Water inlet system of deaerator

Abstract

The utility model belongs to the field of chemical engineering, and particularly relates to a water inlet system of a deaerator. The water inlet system of the deaerator comprises a flash tank used for carrying out flash evaporation on first fluid to obtain second fluid, and the first fluid is high-pressure condensate, medium-pressure condensate or a mixture of the high-pressure condensate and the medium-pressure condensate; the condensate refining system is used for purifying third fluid to obtain fourth fluid, and the third fluid is low-pressure condensate, compressor turbine condensate or a mixture of the low-pressure condensate and the compressor turbine condensate; the heat exchanger is used for conducting heat exchange on the second fluid and the fourth fluid, and the second fluid and the fourth fluid are converted into fifth fluid and sixth fluid correspondingly; the liquid level adjusting valve is used for reducing the pressure of the fifth fluid to obtain seventh fluid; and the deaerator is used for deoxidizing the seventh fluid and the sixth fluid. 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 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 utility model, 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 the water inlet pipeline of the deaerator are relieved.

Description

Technical Field

[0001] This utility model belongs to the field of chemical industry, and specifically relates to a deaerator water inlet system. Background Technology

[0002] Chemical plants, to comprehensively utilize steam heat energy, are generally designed with different pressure levels of steam, such as high-pressure, medium-pressure, and low-pressure, to supply users with different needs. The condensate generated at the corresponding pressure level after users consume heat energy is collected centrally. Typically, high-pressure and medium-pressure condensate undergoes secondary flash evaporation to generate some steam for reuse, and the flash-evaporated condensate is directly sent to the deaerator. Low-pressure condensate and compressor turbine condensate, due to their lower operating pressure, are prone to carrying impurities such as organic carbon, calcium and magnesium ions, and silica, and require purification before being sent to the deaerator. Finally, both portions of condensate, after being deoxygenated in the deaerator to remove dissolved oxygen, are returned to the boiler as boiler feedwater to generate steam.

[0003] The typical deaerator feedwater process generally includes the following steps: 1. Low-pressure condensate and compressor turbine condensate, after purification by the condensate refining system, are in a subcooled state, with a typical operating temperature of approximately 55–85°C and a pressure of approximately 0.17–0.2 MPaG, and are directly sent to the deaerator, whose typical operating pressure is approximately 70 kPaG. 2. High-pressure and medium-pressure condensate undergo secondary flash evaporation in a flash tank to generate some steam, leaving the condensate at the bottom of the tank in a saturated state, with a typical operating temperature of approximately 150°C and a pressure of approximately 0.4 MPaG. 3. The flash tank is connected to a level control valve. After the high-pressure and medium-pressure condensate at the bottom of the tank flows through the level control valve, its pressure decreases, and it partially vaporizes, forming a two-phase flow. The typical operating pressure after the level control valve is approximately 0.17–0.2 MPaG, and the operating temperature is approximately 130–140°C.

[0004] In the two inlet waters of the deaerator, the low-pressure condensate and turbine condensate are first further cooled by the condensate refining system and are in a subcooled state. Generally, steam stripping is used in the deaerator for deoxygenation. The high-pressure and medium-pressure condensate are sent out from the bottom of the flash tank and are in a saturated state. After being throttled by the liquid level regulating valve, they partially vaporize to form a two-phase flow, which can easily cause erosion and thinning of the conveying pipeline or even further leakage and failure. Utility Model Content

[0005] This utility model addresses the aforementioned problems in the existing technology by proposing a deaerator water inlet system.

[0006] Specifically, this utility model provides a deaerator water inlet system, the deaerator water inlet system comprising:

[0007] A flash evaporator is used to flash evaporate 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 a high-pressure condensate and a medium-pressure condensate;

[0008] A condensate purification system is used to purify a 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 is used to exchange heat between a second fluid and a fourth fluid, which are then converted into a fifth fluid and a sixth fluid, respectively.

[0010] A level control valve is used to reduce the pressure of the fifth fluid to obtain the seventh fluid; and

[0011] A deaerator is used to deoxygenate the seventh and sixth fluids.

[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 at the bottom of the flash tank, the second fluid is in a saturated state, and its temperature is 145-160°C and its pressure is 0.35-0.50 MPaG.

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

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

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

[0020] In one or more embodiments, the deaerator operates at a pressure of 50–80 kPaG.

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

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

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

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

[0025] The pipes connecting the liquid level regulating valve and the deaerator; and

[0026] A pipe connecting the second outlet of the heat exchanger and the deaerator;

[0027] The heat exchanger has a first inlet and a first outlet connected together, and a second inlet and a second outlet connected together.

[0028] This utility model also includes a method for supplying water to the deaerator inlet system described in any embodiment of the present invention, the method comprising the following steps:

[0029] The first fluid is passed into the flash tank for flash evaporation to obtain the second fluid;

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

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

[0032] The fifth fluid is depressurized through the liquid level regulating valve to obtain the seventh fluid;

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

[0034] This invention optimizes the process of the two inlet water sections entering the deaerator by adding a heat exchanger before the level regulating valve. Without consuming additional energy or wasting energy, the saturated high-pressure and medium-pressure flash tank bottom condensate is converted into subcooled condensate. At the same time, the low-pressure condensate and compressor turbine condensate after heat exchange remain in a subcooled state. This greatly reduces the vaporization rate of the fluid after throttling through the level regulating valve and alleviates the problem of thinning or even perforation failure of the deaerator inlet water pipe caused by two-phase flow erosion. Attached Figure Description

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

[0036] Figure 2 This is a flow chart of the deaerator water inlet process of this utility model.

[0037] The following are the annotations in the attached diagram: 1 is a flash tank; 2 is a level control valve; 3 is a condensate purification system; 4 is a deaerator; and 5 is a heat exchanger. Detailed Implementation

[0038] To enable those skilled in the art to understand the features and effects of this utility model, the terms and expressions mentioned herein are explained and defined in general terms below. Unless otherwise specified, all technical and scientific terms used herein have the common meaning understood by those skilled in the art regarding this utility model, and in case of conflict, the definitions in this specification shall prevail.

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

[0040] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0041] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0042] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0043] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the present invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the present invention.

[0044] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0045] The deaerator water inlet system of this utility model includes:

[0046] A flash evaporator is used to flash evaporate 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 a high-pressure condensate and a medium-pressure condensate;

[0047] A condensate purification system is used to purify a 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 is used to exchange heat between a second fluid and a fourth fluid, which are then converted into a fifth fluid and a sixth fluid, respectively.

[0049] A level control valve is used to reduce the pressure of the fifth fluid to obtain the seventh fluid; and

[0050] A deaerator is used to deoxygenate the seventh and sixth fluids.

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

[0052] The second fluid is the condensate at the bottom of the flash tank, which is in a saturated state and has 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, and 160°C; and a pressure of 0.35–0.50 MPaG, for example, 0.35 MPaG, 0.37 MPaG, 0.39 MPaG, 0.40 MPaG, 0.41 MPaG, 0.43 MPaG, 0.45 MPaG, 0.47 MPaG, and 0.49 MPaG.

[0053] In this invention, the flash evaporator can flash evaporate 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℃, for example, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃. Temperatures range from 100℃ to 109℃; pressures range from 0.4 to 1.2 MPaG, for example, 0.45 MPaG, 0.5 MPaG, 0.55 MPaG, 0.6 MPaG, 0.65 MPaG, 0.7 MPaG, 0.75 MPaG, 0.8 MPaG, 0.85 MPaG, 0.9 MPaG, 0.95 MPaG, 1 MPaG, 1.05 MPaG, 1.1 MPaG, and 1.15 MPaG.

[0055] The fourth fluid is in a subcooled 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 0.17–0.2 MPaG, for example 0.175 MPaG, 0.18 MPaG, 0.185 MPaG, 0.19 MPaG, 0.195 MPaG.

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

[0057] The fifth fluid is in a subcooled state, with the same pressure as the second fluid, and a temperature of 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 subcooled state, with the same pressure as the fourth fluid, and a temperature of 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 this invention, the heat exchanger can exchange heat between the second and fourth fluids at the aforementioned temperatures and pressures to obtain the fifth and sixth fluids at the aforementioned temperatures and pressures.

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

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

[0062] In this 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, level control valve and deaerator applicable to this utility model are all of known structure and can be purchased commercially.

[0064] In this invention, the fifth fluid, after heat exchange, is sent to the deaerator after being depressurized by a level regulating valve. Because the subcooling before the valve is sufficient, vaporization is basically not achieved or the vaporization rate is greatly reduced after throttling, thus effectively alleviating the problem of pipeline erosion and thinning.

[0065] In this invention, thermal insulation can be installed on each pipe of the deaerator inlet water system to reduce heat loss.

[0066] In this invention, heat exchange takes place between the low-pressure condensate and the compressor turbine condensate inlet of the deaerator and the high-pressure and medium-pressure condensate inlet. Apart from a small amount of heat loss, the optimized process will not cause significant heat loss, nor will it increase the consumption of deaeration steam required by the deaerator.

[0067] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art, unless otherwise stated. The apparatus and compounds in the embodiments are all commercially available.

[0068] Equipment Example 1

[0069] This equipment example provides a deaerator inlet water system. For example... Figure 2 As shown, the deaerator inlet water system includes: a flash tank 1, a condensate purification system 3, a heat exchanger 5, a 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 and the first outlet of the heat exchanger are connected, and the second inlet and the second outlet of the heat exchanger are connected. The deaerator inlet water system also includes: a pipe connecting the flash tank 1 and the first inlet of the heat exchanger 5; a pipe connecting the condensate purification system 3 and the second inlet of the heat exchanger 5; a pipe connecting the first outlet of the heat exchanger 5 and the level regulating valve 2; a pipe connecting the level regulating valve 2 and the deaerator 4; and a pipe 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 for water intake, and includes the following steps:

[0072] A mixture of high-pressure condensate and medium-pressure condensate with 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 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 at a pressure of 0.4–1.2 MPaG and a temperature of 55–110°C and compressor turbine condensate is passed into a condensate refining system for purification to remove organic carbon, calcium and magnesium ions and silica, resulting in a refined mixture of low-pressure condensate and compressor turbine condensate (in a subcooled state, at a temperature of 82°C and a pressure of 0.19 MPaG).

[0074] The mixture of flash tank bottom condensate, refined low-pressure condensate, and compressor turbine condensate is fed into the heat exchanger at rates of 250 tons / hour and 340 tons / hour, respectively, for heat exchange. The flash tank bottom condensate enters through the first inlet, while the mixture of refined low-pressure condensate and compressor turbine condensate enters through the second inlet. The cooled condensate (in a subcooled state, temperature 113℃, pressure 0.4MPaG) is obtained from the first outlet, and the heated mixture of low-pressure condensate and compressor turbine condensate (still in a subcooled state, temperature 106℃, pressure 0.19MPaG) is obtained from the second outlet.

[0075] The cooled condensate is depressurized to 0.19 MPaG (temperature below 113℃, in a supercooled state) through a level regulating valve;

[0076] The mixture of depressurized condensate, heated low-pressure condensate, and compressor turbine condensate is fed into a deaerator for deoxygenation. The deaerator operates at a pressure of 0.071 MPaG.

[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 rises to 106°C, remaining subcooled at an operating pressure of 0.19 MPaG. The temperature of the condensate at the first outlet of the heat exchanger drops to 113°C, and after being throttled and depressurized to 0.19 MPaG by the level control valve, it also remains subcooled, preventing the formation of a gas-liquid two-phase flow in the pipeline and significantly mitigating pipeline thinning caused by erosion. The pipeline length from the level control valve to the deaerator inlet is 100 meters. Following the process of this embodiment, the deaerator inlet water system of Equipment Example 1 has operated stably for over one year after commissioning without any pipeline leaks. Actual pipeline thickness measurement revealed no obvious signs of erosion thinning.

[0078] Comparative Example 1

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

[0080] A mixture of high-pressure condensate and medium-pressure condensate with 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 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 at a pressure of 0.4–1.2 MPaG and a temperature of 55–110°C and compressor turbine condensate is passed into a condensate refining system for purification to remove organic carbon, calcium and magnesium ions and silica, resulting in a refined mixture of low-pressure condensate and compressor turbine condensate (in a subcooled state, at a temperature of 82°C and a pressure of 0.19 MPaG).

[0082] The pressure of the condensate at the bottom of the flash tank is reduced to 0.19 MPaG (temperature 139℃) through the level regulating valve;

[0083] The mixture of the condensate at the bottom of the flash tank after depressurization, the refined low-pressure condensate, and the condensate from the compressor turbine is fed into the deaerator at rates of 250 tons / hour and 340 tons / hour, respectively, for deoxygenation. The deaerator operates at a pressure of 0.071 MPaG.

[0084] In this comparative example, the pipeline from the level control valve to the deaerator inlet is 100 meters long, and has long suffered from severe erosion and thinning. During a major overhaul, all defective pipe sections were replaced. About one year after the unit was started up, a leak reappeared at the newly replaced elbow. Before the next major overhaul (about 5 years after operation), a total of 8 leakage failure points were found. Thickness measurements of the remaining pipelines showed significant thinning, posing a great risk to the long-term safe and stable operation of the unit.

Claims

1. A deaerator inlet water system, characterized in that, The deaerator inlet water system includes: A flash evaporator is used to flash evaporate 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 a high-pressure condensate and a medium-pressure condensate; A condensate purification system is used to purify a 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 is used to exchange heat between a second fluid and a fourth fluid, which are then converted into a fifth fluid and a sixth fluid, respectively. A level control valve is used to reduce the pressure of the fifth fluid to obtain the seventh fluid; and A deaerator is used to deoxygenate the seventh and sixth fluids.

2. The deaerator inlet water system as described in 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 145-160°C and a pressure of 0.35-0.50 MPaG.

3. The deaerator inlet water system as described in claim 1, characterized in that, The condensate purification system is used to remove impurities from the third fluid, including organic carbon, calcium and magnesium ions, and silicon dioxide. The temperature of the third fluid is 55–110°C, and the pressure is 0.4–1.2 MPaG. The fourth fluid is in a subcooled state, with a temperature of 55–85°C and a pressure of 0.17–0.2 MPaG.

4. The deaerator inlet water system as described in 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 inlet water system as described in claim 1, characterized in that, The sixth fluid is in a subcooled 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 inlet water system as described in claim 1, characterized in that, The seventh fluid is in a subcooled state, the pressure of the seventh fluid is 0.17 to 0.2 MPaG, and the temperature of the seventh fluid is lower than that of the fifth fluid.

7. The deaerator inlet water system as described in claim 1, characterized in that, The deaerator operates at a pressure of 50–80 kPaG.

8. The deaerator inlet water system as described in claim 1, characterized in that, The deaerator inlet water system also includes: Piping connecting the flash tank and the first inlet of the heat exchanger; Piping connecting the condensate refining system and the second inlet of the heat exchanger; A pipe connecting the first outlet of the heat exchanger and the liquid level regulating valve; The pipes connecting the liquid level regulating valve and the deaerator; and A pipe connecting the second outlet of the heat exchanger and the deaerator; The heat exchanger has a first inlet and a first outlet connected together, and a second inlet and a second outlet connected together.

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