JP2013228135A - Co boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CO boiler capable of reducing a CO gas concentration at an outlet of a furnace of the CO boiler by sufficiently securing a residence time of CO gas in the furnace.SOLUTION: A CO boiler 1 having a furnace 3 for burning gas containing CO generated from an oil refinery facility includes an exhaust gas outlet 7 formed in an upper side wall of the furnace 3, a nose 5 provided on a side wall on an outlet 7 side below the outlet 7, an assist burner 13 provided below the nose 5 and only on a side wall opposing the nose 5, and a CO gas port 15 which is provided on a wall below the assist burner 13 and supplies gas containing CO into the furnace 3. By providing the CO gas port 15 below the assist burner 13, CO gas flows to the upper outlet 7 while bypassing the nose 5 from the side wall on the nose 5 side by the assist burner 13, and consequently, a residence time of CO gas in the furnace 3 can be secured. Furthermore, by providing a CO gas port 15 in a furnace bottom 21, a lower space of the furnace 3 is effectively used, and the long residence time of CO gas can be secured.

Description

  The present invention relates to a structure of a CO boiler that burns a high-temperature CO-containing gas discharged from an oil refining facility.

  The oil industry is one of the key industries, and oil refinery facilities are equipped with a heavy oil fluid cracking contact device for refining gasoline from heavy oil as demand for gasoline increases. A heavy oil fluid cracking contact apparatus (hereinafter referred to as RFCC apparatus) is an apparatus for purifying high-value-added fractions such as gasoline, kerosene, and light oil by using high-pressure cracking on a catalyst using atmospheric residual oil as a raw material.

  And since the gas containing high-temperature carbon monoxide (CO) is discharged from this RFCC device, a boiler (hereinafter referred to as “CO” -containing gas) is used on the downstream side of the exhaust gas flow path of the heavy oil fluid cracking contact device. A CO boiler is also installed. Combustion of CO-containing gas (hereinafter referred to as CO gas) prevents the emission of CO into the atmosphere, and recovers heat from the high-temperature CO gas using a CO boiler, which is effectively used for in-plant utilities, power generation, etc. Yes.

  As a boiler using a blast furnace gas (hereinafter referred to as BFG) generated in a production process at an ironworks, which is a low calorie gas similar to CO gas, there is the following Patent Document 1. Patent Document 1 discloses a combustion apparatus in which a low-calorie gas burner is provided immediately below a main burner, and the nozzle of the low-calorie gas burner is directed obliquely downward. Combusting low-calorie gas, which has been reversed at the bottom of the furnace, in the high-temperature region of the main burner by preventing flame-retardant low-calorie gas from swirling combustion in the main burner to prevent adverse effects on main burner ignition The combustion efficiency is improved.

  When burning BFG, the CO gas is heated to around 200 ° C. with a heat exchanger before the boiler is charged. However, since the temperature of the CO gas is low, the low-calorie gas burner generally used It is possible to supply gas to the boiler at the same time.

  However, since a large amount of high-temperature CO gas of around 700 ° C. is generated from the RFCC device, the structure of the burner is designed to be heat-resistant or fire-resistant or enlarged in order to supply it to the boiler via the gas burner. However, if a new burner dedicated to this high-temperature CO gas is used, the cost of the burner itself will increase significantly, and the user will be required to make the boiler equipment more compact. It is difficult to do.

Further, as shown in FIG. 11 and FIG. 12, the fuel is charged into the CO boiler only from the front wall (FIG. 11) or the front wall, as in a normal coal fired boiler, oil fired boiler, gas fired boiler, etc. And from the rear wall (Figure 12).
In the CO boiler shown in FIGS. 11 and 12, CO gas is combusted in the furnace 3 by the auxiliary burner 13 and is generally heated by the superheater 9 provided at the exhaust gas outlet section 7, and then a denitration device and desulfurization not shown. It is discharged from the chimney through a device and an electric dust collector. In some cases, a superheater, a denitration device, a desulfurization device, an electrostatic precipitator, etc. are not installed.

When burning a large amount of low-calorie CO gas, it is necessary to install a low-calorie gas or auxiliary fuel combustion device and a combustion air inlet, etc. An increase in the size of the combustion apparatus and the accompanying increase in the size of the boiler equipment are unavoidable, and there are restrictions on the arrangement, which limits the amount of CO gas processed.
Moreover, as a CO boiler using such high-temperature CO gas as a fuel, there are Patent Document 2 and Patent Document 3 below.

In the configuration described in Patent Document 2, an auxiliary combustion burner is provided by placing a port for low calorie gas containing CO on the upper side and a port for incombustible gas containing CO ₂ on the lower side with the auxiliary combustion burner interposed therebetween. The low-calorie gas can be ignited immediately before the low-calorie gas and the non-combustible gas are mixed by the upward flame from.

  Further, in the configuration described in Patent Document 3, the flow rate of the auxiliary combustion gas is controlled based on the net load amount entering the boiler calculated from the specific heat or calorific value of the CO gas being supplied, and this is controlled in the furnace temperature of the boiler. In addition, a configuration is disclosed in which the supply air amount is controlled by comparing the calculated air amount calculated from the net load amount with the actually measured air amount. Therefore, the auxiliary combustion gas can be suppressed to the minimum necessary even if the demand steam amount changes.

JP-A-4-278109 Japanese Patent Laid-Open No. 8-113788 JP-A-8-42801

  As described above, since the CO gas generated from the RFCC apparatus is a high temperature of about 700 ° C. and a large amount, there are problems such as restrictions on the arrangement of the combustion apparatus and enlargement of the apparatus. As in the configuration, it is practically difficult to supply the boiler from the gas burner.

  And in the structure of the said patent document 2, although the port for low calorie gas containing high temperature CO is provided separately from the auxiliary combustion burner, since this port is in contact with the auxiliary combustion burner, the auxiliary combustion burner is provided with a fireproof structure. It is necessary to consider such as. In addition, since CO-containing low calorie gas is supplied from the top of the auxiliary burner, it will flow upward due to the upward flame without contact with the flame and mixing, so low calorie gas stays in the furnace. There is also a problem that time is not secured and the CO gas is not completely burned.

  Similarly, even in the configuration described in Patent Document 3, if the residence time of the CO gas in the furnace is not secured, the CO gas with poor flammability will remain unburned and the CO gas concentration at the furnace outlet will be high. When the CO gas concentration at the furnace outlet is high, energy recovery efficiency deteriorates and harmful CO gas is released into the atmosphere.

Further, in the combustion of CO gas, there is a problem that a decrease in the temperature of the CO gas greatly affects the oxidation reaction rate of CO, and the CO gas concentration at the furnace outlet becomes high. The temperature at which the oxidation reaction of CO is promoted is 700 ° C. or higher, and the temperature decrease of the CO gas greatly affects the combustion efficiency.
Furthermore, it is desirable that nitrogen oxides (hereinafter referred to as NOx) generated by the combustion of fuel are also reduced.

  An object of the present invention is to provide a CO boiler that can secure a sufficient residence time of CO gas in the furnace of the CO boiler and reduce the CO gas concentration at the furnace outlet. Furthermore, the present invention also provides a CO boiler that can reduce NOx produced by fuel combustion.

The above-described problems of the present invention can be solved by the following means.
The invention according to claim 1 is a CO boiler having a cylindrical furnace for burning a by-product gas containing carbon monoxide generated from an oil refining facility. Provided on the outlet part to be discharged, the side wall on the outlet part side below the outlet part, the constricted part for narrowing the exhaust gas flow path, and provided only on the side wall below the constricted part and facing the constricted part A CO boiler comprising an auxiliary combustion burner for burning auxiliary combustion fuel with combustion air, and a CO gas port provided below the auxiliary combustion burner and supplying the gas containing carbon monoxide into the furnace.
The term “cylindrical” means that the cross section includes a polygonal shape such as a circle or a rectangle.

A second aspect of the present invention is the CO boiler according to the first aspect, wherein the CO gas port is provided on a bottom wall of a furnace.
A third aspect of the present invention is the CO boiler according to the second aspect, wherein the CO gas port is provided on the bottom wall on the side wall side where the auxiliary burner is provided.

  According to a fourth aspect of the present invention, there is provided a turning device for forming a turning force in the combustion air of the auxiliary combustion burner in the auxiliary combustion burner, and an adjustment device for adjusting the strength of the turning force by the turning device is provided in the turning device. The CO boiler according to any one of claims 1 to 3.

A fifth aspect of the present invention is the CO boiler according to any one of the first to fourth aspects, wherein a wall around the auxiliary burner is made of a refractory material.
According to a sixth aspect of the present invention, there is provided an after-air port for injecting combustion air insufficient for combustion of fuel in the auxiliary burner into the furnace above the auxiliary burner. The CO boiler according to Item 1.

(Function)
By devising the structure of the furnace and the arrangement of the auxiliary burner and the CO gas port to ensure the residence time of the CO gas in the furnace, the furnace is made an oxidizing atmosphere, and CO is changed to carbon dioxide (CO ₂ ). It can be rendered harmless by oxidation.

  The upper side wall of the furnace has an exhaust gas outlet, and the lower side wall has a constriction for narrowing the exhaust gas flow path. An auxiliary burner for burning the auxiliary fuel with combustion air is provided below the constricted portion and on the side wall facing the constricted portion, and a CO gas port is provided below the auxiliary burner. The CO gas charged into the boiler furnace flows toward the upper outlet, but the CO gas is burned along with the high-temperature injection flame by the injection flame from the auxiliary burner in the flow path between them. On the other hand, it first flows to the side wall on the constricted portion side, and further flows upward along the constricted portion, and then discharged from the outlet portion at the upper part of the furnace.

  If there is a CO gas port above the auxiliary burner, the CO gas introduced into the boiler will rise immediately due to the rising air flow of the flame from the auxiliary burner, so the time of contact with the flame of the auxiliary burner will be short and combustion will be sufficient Not done. Further, the CO gas rises without flowing along the constriction, and passes through the constriction at a high speed. Therefore, sufficient residence time of CO gas in the furnace cannot be secured. Further, since the CO gas hardly flows into the space below the auxiliary burner, the space below the auxiliary burner in the furnace is not sufficiently effectively used for securing the residence time of the CO gas in the furnace.

  In addition, when the auxiliary burner is installed on both opposing wall surfaces such as the front wall and the rear wall of the furnace, the CO gas is supported on the front wall and the rear wall even if the CO gas port is provided below the auxiliary burner. When passing between the burners, the rising speed increases due to the flame of the auxiliary burner from both sides, so that the time of contact with the flame of the auxiliary burner is shortened. In addition, since the upward flow of the combustion gas becomes strong, the CO gas hardly stays in the furnace, so that the combustion is not sufficiently performed.

  However, by providing the CO gas port below the auxiliary burner, CO gas is introduced from the lower side of the auxiliary burner, so the CO gas contacts the lower side of the flame ejected from the auxiliary burner and is accompanied by the flame. Then, while being burned while being caught in the flame, the combustion gas flows to the side wall on the constricted part side, then flows again to the wall side on the side where the auxiliary burner is provided along the constricted part, and bypasses the inside of the furnace Since it flows to the upper furnace outlet, the CO gas flow path becomes longer, and the combustion reaction time can be secured.

  In addition, since CO gas stays in the space below the flame of the auxiliary burner, the space in the furnace is effectively used, the residence time of the CO gas in the furnace can be secured sufficiently, and the radiant heat from the flame allows the CO gas to stay. Since the gas can be maintained at a high temperature, the CO gas can be sufficiently burned.

  Furthermore, since the auxiliary burner is installed only on the side wall facing the constricted portion, the CO gas flows to the constricted portion side along the injection direction of the auxiliary burner and then rises. Since the upward flow caused by the collision of the flames that occurs when provided on the wall surface is not formed, the upward speed is suppressed and the flow is relatively slow.

  Therefore, according to the first aspect of the present invention, the auxiliary burner is installed only on the side wall below the constricted portion and facing the constricted portion, and the CO gas port for introducing the gas containing CO is provided below the auxiliary burner. Thus, the residence time of the CO gas in the furnace is ensured, and the CO gas can be sufficiently burned.

  Further, according to the invention described in claim 2, in addition to the operation of the invention described in claim 1, the CO gas is orthogonal to the flame of the auxiliary burner by providing the CO gas port on the bottom wall of the furnace. Collision in the form, and mixing into the flame is performed quickly and sufficiently, so that combustion of CO gas is promoted.

  In addition, since there are no devices or members such as a combustion device at the bottom of the furnace, there are no restrictions on the arrangement, so even if the CO gas processing amount is large by using this part, the processing amount is not limited. It is possible to increase the opening area of the CO gas port.

  According to the invention described in claim 3, in addition to the operation of the invention described in claim 2, by providing the CO gas port on the bottom wall on the side wall side where the auxiliary burner is provided, the CO gas port is charged. Since CO gas is mixed from the root side of the flame of the auxiliary burner to the flame, the combustion reaction time of the CO gas can be further ensured.

  According to the invention of claim 4, in addition to the action of the invention of any one of claims 1 to 3, the strength of the turning force of the combustion air of the auxiliary burner can be adjusted. For example, by reducing the swirl force of the combustion air, the flow velocity of the combustion air can be increased in the straight direction, so that the flow of CO gas to the side wall on the constricted portion side is promoted by this combustion air flow, The amount of accompanying CO gas is greatly increased. Therefore, the residence time of a large amount of CO gas in the furnace can be further secured, and the CO concentration at the furnace outlet can be significantly reduced.

  According to invention of Claim 5, in addition to the effect | action of the invention of any one of the said Claims 1-4, when the surrounding wall of an auxiliary combustion burner is comprised with a refractory material, from surrounding wall Heat dissipation can be suppressed, and the temperature around the flame of the auxiliary burner can be maintained at a high temperature, so that the temperature of the flame due to combustion air can be prevented from being lowered and kept at a high temperature. At this time, by maintaining the CO gas temperature high, the CO gas combustibility is improved by increasing the rate of the CO oxidation reaction.

  According to the invention described in claim 6, in addition to the action of the invention described in any one of claims 1 to 5, combustion air that is insufficient for combustion of fuel in the auxiliary burner is introduced into the furnace. By installing a jetting after-airport, two-stage combustion can be performed and combustion efficiency is improved.

  That is, CO is burned with the air ratio (ratio of the actual air amount to the theoretical air amount) at the auxiliary burner being 1 or less, but the generation of thermal NOx is suppressed by suppressing rapid combustion. Thermal NOx refers to NOx produced when nitrogen and oxygen contained in combustion air react at a high temperature and become NO.

  Thereafter, the remaining combustion air is ejected from the after-air port to the combustion gas containing CO and unburned components at the furnace outlet, and a part of the combustion air is supplied to the combustion gas rising up the furnace. Since combustion can be performed, CO and unburned components can be completely burned while suppressing generation of thermal NOx.

According to the present invention, it is possible to reduce the CO gas concentration at the furnace outlet by sufficiently securing the residence time of the CO gas in the furnace of the CO boiler. Specifically, it has the following effects.
According to the first aspect of the present invention, since the gas containing CO from the CO gas port installed below the auxiliary burner flows upward while bypassing the furnace, the flow path of the gas containing CO becomes long. Thus, the residence time of the CO gas in the furnace is ensured, and the CO gas can be sufficiently burned.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the combustion of the CO gas is promoted, and the opening area of the CO gas port can be increased, so that the CO gas throughput can be reduced. Can handle at most.
According to the invention described in claim 3, in addition to the effect of the invention described in claim 2, by providing the CO gas port on the bottom wall on the side wall provided with the auxiliary burner, the combustion reaction time of the CO gas can be reduced. Furthermore, it can be secured.

  According to the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, the combustion force is adjusted by adjusting the strength of the turning force of the combustion air of the auxiliary burner. Since the flow velocity of the working air in the straight traveling direction can be increased or decreased, the flow of the CO gas to the side wall on the constricted portion side can be promoted, and the residence time of the CO gas in the furnace can be further secured.

According to the invention of claim 5, in addition to the effect of the invention of any one of claims 1 to 4, the temperature of the combustion air can be maintained at a high temperature. The flammability of CO gas can be improved.
According to the invention described in claim 6, in addition to the effect of the invention described in any one of claims 1 to 5, combustion of auxiliary fuel is performed by installing an after-airport and performing two-stage combustion. NOx generated sometimes can be reduced.

It is a front view of the CO boiler of one Example of this invention. It is a side view of the CO boiler of FIG. It is a bottom view of the CO boiler of FIG. It is a top view which shows the partial cross section of an auxiliary combustion burner. FIG. 4 is a bottom view of the CO boiler when the position of the CO gas port in FIG. 3 is changed. It is a top view of the CO boiler of the other Example of this invention. It is a bottom view of the CO boiler of FIG. It is a front view of the CO boiler of the other Example of this invention. It is a side view of the CO boiler of FIG. It is a bottom view of the CO boiler of FIG. It is a side view of the conventional CO boiler (when a burner is installed only on the front wall). It is a side view of the conventional CO boiler (when a burner is installed in both walls).

  Examples of the present invention will be described below.

1 shows a front view of a CO boiler 1 according to an embodiment of the present invention, FIG. 2 shows a side view of the CO boiler 1 of FIG. 1, and FIG. 3 shows a furnace of the CO boiler of FIG. The top view (bottom view) of the bottom (bottom wall) is shown.
The furnace 3 has a quadrangular horizontal cross section, and includes a nose 5 that is a constricted portion provided on the upper portion of the rear wall 19, an exhaust gas outlet 7 provided above the nose 5, a superheater 9 provided on the exhaust gas outlet 7, and the like. Is done.

  The front wall 11 of the furnace 3 is provided with an auxiliary burner 13 for burning auxiliary combustion fuel with combustion air, and a CO gas port 15 for introducing a gas containing CO below the auxiliary burner 13 is provided.

FIG. 4 shows an example (a plan view showing a partial cross section) when the auxiliary burner 13 is an oil burner.
The auxiliary burner 13 includes a cylindrical sleeve 29, and the sleeve 29 includes a primary air flow path 33 and a fuel nozzle 31 for auxiliary combustion provided on the central axis. Further, a combustion secondary air flow path 35 is provided on the outer peripheral portion of the primary air flow path 33. Combustion air is supplied to the primary air flow path 33 and the combustion secondary air flow path 35 from a wind box 39 disposed outside the furnace side wall. A primary air flow is formed by adjusting the degree of opening and closing of the opening of the sleeve 29 by a damper 41 slidably provided in the primary air flow path 33 so that primary air is supplied. An air register 37 is provided in the secondary air flow path 35, and a combustion air flow is formed by the air register 37 to supply combustion air.

  The air register 37 is a partition (damper) for flowing or stopping the combustion air, and supplies the combustion air to the fuel injected from the burner. When the combustion air is mixed with the fuel, the air register 37 is used as the combustion air. It has a function of adjusting the air flow to stabilize the flame by giving swirl and suppressing the mixing of air as much as possible before the flame or mixing little by little before the flame. There are various types of air registers 37 such as an axial flow type using guide vanes.

  The air register 37 is operated by an opening / closing mechanism or a control device (not shown) to adjust and control the strength of the turning force (swirl number) and the flow rate and flow velocity of the combustion air. Similarly, the damper 41 controls the flow rate of primary air and the flow velocity thereof. The swirl number is a dimensionless number representing the strength of the swirl in the flow with swirl. The larger the swirl number, the stronger the swirl flow.

The gas containing CO generated from the RFCC apparatus has a composition of N ₂ : 70%, CO ₂ : 12%, CO: 4%, H ₂ O: 13%, others: 1% (vol%), and a temperature. It is charged into the furnace 3 (combustion furnace having a depth of 7 m, a height of 10 m, and a width of about 10 m) from the CO gas port 15 under the conditions of 700 ° C. and a flow rate of 500 tons per hour.

  Since the gas containing CO is low in calories and has a low concentration, auxiliary combustion with auxiliary fuel is required to maintain stable combustion. From the auxiliary burner 13, auxiliary combustion fuel is introduced into the furnace 3 together with combustion air. In addition, although the example of an oil burner is shown in FIG. 4, a gas burner may be used, and the auxiliary combustion fuel is not particularly specified, such as oil, gas, by-product oil, and by-product gas, but may be LPG, for example.

The exhaust gas generated by the combustion in the furnace 3 flows from the outlet 7 through the superheater 9 in the direction of arrow A, and is discharged from the chimney through a denitration device, a desulfurization device, an electric dust collector and the like (not shown).
The CO gas port 15 is provided on the front wall 11, the side wall 17, the rear wall 19, the furnace bottom 21, and the like below the auxiliary burner 13, so that the CO gas charged into the furnace 3 is directed toward the upper exhaust gas outlet 7. Since it contacts with the flame of the auxiliary burner 13 during the flow, the combustion is sufficiently performed. Further, since CO gas stays in the space below the auxiliary burner 13, the space in the furnace 3 is effectively used.

  Further, since the auxiliary burner 13 is installed only on the front wall 11, the CO gas is burned while accompanying the flame along the injection direction (indicated by arrow B) of the auxiliary burner 13, and the combustion gas Flows along the rear wall 19 side where the nose 5 is located, then rises along the rear wall 19, and then rises along the nose 5 again toward the front wall 11 to which the auxiliary burner 13 is attached.

Therefore, the residence time of the CO gas in the furnace 3 is ensured, and the CO gas can be sufficiently burned. When the auxiliary burner 13 is installed at the lower part of the front wall 11, the lower space of the furnace 3 can be used effectively. That is, the CO gas temporarily retained in the space is converted into CO gas by radiant heat from the flame of the auxiliary burner. It can be maintained at a high temperature, and combustion of the CO gas can be promoted.
The CO gas port 15 may be provided on a plurality of walls.

  The secondary air, which is the combustion air, is necessary to wrap the burner flame and stabilize the combustion, but the air register 37 weakens the swirl force of the secondary air, which is the combustion air, that is, reduces the swirl number. Thus, the flow velocity of the combustion air in the straight traveling direction can be increased.

The swirl number S is defined by the following equation (1) shown in the combustion engineering handbook (first edition, published by the Japan Society of Mechanical Engineers, July 25, 1995, page 158 of application).
S = Gφ / (G _x · r) (1)
Where Gφ is the angular momentum of the jet (circumferential angular momentum), G _x is the axial momentum of the jet (axial momentum), and r is the outlet diameter of the burner.

  When the swirl number is a strong swirl of 0.6, the CO gas concentration at the outlet 7 exceeds 500 ppm, but when the swirl is a weaker swirl, for example, 0.1 to 0.35, the CO at the outlet 7 It was found that the gas concentration was suppressed to about 60 ppm or less, and the CO gas concentration reduction effect was remarkable.

  When the flow velocity of the combustion air in the straight direction is large, the flow of CO gas to the rear wall 19 on the nose 5 side is promoted, and the amount of CO gas flowing to the rear wall 19 along the flame of the auxiliary burner 13 increases. The residence time in the furnace 3 is further secured. Therefore, the CO gas concentration at the outlet 7 can be further reduced.

  In the case where the CO gas port 15 is provided on the front wall 11 below the auxiliary combustion burner 13, there is a restriction in arrangement with the auxiliary combustion burner 13 compared to the case where it is provided on the bottom of the furnace, but in the ejection direction of the auxiliary combustion burner 13. The CO gas is injected along, and the CO gas is combusted while being entrained by the flame injected from the auxiliary combustion burner 13 having a large flow velocity in the straight traveling direction, and rises while flowing to the rear wall 19 side. The same effect as that obtained when the is provided at the furnace bottom can be obtained.

  FIG. 3 shows an example in which the CO gas port 15 is installed in the furnace bottom 21. In this case, in particular, since CO gas accumulates also in the furnace bottom 21, the space below the furnace 3 can be used more effectively. . In addition, since there is no apparatus or member such as a combustion apparatus in the furnace bottom 21, the opening area of the CO gas port 15 is not limited by the effective use of this portion even if the CO gas throughput is large. Can be made large.

  FIG. 2 shows the flow of CO gas (arrow C). The CO gas introduced from the furnace bottom 21 is caused to flow toward the rear wall 19 by the flow of auxiliary combustion fuel, combustion air, and exhaust gas from the auxiliary burner 13. While rising in the furnace 3, the combustion conditions such as oxygen from the combustion air, flame as the ignition source, high temperature atmosphere, etc. are ensured and hit the nose 5 in the upper part of the rear wall and circulate in the furnace 3. Flow to exit 7. Therefore, when the CO gas port 15 is provided in the furnace bottom 21, the CO gas flow path in the furnace 3 is ensured for a long time, so that it is possible to secure a further residence time of the CO gas, and the CO gas concentration at the outlet 7. Can be reduced.

In particular, when the CO gas port 15 is provided on the front wall 11 side of the furnace bottom 21, the CO gas contacts the flame from the auxiliary burner 13 immediately after being charged and flows to the rear wall 19 while mixing with the flame, A flow path from the front wall 11 side to the rear wall 19 side of the furnace bottom 21 can be secured. Therefore, the CO oxidation reaction time can be ensured to the maximum, and the combustion efficiency is improved.
In addition, as shown in FIG. 5, when the left and right positions (indicated by dotted lines D) of the auxiliary burner 13 and the CO gas port 15 in a plan view are aligned, the CO gas and the flame from the auxiliary burner 13 are more likely to come into contact with each other. Therefore, it is preferable.

  Further, the opening area of the CO gas port 15 is preferably set so that the CO gas charging speed into the furnace 3 does not become too fast. By setting the CO gas injection speed slower than the combustion air speed input from the auxiliary burner 13, the flame of the auxiliary burner 13 can easily accompany the CO gas. Therefore, the combustion air charging speed is generally set to about 20 m / s, the CO gas charging speed is 20 m / s or less, and the opening area of the CO gas port 15 is determined according to the processing amount of CO gas. The

  If the CO gas input speed to the furnace 3 is high, the flame of the auxiliary burner 13 is penetrated. Therefore, the residence time of the CO gas in the furnace 3 cannot be secured, but the CO gas input speed to the furnace 3 is 20 m / By setting an appropriate speed such as s or less, the CO gas collides with the flame of the auxiliary burner 13 in a form orthogonal to the combustion gas, and is sufficiently mixed with the combustion air so that combustion can be sufficiently performed. Reduction can be achieved.

Furthermore, if an after-air port 27 for injecting combustion air insufficient for combustion of fuel in the auxiliary burner 13 into the furnace 3 is installed above the auxiliary burner 13 on the front wall 11 and two-stage combustion is performed, the auxiliary combustion fuel NOx generated during combustion can be reduced.
That is, by reducing the air ratio of the auxiliary burner to less than 1.0 and supplying combustion air to the fuel, the CO gas is burned while performing slow combustion and suppressing the generation of thermal NOx, and the outlet 7 of the furnace 3 Then, the remaining combustion air in the amount of air necessary for combustion is supplied from the after air port 27 to the combustion gas that has risen in the furnace 3, and the CO and unburned components contained in the combustion gas are combusted. By this combustion, it is possible to achieve both suppression of NOx generation and reduction of CO concentration.

  FIG. 6 shows a plan view of a CO boiler as another embodiment of the present invention, and FIG. 7 shows a bottom view of the CO boiler of FIG. In the present embodiment, the case where the horizontal cross section of the furnace 3 is circular is shown, and the other components are the same as those in the first embodiment, and therefore the description of the same members is omitted. Moreover, the front view and side view of the CO boiler are generally the same as those in FIGS.

  When the horizontal cross section of the furnace 3 is circular, the auxiliary burner 13 is provided at a position facing the nose 5. In this embodiment, the same effects as those of the first embodiment are obtained. As in the first embodiment, the CO gas port 15 is provided on the front side of the furnace bottom 21, the left and right positions of the auxiliary burner 13 and the CO gas port 15 are aligned in a plan view, or the combustion air by the air register 37 is used. It goes without saying that the swirl force of the gas, the opening area of the CO gas port 15 may be changed as appropriate in order to adjust the flow rate of the CO gas, or the after-air port 27 may be installed to perform two-stage combustion.

8 shows a front view of a CO boiler 1 according to another embodiment of the present invention, FIG. 9 shows a side view of the CO boiler 1 of FIG. 8, and FIG. 10 shows a CO boiler 1 of FIG. The bottom view of is shown. In addition, in order to understand easily, the installation location of the refractory material 23 is shown in FIG.
In the present embodiment, the refractory material 23 is installed on a part of the side wall 19 of the furnace 3 and the lower portion of the front wall 11, and the other components are the same as those of the first embodiment, so the description of the same members is omitted. .

  The wall around the auxiliary burner 13 may have a fireproof structure, and the wall itself may be constituted by the fireproof material 23, or the wall may be provided with the fireproof material 23. The refractory material 23 is provided so as to surround the auxiliary burner 13. By installing the refractory material 23, heat dissipation from the wall can be suppressed, and a high temperature region can be formed in the peripheral portion of the flame of the auxiliary burner 13 in the furnace 3.

  The combustion air is preheated to 250 to 350 ° C. by an air preheater (not shown) and then supplied to the auxiliary burner 13. Moreover, since the refractory material 23 is installed from the lower end part of the front wall 11 or the side wall 17, the temperature fall of CO gas which flows in from the CO gas port 15 of the furnace bottom 21 can be prevented.

Examples of the refractory material 23 include refractory bricks and refractory mortars defined in JIS R 2001. For example, there are castable refractory materials (also called casters) and plastic refractories mainly composed of silica / alumina.
The refractory material 23 adjusts the construction range in the furnace 3 according to the CO gas-containing gas temperature and its components.

  Since the high temperature range can be maintained by such a fireproof structure, the temperature drop when the combustion air supplied from the auxiliary burner 13 is mixed with the fuel is small, and the oxidation reaction rate of CO is instantaneously accelerated. The temperature of 700 ° C. or higher can be secured, and since the CO gas speed is 700 ° C. even when the CO gas is mixed, the temperature does not drop and the oxidation reaction rate of CO increases. Can be greatly reduced.

  As in the first embodiment, the CO gas port 15 is provided on the front wall 11 side of the furnace bottom 21, the left and right positions of the auxiliary burner 13 and the CO gas port 15 are aligned in a plan view, or the air register 37 is used. It is possible to adjust the swirl force of the combustion air, change the opening area of the CO gas port 15 as appropriate in order to adjust the flow rate of the CO gas, or install the after air port 27 to perform two-stage combustion. Needless to say. Moreover, what is necessary is just to install the refractory material 23 in the side wall around the auxiliary burner 13 when the horizontal cross section of the furnace 3 is circular like Example 2. FIG.

  INDUSTRIAL APPLICABILITY According to the present invention, there is a possibility of use in a boiler that burns a gas containing high-temperature CO in various chemical plants such as an oil refinery plant.

1 CO boiler 3 furnace 5 nose 7 outlet 9 superheater 11 front wall 13 auxiliary burner 15 CO gas port 17 side wall 19 rear wall 21 furnace bottom 23 refractory material 25 ceiling 27 after air port 29 sleeve 31 fuel nozzle 33 primary air flow path 35 second Next air flow path 37 Air register 39 Wind box 41 Damper

Claims (6)

In a CO boiler equipped with a cylindrical furnace that burns by-product gas containing carbon monoxide generated from an oil refining facility,
An outlet provided on the upper side wall of the furnace for discharging exhaust gas generated by combustion;
A constricted portion provided on a side wall on the outlet portion side below the outlet portion, for narrowing a flow path of exhaust gas;
An auxiliary burner that is provided only on the side wall below the constricted portion and facing the constricted portion, and burns the auxiliary fuel with combustion air;
And a CO gas port provided below the auxiliary burner and configured to supply a gas containing carbon monoxide into a furnace.   The CO boiler according to claim 1, wherein the CO gas port is provided on a bottom wall of a furnace.   3. The CO boiler according to claim 2, wherein the CO gas port is provided on a bottom wall on a side wall side where an auxiliary burner is provided. A swirling device that forms a swirl force in the combustion air of the auxiliary burner is provided in the auxiliary burner,
The CO boiler according to any one of claims 1 to 3, wherein an adjustment device that adjusts the strength of the turning force by the turning device is provided in the turning device.   The CO boiler according to any one of claims 1 to 4, wherein a wall around the auxiliary burner is formed of a refractory material.   6. The after-air port according to claim 1, wherein an after-air port is provided above the auxiliary combustion burner to inject combustion air that is insufficient for combustion of fuel in the auxiliary combustion burner into the furnace. The described CO boiler.

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