WO2015025334A2

WO2015025334A2 - Spray modular evaporator

Info

Publication number: WO2015025334A2
Application number: PCT/IN2014/000534
Authority: WO
Inventors: Vivek Verma
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-08-21
Filing date: 2014-08-21
Publication date: 2015-02-26
Anticipated expiration: 2016-02-21
Also published as: WO2015025334A3

Abstract

The spray modular evaporator comprising of plate heat exchanger with entrainment separator equipped vertically in a novel configuration forming a unique multi-effect evaporator to utilize the waste and low temperature vapours or steam of steam turbines, pans & evaporators in sugar, food, process, power plant and other processing industries or any degraded vapours form any process. The spray modular evaporator arranged for expanding heating surface by joining each effect or more effects in series or parallel combination for expanding in the same effect or combinations for additional effects without use of vapour piping and pumping.

Description

SPRAY MODULAR EVAPORATOR

FIELD OF INVENTION

Spray modular evaporator relates to unique multi-effect evaporator comprising several plate heat exchangers essentially vertically equipped with entrainment separator to utilize the waste vapours or steam (low temperature vapours) of steam turbines, pans & evaporators in sugar, food, power plant and other processing industries.

BACKGROUND TO THE INVENTION (PRIOR ART)

Evaporation is an operation used to remove a liquid from a solution, suspension, or emulsion by boiling the liquid. Evaporators are important in process industries for concentrating the solution like cane juice etc. Typically vessels like Falling and Rising Films Evaporators are used in vertical orientation as tubular heating surface and occasionally as plate form. Falling film evaporators can be operated with very low temperature differences between the heating media and the boiling liquid, and they also have very short product contact times, typically just a few seconds per pass. In a rising film design, liquid feed enters the bottom of the heat exchanger and when evaporation begins, vapour bubbles are formed. As the product continues to flow either in tubular or plate channels the evaporation process continues, vapour occupies an increasing amount of the channel. Evaporation starts as feed material falls as a film on tubes on the inner surfaces of calandria tubes. Vapour-liquid separation usually takes place at the heated surface, although some evaporators of this type are arranged for vapour to rise through the tube counter-currently to the liquid.

A plate evaporator of the rising film type and/or the falling film type comprises several heat exchange plates essentially vertically arranged in spaced face-to-face relationship to define evaporation passages alternating with heating medium passages. Evaporation passages with increasing cross-sectioned area and decreasing perimeter in the flow direction of the feed liquid are formed by providing adjacent plates encompassing one evaporation passage with bulges (for example, ridges) which bulges, compared with imaginary planar plates, entail reduced volume of the evaporation passages. The size of said bulges (that is, the volume-reducing effect of said bulges) is gradually reduced in the flow direction of the medium to be evaporated. Thus, the cross-sectional area of the evaporation passages is increased while their perimeter is reduced in said direction (US4586565).

A falling film evaporator includes a shell with a number of heat transfer elements within the shell. Each heat transfer element has two opposed essentially rectangular plates joined together along upright sides and along seams substantially parallel to the upright sides. The seams form with each other, and the upright sides, a number of vertical flow channels through which steam (heating fluid) flows in the interior of the heat transfer elements to evaporate evaporable liquid flowing downwardly in a film over the outer surfaces of the heat transfer plates. (US5837096)

The steam-heated evaporator or thickener is especially suitable for sea water or sugar beet juice. Its plate heat exchangers accept pre-distributed fluid flow from above, which falls as a film on the inner surfaces of vertical channels within, hence being heated in cross- and counter-current flow. (EP0780146).

In a plate evaporator of the falling film type, every second plate interspace constitutes an evaporation space (28) in which evaporation liquid is distributed across the width of the plates in order to run downwardly on the plates, whereas the rest of the plate interspaces constitute condensation spaces (30) for a heat emitting vapour. The invention concerns a particular arrangement for supplying evaporation liquid to the evaporation spaces (28). According to this arrangement, a distribution chamber (27) is delimited within the uppermost part of each plate interspace constituting an evaporation space (28). This distribution chamber extends across the whole width of the plates and communicates with an inlet channel for liquid, extending through the plate package and formed by aligned openings (16) in the plates. In the upper part of each condensation space (30), several sealing means (25) are arranged horizontally spaced from each other. Each sealing means (25) forms together with the two adjacent plates a transferring chamber (29) that is closed from the condensation space (30), but through small holes (17, 1 8) in the plates communicates with at least one distribution chamber (27) and one evaporation space (28). Heat emitting vapor may flow into each condensation space (30) from above through the gaps formed between the horizontally spaced sealing means (25). (US5203406).

Patent No. GB520064A titled 'Improvements in and relating to Multiple Effect Evaporation Processes and Apparatus for Juices and other Liquids' is clarified or semi- clarified cane and beet root juices and similar liquids.

Patent No. WO2006/07433 1 A2 titled 'Distillation Process' is an improvement distillation process to optimize production of distillate from water.

Patent No. WO00/44467 titled 'Multiple Effect Plate Evaporator and Tray Therefor' is made by number of effects (# 1 , #2, ...) each effect ( 1 5) in turn being made up of a plurality of horizontally disposed trays arranged in a form of stacked plates to form a heat exchanger.

Patent No. US 2007015 1840A1 entitled 'Method and device for treating water' is a multi-effect falling-film evaporator, purified water for special purposes. In each effect, a steam phase and water phase is produced from the feed water. The steam phase is used for heating in the subsequent effect, whereby it condenses to product water, and the water phase becomes the feed stream for the subsequent effect.

Patent No. US 699038A entitled 'Multiple Effect' relates "to improvements in multiple effects for the evaporation or concentration of liquids or solutions in which the vapor of each preceding eifect is used for the further evaporation ineach succeeding effect. Patent No. US 2750999A entitled 'Multiple effect evaporator tower' has for an object to provide, in evaporator apparatus of the stated type, novel means for delivering hot vapor from a preceding to a succeeding evaporator chamber, including improved means for removing from the hot vapor, so delivered from a preceding to a succeeding evaporator chamber, any entrained liquid solution for recovery by return of the same to the solution in the preceding evaporator chamber, and also including improved means for discharging water of condensation from the heater drums of the evaporator chambers.

The uniform distribution of the feed liquid is achieved by use of specially designed distribution devices whose proper functioning is decisive to the operational safety of the heat exchanger. Numerous structures and devices are known for improving the distribution of the liquid, such devices generally being placed either on the top of tube bundle or inserted or screwed into the tubes. In the former type of distributors i.e. liquid feed distributor mounted on top of the tube bundle, generally the liquid falls on the tube sheet and then flows into the tubes (flush welded with the tube sheet) in the form of a film. In many cases where the tubes protrude above the top tube sheet forming a collector or reservoir with top tube sheet acting as a base for the collector or reservoir, the feed liquid overflows over the upper edge of the protrusion which may be serrated or toothed. The protrusion may also be slotted or provided with grooves or borings or depressions or the like.

The fact that falling film evaporators operate at lower temperature difference, makes it possible to use them in multiple effect configurations systems in modern plants with very low energy consumption. In certain apparatus, multiple vertical tube bundles are stacked one above the other e.g. as in superimposed multi effect evaporators. In the evaporation and crystallisation process or in process of power generation, a lot of low temperature steam or vapours are generated which are to be condensed by condenser using cold water.

The uniform distribution of the feed is achieved by use of specially designed distribution system for proper functioning which is decisive to the operational safety of the heat exchanger. Numerous structures and devices are known for improving the distribution of the liquid, In such designs distributors are generally being placed either on the top of plate packs or tube bundle or inserted or screwed into the tubes.

Indian Patent Application No. 231 9/DEL/2012 suggests that a modular heat exchanger assembly comprising of heat exchange plate packs modules and entrainment separator arranged horizontally in a novel configuration forming a unique multi effect evaporator. The modular heat exchanger assembly is arranged for expanding heating surface by joining each module or more modules in series for expanding in the same effect or in parallel combinations for additional effects without use of vapour lines.

The arrangements described in the prior art plate evaporators, the evaporation of juice suffer from the following disadvantages:

1. Requirement of large size vapour lines: The vapour lines are required to transfer of vapours from effect to effect are quite large since the specific volume of the steam is very large. This problem becomes even more challenging as we get down to very low pressure.

2. Higher energy losses: Conventional vessels vapours are collected from bottom after liquid separation has to be transported upward to join next vessel in the middle or upper side. Longer travel path leads to higher losses of energy.

3. Difficulties in removal of scale deposits by mechanical means: Besides being complex to make, the prior art evaporators are cumbersome to clean mechanically due to long tubes or plate packs stacked one above other. No automated cleaning is possible as tube length is either submerged in rising film evaporators or surface is not approachable in falling film configuration due to long length.

4. No flexibility to change: Each effect of present configuration have fixed heating surface and same cannot be easily expanded or split to smaller size in case of necessity. Similarly these effects have single vapour inlet and outlet which cannot be altered. 5. High Maintenance Cost: Due to evaporation at high temperature and pressure.

6. High Colour Formation: Due to evaporation at high temperature and pressure.

7. High Inversion Loss: Due to evaporation at high temperature and pressure.

The present invention obviates the drawbacks of the prior art by providing a spray modular evaporator of novel but simple construction. Evaporation gets shifted from high pressure range to low pressure range. The present invention is able to recover the heat from the waste vapours or steam of low temperature and low pressure of pans, evaporators, and turbines or exhaust steam, having very high specific volume and considerable enthalpy, instead of dumping it into the condenser. Spray modular evaporators are of compact design and separators are flanged directly to the plate packs with no interconnecting pipe-work. The low pressure boiling reduces inversion, lowers scale and colour formation with minimising sugar losses. It has increased power generation due to its merit to operate at reduced exhaust pressure and lower steam consumption which saves more fuel. This modular evaporators offer improved residence time since they carry less volume within the heat exchanger.

Features of spray modular evaporator:

• Sturdy construction

• Smooth functionality

• Excellent strength

• Requires less maintenance

• Excellent performance

Since the plate packs can be opened easily, surfaces can be inspected, individual plates can be changed if necessary, and the evaporation rate can be altered by adding or removing individual plates. OBJECTS OF THE INVENTION

The principal object of the present invention is to provide a spray module evaporator which operates as a multi-effect evaporator, is highly effective and uses waste thermal heat.

Another object of the present invention is to provide a spray modular evaporator which operates as a multi-effect evaporator and can be expanded by using modules in series or in parallel or both simultaneously.

Yet another object of the invention is to provide spray modular evaporator comprising of plate heat exchanger and entrainment separator arranged in a vertical configuration.

Yet another object of the innovation is to provide spray modular evaporator operating as a multi-effect evaporator in which the novelty resides in the specific arrangement of the heat exchanger modules.

Still another object of the invention is to provide spray modular evaporator which eliminates the use of vapour lines either for joining vessels or increasing heating surface of each effect or adding more effects to reduce heating consumptions.

Yet another object of the invention is to provide a spray modular evaporator which is expandable in single effect or multiple effects.

Still another object of the invention is to provide spray modular evaporator which is considerably compact owing to novel features.

SUMMARY OF THE INVENTION

The novelty of the invention lies in the configuration of the spray modular evaporator and specific arrangement of the plate heat exchanger and entrainment separator, resulting in synergistic beneficial effects which have not been disclosed in the prior art. Present invention provides a novel design of a spray modular evaporator operating as a multi effect evaporator which enables use of waste low temperature vapours or steam of steam turbines or similar devices, vacuum pans or evaporators. In the present invention, waste heat or vapours from pans, evaporators and exhaust turbines which have very high specific volume can be used for boiling of juice owing to the novel design of the spray modular evaporator. The plate packs of spray modular evaporator are stacked one above other keeping equal distance between each plate pack for simultaneous separation of generated vapours and leaving concentrated juice. Spray modular evaporator is arranged for expanding heating surface by joining each effect or more effects in parallel combinations without use of vapour lines. The present invention is used for movement of juice from top to bottom and transit of steam or vapours from one end to the other end to get progressive concentration which provides better heat transfer efficiency and easy transportation. The low temperature and low pressure evaporation reduces of heat losses through pan / evaporator / exhausted steam, reduces scaling, reduces steam and juice flash heat losses, reduces colour formation in juice, reduces consumption of steam / fuel % cane, reduces inversion at high temperature, reduces complicated bleeding schemes with minimising sugar losses. It improves final product quality and quantity due to low temperature and low pressure evaporation.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows the perspective view of the one effect with reference numbers of the invention.

Fig. 2 shows the triple effect with reference numbers of the invention.

Numbering Details:

100 - Spray Modular Evaporator

101 - Plate Pack i.e. Plate Heat Exchanger

102 - Entrainment Separator

103 - Feed Liquid Header or Juice Header 104 - Spray Nozzles

105 - Distributor Plate

106 - Feed Liquid Collector or Juice Collector

107 - Recirculation Pump

108 -Low Temperature and Low Pressure Pan Vapours, Evaporator Vapours, Turbines

Steams and the like.

109 - Condensate Header

1 10 - NCG Header

1 1 1 - Vapour Outlet

112 - Feed Liquid Spray of Juice Spray

E l - First Effect

E2 - Second Effect

E3 - Third Effect

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE DRAWINGS

The present invention is directed to provide an apparatus for low pressure evaporation novel but simple construction in which the novelty lies in specific synergistic arrangement of different components, resulting in beneficial effects of better energy efficiency, compactness of size, economy of construction, transportation and operation and greater structural integrity.

This has been made possible by incorporating the precise specific synergistic arrangement in the construction of the apparatus:

The spray modular evaporator comprises of plate heat exchangers and entrainment separator arranged in a novel configuration forming a unique multi effect evaporator. In the preferred embodiment of the invention, each effect comprises of plate heat exchangers i.e. plate packs with entrainment separator arranged in a vertical configuration. The whole shape of the spray modular evaporator is rectangular, cylindrical or other shape also. The spray modular evaporator of the invention is arranged for expanding heating surface by arranging first effect to the second effect which is exactly similar to the first effect and third effect is exactly similar to the second effect. In each effect, the plate packs i.e. plate heat exchangers are stacked one above other in vertical axis keeping equal distance between the each plate pack. Each effect requires at least one plate heat exchanger i.e. plate pack and plate pack can be added upto any numbers in a single effect depending upon the requirement of the heating surfaces of the process. For the uniform distribution of the feed liquid spraying by spray nozzles from the top of plate pack of each effect, a specially designed distributor plate is arranged above the every plate pack, besides the top plate pack of every effect, whose proper functioning is decisive to the operational safety of the plate packs. The distributor plates which are horizontally laying over all the plate packs of each effect and it is joined to the entrainment separator or can be joined with a tapered plate and this tapered plate can be again joined with .the entrainment separator. Entrainment separator is used for the separation of entrained liquid droplets from vapours. Due to its alignment or tapered towards distributor plate, the collected feed liquid at entrainment separator of each plate pack flows easily towards distributor plates for uniform distribution. One side of the plate packs are for steam or vapour inlet which is low temperature and low pressure vapours of pans, evaporators and or exhaust steam and other side of each plate pack is entrainment separator which is common for all the plate packs of each effect. The open space between one plate pack to other plate pack which are stacked one above other of each effect is closed by entrainment separator and non-condensate gases (NCG) and condensate is collected separately in headers. A vertical entrainment separator is arranged which is common for all the plate packs of each effect as shown in the figure 1 . Keep some equal distance between each plate pack of each effect to entrainment separator of the same effect for slow striking of vapours or steam at entrainment separator for better condensation and NCG removal. But the entrainment separator of first effect is adjacent to the each plate pack of the second effect that means there is no space between entrainment separator of first effect to the plate packs of the second effect. The outlet steam or vapours through entrainment separator of each plate pack of each effect is passing to the next effect of corresponding plate pack of the spray modular evaporator. Steam inlet and outlet flanges are arranged in this structure. For expanding the heating surfaces, more effects can be added in parallel or series combinations as per requirement of the process. Inlet vapours or steam flows from first effect to third effect for both reverse and forward flow direction. In reverse flow manner, the feed liquid is flow from third effect to second effect then second effect to first effect by controlling with control valve and in forward flow manner feed liquid flow from first effect to second effect then second effect to third effect automatical ly due to pressure differences.

According to fig. 1 to fig. 2, the feed liquid is pumped from bottom to the top by common juice header of third effect and sprayed by spray nozzles over the top of the plate pack of third effect. The vapours or steam of low . temperature and low pressure of pans, evaporators and of exhaust steams are fed to the each plate pack of the first effect and these vapours or steam passes through the entrainment separator of first effect to the correspond irig each plate pack of the second effect and then to the plate packs of third effect. The flow of low temperature and low pressure vapours or steam of pans, evaporators and exhaust steams or turbines steams are in forward direction. The feed liquid from top of plate pack of third effect is freely flow down towards the distributor plate laying above the second plate pack from the top of third effect and then over the distributor plate laying on the third plate pack from the top of the third effect due to gravity and so on. The successive concentration of feed liquid takes place at each plate pack of third effect due to temperature differences. The concentrated liquid is collected at the bottom of the last plate pack from the top of third effect and is again recirculated at the top of the third effect through recirculation pump by common juice header. The level of the liquid is controlled by the control valve. The partially concentrated juice is fed to spray by spray nozzles on the top of the plate pack of the second effect through common juice heater and level of the liquid is controlled by control valve. In the reverse flow of the feed liquid, the level of the liquid in each effect is controlled by the control valve but in forward flow of the feed liquid, no requirement of the control valve. The process liquid vapours of third effect exit through top and bottom portion of each plate pack of third effect and flow towards the entrainment separator portion of the third effect. The plate packs of the second effect are so arranged that the vapour outlet at the entrainment separator portion of first effect operatively become the vapour inlet at the plate pack portion of the second effect and the vapour outlet at the entrainment separator portion of the second effect become the vapour inlet of plate packs of the third effect and so on. The partially concentrated fed juice from the top of the plate pack of the second effect is flow downwards as similar manner in the third effect and collected at the bottom. Again the collected concentrated liquid is recirculated at the top of the second effect through recirculation pump by common juice header for successive concentration and partially fed to spray by spray nozzles at the top plate pack of the first effect and level of the liquid in first effect is controlled by control valve. The collected juice at the bottom of the first effect sent for the further evaporation and collected condensate and NCG from each effect removed through the headers. The outlet vapours or steam of plate packs through the entrainment separator of the third effect is collected in the common vapour line and sent for the condensation to the evaporative condenser.

The flow of the vapours from first effect to the third effect is in forward flow direction whereas the feed liquid flow through the third effect to the first effect i.e. in the reverse flow direction. The flow of feed liquid can also be arranged in the forward direction i.e. from first effect to the third effect without any control valve.

In this manner, the number of effects can be arranged giving the spray modular evaporator of the invention a step configuration. The effect may be added to increase the capacity of the evaporator effect. Similarly, the capacity of evaporator effect may be decreased by using lesser number of plate heat exchangers. Also plate heat exchangers of an evaporator effect may be isolated for maintenance or cleaning. The compact size of the heat exchanger effects allows for mechanical cleaning of the heating surfaces. Thus, the invention allows for varying processing capacities as per the operational or production requirements at the plant. Spray modular evaporator can have the load cell facility for the measurement of the scaling through the weight. In this way each effect or effects may be joined in parallel combination for expanding heating surface as per requirement of the process.

The novel design of the spray modular evaporator of the invention functioning as a multi- effect evaporator has the following significant technical and economic advantages over the existing knowledge:

1. Drastic reduction in vapour piping and pumping from one effect to another effect since vapour outlet of one effect operatively becomes the vapour inlet of the corresponding effect. The reduced travel distance and time of vapours in turn helps wresting pressure losses and hence save energy.

2. Arrangement of plate heat exchanger has significantly higher overall heat transfer coefficient values considering use for flexible plate heat transfer surface. The high heating surface density is due to plate configuration and easy approach to heating surface.

3. Recovery of waste vapour lost in conventional process from pans, evaporators and exhaust turbines and use for further application till the lowest possible sink temperature which further provides many other additional advantages.

4. Reduced scale formation due to low pressure as solubility of most calcium salts (responsible for scale formation) is higher at reduced temperature. The low pressure boiling reduces inversion and colour formation in processing heat sensitive liquids like sugar juice thereby minimising sugar losses. It also reduces frictional losses, enhances the natural draft at an increased velocity.

5. Increased condensing coefficient and flexibility to change;

6. Easy optimization of the heat transfer characteristics of the heat exchanger;

7. The novel design and modular structure of the evaporator enables easy transportation and assembly/disassembly. 8. The modular design enables usage of heat exchange of various effects as per the running capacity of the plant. The capacity of the multi-effect evaporator can be increased at any time by adding new plate heat exchanger.

9. The novel design enables online isolation and cleaning of the spray modular evaporator.

1 0. The novel design permits very convenient mechanical cleaning of heat exchange surfaces, a feature absent in most prior art multi-effect evaporators.

1 1. The novel design provides easy access to and maintenance of all parts and portions of the assembly.

12. The assembly is compact and also has lesser structural requirements for assembly and operation.

13. Greater structural integrity and reduced weight of the apparatus due to its modular structure and compact design.

14. Easy removal of condensate and non-condensable gases due to modular structure.

Example of Industrial Applicability

Various embodiments of the present invention will become apparent to persons skilled in the art upon reference to the description and drawings of the invention. It is contemplated that modification can be made without departing from the spirit and scope of the present invention as described. For example, in sugar industry, a considerable quantity of low pressure and temperature vapours or steam from the pans or evaporators or exhaust steam is rejected to the condensers. The spray modular evaporator gives the advantage of low pressure evaporator and also increases the progressive concentration of the juice. Means are provided to remove the concentrated liquid or juice or non-condensate gasses from the effects.

Referring to Figs. 1 to 2, the novel spray modular evaporator (100) using low temperature and low pressure vapours or steam of pans or evaporators or turbine comprising a plate heat exchanger i.e. plate pack ( 101 ) with an entrainment separator (102) arranged in vertical configuration. The low temperature juice from juice header (103) is sprayed on the plate pack (101) by spray nozzles (104) of the third effect of spray modular evaporator. The juice fell down on the distributor plate (105) of second plate pack from the top of the third effect as per the arrangement of the apparatus and then to the distributor plate (105) of third plate pack from the top of third effect. While following down the feed juice from top to bottom of the plate pack its brix/concentration and temperature rises. The heat required for this purpose is supplied by the vapours generated in second effect. The part of the collected juice (106) at the bottom of the last plate packs (101 ) is again pumped by recirculation pump (107) through the juice header (103) for spraying over the top plate pack (101 ) of third effect for progressive concentration of juice. The part of relative concentrated juice of the third effect is fed to the top plate pack (101) of the second effect. The collected juice from the last plate pack of second effect is again sprayed by spray nozzles (104) on the top of the plate pack of second effect and partially fed to the top plate pack of the first effect. In general, juice keeps on flowing from the previous effect to next prime effect and there is rise in brix/concentration and temperature in every effect. The low temperature vapours or steam of pans and/or evaporators and/or exhaust or turbines (108) is supplied to the each plate pack (101 ) of the first effect which evaporates the juice and condensed. While evaporating the juice the inlet vapours (108) condensed due to low temperature juice and the generated juice vapours flows upward and down ward direction from each plate pack ( 101 ) and out through the entrainment separator ( 102) of first effect. The condensate is collected in the condensate jacket (109) and non-condensate gas (NCG) is collected in the NCG jacket (1 10) as shown in figure 1 to 2. The vapour outlet of entrainment separator (102) of first effect is connected with vapour inlet of plate pack (101 ) of second effect. Juice from the juice header is sprayed over the plate pack of second effect by spray nozzles or other distribution means and condensate and non-condensate gas are collected in the headers. The vapour outlet (1 1 1) of entrainment separator of second effect is connected with vapour inlet of plate pack of third effect. The vapour outlet (1 1 1 ) of entrainment separator of third effect is connected to the evaporative condenser. This process is fully automated. We can expand the effects also as per requirement of the heating surface for the condensation of the vapours and juice evaporation. Finally the juice, after passing through third and second effect, is taken out from the first effect where concentration and temperature reaches to 25-30% and 50°C respectively. This thick clear juice of first effect of spray modular evaporator further fed to conventional evaporators through series of clear juice heaters so as to raise it temperature to operating temperature of the first effect of conventional evaporator set. Rest of the desired juice concentration level is achieved here in the conventional evaporators. Alternatively, the spray modular evaporators can be arranged in suitable number of effects that all the desired level of concentration can be achieved through spray modular evaporators only.

Each similar effect is joined in parallel or series combination to increase heating surface and capacity of individual effect or to increase number of effects as per requirement of the process without use of additional vapour piping and pumping. This enables use of low temperature vapours or steam of pans or evaporators or turbines having very high specific volume instead of letting it into the condenser thereby utilising the enthalpy of vapours in the boiling of juice at low temperature. This low temperature boiling reduces inversion, lower scale formation and colour formation to minimise sugar losses as aforesaid.

Besides the application of the spray modular evaporator of the invention in the sugar industry for low temperature evaporation of juice using low temperature vapours or steam of pans or evaporators or exhaust steam this apparatus can be used in power plant, waste water treatment, municipal waste water treatment, food processing industries like milk & chocolates, fruit processing industries like packed juices, refrigeration of air conditioning, industrial effluent treatment plant with contemplated modification and without departing from the spirit and scope of the present invention.

Claims

I CLAIM

1. A spray modular evaporator apparatus for multi-effect evaporation or concentration of feed liquid using low temperature or degraded vapours of pans, evaporators, turbines and the like, the apparatus consisting:

means for heat exchange through plate or tubular heat exchangers with arrangement in vertical axis;

means for separation of entrained liquid droplets from vapours by entrainment separator;

means for recirculation of feed liquid through recirculation pump; means for continuous spraying the feed liquids through spray nozzles over the plate pack;

means for uniform feed liquid distribution through distributor plate over the each plate pack of each effect;

inlets for introducing low temperature pan vapours, evaporator vapours or exhaust steam and the like at the plate packs of the first effect in reverse or forward flow manners;

inlet for feeding of feed liquid in third effect to second effect, then second effect to first effect by controlling through control valve in reverse flow manner

inlet for feeding of feed liquid in first effect to third effect automatically in forward flow manner;

outlet for vapours or steam from the third effect in reverse or forward flow manners;

outlet for continuously withdrawing thick juice from the bottom plate pack of each effect in reverse flow manner;

outlet for continuously withdrawing thick juice from the bottom plate pack of third effect in forward flow manner;

means for removal of non-condensable gases (NCG) from each plate pack in NCG header and means for removal of condensate from each plate packs through condensate header; wherein the said spray modular evaporator of one or more similar effects each of which contains at least one plate heat exchanger and an entrainment separator arranged vertically in specific synergistic arrangement.

2. The spray modular evaporator as claimed in claim 1 wherein the plate packs (101) are arranged in such a way that the feed liquid flows from top to bottom under gravity.

3. The spray modular evaporator as claimed in claim 1 wherein the vapours or steam flows first effect (El ) to second effect (E2) and second effect (E2) to third effect (E3) in forward flow direction and outlet vapours ( 1 1 1) of third effect (E3) send to the evaporative condenser.

4. The spray modular evaporator as claimed in claim 1 wherein the feed liquid flow from the third effect (E3) to second effect (E2) and then second effect (E2) to first effect (El ) in reverse flow manner by controlling with control valve and outlet concentrated thick juice from first effect (E l ) is sent to the evaporators.

5. The spray modular evaporator as claimed in claim 1 wherein the collected feed liquid (106) at the bottom of the plate pack (101 ) of the third effect (E3), is pumped with recirculation pump ( 107) through the feed liquid header ( 103) for spraying the feed liquid (1 12) by spray nozzles (104) over the top plate packs (1 01 ) of third effect (E3) for progressive concentration of feed liquid and recirculation with same manner in second and first effects.

6. The spray modular evaporator as claimed in claim 1 wherein the collected feed liquid (106) at the bottom of the third effect (E3), is partially pumped through the feed liquid header (1 03) for spraying by spray nozzles over the top plate pack (101 ) of the second effect (E2) by controlling the levels of the feed liquid in each effect with control valve in reverse flow manner and so on.

7. The spray modular evaporator as claimed in claim 1 wherein the collected feed liquid ( 106) at the bottom of the first effect (El ) is pumped through the feed liquid header (103) for spraying by spray nozzles over the top plate pack (101) of the second effect (E2) and then second effect (E2) to third effect (E3) automatically in forward flow manner due to pressure difference and outlet vapours (1 1 1) from third effect (E3) sent to the evaporative condenser.

8. The spray modular evaporator as claimed in claims 1 to 7 wherein the distributor plate (105) for each plate pack (101 ) of each effect is for uniform feed liquid distribution and condensate is collected in condensate header (109) and non- condensate gas are collected in the NCG header ( 1 10) at the bottom of the plate pack ( 101 ) of each effect.

9. The spray modular evaporator as claimed in claims 1 to 8 wherein each similar effect contains at least one plate heat exchanger (101 ) and entrainment separator

(102) is joined in parallel or series to increase the number of similar effects as per requ irement of heating surfaces of the process.

10. The spray modular evaporator as claimed in claims 1 to 9 wherein the said apparatus is using in the utilization of the waste energy of the plant.