the medium side flushing liquid, so that the medium side flushing liquid enters the sealing cavity and forms a liquid film between the sealing medium side dynamic ring and the sealing medium side static ring;

[0025] After adjusting the oil pump pressure and the atmospheric side flushing medium pressure to the target pressure, check whether there is leakage at each sealing point;

[0026] After confirming that there is no leakage at each sealing point, start the stirring motor and start production;

[0027] After the production is completed, turn off the stirring motor, release the pressure inside the reactor, stop flushing the medium side, and complete the seal flushing.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The invention discloses a seal for a sulfuric acid alkylation reactor, comprising a sleeve sleeved on the outer side of a shaft, wherein the sleeve is serially connected with a protective sleeve, an auxiliary sleeve, a primary seal, a spherical roller bearing, a secondary seal, a throttling ring and a wedge-shaped shaft clamp in sequence from the medium side to the atmosphere side; the difference between the inner diameter of the end face of the connection end between the sealing medium side dynamic ring and the sealing medium side static ring in the primary seal and the outer diameter of the sleeve is creatively set to 6mm±0.5mm, the difference between the outer diameter of the end face of the connection end between the sealing medium side dynamic ring and the sealing medium side static ring and the outer diameter of the sleeve is set to 16mm±0.5mm, and the difference between the balance diameter and the outer diameter of the sleeve is set to 8mm±0.5mm, so that the sealing end face can be better closed when the elastic force difference is not large, and the seal can be effectively prevented from being unable to close the end face due to a sudden change in torque during the start-stop process, causing the seal to be The invention can creatively prevent leakage of the seal; creatively set a groove on the sleeve at the position corresponding to the secondary seal to adjust the balance diameter of the dynamic ring on the atmosphere side of the seal; the difference between the outer diameter of the end face of the connection end between the dynamic ring on the atmosphere side of the seal and the static ring on the atmosphere side and the outer diameter of the sleeve is 8mm±0.5mm; the difference between the inner diameter of the end face of the connection end between the dynamic ring on the atmosphere side of the seal and the static ring on the atmosphere side and the outer diameter of the sleeve is -3mm±0.5mm; the difference between the balance diameter of the dynamic ring on the atmosphere side of the seal and the outer diameter of the sleeve is 0mm. This setting can make the thickness of the dynamic rings on the atmosphere side and the medium side thicker and have a higher pressure-bearing capacity of up to 10MPa, which can effectively avoid the problem of sealing ring cracking caused by excessive internal pressure, and reduce the heat generation of the seal to 829008J / Hr, which is nearly 50000J / Hr lower than the heat generation of the original design. The heat generated by the end faces of the primary and secondary seals of the reactor seal is reduced, the temperature rise of the end faces is reduced, and the possibility of liquid vaporization at the end faces is reduced, making the liquid film formation between the dynamic ring on the sealing medium side and the static ring on the sealing medium side more stable. At the same time, the end face closure and resistance to large torque mutations of the seal are improved, which can effectively prevent accidents caused by medium leakage due to high heat generated on the end faces between the dynamic ring on the sealing medium side and the static ring on the sealing medium side, reduce the equipment maintenance cost due to medium leakage corrosion, and improve the stability of equipment long-term operation and production.

[0030] The material of the sealing atmosphere side dynamic ring is graphite. Since graphite has good self-lubricating properties, it can effectively reduce the possibility of serious wear caused by dry friction on the end faces between the sealing atmosphere side dynamic ring and the sealing atmosphere side static ring, thereby reducing the medium leakage caused by the wear of the sealing atmosphere side dynamic ring and affecting production.

[0031] A plurality of first sealing rings are arranged between the shaft sleeve and the shaft, which can further improve the sealing effect of the reactor.

[0032] The material of the dynamic ring on the sealing medium side and the static ring on the sealing medium side is pressureless sintered silicon carbide. Ordinary reaction-sintered silicon carbide is silicon carbide obtained by the reaction of silicon and carbon. The free silicon content in the final material is usually 8% to 12%. The free silicon will be corroded by strong acids and strong alkalis. API682 recommends that the pH value be between 4 and 11. The pressureless sintered silicon carbide is completely composed of silicon carbide, which is formed by pure silicon carbide powder and using a non-oxidizing sintering agent. The structure is uniform silicon carbide and does not contain free silicon. This characteristic makes the pressureless sintered silicon carbide chemically stable in all corrosive environments, so it has better resistance to chemical corrosion and more stable and reliable performance.

[0033] The present invention provides a flushing system for the seal of the sulfuric acid alkylation reactor, comprising an oil tank, an oil pump is arranged inside the oil tank, the oil pump outlet is connected to the atmospheric side flushing medium inlet of the reactor seal, and the atmospheric side flushing medium outlet of the reactor seal is connected to the inlet of the oil tank; the oil pump outlet is also connected to an energy storage tank, so that the atmospheric side flushing liquid can be filled into the space between the atmospheric side dynamic ring of the seal and the atmospheric side static ring of the seal to form a liquid film, which can lubricate and take away heat at the same time, further reducing the possibility of leakage caused by wear of the atmospheric side dynamic and static rings; the reactor seal medium side flushing inlet is connected to the reactor, so that the medium can be filled into the space between the atmospheric side dynamic ring of the seal and the atmospheric side static ring of the seal to form a liquid film, which can lubricate and take away heat at the same time.

[0034] The inlet of the oil pump is connected with a filter, which can effectively filter out impurities in the atmosphere-side flushing liquid to prevent damage to the oil pump.

[0035] A regulating valve is provided between the flushing medium outlet on the atmosphere side of the reactor seal and the inlet of the oil tank, and is used to adjust the flushing medium outlet flow on the atmosphere side of the reactor seal.

[0036] A pressure gauge and a second ball valve are provided between the regulating valve and the atmosphere-side flushing medium outlet of the reactor seal, for monitoring the atmosphere-side flushing medium outlet pressure of the reactor seal and for pressure regulation.

[0037] The present invention also provides a flushing method using the above-mentioned flushing system, which controls the pressure of the air bag inside the energy storage tank to be 0.05MPa-0.1MPa higher than the target pressure of the medium-side flushing liquid, controls the liquid level of the atmospheric side flushing medium inside the oil tank to account for 65%-85% of the volume of the oil tank, adjusts the pressure of the oil pump, makes the pressure of the atmospheric side flushing liquid 0.14MPa-0.41MPa higher than the pressure of the medium-side flushing liquid, makes the pressure of the medium-side flushing liquid before entering the reactor seal higher than the pressure inside the reactor by 0.15MPa-0.35MPa, makes the reactor slowly feed until the pressure inside the reactor reaches the normal production pressure, adjusts the pressure of the oil pump to the target pressure of the atmospheric side flushing liquid, and makes the atmospheric side flushing liquid enter the seal The inside of the sealed cavity is returned to the oil tank after a liquid film is formed between the dynamic ring on the sealed atmosphere side and the static ring on the sealed atmosphere side; the pressure of the flushing liquid on the medium side is adjusted to the target pressure of the flushing liquid on the medium side, so that the flushing liquid on the medium side enters the sealed cavity and forms a liquid film between the dynamic ring on the sealed medium side and the static ring on the sealed medium side; after adjusting the pressure of the oil pump and the pressure of the flushing medium on the atmosphere side to the target pressure, check whether there is leakage at each sealing point; after confirming that there is no leakage at each sealing point, start the stirring motor to start production; after the production is completed, turn off the stirring motor, and after the pressure inside the reactor is relieved and replaced, stop flushing on the sealed medium side first, and then stop flushing on the sealed atmosphere side. Before stopping flushing on the atmosphere side, make sure that the pressure inside the reactor is 0MPa and end the sealing flushing. By adjusting and controlling the system, the stability of the equipment operation is further improved, making it more suitable for long-term production requirements.

[0038] After actual testing, the method and system can make the two reactors of the alkylation unit run for nearly 25 months before the major overhaul, and no shutdown caused by sealing failure occurred during the period. The goal of "zero leakage" and safe, stable and long-term operation of the reactor seal of the alkylation unit was achieved. Compared with the reactor seal of similar units, the number of overhauls was reduced by at least 4 units in the two-year period, and the unplanned shutdown for maintenance was eliminated for a total of about 16 to 18 days, saving maintenance costs, ensuring safe and environmentally friendly long-term operation and greatly improving economic benefits.

[0039] According to the calculation of the processing volume lost when a single reactor of the alkylation unit is cut out for maintenance: the processing volume of the alkylation unit during the operation of a single unit is at least 10-12 t / h less than that of two units running at the same time, and the maintenance time of each reactor is at least 6 days, including 4 days of isolation replacement and 2 days of maintenance. Therefore, the processing volume lost for each reactor per maintenance is about 6 days*24 hours*10 t / h=1440 tons. The raw material of the alkylation unit is liquefied gas, and the octane number of the alkylation product oil is generally around 97. According to the difference between the ex-factory price of 95# gasoline and the price of liquefied gas, the processing volume loss of each reactor per maintenance is calculated to be at least 3.42 million yuan. According to the calculation that the imported seal of the alkylation reactor of the same unit is overhauled once a year, at least 2 overhauls of the alkylation unit reactor have been effectively avoided in the past year. According to the above calculation of the benefits of the loss of a single unit per maintenance, the cumulative efficiency increase in the past year is about: 6.84 million yuan. It can be seen that this bill has produced huge economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural diagram of the PLAN32 flushing seal chamber in the API682 standard in the prior art.

[0041] Figure 2 This is a structural diagram of the PLAN54 flushing seal chamber in the API682 standard in the prior art.

[0042] Figure 3 This is a structural diagram of the PLAN61 flushing seal chamber in the API682 standard in the prior art.

[0043] Figure 4 The diagram is a schematic diagram of a seal of a sulfuric acid alkylation reactor according to the present invention.

[0044] Figure 5 This is a structural diagram of a seal flushing system for a sulfuric acid alkylation reactor of the present invention.

[0045] Figure 6 The present invention is a flow chart of a seal flushing method for a sulfuric acid alkylation reactor.

[0046] Among them, 1-protective sleeve, 2-sealing ring, 3-fastening screw, 4-auxiliary sleeve, 5-primary seal, 6-sleeve, 7-round nut, 8-stop washer, 9-spherical roller bearing, 10-secondary seal, 11-wedge shaft holder, 12-throttling ring, 13-sealing medium side dynamic ring, 14-sealing medium side static ring, 15-sealing atmosphere side dynamic ring, 16-sealing atmosphere side static ring, 17-drain valve, 18-motor, 19-check valve, 20-oil tank, 21-oil pump, 22-reactor seal, 23-energy storage tank, 24-filter, 25-regulating valve, 26-pressure gauge, 27-second ball valve, 28-first ball valve, 29-third ball valve. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0050] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0051] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0052] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0054] See also Figure 4 The present invention discloses a seal for a sulfuric acid alkylation reactor, comprising a shaft sleeve 6 sleeved on the outer side of a shaft, wherein the shaft sleeve 6 is serially connected with a protective sleeve 1, an auxiliary shaft sleeve 4, a primary seal 5, a self-aligning roller bearing 9, a secondary seal 10, a throttle ring 12 and a wedge-shaped shaft clamp 11 in sequence from the medium side to the atmosphere side;

[0055] A plurality of first sealing rings 2 are arranged between the shaft sleeve 6 and the shaft; the primary seal 5 comprises a sealing medium side dynamic ring 13, and the sealing medium side dynamic ring 13 is connected to a sealing medium side static ring 14;

[0056] The auxiliary sleeve 4 is arranged between the protective sleeve 1 and the sealing medium side dynamic ring 13, and is used to adjust the balance diameter of the sealing medium side dynamic ring 13; the sleeve 4 and the protective sleeve 1 are fastened by a fastening screw 3;

[0057] The difference between the inner diameter of the connecting end of the sealing medium side dynamic ring 13 and the sealing medium side static ring 14 and the outer diameter of the shaft sleeve 6 is 6 mm ± 0.5 mm;

[0058] The difference between the outer diameter of the connecting end of the sealing medium side dynamic ring 13 and the sealing medium side static ring 14 and the outer diameter of the shaft sleeve 6 is 16 mm ± 0.5 mm;

[0059] The difference between the balance diameter and the outer diameter of the sleeve 6 is 8 mm ± 0.5 mm;

[0060] The spherical roller bearing 9 is limited by the round nut 7, and a stop washer 8 is arranged between the spherical roller bearing 9 and the round nut 7;

[0061] The secondary seal 10 includes a dynamic ring 15 for sealing the atmosphere, and the dynamic ring 15 for sealing the atmosphere is connected to a static ring 16 for sealing the atmosphere; a groove is provided on the shaft sleeve 6 at a position corresponding to the secondary seal 10, for adjusting the balance diameter of the dynamic ring 15 for sealing the atmosphere; the difference between the outer diameter of the end surface of the connection end between the dynamic ring 15 for sealing the atmosphere and the static ring 16 for sealing the atmosphere and the outer diameter of the shaft sleeve 6 is 8mm±0.5mm; the difference between the inner diameter of the end surface of the connection end between the dynamic ring 15 for sealing the atmosphere and the static ring 16 for sealing the atmosphere and the outer diameter of the shaft sleeve 6 is -3mm±0.5mm; the difference between the balance diameter of the dynamic ring 15 for sealing the atmosphere and the outer diameter of the shaft sleeve is 0mm;

[0062] Preferably, the material of the atmosphere-sealing dynamic ring 15 is graphite; the material of the medium-sealing dynamic ring 13 and the medium-sealing static ring 14 is pressureless sintered silicon carbide.

[0063] See also Figure 5The present invention also provides a flushing system for the seal of the sulfuric acid alkylation reactor, comprising an oil tank 20, a drain port is provided at the bottom of the oil tank 20, a drain valve 17 is provided at the drain port, an oil pump 21 is provided inside the oil tank 20, the oil pump 21 is connected to a motor 18, and a filter 24 is connected to the inlet of the oil pump 21; a check valve 19 is provided at the outlet of the oil pump 21, a first ball valve 28 is provided between the check valve 19 and the outlet of the oil pump 21, and the outlet of the oil pump 21 is connected to the atmospheric side of the reactor seal 22 for flushing. The medium inlet and the atmospheric side flushing medium outlet of the reactor seal 22 are connected to the inlet of the oil tank 20; a regulating valve 25 is arranged between the atmospheric side flushing medium outlet of the reactor seal 22 and the inlet of the oil tank 20, and a pressure gauge 26 and a second ball valve 27 are arranged between the regulating valve 25 and the atmospheric side flushing medium outlet of the reactor seal 22; the outlet of the oil pump 21 is also connected to the energy storage tank 23, and a third ball valve 29 is arranged between the energy storage tank 23 and the outlet of the oil pump 21; the medium inlet of the reactor seal 22 is connected to the reactor.

[0064] See also Figure 6 A flushing method of the flushing system as described above comprises the following steps:

[0065] S1: Make the pressure of the air bag inside the energy storage tank 23 higher than the pressure of the flushing liquid on the atmospheric side by 0.05MPa to 0.1MPa;

[0066] S2: Make the liquid level of the flushing medium on the atmosphere side of the oil tank 20 account for 65% to 85% of the volume of the oil tank 20;

[0067] S3: Turn on the oil pump 21 and adjust the pressure of the oil pump 21 so that the flushing pressure on the atmosphere side is 0.14 MPa to 0.41 MPa higher than the target pressure of the flushing liquid on the medium side;

[0068] S4: Start the medium side flushing, so that the pressure of the medium side flushing liquid before entering the reactor seal is 0.15MPa to 0.35MPa higher than the pressure inside the reactor;

[0069] S5: After the pressure of the oil pump 21 and the pressure of the medium-side flushing liquid are adjusted, the reactor is fed until the internal pressure of the reactor reaches the normal production pressure;

[0070] S6: After the internal pressure of the reactor reaches the normal production pressure, the pressure of the oil pump 21 is adjusted to the target pressure of the atmospheric side flushing liquid, so that the atmospheric side flushing liquid enters the sealed cavity and forms a liquid film between the sealed atmospheric side dynamic ring 15 and the sealed atmospheric side static ring 16, and then returns to the oil tank 20; the pressure of the medium side flushing liquid is adjusted to the target pressure of the medium side flushing liquid, so that the medium side flushing liquid enters the sealed cavity, and forms a liquid film between the sealed medium side dynamic ring 13 and the sealed medium side static ring 14;

[0071] S7: After adjusting the pressure of the oil pump 21 and the pressure of the flushing medium on the atmospheric side to the target pressure, check whether there is leakage at each sealing point;

[0072] S8: After confirming that there is no leakage at each sealing point, start the stirring motor and enter production;

[0073] S9: After the production is completed, turn off the stirring motor, and after the pressure relief and replacement of the reactor, first stop the flushing of the sealed medium side, then stop the flushing of the sealed atmosphere side, and end the flushing of the seal; before stopping the flushing of the atmosphere side, make sure that the pressure inside the reactor is 0MPa. After the stirring motor is stable for 1-2 hours and the pressure relief and replacement of the reactor is stable for 1-2 hours, stop the flushing of the seal on the atmosphere side. It is particularly important to note that after the overhaul, after the oil pump 21 is started for the first time, the pressure relief valve to the oil tank 20 should be opened to exhaust the residual air in the pipeline to prevent the gas from entering the sealed cavity and causing a sealing failure; secondly, as long as there is a corrosive medium and pressure in the reactor, the atmospheric side flushing liquid transmission should never be stopped, and it is necessary to ensure that the atmospheric side flushing pressure is 0.15MPa-0.41MPa higher than the medium side flushing pressure, and at the same time, the pressure before the medium side flushing pressure enters the reactor seal is 0.15MPa-0.35MPa higher than the pressure inside the reactor; that is, ensure that the atmospheric side flushing pressure> the medium side flushing pressure> the reactor internal pressure to avoid the medium, i.e., concentrated sulfuric acid, etc., which is caused by the drop in the atmospheric side flushing pressure and damage to the seal.

[0074] At the same time, if you want to further improve the stable operation cycle of the equipment, you should also optimize the paddle differential pressure and current operation, that is, there are pressure points inside and outside the draft tube near the paddle of the reactor, which can monitor the paddle pressure difference, thereby monitoring the acid-hydrocarbon emulsification mixing. At the same time, the current can also directly reflect the acid-hydrocarbon mixing ratio. When the ratio between acid and hydrocarbon decreases, the current will decrease. If the paddle differential pressure is low, it may be caused by paddle wear or low acid-hydrocarbon ratio. If the current or paddle differential pressure drops suddenly, it is very likely that the paddle is damaged, resulting in a short circuit of the reaction emulsion, that is, the inside and outside of the draft tube are connected. If the paddle is damaged, it will cause dynamic imbalance of the rotor and also cause seal leakage. The pressure tube should be cleaned regularly and flushed with reaction effluent once a week. The recommended frequency is once a week to remove the coke formed in the reaction and ensure accurate readings.

[0075] Control the stable process operation and feed components: The process operation fluctuates greatly, which will cause the load of the stirring paddle to change. At the same time, when the agitator is started, since the stirring medium is an acid-hydrocarbon mixture, the motor is started instantly, and the rotating shaft is subjected to a huge torque, which will impact the seal. In production, there has also been a huge noise at the stirring paddle when the motor is started, which once again confirms that the specific gravity increases after the acid-hydrocarbon mixture, and the instantaneous start of the motor has an impact on the stirring paddle and the seal. The acid should be dropped slowly to avoid uneven acid distribution causing excessive stirring torque. Secondly, the motor should be started when the acid drop amount does not exceed 60% of the normal production acid amount, which can minimize the impact on the stirring paddle. When the feed is composed of C3, C4 and C5 olefins, these different olefin feeds can react to generate compounds with different product qualities, and the acid consumption is also different, resulting in different emulsion densities in the alkylation reactor. The long-term torque alternation of the stirring paddle leads to stress concentration fatigue damage, and in severe cases, there may be a risk of seal leakage or stirring paddle cracking. Therefore, while optimizing the operation, the feed components must also be stabilized and regularly tested to ensure that they meet the standards. It can also avoid accidents caused by seal leakage to a certain extent.

[0076] Take two existing reactors as examples and label them as A and B for comparison. The measured operating parameters are shown in the following table:

[0077]

[0078]

[0079] Take two reactors as an example, denoted as C and D, both of which are equipped with the seal and system provided by the present invention, and the flushing process is controlled by the above method. The measured operating parameters are shown in the following table:

[0080]

[0081] It can be seen that compared with the prior art, after the seal, system and flushing method provided by the present invention are improved and optimized, the main operating parameters of the reactor, such as vibration, bearing temperature, seal heat, emulsification effect of acid-hydrocarbon mixture, etc., have been greatly improved. In particular, after the seal modification, no drop of seal oil leaks during operation, which completely achieves the environmental protection goal of zero leakage of the reactor seal.

[0082] After actual testing, the method and system can make the two reactors of the alkylation unit run for nearly 25 months before the major overhaul, and no shutdown caused by sealing failure occurred during the period. The goal of "zero leakage" and safe, stable and long-term operation of the reactor seal of the alkylation unit was achieved. Compared with the reactor seal of similar units, the number of overhauls was reduced by at least 4 units in the two-year period, and the unplanned shutdown for maintenance was eliminated for a total of about 16 to 18 days, saving maintenance costs, ensuring safe and environmentally friendly long-term operation and greatly improving economic benefits.

[0083] According to the calculation of the processing volume lost when a single reactor of the alkylation unit is cut out for maintenance: the processing volume of the alkylation unit during the operation of a single unit is at least 10-12 t / h less than that of two units running at the same time, and the maintenance time of each reactor is at least 6 days, including 4 days of isolation replacement and 2 days of maintenance. Therefore, the processing volume lost for each reactor per maintenance is about 6d*24h*10t / h=1440t. The raw material of the alkylation unit is liquefied gas, and the octane number of the alkylation product oil is generally around 97. According to the difference between the ex-factory price of 95# gasoline and the price of liquefied gas, the processing volume loss of each reactor per maintenance is calculated to be at least 3.42 million yuan. According to the calculation that the imported seal of the alkylation reactor of the same unit is overhauled once a year, at least 2 overhauls of the alkylation unit reactor have been effectively avoided in the past year. According to the above calculation of the benefits of the loss of a single unit per maintenance, the cumulative efficiency increase in the past year is about: 6.84 million yuan. It can be seen that this plan has produced huge economic benefits.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A sulfuric acid alkylation reactor seal, characterized in that: The invention comprises a shaft sleeve (6) sleeved on the outer side of the shaft, wherein the shaft sleeve (6) is connected in series with a protective sleeve (1), an auxiliary shaft sleeve (4), a primary seal (5), a spherical roller bearing (9), a secondary seal (10), a throttle ring (12) and a wedge-shaped shaft clamp (11) in sequence from the medium side to the atmosphere side; The primary seal (5) comprises a sealing medium side dynamic ring (13), and the sealing medium side dynamic ring (13) is connected to a sealing medium side static ring (14); the auxiliary sleeve (4) is arranged between the protective sleeve (1) and the sealing medium side dynamic ring (13), and is used to adjust the balance diameter of the sealing medium side dynamic ring (13); the difference between the inner diameter of the end surface of the connection end between the sealing medium side dynamic ring (13) and the sealing medium side static ring (14) and the outer diameter of the sleeve (6) is 6 mm ± 0.5 mm; the difference between the outer diameter of the end surface of the connection end between the sealing medium side dynamic ring (13) and the sealing medium side static ring (14) and the outer diameter of the sleeve (6) is 16 mm ± 0.5 mm; the difference between the balance diameter of the sealing medium side dynamic ring (13) and the outer diameter of the sleeve (6) is 8 mm ± 0.5 mm; The secondary seal (10) comprises a dynamic ring (15) on the sealing atmosphere side, and the dynamic ring (15) on the sealing atmosphere side is connected to a static ring (16) on the sealing atmosphere side; a groove is provided on the shaft sleeve (6) at a position corresponding to the secondary seal (10) for adjusting the balance diameter of the dynamic ring (15) on the sealing atmosphere side; the difference between the outer diameter of the end surface of the connection end between the dynamic ring (15) on the sealing atmosphere side and the static ring (16) on the sealing atmosphere side and the outer diameter of the shaft sleeve (6) is 8 mm ± 0.5 mm; the difference between the inner diameter of the end surface of the connection end between the dynamic ring (15) on the sealing atmosphere side and the static ring (16) on the sealing atmosphere side and the outer diameter of the shaft sleeve (6) is -3 mm ± 0.5 mm; and the difference between the balance diameter of the dynamic ring (15) on the sealing atmosphere side and the outer diameter of the shaft sleeve (6) is 0 mm.

2. The seal of sulfuric acid alkylation reactor according to claim 1, characterized in that: The material of the atmosphere-sealing dynamic ring (15) is graphite.

3. The seal of sulfuric acid alkylation reactor according to claim 1, characterized in that: The spherical roller bearing (9) is limited in position by a round nut (7).

4. The seal of sulfuric acid alkylation reactor according to claim 3, characterized in that: A stop washer (8) is arranged between the spherical roller bearing (9) and the round nut (7).

5. The seal of sulfuric acid alkylation reactor according to any one of claims 1 to 4, characterized in that: The materials of the sealing medium side dynamic ring (13) and the sealing medium side static ring (14) are both pressureless sintered silicon carbide.

6. A flushing system for a sulfuric acid alkylation reactor seal comprising the seal of any one of claims 1 to 5, characterized in that: The invention comprises an oil tank (20), wherein an oil pump (21) is arranged inside the oil tank (20), the outlet of the oil pump (21) is connected to the atmospheric side flushing medium inlet of the reactor seal (22), and the atmospheric side flushing medium outlet of the reactor seal (22) is connected to the inlet of the oil tank (20); the outlet of the oil pump (21) is also connected to an energy storage tank (23); and the medium side flushing inlet of the reactor seal (22) is connected to the reactor.

7. The seal flushing system for sulfuric acid alkylation reactor according to claim 6, characterized in that: The inlet of the oil pump (21) is connected to a filter (24).

8. The sulfuric acid alkylation reactor flushing system according to claim 6, characterized in that: A regulating valve (25) is provided between the atmospheric side flushing medium outlet of the reactor seal (22) and the inlet of the oil tank (20).

9. The sulfuric acid alkylation reactor flushing system according to claim 8, characterized in that: A pressure gauge (26) and a second ball valve (27) are provided between the regulating valve (25) and the atmospheric flushing medium outlet of the reactor seal (22).

10. A flushing method using the flushing system according to any one of claims 6 to 9, characterized in that: The following steps are involved: The pressure of the air bag inside the energy storage tank (23) is made 0.05MPa to 0.1MPa higher than the target pressure of the flushing liquid on the atmospheric side; The liquid level of the flushing medium on the atmosphere side of the oil tank (20) accounts for 65% to 85% of the volume of the oil tank (20); Turning on the oil pump (21) and adjusting the pressure of the oil pump (21) so that the flushing pressure on the atmosphere side is 0.14 MPa to 0.41 MPa higher than the flushing liquid pressure on the medium side; Start the medium side flushing, so that the pressure of the medium side flushing liquid before entering the reactor seal (22) is 0.15MPa to 0.35MPa higher than the pressure inside the reactor; After the pressure of the oil pump (21) and the pressure of the medium-side flushing liquid are adjusted, the reactor is fed until the internal pressure of the reactor reaches the normal production pressure; After the internal pressure of the reactor reaches the normal production pressure, the pressure of the oil pump (21) is adjusted to the target pressure of the atmospheric side flushing liquid, so that the atmospheric side flushing liquid enters the sealed cavity and forms a liquid film between the sealed atmospheric side dynamic ring (15) and the sealed atmospheric side static ring (16) before returning to the oil tank (20); the pressure of the medium side flushing liquid is adjusted to the target pressure of the medium side flushing liquid, so that the medium side flushing liquid enters the sealed cavity and forms a liquid film between the sealed medium side dynamic ring (13) and the sealed medium side static ring (14); After adjusting the pressure of the oil pump (21) and the pressure of the flushing medium on the atmospheric side to the target pressure, check whether there is leakage at each sealing point; After confirming that there is no leakage at each sealing point, start the stirring motor and start production; After the production is completed, turn off the stirring motor, and after the pressure inside the reactor is relieved and replaced, first stop the flushing of the sealing medium side, then stop the flushing of the sealing atmosphere side, and end the sealing flushing.

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