CN201072138Y - Novel boiler air preheater - Google Patents

Abstract

The utility model discloses a novel boiler air preheater, which comprises two heat exchangers. A smoke exhaust pipeline and an air inlet pipeline are respectively arranged on each heat exchanger, the smoke exhaust pipelines of the two heat exchangers are crosswise communicated through two connecting pipelines, the air inlet pipelines of the two heat exchangers are also crosswise communicated through two connecting pipelines, the smoke exhaust pipelines and the air inlet pipelines are respectively provided with valves at the part between the two connecting pipelines, and valves are respectively arranged on the connecting pipelines. The preheater not only can effectively solve the problem of air leakage, but also has the advantages that the heating speed is quick, the performance is stable, and the maintenance is easy.

Description

New Boiler Air Preheater

technical field

The utility model relates to auxiliary equipment of a boiler, in particular to an air preheater of the boiler.

Background technique

The current boiler air preheaters mainly include tubular air preheaters and rotary air preheaters, which play an important role in improving boiler efficiency. The main problem faced by tubular air preheaters is low-temperature corrosion, while rotary The air leakage of the conventional air preheater is relatively serious, and it is not easy to achieve an air leakage rate of 6%.

Utility model content

Aiming at the air leakage problem of the existing rotary air preheater, the purpose of the utility model is to provide a boiler air preheater with a low air leakage rate.

In order to achieve the above object, the technical solution adopted by the utility model is:

A boiler air preheater, including two heat exchangers, each heat exchanger is provided with a smoke exhaust pipe and an air intake pipe, the smoke exhaust pipes of the two heat exchangers are cross-connected through two connecting pipes, and the two heat exchangers The air intake pipe of the device is also cross-connected through two connecting pipes, the smoke exhaust pipe and the air inlet pipe are respectively provided with valves in the part between the two connecting pipes, and the connecting pipes are also respectively provided with valves.

The unique circuit design of the utility model can make the air and flue gas alternately flow through the two heat exchangers, which can be switched by opening or closing the valve. When the air flows through the first heat exchanger, it is heated by the first heat exchanger. At this time, the flue gas is heating the second heat exchanger. When the air flows through the second heat exchanger, it is heated by the The second heat exchanger heats it while the flue gas is heating the first heat exchanger. The preheater can not only effectively solve the problem of air leakage, but also has beneficial effects such as fast heating speed, stable performance, and easy maintenance.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the utility model.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in further detail.

The reference signs are explained as follows:

11, 22 - heat exchanger

13, 23 - smoke exhaust pipe

14, 24 - intake pipe

15, 25, 15', 25' - connection pipe

16, 17, 26, 27, 18, 28, 18', 28' - valve

As shown in Figure 1, the air preheater is mainly composed of a heat exchanger 11 and a heat exchanger 22. The heat exchanger 11 is provided with a smoke exhaust pipe 13 and an intake pipe 14, and the heat exchanger 22 is provided with a smoke exhaust pipe. The pipe 23 and the air inlet pipe 24, the exhaust pipe 13 and the smoke exhaust pipe 23 are cross-communicated through the connecting pipe 15 and the connecting pipe 25, and the air inlet pipe 14 and the air inlet pipe 24 are cross-communicated through the connecting pipe 15' and the connecting pipe 25', The smoke exhaust pipe 13 and the air intake pipe 14 are respectively provided with a valve 16 and a valve 17 at the part between its two connecting pipes, and the smoke exhaust pipe 23 and the air inlet pipe 24 are respectively provided with a valve 16 at the part between its two connecting pipes. The valve 26 and the valve 27 are respectively provided with the valve 18 and the valve 28 on the connecting pipe 15 and the connecting pipe 25, and are respectively provided with a valve 18' and a valve 28' on the connecting pipe 15' and the connecting pipe 25'. When in use, first the hot flue gas flows through the heat exchanger 11 through the valve 16 and the valve 17, and heats the heat exchanger 11. At the same time, the air flows through the heat exchanger 22 through the valve 26 and the valve 27, and the heat exchanger 22 heats and flows During this process, valve 18, valve 28, valve 18', and valve 28' are all closed to prevent the flue gas from mixing with air. After the heat exchanger absorbs and releases heat sufficiently, valve 18, valve 28 , valve 18', valve 28' are open and valve 16, valve 17, valve 26, valve 27 are closed, at this time the hot flue gas heats the heat exchanger 22 and the heat exchanger 11 heats the air.

The air leakage rate of this modified air preheater is calculated as follows: Assume that the main body length of the heat exchanger is L, the total cross-sectional area is S, and the flow area is S ₁ , and the non-flow area is S ₂ , obviously: S=S ₁ +S ₂ .

If the valve can be closed instantly, the air leakage of the counter blowing preheater is mainly due to the air or flue gas remaining in the gap of the heat exchanger itself after passing through the heat exchanger, then the air leakage rate of the heat exchanger ε Calculated as the ratio of the residual air/flue gas volume to the air/flue gas volume that passes through in one cycle, namely:

$\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; t</span>}}$

Among them, v is the air velocity, and t is the passage time of the air in a working cycle.

Because all the heat released by the airflow is absorbed by the heat exchanger, according to the energy balance:

c _p ·S ₁ ·v·t·ρ _g (T ₁ -T ₂ )＝c·S ₂ ·L·ρ(T ₁ -T ₂ )

Arranged: c _p · S ₁ · v · t · ρ _g = c · S ₂ · L · ρ

Combining the above formula can get:

$\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&rho;</span>}}$

Where c _p is the specific heat capacity of air at constant pressure, ρ _g is the air density, c is the specific heat capacity of the heat exchanger material, and ρ is the density of the heat exchanger material.

According to this formula, the air leakage rate of this kind of blowing air preheater can be easily estimated: the air specific heat capacity is 1.0045, the density is 1.25 (the density of hot flue gas at 500°C under normal pressure is about 0.5), and the material specific heat capacity is 1 (generally greater than 1 ), and the density is 1000 (the actual density should be greater than 1000), if the flow area is equal to the non-flow area, that is, S ₁ = S ₂ , then ε≈0.125%, it can be seen that the air leakage rate of this preheater is very small.

The above is described with the embodiment of two heat exchangers. In actual use, at least two heat exchangers or multiple sets of parallel connection can be used, so no more details will be given here.

The utility model is not limited to the above-mentioned best implementation mode, and anyone can draw other various forms of products under the enlightenment of the present invention. But no matter any changes are made in its shape or structure, all technical solutions identical or similar to the utility model are all within its protection scope.

Claims (1)

1. A novel boiler air preheater is characterized in that it comprises two heat exchangers, each heat exchanger is provided with a smoke exhaust pipe and an air intake pipe, and the smoke exhaust pipes of the two heat exchangers are connected by two The pipes are cross-connected, and the intake pipes of the two heat exchangers are also cross-connected through two connecting pipes. valve.