Eng3190 Process Operation and Management - Full Investigation Report

Chemical & Process Engineering

Faculty of Engineering and Physical Sciences

ENG3190 Process Operation and Management

FULL INVESTIGATION REPORT

REACTOR AND PHE1 ENEGRY BALANCE PROJECT

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Project Investigators:

Abstract

Plate heat exchangers can be used to achieve heat integration in a chemical plant by preheating cold water feed using a hot product stream. Plate heat exchangers have a stack of closely spaced thin plates, which are clamed together in a frame. The cold and hot fluids pass between alternative plates and plates are thin enough to allow heat transfer. They are cheaper to use and easy to maintain. One of the main aims of this project is to calculate the heat transfer co-efficient for this heat exchanger and analyse its variation with flow rate through the exchanger. The overall heat transfer co-efficient was calculated to be 200 ± 20 W m-2 C-1 with an efficiency of 54%.  The analysis of variation in heat transfer co-efficient with respect to flow rate gives a positive correlation.  The current heat exchanger was compared with the older exchanger and it was found the efficiency has been increased by approximately 2%.

The process uses external heat in the reactor vessel using a coil. The hot water passes through the coil to maintain the optimum temperature in the reactor for the required reaction to take place. This made of a thin copper tube and goes around the inside of the vessel. The heat transfer co-efficient for the coil-reactor arrangement is 1300 ± 50 W m-2 C-1.

An overall energy balance was conducted for both the above areas to verify and analyse the heat recovery from the overall process. The calculations and results for all the aims are given and analysed in detail in this project report.

Contents

Nomenclature

ρ = Density – kg/m3

µ^[1] = Viscosity – Ns/m2

K = Thermal Conductivity – W/m-k

Cp = Specific Heat Capacity – J/kg-k

t = Time – Seconds/Hours/Minutes

T = Temperature - °C

Q = Volumetric flow-rate – m3/s

Di = Internal Tube Diameter – m

Ai = Internal Coil Area – m

Tt = Thickness of Tube – mm

Do = External Tube Diameter – mm

Ao = External Coil Cross-sectional Area – m2

Dav = Average Coil Diameter – m

L – Length of Paddle – m

Nt = Number of turns for Coils

Dg = Gap between Coils – mm

H – Total coil Height – mm

Kw = Thermal Conductivity of Stainless Steel – W m-1C-1

Dc = Coil Width – cm

N – Number of Revolutions – Rev/s

U – Velocity through the line – m/s

Dr = Reactor diameter – m

Aht = Total Heat Transfer Area – m2

Xw/Kw = Heat Transfer Resistance due to Coil Wall – m2/C/W

Ri = Fouling factor coil side – W m-2C-1

Ro = Fouling factor reactor side – W m-2C-1

h = Film Coefficient – W m-2C-1

U = Overall Heat Transfer Coefficient - W m-2C-1

Pr = Prandtl Number

Re = Reynold’s Number

Nu = Nusselt Number

List of Figures

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