Titanium Tube Evaporators Case In Multistage Flash (MSF)

Titanium tube evaporators are a type of heat transfer device used to evaporate fluids in a variety of applications. It is designed with a bundle of titanium tubes, through which a hot fluid is circulated to heat and evaporate the fluid inside the tubes. The evaporated fluid is then condensed, typically using a separate heat exchanger, and the process is repeated. It is commonly used in a wide range of industries, including chemical processing, food and beverage processing, and HVAC systems. They are often used to concentrate or purify a fluid, such as in the production of concentrated juices or dairy products. We like to share the case of titanium in multistage flash (MSF) evaporators.

TECHNICAL SPECIFICATION

A

-BRINE HEATER TYPE:- Cylindrical shell and straight tube type

No of passes:- 1

Fluid:- Shell side Heating steam

Tube side Recycle brine

Design temp. Shell side 100 deg.C

Tube side 100 deg.C

Design press. Shell side 3.45 Bar. G

Tube side 10 Bar. G

Overall H.T.C 2,139 w/m2/deg.K

Heat transfer area 3,013.31 sqr. meter

No of tubes 2,222 pcs

Pitch 40 mm triangular

Tube size (mm) 32.0(O.D) x 30.73(I.D)x 0.635(thick) x 13,720(L)

Distance (between tube plates) 13,492 mm

Operating temp.

Recycle brine Inlet 84.85 deg.C

Recycle brine Outlet 90.56 deg.C

Heating steam Inlet 100.0 deg.C

Condensate outlet 95.0 deg.C

Operating flow Recycle brine 12,750 Ton (metric )

Heating steam 120.6 Ton (metric)

Hydraulic test press. Shell side 5.2 Bar. G

Tube side 15 Bar. G

B.

EVAPORATOR TYPE:- Cross tube multi-stage flash type

No of stages Heat recovery 19

Heat rejection 3

Total 22

Design temp.

Flash chamber Recovery 94 deg.C

Rejection 49 deg.C

Tube side Recovery 88 deg.C

Rejection 43 deg.C

Design pressure Flash chamber side 1.38 Bar. G

Tube side Recovery 10 Bar. G

Rejection 4.5Bar.G

Heat transfer area

Heat recovery section 65,930 sqr. meter

Heat rejection section 8,738.4 sqr. meter

No of tubes Heat recovery section 44,517 pcs

Heat rejection section 6,294 pcs

Dist.betn tube plts

Heat recovery section 14.732 meter

Heat rejection section 14.732 meter

Tube size (mm) Recovery 32.0(O.D) x 30.37 (I.D) x 0.635 (thick)

Rejection 30.0(O.D) x 28.73 (I.D) x 0.635 (thick)

Oprtng flow rate

Recycle brine 12,750 ton

Blowdown 1,682 ton

Cooling water 11,267 ton

The following combination of materials has been used for the construction of evaporators:

BRINE HEATER

SHELL: CARBON STEEL JIS G 3106 SM 41 A

WATER BOX: ALUMINUM BRONZE JIS H 3100 C 6161P

TUBE: TITANIUM ASTM 338

TUBE PLATE: ALUMINUM BRONZE JIS H 3100 C 6161P

TUBE SUPPORT: STAINLESS STEEL SUS 316 L

IMPING. PLATE: STAINLESS STEEL SUS 316 L

CATH. PROT NI-IRON ALOY 9/91 %

EVAPORATOR

STAGES 1,2,3&22 (All internal surfaces ) SUS 316L CLADDED

STAGES 4 ~11 Front and rear Carbon steel sus 316 cladded

Floor and side walls Carbon steel JIS G 3106, Coated with epoxy resin

STAGE 12 ~ 22 Floor and side walls Carbon steel JIS G 3106

25.4 mm above the top of the demister Coated with epoxy resin

FLASH BOX STAINLESS STEEL 316 L

WEIR

BRINE ORIFICE 

DIST.TRAY

DIST. ORIFICE

TUBE TITANIUM ASTM B338

TUBE PLATE ALUMINUM BRONZE JIS H 3100 C 6161P

TUBE SUPPORT NAVAL BRASS JIS H 3100 C 4640

WATER BOX ALUMINUM BRONZE JIS H 3100 C 6161P

CATH. PROT.

STAGE 1~11 SPECIAL NI-IRON ALLOY 9/91 %

STAGE 12-22 PURE IRON

OPERATING METHODS

During the entire period of the evaporator operations, the conventional operation methods as

recommended by the plant manufacturer in the O&M manuals have been followed. Unit startup

Steps include;

- Filling the evaporator with seawater

- Start-up of re-circulation pump

- Creation of vacuum by hogger ejectors up to 0.25 barA

- Heating of brine maintaining recommended temperature and flow gradients

- Change over of vacuum system from hogger to normal holding ejectors

- Increase in steam, brine, make-up & chemical doses to bring the evaporator to full load

Case:

It is widely used in the desalination industry, and one of the most common desalination processes where they are used is the multistage flash (MSF) process. In the MSF process, seawater is heated and pressurized and then fed into a series of titanium tube evaporators, which are arranged in stages. Each stage has a lower pressure than the previous stage, and as the seawater flows through the tubes, it evaporates and leaves behind salt and other impurities. The resulting steam is then condensed and collected as fresh water. It is well-suited for use in the MSF process due to their excellent corrosion resistance and high thermal conductivity, which ensure efficient heat transfer and evaporation. Additionally, titanium material is able to withstand the high temperatures and pressures required for the MSF process.

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