Calculation of plate heat exchanger

Contents

Contents

Schematic symbols

1 Introduction

2 Description of the process diagram

3 Plate heat exchanger calculation

3.1 Process (thermal) calculation

3.2 Structural calculation

3.3 Hydraulic calculation

3.4 Mechanical calculation

4 Calculation of auxiliary equipment

4.1. Calculation of pumps

4.2. Capacity Calculation

5 Conclusion

List of literature

Applications

Schematic symbols

c - average heat carrier mass capacity, J/( kg· ° С );

F - heat transfer surface, m2;

G - mass flow rate of coolant, kg/s;

V - coolant volumetric flow rate, m3/s;

g - acceleration of free fall, m/s2;

K - heat transfer coefficient, W/( m2· ° С);

ΔР - hydraulic resistance, Pa;

Q - heat load, W;

w - coolant speed, m/s;

rz - thermal resistance of the contaminant layer, W/( m2· ° С);

t - temperature, ° С;

α - heat transfer coefficient, W/( m2· ° С);

ρ - density, kg/m3;

? - thermal conductivity, W/( m· ° С);

ξ - coefficient of local resistance;

Re is the Reynolds criterion;

Nu - Nusselt criterion;

Pr - Prandtl criterion;

Indexes

1 - coolant with higher average temperature (hot);

2 - coolant with lower average temperature (cold);

n - initial value; external size;

k is the final value;

st - wall;

pcs - connector;

Process Diagram Description

The scheme of production of alphamethylstyrene by catalytic dehydrogenation of isopropylbenzene is considered.

An iron oxide catalyst is used for the dehydrogenation process.

Mixture of fresh and return isopropylbenzene is supplied by pump H-1 through heat exchanger T-1 to mixing chamber of evaporator I-1. Evaporation in I-1 is carried out in a stream of water vapor (50 wt% of isopropyl benzene), due to which the boiling point decreases from 152.5 to 120 ° C. Evaporation is due to the heat of the contact gas coming from the T-2 superheater. Isopropylbenzene evaporated and heated to 150 ° C from the I-1 evaporator enters the T2 superheater, where it is overheated to 490 ° C due to the heat of the contact gas leaving the P-1 contact apparatus (reactor). Superheated vapors from the T-2 superheater enter the mixing chamber of the P1 contact apparatus, where they are mixed with superheated steam having a temperature of 675 ° C. The steam is superheated in the P-1 tube furnace of gradient type. The steam-gas mixture at the inlet to the reaction zone of the contact apparatus P-1 has a temperature of 590 ° C. Due to the endothermicity of the dehydrogenation reaction, the temperature at the outlet of the reactor is reduced to ~ 550 ° C.

The contact gas is cooled, giving its heat, in the T-2 superheater and in the I1 evaporator, after which it is supplied for after-cooling to the KU-1 recovery boiler. It is then fed to the water-cooled condenser cooler HC-1 in which the liquid hydrocarbons are partially condensed. Final condensation is performed in HK-2 condenser cooled with brine. Condensates from condensers XC1 and XC2 drain into settler E1, from where the hydrocarbon layer is fed through collector E-2 to dryer E3 filled with calcium chloride and then to be separated. Water layer from settling tank E-1 after additional settling is discharged to sewage system. Non-condensed hydrocarbon gases are sent to the gas network.

The dehydrogenation products are then subjected to rectification to recover alphamethylstyrene using a minimum number of columns.

Liquid hydrocarbons from the dehydrogenation unit by the H-3 pump are fed to the KR-1 distillation column to remove the benzene toluene fraction. The residue of KR-1 column is sent by N-4 pump for rectification to KR2 column, where unreacted isopropylbenzene is taken as rectification. The residue of column KR 2, which is a mixture of alphamethylstyrene and high boiling impurities, is pumped by pump H-5 to column KR-3 to separate a resin containing a certain amount of alphamethylstyrene. Alfamethylstyrene with purity of 99.6% is taken from the top from KR-3 column, and resin is taken from the bottom. The resin is sent to E-4 tank by means of N-6 pump and is periodically passed through KR-4 column for distillation of residual alphamethylstyrene. Alphamethylstyrene flows from the top of KR-3 and KR-4 columns are mixed and withdrawn from the installation to the goods park .

Rectifying columns have the standard binding which is turning on HK-3 fridges condensers - XK6 and boilers (reboilers) K-1 - K-4 [4, 5].

Conclusion

Based on the results of the project, the following tasks were solved:

1) Plate heat exchanger of demountable type R 0.6632K01 is calculated and selected as per GOST 1551887. The heat exchange surface area of the plate is 0.6 m2, the heat exchange surface area of the heat exchanger is 63 m3; number of plates - 108 pcs, heat exchange surface reserve - 21%. Hydraulic resistance of the device is not more than 6 kPa.

2) Auxiliary equipment selected:

- centrifugal pumps for giving of heat carriers in the heat exchanger - 120/80 G according to TU 3631042002176102012OAO Volgogradneftemash;

- horizontal cylindrical tanks for heat carriers with volume of 32 m3 - 1-32-1.6-1 as per TS 3683-101-0021729898.

3) Drawings completed:

- process scheme for production of alphamethylstyrene by catalytic hydrogenation of isopropylbenzene (A3);

- general type of plate refrigerator (A3).