CC BY
4
UDK 665.6/.7: 662.6/.9: 662.9
Mukhammadzhonova I. trainee applicant Namangan Engineering and Technology Institute
Uzbekistan, Namangan city Sayidmuradov M. senior lecturer
Department of Process Machines and Equipment Namangan Engineering and Technology Institute
Uzbekistan, Namangan city Xudayberduyev A.
Associate Professor Namangan Engineering and Technological Institute
Uzbekistan, Namangan city
EXPERIMENTAL STUDIES FOR STUDYING PROCESSES OF COOLING HYDROCARBON VAPORS
Abstract: The article presents the results of an experimental study to study the intensification of the heat transfer process during air cooling of hydrocarbon vapors and oil distillates in tubular apparatuses and the development of recommendations for increasing the energy efficiency of industrial air and water coolers that are part of the primary oil distillation unit.
Key words: heat exchange, heat transfer intensification, air cooler, hydrocarbon vapor cooling, pressure drop, efficiency.
Introduction. Air coolers and condenser-coolers of various technological streams are widely used in the oil refining industry. The use of air coolers provides a number of operational advantages, the main of which are saving cooling water and reducing the amount of wastewater, reducing labor costs for cleaning the apparatus due to the absence of scale and scale deposition, and reducing the cost of organizing the circulating water supply of technological units [1].
In air coolers, atmospheric air is used as a refrigerant, flowing in the transverse direction around parallel rows of finned heat exchange tubes through which the cooled product moves. The movement of cooling air is carried out by pumping it with a fan, and in winter, in some cases, due to natural circulation.
The use of pipes finned along the outer surface of the air cooler is due to the need to compensate for the low heat transfer coefficient from the air side due to the developed outer surface of heat transfer [2].
Experimental setup and experimental technique. To study and establish the nature of the influence of temperature, pressure, flow rate and humidity of the vapor phase, as well as the speed and temperature of the cooling air on the efficiency of cooling hydrocarbon vapors in a tubular apparatus; we have
assembled an experimental setup, the schematic diagram of which is shown in the
Fig. 1. Schematic diagram of the experimental air cooling unit: 1 - heat exchanger-condenser with finned tubes; 2 - fan; 3 and 8 - manometer; 4 and 12 -
valves; 5 - safety valve for steam; 6, 9 and 11 - thermometers; 7 - volumetric meter of distillate consumption; 10 - tube-in-tube water tube heat exchanger; 13 - measuring container for collecting distillate; 14 - steam generator; 15 -volumetric gas flow meter; 16 - gas burner;
The pilot plant for air cooling of hydrocarbon vapors (Fig. 1) mainly consists of a steam generator 14, a heat exchanger-condenser with finned tubes 1, a tube-in-tube water tube heat exchanger 10, gas meters 15 and distillate 7 and measuring container 13 for collecting cooled distillate. The installation is equipped with instrumentation and shut-off valves to regulate the flow rate of heat carriers.
Heating steam is obtained in a steam generator 14 with a working volume of 27 liters by heating the initial heat carrier (water or gas condensate) to the boiling point, igniting natural gas using a burner 16. The flow rate of the gas supplied to the burner is set according to the readings of the volumetric meter 15 and is regulated by a valve 41 on the line, this sets the preset steam output of the generator.
The steam pressure in the steam generator 14 and in the heat exchanger-condenser with finned tubes 1 is measured with manometers. The temperature of the hydrocarbon vapor inlet to the heat exchanger-condenser 1 is measured by mercury thermometers 6 inserted into welded oil pockets. The temperature of the hydrocarbon vapor being cooled is measured by mercury thermometers 9, which are placed in welded oil pockets.
At the entrance of the heat exchanger-condenser, a water tube-in-tube heat exchanger 10 is installed, the temperature of the hydrocarbon distillate being cooled is measured by mercury thermometers 11 placed in welded oil pockets.
In the course of experiments, changes in the temperature of cooled hydrocarbon vapors, petroleum distillates, air and water in an experimental heat exchanger-condenser and a tubular water cooler were studied. At the same time, changes in the temperature of condensation of hydrocarbon vapors and cooling of distillates were analyzed depending on changes in temperature, flow rate and pressure of air and water.
During the experiments, the readings of the gas and distillate counter, the values of the temperature of the distillate, air and water at the control points of the apparatus included in the installation, as well as the pressure and temperature of hydrocarbon vapors in the steam generator were recorded.
During the experiments, the temperature of the liquid and vapor was measured using laboratory mercury glass thermometers of the TL-2 and TL-2M type according to TU 25-2001.003-88. The temperature of hydrocarbon vapors in the generator was measured with a manometric thermometer, and its overpressure was measured with DM05 manometers according to TU U33.2-14307481-031: 2005 and GOST 2405-88.
The main purpose of the experimental research was to study the processes of cooling hydrocarbon vapors and oil distillate fractions by air and water methods, to establish the effect of the physical properties of heat carriers and process parameters (temperature, pressure, flow rate and humidity) on the efficiency of heat transfer in the experimental air and water coolers.
This experimental setup makes it possible to conduct experiments on a comprehensive study of the cooling and heat transfer processes when heating oil and gas condensate feedstock with alternative heat carriers.
Content and results of research. The main purpose of the experimental studies was to study the cooling processes of hydrocarbon vapors and oil distillate fractions by air and water methods, to establish the influence of the physical properties of heat carriers and process parameters (temperature, pressure, flow rate and humidity) on the efficiency of heat transfer in the experimental air and water coolers.
During the experiments, we used fractions of oil and gas condensate supplied to the Bukhara oil refinery. Gas condensate used as a working fluid had a density of 751 kg/m3 and a viscosity of 1.066 mm2/s.
Experiments on the study of the cooling processes of hydrocarbon vapors and oil distillate fractions were carried out at a pressure of hydrocarbon vapors of 50, 100, 150, 200 and 250 kPa, an atmospheric temperature of 33-34 °C, its relative humidity of 56 % and a barometric pressure of 713-715 mm Hg. The volume of gas condensate poured into the steam generator was 10 liters. The air flow (cooling agent) speed was 3 m/s. The measurement of the controlled parameters of the process was carried out at each time interval equal to 2 minutes.
In the course of experiments, changes in the temperature of cooled hydrocarbon vapors, petroleum distillates, air and water in an experimental heat exchanger-condenser and a tubular water cooler were studied. At the same time, changes in the temperature of condensation of hydrocarbon vapors and cooling of distillates were analyzed depending on changes in temperature, flow rate and pressure of air and water.
During the experiments, the readings of the gas and distillate counter, the values of the temperature of the distillate, air and water at the control points of the apparatus included in the installation, as well as the pressure and temperature of hydrocarbon vapors in the steam generator were recorded.
During the experiments, the temperature of the liquid and vapor was measured using laboratory mercury glass thermometers of the TL-2 and TL-2M type according to TU 25-2001.003-88. The temperature of hydrocarbon vapors in the generator was measured with a manometric thermometer, and its overpressure was measured with DM05 manometers according to TU U33.2-14307481-031: 2005 and GOST 2405-88. The influence of the operating parameters of the process on the efficiency of heat transfer in an air cooler was studied in the pressure range from 50 to 250 kPa.
In fig. 2 shows the curve of the change in the cooling temperature of the gas condensate vapors in the tubes of the experimental air cooler over time at a pressure of 250 kPa. It can be seen from the graph that at 250 kPa the cooling temperature of hydrocarbon vapors in the cooler proceeds with a smooth decrease in temperature to a state of equilibrium.
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Fig. 2. Changes in the temperature of hydrocarbon steam over time in a tubular
air cooler at P = 250 kPa.
A similar picture of the change in the rate of decrease in the temperature of the vapors was observed at other values of their pressure.
In fig. 3. shows the curves of changes in the temperature of the distillate of gas condensate vapors over time in the experimental air cooler, at a pressure of 250 kPa. As can be seen from the figure, the temperature of the cooled distillate of the gasoline fraction rapidly decreases to 50 ° C within 100 minutes from the beginning of the experiment.
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Fig. 3. Changes in the temperature of the distillate of gas condensate vapors over time in a tubular air cooler at P = 250 kPa.
The duration of the cooling process for hydrocarbon vapors and their distillates was studied in order to assess the dynamics of the process in an experimental cooling apparatus. As you can see, the developed experimental setup is characterized by good dynamic properties.
References:
[1]. Калинин Э.К., Дрейцер Г.А., Ярхо С.А. Интенсификация теплообмена в каналах. - М.: Машиностроение, 1990. - 199 с.: ил. (Kalinin E.K., Dreitser G.A., Yarkho S.A. Intensification of heat transfer in the channels. - M .: Mechanical Engineering, 1990 .-- 199 p .: ill.)
[2]. Гоголин А.А., Данилова Г.Н., Азарсков В.М., Медникова Н.М. Интенсификация теплообмена в испарителях холодильных машин. - М.: Легкая и пищевая промышленность, 1982. - 224 с. (Gogolin A.A., Danilova G.N., Azarskov V.M., Mednikova N.M. Heat transfer intensification in refrigerating machine evaporators. - M .: Light and food industry, 1982 .-- 224 p.)
