Evaporator dead steam utilization system

Abstract

The invention belongs to the technical field of industrial waste heat recovery and utilization, and provides an evaporator dead steam utilization system which comprises a condenser, an inlet of a hot side channel of the condenser is connected with an evaporator dead steam output unit, an outlet of the hot side channel is connected with a vacuumizing unit and a condensate water recovery unit, and an inlet of a cold side channel of the condenser is connected with a heating water return unit. The outlet is connected with a heating water supply unit; the vacuumizing unit comprises at least two vacuumizing branches which are connected in parallel, each vacuumizing branch is provided with at least one vacuum pump, and the vacuumizing efficiencies of different vacuum pumps are different; a first temperature sensor is connected between the inlet of the hot side channel and the evaporator dead steam output unit; a second temperature sensor is arranged on the heating water supply unit, and a third temperature sensor is arranged on the heating water return unit; the temperature sensors and the vacuum pumps are electrically connected with the controller. The system has the advantages of being high in heat exchange efficiency, high in structural reliability, economical, feasible, high in automation degree and capable of finely adjusting the heat supply amount.

Description

Technical Field

[0001] This invention belongs to the field of industrial waste heat recovery and utilization technology, and in particular relates to an evaporator exhaust steam utilization system. Background Technology

[0002] Evaporators play a crucial role in numerous industrial production processes and certain energy utilization systems. They use a heating medium to evaporate liquid substances, thereby achieving separation, concentration, or purification. However, during evaporator operation, a significant amount of waste heat is often directly released into the environment, resulting not only in serious energy waste but also potential adverse effects such as thermal pollution. For example, in the evaporation process of the alumina production industry, after high-temperature steam is used as a heating source to evaporate the solution, the large amount of latent heat released by the steam condensation, as well as the heat dissipated by the evaporator itself, is not fully utilized but is instead discharged with cooling water or waste gas.

[0003] With rising energy costs and increasing global emphasis on energy conservation and emission reduction, improving energy efficiency has become a significant challenge for various industries. Currently, some technologies attempt to recover waste heat from evaporator exhaust steam, such as introducing it into heat pump units for heating or process preheating. However, these solutions generally suffer from the following shortcomings: 1) The system is complex, requiring additional equipment such as heat pumps and external heat sources, resulting in high initial investment and large footprint; 2) Multiple energy conversion stages lead to additional energy losses, and overall energy efficiency needs improvement; 3) Low automation and poor stability and controllability of exhaust steam heat output make it difficult to match the dynamically fluctuating demands of end users. These shortcomings are particularly pronounced in scenarios where exhaust steam waste heat is used for centralized heating in residential areas. Since heating loads need to be adjusted in real-time and precisely based on outdoor temperatures, and the amount of exhaust steam generated is often strongly correlated with the stability of upstream production processes, existing exhaust steam utilization systems suffer from insufficient heat regulation capacity, frequently resulting in over- or under-heating, affecting heating comfort.

[0004] Therefore, there is an urgent need to design an evaporator exhaust steam utilization system with high heat exchange efficiency, high structural reliability, economic feasibility, high degree of automation, and the ability to finely regulate the heat supply, in order to solve the above-mentioned problems existing in the current technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an evaporator exhaust steam utilization system. This system has high heat exchange efficiency, high structural reliability, economic feasibility, high degree of automation, and the ability to finely regulate the heat supply.

[0006] This application provides an evaporator exhaust steam utilization system, including a condenser. The condenser has a cold side channel and a hot side channel. The inlet of the hot side channel is connected to an evaporator exhaust steam output unit, and the outlet of the hot side channel is connected to a vacuum unit and a condensate recovery unit, respectively. The inlet of the cold side channel is connected to a heating return water unit, and the outlet of the cold side channel is connected to a heating supply water unit. Both the heating return water unit and the heating supply water unit are connected to a heating network.

[0007] The vacuum unit includes at least two parallel vacuum branches, each of which is equipped with at least one vacuum pump, and the vacuum pumps have different vacuum efficiencies; a first temperature sensor is connected between the inlet of the hot side channel and the evaporator exhaust steam output unit; a second temperature sensor is provided on the heating water supply unit, and a third temperature sensor is provided on the heating return water unit; the first temperature sensor, the second temperature sensor, the third temperature sensor, and each of the vacuum pumps are electrically connected to the controller.

[0008] As a further description of the above technical solution, the evaporator exhaust steam output unit includes at least two parallel exhaust steam output branches, each of which is equipped with an electric vacuum regulating valve, which is electrically connected to the controller.

[0009] As a further description of the above technical solution, the evaporator exhaust steam output unit includes a parallel exhaust steam output branch for the last-effect evaporator and an exhaust steam output branch for the second-last-effect evaporator.

[0010] As a further description of the above technical solution, the inlet of the hot-side channel is also connected to a new steam output unit.

[0011] As a further description of the above technical solution, a dust collector is also connected between the inlet of the hot side channel and the evaporator exhaust steam output unit.

[0012] As a further description of the above technical solution, a first main valve is also provided on the vacuum branch, a vacuum sensor is connected between the first main valve and the vacuum pump, a first control valve is connected between the vacuum sensor and the vacuum pump, and the vacuum sensor and the first control valve are both electrically connected to the controller.

[0013] As a further description of the above technical solution, the condensate recovery unit includes a hot well and two parallel condensate recovery branches. Each of the condensate recovery branches is provided with a condensate pump and a recovery water tank connected in sequence. The outlet of the hot side channel is connected to the hot well, and the outlet of the hot well is connected to the inlet of the condensate pump.

[0014] As a further description of the above technical solution, a liquid level sensor is installed on the hot well, and a solenoid valve is connected between the condensate pump and the recovery water tank. The liquid level sensor, the condensate pump, and the solenoid valve are all electrically connected to the controller.

[0015] As a further description of the above technical solution, a second main valve is connected between the hot well and the condensate pump, and second control valves are connected to both sides of the condensate pump. A check valve and a first flow sensor are also connected between the condensate pump and the recovery water tank. The second control valve and the first flow sensor are both electrically connected to the controller.

[0016] As a further description of the above technical solution, the heating return water unit is also equipped with a first pressure sensor, a filter, a second flow sensor, a circulating water pump, and a third main valve. The circulating water pump is connected to a third control valve on both sides. The heating supply water unit is also equipped with a second pressure sensor and a fourth main valve. The first pressure sensor, the second pressure sensor, the second flow sensor, the circulating water pump, and the three control valves are all electrically connected to the controller.

[0017] This invention provides an evaporator waste steam utilization system. Firstly, it employs a direct condenser heat exchange method, directly transferring the latent heat of the waste steam to the heating circulating water. This reduces energy losses and equipment investment associated with intermediate conversion equipment such as heat pumps, while also improving system reliability due to the reduced equipment. It is particularly suitable for retrofitting and adding to existing factories or heat exchange stations. Secondly, it uses multiple sensors to monitor the system status in real time, which is then processed uniformly by a controller. This automatically controls a vacuum unit with combinations of large and small pumps of varying vacuum efficiencies, reducing manual operation intensity and ensuring safe, stable, and economical system operation under various conditions. It also enables graded and precise adjustment of the condenser vacuum, allowing for wide-range, rapid, and stable adjustment of the output heat. This matches the dynamic heating needs of residents as outdoor temperatures change, solving the core problem of insufficient adjustment capacity in traditional systems. The evaporator waste steam utilization system provided by this invention has the advantages of high heat exchange efficiency, high structural reliability, economic feasibility, high degree of automation, and precise adjustment of heating output. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is one of the schematic diagrams of an evaporator exhaust steam utilization system provided in a specific embodiment of the present invention.

[0020] Figure 2 This is a second schematic diagram of the evaporator exhaust steam utilization system provided in a specific embodiment of the present invention.

[0021] The following labels are shown in the attached diagram:

[0022] 1. Condenser; 11. Inlet of hot side passage; 12. Outlet of hot side passage; 13. Inlet of cold side passage; 14. Outlet of cold side passage; 15. First temperature sensor;

[0023] 2. Evaporator exhaust steam output unit; 21. Electric vacuum regulating valve; 22. Nine evaporators for the evaporation process; 23. Ten evaporators for the evaporation process;

[0024] 3. Vacuum pumping unit; 31. Vacuum pump; 32. First main valve; 33. Vacuum sensor; 34. First control valve;

[0025] 4. Condensate recovery unit; 41. Hot well; 42. Condensate pump; 43. Recovery water tank; 44. Liquid level sensor; 45. Solenoid valve; 46. Second main valve; 47. Second control valve; 48. Check valve; 49. First flow sensor;

[0026] 5. Heating return water unit; 51. Second temperature sensor; 52. First pressure sensor; 53. Filter; 54. Second flow sensor; 55. Circulating water pump; 56. Third main valve; 57. Third control valve;

[0027] 6. Heating and water supply unit; 61. Third temperature sensor; 62. Second pressure sensor; 63. Fourth main valve;

[0028] 7. Heating pipe network;

[0029] 8. New steam output unit. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please refer to Figures 1 to 2 , Figure 1 This is one of the schematic diagrams of an evaporator exhaust steam utilization system provided in a specific embodiment of the present invention; Figure 2This is a second schematic diagram of the evaporator exhaust steam utilization system provided in a specific embodiment of the present invention. The arrows in the diagram indicate the flow direction of liquid or gas.

[0032] This invention uses the utilization of waste steam from the evaporation process in the alumina production industry as an example for illustration:

[0033] In existing alumina production processes, the sodium aluminate solution in the evaporation stage is heated with high-temperature, high-pressure steam to obtain sufficient heat for the water to escape as exhaust steam. This water is then promptly removed using a vacuum method. This allows the exhaust steam generated during mother liquor concentration to be used as a next-stage heat source. The concentrated mother liquor then undergoes flash evaporation for cooling and depressurization, further concentrating and recovering some heat. Finally, the exhaust steam is treated by a water cooler, dissipating the heat into the atmosphere. Although the exhaust steam contains a significant amount of heat energy, its low temperature and pressure prevent traditional energy-saving technologies from recovering it with reasonable process parameters and relatively low engineering costs. While the exhaust steam temperature is not high, there is still considerable potential for utilization, especially in low ambient temperatures (such as winter), where a large temperature difference exists between the exhaust steam and the environment. This provides a viable basis for utilizing the waste heat from the exhaust steam.

[0034] The evaporator in this production system has a vacuum of 0.088-0.090 MPa and a temperature of 58-60℃. The steam output is 40-50 t / h, resulting in considerable heat loss. Calculations show that sufficient steam at 60℃ can raise the temperature of the cold fluid to 56-57℃, and 20 t / h of steam can raise the temperature of 800 m³ / h of circulating water by approximately 10℃. While the use of circulating water at 56-57℃ is somewhat limited in production, it is sufficient for residential winter heating.

[0035] like Figure 1 As shown in the figure, an evaporator waste steam utilization system provided by this invention can utilize the waste heat from the evaporation process of alumina production for heating. The evaporator waste steam utilization system includes a condenser 1, which has a cold-side channel and a hot-side channel. The inlet 11 of the hot-side channel is connected to the evaporator waste steam output unit 2 for introducing the waste steam to be recovered. The outlet 12 of the hot-side channel branches into two paths, respectively connected to a vacuum unit 3 and a condensate recovery unit 4, so that the waste steam condenses and releases latent heat in the hot-side channel, and the resulting condensate is recovered. The inlet 13 of the cold-side channel is connected to a heating return water unit 5, and the outlet 14 of the cold-side channel is connected to a heating supply water unit 6. Both the heating return water unit 5 and the heating supply water unit 6 are connected to the heating network 7. The low-temperature return water in the heating return water unit 5 absorbs the heat released by the condensation of the waste steam in the cold-side channel, and after its temperature rises, it is output from the heating supply water unit 6 for direct heating.

[0036] The vacuum pumping unit 3 includes at least two parallel vacuum pumping branches, each equipped with at least one vacuum pump 31. Different vacuum pumps 31 have different vacuum pumping efficiencies. This embodiment specifically sets up two parallel vacuum pumping branches, each equipped with one vacuum pump 31. By controlling the start-stop combination of the two vacuum pumps 31 (one with a high vacuum pumping efficiency and the other with a low vacuum pumping efficiency), the vacuum level of the hot-side channel of the condenser 1 can be adjusted in a step-wise and precise manner, thereby changing the rate at which exhaust steam enters the hot-side channel, and consequently changing the amount of exhaust steam entering per unit time. Ultimately, this achieves a wide-range, precise, and stable adjustment of the heat exchange power of the condenser 1.

[0037] This allows the different vacuum pumps 31 mentioned above to have the same rated input power, that is, pumps of the same model can be used as different vacuum pumps 31 due to different installation locations. It also allows at least two vacuum pumps 31 to have different rated input power, that is, at least two vacuum pumps 31 are pumps of different models.

[0038] A first temperature sensor 15 is connected between the inlet 11 of the hot-side channel and the evaporator exhaust steam output unit 2 to monitor the temperature of the incoming exhaust steam. A second temperature sensor 51 is installed on the heating return water unit 5, and a third temperature sensor 61 is installed on the heating supply water unit 6 to monitor the heating supply and return water temperatures. The first temperature sensor 15, the second temperature sensor 51, the third temperature sensor 61, and each vacuum pump 31 are electrically connected to the controller. The controller can automatically control the start and stop of the corresponding vacuum pump 31 and automatically control the vacuum pump efficiency of the vacuum pump 31 through logical operations based on the collected temperature signals (especially the supply / return water temperatures), thereby achieving precise on-demand adjustment of the heating supply.

[0039] This invention provides an evaporator waste steam utilization system. Firstly, it employs a direct condenser heat exchange method, directly transferring the latent heat of the waste steam to the heating circulating water. This reduces energy losses and equipment investment associated with intermediate conversion equipment such as heat pumps. The reduced equipment also improves system reliability, making it particularly suitable for retrofitting and adding to existing factories or heat exchange stations. Secondly, it uses multiple sensors to monitor the system status in real time, which is then processed uniformly by a controller. This automatically controls a vacuum unit with combinations of large and small pumps of varying vacuum efficiencies. This not only reduces manual operation intensity and ensures safe, stable, and economical system operation under various conditions but also enables graded and precise adjustment of the condenser vacuum level. This allows for wide-range, rapid, and stable adjustment of the output heat, thus matching the dynamic heating needs of residents as outdoor temperatures change, solving the core problem of insufficient adjustment capacity in traditional systems.

[0040] The evaporator exhaust steam utilization system provided in this embodiment of the invention has the advantages of high heat exchange efficiency, high structural reliability, economic feasibility, high degree of automation, and the ability to finely adjust the heat supply.

[0041] Preferably, in some embodiments, the evaporator exhaust steam output unit 2 includes at least two parallel exhaust steam output branches, each equipped with an electric vacuum regulating valve 21, which is electrically connected to the controller. In this embodiment, the at least two parallel exhaust steam output branches allow for switching between different electric branches during equipment maintenance to prevent system shutdown, and also prevent system shutdown in case of a failure in one branch. Furthermore, by providing the electric vacuum regulating valve 21, the controller can automatically control the opening of the electric vacuum regulating valve to adjust the exhaust steam intake based on collected temperature signals (especially supply / return water temperatures) through logical calculations. This further ensures precise on-demand adjustment of the system's heating supply to match the dynamic heating needs of residents as outdoor temperatures change.

[0042] Furthermore, based on the above embodiments, the evaporator exhaust steam output unit 2 includes a parallel exhaust steam output branch for the last-effect evaporator and an exhaust steam output branch for the second-last-effect evaporator. In the evaporation process of the alumina production industry in this embodiment, the exhaust steam output branch for the second-last-effect evaporator is specifically connected to the nine groups of evaporators 22 in the evaporation process, and the exhaust steam output branch for the last-effect evaporator is specifically connected to the ten groups of evaporators 23 in the evaporation process.

[0043] like Figure 2 As shown, in some embodiments, the inlet 11 of the hot side channel is also connected to a new steam output unit 8 as a backup or peak-shaving heat source to supplement heat when the exhaust steam heat is insufficient, so as to ensure the supplementation of heat supply of this system under extreme conditions.

[0044] Specifically, in some embodiments, a dust collector (not shown in the figure) is also connected between the inlet 11 of the hot-side passage and the evaporator exhaust steam output unit 2. The dust collector can filter impurities from the exhaust steam entering the hot-side passage to protect the condenser 1 and extend its service life.

[0045] Specifically, in some embodiments, a first main valve 32 is also provided on the vacuum branch. A vacuum sensor 33 is connected between the first main valve 32 and the vacuum pump 31. A first control valve 34 is connected between the vacuum sensor 33 and the vacuum pump 31. Both the vacuum sensor 33 and the first control valve 34 are electrically connected to the controller. The first main valve 32 is opened when the system starts running and does not open or close during system operation. The vacuum sensor 33 can monitor the vacuum level in the system in real time, and the first control valve 34 facilitates the automatic opening or closing of the vacuum branch.

[0046] Preferably, in some embodiments, the condensate recovery unit 4 includes a hot well 41 and two parallel condensate recovery branches, each of which is equipped with a condensate pump 42 and a recovery tank 43 connected in sequence. The outlet 12 of the hot-side channel is connected to the hot well 41, and the outlet of the hot well 41 is connected to the inlet of the condensate pump 42. That is, the condensate recovery unit is designed as a dual-pump redundant structure with liquid level monitoring to ensure reliable condensate discharge. The outlet 12 of the hot-side channel is connected to the hot well 41 so that the condensate in the hot-side channel collects in the hot well. When the condensate in the hot well 41 collects to a certain height, the condensate pump 42 is turned on to automatically draw the condensate in the hot well 41 into the recovery tank 43.

[0047] Furthermore, based on the above embodiment, a liquid level sensor 44 is installed on the hot well 41, and a solenoid valve 45 is connected between the condensate pump 42 and the recovery water tank 43. The liquid level sensor 44, the condensate pump 42, and the solenoid valve 45 are all electrically connected to the controller. The controller can automatically start and stop the condensate pump 42 and the solenoid valve 45 according to the liquid level signal emitted by the liquid level sensor 44, thereby realizing the automatic discharge of condensate.

[0048] Furthermore, based on the above embodiment, a second main valve 46 is connected between the hot well 41 and the condensate pump 42. Second control valves 47 are connected to both sides of the condensate pump 42. A check valve 48 and a first flow sensor 49 are also connected between the condensate pump 42 and the recovery water tank 43. Both the second control valves 47 and the first flow sensor 49 are electrically connected to the controller. The second main valve 46 opens when the system starts and does not open or close during system operation. The second control valves 47 are connected to both sides of the condensate pump 42, meaning that second control valves 47 are installed on both the upstream inlet side and the downstream outlet side of the condensate pump 42, facilitating the automatic opening or closing of the condensate recovery branch.

[0049] Preferably, in some embodiments, the heating return water unit 5 is further equipped with a first pressure sensor 52, a filter 53, a second flow sensor 54, a circulating water pump 55, and a third main valve 56. The circulating water pump 55 has third control valves 57 connected to both sides. The heating supply water unit 6 is further equipped with a second pressure sensor 62 and a fourth main valve 63. The first pressure sensor 52, the second pressure sensor 62, the second flow sensor 54, the circulating water pump 55, and the third control valve 57 are all electrically connected to the controller. The third main valve 56 and the fourth main valve 63 are opened when the system is started and are not opened or closed during system operation. The first pressure sensor 52 and the second pressure sensor 62 are used to monitor the pressure on the heating supply and return water units, and the second flow sensor 54 is used to monitor the flow rate of the heating return water unit 5. The filter 53 filters impurities from the heating return water entering the cold side channel to protect the condenser 1 and extend its service life. The circulating water pump 55 is connected to a third control valve 57 on both sides. That is, a third control valve 57 is installed on the upstream inlet side and the downstream outlet side of the circulating water pump 55 to facilitate the automatic opening or closing of the heating and water supply unit.

[0050] The working process of an evaporator exhaust steam utilization system provided by this embodiment of the invention is as follows:

[0051] In the alumina production process, the exhaust steam generated by the industrial evaporator (which may come from the last effect, second-last effect, etc.) is purified by the evaporator exhaust steam output unit 2 and the dust collector before entering the hot side channel of the condenser 1. Low-temperature water from the heating network 7 enters the cold side channel of the condenser 1 from the heating return water unit 5. Inside the condenser, the exhaust steam and low-temperature water exchange heat, and the exhaust steam condenses into water, its latent heat being absorbed by the cold water. The heated water is output from the heating supply water unit 6 and returned to the heating network 7 to provide heating for users. The condensate is collected in a hot well and then automatically discharged by the condensate pump 42. The vacuum pumping unit 3 continuously pumps steam to maintain the system vacuum.

[0052] The controller receives signals from the first temperature sensor 15 (exhaust steam temperature), the second temperature sensor 51 (supply water temperature), and the third temperature sensor 61 (return water temperature) in real time, and compares them with the target supply water temperature set according to the outdoor air temperature.

[0053] If the current water supply temperature is higher than the set value, it indicates an excess of heat supply. The controller can perform one or more of the following operations to reduce the heat supply: 1) Reduce the opening of the electric vacuum regulating valve 21 to reduce the amount of exhaust steam entering; 2) Run only one vacuum pump with low or high vacuum efficiency to reduce the vacuum efficiency of vacuum pump 31, thereby reducing the vacuum level and the exhaust steam entry rate, thus reducing the amount of exhaust steam entering per unit time. If the current water supply temperature is lower than the set value, it indicates an insufficient heat supply. The controller will perform the opposite operation: 1) Open the electric vacuum regulating valve 21 more; 2) Start the vacuum pump with high vacuum efficiency, or run two vacuum pumps 31 to increase the system vacuum level and the exhaust steam entry rate, thereby increasing the amount of exhaust steam entering per unit time. In extreme cases, a new steam output unit 8 can also be opened to supplement heat. Through the above combined adjustment, the system can quickly and smoothly stabilize the water supply temperature near the set value, achieving precise and automatic control of the heat supply.

[0054] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0055] The mechanism provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention. Therefore, this invention is not limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for utilizing evaporator exhaust steam, characterized in that, The system includes a condenser (1), which has a cold side channel and a hot side channel. The inlet (11) of the hot side channel is connected to the evaporator exhaust steam output unit (2), and the outlet (12) of the hot side channel is connected to the vacuum unit (3) and the condensate recovery unit (4), respectively. The inlet (13) of the cold side channel is connected to the heating return water unit (5), and the outlet (14) of the cold side channel is connected to the heating supply water unit (6). Both the heating return water unit (5) and the heating supply water unit (6) are connected to the heating pipe network (7). The vacuum unit (3) includes at least two parallel vacuum branches, each of which is equipped with at least one vacuum pump (31), and different vacuum pumps (31) have different vacuum efficiencies; a first temperature sensor (15) is connected between the inlet (11) of the hot side channel and the evaporator exhaust steam output unit (2); a second temperature sensor (51) is provided on the heating water supply unit (5), and a third temperature sensor (61) is provided on the heating return water unit (6); the first temperature sensor (15), the second temperature sensor (51), the third temperature sensor (61) and each of the vacuum pumps (31) are electrically connected to the controller.

2. The evaporator exhaust steam utilization system according to claim 1, characterized in that, The evaporator exhaust steam output unit (2) includes at least two parallel exhaust steam output branches, and each exhaust steam output branch is provided with an electric vacuum regulating valve (21), which is electrically connected to the controller.

3. The evaporator exhaust steam utilization system according to claim 2, characterized in that, The evaporator exhaust steam output unit (2) includes a parallel exhaust steam output branch for the last-effect evaporator and an exhaust steam output branch for the second-last-effect evaporator.

4. The evaporator exhaust steam utilization system according to claim 1, characterized in that, The inlet (11) of the hot side channel is also connected to a new steam output unit (8).

5. The evaporator exhaust steam utilization system according to claim 1, characterized in that, A dust collector is also connected between the inlet (11) of the hot side channel and the evaporator exhaust steam output unit (2).

6. The evaporator exhaust steam utilization system according to claim 1, characterized in that, The vacuum branch is also provided with a first main valve (32), a vacuum sensor (33) is connected between the first main valve (32) and the vacuum pump (31), a first control valve (34) is connected between the vacuum sensor (33) and the vacuum pump (31), and the vacuum sensor (33) and the first control valve (34) are both electrically connected to the controller.

7. The evaporator exhaust steam utilization system according to claim 1, characterized in that, The condensate recovery unit (4) includes a hot well (41) and two parallel condensate recovery branches. Each condensate recovery branch is provided with a condensate pump (42) and a recovery water tank (43) connected in sequence. The outlet (12) of the hot side channel is connected to the hot well (41), and the outlet of the hot well (41) is connected to the inlet of the condensate pump (42).

8. The evaporator exhaust steam utilization system according to claim 7, characterized in that, A liquid level sensor (44) is installed on the hot well (41), and a solenoid valve (45) is connected between the condensate pump (42) and the recovery water tank (43). The liquid level sensor (44), the condensate pump (42) and the solenoid valve (45) are all electrically connected to the controller.

9. The evaporator exhaust steam utilization system according to claim 7, characterized in that, A second main valve (46) is connected between the hot well (41) and the condensate pump (42). A second control valve (47) is connected to both sides of the condensate pump (42). A check valve (48) and a first flow sensor (49) are also connected between the condensate pump (42) and the recovery tank (43). The second control valve (47) and the first flow sensor (49) are both electrically connected to the controller.

10. The evaporator exhaust steam utilization system according to claim 1, characterized in that, The heating return water unit (5) is also equipped with a first pressure sensor (52), a filter (53), a second flow sensor (54), a circulating water pump (55), and a third main valve (56). The circulating water pump (55) is connected to a third control valve (57) on both sides. The heating water supply unit (6) is also equipped with a second pressure sensor (62) and a fourth main valve (63). The first pressure sensor (52), the second pressure sensor (62), the second flow sensor (54), the circulating water pump (55), and the three control valves (57) are all electrically connected to the controller.

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