CN102078782A - Method and device for improving internal particle circulation in lift pipe through return air at tower top - Google Patents

Abstract

The invention provides a device and a method for improving the internal circulation of particles in a riser through the return air at the top of the tower. The device includes a riser, the top of the riser is a restraint structure, the side wall of the riser is provided with a fan outlet, and the top side wall of the riser is provided with a return air outlet connected to the restraint structure, and the return air outlet is located above the fan outlet And the return tuyere and the fan outlet are located on the same side of the riser, and a pipe or partition for the return particles to descend is arranged in the riser. The return air is introduced horizontally at the confinement structure at the top of the riser, and the return air flow will carry the particles separated by the confinement structure at the top of the riser downwards, and send them to the bottom of the riser through the pipe or partition for the return particles to descend. The invention effectively utilizes the separation effect of the top constraint structure, and the resistance of the riser system does not increase significantly, and the energy consumption does not increase significantly. It can be used in the fields of chemical industry, grain drying, and flue gas pollutant quality.

Description

Method and device for improving the internal circulation of particles in the riser through the return air at the top of the tower

technical field

The invention relates to a method for improving the internal circulation of particles in a riser, in particular to a method for enhancing the internal circulation of particles through the combination of return air and the restrictive structure at the outlet of the riser. The invention also relates to a riser that improves the internal circulation of particles in the riser.

Background technique

Gas-solid fluidization reaction has become the mainstream of process industry reaction and separation equipment, and occupies an extremely important position in industrial production. At present, major petrochemical companies in the family generally use fluidized catalytic cracking units, and major thermal power generation companies generally use large-scale circulating fluidized bed boilers. application example.

Riser is a common name for a fluidized reactor. Improving the internal circulation effect of particles in the riser has always been a subject of continuous research and development in the industry. Most of the previous measures were achieved by adding internal components and changing the structure of the tower body. Most of these methods have problems such as wear and tear, and are not suitable for materials with high moisture content and high viscosity. The internal circulation enhancement technology of particles has always been a hot and difficult issue in the field of multiphase flow technology research. When the existing riser is in use, the particles that fall back into the tower along the wall of the tower body under the action of the restraint structure have a limited downward depth in the tower body, and are quickly brought to the top of the tower by the upward-flowing airflow, and the circulation effect poor. Therefore, when the existing riser is in use, there is a short residence time of the particles in the riser, which causes the internal circulation effect of the particles in the riser to be poor. In order to prolong the residence time of the particles in the riser, the effective working length of the riser has to be lengthened, so that The working volume of the riser increases, causing problems such as unnecessary waste.

Contents of the invention

The object of the present invention is to provide a device and method for improving the internal circulation of particles in the riser through the return air at the top of the tower, which can prolong the residence time of particles in the riser and improve the internal circulation effect of the particles in the riser.

The purpose of the present invention is achieved like this:

The device for improving the internal circulation of particles in the riser by returning air from the top of the tower of the present invention comprises a riser, the top of the riser is a restraint structure, the side wall of the riser is provided with a fan outlet, and on the top side of the riser There is a return air outlet connected to the restraint structure on the wall, the return air outlet is located above the fan outlet and the return air outlet and the fan outlet are located on the same side of the riser, and a pipe or partition for the return particles to descend is arranged in the riser, and the The above-mentioned pipes or partitions for the downward flow of the return particles are arranged opposite to the return air outlet.

According to the method for increasing the internal circulation of particles in the riser through the return air at the top of the tower, the selected device for improving the internal circulation of the particles in the riser through the return air at the top of the tower includes a riser, the top of the riser is a restraint structure, and the side of the riser There is a fan outlet on the wall, and a return air outlet connected to the restraint structure is provided on the top side wall of the riser. The return air outlet is located above the fan outlet and the return air outlet and the fan outlet are located on the same side of the riser. There are pipes or partitions for the downward flow of the return particles, and the pipes or partitions for the downward flow of the return particles are arranged opposite to the return air outlet; the return air is introduced horizontally at the restraint structure at the top of the riser, and the return air flow will The top of the riser is carried downward by the particles separated by the confinement structure, and sent to the bottom of the riser through the pipe or partition used for the downflow of the particles.

Said horizontal introduction of return air is to lead the outlet gas of the fan of the riser system to the top of the riser.

The horizontally introduced return air is provided by a small blower fan or directly using on-site pneumatically conveyed high-pressure air.

It is best to control the wind speed of the return air to 10-15m/s.

The present invention solves the problems that the particles stay in the riser for a short time when the existing riser is in use, the internal circulation effect of the particles in the riser is poor, and the height of the riser has to be increased in order to prolong the residence time of the particles in the riser.

The technical points of the present invention are as follows: the gas part of the fan outlet of the riser reactor system is introduced back to the top of the riser outlet; a downward circulation channel is arranged on the opposite side of the riser outlet; the gas-solid separation and return is carried out by means of the restraint structure at the top of the riser The pneumatic conveying action of the wind returns the top particles to the lower part of the riser, achieving an enhanced internal circulation of the particles in the riser.

The beneficial effects of the present invention are:

The method of the present invention utilizes the return air and arranges the downward circulation channel on the opposite side of the riser outlet to improve the internal circulation effect of the particles in the riser, relying on the gas-solid separation effect of the restraint structure on the top of the riser and the pneumatic conveying effect of the return air. The top pellets are fed back to the lower portion of the riser, enabling enhanced internal circulation of the pellets in the riser. The method can increase the particle concentration in the riser by 5-10%, increases the particle residence time (equivalent to reducing the height of the riser), and then enhances the internal circulation effect of the riser particles. Under the same reaction parameter conditions, the height of the riser can be appropriately reduced. Reducing the height of the riser is equivalent to reducing the equipment investment cost. At the same time, due to the shortening of the gas flow, the flow resistance of the system can be significantly reduced, thereby realizing the saving of operating power consumption. Calculated only at a gas flow rate of 10m/s, every time the height of the riser is reduced by 1 meter, all resistance losses of 10Pa can be saved, and the energy saving ratio of operation is about 0.03%.

The invention realizes the enhanced internal circulation of the particles by blowing the particles by air, and can be adapted to achieve stable circulation of the particles with a certain moisture content; the invention effectively utilizes the separation effect of the top constraint structure, and the resistance of the riser system does not increase significantly, and there is no obvious energy consumption Increase. The invention can be applied to the fields of chemical industry, grain drying and flue gas pollutant quality.

Description of drawings

Figure 1 is a schematic diagram of the principle of the riser;

Fig. 2 is the A-A sectional view of Fig. 1 (the schematic diagram of particle phase flow in the confinement structure at the top of the tower body);

Fig. 3 is a schematic diagram of the structure and working principle of the device for improving the internal circulation of particles in the riser by returning air from the top of the tower according to the present invention.

Detailed ways

The present invention is described in more detail below in conjunction with accompanying drawing example:

Specific embodiment one: as shown in Figure 3, the specific implementation process of the method for improving the internal circulation of particles in the riser through the return air at the top of the tower described in this embodiment is: Step 1, the constraint structure 1 at the top of the riser 1 The return air is introduced horizontally at -1, and the return air is on the same side as the fan outlet 1-2 of the riser 1, and the wind speed of the return air is controlled to be 3-18m/s; The pipeline or partition 2 where the return particles descend; step 3, use the return air flow to carry the particles separated by the top of the riser 1 relying on the constraint structure 1-1 downward, and pass through the pipeline or partition 2 used for the return particles to descend into the bottom of riser 1.

Specific implementation mode 2: In step 1 of this implementation mode, the method of horizontally introducing return air is: leading the air from the outlet of the fan of the riser system to the top of the riser. The return air blows the particles of the top confinement structure directly to the downlink structure, which can realize the return in the particle tower under the condition of low energy consumption. Other components and connections are the same as those in the first embodiment.

Specific implementation mode 3: In step 1 of this implementation mode, the method of horizontally introducing return air is: using a small fan or directly using on-site pneumatic power to transport high-pressure air to provide the air volume. The return air blows the particles of the top confinement structure directly to the downlink structure, which can realize the return in the particle tower under the condition of low energy consumption. Other components and connections are the same as those in the first embodiment.

Embodiment 4: As shown in FIG. 1 , in step 1 of this embodiment, the wind speed of the return air is controlled to be 5-15 m/s. The return air blows the particles of the top confinement structure directly to the downlink structure, which can realize the return in the particle tower under the condition of low energy consumption. Other components and connections are the same as those in the first embodiment.

Specific embodiment five: as shown in Figure 3, the special device for realizing the above method described in this embodiment includes a riser 1, the top of the riser 1 is a restraint structure 1-1, and the side wall of the riser 1 There is a fan outlet 1-2 on the top, and a return air outlet 1-3 communicated with the restraint structure 1-1 is provided on the top side wall of the riser 1. The return air outlet 1-3 is located above the fan outlet 1-2 and returns The tuyere 1-3 and the fan outlet 1-2 are located on the same side of the riser 1, and a pipe or partition 2 for the downward flow of the return particles is arranged in the riser 1, and the pipe or partition 2 for the return flow of the particles downward Set opposite to return air outlet 1-3. The device of the invention has a simple structure and is easy to realize.

Principle of the present invention is analyzed as follows:

The flow situation at the top of the riser in the prior art is as follows: the air flow flows out along the horizontal outlet after reaching the top outlet, and some particles continue to move upward, and after hitting the top glass plate, they begin to diffuse toward the walls of the tower body in a petal shape, as shown in Figure 1 , the particles on the outlet side are taken away by the horizontal airflow, and the particles on the other three sides fall back into the tower along the wall of the tower body, but their descending depth is limited, and they are quickly brought to the top of the tower.

The present invention guides the gas from the fan outlet of the riser system to the top of the riser (a small fan can also be added or directly use the on-site pneumatic power to transport high-pressure air to provide the air volume). The top of the tube is fed horizontally from the outlet side to the opposite side of the outlet. The air flow is used to carry the particles separated by the restraint structure at the top of the riser, and send them to the bottom of the riser through the downpipe (the pipe or partition 2 used for the downflow of the return particles), thereby enhancing the internal circulation effect of the riser particles.

The top circulation gas flow rate is directly related to the diameter of the tower body: the calculation method is as follows:

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;r</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}}$

In the formula:

Qz is the total flue gas volume, Nm3/h;

r- is the equivalent diameter, m;

α-correction coefficient, generally take 1-2, take 1 when the moisture content of the granular material is less than 10%, take 1.5 when the moisture content is less than 18%; take 2 when the moisture content is less than 22%;

ε- is an empirical coefficient, generally 0.2-0.4; when the return gas pressure is less than 2000Pa, choose a larger value; when the return gas lift pressure is higher than 2000Pa, you can take a smaller value.

Claims (5)

1. one kind is passed through the device that cat head loopback wind improves circulation in the riser endoparticle, comprise riser, it is characterized in that: the top of described riser is a restraining structure, the sidewall of described riser is provided with the blower fan outlet, on the sidewall of the top of riser, be provided with a loopback air port that communicates with restraining structure, top and loopback air port that the loopback air port is positioned at blower fan outlet export the same side that is positioned at riser with blower fan, in riser, be provided with and be used to reflux particle descending pipeline or dividing plate, and the descending pipeline of the described particle that is used to reflux or dividing plate and loopback air port are oppositely arranged.

2. one kind is passed through the method that cat head loopback wind improves circulation in the riser endoparticle, it is characterized in that: the device of selecting for use that passes through to circulate in the cat head loopback wind raising riser endoparticle comprises riser, the top of riser is a restraining structure, the sidewall of riser is provided with the blower fan outlet, on the sidewall of the top of riser, be provided with a loopback air port that communicates with restraining structure, top and loopback air port that the loopback air port is positioned at blower fan outlet export the same side that is positioned at riser with blower fan, in riser, be provided with and be used to reflux particle descending pipeline or dividing plate, and the descending pipeline of the described particle that is used to reflux or dividing plate and loopback air port are oppositely arranged; Level is introduced loopback wind at the restraining structure place at the top of riser, and loopback general mood stream carries the particle that the riser top relies on restraining structure to separate downwards, and particle descending pipeline or dividing plate are sent into the riser bottom through being used to reflux.

3. the method by circulation in the cat head loopback wind raising riser endoparticle according to claim 2, it is characterized in that: it is riser system fan exit gas to be drawn deliver to the riser top that described level is introduced loopback wind.

4. the method by circulation in the cat head loopback wind raising riser endoparticle according to claim 2 is characterized in that: it is to adopt a small-sized fan or directly utilize on-the-spot strength conveying pressure-air that wind regime is provided that described level is introduced loopback wind.

5. according to claim 2,3 or 4 described methods by circulating in the cat head loopback wind raising riser endoparticle, it is characterized in that: the wind speed of control loopback wind is 10-15m/s.

Images