Transient Analysis of Heat Exchanger Networks in the Crude Distillation Unit of Port-Harcourt Refinery (original) (raw)

Pinch Analysis of Heat Exchanger Networks in the Crude Distillation Unit of Port-Harcourt Refinery

The pinch analysis of the heat exchanger networks in the crude distillation unit of the New Port-Harcourt refinery has been performed. This analysis is aimed at ascertaining the energy efficiency and operation of the heat exchangers used in preheating the crude. Process data of the heat exchanger networks (HEN) were collected to formulate a problem table and used in Aspen-Pinch ® software for pinch analysis of the networks. The software produced the composite and grand composite curves, the grid representation and target reports. From these, the minimum heating and cooling requirements of the entire network, the process streams not properly matched and the heat exchangers not properly placed were obtained. The analysis indicated that a total of 98916.1 KW hot utility, 8298.7 KW cold utility were not utilized within the network (poor process stream matching) and that ten heat exchangers were not properly placed. Hence the heat exchangers in the crude distillation unit need to be retrofitted to ensure adequate heat recovery, process to process integration and efficient energy utilization within the network.

Simulation of Fluid Flow and Heat Transfer Process in Heat Exchangers in Petroleum Industries

International Journal of Membrane Science and Technology

Heat exchangers are very useful equipment in a wide range of industries, therefore ?the analysis of the internal flow in them is very important. In this study, a heat exchanger is modeled to solve the flow and temperature field. Three ?turbulence models have been tested for first and second order discretization using ?two different mesh densities, and the results are as follows. The effects of different parameters on the internal conditions of the converter have ?been simulated. The temperature changes decrease in proportion to the reduction of ?the heat transfer coefficient in viscous fluids, and the Reynolds number is greater ?than the Parantel number. For the tube with constant wall temperature and shell inlet, the heat transfer ?coefficient, pressure drop values and heat transfer rate are obtained. In another part, it is shown that the stabilization time of the fluid temperature has a ?direct relationship with the heat capacity of the pipes, and that the performance of ?the tubu...

Mathematical Modeling of Industrial Heat Exchanger System

Applied Mechanics and Materials, 2012

In manufacturing and industrial fields used heat exchanger to control of temperature weather as a boiler or cooling system. This system is not stable as the temperature output can easily disturb by noise and other disturbance such as surrounding temperature. To improve the heat exchanger system performance, the mathematical model‘s needed. The heat exchanger mathematical model in this case is constructed using dynamic modelling based on real parameters of the heat exchanger. The simulation result shows almost similar trend of responses with the experiment result, it means they are can used as a model of the heat exchanger.

Analysis and operation of cooling water flows in a heat exchangers network

Korean Journal of Chemical Engineering, 1997

In general, the flow rates of cooling water flowing in a heat exchangers network should be measured for its operational purpose. However, it is difficult to install flow meters on every spot because of the financial and technical reasons. This work presents an explicit algorithm for determining the flow rates of cooling water flowing in the heat exchangers network in the chemical plant. An algorithm is also presented to obtain the desired flow rates of cooling water in each heat exchanger. In order to solve this problem, multivariable optimization techniques will be used to minimize the differences between the desired flow rates and the present cooling water flow rates which flows through the heat exchanger. The commercial computer program GAMS/MINOS which solves the nonlinear optimization problem is used. Numerical examples are presented to illustrate the scope of this work which can be handled with the formulation.

Modeling and Temperature Control of Heat Exchanger Process

2017

The main purpose of a heat exchanger system is to transfer heat from a hot fluid to a cooler fluid, so temperature control of outlet fluid is of prime importance. In this paper, firstly simplified mathematical model for heat exchanger process has been developed and used for the dynamic analysis and control design. Artificial neural networks (ANN) are effective in modeling of non linear multi variables so modeling of heat exchanger process is accomplished using optimized architecture of artificial neural network after that different controllers such as PID controller, feedback plus feed-forward controller and a ratio controller are developed to control the outlet temperature of a shell and tube heat exchanger. The main aim of the proposed controllers is to regulate the temperature of the outgoing fluid to a desired level in the minimum possible time irrespective of load and process disturbances and nonlinearity. The developed ratio controller has improve the overshoot from 1.34 to 0 ...

Thermohydraulic Simulation of Heat Exchanger Networks

Industrial & Engineering Chemistry Research, 2010

This paper presents a simulation scheme of heat exchanger networks considering thermal and hydraulic effects simultaneously. The determination of network temperatures is carried out together with the evaluation of flow rates and pressures along the network, considering head losses in heat exchangers and associated piping. The model encompasses two systems of equations: a network hydraulic model, composed by a nonlinear system of mass balances and fluid flow equations, and an energy model, represented by a linear system of energy balances and heat exchanger equations. The mathematical structure is based on a matrix representation of the network. The proposed model allows a more realistic analysis of heat exchanger networks where flow rates are constrained by limitations of hydraulic facilities. The utilization of the simulation scheme is illustrated by the analysis of a cooling water system.

On the modelling of heat exchangers and heat exchanger network dynamics using bond graphs

Mathematical and Computer Modelling of Dynamical Systems, 2018

Heat exchanger networks are important systems in most thermal engineering systems and are found in applications ranging from power plants and the process industry to domestic heating. Achieving cost-effective design of heat exchanger networks relies heavily on mathematical modelling and simulation-based design. Today, stationary design calculations are carried out for all new designs, but for some special applications, the transient response of complete networks has been researched. However, simulating large heat exchanger networks poses challenges due to computational speed and stiff initial value problems when flow equations are cast in differential algebraic form. In this article, a systems approach to heat exchanger and heat exchanger network modelling is suggested. The modelling approach aims at reducing the cost of system model development by producing modular and interchangeable models. The approach also aims at improving the capability for large and complex network simulation by suggesting an explicit formulation of the network flow problem.

Transient Behaviour of Heat Exchangers Under Inlet Perturbations

Proceedings of the 4th World Congress on Momentum, Heat and Mass Transfer, 2019

The aim of this investigation is to characterize the transient performance of different heat exchangers for their design and efficient control. This paper explored the effect of inlet mass flow rate and temperature step variations on the dynamic response of a conventional and a minichannel heat exchanger. The work was also extended to include a comparison between these two heat exchangers when both subjected to sudden changes in the liquid inlet conditions. A comprehensive, well-equipped, and large-scale experimental setup was designed and assembled to examine the thermal performance of different heat exchangers under steady and transient changes. At the early stage of a step change, the influence of changing mass flow and inlet temperature of the hot fluid on the response time is found significant while, this effect diminishes as the system approaches steady state. The hot liquid inlet conditions change of mass flow and temperature have more significant effect on the minichannel liquid outlet temperature when compared to the conventional heat exchanger. The reported results can find an application in the design and selection of a cross flow heat exchanger used in thermal management systems such as in automotive industry where compact heat exchanger is required for size and weight reduction.

Identifying of Unsteady Performance of Oil to Water Heat Exchanger Integrated with Process

International Journal of Heat and Technology, 2022

There are many approaches by which the heat exchanger can be modeled depending on how much information is available to start with. Grey-box model represents one of these approaches which is considered in the present study to modeling the unsteady operation heat exchanger. The available measurements of an unidentified heat exchanger integrated with a process involving oil circulation were statistically analyzed to extract the information that could aid in its identification. The proposed heat exchanger system included a hot oil stream coming from the thermal unit process and cooled by a cold-water circuit. The objective of this study is to develop a grey box model for the unspecified heat exchanger with a suitable nonlinear state-space structure and solved numerically using MATLAB-19 software and engineering equation solver (EES). Suitable parameters included oil and water inventories, heat addition, and conductance divisor factor are chosen to fully identify the heat exchanger from measured temperatures and flow rates. The parameters used to identify the oil process included the oil mass inventory within the process and the quantity of heat added. While for the heat exchanger; oil, water, and solid thermal masses were determined along with a conductance divisor to close its model. The results revealed that, comparing the model output with the measured data was satisfactory. The effect of 10% increment in the oil process heat as external excitation on a heat exchanger can only be controlled by water and oil flow rates and any fluctuation in inlet water temperature is insignificant and considered as a noise disturbance. An increment of 19% in the oil flowrate with unchanged water flowrate resulted in an increase in oil outlet temperature by about 4%. applying a noise of about ±10% on inlet water temperature to the system resulted in insignificant effects on the oil temperatures, and therefore it could be considered as uniform temperature. An effective control system to manage the heat exchanger and therefore the process can be designed according to the predictions of changing the water and oil flow rate responses.

Modelling and Simulation of Heat Exchanger with Strong Dependence of Oil Viscosity on Temperature

Fluids

The heating of oil and oil products is widely used to reduce energy losses during transportation. An approach is developed to determine the effective length of the heat exchanger and the temperature of the cold coolant (oil) at its outlet in the case of a strong dependence of oil viscosity on temperature. Oil from the Uzen field (Kazakhstan) is considered as a heated coolant, and water is considered as a heating component. The method of the log–mean temperature difference, modified for the case of variable viscosity, and the methods of computational fluid dynamics (CFD) are used for calculations. The results of the numerical calculations are compared with the data obtained on the basis of a theoretical approach at a constant viscosity. When using a theoretical approach with a constant or variable viscosity, the heat transfer coefficients to cold and hot coolants are found using criterion dependencies. The Reynolds-averaged Navier–Stokes (RANS) and a turbulence model that takes into ...