Waste heat recycling system of gas-steam boiler

Abstract

The utility model discloses a waste heat recycling system of a gas-steam boiler, which comprises a softened water supply unit, a flue gas waste heat recycling unit, a pollution discharge waste heat recycling unit and a condensate water waste heat recycling unit, and the soft pollution discharge waste heat recycling unit comprises a first flash tank, a first drain valve group and a continuous heat exchanger. And the first flash tank and the first drain valve group are arranged between the gas-steam boiler and the continuous blowdown expander. According to the utility model, the steam heat recovered by the blowdown waste heat recovery unit is supplied to the thermal deaerator, is treated by the thermal deaerator and then is fed into the gas-steam boiler, so that the feed water temperature of the gas-steam boiler is increased, and the gas consumption of the gas-steam boiler is further reduced; the hot water waste heat of the pollution discharge waste heat recovery unit and the flue gas waste heat recovery unit can heat water in the heat preservation water tank, and the water supply temperature of the gas-steam boiler is increased.

Description

Technical Field

[0001] The utility model relates to the field of waste heat recovery of gas boilers, in particular to a waste heat recovery and utilization system of gas steam boilers. Background Art

[0002] Steam is a special energy medium commonly used in industrial production and civil construction, and it is irreplaceable. Therefore, in order to meet the steam demand of industrial production and civil construction, steam boilers are often used to provide steam. Gas-fired steam boilers are one of the most commonly used steam boilers, but the natural gas consumption ratio of gas-fired steam boilers is relatively high, which directly affects the operating cost and economic benefits of enterprise production, so energy conservation and emission reduction of gas-fired steam boilers are very necessary. At present, the waste heat recovery of gas-fired steam boilers is mainly concentrated on flue gas waste heat recovery. Although this has improved the utilization rate of gas to a certain extent and reduced the gas energy consumption of gas-fired steam boilers, there is still a lot of waste heat waste, and the condensate return pipe of the heat user directly enters the gas-fired steam boiler without any treatment, which is easy to pollute the water in the boiler, thereby affecting the quality of steam. Therefore, it is crucial to further reduce the energy consumption of gas-fired steam boilers on the basis of improving the feed water quality of gas-fired steam boilers. Summary of the invention

[0003] In view of this, the utility model proposes a waste heat recovery and utilization system for a gas steam boiler.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] The waste heat recovery and utilization system of a gas-fired steam boiler described in the utility model comprises a softened water supply unit, a flue gas waste heat recovery unit, and also comprises a sewage waste heat recovery unit and a condensed water waste heat recovery unit. The softened water supply unit has an insulated water tank; the sewage waste heat recovery unit comprises a first flash tank, a first steam trap group and a continuous heat exchanger. The first flash tank and the first steam trap group are arranged between the gas-fired steam boiler and the continuous sewage expansion device. The steam outlet of the first flash tank is connected to the thermal deaerator through the first steam pipeline, and the hot water outlet thereof is connected to the continuous sewage expansion device through the first steam trap group. The continuous sewage expansion device The steam outlet of the deaerator is connected to the thermal deaerator through the second steam pipeline, and the hot sewage connected to the sewage expansion device enters the sewage cooling pool after passing through the continuous heat exchanger; the insulated water tank is connected to the continuous heat exchanger through the first pipeline, and the continuous heat exchanger is connected to the flue gas waste heat recovery unit through the second pipeline, and the hot water outlet of the flue gas waste heat recovery unit is connected to the insulated water tank through the third pipeline; the water supply port of the thermal deaerator is connected to the gas steam boiler through the fourth pipeline, and a boiler feed pump is arranged on the fourth pipeline; the insulated water tank is connected to the thermal deaerator through the fifth pipeline, and a deoxidation pump is arranged on the fifth pipeline near the insulated water tank.

[0006] The beneficial effects are: the utility model utilizes the sewage waste heat recovery unit to supply the recovered steam heat to the thermal deaerator, and after being processed by the thermal deaerator, it is sent to the gas steam boiler, thereby increasing the feed water temperature of the gas steam boiler, and thereby reducing the gas consumption of the gas steam boiler; in addition, the hot water waste heat of the sewage waste heat recovery unit and the flue gas waste heat recovery unit can heat the water in the insulation water tank, further increasing the feed water temperature of the gas steam boiler, further reducing the gas consumption, and reducing energy costs; the condensed water waste heat recovery unit can recover the condensed water waste heat, further improving the thermal utilization efficiency of the gas steam boiler.

[0007] Preferably, the softened water supply unit includes a softened water device, and the water outlet of the softened water device is divided into three routes, the first route is connected to the insulated water tank, the second route is connected to the thermal deaerator via the boiler dosing device, and the third route is connected to the iron remover of the condensed water waste heat recovery unit, which is used for backwashing the iron remover. Beneficial effect: The soft water of the softened water supply unit has three routes, one route enters the insulated water tank, enters the thermal deaerator after being heated by waste heat, and then increases the feed water temperature of the gas steam boiler; one route enters the boiler dosing device to meet the water demand of the boiler dosing device; one route is used for backwashing the iron remover.

[0008] Preferably, the condensate waste heat recovery unit includes a second flash tank and a closed condensate recovery tank, the condensate inlet of the second flash tank is connected to the steam cylinder, and a second steam trap group is provided at the condensate outlet of the steam cylinder; the steam outlet of the second flash tank is connected to the thermal deaerator through a third steam pipeline, and the condensate outlet of the second flash tank is connected to the iron remover through the third steam trap group and the closed condensate recovery tank, and a condensate pump is provided at the water outlet of the closed condensate recovery tank; the iron remover is connected to the thermal deaerator through a sixth pipeline. The beneficial effect is that after the condensate waste heat is recovered, the steam part directly enters the thermal deaerator, and the high-temperature condensate waste heat also enters the thermal deaerator after recovery and iron removal, which increases the feed water temperature of the steam boiler, thereby reducing the natural gas consumption of the gas steam boiler and reducing the production cost.

[0009] Preferably, the steam cylinder is connected to the thermal deaerator through a steam pressure reducing pipeline, and a condensate recovery pipeline is connected in parallel to the pressure reducing valve group of the steam pressure reducing pipeline, the condensate recovery pipeline is connected to the second flash tank, and a fourth steam trap group for allowing hot water to pass is provided on the condensate recovery pipeline.

[0010] The beneficial effect is: since the thermal deaerator requires steam to work, part of the steam in the steam cylinder is allocated to the thermal deaerator, but high-temperature steam condensate is also prone to appear in the pipeline. In order to make full use of the waste heat of this part of the condensate, the utility model also connects it to the second flash tank through the fourth steam trap group to realize the waste heat utilization.

[0011] Preferably, a CCD online detection system is provided on the sixth pipeline near the water outlet of the iron remover to monitor the water quality of the condensed water and ensure the water quality entering the thermal deaerator.

[0012] Preferably, the steam outlet of the first flash tank is also connected to a first steam sampling unit, the first steam sampling unit includes a first steam sampling pipeline and a first cooler connected in series on the first steam sampling pipeline, and tap water is introduced into another channel of the first cooler; the thermal deaerator is connected to a second steam sampling unit, the second steam sampling unit includes a second steam sampling pipeline and a second cooler connected in series on the second steam sampling pipeline, and tap water is introduced into another channel of the second cooler. The beneficial effect is that the utility model can cool and sample the steam in the first flash tank and the thermal deaerator, which is convenient for monitoring the quality of soft water vapor, thereby ensuring that the steam of the gas boiler meets the needs of industrial production.

[0013] Preferably, the flue gas waste heat recovery unit has a flue gas waste heat recovery heat exchanger arranged in the chimney of the gas steam boiler, the continuous heat exchanger is connected to the flue gas waste heat recovery heat exchanger through the second pipeline, and the flue gas waste heat recovery heat exchanger is connected to the insulation water tank through the third pipeline. The beneficial effect is that the utility model first uses the sewage waste heat recovery unit to heat the water in the insulation water tank once, and then uses the flue gas waste heat of the flue gas waste heat recovery unit to continue to heat it for a second time, effectively ensuring the water supply temperature of the thermal deaerator.

[0014] Compared with the prior art, the utility model utilizes the sewage waste heat recovery unit to supply the recovered steam heat to the thermal deaerator, which is then sent to the gas steam boiler after being processed by the thermal deaerator, thereby increasing the feed water temperature of the gas steam boiler and thereby reducing the gas consumption of the gas steam boiler; in addition, the hot water waste heat of the sewage waste heat recovery unit and the flue gas waste heat recovery unit can heat the water in the insulation water tank, further increasing the feed water temperature of the gas steam boiler, further reducing the gas consumption and reducing energy costs; the condensed water waste heat recovery unit can recover the condensed water waste heat, further improving the thermal utilization efficiency of the gas steam boiler.

[0015] According to the test, compared with the existing gas-fired steam boiler steam system with normal temperature deoxidation and normal temperature deironing, the utility model recovers and reasonably utilizes the waste heat generated, so that the gas energy consumption for producing one ton of steam is relatively reduced by 25m 3 The average water-vapor ratio can reach 1m³ / t, which reduces the water consumption in steam production to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the utility model. DETAILED DESCRIPTION

[0017] The following is a detailed description of an embodiment of the utility model in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the utility model, and a detailed implementation method and a specific operation process are given, but the protection scope of the utility model is not limited to the following embodiment.

[0018] It should be noted that, in the description of the present utility model, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0019] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connection" that may appear should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0020] like Figure 1 As shown, the waste heat recovery and utilization system of a gas steam boiler described in the utility model comprises a softened water supply unit, a flue gas waste heat recovery unit, a sewage waste heat recovery unit and a condensed water waste heat recovery unit. The softened water supply unit comprises a softened water device 1 and an insulated water tank 2 connected to tap water. The outlet of the softened water device 1 is divided into three routes. The first route is connected to the insulated water tank 2. The second route is connected to a thermal deaerator 4 through a boiler dosing device 3 (a commercially available device used to adjust the pH of boiler feed water, the pH is generally between 8.5 and 9.2) to ensure water quality. The third route is connected to an iron remover 5 (with a backwashing pressure pump) of the condensed water waste heat recovery unit, and the iron remover 5 can be backwashed to remove iron ions in the condensed water to ensure the feed water quality of the steam boiler.

[0021] The water feed port of the thermal deaerator 4 is connected to the gas steam boiler 6 through the fourth pipeline L4, and a boiler feed water pump P1 is provided on the fourth pipeline L4. The deoxygenated water is pumped into the gas steam boiler 6 by the boiler feed water pump P1; the insulated water tank 2 is connected to the thermal deaerator 4 through the fifth pipeline L5, and a deoxygenation pump P2 is provided on the fifth pipeline L5 near the insulated water tank 2. The insulated water tank 2 can provide higher temperature water to the thermal deaerator 4, thereby increasing the feed water temperature of the gas steam boiler 6.

[0022] Combination Figure 1It can be seen that the waste heat recovery unit includes a first flash tank 7, a first steam trap group F1 and a continuous heat exchanger 9. The first flash tank 7 and the first steam trap group F1 are arranged on the pipeline between the gas steam boiler 6 and the continuous waste heat expander 10. The steam outlet of the first flash tank 7 is connected to the thermal deaerator 4 through the first steam pipeline Z1. The hot water outlet (i.e., the sewage discharged from the boiler) of the first flash tank 7 is connected to the continuous waste heat expander 10 through the first steam trap group F1 (which can only allow hot water to pass but not steam). The steam outlet of the continuous waste heat expander 10 is connected to the thermal deaerator 4 through the second steam pipeline Z2. The hot sewage from the sewage expander 10 enters the sewage cooling pool after passing through the continuous heat exchanger 9 for further cooling; the insulated water tank 2 is connected to the continuous heat exchanger 9 through the first pipeline L1, and the continuous heat exchanger 9 is connected to the flue gas waste heat recovery unit through the second pipeline L2, and the hot water outlet of the flue gas waste heat recovery unit is connected to the insulated water tank 2 through the third pipeline L3; the flue gas waste heat recovery unit has a flue gas waste heat recovery heat exchanger 11 arranged in the chimney of the gas steam boiler 6, and the continuous heat exchanger 9 is connected to the flue gas waste heat recovery heat exchanger 11 through the second pipeline L2, and the flue gas waste heat recovery heat exchanger 11 is connected to the insulated water tank 2 through the third pipeline L3.

[0023] The gas steam boiler 6 is connected to a periodic sewage expansion device 8 and a continuous sewage expansion device 10. Since the sewage discharged periodically has a small amount and a high solid content, the utility model recovers the waste heat of the continuous sewage discharge of the gas steam boiler 6. When working, the first flash tank 7 can separate the continuous gas-liquid mixture discharged from the gas steam boiler 6 into flash steam and high-temperature hot water (temperature is 100-105°C). The flash steam directly enters the thermal deaerator 4 through the first steam pipeline Z1, provides a part of steam for the thermal deaerator 4, reduces the steam loss of the gas steam boiler 6, and thus increases the steam supply of the gas steam boiler 6, and reduces the steam production cost; the high-temperature hot water (temperature is 100-105°C) enters the continuous sewage expansion device 10, expands and separates through the continuous sewage expansion device 10 to obtain secondary steam and waste hot water with a temperature of 70°C to 90°C, and the waste hot water is discharged into the sewage cooling pool after heat exchange with softened water through the continuous heat exchanger 9, which not only realizes the primary heating of softened water, but also can reduce the sewage temperature to less than 50°C, thereby reducing the cooling water consumption of the sewage cooling pool;

[0024] The softened water from the continuous heat exchanger 9 enters the flue gas waste heat recovery heat exchanger 11, and performs heat exchange with the high-temperature flue gas (temperature of 90°C to 180°C) entering the flue gas waste heat recovery heat exchanger 11, realizing secondary heating of the softened water. After secondary heating, the temperature can reach 70°C to 90°C, and then enters the insulation water tank 2 through the third pipeline L3 to provide 70-90°C water supply for the thermal deaerator 4. The insulation water tank 2, the continuous heat exchanger 9 and the flue gas waste heat recovery heat exchanger 11 are connected in sequence to form a secondary heating cycle, which not only realizes the recovery and utilization of flue gas waste heat, but also realizes the recovery of waste hot water heat of the continuous waste heat of the gas steam boiler 6, improves the feed water temperature of the thermal deaerator 4, and improves the boiler feed water temperature (the boiler feed water temperature is above 104°C). In addition, the temperature of the high-temperature flue gas can be reduced to less than 30°C after heat exchange, reducing the impact on the surrounding environment.

[0025] In order to meet the continuous circulation heating demand of the insulated water tank 2, a water supply pump P3 is provided on the first pipeline L1 between the insulated water tank 2 and the continuous heat exchanger 9; a bypass pipe P with a first butterfly valve is passed between the first pipeline L1 and the second pipeline L2 near the continuous heat exchanger 9; when the temperature of the continuously discharged sewage is low, it directly enters the flue gas waste heat recovery heat exchanger 11 through the bypass pipe P and is heated by the high-temperature flue gas. Figure 1 .

[0026] The gas steam boiler 6 is usually equipped with a steam sub-cylinder 12. The steam of the gas steam boiler 6 is connected to the steam sub-cylinder 12 through the fourth steam pipeline Z4, and steam is provided to the user through the steam sub-cylinder 12. The condensed water waste heat recovery unit can be used to recover the heat of the high-temperature condensed water generated by the steam sub-cylinder 12.

[0027] Specifically: Combined Figure 1 It can be seen that the condensate waste heat recovery unit also includes a second flash tank 13 and a closed condensate recovery tank 14. The condensate inlet of the second flash tank 13 is connected to the steam cylinder 12, and a second steam trap group F2 is provided at the condensate outlet of the steam cylinder 12; the steam outlet of the second flash tank 13 is connected to the thermal deaerator 4 through the third steam pipeline Z3, and the condensate outlet of the second flash tank 13 is connected to the deaerator 4 through the third steam trap group F3 through the closed condensate recovery tank 14. The steam separator 12 is connected to the thermal deaerator 4 through the steam pressure reducing pipeline Z5, and the pressure reducing valve group of the steam pressure reducing pipeline Z5 is connected in parallel with the condensate recovery pipeline N, which is connected to the second flash tank 13, and the condensate recovery pipeline N is provided with a fourth steam trap group F4 for passing hot water;

[0028] The steam cylinder 12 is connected to the thermal deaerator 4; when the steam pressure reducing pipeline Z5 and the steam cylinder 12 both produce condensed water, the high-temperature condensed water produced by the steam cylinder 12 enters the second flash tank 13 through the second steam trap group F2, and the condensed water produced by the steam pressure reducing pipeline Z5 enters the second flash tank 13 through the fourth steam trap group F4. The condensed water is separated into flash steam and high-temperature condensed water (temperature is 70℃~90℃) through the second flash tank 13, and the condensed water enters the third steam trap group F3 to be recovered in the closed condensate recovery tank 14, and then enters the iron remover 5 for iron removal under the action of the condensate pump P4, and enters the thermal deaerator 4 after iron removal, so as to realize the recovery and full utilization of the waste heat of the condensate. In addition, the combination of the second flash tank 13 + the third steam trap group F3 can effectively prevent the flash steam from entering the closed condensate recovery tank 14, thereby preventing the condensate pump P4 from cavitation, and further extending the service life of the condensate pump P4.

[0029] Combination Figure 1 It can be seen that a CCD online detection system 15 (existing commercially available equipment) is provided on the sixth pipeline L6 at the outlet of the iron remover 5 to monitor the water quality of the condensed water. A sewage branch pipe is provided on the sixth pipeline L6 located at the rear side of the CCD online detection system. When the water quality does not meet the standard, it can be directly discharged into the sewage cooling pool through the sewage branch pipe until the water quality meets the standard and then sent to the thermal deaerator 4 to improve the boiler feed water quality.

[0030] The condensate return pipe generated by the user's steam is connected to the second flash tank 13. The treated condensate directly enters the thermal deaerator 4 using the second flash tank 13, and then enters the gas steam boiler after being deoxygenated by the thermal deaerator 4. The CCD online detection system is used for online detection to prevent the condensate from directly entering the boiler, thereby improving the feed water quality of the boiler and further reducing the impact of water quality on the boiler.

[0031] During actual installation, in order to meet the normal operation of the utility model, the boiler feed water pump P1 (variable frequency anti-cavitation pump is selected), deaerator pump P2, make-up water pump P3, and condensate pump P4 are all in two groups, one for backup and one for use.

[0032] Combination Figure 1It can be seen that the steam outlet of the first flash tank 7 is also connected to a first steam sampling unit, which includes a first steam sampling pipeline Z6 and a first cooler E1 connected in series on the first steam sampling pipeline Z6, and tap water is connected to another channel of the first cooler E1; the thermal deaerator 4 is connected to a second steam sampling unit, which includes a second steam sampling pipeline Z7 and a second cooler E2 connected in series on the second steam sampling pipeline Z7, and tap water is connected to another channel of the second cooler E2, and the steam is cooled by tap water. In actual operation, the valve on the first steam sampling pipeline Z6 and the valve on the second steam sampling pipeline Z7 can be opened regularly, and the corresponding steam can be cooled regularly and then the relevant water quality test can be carried out to ensure the water quality of the whole system.

[0033] The water outlet of the softened water supply unit of the utility model is divided into three routes, which can not only meet the automatic backwashing demand of the iron remover 5, but also meet the water demand of the boiler dosing equipment 3, and can also supply water to the insulated water tank 2. During operation, part of the waste heat from the gas steam boiler 6 is converted into flash steam and secondary steam and directly enters the thermal deaerator 4, providing a certain steam source for the thermal deaerator 4; part of it is converted into waste hot water at 70°C to 90°C, which can be used to heat the softened water coming out of the insulated water tank 2; the waste heat of the high-temperature flue gas can be used to heat the softened water for a second time, and the softened water in the insulated water tank 2 can be heated to 70°C to 90°C, effectively ensuring the water supply temperature of the thermal deaerator 4, realizing the recovery and full utilization of the waste heat of the boiler flue gas and the waste heat from the sewage, and no other energy heating equipment is required to heat the softened water, reducing the water supply cost of the gas steam boiler 6;

[0034] During operation, the condensed water generated by steam condensation (from the steam cylinder 12 and the steam pressure reducing pipeline Z5) is flashed into flash steam and high-temperature condensed water through the second flash tank 13. The flash steam directly enters the thermal deaerator 4, and the high-temperature condensed water enters the thermal deaerator 4 after recovery and iron removal, thereby realizing the recovery and utilization of the waste heat of the condensed water. The utility model utilizes the waste heat of condensed water and the waste heat of sewage discharge to provide the thermal deaerator 4 with sufficient steam for its operation. It has been verified that the flash steam and secondary steam of the present invention account for about 10% to 30% of the steam required by the thermal deaerator 4, reducing the steam consumption of the gas steam boiler 6. Under the condition that the user demand remains unchanged, the natural gas consumption of the gas steam boiler 6 is greatly reduced, and the energy-saving and emission-reduction effect is remarkable.

[0035] The utility model utilizes the waste heat of hot water and flue gas in the waste heat of sewage and the waste heat of condensed water to provide 70°C to 90°C water supply for the thermal deaerator 4 without consuming other energy sources, thereby reducing the steam supply cost of the gas steam boiler 6, further reducing the production cost of steam, and having good economic benefits.

[0036] The utility model uses sewage hot water and flue gas heat exchange to increase the temperature of softened water. The hot sewage (the temperature can be reduced to 50°C) is directly discharged into the sewage cooling pool after heat exchange, reducing the cooling water circulation volume of the sewage cooling pool; the utility model can monitor the water quality of condensed water in real time, thereby effectively ensuring the water quality of softened water. Compared with normal temperature thermal deoxidation, the utility model can heat softened water to 70°C to 90°C, greatly increasing the water supply temperature of the thermal deaerator 4, thereby reducing the steam consumption of the thermal deaerator 4, and can also increase the boiler feed water temperature to above 104°C, further reducing natural gas energy consumption and reducing steam production costs.

[0037] Finally, it should be emphasized that the above is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A gas steam boiler waste heat recovery system, comprising a softened water supply unit and a flue gas waste heat recovery unit, characterized in that: It also includes a waste heat recovery unit for sewage and a waste heat recovery unit for condensed water. The softened water supply unit has an insulated water tank. The waste heat recovery unit for sewage includes a first flash tank, a first steam trap group and a continuous heat exchanger. The first flash tank and the first steam trap group are arranged between the gas steam boiler and the continuous sewage expansion device. The steam outlet of the first flash tank is connected to the thermal deaerator through the first steam pipeline, and the hot water outlet is connected to the continuous sewage expansion device through the first steam trap group. The steam outlet of the continuous sewage expansion device is connected to the thermal deaerator through the second steam pipeline. The hot sewage connected to the sewage expansion device enters the sewage cooling tank after passing through the continuous heat exchanger. The insulated water tank is connected to the continuous heat exchanger through a first pipeline, the continuous heat exchanger is connected to the flue gas waste heat recovery unit through a second pipeline, and the hot water outlet of the flue gas waste heat recovery unit is connected to the insulated water tank through a third pipeline; the water supply port of the thermal deaerator is connected to the gas steam boiler through a fourth pipeline, and a boiler feed water pump is arranged on the fourth pipeline; the insulated water tank is connected to the thermal deaerator through a fifth pipeline, and a deoxygenation pump is arranged on the fifth pipeline near the insulated water tank.

2. The waste heat recovery system of a gas steam boiler according to claim 1 is characterized in that: The softened water supply unit includes a softened water device, and the water outlet of the softened water device is divided into three routes. The first route is connected to the insulated water tank, the second route is connected to the thermal deaerator via a boiler dosing device, and the third route is connected to the iron remover of the condensate waste heat recovery unit for reverse flushing the iron remover.

3. The waste heat recovery system of a gas steam boiler according to claim 2 is characterized in that: The condensate waste heat recovery unit includes a second flash tank and a closed condensate recovery tank. The condensate inlet of the second flash tank is connected to the steam cylinder, and a second steam trap group is provided at the condensate outlet of the steam cylinder; the steam outlet of the second flash tank is connected to the thermal deaerator through a third steam pipeline, and the condensate outlet of the second flash tank is connected to the iron remover through the third steam trap group and the closed condensate recovery tank, and a condensate pump is provided at the water outlet of the closed condensate recovery tank; the iron remover is connected to the thermal deaerator through a sixth pipeline.

4. The waste heat recovery system of a gas steam boiler according to claim 3 is characterized in that: The steam cylinder is connected to the thermal deaerator through a steam pressure reducing pipeline, and a condensate recovery pipeline is connected in parallel to the pressure reducing valve group of the steam pressure reducing pipeline. The condensate recovery pipeline is connected to the second flash tank, and a fourth steam trap group for passing hot water is provided on the condensate recovery pipeline.

5. The waste heat recovery system of a gas steam boiler according to claim 2 is characterized in that: A CCD online detection system is arranged on the sixth pipeline near the water outlet of the iron remover.

6. The waste heat recovery system of a gas steam boiler according to claim 1 is characterized in that: The steam outlet of the first flash tank is also connected to a first steam sampling unit, which includes a first steam sampling pipeline and a first cooler connected in series to the first steam sampling pipeline, and tap water is introduced into another channel of the first cooler; the thermal deaerator is connected to a second steam sampling unit, which includes a second steam sampling pipeline and a second cooler connected in series to the second steam sampling pipeline, and tap water is introduced into another channel of the second cooler.

7. The waste heat recovery system of a gas steam boiler according to claim 1 is characterized in that: The flue gas waste heat recovery unit has a flue gas waste heat recovery heat exchanger arranged in the chimney of the gas steam boiler, the continuous heat exchanger is connected to the flue gas waste heat recovery heat exchanger through the second pipeline, and the flue gas waste heat recovery heat exchanger is connected to the insulation water tank through the third pipeline.

Images