Flue gas cooling system and method without changing components

Abstract

The invention discloses a flue gas cooling system without changing components. The flue gas cooling system comprises an exhaust structure, a primary heat exchanger, a cooling medium supply assembly and a cooling medium exhaust pipeline. The exhaust structure is vertically arranged, and flue gas for testing enters from a lower port of the exhaust structure and is exhausted from an upper port of the exhaust structure; the first-stage heat exchanger is arranged in the exhaust structure, the inlet end of the first-stage heat exchanger communicates with the cooling medium supply assembly, and the outlet end of the first-stage heat exchanger communicates with the cooling medium exhaust pipeline. And a cooling medium in the first-stage heat exchanger exchanges heat with flue gas in the exhaust structure. The invention further discloses a flue gas cooling method. The device has the beneficial effects that the heat exchanger arranged in the exhaust structure is used for carrying out heat exchange on flue gas, the flue gas temperature is reduced, a cooling medium in the heat exchanger is not in contact with the flue gas, the components of the flue gas are not changed in the heat exchange process, the infrared characteristics of the flue gas are not influenced, the deviation between a flue gas test and an actual condition is reduced, and the accuracy of a test result is improved.

Description

Technical Field

[0001] The invention relates to the technical field of power system test verification, and in particular to a flue gas cooling method without changing the composition. Background Art

[0002] The flue gas discharged by power units such as diesel engines, gas turbines, and main boilers has the characteristics of high temperature and complex composition. On the one hand, it is easy to produce strong infrared radiation, affecting the infrared stealth of the target; on the other hand, the soot particles, NOx, SOx and other components of the flue gas are easy to cause environmental pollution. Therefore, in recent years, the treatment technology for the flue gas of power units has been continuously developed, and the test technology for flue gas treatment technology is the most reliable means to verify the treatment effect.

[0003] Smoke test technology first needs to generate hot exhaust that can simulate the actual power plant. Generating hot smoke through combustion is a relatively effective technical approach. However, the temperature of the hot smoke generated by combustion is relatively high. On the one hand, it needs to be cooled down, and on the other hand, its composition needs to be ensured not to be changed. Ensuring that its composition remains basically unchanged is an important prerequisite for conducting infrared characteristic tests, flue gas treatment tests, etc. First, because CO2 and H2O in flue gas are the main radiation participating media, they directly determine the strength of infrared radiation. Only ensuring the same temperature without ensuring similar composition will cause the test results to deviate from reality; secondly, when conducting flue gas treatment tests, in order to accurately evaluate the efficiency of flue gas component treatment, the test flue gas is required to be similar to the actual flue gas composition.

[0004] However, the traditional treatment method of spraying water into the flue gas for cooling will significantly increase the concentration of H2O on the one hand, and on the other hand, components such as soot in the flue gas will undergo physical and chemical reactions with water, thereby causing changes in the concentration of corresponding components. This will cause a deviation between the flue gas test and the actual situation, and the test results are not accurate enough. The technology of spraying water for cooling cannot be applied in the above-mentioned application scenarios where the flue gas composition needs to be maintained. Summary of the invention

[0005] The purpose of the present invention is to provide a flue gas cooling method without changing the composition, in view of the shortcomings of the prior art, so as to reduce the deviation between the flue gas test and the actual situation and improve the accuracy of the test results.

[0006] The technical solution adopted by the present invention is: a smoke cooling system without changing the composition, including an exhaust structure, a primary heat exchanger, a cooling medium supply component and a cooling medium discharge pipeline; The exhaust structure is arranged vertically, and the smoke used for the test enters from the lower port of the exhaust structure and is discharged from the upper port of the exhaust structure; The primary heat exchanger is built into the exhaust structure, the inlet end of the primary heat exchanger is connected to the cooling medium supply component, and the outlet end of the primary heat exchanger is connected to the cooling medium discharge pipeline; The cooling medium in the primary heat exchanger exchanges heat with the flue gas in the exhaust structure.

[0007] According to the above scheme, the flue gas cooling system also includes a secondary heat exchanger, which is arranged in the exhaust structure and is located above the primary heat exchanger; the inlet of the secondary heat exchanger is connected to the cooling medium supply component through a pipeline, and the inlet of the secondary heat exchanger is also connected to the outlet of the saturated steam pipeline, the inlet of the saturated steam pipeline is connected to the steam outlet of the steam-water separator, and the inlet of the steam-water separator is connected to the inlet of the cooling medium discharge pipeline; the outlet of the secondary heat exchanger is connected to the superheated steam pipeline.

[0008] According to the above scheme, the cooling medium supply component includes a water tank and a water supply pipeline connected to the water tank, and the water tank is connected to an external water source; a water pump is provided on the water supply pipeline, and the outlet of the water supply pipeline is respectively connected to the inlet of the primary heat exchanger and the secondary heat exchanger.

[0009] According to the above scheme, the water supply pipeline is connected to the saturated steam pipeline through the first branch, and a temperature reduction regulating valve is arranged on the first branch. The cooling water and saturated steam are mixed and then enter the secondary heat exchanger; the water supply pipeline is connected to the inlet of the primary heat exchanger through the second branch.

[0010] According to the above scheme, the water pump is a high-pressure variable frequency water pump. According to the above scheme, the primary heat exchanger and the secondary heat exchanger are both cooling coils arranged vertically, the inlet of the cooling coil is located at the upper end, and the outlet of the cooling coil is located at the lower end.

[0011] According to the above scheme, the lower cooling coil as the first-level heat exchange is arranged in a spiral shape close to the wall of the exhaust structure; the top cooling coil as the second-level heat exchanger is arranged in a mosquito coil shape inside the exhaust structure.

[0012] According to the above solution, the outlet of the superheated steam pipeline is connected to a steam muffler.

[0013] According to the above scheme, temperature sensors are respectively arranged between the primary heat exchanger and the secondary heat exchanger and in the exhaust structure downstream of the secondary heat exchanger.

[0014] The present invention also adopts a flue gas cooling method based on the flue gas cooling system as described above, the method comprising: The flue gas enters the exhaust structure, exchanges heat with the cooling medium in the primary heat exchanger, and after the temperature is reduced, it passes through the secondary heat exchanger. After the flue gas temperature is reduced to the target temperature, it is discharged; When it is detected that the flue gas temperature between the primary heat exchanger and the secondary heat exchanger is higher than the target temperature of the flue gas, the cooling medium flow entering the secondary heat exchanger is adjusted by the water pump. At this time, the calculation formula of the cooling medium flow Q entering the secondary heat exchanger is: Q=B(I p -I by ) / (i ck -i gs ); In the formula, B is the flue gas flow rate, in m³ / s; I p is the detected enthalpy value of the current flue gas, in kJ / m³; I by is the enthalpy value corresponding to the target smoke temperature, in kJ / m³; i ck is the outlet rated steam enthalpy, in kJ / m³; i gs is the inlet water enthalpy, in kJ / m³; When the temperature sensor detects that the flue gas temperature between the primary heat exchanger and the secondary heat exchanger is lower than the target temperature of the flue gas, the cooling medium flow entering the secondary heat exchanger is reduced by the water pump. At this time, the cooling medium flow Q entering the secondary heat exchanger is calculated using the above formula.

[0015] The beneficial effects of the present invention are: 1. The present invention is designed to simulate the actual ship smoke in the tests of infrared characteristics of ship exhaust and smoke treatment. The heat exchanger placed in the exhaust structure is used to exchange heat with the smoke to reduce the smoke temperature. The cooling medium in the heat exchanger does not contact the smoke. The heat exchange process does not change the composition of the smoke and does not affect the infrared characteristics of the smoke. This non-contact cooling technology ensures the similarity of the infrared radiation characteristics of the smoke and the similarity of the smoke pollutants, reduces the deviation between the smoke test and the actual situation, improves the accuracy of the test results, and provides conditions similar to the actual ship for evaluating the performance of infrared characteristics, smoke treatment, etc.

[0016] 2. In the present invention, the saturated steam generated in the primary heat exchanger is mixed with cooling water and enters the secondary heat exchanger to exchange heat with the flue gas again. The cooling water reduces the temperature of the superheated steam, thereby enhancing its heat absorption capacity, thereby further reducing the flue gas temperature and enhancing the ability to regulate the flue gas temperature. The amount of cooling water is adjusted by a temperature reduction regulating valve to reduce the temperature of the superheated steam and also reduce the exhaust noise.

[0017] 3. The present invention utilizes cooling coils as two-stage heat exchangers to exchange heat for flue gas, thereby improving heat exchange efficiency.

[0018] 4. The by-product produced by the present invention is superheated steam, which can be directly discharged into the atmosphere through a steam muffler, or the steam can be used for heating or power generation.

[0019] 5. The flue gas acquisition method of the present invention is based on a two-stage heat exchanger design. According to the determined flue gas target temperature, the difference between the real-time flue gas temperature and the target temperature is used to calculate the cooling water volume, and a water pump is used to adjust it according to the calculation result. This temperature control method is direct and objective, with high adjustment accuracy and high efficiency.

[0020] 6. The flue gas system and method of the present invention are particularly suitable for rapid preparation of test flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a specific embodiment of the present invention.

[0022] Among them: 1-water tank; 2-water pump; 3-exhaust structure; 4-steam-water separator; 5-steam muffler; 6-temperature reduction regulating valve; 7-primary heat exchanger; 8-secondary heat exchanger; 9-supply pipeline; 10-cooling medium discharge pipeline; 11-superheated steam pipeline; 12-saturated steam pipeline; 13-first branch; 14-second branch. DETAILED DESCRIPTION

[0023] In order to better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] like Figure 1 A flue gas cooling system without changing the composition is shown, comprising an exhaust structure 3, a primary heat exchanger 7, a cooling medium supply assembly and a cooling medium discharge pipeline 10; The exhaust structure 3 is arranged vertically, and the smoke used for the test enters from the lower port of the exhaust structure 3, and is discharged from the upper port of the exhaust structure 3 after heat exchange and temperature reduction in the exhaust structure 3; The primary heat exchanger 7 is built into the exhaust structure 3, the inlet end of the primary heat exchanger 7 is connected to the cooling medium supply component, and the outlet end of the primary heat exchanger 7 is connected to the cooling medium discharge pipeline 10; The cooling medium in the primary heat exchanger 7 exchanges heat with the flue gas in the exhaust structure 3 to reduce the temperature of the flue gas; the cooling medium in the primary heat exchanger 7 is heated to become a steam-water mixture.

[0025] In the present invention, the cooling medium supply component supplies cooling medium to the primary heat exchanger 7; the cooling medium is cooling water; and the exhaust structure 3 may be a flue.

[0026] Preferably, the flue gas cooling system also includes a secondary heat exchanger 8, which is arranged in the exhaust structure 3, and the secondary heat exchanger 8 is located above the primary heat exchanger 7; the inlet of the secondary heat exchanger 8 is connected to the cooling medium supply component through a pipeline, and the inlet of the secondary heat exchanger 8 is also connected to the outlet of the saturated steam pipeline 12, the inlet of the saturated steam pipeline 12 is connected to the steam outlet of the steam-water separator 4, and the inlet of the steam-water separator 4 is connected to the inlet of the cooling medium discharge pipeline 10; the outlet of the secondary heat exchanger 8 is connected to the superheated steam pipeline 11.

[0027] In the present invention, the steam-water mixture generated by heating in the primary heat exchanger 7 enters the steam-water separator 4 to separate dry saturated steam, and the saturated steam is mixed with cooling water and enters the secondary evaporator (the amount of cooling water can be adjusted by the temperature reduction regulating valve 6 described later), and exchanges heat with the flue gas in the exhaust structure 3 again to reduce the temperature of the flue gas for the second time; at the same time, the saturated steam in the secondary evaporator is converted into superheated steam and then discharged.

[0028] Preferably, the cooling medium supply assembly includes a water tank 1 and a water supply pipeline connected to the water tank 1, and the water tank 1 is connected to an external water source; a water pump 2 is provided on the water supply pipeline, and the outlet of the water supply pipeline is respectively connected to the inlet of the primary heat exchanger 7 and the secondary heat exchanger 8.

[0029] In the present invention, the water supply pipeline is connected to the saturated steam pipeline 12 through the first branch 13, and a temperature reduction regulating valve 6 is arranged on the first branch 13. The cooling water and the saturated steam are mixed and enter the secondary heat exchanger 8; the water supply pipeline is connected to the inlet of the primary heat exchanger 7 through the second branch 14.

[0030] In the present invention, the water pump 2 is a high-pressure variable frequency water pump 2, which can deliver the required cooling water into the heat exchanger to adjust the temperature of the high-temperature flue gas.

[0031] Preferably, the primary heat exchanger 7 and the secondary heat exchanger 8 are both cooling coils arranged vertically, with the inlet of the cooling coil located at the upper end and the outlet of the cooling coil located at the lower end. The lower cooling coil as the primary heat exchange is arranged in a spiral shape close to the wall of the exhaust structure 3, and cooling water is injected into the cooling coil through the water pump 2, flowing at a high speed in the cooling coil, vaporizing under heat to produce a steam-water mixture, and entering the steam-water separator 4 to separate saturated steam. The top cooling coil as the secondary heat exchanger 8 is arranged in the exhaust structure 3 in a mosquito coil shape, where the saturated steam further absorbs heat and then outputs superheated steam.

[0032] Preferably, the outlet of the superheated steam pipeline 11 is connected to a steam muffler 5 to reduce exhaust noise.

[0033] In the present invention, temperature sensors are respectively arranged between the primary heat exchanger 7 and the secondary heat exchanger 8 and in the exhaust structure 3 downstream of the secondary heat exchanger 8 to detect the flue gas temperature at corresponding positions of the exhaust structure 3.

[0034] A flue gas cooling method based on the flue gas cooling system as described above, the method comprising: The flue gas with an initial temperature of 600°C to 1000°C enters the exhaust structure 3, exchanges heat with the cooling medium in the primary heat exchanger 7, and the flue gas temperature is reduced (the flue gas temperature after the primary cooling is usually 300°C to 700°C). It then passes through the secondary heat exchanger 8, exchanges heat with the cooling medium in the secondary heat exchanger, and the flue gas temperature is reduced to the target temperature before being discharged; After the cooling medium in the primary heat exchanger 7 exchanges heat with the flue gas, the steam-water mixture generates dry saturated steam which is then mixed with cooling water and sent to the secondary heat exchanger 8 to exchange heat with the flue gas to generate superheated steam which is discharged.

[0035] In the present invention, when the temperature sensor detects that the flue gas temperature between the primary heat exchanger 7 and the secondary heat exchanger 8 is higher than the target temperature of the flue gas, the flow rate of the cooling medium entering the secondary heat exchanger 8 is adjusted by the water pump 2. At this time, the calculation formula of the cooling medium flow rate Q entering the secondary heat exchanger 8 is: Q=B(I p -I by ) / (i ck -i gs ); In the formula, B is the flue gas flow rate, in m³ / s; I p is the detected enthalpy value of the current flue gas, in kJ / m³; I by is the enthalpy value corresponding to the target smoke temperature, in kJ / m³; i ck is the outlet rated steam enthalpy, in kJ / m³; i gs is the inlet water enthalpy, in kJ / m³; the above enthalpy values ​​are obtained by looking up relevant tables such as water, water vapor, and flue gas enthalpy temperature.

[0036] When the temperature sensor detects that the flue gas temperature between the primary heat exchanger 7 and the secondary heat exchanger 8 is lower than the target temperature of the flue gas, the cooling medium flow entering the secondary heat exchanger 8 is reduced by the water pump 2. At this time, the cooling medium flow Q entering the secondary heat exchanger 8 is calculated using the above formula.

[0037] When the calculated value obtained by using the above formula is a positive value, it indicates an increase in flow rate; when the calculated value is a negative value, it indicates a decrease in flow rate.

[0038] In the present invention, in order to adjust the superheat of the superheated steam and appropriately control the outlet temperature of the flue gas, the cooling medium in the secondary heat exchanger 8 is controlled by the temperature reduction regulating valve 6, and partially penetrates into the secondary heat exchanger 8 for temperature reduction regulation, so that the flue gas temperature is reduced to close to the target flue gas temperature.

[0039] Example Taking a certain onshore test system as an example, the flue gas cooling system of the present invention is used to cool the test flue gas. The initial temperature of the test flue gas is 1260°C, the target temperature is 550°C; the cooling medium is cooling water, the temperature is about 30°C, and the working pressure is about 3Mpa.

[0040] After the flue gas enters the exhaust structure 3, the cooling water first enters the primary heat exchanger 7 (i.e., the lower cooling coil), and the flue gas temperature is reduced to 769°C through high-temperature convection and radiation heat exchange; the cooling water absorbs the heat of the flue gas and becomes a steam-water mixture, and enters the unheated steam-water separator 4; the steam-water separator 4 outputs 99.5% dry saturated steam after separation; the temperature reduction regulating valve 6 controls the amount of cooling water entering the secondary heat exchanger 8, and after the cooling water amount increases, it is mixed with the dry saturated steam and sent to the secondary heat exchanger 8 (i.e., the upper cooling coil) 8 arranged at the top, and further exchanges heat with the flue gas, and the flue gas temperature is 550°C; then superheated steam is output.

[0041] The device and method described in the present invention utilize a heat exchanger placed in the exhaust structure 3 to exchange heat with the flue gas. The cooling medium in the heat exchanger does not contact the flue gas, and the heat exchange process does not change the composition of the flue gas. At the same time, the by-product generated in the heat exchange process is superheated steam, which can be discharged into the atmosphere through the steam muffler 5 without polluting the environment. The superheated steam can also be sent to the heating system for heating or the steam turbine generator for power generation in application scenarios where waste heat utilization or energy efficiency improvement is required, thereby realizing secondary utilization of energy and reducing carbon emissions.

[0042] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0043] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flue gas cooling system without changing its composition, characterized in that: It includes an exhaust structure, a primary heat exchanger, a cooling medium supply assembly and a cooling medium discharge pipeline; The exhaust structure is arranged vertically, and the smoke used for the test enters from the lower port of the exhaust structure and is discharged from the upper port of the exhaust structure; The primary heat exchanger is built into the exhaust structure, the inlet end of the primary heat exchanger is connected to the cooling medium supply component, and the outlet end of the primary heat exchanger is connected to the cooling medium discharge pipeline; The cooling medium in the primary heat exchanger exchanges heat with the flue gas in the exhaust structure.

2. The flue gas cooling system according to claim 1, characterized in that: The flue gas cooling system also includes a secondary heat exchanger, which is arranged in the exhaust structure and is located above the primary heat exchanger; the inlet of the secondary heat exchanger is connected to the cooling medium supply component through a pipeline, and the inlet of the secondary heat exchanger is also connected to the outlet of the saturated steam pipeline, the inlet of the saturated steam pipeline is connected to the steam outlet of the steam-water separator, and the inlet of the steam-water separator is connected to the inlet of the cooling medium discharge pipeline; the outlet of the secondary heat exchanger is connected to the superheated steam pipeline.

3. The flue gas cooling system according to claim 2, characterized in that: The cooling medium supply assembly includes a water tank and a water supply pipeline connected to the water tank, the water tank is connected to an external water source; a water pump is arranged on the water supply pipeline, and the outlet of the water supply pipeline is respectively connected to the inlet of the primary heat exchanger and the secondary heat exchanger.

4. The flue gas cooling system according to claim 3, characterized in that: The water supply pipeline is connected to the saturated steam pipeline through the first branch. A temperature reduction regulating valve is arranged on the first branch. The cooling water and saturated steam are mixed and then enter the secondary heat exchanger. The water supply pipeline is connected to the inlet of the primary heat exchanger through the second branch.

5. The flue gas cooling system according to claim 3 or 4, characterized in that: The water pump is a high-pressure variable-frequency water pump.

6. The flue gas cooling system according to claim 4, characterized in that: The primary heat exchanger and the secondary heat exchanger are both cooling coils arranged vertically, with the inlet of the cooling coil located at the upper end and the outlet of the cooling coil located at the lower end.

7. The flue gas cooling system according to claim 6, characterized in that: The lower cooling coil as the primary heat exchanger is arranged in a spiral shape close to the wall of the exhaust structure; the top cooling coil as the secondary heat exchanger is arranged in a mosquito coil shape inside the exhaust structure.

8. The flue gas cooling system according to claim 6, characterized in that: The outlet of the superheated steam pipeline is connected with a steam muffler.

9. The flue gas cooling system according to any one of claims 6 to 8, characterized in that: Temperature sensors are respectively arranged between the primary heat exchanger and the secondary heat exchanger and in the exhaust structure downstream of the secondary heat exchanger.

10. A flue gas cooling method based on the flue gas cooling system according to claim 9, characterized in that: The method is: The flue gas enters the exhaust structure, exchanges heat with the cooling medium in the primary heat exchanger, and after the temperature is reduced, it passes through the secondary heat exchanger. After the flue gas temperature is reduced to the target temperature, it is discharged; When it is detected that the flue gas temperature between the primary heat exchanger and the secondary heat exchanger is higher than the target temperature of the flue gas, the cooling medium flow entering the secondary heat exchanger is adjusted by the water pump. At this time, the calculation formula of the cooling medium flow Q entering the secondary heat exchanger is: Q=B(I p -I by ) / (i ck -i gs ); In the formula, B is the flue gas flow rate, in m³ / s; I p is the detected enthalpy value of the current flue gas, in kJ / m³; I by is the enthalpy value corresponding to the target smoke temperature, in kJ / m³; i ck is the outlet rated steam enthalpy, in kJ / m³; i gs is the inlet water enthalpy, in kJ / m³; When the temperature sensor detects that the flue gas temperature between the primary heat exchanger and the secondary heat exchanger is lower than the target temperature of the flue gas, the cooling medium flow entering the secondary heat exchanger is reduced by the water pump. At this time, the cooling medium flow Q entering the secondary heat exchanger is calculated by the above formula.

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