Dead steam waste heat recovery system and method

Abstract

The invention relates to the technical field of waste steam waste heat recovery, and provides a waste steam waste heat recovery system and method.The waste steam waste heat recovery system comprises a gas source, a first heat exchange device and a steam-liquid separator, the gas source is used for providing waste steam, and a heat flow side inlet of the first heat exchange device is connected with an outlet of the gas source through a pipeline; the first heat exchange device is used for exchanging heat between the recycled dead steam and liquid on the cold flow side of the first heat exchange device, and an outlet in the hot flow side of the first heat exchange device is used for discharging condensate formed by heat exchange between the dead steam and the liquid; an inlet of the vapor-liquid separator is connected with an outlet of the cold flow side of the first heat exchange device through a pipeline, and the vapor-liquid separator is used for performing vapor-liquid separation on a vapor-liquid mixture formed by liquid on the cold flow side of the first heat exchange device through heat exchange; a liquid outlet of the vapor-liquid separator is connected with an inlet of the cold flow side of the first heat exchange device and used for sending liquid obtained through vapor-liquid separation back to the cold flow side of the first heat exchange device, a vapor exhaust port of the vapor-liquid separator is used for exhausting gas obtained through vapor-liquid separation, and the energy utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of waste steam waste heat recovery, and particularly to a waste steam waste heat recovery system and method. Background Art

[0002] There are a large number of low-temperature waste steam waste heat resources in many industrial fields. For example, a large amount of low-temperature waste steam is generated during the production processes of chemical, energy, power, and metallurgical industries such as chemical reaction devices, power plant steam turbines, and steel slag water. These waste steam resources are often difficult to utilize due to their low energy grade. Generally, the heat of this part of waste steam is directly discharged to the atmosphere by means of circulating water cooling or air cooling, resulting in waste of resources.

[0003] Therefore, how to realize the recovery and utilization of waste steam waste heat has become an important energy-saving research direction. Summary of the Invention

[0004] The present invention provides a waste steam waste heat recovery system and method to solve the problem of waste of waste steam waste heat in the prior art, improve energy utilization efficiency, and achieve the purpose of energy conservation and consumption reduction.

[0005] The present invention provides a waste steam waste heat recovery system, including:

[0006] A gas source for providing waste steam;

[0007] A first heat exchange device, the inlet of the heat flow side of the first heat exchange device is connected to the outlet of the gas source through a pipeline, and is used for exchanging heat between the recovered waste steam and the liquid on the cold flow side of the first heat exchange device. The outlet of the heat flow side of the first heat exchange device is used for discharging the condensate formed by the heat exchange between the waste steam and the liquid.

[0008] A gas-liquid separator, the inlet of the gas-liquid separator is connected to the outlet of the cold flow side of the first heat exchange device through a pipeline, and the gas-liquid separator is used for separating the gas-liquid mixture formed by the liquid on the cold flow side of the first heat exchange device after heat exchange.

[0009] The liquid discharge port of the gas-liquid separator is connected to the inlet of the cold flow side of the first heat exchange device, and is used for sending the liquid obtained after gas-liquid separation back to the cold flow side of the first heat exchange device. The steam discharge port of the gas-liquid separator is used for discharging the gas obtained after gas-liquid separation.

[0010] According to the waste steam waste heat recovery system provided by the present invention, it further includes a second heat exchange device. The inlet of the cold flow side of the second heat exchange device is connected to an external water source through a makeup water pipe, and is used for supplying makeup water to the cold flow side of the second heat exchange device.

[0011] The inlet of the heat flow side of the second heat exchange device is connected to the outlet of the heat flow side of the first heat exchange device through a pipeline, and is used for heat-exchanging the recovered condensate with residual heat with the makeup water on the cold flow side of the second heat exchange device. The outlet of the heat flow side of the second heat exchange device is used for discharging the heat-exchanged condensate.

[0012] The outlet of the cold flow side of the second heat exchange device is connected to the inlet of the cold flow side of the first heat exchange device through a pipeline, and is used for supplying the preheated makeup water to the first heat exchange device.

[0013] According to the waste steam waste heat recovery system provided by the present invention, it further includes a supercharger. The supercharger is arranged between the gas source and the first heat exchange device. The inlet of the supercharger is connected to the outlet of the gas source through a pipeline, and is used for compressing the waste steam to increase its enthalpy value. The outlet of the supercharger is connected to the inlet of the heat flow side of the first heat exchange device through a pipeline.

[0014] According to the waste steam waste heat recovery system provided by the present invention, a dust removal device is further arranged between the gas source and the supercharger. The inlet of the dust removal device is connected to the outlet of the gas source through a pipeline, and is used for dust removal and purification of the waste steam. The outlet of the dust removal device is connected to the inlet of the supercharger through a pipeline.

[0015] According to the waste steam waste heat recovery system provided by the present invention, it further includes a boosting mechanism. The inlet of the boosting mechanism is connected to the steam exhaust port of the steam-liquid separator, and is used for compressing the gas obtained by steam-liquid separation to a target pressure and a target temperature.

[0016] According to the waste steam waste heat recovery system provided by the present invention, the boosting mechanism includes a steam compressor, or includes at least two steam compressors connected in series or in parallel.

[0017] According to the waste steam waste heat recovery system provided by the present invention, it further includes a scrubbing heat exchange device. The inlet of the scrubbing heat exchange device is connected to the outlet of the dust removal device through a pipeline. A fan is connected to the outlet of the scrubbing heat exchange device, and is used for discharging the treated waste steam.

[0018] The present invention also provides a waste steam waste heat recovery method, including:

[0019] Introducing waste steam into the heat flow side of the first heat exchange device;

[0020] The waste steam exchanges heat with the liquid on the cold flow side of the first heat exchange device and is discharged as condensate;

[0021] The liquid on the cold flow side of the first heat exchange device enters the steam-liquid separator after absorbing heat;

[0022] The vapor-liquid separator returns the liquid obtained through vapor-liquid separation to the cold fluid side of the first heat exchanger and discharges the gas obtained through vapor-liquid separation.

[0023] According to the waste steam waste heat recovery method provided by the present invention, the waste steam exchanges heat with the liquid on the cold fluid side of the first heat exchanger and becomes condensate and is discharged. It further includes:

[0024] Discharging the condensate into the hot fluid side of the second heat exchanger;

[0025] The condensate exchanges heat with the makeup water on the cold fluid side of the second heat exchanger and then is discharged;

[0026] The makeup water on the cold fluid side of the second heat exchanger absorbs heat and then enters the cold fluid side of the first heat exchanger for exchanging heat with the waste steam on the hot fluid side of the first heat exchanger.

[0027] According to the waste steam waste heat recovery method provided by the present invention, the vapor-liquid separator discharges the gas obtained through vapor-liquid separation, including:

[0028] The vapor-liquid separator discharges the gas obtained through vapor-liquid separation into a pressurizing mechanism, and the gas is compressed to a target pressure and a target temperature by the pressurizing mechanism.

[0029] For the waste steam waste heat recovery system and method provided by the present invention, during operation, the waste steam is sent into the first heat exchanger, and it exchanges heat with the liquid on the cold fluid side of the first heat exchanger on the hot fluid side of the first heat exchanger. After heat exchange, the waste steam releases heat and becomes condensate and then is discharged through the outlet on the hot fluid side of the first heat exchanger; while the liquid on the cold fluid side of the first heat exchanger absorbs heat and boils and evaporates into a low-pressure vapor-liquid mixture, and then enters the vapor-liquid separator for separation. The separated liquid returns to the cold fluid side of the first heat exchanger through the liquid discharge port of the vapor-liquid separator to continue exchanging heat with the waste steam, and the separated steam is discharged through the steam discharge port of the vapor-liquid separator and can be processed by related equipment to meet the requirements of the production process or other energy-consuming processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is a schematic structural diagram of the waste steam waste heat recovery system provided by an embodiment of the present invention;

[0032] Figure 2 It is a schematic structural diagram of the waste steam waste heat recovery system provided by another embodiment of the present invention;

[0033] Figure 3 It is a schematic structural diagram of the titanium dioxide waste steam heat recovery system provided by the embodiment of the present invention.

[0034] Reference numerals:

[0035] 1. Gas source; 2. First heat exchange device; 3. Gas-liquid separator; 4. Booster; 5. Second heat exchange device; 6. Dust removal device; 7. First steam compressor; 8. Second steam compressor; 9. Scrubbing heat exchange device; 10. Fan; 11. Post-treatment system. Specific embodiments

[0036] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] The following Figures 1 to 3 describes a waste steam heat recovery system and method provided in the embodiments of the present invention.

[0038] A waste steam heat recovery system provided in this embodiment includes: a gas source 1, a first heat exchange device 2, and a gas-liquid separator 3.

[0039] Among them, the gas source 1 is used to provide waste steam. The inlet of the hot fluid side of the first heat exchange device 2 is connected to the outlet of the gas source 1 through a pipeline, and is used to exchange heat between the recovered waste steam and the liquid on the cold fluid side of the first heat exchange device 2. The outlet of the hot fluid side of the first heat exchange device 2 is used to discharge the condensate formed by the heat exchange between the waste steam and the liquid. The inlet of the gas-liquid separator 3 is connected to the outlet of the cold fluid side of the first heat exchange device 2 through a pipeline. The gas-liquid separator 3 is used to separate the gas-liquid mixture formed by the liquid on the cold fluid side of the first heat exchange device 2 after heat exchange into gas and liquid.

[0040] The liquid discharge port of the gas-liquid separator 3 is connected to the inlet of the cold fluid side of the first heat exchange device 2, and is used to send the liquid obtained after gas-liquid separation back to the cold fluid side of the first heat exchange device 2. The steam discharge port of the gas-liquid separator 3 is used to discharge the gas obtained after gas-liquid separation.

[0041] As can be seen from the above solution, a waste steam waste heat recovery system provided by the present invention, when operating, sends waste steam into the first heat exchange device 2, and exchanges heat between the waste steam on the heat flow side of the first heat exchange device 2 and the liquid on the cold flow side of the first heat exchange device 2. After heat exchange, the waste steam releases heat and becomes condensate, which is then discharged through the outlet on the heat flow side of the first heat exchange device 2; while the liquid on the cold flow side of the first heat exchange device 2 absorbs heat and boils and evaporates into a low-pressure vapor-liquid mixture, and then enters the vapor-liquid separator 3 to be separated. The separated liquid returns to the cold flow side of the first heat exchange device 2 through the liquid discharge port of the vapor-liquid separator 3 to continue heat exchange with the waste steam, and the separated steam is discharged through the steam discharge port of the vapor-liquid separator 3, and can meet the production process or other energy-consuming process requirements after further compression to increase the enthalpy.

[0042] In this way, the entire process realizes the recovery and reuse of waste steam waste heat, helps to improve energy utilization efficiency, reduce process energy consumption, reduce the consumption of external energy, and can be widely applied to the industrial waste heat recovery process.

[0043] In this embodiment, a booster 4 is further included. The booster 4 can be one of a centrifugal compressor, a screw compressor or a high-pressure blower; the booster 4 is arranged between the gas source 1 and the first heat exchange device 2. The inlet of the booster 4 is connected to the outlet of the gas source 1 through a pipeline, and is used to compress the waste steam to increase its enthalpy value. The outlet of the booster 4 is connected to the inlet of the heat flow side of the first heat exchange device 2 through a pipeline.

[0044] With such a setting, by setting the booster 4, the pressure and temperature of the waste steam can be increased, the enthalpy value of the waste steam can be increased, and the flow rate and flow velocity of the waste steam in the system can be increased, thereby improving the utilization rate of waste steam heat energy.

[0045] In this embodiment, a second heat exchange device 5 is further included. The inlet of the cold flow side of the second heat exchange device 5 is connected to an external water source through a makeup water pipe, and is used to supply makeup water to the cold flow side of the second heat exchange device 5; the inlet of the heat flow side of the second heat exchange device 5 is connected to the outlet of the heat flow side of the first heat exchange device 2 through a pipeline, and is used to exchange heat between the recovered condensate with waste heat and the makeup water on the cold flow side of the second heat exchange device 5. The outlet of the heat flow side of the second heat exchange device 5 is used to discharge the heat-exchanged condensate; the outlet of the cold flow side of the second heat exchange device 5 is connected to the inlet of the cold flow side of the first heat exchange device 2 through a pipeline, and is used to supply the preheated makeup water to the first heat exchange device 2.

[0046] With such a setting, by adding a second heat exchanger 5, the secondary utilization of the waste heat in the condensate obtained after the waste steam is heat-exchanged is realized. Clear water is provided to the second heat exchanger 5 from an external water source. The condensate on the heat flow side of the second heat exchanger 5 is heat-exchanged with the makeup water on the cold flow side to further reduce the temperature of the condensate about to be discharged, so that the waste heat of the waste steam is recovered to the greatest extent. After absorbing heat, the makeup water is sent back to the cold flow side of the first heat exchanger 2 and heat-exchanged with the waste steam on the heat flow side of the first heat exchanger 2 together with the liquid sent back by the steam-liquid separator 3. After being heated and evaporated, it enters the steam-liquid separator 3, and the above process is continued.

[0047] Optionally, the first heat exchanger 2 and the second heat exchanger 5 can be one of a plate heat exchanger or a shell-and-tube heat exchanger.

[0048] In this embodiment, a dust removal device 6 is further provided between the gas source 1 and the supercharger 4. The dust removal device 6 can be a bag filter. The inlet of the dust removal device 6 is connected to the outlet of the gas source 1 through a pipeline for dust removal and purification of the waste steam, and the outlet of the dust removal device 6 is connected to the inlet of the supercharger 4 through a pipeline.

[0049] With such a setting, by providing a dust removal device 6 between the gas source 1 and the supercharger 4, the waste steam can be purified, the dust entrained in the waste steam can be removed, the purity of the gas can be improved, the maintenance of the equipment can be reduced, and the service life of the equipment can be extended.

[0050] Furthermore, a supercharging mechanism is further included. The inlet of the supercharging mechanism is connected to the exhaust port of the steam-liquid separator 3 for compressing the gas obtained after steam-liquid separation to a target pressure and a target temperature.

[0051] In this embodiment, the supercharging mechanism includes a steam compressor, or includes at least two steam compressors connected in series or in parallel.

[0052] In a specific embodiment, the supercharging mechanism includes a first steam compressor 7 and a second steam compressor 8 connected in series. The inlet of the first steam compressor 7 is connected to the exhaust port of the steam-liquid separator 3, and the inlet of the second steam compressor 8 is connected to the outlet of the first steam compressor 7. Among them, the first steam compressor 7 and the second steam compressor 8 can adopt a centrifugal compressor, a screw compressor, a Roots compressor or a single-stage high-pressure ratio steam compressor.

[0053] With such a setting, by compressing the gas discharged from the steam-liquid separator 3, such as saturated steam, by the supercharging mechanism to increase the enthalpy value, the gas is gradually compressed in the supercharging mechanism to obtain a target steam with high temperature and high pressure, which can be used for other process processes in production or for the process itself to recycle.

[0054] In some embodiments, it further includes a scrubbing heat exchange device 9. The inlet of the scrubbing heat exchange device 9 is connected to the outlet of the dust removal device 6 through a pipeline, and a fan 10 is connected to the outlet of the scrubbing heat exchange device 9 for discharging the treated exhausted steam. As Figure 2 shown, the scrubbing heat exchange device 9 can be a scrubbing tower. The exhausted steam is simply heat-exchanged through the provided spray heat exchanger. The recovered heat energy of the exhausted steam can be used for heating supply, process washing, etc., or when it is necessary to switch the exhausted steam discharge path during the overhaul of the supercharger 4, the heat exchange device, the vapor-liquid separator 3, the boosting mechanism or for other reasons, the exhausted steam can be temporarily discharged to the suction heat exchange device.

[0055] Optionally, valves such as solenoid valves are respectively arranged on the pipeline connecting the scrubbing heat exchange device 9 and the dust removal device 6 and on the pipeline connecting the supercharger 4 and the dust removal device 6 for realizing the switching of the two process routes.

[0056] The embodiment of the present invention also provides a method for recovering waste heat of exhausted steam, including:

[0057] Step S1: Purify, dust-remove and boost the exhausted steam and then introduce it into the hot fluid side of the first heat exchange device 2;

[0058] Step S2: The exhausted steam exchanges heat with the liquid on the cold fluid side of the first heat exchange device 2 and then is discharged as condensate;

[0059] Step S3: The liquid on the cold fluid side of the first heat exchange device 2 absorbs heat and then enters the vapor-liquid separator 3;

[0060] Step S4: The vapor-liquid separator 3 sends the liquid obtained through vapor-liquid separation back to the cold fluid side of the first heat exchange device 2 and discharges the gas obtained through vapor-liquid separation.

[0061] Through the above scheme, it can be seen that the present invention sends the exhausted steam into the hot fluid side of the first heat exchange device 2 to exchange heat with the liquid on the cold fluid side of the first heat exchange device 2. The liquid on the cold fluid side of the first heat exchange device 2 absorbs heat and then boils and evaporates into a low-pressure vapor-liquid mixture, and then enters the vapor-liquid separator 3 to be separated. The separated liquid returns to the cold fluid side of the first heat exchange device 2 through the liquid discharge port of the vapor-liquid separator 3 to continue to exchange heat with the exhausted steam, and the separated steam is discharged through the steam discharge port of the vapor-liquid separator 3. It can be further boosted through relevant equipment to meet the production process or other energy-consuming process requirements. This process realizes the recovery and reuse of the waste heat of the exhausted steam, helps to improve the energy utilization rate and reduce the process energy consumption.

[0062] Further, step S2 further includes:

[0063] Discharging the condensate into the hot fluid side of the second heat exchange device 5;

[0064] The condensate exchanges heat with the makeup water on the cold fluid side of the second heat exchange device 5 and then is discharged;

[0065] The make-up water on the cold fluid side of the second heat exchanger 5 enters the cold fluid side of the first heat exchanger 2 after absorbing heat, and is used to exchange heat with the exhaust steam on the hot fluid side of the first heat exchanger 2.

[0066] With such an arrangement, the condensate on the hot fluid side of the second heat exchanger 5 exchanges heat with the make-up water on the cold fluid side, realizing the secondary utilization of the waste heat in the condensate obtained after the exhaust steam heat exchange, further reducing the temperature of the condensate to be discharged, so as to maximize the recovery of the waste heat of the exhaust steam. After absorbing heat, the make-up water is sent back to the cold fluid side of the first heat exchanger 2, and exchanges heat with the exhaust steam on the hot fluid side of the first heat exchanger 2 together with the liquid sent back by the steam-liquid separator 3.

[0067] In this embodiment, discharging the gas obtained after gas-liquid separation in step S4 includes: the steam-liquid separator 3 discharges the gas obtained after gas-liquid separation into the pressurizing mechanism, and the gas is compressed to the target pressure and target temperature by the pressurizing mechanism.

[0068] In some embodiments, this waste heat recovery system can be used for the waste heat recovery of the exhaust steam generated by the jet mill in the titanium dioxide production process. Of course, it can also be used for waste heat recovery in other fields. Taking the titanium dioxide production process as an example, this waste heat recovery system will be described below.

[0069] Since titanium dioxide has very high requirements for particle size, particle size distribution and purity, general mechanical crushing equipment is difficult to meet these requirements. Currently, a medium-high pressure steam jet mill (i.e., steam jet mill) is selected as the final crushing equipment for titanium dioxide; the steam jet mill is driven by medium-high pressure steam, and the outlet exhaust steam temperature is about 100°C - 130°C. Due to the presence of dust and non-condensable gases, it is generally completely discharged after being filtered by a bag filter, or simple heat energy recovery is carried out through a spray heat exchanger, which results in a considerable amount of energy waste.

[0070] Such as Figure 3As shown in the figure, the pre-treated titanium dioxide enters the jet mill. Medium-pressure steam is introduced into the jet mill. The titanium dioxide ground by the jet mill enters the post-treatment system 11 for further processing. The exhausted steam generated during the grinding of titanium dioxide enters the dust removal device 6, such as a bag filter. After being treated, the exhausted steam enters the supercharger 4. After being compressed and doing work to increase the temperature and pressure of the exhausted steam, it is introduced into the hot fluid side of the first heat exchanger 2. After exchanging heat with the liquid on the cold fluid side of the first heat exchanger 2, it becomes condensate and enters the hot fluid side of the second heat exchanger 5, and then is discharged. The liquid on the cold fluid side of the first heat exchanger 2 absorbs heat and evaporates and boils to become a low-pressure vapor-liquid mixture, which enters the vapor-liquid separator 3. The vapor-liquid separator 3 returns the treated liquid to the cold fluid side of the first heat exchanger 2 to provide makeup water (clean water) to the cold fluid side of the second heat exchanger 5. After the makeup water exchanges heat with the condensate on the hot fluid side of the second heat exchanger 5 and absorbs heat, it enters the cold fluid side of the first heat exchanger 2 and exchanges heat with the exhausted steam on the hot fluid side of the first heat exchanger 2 together with the liquid discharged from the vapor-liquid separator 3 to continue to participate in evaporation. The gas obtained after being treated by the vapor-liquid separator 3, such as low-pressure pure saturated steam, is sent to the first steam compressor 7 and the second steam compressor 8. After being compressed step by step to increase the pressure, pure steam meeting the target pressure is obtained for use in the air pulverization process or other production processes.

[0071] In the exhausted steam waste heat recovery system during the above-mentioned titanium dioxide production process, the design is reasonable and the structure is simple. In the process, the exhausted steam after dust removal and purification is used to increase the enthalpy value of the exhausted steam through mechanical compression, and through further heat exchange with clean water, the effective recovery of the exhausted steam waste heat is realized; the clean water boils and evaporates after being heated to generate low-pressure steam, and pure steam meeting the pressure requirements for use is produced through the pressurizing mechanism and recycled for use in the titanium dioxide production process or other energy-consuming processes. The whole process realizes the recovery and reuse of the exhausted steam waste heat, which helps to improve the energy utilization rate and reduce the process energy consumption; this system can be used for the waste heat recovery of the exhausted steam in the titanium dioxide air pulverization production process, and can also be used for the waste heat recovery of air pulverization in other industrial fields.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waste steam waste heat recovery system, characterized in that, Comprising: A gas source (1) for providing waste steam; A first heat exchange device (2), the inlet of the heat flow side of the first heat exchange device (2) is connected to the outlet of the gas source (1) through a pipeline, for exchanging heat between the recovered waste steam and the liquid on the cold flow side of the first heat exchange device (2), and the outlet of the heat flow side of the first heat exchange device (2) is used to discharge the condensate formed by the heat exchange between the waste steam and the liquid; A steam-liquid separator (3), the inlet of the steam-liquid separator (3) is connected to the outlet of the cold flow side of the first heat exchange device (2) through a pipeline, and the steam-liquid separator (3) is used to separate the steam-liquid mixture formed by the heat exchange of the liquid on the cold flow side of the first heat exchange device (2); The liquid discharge port of the steam-liquid separator (3) is connected to the inlet of the cold flow side of the first heat exchange device (2), for sending the liquid obtained by steam-liquid separation back to the cold flow side of the first heat exchange device (2), and the steam discharge port of the steam-liquid separator (3) is used to discharge the gas obtained by steam-liquid separation.

2. The waste steam heat recovery system according to claim 1, characterized in that It further comprises a second heat exchange device (5), the inlet of the cold flow side of the second heat exchange device (5) is connected to an external water source through a make-up water pipe, for providing make-up water to the cold flow side of the second heat exchange device (5); The inlet of the heat flow side of the second heat exchange device (5) is connected to the outlet of the heat flow side of the first heat exchange device (2) through a pipeline, for exchanging heat between the recovered condensate with residual heat and the make-up water on the cold flow side of the second heat exchange device (5), and the outlet of the heat flow side of the second heat exchange device (5) is used to discharge the heat-exchanged condensate; The outlet of the cold flow side of the second heat exchange device (5) is connected to the inlet of the cold flow side of the first heat exchange device (2) through a pipeline, for providing the preheated make-up water to the first heat exchange device (2).

3. The waste steam heat recovery system according to claim 1, wherein It further comprises a booster (4), the booster (4) is arranged between the gas source (1) and the first heat exchange device (2), the inlet of the booster (4) is connected to the outlet of the gas source (1) through a pipeline, for compressing the waste steam to increase its enthalpy value, and the outlet of the booster (4) is connected to the inlet of the heat flow side of the first heat exchange device (2) through a pipeline.

4. The waste steam heat recovery system according to claim 3, wherein A dust removal device (6) is further arranged between the gas source (1) and the booster (4), the inlet of the dust removal device (6) is connected to the outlet of the gas source (1) through a pipeline, for dust removal and purification of the waste steam, and the outlet of the dust removal device (6) is connected to the inlet of the booster (4) through a pipeline.

5. The waste steam heat recovery system according to claim 1, wherein It further comprises a boosting mechanism, the inlet of the boosting mechanism is connected to the steam discharge port of the steam-liquid separator (3), for compressing the gas obtained by steam-liquid separation to a target pressure and a target temperature.

6. The waste steam heat recovery system according to claim 5, characterized in that, The boosting mechanism comprises a steam compressor, or comprises at least two steam compressors connected in series or in parallel.

7. The waste steam waste heat recovery system according to claim 4, characterized in that, It further comprises a scrubbing heat exchange device (9), the inlet of the scrubbing heat exchange device (9) is connected to the outlet of the dust removal device (6) through a pipeline, and the outlet of the scrubbing heat exchange device (9) is connected to a blower (10) for discharging the treated waste steam.

8. A method for recovering waste heat from exhaust steam, characterized in that, Comprising: Feed the exhaust steam into the hot fluid side of the first heat exchanger; The exhaust steam exchanges heat with the liquid on the cold fluid side of the first heat exchanger and is discharged as condensate; The liquid on the cold fluid side of the first heat exchanger enters the vapor-liquid separator after absorbing heat; The vapor-liquid separator sends the liquid obtained through vapor-liquid separation back to the cold fluid side of the first heat exchanger and discharges the gas obtained through vapor-liquid separation.

9. The waste steam heat recovery method according to claim 8, characterized in that, The exhaust steam exchanges heat with the liquid on the cold fluid side of the first heat exchanger and is discharged as condensate, further including: Discharge the condensate into the hot fluid side of the second heat exchanger; The condensate is discharged after exchanging heat with the makeup water on the cold fluid side of the second heat exchanger; The makeup water on the cold fluid side of the second heat exchanger enters the cold fluid side of the first heat exchanger after absorbing heat and is used to exchange heat with the exhaust steam on the hot fluid side of the first heat exchanger.

10. The waste steam waste heat recovery method according to claim 8, characterized in that, The vapor-liquid separator discharges the gas obtained through vapor-liquid separation, including: The vapor-liquid separator discharges the gas obtained through vapor-liquid separation into the pressurizing mechanism, and the gas is compressed to the target pressure and target temperature by the pressurizing mechanism.

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