Multi-stage combined type steam condensate waste heat recovery air heater

Abstract

The embodiment of the utility model provides a multi-stage combined type steam condensate water waste heat recovery air heater, and relates to the technical field of waste heat recovery and utilization of secondary steam of steam calcination gypsum condensate water. The multi-stage combined type steam condensate water waste heat recovery air heater comprises a first-stage condensate water heat exchanger, a second-stage heater and a third-stage heater which are internally provided with heat exchange pipes, the first-stage condensate water heat exchanger is provided with a heat exchange pipe network, and a heat medium needing to be heated conducts first-stage heat exchange with condensate water in the first-stage condensate water heat exchanger through the heat exchange pipes; a heated medium passes through the first-stage condensate water heat exchanger and then enters the second-stage heater through the first-stage hot air outlet, the hot air connecting pipe and the hot air inlet of the second-stage heater. The system not only effectively recovers secondary steam heat energy generated by slightly overheated condensate water, but also improves the comprehensive utilization efficiency of the steam heat energy, reduces the mass loss of the condensate water, and reduces energy waste.

Description

Technical Field

[0001] This utility model relates to the field of waste heat recovery and utilization technology of secondary steam from condensate of steam-calcined gypsum, and in particular to a multi-stage composite steam condensate waste heat recovery air heater. Background Technology

[0002] In recent years, the gypsum industry has flourished, driving the widespread application of steam as a clean energy source in process heating and gypsum calcination. Most of this steam originates from superheated steam generated during power plant generation. To ensure efficiency during transport, it is typically kept superheated until it reaches the heat-consuming enterprise. Within these enterprises, the superheat of the steam is generally between 20 and 40 degrees Celsius. After processing by heat exchange equipment in the production process, the condensate remains slightly superheated, with a superheat between 0 and 5 degrees Celsius. However, directly sending this slightly superheated condensate into a condensate expansion tank for recovery will trigger a large amount of secondary flash steam. Specifically, after passing through a steam trap, approximately 10% to 15% of the high-pressure condensate will be converted into secondary flash steam. Although its pressure is lower, its calorific value remains high; for example, at a pressure of 2 kg / cm³. 2 Secondary steam at a temperature of 120 degrees Celsius can release 2206 kJ / kg of heat.

[0003] Currently, many enterprises that use steam as a heat source to heat process materials or calcine gypsum directly release this secondary steam into the atmosphere. This not only causes a huge waste of heat energy, but also causes environmental pollution and noise problems.

[0004] In view of this, a multi-stage composite steam condensate waste heat recovery air heater is proposed, and the introduction of a multi-stage composite steam condensate waste heat recovery air heater has become an effective solution. Utility Model Content

[0005] The purpose of this invention is to provide a multi-stage composite steam condensate waste heat recovery air heater, which can avoid the situation where enterprises that use steam as a heat source to heat process materials or calcined gypsum directly release this secondary steam into the atmosphere, resulting in a huge waste of heat energy.

[0006] This utility model provides a multi-stage composite steam condensate waste heat recovery air heater, including a primary condensate heat exchanger with internal heat exchange tubes, a secondary heater, and a tertiary heater. The primary condensate heat exchanger is equipped with a heat exchange pipe network. The heat medium to be heated exchanges heat with the condensate in the primary condensate heat exchanger through the heat exchange tubes. After passing through the primary condensate heat exchanger, the heated medium enters the secondary heater through the primary hot air outlet, the hot air connection pipe, and the hot air inlet of the secondary heater. The secondary heater receives the medium after the primary heat exchange from the primary condensate heat exchanger and exchanges heat with secondary steam through the heat exchange tubes. The medium after heat exchange is heated to the required temperature by the tertiary heater.

[0007] In one specific implementation, the heat exchange tubes in the primary condensate heat exchanger use the sensible heat of the condensate to heat the medium to 50-60 degrees Celsius, and a drain outlet is provided at the bottom of the primary condensate heat exchanger.

[0008] In one specific implementation, the condensate after the secondary steam heat exchange releases heat energy is directly discharged into the primary condensate heat exchanger through the flash steam expansion vessel, reducing the condensate recovery pipeline. The heated medium is heated to about 80-90 degrees Celsius after passing through the secondary heater.

[0009] In one specific implementation, the inlet of the tertiary heater is equipped with a pressure regulating system to control the amount of primary steam input, thereby adjusting the temperature of the final output hot air.

[0010] In one specific implementation, the medium heated by the secondary heater enters the tertiary heater for third-stage heating, and the outlet temperature of the final heated medium is adjusted according to the operating temperature parameters required by the process. The hot air is heated to 170 to -180 degrees after passing through the tertiary heater.

[0011] In one specific implementation, the high-pressure condensate generated after the primary heat exchange of the steam passes through a steam trap group and is directly discharged into the flash steam expansion vessel through the condensate inlet for water-steam separation. The secondary flash steam generated by the separation enters the heat exchange tube of the secondary heater directly without passing through the pipeline system for condensation and heat exchange. The condensate generated after the secondary flash steam has completed its heat exchange is directly discharged into the primary condensate heat exchanger using the height difference to participate in secondary heat exchange.

[0012] In one specific implementation, a small amount of secondary steam exhaust gas after heat exchange by the secondary heater enters the waste steam collection tank. After reaching the design pressure, it is discharged through a safety valve. The waste steam collection tank is equipped with a pressure gauge connected to the control system and an vent valve.

[0013] In one specific implementation, the flash steam expansion vessel is equipped with a condensate level gauge, which is interlocked with the condensate recovery pump and valve group to ensure timely discharge of condensate and prevent the condensate level from being too high and submerging the condensate inlet. The condensate outlet is connected to the condensate recovery pump and valve group to discharge the condensate after heat exchange into the recovery system.

[0014] In one specific implementation, a primary steam control valve assembly is installed at the steam heat exchange system on the steam pipe leading to the tertiary heater. The primary steam control valve assembly is used to regulate the steam flow rate and pressure entering the tertiary heater.

[0015] In one specific implementation, the high-pressure condensate generated by the heat exchange of the three-stage heater is discharged into the flash steam expansion tank through the three-stage heater condensate discharge valve group for secondary flash evaporation and steam-water separation.

[0016] This utility model provides a multi-stage composite steam condensate waste heat recovery air heater, which, compared with the prior art, offers the following advantages:

[0017] The temperature of the heated air in this invention can be adjusted through a three-stage heater to reach the operating temperature required by other processes that require hot air as a medium, such as hot air drying, which requires a primary and secondary air system. This auxiliary heat exchange system improves the thermal utilization rate of the steam heat exchange system, reduces the overall energy consumption per unit product, and solves the problems of difficult utilization of condensate secondary steam, energy waste, and environmental issues caused by direct emissions. It also addresses the problems of high water vapor concentration and low temperature, leading to condensation, in the exhaust gas of some drying and calcining systems. This invention is significant for reducing energy consumption and recovering condensate in steam heat exchange systems. It not only effectively recovers the secondary steam heat energy generated by slightly superheated condensate but also improves the overall utilization efficiency of steam heat energy, reduces condensate mass loss, and lowers energy waste. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0020] Figure 2 This is an embodiment of the present utility model. Figure 1 One of the partial structural diagrams;

[0021] Figure 3This is an embodiment of the present utility model. Figure 1 The second partial structural diagram;

[0022] Figure 4 This is a schematic diagram of the overall structure of the present utility model embodiment in system application.

[0023] Figure 5 This is an embodiment of the present utility model. Figure 4 One of the partial structural diagrams;

[0024] Figure 6 This is an embodiment of the present utility model. Figure 4 The second partial structural diagram.

[0025] Figure label:

[0026] 1. Primary condensate heat exchanger; 2. Heat exchange piping network; 3. Flash steam expansion tank; 4. Condensate inlet; 5. Condensate level gauge; 6. Condensate outlet; 7. Drain outlet; 8. Primary hot air outlet; 9. Hot air connection pipe; 10. Secondary heater hot air inlet; 11. Secondary heater; 12. Residual steam collection tank; 13. Vent valve; 14. Safety valve; 15. Pressure gauge; 16. Heater connection pipe; 17. Tertiary heater; 18. Tertiary heater condensate drain valve assembly; 19. Primary steam control valve assembly; 20. Steam heat exchange system; 21. Condensate recovery pump and valve assembly. Detailed Implementation

[0027] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] Please refer to Figures 1 to 6This utility model embodiment provides a multi-stage composite steam condensate waste heat recovery air heater. Since the condensate from the steam heat exchange system 20 is slightly superheated condensate, typically at 120-170 degrees Celsius, after passing through the condensate drain system, the pressure drops after the drain valve, causing the condensate to generate a large amount of flash steam. This flash steam mixes with the condensate and is discharged into a condensate collection tank via a pipeline. In the condensate collection tank, the flash steam separates from the condensate to form secondary steam. This secondary steam has lower pressure and temperature but contains a large amount of heat and is generally discharged directly, thus generating heat energy. Due to the significant waste, this application introduces the condensate into a multi-stage composite steam condensate waste heat recovery air heater via a pipe after passing through a steam trap. The slightly superheated condensate exchanges heat with ambient air passing through the primary heat exchange network 2 in the primary condensate heat exchanger 1. The heat exchange tubes in the primary condensate heat exchanger 1 utilize the sensible heat of the condensate to heat the medium to 50-60 degrees Celsius. A drain outlet 7 is provided at the bottom of the primary condensate heat exchanger 1. The primary hot air after heat exchange enters the hot air side of the secondary heater 11 through the primary hot air outlet 8, the hot air connection pipe 9, and the secondary heater hot air inlet 10.

[0029] The secondary flash steam generated by the slightly superheated condensate enters the steam side of the secondary air heater 11 directly through the flash steam expansion tank 3. The condensate generated by the heat exchange flows directly back into the primary condensate heat exchanger 1, reducing the condensate recovery pipeline. After passing through the secondary heater 11, the heated medium is heated to about 80-90 degrees Celsius. A small amount of residual gas that has not been completely heat-exchanged enters the residual steam collection tank 12. After reaching the design pressure, it is discharged through the safety valve 14. The residual steam collection tank 12 is equipped with a pressure gauge 15 connected to the control system, and an vent valve 13 is installed on the residual steam collection tank 12.

[0030] After the primary heat exchange of steam, the high-pressure condensate produced is discharged directly into the flash steam expansion vessel 3 through the condensate inlet 4 via the steam trap group for water-steam separation. The secondary flash steam produced by the separation enters the heat exchange tube of the secondary heater 11 directly without passing through the pipeline system for condensation and heat exchange. After the secondary flash steam has completed its heat exchange, the condensate produced is directly discharged into the primary condensate heat exchanger 1 using the height difference to participate in secondary heat exchange.

[0031] The heated air, after secondary heating, enters the tertiary heater 17 through the heater connecting pipe 16 to exchange heat with high-temperature and high-pressure steam. The temperature of the hot air in the tertiary heater 17 can be adjusted and controlled according to different process requirements by controlling the steam process conditions entering the tertiary heater 17. The air temperature can reach 170-190 degrees Celsius. It is then transported through pipelines to the subsequent hot air or hot air system. The inlet of the tertiary heater 17 is equipped with a pressure regulating system to control the amount of primary steam input, thereby adjusting the temperature of the final output hot air.

[0032] The high-temperature slightly superheated steam introduced into the tertiary heater 17 heats the secondary air, and the resulting condensate is also slightly superheated condensate. It is discharged into the primary condensate heat exchanger 1 through the tertiary heater condensate discharge valve group 18 for waste heat recovery.

[0033] A primary steam control valve assembly 19 is installed at the steam heat exchange system 20 on the steam pipe leading to the tertiary heater 17. The primary steam control valve assembly 19 is used to regulate the steam flow rate and pressure entering the tertiary heater 17.

[0034] All the condensate after sufficient heat exchange is discharged to the condensate recovery system through the condensate outlet 6 on the primary condensate heat exchanger 1. The flash steam expansion tank 3 is equipped with a condensate level gauge 5, which is interlocked with the condensate recovery pump and valve group 21 to ensure timely discharge of condensate and prevent the condensate level from being too high and submerging the condensate inlet 4. The condensate outlet 6 is connected to the condensate recovery pump and valve group 21 to control the liquid level in the primary condensate heat exchanger 1.

[0035] In summary, the working principle of the multi-stage composite steam condensate waste heat recovery air heater of this utility model embodiment is as follows: slightly superheated condensate first exchanges heat with room temperature air in the first-stage condensate heat exchanger 1, and the generated first-stage hot air enters the second-stage heater 11. At the same time, the secondary flash steam generated by the condensate directly enters the second-stage heater 11 for heat exchange. The condensate after heat exchange flows back to the first-stage condensate heat exchanger 1. After water-vapor separation, the high-pressure condensate's secondary flash steam also enters the second-stage heater 11 for heat exchange. The condensate then participates in the secondary heat exchange of the first-stage condensate heat exchanger 1. Subsequently, the second-stage heated hot air enters the third-stage heater 17 to exchange heat with high-temperature and high-pressure steam. After reaching the required temperature, it is output. The condensate generated by the third-stage heater 17 also flows back to the first-stage condensate heat exchanger 1 for waste heat recovery. Finally, all the condensate after heat exchange is discharged to the condensate recovery system, realizing the efficient recovery and utilization of condensate and flash steam heat energy.

[0036] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A multi-stage composite steam condensate waste heat recovery air heater, characterized in that: The system includes a primary condensate heat exchanger (1) with internal heat exchange tubes, a secondary heater (11) and a tertiary heater (17). The primary condensate heat exchanger (1) is equipped with a heat exchange pipe network (2). The heat medium to be heated exchanges heat with the condensate inside the primary condensate heat exchanger (1) through the heat exchange tubes. After passing through the primary condensate heat exchanger (1), the heated medium enters the secondary heater (11) through the primary hot air outlet (8), the hot air connection pipe (9) and the secondary heater hot air inlet (10). The secondary heater (11) receives the medium after primary heat exchange from the primary condensate heat exchanger (1) and exchanges heat with secondary steam through the heat exchange tubes. The medium after heat exchange is heated to the required temperature by the tertiary heater (17).

2. The multi-stage composite steam condensate waste heat recovery air heater according to claim 1, characterized in that: The heat exchange tubes in the primary condensate heat exchanger (1) use the sensible heat of the condensate to heat the medium to 50-60 degrees. A drain outlet (7) is provided at the bottom of the primary condensate heat exchanger (1).

3. The multi-stage composite steam condensate waste heat recovery air heater according to claim 2, characterized in that: The condensate that is released after the secondary steam heat exchange releases heat energy is directly discharged into the primary condensate heat exchanger (1) through the flash steam expansion vessel (3), reducing the condensate recovery pipeline. The heated medium is heated to about 80-90 degrees after passing through the secondary heater (11).

4. The multi-stage composite steam condensate waste heat recovery air heater according to claim 3, characterized in that: The inlet of the three-stage heater (17) is equipped with a pressure regulating system to control the amount of primary steam input, thereby adjusting the temperature of the final output hot air.

5. The multi-stage composite steam condensate waste heat recovery air heater according to claim 4, characterized in that: The medium heater connecting pipe (16) heated by the secondary heater (11) enters the tertiary heater (17) for third-stage heating. The outlet temperature of the final heated medium is adjusted according to the operating temperature parameters required by the process. The hot air is heated to 170-180 degrees after passing through the tertiary heater (17).

6. The multi-stage composite steam condensate waste heat recovery air heater according to claim 5, characterized in that: The high-pressure condensate generated after the steam undergoes primary heat exchange is discharged directly into the flash steam expansion vessel (3) through the condensate inlet (4) via the steam trap group for water-steam separation. The secondary flash steam generated by the separation enters the heat exchange tube of the secondary heater (11) directly without passing through the pipeline system for condensation and heat exchange. The condensate generated after the flash secondary steam has completed its heat exchange is directly discharged into the primary condensate heat exchanger (1) using the height difference to participate in secondary heat exchange.

7. The multi-stage composite steam condensate waste heat recovery air heater according to claim 6, characterized in that: After heat exchange by the secondary heater (11), a small amount of secondary steam exhaust gas enters the residual steam collection tank (12). After reaching the design pressure, it is discharged through the safety valve (14). The residual steam collection tank (12) is equipped with a pressure gauge (15) connected to the control system and an air vent valve (13).

8. The multi-stage composite steam condensate waste heat recovery air heater according to claim 7, characterized in that: The flash steam expansion vessel (3) is equipped with a condensate level gauge (5), which is interlocked with the condensate recovery pump and valve group (21) to ensure timely discharge of condensate and prevent the condensate level from being too high and submerging the condensate inlet (4). The condensate outlet (6) is connected to the condensate recovery pump and valve group (21) to discharge the condensate after heat exchange into the recovery system.

9. The multi-stage composite steam condensate waste heat recovery air heater according to claim 8, characterized in that: A primary steam control valve assembly (19) is installed at the steam heat exchange system (20) on the steam pipe leading to the tertiary heater (17). The primary steam control valve assembly (19) is used to regulate the steam flow rate and pressure entering the tertiary heater (17).

10. The multi-stage composite steam condensate waste heat recovery air heater according to claim 9, characterized in that: The high-pressure condensate generated by the heat exchange of the three-stage heater (17) is discharged into the first-stage condensate heat exchanger (1) through the three-stage heater condensate discharge valve group (18) for waste heat recovery.

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