Description: FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
“MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass ”
2. APPLICANT:

(a) Mazda Limited
(b) India
(c) Mazda House,
Panchvati 2nd Lane,
Ambawadi,
Ahmedabad-380006,
Gujarat, INDIA

3. PREMABLE TO THE DESCRIPTION
? COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed.

Field of invention
The present invention relates to a treatment of waste water and more particularly it relates to MEE (multi-effect evaporation) having MVR (mechanical vapor recompression) coupled TVR (thermal vapor recompression) & PHE (plate calandria) along with SLT (shell & tube) calandria with TVR (thermal vapor recompression) for MVR (mechanical vapor recompression) bypass to remove all the dissolved liquids and solid wastes and offers beneficial and economical method which will reduce the operating as well as capital cost.

Background of the invention
Treating waste water disposed from the industries which contain high TDS (total dissolved solids) and high COD (chemical oxygen demand) is a difficult and a challenging task for all the industries as this task conventionally occur in long as well as costly process. Separation of solids from water and other liquids is required in various industrial processes. As we all know that suspended solids can be easily separated by filtration, decantation and various other methods. However, separation of dissolved solids from waste water and other liquids require energy intensive methods. Conventionally, commercial methods used for separating dissolved solids from waste water and other liquids can be separated by membrane-based and thermal methods.
Membrane-based methods are based on reverse osmosis principle and require a semi-permeable membrane to separate pure liquid and liquid containing dissolved solids. In this method, under normal circumstances, pure liquid from side with pure water moves towards the liquid containing dissolved solids side because of osmosis. However, when liquid containing dissolved solids is pressurized to pressures exceeding the osmotic pressure, the pure liquid from the liquid containing dissolved solids moves through the semi-permeable membrane towards the pure water side leaving concentrated solution on the side with liquid containing dissolved solids. This process is known as reverse osmosis. As the concentration of liquid containing dissolved solids increases, the osmotic pressure also increases this requiring higher pressure to push pure water from the side with liquid containing dissolved solids through semi-permeable membrane to the side with pure water. For separating sea water containing 3% NaCl by weight, the osmotic pressure reaches very high value i.e. 6%-7% NaCl by weight making it practically impossible to separate beyond 6%-7% concentration by weight of NaCl. This concentrated saline water poses environmental problems when disposed-off in rivers or lakes or in sea. However, before the process of treating sea water by reverse osmosis, pretreatment is applied to avoid fouling of semi-permeable membrane which is very costly.
Another method of treating waste water is a thermal method which includes thermal evaporation, freezing and gas hydrate-based water treatment used to separate pure water or pure liquid from saline water or from liquid containing dissolved solids. Thermal evaporation based systems are in use commercially with freezing-based systems found to be techno-commercially non-viable and gas hydrate-based water treatment systems not been tested extensively. Various modifications have been proposed in thermal evaporation systems to decrease operating cost while retaining the simplicity of the system. However, it has been found to be very expensive both operationally and infrastructure-wise to use various modifications of evaporation-based systems like multi-effect evaporation (MEE) to desalinate water or separate pure liquid from liquid containing dissolved solids till complete crystallization of dissolved solids. There are mainly three types of system which are widely used in India to treat the high TDS waste water. They are multi effect evaporation, multi-effect evaporation with thermal vapor recompression and evaporation technology with mechanical vapor compression (MVC).
In the multi-effect evaporation device, the steam generated by the new steam heating the first effect does not enter the condenser, but is reused as the heating medium of the second effect. This effectively reduces fresh steam consumption by approximately 50%. Reusing this principle further reduces fresh steam consumption. The maximum heating temperature of the first effect and the minimum boiling point temperature of the last effect form a total temperature difference, which is distributed in each effect. As a result, the temperature difference per effect decreases as the number of effects increases. Therefore, in order to achieve the specified evaporation rate, the heating area must be increased. Preliminary estimates show that the effective heating area increases proportionally with the number of effects, so that the steam savings gradually decreases while the investment cost increases significantly.
In multi effect technology with thermal vapor recompression, only a portion of vapor from an evaporator can be compressed in a thermo compressor with the remainder condensed in the next-effect calandria or a condenser. The thermo compressor is normally used on a single-effect evaporator or on the first effect of a double -effect evaporator to reduce energy consumption. Thermal recompression is more applicable to low boiling point rise liquids and low to moderate differential temperatures in the calandria to minimize the compression ratio. The main drawback associated with this system is that the MEE requires steam and hence, day by day the steam cost is increasing.
In mechanical vapor compression (MVC) evaporator heat is transferred to the circulating stream by condensing vapor from the compressors. The mechanical vapor compression which increased the temperature and pressure of the vapor required significantly less energy than producing steam at the desired conditions from liquid water. In mechanical vapor compression evaporator, the vapor generated from the circulating stream contains a large amount of energy in the form of latent heat. The main problem associated with this technology is that this vapor cannot be utilized as it is because it is at the same temperatures as the boiling waste water. A higher temperature will be required to allow the main calandria to function properly. Also, mechanical vapor compression required huge power and when there is high concentration of TDS in the waste water, boiling point elevation will increase and accordingly power and capital is increased.
Various prior arts have been disclosed describing the treatment of waste water by membrane-based method and thermal method. The prior art document CN101891330 (B) discloses a waste water treatment system and a waste water treatment method for a power plant. The system comprises a pre-treatment system, evaporation and crystallization system, an ammonia nitrogen treatment system and a membrane condensation and treatment system, wherein the pre-treatment system is connected to waste water of the power plant. This system has a drawback that it operates on reverse osmosis principle and pre-treatment process to treat waste water which led to huge consumption of power as well as it requires huge operating and capital cost. This system also has a limitation of manual operation.
Another prior art document CN104326612 (A) also discloses a method for recovering salt from a waste water treatment system. The waste water is subjected to primary treatment by virtue of the processes such as oxidation, adsorption, precipitation, filtration, softening and CO2 removal. The main drawback associated with this conventional method is that, it undergoes complex and very lengthy process. Also, this system is non-reliable for treating waste water containing high TDS and COD and requires high running and capital cost.
Another commonly used subsequent advanced treatment methods for high-concentration industrial wastewater and/or desulfurization wastewater is seed method. This process is to add crystal nucleus slurry to establish and maintain calcium sulfate crystallization during the brine circulation process of the evaporator. Evaporation of most of the water is done in the brine concentrator, which discharges about 20% TDS of brine, which is further concentrated and evaporated in the crystallizer to concentrate the brine into a fairly thick crystalline slurry and mother liquor (about 50% total solids). The crystallization slurry and mother liquor are dried in the drying and atomizing chamber, and finally collected in the form of dry powder and sent to the disposal site for burial. The seed crystal method has a good effect on wastewater treatment with low content of calcium ions and sulfate ions in an industry or conventional water system, and the cleaning cycle is acceptable, but for a system that is already supersaturated. When the desulfurization wastewater enters into the preheater, scale will soon occur due to the temperature rise and phase change. Once the scale is formed, it will be very difficult to clean, affecting the operation and service life of the equipment.
In order to overcome the above said problem of conventional system and methods that require high operating and capital cost with huge consumption of live steam and power, treating waste water system needs an innovative solution. The present invention provides a game changing solution. The process is exhaustively described in the detailed description.
Object of invention
The principle object of the present invention is to MEE (Multi-effect evaporation) having MVR (mechanical vapor recompression) coupled TVR (thermal vapor recompression) & PHE (plate calandria) along with SLT (shell and tube) calandria with TVR (thermal vapor recompression) for MVR (mechanical vapor recompression) bypass.
The main object of the present invention is to provide a system for treatment of waste water which is the combination of MVR and TVR along with plate type and shell & tube calandria will result in reduction of operating and capital cost.
Another object of the present invention is to provide a system for treatment of waste water which provides bypass mechanism during maintenance of MVR (mechanical vapor recompression) and thus, makes the process more reliable.
Yet another object of the present invention is to provide a system for treating waste water which provides an advantageous choice to the industry.
Still another object of the present invention is to provide MEE having MVR coupled TVR & PHE (plate calandria) along with SLT (shell and tube) calandria with TVR for MVR bypass system which will overcome the problem of the boiling point elevation, reduced live steam consumption, increased the efficiency of the system and reduced the environmental pollution thus, makes the process more economical and beneficial for the industry use.
One more object of the present invention is to provide MEE having MVR coupled TVR & PHE (plate calandria) along with SLT (shell and tube) calandria with TVR for MVR bypass which will overcome the drawbacks of the conventional used systems and will attract toward the zero liquid discharge technology.
Summary of the invention
The present invention discloses a feed tank fluidly communicated with a pair of pre heaters through the feed pump, said pair of pre-heaters connected with the vapor liquid separator, a mechanical vapor recompressor is configured to collect the vapor discharge from the vapor liquid separators, one end of the thermal vapor recompressor is connected with the MVR and second end of the TVR is operatively connected with the shell and tube calandria, wherein liquid from the vapor liquid separator is configured to circulate from the vapor liquid separator to plate type calandria though one of the transfer pump; a partially concentrated feed from the transfer pump is circulated from plate type calandria to the vapor liquid separator through transfer pump; a partially concentrated feed from the transfer pump circulated from the shell and tube calandria to vapor liquid separator through a recirculation pump, plate type calandrias are configured to utilize the vapor from the mechanical vapor recompressor and shell & tube calandria is configured to utilize the discharged steam from thermal vapor recompressor; second thermal vapor recompressor is configured to operate as a bypass mechanism when the mechanical vapor recompressor is in maintenance resulting in continues operation and reducing operating & capital cost and increased reliability of the system.
Brief description of drawings
Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.
Figure 1 depicts a schematic view of an improved system waste water treatment according to the present invention.

Detailed description of the invention
Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompany drawings. The invention is capable of other embodiments, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.
The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.
It is to be understood that the term "comprises" and grammatical equivalents thereof are used herein to mean that other components, ingredients, steps, etc. are optionally present. For example, an article "comprising" (or "which comprises") components A, B, and C can consist of (i.e., contain only) components A, B, and C, or can contain not only components A, B, and C but also contain one or more other components.
For avoidance of doubt, in the context of the description, it is to be understood that the term “MEE” refers to multi effect evaporator, “MVR” refers to mechanical vapor recompressor, “TVR” refers to thermal vapor recompressor, “PHE” refers to plate calandria, “SLT” refers to shell and tube calandria, “TDS” refers to total dissolved solids and “COD” refers to chemical oxygen demand.
It is also to be understood that a system of MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass is aimed to treat waste water which contain high TDS and COD. The waste water contain high TDS and COD is treated under appropriate conditions with several hours of timing and temperatures to make it result in increased efficiency of the system, reduction in live steam consumption & environmental problem, minimization of operating & capital cost and overcome the problem of the boiling point elevation.
The present invention discloses MEE having MVR coupled TVR & PHE along with SLT calandria with TVR for MVR bypass which comprises a feed tank (FT 01) configured to collect the waste water, a pair of pre heaters (HE 01) (HE 02), a pair of plate type calandria (E 01) (E 02), vapor liquid separators (VLS 01), (VLS 02) and (VLS 03), a mechanical vapor recompressor (MVR), a pair of thermal vapor recompressor (TVR 01) (TVR 02), a shell and tube type calandria (E 03), a surface condenser (SC 01), a pair of flash tank (FLT 01) (FLT 02); each vapor liquid separator configured to separate vapor
Now referring to Figure 1, a feed tank (FT 01) is configured to collect feed (a waste water is to be treated) from feed-in line, the pair of pre heaters (HE 01 and HE 02) are configured to preheat the feed-in (waste water) which is pumped from the feed tank (FT 01) through a feed pump (FP 01). Said pair of pre-heaters (HE 01) (HE 02) are connected with the vapor liquid separator (VLS 01). The (MVR) is configured to collect the vapor discharge from the (VLS 01), (VLS 02) and (VLS 03). The one end of the thermal vapor recompressor (TVR 01) is connected with the MVR and second end is operatively connected with the shell & tube calandria (E 03).
The pair of plate type calandria (E 01 and E 02) and shell & tube calandria (E 03) is operatively configured to heat the liquid again which is travelling through (VLS 01), (VLS 02), (VLS 03) respectively. Said pair of plate type calandria (E 01) and (E 02) is configured to utilize the vapor from the mechanical vapor recompressor (MVR). The vapor liquid separators (VLS 01, VLS 02 and VLS 03) are configured to separate out preheated feed vapor and liquid. Said vapor from the vapor liquid separators are travelled upward and liquid is travelled downwards simultaneously. Said liquid from the vapor liquid separator (VLS 01) is configured to circulate from the vapor liquid separator (VLS 01) to the plate type calandria (E 01) through a transfer pump (TP 01). A partially concentrated feed from the transfer pump (TP 01) is circulated from plate type calandria (E 02) to the vapor liquid separator (VLS 02) through a transfer pump (TP 02). A partially concentrated feed from the transfer pump (TP 02) is circulated from the shell & tube calandria (E 03) to the vapor liquid separator (VLS 03) through a recirculation pump (RPE 01). A product pump (PP 01) is configured to pump out the concentrated feed from the recirculation pump (REP 01).
The mechanical vapor recompressor (MVR) is configured to increase the temperature of the vapor. Said mechanical vapor recompressor (MVR) used is root blower type which increases the temperature by 5° to 7°C of feed vapor entering to suction of mechanical vapor recompressor (MVR) through the vapor liquid separators (VLS 01, VLS 02 and VLS 03). The thermal vapor recompressor (TVR 01) is configured to increase the temperature of the part of vapor discharged from the mechanical vapor recompressor (MVR) and part of motive steam (live steam) by 10°-15°C.
The thermal vapor recompressor (TVR 02) is configured to operate as a bypass mechanism when the mechanical vapor recompressor (MVR) is in maintenance. Said mechanical vapor recompressor (MVR) is a mechanical device, so due to flow of steam, mechanical parts get damage. So, to continue the process of the system, the thermal vapor recompressor (TVR 02) is being used to perform the function of mechanical vapor recompressor (MVR). The shell and tube calandria (E 03) is configured with the (VLS 03) and the (TVR 01) where chances of precipitation are high. Said TVR (01) discharge steam is used in the shell and tube type calandria (E 03) as a heating medium.
The surface condenser (SC 01) is configured to cool down the part of vapor travelling from the mechanical vapor recompressor (MVR) or the thermal vapor recompressor (TVR 02), where cooling water is used as cooling medium. The flash tanks (FLT 01 and FLT 02) are configured to collect the condensate (pure or clean water) produced from the plate type calandrias (E 01 and E 02), the shell & tube type calandria (E 03), the preheater (HE 02) and the surface condenser (SC 01). The pre heater (HE 01) is configured to utilize the heat of hot condensate from the surface condenser (SC 01). The pre heater (HE 02) is configured to utilize the part of the vapor coming from the mechanical vapor recompressor (MVR). A pair of condensate pumps (CP 01 and CP 02) are configured to pump the condensate (pure water) collected in the flash tanks (FLT 01 and FLT 02) respectively to the preheater (HE 01) as a heating medium.
A vacuum pump (VP 01) is configured to generate vacuum when there is a generation of extra vapor in the system which may cause the failure of operation. Said extra vapor from the flash tank (FLT 01) is travelled out through the vacuum pump (VP 01).
It is to be understood that when the operation is started, all the equipments of the system will start functioning simultaneously in around 30 to 60 min. So, a particular feature of the treatment process as hereinafter described is that the cycle is continuous.
The present invention provides a process for treating waste water by MEE (Multi-effect evaporation) having MVR (mechanical vapor recompression) coupled TVR (thermal vapor recompression) & PHE (plate calandria) along with SLT (shell and tube) calandria with TVR (thermal vapor recompression) for MVR (mechanical vapor recompression) bypass which comprises following steps:
The method of the present invention comprises following steps:
a) A feed (waste water which is to be treated) is fed in to a feed tank (FT 01).
b) Said feed from feed tank (FT 01) is pumped to a preheater (HE 01) through a feed pump (FP 01). The said preheater (HE 01) utilizes the heat of hot condensate from a surface condenser (SC 01) and preheats the feed (waste water).
c) Said preheated feed is passed into the pre heater (HE 02) for preheating up to the boiling point of the feed (waste water). The said preheated feed is again heated in the pre heater (HE 02) using part of the vapor coming from a mechanical vapor recompressor (MVR) to separate out the condensate from the pre-heated feed and condensate is flashed out into a flash tank (FLT 01) as clean water.
d) Said remaining feed from the preheater (HE 02) is flashed in to a vapor liquid separator (VLS 01) to separate out the vapor and liquid simultaneously.
e) The liquid discharged from the bottom of the vapor liquid separator (VLS 01) is then pumped to a plate type calandria (E 01) through a transfer pump (TP 01). The said liquid is then heated in the plate calandria (E 01) through the vapor coming from the mechanical vapor recompressor (MVR) and flashed in to the vapor liquid separator (VLS 01) again and circulation of the feed is continued for feed concentration. The condensate from the plate calandria (E 01) is travelled to the flash tank (FLT 01).
f) Simultaneously, the vapor discharged from the top of the vapor liquid separator (VLS 01) is travelled to suction of the mechanical vapor recompressor (MVR).
g) Said partially concentrated feed from the transfer pump (TP 01) is travelled to a transfer pump (TP 02) at its suction side and is pumped to a plate calandria (E 02) through the transfer pump (TP 02).
h) Said partially concentrated feed is heated in plate calandria (E 02) through the vapor coming from the mechanical vapor recompressor (MVR) and said heated concentrated feed is flashed in to a vapor liquid separator (VLS 02).
i) The vapor liquid separator (VLS 02) separates out the vapor and liquid simultaneously. In the vapor liquid separator (VLS 02), the vapor is travelling upward and liquid is travelling downwards.
j) The liquid discharged from the bottom of the vapor liquid separator (VLS 02) is then pumped to a plate type calandria (E 02) through a transfer pump (TP 02). The circulation of the feed is continued for feed concentration and condensate is flashed out into a flash tank (FLT 01) as clean water.
k) Simultaneously, the vapor discharged at the top of the vapor liquid separator (VLS 02) is travelled to suction of the mechanical vapor recompressor (MVR).
l) Said partially concentrated feed from transfer pump (TP 02) is travelled to a recirculation pump (RPE 01) at its suction side.
m) Said partially concentrated feed is pumped to a shell and tube calandria (E 03) through the recirculation pump (RPE 01).
n) Said concentrated feed is heated in the shell & tube calandria (E 03) through the steam coming from a thermal vapor recompressor (TVR 01) through its discharge side and said heated concentrated feed is flashed into a vapor liquid separator (VLS 03).
o) Here again, said vapor liquid separator (VLS 03) separates out the vapor and liquid simultaneously. In the vapor liquid separator (VLS 03), the vapor is travelling upward and liquid is travelling downwards.
p) The liquid accumulated at the bottom of the vapor liquid separator (VLS 03) is then pumped to the plate calandria (E 03) through the recirculation pump (RPE 01).
q) Simultaneously, the vapor accumulated at the top of the vapor liquid separator (VLS 03) is travelled to suction of the mechanical vapor recompressor (MVR). The circulation of the feed is continued for feed concentration. Then said concentrated feed (waste) is pumped out from the recirculation pump (RPE 01) via use of a product pump (PP 01).
r) Part of the vapor from MVR is travelled to shell & tube calandria (E 03) through the thermal vapor recompressor (TVR 01) with the help of the motive steam.
s) The condensate (clean water) from the shell and tube type calandria (E 03) is travelled to the flash tank (FLT 01).
t) When the mechanical vapor recompressor (MVR) is in the maintenance, said MVR is bypassed by a thermal vapor recompressor (TVR 02) and enters into the main stream to perform its operation and the system remains under running condition.
u) Said vapor from the vapor liquid separators (VLS 01, VLS 02 and VLS 03) is now travelled to the thermal vapor recompressor (TVR 02) and recompressed vapor with the help of the motive steam.
v) The part of vapor from the (MVR) and/or the thermal (TVR 02) from its discharge is travelled to the surface condenser (SC 01) and cooled down through cooling water and form the condensate in to the flask tank (FLT 02) and pumped to the preheater (HE 01) through a condensate pump (CP 02) as a heating medium.
w) Now, the extra vapor generated in the system is travelled out through the flash tank (FLT 02) to a vacuum pump (VP 01) and vacuum is generated.
x) Simultaneously, the said condensate (clean water) accumulated from step c), e), j) and s) i.e. from the pair of plate type calandria (E 01), (E 02), the shell & tube type calandria (E 03), and the preheater (HE 02) in the flash tank (FLT 01) is pumped out through the preheater (HE 01) via condensate pump (CP 01) and travelled out through discharge side.
y) Record the unit of power cost, steam cost and cooling water cost used in the system every day.
The present invention is experimented and illustrated more in details in the following example. It describes and demonstrates embodiments within the scope of the present invention. It is given solely for the purpose of illustration and is not to be construed as limitations of the present invention, as many variations thereof are possible without departing from spirit and scope.
Example 1:
One accomplishment of the present invention may be illustrated by comparing the operating cost and capital cost of the present invention system and the conventional system. Their preferred quantities and obtained operating cost and capital cost respectively are described in Table 1 below:
Table 1: Operating cost and capital cost of the conventional system
CONVENTIONAL SYSTEM (MEE+TVR)
Feed Capacity KLD 100.0
Power Rs/Kwh 8.0
Steam Rs/Kgh 3.0
Cooling Water Rs/m3 0.7
Feed Rate kg/h 5000
Evaporation Rate kg/h 3750
Product Rate kg/h 1250
Contact Part MOC Titanium Gr2
Operational Cost Break up
MEE System Unit/Day Cost Rs/Day
Power Cost 1,400.0 11,200.0
Steam Cost 17,800.0 53,400.0
Cooling Water 2280 1596
Total Operation Cost 66,196.0
Rs/KL 662.0
Capital Cost Rs. 35,000,000

Table 2: Operating cost and capital cost of the present invention system
PRESENT INVENTION SYSTEM (PHE+S&T+MVR+TVR)
Feed Capacity KLD 100.0
Power Rs/Kwh 8.0
Steam Rs/Kgh 3.0
Cooling Water Rs/m3 0.7
Feed Rate kg/h 5000
Evaporation Rate kg/h 3750
Product Rate kg/h 1250
Contact Part MOC Titanium Gr2
Operational Cost Break up
MEE System Unit/Day Cost Rs/Day
Power Cost 2,200.0 17,600.0
Steam Cost 14,000.0 42,000.0
Cooling Water 400 280
Total Operation Cost 59,880.0
Rs/KL 598.8
Capital Cost Rs. 25,000,000

From the above described invention, it is observed that the system of MEE with introduction of the thermal vapor recompression (TVR 01) with the shell and tube type calandria (E 03) at the last effect of the MEE overcomes the problem of boiling point elevation and introduction of the mechanical vapor recompression (MVR) reduces the live steam consumption. This system also reduced the operating cost as compared with the conventional system by introducing the thermal vapor recompression (TVR 02) to bypass the mechanical vapor recompression (MVR) in its maintenance to still manage the system under running condition and hence, leads to increase in reliability of the system. Now, the introduction of PHE type calandria (E 01 and E 02) in first two effect of the MEE is directed to operate when there was zero precipitation and the shell & tube type calandria (E 03) in last effect of the MEE is directed to operate when there was a higher chance of precipitation. Hence, by introduction of combination PHE type calandria (E 01 and E 02) and shell & tube type calandria (E 03), the capital cost of the system can be reduced.
The invention has been explained in relation to specific embodiment. It is inferred that the foregoing description is only illustrative of the present invention and it is not intended that the invention be limited or restrictive thereto. Many other specific embodiments of the present invention will be apparent to one skilled in the art from the foregoing disclosure. All substitution, alterations and modification of the present invention which come within the scope of the following claims are to which the present invention is readily susceptible without departing from the spirit of the invention. The scope of the invention should therefore be determined not with reference to the above description but should be determined with reference to appended claims along with full scope of equivalents to which such claims are entitled.
, Claims: We Claim:

1. A MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass comprising:
a feed tank (FT 01) configured to collect the waste water, a pair of pre heaters (HE 01) (HE 02), a pair of plate type calandria (E 01) (E 02), vapor liquid separators (VLS 01), (VLS 02) and (VLS 03), a mechanical vapor recompressor (MVR), a pair of thermal vapor recompressor (TVR 01) (TVR 02), a shell and tube type calandria (E 03), a surface condenser (SC 01), a pair of flash tank (FLT 01) (FLT 02); each vapor liquid separator configured to separate vapor and liquid,
a feed tank (FT 01) fluidly communicated with the pair of pre heaters (HE 01) (HE 02) through the feed pump (FP 01), said pair of pre-heaters (HE 01) (HE 02) connected with the vapor liquid separator (VLS 01), the MVR is configured to collect the vapor discharge from the (VLS 01), (VLS 02) and (VLS 03), one end of the TVR (01) is connected with the MVR and second end of the TVR (01) is operatively connected with the shell and tube calandria (E 03),
characterized in that liquid from the vapor liquid separator (VLS 01) is configured to circulate from the vapor liquid separator (VLS 01) to plate type calandria (E 01) though transfer pump (TP 01);
a partially concentrated feed from the transfer pump (TP 01) is circulated from plate type calandria (E 02) to (VLS 02) through transfer pump (TP 02);
a partially concentrated feed from the transfer pump (TP 02) is circulated from the shell and tube calandria (E 03) to vapor liquid separator (VLS 03) through a recirculation pump (RPE 01);
plate type calandria (E 01) and (E 02) are configured to utilize the vapor from the mechanical vapor recompressor (MVR) and shell & tube calandria (E 03) is configured to utilize the discharged steam from thermal vapor recompressor (TVR 01);
the thermal vapor recompressor (TVR 02) is configured to operate as a bypass mechanism when the mechanical vapor recompressor (MVR) is in maintenance.
2. The MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass as claimed in claim 1, wherein the surface condenser (SC 01) is configured to cool down the part of the vapor travelling from the mechanical vapor recompressor (MVR) or the thermal vapor recompressor (TVR 02) with the help of cooling water.
3. The MEE having MVR coupled TVR & PHE along with SLT calandria with TVR for MVR bypass as claimed in claim 1, wherein pre heater (HE 01) is configured to utilize the heat of hot condensate from the surface condenser (SC 01).
4. The MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass as claimed in claim 1, wherein pre heater (HE 02) is configured to preheat the waste water by using part of the vapor coming from the mechanical vapor recompressor (MVR).
5. A method for treating waste water by the MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass as claimed in claim 1, comprising following step:
a) feeding a feed in to a feed tank (FT 01);
b) pumping the feed from the feed tank (FT 01) into a preheater (HE 01) through a transfer pump (TP 01) and preheating the feed by utilizing the heat of hot condensate from a surface condenser (SC 01);
c) passing the preheated feed from the preheater (HE 01) into a preheater (HE 02) and preheating the feed up to the boiling point by utilizing the vapor coming from a mechanical vapor recompressor (MVR) to separate out the condensate from the pre-heated feed and flashing condensate into a flash tank (FLT 01) as clean water;
d) flashing the remaining feed from the preheater (HE 02) into a vapor liquid separator (VLS 01) to separate out the vapor and liquid simultaneously;
e) circulating the liquid discharged from the vapor liquid separator (VLS 01) to a plate type calandria (E 01) through the transfer pump (TP 01) continuously and heating said liquid in the plate calandria (E 01) through the vapor coming from the mechanical vapor recompressor (MVR) to separate out the condensate from the liquid and flashing condensate into the flash tank (FLT 01) as clean water;
f) discharging the vapor from the vapor liquid separator (VLS 01) and travelling to suction of the mechanical vapor recompressor (MVR) simultaneously;
g) pumping the remaining partially concentrated feed obtained in step e) into a plate type calandria (E 02) through a transfer pump (TP 02) and heating said partially concentrated feed into the plate type calandria (E 02) through the vapor coming from the mechanical vapor recompressor (MVR); and said heated concentrated feed is flashed into a vapor liquid separator (VLS 02);
h) separating the vapor and liquid from the heated concentrated feed into the vapor liquid separator (VLS 02);
i) circulating the liquid discharged from the vapor liquid separator (VLS 02) to the plate type calandria (E 02) through the transfer pump (TP 02) continuously and heating said liquid in the plate calandria (E 02) through the vapor coming from the mechanical vapor recompressor (MVR) to separate out the condensate from the liquid and flashing condensate into the flash tank (FLT 01) as clean water;
j) discharging the vapor from the vapor liquid separator (VLS 02) and travelling to suction of the mechanical vapor recompressor (MVR) simultaneously;
k) pumping the remaining partially concentrated feed obtained in step i) into a shell and tube type calandria (E 03) through a recirculation pump (RPE 01) and heating said partially concentrated feed into the shell and tube type calandria (E 03) through the part of vapor from the mechanical vapor recompressor (MVR) through the thermal vapor recompressor (TVR 01) and said heated concentrated feed is flashed into a vapor liquid separator (VLS 03);
l) separating the vapor and liquid from the heated concentrated feed into the vapor liquid separator (VLS 03);
m) circulating the liquid discharged from the vapor liquid separator (VLS 03) to the shell and tube type calandria (E 03) through the recirculation pump (RPE 01) continuously and heating said liquid in the shell and tube type calandria (E 03) to separate out the condensate from the liquid and flashing condensate into the flash tank (FLT 01) as clean water;
n) discharging the vapor from the vapor liquid separator (VLS 03) and travelling to suction of the mechanical vapor recompressor (MVR) simultaneously and pumping out the remaining waste from the recirculation pump (RPE 01) via use of a product pump (PP 01);
o) accumulating the condensate from step c), e), i) and m) in the flash tank (FLT 01) and pumping out to the preheater (HE 01) via condensate pump (CP 01) and discharging out through the pre heater (HE 01).
6. The method for treating waste water by the MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass as claimed in claim 5, wherein mechanical vapor recompressor (MVR) is bypassed by the thermal vapor recompressor (TVR 02) when the mechanical vapor recompressor (MVR) is in the maintenance.
7. The method for treating waste water by the MEE having MVR coupled TVR & PHE alongwith SLT calandria with TVR for MVR bypass as claimed in claim 5, wherein remaining vapor from the (MVR) or the (TVR 02) from its discharge side is travelled into the surface condenser (SC 01) to form condensate which is passed to the flash tank (FLT 02) and pumped out via condensate pump (CP 02).

Dated this on 4th day of May, 2022.