Water inlet system and water inlet method for deaerator

Abstract

The invention belongs to the field of chemical engineering, and particularly relates to a water inlet system and method for a deaerator. According to the water inlet system of the deaerator, the heat exchanger is additionally arranged in front of the liquid level adjusting valve, on the premise that no extra energy is consumed, saturated-state high-pressure and medium-pressure condensate is converted into over-condensate, and meanwhile low-pressure condensate after heat exchange and condensation of a turbine of the compressor are still in an over-cooling state. According to the invention, the vaporization rate of fluid throttled by the liquid level regulating valve is greatly reduced, and the problems of thinning, even perforation and failure caused by two-phase flow erosion of a water inlet pipeline of the deaerator are relieved.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry, and in particular relates to a deaerator water inlet system and a water inlet method. Background Art

[0002] In order to comprehensively utilize steam thermal energy, chemical plants are generally designed with steam of different pressure levels, such as high pressure, medium pressure, and low pressure, and are supplied to users with different needs. The condensate of the corresponding pressure level generated after the user consumes the heat energy will be collected uniformly. Usually, high-pressure and medium-pressure condensate are flashed to generate part of the steam for reuse, and the condensate after flashing is directly sent to the deaerator; low-pressure condensate and compressor turbine condensate are easy to carry impurities such as organic carbon, calcium and magnesium ions, and silica due to the low operating pressure, and need to be refined before being sent to the deaerator. Finally, the two parts of condensate are sent back to the boiler as boiler feed water to generate steam after the dissolved oxygen is removed by the deaerator.

[0003] The conventional deaerator water inlet process generally includes the following steps: 1. After the low-pressure condensate and compressor turbine condensate are purified by the condensate refining system, they are in a supercooled state, with a typical operating temperature of about 55-85°C and a pressure of about 0.17-0.2MPaG, and are directly sent to the deaerator. The typical operating pressure of the deaerator is about 70kPaG. 2. After the high-pressure and medium-pressure condensate are flashed twice in the flash tank to produce part of the steam, the condensate at the bottom of the tank is in a saturated state, with a typical operating temperature of about 150°C and a pressure of about 0.4MPaG. 3. The flash tank is connected to the liquid level regulating valve. After the high-pressure and medium-pressure condensate at the bottom of the tank flows through the liquid level regulating valve, the pressure is reduced and partially vaporized to form a two-phase flow. The typical operating pressure after the liquid level regulating valve is about 0.17-0.2MPaG, and the operating temperature is about 130-140°C.

[0004] Among the two parts of water inlet to the deaerator, the low-pressure condensate and turbine condensate are first further cooled by the condensate refining system and are in a supercooled state. Generally, steam stripping is required for deoxygenation in the deaerator; while the high-pressure and medium-pressure condensates are sent out from the bottom of the flash tank in a saturated state. After throttling by the liquid level regulating valve, they are partially vaporized to form a two-phase flow, which can easily cause erosion and thinning of the transmission pipeline or even further leakage and failure. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a deaerator water inlet system and a water inlet method.

[0006] Specifically, one aspect of the present invention provides a deaerator water inlet system, the deaerator water inlet system comprising:

[0007] A flash tank, used for flashing a first fluid to obtain a second fluid, wherein the first fluid is a high-pressure condensate, a medium-pressure condensate, or a mixture of the high-pressure condensate and the medium-pressure condensate;

[0008] A condensate refining system, used for purifying the third fluid to obtain a fourth fluid, wherein the third fluid is low-pressure condensate, compressor turbine condensate, or a mixture of low-pressure condensate and compressor turbine condensate;

[0009] A heat exchanger, used to perform heat exchange between the second fluid and the fourth fluid, so that the second fluid and the fourth fluid are converted into a fifth fluid and a sixth fluid respectively;

[0010] a liquid level regulating valve, used to reduce the pressure of the fifth fluid to obtain a seventh fluid; and

[0011] A deaerator is used for deoxygenating the seventh fluid and the sixth fluid.

[0012] In one or more embodiments, the temperature of the first fluid is 180-250° C., and the pressure is 1.6-2.2 MPaG.

[0013] In one or more embodiments, the second fluid is the condensate from the bottom of the flash tank, and the second fluid is in a saturated state with a temperature of 145 to 160° C. and a pressure of 0.35 to 0.50 MPaG.

[0014] In one or more embodiments, the condensate refining system is used to remove impurities in the third fluid, the impurities including organic carbon, calcium and magnesium ions, and silicon dioxide.

[0015] In one or more embodiments, the temperature of the third fluid is 55 to 110° C., and the pressure is 0.4 to 1.2 MPaG.

[0016] In one or more embodiments, the fourth fluid is in a supercooled state, with a temperature of 55 to 85° C. and a pressure of 0.17 to 0.2 MPaG.

[0017] In one or more embodiments, the fifth fluid is in a supercooled state, the pressure of the fifth fluid is the same as the pressure of the second fluid, and the temperature of the fifth fluid is 108-115°C.

[0018] In one or more embodiments, the sixth fluid is in a supercooled state, the pressure of the sixth fluid is the same as the pressure of the fourth fluid, and the temperature of the sixth fluid is 100-107°C.

[0019] In one or more embodiments, the seventh fluid is in a supercooled state, the pressure of the seventh fluid is 0.17-0.2 MPaG, and the temperature of the seventh fluid is lower than that of the fifth fluid.

[0020] In one or more embodiments, the operating pressure of the deaerator is 50 to 80 kPaG.

[0021] In one or more embodiments, the deaerator water inlet system further comprises:

[0022] a pipe connecting the flash tank and a first inlet of the heat exchanger;

[0023] a pipeline connecting the condensate refining system and the second inlet of the heat exchanger;

[0024] a pipeline connecting the first outlet of the heat exchanger and the liquid level regulating valve;

[0025] a pipeline connecting the liquid level regulating valve and the deaerator; and

[0026] a pipeline connecting the second outlet of the heat exchanger and the deaerator;

[0027] The first inlet of the heat exchanger is communicated with the first outlet, and the second inlet of the heat exchanger is communicated with the second outlet.

[0028] Another aspect of the present invention provides a method for feeding water to a deaerator water inlet system as described in any embodiment herein, the method comprising the following steps:

[0029] Passing the first fluid into the flash tank for flash evaporation to obtain the second fluid;

[0030] Passing the third fluid into the condensate refining system for purification to obtain the fourth fluid;

[0031] Passing the second fluid and the fourth fluid into the heat exchanger for heat exchange, so that the second fluid and the fourth fluid are converted into the fifth fluid and the sixth fluid respectively;

[0032] Depressurizing the fifth fluid through the liquid level regulating valve to obtain the seventh fluid;

[0033] The sixth fluid and the seventh fluid are passed into the deaerator.

[0034] The present invention optimizes the process of the two parts of water entering the deaerator, that is, a heat exchanger is added in front of the liquid level regulating valve. Under the premise of not consuming extra energy and not causing energy waste, the saturated high-pressure and medium-pressure flash tank bottom condensate is converted into supercooled liquid. At the same time, the low-pressure condensate after heat exchange and the compressor turbine condensate are still in a supercooled state, thereby greatly reducing the vaporization rate of the fluid after throttling through the liquid level regulating valve, and alleviating the problem of thinning or even perforation failure of the deaerator water inlet pipeline due to two-phase flow erosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a conventional deaerator water inlet process flow chart.

[0036] Figure 2 This is a process flow chart of water inlet into the deaerator of the present invention.

[0037] The reference numerals are as follows: 1 is a flash tank; 2 is a liquid level regulating valve; 3 is a condensate refining system; 4 is a deaerator; and 5 is a heat exchanger. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in this document. Unless otherwise specified, all technical and scientific terms used in this document have the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definitions in this specification shall prevail.

[0039] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0040] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0041] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0042] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0043] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope defined by the present invention.

[0044] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0045] The deaerator water inlet system of the present invention comprises:

[0046] A flash tank, used for flashing a first fluid to obtain a second fluid, wherein the first fluid is a high-pressure condensate, a medium-pressure condensate, or a mixture of the high-pressure condensate and the medium-pressure condensate;

[0047] A condensate refining system, used for purifying the third fluid to obtain a fourth fluid, wherein the third fluid is low-pressure condensate, compressor turbine condensate, or a mixture of low-pressure condensate and compressor turbine condensate;

[0048] A heat exchanger, used to perform heat exchange between the second fluid and the fourth fluid, so that the second fluid and the fourth fluid are converted into a fifth fluid and a sixth fluid respectively;

[0049] a liquid level regulating valve, used to reduce the pressure of the fifth fluid to obtain a seventh fluid; and

[0050] A deaerator is used for deoxygenating the seventh fluid and the sixth fluid.

[0051] The temperature of the first fluid is 180-250°C, for example, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C; the pressure is 1.6-2.2MPaG, for example, 1.65MPaG, 1.7MPaG, 1.75MPaG, 1.8MPaG, 1.85MPaG, 1.9MPaG, 1.95MPaG, 2MPaG, 2.05MPaG, 2.1MPaG, 2.15MPaG.

[0052] The second fluid is the condensate at the bottom of the flash tank, which is in a saturated state, with a temperature of 145-160°C, for example, 145°C, 147°C, 149°C, 150°C, 151°C, 153°C, 155°C, 157°C, 159°C, 160°C; and a pressure of 0.35-0.50MPaG, for example, 0.35MPaG, 0.37MPaG, 0.39MPaG, 0.40MPaG, 0.41MPaG, 0.43MPaG, 0.45MPaG, 0.47MPaG, 0.49MPaG.

[0053] In the present invention, the flash tank can flash the first fluid at the aforementioned temperature and pressure to obtain the second fluid at the aforementioned temperature and pressure.

[0054] The temperature of the third fluid is 55-110°C, for example, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C , 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃; the pressure is 0.4~1.2MPaG, for example, 0.45MPaG, 0.5MPaG, 0.55MPaG, 0.6MPaG, 0.65MPaG, 0.7MPaG, 0.75MPaG, 0.8MPaG, 0.85MPaG, 0.9MPaG, 0.95MPaG, 1MPaG, 1.05MPaG, 1.1MPaG, 1.15MPaG.

[0055] The fourth fluid is in a supercooled state, with a temperature of 55-85°C, for example, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C; and a pressure of 0.17-0.2MPaG, for example, 0.175MPaG, 0.18MPaG, 0.185MPaG, 0.19MPaG, 0.195MPaG.

[0056] In the present invention, the condensate purification system can purify the third fluid at the aforementioned temperature and pressure to obtain the fourth fluid at the aforementioned temperature and pressure.

[0057] The fifth fluid is in a supercooled state, the pressure is the same as that of the second fluid, and the temperature is 108-115°C, for example, 109°C, 109.5°C, 110°C, 110.5°C, 111°C, 111.5°C, 112°C, 112.5°C, 113°C, 113.5°C, 114°C, and 114.5°C.

[0058] The sixth fluid is in a supercooled state, the pressure is the same as that of the fourth fluid, and the temperature is 100-107°C, for example, 100.5°C, 101°C, 101.5°C, 102°C, 102.5°C, 103°C, 103.5°C, 104°C, 104.5°C, 105°C, 105.5°C, 106°C, and 106.5°C.

[0059] In the present invention, the heat exchanger can perform heat exchange on the second fluid and the fourth fluid at the aforementioned temperature and pressure to obtain the fifth fluid and the sixth fluid at the aforementioned temperature and pressure.

[0060] The seventh fluid is in a supercooled state, with a pressure of 0.17-0.2 MPaG, for example, 0.175 MPaG, 0.18 MPaG, 0.185 MPaG, 0.19 MPaG, 0.195 MPaG; and a temperature lower than that of the fifth fluid.

[0061] In the present invention, the liquid level regulating valve can reduce the pressure of the fifth fluid at the aforementioned temperature and pressure to obtain the seventh fluid at the aforementioned temperature and pressure.

[0062] In the present invention, the operating pressure of the deaerator is preferably 50-80 kPaG, for example 51 kPaG, 52 kPaG, 53 kPaG, 54 kPaG, 55 kPaG, 56 kPaG, 57 kPaG, 58 kPaG, 59 kPaG, 60 kPaG, 61 kPaG, 62 kPaG, 63 kPaG, 64 kPaG, 65 kPaG, 66 kPaG, 67 kPaG, 68 kPaG, 69 kPaG, 70 kPaG, 71 kPaG, 72 kPaG, 73 kPaG, 74 kPaG, 75 kPaG, 76 kPaG, 77 kPaG, 78 kPaG, and 79 kPaG.

[0063] The flash tank, condensate refining system, heat exchanger, liquid level regulating valve and deaerator applicable to the present invention are all of known structures and can be purchased from commercial sources.

[0064] In the present invention, the fifth fluid after heat exchange is sent to the deaerator after being depressurized by the liquid level regulating valve. Since the subcooling degree before the valve is sufficient, it will not be vaporized or the vaporization rate will be greatly reduced after throttling, thereby effectively alleviating the problem of pipeline erosion and thinning.

[0065] In the present invention, thermal insulation can be provided on each pipeline of the deaerator water inlet system to reduce heat loss.

[0066] In the present invention, heat exchange is carried out between the low-pressure condensate of the deaerator and the condensate inlet of the compressor turbine and the high-pressure and medium-pressure condensate inlet. Except for a small amount of heat dissipation loss, the optimized process will not cause obvious heat loss, nor will it cause an increase in the consumption of deoxidation steam required for the deaerator.

[0067] The present invention will be described below in the form of specific examples. It should be understood that these examples are illustrative only and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The devices and compounds in the examples can all be purchased from commercial sources.

[0068] Equipment Example 1

[0069] This equipment example provides a deaerator water inlet system. Figure 2 As shown, the deaerator water inlet system includes: a flash tank 1, a condensate refining system 3, a heat exchanger 5, a liquid level regulating valve 2 and a deaerator 4. The heat exchanger 5 includes a first inlet, a second inlet, a first outlet and a second outlet; the first inlet of the heat exchanger is connected to the first outlet, and the second inlet of the heat exchanger is connected to the second outlet. The deaerator water inlet system also includes: a pipeline connecting the flash tank 1 and the first inlet of the heat exchanger 5, a pipeline connecting the condensate refining system 3 and the second inlet of the heat exchanger 5, a pipeline connecting the first outlet of the heat exchanger 5 and the liquid level regulating valve 2, a pipeline connecting the liquid level regulating valve 2 and the deaerator 4, and a pipeline connecting the second outlet of the heat exchanger 5 and the deaerator 4.

[0070] Example 1

[0071] This embodiment uses the deaerator water inlet system of Equipment Example 1 to inlet water, including the following steps:

[0072] A mixture of high-pressure condensate and medium-pressure condensate at a pressure of 1.6-2.2 MPaG and a temperature of 180-250° C. is passed into a flash tank for flash evaporation to obtain a condensate at the bottom of the flash tank (in a saturated state, with a temperature of 151° C. and a pressure of 0.4 MPaG);

[0073] A mixture of low-pressure condensate and compressor turbine condensate at a pressure of 0.4-1.2 MPaG and a temperature of 55-110° C. is passed into a condensate refining system for purification to remove organic carbon, calcium and magnesium ions and silicon dioxide therein, thereby obtaining a refined mixture of low-pressure condensate and compressor turbine condensate (in a supercooled state, with a temperature of 82° C. and a pressure of 0.19 MPaG);

[0074] The flash tank bottom condensate, the refined low-pressure condensate and the mixture of compressor turbine condensate are respectively introduced into the heat exchanger at a rate of 250 tons / hour and 340 tons / hour for heat exchange, the flash tank bottom condensate is introduced from the first inlet, the refined low-pressure condensate and the mixture of compressor turbine condensate are introduced from the second inlet, the cooled condensate (in a supercooled state, with a temperature of 113°C and a pressure of 0.4MPaG) is obtained from the first outlet, and the heated low-pressure condensate and the mixture of compressor turbine condensate (still in a supercooled state, with a temperature of 106°C and a pressure of 0.19MPaG) is obtained from the second outlet;

[0075] The cooled condensate is decompressed to 0.19MPaG (temperature is lower than 113°C, in a supercooled state) through a liquid level regulating valve;

[0076] The mixture of the decompressed condensate, the heated low-pressure condensate and the compressor turbine condensate is respectively introduced into the deaerator for deoxygenation. The operating pressure of the deaerator is 0.071MPaG.

[0077] In this embodiment, after passing through the heat exchanger, the temperature of the mixture of low-pressure condensate and compressor turbine condensate entering the deaerator is increased to 106°C, and it is still in a supercooled state at an operating pressure of 0.19MPaG; the temperature of the condensate at the first outlet of the heat exchanger is reduced to 113°C, and it is also in a supercooled state after throttling and reducing the pressure to 0.19MPaG through the liquid level regulating valve, thereby avoiding the formation of gas-liquid two-phase flow in the pipeline, thereby greatly alleviating the thinning of the pipeline caused by the erosion effect. The length of the pipeline from the liquid level regulating valve to the deaerator inlet is 100 meters. According to the process of this embodiment, the deaerator water inlet system of Equipment Example 1 has been operating stably for more than one year after being put into use, and no pipeline leakage has occurred. After the actual pipeline thickness measurement inspection, no obvious signs of erosion and thinning were found.

[0078] Comparative Example 1

[0079] This comparative example uses Figure 1 The conventional deaerator water inlet system shown includes the following steps:

[0080] A mixture of high-pressure condensate and medium-pressure condensate at a pressure of 1.6-2.2 MPaG and a temperature of 180-250° C. is passed into a flash tank for flash evaporation to obtain a condensate at the bottom of the flash tank (in a saturated state, with a temperature of 151° C. and a pressure of 0.4 MPaG);

[0081] A mixture of low-pressure condensate and compressor turbine condensate at a pressure of 0.4-1.2 MPaG and a temperature of 55-110° C. is passed into a condensate refining system for purification to remove organic carbon, calcium and magnesium ions and silicon dioxide therein, thereby obtaining a refined mixture of low-pressure condensate and compressor turbine condensate (in a supercooled state, with a temperature of 82° C. and a pressure of 0.19 MPaG);

[0082] The condensate at the bottom of the flash tank is decompressed to 0.19 MPaG (temperature is 139°C) through the liquid level regulating valve;

[0083] The mixture of the flash tank bottom condensate after reduced pressure, the refined low-pressure condensate and the compressor turbine condensate was introduced into the deaerator at a rate of 250 tons / hour and 340 tons / hour respectively for deoxygenation. The operating pressure of the deaerator was 0.071 MPaG.

[0084] In this comparative example, the length of the pipeline from the liquid level control valve to the deaerator inlet is 100 meters, and the erosion and thinning have been serious for a long time. During a major overhaul, all defective pipe sections were replaced. After the device was started and operated for about 1 year, local leakage occurred again in the newly replaced elbows. Before the next major overhaul (that is, after about 5 years of operation), a total of 8 leakage failure points were found. The thickness measurement of the remaining pipelines found obvious thinning, which brought great risks to the long-term safe and stable operation of the device.

Claims

1. A deaerator water inlet system, characterized in that: The deaerator water inlet system comprises: A flash tank, used for flashing a first fluid to obtain a second fluid, wherein the first fluid is a high-pressure condensate, a medium-pressure condensate, or a mixture of the high-pressure condensate and the medium-pressure condensate; A condensate refining system, used for purifying the third fluid to obtain a fourth fluid, wherein the third fluid is low-pressure condensate, compressor turbine condensate, or a mixture of low-pressure condensate and compressor turbine condensate; A heat exchanger, used to perform heat exchange between the second fluid and the fourth fluid, so that the second fluid and the fourth fluid are converted into a fifth fluid and a sixth fluid respectively; a liquid level regulating valve, used to reduce the pressure of the fifth fluid to obtain a seventh fluid; and A deaerator is used for deoxygenating the seventh fluid and the sixth fluid.

2. The deaerator water inlet system according to claim 1, characterized in that: The temperature of the first fluid is 180-250°C and the pressure is 1.6-2.2 MPaG; The second fluid is the condensate at the bottom of the flash tank. The second fluid is in a saturated state, with a temperature of 145 to 160° C. and a pressure of 0.35 to 0.50 MPaG.

3. The deaerator water inlet system according to claim 1, characterized in that: The condensate refining system is used to remove impurities in the third fluid, wherein the impurities include organic carbon, calcium and magnesium ions, and silicon dioxide; The temperature of the third fluid is 55-110°C and the pressure is 0.4-1.2MPaG; The fourth fluid is in a supercooled state, with a temperature of 55-85° C. and a pressure of 0.17-0.2 MPaG.

4. The deaerator water inlet system according to claim 1, characterized in that: The fifth fluid is in a supercooled state, the pressure of the fifth fluid is the same as the pressure of the second fluid, and the temperature of the fifth fluid is 108-115°C.

5. The deaerator water inlet system according to claim 1, characterized in that: The sixth fluid is in a supercooled state, the pressure of the sixth fluid is the same as the pressure of the fourth fluid, and the temperature of the sixth fluid is 100-107°C.

6. The deaerator water inlet system according to claim 1, characterized in that: The seventh fluid is in a supercooled state, the pressure of the seventh fluid is 0.17-0.2 MPaG, and the temperature of the seventh fluid is lower than that of the fifth fluid.

7. The deaerator water inlet system according to claim 1, characterized in that: The operating pressure of the deaerator is 50-80 kPaG.

8. The deaerator water inlet system according to claim 1, characterized in that: The deaerator water inlet system also includes: a pipe connecting the flash tank and a first inlet of the heat exchanger; a pipeline connecting the condensate refining system and the second inlet of the heat exchanger; a pipeline connecting the first outlet of the heat exchanger and the liquid level regulating valve; a pipeline connecting the liquid level regulating valve and the deaerator; and a pipeline connecting the second outlet of the heat exchanger and the deaerator; The first inlet of the heat exchanger is communicated with the first outlet, and the second inlet of the heat exchanger is communicated with the second outlet.

9. A method for feeding water into a deaerator water inlet system according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: Passing the first fluid into the flash tank for flash evaporation to obtain the second fluid; Passing the third fluid into the condensate refining system for purification to obtain the fourth fluid; Passing the second fluid and the fourth fluid into the heat exchanger for heat exchange, so that the second fluid and the fourth fluid are converted into the fifth fluid and the sixth fluid respectively; Depressurizing the fifth fluid through the liquid level regulating valve to obtain the seventh fluid; The sixth fluid and the seventh fluid are passed into the deaerator.

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