JP3486023B2 - Combustion heating method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion heating method for forming two heat flux regions having different levels with respect to a heated pipe in a heating furnace, and more specifically, it is possible to downsize a reforming furnace. The present invention relates to a combustion heating method for a hydrocarbon steam reforming furnace.

[0002]

2. Description of the Related Art Conventionally, when it is attempted to form two heat flux regions having different temperature levels in a heating furnace in order to adapt to reaction conditions, it is necessary to precisely control the installation location of the combustion burner, the number of installations, the combustion method, etc. I could not form clearly,
We have responded by providing a partition wall in the heating furnace and dividing the room. In recent years, a heat storage type combustion device has been developed, but an integrated high-speed switching heat storage type, which is installed on the furnace wall so as to face each other and switches combustion at high speed, makes the furnace temperature uniform. However, it was not possible to clearly form two heat flux regions having different temperature levels in the heating furnace. On the other hand, the steam reforming of hydrocarbons mainly includes a steam reforming reaction step represented by the following formula, a desulfurization step as a pre-step for removing the sulfur content in the hydrocarbon as necessary, and CO as steam as a post-step. a metamorphic step of converting the H ₂ and CO ₂ are reacted, the pressure swing adsorption (PSA), membrane hydrogen purification step separation or the like, CO ₂ cleaning process for removing CO _2, CO
And a methanation step to convert CO ₂ to methane is added. C _m H _n + oH ₂ O → pCO + qCO ₂ + rH ₂ + sCH ₄ +
zC Conventionally, a steam reforming furnace used in a steam reforming reaction step has a reforming tube filled with a catalyst and a combustion burner, but the temperature inside the furnace is non-uniform and there is a tendency for partial heating.
In addition, from the inlet of the reforming pipe to the central portion, a region called a reforming zone that requires uniform high heat flux heating accompanied by endothermic reaction and from the central portion to the outlet thereof, shift reaction zone (CO + H ₂ O → CO ₂ + H ₂ ) There are two different heat flux areas called high heat flux heating areas that do not require high heat flux heating. For this reason, in the conventional combustion burner method, even if the above heat flux area is attempted to be formed, it is not uniform as shown in FIG. Since the temperature distribution is uniform (heat flux distribution), the reforming tube has to be long in order to recover heat, and the reforming furnace has been enlarged. In addition, when the reaction conditions are changed, the heating amount corresponding thereto cannot be changed sufficiently, which causes a decrease in yield and the like.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide two heat flux regions having different levels suitable for reaction conditions with respect to a pipe to be heated in a furnace space of a heating furnace or a reforming furnace. The present invention provides a combustion heating method capable of improving thermal efficiency and downsizing a heating furnace or the like, particularly in a steam reforming furnace for hydrocarbons, by forming the heating furnace.

Under these circumstances, as a result of earnest studies by the present inventor, as a result, in a hydrocarbon steam reforming furnace, a heat storage type heat exchanger integrated combustion device is used, and a heated pipe (reforming pipe) is used. ), It is found that the efficiency of heat recovery is improved and the reforming pipe can be shortened by forming two heat flux regions having different levels, and therefore the reforming furnace can be remarkably downsized, and the present invention is realized. It came to completion. That is, the present invention is a heat storage type heat exchanger integrated combustion device for supplying combustion air to the burner and discharging combustion gas from the burner through the heat storage exchanger, installed in the furnace wall in one or more pairs, By adjusting the supplied fuel, in the heating furnace internal space, with respect to the pipeline to be heated, the high heat flux region is from the pipeline inlet portion to the central portion of the pipeline, and from the central portion of the pipeline to the pipeline. It is intended to provide a combustion heating method characterized in that two heat flux regions having different levels, which are low temperature flux regions, are formed up to the outlet of the passage.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A heat storage type heat exchanger integrated combustion apparatus used in a combustion heating method of the present invention is designed to supply combustion air to a burner and discharge combustion gas from the burner through the heat storage type exchanger. There is no particular limitation as long as it is a combustion device that has a heat storage type heat exchanger for performing the operation and is integrated with it, and for example, the one disclosed in JP-A-7-83585 can be used.

That is, FIG. 1 shows an example of the heat storage type heat exchanger integrated combustion apparatus, and FIG. 2 shows an example of the heat storage type heat exchanger.
The heat storage type heat exchanger 30 is connected to the combustion air system (low temperature fluid flow path) 33 and the combustion exhaust gas system (high temperature fluid flow path) 34 of the burner system, and is supplied via the heat storage type heat exchanger 30 for combustion. While burning the burner 35 with air, the combustion exhaust gas is taken out of the furnace 37 and the heat storage type heat exchanger 30 is used.
The combustion air is preheated to a high temperature near the temperature of the combustion exhaust gas and supplied by the waste heat of the combustion exhaust gas. This furnace comprises a furnace body 38 and at least two pairs of burners 35 installed therein. The burner 35 is not particularly limited in its structure and combustion method, but the combustion air is supplied through the heat storage type heat exchanger 30. Further, the combustion exhaust gas in the furnace 37 is taken out by a high temperature fluid means installed in the furnace body 38, for example, an exhaust pipe 36 connected to the combustion exhaust gas system 34. Incidentally, reference numeral 31 in the drawing
Is a fan for supplying combustion air, and 32 is a fan for discharging combustion exhaust gas. Although not shown, the burner 35 is usually provided with auxiliary equipment such as ignition means and pilot burner.

As the heat storage type heat exchanger 30 used in such a heat storage type heat exchanger integrated combustion apparatus, for example, N (N = n + 1, where n is a positive even number of 2 or more in the circumferential direction and always contains a fluid). The number of chambers that flow.) A heat storage body that allows fluid to pass axially through each of the chambers that are evenly divided into chambers, and a fluid having a temperature difference that is connected to both open ends of the heat storage body and that has a temperature difference 2 A double-piped inlet / outlet means partitioned by an annular partition into a low temperature fluid chamber connected to one low temperature fluid system and a high temperature fluid chamber connected to the other high temperature fluid system,
The low-temperature fluid communication hole and the high temperature, which are respectively interposed between the heat storage body and the inlet / outlet means to shut off between the heat storage body and the inlet / outlet means, and communicate the low-temperature fluid chamber and the heat storage body with each other. N / 2 number of high temperature fluid communication holes for communicating the fluid chambers with the heat storage body are alternately arranged,
The switching means is configured to rotate continuously or intermittently to sequentially connect the high temperature fluid chamber and the low temperature fluid chamber of the inlet / outlet means to one of the chambers of the heat storage body partitioned into N chambers, and the switching means. The high temperature fluid communication hole and the low temperature fluid communication hole are arranged at an interval of an angle α represented by Formula (1),

[0008]

[Equation 4]

(Wherein β ₁ is a central angle circumscribed from the rotation center O of the switching portion to the communication hole for high temperature fluid, and β ₂ is a central angle circumscribed from the rotation center O of the switching portion to the communication hole for low temperature fluid. Further, the size of the communication hole for low temperature fluid and the size of the communication hole for high temperature fluid can be expressed by the formula (2).

[0010]

[Equation 5]

Satisfactory is preferable. Where the angle α
Is preferably set to α = 360 ° / n. still,
In the present specification, the term “the chamber in which the heat storage body is divided” refers not only to the case where the heat storage body itself is partitioned into a plurality of chambers but also to the case where the heat storage body is substantially divided into a plurality of chambers by the distribution chamber. Is included.

Further, the heat storage type heat exchanger (1) used in the present invention has N (where N = n + 1, n is a positive even number of 2 or more, and indicates the number of chambers through which the fluid always flows) chambers. A total number of chambers Z (where Z = a · N, a is a positive integer indicating the number of units) is defined as one unit, and a plurality of partitioned chambers are formed in the heat storage body. An a-chamber that does not flow fluid is formed between the N chamber of one unit and the N chamber of another unit, and the arrangement angle α between the high temperature fluid communication hole and the low temperature fluid communication hole Is equation (4)
Have a relationship of

[0013]

[Equation 6]

The size of the communication hole for the high temperature fluid and the size of the communication hole for the low temperature fluid are expressed by the equation (5).

[0015]

[Equation 7]

Those satisfying are more preferable.

Further, the heat storage type heat exchanger (2) used in the present invention has N (N = n + 2, where n is a positive integer of 2 or more) in the circumferential direction and is the number of chambers through which the fluid always flows. ) A heat storage body that is evenly divided into chambers and through which fluid can pass in the axial direction, and one of two flow passages that are connected to both open ends of the heat storage body and that flow the fluid having a temperature difference. A double tubular inlet / outlet means partitioned by an annular partition into a low temperature fluid chamber connected to the low temperature fluid system and a high temperature fluid chamber connected to the other high temperature fluid system, and between the heat storage body and the inlet / outlet means, respectively. A low-temperature fluid communication hole for communicating between the low-temperature fluid chamber and the heat storage medium and a high-temperature fluid communication hole for communicating between the high-temperature fluid chamber and the heat storage medium while intervening between the heat storage medium and the inlet / outlet means. Are arranged at intervals of the angle C represented by the formula (3).

[0018]

[Equation 8]

Further, it is constituted by a switching means which rotates continuously or intermittently to sequentially connect the high temperature fluid chamber and the low temperature fluid chamber of the inlet / outlet means to one of the heat storage chambers divided into N chambers. A thing is also used suitably.

In this heat storage type heat exchanger (2), N (here, N = n + 2, n is a positive integer of 2 or more, which indicates the number of chambers through which the fluid always flows) is defined as one unit. Number Z
(Where Z = a · N, where a is a positive integer indicating the number of units), a plurality of united chambers are formed in the heat storage body, and the space between the high temperature fluid communication hole and the low temperature fluid communication hole is formed. To the formula (6)

[0021]

[Equation 9]

It is preferable that the interval of the angle C represented by is set.

That is, in FIG. 2, the low temperature fluid chamber 6a and the high temperature fluid chamber 6b of the inlet / outlet means 6 store heat in the distribution chamber 2 via the low temperature fluid communication hole 5 and the high temperature fluid communication hole 4 of the switching means 3, respectively. It communicates with different rooms and compartments of body 1,
Two kinds of fluids having different temperatures are flowed in the heat storage body without intersecting each other. At this time, in the case of the heat storage type heat exchanger (1), a high-temperature fluid such as a combustion gas flows in the a / n / 2 chambers of the heat storage body partitioned into the a / N chambers, and the other a / n / 2 chambers. A low temperature fluid, for example, combustion air flows into the chamber, and the remaining chamber a is an empty chamber in which no fluid flows because it is not connected to any of the flow paths.
Therefore, if the chamber / compartment communicating with the low temperature fluid chamber 6a and the chamber / compartment communicating with the high temperature fluid chamber 6b of the entrance / exit means 6 are sequentially changed by the operation of the switching means 3, the high temperature fluid and the low temperature fluid are separated from each other. It will flow through the same room / compartment of the heat storage body at different times. For example, a low-temperature fluid such as combustion air will flow into the heat storage body after flowing a high-temperature fluid such as combustion exhaust gas, and the heat of the heat storage body heated by the passage of the high-temperature fluid will be taken by the low-temperature fluid, resulting in heat exchange. To do.

The switching of the flow of the fluid is such that the communication hole 4 for the high temperature fluid is advanced in the rotational direction than the communication hole 5 for the low temperature fluid, and the communication hole 5 for the low temperature fluid and the communication for the high temperature fluid are communicated in the same chamber. Since the holes 4 and the holes 4 do not exist at the same time, and the holes 4 sequentially move from the front communication hole to the front chamber one by one, the communication holes 4 for the high-temperature fluid in the front row in the chamber next to the empty chamber are stored in the heat storage body 1.
Of the front, that is, the low-temperature fluid communication hole 5 and the other high-temperature fluid communication holes 4 and low-temperature fluid communication holes 5 that are located behind the same even if they are in the empty chamber still exist in the same chamber / compartment and are switched. Does not start. And, the communication hole 4 for high temperature fluid in the front row
The room that had been in communication with the high-temperature fluid communication hole 4 in the front row until now, after completely moving to the front room / compartment that was empty
The compartment becomes an empty room, and the next low temperature communication hole 5 approaches there. At this time, the communication hole 5 for the low temperature fluid is
Since the two chambers / compartments of the compartment and the new room / compartment (vacant chamber) are simultaneously straddled and the two chambers / compartments are switched while supplying the fluid at the same time, the flow of the fluid is not interrupted.
Moreover, since the communication hole 4 for the high temperature fluid in the front row is located in the chamber / compartment one before the chamber / compartment where the communication hole 5 for the low temperature fluid is approaching, the high temperature fluid and the low temperature fluid are mixed in the same compartment. It doesn't fit.

In the combustion heating method of the present invention, one or a plurality of heat storage type heat exchanger-integrated combustion devices are installed on the furnace wall, and one of the one or a plurality of pairs is to be heated. It does not matter how it is installed if it is installed at the entrance side. For example, in FIGS. 4A and 4B, 2
FIG. 4 (c) and FIG. 4 (d) show two pairs of two, and FIG. 4 (e) shows three pairs of one. In order to form two heat flux regions of different levels for the heated pipeline in the heating furnace internal space as described below, consider the capacity of the heating furnace or reforming furnace, the capacity of the heated object, the reaction conditions, etc. At the same time, the number of heat-storage-type heat exchanger integrated combustion devices, the place of arrangement, and the like may be appropriately selected. 5 (a) and 5 (b) are views seen from the inlet side of the pipe to be heated, FIG. 5 (a) shows a box-type heating furnace (b).
Indicates a cylindrical heating furnace.

The type of the heating furnace is not particularly limited, and examples thereof include a tube heating furnace, a hydrocarbon steam reforming furnace, a steel furnace, and the like, of which the hydrocarbon steam reforming furnace is preferable. As such a steam reforming furnace for hydrocarbons (hereinafter, also simply referred to as "reforming furnace"), for example, several to several hundred reforming tubes filled with a nickel-based catalyst are arranged, and a heat storage heat exchanger is provided. It is preferable that 2 to 20 integrated combustion devices are arranged.

In the combustion heating method of the present invention, it is necessary to form two heat flux regions having different levels with respect to the pipe to be heated in the space inside the heating furnace, and the heat pipe region from the inlet of the pipe to be heated The high heat flux region extends to the central portion, and the low heat flux region extends from the central portion of the pipeline to the outlet portion. FIG. 6 shows an example of forming two heat flux regions having different levels in a hydrocarbon steam reforming furnace. In FIG. 6, the broken line shows the ideal heat flux distribution, and the solid line shows the actual heat flux distribution. Therefore, a transition region from the high temperature flux region to the low temperature flux region may exist. Further, as shown in FIG. 7, each heat flux region can be changed horizontally or vertically depending on operating conditions (reaction conditions) and the like. Therefore, the central portion does not indicate the center of the heated pipe, but the center ±
A part having a width of total pipe length × 0.2 is shown. In the case of steam reforming of hydrocarbons, the central portion is the end portion of the reforming reaction zone and the start portion of the shift reaction. Examples of the case where the high temperature heat flux region is shifted to the right include a case where the raw material flow rate is increased and a case where the catalyst deterioration is taken into consideration. Also,
It is preferable to take a uniform heat flux in each of the high-temperature heat flux region and the low-temperature heat flux region, but each is ± 2 of the central heat flux value.
It may be fluctuated with a heat flux width of 0%.

In the combustion heating method of the present invention, a high heat flux region is provided from the heated pipe inlet to the center of the pipe, and a low heat flux region is provided from the pipe to the outlet of the pipe. Therefore, 30 to 100% by weight, preferably 50 to 10% by weight of the total amount of fuel supplied to the heating-type heat exchanger integrated combustion apparatus installed on the inlet side of the heating furnace of the heating furnace.
It is preferable to supply 0% by weight because two different heat flux regions can be clearly formed and heat recovery can be efficiently performed.

Therefore, as shown in FIG. 4 (c), in the reforming furnace in which four heat storage type heat exchanger integrated combustion devices are installed, the supply heat quantity ratio is Q ₁ (= Q ₂ ): Q ₃ (= Q ₄ ) = 50:
Adjust in the range of 50 to 100: 0, and in the box-type reforming furnace, the furnace inlet temperature is 1200 to 1400 ° C (heat flux 65,000).
0-80,000 kcal / m ² · h), furnace outlet temperature 100
0 to 1100 ° C (heat flux 25,000 to 40,000 kc
al / m ² · h), cylindrical reforming furnace with inlet temperature 1300-
1500 ° C (heat flux 40,000-55,000 kcal /
m ² · h), and the furnace outlet temperature is preferably 1100 to 1200 ° C (heat flux 16,000 to 30,000 kcal / m ² · h).

As described above, when the flow paths of the high temperature combustion gas and the low temperature air are switched, the flow of the fluid is not interrupted and the stable supply or discharge of the fluid is possible, so that the flame is stable and the high temperature combustion is performed. Due to the high temperature combustion by use air, it is possible to make the temperature uniform in a specific region. Therefore, by using a plurality of the combustion devices and independently supplying a specific amount of fuel, two heat flux regions having different levels can be formed in the space inside the furnace. Thus, when two reactions having different required heat amounts occur in the reforming tube such as a hydrocarbon steam reforming furnace, a heat flux region suitable for the two reactions can be formed, which is particularly preferable.

[0031]

EFFECTS OF THE INVENTION Since the heat in the furnace can be efficiently recovered, it is not necessary to install a residual heat pipe or the like in the convection section as in the conventional case, and the capital investment can be reduced. By adjusting the amount of heat recovered from the combustion exhaust gas for generating steam and the amount of heat passing through the heat storage body, it is possible to support flexible design and operation as thermal self-sufficiency. Especially in a hydrocarbon steam reforming furnace, the amount of heat can be effectively supplied to the object to be heated by two temperature regions of different levels,
The reforming furnace can be downsized. In addition, since the temperature can be made uniform in the high temperature heat flux region in the reforming furnace, the possibility of partial overheating of the reforming tube is reduced, which reduces S / C (steam / carbon) and avoids carbon precipitation. Also, the life of the tube can be extended.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a heat storage type heat exchanger integrated combustion device used in the present invention.

FIG. 2 is an explanatory view showing a heat storage type heat exchanger used in the heat storage type heat exchanger integrated combustion device.

FIG. 3 is an explanatory diagram showing a relationship between a communication hole for high temperature fluid and a communication hole for low temperature fluid.

FIG. 4 is a sectional view showing an example of a heating furnace used in the present invention.

FIG. 5 is a side view showing an example of a heating furnace used in the present invention.

FIG. 6 is a diagram showing a heat flux distribution in a hydrocarbon steam reforming furnace.

FIG. 7 is a diagram showing an aspect of heat flux distribution.

FIG. 8 is a diagram showing a heat flux distribution of a heating furnace using a conventional combustion burner system.

[Explanation of symbols]

7 Heated tube 8 flames 30 heat storage type heat exchanger 39 Combustion device with integrated heat storage heat exchanger 40 heating furnace

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiko Hirashiro 6-6, Kojimachi, Chiyoda-ku, Tokyo Cosmo Engineering Co., Ltd. (72) Eiichi Akechi 2-53, Shirute, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Furnace Kogyo Co., Ltd. (72) Inventor Toshiaki Hasegawa 2-53, Shirate, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Furnace Industry Co., Ltd. (56) Reference JP-A-5-118764 (JP, A) JP-A-59 -74409 (JP, A) JP-A-7-83585 (JP, A) Actually developed 59-142651 (JP, U) Actually developed 56-141736 (JP, U) (58) Fields investigated (Int.Cl) . ⁷ , DB name) F28D 17/04

Claims (5)

(57) [Claims] 1. A heat storage type heat exchanger integrated combustion device for supplying combustion air to a burner and discharging combustion gas from the burner through the heat storage exchanger is installed on the furnace wall in one or more pairs, By adjusting the supplied fuel, in the heating furnace internal space, with respect to the pipeline to be heated, the high heat flux region is from the pipeline inlet portion to the central portion of the pipeline, and from the central portion of the pipeline to the pipeline. A combustion heating method characterized in that two heat flux regions having different levels, which are low temperature flux regions, are formed up to the outlet of the passage. 2. 50 to 100% by weight of the total fuel amount in the heat storage type heat exchanger integrated combustion device installed on the inlet side of the heated pipeline.
The combustion heating method according to claim 1, further comprising: 3. The combustion heating method according to claim 1, wherein the heating furnace is a hydrocarbon steam reforming furnace having a reforming tube filled with a catalyst into which hydrocarbon and steam flow. 4. The heat storage type heat exchanger of the heat storage type heat exchanger integrated combustion apparatus has N (N = n + 1) in the circumferential direction, where n is a positive even number of 2 or more and is the number of chambers through which the fluid always flows. A heat storage body that allows a fluid to pass in the axial direction through each of the chambers that are evenly divided into chambers, and a flow path of two systems that are connected to both open ends of the heat storage body and flow the fluid having a temperature difference. A double tubular inlet / outlet means partitioned by an annular partition wall into a low temperature fluid chamber connected to one low temperature fluid system and a high temperature fluid chamber connected to the other high temperature fluid system, the heat storage body and the inlet / outlet means. While interposing between the heat storage body and the inlet / outlet means respectively, the low temperature fluid communication hole for communicating the low temperature fluid chamber and the heat storage body, and the high temperature fluid chamber and the heat storage body. Alternately with the high-temperature fluid communication holes for communication
And / or switching means for arranging every two of them and rotating them continuously or intermittently so that the high temperature fluid chamber and the low temperature fluid chamber of the inlet / outlet means are sequentially communicated with any one of the chambers of the heat storage body divided into N chambers. And the communication hole for the high temperature fluid and the communication hole for the low temperature fluid of the switching means are represented by the mathematical expression (1).
Are arranged at intervals of (In the formula, β ₁ indicates a central angle circumscribing the rotation center O of the switching portion to the communication hole for high temperature fluid, and β ₂ indicates the rotation center O of the switching portion.
Shows the central angle circumscribing the through hole for the low temperature fluid. ) Further, the size of the communication hole for the low temperature fluid and the communication hole for the high temperature fluid is expressed by the following equation (2). The combustion heating method according to any one of claims 1 to 3, which is satisfied. 5. The heat storage type heat exchanger of the heat storage type heat exchanger integrated combustion apparatus has N (N = n + 2) in the circumferential direction, where n is a positive integer of 2 or more and is the number of chambers through which the fluid always flows. .) A heat storage body that is evenly divided into chambers and allows fluid to pass through each chamber in the axial direction, and one of two flow paths that are connected to both open ends of the heat storage body and flow the fluid having a temperature difference. Of the low temperature fluid chamber connected to the low temperature fluid system and the high temperature fluid chamber connected to the other high temperature fluid system, and the double space-shaped inlet / outlet means partitioned by the annular partition wall, the heat storage body and the inlet / outlet means. While interposing between the heat storage body and the inlet / outlet means respectively, the low temperature fluid communication hole for communicating the low temperature fluid chamber and the heat storage body, and the high temperature fluid chamber and the heat storage body. The communication hole for the high temperature fluid to be communicated is the mathematical formula (3).
Are arranged at intervals of an angle C represented by And a switching means that rotates continuously or intermittently to sequentially connect the high temperature fluid chamber and the low temperature fluid chamber of the inlet / outlet means to one of the heat storage chambers divided into N chambers. Item 4. The combustion heating method according to any one of Items 1 to 3.