Efficient steam boiler flue gas waste heat recovery device

Abstract

The utility model discloses an efficient steam boiler flue gas waste heat recovery device, which relates to the technical field of steam boilers, and comprises a primary condenser, a secondary condenser, a steam type heat pump and a deaerator, a first heat exchange cavity, a second heat exchange cavity and a third heat exchange cavity are formed in the steam type heat pump; a water inlet of the first-stage condenser is used for introducing boiler replenishing water, a water outlet of the first-stage condenser is communicated with an inlet of the first heat exchange cavity through a first pipeline, an outlet of the first heat exchange cavity is communicated with a water inlet of the deaerator through a second pipeline, and a water outlet of the deaerator is used for being communicated with a water replenishing port of a steam boiler; a circulating water passage can be formed between the second heat exchange cavity and the second-stage condenser so as to heat boiler replenished water in the first heat exchange cavity; and an inlet of the third heat exchange cavity is used for introducing steam so as to heat boiler replenished water in the first heat exchange cavity.

Description

Technical Field

[0001] The utility model relates to the technical field of steam boilers, in particular to a high-efficiency steam boiler flue gas waste heat recovery device. Background Art

[0002] There are a large number of steam boilers in the industrial production process. Usually, waste heat recovery equipment such as boiler economizers and condensers are installed on the flue of the steam boiler to heat the boiler feed water.

[0003] However, due to the lack of effective fluid design in the traditional boiler flue gas condensation process, the heat exchange efficiency is low and the low-grade flue gas condensation heat cannot be utilized. Usually, the exhaust gas temperature is above 60°C and the boiler feed water temperature is below 50°C. It is impossible to fully utilize the flue gas waste heat through heat exchange between the flue gas and the feed water. Utility Model Content

[0004] The purpose of this utility model is to provide a high-efficiency steam boiler flue gas waste heat recovery device to solve the problems existing in the above-mentioned related technologies. It can fully utilize the heat in the boiler flue gas to heat the boiler make-up water, thereby achieving the purpose of efficiently recovering the flue gas condensation heat and reducing energy consumption.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] The utility model provides a high-efficiency steam boiler flue gas waste heat recovery device, comprising a primary condenser, a secondary condenser, a steam-type heat pump and a deaerator, wherein the primary condenser and the secondary condenser are used to be connected in series on the flue of the steam boiler from front to back, and the steam-type heat pump is provided with a first heat exchange chamber, a second heat exchange chamber and a third heat exchange chamber; the water inlet of the primary condenser is used to allow boiler water to be introduced, the water outlet of the primary condenser is communicated with the inlet of the first heat exchange chamber through a first pipeline, and the outlet of the first heat exchange chamber is communicated with the water inlet of the deaerator through a second pipeline , the water outlet of the deaerator is used to communicate with the water supply port of the steam boiler; the outlet of the second heat exchange chamber is communicated with the water inlet of the secondary condenser through a third pipeline, and the water outlet of the secondary condenser is communicated with the inlet of the second heat exchange chamber through a fourth pipeline, and a circulating water passage can be formed between the second heat exchange chamber and the secondary condenser to heat the boiler supply water in the first heat exchange chamber; the inlet of the third heat exchange chamber is used to pass steam to heat the boiler supply water in the first heat exchange chamber, and the outlet of the third heat exchange chamber is communicated with the first pipeline through a fifth pipeline.

[0007] Preferably, a boiler economizer is further included, which is used to be connected in series to the flue of the steam boiler and is located in front of the primary condenser; the water outlet of the deaerator is connected to the water inlet of the boiler economizer through the sixth pipeline, and the water outlet of the boiler economizer is connected to the water supply port of the steam boiler through the seventh pipeline.

[0008] Preferably, a deaerator outlet pump is also provided on the sixth pipeline.

[0009] Preferably, the water inlet of the primary condenser is also connected to a water supply mechanism, which includes a water softener and a softened water tank connected in sequence, and the water outlet of the softened water tank is connected to the water inlet of the primary condenser through an eighth pipeline.

[0010] Preferably, the eighth pipeline is further provided with a softening water tank outlet pump.

[0011] Preferably, a circulating water pump is also provided on the third pipeline.

[0012] Preferably, the primary condenser is an asymmetric plate heat exchanger.

[0013] Preferably, the secondary condenser is an asymmetric plate heat exchanger.

[0014] Preferably, the steam-type heat pump is a lithium bromide-type absorption heat pump.

[0015] Preferably, the deaerator is a thermal deaerator.

[0016] Compared with the related art, the utility model has achieved the following technical effects:

[0017] The utility model provides a high-efficiency steam boiler flue gas waste heat recovery device, which includes a first-stage condenser, a second-stage condenser, a steam-type heat pump and a deaerator. When working, the first-stage condenser and the second-stage condenser are connected in series on the flue of the steam boiler from front to back, and boiler feed water is passed into the first-stage condenser to exchange heat with the boiler flue gas. The boiler feed water heated by the boiler flue gas enters the first heat exchange chamber of the steam-type heat pump. At the same time, a circulating water passage is formed between the second heat exchange chamber of the steam-type heat pump and the second-stage condenser, so that the circulating water in the second heat exchange chamber enters the second condenser to exchange heat with the boiler flue gas, thereby extracting condensation heat from the boiler flue gas. The circulating water heated by the boiler flue gas is used as a low-temperature heat source of the steam-type heat pump to heat the boiler feed water in the first heat exchange chamber, and steam is passed into the third heat exchange chamber of the steam-type heat pump to heat the boiler feed water in the first heat exchange chamber. The heated boiler feed water is then treated in the deaerator and enters the steam boiler, thereby fully utilizing the heat in the boiler flue gas to heat the boiler feed water, achieving the purpose of efficiently recovering the flue gas condensation heat and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the working process of a high-efficiency steam boiler flue gas waste heat recovery device provided in an embodiment of the utility model.

[0020] In the figure: 01-steam boiler, 02-flue, 03-chimney, 1-primary condenser, 2-secondary condenser, 3-steam heat pump, 4-deaerator, 5-first pipeline, 6-second pipeline, 7-third pipeline, 701-circulating water pump, 8-fourth pipeline, 9-fifth pipeline, 10-boiler economizer, 11-sixth pipeline, 1101-deaerator outlet pump, 12-seventh pipeline, 13-water softener, 14-softened water tank, 15-eighth pipeline, 1501-softened water tank outlet pump. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] The purpose of this utility model is to provide a high-efficiency steam boiler flue gas waste heat recovery device to solve the problems existing in the relevant technology. It can make full use of the heat in the boiler flue gas to heat the boiler make-up water, thereby achieving the purpose of efficiently recovering the flue gas condensation heat and reducing energy consumption.

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0024] like Figure 1 As shown, this embodiment provides a high-efficiency steam boiler flue gas waste heat recovery device, including a primary condenser 1, a secondary condenser 2, a steam type heat pump 3 and a deaerator 4. The primary condenser 1 and the secondary condenser 2 are used to be connected in series on the flue 02 of the steam boiler 01 from front to back ( Figure 1The outlet of the middle flue 02 is connected to the chimney 03), and a first heat exchange chamber, a second heat exchange chamber and a third heat exchange chamber are provided in the steam type heat pump 3; the water inlet of the first-stage condenser 1 is used to pass boiler feed water, and the water outlet of the first-stage condenser 1 is connected with the inlet of the first heat exchange chamber through the first pipe 5, and the outlet of the first heat exchange chamber is connected with the water inlet of the deaerator 4 through the second pipe 6, and the water outlet of the deaerator 4 is used to communicate with the feed water port of the steam boiler 01; the outlet of the second heat exchange chamber is connected with the water inlet of the secondary condenser 2 through the third pipe 7, and the water outlet of the secondary condenser 2 is connected with the inlet of the second heat exchange chamber through the fourth pipe 8, and a circulating water passage can be formed between the second heat exchange chamber and the secondary condenser 2 to heat the boiler feed water in the first heat exchange chamber; the inlet of the third heat exchange chamber is used to pass steam to heat the boiler feed water in the first heat exchange chamber, and the outlet of the third heat exchange chamber is connected with the first pipe 5 through the fifth pipe 9.

[0025] During operation, the first-stage condenser 1 and the second-stage condenser 2 are connected in series on the flue 02 of the steam boiler 01 from front to back, and the boiler feed water is passed into the first-stage condenser 1 to exchange heat with the boiler flue gas. The boiler feed water heated by the boiler flue gas enters the first heat exchange chamber of the steam-type heat pump 3. At the same time, a circulating water passage is formed between the second heat exchange chamber of the steam-type heat pump 3 and the second-stage condenser 2, so that the circulating water in the second heat exchange chamber enters the second condenser 2 to exchange heat with the boiler flue gas, extracting the condensation heat in the boiler flue gas, and the circulating water heated by the boiler flue gas is used as the low-temperature heat source of the steam-type heat pump 3 to heat the boiler feed water in the first heat exchange chamber. In addition, the steam is passed into the third heat exchange chamber of the steam-type heat pump 3 to heat the boiler feed water in the first heat exchange chamber. The heated boiler feed water is then treated by the deaerator 4 and enters the steam boiler 01, thereby fully utilizing the heat in the boiler flue gas to heat the boiler feed water, achieving the purpose of efficiently recovering the flue gas condensation heat and reducing energy consumption.

[0026] It should be noted that the heating calculation in the above process is as follows:

[0027] 1. Calculation of water heating for primary condenser 1

[0028] (1) Flue gas characteristics

[0029] According to the composition and characteristics of boiler flue gas, it contains a large amount of water vapor, and its dew point temperature is generally around 57°C. When the temperature of the boiler flue gas drops below the dew point temperature, the water vapor in the boiler flue gas condenses into liquid water. The phase change process releases a large amount of heat, which is what we call condensation heat (latent heat). The latent heat is much greater than the sensible heat of the flue gas.

[0030] (2) Design parameters

[0031] In this embodiment, the exhaust gas temperature before entering the primary condenser 1 is about 100°C, and the boiler feed water at 25°C needs to be heated. According to theoretical calculations, the boiler feed water can be heated to 69.7°C. The specific calculation is as follows:

[0032] 1) Latent heat

[0033] The temperature of boiler feed water can be raised by utilizing the latent heat of vaporization of water vapor in boiler flue gas:

[0034] The latent heat of vaporization of water vapor in boiler flue gas is about 10% of the low calorific value of natural gas (the latent heat of vaporization of water vapor per ton of boiler flue gas is about 6.5×10 4 Kcal), and the recovered heat can raise the feed water temperature of a 1t boiler to 65℃.

[0035] Since the dew point temperature of water in boiler flue gas is about 57℃, the latent heat of vaporization of this part of water vapor can increase the temperature of boiler feed water to 57℃ at most. We can use this part of heat to increase the temperature of boiler feed water to 57℃.

[0036] The heat and value that can be recovered by using the latent heat of vaporization of water vapor in boiler flue gas to heat boiler feed water:

[0037] Based on the annual average boiler feed water temperature of 25°C, the boiler feed water is heated to 57°C using low-temperature flue gas. The amount of heat that can be recovered from the flue gas per ton of steam is:

[0038] (57-25)×1000=3.2×10 4 kcal

[0039] 2) Sensible heat part

[0040] All boiler flue gas above 57℃ is sensible heat. The amount of heat that can be recovered from flue gas per ton of steam is:

[0041] 78×11.604×1.25×1.09÷4.1868×(100-57)=1.27×10 4 Kcal

[0042] 3) Total waste heat

[0043] Through the primary condenser 1 provided in this embodiment, the total amount of latent heat and sensible heat that can be recovered from the flue gas per ton of steam is:

[0044] 3.2+1.27=4.47×10 4 Kcal

[0045] If calculated based on the boiler feed water temperature of 25°C, the boiler feed water temperature can be raised to 70°C after passing through the primary condenser 1 provided in this embodiment.

[0046] 2. Calculation of water heating for steam heat pump 3

[0047] The exhaust gas temperature is cooled to 47-48°C by primary condenser 1 and further cooled to below 42°C by secondary condenser 2, generating circulating water at 40 / 45°C, which provides waste heat for steam-type heat pump 3. The heat pump heating COP of steam-type heat pump 3 is 1.7. Of the 1.7 parts of heat generated by steam-type heat pump 3, 0.7 is provided by secondary condenser 2 and 1 part is provided by steam. Steam-type heat pump 3 raises the boiler feed water from 70°C to 95°C, of which 10°C is provided by waste heat from the flue gas and 15°C is provided by steam.

[0048] 3. Calculation of water supply and heating for this device

[0049] According to the above calculations, the primary condenser 1 uses the boiler flue gas to raise the temperature of the boiler feed water from 25°C to 70°C. The steam-type heat pump 3 raises the temperature of the boiler feed water after exiting the primary condenser 1 to 95°C, of which 10°C is provided by the flue gas waste heat and 15°C is provided by the steam. Therefore, the flue gas waste heat heats the 25°C boiler feed water to 95°C, for a total temperature rise of 70°C, of which 55°C is provided by the flue gas waste heat and 15°C is provided by the steam. Assuming that the boiler consumes 80Nm to produce 1t of steam, 3 Natural gas, the calorific value of natural gas is 8300Kcal / Nm 3 Calculation shows that the proportion of flue gas waste heat recovery heat to natural gas heat is:

[0050] 1×55×(4180÷3600)÷80÷(8300÷860)=8.28%

[0051] In this embodiment, the primary condenser 1 and the secondary condenser 2 are preferably asymmetric plate heat exchangers, the steam heat pump 3 is preferably a lithium bromide absorption heat pump, and the deaerator 4 is preferably a thermal deaerator. In this embodiment, a circulating water pump 701 is also provided on the third pipeline 7 to provide power for the circulating water, so that the device has the following advantages:

[0052] First, the primary condenser 1 and the secondary condenser 2 in this embodiment both adopt the structure of a plate-type asymmetric heat exchanger. The airflow and water distribution in this structure are more uniform, which greatly improves the heat exchange efficiency between the flue gas and water, and makes full use of the natural heat exchange temperature difference between the flue gas and the make-up water, so that the make-up water temperature is raised higher.

[0053] Second, the steam-type heat pump 3 in this embodiment adopts lithium bromide absorption heat pump technology to heat the flue gas obtained by the secondary condenser 2, further utilizing the low-temperature condensation heat of the flue gas and reducing the steam consumption of the thermal deaerator.

[0054] Third, this device adopts a first-stage condenser 1 and a steam-type heat pump 3 connected in series, and uses two sets of equipment to perform relay heating. In addition, by controlling the flow of the circulating water pump 701, the circulating water volume is matched with the boiler flue gas volume, thereby making full use of the heat exchange temperature difference and the flue gas heat.

[0055] In this embodiment, the device also includes a boiler economizer 10, which is used to be connected in series to the flue 02 of the steam boiler 01 and is located in front of the primary condenser 1; the water outlet of the deaerator 4 is connected to the water inlet of the boiler economizer 10 through the sixth pipeline 11, and the water outlet of the boiler economizer 10 is connected to the water supply port of the steam boiler 01 through the seventh pipeline 12.

[0056] Furthermore, a deaerator outlet pump 1101 is also provided on the sixth pipeline 11 .

[0057] In this embodiment, the water inlet of the primary condenser 1 is also connected to a water supply mechanism, which includes a water softener 13 and a softened water tank 14 connected in sequence. The water outlet of the softened water tank 14 is connected to the water inlet of the primary condenser 1 through an eighth pipeline 15.

[0058] Furthermore, a softened water tank outlet pump 1501 is also provided on the eighth pipeline 15 .

[0059] In summary, this device is based on a high-efficiency plate-type flue gas condenser combined with an absorption heat pump to recover the flue gas waste heat of a high-efficiency steam boiler 01. The flue gas waste heat is fully recovered for boiler feed water heating. It is suitable for projects where the condensed water of the steam boiler 01 is not recovered and the feed water heating and deoxygenation process requires steam consumption. The high-efficiency plate-type flue gas condenser makes full use of the natural temperature difference to increase the feed water temperature, and the absorption heat pump further utilizes the low-temperature condensation heat of the flue gas to raise the feed water temperature to 95°C, effectively realizing the recovery of latent heat in the flue gas, cooling the flue gas temperature to below 40°C, and improving the boiler efficiency by more than 8%.

[0060] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A high-efficiency steam boiler flue gas waste heat recovery device, characterized by: The invention comprises a primary condenser, a secondary condenser, a steam-type heat pump and a deaerator. The primary condenser and the secondary condenser are used to be connected in series on the flue of the steam boiler from front to back. The steam-type heat pump is provided with a first heat exchange chamber, a second heat exchange chamber and a third heat exchange chamber; the water inlet of the primary condenser is used to introduce boiler water, the water outlet of the primary condenser is connected to the inlet of the first heat exchange chamber through a first pipeline, the outlet of the first heat exchange chamber is connected to the water inlet of the deaerator through a second pipeline, and the water outlet of the deaerator is used to It is connected to the water feed port of the steam boiler; the outlet of the second heat exchange chamber is connected to the water inlet of the secondary condenser through a third pipeline, and the water outlet of the secondary condenser is connected to the inlet of the second heat exchange chamber through a fourth pipeline, and a circulating water passage can be formed between the second heat exchange chamber and the secondary condenser to heat the boiler feed water in the first heat exchange chamber; the inlet of the third heat exchange chamber is used to pass steam to heat the boiler feed water in the first heat exchange chamber, and the outlet of the third heat exchange chamber is connected to the first pipeline through a fifth pipeline.

2. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 1 is characterized in that: It also includes a boiler economizer, which is used to be connected in series to the flue of the steam boiler and is located in front of the primary condenser; the water outlet of the deaerator is connected to the water inlet of the boiler economizer through the sixth pipeline, and the water outlet of the boiler economizer is connected to the water supply port of the steam boiler through the seventh pipeline.

3. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 2 is characterized in that: The sixth pipeline is also provided with a deaerator water outlet pump.

4. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 1 is characterized in that: The water inlet of the primary condenser is also connected to a water supply mechanism, which includes a water softener and a softened water tank connected in sequence. The water outlet of the softened water tank is connected to the water inlet of the primary condenser through an eighth pipeline.

5. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 4 is characterized in that: The eighth pipeline is also provided with a softening water tank outlet pump.

6. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 1 is characterized in that: The third pipeline is also provided with a circulating water pump.

7. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 1 is characterized in that: The primary condenser is an asymmetric plate heat exchanger.

8. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 1 is characterized in that: The secondary condenser is an asymmetric plate heat exchanger.

9. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 1, characterized in that: The steam type heat pump is a lithium bromide type absorption heat pump.

10. The high-efficiency steam boiler flue gas waste heat recovery device according to claim 1, characterized in that: The deaerator is a thermal deaerator.

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