CN103292607B - Heat storage and exchange method used for recovering waste heat of smoke with flying ash - Google Patents

Abstract

A heat storage and heat exchange method for recovering waste heat of flue gas containing fly ash in the technical field of waste heat recovery from flue gas, by setting an air chamber before the flue gas containing fly ash enters the heat storage chamber to reduce the amount of fly ash entering the heat storage chamber Ash, and a nozzle is installed at the air inlet of the air chamber to accelerate the speed of the flue gas. The flue gas enters the refractory ball bed layer of the regenerator and blows the refractory balls to increase the gap between the refractory balls. The bed layer of refractory balls forms a fluidized bed, and the heat exchange between the flue gas and the refractory balls makes the heat stored in the refractory balls, and the fly ash entering the regenerator flows out of the regenerator, so as to avoid blocking the circulation channel. The invention has simple structural design and operation, low ash removal cost, and is especially suitable for occasions with high ash content in flue gas.

Description

Heat storage and heat exchange method for recovering waste heat of flue gas containing fly ash

technical field

The invention relates to a method in the technical field of waste heat recovery from flue gas, in particular to a heat storage and heat exchange method for recovering waste heat from flue gas containing fly ash. the

Background technique

High-temperature air combustion technology is widely used in metallurgy, machinery, chemical industry, solid waste treatment and other fields, and has the advantages of uniform combustion/heating, high thermal efficiency, and low _NOx emissions. The core component of this technology is the heat storage and heat exchange device, which adopts fast reversing operation, which can greatly recover the heat of high-temperature flue gas and use it to preheat combustion-supporting gas and fuel. The heat storage and heat exchange device is equipped with two or more paired regenerators, which are filled with randomly piled refractory balls or directly use refractory honeycomb bodies to store or release heat in the form of fixed beds. Taking a device with two regenerators as an example, one regenerator has a lower temperature and is a cold regenerator; the other has a higher temperature and is a hot regenerator. While the flue gas passes through the cold regenerator, the cold gas to be preheated passes through the hot regenerator. After a certain period of time, the temperature of the cold regenerator rises and becomes a hot regenerator, while the temperature of the hot regenerator decreases. Become a cold heat storage chamber. Then change the flow direction of the hot and cold gas through the reversing valve, so that the hot gas enters the new cold regenerator to release heat, and the cold gas enters the new hot regenerator to absorb heat, so that the heat is continuously transferred from the flue gas to the preheated gas. transfer.

However, the high-temperature air combustion technology is currently only successfully applied in the combustion of gaseous fuels, and its application in the combustion of ash-containing solid fuels such as coal powder/granules, biomass, and garbage is limited. The reason is that the regenerator used to recover the waste heat of the flue gas and preheat the combustion-supporting air and fuel is easily blocked by the fly ash carried in the flue gas, resulting in unstable operation and high maintenance costs. Especially when the ceramic honeycomb body is used as the heat storage body, once the narrow channel of the honeycomb body is blocked by fly ash, it is extremely difficult to clean it. If the refractory ball is used as the heat storage body, it is easier to clean, but it needs to be removed and replaced frequently, which is not conducive to the stability of the system and the reduction of cost. the

After searching the prior art, it was found that Chinese patent document number CN202499873, published on 2012-10-24, records an improved spherical hot blast stove, which consists of a furnace body, a furnace cavity, a combustion port installed on the furnace wall, Ball loading hole, two upper and lower ball unloading holes and brick unloading hole, dust cleaning hole, cold air pipe and hot air pipe. The upper part of the furnace cavity is the combustion chamber, and the lower part is the heat storage chamber. There is a refractory ball furnace bar at the position from the loading and unloading ball hole to the position below the hot air outlet; Under the condition of the same total heating area, the volume of the regenerator of the spherical hot blast stove is much smaller. The refractory ball is installed above the inclined grate, and it is extremely convenient and fast when the refractory ball needs to be unloaded. At the same time, the movement of gas in the pebble bed and checker brick chamber is an irregular turbulent movement, and its horizontal and vertical multi-dimensional surfaces are all involved in heat exchange. But the defect and deficiency of this prior art compared with the present invention are: when gas contains more fly ash, after flowing through checker brick and pebble bed described in this prior art, fly ash can be deposited in checker brick aperture And in the pebble bed, if it is serious, it will cause blockage, so that the regenerator cannot work, and the furnace needs to be frequently shut down for cleaning. The invention can greatly reduce or avoid the deposition of fly ash in the gas in the regenerator. the

Contents of the invention

The present invention aims at the above-mentioned deficiencies in the prior art, and provides a heat storage and heat exchange method for recovering the waste heat of flue gas containing fly ash, so that the high-temperature air combustion technology can be used in the occasion of burning solid fuels, and the advantages of the technology can be fully utilized. Advantage. the

The present invention is achieved through the following technical solutions:

The invention provides a heat storage and heat exchange method for recovering the waste heat of flue gas containing fly ash, by setting an air chamber before the flue gas containing fly ash enters the heat storage chamber to reduce the fly ash entering the heat storage chamber, and The air inlet of the air chamber is provided with a nozzle to accelerate the traveling speed of the flue gas, and the flue gas enters the refractory ball bed layer of the regenerator, blowing the refractory balls, so that the gap between the refractory balls increases, and the refractory ball bed layer A fluidized bed is formed, heat is exchanged between the flue gas and the refractory balls so that the heat is stored in the refractory balls, and the fly ash entering the regenerator flows out of the regenerator, so as to avoid blocking the circulation channel. the

The purpose of accelerating the travel speed of the flue gas is to fluidize the refractory pebble bed layer of the regenerator, and the flue gas velocity needs to reach 1.5 to 10 times the critical fluidization velocity. The calculation formula of the critical fluidization velocity is:

$u_{\mathrm{mg}}=\frac{\mathrm{\μ}}{d_p{\mathrm{\ρ}}_g}(\sqrt{{33.7}^2+0.0408\frac{d_p^3{\mathrm{\ρ}}_g({\mathrm{\ρ}}_p-{\mathrm{\ρ}}_g)g}{{\mathrm{\μ}}^2}}-33.7),$ Among them, u _mg is the critical fluidization velocity, d _p is the diameter of the refractory ball, μ is the dynamic viscosity, ρ _g is the smoke density, ρ _p is the density of the refractory ball, and g is the acceleration of gravity.

The way to reduce the fly ash entering the regenerator is: install an air chamber before the regenerator and install an air distribution plate at the entrance of the regenerator, when the flue gas containing fly ash enters the air chamber and flows through the cloth When the wind plate is installed, due to the pressure difference and the blocking of the air distribution plate, the speed of part of the fly ash is reduced and deposited in the air chamber. the

The air chamber can make the flue gas mix evenly therein, avoiding the uneven flow in the subsequent refractory balls caused by the difference in gas inlet pressure and velocity. the

The method for accelerating the speed of the flue gas is as follows: a nozzle is arranged at the air inlet of the air chamber and a number of through holes are evenly opened on the air distribution plate. Trapezoidal structure with narrow exit. the

The total area A _hole of all through-hole outlets on the air distribution plate is calculated according to the flue gas volume flow rate and the selected flue gas velocity, and the formula is: Among them, V _g is the flue gas volume flow rate, and u is the flue gas velocity.

The diameter of the outlet of a single through hole on the air distribution plate is 0.5 to 1.0 times the diameter of the refractory ball, and 0.75 to 0.8 times the diameter of the inlet. the

The outlet area of the nozzle at the air inlet of the air chamber is equal to the total area A of the through hole outlet of the air distribution plate, and the outlet diameter of _{the nozzle} is 0.75 to 0.8 times the diameter of the inlet.

Both the flue gas velocity at the exit of the nozzle and the flue gas velocity at the outlet of the through hole of the air distribution plate can reach twice the velocity of the inlet flue gas. the

In the fluidized state, the heat exchange between the flue gas and the refractory ball is mainly through convection and radiation. When the temperature of the flue gas decreases by ΔT _g , the following heat balance equation is satisfied:

${\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; pg</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

Among them, c _pg is the specific heat capacity of the flue gas, T _g is the flue gas temperature, α is the convective heat transfer coefficient, a is the specific surface area of the bed, A ₀ is the cross-sectional area of the regenerator, and ΔH is the corresponding value when the flue gas temperature decreases by ΔT _g Bed height, T _p is the temperature of refractory balls, ε _p is the blackness of refractory balls, σ is the Stefan-Boltzmann constant, ε is the bed porosity, n is the number of refractory balls, V _p is the volume of refractory balls, H is the total height of the bed; the formula for convective heat transfer coefficient α is:

Nu＝0.03Re ^1.3 0.1<Re<100

Nu＝2+0.6Re ^1/2 Pr ^1/3 Re>100,

Among them, Nu is the Nusselt number, Nu=αd _p /λ _g , λ _g is the thermal conductivity of the flue gas; Re is the Reynolds number, Re=ud _p ρ _g /μ; Pr is the Prandtl number, Pr=c _pg μ/λ _g .

It can be seen from the calculation formula that the higher the flue gas velocity, the larger the Reynolds number and the larger the convective heat transfer coefficient α, indicating the higher the heat transfer intensity. When convective heat transfer and radiation heat transfer are considered at the same time, the heat transfer coefficient between the flue gas and the refractory ball can reach 200-400W/(m2·℃). the

The refractory ball has a density of 700-1000kg/m3, a specific heat capacity of 0.8-1.1kJ/(kg·°C), and a diameter of 5-10mm. Refractory balls have high heat storage capacity, and the smaller the diameter, the larger the specific surface area involved in heat exchange. the

The present invention relates to a device for realizing the above-mentioned heat storage and heat exchange method, comprising: a regenerator, an air chamber, an air distribution plate and a refractory ball, wherein: an air distribution plate is provided at the entrance of the regenerator, and an air chamber is provided in front , There are refractory balls in the circulation channel of the regenerator. the

A nozzle is provided at the air inlet of the air chamber, and the structure of the nozzle is a trapezoidal structure with a wide inlet at the bottom and a narrow outlet at the top. the

A plurality of through holes are evenly opened on the air distribution plate, and the structure of the through holes is a trapezoidal structure with a wide entrance at the bottom and a narrow exit at the top. the

The diameter of the outlet of a single through hole on the air distribution plate is 0.5 to 1.0 times the diameter of the refractory ball, and 0.75 to 0.8 times the diameter of the inlet. the

The outlet area of the nozzle at the air inlet of the air chamber is equal to the total area A of the through hole outlet of the air distribution plate, and the outlet diameter of _{the nozzle} is 0.75 to 0.8 times the diameter of the inlet.

The outside of the heat storage chamber is provided with an insulation layer. the

In the present invention, an air chamber and an air distribution plate are arranged before the regenerator to block a part of the fly ash; the rest of the fly ash enters the bed of refractory balls along with the flue gas, and the flue gas blows the refractory balls, the gap between the balls increases, and even reaches a fluidized state , at this time, the refractory ball bed can be approximated as a fluidized bed, which absorbs and stores the heat of the flue gas through heat exchange, and the fly ash in the flue gas can still flow with the flue gas due to the increased circulation channels in the bed. Flow out of the regenerator; when heating the combustion-supporting gas or fuel gas, the gas can be fed into the thermal regenerator from top to bottom. At this time, the refractory ball packed bed can be regarded as a fixed bed, and the accumulated heat is transferred to the preheated gas. the

technical effect

The invention realizes the first ash removal of the flue gas in front of the refractory pebble bed by setting the air chamber and the air distribution plate, and realizes the fly ash in the flue gas flowing out of the regenerator through the fluidization of the refractory pebble bed, effectively avoiding the fly ash in the regenerator. The channel is deposited and blocked in the bed; nozzles are installed at the air inlet of the air chamber, and a number of through holes are evenly opened on the air distribution plate to increase the flow rate of the flue gas, creating conditions for the fluidization of the refractory pebble bed; the flue gas and The fluidized bed of refractory balls performs strong convection and radiation heat exchange, which realizes the transfer of heat from flue gas to refractory balls. The invention has simple structural design and operation, low ash removal cost, and is especially suitable for occasions with high ash content in flue gas. the

Description of drawings

Fig. 1 is a schematic diagram of the device structure of the present invention. the

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example. the

Example 1

As shown in Figure 1, the method of this embodiment is specifically: first, before the flue gas containing fly ash enters the regenerator, reduce the fly ash entering the regenerator; The bed of refractory balls 4 in the regenerator blows the refractory balls 4, so that the gap between the refractory balls 4 increases, and the bed of refractory balls 4 forms a fluidized bed, and the heat exchange between the flue gas and the refractory balls 4 makes the heat The fly ash stored in the refractory ball 4 and entering the regenerator flows out of the regenerator, so as to avoid blocking the circulation channel. the

The way to reduce the fly ash entering the regenerator is: install an air chamber 2 before the regenerator, and at the same time, install an air distribution plate 3 at the entrance of the regenerator, when the flue gas containing fly ash enters the air chamber 2 And when it flows through the air distribution plate 3, due to the pressure difference and the blocking of the air distribution plate 3, the speed of some fly ash is reduced and deposited in the air chamber 2. the

At the same time, the air chamber 2 allows the flue gas to mix uniformly therein, avoiding uneven flow in the subsequent refractory ball 4 due to the difference in gas inlet pressure and velocity. the

The method of accelerating the speed of the flue gas is: the air inlet of the air chamber 2 is provided with a nozzle, and the air distribution plate 3 is evenly opened with a number of through holes. A trapezoidal structure with a narrow upper exit. the

The diameter of the outlet of a single through hole on the air distribution plate 3 is 0.5 to 1.0 times the diameter of the refractory ball 4 and 0.75 to 0.8 times the diameter of the inlet. The outlet area of the nozzle 1 at the air inlet of the air chamber 2 is equal to the total area of the through hole outlet of the air distribution plate 3, and the outlet diameter of the nozzle 1 is 0.75-0.8 times of the inlet diameter. Both the flue gas velocity at the outlet of the nozzle 1 and the flue gas velocity at the outlet of the through hole of the air distribution plate 3 can reach about twice the velocity of the inlet flue gas. the

The refractory ball 4 has a density of 700-1000kg/m3, a specific heat capacity of 0.8-1.1kJ/(kg·°C), and a diameter of 5-10mm. The heat transfer coefficient between the flue gas and the refractory ball 4 can reach 200-400W/(m2·°C). the

In the fluidized state, the flue gas velocity reaches 1.5 to 10 times the critical fluidization velocity. The formula for calculating the critical fluidization velocity is:

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; mg</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}<span\; class="notranslate">\; (</span>\sqrt{{\mathrm{<span\; class="notranslate">\; 33.7</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.0408</span>}\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; g</span>}}{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 33.7</span>}<span\; class="notranslate">\; )</span>$

In the formula, u _mg is the critical fluidization velocity, d _p is the diameter of the refractory ball 4, μ is the dynamic viscosity, ρ _g is the smoke density, ρ _p is the density of the refractory ball 4, and g is the acceleration of gravity. According to the flue gas volume flow rate and flue gas velocity, the total area of the through-hole outlet on the air distribution plate 3 can be calculated. A _{hole, air distribution plate} , the calculation formula is:

In the formula, V _g is the flue gas volume flow rate, and u is the flue gas velocity.

During heat exchange, when the flue gas temperature decreases by ΔT _g , the following heat balance equation is satisfied between the flue gas and the refractory ball 4:

${\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; pg</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; )</span>$

in, $a=\frac{6(1-\mathrm{\&epsiv;})}{d_p},$ $\mathrm{\&epsiv;}=1-\frac{\mathrm{no}{V}_p}{A_{0}h}.$

In the above formula, c _pg is the specific heat capacity of the flue gas, T _g is the temperature of the flue gas, α is the convective heat transfer coefficient, a is the specific surface area of the bed, A ₀ is the cross-sectional area of the regenerator, and ΔH is when the temperature of the flue gas decreases by ΔT _g The corresponding bed height, T _p is the temperature of the refractory ball 4, ε _p is the blackness of the refractory ball 4, σ is the Stefan-Boltzmann constant, ε is the bed porosity, and n is the number of the refractory ball 4 , V _p is the volume of the refractory ball 4, and H is the total height of the bed. The formula for calculating the convective heat transfer coefficient α is:

Nu＝0.03Re ^1.3 0.1<Re<100

Nu＝2+0.6Re ^1/2 Pr ^1/3 Re>100

Among them, Nu is the Nusselt number, Nu=αd _p /λ _g , λ _g is the thermal conductivity of the flue gas; Re is the Reynolds number, Re=ud _p ρ _g /μ; Pr is the Prandtl number, Pr=c _pg μ/λ _g .

Example 2

This embodiment is a device based on the method of Embodiment 1, as shown in Figure 1, including: a regenerator, an air chamber 2, an air distribution plate 3 and a refractory ball 4, wherein: the entrance of the regenerator is provided with an air distribution plate 3. There is an air chamber 2 in front, and a refractory ball 4 is arranged in the circulation channel of the regenerator. the

The air inlet of the air chamber 2 is provided with a nozzle, and the structure of the nozzle is a trapezoidal structure with a wide inlet at the bottom and a narrow outlet at the top. the

Evenly have some through-holes on the described air distribution plate 3, the structure of this through-hole is the trapezoidal structure that bottom entrance is wide and top exit is narrow. the

The outside of the heat storage chamber is provided with an insulating layer 5 . the

The flue gas containing fly ash enters the air chamber 2 from the nozzle 1, and after being uniformly mixed therein, part of the fly ash settles in the air chamber 2, and the rest of the fly ash passes through the air distribution plate 3 along with the hot flue gas. Evenly open holes on the air distribution plate 3 . Through the flattening of the air distribution plate 3 and the acceleration of the nozzle, the hot flue gas enters the bed of refractory balls 4 . The high-speed hot flue gas blows the refractory balls 4 to increase the distance between the refractory balls 4, and the fly ash in the flue gas can easily pass through the bed of the refractory balls 4. There is a strong heat exchange between the hot flue gas and the refractory ball 4, and the heat is stored in the refractory ball 4. Thermal insulation layer 5 is arranged outside the heat storage, which can reduce the loss of heat. After the flue gas transfers heat to the refractory ball 4, it carries the fly ash out of the regenerator from the air outlet 6, so as to recover the heat of the flue gas, and at the same time, the fly ash will not be deposited in the refractory ball 4 bed, avoiding frequent unloading of the ball Ash removal. the

Claims (10)

1. A heat storage and heat exchange method for reclaiming waste heat of flue gas containing fly ash, characterized in that, before the flue gas containing fly ash enters the heat storage chamber, an air chamber is set to reduce the fly ash entering the heat storage chamber , and a nozzle is set at the air inlet of the air chamber to accelerate the speed of the flue gas, the flue gas enters the refractory ball bed layer of the regenerator, and blows the refractory balls, so that the gap between the refractory balls increases, and the refractory The pebble bed layer forms a fluidized bed, and the heat exchange between the flue gas and the refractory balls makes the heat stored in the refractory balls, and the fly ash entering the regenerator flows out of the regenerator, so as to avoid blocking the circulation channel. 2. The method according to claim 1, characterized in that, the speed of advancing of the accelerated flue gas refers to: the refractory pebble bed layer of the regenerator is fluidized, and the flue gas velocity reaches the critical fluidization velocity. 1.5 to 10 times, the calculation formula of the critical fluidization velocity is: $u_{\mathrm{mg}}=\frac{\mathrm{\&mu;}}{d_p{\mathrm{\&rho;}}_g}(\sqrt{{33.7}^2+0.0408\frac{d_p^3{\mathrm{\&rho;}}_g({\mathrm{\&rho;}}_p-{\mathrm{\&rho;}}_g)g}{{\mathrm{\&mu;}}^2}}-33.7),$ Among them, u _mg is the critical fluidization velocity, d _p is the diameter of the refractory ball, μ is the dynamic viscosity, ρ _g is the smoke density, ρ _p is the density of the refractory ball, and g is the acceleration of gravity. 3. The method according to claim 1, characterized in that the reduction of fly ash entering the regenerator refers to: installing an air chamber before the regenerator, and at the same time, installing an air distribution plate at the entrance of the regenerator , when the flue gas containing fly ash enters the air chamber and flows through the air distribution plate, due to the pressure difference and the blocking of the air distribution plate, part of the fly ash velocity is reduced and deposited in the air chamber. 4. The method according to claim 1, 2 or 3, characterized in that the traveling speed of the accelerated flue gas is realized by the following method: a nozzle is set at the air inlet of the air chamber, and the air distribution plate is evenly opened. There are several through holes, and the structure of the nozzle pipe and the through holes is a trapezoidal structure with a wide entrance at the bottom and a narrow exit at the top. 5. The method according to claim 4, characterized in that, the total area A _{hole of all said through holes on the air distribution plate, the air distribution plate} is calculated according to the flue gas volume flow rate and the selected flue gas velocity, the formula is : Among them, V _g is the flue gas volume flow rate, and u is the flue gas velocity. 6. The method according to claim 4, characterized in that, in the fluidized state, the heat exchange between the flue gas and the refractory ball is mainly through convection and radiation, and when the temperature of the flue gas decreases by ΔT _g , the following heat balance equation is satisfied : ${\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; pg</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$ Among them, c _pg is the specific heat capacity of the flue gas, T _g is the flue gas temperature, α is the convective heat transfer coefficient, a is the specific surface area of the bed, A ₀ is the cross-sectional area of the regenerator _{, and} ΔH is the corresponding value when the flue gas temperature decreases by ΔT _g Bed height, T _p is the temperature of refractory balls, ε _p is the blackness of refractory balls, σ is the Stefan-Boltzmann constant, ε is the bed porosity, n is the number of refractory balls, V _p is the volume of refractory balls, H is the total height of the bed; the formula for convective heat transfer coefficient α is: Nu=0.03Re ^1.3 0.1<Re<100, Nu＝2+0.6Re ^1/2 Pr ^1/3 Re>100 Among them, Nu is the Nusselt number, Nu=αd _p /λ _g , λ _g is the thermal conductivity of the flue gas; Re is the Reynolds number, Re=ud _p ρ _g /μ; Pr is the Prandtl number, Pr=c _pg μ/λ _g . 7. A device for implementing the heat storage and heat exchange method according to claim 4 or 5, characterized in that it comprises: a regenerator, an air chamber, an air distribution plate and a refractory ball, wherein: the entrance of the regenerator is provided with The air distribution plate is provided with an air chamber in front, and a refractory ball is arranged in the circulation channel of the regenerator. 8. The device according to claim 7, characterized in that, the air inlet of the air chamber is provided with a nozzle, and the structure of the nozzle is a trapezoidal structure with a wide inlet at the bottom and a narrow outlet at the top. 9. The device according to claim 7, wherein a plurality of through holes are evenly opened on the air distribution plate, and the structure of the through holes is a trapezoidal structure with a wide entrance at the bottom and a narrow exit at the top. 10. The device according to claim 9, wherein the diameter of the outlet of the single through hole on the air distribution plate is 0.5-1.0 times the diameter of the refractory ball, and 0.75-0.8 times the diameter of the inlet.