MATERIAL BALANCE AROUND EVAPORATOR

Suppose MEG is concentrated from 19.73 % to 60 % in this long tube vertical falling film evaporator.

Feed:

H2O                            =99277KG

MEG                            =25508KG

DEG                            =4201KG

TEG                             =300KG

Product:

H2O                            =?

MEG                            =25508KG

DEG                            =4201KG

TEG                             =300KG

Total material out from evaporator= 25508 / 0.6

= 42513 kg

H2o at Outlet                           = 42513-25508-4201-300

= 12504 kg

H2O Evaporator                      = 99277-12504

= 86773 kg

D = D1+D2+D3                      =86773 Kg ________(1)

1st Effect:

ms λs                                       = FCP(T1 – T2) +  D1 λ2

Steam temp. Ts                        = 486 K

λs                                             =1886 kJ/kg

C_p                                            = 1.98 KJ/kg.k

m_s (1886)=129286(1.98)(455-468)+D1(202.2)

m_s = -1764.49 +D1(1.071)______(2)

2nd Effect:

D₁ λ₁    = (F-D1)Cp(T2-T1)+D2 λ2

λ₁                                 = 2020.2 kj/kg

λ₂                                 = 2179 kj/kg

C_p                                =4.23 kJ/kg

(2020.2)D₁ = (129286-D₁)*4.23*(405- 455)+D₂(2179)

D₁ = -15118.03+D₂*(1.205) ______(3)

3rd effect:

D₂ λ₂ = (F-D₁-D₂)C_p(T₃-T₂)+D₃ λ₃

λ₃                                            =2326 KJ/KG

λ₂                                            =2179 KJ/KG

C_p                                           =4.03 KJ/KG.K

(2179)D2 = (129286-D₁-D₂)*4.03*(350- 405)+D₃(2326)

From =1

D₃        = 86773-D₁-D₂

2179 *D₂ = (129386-D₁-D₂)(-221.65)+(86773-D₁-D₂)*2326

4283.35*D₂ = 173177756.1- 2104.35*D₁___________(4)

From = 3

4283.35*D₂ = 173177754.1 - 2104.35 *  (-15118.03+1.21*D2)

D₂        = 22194 kg/hr

From = 4

D₁           = 33927kg/hr

From = 1

D₃        = 33927 kg/hr

From = 2

ms        = 27931 kg/hr

Component	Mass (kg) IN	Mass % Inx	Mass(kg) OUT	Mass % OUT
Water	99277	76.8	12504	29.4
MEG	25508	19.73	25508	60.0
DEG	4201	3.25	4201	9.9
TEG	300	0.25	300	0.7
Total	129286	100.0	42513	29.4