Micro-overheating gas-fired boiler with hot standby and quick start functions

Abstract

The utility model discloses a micro overheating gas-fired boiler with hot standby and quick start functions, which comprises a burner, a steam pocket, a hearth, a turning flue, a tail flue and a chimney, the steam pocket is connected with a downcomer, and an evaporator I and an evaporator II are sequentially arranged in the hearth along the flowing direction of smoke. The upper end and the lower end of the first evaporator and the upper end and the lower end of the second evaporator are communicated with the steam pocket and the downcomer respectively through pipelines, the superheater, the economizer, the air preheater and the condensation water heater are sequentially arranged in the tail flue behind the turning flue from bottom to top, and the chimney is arranged behind the condensation water heater. Through structural arrangement and water circulation process optimization, the hot standby load of the boiler is below 5%, fuel consumption can be saved to the maximum extent when the steam demand is insufficient, and the energy utilization efficiency is improved. The unit can be lifted to the full load of the boiler from the hot standby working condition within only 5 minutes at the soonest, the steam requirement of a user can be responded in time, good adaptability to a main process is achieved, and shutdown of a main process device is avoided.

Description

Technical Field

[0001] The utility model relates to the fields of petrochemical industry and boiler technology, and in particular to a slightly superheated gas boiler with hot standby and quick start functions. Background Art

[0002] The petrochemical industry has experienced significant growth in recent years, particularly in the PTA (purified terephthalic acid) market. Following a boom in the second half of 2017, domestic production saw rapid growth, reaching a 13.48% year-on-year increase in 2018. With new plants coming online in 2019 and continued favorable demand, PTA production reached 44.854 million tons, a 10.58% increase. This increased production has driven demand for steam, significantly increasing the need for boilers in the petrochemical industry.

[0003] Petrochemical processes have stringent steam requirements, requiring both stable and timely steam availability. Against the backdrop of increasingly stringent national environmental protection requirements, companies are not only gradually replacing coal-fired boilers with gas-fired ones, but are also primarily installing gas-fired boilers in new installations. Gas-fired boilers have higher fuel costs than coal-fired ones. Therefore, while still meeting process requirements, users desire to minimize gas consumption during the boiler's standby phase to save operating costs.

[0004] The minimum stable combustion load of a conventional Π-type gas boiler is 30%, and the fuel consumption is high when in standby mode. At the same time, the hot start-up time of a conventional Π-type gas boiler exceeds 1 hour, which cannot respond to users' steam needs in a timely manner.

[0005] Reducing the hot standby load can save fuel consumption to the maximum extent and improve energy utilization efficiency when steam demand is insufficient; at the same time, it often reduces the load increase time, responds to the user's steam demand in a timely manner, and has better adaptability to the main process. Utility Model Content

[0006] To address these technical issues, this utility model has designed a slightly superheated gas-fired boiler with hot standby and quick-start capabilities. By optimizing its structural layout and water circulation process, the boiler's hot standby load is kept below 5%, minimizing fuel consumption and improving energy efficiency when steam demand is insufficient. The unit can be upgraded from hot standby to full boiler load in as little as 5 minutes, enabling timely response to user steam demands. Its excellent adaptability to the primary process prevents downtime of primary process equipment, bringing significant economic benefits to the owner.

[0007] The utility model adopts the following technical solutions:

[0008] A slightly superheated gas boiler with hot standby and quick start functions includes a burner, a steam drum, a furnace, a turning flue, a tail flue and a chimney. The steam drum is connected to a downcomer. Evaporator 1 and evaporator 2 are arranged in sequence in the furnace along the flow direction of the flue gas. The upper and lower ends of evaporator 1 and evaporator 2 are connected to the steam drum and the downcomer through pipelines respectively. A superheater, an economizer, an air preheater and a condensate heater are arranged in sequence from bottom to top in the tail flue behind the turning flue. The chimney is arranged behind the condensate heater.

[0009] Preferably, the burners are arranged in layers on the front wall of the furnace, and can be arranged in 1 to 3 layers according to the situation, with 1 to 2 burners arranged on each layer.

[0010] Preferably, the furnace is arranged horizontally, and the furnace depth can reach more than 10m. The burner can be designed with a longer flame to reduce NOx emissions.

[0011] Preferably, the drum adopts a large-volume design with increased water volume to ensure that the drum water level can remain stable during rapid load increase, and a certain amount of flash steam is provided in the early stage of load increase to increase the boiler startup rate.

[0012] Preferably, the downcomers are arranged in multiple pieces with large cross-sections, which increases the steam-water flow area and reduces the steam-water flow resistance, thereby facilitating the rapid establishment of water circulation and ensuring the safety of water circulation during rapid boiler startup.

[0013] Preferably, the superheater, economizer and condensate heater may adopt a finned tube structure to improve heat transfer efficiency and reduce boiler steel consumption.

[0014] Preferably, the superheater, economizer, air preheater and condensate heater are delivered to the site in a tube box structure, and on-site construction only requires hoisting them into place, which reduces the on-site installation workload, reduces on-site installation costs, and shortens the boiler construction period.

[0015] Preferably, the air preheater can adopt a vertical pipe box structure, a horizontal pipe box structure, a heat pipe structure or a rotary structure.

[0016] Preferably, the air preheater can be arranged in 1 to 3 stages to reduce the flue gas temperature at the boiler outlet and improve boiler efficiency.

[0017] Preferably, the chimney is supported on the boiler rear frame, which reduces the steel consumption of the chimney and the footprint of the boiler.

[0018] Preferably, the steam temperature at the boiler outlet has a superheat of 3 to 20° C. to prevent condensation of the steam during transmission.

[0019] The beneficial effects of the utility model are as follows: (1) by optimizing the structural arrangement and the water circulation process, the hot standby load of the boiler is kept below 5%, which can save fuel consumption to the maximum extent and improve energy utilization efficiency when the steam demand is insufficient; (2) the unit can be upgraded from the hot standby condition to the full load of the boiler in as little as 5 minutes, which can respond to the user's steam demand in a timely manner, has good adaptability to the main process, avoids the shutdown of the main process equipment, and brings great economic benefits to the owner. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the utility model;

[0021] In the figure: 1. Burner, 2. Steam drum, 3. Downcomer, 4. Furnace, 5. Evaporator 1, 6. Evaporator 2, 7. Superheater, 8. Economizer, 9. Air preheater, 10. Condensate heater, 11. Chimney, 12. Turning flue, 13. Tail flue. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0023] Example: Figure 1 As shown, a slightly superheated gas boiler with hot standby and quick start functions includes a burner 1, a steam drum 2, a furnace 4, a turning flue 12, a tail flue 13 and a chimney 11. A downcomer is connected to the steam drum.

[0024] Evaporator 1 5 and evaporator 2 6 are arranged in sequence in the furnace along the flow direction of the flue gas. The upper and lower ends of evaporator 1 and evaporator 2 are connected to the steam drum and the downcomer through pipelines respectively. In the tail flue 13 after the turning flue 12, the superheater 7, economizer 8, air preheater 9 and condensate heater 10 are arranged in sequence from bottom to top, and the chimney 11 is arranged behind the condensate heater.

[0025] By optimizing the structural layout and water circulation process, this new system keeps the boiler's hot standby load below 5%, maximizing fuel savings and improving energy efficiency when steam demand is insufficient. The unit can be upgraded from hot standby to full boiler load in as little as 5 minutes, enabling timely response to user steam demands. It also offers excellent adaptability to the primary process, avoiding downtime for the primary process unit and delivering significant economic benefits to the owner.

[0026] The burners 1 are arranged in layers on the front wall of the furnace 4, and can be arranged in 1 to 3 layers according to the situation, with 1 to 2 burners arranged on each layer.

[0027] To reduce NOx emissions, the furnace is arranged horizontally, the furnace depth exceeds 10m, and the burner is designed with a longer flame.

[0028] In order to ensure that the drum water level can remain stable during the rapid load increase process and improve the boiler startup rate, drum 2 adopts a large volume design, the water volume is increased, and a certain amount of flash steam is provided in the early stage of load increase.

[0029] In order to ensure the safety of water circulation during the rapid start-up of the boiler, the downcomer 3 is arranged in multiple pieces with large cross-sections, which increases the steam-water flow area, reduces the steam-water flow resistance, and is conducive to the rapid establishment of water circulation.

[0030] In order to improve heat transfer efficiency and reduce boiler steel consumption, finned tube structures can be used for superheaters, economizers and condensate heaters.

[0031] In order to reduce the workload and cost of on-site installation and shorten the construction period of the boiler, the superheater, economizer, air preheater and condensate heater are supplied to the site in a tube box structure. On-site construction only requires lifting them into place.

[0032] The air preheater can adopt a vertical tube box structure, a horizontal tube box structure, a heat pipe structure or a rotary structure.

[0033] In order to reduce the flue gas temperature at the boiler outlet and improve boiler efficiency, the air preheater can be arranged in 1 to 3 stages.

[0034] In order to reduce the steel consumption of the chimney and reduce the area occupied by the boiler, the chimney is supported on the rear frame of the boiler.

[0035] To avoid condensation of steam during transmission, the steam temperature at the boiler outlet is superheated by 3~20℃.

[0036] The embodiment described above is only a preferred solution of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A slightly superheated gas boiler with hot standby and quick start functions, comprising a burner, a steam drum, a furnace, a turning flue, a tail flue and a chimney, wherein a downcomer is connected to the steam drum, and is characterized in that: Evaporator 1 and evaporator 2 are arranged in sequence in the furnace along the flow direction of the flue gas. The upper and lower ends of evaporator 1 and evaporator 2 are connected to the steam drum and the downcomer through pipelines respectively. The superheater, economizer, air preheater and condensate heater are arranged in sequence from bottom to top in the tail flue after the flue is turned. The chimney is arranged behind the condensate heater.

2. A slightly superheated gas boiler with hot standby and quick start functions according to claim 1, characterized in that: The burners are arranged in layers on the front wall of the furnace, and can be arranged in 1 to 3 layers according to the situation, with 1 to 2 burners arranged on each layer.

3. The slightly superheated gas boiler with hot standby and quick start functions according to claim 1 is characterized in that: The furnace is arranged horizontally, and the furnace depth can reach more than 10m.

4. The slightly superheated gas boiler with hot standby and quick start functions according to claim 1 is characterized in that: The downcomers are arranged in multiple pieces.

5. The slightly superheated gas boiler with hot standby and quick start functions according to claim 1 is characterized in that: The superheater, economizer and condensate heater adopt fin tube structure.

6. The slightly superheated gas boiler with hot standby and quick start functions according to claim 1 is characterized in that: The air preheater adopts a vertical pipe box structure, a horizontal pipe box structure, a heat pipe structure or a rotary structure.

7. The slightly superheated gas boiler with hot standby and quick start functions according to claim 1 is characterized in that: The air preheater is arranged in 1 to 3 stages.

8. The slightly superheated gas boiler with hot standby and quick start functions according to claim 1 is characterized in that: The chimney is supported on the boiler rear frame.

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