IL248315A - Absorption refrigerating machine with a working solution of lithium bromide/methanol - Google Patents

Description

248315/2 Absorption refrigeration machine with a working solution of the lithium bromide/methanol Authors: Mirmov Naum, Shpatz Zvi Background Absorption refrigeration machine, where the salt in alcohol solution is used as the working solution, has the several distinguishing features. A working solution based on lithium bromide + methyl alcohol (LiBr + CH3OH) is used in refrigeration machine. Such solution allows to obtaining boiling points of refrigerant (methanol) in the evaporator of about minus (-15°...-12°C). At said boiling points the specific volume of vapors is 28-40 m3 / kg. Decreasing of boiling point from 0°C to -15°C leads to increasing in specific volume of vapors by 6-10% as temperature decreases for every 1°C. Large specific volume of vapors requires significant increasing of the flow area of the vapor connecting pipelines between the generator and the condenser, especially between the evaporator and the absorber. Increasing of the flow areas of the vapor pipelines leads to reducing of the vapor flow velocity from the generator into the condenser as well as from the evaporator into the absorber. Furthermore, in the evaporator with negative temperatures boiling vapor pressure is several times lower than in the absorber. Therefore, refrigerant vapor (methanol) flows slowly from the evaporator in the absorber, despite the considerable difference in concentration. To provide a given negative boiling temperature in the evaporator and to maintain the normal operation of refrigerating machine in both the evaporator outlet branch pipe and inlet branch pipe of the absorber a mechanical booster is installed. This booster is designed as a centrifugal wheel or axial impeller. The rotation of the impeller in the mechanical booster is carried out by hydraulic, pneumatic or electric drives. Mechanical booster of the evaporator increases the speed of the methanol vapor from the evaporator to the absorber and overcoming possible pressure difference in the absorber and the evaporator. Mechanical booster of the absorber creates steam velocity in the inlet section of the absorber in the range of 14-15 m / sec, which increases the efficiency of absorption of methanol vapor working solution.

To reduce overall size of refrigeration machine and its weight, machine is composed of the two assembly units: block (A) and block (B). An assembly unit consists of separate apparatuses. Branch pipes of the evaporator and the absorber and of the generator and the condenser are connected by means of bend that has minimum aerodynamic resistance. Self actuated check valve is installed between branch pipe and connecting bend.

Viscosity of solution methanol- lithium bromide is significantly higher than the pure solvent. Since the refrigeration machine is running at subzero temperatures, gear type pump of low-speed or vortex pump are used instead centrifugal pump for properly circulation of the solution in such a machine.

LiBr + CH3OH solution has a tendency to crystallization when it is subcooled in the absorber and pipelines of solution circulation. Crystallization takes place at technological and other types of stops or by insufficient working solution in the machine. To eliminate possible crystallization 248315/2 of the solution when it is subcooled, there are devices in the absorber sump for installing heating elements, for example electric heating elements.

For methanol drainage from the evaporator during technological or other stop of the refrigeration machine, evaporator and absorber are connected to the sprinkling tray, in which the automatic solenoid valve and the pump are installed. The pump is turned on when the refrigerating machine is stopped. Drainage of the liquid methanol from the evaporator into the absorber in turn prevents crystallization of the solution.

The weak solution feeding onto generator of the heat exchange tubes is carried out by circulation pump through a distribution device which is designed as a fan-like type distributor with mesh sprinklers. The distribution device of the absorber is also designed as a fan-like distributor with drain holes of varying diameter. For uniform distribution of the solution flow onto the heat exchange tubes of the absorber under the spray device over the pipes a wire-mesh plate is installed.

In the outlet branch pipes of the generator the drop catcher are installed, which prevent the drop entrainment of the liquid solution during desorption process. 2. Application fields The invention relates to refrigerating engineering for technological cold in manufacturing process for cold store warehouse, meat and dairy industries, in the food industry, petrochemical and gas industry as well as for air conditioning systems in industry and households. 3. Existing analogues Designs of absorption refrigeration machines have certain distinctions depending on the applied working solution. Most widely widespread are absorption refrigeration machines that work with working solutions N¾ / H20 or H20 / LiBr. The absorption refrigeration machines that work on N¾ / H20 solution allow obtaining boiling temperatures in the evaporator up to -30°...-35°C.

Absorption refrigeration machines, which use salt solutions in water, are most widely known and widespread (lithium bromide refrigeration machines). For such machines the most common working solution is LiBr + H20. Refrigeration machines with such a solution are manufactured by many companies, for example, "Carrier" and its branches in South Korea, China and Russia. A distinguishing feature of refrigeration machines operating on water solutions of salts is that the arrangement of all heat exchangers of the machine is carried out in one or two housings. This simplifies construction of the machine but increases its overall dimensions and weight. The lithium bromide refrigeration machines operate on heat sources at 110°...120°C. The lithium bromide refrigeration machines are used for air conditioning systems and for cold water making at 10°...15°C for process cooling needs.

Absorption refrigeration machines that work on a solution of water - salt, have a number of disadvantages: - such refrigerating machines can operate only in the temperature range of air conditioning; 248315/2 - operation of the refrigeration machine is under a high vacuum, which places high demands on sealing of the machine, increases weight of the apparatuses; - when the temperature of cooling water or heating source are changed at technological and other type of stops, the crystallization of the solution is occurred, that makes operation condition of the machine impossible; To avoid crystallization of the solution various, heat exchangers or other devices are added to the machine, or chemical additives are injected into salt solution. By adding chemical additives the temperature range of crystallization is expanded or this process is completely neutralized. In some constructions of refrigerating machines installation of special equipment (heat exchangers, pumps), control devices and controlling of concentration of the solution is provided.

Patents US 6,122,930 B1 and US 6,247,331 B1 [Nishiguchi, et al. Sep. 26, 2000; Jun. 19, 2001] are known. In these patents are proposed the lithium bromide refrigeration machine that produces cooled water of temperature about 1.0°...1.5°C. Refrigerant in such machines is an aqueous solution of lithium bromide of concentration not lower than 15%. Design feature of these absorption refrigerating machines is that it has two absorber, two evaporators and two generators. The absorber and the evaporator are located in the same housing while the evaporator of "open" type is used. Accordingly, the refrigerating machine comprises two pumps for refrigerant circulation, and two pumps for solution circulation. One of the pumps is intended for circulating the high pressure solution because the solution feed into the absorber is carried out through the ejector. The two-stage regeneration of solution is considerable complicates the design of the refrigerating machine. Control of mode operation is complicated and requires special control and adjustment instruments. The system of solution spraying and feeding onto the heat transfer elements of the absorbers and evaporators has a complicated design. It is possible the formation of ice blockage in the low temperature part of the machine, which leads to stop the refrigeration machine.

Similar design of absorption refrigeration machine is given in the article [Gorshkov V. G., et al. Herald of the MAR, N° 4, 2013, pp. 51-53]. The refrigeration machine with single-stage solution regeneration and steam heating of generator is tested. The main distinction of the refrigeration machines with “the open evaporator” from the existing absorption refrigeration machines is absence of the tube bundle of the evaporator. The refrigerant in such machine is used as cold medium which is circulated between user of refrigeration and evaporator space. The given data of the test results shows difficulty to obtain low boiling point in the evaporator. Stable operation is only possible while maintaining a strictly defined temperature of the heating source and the condensation temperature.

For subzero temperatures of cooling agents are proposed hybrid refrigerating machines. Hybrid refrigeration machines combine absorption and vapor compression cycles. The suction side of the compressor is connected either directly to the evaporator or to vapor pipeline between the evaporator and the absorber. The discharge side of the compressor is connected either directly to the condenser of the refrigeration machine or to vapor pipeline between the generator and the condenser. Hybrid refrigeration machines can operate only if the absorption machine works on solution NH3 / H20 or on one of HFC / organic absorbent solutions. In Patent US 4,428,854 [Enjo, et al. Jan. 31, 1984] is proposed working solution R134A with organic solvent (of tetraethylene glycol dimethyl ether, di ethylfonnamide, methyl ethyl 248315/2 ketone, methyl tetrahydrofurfuryl ether, ethyl tetrahydrofurfuryl ether and butyl tetrahydrofurfuryl ether, said 1,1,1,2-tetrafluoroethane being present in an amount of at least 40% wt. based on the weight of the composition).

Based on the similar working solutions in Patents US 7,765,823 B2 [Shiflett et al. Aug.3, 2010], 8,800,318 B2, [Erickson, Aug.12, 2014], 8,707,720 B2 [Shiflett et al. Apr. 29, 2014] hybrid refrigerating machines are proposed. Compressor in the hybrid refrigeration machine is used when electrical demand is dropped. At this time electricity rate is lower which leads to reducing operating costs. At the peak electrical load is mainly used absorption machine. The compressor is turned on by necessity covering only the part of load on refrigeration supply system.

Hybrid refrigeration machines are not find wide practical application since they demand highly qualified maintenance, are manufacturing costly, do not give economic efficiency which there is in design calculation.

Absorption refrigerating machines, in which alcohols: methyl CH3OH and ethyl C2H3OH are used as volatile components (refrigerant), are known. Preference is given to methanol and systems based on it, because of its thermo-physical properties. Pilot refrigeration machine using LiBr + CH3OH solution is proposed [see “Kholodilnaya Technika”, 1968, Ns 1, page 4-6]. Refrigeration machine was assembled from individual of the shell-and-tube apparatuses^ The heat exchanger of the solution is tube-in-tube type. The experimental data shows the possibility of obtaining sufficiently low boiling points at a temperature in the absorber of 20°C to 35°C. Concentration of the solution in the absorber was 47-53% while in the generator is 53-47%. By different operating conditions were obtained subzero boiling temperatures of the refrigerant (methanol) in the evaporator: -5.5°C; -11.2°C; -18.6°C respectively. As indicated in the article, design thermal coefficient is of 0.62-0.65. For low temperature absorption refrigeration machines, especially those working on the solutions of alcohols and salts, it is quite good indicator. The disadvantages of such refrigeration machines as follows: - presented refrigeration machine made in laboratory version without corresponding design study of industrial model; - each heat exchanger of the machine is provided with a vacuum pump to maintain a constant vacuum in the apparatuses of the machine that is absolutely not suitable for industrial machine; - presented technological scheme of the refrigeration machine shows only qualitative ability to create absorption refrigeration machines operating on salt solutions of lithium bromide with methanol.

The closest technical solution is the Russian Patent Application registration N° 2013102320 (registration date 17.01.2013), Int. Cl. F25B 15/00, F25B 15/06. In said application an absorption refrigeration machine is proposed that runs on lithium bromide solution with methanol. The machine underwent a pilot test at solution concentration of 50-50%. At the boiling point of the refrigerant in the evaporator minus -12°C, the performance of the machine was about 8.0-8.3 kW.

The temperature of the cooled coolant (water solution of ethylene glycol) was obtained minus -8.0°C. Throttling device of the Venturi-type multi-pass nozzle is used in the in refrigeration machine. Buffer tanks for methanol, which are connected to spray of the solution in the absorber, are installed in the machine for preventing possible crystallization of the solution during technological or other type of stops. 248315/2 The disadvantages of said refrigeration machine are: - with installed throttle device there is no possibility of smooth regulation of refrigerant feeding into the evaporator; - construction of the machine is suitable for obtaining low cooling capacities, no more than 15 kW; - feeding and distribution of liquid in the evaporator have low eficiency because liquid does not uniformly coats surface of heat exchange tubes.

There are other patents which consider construction and schemes of absorption refrigeration machines with saline solutions: Patent US 3,626,711; 12/1971 Porter, et al. U.S. Cl.62/141; Patent US 3,848,430; 11/1974 Porter, et al. U.S. Cl.62/476, 497; 165/82, 162; Patent US 4,428,854; 1/1984, Enjo, et al. U.S. Cl.259/69, 67, 364; 62/112; 570/134, 175; Patent US 4,458,499; 7/1984 Grossman, et al. U.S. Cl.62/148, 476; Patent US 4,672,821; 6/1987 Furutera, et al. U.S. Cl.62/324.2; 62/238.3; 62/476; Patent US 4,732,008; 3/1988 DeVault, et al. U.S. Cl.62/79, 332, 335, 476; 62/238.3; Patent US 5,044,174; 9/1991 Nagao, et al. U.S. Cl.62/476, 113; 62/238.3; Patent US 5,367,884; 11/1994 Phillips, et al. U.S. Cl.62/101, 476, 497, 485; 62/238.3; Patent US 5,592,825; 1/1997 Inoue; U.S Cl.62/141, 105, 476, 483; Patent US 6,122,930; 9/2000 Nishiguchi, et al. U.S. Cl.62/476, 483, 485; 62/141, 335; Patent US 6,141,987; 11/2000 Huor, et al. U.S. Cl.62/476, 483; 62/141; Patent US 6,247,331 Bl; 6/2001 Nishiguchi, et al. U.S. Cl.62/476, 483, 485; 62/141, 335; Patent US 6,536,229 Bl; 3/2003 Takabataka, et al. U.S. Cl.62/476, 487, 489; 62/85, 238, 475; Patent US 6, 993,933 B2; 2/2006 Nishimoto, et al. U.S. Cl.62/489, 494, 497; 62/476, 485; Patent US 7,316,126 B2; 1/2008 Aoyama, et al. U.S. Cl.62/476, 484, 489; Patent US 7,765,823 B2; 8/2010 Shiflett, et al. U.S. Cl.62/196.1, 238.6, 197, 252/67; Patent US 8,353,170 B2; 1/2013 Su, et al. U.S. Cl.62/119, 476, 481; 62/324.1, 483, 513; Patent US 8,707,720 B2; 4/2014 Shiflett, et al. U.S. Cl.62/196.1, 238.6, 197, 252/67; Patent CN101603744; 12/2006 Takemura, et al. Int. C1.F25B15/00; F25B49/04; Patent RU 2029202 Cl; 2/1995 Latyshev V., Int. C1.F25B 15/00; Patent RU 2101625 C2; 1/1998 Gadelshin M., Int. C1.F25B15/16; Patent RU 2164325 C2; 3/2001 Winnington, et al. Int. C1.F25B 15/06; F25B49/04; Patent RU 2443948 C2; 2/12012 Leontiev, et al. Int. C1.F25B15/00; F25B29/00; Russian Patent Application 2013102320, on 17.01.2013 Mirmov, et al. Int. C1.F25B15/00; F25B 15/06; US Patent Application 2013/0269373, Oct.17, 2013 Radhakrishnan, et al., U.S. Cl.62/79, 333.

Other Publications Grosman E. R., et al. Study absorption refrigeration machine using a methanol solution of lithium bromide. Kholodilnaya Tekhnika, 1968, 7, pp. 4-6.

Sakiymota A., Nishiguchi A. Development of an absorption refrigeration machines, operating at heat and cooling temperatures up to below 0°C. Proceedings of the International Conference on sorption heat pumps, 1999, Munich. Germany. 248315/2 Gorshkov V. G., et al. Generating low boiling temperatures of a refrigerant in a lithium bromide absorption refrigerating system. Kholod: Technique and Technologies, Herald of the MAR, Ns 4, 2013, pp. 51-53.

Figure captions: Fig.l. Schematic diagram of an absorption refrigeration machine; Fig.2. Connection block of the generator and condenser; Fig.2a. Connection unit of the generator and condenser (Section A- A); Fig.3. Connection unit of the absorber and evaporator; Fig.3a. Connection unit of the absorber and evaporator (Section B-B); Fig.4. Construction of the evaporator with the centrifugal booster; Fig.5. Mounting design of the centrifugal booster in the branch pipe of the evaporator; Fig.5a. Design of booster’s drive from the hydraulic turbine; Fig.6. General views of the arrangement the axial booster in the absorber (Section C-C); Fig.6a. Construction of the absorber (view from side of the removable cover); Fig.7. Mounting design of the booster with axial impeller to the bend of the absorber; Fig.8. Construction of the generator (section D-D); Fig.8a. Construction of the generator (view from side of the removable cover); Fig.9. Construction of the condenser (section E-E); Fig.9a. Construction of the condenser (view from side of the removable cover); Fig.10. Construction of the distribution device of the generator; Fig.10a. Construction of the distribution device of the generator (top view); Fig.10b. Construction of the distribution device of the generator (section F-F); Fig.10c. The distribution device of the absorber; Fig.lOd. The arrangement of the sprinkling trays.

This technical proposal provides properly and effective operation of the absorption refrigeration machine on LiBr / CH3OH working solution at subzero operating temperatures, increasing reliability and working capacity, preventing crystallization of the solution. Solution of the goal is achieved by that the machine comprises two assembly units, where in block (A) generator with condenser are connected while in block (B) absorber with evaporator are connected.

For this purpose in both the evaporator outlet branch pipe and the absorber inlet branch pipe a mechanical booster is installed. This booster is designed as a centrifugal wheel or axial impeller. The rotation in the mechanical booster is carried out by hydraulic, pneumatic or electric drives. The mechanical booster of the evaporator increases the speed at movement of the methanol vapor from the evaporator to the absorber. The mechanical booster installed in the inlet pipe absorber provides, at the inlet of the absorber methanol vapor velocity about 14-15 m / sec, which increases the efficiency of methanol vapor absorption of the working solution.

Feeding of the weak solution onto generator heat exchange tubes is carried out by circulation pump through a distribution device which is designed as a fan-like type distributor with mesh sprinklers. The distribution device of the absorber is also designed as a fan-like distributor with drain holes of varying diameter. For uniform distribution of the solution flow onto the heat 248315/2 operating condition of the refrigerating machine.

In a branch pipe (24) of the evaporator (7) is installed the booster (25), rotation of which is carried out by drive (26). The booster (25) discharges vapor of the refrigerant from the evaporator (7) into the absorber (9). In the bend (8) before an inlet branch pipe (27) of the absorber (9) is installed the booster (28), for example of axial type with drive (29).

Cooling agent, for example 35% solution of ethylene glycol is fed into the tubes (30) of the evaporator (7) by the pipeline (Ci2) and withdrawn to the cooling system by the pipeline (C13).

Hot water is fed into tubes (31) of the generator (1) by the pipeline (C14) through the 3 -way valve (32) while is withdrawn through the pipeline (C15).

Cold water is fed into tubes (33) of the condenser (3) by the pipeline (C 6) while is withdrawn into the cooling tower (is not shown in the scheme) by the pipeline (C 7).

All apparatuses of the refrigerating machine are equipped with 3-way valves (34), by which the vacuum pumping of the apparatuses and filling them by working solution are carried out. In the receiver (5) is installed a coil (35) that provide subcooling of liquid methanol before expansion valve (EV-1). All apparatuses and piping of the refrigeration machine are provided with thermal insulation (36).

The proposed absorption refrigeration machine is designed, for example, with horizontal arrangement of all its apparatuses. Main apparatuses of the machine (absorber, generator, evaporator and condenser) are shell and tube type with U-type of the heat exchange tubes. The regenerative heat exchanger (6) and the subcooler (10) are also of the shell and tube type, but are of straight-tube in the heat exchangers.

Fig. 4 shows design of the evaporator. The evaporator (7) is a shell and tube heat exchanger. The evaporator (7) consists of a casing (41) with the flange (42) and the blind cover (43). Inside the casing (41) are placed the U-type heat exchange tubes (30) and fixed to the tube sheet (44). The heat exchange tubes (30) and the tube sheet (44) form a tube bundle (45). To prevent deflection of the tubes (30) an intermediate segmental baffle (46) is mounted in the housing (41). The evaporator (7) is provided at least with two branch pipes (24) for vapor withdrawing into the absorber (9). Quantity of the vapor branch pipes (24) and their nominal diameter are selected depending on the cooling capacity, boiling point of the refrigerant and its thermo physical properties (mainly in the specific volume of vapors). For the better refrigerant vapor withdrawing from the evaporator into the absorber, the evaporator provided with the booster (25). The booster (25) can be axial or centrifugal type of wheel. Its drive can be as hydraulic, pneumatic or electric motors. For the evaporator is most advisable to use hydraulic drive because inside of it for the booster rotation is potential energy of the flow of liquid refrigerant is used. Liquid refrigerant by the pressure of condensation is fed through the pipeline (C3) to the expansion valve (EV-1), and then is fed to the drive wheel and to the tube space of the evaporator (see Fig. IT The hydraulic drive (26) of the booster (25) is, for example, a hydraulic turbine which can be installed directly in the casing of the evaporator (7) or on the outside of the apparatus. One of the embodiments of a hydraulic drive of centrifugal type is shown in Fig.5 and Fig.5a. In this case the booster (25) is installed in each vapor branch pipe (24).

The apparatus closed by cover (47) with a flange (48). In the cover (47) made a partition (49) that provide double passageways of refrigerant in the pipes (30) of the evaporator (7). In the cover (47) are installed the connecting branch (400) and (401) for inlet and outlet of refrigerant. 248315/2 The evaporator (7) is provided with a connecting branch (402) for liquid refrigerant and with the connecting branches (403), (404) and (405) for installing 3 -way valves, gages and control instruments, respectively. A connecting branch (406) is intended for the refrigerant drainage from the evaporator at technological stops of the machine. To the connecting branch (406) is installed the pipeline (C2). The connecting branch (407) is intended for mounting of a refrigerant level gage in the evaporator. The apparatus is equipped with standard supports (408) and thermal insulation (36).

In the Fig.5 and Fig.5a is shown one of the elements of the constructive placement of the booster (25) in the branch pipe (24) of the evaporator as well as the drive, for example hydraulic turbine, connection. The booster (25) consists of the centrifugal wheel (51) which is fixed on the axle (52). The axle (52) is attached to the shaft (53) of the turbine (54) and supported by the two bearings (55) and (56). In the wall of the branch pipe (24) is performed the opening that is closed by the flange (58). In the flange (58) is mounted the seal housing (59) for installing the sealing bush (501) and the seal ring (502). The hydraulic turbine (54) comprises of the inlet connecting branch (503), the nozzle apparatus (504), the impeller (505), the sealing elements (506) and the bearings (56).

The nozzle apparatus (504) gives to fluid flow required direction for inlet into the impeller blades (505) and serves for transformation of potential energy of the liquid refrigerant flow, that comes from the receiver (5), into rotation motion of the turbine impeller (505) and thus into rotation of the impeller (51) of the booster (25). The turbine impeller (505) is mounted in the housing (507). The outlet branch pipe (508) of the turbine (54) is connected to the pipeline (509) through of which liquid refrigerant enter the tube space of the evaporator (7).

In the presence in the evaporator (7), for example, of the two vapor branch pipes (24) the pipeline (503) is connected to manifold (in the Fig.5a is not shown) that it connected to the expansion valve (EV-1).

Fig.6 and 6a shows construction diagram of the absorber (9) that is designed as a shell and tube heat exchanger with U-type of the heat exchange tubes. The absorber £9] consists of a casing (61) with flange (62) and blind cover (63). Heat exchange tubes (20) are placed G see Fig. 3] inside the casing (61), which are fixed in the tube sheet (64).The heat exchange tubes (18) with the tube sheet (64) form a tube bundle (65). Intermediate segmental baffle (66) is mounted in the casing (61) to prevent deflection of the tubes (20).

The apparatus is closed by the cover (67) with the flange (68). There is a partition (69) in the cover to provide two-pass flow of cooling water. Cold water is fed into heat exchange tubes (20) through a branch pipe (600) but is withdrawn through a branch pipe (601) into the pipeline (C10) and fed into heat exchange tubes (21) of the subcooler (10) l~see Fig. 11.

The absorber (9) is provided with branch pipes (27) for the refrigerant vapors feeding from the evaporator (7). The number of branch pipes (27) corresponds to the amount of vapor branch pipes of the evaporator (7). In the each branch pipe (27) is installed the supercharger (28), for example, of the axial type. The drive (29) of the booster (28) is mounted on the bend (8). In the branch pipes (27) can be installed the supercharger (28) of centrifugal type similar to the booster (25) Fsee Fig.4. and Fig51. 248315/2 The spraying mesh (61) is installed in the casing (61) above the tube bundle (65) while the distribution device (19), which is intended for uniform feed of working solution onto the heat exchange tubes (20) in the absorber (9), is installed above the spraying mesh (61). Design of the distribution device (19) is shown in Fig.10c. The distribution device (19) is connected to the branch pipe (603) that is provided with two flanges (604) and (605). The branch pipe (603) is connected to the flange (606) of the connecting branch (607) by the flange (604) and thus the distribution device (19) is fixed in the casing (61) of the absorber. The branch pipe (603) is connected by the flange (606) to the pipeline (Cg) of feeding working solution from the generator (1) into the absorber (9) [see Fig.11. In the bottom portion (22) of the absorber (9) the heating elements (23), for example an electric type are placed. Also in the bottom portion (22) there is a connecting branch (608) for connecting the pipelines (C2) in which are installed automatic valve (SCF), the pump (13) and the connecting branch (609) for the 3-way valve connecting (14) [see FigJJ. The connecting branch (610) and (611) are intended for installing gages and control instruments. The apparatus is equipped with the supports (612) and thermal insulation (36).

Drive of the booster (28) can be electrical, pneumatic or hydraulic. Depending on the type and the design of the selected drive (29) for the booster (28) its fixing will diferent. In the most general form, one of the proposed options of axial type of the booster (28) is shown in Fig.7.

The booster (28) consists of the impeller (71) fixed on the end of the shaft (72). The shaft (72) is installed in the guide bush (73) that is mounted in the seal housing (74) together with the seal rings (75). Sealing of the shaft is provided by the gland bush (76). The seal housing (74) is mounted in the locating flange (77) that is welded to the supporting sleeve (78). The said supporting sleeve (78) is mounted on the bend (8) of the absorber (9).

Fig.8 and 8a shows construction diagram of the generator (1) that is designed as a shell and tube heat exchanger with U-type of the heat exchange tubes. The generator (1) consists of a casing (81) with flange (82) and blind cover (83). The heat exchange tubes (31) are placed [see Fig. 21 inside the casing (81), which are fixed in the tube sheet (84). The heat exchange tubes (31) with the tube sheet (84) form a tube bundle (85). Intermediate segmental bafle (86) is mounted in the casing (81) to prevent deflection of the tubes (31). The apparatus is closed by the cover (87) with the flange (88). There is a partition (89) in the cover to provide two-pass flow of hot water. Heat-transfer agent (hot water) is fed through the connecting branch (800) but withdrawn from the apparatus through the connecting branch (801). The generator (1) is provided at least with the two branch pipes (802) for refrigerant vapor withdrawing into the condenser (3).

In flow area of the branch pipes (802) are mounted mesh drop catcher (803), which prevent entrainment of drops of the refrigerant into the condenser (3). In the casing (81) above the tube bundle (85) the distribution device (16) is installed, design of which is shown in Fig.10. 10a, 10b. The distributor device (16) attached to the connecting branch (804) which is provided with two flanges (805) and (806). The connecting branch (804) is attached by the flange (805) to the flange (807) of the connecting branch (808) and fixes position of the distributor device (16) in the generator casing. The connecting branch (804) is connected by the flange (807) to the pipeline (C6) for feeding the working solution from the absorber (9) into the generator (1) fsee. 248315/2 Fig.ll. The connecting branch (809) and (810) are intended to installing gages and control instruments .The connecting branch (811) is used for connection to the pipeline (C7) for discharging hot solution into the tube space (17) of the heat exchanger (6). The apparatus is provided with the standard supports (812) and thermal insulation (36).

Fig. 9. 9a shows construction diagram of the condenser (3) that is designed as a shell and tube heat exchanger with U-type of the heat exchange tubes. The condenser (3) consists of a casing (91) with flange (92) and blind cover (93). The heat exchange tubes (33) are placed inside the casing (91) fsee Fig. 21. which are fixed in the tube sheet (94). The heat exchange tubes (33) with the tube sheet (94) form a tube bundle (95). Intermediate segmental baffle (96) is mounted in the casing (91) to prevent deflection of the tubes (33). The apparatus is closed by the cover (97) with the flange (98). There is a partition (99) in the cover to provide two-pass flow of cooling water. Cold water is fed into the heat exchange tubes (33) through the connecting branch (900) but withdrawn to the cooling tower (is not shown in the figure) through the connecting branch (901).The condenser (3) is provided at least with the two branch pipes (902) for refrigerant vapor feed from the generator (1). The connecting branch (903) is used for connection to the pipeline ( ) that is intended for pressure balance in the condenser (3) and the receiver (5). The refrigerant condensate enters the receiver (5) through the connecting branch (904). The connecting branch (905) and (906) are intended for installing gages and control instruments. The apparatus is equipped with the standard supports (907).

The construction of the distribution device (16) of the generator (1) is shown in Fig.10. 10a, 10b. The distribution device (16) is intended for uniform feeding of the working solution in a fine state onto the heat exchange tubes (31) of the generator (1). The distribution device (16) contains a main distribution pipe (101) closed at the ends by the caps (102). In the middle part of the main distribution pipe (101) the coupling (103) is mounted, wherein the connecting branch (104) is installed. The sprinklers made as sprinkling trays (105) are installed along the main distribution pipe (101) on both sides, tangentially to the lower generatrix. The sprinkling trays (105) a placed at an angle of 1-4° to the longitudinal section plane of the main distribution pipe (101). The sprinkling tray (105) is made of a pipe with a cut-off segment (106), whose height is approximately 1/3 of the tube diameter. The length of the cut-off segment (106) depends on the size of the generator (1) and is at least 2/3 of the sprinkling tray (105) length. The several slits (107) are made along the length of the sprinkling tray (105). They are closed by meshes. The size of the mesh openings increases as the distance of the slit from the distribution pipe is grown to the end of the sprinkling tray. The sprinkling tray is provided with the partition (108).

The design of the distribution device (19) of the absorber (9) slightly differs from the design of the distribution device (16) of the generator (1). The difference is in the arrangement of the sprinkling trays (105) regarding to the main distribution tube (101) fsee Fig.10c and lOdl. The sprinkling tray (105) installed perpendicular to the vertical axis of the main distribution tube (101). At the bottom of the sprinkling tray (105) drain holes (109) are made, the diameter of which increases proportionally according to the flow rate ratio of the solution entering the absorber. 248315/2 Absorption refrigeration machine with the working solution LiBr/CH/jOH operates as follows: Inspection of all machine systems and external connections of heat-carrying agent circulation, cooling water and refrigerant are carried out before starting the refrigerating machine. The circulation pump (11) is started up and solution circulating factor between generator (1) and absorber (9) is set. Cold water is fed via pipeline (C16) into the tubes (33) of the condenser (3) while via pipeline (C9) into the tubes (20) of the absorber (9). From the tubes (20) via pipeline (C10) water enters the tubes (21) of the subcooler (10) and then via pipeline (Cn) is withdrawn into the cooling tower. The valve (32) is opened and hot heat-carrying agent, for example, hot water is fed into the tubes (31) of the generator (1). From the tubes (31) heat-carrying agent is withdrawn via pipeline (C15). The weak solution is fed into the generator (1) from the absorber (9) by the pump (11). Previously solution is pumped through the tube (15) of the heat exchanger (6) where it is heated by the heat of solution which drains from the generator (1). From the tubes (15) solution is fed through the pipeline (C15) to the distribution device (16) of the generator (1). Hot water incoming into the tubes (31) heats the working solution of lithium bromide with methanol. The temperature of the hot water does not exceed 75°... 80°C, which allows bringing the solution to the boiling point, which is at 4-6°C below the temperature of the heating water.

Methanol vapors are evolved at the boiling in the generator (1) from the solution. Methanol vapors via the bend (2) enter the condenser (3), wherein are condensed arriving at surface of the tubes (33). Condensate of the refrigerant drains from the condenser (3) into the receiver (5), from which enters the inlet branch pipe (503) of the hydraulic turbine (54) via the pipeline (C3) through the expansion valve (EV-1). Liquid refrigerant flow (methanol) is fed through the nozzle apparatus (504) onto the impeller (505) of the turbine (54) which begins to rotate and thus drives the impeller (51) of the booster (25). In the expansion valve (EV-1) as well as in the nozzle apparatus (504) throttling process takes place, the temperature and the pressure of the fluid drops to the pressure and the temperature in the evaporator (7). In this case flooded type of the evaporator is used. For such evaporators normal filling of the liquid refrigerant is 2/3 of the volume of the evaporator tube space.

The cooling agent, e.g. 35% water solution of ethylene glycol, through the pipeline (C12) is fed into the tubes (30) of the evaporator (7). The circulation of ethylene glycol in the tubes (30) causes boiling of the refrigerant in the tube space of the evaporator (7), wherein the ethylene glycol is cooled. The cooled ethylene glycol is withdrawn through the pipeline (C12) into the cooling system. The refrigerant vapor is directed by the supercharger (25) to the bend (8) through the open automatic non-return valve (12) and the inlet branch pipes (27) fed into the absorber (9). The booster (25) provides stability for a given boiling pressure in the evaporator (7) by continuously withdrawing of methanol vapors. E.g., at a temperature of -6°C of the cooled withdrawn ethylene glycol, refrigerant boiling temperature (methanol) in the evaporator (7) will be -10°...-11°C. Operating pressure in the evaporator for the given temperatures will be around of 35-40 mbar.

Methanol vapors entering the absorber (9) are absorbed by the strong solution flow which drains from the generator (1) through the pipeline (C7). Since a strong solution, which drains from the generator (1) has a high temperature it is previously directed to the tube space (17) of 248315/2 the heat exchanger (6). The temperature of the solution is reduced In the heat exchanger (6) by the flow of weak solution, which is fed to the tubes (15) from the absorber (9). A cold weak solution is withdrawn by the pump (11) from the bottom portion (22) of the absorber (9) through the three-way valve (14) through the pipeline (C4). In the regenerative heat exchanger (6) takes place heat exchange between the strong and weak solution. Due to heat of the strong solution the weak solution is heated, and the strong solution is cooled. Preheated in a heat exchanger (6) the weak solution is directed through the pipeline (C6) into the main distribution pipe (101) of the distribution device (16) of the generator (1). From the main distribution pipe (101) the solution is fed into the sprinkling trays (105) and through the slots (107) evenly irrigates the heat exchange tubes (31) of the generator (1). Finely dispersed spraying of the solution is achieved in that the slots (107) are closed by the meshes with different mesh value. In the generator (1) by spraying of the weak solution with the help of the sprinkling trays (105), methanol boiling begins when the part of the liquid is still in the droplet state. This reduces both the temperature of heating and the energy consumption in the generator.

Feeding of the weak solution from the absorber (9) into the tubes (15) of the heat exchanger (6) is carried out by the pump (11) through the pipeline (C 5). The strong solution enters the tube space (18) of the subcooler (10) from the tube space (17) of the heat exchanger (6). Additional cooling of the solution in subcooler (10) is carried out by the water, which is fed from the tubes (20) of the absorber (9) through the pipeline ( o). The water is withdrawn from the tubes (21) through the pipeline (Cn) into the cooling tower. The strong solution cooled in a heat exchanger (6) and the subcooler (10) is fed into the main distribution pipe (101) of the distribution device (19) of the absorber (9) through the expansion valve (EV-2) through the pipeline (C8). The solution from the main distribution pipe (101) enters sprinkling trays (105) and uniformly drains through the drain holes (109) to the spraying mesh (602). The solution from the spraying mesh (602) uniformly irrigates the heat exchange tubes (20) in the form of the fine drops. The spraying mesh (602) increases amount of the fine drops of the liquid thereby increasing the mass transfer contact surface during methanol vapors absorption. The booster (28), which increases the flow velocity of methanol vapors at their feed to the absorber, is turned on. Finely dispersed spraying and increased speed of the vapors input provides high efficiency of the vapor absorption of methanol by the strong solution.

Required operating mode, e.g. boiling temperature in the evaporator (7) -10°C, is set by adjusting the amount and temperature of the cooling water, which is fed into the tubes (20) of the absorber (9) and, thus into the tubes (33) of the condenser (3). Amount and temperature, e.g. +70°C, of hot water that is fed into the tubes (31) of the generator (1) are also set. The flow rate of the heating water is controlled by a 3 -way valve (32). In steady operating mode, refrigerant temperature on leaving from the evaporator to be maintained about -6°...-7°C. This operation mode of the refrigerating machine is maintained by the automatic control and adjustment system. Routine inspection of the sealing systems of the circulating pump and superchargers is performed at least once a year. The refrigerating machine is intended for long term operation (up to 7-9 years) without repair and stops.

Claims (4)

248315/2 Claims What is claimed is:

1. An absorption refrigerating machine, in which the working solution is a solution of lithium bromide in methyl alcohol, containing an absorber, a generator, an evaporator, a condenser, a heat exchanger, a subcooler and a pump to pump the solution has the following distinguishing features: a) an evaporator and an absorber provided with at least two branch pipes and respectively interconnected by at least two bends for vapor feeding from the evaporator into the absorber; b) an evaporator and an absorber interconnected by pipeline for draining liquid refrigerant from the evaporator into the absorber; c) an absorber which provided with a mechanical booster, which is mounted in the inlet branch pipe of the apparatus for increasing the speed of methanol vapor entering into the absorber space and so as for the increasing of the absorption capacity of the solution; d) an evaporator which provided with a mechanical booster which is installed in the outlet branch pipe of the apparatus for overcoming the pressure difference of methanol vapor in the absorber and evaporator; e) a mechanical booster of the evaporator being which is provided with a hydraulic drive comprising a hydraulic turbine and so as that uses flow energy of a refrigerant coming from the receiver into the evaporator; f) an absorber and a generator equipped with a fan-type distribution device, which is installed above the tube bundle of heat exchange tubes; g) an absorber provided with a spraying mesh installed between the distribution device and the tube bundle of heat exchange tubes; h) at the bottom of the absorber along its length, the heating elements are installed to prevent a possible crystallization of the solution during technological and other types of stops; i) a generator equipped with the drop catchers that are installed in the outlet branch pipes of the apparatus.

2. An absorption refrigeration machine according to claim 1, wherein before the inlet branch pipes of the absorber self actuated check valves are mounted.

3. An absorption refrigeration machine according to claim 1, wherein a mechanical booster is designed as a centrifugal wheel or axial impeller.

4. An absorption refrigeration machine according to claim 1, wherein a distribution device of the absorber and a generator comprises a main distribution pipe, along of the both sides of which tangential to lower generatrix sprinkling trays are installed. 15