BACKGROUND OF THE INVENTION
[0002] Evaporation process, when used in Dairy Industry, is performed as a preliminary step where the milk is normally concentrated from an initial solid content of 8-12% to a final concentration of 42-48% before the final concentrate is fed to a spray dryer. Typically, the evaporation process is performed in multiple effect evaporators, also commonly referred to as multi effect evaporators, where two or more effects and/or vessels operate at progressively lower pressures and thereby lowering the boiling points of the concentrate. As a concept, in a multiple effect evaporator, water is boiled in a sequence of heat exchangers, each held at a lower pressure than the last. As the boiling point of water decreases as pressure decreases, the vapor boiled off in one heat exchangers is used to heat the next, and only the first vessel (at the highest pressure) requires an external source of heat. By means of such a heating mechanism, the evaporator evaporates the solvent such as water and concentrates non-volatile solutes such as milk.
[0003] While using multiple effect evaporators, vapour produced in first effect can be used as a heating medium for the second effect. The result is that the amount of steam required is approximately equal to the total amount of water evaporated divided by the number of effects. During operation, the raw feed is introduced in the first effect and is passed from effect to effect parallel to steam flow. The product is withdrawn from the last effect. Conventional Multiple effect evaporators typically include Calandrias, Vapour separators, Pre-heaters, Thermo Vapor
Recompression (TVR), Condensers and Cooling towers as their primary components in any industrial plant site.
[0004] Evaporator Calandrias or simply referred to as a calandria is a long-tube vertical heat exchanger that places the liquid to be heated inside the tubes and the liquid to be evaporated outside the tubes. Thermal Vapour Recompression (TVR), on the other hand, is configured to use live stream to recompress to vapour from one effect to be used as heating medium for the first effect. Vapour separators
integrated into the evaporation process ensure efficient separation of liquid and
vapour. Pre-heaters are used to heat the feed to an evaporator with regenerated vapours. Condensers are used to condense surplus vapour from final evaporation stage. Condensers use a cooling tower and cooling pump in the plant for circulation of water to condense the vapors of last effect.
[0005] Conventional Multiple effect evaporators include two-effect, four -effect, five - effect and even the seven - effect evaporators equipped with condensers. These Condensers spend a lot of resources and energy to make the whole evaporator plant function effectively. For instance, a lot of cooling water is required to condense last effect vapour and moreover, a cooling tower is needed to cool hot water coming out of the condenser.
[0006] Therefore, there is a need for an energy efficient Multi effect evaporator plant that can overcome the above mentioned problem of using resources such as condensers, cooling towers and cooling water, which can actually be avoided.
OBJECTS OF THE INVENTION
[00071 K is an object of the present invention to provide a multi effect
evaporator that functions without a condenser.
[0008] It is another object of the invention to provide a multi effect evaporator
that functions without cooling water and cooling water pumps.
[0009] It is yet another object of the invention to provide a multi effect
evaporator that functions without cooling tower equipments.
[00010] It is another object of the invention to provide gentle heat treatment
to the liquid to be processed in a multi effect evaporator.
[00011] It is an object of the present invention to provide an improvement in the
existing evaporation system thereby to re-use all generated vapors in the plant and
make the system energy efficient one.
SUMMARY OF THE INVENTION
[00012] The described systems and methods relate to a Multi effect evaporator plant that functions without a condenser and cooling tower equipments. In the system, the proposed Multi effect evaporator plant uses a pre-heater that is sufficient to eliminate the use of the condenser. The pre-heater has the capability of condensing remaining vapor accumulated in the last effect and/or vessel of a Multi effect evaporator. The Multi effect evaporator plant uses energy efficient devices and methods to provide a unique condensation process that distributes vapors of multiple effects in a manner such that all vapors are used within the system, thereby avoiding the need of a condenser. Further, the Multi effect evaporator plant provides an energy efficient condensation process that uses pre-heater as the condenser thereby avoiding condenser and cooling tower equipments.
BRIEF DESCRIPTION OF THE DRAWINGS
[00013] The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. [00014] Fig. 1 illustrates a block diagram of a conventional Multi effect evaporator system (prior art) that uses condensers and cooling towers for working of the system.
[00015] Fig. 2 illustrates a block diagram of a novel Multi effect evaporator that functions without a condenser and/or a cooling water requirement as part of an embodiment of the invention.
DETAILED DESCRIPTION
[00016] The systems and methods described herein may be used in many different and compatible operating environments. Multiple and varied implementations are described below. An exemplary environment that is suitable for practicing various implementations is discussed in the following section. While the systems and methods are described in the foregoing contexts, acts and operations described hereinafter is implemented in hardware or other forms of computing platforms. Even though most of the disclosure in the present embodiments discussed below discloses some specific systems and methods for a multi effect evaporator that can function without condenser and cooling tower equipments, all other compatible apparatus and modes of multi effect evaporator execution can be used for implementation of the proposed systems and methods.
[00017] Fig. 1 (Prior Art) illustrates a conventional Multi effect (5-effect) evaporator 100 and a mechanism of operation thereof. The evaporator 100 includes a plurality of Calandrias including 102,104,106,108 and 110, together referred to as calandria 102 hereinafter. The evaporator unit 100 includes a number of vapour
separators (112, 114, 116, 118 and 120), together referred to as vapour separators 112 hereinafter, Pre-heaters (122, 124, 126, 128, 130 and 132), together referred to as pre-heaters 122 hereinafter, and a direct system injector (DSI) 134. The conventional unit 100 further includes a Thermal Vapour Recompression (TVR) 136, a flash vessel 138 and a condenser 140.
[00018] In an embodiment, liquid feed is stored in a balance tank. During the feed concentration process, the liquid feed from the balance tank is passed into the pre-heaters 122. Pre-heaters 122 are used to heat the feed with generated vapors, preferably of less energy value than that of the steam or vapor condensed in the evaporator heat exchanger. In an implementation, the processed feed from pre-heater 122 is then passed into the DSI unit 134. In one implementation, the DSI unit 134 performs the pasteurization process, which involves the heating of the product by directly injecting steam into the product thereby heating the liquid upto pasteurization temperature.
[00019] In one embodiment, feed from the DSI unit 134 is then passed into the first calandria 102 through a holding vat and flash vessel 138. The feed enters the first calandria 102 in the tube side subsequent to which the boiling in the tube starts, which causes flow of liquid vapor mixture to the vapour separator 112. In one implementation the vapour separator 112 is maintained at particular vacuum. [00020] In one embodiment, the vapour separator 112 removes the vapour from the product and further allows it to pass through the second calandria 104 as a heating medium. Subsequently, the above process is performed at different Calandrias (106 - 110) separated by vapour separators (116 - 120). The liquid from vapour separator 112 passes through the Calendrias (106-110) and 45% concentrated milk product is yielded out of the last calandria and/or effect. The heating medium, which is steam, passes through a TVR system 136 where portion of the generated vapour gets sucked along with the steam to enhance energy efficiency.
[00021] In an embodiment, the last evaporated vapour from the vapour separator 120 is fed into the condenser 140 and pre-heater 122. In an implementation, in the condenser 140, the vapour acts as a heating medium for the product and is condensed by bringing in contact with cold water at 30 degree C using a cooling water pump. In the condenser 140, cooling water, being fed at 30°C is circulated which gets heated upto 38°C and subsequently gets cooled in a cooling tower 146 and the cooled water is recirculated in the condenser as a cyclic process. [00022] Thus, in the conventional multi effect evaporation configuration such as illustrated in configuration 100, there is a lot of energy and resources consumed by the condenser 140 and the cooling water equipments.
[00023] Fig. 2 illustrates a block diagram of a Multi effect evaporator 200 that functions without condenser and cooling water requirement as part of an embodiment of the invention.
[00024] The evaporator 200 includes a plurality of Calandrias 102, 104, 106,108 and 110. The evaporator unit 200 includes a number of vapour separators (112,114, 116, 118 and 120), Pre-heaters (122, 124, 126, 128, and 230) and a direct system injector (DSI) 134. The evaporator unit 200 further includes a Thermal Vapour Recompression (TVR) 136, a flash vessel 138 and a condensate pump 144. [00025] In an embodiment, liquid feed to be condensed is stored in a balance tank. The liquid feed from the balance tank is passed through the pre- heaters (122, 124, 126, 128, and 230). Pre-heaters are used to heat the feed with generated vapors, preferably of less energy value than that of the steam. In an implementation, the feed from pre-heater 122 is then passed into the DSI unit 134. In another implementation, the DSI unit 134 performs the pasteurization process which involves heating of the feed by directly injecting steam into the product. [00026] In an embodiment, feed from the DSI unit 134 is then passed into the first calandria 102 through a holding vat and flash vessel 138. The feed enters the first calandria 102 in the tube side subsequent to which the boiling in the tube starts
thereby causing flow of liquid vapor mixture to the vapour separator 112. In one implementation the vapour separator 112 is maintained at a particular vacuum. [00027] In an embodiment, the vapour separator 112 removes the vapour from the product and the liquid is further allowed it to pass through the second calandria 104. Subsequently, the above process is performed at different Calandrias (106 -110) separated by vapour separators (116 - 120). The heating medium, which is steam, passes through a TVR system 136 where portion of the generated vapour gets sucked along with the steam to enhance energy efficiency. [00028] In an embodiment, the Calendria 110 does not include a pre heater required for heating the feed with generated vapors. No pre-heater for a specific calendria leads to low evaporation in the particular stage leading lower amount of generated vapour. With low vapor being generated, a pre-heater 230 is sufficient to act as a condenser for condensing the remaining vapor amount thereby avoiding the need for a separate condenser and cooling tower.
[00029] In an embodiment, the last separated vapour from the vapour separator 120 is fed into the pre- heater 230. Further, the Multi effect evaporator 200 uses energy efficient devices and methods to provide a unique condensation process that distributes vapors of multiple effects in a manner such that all vapors are used in the system thereby avoiding the need for additional vapour for condensing in a condenser. As the pre-heater in the above described multi effect evaporator 200 condenses the vapour, there is no need of a separate condenser to condense the last separated vapour in the system 200. In one embodiment of the invention, since the condenser is eliminated completely, there is no need for cooling tower and other cooling water equipments.
[00030] Results illustrating concentration of milk along with temperature reduction across vapour separators used in a Multi effect evaporator 200 having a six effect calandria system are shown in Table 1. The table clearly demonstrates
MULTI EFFECT EVAPORATOR
FIELD OF INVENTION:
[0001] The invention relates to a Multi effect evaporator plant. In particular, the present invention relates to systems and methods for a Multi effect evaporator plant that avoids the need for a condenser and a cooling tower in the plant.
efficient working of the evaporator 200 without the condenser, cooling water, and cooling tower and instead using a pre-heater for condensing the residual vapour.

(Table Removed)
Table 1
[00031] The foregoing illustrated and described embodiments of the invention are susceptible to various modifications and alternative forms, and it should be understood that the invention generally, as well as the specific embodiments described herein, are not limited to the particular forms or embodiments disclosed,
but cover all modifications, equivalents and alternatives falling within the scope of the appended claims. By way of non- limiting example, it will be appreciated by those skilled in the art that particular features or characteristics in one embodiment may be combined as suitable with features or characteristics described in another embodiment. Moreover, the system and method for of the present invention can be a system used along with an automated or even with a manual system.
ADVANTAGES OF THE INVENTION
[00032] The present invention provides a multi effect evaporator that functions
without condenser.
[00033] The present invention provides a multi effect evaporator that functions
without cooling water and cooling water pumps.
[00034] The present invention provides a multi effect evaporator that functions
without cooling tower equipments.
[00035] The present invention provides a gentle heat treatment of the liquid to be
processed in a multi effect evaporator.
[00036] The present invention provides an improvement in the existing
evaporation system thereby to re-use all evaporated vapour in the plant and make
the system as energy efficient one.

WE CLAIM;
1. A multi effect evaporator for concentrating a non-volatile liquid feed,
wherein said evaporator comprises:
a plurality of calandrias;
a plurality of vapour separators;
a plurality of pre-heaters for heating said liquid feed with a heat transfer medium, wherein at least one pre-heater of said plurality of pre-heaters condenses last effect vapour from said plurality of vapour separators.
2. The multi effect evaporator as claimed in claim 1, wherein said multi effect evaporator avoids need of a condenser and a cooling tower.
3. The multi effect evaporator as claimed in claim 1, wherein said multi effect evaporator distributes vapors of multiple effects such that all vapors are used within said multi effect evaporator.
4. The multi effect evaporator as claimed in claim 1, wherein said non-volatile liquid feed comprises of milk at low feed temperature.
5. The multi effect evaporator as claimed in claim 1, wherein said evaporator further comprises of a Thermo Vapor Recompression (TVR) configured to suck generated vapour along with steam.
6. The multi effect evaporator as claimed in claim 1, wherein at least one effect of said multi effect evaporator does not have a pre-heater.
7. The multi effect evaporator as claimed in claim 6, wherein said at least one effect is the last effect of said multi effect evaporator.