Online real-time intelligent management system for floating roof storage tank

Abstract

The invention discloses an online real-time intelligent management system for a floating roof storage tank. Comprising a data acquisition module, a floating disc inclination angle measurement module, an energy conservation calculation module, a floating disc mass m change correction function module, a floating roof drainage monitoring module, a friction dynamic change module and a floating roof storage tank sealing oil gas space flash explosion prevention and monitoring function module. Parameter data are obtained through analysis and calculation of all functional modules, correlation is estimated through a self-learning function and intelligent optimization, potential safety hazards of oil gas leakage and detonation of the external floating roof are overcome through optimization control, meanwhile, the service life of the storage tank is prolonged, and the storage efficiency of the storage tank is improved; in addition, the inclination of the floating disc is measured by adopting a three-point positioning equilateral triangle measurement algorithm on the top of the floating disc, the detection precision is high, the floating disc is ensured to ascend and descend stably, and safe operation of the storage tank is also ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of floating roof storage tanks, and specifically to an on-line real-time intelligent management system for floating roof storage tanks. Background Art

[0002] With the rapid development of China's economy and the continuous progress of science and technology, the demand for various oil products including crude oil is increasing continuously. The larger the single-tank volume, the smaller the tank construction cost and the less the investment. The number of large domestic oil tanks is increasing continuously. At present, the 150,000 cubic meter capacity of external floating roof storage tanks for crude oil has been widely promoted. The increase in the oil tank capacity reduces the floor area. The large scale is convenient for centralized management, which is beneficial to intelligent management to reduce breathing loss. The optimization control of the energy conservation of the floating disc operation is more important. The inclination of the large floating disc, the anti-leakage of the sealed cabin, the primary and secondary seals, and the explosion prevention and display of combustible gases are more important. With the application and promotion of high-strength steel, the consumption of steel plates is saved, and funds are also saved. However, the overall weight of the storage tank is reduced, which increases the inertia during the operation of large-scale storage tanks, resulting in large kinetic energy for rising and falling and large changes in friction force. This causes poor stability of the oil tank. The increase in the volume of the oil tank leads to a large space inside the floating roof storage tank, and the increase in the cumulative amount of combustible gas increases the harmfulness of the potential safety hazards. To overcome these problems, it is necessary to conduct on-line real-time intelligent digital management of external floating roof and internal floating roof storage tanks. Summary of the Invention

[0003] To solve the defects existing in the prior art, the present invention provides an on-line real-time intelligent management system for floating roof storage tanks.

[0004] To solve the above technical problems, the present invention provides the following technical solutions:

[0005] An on-line real-time intelligent management system for floating roof storage tanks of the present invention includes a data acquisition module, a floating disc inclination angle measurement module, an energy conservation calculation module, a correction function module for the change of the floating disc mass m, a floating roof drainage monitoring module, a dynamic friction force change module, and a prevention and monitoring function module for flash explosion of the sealed oil and gas space of the floating roof storage tank;

[0006] The data acquisition module is used to collect all technical parameter data in the storage tank area; the floating disc inclination angle measurement module is used to measure the inclination angle of the floating disc; the energy conservation calculation module is used to calculate the kinetic energy in the floating and sinking states, the correction function module for the change of the floating disc mass m is used to implement correction of the floating disc mass m, the floating roof drainage monitoring module is used to monitor the rainwater accumulation and drainage state of the floating roof, the dynamic friction force change module is used to calculate the dynamic change of the friction force, and the prevention and monitoring function module for flash explosion of the sealed oil and gas space of the floating roof storage tank conducts prevention and monitoring of flash explosion of the oil and gas space;

[0007] The measurement method of the floating disc tilt angle measurement module is as follows: at the top of the floating disc, an equilateral triangle with three-point positioning is used. The distances from the three points A, B, and C to the edge of the floating disc are all 1.5 m. An internal floating drum liquid level transmitter or radar level gauge for measuring the crude oil liquid level is installed at each of the three points A, B, and C. The bottoms of the three internal floating roof level gauges or radar level gauges are consistent with the bottom edge of the floating disc and are at the same horizontal plane as the oil surface. Subsequently, a coordinate system is set, and then there are A(0,0), B(L,0), and C where L is the side length of the equilateral triangle;

[0008] Then there is the plane equation of the depth of the floating disc immersed in the liquid oil: Z = pX + qY + r; where z is the height in the slope formula, p is the coefficient of the X-axis, q is the coefficient of the Y-axis, ha is the oil immersion depth at point A, hb is the oil immersion at point B, and hc is the oil immersion at point C;

[0009] Then the inclination angle of the floating disc

[0010] 4. As a preferred technical solution of the present invention, the working method of the energy conservation calculation module is as follows: First, an energy conservation relationship is established, and there is a formula Wli = ΔKE + ΔPE + Wfr, where Wli is the work done by the liquid on the floating disc, and Wfr is the work done by the frictional force,

[0011] ΔPE is the gravitational potential energy generated by the height change of the floating disc, and the formula is; ΔPE = mgh, where h is the lifting height of the floating disc and g is the acceleration due to gravity;

[0012] ΔKE is the energy of the floating disc during movement, and the formula is: KE = 1 / 2mv 2 , where m is the mass of the floating disc and v is the instantaneous velocity;

[0013] Wfr is the work done by the frictional force between the annular seal of the floating disc and the tank wall, and the formula is Wfr = fh, where f is the frictional force and the direction is always opposite to the direction of movement;

[0014] During the rising process of the floating disc: The liquid pushes the floating disc to rise through buoyancy, and the buoyancy does work Wli = B·h, where: B is the buoyancy B = ρ·v·g, which is related to the volume of the liquid displaced by the floating disc;

[0015] Then there is: B·h = 1 / 2mv 2 + mgh + f·h,

[0016] When rising at a constant speed, then v is a constant speed value, ΔKE = 0, and B = mg + f. The buoyancy needs to overcome the gravity and frictional force of the floating disc;

[0017] During the descending process of the floating disc: The gravitational potential energy of the floating disc decreases, and ΔPE = -mgh;

[0018] Then there is 1 / 2mv 2= mgh - f·h, where v is the rising or falling speed of the floating roof.

[0019] When descending at a constant speed (ΔKE = 0): mg = f, and the gravitational potential energy is completely used to overcome friction.

[0020] As a preferred technical solution of the present invention, the working method of the functional module for correcting the change in the mass m of the floating roof is that for the mass m correction formula:

[0021] When the floating roof is working properly, the buoyancy B of the floating roof in the static state, then the mass m of the floating roof = B, where m is the mass of the floating roof top, and the value of m is calculated through the buoyancy B = ρ·v, and the m in the database is corrected;

[0022] When water accumulates on the tank top or water enters the density cabin of the floating roof;

[0023] Among them, water accumulation on the tank top or leakage of the sealing cabin will increase the weight m of the floating roof, and the change in the weight of the floating roof causes a change in the oil immersion depth h of the floating roof. By obtaining the measured value of the oil immersion depth h, the average value of ha, hb, and hc at points A, B, and C, where V = h·s, where V is the oil immersion volume M of the floating roof 3 , h is the oil immersion depth of the floating roof, s is the lower top area M of the floating roof 2 ,, then the calculation formula for the mass m of the floating roof: m = ρ·s·h, where ρ is the density of the oil product, and the m in the database will be corrected using the calculated mass m of the floating roof.

[0024] As a preferred technical solution of the present invention, the working method of the floating roof drainage monitoring module is to install floating roof water accumulation ultrasonic level transmitters H-01, H-02, and H-03 beside the equilateral triangle A, B, and C at the top of the floating roof to measure the inclination, monitor the floating roof top water accumulation data, install a drainage flow transmitter F1-04 on the pipeline at the bottom drainage outlet of the storage tank and monitor the oil content in the drain pipe water, the blockage situation in the drain pipe, and the surging situation of the drainage hose in the storage tank.

[0025] Design and establish an average height Hs of the external floating roof water accumulation with a maximum water accumulation of 250mm, and obtain: Ks = Hs\250. In the above formula: Ks is the external floating roof water accumulation change coefficient, and Hs is the average height of the external floating roof water accumulation; Ks less than 1 meets the standard, and Ks greater than 1 exceeds the standard;

[0026] Establish an external floating roof bottom drainage flow Fs, and obtain: Fs = F04\F0,

[0027] In the above formula, Fs is the external floating roof drainage flow coefficient, F0 is the bottom drainage flow when the external floating roof water accumulation is 250mm, which can be obtained through simulation calculation, and F04 is the instantaneous flow at the bottom of the external floating roof;

[0028] The state of the external floating roof drainage system can be analyzed through Ks and Fs, and the drainage efficiency of the system can be estimated by analyzing Ks, Fs, climate, and rainfall data.

[0029] As a preferred technical solution of the present invention, the working method of the friction force dynamic change module is that if the friction force is too large or changes, it will cause the floating disc to get stuck. Then, by observing the changes in the buoyancy B of the floating disc rising, stopping, and falling, the dynamic change of the friction force can be obtained.

[0030] As a preferred technical solution of the present invention, the working method of the flash explosion prevention and monitoring function module for the sealed oil and gas space of the floating roof storage tank is to detect the concentration and pressure of combustible gas in the sealed oil and gas space. When the concentration in the sealed oil and gas space reaches the warning value, nitrogen is injected to inert the combustible gas.

[0031] The beneficial effects of the present invention are as follows:

[0032] This kind of online real-time intelligent management system for floating roof storage tanks obtains parameter data through the analysis and calculation of each functional module, and through the self-learning function and intelligent optimization, it can predict and optimize the control to overcome the potential safety hazards of oil and gas leakage and explosion of the external floating roof, while extending the service life of the storage tank and improving the storage efficiency of the storage tank; in addition, for the measurement of the inclination of the floating disc in the present invention, at the top of the floating disc, three points A, B, and C of an equilateral triangle for three-point positioning are uniformly 1.5 m away from the edge of the floating disc. The floating disc is equivalent to the circumcircle of the equilateral triangle, and its center of gravity is consistent. Special internal floating drum liquid level transmitters or radar level gauges for measuring the crude oil liquid level are installed at points A, B, and C. The bottoms of the three internal floating roof level gauges are consistent with the bottom edge of the floating disc and are at the same horizontal plane as the oil product liquid surface. The measured liquid level value on the floating disc surface is equal to the oil immersion depth h of the floating disc, and its measurement accuracy reaches 0.2 level, so it has a high detection accuracy. Description of the Drawings

[0033] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention.

[0034] In the drawings:

[0035] Figure 1 is a schematic structural diagram of an online real-time intelligent management system for a floating roof storage tank of the present invention;

[0036] Figure 2 is an installation schematic diagram of the floating disc of an online real-time intelligent management system for a floating roof storage tank of the present invention;

[0037] Figure 3 is a sampling diagram of A, B, and C of an online real-time intelligent management system for a floating roof storage tank of the present invention;

[0038] Figure 4 It is a schematic diagram of the installation of the internal floating drum liquid level transmitter or radar liquid level gauge of an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0039] Figure 5 It is a control schematic diagram of an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0040] Figure 6 It is a schematic diagram of the nitrogen injection pipe of an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0041] Figure 7 It is a schematic diagram of the change in kinetic energy of the floating roof during movement in an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0042] Figure 8 It is a schematic diagram of the change in work done by friction during movement in an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0043] Figure 9 It is a schematic diagram of the change in potential energy of the floating roof during movement in an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0044] Figure 10 It is a schematic diagram of the change in buoyancy B of the floating roof during movement in an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0045] Figure 11 It is a schematic diagram of the change in concentration of combustible gas during movement in an on-line real-time intelligent management system for floating roof storage tanks of the present invention;

[0046] Figure 12 It is a schematic diagram of the detection point of the concentration of combustible gas during movement in an on-line real-time intelligent management system for floating roof storage tanks of the present invention.

[0047] In the figure: 1. Data acquisition module; 2. Floating roof tilt angle measurement module; 3. Energy conservation calculation module; 4. Correction function module for the change in the mass m of the floating roof; 5. Floating roof drainage monitoring module; 6. Friction force dynamic change module; 7. Function module for preventing and monitoring flash explosion in the sealed oil and gas space of the floating roof storage tank; 8. Tank body; 9. Floating roof; 10. Sealing ring; 11. Drainage device; 12. Internal floating drum liquid level transmitter; 13. Ultrasonic liquid level transmitter; 14. Nitrogen injection pipe. Specific implementation mode

[0048] The following is a description of the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0049] Embodiment: As Figures 1 - 12As shown in the figure, an online real-time intelligent management system for a floating roof storage tank of the present invention conducts two-way communication and mutual data acquisition with the DCS control system in the tank area through the 0PC communication port, and can collect the required control and measurement parameters from the DCS computer control system in the tank area. At the same time, the optimized parameter data generated by the intelligent system TIMS of the present invention enters the DCS system through the OPC interface and can be displayed on the human-machine interface of the DCS. It includes processes, curves, change rates, tables, and PID control of various control valves of the storage tank. Various calculation function modules and the measurement instruments and probe signals they require. For example, the transmitter signals of the depths ha, hb, and hc of the oil-immersed liquid levels at the three vertices of the equilateral triangle of the floating roof, as well as the newly installed pressure transmitter, nitrogen control valve, drain control valve, flowmeter, and other newly installed probe and control valve signals of the nitrogen sealing device inside the floating roof top sealing ring all enter the DCS system from the site and then enter the database of the online real-time intelligent management system of the storage tank of the present invention through the OPC interface.

[0050] This system includes a data acquisition module 1, a floating disc tilt angle measurement module 2, an energy conservation calculation module 3, a correction function module 4 for the change in the mass m of the floating disc, a floating roof drainage monitoring module 5, a dynamic friction change module 6, and a flash explosion prevention and monitoring function module 7 for the sealed oil and gas space of the floating roof storage tank;

[0051] The data acquisition module 1 is used to collect all technical parameter data in the storage tank area; the data acquisition module 1 collects a large amount of data generated by the algorithms of each function module during the operation of various storage tanks. For example: the real-time height, speed, kinetic energy, potential energy, buoyancy, weight of the floating disc, oil immersion depth, tilt angle of the floating disc, friction between the floating disc and the tank wall, concentration of combustible gas alarm devices at each distribution point on the floating roof top, change rate of combustible gas concentration, data of the floating roof top and accumulated water, drainage data, and a series of data for inerting nitrogen and oil and gas. These data are composed of the databases of the storage tanks in the entire tank area and form a big data chain of storage tanks for processing.

[0052] The floating disc tilt angle measurement module 2 is used to measure the tilt angle of the floating disc; the energy conservation calculation module 3 is used to calculate the kinetic energy in the floating-up and floating-down states, the correction function module 4 for the change in the mass m of the floating disc is used to implement correction of the mass m of the floating disc, the floating roof drainage monitoring module is used to monitor the rainwater accumulation and drainage status of the floating roof, the dynamic friction change module 6 is used to calculate the dynamic change of friction, and the flash explosion prevention and monitoring function module 7 for the sealed oil and gas space of the floating roof storage tank conducts flash explosion prevention and monitoring of the oil and gas space. The sealed oil and gas space refers to the space where the floating disc touches the bottom;

[0053] In the anti-wind design of floating roof storage tanks, to ensure that the section modulus of the anti-wind ring meets the wind speed conditions and an anchoring device needs to be set when the tipping height-diameter ratio or tipping moment of the storage tank exceeds the critical value, the inclination of the floating roof is set at about 0.5°. Therefore, during the operation of the oil tank, the inclination of the floating roof is set between 0° and 1°. So, the change in the inclination of the floating roof is very important for the safety of the stable operation of the storage tank. The change in the inclination of the floating roof causes the inclination and accumulation of water on the top of the floating roof, resulting in uneven unilateral force on the floating roof, large changes in the friction force between the floating roof and the tank wall, damage to the primary and secondary seals of the floating roof, and also causing jamming during the operation of the floating roof. Therefore, for the measurement and calculation of the inclination of the floating roof, etc., controlling the inclination within the range of 0° to 1° during the operation of the floating roof is an important factor to ensure the smooth rise and fall of the floating roof and also an important factor to ensure the safe operation of the storage tank.

[0054] Currently, several existing technologies for measuring the inclination of the floating roof have many defects. The main reasons are as follows: The top of the floating roof is welded by many roof plates about 5 mm thick, with inaccurate flatness and irregular inclination. Also, due to climate change, thermal expansion and contraction, etc., the horizontal plane at the top is inaccurate, especially the measurement within the range of 0° to 1° cannot be satisfied.

[0055] Among them, the measurement method of the floating roof inclination angle measurement module 2 in the present invention is as follows: On the top of the floating roof, an equilateral triangle with three-point positioning is adopted. The three points A, B, and C are uniformly 1.5 m away from the edge of the floating roof. An internal floating drum liquid level transmitter or radar liquid level gauge for measuring the crude oil liquid level is installed at each of the three points A, B, and C. The bottoms of the three internal floating roof liquid level gauges or radar liquid level gauges are flush with the bottom edge of the floating roof and at the same horizontal plane as the oil product liquid surface. Subsequently, a coordinate system is set, and then there are A(0,0), B(L,0), and where L is the side length of the equilateral triangle;

[0056] Then there is the plane equation of the depth of the floating roof immersed in the liquid oil: Z = pX + qY + r; where z is the height in the slope formula, p is the coefficient of the X-axis, q is the coefficient of the Y-axis, ha is the oil immersion depth at point A, hb is the oil immersion at point B, and hc is the oil immersion at point C;

[0057] Then the inclination angle of the floating roof

[0058] Among them, for the calculation of the friction force between the floating roof and the tank body, the sealing system between the tank body and the floating roof consists of a primary and secondary sealing mechanism with a nitrile rubber elastic sealing ring. The friction force calculation is F = N·μ, where F is the friction force, which is the normal pressure of the elastic element of the floating roof and the pressing plate on the tank wall, and μ is the friction coefficient.

[0059] After multiple experimental measurements: The friction coefficient of the nitrile rubber elastic sealing ring of a storage tank with a volume of 20,000 cubic meters and a diameter of 40 meters is between 0.1 and 0.4. The normal elastic force of the primary seal is 12 N / cm², and the normal elastic force of the secondary seal is 25 N / cm².

[0060] Let the friction force of the primary seal be F1, the sealing area be S1, and the width of the nitrile rubber elastic sealing ring be 38 cm.

[0061] Then F1 = N1 * S1 * μ, and substituting the values gives F01 = 116.9 tons.

[0062] Let the friction force of the secondary seal be F2, the sealing area be S2, and the width of the nitrile rubber elastic sealing ring be 10 cm. Then F2 = NO2 * S2 * μ, and substituting the values gives F2 = 64.8 tons; then the friction force F = F1 + F2 = 180.98 tons.

[0063] In this way, based on the tilt angle of the floating roof and the change in the friction force between the floating roof and the tank body, combined with the buoyancy received by the floating roof, the sealing state of the sealing ring and the leakage situation of the floating roof sealing cabin can be analyzed.

[0064] As one of the embodiments, where L = 40000 mm, ha = 400 mm, hb = 100 m, hc = 180 mm. Then substituting the data into the above formula gives θ = 0.273°;

[0065] If the obtained data is changed to L = 40000, ha = 50 mm, hb = 30 m,

[0066] Then substituting the data into the above formula gives θ ≈ 0.52°. From the above calculation results, it can be seen that the calculation accuracy of the oil immersion depth method through the three vertices of an equilateral triangle in the present invention can fully meet the monitoring of the floating roof operation process, ensure that the tilt angle of the floating roof is within the safe range of 0.5°, and control the tilt of the floating roof through the wind resistance ring, tank wall thickness, and anchoring design, fully meeting the design requirements.

[0067] Among them, the unevenness of the storage tank foundation is the main reason for the tilt of the floating roof. In this way, the tilt angle of the floating roof can be monitored online in real time based on data analysis, so that the main reason for the tilt caused by the uneven foundation can be found, which is convenient for subsequent rectification and prolongs the service life of the storage tank. And the change in the tilt degree of the floating roof, combined with the correlation between the friction of the tank body and the primary and secondary seals, can analyze and determine the sealing state. And find the cause of jamming and optimize and intelligent control.

[0068] Among them, the working method of the energy conservation calculation module 3 is to first establish an energy conservation relationship. There is a formula Wli = ΔKE + ΔPE + Wfr, where Wli is the work done by the liquid on the floating roof, Wfr is the work done by friction, and ΔPE is the gravitational potential energy generated by the floating roof due to height change. The formula is: ΔPE = mgh, where h is the lifting height of the floating roof and g is the acceleration due to gravity.

[0069] ΔKE is the energy of the floating roof during movement. The formula is: KE = 1 / 2mv 2 , where m is the mass of the floating roof and v is the instantaneous velocity; Wfr is the work done by the friction between the annular seal of the floating roof and the tank wall. The formula is Wfr = fh, where f is the friction force, and its direction is always opposite to the direction of movement;

[0070] During the rising process of the floating roof: The liquid pushes the floating roof to rise through buoyancy. The work done by buoyancy is Wli = B·h, where: B is the buoyancy force, B = ρ·v·g, which is related to the volume of the liquid displaced by the floating roof;

[0071] Then there is: B·h = 1 / 2mv 2 + mgh + f·h,

[0072] When rising at a constant speed, v is a constant speed value, ΔKE = 0, and B = mg + f. The buoyancy force needs to overcome the gravity and friction of the floating roof;

[0073] Among them, during the stage of the floating roof of the floating roof tank rising and oil inlet, the inlet oil pump is started, the inlet oil control valve FV01 is opened, the oil product enters the storage tank, the liquid level rises, the immersion depth of the floating roof in the oil increases, the buoyancy force of the floating roof increases, the floating roof is lifted, the oil product flow rate increases, the liquid level in the storage tank increases, and the acceleration of the floating roof rises. If the oil inlet volume is at a constant value, then the floating roof moves at a constant speed. When the floating roof is rising, the height of the floating roof increases and the potential energy increases.

[0074] During the stage when the floating roof of the floating roof tank is in a static state, when the storage volume of the oil product entering the storage tank reaches the requirement and the oil inlet process is completed, the inlet oil control valve is closed, the liquid level is constant, and the floating roof is supported by the buoyancy force B generated by the immersion level of the floating roof in the oil. The buoyancy force: B = ρ·v·g, where: ρ is the density of the oil product, v is the volume of the oil product displaced by the floating roof, and g is the acceleration.

[0075] During the descending process of the floating roof: The gravitational potential energy of the floating roof decreases, ΔPE = -mgh;

[0076] Then there is 1 / 2mv 2 = mgh - f·h, where v is the rising or falling speed of the floating roof,

[0077] When descending at a constant speed (ΔKE = 0): mg = f. The gravitational potential energy is completely used to overcome friction. This is the stage when the floating roof of the floating storage tank descends (oil is discharged). The oil discharge pump starts, and the oil discharge flow control valve FV02 is opened. The oil is output from the storage tank. The output of the oil causes the liquid level in the storage tank to drop, reducing the oil immersion depth of the floating roof, decreasing the buoyancy, and causing the floating roof to descend. At this time, the potential energy of the floating roof decreases, and the descent of the floating roof is provided by the potential energy of the floating roof. At this time, the potential energy mainly overcomes the work done by the friction force on the annular sealing surface of the floating roof during the descent. Friction forces are generated during both the descent and ascent of the floating roof, and the direction of the friction force is opposite to the directions of ascent and descent.

[0078] Conduct a balance state analysis. During the stable operation of the floating roof, the floating roof usually moves at a constant speed. At this time, the change in kinetic energy is 0. At this time:

[0079] Ascending balance: Buoyancy B = mg + f, and additional energy needs to be continuously applied to offset the friction force.

[0080] Descending balance: Gravity mg = f, and the friction force completely balances the weight of the floating roof.

[0081] Among them, from the analysis, calculation of kinetic energy, change in potential energy, and calculation of buoyancy, all involve the mass m of the floating roof. If the change in the mass of the floating roof has a great impact on its calculation results, it is necessary to correct the change in the mass m of the floating roof. The working method of the function module 4 for correcting the change in the mass m of the floating roof is that the correction formula for the mass m is:

[0082] When the floating roof is working normally, when the buoyancy B of the floating roof is in the static state, then the mass m of the floating roof = B, where m is the mass of the floating roof. The value of m is calculated through the buoyancy B = ρ·v, and m in the database is corrected.

[0083] Based on a 20,000 - cubic - meter storage tank. The diameter of the floating roof is 40000 mm, the liquid density ρ = 1, and the average oil immersion depth is 0.15 m. Then

[0084] The bottom area of the storage tank is 1256 square meters, and the buoyancy B = ρ·v = 188.4 tons.

[0085] When there is water accumulation on the tank top or water enters the density compartment of the floating roof;

[0086] Among them, water accumulation on the tank top or leakage of the sealing compartment will both increase the weight m of the floating roof, and the change in the weight of the floating roof causes a change in the oil immersion depth h of the floating roof. By obtaining the measured value of the oil immersion depth h, the average value of ha, hb, and hc at points A, B, and C. Among them, V = h·s, where V is the oil immersion volume of the floating roof M 3 , h is the oil immersion depth of the floating roof, and s is the lower top area of the floating roof M 2, then the formula for calculating the mass m of the floating roof is: m = ρ·s·h, where ρ is the density of the oil product, and the mass m in the database obtained by calculation will be used to correct the m of the floating roof.

[0087] Among them, the floating roof has a floating roof drainage device. When it rains, the rainwater on the floating roof is collected into the pool trough at the top center through the floating roof drainage trough. The central catchment trough at the top discharges into the oil-containing sewage treatment system of the tank farm through a drainage hose with a check valve and a drainage cut-off valve at the bottom outlet of the tank. Once the drainage system is blocked during the drainage process of the oil tank, causing water accumulation on the floating roof, under the influence of the unilateral inclination of the floating roof, unilateral water accumulation occurs and the instability of the floating roof rising and falling is increased, which poses a hidden danger to the safe operation of the floating roof. At the same time, leakage of the drainage hose will cause the oil product in the storage tank to drain with the water.

[0088] The working method of the floating roof drainage monitoring module 5 is to install floating roof water accumulation ultrasonic level transmitters H-01, H-02, and H-03 beside the equilateral triangles A, B, and C at the top of the floating roof to measure the inclination, and monitor the floating roof water accumulation data. Install a drainage flow transmitter F1-04 and the oil content of the water in the drainage pipe on the pipeline at the drainage outlet at the bottom of the storage tank to monitor the blockage situation in the drainage pipe and the leakage of the drainage hose in the storage tank.

[0089] Design and establish an average height Hs of the external floating roof water accumulation with a maximum water accumulation of 250mm.

[0090] It can be obtained that: Ks = Hs\250. In the above formula: Ks is the external floating roof water accumulation change coefficient, and Hs is the average height of the external floating roof water accumulation; when Ks is less than 1, it meets the standard, and when Ks is greater than 1, it exceeds the standard.

[0091] Establish an external floating roof bottom drainage flow Fs, and it can be obtained that: Fs = F04\F0.

[0092] In the above formula, Fs is the external floating roof drainage flow coefficient, F0 is the bottom drainage flow when the external floating roof water accumulation is 250mm, which can be obtained through simulation calculation, and F04 is the instantaneous flow at the bottom of the external floating roof.

[0093] Through Ks and Fs, the state of the external floating roof drainage system can be analyzed. By analyzing Ks, Fs, climate, and rainfall data, the drainage efficiency of the system can be estimated, and preparations for the rainy season and typhoon season can be made. Then there is As = A20\A0, where As is the oil content coefficient in the external floating roof top drainage; A20 is the instantaneous oil content concentration in the external floating roof top drainage; A0 is the oil content concentration of the oil-containing sewage released by the local environmental protection department.

[0094] Analysis: For As: when As is equal to 1, the drainage oil content concentration is in a critical state; when As is less than 1, it meets the standard; when As is greater than 1, there is a small amount of oil leakage phenomenon and the external floating roof seal is aging; when As is greater than 2, the external floating roof drainage hose may be leaking.

[0095] Among them, the working method of the friction force dynamic change module 6 is that if the friction force is too large or there are changes, it will cause the floating roof to get stuck. Then, by obtaining the changes in the buoyancy B of the floating roof rising, stopping, and falling, the dynamic change of the friction force can be obtained. The work done by the friction force is related to the floating roof sealing material, the roughness of the tank wall, and the lubrication state. The vertical (normal) force f between it and the tank wall is the elastic force of the elastic elements of the primary and secondary seals. The elastic force is obtained through on-site measurement, from the manufacturer of the elastic elements, or from an engineering manual, and is basically constant. The friction coefficient μ can also be obtained from the manufacturer or an engineering manual. Through the changes in the friction force and the work done by the friction force, these changes can be obtained through Figures 6 - 10 It can be seen from the graphs of the operating curves and change rates of the kinetic energy, potential energy, and friction force of the storage tank.

[0096] If the friction force is too large or there are changes, it will cause the floating roof to get stuck. From the dynamic curve, factors such as damage and aging of the primary and secondary sealing materials can be judged. All of these can be obtained from Figures 6 - 10 the graph. These factors can be realized by establishing a functional module for the dynamic change curve of the friction force.

[0097] The working method of the function module for preventing and monitoring flash explosion of the oil and gas space in the floating roof storage tank is to detect the concentration and pressure of combustible gas in the sealed oil and gas space. When the concentration in the sealed oil and gas space reaches the warning value, nitrogen injection is carried out to inert the combustible gas.

[0098] According to records, among 107 cases of fires in various storage tanks, 65 cases were caused by the ignition of the mixture of combustible gas and air between the primary and secondary seals of the external floating roof by lightning, accounting for 61% of the accidents.

[0099] There are two types of reasons for these fires in external floating roof storage tanks:

[0100] Due to the damage and aging of the seals between the primary and secondary seals, and the large gap between the seals and the tank wall, the combustible gas with excessive concentration in the annular space of the external floating roof seal becomes an important ignition source for triggering the fire of the storage tank by lightning, static electricity, sparks, etc.

[0101] When major repairs are carried out on the external floating roof storage tank or when business operations such as entering and leaving the storage tank are required, it is required that the floating roof sinks to the bottom. When the floating roof has not risen and the liquid level is lower than the floating roof support, there is a mixture of combustible gas and air in the space below the floating roof. Air enters from within the annular seal. At this time, if it is required to fill the oil, it will force the combustible gas to pass through the floating roof seal layer and enter the air above the external floating roof. At this time, the maximum pressure in the oil and gas space below the floating roof can reach 9.75 kPa, and the explosion limit of the mixed oil and gas reaches 19.04% within 0.5 hours. The lower explosion limit of the combustible gas generated by crude oil is 1.4% - 2.1%. It can be seen that the concentration of the combustible gas volatilized from crude oil has far exceeded the explosion concentration.

[0102] The concentration of the combustible gas reaches the flash point, and the oxygen content in the combustible gas exceeds 10%. The energy sparks and static electricity for igniting the combustible gas. Use the probes of the original combustible gas alarm analyzer system to collect the combustible gas concentrations at various points above the outer floating roof sealing ring for data processing and analysis.

[0103] Use the probes of the original combustible gas alarm analyzer system to collect the combustible gas concentrations at various points above the outer floating roof sealing ring for data processing and analysis. See details in: the kinetic energy, potential energy, friction, and the curve graphs of the running curve and change rate of the combustible gas of the storage oil tank.

[0104] Combined with the change of the friction force of the outer floating roof annular sealing ring, the concentration points can be determined.

[0105] Analyze the combustible gas change rate from the change rate of the combustible gas concentration on the upper sealing ring of the outer floating disc and the time to limit. The combustible gas change rate ΔC = (Ct2 - Ct1) / (t2 - t1),

[0106] where: ΔC is the change rate concentration of the combustible gas per minute; Ct2 is the concentration of the combustible gas at time t2, V / V%; Ct1 is the concentration of the combustible gas at time t1, V / V%; t1 is the sampling time in minutes of the TIMS-DT intelligent digital platform; t2 is the sampling time in minutes of the TIMS-DT intelligent digital platform; the time Tx in minutes for the combustible gas concentration to reach the lower explosion limit concentration.

[0107] Tx = Cx / ΔC;

[0108] where: Tx is the time in minutes for the combustible gas concentration to reach the lower explosion limit concentration; Cx is the lower explosion limit concentration of the combustible gas. In this way, the combustible gas can be detected according to the combustible gas change rate ΔC and the time Tx in minutes for the combustible gas concentration to reach the lower explosion limit concentration, and nitrogen can be conveniently and timely injected for inerting to avoid explosion.

[0109] Inject nitrogen into the first and second seals of the outer floating roof to inert the combustible gas, reduce the combustible gas concentration in the first and second seals and make the concentration change rate zero, widen the flash explosion concentration Cx of the combustible gas, and design a set of nitrogen injection and pressure PID control circuits for the first and second seals, PC-02 and PC-03 control circuits. See details in Figure Six : the floating disc of the outer floating roof storage oil tank.

[0110] Inert the first and second seal spaces and the pressure and inert the oil and gas at the bottom of the tank by spraying nitrogen. The so-called oil and gas inerting means that after spraying nitrogen, since nitrogen is an inert gas and a diatomic gas, it will quickly diffuse after entering the first and second seals, eliminating two of the three explosion factors in the deflagration of the combustible gas and achieving the purpose of inerting.

[0111] Regarding the inerting pressure control range of the first- and second-stage seals, based on the current experience, standards, and calculations for the nitrogen sealing pressure control range in the space above the floating roof of the internal floating roof tank, it is safe and reliable to control the seal space pressure within 0.2 - 0.5 KPa. Because when the pressure is less than 0.2, when the ambient temperature changes, the annular space pressure will decrease, and the pressure between the floating roof and the liquid level will increase, causing liquid vaporization and an increase in combustible gases. If the space pressure is greater than 0.5 KPa, at this time, when the temperature increases, it has a greater impact on the tension and pressure of the nitrile rubber seal. The above factors and parameters are introduced into the TIMS-DT intelligent digital platform, which will perform self-learning, optimization, and automatic calibration of parameters. Due to management and operation requirements, the floating roof of the internal and external floating roof tanks sinks to the bottom. To prevent a space between the floating roof and the liquid level when the floating roof has not risen and the liquid level is lower than the floating roof valve support, if oil needs to be filled at this time, the TIMS system will start injecting nitrogen to inert the combustible gases in the space at the bottom of the floating roof. Open the xcv-01 valve, and nitrogen is injected by the SCV-01, with the pressure within the range of 10 - 12 KPa. At this time, the combustible gas analysis system above the floating roof seal ring monitors the concentration of combustible gases to prevent the concentration from exceeding the lower explosion limit value of combustible gases.

[0112] The change curves of the buoyancy B of the floating roof rising, stopping, and descending can be seen in the figure curve graph

[0113] The buoyancy B = ρ·v·g, where ρ is the density of the liquid oil product, v is the volume of the liquid oil product displaced by the floating roof, and g is the acceleration. From Figures 6 - 10 the operating curves and change rates of the kinetic energy, potential energy, and frictional force of the storage tank in Figure 4 the curve graph, it can be obtained that:

[0114] When the floating roof is stationary, the buoyancy B = mg

[0115] After the inflection point A, the acceleration of the floating roof rises and enters the oil filling state. When the floating roof rises at a constant speed and v = constant, and ΔKE = 0, the buoyancy B = mg - f. At this time, the frictional force is opposite to the rising direction and is negative. From the inflection point B to the inflection point C, the direction is downward. When doing uniform motion, the motion curve goes from the inflection point C to the inflection point D, which is a horizontal straight line.

[0116] When the floating roof reaches the required liquid level for oil filling, the floating roof stops rising and enters the stationary state. At this time, starting from the inflection point D in the curve graph, it descends and then is a horizontal straight line. The buoyancy B = mg, and the buoyancy B lifts the floating roof.

[0117] From the change curves of the buoyancy rising, stopping, and descending and the KE kinetic energy, when the floating roof is operating, its kinetic energy KE can be seen in Figure Five the operating curves and change rates of the kinetic energy, potential energy, frictional force, and combustible gases of the storage tank. In the curve graph of the kinetic energy KE work of the floating roof operation, KE = 1 / 2mv 2, it can be seen from the figure that the floating roof starts from the 0 coordinate and enters the floating roof accelerating rising and oil inlet stage. From the inflection point A of the curve, the floating roof starts the uniform rising and oil inlet stage. KE shows a horizontal straight line. From the inflection point B in the figure, the floating roof decelerates and the kinetic energy decreases. At this point, the kinetic energy becomes zero and it starts to enter the oil storage stage. From the running curve coordinates in the figure, the change of the kinetic energy KE in each running stage can be seen, and the jamming of the floating roof and the change of buoyancy can also be seen, including the change of the mass m of the floating roof. Due to reasons such as water accumulation on the floating roof, leakage of the sealed cabin, change of the friction force caused by the change of the round curvature force of the sealing surface and the wall tank, etc., it will affect the KE kinetic energy and is verified.

[0118] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An on-line real-time intelligent management system for floating roof storage tanks, characterized in that: It includes a data acquisition module (1), a floating roof tilt angle measurement module (2), an energy conservation calculation module (3), a correction function module for the change of the floating roof mass m (4), a floating roof drainage monitoring module (5), a dynamic friction change module (6), and a flash explosion prevention and monitoring function module for the sealed oil and gas space of the floating roof storage tank (7); The data acquisition module (1) is used to collect all technical parameter data in the storage tank area; the floating roof tilt angle measurement module (2) is used to measure the floating roof tilt angle; the energy conservation calculation module (3) is used to calculate the kinetic energy in the floating up and down states, the correction function module for the change of the floating roof mass m (4) is used to implement the correction of the floating roof mass m, the floating roof drainage monitoring module is used to monitor the rainwater accumulation and drainage state of the floating roof, the dynamic friction change module (6) is used to calculate the dynamic change of the friction force, and the flash explosion prevention and monitoring function module for the sealed oil and gas space of the floating roof storage tank (7) conducts flash explosion prevention and monitoring of the oil and gas space; The measurement method of the floating disc tilt angle measurement module (2) is as follows: at the top of the floating disc, an equilateral triangle with three-point positioning is used. The distances of the three points A, B, and C from the edge of the floating disc are uniformly 1.5 m. An internal floating drum liquid level transmitter or a radar liquid level gauge for measuring the crude oil liquid level is installed at each of the three points A, B, and C. The bottoms of the three internal floating roof liquid level gauges or radar liquid level gauges are consistent with the bottom edge of the floating disc and are at the same horizontal plane as the liquid surface of the oil product. Subsequently, a coordinate system is set, and then there are A(0,0), B(L,0), and C( , ), where L is the side length of the equilateral triangle; Then there is the depth plane equation of the floating roof immersed in the liquid oil: Z = pX + qY + r; where z is the height z of the slope formula, p is the coefficient of the X-axis, q is the coefficient of the Y-axis, ha is the oil immersion depth at point A, hb is the oil immersion at point B, and hc is the oil immersion depth at point C; Then the inclination angle of the floating disc .

2. The on-line real-time intelligent management system for a floating roof storage tank according to claim 1, wherein, The working method of the energy conservation calculation module (3) is to first establish an energy conservation relationship, with the formula Wli = ΔKE + ΔPE + Wfr, where Wli is the work done by the liquid on the floating roof, and Wfr is the work done by the friction force, ΔPE is the gravitational potential energy generated by the height change of the floating roof, and the formula is; ΔPE = mgh, where h is the lifting height of the floating roof and g is the acceleration due to gravity; ΔKE is the energy of the floating roof during movement, and the formula is: KE = 1 / 2mv², where m is the mass of the floating roof and v is the instantaneous velocity; Wfr is the work done by the friction force between the annular seal of the floating roof and the tank wall, and the formula is Wfr = fh, where f is the friction force and the direction is always opposite to the direction of movement; During the rising process of the floating roof: The liquid pushes the floating roof to rise through buoyancy, and the buoyancy work Wli = B·h, where: B is the buoyancy B = ρ·v·g, which is related to the volume of the liquid displaced by the floating roof; Then there is: B·h = 1 / 2mv² + mgh + f·h, When rising at a constant speed, then v is a constant speed value, ΔKE = 0, and B = mg + f, and the buoyancy needs to overcome the gravity and friction of the floating roof; During the descending process of the floating roof: The gravitational potential energy of the floating roof decreases, and ΔPE = -mgh; Then there is 1 / 2mv² = mgh - f·h When descending at a constant speed (ΔKE = 0): mg = f, and the gravitational potential energy is completely used to overcome the friction.

3. An on-line real-time intelligent management system for a floating roof storage tank according to claim 1, characterized in that, The working method of the correction function module for the change of the floating roof mass m (4) is that the correction formula for the mass m is: When the floating roof is working normally, the buoyancy B of the floating roof in the static state, then the floating roof mass m = B, where m is the mass of the floating roof, and the value of m is calculated through the buoyancy B = ρ·v, and the m in the database is corrected; When there is water accumulation on the tank top or water enters the density compartment of the floating roof; Water accumulation on the tank top or leakage in the sealed cabin will increase the weight m of the floating roof. The change in the weight of the floating roof causes a change in the oil immersion depth h of the floating roof. By obtaining the measured value of the oil immersion depth h and the average values of ha, hb, and hc at points A, B, and C, where V = h·s, where V is the oil immersion volume of the floating roof in m³, h is the oil immersion depth of the floating roof, and s is the lower top area of the floating roof in m². Then, the calculation formula for the mass m of the floating roof is: m = ρ·s·h, where ρ is the density of the oil product. The mass m in the database of the floating roof calculated using this formula will be corrected.

4. An online real-time intelligent management system for a floating roof storage tank according to claim 2, characterized in that The working method of the floating roof drainage monitoring module (5) is to install floating roof water accumulation ultrasonic level transmitters H-01, H-02, and H-03 beside the equilateral triangle A, B, and C at the top of the floating roof to measure the inclination, and monitor the water accumulation data on the floating roof top. Install a drainage flow transmitter F1-04 on the pipeline at the bottom drainage outlet of the storage tank to monitor the oil content in the drain pipe water, the blockage condition in the drain pipe, and the surging condition of the drainage hose in the storage tank. Design and establish an average height Hs of the external floating roof water accumulation with a maximum water accumulation of 250 mm. It is obtained that: Ks = Hs / 250. In the above formula: Ks is the external floating roof water accumulation change coefficient, and Hs is the average height of the external floating roof water accumulation; Ks less than 1 meets the standard, and Ks greater than 1 exceeds the standard. Establish an external floating roof bottom drainage flow Fs, and it is obtained that: Fs = F04 / F0. In the above formula, Fs is the external floating roof drainage flow coefficient, F0 is the bottom drainage flow when the external floating roof water accumulation is 250 mm, which can be obtained through simulation calculation, and F04 is the instantaneous flow at the bottom of the external floating roof. The state of the external floating roof drainage system can be analyzed through Ks and Fs, and the drainage efficiency of the system can be predicted by analyzing Ks, Fs, climate, and rainfall data.

5. The on-line real-time intelligent management system for a floating roof storage tank according to claim 1, characterized in that, The working method of the friction force dynamic change module (6) is that if the friction force is too large or changes, it will cause the floating roof to get stuck. Then, through the changes in the buoyancy B of the floating roof rising, stopping, and falling, the dynamic change of the friction force can be obtained.

6. The online real-time intelligent management system for a floating roof storage tank according to claim 1, characterized in that, The working method of the floating roof storage tank sealed oil and gas space flash explosion prevention and monitoring function module is to detect the concentration and pressure of combustible gas in the sealed oil and gas space. When the concentration in the sealed oil and gas space reaches the warning value, nitrogen injection is carried out to inert the combustible gas.

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