JP2002361039A - Electron beam type waste gas treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electronic beam type waste gas treatment equipment which is capable of dealing with an waste gas treatment capacity greater than heretofore. SOLUTION: This electronic beam type waste gas treatment equipment has a superconducting electron beam generator 30 which generates the electron beam 34 from an electron source 32 and accelerates this beam by a superconducting accelerator 38 and scans and outputs the same by a scanner 56. The equipment is constituted to make the electron beam 34 from the superconducting electron beam generator 30 incident on the direction along the flow of the waste gas 2 into a reactor 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Field of the Invention The invention utilizes an electron beam, such as sulfur oxides in the exhaust gas leaving the thermal power plant or the like (SO _X) and removal of nitrogen oxides (NO _X) (i.e. desulfurization and denitration The present invention relates to an electron beam type exhaust gas treatment apparatus for performing the above method, and more specifically, to an improvement of the electron beam generation apparatus.

[0002]

2. Description of the Related Art Electron beam type exhaust gas treatment apparatuses are attracting worldwide attention because they can desulfurize and denitrate exhaust gas and collect ammonium sulfate (ammonium sulfate) and ammonium nitrate (ammonium nitrate) as fertilizers as by-products. ing. For example, “Radiation and Industry” No. 82 (19
99), pp. 9-17.

FIG. 4 shows a conventional example of this type of electron beam type exhaust gas treatment apparatus. The apparatus includes an electron beam generator 12 for generating an electron beam 18, an exhaust gas 2 to be treated, ammonia 8, and the electron beam 18. The electron beam 18 is introduced into the exhaust gas 2 in the presence of ammonia 8.
And a cylindrical reactor 10 that removes sulfur oxides and nitrogen oxides in the exhaust gas 2 by irradiating the exhaust gas 2 with sulfur.

[0004] Exhaust gas 2 from a power generation boiler or the like is usually
The cooling device 4 cools to a temperature (for example, about 60 ° C.) suitable for the desulfurization and denitration reactions.

[0005] Ammonia 8 is supplied from ammonia supply device 6 in an amount required for desulfurization and denitration reactions.

The electron beam generator 12 includes a plurality of electron beam accelerators 14 (only two are shown) which are provided on the side of the reactor 10 and irradiate the electron beam 18 from a direction orthogonal to the flow of the exhaust gas 2. DC high voltage (for example, 8) for accelerating the electron beam 18 is applied to each electron beam accelerator 14.
And a plurality of DC high-voltage power supplies 26 (only one is shown) for supplying a voltage of 00 kV).

Each electron beam accelerator 14 controls the electron beam 1
A filament section 16 for generating the electron beam 8, an electrostatic accelerating tube 20 for accelerating the electron beam 18, a scanner 22 for one-dimensionally scanning the accelerated electron beam 18, and a tip of the scanner 22. And the provided window foil 24.
The window foil 24 separates the vacuum atmosphere in the electron beam accelerator 14 from the atmospheric pressure atmosphere in the reactor 10 and transmits the electron beam 18, and is made of, for example, a titanium foil having a thickness of about 35 μm. In FIG. 4, the electron beam 1
Numeral 8 illustrates a state in which scanning is performed right and left for easy understanding, but in actuality, in this example, scanning is performed in the front and back directions on the paper surface.

[0008] In the reactor 10, active species having strong oxidizing power are generated in the exhaust gas 2 by the irradiation of the electron beam 18, whereby SO _x and NO _x are oxidized to become intermediate products of sulfuric acid and nitric acid. These react with ammonia 8 to produce ammonium sulfate and ammonium nitrate powder particles, respectively.

[0009] These powder particles are taken out of the reactor 10 together with the exhaust gas 2 and separated and collected by a dry-type dust collector or the like at the subsequent stage, and the purified exhaust gas 2 is released into the atmosphere from a chimney or the like. You.

[0010]

An electron beam type exhaust gas treatment apparatus using the above-described electron beam generator 12 has a problem that it is difficult to cope with a larger amount of exhaust gas treatment than the current state.

That is, in the current largest electron beam type exhaust gas treatment apparatus, the throughput of the exhaust gas 2 is 620,000 Nm.
³ / h (corresponding to a power generation output of 220 MW). To process this, the beam energy of the electron beam 18 per unit is 800 keV and the beam current is 500 m
A. A total electron beam output of 2.4 MW is realized by using six electron beam accelerators 14 each having a beam output of 400 kW. The power supply has an output voltage of 800 kV and an output voltage of 1
A. Three DC high-voltage power supplies 26 having an output of 800 kW are used, and one DC high-voltage power supply 26 supplies 500 mA to two electron beam accelerators 14 at a time.

The reason why six electron beam accelerators 14 are used is that the electron beam output 2.4 MW determined by the exhaust gas throughput is used.
Is required because the beam output of one electron beam accelerator 14 is limited to about 400 kW. The output of each DC high-voltage power supply 26 is limited to about 800 kW.

Theoretically, the beam output P is the product of the beam energy E of the electron beam 18 and the beam current I (ie, P = E · I), so that at least one of the beam energy E and the beam current I If the value is larger than the above value, the beam output P can be increased, but it is practically difficult.

That is, in order to make the beam energy E of the electron beam 18 larger than 800 keV, the output voltage of the DC high-voltage power supply 26 must be made larger than 800 kV. It is actually difficult to manufacture a DC high-voltage power supply 26 capable of outputting a large current as described above, both technically and cost-wise. Even if it can be manufactured, one DC high voltage power supply 2
6 becomes extremely large and cannot be transported.

The beam current I of the electron beam 18 is set to 5
When the current is larger than 00 mA, the amount of heat generated by the electron beam transmission loss of the window foil 24 becomes smaller than the beam current I of the electron beam 18.
, The amount of heat generated by the window foil 24 becomes too large to withstand. It is also difficult to manufacture the DC high-voltage power supply 26 that supplies such a large current.

As described above, even at a power generation output of 220 MW, as many as six electron beam accelerators 14 and three DC high-voltage power supplies 26 must be provided. It is difficult to cope with a power generation facility having a larger output (for example, about 400 MW) requiring a larger exhaust gas throughput by simply extending the conventional technology. There are many power generation facilities of about 400 MW per unit in Japan and overseas.

SUMMARY OF THE INVENTION Accordingly, it is a main object of the present invention to provide an electron beam type exhaust gas treatment apparatus capable of coping with a larger amount of exhaust gas treatment than before.

[0018]

According to the present invention, there is provided an electron beam type exhaust gas treating apparatus as the above-mentioned electron beam generating apparatus, which generates an electron beam, accelerates the electron beam with a superconducting accelerator, and then scans and outputs the electron beam. A beam generator, and the electron beam from the superconducting electron beam generator is configured to be incident on the reactor in a direction along the flow of the exhaust gas in the reactor. It is characterized by.

The superconducting accelerator constituting the above-mentioned superconducting electron beam generator is a kind of linear accelerator, and is much higher (for example, one order of magnitude higher) than an electrostatic accelerator using a conventional accelerating tube. An electron beam of energy can be obtained.

Moreover, in the superconducting accelerator, the Joule heat loss in the superconducting accelerating cavity constituting the superconducting accelerator is much smaller than that in normal conduction and can be almost ignored. No instability problems occur. As a result, it is possible to easily realize a large output with a large beam current as compared with the conventional normal type linear accelerator.

As described above, the use of the superconducting electron beam generator makes it possible to obtain a high-energy and high-output electron beam, so that it is possible to easily cope with a larger exhaust gas throughput than conventional ones. it can.

[0022]

FIG. 1 is a schematic diagram showing an example of an electron beam type exhaust gas treatment apparatus according to the present invention. FIG.
FIG. 2 is a schematic cross-sectional view showing an example around a superconducting accelerator in FIG. 1. Parts that are the same as or correspond to those of the conventional example shown in FIG. 4 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.

This electron beam type exhaust gas treatment apparatus replaces the conventional electron beam generator 12 by generating an electron beam 34 from an electron source 32, accelerating the electron beam 34 by a superconducting accelerator 38, and then scanning by a scanner 56. And a superconducting electron beam generator 30 for outputting. In addition, the electron beam 34 from the superconducting electron beam generator 30 is supplied into the reactor 10 in a direction along the flow of the exhaust gas 2 in the reactor 10 (that is, in a direction along the axis of the reactor 10). It is configured to be incident. The electron beam 34 need not be completely parallel to the flow direction of the exhaust gas 2. Rather, it is preferable to have a certain angle because three-dimensional irradiation of the electron beam 34 becomes possible.

In this example, the exhaust gas 2 is introduced into the reactor 10 obliquely from the upstream end of the reactor 10 but is not limited to this.

In this example, the superconducting electron beam generator 30 has an electron source 32 for generating an electron beam 34 and a superconducting acceleration cavity 46 (see FIG. 2) maintained in a superconducting state. A superconducting accelerator 3 which accelerates and outputs an electron beam 34 supplied from a source 32 through a compressor 36 by a high-frequency electric field in a superconducting accelerating cavity 46 in this example.
8, a high-frequency oscillator 50 for supplying high-frequency power 54 for acceleration to the superconducting accelerator 38 (more specifically, to the superconducting accelerating cavity 46 therein), and an electron beam 34 output from the superconducting accelerator 38 And a refrigerator 48 (see FIG. 2) for supplying a liquid refrigerant 44 for keeping the superconducting acceleration cavity 46 therein in a superconducting state to the superconducting accelerator 38. It has.

Such a superconducting electron beam generator 30
Thus, for example, an electron beam 34 having a beam output of 3 MW with an energy of 10 MeV is generated. In that case,
The beam current is 300 mA. 500 m beam current
If A, the beam output is 5 MW.

The electron source 32 is, for example, 10 to 50 MHz.
A pulse-like (which is also called a micropulse) electron beam 34 having a frequency of .mu. More specifically, assuming that the pulse frequency is 10 MHz, the pulse width is 10 ns and the peak current is 3 A as a charge amount of 30 nC (nanocoulomb) per pulse.

In this example, the pulse width of the electron beam 34 is reduced by 1/50 to 1/100 by a compressor (also called a buncher) 36 so that the electron beam 34 can be accelerated more efficiently by a superconducting accelerator 38. It is compressed to a degree and then enters the superconducting accelerator 38. The incidence on the superconducting accelerator 38 is
For example, it may be performed at an incident energy of about 100 keV.

The superconducting accelerator 38 is a kind of a high-frequency linear accelerator, and has a structure as shown in FIG. 2 in this example. An example of this type of superconducting accelerator is described in Japanese Patent No. 3094299.

The superconducting accelerator 38 includes a liquid refrigerant container 42 filled with a liquid refrigerant 44 supplied from a refrigerator 48.
Inside, a plurality (five in the illustrated example) of superconducting acceleration cavities 46 connected in series are housed, and the liquid refrigerant container 42 is housed in a vacuum chamber 40. Usually, a heat shield, a support thereof, and the like are provided between the liquid refrigerant container 42 and the vacuum container 40, but are not shown here.

In this example, each superconducting acceleration cavity 46 is formed of niobium (Nb), liquid helium is used as the liquid refrigerant 44, and a helium refrigerator is provided as the refrigerator 48. Therefore, each superconducting accelerating cavity 46 is kept in a superconducting state at a temperature of 4.2 K of liquid helium. However, a superconducting material other than niobium may be used for the superconducting acceleration cavity 46, and the type of the liquid refrigerant 44 that keeps the superconducting state may be determined according to the material.

The maximum acceleration energy of the electron beam 34 is generally determined by the number of superconducting accelerating cavities 46 (the number of cells), the frequency of the high-frequency power 54, and the like. For example, 250M
With 6 cells at Hz, beam energy of about 10 MeV can be obtained stably. However, it is not limited to this.

The superconducting accelerator 38 and the reactor 1
For example, 0 is installed horizontally and in series with each other, and the electron beam 34 which is accelerated in the horizontal direction and exits is scanned by the scanner 56 so as to enter the reactor 10 in the lateral direction.

It is preferable that the refrigerator 48 be mounted on the superconducting accelerator 38, rather than being arranged separately from the superconducting accelerator 38. By doing so, the transfer loss of the liquid refrigerant 44 can be eliminated, and high efficiency can be achieved. Also,
It is preferable to provide a plurality of small refrigerators 48 rather than one large refrigerator 48. If you do so,
An inexpensive refrigerator can be used, and the refrigerator 4
The maintenance and management of the refrigerator 8 becomes easy, and the qualification for operating the refrigerator 48 under the High Pressure Gas Safety Law (formerly the High Pressure Gas Control Law) becomes unnecessary.

The oscillation tube of the high-frequency oscillator 50 includes, for example,
High current tetrode used for high frequency heating (Tetrod
The oscillation frequency may be selected around 250 MHz using e). By doing so, power efficiency of about 75% can be secured. A frequency around 500 MHz may be selected.

High frequency power 54 from high frequency oscillator 50
Is transmitted to the superconducting accelerator 38 via the waveguide 52, for example. This transmission involves a normal (ie, atmospheric pressure inside)
Although a waveguide or a coaxial waveguide may be used, it is preferable to use a waveguide 52 having a vacuum inside. This is the case in this example. This eliminates the need for a partition plate (ceramic plate) for separating the pressure difference at the connection between the waveguide 52 and the superconducting acceleration cavity 46. MW class high frequency power 5
In order to allow the continuous passage of 4, a normal ceramic plate generates a large amount of heat and cannot endure it, but this can be eliminated. In addition, means for branching the waveguide 52 and supplying high frequency power 54 to the superconducting accelerator 38 from a plurality of locations may be employed.

Since the electron beam 34 accelerated by the superconducting accelerator 38 emerges in a straight line, it is scanned by a magnetic field or the like by a scanner 56 and spread. In this example, the scanner 56 includes a scanning coil 58 that scans the electron beam 34 with a magnetic field, a divergent scanning tube 60, and a window foil 62 provided at the tip of the scanning tube 60. The scanning frequency may be, for example, about 100 to 200 Hz.

The window foil 62 separates the vacuum atmosphere on the side of the superconducting accelerator 38 and the scanner 56 from the atmospheric pressure atmosphere in the reactor 10 and transmits the electron beam 34, similarly to the conventional window foil 24. And is made of, for example, a titanium foil having a thickness of 30 to 40 μm. If the thickness is smaller than this, the transmission loss of the electron beam 34 is reduced, but the electron beam 34 is easily broken and reliability is reduced.

When the electron beam 34 is scanned one-dimensionally (for example, in the X direction) by the scanner 56, the electron beam 34 spreads in a plane. When the electron beam 34 is scanned two-dimensionally (for example, in both X and Y directions orthogonal to each other), the electron beam 34 spreads three-dimensionally. Two-dimensional scanning is preferable because the irradiation area of the electron beam 34 to the exhaust gas 2 can be made larger and the irradiation efficiency of the electron beam 34 becomes higher.

Although the two-dimensional scanning of the electron beam 34 itself is easy, when scanning in both X and Y simultaneously like a television screen, a window foil 62 having a large area for transmitting the planar electron beam 34 is required. And the device needs to be devised for its support and cooling.

In this case, as an example, as shown in FIG. 3, a window foil 62 is attached to a mounting frame 64 having two rows of parallel openings 66 with a water-cooled bar 68 therebetween, and the electron beam 34 is turned by an arrow. The scanning may be performed so as to rotate in a rectangular shape as shown by R, so that the time to cross the crosspiece 68 may be shortened as much as possible. By doing so, the two openings 66
Since the electron beam 34 passing through the reactor 10 opens up and down and spreads slightly and enters the reactor 10, the electron beam 34 crosses the exhaust gas 2 flowing in the reactor 10 at an appropriate angle, and the exhaust gas 2 can be efficiently treated. The support and cooling of the window foil 62 are also facilitated.

The superconducting accelerator 38 constituting the superconducting electron beam generator 30 is a kind of linear accelerator, and is far more (for example, one digit) than the conventional electrostatic accelerator 14 using the accelerating tube 20. A high energy electron beam 34 (above) can be obtained.

In the conventional normal-conduction type linear accelerator, the upper limit is to obtain an electron beam having a beam energy of about 10 MeV and a beam output of about 25 kW. This is because in a normal conduction type acceleration cavity, a huge amount of Joule heat is generated just by generating an acceleration electric field, and this heat causes unevenness and large distortion in the acceleration cavity, which easily causes unstable operation. However, when the output is large, it is extremely difficult to suppress the occurrence of instability and ensure stability.

On the other hand, in the superconducting accelerator 38, the Joule heat loss in the superconducting acceleration cavity 46 constituting the superconducting accelerator 38 is much smaller than that in normal conduction and can be almost ignored. The problem of operation instability due to the occurrence of distortion does not occur. As a result, it is possible to easily realize a large output with a large beam current as compared with the conventional normal type linear accelerator. For example, as described above, the electron beam 3
4 had a beam energy of 10 MeV and a beam current of 30
It is possible to realize a laser beam having a beam output of about 0 to 500 mA and a beam output of about 3 to 5 MW.

As described above, the superconducting electron beam generator 3
By using 0, a high energy and high output electron beam 34 can be obtained, so that it is possible to easily cope with a larger exhaust gas throughput than before.
Therefore, it is possible to easily cope with power generation equipment having a larger output than before.

This is to increase the output mainly by increasing the energy of the electron beam 34 as compared with the conventional electrostatic electron beam accelerator 14. In this case, since the beam current does not need to be increased, the amount of heat generated due to the beam transmission loss in the window foil 62 does not need to be increased. Rather, the transmission loss is reduced by increasing the energy of the electron beam 34. As a result, the heat generation of the window foil 62 does not need to be increased, so that the damage of the window foil 62 is easily prevented and the reliability is improved.

Moreover, the superconducting electron beam generator 3
From 0, the high energy electron beam 34
Since the high-energy electron beam 34 has high permeation power in the exhaust gas 2 in the reactor 10, the electron beam 34 is incident in the direction along the flow of the exhaust gas 2 while scanning the electron beam 34. Accordingly, the same electron beam 34 can be applied to the exhaust gas 2 in a larger area to perform processing, as compared with the case where the electron beam is irradiated in the direction orthogonal to the flow of the exhaust gas as in the related art. As a result, the utilization efficiency of the electron beam 34 is increased, and the treatment efficiency of the exhaust gas 2 is increased.

The superconducting electron beam generator 30 is different from the conventional electron beam generator 12 in which many electron beam accelerators 14 and many DC high voltage power supplies 26 need to be arranged. Since the arrangement space and the total weight can be made much smaller, the size and weight of the electron beam type exhaust gas treatment device can be reduced.

The energy of the electron beam 34 generated from the superconducting electron beam generator 30 is 10 MeV
It can be selected almost arbitrarily up to the extent, and there is almost no restriction from the superconducting electron beam generator 30 side. The energy can be freely selected from the viewpoint of the reaction in the reactor 10. Therefore, the degree of freedom of the device design is high.

The beam current of the electron beam 34 generated from the superconducting electron beam generator 30 is, for example, about 300 to 500 mA as described above, but is not limited to this.

Further, a plurality of superconducting electron beam generators 30 as described above may be provided for one reactor 10. In that case, a plurality of superconducting electron beam generators 30
May be arranged on one side of the reactor 10 or on both sides of the reactor 10 so as to face each other. In the latter case,
For example, the treated exhaust gas 2 may be taken obliquely from the downstream end of the reactor 10.

[0052]

As described above, according to the present invention, a superconducting electron beam generator having a superconducting accelerator is provided, which has higher energy than conventional electrostatic accelerators and normal-conducting linear accelerators. In addition, since a high-power electron beam can be obtained, it is possible to easily cope with a larger exhaust gas throughput than ever before.

In addition, since the beam current does not need to be increased by increasing the energy of the electron beam, and the heat generation of the window foil does not need to be increased, it is easy to prevent breakage of the window foil and reliability is improved.

Furthermore, by scanning a high-energy electron beam having a large penetrating power and making it incident in the direction along the flow of the exhaust gas, the same electron beam can be applied to the exhaust gas in a larger area for processing.
The utilization efficiency of the electron beam is increased, and the treatment efficiency of the exhaust gas is increased.

The superconducting electron beam generator according to the present invention is different from the conventional electron beam generator in which a large number of electron beam accelerators and a large number of high-voltage DC power supplies for the electron beam accelerator need to be arranged. Since the arrangement space and the total weight can be made much smaller, the size and weight of the electron beam type exhaust gas treatment device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an electron beam type exhaust gas treatment apparatus according to the present invention.

FIG. 2 is a schematic cross-sectional view showing an example around a superconducting accelerator in FIG.

FIG. 3 is a front view showing an example of the relationship between electron beam scanning and window foil.

FIG. 4 is a schematic view showing an example of a conventional electron beam type exhaust gas treatment apparatus.

[Explanation of symbols]

 2 Exhaust gas 8 Ammonia 10 Reactor 30 Superconducting electron beam generator 32 Electron source 34 Electron beam 38 Superconducting accelerator 46 Superconducting accelerating cavity 48 Refrigerator 50 High frequency oscillator 56 Scanner 62 Window foil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G21K 5/04 ZAA B01D 53/34 ZAB 5/10 F term (Reference) 4D002 AA02 AA12 AC10 BA05 BA09 DA07 FA06 4G075 AA03 AA37 BA05 BA06 BD22 CA03 CA14 CA39 CA62 CA80 DA02 EB21 FB02 FC11

Claims (2)

[Claims] An electron beam generator for generating an electron beam, exhaust gas to be treated, ammonia and the electron beam are introduced, and the exhaust gas is irradiated with the electron beam in the coexistence of ammonia, and sulfur oxides in the exhaust gas and A reactor for removing nitrogen oxides, wherein the superconducting electron beam is generated by generating an electron beam, accelerating the electron beam by a superconducting accelerator, and then scanning and outputting the electron beam. A beam generator, and the electron beam from the superconducting electron beam generator is configured to be incident on the reactor in a direction along the flow of the exhaust gas in the reactor. An electron beam type exhaust gas treatment apparatus characterized by the above-mentioned. 2. The superconducting electron beam generator includes an electron source for generating an electron beam, and a superconducting accelerating cavity maintained in a superconducting state. A superconducting accelerator that accelerates and outputs by a high-frequency electric field in the superconducting acceleration cavity, a high-frequency oscillator that supplies high-frequency power for acceleration to the superconducting acceleration cavity in the superconducting accelerator, and an electron that is output from the superconducting accelerator. A scanner for scanning the beam at least one-dimensionally to enter the reactor, and a refrigerator for supplying the superconducting accelerator with a liquid refrigerant for keeping a superconducting accelerating cavity therein in a superconducting state. An electron beam type exhaust gas treatment apparatus according to claim 1.