RU2196805C1 - Method of cleaning crude oil from suspended impurities - Google Patents

Abstract

FIELD: crude oil treatment. SUBSTANCE: method consists in heating crude oil and cleaning it in centrifuge, at least two viscosity measurements being performed at different temperatures, and oil heating temperature ensuring specified quality of product (T) is found from equation:

, in which u denotes viscogram slope coefficient

; t and t₀ are oil temperatures, ^°C; ν, ν_o are kinematic viscosity values, cSt; c required concentration of suspended impurities in oil, %; Q_pr specified productivity of centrifuge, cu.m/h; k, f, and d are empiric coefficients. EFFECT: enabled achieving required mechanical purification degrees owing to oil temperature control possibility. 1 dwg

Description

 The invention relates to the field of primary preparation of crude oil in the fields and can be used for its purification from solids.

 There is a method of primary preparation of crude oil, which consists in degassing, dehydration and desalting of oil [1]. (A.S. 362043, publ. 12/13/1972).

 However, this method does not provide for the purification of oil from impurities.

 The closest technical solution (prototype) is a method for deep purification of preheated crude oil from solids using a centrifuge [2]. (Pat. Canada CA 1314490, publ. 16.03.1993). The heating of hydrocarbons provides a decrease in their viscosity and a deeper purification.

 However, in the known method there is no technology for maintaining the required concentration of solids when changing the viscosity of oil, which may differ by several orders of magnitude.

 The objective of the proposed method is to obtain at a given centrifuge performance the required concentration of solids in oil by adjusting the viscosity of the oil by heating it to the appropriate temperature.

при этом показатель крутизны вискограммы определяют из соотношения:

где u - показатель крутизны вискограммы;
t, t_o - температура нефти, ^oС;
ν, ν_o - кинематическая вязкость, сСт;
с - требуемая концентрация мехпримесей в нефти, %;
Q₃ - заданная производительность центрифуги, м³/ч;
k, f и d - эмпирические коэффициенты.To solve this problem in a known method, including its heating and cleaning in a centrifuge, it is new that at least two viscosity measurements are made at different temperatures, and the temperature of the oil heating, which provides the desired oil quality, is determined from the ratio:

while the slope of the visogram is determined from the ratio:

where u is an indicator of the steepness of the visogram;
t, t _o - oil temperature, ^o С;
ν, ν _o - kinematic viscosity, cSt;
C is the required concentration of solids in oil,%;
Q ₃ - the specified performance of the centrifuge, m ³ / h;
k, f and d are empirical coefficients.

 As a result of the application of the proposed method, the required depth of oil purification from mechanical impurities is achieved with fluctuations in the viscosity of oil entering the refining.

 These signs can eliminate the disadvantage inherent in the known method of oil refining due to the selection of the technological regime of refining, depending on the properties of the oil and the parameters of the centrifuge.

 We are not aware of methods for purifying oil from mechanical impurities that have a combination of the above characteristics, which means that the proposed method meets the requirements for inventions.

 As you know, the viscosity of oils can be used over a wide range depending on their origin. Even within the same field, the viscosity of oil produced from different reservoirs can vary significantly.

 To obtain the required concentration of mechanical impurities, it is necessary that for certain parameters of the centrifuge, due to its design and technical and technological parameters, the viscosity of the oil fed to the centrifuge, regardless of its initial viscosity, does not exceed the permissible value. Therefore, to obtain the required oil refining depth, it is necessary to maintain a certain viscosity by adjusting the temperature of the oil preheating.

B зависимости от конструктивных особенностей центрифуги, ее сепарационные свойства характеризуются некоторой постоянной величиной и для получения требуемой глубины очистки жидкости от мехпримесей необходимо при заданной производительности иметь определенную вязкость очищаемой жидкости.The temperature dependence of oil viscosity is described by the empirical Reynolds relation
ν = ν _o exp [-u (tt _o )]
where t, t _o - oil temperature, ^o С;
ν, ν _o - kinematic viscosity, cSt;
u is an indicator of the steepness of the visogram,
where from

Depending on the design features of the centrifuge, its separation properties are characterized by a certain constant value and in order to obtain the required depth of liquid purification from mechanical impurities, it is necessary to have a certain viscosity of the liquid being purified at a given performance.

The relationship between viscosity and productivity is expressed by the hyperbole equation of the form
(ν-f) (Qd) = k • c (2)
where Q is the productivity of the centrifuge, m ³ / h;
C is the required concentration of solids in oil,%;
ν is the kinematic viscosity of the liquid being cleaned, cSt;
k, c and d are empirical coefficients.

Способ очистки нефти от мехпримесей осуществляют следующим образом. Производят по меньшей мере два замера вязкости нефти ν_o, ν при различных температурах t_o, t и определяют показатель и крутизны вискограммы из соотношения (1).Using dependencies (1) and (2), for a given centrifuge performance Q ₃ , the temperature necessary to obtain the required concentration of solid phase in oil can be determined

The method of purification of oil from impurities is as follows. At least two measurements are made of the oil viscosity ν _o , ν at various temperatures t _o , t and the indicator and steepness of the visogram are determined from relation (1).

 Using the characteristic of the centrifuge expressing the dependence of the performance Q of the centrifuge on the viscosity ν, we determine the empirical coefficients k, f, and d from relation (2).

 The obtained indices u, k, f and d are used to determine the required oil heating temperature from relation (3).

 Consider an example implementation of the proposed method.

 In the drawing, numeral 1 denotes a curve expressing the dependence of oil viscosity of the Kiyazlinskoye field on the heating temperature, and numeral 2 represents a typical curve characterizing the relationship between the performance of an OGSh type centrifuge and the viscosity of the liquid being cleaned, at which the required concentration of solids with = 0.05% is achieved.

Используя данные, приведенные на графике, выражающем соотношение между производительностью центрифуги и вязкостью очищаемой жидкости, получаем значения эмпирических коэффициентов в соотношении (2)
k=5920; f=1 сСт; d=1,5 м³/ч
Подставляя величины u, t_o, ν_o,k, d и с при заданной производительности центрифуги Q₃= 10 м³/с, используя соотношение (3), получаем требуемую температуру нагрева, обеспечивающую получение заданного качества нефти.We measure viscosity at temperatures t _o and t, for example, 20 ^o C and 34 ^o C. At these temperatures ν _o = 131 cSt, ν = 87.5 cSt. Then the slope of the visogram is

Using the data shown in the graph expressing the relationship between the performance of the centrifuge and the viscosity of the liquid being cleaned, we obtain the values of empirical coefficients in the relation (2)
k = 5920; f = 1 cSt; d = 1.5 m ³ / h
Substituting the values of u, t _o , ν _o , k, d and c for a given centrifuge productivity Q ₃ = 10 m ³ / s, using relation (3), we obtain the required heating temperature, which ensures a given oil quality.

Таким образом, для получения требуемой концентрации мехпримесей 0,05% при заданной производительности центрифуги 10 м³/ч и данных свойствах нефти необходимо ее нагреть до температуры 65^oС.

Thus, to obtain the desired concentration of solids 0.05% for a given centrifuge performance of 10 m ³ / h and these oil properties, it is necessary to heat it to a temperature of 65 ^o C.

SOURCES OF INFORMATION
1. A.S. 362043, publ. 12/13/1972.

 2. Canadian Patent CA 1314490, publ. 03/16/1993.

Claims (1)

A method of purifying oil from mechanical impurities, including its heating and purification in a centrifuge, characterized in that at least two viscosity measurements are made at various temperatures, and the temperature of oil heating, which provides a given oil quality, is determined from the ratio

while the rate of slope of the visogram is determined from the ratio

where u is an indicator of the steepness of the visogram;
t, t _o - oil temperature, ^o С;
ν, ν _o - kinematic viscosity, cSt;
C is the required concentration of solids in oil,%;
Q ₃ - the specified performance of the centrifuge, m ³ / h;
k, f and d are empirical coefficients.