JPS5847230Y2 - Blast furnace exhaust gas energy recovery device - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a device for recovering exhaust gas energy from a blast furnace.

Blast furnaces generate large quantities of exhaust gases, which contain significant amounts of thermal and mechanical energy, and simply releasing them into the atmosphere would waste a valuable energy source. This results in

By the way, conventionally, there are two methods for recovering the pressure energy of blast furnace gas: one using a centripetal turbine and the other using an axial flow turbine.

The former method involves passing gas that has been washed with water and saturated with water vapor through a centripetal turbine to remove dust, but this method requires large equipment and high equipment costs, as well as relatively low efficiency and low energy consumption. This is accompanied by the essential drawback that the recovery rate is not good.

On the other hand, although the latter method has the essential advantage that the axial flow turbine is smaller and more efficient than the centripetal turbine, the efficiency decreases due to dust sticking to the nozzle and rotor blades, and the nozzle is blocked by dust. However, this was not possible because problems such as vibration caused by dust attached to the rotor blades remained unresolved.

Therefore, in conventional axial flow turbine systems, it is necessary to completely remove dust to prevent erosion of the turbine blades, and to prevent dust from sticking and accumulating on the nozzles and rotor blades. It was necessary to heat it to dry it completely.

Therefore, in addition to requiring a partial combustion device or a heat exchanger for blast furnace gas, dry dust also has the disadvantage that it causes more wear on the turbine blades than dust wrapped in moisture.

As mentioned above, the present invention aims to efficiently recover energy from blast furnace exhaust gas using an axial flow turbine, which has various advantages that are essentially superior to centripetal turbines. This method eliminates the sticking and accumulation of dust on the nozzle and rotor blades, which is the biggest disadvantage of the method, and also does not cause erosion, and provides stable performance over a long period of time, making full use of the essential advantages of the axial flow turbine method. The purpose of the present invention is to provide a blast furnace gas energy recovery device that can perform the following steps.

To achieve this objective, the present invention aims to prevent the dust contained in the exhaust gas from adhering to the nozzles, rotor blades, etc. when recovering energy from the exhaust gas of a blast furnace, and to prevent the dust contained in the exhaust gas from adhering to the nozzles, moving blades, etc. It is characterized by being able to prevent the occurrence of erosion caused by.

That is, the present invention includes a blast furnace, a dust catcher connected to the top of the blast furnace by a duct, a venturi scrubber connected to the dust catcher by a duct, a nuclear venturi scrubber, an inlet blocking valve, and an inlet emergency valve. The axial flow turbine is connected to an axial flow turbine whose inlet side is connected by a duct through a shutoff valve and a speed control valve, water sprayers are provided before and after the speed control valve, and a driven machine is connected to the axial flow turbine, and on the other hand, The venturi scrubber is provided with a bypass duct leading to the outside of the system via a septan valve, and the bypass duct on the outlet side of the septan valve is used as a duct leading from the outlet side of the axial flow turbine to the outlet stop valve via an outlet stop valve. The height and chord length ratios of the nozzle and rotor blade of the axial flow turbine are substantially equal, the number of turbine stages is increased, and the thickness of the trailing edge of the nozzle and rotor blade is increased by 8 to 10 degrees. , the circumferential speed of the first rotor blade is 150 to 180 m.
/s, and the outlet of the nozzle and the outlet of the rotor blade are set in the same direction to generate a swirling flow that toss the turbine shaft in the gas flow, while the casing of the axial turbine This is a blast furnace exhaust gas energy recovery device characterized in that a slit is provided perpendicularly to the turbine axis of the blast furnace.

In other words, after saturating the exhaust gas containing dust from the blast furnace with water vapor, the saturated gas is continuously sprayed with a large amount of water before it enters the axial flow turbine. In addition to the cleaning action of the water mist itself, the cooling action of the water provides a sufficient water spray to the axial turbine to condense the supersaturated water vapor and envelop the dust before it enters the axial turbine. By doing this upstream, it prevents dust from sticking and accumulating on the blades, and also reduces the ratio between the height and chord length of the nozzle and rotor blades, creating a stubby shape, and increasing the number of stages to reduce dust. In addition to preventing insects from adhering to the dust and preventing erosion due to increased mist, the system also generates a swirling gas flow around the turbine shaft to quickly separate dust and mist using centrifugal force, thereby solving previously unsolved problems. were solved all at once.

The present invention will be further described below with reference to embodiments shown in the accompanying drawings.

FIG. 1 is a system diagram showing an embodiment of a blast furnace exhaust gas energy recovery device according to the present invention, in which exhaust gas discharged from a blast furnace 1 is led to a dust catcher 3 via a duct 2, and then to a duct 4. The water is then sent to a venturi scrubber, that is, a moisture and dust remover 5.

In the moisture remover 5, the blast furnace gas is saturated with steam as a first stage.

For example, if the blast furnace gas is normal and the temperature is about 150℃
, about 2 atmospheres (gauge), the gas a1 is saturated with water vapor at about 60° C. by cooling by evaporation of water in the moisture remover 5.

This saturated gas a1 is further supplied to the duct 6, the inlet blocking valve 1, the duct 8, the inlet valve 9, the duct 10, and the regulating valve 1.
1. It flows into the axial flow turbine 13 through the duct 12 and is used as a driving power source for driving the driven machine 14 connected to the axial flow turbine 13.

In that case, the saturated gas a1 is continuously sprayed with a large amount of water in the ducts 10 and 12 according to the present invention as described later, and becomes supersaturated gas a2, and the gas a2 discharged from the axial flow turbine 13 is It is further guided through the duct 15, the outlet stop valve 16, the duct 1T, the outlet stop valve 18, and the duct 19, and is discharged out of the system through the duct 20.

On the other hand, the saturated gas a1 bypassed from the wet dust remover 5 via the bypass duct 2L septan valve 22 is the gas a2
At the same time, it can also be discharged from the duct 20 to the outside of the system.

In the blast furnace gas flow system as described above, according to the present invention, before the gas a1 saturated with water vapor in the wet dust remover 5 enters the axial flow turbine 13, a large amount of low-temperature water is added to the saturated gas a1. A pump 23 is provided for continuous spraying.

That is, the pump 23 is connected to the duct 10 via the duct 24 and to the duct 1 via the duct 25 to add spray water to the saturated gas a1 upstream of the axial turbine 13.
2 are connected to each other.

However, in the embodiment shown in FIG. 1, the spray water is also sprayed on the duct 10 upstream of the speed regulating valve 11 in order to clean the speed regulating valve 11, but this is omitted and the duct 2
5 may be used alone, or as long as it is upstream of the axial flow turbine 13, it may be sprayed at other locations as well.

In either case, the saturated gas a1 is condensed into a mist of condensed water vapor and the dust in the gas as a core by the action of low-temperature spray water, and the saturated steam surrounds the dust core. It becomes a state of enveloping.

When dust wrapped in a layer of water like a double-layered microsphere is captured inside a turbine, the layer of water acts as a kind of cushioning material and the dust adheres directly to the inner wall of the turbine. This will be prevented.

Furthermore, the minute mist generated by the condensation of water vapor by spraying low-temperature water onto the water vapor saturated gas a1 has a small inertia, so it flows in almost the same way as the gas flow within the blade row of the axial flow turbine 13, and the concave surface of the nozzle, Since it flows along the convex surface, it has the effect of preventing dust from adhering.

Historically, in this invention, the following structural considerations have been made to the axial flow turbine 13 in order to prevent dust from adhering to the axial flow turbine 13 and to prevent erosion from occurring due to an increase in mist due to continuous water spraying. are paying.

(1) That is, in the present invention, the ratio of the height and chord length of the nozzle and rotor blade of an axial flow turbine is reduced from the usual 2 to 3 to about 1.

In other words, the height of the nozzle and rotor blades is made low and the width is made large, giving the overall shape a stubby shape.

That is, as shown in FIG. 2, compared to the conventional rotor blade 28, the present invention has a larger rotor blade 2γ and nozzle to reduce the influence of erosion.

Along with this, the thickness of the trailing edge of the nozzle and rotor blade has been changed from the usual 1 to 2 m to about 8 to 10 m to resist erosion.

In addition, in this invention, the nozzle and rotor blades are made large and stubby, and the number of stages is increased to provide a sufficient number of stages.
The usual 1-2 stages are changed to 2-4 stages, and in conjunction with lowering the circumferential speed of the rotor blades, which will be described later, this prevents a decrease in turbine efficiency.

(2) Also, the speed of the gas flowing out from the nozzle is 160 m/s or more, whereas it is normally 200 m/s or more.
It is lowered to about m/s.

In addition, the angle of gas outflow from the nozzle has been changed from the usual approximately 65° to
The angle is reduced from about 70° to about 55°.

In this way, by reducing the gas velocity flowing out of the nozzle and reducing the gas outflow angle, a smooth flow is provided to the gas flow containing dust and mist, preventing erosion and making the gas flow centered around the turbine axis. A swirling flow of gas is formed to generate centrifugal force, which forces large-sized mist and dust to the inner wall of the casing and quickly discharges it to the outside from the slits and exhaust grooves provided on the inner wall. It is possible to prevent dust from adhering to the stage nozzle and the first stage rotor blade.

(3) In the present invention, the circumferential speed of the tip of the rotor blade is lowered, and the circumferential speed of the first rotor blade, which is normally 300 m/s or more, is increased to 150 to 180 m/s, where dust sticks particularly strongly.
I have to.

By lowering the circumferential speed of the tip of the rotor blade in this way, the amount of work per stage is reduced, but as mentioned in (2) above, it is possible to increase the size of the nozzle and rotor blade and increase the number of stages. Prevents efficiency from decreasing.

Furthermore, by lowering the circumferential speed, the relative speed of the moving blade with respect to the gas is reduced, so the collision speed with the mist can be reduced, and the occurrence of erosion is prevented.

(4) Furthermore, in the present invention, a slit is provided on the outer periphery of the casing of the axial flow turbine 13 so as to be orthogonal to the turbine axis, so that dust and mist can be quickly discharged.

A typical axial flow turbine is designed to obtain maximum efficiency by making the gas outflow direction at the nozzle outlet different from the outflow direction at the rotor blade outlet, that is, the next stage nozzle.

Therefore, the gas does not generate a swirling flow in the same direction.

In contrast, in the present invention, the nozzle outlet and rotor blade outlet are in the same direction, thereby creating a swirling flow around the turbine shaft in the gas flow, and using this centrifugal force, dust and mist are removed from the gas. It is actively separated and discharged through the slit.

(5) In addition, in order to prevent dust from adhering to and accumulating in the labyrinth part, which prevents gas leakage, an inert gas is kept at a slightly higher pressure than the blast furnace gas so that no gas containing dust flows into the labyrinth part. Supplying gas or steam for sealing purposes.

As explained above, according to the present invention, an axial flow turbine is used to recover energy from blast furnace exhaust gas,
In addition, this axial flow turbine has a structure that makes it difficult for dust to adhere to it or cause erosion, so that the following effects can be achieved.

(a) First, the spray water mist itself can clean the nozzles, blades, etc.

(b) In the tdJK turbine, dust with a small particle size (1μ or less) is also present on the concave side of the nozzle and on the convex side of the other nozzle (the back of the blade), that is, metals (oxides and It has become clear that fumes (sulfides) are fixed and deposited, and that this fixation and deposition is caused by high-speed collisions of metal particles and so-called OH bonds.

However, in conventional axial flow turbines, the convex surface of the nozzle (
Because of the separation effect caused by inertial force, it is difficult for the purifying force to reach the back surface of the blade (the back surface of the blade), and dust can adhere to and accumulate rapidly in this area, eventually clogging the nozzle.

However, according to the present invention, in order to exert purifying power on this area, the diameter of the water mist that can be obtained with a normal water sprayer is insufficient, and the diameter of the water mist that is generated by the cooling effect of the gas by the sprayed water is insufficient. Small particle size (
It was found that a mist of about 1μ) was necessary.

In the present invention, such desirable small particle size mist can be obtained, and as shown by the dotted line in FIG. Of course, it has been revealed that the liquid flows in such a manner that it also washes away the dust (d) stuck to the convex surface of the nozzle.

This is the second effect.

(c) Thirdly, when condensation of supersaturated water vapor as described above occurs, water droplets are formed with many small-sized dust particles as nuclei, and the dust is wrapped in a water film, so that the OH Since the effect of the bond is eliminated and the water film acts as a buffer during high-speed collision, the effect of preventing dust from adhering to the convex surface of the nozzle can be obtained.

Therefore, the present invention can eliminate the drawbacks of the conventional axial flow turbine system at once, and has the advantage of an axial flow turbine system that is essentially superior to a system using a centripetal turbine. It is possible to use a flow turbine, the equipment cost is low, and the most important factor, efficiency, is higher than 10 times, so the energy recovery rate is good and it is economical. can.

(d) Furthermore, in this invention, special consideration has been taken to the structure of the axial flow turbine, and the nozzle and rotor blades are made low in height and wide, giving the overall shape a stubby shape. This means that the zero gas passage area is larger than that of a normal axial flow turbine.

By using large turbine blades, the influence of erosion due to clogging due to adhesion of dust can be prevented as much as possible.

Furthermore, a large gas passage area in the front stage of the turbine means a reduction in the turbine workload in the front stage, but in this invention, by reducing the load on the front stage, collisions of dust and mist with the turbine blades are prevented as much as possible. , by increasing the number of stages in the entire turbine, a decrease in overall efficiency is prevented.

Such a turbine blade structure can further enhance the effect of preventing dust adhesion and erosion.

(e) Furthermore, in the present invention, the nozzle and the outlet of the rotor blade are directed in the same direction to generate a swirling flow around the turbine axis in the gas flow, and on the other hand, a slit is provided in the turbine casing so as to be orthogonal to the turbine axis. Therefore, dust and mist contained in the gas flow can be actively discharged out of the turbine system by centrifugal force.

(f) When compared with the conventional axial flow turbine system, there is also the advantage that the equipment cost is considerably reduced because there is no need for complete dust removal and heating of the blast furnace gas.

The system can be made very simple if the same type of water used in the wet dust removal system is used as the water for continuous water spraying on the saturated gas.

This is advantageous because the gas from the outlet of the wet dust remover conventionally used in blast furnaces can be used as is.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of a blast furnace exhaust gas energy recovery device according to the present invention, Fig. 2 a and b are comparative explanatory diagrams showing the shapes of turbine blades according to the prior art and the present invention, respectively, and Fig. 3 FIG. 2 is an explanatory diagram showing the state of dust adhesion on a turbine blade and the flow of gas and mist according to the present invention. DESCRIPTION OF SYMBOLS 1... Blast furnace, 5... Wet type dust remover, 13... Axial flow turbine, 14... Driven machine, 23... Pump for water spray.

Claims (1)

[Scope of utility model registration request] a blast furnace; a dust catcher connected to the top of the blast furnace by a duct; a venturi scriber connected to the dust catcher by a duct; the venturi scriber, an inlet blocking valve, an inlet emergency shutoff valve; It consists of an axial flow turbine whose inlet side is connected by a duct via a speed regulating valve, water sprayers are provided before and after the speed regulating valve, a driven machine is connected to the axial flow turbine, and the vent scriber is connected to the driven machine. −
A bypass duct leading to the outside of the system via a septan valve is provided, and the bypass duct on the outlet side of the septan valve is connected to a duct leading from the outlet side of the axial flow turbine to the outlet stop valve via the outlet stop valve. The ratio of the height of the nozzle and the rotor blade to the chord length of the axial flow turbine is made substantially equal, and the number of turbine stages is increased, and the thickness of the trailing edge of the nozzle and the rotor blade is set to 8 to 10 m.
The peripheral speed of the first rotor blade is set to 150 to 180 m/s, and the outlet of the nozzle and the outlet of the rotor blade are set in the same direction to generate a swirling flow around the turbine axis in the gas flow, while, A blast furnace exhaust gas energy recovery device, characterized in that a slit is provided in the casing of the axial turbine so as to be perpendicular to the turbine axis of the axial turbine.