CN202813420U

CN202813420U - System for raising air temperature of secondary air at inlet of air preheater

Info

Publication number: CN202813420U
Application number: CN201220491704XU
Authority: CN
Inventors: 刘正宁; 李阳; 张鑫; 张春飞; 曹立勇; 郭盼; 张媛; 雷宇
Original assignee: Dongfang Electric Corp
Current assignee: Dongfang Electric Co ltd
Priority date: 2012-09-25
Filing date: 2012-09-25
Publication date: 2013-03-20
Anticipated expiration: 2022-09-25

Abstract

The utility model relates to boiler smoke discharging technology, in particular to a system for raising air temperature of secondary air at an inlet of an air preheater. The system is characterized in that a mixer is arranged in the middle of a secondary air inlet pipeline of the air preheater. A hot air circulation pipeline is arranged at an outlet of a primary air outlet pipeline of the air preheater in a connecting mode and is communicated with the mixer. Primary air is led to the mixer so as to regulate hot air. Through adoption of the structure, the system is little in resistance loss, can effectively raise the air temperature of the secondary air at the inlet of the air preheater, relieves functions of low-temperature corrosion, can effectively reduce the design goal of smoke discharge temperature of a boiler in the design stage of a power plant, can carry out air temperature adjustment according to the actual conditions of the power plants through arrangement of a smoke baffle, and is simple and convenient to operate.

Description

A kind of system that improves air preheater import Secondary Air wind-warm syndrome

Technical field

The utility model relates to the boiler exhaust gas technology, particularly a kind of system that improves air preheater import Secondary Air wind-warm syndrome.

Background technology

Exhaust gas temperature is to affect the topmost factor of boiler efficiency, and the loss of present boiler exhaust gas accounts for more than 4%, so the reduction of exhaust gas temperature has very important significance to the lifting of boiler efficiency.But exhaust gas temperature is crossed the low air preheater generation cold end corrosion that makes easily.On the reason that cold end corrosion occurs, be the size of sulfur content in coal amount on the one hand, this can't change concerning the boiler of selecting fixing coal; Air preheater inlet air temperature and exhaust gas temperature on the other hand.So will reduce to a certain extent exhaust gas temperature to improve boiler efficiency, avoid again cold end corrosion simultaneously, just must improve the air preheater inlet air temperature.

Along with the progressively consumption of coal resources, colm is also adopted by power plant gradually.Especially sulphur coal is also used by some power plant now on a large scale.Using the serious consequence of sulphur coal is easily to cause cold end corrosion.Equipment producer is when designing boiler, and for the consideration to cold end corrosion, often that the exhaust gas temperature design is higher, the design exhaust gas temperature of some boiler of power plant is up to 160 ℃.Calculating shows that exhaust gas temperature reduces by 5 ℃, and boiler efficiency improves more than 1%.If adopt the boiler of power plant exhaust gas temperature of sulphur coal can be reduced to 130 ℃, avoiding under the prerequisite of cold end corrosion, will bring huge economic benefit.

At cold districts such as Xinjiang, the Inner Mongol, especially in the winter time, air themperature is low to moderate below-40 ℃, and so the air of low temperature directly enters air preheater, must cause cold end corrosion.Therefore be in security consideration, must improve the temperature of the inlet air of air preheater, producer generally takes following measures:

(1) steam air heater is installed, namely before cold air enters air preheater, is installed additional a heat exchanger, utilize extracted steam from turbine heating cold wind, air preheater import wind-warm syndrome value is increased to more than 20 ℃.

Said method can improve air preheater import wind-warm syndrome, but can cause following drawback: 1) because the steam air heater thermal source from steam turbine, causes pipe arrangement complicated; 2) because steam is met the condensation knot, so need in the design of steam air heater, consider steam trap connection, cause the steam air heater complex structure; 3) the steam air heater resistance is larger, is generally (300MW unit) about 300Pa; 4) because pressure of extracted steam from turbine is higher, may cause internal pipeline to leak.

(2) adopt hot blast recirculation, namely extract portion of air out from air preheater and enter fans entrance.

The method also can improve the air preheater inlet temperature, but has following problem: 1) hot blast directly enters fans entrance, causes that fans entrance atmospheric density is too small, volume is excessive, has a strong impact on fan operation efficient, causes compressor flow to reduce; 2) high-pressure side (outlet of air preheater device) directly enters low-pressure end (fans entrance), causes crushing larger.

The utility model content

The utility model is for solving the Upgrade Problem of existing station boiler air preheater entrance secondary air temperature, a kind of system that improves air preheater import Secondary Air wind-warm syndrome is provided, system architecture is simple, not only can improve air preheater Secondary Air entrance wind-warm syndrome, can also suppress the generation of cold end corrosion.

For solving the problems of the technologies described above, the technical solution of the utility model is as follows:

A kind of system that improves air preheater import Secondary Air wind-warm syndrome, it is characterized in that: blender is set in the middle of the secondary air inlet pipeline of air preheater, a wind outlet conduit exit at air preheater is connected with a hot air circulate pipeline, the hot air circulate pipeline communication is to blender, the hot blast of a wind outlet conduit is guided in the blender, fully mix with the cold wind of the secondary air inlet pipeline that passes in the blender, obtain the mixing air that temperature is higher than the cold wind of secondary air inlet pipeline, then mixing air is continued to enter into air preheater by the secondary air inlet pipeline, reach the purpose that improves the Secondary Air wind-warm syndrome.

Described hot air circulate install pipeline has gas baffle, and gas baffle can be adjusted the recirculation air quantity according to actual conditions by gas baffle near the junction of hot air circulate pipeline and a wind outlet conduit.

The principle of native system is as follows:

At cold district, the import wind-warm syndrome of the air preheater of station boiler is very low, cold end corrosion is inevitable, therefore, in air preheater Secondary Air porch blender is set, utilize the hot blast of a wind to heat as the cold wind of thermal source to the secondary air inlet of air preheater, improved the inlet temperature of air preheater Secondary Air, effectively prevented the generation of cold end corrosion; Power is provided by wind self pressure head, does not need extra power; If a wind-heat wind undersupply can be regulated the bypass cold wind of a wind blower fan.

The beneficial effects of the utility model are as follows:

The utility model is simple in structure, and SR loss is less, and Secondary Air intake air temperature that can the Effective Raise air preheater has alleviated the cold end corrosion effect; Can be implemented in power plant's design phase, effectively reduce the target of boiler design exhaust gas temperature; By the gas baffle that arranges, can regulate wind-warm syndrome according to each power plant's actual conditions, easy to operate simple.

Description of drawings

Fig. 1 is structural representation of the present utility model;

Wherein, Reference numeral is: 1 air preheater, 2 blenders, 3 wind inlet pipelines, 4 wind outlet conduits, 5 secondary air inlet pipelines, 6 Secondary Air outlet conduits, 7 smoke inlets, 8 exhanst gas outlets, 9 hot air circulate pipelines, 10 gas baffles.

The specific embodiment

As shown in Figure 1, a kind of system that improves air preheater import Secondary Air wind-warm syndrome, the bottom of air preheater 1 is provided with wind inlet pipeline 3 one time, secondary air inlet pipeline 5 and exhanst gas outlet 8, the top of air preheater 1 is provided with wind outlet conduit 4 one time, Secondary Air outlet conduit 6 and smoke inlet 7, in the middle of the secondary air inlet pipeline 5 of air preheater 1, blender 2 is set, wind outlet conduit 4 exits at air preheater 1 are connected with a hot air circulate pipeline 9, hot air circulate pipeline 9 is communicated to blender 2, the hot blast of a wind outlet conduit 4 is guided in the blender 2, fully mix with the cold wind of the secondary air inlet pipeline 5 that passes in the blender 2, obtain the mixing air that temperature is higher than the cold wind of secondary air inlet pipeline 5, then mixing air is continued to enter into air preheater 1 by secondary air inlet pipeline 5, reach the purpose that improves the Secondary Air wind-warm syndrome.

Described hot air circulate pipeline 9 is provided with gas baffle 10, and gas baffle 10 can be adjusted the recirculation air quantity according to actual conditions by gas baffle 10 near the junction of hot air circulate pipeline 9 and a wind outlet conduit 4.

The principle of native system is as follows:

At cold district, the import wind-warm syndrome of the air preheater 1 of station boiler is very low, cold end corrosion is inevitable, therefore, in air preheater 1 Secondary Air porch blender 2 is set, utilize the hot blast of a wind to heat as the cold wind of thermal source to the secondary air inlet of air preheater 1, improved the inlet temperature of air preheater 1 Secondary Air, effectively prevented the generation of cold end corrosion; Power is provided by wind self pressure head, does not need extra power; If wind-heat wind undersupply, (annotate: the hot blast of primary air fan outlet is divided into two-way can to regulate the bypass cold wind of a wind blower fan, one the tunnel enters air preheater 1, another road enters the coal pulverizer preceding pipeline, in order to the coal pulverizer inlet wind-warm syndrome is regulated, need this three transportation work styles amount of operating personnel's reasonable distribution herein).

Claims

1. system that improves air preheater import Secondary Air wind-warm syndrome, it is characterized in that: blender (2) is set in the middle of the secondary air inlet pipeline (5) of air preheater (1), wind outlet conduit (4) exit at air preheater (1) is connected with a hot air circulate pipeline (9), and hot air circulate pipeline (9) is communicated to blender (2).

2. system according to claim 1, it is characterized in that: described hot air circulate pipeline (9) is provided with gas baffle (10), and gas baffle (10) is near the junction of hot air circulate pipeline (9) with a wind outlet conduit (4).