Extraction back pressure vacuum heating steam turbine and its operation mode

Abstract

The present invention discloses an extraction back-pressure vacuum heating steam turbine, in which at least one set of through holes, namely a first through hole group and a second through hole group, is provided along the flow direction of high-temperature and high-pressure steam in the steam turbine; wherein the two groups of through holes are respectively located at the positions of optimized static baffles, and the first and second through hole groups are respectively located on the cylinder of the steam turbine; the first and second through hole groups are respectively connected through an extraction main pipe and an extraction regulating valve, so as to adjust the flow rate of high-temperature and high-pressure steam; along the flow direction of steam, the first through hole group is in front of the regulating valve; a first external steam supply pipeline is connected between the first through hole group and the extraction regulating valve, and the switching of multiple modes of the steam turbine is realized through the regulating valve, and multiple operation modes are provided, so as to achieve the purposes of free switching, high efficiency and low cost.

Description

Technical Field

[0001] The invention relates to the field of steam turbines, and in particular to a steam turbine and an operating mode that can be switched between different modes. Background Art

[0002] A steam turbine, also known as a steam turbine engine, is a rotary steam power device. High-temperature and high-pressure steam passes through a fixed nozzle and becomes an accelerated steam flow, which is then sprayed onto the blades, causing the rotor with the blades to rotate and perform work externally. Steam turbines are the main equipment in modern thermal power plants and are also used in the metallurgical industry, chemical industry, and ship power devices.

[0003] There are several types of steam turbines including condensing, heating, back pressure, extraction and saturated steam turbines.

[0004] The steam discharged from the condensing steam turbine flows into the condenser, and the exhaust pressure is lower than the atmospheric pressure. Therefore, it has good thermal performance and is the most commonly used type of steam turbine; the heating steam turbine not only provides power to drive the generator or other machinery, but also provides heat for production or life, and has a high thermal energy utilization rate; the exhaust pressure of the back-pressure steam turbine is a steam turbine greater than the atmospheric pressure; the extraction steam turbine is a steam turbine that can extract steam from the intermediate stage for heating; the saturated steam turbine is a steam turbine that uses saturated steam as new steam.

[0005] In simple terms:

[0006] Back pressure refers to the positive pressure of the exhaust steam at the tail of the steam turbine (no negative pressure or vacuum);

[0007] Condensation means that the exhaust steam pressure at the tail of the steam turbine is negative pressure (connected with a negative pressure extraction device, such as a condenser);

[0008] Steam extraction refers to extracting part (or all) of the steam from the inside of the steam turbine for external use or work. If the steam extraction is only a part, there are still two forms of exhaust at the tail of the steam turbine: extraction back pressure (extraction back) and extraction condensation (extraction condensation).

[0009] Existing power station steam turbines are generally cooled in the form of water towers, which causes a large loss of heat and cannot meet the use of different working conditions in winter and summer, such as:

[0010] When used in winter, it can provide heating to surrounding users, and the heat utilization rate is relatively good;

[0011] When used in summer, the steam turbine still needs to operate as a whole. For example, the extraction steam turbine can only output from the very end, resulting in a large amount of waste heat being wasted. Summary of the invention

[0012] In order to solve the above technical problems, the present invention provides a new steam turbine that can be switched between different modes, and on this basis provides a new extraction back-pressure vacuum heating steam turbine and a new operating mode, which can freely switch between extraction and back pressure, condensation, and heating modes, thereby greatly improving the operating efficiency and heat utilization rate.

[0013] To achieve the above object, the present invention is implemented through the following technical solutions:

[0014] An extraction back-pressure vacuum heating steam turbine, wherein a moving impeller and a static baffle matched therewith are arranged in stages in the steam turbine cylinder, and at least one set of through holes, namely a first through hole group and a second through hole group, is arranged behind the moving impeller of at least the first-stage static baffle along the flow direction of high-temperature and high-pressure steam; wherein the two sets of through holes are respectively located at the positions of the optimized static baffles;

[0015] The first and second through hole groups are respectively located on the turbine cylinder; the first and second through hole groups are correspondingly connected through a steam extraction regulating valve, and the regulating valve is used to adjust the steam flow rate of high-temperature and high-pressure steam entering the second through hole group through the first through hole group;

[0016] Along the flow direction of the steam, the first through hole group is in front of the regulating valve; a first external steam supply pipeline is connected between the first through hole group and the air extraction regulating valve.

[0017] Preferably, the optimized partitions located at the two groups of through holes are sealing adjustment partitions.

[0018] The middle of the partition is provided with an axial hole for the turbine rotor to pass through. The front end face of the sealing and regulating partition seals the high-pressure steam in front. An annular groove is provided on the annular side of the partition towards the axial hole.

[0019] The annular groove has a first annular edge and a second annular edge formed on both sides thereof to match with the groove of the steam turbine cylinder, wherein the second annular edge is located away from the steam inlet end of the steam turbine; a steam inlet channel for steam to pass through is provided inside the second annular edge;

[0020] The two groups of annular through holes, wherein the first through hole group is located between the first ring edge and the previous stage impeller, and the second through hole group is located between the first ring edge and the second ring edge;

[0021] In the radial direction, the annular groove is provided with nozzle group partition ribs at intervals, and two adjacent partition ribs, the first ring edge, and the bottom of the annular groove form a cavity. The steam enters along the second through hole group, enters the cavity, and is discharged through the steam inlet channel to the next stage.

[0022] Preferably, the tail outlet of the steam turbine is connected to a heat exchanger via a regulating valve, and the heat exchanger is used for heat supply; a second external steam supply pipeline is connected in parallel with the regulating valve and the heat exchanger.

[0023] Preferably, the tail outlet of the steam turbine is connected to a condenser.

[0024] Preferably, a blocking plate is detachably provided between the tail outlet of the steam turbine and the connected condenser; a second outlet is provided at the tail of the steam turbine, and the second outlet is connected to a second external heat supply pipeline.

[0025] Preferably, a vacuum device is provided on the second external heat supply pipeline and the heat exchanger.

[0026] Preferably, a sealing partition is provided on the inner side of the tail of the turbine, the turbine rotor passes through the sealing partition, the outer ring of the sealing partition is sealed by a groove arranged on the turbine cylinder, and a through hole is provided on the sealing partition, through which the steam is output from the turbine.

[0027] A switching operation mode of the steam turbine,

[0028] Mode 1: Full steam supply mode

[0029] The steam turbine uses a sealed regulating diaphragm. At this time, the steam extraction regulating valve is completely closed, the passage between the first and second through hole groups is cut off, and the first external steam supply pipeline is opened. After the high-temperature and high-pressure steam works in the front section of the steam turbine, the high-temperature and high-pressure steam is directly used as industrial steam and no longer flows through the rear section of the steam turbine;

[0030] Mode 2: Power generation mode

[0031] The steam turbine uses a sealed regulating diaphragm;

[0032] At this time, the first external steam supply pipeline is completely closed, the steam extraction regulating valve is completely opened, the passage between the first and second through hole groups is opened, and the steam flows through the entire steam turbine;

[0033] Mode 3: Adjusting steam supply mode

[0034] The steam turbine uses a sealed regulating diaphragm;

[0035] According to the pressure matching needs, the steam extraction regulating valve and the first external steam supply pipeline are opened at the same time. According to the pressure matching needs, the steam supply pressure is adjusted through the regulating valve to distribute the flow of the first external steam supply pipeline and the steam flow through the tail of the turbine.

[0036] In the operation mode: In the above steam turbine mode 2 and mode 3, the tail of the steam turbine is provided with the following modes:

[0037] Tail mode 1: Only the condenser is connected. The condenser establishes and maintains a high vacuum at the turbine exhaust port. At the same time, the water condensed at the turbine exhaust port is used as boiler feed water, forming a complete cycle.

[0038] Tail mode 2: Based on tail mode 1, a plugging plate is provided at the outlet of the steam turbine, and a second outlet is provided at the tail of the steam turbine, and the second outlet is connected to the second external steam supply pipeline. The plugging plate is fixedly connected to the plugging plate of the steam turbine outlet, and the condenser is plugged when not in use; at this time, the switching between the condenser being used alone and the second external steam supply pipeline being used alone is realized;

[0039] Tail mode 3: A heat exchanger is connected to the tail outlet of the steam turbine through a regulating valve, and a second external steam supply pipeline is provided in parallel with the heat exchanger. A throttle valve is provided on the heat exchanger and the second external steam supply pipeline respectively. The following three modes are realized through the respective throttle valves:

[0040] A. Full heating mode: In winter, close the second external steam supply pipeline and open the heat exchanger. The heat exchanger can provide heating for residential or industrial areas in winter.

[0041] B. Full steam supply mode: Outside the heating period, close the heat exchanger and open the second external steam supply pipeline to meet the industrial steam supply needs at lower temperature and lower pressure;

[0042] C. Mixed mode: Open the regulating valves of the heat exchanger and the second external steam supply pipeline to realize dual channels. The size of the channels can be adjusted according to the needs of temperature and pressure.

[0043] The steam turbine provided by the present invention creatively introduces an improved partition and is provided with at least two sets of through holes (first and second through hole groups) on the turbine cylinder. The two sets of through holes are connected through a mother pipe or a directly connected steam extraction regulating valve. In this way, when the regulating valve is opened, the high-temperature and high-pressure steam in front of the partition can enter the rear of the steam turbine through the first through hole, the regulating valve, the second through hole, and the steam inlet pipe; when the sealing regulating valve is closed, the high-temperature and high-pressure steam can directly enter the first external steam supply pipeline, which is convenient for meeting the industrial steam needs that require (high-temperature and high-pressure) steam.

[0044] The present invention provides a new sealing regulating baffle, one end of which facing the turbine inlet is completely sealed, forming a basis for intercepting high-temperature and high-pressure steam.

[0045] The first and second ring edges are matched with the annular grooves on the inner wall of the turbine cylinder to achieve sealing on the one hand and fix the partition on the other hand.

[0046] The steam inlet channel arranged on the second ring edge can allow the high-temperature and high-pressure steam that bypasses the steam extraction regulating valve to continue to flow through the rear of the steam turbine to continue to do work. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The schematic diagram of the steam turbine structure under the sealing and regulating diaphragm structure;

[0048] Figure 2The schematic diagram of the steam turbine structure under the sealing and regulating diaphragm structure;

[0049] Figure 3 for Figure 2 AA view;

[0050] Figure 4 Schematic diagram of the throttling baffle structure;

[0051] Figure 5 for Figure 4 Side view of

[0052] Figure 6 It is a schematic diagram of the steam turbine structure under the throttling diaphragm structure;

[0053] Figure 7 The schematic diagram of the steam turbine structure is provided with a sealing partition;

[0054] Figure 8 for Figure 7 AA view;

[0055] Fig. 9 It is a schematic diagram of the steam turbine structure with two sets of vent groups;

[0056] Fig.10 It is a schematic diagram of the structure with steam extraction main pipe. DETAILED DESCRIPTION

[0057] The present solution is described below in conjunction with the accompanying drawings and specific implementation methods.

[0058] The existing steam turbine itself is equipped with a matching multi-stage static baffle and impeller combination. Each stage includes a static baffle fixed to the turbine cylinder and a moving impeller fixed to the rotor. Along the flow direction of high-pressure steam, each stage of the static baffle is located in front of the moving impeller. The outer ring of the static baffle is fixed to the inside of the turbine cylinder through a groove, and the middle part of the static baffle is sealed with the rotor through a steam seal.

[0059] The essence of the present invention is to open two groups of through holes on the cylinder of the steam turbine, namely, a first through hole group 3 and a second through hole group 4, and to connect the two groups of through holes correspondingly through a steam extraction regulating valve 5. Figure 1 As shown, along the steam flow direction, the first through hole group is in front of the steam extraction regulating valve 5; a first external steam supply pipeline 7 is connected between the first through hole group and the steam extraction regulating valve.

[0060] Because the high-temperature and high-pressure steam flows uniformly in an annular manner during the operation of the steam turbine, preferably, the first through hole group 3 and the second through hole group 4 are arranged in a rectangular array with the axis of the steam turbine rotor as the center, so as to form a stable and uniform steam flow rate; for the convenience of connection, each steam extraction mother pipe of the first through hole group 3 can be connected, and the steam extraction mother pipe is connected to the through holes of the second through hole group 4 through the steam extraction regulating valve 5. The steam extraction regulating valve 5 can be set on the mother pipe 41, such as Fig.10 As shown, one may also be provided on each branch.

[0061] For ease of processing, the two groups of through holes can be along the radial direction of the cylinder; however, in order to ensure smooth flow of steam, the two groups of through holes can be tilted, each tilted toward the direction of the steam extraction regulating valve to reduce the right-angle flow resistance of the steam.

[0062] In order to cooperate with the two groups of through holes and play the role of throttling the steam, the present invention also optimizes "a certain level" of the static baffle. Along the direction of high-pressure steam flow, a moving impeller fixed to the turbine rotor is still provided behind the optimized baffle.

[0063] Because the temperature and pressure of high-temperature and high-pressure steam are very high, it cannot be used directly in industry and civilian use. Therefore, the steam turbine needs to be operated first, and the steam with a relatively low temperature and pressure after the work can be directly used. Therefore, the "certain level" in this embodiment should not be the first level. The specific level can be selected according to the needs of the steam pressure and temperature.

[0064] This embodiment selects the fourth level. This implementation method adopts two forms. Generally, one or two sets can meet the needs.

[0065] The position of the optimized baffle should be located at the positions of the two groups of through holes, that is, the two groups of through holes should be located at the position of the optimized baffle, and a moving impeller 2 is provided behind the optimized baffle.

[0066] The present invention provides an optimized partition:

[0067] Sealing adjustment partition 1, Figure 2 , 3 As shown, the partition is a flat (plate) columnar structure, which is generally assembled into an integral structure using two semicircles, and an axial hole 11 for the turbine rotor to pass through is provided in the middle of the partition, and an annular groove 12 is provided on the annular side of the partition toward the axial hole, and a first annular edge 13 and a second annular edge 14 are formed on both sides of the annular groove 12 to match the groove of the turbine cylinder, wherein the second annular edge 14 is far away from the steam inlet end of the turbine, a sealing surface is formed on the front side of the first annular edge 13, and a steam inlet channel 15 is provided on the inner side of the second annular edge.

[0068] Among the two groups of annular through holes, the first through hole group 3 is located between the first ring edge 13 and the previous stage impeller, and the second through hole group 4 is located between the first ring edge 13 and the second ring edge 14; the first and second groups of through holes are connected through the steam extraction regulating valve 5 respectively for adjusting the high-pressure steam flow.

[0069] In the radial direction, the annular groove is provided with nozzle group partition ribs 16 at intervals, and two adjacent partition ribs, the first ring edge, and the bottom of the annular groove form a four-sided closed cavity, so that the steam enters through the second through hole group and is discharged from the steam inlet channel to the next stage. The second ring edge is provided with steam nozzles (not shown, the existing design can be used), and the steam nozzles are evenly arranged in the steam inlet channel.

[0070] Because a circular channel is formed when the steam turbine rotates, the steam inlet channel 15 is spaced apart in a circular array with the center of the partition as the center, so as to facilitate the flow of steam and form a stable and uniform flow rate and pressure. For ease of processing, the steam inlet channel 15 can be a fan-shaped through hole, and the lower arc surface of the fan is flush with the annular groove.

[0071] The above-mentioned sealing adjustment partition 1 is adopted. In order to adapt to the first ring edge 13 and the second ring edge 14, an inner groove is provided on the inner wall of the turbine cylinder, so that the first ring edge 13 and the second ring edge 14 can be fixed to the turbine cylinder through the inner groove.

[0072] There is at least one level of original static baffle moving blades in front of the sealing and adjusting baffle 1 to facilitate the overall operation of the system. The sealing and adjusting baffles are generally used in one or two groups. Figure 1 , 6 The first level is adopted. Fig. 9 It is a secondary institution.

[0073] The above steam supply method can run three working modes:

[0074] Mode 1: Full steam supply mode

[0075] The steam turbine adopts a sealed regulating diaphragm 1. At this time, the steam extraction regulating valve 5 is completely closed, the passage between the first and second through hole groups is cut off, and the first external steam supply pipeline is opened. After the high-temperature and high-pressure steam works in the front section of the steam turbine, the high-temperature and high-pressure steam is directly used for industrial steam and no longer flows through the rear section of the steam turbine;

[0076] In this mode, although the steam is used to supply steam to the outside, the steam turbine cannot completely seal the steam 100%, and some steam will enter the tail of the steam turbine. After entering the tail, the steam will feel the rotational resistance caused by the impeller and static baffle when the steam turbine rotates, and lose some energy. Therefore, a low-pressure vacuum device is connected to the tail of the steam turbine to extract the steam escaping to the tail in time, thereby reducing resistance and improving energy utilization.

[0077] Mode 2: Power generation mode

[0078] The steam turbine uses a sealed regulating diaphragm;

[0079] At this time, the first external steam supply pipeline is completely closed, the steam extraction regulating valve is completely opened, the passage between the first and second through hole groups is opened, and the steam flows through the entire steam turbine;

[0080] Mode 3: Adjusting steam supply mode

[0081] The steam turbine uses a sealed regulating diaphragm;

[0082] According to the pressure matching needs, open the steam extraction regulating valve and the first external steam supply pipeline at the same time, adjust the pressure of the regulating valve according to the pressure matching needs, and distribute the steam flow of the first external steam supply pipeline flowing through the tail of the turbine.

[0083] Only in the above-mentioned modes 2 and 3, a large amount of steam enters the tail of the steam turbine. The steam entering the tail of the steam turbine can have the following modes after passing through the steam turbine:

[0084] Tail mode 1:

[0085] The tail is only connected to the condenser 8, which establishes and maintains a high vacuum at the turbine exhaust port. At the same time, the water condensed at the turbine exhaust port is used as boiler feed water, forming a complete cycle. Figure 6 shown.

[0086] Tail mode 2:

[0087] On the basis of tail mode 1, a plugging plate 30 can be provided at the outlet of the steam turbine, and at the same time, a second outlet is opened at the tail of the steam turbine, and the second outlet is connected to the second external steam supply pipeline 20, and the plugging plate is connected to the outlet flange of the steam turbine, and the condenser can be blocked when not in use; at this time, the condenser and the second external steam supply pipeline can be switched, and the condenser can be used alone or the second external steam supply pipeline can be used alone; Figure 6 shown.

[0088] Tail mode three:

[0089] The outlet of the steam turbine tail is connected to a heat exchanger 9 through a regulating valve, and a second external steam supply pipeline 20 is provided in parallel with the heat exchanger 9. The heat exchanger and the second external steam supply pipeline are each provided with a throttle valve, and the following three modes are realized through each throttle valve:

[0090] A. Full heating mode: In winter, close the second external steam supply pipeline and open the heat exchanger. The heat exchanger can provide heating for residential or industrial areas in winter. Preferably, the heat exchanger can be operated under vacuum negative pressure to improve the efficiency of the steam turbine.

[0091] B. Full steam supply mode: Outside the heating period, close the heat exchanger and open the second external steam supply pipeline to meet the industrial steam supply needs of lower temperature and lower pressure.

[0092] C. Mixed mode: Open the regulating valves of the heat exchanger and the second external steam supply pipeline to realize dual channels. The size of the channels can be adjusted according to the needs of temperature and pressure.

[0093] During back pressure operation, because the pressure at the tail of the steam turbine is relatively high, but the tail of the steam turbine can withstand a relatively low pressure due to material problems, a sealing partition 31 is added behind the last stage impeller. Figure 7 , 8 As shown, the high-pressure steam at the front no longer enters the rearmost part of the steam turbine. A through hole 32 is opened on the sealing partition, and a pipe 33 is connected to the through hole 32. The other end of the pipe goes around the steam turbine and is connected to the final user end, such as a heat exchanger, a second external heat supply pipeline, etc.

Claims

1. A steam extraction back pressure vacuum heating steam turbine, wherein a moving impeller and a static baffle cooperating therewith are arranged in stages in the steam turbine cylinder, characterized in that: Along the flow direction of the high-temperature and high-pressure steam, at least one set of through holes, namely, a first through hole group and a second through hole group, is provided behind the impeller of at least the first-stage static baffle; wherein the two sets of through holes are respectively located at the positions of the optimized static baffles; The first and second through hole groups are respectively located on the turbine cylinder; the first and second through hole groups are correspondingly connected through a steam extraction regulating valve, and the steam extraction regulating valve is used to adjust the steam flow rate of high-temperature and high-pressure steam entering the second through hole group through the first through hole group; Along the steam flow direction, the first through hole group is in front of the steam extraction regulating valve; a first external steam supply pipeline is connected between the first through hole group and the steam extraction regulating valve; The optimized static baffles located at the two sets of through holes are sealed and adjusted baffles. The middle of the sealing and adjusting partition is provided with an axial hole for the turbine rotor to pass through. The front end surface of the sealing and adjusting partition seals the high-pressure steam in front. An annular groove is provided on the annular side surface of the sealing and adjusting partition towards the axial hole. The annular groove has a first annular edge and a second annular edge formed on both sides thereof to match with the groove of the steam turbine cylinder, wherein the second annular edge is located away from the steam inlet end of the steam turbine; a steam inlet channel for steam to pass through is provided inside the second annular edge; Among the two groups of through holes, the first through hole group is located between the first ring edge and the previous stage impeller, and the second through hole group is located between the first ring edge and the second ring edge; In the radial direction, nozzle group spacing ribs are arranged in the annular groove at intervals, and two adjacent spacing ribs, the first ring edge, and the bottom of the annular groove form a cavity. The steam enters along the second through hole group, enters the cavity, and is discharged through the steam inlet channel to enter the next stage; A sealing partition is provided on the inner side of the tail of the steam turbine, and the turbine rotor passes through the sealing partition. The outer ring of the sealing partition is sealed by a groove arranged on the turbine cylinder. A through hole is provided on the sealing partition, and the steam is output from the turbine through the through hole.

2. The steam turbine according to claim 1, characterized in that The tail outlet of the steam turbine is connected to a heat exchanger through a regulating valve, and the heat exchanger is used for heat supply; a second external steam supply pipeline is connected in parallel with the regulating valve and the heat exchanger.

3. The steam turbine according to claim 1, characterized in that: The tail outlet of the steam turbine is connected to the condenser.

4. The steam turbine according to claim 3, characterized in that A blocking plate is detachably provided between the tail outlet of the steam turbine and the condenser; a second outlet is provided at the tail of the steam turbine, and the second outlet is connected to a second external heat supply pipeline.

5. The steam turbine according to claim 2, characterized in that: The second external heat supply pipeline and the heat exchanger are provided with a vacuum device.

6. A switching operation mode of the extraction back-pressure vacuum heating steam turbine according to claim 1, characterized in that: Mode 1: Full steam supply mode The steam turbine uses a sealed regulating diaphragm. At this time, the steam extraction regulating valve is completely closed, the passage between the first and second through hole groups is cut off, and the first external steam supply pipeline is opened. After the high-temperature and high-pressure steam works in the front section of the steam turbine, the high-temperature and high-pressure steam is directly used as industrial steam and no longer flows through the rear section of the steam turbine; Mode 2: Power generation mode The steam turbine uses a sealed regulating diaphragm; At this time, the first external steam supply pipeline is completely closed, the steam extraction regulating valve is completely opened, the passage between the first and second through hole groups is opened, and the steam flows through the entire steam turbine; Mode 3: Adjusting steam supply mode The steam turbine uses a sealed regulating diaphragm; According to the pressure matching needs, the steam extraction regulating valve and the first external steam supply pipeline are opened at the same time. According to the pressure matching needs, the steam supply pressure is adjusted through the steam extraction regulating valve to distribute the steam flow through the first external steam supply pipeline and the steam flow flowing through the tail of the turbine.

7. The switching operation mode of the extraction back-pressure vacuum heating steam turbine according to claim 6 is characterized in that: Under the above steam turbine modes 2 and 3, the tail section of the steam turbine is provided with the following modes: Tail mode 1: Only the condenser is connected. The condenser establishes and maintains a high vacuum at the turbine exhaust port. At the same time, the water condensed at the turbine exhaust port is used as boiler feed water, forming a complete cycle. Tail mode 2: Based on tail mode 1, a plugging plate is provided at the outlet of the steam turbine, and a second outlet is provided at the tail of the steam turbine, and the second outlet is connected to the second external steam supply pipeline. The plugging plate is fixedly connected to the plugging plate of the steam turbine outlet, and the condenser is plugged when not in use; at this time, the switching between the condenser being used alone and the second external steam supply pipeline being used alone is realized; Tail mode 3: A heat exchanger is connected to the tail outlet of the steam turbine through a regulating valve, and a second external steam supply pipeline is provided in parallel with the heat exchanger. A throttle valve is provided on the heat exchanger and the second external steam supply pipeline respectively. The following three modes are realized through the respective throttle valves: A. Full heating mode: In winter, close the second external steam supply pipeline and open the heat exchanger. The heat exchanger can provide heating for residential or industrial areas in winter. B. Full steam supply mode: Outside the heating period, close the heat exchanger and open the second external steam supply pipeline to meet the industrial steam supply needs at lower temperature and lower pressure; C. Mixed mode: Open the regulating valve, heat exchanger, and throttle valve of the second external steam supply pipeline to realize dual channels. The size of the channel can be adjusted according to the needs of temperature and pressure.

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