GB2440159A

GB2440159A - Dual vacuum trap freezer for the recovery of heavy water vapour in which air exists

Info

Publication number: GB2440159A
Application number: GB0623190A
Authority: GB
Inventors: Mohammad Sharafi; Mostafa Sharafi
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-11-22
Filing date: 2006-11-21
Publication date: 2008-01-23
Also published as: GB0623190D0

Abstract

A dual vacuum trap freezer (DVTF) for the recovery of heavy water (D2O) vapour in which air exists is located between a distillation plant and a high vacuum steam ejector. The dual vacuum trap freezer comprises twin alternating units 'A', 'B' for continuous operation of the recovery process. Each unit includes three complete refrigeration systems and a common vacuum chamber 13 divided into three zones. Each zone is associated with a group of refrigeration coils connected to one of the refrigeration systems and is equipped with a drain pan for condensate removal. The first zone (Zone no.1) comprises a group of dehumidifying coils; the second zone (Zone no.2) comprises a group of freezing coils; the third zone (Zone no.3) comprises a group of deep freezing coils. A static defrost system removes accumulated ice on the freezing coils and deep freezing coils. A daily heavy water condensate receiver 26 collects the condensate from each of the drain pans. An exit system returns the collected condensate under vacuum conditions to a main process line of the distillation plant. A control panel 50 optimises the operational conditions through the dual vacuum trap freezer. Preferably, the control panel comprises a direct digital control system with a microprocessor employing predetermined control algorithms.

Description

1 2440159 Process for Recovering of Heavy Water Vapor, D20, in which

Air exists, by Means of Refrigeration Cold Trap "DVTF" at Vacuum condition

Background of the Invention

Field of the Invention

This invention relates generally to dehumidifying process of air at high and very low dew points.

This invention is more particularly directed toward the recovery process of heavy water vapor content of air, by means of dehumidifying and freezing system.

Description and Discussion of the Prior Art

Dehumidification is the reduction of the water content of air, gases, or other fluids.

Regarding to prior and present industry practice, the term dehumidification is normally limited to equipment that operates at essentially atmospheric pressures and is built according to the industry standards. In present industry various methods of dehumidification such as Compression, refrigeration, liquid sorption and solid sorption or combinations of these systems are employed. In present industry that depends on requirements of the final dew point, the removal of moisture is accomplished by cooling alone, with sorption, or both. Refrigeration of the gas below its dew point is the most common method of dehumidification. This method is advantageous when the gas is comparatively warm, has a high moisture content, and outlet dew point desired is above 45 F (5 c). Frequently, refrigeration is used in combination with sorption (solid/liquid) dehumidifiers, in order to obtain an extremely low dew point of minimum cost.

In present industry, refrigeration or other cooling means are often supplied as a supplement to the desiccant dehumidifier, in series, in order to remove excess moisture and provide the desiccant bed with air having a higher relative humidity and lower temperature.

Thus, some moisture is removed at high dew points, where refrigeration is more economical, and the desiccant dehumidifier at its most efficient operating condition and very low outlet humidity removes the remainder.

Some of the more important commercial applications include the following: -Lowering the relative humidity to facilitate manufacturing and handling of hygroscopic materials.

-Lowering the relative humidity caused to prevent condensation on products manufactured in low-temperature process.

-Providing protective atmospheres for the heat treatment of metals.

-Maintaining controlled humidity condition in warehouses and caves used for storage.

-Preserving ships and other surplus equipment which would otherwise deteriorate.

-Numerous static applications in which a dry atmosphere must be maintained in a close space or container, such as the cargo hold of a ship.

-Condensation and corrosion control.

-Drying air for wind tunnels.

-Drying natural gas.

-Drying of gases which are to be liquefied.

-Drying of instrument air and plant air.

-Drying of process and industrial gases.

* Dehydration of liquids.

In accordance with the present invention, the removal of high moisture (D20 vapor) content of air, is accomplished by cooling alone, with desired high, and very low dew point for entire recovery process to recover the product (D20 water), there after to be collected in the condensate receiver with high purity and maximum recovery at high vacuum condition.

Therefore, the prior industry compared with present invention in both, refrigeration alone, or in combination with sorption dehumidifiers could not be justified, for the most important following reasons: By way of this explanation, I disadvantage of the existing refrigeration or other cooling means alone, without combination with sorption dehumidifiers, is limited to the equipments with high dew point, at which a minor total amount of moisture content of air compared with present invention is condensed, and the liberated air with remainder moisture leaves the refrigeration system either, direct to a process line, or to desiccant dehumidifiers, and then to process line, depending on required dew points to be used. As a result, none of the both processed items mentioned above (the minor total amount of moisture, or dried air) are corresponded to the recovery process of the present invention.

disadvantage of the existing refrigeration or other cooling means in combination with sorption dehumidifiers which produce, high an low dew points, is the absorbed vapor by desiccant dehumidifier, from which finally, exhausted in to atmosphere, and the dried air supplied to process line, when both of them are again, against the present invention novel desir.

3 disadvantage of the existing dehumidifiers is the performance of the existing refrigeration dehumidifiers in which it is much less than the present invention, for two reasons, first, there are some differences about know how applied between and, secondly, the complexity design and selected equipments, and materials to provide the objects of the present invention.

4th disadvantage of existing dehumidifier is its operation at atmospheric condition, compared with present invention that can be on operation both, either atmospheric or until high vacuum condition.

5th disadvantage of existing dehumidifier, is the difference and non sensitive of its pressure drop of air flow through the entire system, compared with the present invention in which there is so accurate and sensitive pressure drop to effect the steady state of main process line condition during operation, and recovery process in vacuum chamber of DVTF, for heavy water vapor, particularly at high vacuum condition, if it tends to vary beyond the range of expected pressure drop value.

To show the difference between the said commercial applications of prior art and present invention's recovered product (D20), it is described some of the more important applications of heavy water, D20, as follows; Heavy water has a great similarity in its physical and chemical properties to ordinary water. But its nuclear properties display a significant variation that makes it an extremely efficient material for use as moderator in a nuclear reactor. During the last two decades, a major mention has been focused on application of D20 in medicine and industry, besides its usage in understanding reaction mechanisms in biological and physical sciences.

Objectives and Summary of the Invention

Objectives 1St Accordingly, it aims to provide a particularly cold trap equipped with dehumidifier and freezing coils which substitutes for the prior arts.

2 Object of the invention is to provide a vacuum chamber wherein series of cooling and freezing coils are disposed, for removal of high moisture (D20 vapor) content of air with puri,y quality and maximized performance at vacuum condition.

3 Object of the invention is to provide proper individual refrigeration systems, with a particular common vacuum chamber in which a series of multiplexed dehumidifying and freezing coils are placed, to maintain the appropriate and desired high, medium and very low dew points, used for removal of maximum moisture (over 96% of absolute humidity) content of the air.

4th Object of the invention is to provide a unique static defrost method in order to keep the original properties of product during defrost cycle, for changing the solid phase of accumulated frost and ice on freezing coils, to liquid with most simplified devices at vacuum condition.

5th Object of the invention is to provide a system for the condensate drips from dehumidifying and freezing coils, to be colleted and funneled in to a daily condensate receiver, where it is automatically emptied when the tank becomes full of condensate, in to the main process line of the distillation plant, because of gravity at vacuum condition.

6th Object of the invention is to provide a twin units construction for continuous operation recovery process.

7th Object of the invention is to provide a control panel ensures optimal operational condition through the refrigeration machine "DVTF"

Summary of the Invention

In present industry, refrigeration or other cooling means are often supplied as a supplement to the desiccant dehumidifier, in series, in order to remove excess moisture and provide the desiccant bed with air having a higher relative humidity and lower temperature. Thus, some moisture is removed at high dew points, where refrigeration is more economical, and the desiccant dehumidifier at its most efficient operating condition and very low outlet humidity removes the remainder.

As earlier said, the most important purpose of the existing refrigeration or other cooling mean alone in combination with sorption dehumidifiers, is the process of humidified air, in order to supply the dry air with required high or very low dew points, towards the commercial applications, while the separated moisture is not used for particular intended purpose, if it is not purged into atmosphere or condensed to be drained to waste.

There fore, none of the processed items (condensed moisture or, dried air) mentioned above, could provide the aim and objects of the present invention particularly, at vacuum condition.

In accordance with the present invention, the removal of high moisture (D20 vapor) content of air is accomplished by cooling alone, with high efficiency at desired high and very low dew point for entire recovery process; when the continuous saturated air from the distillations plant passes over the designed dehumidifying and freezing coils disposed in vacuum chamber.

In this case, (D20 water), is collected from either, the dehumidifying coils during refrigeration cycles or freezing coils during static defrosting cycle, in the daily condensate receiver with high purity, maximum efficiency and finally return back to the main process line of the distillation plant at vacuum condition, when the liberated air with extremely low absolute humidity and low temperature will be drawn by two-stage steam ejector system, and then, purged in to atmosphere.

The operable ejector produces both, a condition of high vacuum chamber at vacuum and predetermined conditions of vacuum at an umber of location in distillation plant.

For a continuous recovery process, the machine "DVTF" is designed as a twin alternating units (A&B) construction for continuous operation, thus, it is called. "Dual Vacuum Trap Freezer" The above brief description sets forth rather broadly the more important features of the present invention in order that the detailed description thereof that follows may be better understood. There are, of course, other features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily by utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present invention.

These together with still other advantageous objects of the invention with various features of novelty that characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its usages, reference should be had the accompanying drawing and descriptive matter in which there are illustrated preferred embodiments of the invention.

In this respect, before explaining the preferred embodiments of the invention in detail, it is necessary to be understood that the application of the invention is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawing. The invention has other embodiments and of being practiced and carried out in various ways.

Further, the purpose of the Abstract is to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, the Abstract is neither intended to define the invention or the application, which only is measured by the claims, nor it is intended to be limited as to the scope of the invention in any way.

Brief Description of the Drawing -Detailed Description of the Preferred Embodiment The invention will be better understood and the above objects as well as objects other than those set forth above will become more apparent after a study of the following detailed description thereof such description makes reference to the annexed drawing wherein: Fig 1, Schematic Diagram of Dual Vacuum Trap Freezer, "DVTF", existing between Distillation Plant & two-stage Steam Ejector, Process for Recovering of Heavy Water, D20 Description of the preferred embodiment. With reference now to the drawing, a new and improved cold trap "DVTF", embodying the principles and concepts of the present invention will be described.

Turning initially to Fig.1, the illustrated vapor recovery system is designed to recover the vapor (D20 vapor) present in the air entered through the inlet solenoid valve (34) of vacuum chamber (13) and expelled both, condensate water through the drain valve (27) to main process line of distillation plant and dry air through the outlet solenoid valve (35) of vacuum chamber toward the two-stage steam ejector, during process of producing heavy water in distillation plant. Thus, in the particular embodiment illustrated, the vacuum chamber (13) with the alternative vacuum chamber is connected, between, the distillation plant and two-stage steam ejector through their air manifolds.

For, a continuous recovery process of constant flow rate, in once thru application, with extremely low pressure drop, this package is designed for a twin alternating units (A&B) construction, named, Dual Vacuum Trap Freezer, "DVTF".

As shown in the Fig.1, the "DVTF" package (unit-A or B) for recovering process of heavy water vapor, has three single stage refrigeration systems, with a common vacuum chamber (13) in which, the multiplex coils related to each system are disposed. , won , system,, single stage compressor to the condenser pressure subsequently compresses the entire refrigerant leaving the multiplex evaporators. A refrigeration line (14-2) leads from the compressor (14), to the oil separator (14-3), to the check valve (14-4), to the air cooled condenser (17), to the head pressure control valve (17-1), to the receiver (20), to the sub cooled coil (20-1), to the refrigerant filter drier (20-2), to the solenoid valve (20-3), to the liquid sight glass (20-4), to the liquid manifold with four branches (20-5), there from, to the first branch expansion valve (1-1), to the dehumidifying coils, (1) to the Evaporator Pressure Regulating Valve, EPRV (1-2), also, to the second branch exp.v. (2-1), to the second dehumidifying coils, (2), to the EPRV (2-2), also to the third branch exp.v. (3-1) To the third dehumidifying coils (3), to the EPRV (3-2), also, to the exp.v. (4-1), to the forth dehumidifying coils (4), to the check valve (4-2). After the check valve and EPRV (S) to the suction manifold, (4-3), to the accumulator (14-1) and back to the compressor (14), for circulating a refrigerant through the first refrigeration system of zoon, of the unit (A).

Fig 1, zone 2, system 2, a refrigeration line (15-2) leads from the compressor (15), to the oil separator (15-3), to the check valve (15-4), to the air cooled condenser (18), to the head pressure control valve (18-I), to the receiver (21), to the sub cooled coil (21-1), to the refrigerant filter drier (21-2), to the solenoid valve (21-3), to the liquid sight glass (21-4), to the liquid manifold (21-5), there from, to the first branch capillary tube (5-1) as a refrigerant metering device, to the first freezing coil, (5) to the Evaporator Pressure Regulating Valve, EPRV (5-2), also, to the second branch capillary tube (6-1), to the second freezing coil, (6), to the EPRV (6-2), also, to the third branch capillary tube (7-1) to the third freezing coil (7), to the EPRV (7-2), also, to the forth branch capillary tube (8-1), to the forth freezing coil (8), to the check valve (8-2) . After the check valve and EPRV(S) to the suction manifold, (8-3), to the accumulator (15-1) and back to the compressor (15), for circulating a refrigerant through the second refrigeration system of zone 2 of the unit (A).

Fig 1, zone 3, system 3, A refrigeration line (16-2) leads from the compressor (16), to the oil separator (16-3), to the check valve (16-4), to the air cooled condenser (19), to the head pressure control valve (19-1), to the receiver (22), to the sub cooled coil (22-1), to the refrigerant filter drier (22-2), to the solenoid valve (22-3), to the liquid sight glass (22-4), to the liquid manifold (22-5), there from, to the first capillary tube (9-1), to the first deep freezing coil, (9) to the Evaporator Pressure Regulating Valve, EPRV (9-2), also, to the second capillaiy tube (10-I), to the second deep freezing coil, (10), to the EPRV (10-2), also, to the third capillary tube (11-1) to the third deep freezing coil (11), to the EPRV (11- 2), and to the forth capillary tube (12-I), to the forth deep freezing coil (12), to the check valve (12-2). After the check valve and EPRV (S), to the suction manifold, (12-3), to the accumulator (16-1) and back to the compressor (16), for circulating a refrigerant through the third refrigeration system of zone 3 of the unit (A).

Since, the recovery process requires refrigeration at more than one temperature; this could be accomplished by using a separate throttling valve and separate compressor for each coil operating different temperatures. However, such a system will be bulky and probably uneconomical. A more practical and economical approach would be to route all the exit streams from the refrigerated coils to a single compressor and let it handle the compression process for each zone of three systems.

In the system, zone; the common vacuum chamber comprises four the dehumidifying coils, (1), (2), (3), (4), to provide four different high desired dew points that the forth one is approach the freezing point. For removal of D20 vapor in the air, the continuous air flowing through the vacuum chamber passes over the dehumidifying coils, its temperature decreases and its relative humidity maintained at constant specific humidity. Due to the cooling of air through the dehumidifying coils, (1), (2), (3), (4), results in condensation of the majority portion of vapor in the air during the refrigeration cycle. Air remains saturated during the entire condensation process, which follows a line of nearly 100 percent relative humidity. Until the final coil (4) in zone, and the two next freezing coils will be reached.

The heavy water vapor that condenses out of the air during this process is removed from the dehumidifying section into drain pan where ills funneled in to a lower section where the daily condensate receiver is placed.

In the system 2, zone 2; the common vacuum chamber (13) comprises four freezing coils, (5), (6), (7), (8) to provide four different low desired dew points for frosting some other part of the remainder of D20 vapor in the air, coming from zoon 1. In this case, D20 vapor with high relative humidity and low temperature, in contact with freezing coils will tend to freeze on coils and causing more frost formation with expected thicker frost on freezing surfaces. There by, some other portion of D20 vapor will be recovered during airflow through the refrigeration system 2.

In the system 3, zone 3; the common vacuum chamber (13) comprises four deep freezing coils (9), (10), (II), (12), to provide four different very low desired dew points for deep freezing of any remainder of D20 vapor in the air, coming from zone 2 In this case, any remainder of 020 vapor with high relative humidity and very low temperature in contact with deep freezing coils will tend to freeze on coils and causing more ice formation with expected average thicker ice on freezing surfaces. There by, providing of that near complete D20 vapor recovery, over than 96% weight of absolute entering vapor content of air, is achieved and the dry air with a negligible amount of vapor and very low temperature would be liberated and drawn by two-stage steam ejector system; where being purged in to atmosphere.

Unexpected thicker ice ultimately leads to substantial reduction in the evaporators (freezing coils) capacity, systems efficiency, and a greater than expected pressure drop; there fore, removal of the frost or dc-icing of the freezing coils at regular intervals is an absolute necessity.

Due to the pressure drop, the flow metering device (42) or differential pressure control device (41) by the aid of micro processor in control panel, disconnects at once, the three refrigeration systems (1, 2, 3), and gradually close the inlet (34) and outlet (35) opening of the vacuum chamber of unit "A" and open the inlet and outlet opening of the vacuum chamber of unit "B" at the same time, for continuation of the recovery process. In the mean while the unit "A" will be put on defrost operation.

Fig 1, unit "A" illustrates a static defrost cycle which is automatically started when ever microprocessor sometimes senses unexpected value by airflow metering or differential pressure control devices and a number of actions take place: The three refrigeration cycles of the unit are stopped and the inlet solenoid valve (34), and outlet solenoid valve (35), of vacuum chamber are completely closed. The discharge liquid brine solenoid valve (31), to jacket brine (13-2) mounted on the bottom of the vacuum chamber is opened. Instantly, the warm brine, from insulated (28-4) circulating tank (28) fills up the jacket brine (13-2) by gravity force and the air inside the jacket brine (13-2) is purged in to atmosphere through the axillary's air vent (13-2-1) when the jacket is filling up with the warm brine. There after, the circulator brine pump (30) starts the defrost process and circulates the warm brine through the jacket brine (13), evacuated pump (32), check valve (33), and back to the circulating tank (28). The circulating tank as a source of energy, includes a thermostatic electrical heater element (28-1) to heat and control the brine circulation, under varying temperature condition of defrost operation.The circulating tank further including an air vent pipe (28-3) to atmosphere.

During warm brine circulation through the jacket brine (13-2), the energy is first transferred to the air layer adjacent to the interior surface of vacuum chamber by conduction, and then carried away from the surface to the accumulated ice surfaces on freezing coils by convection without any external means such as a fan or wind. There fore, this convection is called free or natural convection; caused by buoyancy forces induced by density differences due to the variation of temperature in the air. In this manner during defrost, the free convection due to the buoyancy forces will increase the amount of heat available to remove the accumulated ice (dc-icing) from the freezing coils in form of condensate drips in to the condensate pan (drain pan) where by funneled in to daily condensate receiver. A thermostat (40) mounted with in the vacuum chamber is set to sense arise in the temperature of the finned surface of the deep-freezing coils. A temperature of 40F (4.4 c) indicates the removal of frost and automatically returns the unit (A) to the post-defrost period. The post -defrost period starts as follows; the circulator brine pump (30) is stopped, the discharge liquid brine solenoid valve (31) to jacket brine (13-2) is closed, the evacuated pump (32) to circulating tank (28) starts empting of brine from the jacket brine (13-2) through the check valve (33) in conjunction with vacuum breaker line (28-5) to circulating tank (28). The three refrigeration cycle systems (1, 2, 3) start for a short time to re-condensed and freeze any little left heavy water vapor on refrigerated coils to prevent it leaving the vacuum chamber toward the two-stage steam ejector during the next start; and decrease the interior space temperature (corresponding in pressure) of vacuum chamber until the initial vacuum condition, is achieved, then the three refrigeration systems are stopped. There after this unit "A" will stay as a stand by of unit "B" for another start up.

According to the quality management for the highest possible quality in the production (heavy water), it is emphasized the importance of careful facing the frozen product (D20 iced) with indirect heating for removal of accumulated ice on freezing coils. There fore, heated air as described above, is the defrosting medium in this situation; and since there is no forced circulation of air, i.e. free convection it is called in particular "static" defrost system which is quite suited design for the closed sealed vacuum chamber, in response to this particular design.

Fig, Daily condensate receiver and drain system is shown. This system is used to receive condensate drips from refrigerated coils drain pans (25-1), (24-1), (23-I), through the check valves (25), (24), (23), in to daily condensate receiver, by gravity. The system in-clued; a recovery tank or well insulated daily condensate receiver (26), in which a float ball (26-1) is placed, the electric float switch (26-4) in connection with float ball, the D20 level indicator (26-1), an equalizer pressure solenoid value (27-1) and an outlet solenoid valve (27). The usual operation is as follows: the condensate drips from dehumidifying (25-1) and freezing (24-1) (23-1) drain pans funneled through the check valves (25), (24), (23), by gravity; when the condensate receiver (26) is nearly filled, the float ball (26-3) rises and makes the electrical circuit of float ball switch (26-4) and by the aid of micro processor which operates both together, the solenoid valve (27) in the outlet liquid line and the solenoid valve (27-1) in the equalizer pressure line, to flow of the condensate drips easily, into the main process line of the distillation plant, when the condensate receiver (26) is emptied, the float ball falls to low level of condensate in the receiver and breaks the electrical circuit of float ball switch (26-4) by aid of microprocessor which operates the solenoid valves (27), and (27-1) to be closed. Operation is accomplished during defrosting cycle.

Fig 1, illustrated the control panel, (50), which is a system using Direct Digital Control (DDC) involves adopting a microprocessor according to predetermined control algorithms.

The system can analyze and perform calculations from the sensors both digital and analog input signals i.e. in the form of continuous variable output from the microprocessor is either in digital form to actuate dampers, valves and relays or converted to analog signal to operate the actuators. Consequently; the control panel system ensures optimal operational condition through the DVTF package, and incorporates functions for monitoring, regulation and recording to meet varying process requirements; in this case, programming is carried out with the aid of microprocessor.

These are some of the functions as follows: * Data logging of all machinery operation and recovery process parameters * Large format screen display (monitor) * Communications with remote displays, printers and computers (via modem) * Automatic control of start up and shut down sequences * Micro processor based for maximum reliability * And many more

Claims

Claims 1. A Dual Vacuum Trap Freezer; "DVTF" is a package for process

recovering of heavy water vapor in which air exists, under vacuum condition, placed between a distillation plant and a high vacuum steam ejector, the package "DVTF" comprising: a twin units (A&B) construction for continuous operation recoveiy process, each said unit including three complete multiplexing refrigeration system, a common vacuum chamber divided to three zones (1,2,3) each said zone is earmarked for a group of refrigerated coils connected to one of the said refrigeration system and also equipped with a drain pan, each said refrigeration system includes useful accessories means together by means of directing refrigerant from the single stage compressor in to the air cooled condenser, the receiver, the group of dehumidi1'ing coils (zone-I), or the group of freezing coils (zone-2), or the group of deep freezing coils(zone-3), and back to the compressor, said useful accessories means such as refrigerant metering devices and controls for safety reasons, to enhance the operation characteristics of said system or to facilitate service, said vacuum chamber in which, the once through continuous saturated air passes over the said refrigerated coils, a "static" defrost system for removal of accumulated ice on said refrigerated coils zones 2&3, a daily heavy water condensate receiver to collect the condensate drips from said three drain pans, an exit means system for returning back the condensate drips from condensate receiver in to main process line of said distillation plant under vacuum condition, a control panel ensures optimal operational condition through the "DVTF".

2. The invention of claim I wherein said each multiplexing refrigeration system includes one air cooled condensing unit and several said coils connected to the same single stage compressor with no capacity control, the entire refrigerant leaving the multiplex said evaporators is subsequently compressed by said single stage compressor to the said air cooled condenser pressure, any said refrigerated coils in each said zone, has different temperature, the temperature of each said coils excepted the last coldest one in each said zone is regulated by a pressure regulating valve, said last coil in each zone is connected the compressor through a cheek valve 3. The invention of claim 2 including a vacuum chamber wherein said groups of refrigerated coils are placed to maintain the appropriate and desired high, low and very low dew points, used for removal of maximum D20 vapor (over 96% of absolute vapor) content of the air enters the said vacuum chamber.

4. The invention of claim 3 wherein the said vapor D20 content of said air being processed, enters the said vacuum chamber through an inlet, this inlet is connected to said distillation plant, the incoming said air from distillation plant passes in sequence over the said three groups zones of refrigerated coils, finally said air with extremely negligible low vapor and low temperature leaves through the outlet of said vacuum chamber.

5. The invention of claim 4 wherein the vapor D20 content of the air being processed enters the said vacuum chamber, and passes through the entire length of said vacuum chamber over the said refrigerated coils under nearly constant vacuum pressure above triple point pressure, Pir 661 pa, along with a gradual temperature gradient of the said air temperature from above freezing point to well below the triple point temperature, TIr 3.82 C, and finally expels from the outlet of said vacuum chamber. This outlet is connected to a high vacuum operable steam ejector.

6. The invention of claim 5 wherein said operable steam ejector to produce both, a condition of vacuum in said vacuum chamber and predetermined conditions of vacuum at a number of location in said distillation plant.

7. The invention of claim I wherein a "static" defrost system for removal of accumulated ice on said refrigerated coils (zones 2&3) placed in said vacuum chamber comprising the steps of: providing a warm brine circulating tank, said circulating tank connected to atmosphere to open air the inlet and outlet ports of the said vacuum chamber are completely closed, the three refrigeration cycles of the said unit stopped, the jacket brine mounted on the bottom of said vacuum chamber instantly filled up with said warm brine by gravity from said circulating tank, in this case the air inside the said jacket brine is purged into atmosphere through the auxiliary air vent, continuously recirculation warm brine liquid from said circulating tank along a closed flow path containing said jacket brine back to said circulating tank to energize the air layer adjacent to the interior surface of said vacuum chamber by conduction, the said energy carried away from the surface to the accumulated ice surfaces on said freeEing and deep freezing coils by free convection due to the buoyancy forces, said free convection due to the said buoyancy forces will increase the amount of heat available to remove the accumulated ice (dc-icing) from said coils in from of condensate drips fall in the drip pans where gravity pulls the condensate through the check valves in to the said daily condensate receiver, said condensate receiver further including a condensate exit means.

8. The invention of claim 7 wherein said condensate receiver includes an exit condensate means, said exit condensate means including a hole on top and a hole on the bottom of said condensate receiver, said hole on the top is connected to pressure equalizer line which is located between said condensate receiver and predetermined location on said distillation plant where the said hole on bottom is connected to flow and return back the condensate to main process line of said distillation plant easily, due to the gravity at vacuum condition.