Determination of losses of oil or oil products from evaporation in emissions of steam-air mix at filling in transportation tanks

FIELD: oil-and-gas industry.

SUBSTANCE: hydrocarbons concentration is measured in vapour-air mix flowing from filler neck as well as time interval from fill in start to initial occurrence of hydrocarbons in said mix, said concentration being taken as the minimum magnitude. Time interval when hydrocarbons concentration reaches maximum magnitude and moment when maximum level in the tank is reached are measured. Bulk of losses of oil or oil products is determined by the formula: M " п п " = V " ц " [ ( t " ц " t C m a x ) C m a x t " ц " + ( t C m a x t C m i n ) ( C m a x + C m i n ) 2 t C m a x ] , where M"пп" is bulk of losses caused by evaporation in vapour-air mix emissions, kg; V"ц" is tank volume, m3; t"ц" is time interval from fill in start to maximum fill in level, min; Cmax is maximum concentration of hydrocarbons in said mix, kg/m3; Cmin is minimum concentration of hydrocarbons in said mix, kg/m3; tCmax is time interval from fill in start to occurrence of vapours with concentration Cmax, min; tCmin is time interval from fill in start to occurrence of vapour with concentration Cmin, min.

EFFECT: lower labour input, higher accuracy of loss determination.

1 tbl

 

The method of determining losses applicable in the preparation and transportation of oil and water emulsions, and enterprises engaged in the refining, transportation and distribution of petroleum products.

At present great attention is paid to implementation of the management, the problems of unbalance and improvement of measurement and metering of oil or petroleum products during processing, transportation, storage and consumption. In this light, it is urgent to create a simple to use and highly accurate method for determining the losses of hydrocarbons from evaporation during filling, transport containers.

There is a method of determining the mass loss of oil and oil products from evaporation in the emissions of air-steam mixture in the process of lling a certain volume (Abazova F. F., Bronstein, I. S. and others Struggle with the loss of oil and oil products during their transportation and storage. - M.: Nedra, 1981, S. 26). Commonly used to measure the concentration of hydrocarbons in the steam-air mixture at the outlet of the neck of the container and having an average concentration according to the formula calculate the mass losses of hydrocarbons:

where M is the mass loss of oil and oil products from evaporation from the tank during filling, kg;

Ccp- the average mass to ncentrate vapors of hydrocarbons expelled from the tank vapor mixture, kg/m3;

V is the volume displaced from the tank vapor mixture, m3.

There is also known a method of determining the volume of light hydrocarbons (Abazova F. F., Bronstein, I. S. and others Struggle with the loss of oil and oil products during their transportation and storage. - M.: Nedra, 1981, S. 75), lose when filling vehicle tanks, including the determination of the value of emissions as the volume of injected oil, measuring the density of the vapor of the oil in the steam-air mixture at the outlet from the tank neck, the determination of the saturated vapor pressure of petroleum products and the subsequent calculation of the value of mass loss of hydrocarbons by the formula:

where kT- the ratio of the saturation vapor oil (tabular values obtained experimentally);

VZack- the volume of injected oil m3;

Psthe vapor pressure of a petroleum product, kPa;

Pabsthe absolute pressure of the gas space capacity, kPa;

ρ is the density of vapors of oil, kg/m3.

This method does not determine the true value of the amount of propelling steam-air mixture due to evaporation of the oil, as the ratio of the saturation vapor oil kTused in the calculation formula obtained experimentally for different climatic zones and PE is the iodines, and is valued what determines the high accuracy of calculations.

There is a method of determining the volume of light hydrocarbons (Budurov I. P. study of the evaporation of motor fuels during storage. thesis of candidate of technical Sciences. - M.: Institute of fuel MO, 1958, S. 70) lost when filling vehicle tanks, including the determination of the value of emissions as the volume of injected oil, the measurement of the concentration of hydrocarbons in the steam-air mixture at the outlet of the neckline capacity at the start and end points in time and the subsequent calculation of the value of mass loss of hydrocarbons by the formula:

where Vcontainer- volume of tank, m3;

k - conversion coefficient of the volume concentration in the mass concentration of vapors of oil (calculated separately);

CM1Cm2mass concentration of hydrocarbons in the gas space of the vessel, respectively, the start and end time points of the vessel.

The disadvantage of this method is its significant error due to the fact that they make the assumption - saturated steam-air mixture instantly to the maximum possible concentration of oil vapor. But, as practice shows, this process is longer, and that gives the error in the calculations.

The closest technical with whom snasti and taken for the prototype is a method for determining loss of hydrocarbon oil and petroleum products from evaporation concentration of hydrocarbon vapors (Bolshaya Century. And. The construction and operation of oil depots. - M.: Costoptimized, 1955, S. 330) that is displaced from the container during a single filling, which includes the determination of the volume of the gas space capacity as the geometric volume (data from passports to capacity), the determination of the temperature and pressure of the gas space at the time of filling the tank, the measurement of the maximum concentration of hydrocarbons in the steam-air mixture at the outlet of the neck vessels, measurement of molecular weight hydrocarbon vapors and subsequent calculation of the value of mass loss of hydrocarbons by the formula:

where V is the volume of the gas space capacity, m3;

T is the temperature of the gas space at the time of filling the tank, To;

P is the pressure of the gas space at the time of filling containers, PA;

C - the maximum value of the volume concentration of hydrocarbons in the gas space capacity;

M - molecular weight hydrocarbon vapors, kg/mol;

- universal gas constant, j /(mol*K).

This method solves the problem of determination of the loss of oil, gives a fairly objective picture, but has significant error due to the fact that it does not take into account the uneven distribution of concentration of oil vapor at the height of the gas space is TBA, associated with the evaporation of petroleum products with a high vapor pressure occurring in the process of filling the tank. Also the disadvantage of this method is the need to use complex and expensive measuring equipment (chromatograph, etc.,) to determine the molecular weight hydrocarbon vapors, if take-valued molecular weight hydrocarbon vapors, it causes a significant error in the calculations.

The technical result of the invention is to reduce the complexity and increase the accuracy of determination of loss of hydrocarbon oil from evaporation when filling out the shipping container.

This technical result is achieved by the fact that to determine the mass loss of oil or oil from evaporation in the emissions of steam-air mixture during the filling of the transport capacity of a given size, including the lling of oil or oil products to the maximum level and the measurement of the concentration of hydrocarbons in the steam-air mixture at the outlet of the neck tank, process vessel, record the time of commencement of loading of oil or oil product, fixed period of time from start of loading to the initial occurrence of hydrocarbons in the vapor mixture, which is taken for the minimum value of the concentration, the length of time before momentdesire the maximum value of the concentration of hydrocarbons in the steam-air mixture and the length of time to achieve the maximum filling level, and the weight loss of oil or oil products is determined by the following formula:

where MPP- weight loss of oil or oil from evaporation in the emissions of air-steam mixture, kg;

VC- tank capacity, which is the volume of the gas space capacity, m3;

tC- the length of time from start of loading capacity up to the maximum filling level, min;

Cmax- the maximum mass concentration of hydrocarbons in the vapor mixture, kg/m3;

Cmin- minimum mass concentration of hydrocarbons in the vapor mixture, kg/m3;

tCmax- the length of time from start of loading to the exit vapor concentration Cmax, min;

tMin- the length of time from start of loading to the exit vapor concentration Cminmin

These distinctive properties in conjunction with the known are essential to achieve a technical result as a measurement of time intervals from start of loading to:

- initial occurrence of hydrocarbons in the vapor mixture, which is the minimum concentration value;

- the moment of maximum hydrocarbon concentration in the vapor mixture;

- end loading to the maximum level in the tank,

allow the objective to take into account the uneven distribution of concentration of oil vapor at the height of the gas space and to simplify the way therefore there is no need for complex equipment.

The method is implemented as follows.

Before loading capacity determine the volume of the gas space VCstatic methods GOST R 8.595-2004 as a geometric volume or take the data from the passport on capacity. Prepare to work the detector and stopwatch. Intake tube of the detector set at the level of the lower edge filler neck of the tank. Include a stopwatch at the beginning of loading of oil or petroleum products and measure the current values of the concentration of hydrocarbons in the vapor mixture. When in a steam-hydrocarbon vapor mixture is fixed first period of time tMinfrom the beginning of loading to the initial occurrence of hydrocarbons in the steam-air mixture with a concentration of Cmin. When reaching into the outgoing steam-air mixture concentration of vapors of the hydrocarbons of the maximum of Cmaxfix the second period of time tCmaxfrom the start of loading until reaching the maximum value of the concentration of hydrocarbons in the vapor mixture. The third period of time tCfixed at the end of loading to the maximum value. Using the obtained values, find the mass losses of hydrocarbons from evaporation by the formula (5).

The claimed method was tested p. and loading of various petroleum products in the transport capacity on the facilities of the refinery, the results shown in table 1.

Table 1
No.ProductCapacity MCm3tCmin,minCming/m3tCmax,mintCmax,g/m3tC, minWeight loss f-Le (5) MPP,gWeight loss f-Le (4) G, g
1Nefras P-1662,81to 4.6258,82764,3367,030321,845441,80
2Regular 92613,49to 124.49,13021,7510,2679996,7978612,1
3Regular 92 61,32,358,899,32879,5510,1881418,7571738,5
4Mazut M100660,08at 83.5412,8753,33467023,3226,49
5Alkylate664,35to 4.6237817,654533538,526227,61
6DT furnace66117,786,54408,8311,0722966,831556,90
7TS-1662,33of 3.56 12515,4814,118869,312475,15
8AI-98665,1271,1044,891635,35060918,9624910,4

As can be seen from the obtained results, the claimed method has a higher accuracy of determination of the loss of hydrocarbons of petroleum or petroleum products from evaporation during filling, transport capacity, and reduced complexity when using this method, because its application does not require the use of complex equipment.

The proposed solution is new as from publicly available information is not known a technique in which the measured time intervals from start of loading to changes in concentrations of hydrocarbon vapors in air-steam mixture leaving.

The proposed solution is industrially applicable, as to its implementation can be used with standard equipment, widely used in the field of measurement technology.

Method for determination of mass loss of oil or oil products from evaporation of Wabash steam-air mixture during the filling of the transport capacity of a given size, includes filling the tank with oil or oil to the maximum level and the measurement of the concentration of hydrocarbons in the steam-air mixture at the outlet of the neck of the container, characterized in that in the process of filling the tank, record the time of commencement of loading of oil or oil products, fixed period of time from start of loading to the initial occurrence of hydrocarbons in the vapor mixture, which is taken for the minimum value of concentration, the length of time until reaching the maximum value of the concentration of hydrocarbons in the steam-air mixture and the length of time to achieve the maximum level, and a lot of loss of oil or oil products is determined by the following formula:

where MPP- weight loss of oil or oil from evaporation in the emissions of air-steam mixture, kg;
VC- the amount of transport capacity, which is the volume of the gas space capacity, m3;
tC- the length of time from start of loading capacity up to the maximum filling level, min;
Cmax- the maximum mass concentration of hydrocarbons in the vapor mixture, kg/m3;
Cmin- minimum mass concentration of hydrocarbons in the vapor mixture, kg/m3;
tCmax- the length of time from start of loading to the exit of the vapor concentration C max, min;
tMin- the length of time from start of loading to the exit vapor concentration Cminmin



 

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