A device for directly recovering waste heat from turbine exhaust steam

Abstract

The present invention relates to a device for directly recovering waste heat of turbine exhaust steam, comprising a steam turbine, a turbine exhaust steam pipeline, a heat exchange device, a condensate pump, a cold side inlet pipeline of the heat exchange device, a cold side outlet pipeline of the heat exchange device, a detector, a valve, and a controller. The present invention utilizes turbine exhaust steam to heat the cold side logistics through the heat exchange device, selects a turbine with a suitable outlet back pressure, so that the temperature of the turbine exhaust steam meets the heat exchange requirements of the heat demand user, so that the two can be coupled for heat exchange, saving the cold energy consumption of circulating water and other public works and the heat energy consumption of steam, warm water and other public works; the present invention recovers and utilizes turbine exhaust steam as a low-temperature heat source, which has a significant energy-saving effect on the one hand, and can save the investment in heat exchange equipment on the other hand. More importantly, it can obtain significant benefits in the reasonable use of energy levels: realizing the same-level utilization of turbine exhaust steam.

Description

Technical Field

[0001] The invention relates to a device for directly recovering turbine exhaust steam waste heat. Background Art

[0002] As my country's energy conservation and emission reduction requirements for chemical companies become increasingly stringent and energy conservation work continues to deepen, it is becoming increasingly difficult for refining companies to further reduce the energy consumption of their equipment and the entire plant. Realizing the comprehensive utilization of thermal energy, especially the optimal utilization of low-temperature waste heat, has become the main development direction for refining companies to further save energy and reduce emissions.

[0003] For conventional steam turbines, after steam does work in the turbine, the exhaust temperature is relatively low, generally 40-65°C, and the general pressure is 7.5-25KPaA. These turbine exhaust steam needs to be cooled by cooling water and then discharged or pumped to recover condensate. Conventional turbine exhaust steam, a low-temperature heat source, often has a very large volume flow rate due to relatively low temperature and high vacuum, resulting in a very large size of the transmission pipeline, making equipment layout and pipeline layout difficult. Therefore, the low-temperature heat energy of turbine exhaust steam cannot be fully utilized, resulting in a large waste of energy. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a device for directly recovering the waste heat of turbine exhaust steam by adjusting the back pressure of turbine exhaust steam and thus adjusting the temperature of turbine exhaust steam to meet the heat exchange requirements of users with heat demands and realize turbine exhaust steam capacity recovery and utilization in response to the current status of the prior art.

[0005] The technical solution adopted by the present invention to solve the above technical problems is:

[0006] A device for directly recovering waste heat from turbine exhaust steam, comprising:

[0007] A steam turbine, with a steam pipeline for steam input connected to the front side, is used to provide a place for steam to do work;

[0008] a turbine exhaust pipeline, the inlet of which is connected to the exhaust end of the steam turbine;

[0009] a heat exchange device, used for exchanging heat with steam, the inlet of which is connected to the outlet of the turbine exhaust pipeline;

[0010] A condensate pump is arranged downstream of the heat exchange device, the inlet of the pump is connected to the outlet of the heat exchange device through a pump inlet condensate pipeline, and the outlet is connected to a pump outlet condensate pipeline;

[0011] a heat exchange equipment cold side inlet pipeline connected to the cold side inlet of the heat exchange equipment; and

[0012] A cold side outlet pipeline of the heat exchange device, connected to the cold side outlet of the heat exchange device;

[0013] There are multiple detectors, each used to detect the temperature, pressure and flow rate of the fluid in each pipeline;

[0014] Valves, which are multiple and are respectively arranged on each pipeline to control the flow of each pipeline;

[0015] The controller is connected with the detector and the valve electrical signal, and is used to adjust the flow rate of the turbine exhaust steam so as to adjust the back pressure of the steam turbine.

[0016] It should be noted that the design values ​​of turbine temperature and back pressure in the present invention can be completed before equipment selection, that is, the exhaust temperature and back pressure of the turbine are determined in the process calculation; the control valve and other control actuators set at the turbine outlet are used for fine-tuning, that is, the back pressure at the turbine outlet will be slightly higher than the required pressure (P51), and the pressure reduction through the control valve meets the requirements. In the present invention, the temperature T / ℃, pressure P / MPaA, flow rate F / (kg / h), and enthalpy value H / (kJ / kg) are defined, then:

[0017] Steam information in steam pipeline: gas phase, T4, P4, F4, H4;

[0018] Turbine outlet exhaust information in the turbine exhaust pipeline: saturated gas phase, T51, P51, F51, H51;

[0019] Exhaust information at the inlet of the heat exchange equipment in the turbine exhaust pipeline: saturated gas phase, T52, P52, F52, H52;

[0020] Pump inlet condensate information in the pump inlet condensate pipeline: liquid phase, T6, P6, F6, H6;

[0021] Pump outlet condensate information in the pump outlet condensate pipeline: liquid phase, T7, P7, F7, H7;

[0022] Medium information in the cold side inlet pipeline of the heat exchange equipment: unlimited phase, T8, P8, F8, H8;

[0023] Medium information in the cold side outlet pipeline of the heat exchange equipment: unlimited phase, T9, P9, F9, H9;

[0024] The output power of the steam turbine is F4×H4-F51×H51, which is given by the external demand of the device.

[0025] Preferably, in the heat exchange equipment, the turbine exhaust steam and the cold side medium exchange heat, the increased enthalpy value of the cold side medium is equal to the reduced enthalpy value of the turbine exhaust steam condensation, and the turbine exhaust steam needs to meet the heat load requirement of the heat exchange equipment, F8×(H9-H8)=F4×(H4-H5), where F8×(H9-H8) is given by the demand outside the device.

[0026] Preferably, the hot-side inlet temperature of the heat exchange equipment is higher than the cold-side outlet temperature, i.e., T52 > T9. The hot-side inlet temperature is determined by the turbine back pressure, i.e., the pressure of the exhaust steam. When the temperature of the turbine exhaust steam increases, considering that the steam conditions (temperature, pressure, etc.) and the output power at the turbine inlet remain unchanged, the steam consumption required by the turbine will increase. At the same time, higher requirements will be put forward for the mechanical design of the turbine. Therefore, T51 and T52 should not be too high.

[0027] Preferably, 0.01 °C < T52 - T9 < 200 °C, 0.01 °C < T52 - T8 < 220 °C, where T8 and T9 are given by the external requirements of the device. More preferably, 5 °C < T52 - T9 < 50 °C, 10 °C < T52 - T8 < 50 °C; most preferably, 10 °C < T52 - T9 < 20 °C, 10 °C < T52 - T8 < 20 °C.

[0028] Preferably, the size of the turbine exhaust pipeline should be selected to satisfy (P51 - P52) < 100 kPa, (T51 - T52) < 100 °C. More preferably, the size of the turbine exhaust pipeline (5) should be selected to satisfy (P51 - P52) < 20 kPa, (T51 - T52) < 20 °C; most preferably, the size of the turbine exhaust pipeline (5) should be selected to satisfy (P51 - P52) < 3 kPa, (T51 - T52) < 3 °C. The size of the turbine exhaust pipeline should be reasonably determined to meet the requirements that both the pressure drop (P51 - P52) and the temperature drop (T51 - T52) are as small as possible. On the one hand, the larger the size, the larger the flow area, and the smaller the pressure drop (P51 - P52); on the other hand, the larger the size, the larger the heat exchange area, and the larger the temperature drop (T51 - T52). For a determined flow rate, pipeline length, and overall heat transfer coefficient, using the above parameters of the present invention, the best energy-saving effect can be obtained.

[0029] Preferably, the straight-line distance between the steam turbine and the heat exchange equipment is not greater than 10 km, and the length of the turbine exhaust pipeline is not greater than 20 km. More preferably, the straight-line distance between the two should not be greater than 1 km, and the length of the connected pipeline should not be greater than 2 km; most preferably, the straight-line distance between the two should not be greater than 0.5 km, and the length of the connected pipeline should not be greater than 1 km. Since the turbine exhaust generally has characteristics such as a relatively high vacuum degree, higher than the ambient temperature, and a relatively large mass flow rate, the volume flow rate of the turbine exhaust is very large, resulting in an extremely large size of the turbine exhaust pipeline. At the same time, in terms of process technology, it is required that both the pressure drop (P51 - P52) and the temperature drop (T51 - T52) of the turbine exhaust pipeline are as small as possible to reduce heat energy loss. Therefore, the steam turbine and the heat exchange equipment should be arranged as close as possible, and the turbine exhaust pipeline should also be as short as possible.

[0030] Preferably, the turbine outlet of the turbine exhaust pipeline is higher than the inlet of the heat exchanger. The turbine exhaust pipeline needs to fully consider the influence of the accumulated liquid formed by the condensation of the turbine exhaust. Generally, the turbine exhaust pipeline should not have a bag shape (that is, the lowest point of the turbine exhaust pipeline is lower than the turbine outlet and the inlet of the heat exchanger). If the turbine exhaust pipeline has a bag shape, a drainage facility must be installed at the lowest point. The present invention preferably adopts the above structure. Optimally, the turbine exhaust pipeline is gradually lowered from the turbine outlet to the inlet of the heat exchanger.

[0031] Preferably, the total heat transfer coefficient of the turbine exhaust pipeline is less than 2000w / (m 2 ·℃). Preferably, the total heat transfer coefficient of the turbine exhaust pipeline should be less than 500w / (m 2 ·℃); Optimally, the total heat transfer coefficient of the turbine exhaust pipeline should be less than 50w / (m 2 ·℃). The turbine exhaust pipe should be fully insulated to minimize the heat exchange between the turbine exhaust and the environment.

[0032] Preferably, the connection structure on the turbine exhaust pipeline should avoid flange connection pipe openings as much as possible. Generally, the number of flange connection pipe openings of the turbine exhaust pipeline should be less than 10; preferably, the number of flange connection pipe openings of the turbine exhaust pipeline should be less than 5; optimally, the number of flange connection pipe openings of the turbine exhaust pipeline should be less than 3.

[0033] The present invention utilizes turbine exhaust steam to heat the cold side logistics through heat exchange equipment, and to meet the requirements, it is necessary to control the temperature and flow rate of the turbine exhaust steam outlet, the size of the turbine exhaust steam pipeline and the total heat transfer coefficient. The above factors work together to achieve good low-temperature heat energy recovery of the turbine exhaust steam.

[0034] Due to the leakage of the sealing surface in the negative pressure operating system, the heat exchange device of the present invention can be equipped with a vacuum device to remove the non-condensable gas in the device to ensure the condensation heat exchange effect in the heat exchange device.

[0035] Compared with the prior art, the advantages of the present invention are as follows: the present invention utilizes turbine exhaust steam to heat the cold side logistics through heat exchange equipment, and designs and selects a steam turbine with a suitable back pressure so that the temperature of turbine exhaust steam meets the heat exchange requirements of users with heat demand, so that the two can be coupled for heat exchange, saving the consumption of cold energy such as circulating water of public works and the consumption of heat energy such as steam and warm water;

[0036] The present invention recycles and utilizes turbine exhaust steam as a low-temperature heat source. On the one hand, it has a significant energy-saving effect, and on the other hand, it can save investment in heat exchange equipment. More importantly, it can obtain significant benefits in the rational use of energy levels: it realizes the same-level utilization of turbine exhaust steam, while saving high-grade energy such as higher-energy-level steam or eliminating other heating systems such as warm water, thereby greatly reducing the energy consumption and investment costs of the device, which is of great significance for energy conservation and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to the accompanying drawings.

[0039] like Figure 1 As shown, the device for directly recovering turbine exhaust waste heat of the present invention comprises:

[0040] A steam turbine 1, with a steam pipeline 4 for steam input connected to the front side, for providing a place for steam to do work;

[0041] A turbine exhaust pipeline 5, the inlet of which is connected to the exhaust end of the steam turbine 1;

[0042] The heat exchange device 2 is used for exchanging heat with steam, and the inlet is connected to the outlet of the turbine exhaust pipeline 5;

[0043] A condensate pump 3 is arranged downstream of the heat exchange device 2, the inlet of which is connected to the outlet of the heat exchange device 2 through a pump inlet condensate pipeline 6, and the outlet is connected to a pump outlet condensate pipeline 7;

[0044] A heat exchange equipment cold side inlet pipeline 8 connected to the cold side inlet of the heat exchange equipment 2; and

[0045] The heat exchange equipment cold side outlet pipeline 9 is connected to the cold side outlet of the heat exchange equipment 2;

[0046] There are multiple detectors, each used to detect the temperature, pressure and flow rate of the fluid in each pipeline;

[0047] Valves, which are multiple and are respectively arranged on each pipeline to control the flow of each pipeline;

[0048] The controller is connected with the detector and the valve electrical signal, and is used to adjust the flow rate of the turbine exhaust steam and thus adjust the back pressure of the steam turbine.

[0049] In this embodiment, temperature T / °C, pressure P / MPaA, flow rate F / (kg / h), and enthalpy value H / (kJ / kg) are defined, where for a medium of a certain phase, the enthalpy value H is a function of temperature T and pressure P, then:

[0050] Steam information in steam line 4: gas phase, T4, P4, F4, H4;

[0051] Exhaust information of turbine outlet in turbine exhaust line 5: saturated gas phase, T51, P51, F51, H51;

[0052] Exhaust information at the inlet of the heat exchange equipment in turbine exhaust pipeline 5: saturated gas phase, T52, P52, F52, H52;

[0053] Pump inlet condensate pipeline 6 pump inlet condensate information: liquid phase, T6, P6, F6, H6;

[0054] Pump outlet condensate pipeline 7 pump outlet condensate information: liquid phase, T7, P7, F7, H7;

[0055] Medium information in the cold side inlet pipeline 8 of the heat exchange equipment: phase state is not limited, T8, P8, F8, H8;

[0056] Medium information in the cold side outlet pipeline 9 of the heat exchange equipment: phase state is not limited, T9, P9, F9, H9;

[0057] The output power of the steam turbine 1 is F4×H4 - F51×H51, and this value is given by the external demand of the device.

[0058] In the heat exchange equipment 2, the exhaust steam of the turbine exchanges heat with the cold side medium. The increased enthalpy value of the cold side medium is equal to the decreased enthalpy value of the condensation of the turbine exhaust steam. The turbine exhaust steam needs to meet the heat load demand of the heat exchange equipment, F8×(H9 - H8) = F4×(H4 - H5), where F8×(H9 - H8) is given by the external demand of the device.

[0059] The hot side inlet temperature of the heat exchange equipment 2 is higher than the cold side outlet temperature, that is, T52 > T9. The hot side inlet temperature is determined by the turbine back pressure, that is, the pressure of the exhaust steam. When the temperature of the turbine exhaust steam increases, considering that the steam conditions (temperature, pressure, etc.) and the output power at the turbine inlet remain unchanged, the steam consumption required by the turbine will increase. At the same time, higher requirements will be put forward for the mechanical design of the turbine. Therefore, T51 and T52 should not be too high.

[0060] 0.01°C < T52 - T9 < 200°C, 0.01°C < T52 - T8 < 220°C, where T8 and T9 are given by the external demand of the device. Preferably, 5°C < T52 - T9 < 50°C, 10°C < T52 - T8 < 50°C; optimally, 10°C < T52 - T9 < 20°C, 10°C < T52 - T8 < 20°C.

[0061] The size of the turbine exhaust pipe 5 should satisfy (P51-P52) <100kPa, (T51-T52) <100°C. Preferably, the size of the turbine exhaust pipe 5 should satisfy (P51-P52) <20kPa, (T51-T52) <20°C; optimally, the size of the turbine exhaust pipe 5 should satisfy (P51-P52) <3kPa, (T51-T52) <3°C. The size of the turbine exhaust pipe 5 should be reasonably determined to meet the requirements of minimizing the pressure drop (P51-P52) and the temperature drop (T51-T52). On the one hand, the larger the size, the larger the flow area and the smaller the pressure drop (P51-P52); on the other hand, the larger the size, the larger the heat exchange area and the larger the temperature drop (T51-T52). For a determined flow rate, pipe length, and total heat transfer coefficient, the above parameters of the present invention can be used to obtain the best energy-saving effect.

[0062] The straight-line distance between the steam turbine 1 and the heat exchange equipment 2 is not greater than 10 km, and the length of the turbine exhaust pipeline 5 is not greater than 20 km. Preferably, the straight-line distance between the two should not be greater than 1 km, and the length of the connected pipeline should not be greater than 2 km; optimally, the straight-line distance between the two should not be greater than 0.5 km, and the length of the connected pipeline should not be greater than 1 km. Since turbine exhaust generally has the characteristics of high vacuum, higher than ambient temperature and large mass flow, the volume flow of turbine exhaust is very large, resulting in a very large size of the turbine exhaust pipeline; at the same time, from a process technology perspective, the pressure drop (P51-P52) and temperature drop (T51-T52) of the turbine exhaust pipeline are required to be as small as possible to reduce heat energy loss. Therefore, the steam turbine and heat exchange equipment are arranged as close as possible, and the turbine exhaust pipeline should also be as short as possible.

[0063] The turbine outlet of the turbine exhaust pipeline 5 is higher than the inlet of the heat exchange device 2. The turbine exhaust pipeline 5 needs to fully consider the influence of the accumulated liquid formed by the condensation of the turbine exhaust. Generally, the turbine exhaust pipeline should not have a bag shape (that is, the lowest point of the turbine exhaust pipeline is lower than the turbine outlet and the inlet of the heat exchange device). If the turbine exhaust pipeline has a bag shape, a drainage facility must be installed at the lowest point. The present invention preferably adopts the above structure. Optimally, the turbine exhaust pipeline is gradually lowered from the turbine outlet to the inlet of the heat exchange device.

[0064] The total heat transfer coefficient of turbine exhaust pipe 5 is less than 1000w / (m 2 ·℃). Preferably, the total heat transfer coefficient of the turbine exhaust pipe 5 should be less than 500w / (m 2 ·℃); Optimally, the total heat transfer coefficient of the turbine exhaust pipeline should be less than 50w / (m 2·℃). The turbine exhaust pipe should be fully considered for insulation to minimize the heat exchange between the turbine exhaust and the environment. The connection structure on the turbine exhaust pipe 5 is welded. Flange connection pipe openings should be avoided as much as possible. Generally, the number of flange connection pipe openings of the turbine exhaust pipe should be less than 10; preferably, the number of flange connection pipe openings of the turbine exhaust pipe should be less than 5; optimally, the number of flange connection pipe openings of the turbine exhaust pipe should be less than 3.

[0065] The structure and recovery information of the present invention are further explained by taking the following given parameters of external demand as an example: the output power of the steam turbine 1 is 43400kw; the medium information in the cold side inlet pipeline 8 of the heat exchange equipment 2 is T8=58.6℃, P8=1.94MPaA, F8=1860046kg / h; the medium information in the cold side outlet pipeline 9 of the heat exchange equipment 2 is T9=58.6, P9=1.92MPaA, F8=1860046kg / h; the heat load of the heat exchange equipment 2 is 70.19MW.

[0066] Embodiment 1:

[0067] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 134500 kg / h, H4 = 3377 kJ / kg; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 is gradually lowered from the turbine outlet to the heat exchange equipment inlet; the size of turbine exhaust pipeline 5 is DN2500; there are 2 flange connections on turbine exhaust pipeline 5 ; According to the output power of steam turbine 1 is 43400kw, that is, F4×H4-F51×H51=43400kw, where F51=F4=134500kg / h, it can be obtained that H51=2216kJ / kg, for saturated steam, it can be known that the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA; the total heat transfer coefficient of the connected pipeline is 0.05w / (m 2 ·℃), the heat loss is about 2.1mw (ambient temperature is 15℃), F52=F51=134500kg / h, H52=2157.5kJ / kg, the exhaust information of the heat exchange equipment inlet in the turbine exhaust pipeline 5 is T52=70.0℃, P52=0.031MPaA, which satisfies (P51-P52)<3kPa, (T51-T52)<3℃.

[0068] The output power of steam turbine 1 is 43400kw, which meets the requirements; the heat exchange equipment 2 operates normally, the heat exchange effect is good, and the heat load is 70.19MW.

[0069] Comparative Example 1:

[0070] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 124700 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 is gradually reduced from the turbine outlet to the heat exchange equipment inlet; the total heat transfer coefficient of the turbine exhaust pipeline 5 is less than 50w / (m 2 ·℃); the size of turbine exhaust pipeline 5 is DN2500; there are two flange connection ports on turbine exhaust pipeline 5; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=54.1℃, P51=0.015MPaA, F51=124700kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=54.0℃, P52=0.015MPaA, F52=124700kg / h.

[0071] The output power of steam turbine 1 is 43400kw, which meets the requirements; however, since the turbine exhaust back pressure is too low and the exhaust temperature is lower than the temperature of the heat demanding user, heat exchange cannot be carried out.

[0072] Comparative Example 2:

[0073] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 125200 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 is gradually reduced from the turbine outlet to the heat exchange equipment inlet; the total heat transfer coefficient of the turbine exhaust pipeline 5 is less than 50w / (m 2 ·℃); the size of turbine exhaust pipeline 5 is DN2500; there are 2 flange connection ports on turbine exhaust pipeline 5; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA, F51=125200kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=70.0℃, P52=0.031MPaA, F52=125200kg / h.

[0074] The output power of steam turbine 1 is 40400kw, which does not meet the requirements; the heat exchange equipment 2 operates normally and the heat exchange effect is good, but the heat load is 66.88MW, which does not meet the requirements.

[0075] Comparative Example 3:

[0076] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 134500 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 11000 m, and the distance between the connected pipelines is 21000 m; the turbine exhaust pipeline 5 is gradually reduced from the turbine outlet to the heat exchange equipment inlet; the total heat transfer coefficient of turbine exhaust pipeline 5 is less than 50w / m 2·℃; the size of turbine exhaust pipeline 5 is DN2500; there are 2 flange connection ports on turbine exhaust pipeline 5; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA, F51=134500kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=33℃, P52=0.005MPaA, F52=134500kg / h.

[0077] The output power of steam turbine 1 is 43400kw, which meets the requirements; due to the excessive resistance drop of turbine exhaust pipeline 5 and excessive heat dissipation, the inlet temperature of heat exchange equipment 2 is too low and heat exchange cannot be carried out.

[0078] Comparative Example 4:

[0079] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 134500 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 has a bag shape and no drainage facilities; the total heat transfer coefficient of the turbine exhaust pipeline 5 is less than 50w / (m 2 ·℃); the size of turbine exhaust pipeline 5 is DN2500; there are two flange connection ports on turbine exhaust pipeline 5; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA, F51=134500kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=70℃, P52=0.018MPaA, F52=134500kg / h.

[0080] The output power of steam turbine 1 is 43400kw, which meets the requirements; because the turbine exhaust pipeline 5 is bag-shaped and has no drainage facilities, water hammer occurs, causing safety hazards, and the turbine exhaust pressure drop increases, the heat exchange effect of heat exchange equipment 2 is poor, and the heat load does not meet the requirements.

[0081] Comparative Example 5:

[0082] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 134500 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 is gradually reduced from the turbine outlet to the heat exchange equipment inlet; the total heat transfer coefficient of the turbine exhaust pipeline 5 is greater than 1000 w / (m 2·℃); the size of turbine exhaust pipeline 5 is DN2500; there are two flange connection ports on turbine exhaust pipeline 5; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA, F51=134500kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=33.0℃, P52=0.005MPaA, F52=134500kg / h.

[0083] The output power of steam turbine 1 is 43400kw, which meets the requirements; due to excessive heat dissipation of turbine exhaust pipeline 5, the inlet temperature of heat exchange equipment 2 is too low and heat exchange cannot be carried out.

[0084] Comparative Example 6:

[0085] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 134500 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 is gradually reduced from the turbine outlet to the heat exchange equipment inlet; the total heat transfer coefficient of turbine exhaust pipeline 5 is less than 50w / (m 2 ·℃); the size of turbine exhaust pipeline 5 is DN500; there are two flange connection ports on turbine exhaust pipeline 5; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA, F51=134500kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=70.0℃, P52=0.012MPaA, F52=134500kg / h.

[0086] The output power of steam turbine 1 is 43400kw, which meets the requirements; due to the excessive resistance drop of turbine exhaust pipeline 5, the heat exchange effect of heat exchange equipment 2 is poor and the heat load does not meet the requirements.

[0087] Comparative Example 7:

[0088] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 134500 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 is gradually reduced from the turbine outlet to the heat exchange equipment inlet; the total heat transfer coefficient of turbine exhaust pipeline 5 is less than 50w / (m 2·℃); the size of turbine exhaust pipeline 5 is DN10000; there are two flange connection ports on turbine exhaust pipeline 5; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA, F51=134500kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=63.1℃, P52=0.023MPaA, F52=134500kg / h.

[0089] The output power of steam turbine 1 is 43400kw, which meets the requirements; due to excessive heat dissipation of turbine exhaust pipeline 5, the heat exchange effect of heat exchange equipment 2 is poor and the heat load does not meet the requirements.

[0090] Comparative Example 8:

[0091] The steam information in steam pipeline 4 is T4 = 506 ° C, P4 = 11.1 MPaA, F4 = 134500 kg / h; the straight-line distance between steam turbine 1 and heat exchange equipment 2 is 50 m, and the distance between the connected pipelines is 100 m; the turbine exhaust pipeline 5 is gradually reduced from the turbine outlet to the heat exchange equipment inlet; the total heat transfer coefficient of turbine exhaust pipeline 5 is less than 50w / (m 2 ·℃); the size of turbine exhaust pipeline 5 is DN2500; there are 15 flange connection ports on turbine exhaust pipeline 5, and no vacuum equipment is provided; the exhaust information of turbine outlet in turbine exhaust pipeline 5 is T51=70.2℃, P51=0.032MPaA, F51=134500kg / h; the exhaust information of heat exchange equipment inlet in turbine exhaust pipeline 5 is T52=63.0℃, P52=0.058MPaA, F52=134500kg / h.

[0092] The output power of steam turbine 1 is 43400kw, which meets the requirements; due to too many flange connection ports on turbine exhaust pipeline 5, air leaks into turbine exhaust pipeline 5, seriously affecting the heat exchange effect of heat exchange equipment 2, and the heat load does not meet the requirements.

[0093] It can be seen from the comparative data of Example 1 of the present invention and Comparative Examples 1 to 8 that in order to utilize turbine exhaust steam to heat the cold side logistics through the heat exchange equipment and meet the requirements, it is necessary to control the pressure and flow rate of the turbine exhaust steam outlet, the size and layout of the turbine exhaust steam pipeline and the overall heat transfer coefficient and other factors. The above factors work together to achieve the low-temperature heat energy recovery of the turbine exhaust steam as planned.

Claims

1. A device for directly recovering waste heat from turbine exhaust steam, characterized in that Including: A steam turbine, with a steam pipeline for steam input connected to the front side, which is used to provide a place for steam to do work; A turbine exhaust pipeline, the inlet of which is connected to the exhaust end of the steam turbine; A heat exchange device, which is used to exchange heat for steam, and the inlet of which is connected to the outlet of the turbine exhaust pipeline; A condensate pump, which is arranged downstream of the heat exchange device, the inlet of which is connected to the outlet of the heat exchange device through a pump inlet condensate pipeline, and the outlet of which is connected to a pump outlet condensate pipeline; A heat exchange device cold side inlet pipeline, which is connected to the cold side inlet of the heat exchange device; And A heat exchange device cold side outlet pipeline, which is connected to the cold side outlet of the heat exchange device; Detectors, which are multiple and are respectively used to detect the temperature, pressure and flow rate of the fluid in each pipeline; Valves, which are multiple and are respectively arranged on each pipeline and are used to control the flow rate of each pipeline; A controller, which is electrically connected to the detectors and valves and is used to adjust the back pressure of the steam turbine; Defining temperature T / ℃, pressure P / MPaA, flow rate F / (kg / h), enthalpy value H / (kJ / kg), then Steam information in the steam pipeline: gas phase, T4, P4, F4, H4; Turbine outlet exhaust information in the turbine exhaust pipeline: saturated gas phase, T51, P51, F51, H51; Heat exchange device inlet exhaust information in the turbine exhaust pipeline: saturated gas phase, T52, P52, F52, H52; Pump inlet condensate information in the pump inlet condensate pipeline: liquid phase, T6, P6, F6, H6; Pump outlet condensate information in the pump outlet condensate pipeline: liquid phase, T7, P7, F7, H7; Medium information in the heat exchange device cold side inlet pipeline: phase state not limited, T8, P8, F8, H8; Medium information in the heat exchange device cold side outlet pipeline: phase state not limited, T9, P9, F9, H9; The output power of the steam turbine is F4×H4 - F51×H51, and this value is given by the external demand of the device; The turbine exhaust exchanges heat with the cold side medium, and the increased enthalpy value of the cold side medium is equal to the reduced enthalpy value of the condensation of the turbine exhaust. The turbine exhaust needs to meet the heat load demand of the heat exchange device, F8×(H9 - H8) = F4×(H4 - H5), where F8×(H9 - H8) is given by the external demand of the device; 0.01℃ < T52 - T9 < 200℃, 0.01℃ < T52 - T8 < 220℃, where T8 and T9 are given by the external demand of the device; The selection of the size of the turbine exhaust pipeline should meet (P51 - P52) < 100 kPa, (T51 - T52) < 100℃; The straight-line distance between the steam turbine and the heat exchange device is not more than 10 km, and the length of the turbine exhaust pipeline is not more than 20 km; The total heat transfer coefficient of the turbine exhaust pipeline is less than 2000w / (m 2 ·℃).

2. The device for directly recovering waste heat from turbine exhaust steam according to claim 1, characterized in that: The hot side inlet temperature of the heat exchange device is higher than the cold side outlet temperature, that is, T52 > T9.

3. The device for directly recovering waste heat from turbine exhaust steam according to claim 1 or 2, characterized in that: The turbine outlet of the turbine exhaust pipeline is not lower than the inlet of the heat exchange device.

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