Zero steam consumption boiler feed water waste heat utilization system

Abstract

The present invention relates to the field of energy-saving and environmental protection technology, and provides a zero-steam consumption boiler feed water waste heat utilization system, including: a vacuum air stripping deoxygenation unit, including a plurality of vacuum air strippers connected in series and parallel; a multi-stream heat exchanger, wherein the first heat exchange section and the deoxygenated water pipeline of the second heat exchange section are connected and the heat source pipeline is independent; a working fluid heat exchanger, wherein the water outlet of the vacuum air stripping deoxygenation unit is connected to the deoxygenated water output port through the deoxygenated water pipeline of the multi-stream heat exchanger and the deoxygenated water pipeline of the working fluid heat exchanger in turn; a working fluid evaporator, wherein one end of the heat source pipeline is connected to the heat source water inlet and the other end is connected to the heat source water return port through the heat source pipeline of the first heat exchange section, and the heat source water inlet is also connected to the heat source water return port through the heat source pipeline of the second heat exchange section, and the second working fluid pipeline of the working fluid evaporator forms a cycle with the first working fluid pipeline of the working fluid heat exchanger. The present invention can ensure that the dissolved oxygen index of the deoxygenated water is qualified, reduce the operating energy consumption, ensure that the temperature index of the deoxygenated water is qualified, and finally produce qualified boiler feed water.

Description

Technical Field

[0001] The invention relates to the technical field of energy conservation and environmental protection, and in particular to a zero-steam consumption boiler feed water waste heat utilization system. Background Art

[0002] In industry, deoxygenated water is the source of water for boiler steam production. According to the requirements of the steam production process, the dissolved oxygen index of deoxygenated water must meet the specifications of 5μg / L to 100μg / L, and the temperature must meet the specifications of 104℃ to 156℃. If the dissolved oxygen exceeds the standard, at above 100℃, oxygen corrosion will aggravate equipment corrosion, which is very harmful to the safe operation of steam production. In order to meet the requirements of boiler feed water for oxygen content, the commonly used deoxygenation methods in the prior art are: thermal deoxygenation, vacuum deoxygenation, degassing membrane deoxygenation, redox resin deoxygenation and sodium sulfite deoxygenation.

[0003] Among them, the thermal deoxygenation technology has qualified deoxygenation indicators, but the deoxygenation process requires a large amount of steam, resulting in high deoxygenation energy consumption and operating costs, high carbon emissions, and uneconomical operation. The vacuum deoxygenation and degassing membrane deoxygenation technologies have qualified deoxygenation indicators and low operating energy consumption, but the temperature of the deoxygenated water they produce is close to room temperature (20°C to 40°C), and waste heat or steam is required to heat it up in the subsequent steam production process. From a system perspective, it does not reduce energy consumption and operating costs; if the degassing membrane + waste heat utilization combination is adopted, the production of deoxygenated water at 104°C to 156°C requires the waste heat side to reach 110°C to 160°C or above, which greatly limits the scope of application of its technology. Redox resin deoxygenation and sodium sulfite deoxygenation have unstable deoxygenation indicators and require steam heating. In addition, the amount of added medicine is large, the operating cost is high, and the application is relatively limited.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In view of this, the present invention provides a zero-steam consumption boiler feed water waste heat utilization system to solve the problems existing in the existing deoxygenation technology, which can ensure that the dissolved oxygen index of the deoxygenated water is qualified, reduce the operating energy consumption cost, and ensure that the temperature index of the deoxygenated water is qualified, and finally produce qualified boiler feed water.

[0006] According to one aspect of the present invention, a zero-steam consumption boiler feed water waste heat utilization system is provided, comprising: a vacuum air stripping deoxygenation unit connected to a desalted water inlet, the vacuum air stripping deoxygenation unit comprising a plurality of vacuum air strippers connected in series, wherein the series connection nodes of adjacent vacuum air strippers are also connected to the desalted water inlet via a total water inlet pipeline; a multi-stream heat exchanger comprising a first heat exchange section and a second heat exchange section respectively comprising a deoxygenated water pipeline and a heat source pipeline, the first heat exchange section and the second heat exchange section being connected to the deoxygenated water pipeline, and the heat source pipeline being independent; a working fluid heat exchanger comprising a deoxygenated water pipeline The working fluid evaporator comprises a heat source pipeline and a second working fluid pipeline, one end of the heat source pipeline is connected to the heat source water inlet and the other end is connected to the heat source water return port via the heat source pipeline of the first heat exchange section, the heat source water inlet is also connected to the heat source water return port via the heat source pipeline of the second heat exchange section, and the second working fluid pipeline and the first working fluid pipeline form a working fluid circulation pipeline.

[0007] In some embodiments, each of the vacuum strippers has a water inlet and a water outlet, wherein the water outlet of the preceding vacuum stripper is connected in series with the water inlet of the succeeding vacuum stripper, and the series node between the water inlet of the first vacuum stripper and the water outlet of the preceding vacuum stripper and the water inlet of the succeeding vacuum stripper is connected to the desalted water inlet via the total water inlet pipeline.

[0008] In some embodiments, each of the vacuum strippers further has an air inlet and an air outlet, the air inlet of each of the vacuum strippers is connected to an inert gas inlet, and the air outlet of each of the vacuum strippers is connected to a vacuum pump.

[0009] In some embodiments, the inert gas is nitrogen, and the purity of the nitrogen is greater than or equal to 99.9%.

[0010] In some embodiments, the zero-steam consumption boiler feed water waste heat utilization system further includes: a filter connected between the desalted water inlet and the vacuum air stripping deoxygenation unit.

[0011] In some embodiments, the zero-steam consumption boiler feed water waste heat utilization system also includes: a compressor connected to the pipeline from the second working fluid pipeline to the first working fluid pipeline; and a throttling expansion valve connected to the pipeline from the first working fluid pipeline to the second working fluid pipeline.

[0012] In some embodiments, the zero-steam consumption boiler feed water waste heat utilization system further includes: a booster pump connected between the deoxygenated water pipeline and the deoxygenated water output port.

[0013] In some embodiments, the working fluid circulating in the working fluid circulation pipeline is a non-azeotropic working fluid, and the non-azeotropic working fluid comprises the following components: 5% to 35% by mass of trans-1,3,3,3-tetrafluoropropene, 10% to 15% by mass of pentafluoropropane, and 50% to 85% by mass of trans-1-chloro-3,3,3-trifluoropropene.

[0014] In some embodiments, the temperature of the desalted water entering the desalted water inlet is 20°C to 40°C and the pressure is 0.3MPag to 1.0MPag; the temperature of the heat medium water entering the heat source water inlet is 70°C to 95°C, and the temperature of the heat medium water flowing out of the heat source return water outlet is 50°C to 80°C.

[0015] In some embodiments, the temperature of the deoxygenated water flowing out of the multi-stream heat exchanger is 70°C to 90°C, and the temperature of the deoxygenated water flowing out of the deoxygenated water outlet is 104°C to 156°C and the pressure is 0.2MPag to 10MPag.

[0016] The beneficial effects of the present invention compared with the prior art include at least:

[0017] The zero steam consumption deoxygenation process proposed in the present invention is based on vacuum gas lift deoxygenation, cascade utilization of waste heat from heat sources, and upgraded utilization of waste heat from working fluid circulation. It effectively solves the problems existing in existing deoxygenation technologies, and reduces operating energy consumption costs while ensuring that the dissolved oxygen index of deoxygenated water is qualified. It fully recovers and utilizes waste heat from heat sources, achieves zero steam consumption, and has significant energy-saving benefits. It also ensures that the temperature index of deoxygenated water is qualified, and can continuously produce deoxygenated water at 104°C to 156°C as boiler feed water.

[0018] The present invention firstly realizes room temperature deoxygenation at 20°C to 40°C through a vacuum airlift deoxygenation unit to meet the deoxygenation index requirements, and then uses the waste heat of the heat source in a cascade manner to heat the deoxygenated water to 70°C to 90°C through a multi-stream heat exchanger, and then uses the working fluid circulation waste heat upgrading technology to heat the deoxygenated water to a set temperature (104°C to 156°C) through a working fluid heat exchanger. Finally, deoxygenated water of different grades is produced according to user needs. The entire process does not require steam consumption, and zero steam consumption deoxygenation is achieved throughout the process.

[0019] Among them, the vacuum airlift deoxygenation unit adopts a series-parallel combination of multiple vacuum airlifters, which can achieve deep removal of deoxygenation indicators through series connection and realize online removal, cleaning and replacement through parallel connection, without causing downtime risk to system operation, and improving the system deoxygenation indicators and operation reliability.

[0020] The working fluid is used as a circulating working fluid for waste heat upgrading and utilization. Combining the heat source cooling and deoxygenated water heating process without phase change heat characteristics, a waste heat upgrading and utilization process cycle is established. First, the waste heat of the heat source is used to evaporate the working fluid step by step through the working fluid evaporator for deep heat exchange. Then the working fluid is condensed step by step with the deoxygenated water through the working fluid heat exchanger for deep heat exchange. The temperature glide advantage of the working fluid evaporation and condensation process is used to realize the temperature change process of working fluid condensation and evaporation and the heat exchange of deoxygenated water and heat source. Considering the actual situation that the temperature of deoxygenated water and heat source is changing, this cycle process fits the actual heat exchange process, so that energy efficiency is effectively improved.

[0021] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present invention, and together with the specification are used to explain the principles of the present invention. Obviously, the accompanying drawings described below are only some embodiments of the present invention, and for those of ordinary skill in the art, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0023] Figure 1 A schematic structural diagram of a zero-steam consumption boiler feed water waste heat utilization system according to an embodiment of the present invention is shown;

[0024] Figure 2 A schematic diagram of medium flow in a zero steam consumption boiler feed water waste heat utilization system in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided to make the present invention more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art.

[0026] The accompanying drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus their repeated description will be omitted.

[0027] In the description of the present invention, "first", "second" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different components. The term "plurality" means two or more, unless otherwise clearly and specifically defined. In addition, in the description of the present invention, when it is said that a device is "connected" to another device, this includes not only the case of direct connection, but also the case of indirect connection through other elements.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and features in different embodiments may be combined with each other.

[0029] Figure 1 The structure of the zero steam consumption boiler feed water waste heat utilization system in the embodiment of the present invention is shown in FIG. Figure 1 As shown, the zero steam consumption boiler feed water waste heat utilization system provided by the embodiment of the present invention includes:

[0030] The vacuum stripping deoxygenation unit 20 is connected to the desalted water inlet 81. The vacuum stripping deoxygenation unit 20 includes a plurality of vacuum strippers connected in series (for example, a primary vacuum stripper 2A, a secondary vacuum stripper 2B, a tertiary vacuum stripper 2C, and a quaternary vacuum stripper 2D, but not limited thereto), wherein the serial nodes of adjacent vacuum strippers are also connected to the desalted water inlet 81 via a total water inlet pipeline 82;

[0031] The multi-stream heat exchanger 30 includes a first heat exchange section 3A and a second heat exchange section 3B respectively including a deoxygenated water pipeline 31 and a heat source pipeline 32 (wherein the first heat exchange section 3A is a medium temperature section of the multi-stream heat exchanger 30, and the second heat exchange section 3B is a low temperature section of the multi-stream heat exchanger 30), the deoxygenated water pipeline 31 of the first heat exchange section 3A and the second heat exchange section 3B are connected, and the heat source pipeline 32 is independent;

[0032] The working medium heat exchanger 40 includes a deoxygenated water pipeline 41 and a first working medium pipeline 42. The water outlet of the vacuum stripping deoxygenation unit 20 (i.e., the water outlet 22 of the four-stage vacuum stripper 2D) is connected to the deoxygenated water output port 84 via the deoxygenated water pipeline 31 of the first heat exchange section 3A, the deoxygenated water pipeline 31 of the second heat exchange section 3B, and the deoxygenated water pipeline 41 of the working medium heat exchanger 40 in sequence;

[0033] The working fluid evaporator 50 includes a heat source pipeline 51 and a second working fluid pipeline 52. One end of the heat source pipeline 51 of the working fluid evaporator 50 is connected to the heat source water inlet 71 and the other end is connected to the heat source water return port 72 via the heat source pipeline 32 of the first heat exchange section 3A. The heat source water inlet 71 is also connected to the heat source water return port 72 via the heat source pipeline 32 of the second heat exchange section 3B. The second working fluid pipeline 52 of the working fluid evaporator 50 and the first working fluid pipeline 42 of the working fluid heat exchanger 40 form a working fluid circulation pipeline.

[0034] The zero steam consumption deoxygenation process proposed in the present invention is based on vacuum gas lift deoxygenation, cascade utilization of waste heat from heat sources, and upgraded utilization of waste heat from working fluid circulation. It effectively solves the problems existing in existing deoxygenation technologies, and reduces operating energy consumption costs while ensuring that the dissolved oxygen index of deoxygenated water is qualified. It fully recovers and utilizes waste heat from heat sources, achieves zero steam consumption, and has significant energy-saving benefits. It also ensures that the temperature index of deoxygenated water is qualified, and can continuously produce deoxygenated water at 104°C to 156°C as boiler feed water.

[0035] The present invention firstly realizes room temperature deoxygenation at 20°C to 40°C through the vacuum air stripping deoxygenation unit 20 to meet the deoxygenation index requirements, and then utilizes the waste heat of the heat source in a cascade manner, and heats the deoxygenated water to 70°C to 90°C through the multi-stream heat exchanger 30, and then utilizes the working fluid circulation waste heat upgrading technology to heat the deoxygenated water to a set temperature (104°C to 156°C) through the working fluid heat exchanger 40, and finally produces deoxygenated water of different grades according to user needs. The whole process does not require steam consumption, and zero steam consumption deoxygenation is achieved in the whole process.

[0036] Among them, the vacuum air stripping deoxygenation unit 20 adopts a series-parallel combination of multiple vacuum air strippers, which can achieve deep removal of deoxygenation indicators through series connection and online removal, cleaning and replacement through parallel connection, without causing downtime risks for system operation, thereby improving the system deoxygenation indicators and operation reliability.

[0037] The working fluid is used as a circulating working fluid for waste heat upgrading and utilization. In combination with the heat source cooling and deoxygenated water heating process without phase change heat change characteristics, a waste heat upgrading and utilization process cycle is established. First, the waste heat of the heat source is used to evaporate the working fluid step by step through the working fluid evaporator 50 for deep heat exchange. Then, the working fluid is condensed step by step with the deoxygenated water through the working fluid heat exchanger 40 for deep heat exchange. The temperature glide advantage of the working fluid evaporation and condensation process is used to realize the temperature change process of the working fluid condensation and evaporation and the heat exchange between the deoxygenated water and the heat source. Considering the actual situation that the temperature of the deoxygenated water and the heat source is changing, the cycle process fits the actual heat exchange process, so that the energy efficiency is effectively improved.

[0038] Compared with conventional traditional thermal deoxygenation technology, the present invention can produce deoxygenated water of the same quality, with cost and energy consumption reduced by more than 60%; the present invention also does not require the consumption of steam, achieving zero steam consumption deoxygenation in the entire process.

[0039] Compared with conventional degassing membrane deoxygenation technology, the present invention adopts a series-parallel combination process of vacuum air stripping devices to achieve deep removal of deoxygenation indicators and online removal, cleaning and replacement, thereby improving the system's deoxygenation indicators and operational reliability; and the present invention can produce deoxygenated water at 104°C to 156°C according to user needs, which is significantly different from the water supply indicators of conventional degassing membrane deoxygenation technology.

[0040] Compared with the conventional room temperature deoxygenation + waste heat heat exchange technology, the present invention effectively solves the problem that deoxygenated water above 100°C cannot be produced, or even if deoxygenated water above 100°C is produced, the waste heat quality requirement is very high, resulting in the problem that if deoxygenated water of 104°C to 156°C needs to be produced, the waste heat side is required to reach 110°C to 160°C or above; the present invention does not require high waste heat quality, and can use conventional heat medium water as a heat source. Through the method of cascade heat exchange + waste heat upgrading and utilization, the deoxygenated water is gradually heated to the set temperature, which not only meets the user's quality requirements for deoxygenated water, but also does not require high waste heat quality, and the scope of application is greatly expanded.

[0041] In some embodiments, each vacuum stripper has a water inlet and a water outlet, wherein the water outlet of the preceding vacuum stripper is connected in series with the water inlet of the succeeding vacuum stripper (i.e., the water outlet 22 of the primary vacuum stripper 2A is connected in series with the water inlet 21 of the secondary vacuum stripper 2B, the water outlet 22 of the secondary vacuum stripper 2B is connected in series with the water inlet 21 of the tertiary vacuum stripper 2C, the water outlet 22 of the tertiary vacuum stripper 2C is connected in series with the water inlet 21 of the quaternary vacuum stripper 2D), and the first The water inlet of each vacuum air stripper (i.e., the water inlet 21 of the first-stage vacuum air stripper 2A) and the series nodes between the water outlet of the previous vacuum air stripper and the water inlet of the next vacuum air stripper (including the series node between the first-stage vacuum air stripper 2A and the second-stage vacuum air stripper 2B, the series node between the second-stage vacuum air stripper 2B and the third-stage vacuum air stripper 2C, and the series node between the third-stage vacuum air stripper 2C and the fourth-stage vacuum air stripper 2D) are connected to the desalted water inlet 81 via the main water inlet pipeline 82.

[0042] In some embodiments, each vacuum stripper further has an air inlet and an air outlet. The air inlet of each vacuum stripper is connected to the inert gas inlet 91 , and the air outlet of each vacuum stripper is connected to the vacuum pump 92 .

[0043] The vacuum stripper is provided with a polymer internal component, which only allows oxygen molecules dissolved in the desalted water to pass through; in addition, under the negative pressure of the vacuum pump 92 and the action of the inert gas, the dissolved oxygen in the desalted water is continuously removed step by step through multiple vacuum strippers, and finally the deoxygenated water index requirements (usually designed to be no higher than 7ppb) are met.

[0044] In some embodiments, the inert gas is nitrogen, and the purity of the nitrogen is greater than or equal to 99.9%. By designing the purity of the nitrogen to be greater than or equal to 99.9% (mol%), the deoxygenation effect of the desalted water is ensured.

[0045] In some embodiments, the zero-steam consumption boiler feed water waste heat utilization system further includes: a filter 10 connected between the desalted water inlet 81 and the vacuum air stripping deoxygenation unit 20. The filter 10 is used to deeply remove solid particles and fungi in the desalted water.

[0046] In some embodiments, the zero-steam consumption boiler feed water waste heat utilization system also includes: a compressor 60, connected in a pipeline from the second working fluid pipeline 52 of the working fluid evaporator 50 to the first working fluid pipeline 42 of the working fluid heat exchanger 40; a throttling expansion valve K, connected in a pipeline from the first working fluid pipeline 42 of the working fluid heat exchanger 40 to the second working fluid pipeline 52 of the working fluid evaporator 50.

[0047] Through the working medium circulation pipeline of the second working medium pipeline 52 of the working medium evaporator 50 → the compressor 60 → the first working medium pipeline 42 of the working medium heat exchanger 40 → the throttling expansion valve K → the second working medium pipeline 52 of the working medium evaporator 50, the working medium forms a circulating working medium for waste heat upgrading and utilization, and the waste heat upgrading and utilization process cycle is established by combining the heat source cooling and the deoxygenated water heating process without phase change heat characteristics. Firstly, the waste heat of the heat source is utilized to evaporate the working fluid step by step through the working fluid evaporator 50 for deep heat exchange, and then the working fluid is pressurized to a set pressure through the compressor 60, and then condensed step by step through the working fluid heat exchanger 40 for deep heat exchange with deoxygenated water, and then the cycle is completed through the throttling expansion valve K. This process is close to the ideal Lorentz cycle. Compared with the nearly isothermal process of condensation and evaporation of the conventional reverse Carnot cycle, the present invention utilizes the temperature glide advantage of the working fluid evaporation and condensation process to realize the variable temperature process of working fluid condensation and evaporation and heat exchange between deoxygenated water and the heat source, taking into account the actual situation that the temperature of the deoxygenated water and the heat source is changing. The cycle process of the present invention is more in line with the actual heat exchange process, so that the energy efficiency is effectively improved, and the cost and energy consumption can be reduced by more than 25%.

[0048] In some embodiments, the zero-steam consumption boiler feed water waste heat utilization system also includes: a booster pump 44, connected between the deoxygenated water pipeline 41 of the working medium heat exchanger 40 and the deoxygenated water output port 84, to help output qualified deoxygenated water as boiler water.

[0049] Figure 2 The medium flow diagram in the zero steam consumption boiler feed water waste heat utilization system in the embodiment of the present invention is shown below. Figure 1 and Figure 2 As shown, the process flow of using the zero steam consumption boiler feed water waste heat utilization system to produce qualified boiler water is explained.

[0050] The desalted water S-1 comes from upstream and first enters the filter 10 to deeply remove solid particles and fungi in the desalted water. The filtered desalted water S-2 enters the vacuum stripping deoxygenation unit 20 for deoxygenation; wherein, the desalted water S-3 entering the first-stage vacuum stripper 2A, the desalted water S-4 entering the second-stage vacuum stripper 2B, the desalted water S-5 entering the third-stage vacuum stripper 2C, and the desalted water S-6 entering the fourth-stage vacuum stripper 2D can come from the vacuum stripper of the previous stage and / or from the filtered desalted water S-2. In addition, the nitrogen S-8 entering the system is divided into part of nitrogen S-8A entering the first-stage vacuum stripper 2A (when the first-stage vacuum stripper 2A is working), part of nitrogen S-8B entering the second-stage vacuum stripper 2B (when the second-stage vacuum stripper 2B is working), part of nitrogen S-8C entering the third-stage vacuum stripper 2C (when the third-stage vacuum stripper 2C is working), and part of nitrogen S-8D entering the fourth-stage vacuum stripper 2D (when the fourth-stage vacuum stripper 2D is working). The vacuum stripper is provided with special polymer internal components, which only allow oxygen molecules dissolved in the desalted water to pass through, and the dissolved oxygen in the desalted water is continuously removed step by step under the negative pressure of the vacuum pump 92 and the action of nitrogen, so as to meet the deoxygenated water index requirements. The gases discharged from each vacuum stripper (including the gas S-9A discharged when the first-stage vacuum stripper 2A is working, the gas S-9B discharged when the second-stage vacuum stripper 2B is working, the gas S-9C discharged when the third-stage vacuum stripper 2C is working, and the gas S-9D discharged when the fourth-stage vacuum stripper 2D is working) are combined into gas S-10 and discharged into the atmosphere. The gas S-11 discharged into the atmosphere includes removed oxygen and nitrogen, etc. Among them, the inlet water temperature of the desalted water S-1 is 20℃ to 40℃, and the inlet water pressure is 0.3MPag to 1.0MPag, which can be adjusted according to production requirements.

[0051] After deoxygenation, the qualified deoxygenated water S-7 enters the multi-stream heat exchanger 30, and is deep-heated with the heat medium water S-19 after heat exchange in the first heat exchange section 3A, and with part of the initial heat medium water S-16 in the second heat exchange section 3B. The temperature of the deoxygenated water S-12 after heat exchange is heated to 70°C to 90°C, and then enters the working medium heat exchanger 40, and is deeply heat-exchanged with the high-temperature and high-pressure working medium S-24, so that the temperature of the deoxygenated water S-13 out of the working medium heat exchanger 40 is increased to 104°C to 156°C, meeting the needs of users at different temperature levels. After the action of the booster pump 44, the qualified deoxygenated water S-14 with a pressure of 0.2MPag to 10MPag is output. Among them, the temperature of the output qualified deoxygenated water S-14 can be adjusted within the range of 104°C to 156°C according to production requirements, and the pressure can be adjusted within the range of 0.2MPag to 10MPag according to production requirements.

[0052] The gas-liquid mixed working medium S-22 exchanges heat with part of the initial water supply heat medium S-17 through the working medium evaporator 50, and the gas phase working medium S-23 evaporates and heats up to the set temperature, and then enters the compressor 60, pressurizes the low-temperature and low-pressure gas phase working medium S-23 to the set pressure, forms the high-temperature and high-pressure gas phase working medium S-24, and then enters the working medium heat exchanger 40, condenses and cools down to the set temperature. The working medium S-25 discharged from the working medium heat exchanger 40 is depressurized to the set pressure through the throttling expansion valve K, becomes the gas-liquid mixed working medium S-22 and enters the working medium evaporator 50, forming a working medium near-Lorentz cycle. Among them, the working fluid is preferably a non-azeotropic ternary environmentally friendly working fluid, which includes the following components: 5% to 35% by mass of R1234ze(e) (Chinese name: trans-1,3,3,3-tetrafluoropropene, CAS number: 29118-24-9), 10% to 15% by mass of R245fa (Chinese name: pentafluoropropane, CAS number: 460-73-1), 50% to 85% by mass of R1233zd (Chinese name: trans-1-chloro-3,3,3-trifluoropropene, CAS number: 102687-65-0). This ensures that the GWP (Global Warming Potential) does not exceed 150. In actual application, it can be adjusted within the formula range according to the deoxygenated water temperature requirements.

[0053] As a heat source, the heat medium water S-15 is input in two ways. One way of heat medium water S-16 enters the second heat exchange section 3B of the multi-stream heat exchanger 30 and exchanges heat with the deoxygenated water S-7 after passing the deoxygenation test. The other way of heat medium water S-17 enters the working medium evaporator 50 and exchanges heat with the working medium S-23 in the gas phase. After the heat exchange, the heat medium water S-19 enters the first heat exchange section 3A of the multi-stream heat exchanger 30 and exchanges heat with the deoxygenated water S-7 after passing the deoxygenation test. Finally, the heat medium water S-18 discharged from the second heat exchange section 3B and the heat medium water S-20 discharged from the first heat exchange section 3A merge into the heat medium water return water S-21 and return to the upstream. Among them, the inlet water temperature of the heat medium water S-15 is 70℃ to 95℃, and the return water temperature is 50℃ to 80℃, which can be adjusted according to production requirements.

[0054] To facilitate understanding of the present invention, implementation examples are listed below. Those skilled in the art should understand that the implementation examples are only to help understand the present invention and should not be regarded as limiting the present invention.

[0055] Case 1 to Case 3 respectively give the energy consumption and cost of producing deoxygenated water at 104℃ to 156℃, and compare the energy consumption and cost of thermal deoxygenation technology and conventional heat pump waste heat upgrade. The energy price is 0.6 yuan / kW for electricity, 250 yuan / t for steam, 0.23 for energy discount coefficient, 66 for 0.4MPag steam, and 76 for 1.0MPag steam, as shown in the following table.

[0056]

[0057] After the present invention is implemented, zero steam consumption deoxidation can be achieved, and the energy consumption and cost of deoxidized water are lower. Deoxygenated water at 104°C to 156°C is produced. The power consumption per ton of deoxygenated water is 3.6KW / t to 21.2KW / t, which is equivalent to a deoxygenated water cost of 2.2 yuan / t to 12.7 yuan / t and an energy consumption of 0.8kgEO / t to 4.9kgEO / t, respectively. It is significantly better than thermal deoxygenation technology (deoxygenated water cost and energy consumption are 13.4 yuan / t to 43.1 yuan / t and 3.5kgEO / t to 13.1kgEO / t, respectively), and the deoxygenated water cost is reduced by 70.4% to 83.7%, and the energy consumption is reduced by 62.7% to 76.4%; it is also better than conventional heat pump waste heat upgrading technology (deoxygenated water cost and energy consumption are 3.3 yuan / t to 18.5 yuan / t and 1.3kgEO / t to 7.1kgEO / t, respectively), and the deoxygenated water cost is reduced by 27.5% to 34.8%, and the energy consumption is reduced by 27.5% to 34.8%. The present invention realizes zero steam consumption deoxygenation and produces boiler feed water with qualified dissolved oxygen index and temperature. The deoxygenation cost and energy consumption are lower than those of traditional processes, and the energy-saving benefits are significant.

[0058] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A zero steam consumption boiler feed water waste heat utilization system, characterized in that: include: A vacuum stripping deoxygenation unit connected to a desalted water inlet, wherein the vacuum stripping deoxygenation unit comprises a plurality of vacuum strippers connected in series, wherein the series connection nodes of adjacent vacuum strippers are also connected to the desalted water inlet via a total water inlet pipeline; A multi-stream heat exchanger, comprising a first heat exchange section and a second heat exchange section respectively including a deoxygenated water pipeline and a heat source pipeline, wherein the deoxygenated water pipelines of the first heat exchange section and the second heat exchange section are connected, and the heat source pipelines are independent; A working medium heat exchanger, comprising a deoxygenated water pipeline and a first working medium pipeline, wherein the water outlet of the vacuum air stripping deoxygenation unit is connected to the deoxygenated water output port via the deoxygenated water pipeline of the first heat exchange section, the deoxygenated water pipeline of the second heat exchange section and the deoxygenated water pipeline in sequence; The working fluid evaporator comprises a heat source pipeline and a second working fluid pipeline, wherein one end of the heat source pipeline is connected to a heat source water inlet and the other end is connected to a heat source water return port via the heat source pipeline of the first heat exchange section, the heat source water inlet is also connected to the heat source water return port via the heat source pipeline of the second heat exchange section, and the second working fluid pipeline and the first working fluid pipeline form a working fluid circulation pipeline.

2. The zero steam consumption boiler feed water waste heat utilization system according to claim 1, characterized in that: Each of the vacuum strippers has a water inlet and a water outlet, wherein the water outlet of the preceding vacuum stripper is connected in series with the water inlet of the succeeding vacuum stripper, and the series node between the water inlet of the first vacuum stripper and the water outlet of the preceding vacuum stripper and the water inlet of the succeeding vacuum stripper is connected to the desalted water inlet via the total water inlet pipeline.

3. The zero steam consumption boiler feed water waste heat utilization system according to claim 1, characterized in that: Each of the vacuum strippers also has an air inlet and an air outlet. The air inlet of each of the vacuum strippers is connected to an inert gas inlet, and the air outlet of each of the vacuum strippers is connected to a vacuum pump.

4. The zero steam consumption boiler feed water waste heat utilization system according to claim 3, characterized in that: The inert gas is nitrogen, and the purity of the nitrogen is greater than or equal to 99.9%.

5. The zero steam consumption boiler feed water waste heat utilization system according to claim 1, characterized in that: Also includes: A filter is connected between the desalted water inlet and the vacuum air stripping deoxygenation unit.

6. The zero steam consumption boiler feed water waste heat utilization system according to claim 1, characterized in that: Also includes: A compressor connected to a pipeline from the second working fluid pipeline to the first working fluid pipeline; A throttling expansion valve is connected to a pipeline from the first working fluid pipeline to the second working fluid pipeline.

7. The zero steam consumption boiler feed water waste heat utilization system according to claim 1, characterized in that: Also includes: A booster pump is connected between the deoxygenated water pipeline and the deoxygenated water output port.

8. The zero steam consumption boiler feed water waste heat utilization system according to claim 1, characterized in that: The working fluid circulating in the working fluid circulation pipeline is a non-azeotropic working fluid, and the non-azeotropic working fluid comprises the following components: 5% to 35% by mass of trans-1,3,3,3-tetrafluoropropene, 10% to 15% by mass of pentafluoropropane, and 50% to 85% by mass of trans-1-chloro-3,3,3-trifluoropropene.

9. The zero steam consumption boiler feed water waste heat utilization system according to claim 1, characterized in that: The temperature of the desalted water entering the desalted water inlet is 20°C to 40°C and the pressure is 0.3MPag to 1.0MPag; The temperature of the heat medium water entering the heat source water inlet is 70°C to 95°C, and the temperature of the heat medium water flowing out of the heat source water return port is 50°C to 80°C.

10. The zero steam consumption boiler feed water waste heat utilization system according to any one of claims 1 to 9, characterized in that: The temperature of the deoxygenated water flowing out of the multi-stream heat exchanger is 70°C to 90°C, and the temperature of the deoxygenated water flowing out of the deoxygenated water output port is 104°C to 156°C and the pressure is 0.2MPag to 10MPag.

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