Control method for high-viscous oil product discharge from railroad tank cars

FIELD: control and monitor system for oil product discharge with the use of circulation heating systems, particularly in terminal station of petroleum storage depot.

SUBSTANCE: method involves determining temperature of outer tank car wall by measuring thereof in lower tank car case portion, which is the nearest to tank car bottom; comparing the measured temperature with one estimated from heat calculations performed with the use of control computer. The temperature is calculated from well-known correlations with taking into consideration previously measured temperature of ambient air and wind velocity, technical characteristics of tank cars, physical properties of oil product to be discharged and air.

EFFECT: increased efficiency due to reduced amount of residual oil product and reduced flow rate of heating agent due to determining time point optimal for heater deactivation.

1 dwg, 1 tbl

The invention relates to automated methods and management process control discharge of high-viscosity petroleum products from rail tank using a circulating heating and can be applied at transfer terminals and tank farms equipped with the circulation of heated oil in tank wagons.

It is known that the vast majority of rail tank cars equipped with a bottom drain devices. The known method discharge of high-viscosity oil rail cars (EDC) using the heated discharge device of the tank with live steam, drain most of the oil with the continuation of her heated with live steam, after which the heated oil is served in the jetting device, wash and warm up the remains until full discharge (A.S. USSR, No. 418421, B 65 G 69/20, 1971).

The disadvantage of this method is significant flooding drained oil.

There is also known a method of draining a viscous oil from GDC using a submersible folding on the bottom of the tank device, comprising preheating the oil before the formation of the upper thin layer, simultaneous heating and discharge of oil to the level of the upper generatrix of the folding elements of the device on which ograve and subsequent heating of the oil to a temperature providing a drain without a trace (as the USSR, No. 227361, B 65 D 88/74, 1966).

This method has such disadvantages as high coolant flow and low efficiency of heating devices, as posted inside the tank, they require periodic inspection and repair. In addition, the known methods are subject to control only as heat oil and its physico-chemical parameters without considering the influence of external factors (ambient temperature, wind speed and design features of the tank.

The closest in technical essence is taken as a prototype method of draining viscous liquids from a device lower discharge GDC, including the use of the circuit, in which heated oil in the heat exchanger to a certain temperature, the flow of heated oil to the lower discharge device having in its design telescopic monitor, the links of which under the pressure of heating oil moved apart, introducing nozzle head inside the tank. The heated oil from the zone of the discharge device enters the heat exchanger circulation circuit and returns to the tank.

When the temperature reaches the drain oil is sent to storage tanks, and drain the rest of the oil warm up is 10-15° With higher temperature drain in the circuit (as the USSR, No. 469644, B 67 D 5/01, 1973).

The known method has a low efficiency due to the lack of control over the temperature of the oil inside GDC that unnecessarily increases the time of heating oil and, as a result, increases the cost of the process.

In addition, as shown, the known method does not provide a complete discharge of oil due to the low temperature of the oil near the bottom of the tank especially in the cold season.

The technical result of the invention is to increase the efficiency of the method by reducing nalivaeva balance and reduction of consumption of heating agent by determining the turn off heat.

This technical result is achieved by the known method of process control discharge of high-viscosity petroleum products (TM) - equipped device lower discharge IDC, involving heating the coolant NP using its circulation to reach the value of the regulatory discharge temperature at which the viscosity of the pumped TM provides the most complete emptying of the tank according to the invention define specific heat, and pour out the oil, thermal conductivity of oil, air and material of the wall of tank wagons, vaskos the ü oil the viscosity of the air, the coefficient of volume expansion of oil density of oil, the diameter of the rail, the length of the boiler tank wagons, the thickness of the tank wall, the degree of blackness of the surface railway tanks, regulatory temperature drain oil from tank wagons and the Planck constant, measure the current values of ambient temperature, wind speed and temperature of the outer wall of the steel rail at the bottom, as close as possible to the bottom of the tank, which is compared with a calculated value of the temperature determined by the following dependencies:

t_STN ^R=t_o+k/a₁·(t_TM-t_o), where

t_STN ^Ris the calculated temperature of the outer wall GDC which corresponds to the temperature draining of oil residue, ° C;

t_o- the ambient (air), ° (readings from the sensor of thermometer);

t_TM- regulatory discharge temperature TM, providing its discharge without a trace, ° C;

a₁- the heat transfer coefficient from the wall EDC in the environment, W/(m²·°(C)equal and₁=0,032· λ_in/L· Re^0,8,

k is the coefficient of heat transfer from the oil to the environment, W/(m²· °C)determined by the formula

k=[l/a₁+δ_article/λ_article+l/a₂+l/a₃]^-1where

where a₂- the heat transfer coefficient from the NP to the wall IDC, W/(m²·°C)determined by dependencies

and₂=0,5· λ_TM/D_IDC·(Gr· Pr)_TM ^1/4·[(Pr)_TM/(Pr)_article]^1/4,

and₂- the heat transfer coefficient from the wall GDC radiation, W/(m²·°C)equal to

and₃=ε_article·C_s·{[(t_STN ^R+273)/100]⁴-[(t_o+273)/100]⁴}/(t_STN ^R-t_owhere

δ_articlethe wall thickness of the tank, m (passport data);

λ_article- coefficient of thermal conductivity of the material of the wall rail, W/(m²·°(C) (reference data);

λ_TM- coefficient of thermal conductivity of oil, W/(m²·° (C) (reference data);

λ_in- coefficient of thermal conductivity of air, W/(m²·°(C) (reference data);

D_IDCthe diameter of railroad tank cars, m (passport data);

L is the length of the boiler railroad tank cars, m (passport data);

Re - Reynolds number (dimensionless similarity criterion);

Pr dimensionless similarity criterion Prandtl calculated at a given (normative) temperature drain oil (TM) and the temperature of the inner wall of the tank (CTB) according to the following dependence

Pr_TM=ν_TM·c_TM·ρ_TM/λ_TM ^TM,

Pr_STV=ν_STV·c_STV·ρ_STV/λ_TM^STV,

Gr - dimensionless similarity criterion of Grashof equal to

Gr=D³ _IDC·g· β_TM·Δt/ν² _TMwhere

ν_TM(ν_STV- the viscosity of the oil at the temperature of the drain and the inner wall of the tank, respectively, m²/s (reference data);

with_TM(C_STV) - specific heat of the oil at the temperature of the drain and the inner wall of the tank, respectively, j/(kg· ° (C) (reference data);

ρ_TM(ρ_STV- the density of the oil at the temperature of the drain and the inner wall of the tank, respectively, kg/m³(reference data);

β_TM- coefficient of volume expansion of the oil, 1/deg (reference data);

g - acceleration of gravity=9,81 m/s²(constants is);

w_in- the current value of the wind speed, m/sec (reading from a sensor);

ν_inthe viscosity of the air, m²/s (reference data);

ε_article- degree black surface of the tank (passport data):

ε_article=1 for black;

ε_article=0,8-0,95 - for red, green, and gray;

ε_article=0.7 for aluminum coatings;

Δ t=(t_TM-t_STV ^R- the temperature difference between the NP and the inner wall of the tank ° C

where t_STV ^Restimated value of the temperature of the inner wall of the railway tank equal to

t_STV ^R=t_o+k/α₂·(t_TM-t_o),

C_sis the Planck constant, equal 5,76 Bm/(m²·°K⁴) (constant);

t_STN ^and- the current measured value of the temperature of the outer wall shell tank wagons (sensor readings) and

at t_STN ^and≥t_STN ^R, - stop the circulation of heating oil.

The technical essence of the method lies in the fact that the management of the discharge process high viscosity NP from IDC carried out according to the results of measuring the current temperature of the outer wall of the shell IDC (t_STN ^Rat the bottom point, as close the to the bottom of the tank (most remote from the bottom drain of the device), given the influence of the ambient temperature (t_o), wind speed (w_inand design features of the tank.

Installing temperature sensor TM inside IDC in its lower part near the bottoms difficult and also leads to contamination of high-viscosity oil of the fixtures and land drain. Measuring the current value of the wall temperature on the outer side GDC easy to operate and reliable.

The drawing shows a block diagram of a device implementing process control method heating and discharge of high-viscosity NP from IDC.

The device implementing the method comprises a block 1 of the data collection and processing, block 2 input parameters, the sensor 3 is at ambient temperature (air), the sensor 4 wind speed sensor 5 temperature of the outer wall GDC 6.

On the bottom of the drain unit 7 IDC 6 is set lower discharge device 8 containing a telescopic monitor 9 to allow the head 10.

The nozzle device 8 bottom drain connected to the drain manifold 11.

Telescopic monitor 9 through the pipeline (without positions) connected to the pressure reservoir 12.

The circuit of heating oil includes: drain piping (without positions), the circulation pump 13, the valve 14 controls the flow of oil into the heat exchanger 15 and the discharge pipe is the wires (without positions) connected to the pressure reservoir 12.

For flow blocking pour the heated oil to the tank battery is the valve 16, which is the period of heating (circulation) is closed.

The sensor 5 is installed in the lower part of the shell IDC in close proximity to the bottom of the tank due to the fact that the lower ends of the tank are not available for most of the heating cavities. As sensors 5 and 3 (as an option) can be used thermocouple. Could also be applied to any temperature sensor with digital or analog output signal, providing error ± 1° s when ambient temperatures from -35° C to +35° C.

Sensors ambient temperature 3 and wind speed 4 is installed in the upper part of the loading rack. The wind speed sensor is implemented on the basis of typical meteorological instrument with an accuracy of ± 1 m/sec.

As a data processing unit used a personal computer with RAM not less than 16 megabytes.

The method is implemented as follows:

EXAMPLE.

From railway tanks green, made of carbon steel, it is necessary to drain the fuel oil M-100.

Values defined and measured parameters are presented in table. 1.

In accordance with the table set and measured values for a given program are determined by the temperatures of the inner and outer walls IDC. The calculation is carried out by the method of successive approximation step:

- t^{Sha is} =+0,1° for the outer wall.

- t^step=-0,1° for the inner wall.

For the initial values of the calculated wall temperature IDC accept:

for internal walls - normative temperature drain oil (mazut M-100 t_TM=+60° C), i.e. t_STV ^R=t_TM=+60°

for the outer wall is measured by thermometer ambient temperature, i.e. t_STV ^R=t_o=-15°

In the process of data processing is the constant comparison of the temperature of the outer wall, measured by the sensor (t_STV ^and), which is constantly changing as a result of heating oil (mazut M-100) due to the circulation, and the calculated values (t_STN ^R). As soon as the estimated temperature of the outer wall (t_STN ^R=23,2° (C) will be equal to the sensor data (t_STN ^and)stop warming up and begin draining oil.

Thus, the use of the invention increases the efficiency of the drainage system of high-viscosity petroleum products using the convection-heated, significantly reducing the amount of nalivaeva residue in the tank with the required minimum needs in the coolant (pair).

Sources of information

1. AS the USSR №418421, B 65 G 69/20,1971

2. AS of the USSR, No. 227361, B 65 D 88/74,1966

3. AS OF THE USSR, NO. 46644, B 67 D 5/01,1973 (prototype).

4. Edigarov YEAR, Bobrovsky S.A. “Design and operation of tank farms and gas storage”. M.: Nedra, 1973, s-227;

5. Kutateladze S.S., Borishansky V.M. Handbook of heat transfer. HP: Gosenergoizdat, 1959, p.35-38;

6. Agapkin V.M. Borisov, S., Krivoshein B.L. reference guide for the calculations of pipelines. M.: Nedra, 1987, p.27-48

The process control method of draining viscous oil from a device bottom unloading rail tank car, comprising heating a heat carrier oil using its circulation to reach the value of the regulatory discharge temperature at which the viscosity of the pumped oil provides the most complete emptying of the tank, characterized in that ask specific heat, and pour out the oil, thermal conductivity of oil, air and material of the wall of tank wagons, the viscosity of the oil, the viscosity of the air, the coefficient of volume expansion of oil density of oil, the diameter of the rail, the length of the boiler tank wagons, the thickness of the tank wall, the degree of blackness of the surface railway tanks, regulatory temperature drain oil from rail tanks and Planck constant, measure the current values of the temperature environment, wind speed and temperature of the outer wall of the steel rail at the bottom, as close as possible to the bottom of the tank, which is compared with a calculated value of the temperature determined by the following dependencies:

t_STN ^R=t_o+k/a₁·(t_TM-t_o),

where t_STN ^Ris the calculated temperature of the outer wall of the rail which corresponds to the temperature draining of oil residue, ° C;

t_o- the ambient (air), ° (readings from the sensor of thermometer);

t_TM- standard temperature drain oil, providing its discharge without a trace, ° C;

a₁- the heat transfer coefficient from the wall rail in the environment, W/(m²·°C)equal to

and₁=0,032· λ_in/L· Re^0,8,

k is the coefficient of heat transfer from the oil to the environment, W/(m²·°C)determined by the formula

k=[l/a₁+δ_article/λ_article+l/a₂+l/a₃]^-1,

where a₂- coefficient of heat transfer from the oil to the wall of tank wagons, W/(m²·°C)determined by dependencies

and₂=0,5· λ_TM/D_IDC·(Gr· Pr)_TM ^1/4·[(Pr)_TM/(Pr)_STV]^1/4,

and₃- the heat transfer coefficient from the wall rail radiation, W/(m²·°C)equal to

and₃=ε_article·C_s·{[(t_STN ^R+273)/100]⁴-[(t_o+273)/100]⁴}/(t_STN ^R-t_o)

where δ_articlethe wall thickness of the tank, m (passport data);

λ_article- coefficient of thermal conductivity of the material of the wall rail W/(m²·°(C) (reference data);

λ_TM- coefficient of thermal conductivity of oil, W/(m₂·°C) (reference data);

λ_in- coefficient of thermal conductivity of air, W/(m²·°C) (reference data);

D_IDCthe diameter of railroad tank cars, m (passport data);

L is the length of the boiler railroad tank cars, m (passport details;)

Re - Reynolds number (dimensionless similarity criterion), Re=w_in/D_IDC/v_in,

Pr dimensionless similarity criterion Prandtl calculated at a given (normative) temperature drain oil (TM) and the temperature of the PE the inner tank wall (STW) for the following dependencies:

Pr_TM=ν_TM·c_TM·ρ_TM/λ_TM ^TM;

Pr_STV=v_STV·c_STV·ρ_STV/λ_TM ^STV;

Gr - dimensionless similarity criterion of Grashof equal to

Gr=D³ _IDC·g· β_TM·Δt/v² _TM,

where ν_TM(ν_STV- the viscosity of the oil at the temperature of the drain and the inner wall of the tank, respectively, m²(reference data);

c_TM(c_STV) - specific heat of the oil at the temperature of the drain and the inner wall of the tank, respectively, j/(kg· ° C), (reference data);

ρ_TM(ρ_STV- the density of the oil at the temperature of the drain and the inner wall of the tank, respectively, kg/m³(reference data);

β_TM- coefficient of volume expansion of the oil, 1/deg (reference data);

g - acceleration of gravity=9,81 m/s²(constant);

w_in- the current value of the wind speed, m/s (readings from a sensor);

ν_inthe viscosity of the air, m²(reference data);

ε_article- degree black surface of the tank (passport d is installed):

ε_article=1 for black;

ε_article=0,8-0,95 - for red, green, and gray;

ε_article=0.7 for aluminum coatings

Δ t=(t_TM-t_STV ^p- the temperature difference between the oil and the inner wall of the tank ° S, where t_STV ^Restimated value of the temperature of the inner wall of the railway tank equal to

t_STV ^R=t_o+k/α₂×(t_TM-t_o),

C_sis the Planck constant, equal 5,76 W/(m²°K⁴) (constant);

t_STN ^and- the current measured value of the temperature of the outer wall shell tank wagons (sensor readings) and at t_STN ^and≥t_STN ^Rlonger warm-up and circulation of heating oil.