INCREASING THE EFFICIENCY OF SHELL AND TUBE HEAT EXCHANGE DEVICES

ABSTRACT

This article discusses methods for increasing the efficiency of shell and tube heat exchangers, which are among the most widely used types of heat exchange equipment in industrial processes. The study analyzes factors influencing heat transfer performance, including flow arrangement, material selection, and fouling effects. Various design modifications, such as the use of baffles, surface enhancement techniques, and optimization of flow parameters, are considered to improve thermal efficiency. The results show that proper design optimization can significantly enhance heat transfer rates while reducing energy consumption and operational costs. The article discusses scientific research efforts to determine the optimal limits of the speed of movement of oil, gas condensate and their fractions in tubular heat exchangers and to improve the processing technology based on improving hydrodynamic regimes to increase heat exchange efficiency.

АННОТАЦИЯ

В данной статье рассматриваются методы повышения эффективности кожухотрубных теплообменников, которые являются одним из наиболее распространённых видов теплообменного оборудования в промышленности. Проведен анализ факторов, влияющих на теплопередачу, включая схему течения, выбор материалов и образование отложений. Рассмотрены различные конструктивные изменения, такие как использование перегородок, методы интенсификации теплообмена и оптимизация параметров потока. Результаты показывают, что правильная оптимизация конструкции значительно повышает коэффициент теплопередачи, снижая при этом энергозатраты и эксплуатационные расходы. Cтатье рассматриваются научные исследования, направленные на определение оптимальных пределов скорости движения нефти, газового конденсата и их фракций в трубчатых теплообменниках и совершенствование технологии их переработки на основе улучшения гидродинамических режимов для повышения эффективности теплообмена.

Keywords: heat exchange, mass flow, gas condensate, flow rate, oil, rod diameter.

Ключевые слова: теплообмен, массовый расход, газовый конденсат, расход, нефть, диаметр стержня.

INTRODUCTION

Heat exchangers play a crucial role in a wide range of industrial applications, including power generation, chemical processing, oil refining, and HVAC systems. Among the different types of heat exchangers, shell and tube heat exchangers are the most commonly used due to their simple design, reliability, and ability to operate under high pressure and temperature conditions. However, the efficiency of these devices can be limited by factors such as fouling, thermal resistance, improper flow distribution, and material constraints.

Improving the efficiency of shell and tube heat exchangers is essential for reducing energy consumption, minimizing operational costs, and enhancing overall system performance. Recent research has focused on various approaches to optimize heat transfer, such as the implementation of advanced baffle designs, use of surface enhancement techniques, and optimization of fluid flow parameters. Additionally, computational modeling and experimental studies have provided valuable insights into the thermodynamic and hydraulic behavior of these systems.

This paper aims to analyze the key factors affecting the performance of shell and tube heat exchangers and to propose effective methods for increasing their thermal efficiency. The study highlights both traditional and innovative techniques that can lead to significant improvements in heat transfer rates, contributing to more sustainable and cost-effective industrial operations.

METHODOLOGY

Research is being conducted in the world to develop effective technologies for the primary processing of hydrocarbon raw materials. One of the priority tasks is to develop technologies for improving the design of thermal devices for the processing of hydrocarbon raw materials on a global scale and obtaining products that meet the requirements of world standards for quality indicators. For this reason, it is becoming important to produce petroleum products whose environmental indicators have been improved by increasing the thermal efficiency of devices used in the primary processing of liquid hydrocarbons and reducing heat losses.

In the installation for increasing the active surface of the pipe at low raw material consumption, an additional rod is installed on the inner pipe of the heat exchanger.

To study the effect of the rod diameter on the change in the temperature of the heated raw material, the rods are made of stainless steel of different diameters. d₁=12 mm, d₂ =15 mm, d₃ = 18 mm, L = 2000 mm

Today, the lack of raw materials negatively affects the full functioning of many oil refineries. This leads to the use of thermal resources of the plant in an incomplete volume and to an increase in energy costs during the primary processing of raw materials.

The main solution to these problems is the full use of the thermal surfaces of the devices with the improvement of the hydrodynamic modes of the raw material flow. For this purpose, we used rods on the heat exchanger pipes. These rods increase the active heat exchange surface of the inner surface of the pipeline in the tubular heat exchanger. This allows the temperature of the raw material at the outlet of the device to increase.

Tables 3.1÷3.4 show changes in the temperature of the raw material at a constant density of the heat carrier depending on the flow rate of the raw material. The internal diameter of the heat exchange pipe d = 22 mm, the temperature of the raw material at the inlet to the heat exchanger t = 20 ^oC, the temperature of the heat carrier t = 120 ^oC.

 Table 1.

Change in the output temperature of the raw material depending on the rod diameter (G = 2 kg/min.)

Table 2.

Change in the output temperature of the raw material depending on the rod diameter (G = 6 kg/min.)

Table 3.

Change in the output temperature of the raw material depending on the rod diameter (G = 10 kg/min.)

From the data shown in tables 3.1÷3.4 it is evident that the oil temperature decreases from 70 to 55 °C with the increase in the flow rate, with the installation of the rod on the heat exchange pipe the output temperature of the feedstock increases significantly due to the increase in the active heat exchange surface and the creation of improved hydrodynamics. At G = 2 kg/min with the installation of a rod with a diameter of 10 mm in the pipe the temperature of the feedstock at the outlet from the pipe increases additionally by 2 °C. With the installation of a rod with a diameter of 12 mm the temperature of the feedstock increases by 5 °C, and with the installation of a 15 mm rod on the pipe the temperature of the feedstock increases by 9 °C. In all objects of study the output temperature also increases from 2 to 10 °C depending on the diameter of the rod.

Table 4.

Change in the output temperature of the raw material depending on the rod diameter (G = 14 kg/min.)

During the experiments, the hydrocarbon feedstock was heated by gas condensate vapors. The experiments were conducted at feedstock flow rates in the inner tube of the pilot plant of 2; 6; 10; 14 kg/min. These feedstock flow rate limits ensure the establishment of various hydrodynamic modes of its movement in the heat exchange tube.

The dependencies of the oil and gas condensate flow rate on the mass flow rate of the feedstock are given in Table 5

Table 5.

Raw material flow rate versus mass flow rate

It is evident from Table 3.5 that, with an increase in the mass flow rate of raw materials from 2 to 14 kg/min in a heat exchange tube with an internal diameter of 20 mm at Dt_ср = 50оС, the oil flow rate increases by 6.8 times, and the gas condensate flow rate by 6.96 times.

With the establishment of a different rod diameter in the tube, the oil and gas condensate flow rate increases (Fig. 3.3).

Figure 3.3. Oil flow rate dependences on mass flow rate and rod diameter

From Fig. 3.3 it is evident that with the installation of a rod with a diameter of 10÷15 mm on the heat exchange tube at oil flow rates of 2÷14 kg/min the flow rate increases by 6.8 times. The gas condensate velocity increases by 7 times.

RESULTS

With an increase in the liquid flow rate in the heat exchange tube the Reynolds criteria also change, characterizing the relationship between inertial forces and viscosity forces are given in Tables 3.6 and 3.7.

According to the data in Table 3.6, at the beginning of the experiments, when the oil mass flow rate is 2 kg/min the Reynolds number is 649 and a laminar liquid regime is observed. With an increase in the mass flow rate of oil through a pipe with a diameter of 20 mm, the Reynolds number increases by 6.82 times (Re = 4427) and a transient mode of motion is observed. With an increase in the mass flow rate of gas condensate from 2 to 14 kg/min, the Reynolds number value increases from 4800 to 33433. The intensity of the increase in the Reynolds number is 86%.

Table 6.

Dependence of Reynolds criteria on mass flow rate of raw materials

Table 7.

Dependence of the Reynolds criterion on the mass flow rate of raw materials and the rod diameter

From the data presented in Table 3.7 it follows that with an increase in the mass flow rate from 2 to 14 kg/min when installing a rod with a diameter of 10 mm, the Reynolds criterion for oil flow increases from 434 to 2954, and for gas condensate flow from 492 to 3446. With the installation of a rod with a diameter of 12 mm, the Reynolds criterion for oil flow increases accordingly by flow rates from 406 to 2762, and for gas condensate from 461 to 3231. When installing a rod in a pipe with a diameter of 15 mm, the Reynolds criterion for oil changes from 372 to 2532, and for gas condensate from 422 to 2954.

CONCLUSION

The obtained data show that with an increase in the diameter of the rod installed in the heat exchange tube, a decrease in the Reynolds number is observed. This is explained by the fact that with an increase in the diameter of the rod, the equivalent diameter of the channel decreases, the equivalent diameter is directly proportional to the Reynolds number. Therefore, with an increase in the diameter of the rod, the flow rate increases, and the Reynolds number decreases.

An experimental setup was assembled to study the effect of the mode of movement of heated oil in horizontal tubes of the heat exchanger.

The effect of mass flow rate on the flow motion mode is studied. With an increase in the mass flow rate of oil through a pipe with a diameter of 20 mm, the Reynolds number increases by 6.82 times (Re = 4427) and a transient motion mode is observed. With an increase in the mass flow rate of gas condensate from 2 to 14 kg/min, the Reynolds number value increases from 4800 to 33433. The intensity of the increase in the Reynolds number is 86%.

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