A self-circulating emission reduction device for oil vapor in storage tanks

Abstract

A self-circulating, emission-reduction device for oil vapor in a storage tank primarily includes a breathing valve, a steam transmission pipe, a steam exhaust pipe, a steam recovery pipe, an absorption oil tank, a gas distribution pipe, an intermediate airbag, a top airbag, a heat pipe, and a fan. The device relies on the condensation and evaporation of the absorbed oil in the absorption oil tank, as well as the expansion and contraction of the airbag, to form a closed, self-circulating breathing system that automatically matches the pressure increase or decrease caused by the breathing of the storage tank. This device requires no human intervention, no external power equipment, and no energy consumption, achieving zero steam emissions. It is a low-carbon, environmentally friendly device with broad prospects for promotion and application.

Description

Technical Field

[0001] The present invention belongs to the field of energy conservation and environmental protection, and specifically relates to a device that automatically discharges and recovers oil and gas from a storage tank through closed self-circulation, thereby reducing oil vapor loss in the storage tank and improving storage safety of the storage tank. Background Art

[0002] Petroleum and its products are a mixture of various hydrocarbons. During oil delivery and collection operations, as well as normal storage, so-called breathing losses occur, accelerating oil evaporation and loss. The evaporation loss of oil and vapor during the flow of oil into and out of finished oil tanks is called "large breathing" loss. This loss occurs when the continuous injection of oil into the tanks causes the pressure in the oil and vapor space within the tanks to rise continuously, causing oil and vapor to escape from the tank top, resulting in evaporation loss. "Small breathing" loss refers to evaporation loss caused by changes in the internal vapor pressure of the tanks during static storage due to environmental factors such as wind speed, temperature, and concentration, leading to gas exchange with the air outside the tank. This evaporation loss increases the gum content, resulting in a decline in oil quality. It also accelerates gasoline oxidation, reducing the oil's octane rating. Currently, three main technical methods for oil and vapor recovery are adsorption, absorption, and condensation.

[0003] The principle of the absorption method is to input the discharged oil vapor into the absorption tower, where the oil vapor is fully contacted with the absorption liquid in the absorption tower, so that most of the hydrocarbon components are dissolved in the absorption liquid. The absorption liquid that dissolves organic hydrocarbons needs to be regenerated or recycled.

[0004] The adsorption method relies on the selective adsorption properties of an adsorbent for organic hydrocarbon components and air in an oil-gas mixture. This allows the organic hydrocarbon components to be adsorbed by the adsorbent. A vacuum system then creates negative pressure, desorbing the hydrocarbon components attached to the adsorbent. These hydrocarbon components are then recovered through subsequent processes. Activated carbon is typically used as the adsorbent, but silica gel and other materials are also acceptable. The recovery unit typically consists of two adsorption tanks filled with adsorbent. While one tank is in the "adsorption" state, the other is "regenerated" by a vacuum pump.

[0005] The condensation method involves cooling the collected oil and gas in multiple stages, causing the hydrocarbon vapor pressure in the oil and gas to reach a supersaturated state and condense into a liquid state, thereby achieving oil and gas recovery. The recovered oil is pressurized by a pump and returned to the storage tank.

[0006] In summary, existing methods for recovering vapor from storage tanks are complex, require extensive equipment, and consume high operating energy. To overcome the shortcomings of the existing technology, the present invention proposes a self-circulating oil vapor emission reduction device for storage tanks. This device automatically receives large amounts of oil vapor generated within the tank. When the vapor pressure within the tank decreases, the previously discharged oil vapor returns to the tank, forming an automatic circulation system completely isolated from the environment. This system completely eliminates evaporation losses without requiring additional energy consumption. Summary of the Invention

[0007] The present invention relates to a self-circulating emission reduction device for oil vapor in a storage tank, which mainly comprises a breathing valve, a steam transmission pipe, a steam discharge pipe, a steam recovery pipe, an oil absorption tank, a gas distribution pipe, an intermediate air bag, a top air bag, a heat pipe, a fan, etc.; the breathing valve is installed on the top of the storage tank, the inlet of the breathing valve is connected to the steam space above the gas-liquid interface of the storage tank, and the outlet of the breathing valve is connected to the inlet of the steam transmission pipe.

[0008] The absorption oil tank is a cylindrical structure, the tank top plate is circular and located in the center of the top of the absorption oil tank. Its diameter is 1 / 3 to 1 / 2 of the diameter of the absorption oil tank. The circumferential side of the tank top plate is connected to the pipe wall of the absorption oil tank through several horizontally arranged support rods. The liquid phase space below the gas-liquid interface of the absorption oil tank is installed with a gas distribution pipe.

[0009] An intermediate airbag is installed on the top of the absorption oil tank, and the number of intermediate airbags is one or more. A top airbag is provided on the top of the intermediate airbag; the intermediate airbag and the top airbag are circular hollow elastic shells, and the central cavity size of the intermediate airbag and the top airbag is exactly the same, and the diameter of the central cavity is approximately 1.05 to 1.1 times the outer diameter of the heat pipe; the ventilation ring size of the intermediate airbag and the top airbag is exactly the same; an overpressure valve and a vacuum valve are installed on the upper part of the bag wall of the top airbag.

[0010] The heat pipe runs through the central cavity of the airbag, and the bottom outlet of the heat pipe passes through the center of the top plate of the absorption oil tank, penetrating into the liquid phase of the absorption oil tank, and the outlet end is sealed. An oil phase heat exchanger is installed on the pipe wall near the heat pipe outlet; a filling cap is installed at the top outlet of the heat pipe, a fan is installed under the filling cap, and an air heat exchanger is installed between the fan and the top airbag.

[0011] The inlet of the steam exhaust pipe is connected to the outlet of the steam transmission pipe, the outlet of the steam exhaust pipe is connected to the inlet of the gas distribution pipe located in the absorption oil tank, and a discharge one-way valve is provided on the steam exhaust pipe; the inlet of the steam recovery pipe is connected to the outlet of the steam transmission pipe, the outlet of the steam recovery pipe is connected to the gas phase space above the liquid level of the absorption oil tank, and a recovery one-way valve is provided on the steam recovery pipe.

[0012] The materials of the middle airbag and the top airbag are both oil and gas corrosion-resistant rubber, which can freely expand and contract and deform; the top and bottom of the middle airbag are both provided with ventilation rings, and the bottom of the top airbag is provided with a ventilation ring. The ventilation ring on the top of the middle airbag and the ventilation ring on the bottom of the top airbag are connected to each other. The steam in the upper space of the oil tank is absorbed through the gap between the tank top support rods and then enters the middle airbag and the top airbag through the ventilation ring.

[0013] A flame arrester is installed on the steam transmission pipe and is located downstream of the breathing valve.

[0014] The absorption oil in the reservoir of the absorption tank is gasoline, kerosene and other low-boiling point light oils that are lighter than the oil components in the tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the composition of the present invention;

[0016] Figure 2 This is a schematic diagram of the oil absorption tank of the present invention;

[0017] Figure 3 Schematic diagram of the intermediate airbag of the present invention;

[0018] Figure 4 A top view of the intermediate airbag of the present invention;

[0019] Figure 5 This is a schematic diagram of the top airbag of the present invention;

[0020] Figure 6 This is a top view of the top airbag of the present invention;

[0021] Figure 7 Schematic diagram of the steam discharge process of the present invention;

[0022] Figure 8 Schematic diagram of the steam recovery process of the present invention.

[0023] 1-Breathing valve; 2-Steam transmission pipe; 3-Steam discharge pipe; 4-Steam recovery pipe; 5-Absorption oil tank; 6-Gas distribution pipe; 7-Middle air bag; 8-Top air bag; 9-Heat pipe; 10-Fan; 11-Storage tank; 12-Tank top plate; 13-Support rod; 14-Ventilation ring; 15-Overpressure valve; 16-Vacuum valve; 17-Oil phase heat exchanger; 18-Filling cap; 19-Air heat exchanger; 20-Discharge check valve; 21-Recovery check valve; 22-Flame arrester; 23-Absorption oil; 24-Center cavity. DETAILED DESCRIPTION

[0024] like Figure 1As shown, the present invention relates to a self-circulating emission reduction device for oil vapor in a storage tank, which mainly includes a breathing valve 1, a steam transmission pipe 2, a steam discharge pipe 3, a steam recovery pipe 4, an absorption oil tank 5, a gas distribution pipe 6, an intermediate air bag 7, a top air bag 8, a heat pipe 9, a fan 10, etc. The breathing valve 1 is installed on the top of the storage tank 11, the inlet of the breathing valve 1 is connected to the steam space above the gas-liquid interface of the storage tank 11, the outlet of the breathing valve 1 is connected to the inlet of the steam transmission pipe 2, a flame arrester 22 is installed on the steam transmission pipe 2, and the flame arrester 22 is located downstream of the breathing valve 1. The absorption oil 23 in the reservoir of the absorption oil tank 5 is a low-boiling-point light oil product such as gasoline and kerosene that is lighter than the components in the storage tank 11.

[0025] The outlet of the steam transmission pipe 2 is connected to the inlet of the steam discharge pipe 3, the outlet of the steam discharge pipe 3 is connected to the inlet of the gas distribution pipe 6 located in the absorption oil tank 5, and the steam discharge pipe 3 is provided with a discharge check valve 20; the inlet of the steam recovery pipe 4 is connected to the outlet of the steam transmission pipe 2, the outlet of the steam recovery pipe 4 is connected to the gas phase space above the liquid level of the absorption oil tank 5, and the steam recovery pipe 4 is provided with a recovery check valve 21.

[0026] The top of the absorption oil tank 5 is equipped with an intermediate airbag 7, the number of which is one or more. A top airbag 8 is provided on the top of the intermediate airbag 7. Ventilation rings 14 are provided on the top and bottom of the intermediate airbag 7, and a ventilating ring 14 is provided on the bottom of the top airbag 8.

[0027] like Figure 2 As shown, the absorption oil tank 5 is a cylindrical structure, the tank top plate 12 is circular, located in the center of the top of the absorption oil tank 5, and its diameter is 1 / 3 to 1 / 2 of the diameter of the absorption oil tank 5. The circumferential side of the tank top plate 12 is connected to the pipe wall of the absorption oil tank 5 through a number of horizontally arranged support rods 13, and the liquid phase space below the gas-liquid interface of the absorption oil tank 5 is installed with a gas distribution pipe 6; the heat pipe 9 runs through the central cavity 24 of the air bag, and the bottom outlet of the heat pipe 9 passes through the center of the tank top plate 12 of the absorption oil tank 5, penetrates into the liquid phase of the absorption oil tank 5, and the outlet end is sealed. An oil phase heat exchanger 17 is installed on the pipe wall near the outlet of the heat pipe 9, and a filling cap 18 is installed at the top outlet of the heat pipe 9. A fan 10 is installed below the filling cap 18, and an air heat exchanger 19 is installed between the fan 10 and the top air bag 8.

[0028] like Figure 3 、 Figure 4 、 Figure 5 、 Figure 6As shown, the intermediate airbag 7 and the top airbag 8 are annular hollow elastic shells, both of which are made of oil and gas corrosion-resistant rubber and can freely expand and contract and deform; the central cavity 24 of the intermediate airbag 7 and the top airbag 8 are exactly the same in size, and the diameter of the central cavity 24 is approximately 1.05 to 1.1 times the outer diameter of the heat pipe 9; the ventilation rings 14 of the intermediate airbag 7 and the top airbag 8 are exactly the same in size; the ventilation ring 14 at the top of the intermediate airbag 7 and the ventilation ring 14 at the bottom of the top airbag 8 are interconnected, and the steam above the gas-liquid interface of the absorption tank 5 passes through the gap between the tank top support rods 13, and then enters the intermediate airbag 7 and the top airbag 8 through the ventilation ring 14.

[0029] The working principle of the present invention is as follows:

[0030] like Figure 7 The figure shows a schematic diagram of the steam discharge process. When the storage tank 11 breathes a lot and causes a large amount of oil vapor to be generated above the liquid level, the oil vapor pressure increases. When the steam pressure exceeds the working positive pressure of the breathing valve 1, the breathing valve 1 automatically opens, and the oil vapor will enter the steam transmission pipe 2 from the storage tank 11. The discharge check valve 20 and the recovery check valve 21 play a control role in the direction of steam flow. When the steam pressure in the storage tank 11 is higher than that in the absorption oil tank 5, the steam flows from the storage tank 11 to the absorption oil tank 5. The discharge check valve 20 automatically opens under the action of the differential pressure, and the recovery check valve 21 automatically closes under the action of the differential pressure. The steam enters the distribution pipe 6 through the steam discharge pipe 3. The distribution pipe 6 is located below the liquid level of the absorption oil 23. A plurality of exhaust holes are installed on the distribution pipe 6, and the direction is toward the bottom of the tank. The function is to evenly distribute the steam into the absorption oil 23 and increase the absorption area. The absorption oil 23 is made of light oil products such as gasoline, kerosene, and naphtha, and its composition is close to that of oil vapor. According to the principle of "like dissolves like," a large amount of oil vapor is absorbed and then stored in the absorption oil 23. A portion of the oil vapor passes through the liquid layer and enters the gas phase space above the absorption tank 5. Then, through the gap around the top plate 12 of the absorption tank 5, it enters the middle airbag 7 through the vent ring 14 and is then transferred to the top airbag 8. As the amount of steam in the airbag gradually increases, the volume of the airbag continues to expand and the pressure gradually increases until it reaches equilibrium with the pressure in the vapor space above the storage tank 11. At this time, the steam discharge process automatically stops. If the pressure in the airbag exceeds the pressure limit of the airbag, the overpressure valve 16 above the top airbag 8 automatically opens to relieve pressure to ensure safety.

[0031] like Figure 8The figure shows a schematic diagram of the steam recovery process. During oil extraction operations or at night, when the temperature in storage tank 11 drops and steam condenses, the steam pressure in storage tank 11 decreases. Because the absorption tank 5 is interconnected with storage tank 11, the absorption tank 5 can quickly sense pressure changes within tank 11. When the pressure in storage tank 11 drops below that of the absorption tank 5, the oil vapor above the liquid level in the absorption tank 5, driven by the differential pressure, flows through the vapor recovery pipe 4 into the vapor transmission pipe 2, and then through the breather valve 1 into storage tank 11, thereby preventing the collapse and failure of storage tank 11 due to excessive pressure. As the vapor from above the absorption tank 5 continues to enter the storage tank 11, the pressure in the absorption tank 5 decreases. Based on the principle of vapor-liquid equilibrium, the low-boiling-point absorbent oil 23 in the absorption tank 5 evaporates faster, generating more oil vapor to compensate for the decrease in steam. Simultaneously, the vapor in the top airbag 8 and the middle airbag 7 also moves downward, ultimately flowing into the vapor recovery pipe 4. As the pressure in the top airbag 8 and the middle airbag 7 gradually decreases, the airbags gradually contract and deform. When the vacuum degree of the gas in the airbag is higher than the safety limit, the vacuum valve 16 located above the top airbag 8 automatically opens, and the outside air enters the airbag and then enters the storage tank 11 through the airbag, preventing the storage tank 11 from being damaged due to excessive vacuum.

[0032] The heat pipe 9 is located in the center of the airbag, and its lower part is fixed to the top of the absorption oil tank 5. It plays a guiding role during the expansion or contraction of the airbag to prevent the airbag from becoming unstable under external forces such as wind loads.

[0033] Heat pipe 9 is a heat transfer element that relies on its internal workings to induce a phase change in liquid to achieve heat transfer. It has efficient thermal conductivity and can be regularly replenished with working fluid through a refill cap 18 at the top of heat pipe 9. An oil-phase heat exchanger 17 is installed at the bottom of heat pipe 9. When hot oil is injected into storage tank 11 or the ambient temperature rises during the day, a large amount of high-temperature steam is generated. Driven by a pressure differential, the high-temperature steam enters absorption tank 5 and enters the oil layer of absorption tank 5 through distribution pipe 6. As a result, the temperature of the absorbed oil 23 rises rapidly. The heat is transferred to heat pipe 9 through oil-phase heat exchanger 17, and heat pipe 9 quickly transfers the heat to air heat exchanger 19 located at the top. A fan 10 is installed on top of air heat exchanger 19. When there is wind, fan 10 rotates and blows air downward, enhancing convective heat exchange between air heat exchanger 19 and the environment, thereby lowering the temperature of the steam in absorption tank 5 and the airbag, slowing the rate of steam generation, and thus reducing the airbag expansion load.

[0034] However, when the pressure in storage tank 11 is low, the vapor from absorption tank 5 will flow back into storage tank 11, reducing the pressure within absorption tank 5. Absorption oil 23 is a lightweight, low-boiling oil, and the reduced pressure promotes its evaporation. As evaporation absorbs heat, the temperature of absorption oil 23 gradually decreases. At this point, the air heat exchanger 19 above heat pipe 9 transfers ambient heat through the heat pipe 9 to the oil-phase heat exchanger 17 in absorption tank 5, thereby maintaining a constant temperature for absorption oil 23. This allows absorption oil 23 to generate sufficient steam in a timely manner to compensate for the pressure drop in storage tank 11 caused by insufficient steam.

[0035] In practice, the number of intermediate airbags 7 can be adjusted as needed. Furthermore, a single absorption tank 5 can be connected to multiple storage tanks 11, thereby forming a large oil and vapor recovery network. In this way, vapor from any tank can enter the absorption tank 5, the airbags, and other connected tanks, thereby improving overall vapor balance control.

[0036] Compared to traditional vapor recovery technology, the present invention relies on the condensation and evaporation of the absorbent oil 23 in the absorbent tank 5, as well as the expansion and contraction of the airbag, to form a closed, self-circulating breathing system. During normal operation, there is no vapor loss, and outside air does not enter the storage tank 11, thus preventing the formation of flammable and explosive gas mixtures, thereby improving safety. Furthermore, the condensation and evaporation of the absorbent oil 23 in the absorbent tank 5, as well as the expansion and contraction of the airbag, are completely autonomous, relying on pressure changes within the storage tank 11. Operation requires no human intervention, external power equipment, or energy consumption, resulting in energy conservation and environmental protection.

Claims

1. A self-circulating emission reduction device for oil vapor in a storage tank, characterized in that: Mainly includes: breathing valve (1), a steam transmission pipe (2), a steam discharge pipe (3), a steam recovery pipe (4), an absorption oil tank (5), a gas distribution pipe (6), an intermediate air bag (7), a top air bag (8), a heat pipe (9), and a fan (10); the breathing valve (1) is installed on the top of the storage tank (11), the inlet of the breathing valve (1) is connected to the steam space above the gas-liquid interface of the storage tank (11), and the outlet of the breathing valve (1) is connected to the inlet of the steam transmission pipe (2); The absorption oil tank (5) is a cylindrical structure. The tank top plate (12) is circular and located at the center of the top of the absorption oil tank (5). Its diameter is 1 / 3 to 1 / 2 of the diameter of the absorption oil tank (5). The circumference of the tank top plate (12) is connected to the tank wall of the absorption oil tank (5) through a plurality of horizontally arranged support rods (13). A gas distribution pipe (6) is installed in the liquid phase space below the gas-liquid interface of the absorption oil tank (5). An intermediate airbag (7) is installed on the top of the absorption oil tank (5), and the number of the intermediate airbags (7) is one or more. A top airbag (8) is installed on the top of the intermediate airbag (7); the intermediate airbag (7) and the top airbag (8) are circular hollow elastic shells, and the central cavity (24) of the intermediate airbag (7) and the top airbag (8) are exactly the same in size, and the diameter of the central cavity (24) is 1.05 to 1.1 times the outer diameter of the heat pipe (9); the ventilation rings (14) of the intermediate airbag (7) and the top airbag (9) are exactly the same in size; an overpressure valve (15) and a vacuum valve (16) are installed on the upper part of the wall of the top airbag (8); The heat pipe (9) passes through the central cavity (24) of the airbag, and the bottom outlet of the heat pipe (9) passes through the center of the tank top plate (12) of the absorption oil tank (5) and penetrates into the liquid phase of the absorption oil tank (5). The outlet end is sealed, and an oil phase heat exchanger (17) is installed on the pipe wall near the outlet of the heat pipe (9); a filling cap (18) is installed at the top outlet of the heat pipe (9), a fan (10) is installed below the filling cap (18), and an air heat exchanger (19) is installed between the fan (10) and the top airbag (8); The inlet of the steam discharge pipe (3) is connected to the outlet of the steam transmission pipe (2), and the outlet of the steam discharge pipe (3) is connected to the inlet of the gas distribution pipe (6) located in the absorption oil tank (5). The steam discharge pipe (3) is provided with a discharge check valve (20); the inlet of the steam recovery pipe (4) is connected to the outlet of the steam transmission pipe (2), and the outlet of the steam recovery pipe (4) is connected to the gas phase space above the liquid level of the absorption oil tank (5). The steam recovery pipe (4) is provided with a recovery check valve (21).

2. The oil vapor self-circulation emission reduction device for a storage tank according to claim 1, characterized in that: The materials of the intermediate airbag (7) and the top airbag (8) are both oil-gas corrosion-resistant rubber and can be freely expanded and deformed; the top and bottom of the intermediate airbag (7) are both provided with a ventilation ring (14), and the bottom of the top airbag (8) is provided with a ventilation ring (14). The ventilation ring (14) on the top of the intermediate airbag (7) and the ventilation ring (14) on the bottom of the top airbag (8) are interconnected, and the steam above the gas-liquid interface of the absorption tank (5) passes through the gap between the tank top support rods (13) and enters the intermediate airbag (7) and the top airbag (8) through the ventilation ring (14).

3. The oil vapor self-circulation emission reduction device for a storage tank according to claim 1, characterized in that: A flame arrester (22) is installed on the steam transmission pipe (2), and the flame arrester (22) is located downstream of the breathing valve (1).

4. The device for reducing oil vapor self-circulation in a storage tank according to claim 1, characterized in that: The absorption oil (23) in the reservoir of the absorption oil tank (5) is a low-boiling-point light oil product that is lighter than the oil component in the storage tank (11).

Images