RU2783130C1 - Method for determining hydrocarbon emissions from tanks into the atmosphere - Google Patents

Abstract

FIELD: petroleum industry.

SUBSTANCE: invention relates to the transport and storage of petroleum and petroleum products, in particular, to methods for controlling hydrocarbon emissions from tanks into the atmosphere. Method involves measuring the level and sampling the petroleum/petroleum product contained in the tank, as well as measuring the temperature and pressure in the gas space of the tank and the content of oxygen in the air-vapour mixture (AVM) displaced from the tank. Based on the resulting data, the mass of hydrocarbon emission into the atmosphere is calculated when the tank is filled with petroleum/petroleum product, by the formula

in case of stationary storage of petroleum/petroleum product, the mass is calculated by the formula

where: m_h is the average content of hydrocarbons in 1 m³ of the air-vapour mixture; K_e is the average coefficient of excess of the volume of the air-vapour mixture displaced into the atmosphere over the injected volume; T_in, V_in, P_g1 are the initial temperature, volume and pressure of the gas space of the tank at the beginning of movement of the AVM in the mounting branch pipe of the tank; T_end, V_end, P_g2 are the temperature, volume and pressure of the gas space of the tank at the end of movement of the AVM in the mounting branch pipe of the tank; V_g is the volume of gas space during storage; c_in, c_end is the volume concentration of hydrocarbons in the gas space of the tank initially, at the beginning of movement of the AVM in the mounting branch pipe of the tank and at the end of movement of the AVM in the mounting branch pipe of the tank. The resulting emission values are summed up for one day, one week, or another required period of time, wherein the molar mass of the vapours of petroleum/petroleum product injected/contained in the tank is determined within the same period.

EFFECT: reduction in the labour intensity and increase in the accuracy of determining hydrocarbon emissions into the atmosphere, as well as expansion of the range of technical means.

2 cl, 1 dwg

Description

Field of invention

The invention relates to the transport and storage of oil and petroleum products, in particular, to methods for controlling emissions of hydrocarbons from tanks into the atmosphere.

State of the art

A known direct method for determining the loss of oil / oil products from evaporation by calculation and experiment by the concentration and average density of vapors displaced from tanks [RD 153-39-019-97 Guidelines for determining the technological losses of oil at the enterprises of oil companies of the Russian Federation / In the book. Industrial safety in gas processing industries: Collection of documents. Series 08. Issue 1 / Col. ed. - M .: State Unitary Enterprise "Scientific and Technical Center for Safety in Industry of the Gosgortekhnadzor of Russia", 2002]. The loss of hydrocarbons for one filling of the tank is calculated by the formula of V.I. Chernikin [Chernikin V.I. Construction and operation of tank farms. M.: Gostoptekhizdat, 1955. 518 p.]

where C _cf is the average volumetric concentration of hydrocarbons in the outgoing vapor-air mixture for the entire period of filling,

C ₀ , C ₁ , C ₂ , C ₃ - volumetric concentration of hydrocarbons in the vapor-air mixture leaving the tank at the beginning of filling, at two intermediate points and at the end of filling, fractions of a unit;

C _n , T _n , V _n , P _n - volume concentration of hydrocarbons and temperature in the gas space of the reservoir, as well as the volume of the gas space (GP) of the reservoir and the pressure in it at the beginning of filling;

C _to , T _to , V _to , P _to - the same at the end of filling;

ρ ₀ - the average density of hydrocarbon vapors in the outgoing steam-air mixture for the entire period of filling.

The average density of the hydrocarbon part of the oil/oil product vapor is determined by the results of chromatographic analyzes of the composition of samples of the vapor-air mixture according to GOST 14920.

The concentration of hydrocarbons is determined at least 8 times during the filling of the reservoir by analyzing samples of the vapor-air mixture on gas analyzers or chromatographs. The concentration of hydrocarbons in the vapor-air mixture (PVA) is determined as the arithmetic mean of all values during the filling of the reservoir.

The disadvantage of this method is the high laboriousness of taking and analyzing a large number of PVA samples, as well as ignoring the fact that the volume of PVA displaced into the atmosphere during operations with volatile oil products, as a rule, exceeds the injection volume.

There are known indirect methods for determining emissions of oil/oil product vapors by changing their physical and chemical properties (saturated vapor pressure, hydrocarbon composition of the hydrocarbon liquid in samples taken before and after the reservoir) [RD 153-39-019-97 Guidelines for determining the technological losses of oil at the enterprises of oil companies of the Russian Federation / In the book. Industrial safety in gas processing industries: Collection of documents. Series 08. Issue 1 / Col. ed. - M .: State Unitary Enterprise "Scientific and Technical Center for Safety in Industry of the Gosgortekhnadzor of Russia", 2002]. The disadvantage of indirect methods, in addition to high labor intensity, is a significantly lower measurement accuracy.

There is a known calculation method for determining emissions of oil/oil product vapors for the year according to empirical formulas that use numerical coefficients depending on the turnover ratio of tanks, the pressure of saturated vapors of oil/oil product [Guidelines for determining emissions of pollutants into the atmosphere from tanks with additions of the Research Institute Atmosphere ( approved by order No. 199 of 04/08/98). M.: RF State Committee for Environmental Protection, 1999. 38 p.]. The disadvantage of this method is its low accuracy, because actual emission conditions are not taken into account, and numerous empirical formulas used in the calculation have a high error.

The closest to the proposed technical essence is a direct method for determining the release of oil/oil product vapors from evaporation by measuring the volume of PVA displaced from the reservoir, as well as the concentration and average density of vapors [RD 153-39-019-97 Guidelines for determining the technological losses of oil per enterprises of oil companies of the Russian Federation / In the book. Industrial safety in gas processing industries: Collection of documents. Series 08. Issue 1 / Col. ed. - M .: State Unitary Enterprise "Scientific and Technical Center for Safety in Industry of the Gosgortekhnadzor of Russia", 2002]. The release value is calculated by multiplying the average density of hydrocarbon vapors displaced from the reservoirs, reduced to a pressure of 0.101 MPa and a temperature of 273 K, by the volume concentration of hydrocarbons in the PVA leaving the reservoir and by the volume of the steam-air mixture, reduced to a pressure of 0.101 MPa and a temperature of 273 K, released from tank for a controlled period of time.

When calculating the average vapor density based on the results of chromatographic analyzes, the arithmetic mean value is taken.

The concentration of hydrocarbons in PVA is determined as the arithmetic mean of all values during the filling of the reservoir.

The volume of the steam-air mixture leaving the tanks is measured by rotary gas meters, selected according to the maximum expected performance; normal diaphragms or anemometers mounted on the mounting nozzles of the breathing valves of the tanks.

The disadvantages of this method are the high laboriousness of the selection and analysis of a large number of PVA samples, as well as the high error in determining the volume of PVA released from the tank, due to insufficient tightness of the roof, hatches and upper belts of the tank.

The present invention solves the problem of reducing the complexity and improving the accuracy of determining emissions.

Brief description of the drawings

The present invention is illustrated by the drawing (Fig. 1).

In FIG. 1 shows a diagram of equipping an oil / oil product tank with instruments for performing measurements, processing and storing them.

According to FIG. 1, temperature sensors 4, pressure 5 and oil/oil product level 6 are placed in the gas space of the tank 1, and PVA flow sensors 7 and oxygen content in it 3 are placed in the mounting pipe of the breathing valves. To receive and process sensor readings in the "online" mode, information processing and recording device 8.

The method is implemented as follows.

When the PVA starts moving in the mounting pipe of the breathing fittings, according to the signal from the flow sensor 7, the device 8 records the values of temperature, pressure and volume of the gas space of the tank, as well as the oxygen content in the PVA displaced from the tank at a given time. When the movement of PVA in the mounting pipe of the breathing fittings stops, according to the signal of the flow sensor 7, the device 8 again records the values of temperature, pressure and volume of the gas space of the tank, as well as the oxygen content in the PVA displaced from the tank at the moment the movement of the PVA stops in the mounting pipe of the tank.

In addition, periodically (for example, once a day) a sample of the oil/oil product in the tank is taken, which is analyzed to determine the molar mass of its/its vapors.

Based on the data obtained, for each outlier, the following is calculated:

- the average content of hydrocarbons in 1 m ^{3 of} the vapor-air mixture;

- the average coefficient of excess of the volume of the steam-air mixture displaced into the atmosphere over the injection volume.

Next, the mass of hydrocarbons released into the atmosphere is calculated using the formulas:

- when filling the tank with oil / oil product

- during stationary storage of oil / oil product

where: m _y - the average content of hydrocarbons in 1 m ^{3 of} the vapor-air mixture;

K _p - the average coefficient of excess of the volume of the steam-air mixture displaced into the atmosphere, over the injection volume;

T _n , V _n , R _g1 - temperature, volume and pressure of the gas space of the tank at the beginning of the movement of the PVA in the mounting pipe of the tank;

T _c , V _c , R _g2 - temperature, volume and pressure of the gas space of the tank at the moment of the cessation of the movement of the PVA in the mounting pipe of the tank;

V _g - the volume of the gas space of the tank during storage;

с _н , с _к - volumetric concentration of hydrocarbons in the gas space of the reservoir, respectively, at the beginning of the movement of the PVA in the mounting pipe of the tank and at the moment of termination (at the end) of the movement of the PVA in the mounting pipe of the tank.

To determine the values of temperature, pressure and level of oil / oil product, oxygen content in the steam-air mixture displaced from the tank

The values of temperature, pressure and level of oil/oil product, oxygen content in the vapor-air mixture displaced from the tank, as well as the moments of the beginning and end of the release of hydrocarbons are recorded according to the readings of the sensors.

The present description of the implementation of the present invention illustrates the operation of the proposed method for determining emissions of hydrocarbons from reservoirs into the atmosphere. The scope of this invention is defined by the attached claims, taking into account possible equivalent features.

Claims (13)

1. A method for determining the release of hydrocarbon vapors from tanks into the atmosphere, which involves measuring the level of oil / oil product in it, as well as sampling the oil / oil product, characterized in that at the beginning and at the end of the movement of the vapor-air mixture (PVA) in the mounting pipe of the respiratory fittings measure the temperature and pressure in the gas space of the tank, as well as the oxygen content in the vapor-air mixture displaced from the tank, based on the data obtained, calculate the mass of hydrocarbons released into the atmosphere according to the formulas: when filling the tank with oil / oil product

during stationary storage of oil / oil product

where m _y - the average content of hydrocarbons in 1 m ³ steam-air mixture; K _p - the average coefficient of excess of the volume of the steam-air mixture displaced into the atmosphere, over the injection volume; T _n , V _n , R _g1 - temperature, volume and pressure of the gas space of the tank at the beginning of the movement of the PVA in the mounting pipe of the tank; T _c , V _c , R _g2 - temperature, volume and pressure of the gas space of the tank at the moment of the cessation of the movement of the PVA in the mounting pipe of the tank; V _g - the volume of the gas space of the tank during storage; s _n , s _k - volume concentration of hydrocarbons in the gas space of the tank, respectively, at the beginning of the movement of the PVA in the mounting pipe of the tank and at the time of termination - at the end of the movement of the PVA in the mounting pipe of the tank; the obtained emission values are summarized for a day, a week, or another necessary period of time, while within the same period, the molar mass of oil/oil product vapor injected/located in the reservoir is determined. 2. The method according to p. 1, characterized in that to determine the moments of the beginning and end of the release of hydrocarbons, a vapor-air mixture flow sensor is used, while the values of temperature, pressure and oil / oil product level, oxygen content in the vapor-air mixture displaced from the tank are also recorded according to the readings sensors.

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