AU2020200018A1

AU2020200018A1 - System and method for recycling condensed water produced in air compressor cooler

Info

Publication number: AU2020200018A1
Application number: AU2020200018A
Authority: AU
Inventors: Alain Briglia
Original assignee: Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2018-12-28
Filing date: 2020-01-02
Publication date: 2020-07-16
Also published as: EA201992887A2; EA201992887A3; CN109555666A; CN109555666B

Abstract

System for recycling condensed water produced in an air compressor cooler, comprising: a starting material air intake pipeline, an air compressor, an air compressor cooling system comprising an intercooler and/or an aftercooler, a condensed water storage tank, a condensed water filtration and pump system, and a condensed water fogging apparatus; starting material air that has been pressurized in the air compressor can be cooled in the cooler to generate condensed water, wherein the starting material air intake pipeline is connected to the air compressor, the intercooler and/or aftercooler of the air compressor cooling system is/are connected to the condensed water storage tank, the condensed water storage tank is connected to the condensed water filtration and pump system and the condensed water fogging apparatus in sequence, and the condensed water fogging apparatus comprises a nozzle and is disposed in the starting material air intake pipeline. Fi.21 22 5 3 S LI ------- _____2 r i -- ------ ----- 9 10I' * 23 ------------- ff----- -- Fig.1 1/1 Drawing accompanying description 12 1 14 21 I ii 2 3 - - ----------- 9 ' 10 23 Fig.1

Description

1/1 Drawing accompanying description

12 21 1

14 Ii 2 3

- - ----------- 9

' 10

23

Fig.1

Description

SYSTEM AND METHOD FOR RECYCLING CONDENSED WATER PRODUCED IN AIR COMPRESSOR COOLER

Technical Field

[0001] The present invention relates to a system and method for recycling condensed water, in particular to a system and method for recycling condensed water produced in an air

compressor cooler.

Background Art

[0002] Air compressors are widely used in fields such as steel, electric power, chemical

industry, petroleum natural gas, mining and machinery manufacture. In order to increase the output power of large air compressors, methods for reducing the inlet temperature of the gas

being compressed are generally employed, including fogging, wet compression and evaporative cooling, etc. When the air compressor is driven by a condensing steam turbine, the output power

of the steam turbine is also influenced by the air-cooled condenser connected thereto. The more

fully the steam is cooled in the air-cooled condenser, the higher the output power of the steam turbine. When the saturated dampness of air is low, the cooling performance of the air-cooled

condenser can be increased by increasing the dampness of the air stream.

[0003] The fogging of air compressor inlet air or increasing the dampness of the air stream in an air-cooled condenser both require demineralized water, and this requirement is particularly

urgent in hot weather. However, in arid regions, the use of large amounts ofdemineralized water will greatly increase operating costs; hence, the abovementioned measures for saving energy and

reducing consumption are often unable to be implemented.

[0004] Condensed water is generally produced in the intercoolers and aftercooler of a large

staged air compressor. In the prior art, this type of condensed water is often not utilized, and pollutes the environment when discharged as waste water.

[0005] CN205940194U has disclosed a condensed water separation and centralized discharge system for an air compressor, wherein condensed water collected via a multi-stage gas/water

separator and a water collector is gathered in a centralized waste discharge pipe for discharge.

[0006] CN202073793U has disclosed an external fogging water-jetting cooling system for an air compressor main unit. Condensed water produced during operation of the air compressor is

sprayed in the form of a mist onto a housing of the air compressor main unit, vaporizing to cool the main unit, in order to attain the objectives of rational utilization of water resources, rapid

reduction of the air compressor main unit temperature and the operating environment

temperature, reducing energy consumption and extending lifespan.

Content of the invention

[0007] The technical problem to be solved by the present invention is how to reduce the energy consumption of equipment such as air compressors, condensing steam turbines and air

cooled condensers, and improve the operating performance thereof, while reducing the consumption of additional water, especially in hot and dry environments.

[0008] In order to solve the abovementioned technical problem, a system for recycling condensed water produced in an air compressor cooler is used, the system comprising a

starting material air intake pipeline, an air compressor, an air compressor cooling system comprising an intercooler and/or an aftercooler, a condensed water storage tank, a condensed

water filtration and pump system, and a condensed water fogging apparatus, wherein the starting material air intake pipeline is connected to the air compressor, the intercooler and/or

aftercooler of the air compressor cooling system is/are connected to the condensed water storage tank, the condensed water storage tank is connected to the condensed water filtration

and pump system, the condensed water fogging apparatus and the starting material air intake

pipeline in sequence, and the condensed water fogging apparatus comprises a nozzle and is disposed in the starting material air intake pipeline. Starting material air that has been

pressurized in different stages of the air compressor is cooled in the cooler to generate condensed water, and at least a portion of condensed water is conveyed into the condensed water storage tank; when necessary, at least a portion of condensed water in the condensed water storage tank is processed by the condensed water filtration and pump system, and is then atomized in the condensed water fogging apparatus and enters the starting material air intake pipeline to lower the temperature of starting material air.

[0009] The abovementioned system may further comprise a condensing steam turbine driving the air compressor, an air-cooled condenser, and a boiler for reheating steam, wherein

the condensing steam turbine, the air-cooled condenser and the boiler are connected to form a thermodynamic cycle of steam, the condensed water filtration and pump system is connected

to the air-cooled condenser, and at least a portion of condensed water in the condensed water

storage tank is processed by the condensed water filtration and pump system, then enters the air-cooled condenser as a spray to enhance a heat transfer effect of the air-cooled condenser.

[0010] Optionally, another system for recycling condensed water produced in an air

compressor cooler may also be used, this system comprising a starting material air intake pipeline, an air compressor, an air compressor cooling system comprising an intercooler and/or an

aftercooler, a condensed water storage tank, a condensed water filtration and pump system, a condensing steam turbine driving the air compressor, an air-cooled condenser, and a boiler for

reheating steam; the condensing steam turbine, the air-cooled condenser and the boiler are

connected to form a thermodynamic cycle of steam, the starting material air intake pipeline is connected to the air compressor, the intercooler and/or aftercooler of the air compressor cooling

system is/are connected to the condensed water storage tank, and the condensed water storage tank is connected to the condensed water filtration and pump system and the air-cooled

condenser in sequence, wherein pressurized starting material air is cooled in the cooler to generate condensed water, and at least a portion of condensed water is conveyed into the

condensed water storage tank; when necessary, at least a portion of condensed water in the condensed water storage tank is processed by the condensed water filtration and pump system,

then enters the air-cooled condenser as a spray to enhance a heat transfer effect of the air-cooled

condenser.

[0011] The other system mentioned above may further comprise a condensed water fogging apparatus, having one end connected to the starting material air intake pipeline and another end connected to the condensed water filtration and pump system; the condensed water fogging apparatus comprises a nozzle and is disposed in the starting material air intake pipeline, wherein at least a portion of condensed water in the condensed water storage tank is processed by the condensed water filtration and pump system, and is then atomized in the condensed water fogging apparatus and enters the starting material air intake pipeline to lower the temperature of starting material air.

[0012] The air compressor cooling system in each of the systems mentioned above comprises a cooling water driving apparatus, a water intake pipeline and a water output pipeline.

[0013] The air-cooled condenser comprises a humidification-type air cooler, a spray-type air cooler and a surface-evaporation-type air cooler.

[0014] Preferably, the condensed water storage tank is further connected to a replenishment water pipeline.

[0015] Each of the systems mentioned above is used in a cryogenic air separation apparatus.

[0016] Also disclosed in the present invention is a method for recycling condensed water produced in an air compressor cooler, comprising: providing a starting material air intake pipeline, an air compressor, an air compressor cooling system comprising an intercooler and/or an aftercooler, a condensed water storage tank, a condensed water filtration and pump system, and optionally a) a condensed water fogging apparatus; and/or b) a condensing steam turbine driving the air compressor, an air-cooled condenser, and a boiler for reheating steam, wherein starting material air that has been pressurized in stages in the air compressor is cooled in the cooler to generate condensed water, and at least a portion of condensed water is conveyed into the condensed water storage tank; when necessary, condensed water in the condensed water storage tank is processed by the condensed water filtration and pump system, then optionally c) at least a portion of condensed water is atomized in the condensed water fogging apparatus and enters the starting material air intake pipeline to lower the temperature of starting material air; and/or d) at least a portion of condensed water enters the air-cooled condenser as a spray to enhance a heat transfer effect of the air-cooled condenser.

[0017] The system and method of the present invention are used to recycle condensed water

generated in the cooling system of an air compressor, such that condensed water is stored when in abundance, reducing the discharge of condensed water into the environment; in hot and dry

environments, the condensed water stored can be used to subject starting material air of the air compressor and/or inlet air of an air-cooled condenser to spraying/humidification to achieve

cooling, lowering the energy consumption of the air compressor and the air-cooled condenser, improving their performance, and thereby achieving the results of saving energy, saving water

and protecting the environment.

Description of accompanying drawing

[0018] The accompanying drawing in the present disclosure merely serves to illustrate the

present invention, such that the spirit of the present invention can be understood and explained, but does not limit the present invention in any regard. For clarity, the various

component parts of the present invention are not drawn to actual scale.

[0019] Fig. 1 is a schematic diagram of an embodiment of the present invention.

[0020] 1 - air compressor; 2 - intercooler; 3 - aftercooler; 4 - first-stage compressor; 5

second-stage compressor; 6 - condensing steam turbine; 7 - air-cooled condenser; 8 - boiler; 9 condensed water storage tank; 10 - condensed water filtration and pump system; 11

condensed water fogging apparatus; 12 - starting material air intake pipeline; 21 - air compressor cooling system; 22 - condensed water pipeline; 23 - replenishment water pipeline.

Particular embodiments

[0021] Air compressors are machines that are used to compress air and thereby increase air pressure, and generally include three basic types, namely reciprocating air compressors, rotary

air compressors and centrifugal air compressors. When it is necessary to increase the pressure of a gas to a high level, air compression is often accomplished in an air compressor in stages. In the process of compression, the temperature of a gas will increase significantly, but the gas will consume a greater amount of energy at a high temperature. For this reason, intercoolers are disposed between compression chambers of different stages, i.e. before entering the next stage, high-temperature gas exiting an intermediate stage of compression is first led into an intercooler to be cooled, and the cooled low-temperature gas is then sent into the next stage of compression. Before being utilized further, fully compressed discharge gas also correspondingly needs to be cooled to less than 40°C in an aftercooler.

[0022] The output power of an air compressor can also be improved by lowering the

temperature of starting material air at an inlet. A fogging apparatus, generally nozzles, is placed

in a gas intake pipeline for starting material air. When pressurized demineralized water passes through a row of nozzles at a pressure of 2000 psi for example, fine water droplets with

diameters at the micron scale will form, and these water droplets evaporate very quickly in a gas intake stream of starting material air, effectively lowering the temperature of the starting

material air.

[0023] The intercoolers at the various stages, and the aftercooler, are all a part of the air compressor cooling system. Coolers may be classed as air-cooled types and water-cooled types;

in general, water-cooled types are used together with multi-stage air compressors, because

water cooling has higher efficiency, and the temperature achieved through cooling is lower. Cooler styles include tubular, plate and umbrella styles, etc. For example, gas pipelines are

disposed in a shell-and-tube cooler, with a cooling water channel between the gas pipelines and a cooler housing. One end of each gas pipeline is connected via a connecting pipe to an outlet

of the gas compression chamber of the previous stage, while the other end is connected via a connecting pipe to an inlet of the compression chamber of the next stage, or to a gas discharge

port.

[0024] Besides coolers, the cooling system further comprises a cooling water driving

apparatus, a water intake pipeline and a water output pipeline. Cooling water first enters the intercooler through a pipeline and then enters the aftercooler to cool the compressed gas. It is

possible that condensed water will be produced through the cooling of gas in the coolers, so condensed water collection and discharge apparatuses will generally be disposed after the intercooler and aftercooler. Commonly encountered apparatuses of this type include gas/water separators disposed on gas pipelines, water collectors or filters/water discharge valves, etc.

[0025] Air compressors are generally driven by electric motors or steam turbines. A steam turbine is a type of rotary prime mover which converts thermal energy of steam into

mechanical work. Steam turbines are widely used in fields such as electric power and air separation, on account of having high efficiency, low energy consumption and low

manufacturing costs. Condensing steam turbines and back pressure steam turbines are two common types of steam turbine, wherein condensing steam turbines are combined with a

condenser and a boiler to realize a thermodynamic cycle of steam. The condenser plays the role

of a cold source in the abovementioned thermodynamic cycle; moreover, a high degree of vacuum is established and maintained in a steam discharge pipe of the steam turbine, and

clean condensed water is supplied as boiler feed water. As the steam discharge pressure and steam discharge temperature of the steam turbine are reduced, the thermal efficiency of the

cycle can be increased, therefore it is extremely important that a condenser with high condensing efficiency be used.

[0026] Condensers are classed as water-cooled and air-cooled according to the cooling

medium used. Compared with water cooling, air cooling has the advantages of saving water,

causing little environmental pollution and having low operating costs, but has the disadvantages of taking up a large area (or space), requiring a large one-time investment, and

being restricted by medium temperature and environment temperature. Air cooling is preferred in dry regions. However, if an increase in air temperature alone is relied upon to carry

heat away, then because the enthalpy of air is too low, the cooling temperature thereof depends on the dry-bulb temperature of air, so it is only possible to cool hot fluid in a pipe to

°C - 20°C higher than the ambient temperature; in hot desert regions, this cannot meet the requirements of high-efficiency condensing. Thus, wet air-cooled condensers, abbreviated as

wet air coolers, i.e. air coolers which rely on an increase in air temperature to carry heat away

and rely on finned pipes and fans and sprayed water to increase moisture for cooling and enhanced heat transfer, have been applied on a broad scale in recent years. Depending on the

manner in which water is jetted, wet air coolers can be further divided into three types, namely humidification-type wet air coolers, spray-type wet air coolers and surface-evaporation-type wet air coolers. For example, a humidification-type air cooler sprays water in the form of a mist at an air inlet, such that dry air is humidified and approaches the saturation temperature, and is cooled. The lower the relative humidity of dry air, the greater the degree of cooling after humidification, and the more significant the cooling effect. A spray-type air cooler, on the other hand, sprays water in the form of a mist directly onto finned pipes of a pipe bundle, and due to the evaporation of water and the humidification and cooling of air, heat transfer is enhanced. The amount of water used in spraying is only 2% - 3% of that used in a water cooler, and the heat transfer intensity can be 2 - 4 times higher than that of a dry air cooler.

[0027] Unlike the practice of discharging condensed water through a waste discharge

pipeline in the prior art, in the present invention, the condensed water that is produced and collected in each intercooler and the aftercooler is conveyed through a pipeline to a condensed

water storage tank. Climatic variation in deserts is considerable; when the ambient temperature is too high, for example in a hot summer in a desert region, the condensed water

in the condensed water storage tank is processed in a condensed water filtration and pump system, and subsequently, can be conveyed to a condensed water fogging apparatus disposed

in a starting material air intake pipeline, and/or into an air-cooled condenser to enhance the heat transfer effect of the air cooler as a spray. Suitable air-cooled condensers include

humidification-type wet air coolers and spray-type wet air coolers. The condensed water

storage tank may also be connected to a replenishment water pipeline, to guarantee the supply of water to fogging and spraying apparatuses.

[0028] Some feasible embodiments of the present invention are described demonstratively

below in conjunction with fig. 1.

[0029] In an air separation apparatus, a starting material air intake pipeline 12 is connected to a main air compressor 1. The starting material air referred to here has been precooled in a

precooling apparatus and purified in a purification apparatus; for simplicity, these apparatuses

are not shown in fig. 1. The air compressor 1 may be driven by an electric motor, a steam turbine or a gas turbine, etc. In order to achieve a better compression effect, multi-stage

compression is generally adopted in the air compressor, and air entering a compression chamber in the next stage is cooled by a cooler between compression chambers in different stages. The air compressor in fig. 1 schematically comprises compression chambers 4 and 5 in two stages, and also comprises an intercooler 2 and an aftercooler 3 which are connected by means of an air compressor cooling system 21. Due to cooling effect considerations, water cooling is generally used; thus, the air compressor cooling system 21 comprises a cooling water driving apparatus, a water intake pipeline and a water output pipeline (not shown in fig. 1).

Compressed air will produce condensed water when cooled; this condensed water is collected in the coolers, and optionally after preliminary filtration (not shown in fig. 1), is conveyed into a

condensed water storage tank 9 via a common condensed water pipeline 22.

[0030] The condensed water that is collected and stored is used in various ways throughout

the year. One way of using it is as follows: in hot weather, at least a portion of the condensed water stored in the condensed water storage tank 9 is processed in a condensed water

filtration and pump apparatus 10, and then conveyed into a condensed water fogging apparatus 11via a pipeline. The condensed water fogging apparatus 11 comprises a nozzle and

is disposed in the starting material air intake pipeline 12; condensed water can be atomized by the nozzle to form a water mist with diameters at the micron scale, and sprayed onto starting

material air so as to lower the temperature of the starting material air, thereby improving the energy consumption and output power of the air compressor.

[0031] Another way of using the condensed water is suitable for the situation in which a condensing steam turbine 6 is used to drive the air compressor 1. The condensing steam

turbine 6, an air-cooled condenser 7 and a boiler 8 are connected in sequence and form a thermodynamic cycle of steam. The condenser may use water cooling and air cooling; air

cooling is chosen here. In hot weather, at least a portion of the condensed water stored in the condensed water storage tank 9 is processed in the condensed water filtration and pump

apparatus 10, then enters the air-cooled condenser 7 and, as a spray, increases the cooling extent and efficiency of the air-cooled condenser 7, such that the gas discharge temperature of

the condensing steam turbine 6 falls, the thermal efficiency of the cycle is higher, and the

energy consumption of the condensing steam turbine 6 falls.

[0032] Yet another way of using the condensed water is as follows: condensed water stored in the condensed water storage tank 9 is processed in the condensed water filtration and pump apparatus 10, and subsequently, simultaneously is conveyed into the condensed water fogging apparatus 11and enters the air-cooled condenser 7 as a spray, thereby further improving the energy consumption of the entire system.

[0033] In order to prevent a situation whereby the condensed water produced in the air

compressor 1 is not sufficient for supply, a replenishment water pipeline 23 is added for the purpose of adding demineralized water to the condensed water storage tank 9.

[0034] Embodiment 1 below corresponds to a cryogenic rectification air separation

apparatus with an oxygen output of 2000 tons per day. The processing capacity of a main air

compressor of the apparatus is 300000 Nm 3/h. Nm 3 is normal cubic meters, denoting unit volume at 0°C and 1 standard atmosphere. The following table lists, for each month in a

particular region, the average relative humidity, average temperature, average water content of air, and correspondingly, the total water content of air compressed each month and the total

amount of condensed water produced in the air compressor each month:

Average Average Average Total water Total relative temperatur water content of amount of humidity e [°C] content of air condensed

[%] air compressed water

[kg/Nm 3] each month producedin

[ton] air compressor each month

[ton]

August 75 23 0.0155 3460 2724

September 80 17 0.0166 2589 1853

October 80 10 0.0075 1674 938

November 70 5 0.0048 1071 335

December 60 2 0.0034 759 23

January 70 -3 0.0028 625 0

February 60 0 0.0029 647 0

March 70 4 0.0045 1004 11

April 80 13 0.0091 2031 1295

May 75 18 0.0115 2567 1831

June 75 22 0.0146 3259 2523

July 60 28 0.0164 3660 2701

Total 23347 14235

annual amount

[tons]

[0035] As the table above shows, the water content of all of the air compressed in one year by an air compressor capable of processing 300000 normal cubic meters of air per hour is the

sum of the 12 months, about 23347 tons, of which about 14235 tons can be condensed in the coolers and sent into a condensed water storage tank for storage. This portion of condensed

water may be used in accordance with one or more of the embodiments listed above, in a period of time when the air temperature is highest in the region in question (different regions

will have different maximum temperatures, but in general, a period of time when the air

temperature exceeds 25 or 30°C is chosen). For example, it may enter a starting material air pipeline as a spray, in which case about 270 tons of condensed water will be consumed each

year; or be sent into an air-cooled condenser as a spray, in which case about 9100 tons of condensed water will be consumed each year. Using the condensed water collected, these two

requirements can essentially be satisfied; thus, consumption of water resources can be greatly

reduced while saving energy.

[0036] It should be understood that the embodiments above are merely intended to explain the technical solution of the present invention, without limiting the scope of protection of the present invention; those skilled in the art could make numerous amendments and changes according to the concept of the present invention without any creative effort. Thus, all technical solutions obtainable through logical analysis, inference or limited experiment by those skilled in the art, according to the concept of the present invention and on the basis of the prior art, should fall within the scope of protection determined by the claims.

Claims

1. System for recycling condensed water produced in an air compressor cooler, comprising: a starting material air intake pipeline, an air compressor, an air compressor cooling system comprising an intercooler and/or an aftercooler, a condensed water storage tank, a condensed water filtration and pump system, and a condensed water fogging apparatus; starting material air that has been pressurized in the air compressor can be cooled in the cooler to generate condensed water, wherein the starting material air intake pipeline is connected to the air compressor, the intercooler and/or aftercooler of the air compressor cooling system is/are connected to the condensed water storage tank, the condensed water storage tank is connected to the condensed water filtration and pump system and the condensed waterfogging apparatus in sequence, and the condensed waterfogging apparatus comprises a nozzle and is disposed in the starting material air intake pipeline.

2. System according to Claim 1, further comprising: a condensing steam turbine driving the air compressor, an air-cooled condenser, and a boiler for reheating steam, wherein the condensing steam turbine, the air-cooled condenser and the boiler are connected to form a thermodynamic cycle of steam, the condensed water filtration and pump system is connected to the air-cooled condenser, and at least a portion of condensed water in the condensed water storage tank is processed by the condensed water filtration and pump system, then enters the air-cooled condenser as a spray to enhance a heat transfer effect of the air-cooled condenser.

3. System for recycling condensed water produced in an air compressor cooler, comprising: a starting material air intake pipeline, an air compressor, an air compressor cooling system comprising an intercooler and/or an aftercooler, a condensed water storage tank, a condensed water filtration and pump system, a condensing steam turbine driving the air compressor, an air-cooled condenser, and a boilerfor reheating steam; the condensing steam turbine, the air-cooled condenser and the boiler are connected to form a thermodynamic cycle of steam, and starting material air that has been pressurized in the air compressor can be cooled in the cooler to generate condensed water, wherein the starting material air intake pipeline is connected to the air compressor, the intercooler and/or aftercooler of the air compressor cooling system is/are connected to the condensed water storage tank, the condensed water storage tank is connected to the condensed water filtration and pump system and the air-cooled condenser in sequence, and at least a portion of condensed water in the condensed water storage tank is processed by the condensed water filtration and pump system, then enters the air-cooled condenser as a spray to enhance a heat transfer effect of the air-cooled condenser.

4. System according to Claim 3, further comprising: a condensed water fogging apparatus, having one end connected to the starting material air

intake pipeline and another end connected to the condensed water filtration and pump

system, the condensed water fogging apparatus comprising a nozzle and being disposed in the starting material air intake pipeline, wherein at least a portion of condensed water in the

condensed water storage tank is processed by the condensed water filtration and pump system, and is then atomized in the condensed water fogging apparatus and enters the

starting material air intake pipeline to lower the temperature of starting material air.

5. System according to any one of Claims 1 - 4, wherein the air compressor cooling system further comprises a cooling water driving apparatus, a water intake pipeline and a water

output pipeline.

6. System according to any one of Claims 2 - 4, wherein:

the air-cooled condenser comprises a humidification-type air cooler, a spray-type air cooler and a surface-evaporation-type air cooler.

7. System according to any one of Claims 1 - 4, wherein the condensed water storage tank is

further connected to a replenishment water pipeline.

8. System according to Claim 7, wherein: the system is used in a cryogenic air separation

apparatus.

9. Method for recycling condensed water produced in an air compressor cooler, comprising: providing an air compressor, a starting material air intake pipeline, an air compressor cooling

system comprising an intercooler and/or an aftercooler, a condensed water storage tank, a condensed water filtration and pump system, and optionally a) a condensed water fogging apparatus; and/or b) a condensing steam turbine driving the air compressor, an air-cooled condenser, and a boiler for reheating steam; pressurized starting material air being cooled in the cooler to generate condensed water, at least a portion of condensed water being conveyed into the condensed water storage tank, and condensed water in the condensed water storage tank being processed bythe condensed water filtration and pump system, then optionally c) at least a portion of condensed water being atomized in the condensed water fogging apparatus and entering the starting material air intake pipeline to lower the temperature of starting material air; and/or d) at least a portion of condensed water entering the air-cooled condenser as a spray to enhance a heat transfer effect of the air-cooled condenser.

10. Method according to Claim 9, wherein the air compressor cooling system further comprises a cooling water driving apparatus, a water intake pipeline and a water output pipeline.

11. Method according to Claim 10, wherein the condensed water fogging apparatus comprises a

nozzle and is disposed in the starting material air intake pipeline.

12. Method according to Claim 10, wherein the air-cooled condenser comprises a humidification

type air cooler, a spray-type air cooler and a surface-evaporation-type air cooler.

13. Method according to Claim 10, wherein the condensed water storage tank is further connected to a replenishment water pipeline.