Title of Invention

ABSORPTION REFRIGERATING PROCESS FOR TEMPERATURES BELOW 0C WITHOUT PRESSURE-BALANCING GAS

Abstract

Method for the cold production using a pair of working materials the components of which, in their pure state, are liquids with different boiling points used in both the high-pressure and the low-pressure section without any pressure-compensating gas present characterized in that the cold overrich solution (16) entering the high-pressure section is employed in a complete and uncontrolled manner as cooling agent that js preheated inside a non-adiabatic rectifier arranged in horizontal position (18), then further takes up heat from the weak solution inside the heat exchanger (19), desorbed inside the desorber (21) first in a regenerative way by the solution reflux (22) and finally on the concentration of the weak solution (20) inside the external-fired part of the flooded desorber (21), after which it transfers heat first in the solution reflux (22) and finally in the heat exchanger (19),and that the liquefied refrigerant (1) entering the low-pressure section is supercooled first inside the aftercooler (2) by cold vapors (3) coming from the flooded evaporator (4) and after this by branched-off refrigerant (6) inside the degasser (5), with the temperature of the supercooled refrigerant downstream of the degasser (5) being used as command variable for the automatic refrigerant feeding into the evaporator (4) through an as such commonly known thermostatic expansion valve (7).

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See Section 10, rule 13) ABSORPTION REFRIGERATING PROCESS FOR TEMPERATURES BELOW 0°C WITHOUT PRESSURE-BALANCING GAS DR.-ING. HANS FORSTER of BEIMSSTRASSE 59, D-39110 MAGDEBURG, GERMANY , GERMAN national The following specification particularly describes the nature of the invention and the manner in' which it is to be performed : - ORIGINAL 419/MUMNP/2003 28/4/2003 GRANTED 9/7/2004 Absorption-type refrigerating method for temperatures below 0°C without pressure-compensating gas The invention relates to a method and device for the cold production after the sorption principle at temperatures below 0°C, with a circulating solution made up of two liquids perfectly soluble in each other without any pressure-compensating gas present. Absorption-type refrigerating machines according to the invention are preferably applicable for units having an output of some kilowatts, or even some megawatts at special configuration, with the heating.parameters necessarily being in a range above 100°C. Absorption-type refrigerating units without pressure-compensating gas have a distinctly high pressure level in their hot section determined by the condensation of the refrigerant, whereat in the cold section a low pressure level is built up depending on the evaporation temperature of the pure refrigerating agent. The suggested improvements, therefore, relate both to the high-pressure and the low-pressure part of the method and to the equipment in connection therewith. Regarding the low-pressure section, the prior art is described taking DE - 19921469 A1 as a basis. According to this, there is a method known in which both condenser and evaporator are designed as a plate heat exchanger where the evaporator is fed with refrigerant from above and the refrigerant vapors, together with the non-evaporated part of the refrigerant and the residual aqueous degassing liquid, are drawn off at its bottom end. The two-phase mixture made up of refrigerant vapor and liquid refrigerant plus water is conveyed into the aftercooler. To allow for this, evaporator, aftercooler and absorber are to be arranged - in the said sequence - with a natural gradient. There is not just vapor superheated inside the aftercooler but also refrigerant evaporated after being branched-off. Hence, the cold vapor's refrigerating capacity is not sufficiently used, in particular since the quantity of refrigerant to be branched-off at different output levels is containing excessive amounts of refrigerant, i.e. refrigerant that ought to deliver refrigerating performance inside the evaporator. The need to have evaporator, aftercooler and absorber arranged with a natural gradient makes it difficult to construct the unit in a package type design. A two-phase flow, carrying the risk of erosion, already occurs inside the aftercooler. As this two-phase mixture is added to the weak solution upstream outside the absorber, there is no practicable option to have that weak solution finely divided inside the absorber. The unit's output regulation, as described in DE 19921469A1 done using the temperature difference as it exists when superheating the refrigerant vapors inside the evaporator, with intervention being made via the solution circulation. Such kind of regulation does not allow the evaporator to exercise its natural control via the expansion valve, and it makes regulation more expensive. Thermodynamic aspects, lack of package type design, cost issues, an expensive regulation principle as well as potential failures due to erosion processes and limitations as to the fine division of weak solution lead to the conclusion that the described method, even with a degasser left out, is not suited for the construction of package-type small-size units. From EP 0232746 A2, there is further known a method and device for the design of the low-pressure section by which the refrigerant is branched-off through a regulator-controlled appliance, powered from an outside source, with the minimum temperature difference between the supercooled refrigerant before its relaxation into the evaporator and the its vapor temperature being used as command variable. This is considered an energy-efficient way to automatically keep the concentration of the evaporating refrigerant at the desired level. The disadvantage in this method is the need for both the relaxation of refrigerant and its branched-off to use regulating devices that are interfering with each other and cause expenses and, in particular, because branching-off the refrigerant requires regulators powered from an outside source. Such approach to controlling the low-pressure section by using two variables is not suitable for low-output absorption-type refrigerating units because of the level of cost caused and the technical problems involved due to the mutual interference of the command variables. As far as the method's high-pressure section is concerned, the prior art can be described by making reference to standard works. The falling film technique was characteristic of the prior art for a long time. After the standard work by Niebergall, desorbers were designed as upright column-like appliances with standing stripping pipes inside which the overrich solution, in form of a film stream, is flowing from top to bottom. This type of design is still useful in high-output desorbers with heating steam at the shell if the adiabatic design of the rectifier with forced external reflux is to be kept up. The advantage in this approach is the reverse current principle after, which the degassing film and the upward moving vapors are guided, as well as the low ammonia quantity contained in the desorber. Said advantageous reverse current principle can also be implemented in hot water heated desorbers, as regards the solution to be degassed. This design type, however, does not perfectly allow the desirable use of a solution recirculation which would distinctively increase the effect as is caused by an improved energy transformation. Also, the vertical structure in the design of desorber and rectifier are considered a disadvantage because this brings about constraints on the unit's package type design, as well as increased costs. For that reason, horizontal vessels in which the heating fluid runs inside the piping have become the usual design for desorbers for some time. The are well suited for the construction of package type units where the equipment components can bear-ranged in no way other than horizontal. However, solution and heating fluid are not easily to be guided after the reverse current principle inside a flooded desorber ar-ranged in horizontal position. This, on the other hand, is an indispensable prerequi-site for utilizing waste heat with intensive refrigerating of waste heat transfer me-diums, since absorption-type refrigerating technology becomes more and more de-pendent on such condition. In most cases, liquid heat transfer mediums such as hot water or organic liquids serve as waste heat transfer fluids that are to deliver heat inside a flooded desorber working strictly after the reverse current principle. At the same time, a way must be found to economically and efficiently integrate the recirculation of the solution, which is necessary also owing to the fact that the cold overrich solution takes up heat inside the rectifier. It is the object of the invention to show ways in which it becomes possible to con-struct absorption-type refrigerating units without pressure-compensating gas for temperatures below 0°C after a package type design and at a low-cost basis, that can be used also as small-size units with outputs of some kilowatts. According to the invention, the problem is solved for both the low-pressure and the high-pressure section as follows: In the low-pressure section, the liquefied refrigerant (1) is supercooled first inside the aftercooler (2) by cold vapors (3) coming from the flooded evaporator (4) and subsequently inside the degasser (5) by refrigerant (6) that is branched-off, and the supercooling temperature reached downstream of the degasser (5) is used as the command variable for a thermostatic expansion valve (7) through which refrigerant is fed into the evaporator (4), with the said four process units - aftercooler (2), flooded evaporator (4), degasser (5), and absorber (9) - being integrated as horizon-tal pipe bundle apparatuses within one common pressure jacket (8) and connected wit each other through weirs and/or windows so as to allow branched-off refriger-ant to flow from evaporator (4) over weirs into the degasser (5), and degassing re-siduals (15) to the solution collector (14) where the remaining solution submerged in the same, whereat refrigerant vapor formed inside the evaporator (4) and the de-gasser (5) enters the absorber (9), preferably from below, after being superheated inside the aftercooler (2). In the high-pressure section, the cold overrich solution (16), after passing the solution pump (17), is fed for regenerative cooling into the non-adiabatic rectifier (18), then sent to the heat exchanger (19) for exchange of heat with the weak solution (20), and further conveyed to the desorber (21) in which the said solution is degassing first inside the solution reflux (22) and then in the external-fired part, and after this - now being a regenerative heating fluid - sent back to the solution reflux (22) where it undergoes a pre-cooling before it, inside the heat exchanger (19), is supercooled down the absorption temperature level. The desorber (21), as a horizontally arranged flooded apparatus, is equipped with lengthwise guiding plates (23) to produce a reverse current between heat transfer medium (24) and degassing solution, with the solution reflux (22) being arranged within a separate tray (25) above the external-fired part onto the lengthwise guiding plates (23). Schematic drawings are used to explain the invention in more detail. Figure 1 shows the low-pressure section of the method according to the invention. Figure 2 shows a section through the low-pressure unit, incl. evaporator, aftercooler, degasser and absorber as integrated process stages. Figure 3 is a schematic depiction of the process flow in the high-pressure section, involving desorber, rectifier, heat exchanger and solution pump. Figure 4 shows sections through the horizontally arranged flooded desorber. From figure 1 it can be seen that branching-off the refrigerant, by overflowing from the flooded evaporator (4), is effected by controlling the refrigerant supply through the thermodynamic expansion valve (7). A pre¬condition for the employment of a thermodynamic expansion valve, which as such is ought to be used only in "dry" evaporators with vnpoi superheating, the refrigerant must be extremely supercooled in two steps, where - in a first step - supercooling is by using the cold vapors inside the aftercooler (2), whereat the second aftercooling is by degassing the refrigerant. In this way, the refrigerant gets extremely supercooled so as to have a temperature of only 5K to 12K above its evaporating temperature, which is the superheating temperature range in case of dry evaporation, and hence enables employment of commonly used thermostatic expansion valves. At the same time, level control inside the flooded evaporator (4) and the degasser (5) can be dropped as it is replaced by overflow weirs. Use of overflow weirs for branching off the refrigerant (6) and taking up the degassing residuals (15) suggests a package-type design in form of horizontal structures, where the required compactness may be further improved if - in case of low-output units - the flooded evaporator (4), the degasser (5), the aftercooler (2) and the absorber (9) are housed inside one common pressure jacket (8) - see figure 2 - so that overflowing can be effected without external piping, with the center part being formed by the degasser (5) and - as the case may be - the aftercooler (2) so as to minimize cold bridges between evaporator (4) and absorber (9) by "suspending" the degasser (5) between evaporator and absorber. The described principle of controlling as well as the use of weirs and vapor transfer windows can be applied even to high-performance units in which, however, housing in a common pressure jacket is not necessarily required. As regards the high-pressure section, the method according to the invention as depicted in figure 3 is based on a two-step pre-heating of the overrich solution (16) by the non-adiabatic rectifier (18) and the heat exchanger (19). Analogously, the weak solution (20) undergoes a two-step cooling, where - at the hot end - heat is transferred to the solution reflux (22) and then to the overrich solution inside the heat exchanger (19). The reflux (26) from the non-adiabatic rectifier (18) is sent back to the desorber (21), and submerged. The desorber's (21) structural design, as depicted in figure 4, is characterized by lengthwise guiding plates (23) which create the reverse current between degassing solution and heat transfer medium (24), and at the same time support the tray (25) for the solution reflux (22). List of terms used 1 liquefied refrigerant 2 aftercooler 3 cold vapors 4 flooded evaporator 5 degasser 6 branched-off refrigerant 7 thermostatic expansion valve 8 pressure jacket 9 absorber 10 transient zone 11 weir 12 window 13 window 14 solution collector 15 degassing residuals 16 cold overrich solution 17 solution pump 18 cooled rectifier (non-adiabatic rectifier) 19 heat exchanger 20 weak solution 21 desorber 22 solution reflux 23 lengthwise guiding plates 24 heat transfer medium 25 tray 26 reflux 27,28 antechambers 29 vertical chamber bridges I CLAIM : Method for the cold production using a pair of working materials the components of which, in their pure state, are liquids with different boiling points used in both the high-pressure and the low-pressure section without any pressure-compensating gas present characterized in that the cold overrich solution (16) entering the high-pressure section is employed in a complete and uncontrolled manner as cooling agent that js preheated inside a non-adiabatic rectifier arranged in horizontal position (18), then further takes up heat from the weak solution inside the heat exchanger (19), desorbed inside the desorber (21) first in a regenerative way by the solution reflux (22) and finally on the concentration of the weak solution (20) inside the external-fired part of the flooded desorber (21), after which it transfers heat first in the solution reflux (22) and finally in the heat exchanger (19),and that the liquefied refrigerant (1) entering the low-pressure section is supercooled first inside the aftercooler (2) by cold vapors (3) coming from the flooded evaporator (4) and after this by branched-off refrigerant (6) inside the degasser (5), with the temperature of the supercooled refrigerant downstream of the degasser (5) being used as command variable for the automatic refrigerant feeding into the evaporator (4) through an as such commonly known thermostatic expansion valve (7). Device for the implementation of the method For the coold as calimed 1 characterized in that the as such commonly known desorber (21) arranged in horizontal position and operating in flooded mode is subdivided by lengthwise guiding plates (23) supporting the tray (25) of the solution reflux (22), with the antechambers Device for the implementation of the method according to claim 1 characterized in that the evaporator (4), absorber (9), aftercooler (2) and degasser (5) are housed inside a horizontally arranged common pressure jacket (8) in which the coldest zone (evaporator 4) and the hottest zone (absorber 9) are separated from each other by a transient zone (10) arranged in between the same and made up by the degasser (5) and - as the case may be - the aftercooler (2), with the evaporator (4) being connected through a weir (11) with the degasser (5) and through a window (12) with the aftercooler (2), whereat the aftercooler (2), in turn, is connected through a window (13) - via another appropriate connection with the solution collector (14) - to the absorber (9). Dated this 23rd day of April, 2003. Hiral Chandrakant Joshi AGENT FOR DR.-ING. HANS FORSTER

Documents:

419-mum-2003 cancelled pages (9-7-2004).pdf

419-mum-2003 correspondence (13-1-2005).pdf

419-mum-2003 correspondence (ipo)(14-6-2007).pdf

419-mum-2003 drawing(9-7-2004).pdf

419-mum-2003 form 1 (9-7-2004).pdf

419-mum-2003 form 19(3-10-2003).pdf

419-mum-2003 form 2 (granted) (9-7-2004).pdf

419-mum-2003 form 3 (9-7-2004).pdf

419-mum-2003 form 5 (9-7-2004).pdf

419-mum-2003 power of attorney (14-7-2003).pdf

419-mum-2003- claim(garnted)- (9-7-2004).pdf

419-mum-2003-claims(garnted)-(9-7-2004).doc

419-mum-2003-form 2(garnted)- (9-7-2004).doc

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