DESC:
FIELD
The present disclosure relates to evaporation systems.
DEFINITION
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
LMTD: Logarithmic Mean Temperature Difference (LMTD) is the average driving force of heat transfer. LMTD is defined as the logarithmic average of the temperature difference between hot and cold fluids at each end of a heat exchanger.
LMTD =(?T_1-?T_2)/(ln?(?T_1/ ?T_2))
where ‘1’ is a first end and ‘2’ is a second end of the heat exchanger.
In a co-current-type heat exchanger,
?T_1=T_hot1-T_cold1=T_(hot in)-T_(cold in)
?T_2=T_hot2-T_cold2=T_(hot out)-T_(cold out)
whereas, in a Counter-current heat exchanger,
?T_1=T_hot1-T_cold1=T_(hot in )-T_(cold out)
?T_2=T_hot2-T_cold1=T_(hot out)-T_(cold in)

BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
An evaporator in the form of a heat exchanger is used to separate a solvent and a solute. Steam is generally used as the heat source in such evaporators. A multiple effect evaporator (MEE) system operates based on the principle of evaporation of a solvent at reduced pressures across each effect (stage) thereby reducing the live steam consumption. For illustration purpose, water is considered as the solvent (although solvent can be any liquid) and mixture of inorganic salts is considered as the solute. For example, a 4-stage evaporation system will typically require 1 kg of live steam to evaporate 4 kg of water where as a single stage evaporation system will require 4 kg of steam to evaporate 4 kg of water. Using the principle of evaporation at multiple effects, the steam consumption of the MEE system can be drastically reduced resulting in less operating expenses (OPEX). MEE system can concentrate the feed effluent water (water containing mixed inorganic salts in dissolved form) upto about 40% in the case of zero liquid discharge applications. Beyond that the salts precipitation will take place resulting in scaling and formation of hard scales.
Therefore, the concentrated effluent water (at 25% to 40%) is then taken to an agitated thin film dryer (ATFD) system to concentrate the salts further to about 90% dry condition. The concentrated effluent water is distributed to the wall of the inner shell of ATFD by means of a rotor (scrapper blades area attached to the rotor) to form a thin film. Steam is supplied as the hot source in the steam jacket surrounding the inner shell resulting in evaporation of the water from the concentrated effluent water. The mixture of inorganic salts obtained at the outlet of ATFD is almost 90% dry.
The feed effluent water coming from reverse osmosis (RO) system is used as the cooling water for condenser in the MEE system. The feed water gets preheated first in the condenser and then goes to the other preheaters in the MEE system. An adiabatic evaporator (i.e. cooling tower) can be incorporated to cool the excess cooling water coming from the condenser resulting in evaporation loss. The evaporation loss of the cooling tower results in reduction of evaporation load to MEE system thereby achieving good steam economy. However, in some cases soft water is used as the cooling water for condenser instead of effluent water resulting in increased evaporation load to the MEE system and reduction in steam economy.
Steam economy is defined as the ratio of the mass of steam supplied to the evaporation mass of the water. Steam economy of the MEE system can be slightly increased by incorporating a thermo compressor (TC) wherein the part of the vapour generated at a stage (i.e., low-pressure evaporator) is compressed to an intermediate pressure using the high pressure live steam from the boiler.
Though good steam economy is achieved in the MEE system by means of increasing number of stages, adiabatic evaporator design (where feed effluent water is used as cooling water for condenser) and incorporation of TC, the steam consumption of ATFD system is not reduced. The vapour generated in the ATFD is either taken to a separate condenser for condensing it to water, or it is vented out which leads to evaporation loss.
There is, therefore, felt a need of a system which solves the problems related to a thermal evaporation system for solvent and solute recovery as described hereinabove.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a thermal evaporation system for solvent and solute recovery.
Another object of the present disclosure is to provide a thermal evaporation system for solvent and solute recovery, which is more energy-efficient.
Yet another object of the present disclosure is to provide a thermal evaporation system for solvent and solute recovery, which has lower steam consumption.
Still another object of the present disclosure is to provide a thermal evaporation system for solvent and solute recovery, which is economical.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
ABBREVIATIONS
MEE - Multiple effect evaporator
HX - Heat exchanger
PH - Preheater
FV - Flash vessel
P - Pump
TC - Thermo compressor
C - Condenser
ATFD - Agitated thin film drier
RO - Reverse osmosis
CT - Cooling tower

SUMMARY
Provided in this present disclosure is a thermal evaporation system for solute-solvent recovery.
The thermal evaporation system comprises of an evaporator module which converts a solute-solvent mixtue received from an effluent tank to a first concentration, which is upto 40% dry, and a dryer which receives the solute-solvent mixture in said first concentration and converts it to a second concentration, which is upto 100% dry. The thermal evaporation system also has a recirculation conduit which recirculates the vapors generated in said dryer in the system. These vapors may be reciculated through a recirculation conduit(s). Further, the system uses thermocompressor(s) and/or recompressor(s) positioned prior to said evaporator module and/or the dryer for compression of the vapors carried by the recirculation conduit(s) from the dryer.
The thermocompressors are configured to mix fresh heating fluid (live steam) with the received recirculated vapors to reduce the heating fluid requirement.
The evaporator module is a multieffect evaporator module (MEE) and comprises a plurality of evaporation stages. The recompressor is a mechanical compressor and the dryer can be an Agitated Thin Film Dryer (ATFD).
Preferably, the dryer has a rotary air lock valve to minimize air ingress.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
A thermal evaporation system for solvent and solute recovery of the present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 is a schematic diagram of a 4-stage MEE system with ATFD for salt concentration according to prior art;
Figure 2 is a schematic diagram of a 4-stage MEE system with TC and ATFD for salt concentration according to prior art;
Figure 3 is a schematic block diagram of a thermal evaporation system according to a first embodiment of the present disclosure;
Figure 3a is a schematic block diagram of a thermal evaporation system according to a second embodiment of the present disclosure;
Figure 4 is a schematic block diagram of a thermal evaporation system according to a third embodiment of the present disclosure;;
Figure 5 is a schematic block diagram of a thermal evaporation system according to a fourth embodiment of the present disclosure;Figure 6 is a schematic block diagram of a thermal evaporation system according to a fifth embodiment of the present disclosure;
Figure 7 is a schematic block diagram of a thermal evaporation system according to a sixth embodiment of the present disclosure;
Figure 8 is a schematic block diagram of a thermal evaporation system according to a seventh embodiment of the present disclosure;
Figure 9 is a schematic block diagram of a thermal evaporation system according to a eighth embodiment of the present disclosure;
Figure 10 is a schematic block diagram of a thermal evaporation system according to a ninth embodiment of the present disclosure;
Figure 11 is a schematic block diagram of a thermal evaporation system according to a tenth embodiment of the present disclosure;
Figure 12 is a schematic block diagram of a thermal evaporation system according to an eleventh embodiment of the present disclosure;
Figure 13 illustrates an evaporator module comprising four-stage evaporation in accordance to the first embodiment of the present disclosure;
Figure 14 illustrates an evaporator module comprising four-stage evaporation in accordance to the second embodiment of the present disclosure;
Figure 15 illustrates an evaporator module comprising four-stage evaporation in accordance to the third embodiment of the present disclosure;
Figure 16 illustrates an evaporator module comprising four-stage evaporation in accordance to the fourth embodiment of the present disclosure; and
Figure 17 illustrates an evaporator module comprising four-stage evaporation in accordance to the fifth embodiment of the present disclosure.

LIST OF REFERENCE NUMERALS
100 - Thermal evaporation system
102 - Evaporator module (i.e., MEE system)
104 - Dryer
106 - Effluent tank
108 - Thermo compressor
110 - Recirculation conduit
112 - Recompressor
114 - Steam inlet for thermo compressor (108)
116 - Steam inlet for the multiple effect evaporator system (102)
118 - Effluent solution inlet for effluent tank (106)
120 - Conduit for transfer of effluent solution from effluent tank (106) to multiple effect evaporator system (102)
122 - Conduit for transfer of first concentrated solution outlet from multiple effect evaporator system (102) to dryer (104)
124 - Vacuum line outlet from multiple effect evaporator system (102)
126 - Steam inlet for dryer (104)
128 - Condensate outlet from dryer (104)
130 - Second concentrated solution outlet from dryer (104)
132a - First heat exchanger
132b - Second heat exchanger
132c - Third heat exchanger
132d - Fourth heat exchanger
134a - First flash vessel
134b - Second flash vessel
134c - Third flash vessel
134d - Fourth flash vessel
136a - First preheater
136b - Second preheater
136c - Third preheater
136d - Fourth preheater
138a - First pump
138b - Second pump
138c - Third pump
138d - Fourth pump
138e - Fifth pump
140 - Vacuum pump
142 - Condenser

DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises”, “comprising”, “including” and “having” are open-ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
When an element is referred to as being “mounted on”, “engaged to”, “connected to” or ‘coupled to” another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as “inner”, “outer”, “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
An evaporator in the form of a heat exchanger is used to separate a solvent and a solute. Steam is generally used as the heat source in such evaporators. A multiple effect evaporator (MEE) system operates based on the principle of evaporation of a solvent at reduced pressures across each effect (stage) thereby reducing the live steam consumption. For illustration purpose, water is considered as the solvent (although solvent can be any liquid) and mixture of inorganic salts is considered as the solute. For example, a 4-stage evaporation system will typically require 1 kg of live steam to evaporate 4 kg of water where as a single stage evaporation system will require 4 kg of steam to evaporate 4 kg of water. Using the principle of evaporation at multiple effects, the steam consumption of the MEE system can be drastically reduced resulting in less operating expenses (OPEX). MEE system can concentrate the feed effluent water (water containing mixed inorganic salts in dissolved form) upto about 40% in the case of zero liquid discharge applications. Beyond that precipitation of the salts will take place resulting in scaling and formation of hard scales.
Though good steam economy is achieved in the MEE system by means of increasing number of stages, adiabatic evaporator design (where feed effluent water is used as cooling water for condenser) and incorporation of TC, the steam consumption of ATFD system is not reduced. The vapour generated in the ATFD is either taken to a separate condenser for condensing it to water, or it is vented out which leads to evaporation loss.
Figure 1 and Figure 2 illustrate a 4-stage multiple effect evaporator (MEE) system (102) of the prior art, with an integrated agitated thin film dryer (ATFD) (104). The heat exchangers (132a, 132b, 132c, 132d) are preferably of ‘forced circulation type’, although the design configuration can be selected from a group consisting of falling film type, rising film type and so on, and the construction can be selected from a group consisting of shell-and-tube type, plate type and so on.
Steam economy can be slightly improved by incorporating a thermo compressor (108) (TC) wherein a part of the water vapour generated in the first stage (i.e., at low pressure) is compressed to an intermediate pressure using the high-pressure live steam from the boiler, as illustrated schematically in Figure 2.
Also, the feed effluent water can be used for cooling in the condenser, using an ‘adiabatic evaporator’, i.e. a cooling tower. The feed effluent water gets preheated in the condenser before going to other preheaters in the system.
Though steam economy is improved by increasing number of stages, increasing the number of stages has a limit, since, at higher stages, the last few stages will have concentrated salt solution that can cause deposition and therefore formation of hard scales on the surface of the heat exchanger. Furthermore, the capital cost of the system also increases with each stage added to it and so does the maintenance requirement. Moreover, improvement in steam economy achieved by incorporating an adiabatic evaporator configuration as mentioned above, as well as by incorporation of a TC, though appreciable, can further be engineered to be significantly better.
The present disclosure envisages a thermal evaporation system for solute-solvent recovery that overcomes the problems of the prior art. .
In a first embodiment, illustrated in Figure 3, the thermal evaporation system (100) comprises an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration, an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102), a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration, a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system, and a thermocompressor (108) configured to receive said vapors generated by said dryer from said recirculation conduit(110) and a live steam stream (114) from an external source and wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module.
In a second embodiment, illustrated in Figure 3a, in the system as per the first embodiment, a recompressor (112) is placed between said dryer(104) and said thermocompressor (108) such that said recirculation conduit (110) is split into a first part (110a) and a second part (110b), wherein said first part(110a) carries the vapors generated by the dryer (104) to said recompressor (112) wherein said recomprssor compresses said vapors which are then received by said thermocompressor through said second part (110b).

In a third embodiment, illustrated in Figure 4, the thermal evaporation system (200) for solute-solvent recovery comprises an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration, an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102), a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration, a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system and a thermocompressor (108) configured to receive said vapors generated by said dryer from said recirculation conduit (110) and a live steam stream (114) from an external source and wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said dryer (104) through an inlet (126) of said dryer (104).
In a fourth embodiment, illustrated in Figure 5, in the system as per the third embodiment, a recompressor (112) is placed between said dryer(104) and said thermocompressor (108) such that said recirculation conduit (110) is split into a first part (110a) and a second part (110b), wherein said first part(110a) carries the vapors generated by the dryer (104) to said recompressor (112) wherein said recompressor compresses said vapors which are then received by said thermocompressor through said second part (110b).
In a fifth embodiment, illustrated in Figue 6, a thermal evaporation system (300) for solute-solvent recovery comprises an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration, an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102), a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration, a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system and a recompressor(112) configured to receive said vapors generated by said dryer from said recirculation conduit (110) and compresses said vapors and circulates them to said dryer (104) through an inlet (126) of said dryer (104), wherein said vapors are mixed with a stream of live steam (190) before they enter the inlet (126)
In a sixth embodiment, illustrated in Figure 7, the thermal evaporation system (400) for solute-solvent recovery comprise an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration, an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102), a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration, a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system and a first thermocompressor (108) configured to receive a partial portion said vapors generated by said dryer (104) from said recirculation conduit(110) and a live steam stream (114) from an external source and wherein said first thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module and a second thermocompressor (108’) configured to receive a partial portion of said vapors generated by said dryer from said recirculation conduit (110’) and a live steam stream (114’) from an external source and wherein said thermocompressor (108’) supplies a compressed mixture of said steam and vapors to said dryer (104) through an inlet (126) of said dryer (104).

In a seventh embodiment, illustrated in Figure 8, in the system according to the sixth embodiment, a recompressor (112’) is placed between said dryer (104) and said thermocompressor (108’) such that said recirculation conduit (110’) is split into a first part (110a’) and a second part (110b’), wherein said first part(110a’) carries a partial portion of the vapors generated by the dryer (104’) to said recompressor (112’) wherein said recompressor compresses said vapors which are then received by said thermocompressor (108’) through said second part (110b’).
In an eighth embodiment, illustrated in Figure 9, the thermal evaporation system (500) for solute-solvent recovery comprises an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration, an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102), a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration, a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system and a recompressor (112’’) configured to receive a partial portion of said vapors generated by said dryer (104) from said recirculation conduit (110’’) and compresses said vapors and circulates them to said dryer (104) through an inlet (126) of said dryer (104), wherein said vapors are mixed with a stream of live steam (190) before they enter the inlet (126).

In a ninth embodiment, illustrated in Figure 10, the thermal evaporation system (600) for solute-solvent recovery comprises an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration, an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102), a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration , a first recirculation conduit (110a) and a second recirculation conduit (110b) for circulating vapors generated by said dryer in the system, a first recompressor (112) that receives a partial portion of the vapors generated by the dryer (104) through said recirculation conduit 110a wherein said first recomprssor compresses said vapors, a first thermocompressor (108) configured to receive the compressed vapors from said first recompressor through said second recirculation (110b) conduit and a live steam stream (114) from an external source ,and wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module and a second thermocompressor (108’) configured to receive a partial portion of said vapors generated by said dryer from said recirculation conduit (110’) and a live steam stream (114’) from an external source and wherein said thermocompressor (108’) supplies a compressed mixture of said steam and vapors to said dryer (104) through an inlet (126) of said dryer (104).

In a tenth embodiment, illustrated in Figure 11, in the system according to the ninth embodiment, a second recompressor (112’) is placed between said dryer(104) and said thermocompressor (108’) such that said recirculation conduit (110’) is split into a first part (110a’) and a second part (110b’), wherein said first part(110a’) carries a partial portion of the vapors generated by the dryer (104’) to said second recompressor (112’) wherein said recompressor compresses said vapors which are then received by said thermocompressor (108’) through said second part (110b’).
In an eleventh embodiment, illustrated in Figure 12, the thermal evaporation system (700) for solute-solvent recovery comprises an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration, an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102), a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration, a first recirculation conduit (110a) and a second recirculation conduit (110b) for circulating vapors generated by said dryer in the system, a first recompressor (112) that receives a partial portion of the vapors generated by the dryer (104) through said recirculation conduit 110a wherein said first recomprssor compresses said vapors, a first thermocompressor (108) configured to receive the compressed vapors from said first recompressor through said second recirculation (110b) conduit and a live steam stream (114) from an external source , wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module, and a second recompressor(112’’) configured to receive a partial portion of said vapors generated by said dryer (104) from said recirculation conduit (110’’) and compresses said vapors and circulates them to said dryer (104) through an inlet (126) of said dryer (104), wherein said vapors are mixed with a stream of live steam (190) before they enter the inlet (126).

The evaporator module maybe implemented as a multieffect evaporator module (MEE) which may have a plurality of evaporation stages.The dryer may be an Agitated Thin Film Dryer (ATFD) . The recompressor(s) can be mechanical compressor.
Preferably, the dryer has a rotary air lock valve to minimize air ingress.

Under normal operating conditions, the output of the MEE, i.e. said first concentration is upto 40% dry and the output of the ATFD is upto 100% dry.

The evaporator module ( is configured to concentrate a solute-solvent mixture by evaporating solvent from the mixture to provide a concentrated solute-solvent mixture of a first concentration, wherein the first concentration is upto 40% dry.
The effluent tank (106) is configured to supply the solute-solvent mixture to the evaporator module (102).
The dryer (104) is configured to further concentrate the concentrated solute-solvent mixture of first concentration and provide a solute-solvent mixture of a second concentration, wherein the second concentration is upto 90% dry.
The recirculation conduit (110) is configured to recirculate vapours generated by the dryer (104) within the thermal evaporation system (100). Where required, the reciculation conduit may be split to a plurality of conduits as in 110a and 110b, for the necessary connection and functionalities to be realized such as fitting the recompressor between the thermocompressor and dryer. .
The thermo compressor(s) (108, 108’) is configured to mix fresh heating fluid with the recirculated vapours to reduce the fresh heating fluid requirement.
The re-compressor (112,112’)is disposed on the recirculation conduit (110), configured to increase the pressure of heating fluid (vapors) coming from the dryer (104).

Figures 13,14,15,16 and 17 illustrates the evaporator module having four stages of evaporation as example in accordance to the first, second, third, fourth and fifth embodiments respectively. .
Though for the purpose of explanation and illustration, a 4-stage implementation of the invention embodiment is shown and considered, it is understood that any single or multiple stages may be considered for implementation of the invention disclosed in the current disclosure, and it is obvious to a person skilled in the art to design and engineer such a system as the application demands it.
In the first and second embodiments illustrated in Figure 3 and Figure 3a, all the vapor generated by the ATFD(104) is utilized as the heat source in the MEE system (102).
In the third, fourth and fifth embodiments, illustrated in Figure 4, Figure 5 and Figure 6 respectively, the vapors generated by the ATFD(104) are utilized as the heat source in the ATFD(104).

As the evaporation load increases in the ATFD (104), the steam pressure obtained at the TC (108) outlet decreases due to more compression work resulting in decreased LMTD for the heat exchangers. Since LMTD for the heat exchangers is reduced, the larger heat exchangers would be required, resulting in capital cost increment when compared to that of taking live steam to the MEE system (102).
This problem is overcome by putting a mechanical vapour recompressor (112) (MVR) in between the TC (108) and the ATFD (104),. The MVR (112) increases the pressure of vapour generated in the ATFD (104) and feeds the vapour into the TC (108). Here, the MVR (112) can be of any type such as, but not limited to, fan, blower or compressor which can compress the steam/vapor to increase its pressure. Since the pressure of vapour from the ATFD (104) is increased, the pressure of steam coming out from the TC (108) after mixing with high pressure live steam from the boiler is higher.
The discharge pressure of steam from the TC (108) will be significantly higher . and the high discharge pressure of steam increases the available LMTD for the heat exchangers resulting in compact and less expensive system.
A problem that can affect the performance of evaporation system is the carryover of air along with vapour generated from the ATFD (104). Therefore, the ATFD (104) system is configured with a rotary air lock valve to minimize air ingress. Even if the air carryover happens, the non-condensable air can be transferred via the non-condensable transfer lines connected from each heat exchanger (132a, 132b, 132c, 132d) to the flash vessels (138a, 138b, 138c, 138d) of the MEE. (These non-condensable lines are not shown in all the figures to avoid confusions in the schematic drawings). Finally the non-condensables would get collected in the condenser, which in turn is connected to vacuum pump (140) to vent out the non-condensables ensuring smooth operation of the plant. If required, individual vacuum pumps can be connected to first heat exchanger (132a) to remove the air ingresses into the system as non-condensables.
As shown in Figures 7,8, 10,11, part of the vapour generated in the ATFD (104) is recovered and is mixed with the live steam coming from the boiler in the thermo compressor (108’) (TC). The remaining part of the vapor generated in the ATFD (104) can be reused/recovered in the MEE system (102) to decrease overall live steam consumption or it can be taken through to a condenser and recovered as water or can be rejected to the atmosphere.
. To further increase the recovery rate of vapour generated in ATFD (104) over that given by the processes shown in Figure 15 and Figure 16 (i.e. to recover all vapours generated in ATFD), an MVR (112) is used, as shown in Figure 17,. The MVR compresses all the vapours generated in the ATFD (104) which is used as hot source of ATFD (104). This drastically reduces the steam consumption of the ATFD (104) than the steam requirement of the ATFD (104) as shown in Figure 15 and Figure 16. If a single MVR (112) is not sufficient to achieve desired discharge pressure at the outlet in order to maintain minimum LMTD for the ATFD (104), then multiple MVR (112) systems can be put in series to boost the pressure of vapour generated in the ATFD (104). The expenses incurred due to additional power consumption resulted due to MVR systems are much lesser than the savings resulted due to steam consumption reduction.
The decrease in LMTD of the ATFD (104) system when compared to taking high pressure live steam directly to ATFD (104) results in bigger ATFD (104) due to increased heat transfer area. However, the additional costs incurred are nullified over a period of operation due to great reduction in the steam consumption and less operational costs incurred. A problem that can affect the performance of evaporation system as mentioned in the first aspect, the second aspect and the first aspect of the second embodiment is the carryover of air along with vapour generated from the ATFD (104). The ATFD (104) system has a rotary air lock valve to minimize air ingress. Even if the air carryover happens, the non-condensable air can be transferred via the non-condensable transfer lines connected to the vacuum pump from the shell / jacket side of ATFD (104). The non-condensables in the heat exchangers (132a, 132b, 132c, 132d) of MEE system are transferred to flash vessels (138a, 138b, 138c, 138d). (These non-condensable lines are not shown in all the figures to avoid confusions in the schematic drawings). Finally, the non-condensables get collected in the condenser, which in turn is connected to vacuum pump to vent out the non-condensables ensuring smooth operation of the MEE plant. In same manner, non-condensables from jacket of ATFD (104) can be vented out.
In prior art, vapour generated in the ATFD (104) of the integrated MEE-ATFD system is taken to a separate condenser for condensing it to water, or it is vented out to the atmosphere leading to evaporation loss. In the system of the present disclosure, the evaporation losses are not only avoided, but the steam economy is significantly improved. Overall live steam consumption of the evaporation system according to the present disclosure is significantly lower leading to lower operating costs and a more energy-efficient system. The proposed processes offer the benefit of reduction of live steam consumption irrespective of heat exchanger types or design configurations. The flash vessel design also vary based on the type of heat exchanger and do not have any impact on the outcomes of the proposed processes.
The present disclosure is further described in the light of the following experiments. Experiments are set forth for illustration purpose only, which are not to be construed for limiting the scope of the disclosure. The following laboratory experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial/commercial scale.
Applications: All applications which involve combination of steam-based as well as non-water vapor based multiple effect evaporation system and dryer system. Such applications are used in the following industries:
Zero liquid discharge systems for waste water treatment industries
Sugar industries
Distillery industries
Food industries
Chlor-alkali plants
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises”, “comprising”, “including” and “having” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
When an element is referred to as being “mounted on”, “engaged to”, “connected to” or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as “inner”, “outer”, “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a thermal evaporation system for solvent and solute recovery which:
is more energy-efficient;
has lower steam consumption;
is compact; and
is economical.
The foregoing disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:WE CLAIM:
1. A thermal evaporation system (100) for seprating solute from a solute-solvent mixture comprising:
a. an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration;
b. an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102);
c. a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration;
d. a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system; and
e. a thermocompressor (108) configured to receive said vapors generated by said dryer from said recirculation conduit(110) and a live steam stream (114) from an external source and wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module.
2. The thermal evaporation system (100) as claimed in claim 1, wherein a recompressor (112) is placed between said dryer(104) and said thermocompressor (108) such that said recirculation conduit (110) is split into a first part (110a) and a second part (110b), wherein said first part(110a) carries the vapors generated by the dryer (104) to said recompressor (112) wherein said recomprssor compresses said vapors which are then received by said thermocompressor through said second part (110b).
3. A thermal evaporation system (200) for seprating solute from a solute-solvent mixture comprising:
a. an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration;
b. an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102);
c. a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration;
d. a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system; and
e. a thermocompressor (108) configured to receive said vapors generated by said dryer from said recirculation conduit (110) and a live steam stream (114) from an external source and wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said dryer (104) through an inlet (126) of said dryer (104).

4. The thermal evaporation system (200) as claimed in claim 3, wherein a recompressor (112) is placed between said dryer(104) and said thermocompressor (108) such that said recirculation conduit (110) is split into a first part (110a) and a second part (110b), wherein said first part(110a) carries the vapors generated by the dryer (104) to said recompressor (112) wherein said recompressor compresses said vapors which are then received by said thermocompressor through said second part (110b).
5. A thermal evaporation system (300), for seprating solute from a solute-solvent mixture comprising:
a. an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration;
b. an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102);
c. a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration;
d. a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system; and
e. a recompressor(112) configured to receive said vapors generated by said dryer from said recirculation conduit (110) and compresses said vapors and circulates them to said dryer (104) through an inlet (126) of said dryer (104), wherein said vapors are mixed with a stream of live steam (190) before they enter the inlet (126).
6. A thermal evaporation system (400) for seprating solute from a solute-solvent mixture comprising:
a. an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration;
b. an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102);
c. a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration;
d. a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system;
e. a first thermocompressor (108) configured to receive a partial portion said vapors generated by said dryer (104) from said recirculation conduit(110) and a live steam stream (114) from an external source and wherein said first thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module ; and
f. a second thermocompressor (108’) configured to receive a partial portion of said vapors generated by said dryer from said recirculation conduit (110’) and a live steam stream (114’) from an external source and wherein said thermocompressor (108’) supplies a compressed mixture of said steam and vapors to said dryer (104) through an inlet (126) of said dryer (104).

7. The thermal evaporation system (400) according to claim 6, wherein wherein a recompressor (112’) is placed between said dryer(104) and said thermocompressor (108’) such that said recirculation conduit (110’) is split into a first part (110a’) and a second part (110b’), wherein said first part(110a’) carries a partial portion of the vapors generated by the dryer (104’) to said recompressor (112’) wherein said recompressor compresses said vapors which are then received by said thermocompressor (108’) through said second part (110b’).
8. A thermal evaporation system (500) for seprating solute from a solute-solvent mixture comprising:
a. an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration;
b. an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102);
c. a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration;
d. a recirculation conduit (110) configured to recirculate vapours generated by said dryer (104) within said system; and
e. a recompressor(112’’) configured to receive a partial portion of said vapors generated by said dryer (104) from said recirculation conduit (110’’) and compresses said vapors and circulates them to said dryer (104) through an inlet (126) of said dryer (104), wherein said vapors are mixed with a stream of live steam (190) before they enter the inlet (126).
9. A thermal evaporation system (600) for seprating solute from a solute-solvent mixture comprising:
a. an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration;
b. an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102);
c. a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration;
d. a first recirculation conduit (110a) and a second recirculation conduit (110b) for circulating vapors generated by said dryer in the system;
e. a first recompressor (112) that receives a partial portion of the vapors generated by the dryer (104) through said recirculation conduit 110a wherein said first recomprssor compresses said vapors;
f. a first thermocompressor (108) configured to receive the compressed vapors from said first recompressor through said second recirculation (110b) conduit and a live steam stream (114) from an external source ,and wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module; and
g. a second thermocompressor (108’) configured to receive a partial portion of said vapors generated by said dryer from said recirculation conduit (110’) and a live steam stream (114’) from an external source and wherein said thermocompressor (108’) supplies a compressed mixture of said steam and vapors to said dryer (104) through an inlet (126) of said dryer (104).

10. The thermal evaporation system (600) as claimed in claim 9, wherein wherein a second recompressor (112’) is placed between said dryer(104) and said thermocompressor (108’) such that said recirculation conduit (110’) is split into a first part (110a’) and a second part (110b’), wherein said first part(110a’) carries a partial portion of the vapors generated by the dryer (104’) to said second recompressor (112’) wherein said recompressor compresses said vapors which are then received by said thermocompressor (108’) through said second part (110b’).
11. A thermal evaporation system (700) for seprating solute from a solute-solvent mixture comprising:
a. an evaporator module (102) configured to concentrate a solute-solvent mixture by evaporating solvent from said mixture to provide a concentrated solute-solvent mixture of a first concentration;
b. an effluent tank (106) configured to supply said solute-solvent mixture to said evaporator module (102);
c. a dryer (104) configured to further concentrate said concentrated solute-solvent mixture of said first concentration and provide a solute-solvent mixture of a second concentration;
d. a first recirculation conduit (110a) and a second recirculation conduit (110b) for circulating vapors generated by said dryer in the system;
e. a first recompressor (112) that receives a partial portion of the vapors generated by the dryer (104) through said recirculation conduit 110a wherein said first recomprssor compresses said vapors;
f. a first thermocompressor (108) configured to receive the compressed vapors from said first recompressor through said second recirculation (110b) conduit and a live steam stream (114) from an external source ,and wherein said thermocompressor (108) supplies a compressed mixture of said steam and vapors to said evaporation module (102) through a heating fluid inlet (116) of said evaporation module; and
g. a second recompressor(112’’) configured to receive a partial portion of said vapors generated by said dryer (104) from said recirculation conduit (110’’) and compresses said vapors and circulates them to said dryer (104) through an inlet (126) of said dryer (104), wherein said vapors are mixed with a stream of live steam (190) before they enter the inlet (126).

12. The thermal evaporation system according to any of the preceeding claims, wherein said evaporator module (102) is a multieffect evaporator module (MEE).

13. The thermal evaporation system according to any of the preceeding claims, wherein said dryer (104,104’) has a rotary air lock valve to minimize air ingress.

13. The thermal evaporation system according to claim 12, wherein said evaporator module (102) comprises a plurality of evaporation stages.

14. The thermal evaporation system according to claim 12, wherein said first concentration is upto 40% dry.

15.The thermal evaporation system according to claim 12, wherein said second concentration is upto 100% dry.

Dated this 25th day of September, 2019

MOHAN DEWAN, IN/PA-25
of R.K. DEWAN & COMPANY
APPLICANT’S PATENT ATTORNEY


TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI