A High Efficiency Energy Conserving Multi Stage Evaporator Cum Water Recycle Plant (100 C)

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FORM-2
THE PATENTS ACT ,1970
(39 OF 1970)


COMPLETE SPECIFICATION (SEE SECTION 10)
A HIGH EFFICIENCY ENERGY CONSERVING MULTI STAGE EVAPORATOR CUM WATER RECYCLE PLANT. (100°C)
ATRE ASHOK DATTATRAYA ,
'Pushpa Heights', 1st floor, Bibwewadi Corner, PUNE-411 037. Maharashtra State, India
Indian Citizen

- 7 JUL 2000
Following specification (particularly ) describes the nature of invention and the manner in which it is to be performed:-
GRANTED

This invention relates to a high efficiency energy conserving multi stage evaporator cum water recycling plant using instant steaming (IBR/NONTBR) steam boiler. More particularly high efficiency energy conserving multistage evaporator cum water recycle plant for effluents/waste water.
In known multistage evaporator cum water recycle plant having following features :-
1) vacuum is applied in last stage condenser and total system is under vacuum.
2) Only partial degassing is done. This results in tremendous foaming and process destabilization.
3) IBR steam boiler used. Therefore a certified boiler attendants is required. The annual boiler inspection is to be carried out. During annual inspection boiler is kept out of operation unless a stand by boiler is made available.
4) Efficiency of evaporation is low.
With these features of known multistage evaporator plant following drawbacks exist.
1) As evaporation system is operated under vacuum it requires perfect sealing arrangements.
2) Due to partial degassing of feed water, the dissolved gases present inside feed water could not be removed. This results in tremendous foaming and process destabilization.
3) Use of IBR boiler required certified boiler attendant and annual inspection. During boiler inspection stoppage of plant.
4) Due to low evaporation efficiency running cost of plant.
It is object of the present invention to provide a high efficiency energy conserving evaporator cum water recycle plant working under pressure, having on line degassing system, and operatable on NON-IBR instant steaming boiler.

1. Accordingly the present invention provides A High Efficiency Energy conserving
Multi stage Evaporator cum water recycle plant comprising : i) number of falling film evaporator, steam heated, having steam inlet and steam
outlet with inlet for feed water and an outlet for condensate; ii) the said outlet of steam of earlier stage connected to steam inlet of next stage; iii) the said inlet of feed water provided with three way divertor valve, and said outlet
of condensate connected to individual condensate heat exchanger; iv) a feed water tank provided to receive preheated feed water from the boiler
economizer, heat exchanger heated by waste steam and condenser heat exchanger
of last stage of falling film evaporator; v) the said feed tank provided with heating means by steam to raise the temperature
of feed water to 100°c and adequate gas release area provided to release dissolved
gases; vi) pipe means to supply said heated feed water to first stage falling film evaporator
provided passing through last stage said individual condensate heat exchanger to
first stage individual condensate heat exchanger; vii) said all individual condensate heat exchanger outlet made common to-collect
distilled water and store the same.
Invention is described with reference to accompanying drawing wherein Figure 1 shows plant layout of high efficiency energy conserving multistage evaporator cum water recycling plant according to invention.
Now referring to the figure of accompanying , the evaporator comprises number of falling film evaporators. In the figure seven set of falling film evaporators fl, f2, O, f4, f5, f6, f7 are provided. The each of the falling film evaporator is provided with three way valve 12 to supply feed water there in. The water level in the said falling film evaporator is maintained with the help said three-way divertor valve 12. For maintaining water level inside the said evaporator level indicator cum transmitter 15 is provided. A steam inlet and an outlet are provide to each of the falling film evaporator. The feed water flows from inside of the tube in form of a thin film.

The steam as a heating media is supplied on the out side of the said tube under pressure. The steam generated in falling film evaporator is provided with moisture separator 13 for removing the water from the wet steam and thus dried said steam is supplied to next falling film evaporator. There is also provide outlet for condensate in each of falling film evaporator. The each of the said condensate outlet is connected to an individual condensate heat exchanger through which feed water is passed for raising the temperature by Utilising heat of condensate. In the figure said condensate heat exchanger are indicated by numerals 5 to 10. The outlets of said all condensate heat exchangers are made common to collect distilled water and send to storage. The feed water from feed tank is supplied condensate heat exchanger 5 by means of circulation pump. And next same is passed through condensate heat exchanger 6. Similarly it taken last condensate heat exchanger 10. The out let of condensate heat exchanger 10 is connected to first falling film tube evaporator f-.lthrough two way valve. The steam supply to the first falling film evaporator is supplied from boiler. The outlet steam from the steam outlet of the first falling film evaporator f-1 is supplied to next falling film evaporator f-2. Similar arrangement is made for third f-3, forth f-4, fifth f-5, sixth f-6 and seventh f-7. After third stage of falling film evaporator the part steam coming out of outlet is fed to thermo-compressor as a secondary steam and motive steam at required high press to get steam at required pressure which is fed to first stage. The separated water from moist steam is also taken out with help circulation pump 14 and supplied to next stage falling film evaporator through three way divertor valve. Thus feed is concentrated partially. The boiler economizer is used to heat feed water. In the figure 1 there is shown two economizers of boiler 1 & 2 provided to heat feed water through pipe line p-1. Also the feed water is heated through condenser 3 which is heated by waste heat of last stage waste steam and condensate heat exchanger 4 which is heated by the condensate of last stage of falling film evaporator. The heated feed water is taken to feed tank 11. The said feed water tank is provided with steam heating to raise the temperature of feed water to 100° c to remove dissolved gases. The said feed water 11 tank is also provided with adequate gas release area and continuous modulation of temperature and level control system.

Details of component parts of figure 1:-Boiler economizers 1&2, Feed water tank 11,
Heat exchanger heated by waste heat of evaporator 3, Heat exchanger heated by last stage condensate 4, Condensate heat exchangers 5to 10, Three way divertor valve 12, Falling film evaporators fl to f7, Moi sture separator 13, Circulation pump 14, Water level indicator cum transmitter 15, Temperature indicator 16, Thermo-compressor Tc Operation of plant: -
1). Feed is preheated with the help of waste heat available in boilers economizers land 2, condenser 3 and condensate heat exchanger 4 up to 90° c to 95° c.
2) Feed is further heated up to 100°c in feed tank 11 to remove dissolved gases completely. Feed tank is provided with adequate gas release area and continuous modulation temperature and level control.
3) Waste water /feed is feed to first stage falling film evaporator with help of feed pump. The feed flows from inside of the tubes in very thin film. The steam as a heating media is supplied on tube from out side at required pressure. The heated feed gets collected at the bottom of the evaporator where steam gets separated. The steam then supplied to next stage through high efficiency moisture separator. The condensate from the shell side pass through condensate heat exchanger to pre heat the feed and collected in distilled water tank. The level indicator cum controllers are installed on each stages to maintain constant level inside evaporator with help of three way divertor valve. Partially concentrated feed is transferred to next the stage where the

above process is repeated. Part of steam coming out of 3rd stage is fed to thermo-compressor as a secondary steam and motive steam at required high press to get at required pressure which is feed to the lst stage evaporator. Steam generated in last stage is passed through condenser to preheat the incoming feed and concentrated feed is drain out or can be treated with available presmud.
The number of stages range from 1 to 30 depending on the water evaporation capacity and application. Advantages:
i) Highest evaporation as per following

No. of stage Evaporation efficiency kg/ kg of motive steam
3 4kg/kg
5 9kg/kg
7 13kg/kg
ii) Continuos modulation of temperature and level parameters. Due to this plant is
capable for accepting reasonable variation in feed water, iii) Fully automatic, complete degassing of above 100° c before entry to 1ststage of
multistage evaporator.
I Claim:-
1 A High Efficiency Energy conserving Multi stage Evaporator cum water
recycle plant comprising : i) number of falling film evaporator, steam heated, having steam inlet and steam
outlet with inlet for feed water and an outlet for condensate;
ii) the said outlet of steam of earlier stage connected to steam inlet of next stage; iii) the said inlet of feed water provided with three way divertor valve and said outlet
of condensate connected to individual condensate heat exchanger;

iv) a feed water tank provided to receive preheated feed water in the boiler
economizer, heat exchanger heated by waste steam and condensate heat
exchanger of last stage of falling film evaporator; v) the said feed tank provided with heating means by steam to raise the temperature
of feed water to 100° c and adequate gas release area provided to release dissolved
gases; vi) pipe means to supply said heated feed water to first stage falling film evaporator
provided passing last stage said individual condensate heat exchanger to first
stage individual condensate heat exchange; vii) said all individual condensate heat exchanger outlet made common to collect
distilled water and store the same.
2 A plant as claimed in claim 1 wherein said outlet of falling film evaporator provided with moisture separator before supply to next stage said evaporator.
3 A plant as claimed in claim 1 and 2 wherein said outlet of steam moisture separator every intermediate stage coupled to a thermo-compressor to take out part steam for raising of pressure to the value of first stage.
4 A plant as claimed in claim 3 wherein the said intermediate stage is any stage depending upon number of stages.
5 A plant as claimed in claims 1 to 4 wherein a circulation pump provide to supply condensed steam water to falling film evaporator through the said three way divertor valve.
6 A plant as claimed in claims 1 to 5 wherein the said falling film evaporator provided with level indicator cum transmitter and PID controller maintaining level therein.
7 A plant as claimed claims 1 to 6 wherein pump means provided to supply feed water to the said boiler economiser, waste steam heat exchanger and condensate heat exchanger for preheating.
8 A process for recycling of waste water using the plant of claims 1 to 7 comprising steps of:
i) preheating waste /feed water in the boiler economizer , waste steam heat exchanger and condensate to the temperature of 90° c to 95° c;

ii) the said preheated feed waste water is collected in a feed tank and further heated
to temperature of 100° c to release dissolved gases;
iii) the said heated feed water is passed through the all the said individual condensate heat exchangers from the last stage said heat exchanger to the first stage said heat exchanger to recover heat from the said condensate;
iv) said feed water of step (iii) is supplied to first stage falling film evaporator through three-way divertor valve, and steam at required high pressure through thermocompresser is injected at inlet of said first stage evaporator and outlet steam is injected to next stage evaporator;
v) the codensate from each of said evaporator is passed through said condensate heat exchanger and outlet of all the said heat exchanger is made common to collect distilled water.
9) A process as claimed in claim 8 where in the part of outlet steam at intermediate stage is passed through the thermo-compressor to raise the pressure of steam to the initial pressure.
10) A High Efficiency Energy conserving Multi stage Evaporator cum water recycle plant as claimed in claims 1 to 8 and as here in described with reference to figure of accompanying drawing.
Dated this 30th Day of June,2000

( M.D.BHATE)
AGENT FOR APPLICANT

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