Deep utilization method and system for waste heat of exhaust smoke of whole plant

Abstract

The invention belongs to the field of energy conservation and consumption reduction of a gas boiler heat supply gas turbine power plant. The current gas-fired boiler adopts thermal deoxidization to control water supply and oxygen dissolution, water is supplied to a deaerator from an outlet of a secondary energy saver, the smoke exhaust temperature is about 60 DEG C, and waste heat is not fully utilized. Therefore, a novel pipeline system is constructed, a traditional heat exchange process is subverted, and exhaust smoke waste heat is utilized to the maximum extent through multiple heat exchange. The system comprises two sets of schemes adaptive to different operation states, and the schemes can be flexibly switched. When the gas-fired boiler runs, water supplied from an outlet of the secondary energy saver is led to the double-tube heat exchanger of the pressure regulating station, and returns to the primary energy saver after heat exchange to replace a water bath furnace to heat natural gas, so that the heating effect is guaranteed, gas is saved, and the water temperature of an inlet of the primary energy saver is reduced. When the gas turbine runs, one path of feed water is led to the double-tube heat exchanger from the low-pressure feed water secondary heater, and the feed water returns to the condenser after heat exchange, so that the gas consumption of the water bath furnace in low-temperature climate is saved, and more smoke exhaust waste heat is utilized in other climate. The two modes both can reduce the exhaust gas temperature, and are efficient in utilization, energy-saving, emission-reducing, green and environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of energy saving and consumption reduction of gas turbine power plant equipped with gas-fired boiler heating, in particular to a method and system for deep utilization of exhaust flue gas waste heat of the whole plant. BACKGROUND

[0002] At present, there is a certain degree of exhaust flue gas waste heat loss in the current operation mode of all gas-fired boilers and waste heat boilers of gas turbine power plants. During the operation of the gas-fired boiler, the method of thermal deaeration is generally adopted to control the dissolved oxygen of the feed water, and the method for reducing the exhaust flue gas temperature is to reform the feed water system, that is, to expand the capacity of the coal economizer or to add a set of secondary economizer. The feed water at the outlet of the secondary economizer flows to the deaerator, and therefore, the low exhaust flue gas waste heat is not fully utilized.

[0003] At the same time, when the air temperature is low, in order to ensure the temperature of natural gas, a water bath furnace is needed to heat the natural gas, which consumes additional natural gas.

[0004] Therefore, a new type of exhaust flue gas deep utilization system for gas-fired boiler is proposed, which heats through multiple heat exchange modes, maximally utilizes the exhaust flue gas waste heat, and reduces energy loss. In addition, the system after the reform not only improves the utilization rate of exhaust flue gas waste heat, but also reduces the emission of carbon dioxide, which is green and environmentally friendly. SUMMARY

[0005] In view of the above problems, the present application proposes a method and system for deep utilization of exhaust flue gas waste heat of the whole plant to improve the above problems.

[0006] In order to solve the problem that there is a certain degree of exhaust flue gas waste heat loss in the current operation mode of the gas-fired boiler and the gas turbine power plant, a new type of exhaust flue gas deep utilization system for gas-fired boiler is proposed, which performs multiple heat exchange reactions through a new pipeline system, maximally utilizes the exhaust flue gas waste heat, and reduces energy loss.

[0007] To achieve the above purpose, the present application is realized by the following technical scheme:

[0008] A method and system for deep utilization of exhaust flue gas waste heat of the whole plant, the steps are as follows

[0009] 1. An isolation valve is installed on the pipeline after the feed water regulating valve and before the primary economizer.

[0010] 2. An isolation valve is installed after the primary economizer.

[0011] 3. A hole is opened on the pipeline before and after, and a pipeline and a valve are connected, and each is connected with the inlet and outlet pipelines of the pressure regulating station double-pipe heater.

[0012] 4. An isolation valve is installed at the outlet of the secondary economizer.

[0013] 5. A bypass pipe is added to the inlet of the newly installed isolation valve after the water supply regulating valve and before the primary energy economizer, connected to the outlet pipe of the newly installed valve after the primary energy economizer, as a bypass pipe of the primary energy economizer, and an isolation valve is installed on the pipe.

[0014] 6. A pipe is added to the inlet of the newly installed isolation valve after the primary energy economizer, connected to the outlet of the newly installed isolation valve at the outlet of the secondary energy economizer, and an isolation valve is installed on the pipe.

[0015] 7. A pipe is added to the inlet of the newly installed isolation valve at the outlet of the secondary energy economizer, connected to the outlet of the newly installed isolation valve at the primary energy economizer, and an isolation valve is installed on the pipe.

[0016] 8. When the gas boiler is running, the feed water at the outlet of the secondary energy economizer can be introduced to the dual-pipe heat exchanger after the pressure regulating station and returned to the primary energy economizer, replacing the water bath furnace for heating natural gas.

[0017] 9. When the gas turbine is running, a low-pressure feed water is introduced from the low-pressure feed water secondary heater to the dual-pipe heat exchanger at the pressure regulating station, and returned to the condenser after heat exchange, replacing the water bath furnace for heating natural gas.

[0018] The beneficial effects of the present application are:

[0019] (1) By switching the system operation mode, the gas consumption and heat consumption are reduced, and the heating capacity of the gas boiler is increased by 10% compared with the design value, and about 6% compared with the current actual working condition.

[0020] (2) When the gas boiler is running, the gas consumption for heating can be reduced by more than 3 standard cubic meters per ton of steam, and according to the annual heating of 220,000 tons, more than 660,000 cubic meters of natural gas can be saved annually, with an economic benefit of about 2 million yuan.

[0021] (3) When the gas turbine is running, the outlet temperature of the water bath furnace is about 55℃, the heating can increase the temperature of the natural gas by 20℃, and after using the low-pressure feed water at the outlet of the low-pressure feed water heater, the temperature of the natural gas can be increased by more than 25℃, and the exhaust gas temperature of the waste heat boiler can be reduced by more than 2℃, and according to the preliminary calculation of 5000 hours of annual operation, more than 350,000 cubic meters of natural gas can be saved annually, with an economic benefit of about 1 million yuan.

[0022] (4) Using the system for calculation, the annual CO2 emission can be reduced by about 1964.16 tons, which is green and environmentally friendly, and energy-saving and emission-reducing. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0024] Figure 1 The schematic diagram of the overall process proposed by the embodiment of the present application is shown.

[0025] Circulating pump (1), deaerator (2), secondary economizer (3), primary economizer (11), double-pipe heat exchanger (10), condenser (7)

[0026] Figure 2 The schematic diagram of the process part of the gas boiler reconstruction proposed by the embodiment of the present application is shown.

[0027] Circulating pump (1), deaerator (2), secondary economizer (3), primary economizer (11) DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments only constitute some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] Embodiment 1

[0030] The exhaust gas heat deep utilization method and system of the present embodiment has the following steps:

[0031] The main connecting equipment is: #1 gas turbine, condenser (7), feedwater heater (6), double-pipe heat exchanger (10)

[0032] The gas turbine has a unique thermodynamic cycle structure, resulting in high power density. At the same time, due to its small volume, it is relatively light and fast in starting speed. With the assistance of a starter, it can quickly reach the rated speed and be in a high-speed rotating state with a small vibration frequency. Meanwhile, it uses combustible gas, which is clean and convenient compared to coal, and stable and efficient compared to new energy. However, a large amount of intake and exhaust is required during operation.

[0033] Therefore, combined with the actual situation of the factory, the gas boiler adopts a thermal deaeration method to control the oxygen dissolution of the feedwater. After the current system is modified, the feedwater at the outlet of the secondary economizer flows to the primary economizer and then to the deaerator. However, the feedwater temperature is relatively high, which requires the opening of the primary economizer water side bypass valve to reduce the overall temperature of the deaerator, thereby increasing the exhaust gas heat utilization rate.

[0034] During the operation of the gas turbine, a low-pressure feed water is led from a low-pressure feed water primary feed water heater to a dual-tube heat exchanger of a pressure regulating station to heat natural gas and then the return water is returned to a condenser, and the current water bath boiler outlet temperature is about 55 DEG C, and the heating can increase the natural gas temperature by 20 DEG C.

[0035] Example 2

[0036] The smoke exhaust heat deep utilization method and system of the embodiment has the following steps:

[0037] The main connected equipment is: #1 gas boiler, deaerator (2), secondary economizer (3), primary economizer (11), dual-tube heat exchanger (10)

[0038] The gas turbine has a unique thermodynamic cycle structure, resulting in a large power density, and because its volume is much smaller than that of the transmission device rotor, it is relatively light and fast to start, and can quickly reach the rated speed under the assistance of the starter, and is in a high-speed rotating state, and has a small vibration frequency, and uses combustible gas, which is clean and convenient compared with coal, and is stable and efficient compared with new energy. However, a large amount of intake and exhaust is required during work.

[0039] Therefore, combined with the actual situation of the plant, during the operation of the gas turbine, a low-pressure feed water is led from a low-pressure feed water secondary heater to a dual-tube heat exchanger of a pressure regulating station, and then returned to a primary economizer after heat exchange, and the exhaust heat is absorbed again.

[0040] During the operation of the gas boiler, the desalted water is flowed into the secondary economizer by the newly added valve and the circulating pump, and the desalted water is heat-exchanged with the exhaust heat, and the temperature is about 38-40 DEG C.

[0041] During the operation of the gas boiler, the desalted water flowed into the secondary economizer is heat-exchanged with the desalted water in the dual-tube heat exchanger, and the outlet temperature can reach 20-25 DEG C.

[0042] During the operation of the gas boiler, the desalted water flowed into the dual-tube heat exchanger is heat-exchanged with the desalted water in the primary economizer, and the outlet temperature can reach 80-100 DEG C.

[0043] During the operation of the gas boiler, the water in the deaerator is finally supplied to the upper drum through the pipeline of the valve (4).

[0044] At the same time, after the low-pressure feed water (water temperature 85 DEG C, water flow 80t / h) at the outlet of the low-pressure economizer 1 of the waste heat boiler is used, the temperature of the natural gas can be increased by more than 25 DEG C, and the exhaust gas temperature of the waste heat boiler can be reduced by more than 2 DEG C. The waste heat of the flue gas is used to replace the water bath furnace of the pressure regulating station to heat the natural gas, and the low-efficiency operation equipment (water bath boiler) is eliminated.

[0045] In summary, the application provides a kind of full plant exhaust gas waste heat deep utilization method and system, theoretically calculate the minimum control exhaust gas temperature under deep utilization of waste heat energy, utilize system redesign and reconstruction to reach maximum utilization of gas boiler and waste heat boiler exhaust gas waste heat energy.

[0046] Example 3

[0047] The exhaust gas waste heat deep utilization method and system of the embodiment are as follows:

[0048] The main connected equipment is: #2 gas turbine, condenser (7), feed water heater (6), double-tube heat exchanger (10)

[0049] The gas turbine has a unique thermodynamic cycle structure, resulting in high power density. At the same time, due to its small volume, it is relatively light and fast in starting speed. With the assistance of a starter, it can quickly reach the rated speed and be in a high-speed rotating state with a small vibration frequency. In addition, it uses combustible gas, which is clean and convenient compared to coal, and stable and efficient compared to new energy. However, a large amount of intake and exhaust is required during operation.

[0050] Therefore, combined with the actual situation of the plant, the gas boiler adopts a thermal deoxidization method to control the oxygen dissolution of the feed water. After the current system is transformed, the feed water at the outlet of the secondary economizer flows to the primary economizer and then to the deoxidizer. However, the feed water temperature is relatively high, which requires the opening of the primary economizer water side bypass valve to reduce the overall temperature of the deoxidizer, thereby increasing the exhaust gas waste heat utilization rate.

[0051] During the operation of the gas turbine, a low-pressure feed water is introduced from the low-pressure feed water primary feed water heater to the pressure regulating station double-tube heat exchanger to heat the natural gas and then back to the condenser. The outlet temperature of the current water bath boiler is about 55 DEG C, and the heating can increase the temperature of the natural gas by 20 DEG C. In summary, the application provides a kind of full plant exhaust gas waste heat deep utilization method and system, theoretically calculate the minimum control exhaust gas temperature under deep utilization of waste heat energy, utilize system redesign to reach maximum utilization of gas boiler and waste heat boiler exhaust gas waste heat energy.

[0052] Example 4

[0053] The preparation method of the pseudo-boehmite / graphene powder of the embodiment is as follows:

[0054] The main connected equipment is: #2 gas boiler, deoxidizer (2), secondary economizer (3), primary economizer (11), double-tube heat exchanger (10)

[0055] Gas turbine due to its unique thermodynamic cycle structure, resulting in high power density, while its volume is much smaller than the transmission device rotor is more lightweight, faster start speed, with the help of the starter can quickly reach the rated speed, in high speed rotation, vibration frequency is small, while the use of flammable gas, compared with coal clean, convenient, compared with new energy stable, efficient. But in the work needs a lot of intake and exhaust.

[0056] Therefore, combined with the actual situation of the factory, when the gas turbine is running, a low-pressure feedwater is led from the low-pressure feedwater secondary heater to the double-pipe heat exchanger of the pressure regulating station, and after heat exchange, it is returned to the primary economizer to absorb the exhaust gas waste heat again.

[0057] When the gas boiler is running, its characteristic is that the desalted water flows into the secondary economizer by the newly added valve and the circulating pump, and the desalted water exchanges heat with the exhaust gas waste heat, and at this time, the temperature is about 45-47 DEG C.

[0058] When the gas boiler is running, its characteristic is that the desalted water heated by flowing into the secondary economizer flows into the double-pipe heat exchanger through the valve, and at this time, the outlet temperature can reach 20-25 DEG C.

[0059] When the gas boiler is running, its characteristic is that the desalted water flowing into the double-pipe heat exchanger flows into the primary economizer through the valve, and the primary economizer is heated again by the exhaust gas waste heat, and at this time, the outlet temperature can reach 80-100 DEG C.

[0060] When the gas boiler is running, finally, the water in the deaerator is supplied to the upper drum through the pipeline of the valve (4).

[0061] When the gas boiler is running, a low-pressure feedwater is led from the low-pressure feedwater primary feedwater heater to the double-pipe heat exchanger of the pressure regulating station, and after heating the natural gas, the water is returned to the condenser, and the current water bath boiler outlet temperature is about 55 DEG C, and the heating can increase the natural gas temperature by 20 DEG C.

[0062] At the same time, after the low-pressure feedwater (water temperature 85 DEG C, water flow 80 t / h) at the outlet of the low-pressure economizer 1 of the waste heat boiler is replaced, the natural gas temperature can be increased by more than 25 DEG C, and the exhaust gas temperature of the waste heat boiler can be reduced by more than 2 DEG C. The exhaust gas waste heat is used to replace the water bath furnace of the pressure regulating station to heat the natural gas, and the low-efficiency operation equipment (water bath furnace) is eliminated.

[0063] In summary, the full-factory exhaust gas waste heat deep utilization method and system provided by the application theoretically calculates the deep utilization of waste heat energy under the minimum control exhaust gas temperature, and the system is redesigned and transformed to maximize the utilization of exhaust gas waste heat energy of the gas boiler and the waste heat boiler.

[0064] Comparative Example 1

[0065] The main connecting equipment is: #1 gas boiler, deaerator (2), first energy-saving device (11), double-tube heat exchanger (10)

[0066] The gas turbine has a unique thermodynamic cycle structure, resulting in high power density. At the same time, due to its volume being much smaller than the transmission device rotor, it is relatively light and fast to start. With the assistance of the starter, it can quickly reach the rated speed and be in a high-speed rotating state with a small vibration frequency. Meanwhile, it uses combustible gas, which is clean and convenient compared to coal, and stable and efficient compared to new energy. However, a large amount of intake and exhaust is required during work.

[0067] In the traditional system construction process

[0068] When the gas boiler is running, the characteristic is that the desalted water flowing into the deaerator water tank exchanges heat with the heat source, thereby providing additional heat value for thermal deaeration.

[0069] When the gas boiler is running, the characteristic is that the desalted water flowing into the deaerator through thermal deaeration is flowed into the first energy-saving device through the valve for heat exchange, and the outlet temperature can reach 80-100℃ at this time.

[0070] When the gas boiler is running, the characteristic is that the water in the deaerator is finally supplied to the upper drum through the pipeline of the valve (4) by the feed water pump.

[0071] Comparative Example 2

[0072] The main connecting equipment is: #2 gas boiler, deaerator (2), first energy-saving device (11), double-tube heat exchanger (10)

[0073] The gas turbine has a unique thermodynamic cycle structure, resulting in high power density. At the same time, due to its volume being much smaller than the transmission device rotor, it is relatively light and fast to start. With the assistance of the starter, it can quickly reach the rated speed and be in a high-speed rotating state with a small vibration frequency. Meanwhile, it uses combustible gas, which is clean and convenient compared to coal, and stable and efficient compared to new energy. However, a large amount of intake and exhaust is required during work.

[0074] In the traditional system construction process

[0075] When the gas boiler is running, the characteristic is that the desalted water flowing into the deaerator water tank exchanges heat with the heat source, thereby providing additional heat value for thermal deaeration.

[0076] When the gas boiler is running, the characteristic is that the desalted water flowing into the deaerator through thermal deaeration is flowed into the first energy-saving device through the valve for heat exchange, and the outlet temperature can reach 80-100℃ at this time.

[0077] The gas boiler is characterized in that the water in the deaerator is supplied to the upper drum through the pipeline of the valve (3) by the feed water pump.

[0078] Comparative Example 3

[0079] The main connected devices are: #1 gas boiler, deaerator (2), first energy saver (11), second energy saver (3), double-pipe heat exchanger (10)

[0080] The gas turbine has a unique thermodynamic cycle structure, resulting in high power density. At the same time, due to its small volume, it is relatively light and fast to start, and can quickly reach the rated speed under the assistance of the starter, and is in a high-speed rotating state with small vibration frequency. Meanwhile, it uses combustible gas, which is clean and convenient compared to coal, and stable and efficient compared to new energy. However, a large amount of intake and exhaust is required during operation.

[0081] In the traditional system construction process

[0082] The gas boiler is characterized in that the desalted water flowing into the deaerator is heat exchanged with the heat source after flowing into the deaerator, thereby providing additional heat value for thermal deaeration.

[0083] The gas boiler is characterized in that the desalted water flowing into the deaerator is heat exchanged with the heat source after flowing into the deaerator, thereby providing additional heat value for thermal deaeration.

[0084] The gas boiler is characterized in that the desalted water flowing into the deaerator is heat exchanged with the heat source after flowing into the deaerator, thereby providing additional heat value for thermal deaeration.

[0085] The gas boiler is characterized in that the desalted water flowing into the deaerator is heat exchanged with the heat source after flowing into the deaerator, thereby providing additional heat value for thermal deaeration.

[0086] The gas boiler is characterized in that the desalted water flowing into the deaerator is heat exchanged with the heat source after flowing into the deaerator, thereby providing additional heat value for thermal deaeration.

[0087] Comparative Example 4

[0088] The main connected devices are: #1 gas boiler, deaerator (2), first energy saver (11), second energy saver (3), double-pipe heat exchanger (10)

[0089] Gas turbine has a unique thermodynamic cycle structure, resulting in high power density, and its volume is much smaller than the transmission device rotor, which is relatively light and fast to start. With the help of the starter, it can quickly reach the rated speed and be in a high-speed rotating state with a small vibration frequency. Compared with coal, it is clean and convenient, and compared with new energy, it is stable and efficient. However, a large amount of air intake and exhaust is required during operation.

[0090] In the traditional system construction process

[0091] When the gas-fired boiler is running, the desalted water flowing into the deaerator tank exchanges heat with the heat source, so as to provide additional heat value for thermal deaeration.

[0092] When the gas-fired boiler is running, the desalted water flowing into the deaerator tank exchanges heat with the heat source, so as to provide additional heat value for thermal deaeration.

[0093] When the gas-fired boiler is running, the desalted water flowing into the deaerator tank exchanges heat with the heat source, so as to provide additional heat value for thermal deaeration.

[0094] When the gas-fired boiler is running, the desalted water flowing into the deaerator tank exchanges heat with the heat source, so as to provide additional heat value for thermal deaeration.

[0095] When the gas-fired boiler is running, the desalted water flowing into the deaerator tank exchanges heat with the heat source, so as to provide additional heat value for thermal deaeration.

[0096] Test Example 1

[0097] Through performance test of #1 gas-fired boiler, since the water temperature entering the primary economizer decreases from 102℃ to about 50℃, the average heat release temperature difference of flue gas to feed water increases, the heat absorption of feed water increases, and therefore the exhaust gas temperature decreases, so the benefit cannot be accurately calculated, but specific data can be obtained through experiment for calculation.

[0098] The method is as follows, that is, under the current operation mode, the deaerator heating is turned off, the parameters of the gas-fired boiler during operation are recorded, and the heating gas consumption is calculated and compared with that when the heating is not turned off. The gas-fired boiler heat rate is calculated by the positive balance method

[0099]

[0100] Wherein, η: boiler thermal efficiency, Q output : boiler effective output energy (kJ / h), Q input : total heat input of boiler (kJ / h), Q doubleThe double-pipe heat exchanger output energy (kJ / h), since other parameters remain unchanged, through the new system to the boiler for new combustion, through the calculation of the gas boiler thermal efficiency of 102 %.

[0101] Test Example 2

[0102] Through the performance test calculation of #1 gas turbine, the natural gas quantity is calculated

[0103]

[0104] x: natural gas quantity (ten thousand square meters), Q: gas turbine running gas consumption (kJ / h), ΔT: temperature rise (℃), C: specific heat capacity of natural gas J (kg / k), LHV: heat value (MJ / m 2 Through the calculation, the annual natural gas saving quantity is 350 thousand square meters.

[0105] Test Example 3

[0106] Through the performance test of #2 gas boiler, since the water temperature entering the primary energy saver is reduced from the original 100℃ to about 47℃, the average heat release temperature difference of flue gas to feed water is increased, the heat absorption of feed water is increased, so the exhaust gas temperature is also reduced. Although the benefit cannot be accurately calculated, specific data can be obtained through the experiment for calculation.

[0107] The method is as follows, that is, under the current operation mode, the deaerator heating is withdrawn, the parameters of the gas boiler during operation are recorded, and the heating gas consumption is calculated. Compared with the heating gas consumption without withdrawing the heating operation, the gas boiler thermal efficiency is calculated by the normal balance method, wherein η: boiler thermal efficiency, Q output Boiler effective output energy (kJ / h), Q input Boiler total input heat (kJ / h), Q double The double-pipe heat exchanger output energy (kJ / h), since other parameters remain unchanged, through the new system to the boiler for new combustion, through the calculation of the gas boiler thermal efficiency of 102 %.

[0108] Test Example 4

[0109] Through the performance test calculation of #2 gas turbine, the natural gas quantity is calculated 2 Through the calculation, the annual natural gas saving quantity is 32 million square meters.

[0110] Test Example 5

[0111] The performance test experiment of the gas boiler is carried out, the heat efficiency of the gas boiler is calculated by using the counterbalance method, the combustion performance of the boiler is analyzed, the sum of each heat loss is determined, and then the boiler efficiency is obtained, and the obtained result is the gross efficiency of the boiler.

[0112] It is found by calculation that the heat loss of flue gas is the largest among each heat loss. The heat loss of flue gas of the first gas boiler is 4.47%. The heat loss by radiation is related to the load of the gas boiler, the higher the load of the boiler, the smaller the proportion of the heat loss by radiation, and the heat loss by radiation of the first gas boiler is 1.17%. The content of CO in the flue gas of the gas boiler is 0.00%, so the incomplete combustion heat loss of gas is 0.00%. The fuel of the gas boiler is natural gas, and no ash is produced in the combustion process, so the incomplete combustion heat loss of solid and the physical heat loss of ash are both 0.00%. Finally, the heat efficiency of the gas boiler is 94.36%.

[0113] Test Example 6

[0114] The performance test experiment of the gas boiler is carried out, the heat efficiency of the gas boiler is calculated by using the counterbalance method, the combustion performance of the boiler is analyzed, the sum of each heat loss is determined, and then the boiler efficiency is obtained, and the obtained result is the gross efficiency of the boiler.

[0115] It is found by calculation that the heat loss of flue gas is the largest among each heat loss. The heat loss of flue gas of the first gas boiler is 4.47%. The heat loss by radiation is related to the load of the gas boiler, the higher the load of the boiler, the smaller the proportion of the heat loss by radiation, and the heat loss by radiation of the first gas boiler is 1.17%. The content of CO in the flue gas of the gas boiler is 0.00%, so the incomplete combustion heat loss of gas is 0.00%. The fuel of the gas boiler is natural gas, and no ash is produced in the combustion process, so the incomplete combustion heat loss of solid and the physical heat loss of ash are both 0.00%. Finally, the heat efficiency of the gas boiler is 94.36%.

[0116] Test Example 7

[0117] The performance test experiment of the gas boiler is carried out, the heat efficiency of the gas boiler is calculated by using the counterbalance method, the combustion performance of the boiler is analyzed, the sum of each heat loss is determined, and then the boiler efficiency is obtained, and the obtained result is the gross efficiency of the boiler.

[0118] Through calculation, it is found that the flue gas heat loss is the largest one among all the heat losses. The flue gas heat loss of the No. 1 gas boiler is 3.89%. The heat loss by radiation is related to the load of the gas boiler, and the higher the load of the boiler, the smaller the proportion of the heat loss by radiation. The heat loss by radiation of the No. 1 gas boiler is 0.73%. The content of CO in the flue gas of the gas boiler is all 0.00%, so the incomplete combustion heat loss of gas is all 0.00%. The fuel of the gas boiler is natural gas, and no ash is produced in the combustion process, so the incomplete combustion heat loss of solid and the physical heat loss of ash are both 0.00%. Finally, the thermal efficiency of the gas boiler is 96.47%.

[0119] Test Example 8

[0120] Through the performance test of the gas boiler, the thermal efficiency of the gas boiler is calculated by using the counterbalance method, the combustion performance of the boiler is analyzed, the sum of all the heat losses is determined, and then the boiler efficiency is obtained. The obtained result is the gross efficiency of the boiler.

[0121] Through calculation, it is found that the flue gas heat loss is the largest one among all the heat losses. The flue gas heat loss of the No. 2 gas boiler is 4.44%. The heat loss by radiation is related to the load of the gas boiler, and the higher the load of the boiler, the smaller the proportion of the heat loss by radiation. The heat loss by radiation of the No. 2 gas boiler is 0.71%. The content of CO in the flue gas of the gas boiler is all 0.00%, so the incomplete combustion heat loss of gas is all 0.00%. The fuel of the gas boiler is natural gas, and no ash is produced in the combustion process, so the incomplete combustion heat loss of solid and the physical heat loss of ash are both 0.00%. Finally, the thermal efficiency of the gas boiler is 95.54%.

[0122] In the description of the present application, it should be noted that the calculation of the present application is all supported by actual corresponding production data.

[0123] At the same time, the system description should be understood in a broad sense. For example, "valves" are collectively referred to as specific "shutoff valves", "regulating valves", "check valves", etc. according to function; "ball valves", "butterfly valves", "stop valves", etc. according to structure; "hand-operated valves", "electrically-operated valves", etc. according to driving mode. For those skilled in the art, the specific meanings of the above-mentioned terms in the present application can be understood according to specific circumstances.

[0124] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method and system for deep utilization of flue gas waste heat in a plant, characterized in that, The steps are as follows: (1) When the gas-fired boiler is running, the secondary economizer outlet feed water can be introduced to the double-tube heat exchanger of the pressure regulating station and then returned to the primary economizer, using the flue gas waste heat to replace the water bath furnace to heat the natural gas; (2) The double-tube heat exchanger returns to the primary economizer and then enters the deaerator, reducing the secondary economizer inlet flue gas temperature and ultimately reducing the exhaust gas temperature; (3) When the gas turbine is running, a low-pressure feed water is introduced from the low-pressure feed water secondary heater to the double-tube heat exchanger of the pressure regulating station, and after heat exchange, it is returned to the primary economizer, using the flue gas waste heat to replace the water bath furnace to heat the natural gas.

2. The method and system for deep utilization of flue gas waste heat of the whole plant according to claim 1, wherein the main connected equipment is: a deaerator (2), a secondary economizer (3), a primary economizer (11), and a double-tube heat exchanger (10).

3. A method and system for full-plant flue gas exhaust heat deep utilization according to claim 1, wherein when the gas boiler is in operation, it is characterized in that, The desalted water is introduced into the secondary economizer by the newly added valve and the circulating pump, and the desalted water is heat exchanged with the flue gas waste heat, at this time the temperature is about 38-40℃.

4. The method and system for full plant flue gas waste heat deep utilization according to claim 2, wherein when the gas boiler is running, it is characterized in that, The desalted water heated in the secondary economizer is introduced into the primary economizer through the double-tube heat exchanger, and the desalted water is heated again, at this time the outlet temperature can reach 80-100℃.

5. A method and system for the deep utilization of flue gas exhaust heat in a plant according to claim 2, characterized in that, when the gas boiler is in operation, The desalted water heated in the primary economizer is introduced into the deaerator through the valve (1) for thermal deaeration.

6. The method and system for deep utilization of flue gas waste heat of the whole plant according to claim 2, wherein when the gas-fired boiler is running, the water in the deaerator is finally supplied to the upper drum through the pipeline of the valve (4) by the feed water pump.

7. The method and system for deep utilization of flue gas waste heat of the whole plant according to claim 3, wherein when the gas turbine is running, the low-pressure feed water is introduced into the double-tube heat exchanger through the newly added valve to heat the natural gas and returned to the condenser.

8. The method and system for deep utilization of flue gas waste heat according to claim 1.

9. The application of the method and system for deep utilization of flue gas waste heat according to claim 1 in the energy saving and consumption reduction of the gas turbine power plant.

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